- Email: [email protected]
Repeated CT scans in trauma transfers: An analysis of indications, radiation dose exposure, and costs
Accepted Manuscript Title: Repeated CT scans in Trauma Transfers: An Analysis of Indications, Radiation Dose Exposure, and Costs Author: Ricarda Hinzpeter Kai Sprengel Guido A. Wanner Peter Mildenberger Hatem Alkadhi PII: DOI: Reference:
S0720-048X(17)30011-6 http://dx.doi.org/doi:10.1016/j.ejrad.2017.01.007 EURR 7695
To appear in:
European Journal of Radiology
Received date: Revised date: Accepted date:
7-7-2016 1-1-2017 5-1-2017
Please cite this article as: Hinzpeter Ricarda, Sprengel Kai, Wanner Guido A, Mildenberger Peter, Alkadhi Hatem.Repeated CT scans in Trauma Transfers: An Analysis of Indications, Radiation Dose Exposure, and Costs.European Journal of Radiology http://dx.doi.org/10.1016/j.ejrad.2017.01.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Repeated CT scans in Trauma Transfers: An Analysis of Indications, Radiation Dose Exposure, and Costs
Ricarda Hinzpeter1, MD, Kai Sprengel2, MD, Guido A. Wanner2,3, MD, 4Peter Mildenberger, MD, Hatem Alkadhi1, MD, MPH, EBCR
1
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland
2
Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Switzerland 3
Department of General Surgery, Schwarzwald-Baar Klinikum, University of Freiburg, Germany
4
Department of Diagnostic and Interventional Radiology, University Hospital of Mainz, Germany
1. Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland Ricarda Hinzpeter, [email protected] Hatem Alkadhi, [email protected]
2. Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland Kai Sprengel, [email protected]
1
3. Department of General Surgery, Schwarzwald-Baar Klinikum, University of Freiburg, Klinikstr. 11, D-78052 Villingen-Schwenningen, Germany Guido A. Wanner, [email protected]
4. Department of Diagnostic and Interventional Radiology, University Hospital of Mainz, Langenbeckstr. 1, D-55131 Mainz, Germany Peter Mildenberger, [email protected]
Corresponding author: Hatem Alkadhi, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland, Tel. +41 (0)44 255 3662, Fax: +41 (0)44 255 4443, email: [email protected]
Highlights:
Repetition of CT in trauma patients occurs relatively often.
Repetition of CT is mainly caused by inadequate image data transfer.
Potentially preventable CT examinations add radiation dose to patients.
Repeated CT is associated with excess costs to the health care system.
2
Abstract Objectives: To identify the number of CT scans repeated in acute trauma patients receiving imaging before being referred to a trauma center, to define indications, and to assess radiation doses and costs of repeated CT. Methods: This retrospective study included all adult trauma patients transferred from other hospitals to a Level-I trauma center during 2014. Indications for repeated CT scans were categorized into: inadequate CT image data transfer, poor image quality, repetition of head CT after head injury together with completion to whole-body CT (WBCT), and follow-up of injury known from previous CT. Radiation doses from repeated CT were determined; costs were calculated using a nation-wide fee schedule. Results: Within one year, 85/298 (28.5%) trauma patients were transferred from another hospital because of severe head injury (n=45,53%) and major body trauma (n=23;27%) not manageable in the referring hospital, repatriation from a foreign country (n=14;16.5%), and no ICU-capacity (n=3;3.5%). Of these 85 patients, 74 (87%) had repeated CT in our center because of inadequate CT data transfer (n=29;39%), repetition of head CT with completion to WBCT (n=24;32.5%), and follow-up of known injury (n=21;28.5%). None occurred because of poor image quality. Cumulative dose length product (DLP) and annual costs of potential preventable, repeated CT (inadequate data transfer) was 631mSv (81’304mGy*cm) and 35’233€, respectively. Conclusion: A considerable number of transferred trauma patients undergo potentially preventable, repeated CT, adding radiation dose to patients and costs to the health care system. Abbreviations WBCT
whole-body computed tomography
DLP
dose-length product
Key words: imaging, trauma, radiation exposure, health care costs 3
Introduction Computed tomography (CT) is the modality of choice for the early imaging work-up of severely injured trauma patients [1-4]. This is mainly due to fast image acquisition, robustness, accuracy and wide availability. Nevertheless, CT scans have the disadvantage of being associated with potentially harmful radiation exposure to the often relatively young trauma population [5-7]. The Swiss government announced in 2011 a total of 12 authorized centers for treatment of severely injured trauma patients, based on various criteria including the availability of 24/7 trauma patient care including radiology services. In addition, these trauma centers have to guarantee a standardized and structured data acquisition to a registry which records the quality of processes and results. While these trauma centers are intended to deliver the primary care of severely injured trauma patients, still many injured patients are admitted and often are radiologically evaluated in other, mostly regional hospitals and are then being transferred to a Level-I trauma center [8]. Reasons for transfers of these patients to a trauma center may be an initial underestimation of the true trauma load, patients who become hemodynamically unstable or had a trauma which is not manageable in the referring hospital [9, 10]. It was observed that transferred trauma patients frequently had foregoing initial CT examinations performed at the referring institution, but many of them were rescanned based on indications of our trauma surgeons. This is in line with some recent literature from the U.S. indicating that repeated CT imaging in trauma patients occurs relatively often, and indications for duplicate CT imaging differ depending on the institution and referring networks [8-13]. Potentially unnecessary repeated CT scans, however, expose trauma patients to additional ionizing radiation and increase resource use [14]. It was sought to identify the number of CT scans repeated in trauma patients receiving a radiologic work-up before being referred to our trauma center, to define indications for 4
repeated CT scans including imaging findings, and to assess associated radiation doses and costs.
5
Materials and Methods Study Population This study was performed at our Level-I trauma center in Switzerland between January and December 2014. During this one-year period 298 trauma patients were identified (mean age 52±22 years), being either directly admitted to our trauma center (213/298, 72%) or being transferred after secondary survey (85/298, 29%) (Figure 1). Reasons for transfer to our trauma center were severe head injury (n=45, 53%) and major body trauma (n=23, 27%) being not manageable in the referring hospital, repatriation from a foreign country (n=14, 17%), and lack of local intensive care unit (ICU) capacity (n=3, 4%). All patients included were recorded in the trauma registry hosted by the German Association for Trauma Surgery (www.traumaregister-dgu.de). According to this trauma registry only patients who are admitted through the emergency room and who are in need of intensive care are recorded in the database. In the present study only those adult trauma patients were included who got a CT evaluation at our hospital’s emergency department. Repetition of CT was defined as CT examination in the referring hospital and at our trauma center within 24 hours of trauma. Patients who had been evaluated and underwent one or more CT examinations in the context of acute trauma and those who were directly referred and who had no foregoing CT were compared regarding age, sex, trauma mechanism, injury severity score (ISS) and time from trauma to our trauma center (Table 1) [15]. These data were taken from the electronic records of patients in all involved hospitals. This retrospective study had local ethics committee approval; written informed consent requirement was waived.
Data Collection and Categorization
6
A thorough database search was made to identify the trauma mechanism, the severity of trauma indicated by the ISS and the indications for repeated CT examinations in our trauma center in patients who were transferred from a regional hospital. These indications were categorized as previously shown [11, 12]: inadequate CT image data transfer, poor CT image quality, repetition of head CT after head injury together with completion to WBCT, and follow-up of trauma injury known from previous CT in the regional hospital. The four body regions comprising a whole-body CT were evaluated: head, neck/cervical spine, chest and abdomen. Imaging data from referring hospitals were either sent electronically or were provided per data carrier (CD). For electronic transfer of imaging studies we used the MedicalConnector-network (H-Net AG, Zurich, Switzerland). This network ensures a flexible and encrypted transmission of medical data in the required data format.
Image quality of CT in referring hospitals First, all CT examinations performed in the referring hospital (and which were repeated in our trauma center) were reviewed regarding image quality by one blinded radiologist (with 13 years of experience in imaging). Image quality was categorized in a dichotomic way: diagnostic or non-diagnostic because of inadequate image quality.
CT examination All CT examinations in our center were performed using a 128-slice CT scanner (SOMATOM Definition Flash; Siemens Healthcare) located adjacent to the emergency room and included non-enhanced CT of the head, non-enhanced CT of the cervical spine and contrast-enhanced CT of the chest and abdomen. The contrast media protocol aimed at an arterio-venous phase for the chest and a portal-venous phase of the abdomen. For this, a total of 100 ml non-ionic iodinated contrast material (Iopromidum, Ultravist 300, 300mg/ml, 7
Bayer, Leverkusen, Germany) with a flow rate of 4 ml/sec was injected through an antecubital vein. Contrast agent application was controlled by bolus tracking in the descending aorta (attenuation threshold 120 HU at 120 kVp). Image acquisition started 5 sec and 40 sec after the signal density reached the predefined threshold. All CT scans in our department were performed with our institutional standard protocol settings using a tube voltage of 120kVp and with quality reference tube current-time products adjusted to the respective body region (head: 320mAs, cervical spine: 200mAs, chest and abdomen: 150mAs). Images were reconstructed and reformatted with slice thicknesses ranging from 1-2mm using sinogram-affirmed iterative reconstruction at a strength level of 3.
Imaging findings in repeated CT All repeated CT examinations in our hospital were analyzed regarding their imaging findings and were compared to those from the previous CT examinations in the referring hospitals. Imaging findings were categorized by indications for repeated CT and by each body region (head, C-spine/neck, chest, and abdomen) as follows: no new imaging findings related to trauma, stable trauma injury known from previous CT, progression of trauma injury known from previous CT, progression of trauma injury requiring intervention and/or surgery.
Radiation Dose Estimation The radiation exposure per CT scan was collected from the radiation dose reports automatically generated by the scanner. The metric dose length product (DLP, in mGy*cm) was used as the most suitable radiation dose parameter for such studies, as previously shown [12]. Effective radiation doses (in mSv) were estimated using conversion coefficients (k) for adults specific to the respective body regions at 120kVp reported in the 2007
8
Recommendations of the International Commission on Radiological Protection (ICRP [16]) using the following equation : ED ≈ k* DLP.
Cost Calculation A nation-wide fee schedule was used to obtain the hospital charges for each repeated CT scan. Costs of head, c-spine/neck, and chest/abdomen CT were assessed separately. Detailed information about the fee schedule is provided in Table 2. These costs in trauma patients in the emergency department equal those for outpatients plus an additional fee for the required intensive care.
Statistical Methods Quantitative variables were expressed as means ± standard deviations for normally distributed, and as medians ± interquartile ranges for non-normally distributed values. Percentages were used for categorical parameters. Normality was tested using the ShapiroWilk test. Student’s t-test for independent samples was used for differences between patient groups regarding age. Mann-Whitney U test was used to test for differences between patient groups regarding the injury severity score (ISS). The 2 test was used for differences between patient groups regarding sex and trauma mechanism. The Levene’s test was conducted for differences between patient groups regarding the time from trauma until arrival at our trauma center. For economic calculations we used the exchange rate from January 8th 2016 (1 CHF = 0.9207 €). Data were analyzed using commercially available software (IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp). The level of significance was set at a two-tailed p-value < 0.05.
9
Results Study Population Seventy-four of the 85 referred patients (87%) underwent repeated CT, whereas 11/85 patients (13%) had no repeated CT examination (Figure 2). There were no significant differences between patients with repeated CT as compared to those without repeated CT regarding sex (p=0.43), age (p=0.08) and ISS (p=0.58). Fall and motor vehicle accidents were the mechanisms responsible for most traumas in both patient populations, with no differences between groups (p=0.98). The mean time from trauma to admission to our center was significantly shorter in patients without repeated CT (median 1.5 ± 3 hours) as compared to those with repeated CT (median 3.0 ± 19 hours, p<0.001), which was mainly due to their stay in the referring hospitals (Table 1).
Indications for repeated CT Indications for repeated CT scans included inadequate CT image data transfer (n=29, 39%), repetition of head CT after known head injury together with completion to WBCT (n=24, 32.5%) and follow-up of known trauma injury from previous CT (n=21, 28.5%). Image quality assessment showed that none of the examinations was repeated in our hospital because of poor image quality of the CT performed in the referring hospital.
Imaging findings categorized by indications for repeated CT Detailed information about the imaging findings in repeated CT in each category and for each body region is provided in Table 3. Inadequate CT image data transfer: Of the 29 patients in whom CT was repeated because of inadequate CT image data transfer, 5 (17%) with head injury and 17 (59%) with injury of the chest and abdomen showed a progression of traumatic injury requiring immediate intervention/surgery. 10
Repetition of head CT and completion to WBCT: Of the 24 patients in whom head CT was repeated and WBCT was completed, 4 (17%) with head injury and 2 (8%) with injury of chest and abdomen showed a progression of traumatic injury requiring immediate intervention/surgery. Follow-up of known trauma injury: Of the 21 patients in whom CT was repeated because of known injury 3 (14%) head and 6/21 (29%) chest and abdomen injuries showed a progression requiring immediate intervention/surgery.
Radiation Dose Estimation The additional estimated effective radiation dose of repeated CT scans separately assessed for the different indications ranged from 2-3mSv (DLP: 1050-1580 mGy*cm) for head CT, from 0.5-1mSv (DLP: 100-200 mGy*cm) for the C-spine/neck, and from 8-18mSv (DLP: 540-1200 mGy*cm) for the chest and abdomen per patient (Table 4). The estimated effective radiation dose of repeated CT scans separately determined for each body region were as follows: DLP head: 1411 mGy*cm ± 236 mGy*cm; DLP Cspine/neck: 296 mGy*cm ± 55 mGy*cm; DLP chest and abdomen: 1366 mGy*cm ± 549 mGy*cm. Inadequate CT image data transfer and poor CT image quality were defined as potentially preventable radiologic work-up and showed a peak of additional radiation dose between 20-30mSv (DLP:1340-2015 mGy*cm) per patient and consisted mainly of chest/abdomen and head CT examinations. In distinction, clinically indicated CT examinations (follow-up of known trauma injury from foregoing CT, repetition of head CT after known head injury with completion to WBCT) showed a peak of additional dose exposure between 0-10mSv (DLP: 0-1060mGy*cm) per patient. Most patients in the latter group suffered from intracranial hemorrhage (Figure 3).
11
Total cumulative radiation doses of potentially preventable repeated CT examinations were 81’304mGy*cm (631mSv) per annum and 2’803mGy*cm (21.8mSv) per patient.
Cost Calculation Additional hospital charges ranged from 425CHF (391€) to 1’921CHF (1’769€) per patient that had one or more repeated CT scans. The combined additional annual costs in the entire population of 74 patients with repeated CT examination totaled 69’172CHF (63’694€): head: 26’359CHF (24’272€), C-spine: 8’731CHF (8’040€), chest/abdomen: 34’081CHF (31’382€). The total additional annual costs for preventable repeated CT amounted 38’263CHF (35’233€): head: 9’787CHF (9’012€), C-spine 5’675CHF (5’226€), chest/abdomen: 22’810CHF (21’004€).
12
Discussion Previous studies reported a considerable rate of duplicate CT studies in transferred trauma patients [8, 9, 11-13, 17]. However, most of these studies did either not evaluate radiation doses [8, 17] or provided only estimations [9, 13] and extrapolations [11] of applied radiation doses. The present study aimed at a quantification of the number of repeated CT scans in trauma patients in a European level-I trauma center including assessments of radiation doses and additionally of related costs of these repeated CT examinations. It was found that of all transferred severely injured trauma patients over a one-year period 87% received at least one repeated CT examination, of which 39% were potentially preventable because of problems with the CT image data transfer to our hospital. These repeated CT examinations in trauma patients were associated with a cumulative radiation dose penalty of 81’304mGy*cm (631 mSv) (2’803 mGy*cm and 21.8 mSv per patient) and with additional annual total costs of 35’233€ (1’215 € per patient).
In this study it was noted that the most common reason for potentially preventable CT scans was inadequate CT image data transfer, which occurred in 39% of all repeated CT examinations. Of those, 17% underwent immediate intervention/surgery of the head and 59% of the chest and abdomen only after repeated CT was available, which indicates that a time delay potentially affecting the outcome occurred in a considerable number of these patients. CT image data transfer of trauma patients to our hospital is performed either by manual transfer of CD’s or via internet. Use of CD’s is known to be hampered by incompatibilities of different computer and software systems, while there is need for making CT images available to local radiologists and clinicians as fast as possible – especially in the setting of acute trauma. Regarding the transfer of images through the internet, we noticed in our daily clinical routine that this approach is feasible in patients who are being transferred in
13
the non-trauma setting very well, but appears to be not fast enough for some emergency situations. Such problems should have been solved already, considering the various initiatives for sharing radiologic images such as the Integrating the Healthcare Enterprise (IHE), which provides a standard-based approach for establishing and accepting solutions [18, 19]. Nearly all vendors producing radiological systems for image acquisition and processing implement the open digital imaging and communications in medicine (DICOM) protocol in their products. DICOM not only serves as an open standard for storing multimodal medical images (as well as supplemental information such as reports, segmentation, or registration information), but also defines communication protocols for the exchange of these data entities. Use of a DICOM-email protocol has been recently proposed as a potential solution for fast and secure connections between hospitals causing minimal problems with existing firewall policies [20]. The used basic email protocol guarantees a mandatory encryption and signature of electronically transferred patient data. In distinction to data transfer, there exists also the option of streaming which allows physicians at the trauma center to electronically access the images obtained in the regional hospital’s emergency department [9]. This provides trauma surgeons to review and evaluate CT images well ahead of patient arrival at the trauma center. Despite of these technical possibilities, however, potentially preventable repetition of CT examinations remains an issue, which often can only be solved by making use of several measures at the same time [13]. Our study indicates that with a consistently functioning and fast image data transfer system, a decrease in the rate of repeated CT could have been achieved, which would go along with a reduction of radiation dose and costs because of unnecessary resource usage. Specifically, each patient undergoing potentially preventable
14
repeated CT in our study received a radiation dose penalty of 21.8mSv on average, and costs accounted to 1’214 € per patient. Interestingly, insufficient image quality was not the reason for unnecessarily repeated CT scans in any of our patients. This indicates a high and homogeneous standard in CT image data acquisition along with standardized protocols in trauma patients in the national and international referring hospitals of this study. A total of 33% patients underwent CT imaging in the early trauma care in our hospital for both, repeating head CT in case of known brain injury and completing the imaging workup to a WBCT. WBCT is increasingly considered the imaging tool of choice in patients with trauma during the early resuscitation phase, based on data suggesting an increased probability of survival [21, 22]. It must be kept in mind, however, that the benefits of completion of CT to WBCT are not justified in all patients. Heller et al. [10] demonstrated that clinical management of trauma patients undergoing additional CT examinations of the chest and abdomen after known acute head injury changed only rarely, and occult traumatic findings in the chest and abdomen were found in only 2% of the examinations. Kelleher et al. [23] recently indicated that an additional chest and abdominal CT in patients with known head trauma who otherwise are asymptomatic is not justified in case of low-velocity trauma or fall from a standing position. In our study population, repetition of head CT together with completion to WBCT yielded previously unknown injury of the c-spine/neck in 21% and of the chest and abdomen in 25% of patients, of which 8% required immediate intervention/surgery. Although these relatively high numbers appear to justify a completion to WBCT in polytrauma patients when only head CT was performed, a certain bias must be taken into account because transferred trauma patients are more likely to show a higher injury severity, while less severe trauma patients are kept in the primary center. In accordance with the literature [9], the most commonly repeated examination in this study was head CT. In our patient population, 28.5% of the transferred patients received a 15
follow-up CT scan of the head because of known injury, and 76% of repeated head CT’s were performed together with completion to WBCT. Additional radiation exposure due to repeated head CT was substantially lower as compared to that from chest/abdominal CT, with a cumulative DLP of 37’845mGy*cm (mean 1’892mGy*cm per patient), whereas additional costs were similar with a total of 15’416 CHF (14’080 € per patient). This is explained by the tissue weighting factors for chest and abdominal organs (that are used for calculating the effective dose) being higher than those for the head [16]. Still, head CT is known to be subject to overutilization and often is performed routinely without consequences in treatment nor benefits for the patient [24]. In our study follow-up CT of know injury revealed stable head injury in 43% of patients, whereas 29% showed progression of the known brain injury with 14% requiring immediate surgery/intervention. Again, these high numbers appear to justify repetition of head CT in those polytrauma patients with known head injury.
The following study limitations must be acknowledged. First, there are inherent drawbacks of the retrospective study design. This holds particularly true for the type of data transfer error, which could not be evaluated specifically in this study design. Although a database search was made to clarify in detail which of the data transfer options failed, it was not possible to distinguish further due to the lack of documentation regarding this specific aspect. Since the definition of potentially preventable examinations is based on technical aspects, this limits the conclusions of the study. Second, this study was a single-center study, and results may not be generalizable to other centers and/or others countries. A multicentre trial would have a higher scientific impact and would better help in deducing the financial implications in a wider scale. Third, we estimated the effective radiation dose using the DLP with equation ED ≈ k x DLP, however, this method was shown to underestimate the effective dose when compared with direct measurements [25]. Thus, the true additional radiation dose to patients undergoing repeated CT probably is slightly higher than our estimated values. 16
Finally, we did not calculate the time delay resulting from repeated CT, which is another clinically relevant factor potentially affecting the outcome of patients with acute trauma.
Conclusion In conclusion, the present study demonstrates that trauma patients often undergo repeated CT examinations when being initially surveyed in another hospital and then are being transferred to a trauma center. Problems with the CT image data transfer were identified as the main reason for repetition of CT, which adds additional, potentially preventable radiation dose to the patients and costs to the health care system. This underlines the value of efforts in establishing powerful and secure eHealth solutions on regional or national levels, as they are currently in work in many European countries to improve reliable and timely access to medical information.
17
References [1] L.L. Geyer, M. Koerner, S. Wirth, F.G. Mueck, M.F. Reiser, U. Linsenmaier, Polytrauma: optimal imaging and evaluation algorithm, Semin Musculoskelet Radiol 17(4) (2013) 371-9. [2] K. Buch, T. Nguyen, E. Mahoney, B. Libby, P. Calner, P. Burke, A. Norbash, A. Mian, Association between cervical spine and skull-base fractures and blunt cerebrovascular injury, Eur Radiol 26(2) (2016) 524-31. [3] C. Faget, P. Taourel, J. Charbit, A. Ruyer, C. Alili, N. Molinari, I. Millet, Value of CT to predict surgically important bowel and/or mesenteric injury in blunt trauma: performance of a preliminary scoring system, Eur Radiol 25(12) (2015) 3620-8. [4] P.H. Fung Kon Jin, A.R. van Geene, K.F. Linnau, G.J. Jurkovich, K.J. Ponsen, J.C. Goslings, Time factors associated with CT scan usage in trauma patients, European journal of radiology 72(1) (2009) 134-8. [5] G. Schueller, M. Scaglione, U. Linsenmaier, C. Schueller-Weidekamm, C. Andreoli, M. De Vargas Macciucca, G. Gualdi, The key role of the radiologist in the management of polytrauma patients: indications for MDCT imaging in emergency radiology, Radiol Med 120(7) (2015) 641-54. [6] H. Oikarinen, S. Merilainen, E. Paakko, A. Karttunen, M.T. Nieminen, O. Tervonen, Unjustified CT examinations in young patients, Eur Radiol 19(5) (2009) 1161-5. [7] V. Miele, C. Andreoli, R. Grassi, The management of emergency radiology: key facts, European journal of radiology 59(3) (2006) 311-4. [8] A.J. Young, K.S. Meyers, L. Wolfe, T.M. Duane, Repeat computed tomography for trauma patients undergoing transfer to a level I trauma center, The American Surgeon 78(6) (2012) 675-678. [9] T.J. Berkseth, M.A. Mathiason, M.E. Jafari, T.H. Cogbill, N.Y. Patel, Consequences of increased use of computed tomography imaging for trauma patients in rural referring hospitals prior to transfer to a regional trauma centre, Injury 45(5) (2014) 835-839. 18
[10] M.T. Heller, E. Kanal, O. Almusa, S. Schwarz, M. Papachristou, R. Shah, S. Ventrelli, Utility of additional CT examinations driven by completion of a standard trauma imaging protocol in patients transferred for minor trauma, Emergency radiology 21(4) (2014) 341-347. [11] A.D. Hill, J.S. Catapano, J.B. Surina, M. Lu, Clinical and Economic Impact of Duplicated Radiographic Studies in Trauma, (2013). [12] A.C. Jones, D. Woldemikael, T. Fisher, G.R. Hobbs, B.J. Prud’homme, G.K. Bal, Repeated computed tomographic scans in transferred trauma patients: Indications, costs, and radiation exposure, Journal of Trauma and Acute Care Surgery 73(6) (2012) 1564-1569. [13] P.T. Flanagan, A. Relyea-Chew, J.A. Gross, M.L. Gunn, Using the Internet for image transfer in a regional trauma network: effect on CT repeat rate, cost, and radiation exposure, J Am Coll Radiol 9(9) (2012) 648-56. [14] K.J. Psoter, B.S. Roudsari, J.M. Graves, C. Mack, J.G. Jarvik, Declining trend in the use of repeat computed tomography for trauma patients admitted to a level I trauma center for traffic-related injuries, European journal of radiology 82(6) (2013) 969-73. [15] M. Stevenson, M. Segui-Gomez, I. Lescohier, C. Di Scala, G. McDonald-Smith, An overview of the injury severity score and the new injury severity score, Injury Prevention 7(1) (2001) 10-13. [16] R. Protection, ICRP publication 103, Ann. ICRP 37(2.4) (2007) 2. [17] D.M. Emick, T.S. Carey, A.G. Charles, M.L. Shapiro, Repeat imaging in trauma transfers: a retrospective analysis of computed tomography scans repeated upon arrival to a Level I trauma center, J Trauma Acute Care Surg 72(5) (2012) 1255-62. [18] D.S. Mendelson, P.R. Bak, E. Menschik, E. Siegel, Informatics in radiology: image exchange: IHE and the evolution of image sharing, Radiographics 28(7) (2008) 1817-33. [19] P. Mildenberger, [Integrating the healthcare enterprise (IHE) for radiology: status 2013], Radiologe 53(2) (2013) 149-52.
19
[20] G. Weisser, M. Walz, S. Ruggiero, M. Kammerer, A. Schroter, A. Runa, P. Mildenberger, U. Engelmann, Standardization of teleradiology using Dicom e-mail: recommendations of the German Radiology Society, Eur Radiol 16(3) (2006) 753-8. [21] S. Huber-Wagner, R. Lefering, L.M. Qvick, M. Korner, M.V. Kay, K.J. Pfeifer, M. Reiser, W. Mutschler, K.G. Kanz, S. Working Group on Polytrauma of the German Trauma, Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study, Lancet 373(9673) (2009) 1455-61. [22] M. Scaglione, F. Iaselli, G. Sica, B. Feragalli, R. Nicola, Errors in imaging of traumatic injuries, Abdom Imaging 40(7) (2015) 2091-8. [23] M.S. Kelleher, Jr., G. Gao, M.F. Rolen, S.A. Bokhari, Completion CT of Chest, Abdomen, and Pelvis after Acute Head and Cervical Spine Trauma: Incidence of Acute Traumatic Findings in the Setting of Low-Velocity Trauma, Radiology (2015) 151509. [24] C.V. Brown, G. Zada, A. Salim, K. Inaba, G. Kasotakis, P. Hadjizacharia, D. Demetriades, P. Rhee, Indications for routine repeat head computed tomography (CT) stratified by severity of traumatic brain injury, J Trauma 62(6) (2007) 1339-44; discussion 1344-5. [25] L.M. Hurwitz, T.T. Yoshizumi, P.C. Goodman, D.P. Frush, G. Nguyen, G. Toncheva, C. Lowry, Effective dose determination using an anthropomorphic phantom and metal oxide semiconductor field effect transistor technology for clinical adult body multidetector array computed tomography protocols, Journal of computer assisted tomography 31(4) (2007) 544549.
20
Figure captions
Figure 1: Flowchart of the study. ICU: intensive care unit. *not manageable in referring hospital.
Figure 2: Flowchart showing the indications for repeated CT. WBCT: whole-body CT.
Figure 3: Estimated additional effective dose radiation (mSv) for repeated CT scans, subdivided into clinically indicated and potentially preventable examinations.
21
Fig 1
Fig 2 22
Fig 3
23
Table 1: Demographic data of the trauma patients.
Number of patients Age (years) (mean ± SD)
Repeated CT
Referred without CT
No repeated CT
74
11
213
56 ± 18.9
48 ± 25
51 ± 22.9
Sex
p-values*
0.08 0.43
Male
50 (68%)
8 (73%)
154 (72%)
Female
24 (32%)
3 (27%)
59 (28%)
12.4
4.7
1.8
<0.001
25 ± 16.8
23 ± 18.4
25 ± 18.6
0.58
Time from trauma to trauma center (h) ISS Trauma mechanism
0.98
traffic accident
25 (34%)
3 (28%)
70 (33%)
fall
34 (46%)
4 (36%)
101 (47%)
others
15 (20%)
4 (36%)
42 (20%)
ISS: Injury Severity Score; SD: standard deviation *comparison between patients with repeated CT (n=74) and those who had no repeated CT (n=224)
24
Table 2: Fee-schedule for cost calculations of CT examinations. Non-enhanced CT
Contrast media-enhanced CT
Head
425 CHF (391 €*)
727 CHF§ (669 €*)
C-spine/neck
436 CHF (401 €*)
539 CHF° (496 €*)
Thorax
-
580 CHF (534 €*)
Abdomen
-
578 CHF (532 €*)
* using the exchange rate from CHF to € from January 8, 2016. ° single phase CT with contrast media § non-enhanced and contrast-enhanced CT
25
Table 3: Imaging findings in repeated CT categorized by body regions and indications. No new imaging findings
Inadequate data transfer (n=29)
Poor image quality (n=0) Repetition of head CT and completion to WBCT (n=24) Follow-up of known injury (n=21)
Stable trauma injury
Progression of trauma injury
injury
requiring intervention/surgery
Head: 2 (7%)
Head: 7 (24%)
Head: 3 (10%)
Head: 5 (17%)
C-spine/neck: 4 (14%)
C-spine/neck: 8 (28%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 2 (7%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 17 (59%)
-
-
-
-
Head: 0 (0%)
Head: 10 (42%)
Head: 10 (24%)
Head: 4 (17%)
C-spine/neck: 19 (79%)
C-spine/neck: 0 (0%)
C-spine/neck: 5 (21%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 17 (71%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 4 (17%)
Chest/Abdomen: 2 (8%)
Head: 2 (10%)
Head: 9 (43%)
Head: 3 (14%)
Head: 3 (14%)
C-spine/neck: 4 (19%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 1 (5%)
Chest/Abdomen: 2 (10%)
Chest/Abdomen: 6 (29%)
26
Progression of trauma
Table 4: Reasons for repeated CT scans and corresponding radiation doses (effective dose and DLP) per patient. Total
Head
C-spine/neck
Chest/Abdome n
Inadequate data transfer
22 mSv
3 mSv
1 mSv
18 mSv
2803 mGy*cm
1579
196 mGy*cm
1208 mGy*cm
mGy*cm Poor image quality
Repetition of head CT and completion to WBCT
-
-
-
-
21 mSv
3 mSv
1 mSv
18 mSv
2830 mGy*cm
1579
196 mGy*cm
1208 mGy*cm
mGy*cm Follow-up of known injury
10 mSv
2 mSv
0.5 mSv
8 mSv
1802 mGy*cm
1053
98 mGy*cm
537 mGy*cm
mGy*cm
27
S0720-048X(17)30011-6 http://dx.doi.org/doi:10.1016/j.ejrad.2017.01.007 EURR 7695
To appear in:
European Journal of Radiology
Received date: Revised date: Accepted date:
7-7-2016 1-1-2017 5-1-2017
Please cite this article as: Hinzpeter Ricarda, Sprengel Kai, Wanner Guido A, Mildenberger Peter, Alkadhi Hatem.Repeated CT scans in Trauma Transfers: An Analysis of Indications, Radiation Dose Exposure, and Costs.European Journal of Radiology http://dx.doi.org/10.1016/j.ejrad.2017.01.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Repeated CT scans in Trauma Transfers: An Analysis of Indications, Radiation Dose Exposure, and Costs
Ricarda Hinzpeter1, MD, Kai Sprengel2, MD, Guido A. Wanner2,3, MD, 4Peter Mildenberger, MD, Hatem Alkadhi1, MD, MPH, EBCR
1
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland
2
Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Switzerland 3
Department of General Surgery, Schwarzwald-Baar Klinikum, University of Freiburg, Germany
4
Department of Diagnostic and Interventional Radiology, University Hospital of Mainz, Germany
1. Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland Ricarda Hinzpeter, [email protected] Hatem Alkadhi, [email protected]
2. Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland Kai Sprengel, [email protected]
1
3. Department of General Surgery, Schwarzwald-Baar Klinikum, University of Freiburg, Klinikstr. 11, D-78052 Villingen-Schwenningen, Germany Guido A. Wanner, [email protected]
4. Department of Diagnostic and Interventional Radiology, University Hospital of Mainz, Langenbeckstr. 1, D-55131 Mainz, Germany Peter Mildenberger, [email protected]
Corresponding author: Hatem Alkadhi, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistr. 100, CH-8091 Zurich, Switzerland, Tel. +41 (0)44 255 3662, Fax: +41 (0)44 255 4443, email: [email protected]
Highlights:
Repetition of CT in trauma patients occurs relatively often.
Repetition of CT is mainly caused by inadequate image data transfer.
Potentially preventable CT examinations add radiation dose to patients.
Repeated CT is associated with excess costs to the health care system.
2
Abstract Objectives: To identify the number of CT scans repeated in acute trauma patients receiving imaging before being referred to a trauma center, to define indications, and to assess radiation doses and costs of repeated CT. Methods: This retrospective study included all adult trauma patients transferred from other hospitals to a Level-I trauma center during 2014. Indications for repeated CT scans were categorized into: inadequate CT image data transfer, poor image quality, repetition of head CT after head injury together with completion to whole-body CT (WBCT), and follow-up of injury known from previous CT. Radiation doses from repeated CT were determined; costs were calculated using a nation-wide fee schedule. Results: Within one year, 85/298 (28.5%) trauma patients were transferred from another hospital because of severe head injury (n=45,53%) and major body trauma (n=23;27%) not manageable in the referring hospital, repatriation from a foreign country (n=14;16.5%), and no ICU-capacity (n=3;3.5%). Of these 85 patients, 74 (87%) had repeated CT in our center because of inadequate CT data transfer (n=29;39%), repetition of head CT with completion to WBCT (n=24;32.5%), and follow-up of known injury (n=21;28.5%). None occurred because of poor image quality. Cumulative dose length product (DLP) and annual costs of potential preventable, repeated CT (inadequate data transfer) was 631mSv (81’304mGy*cm) and 35’233€, respectively. Conclusion: A considerable number of transferred trauma patients undergo potentially preventable, repeated CT, adding radiation dose to patients and costs to the health care system. Abbreviations WBCT
whole-body computed tomography
DLP
dose-length product
Key words: imaging, trauma, radiation exposure, health care costs 3
Introduction Computed tomography (CT) is the modality of choice for the early imaging work-up of severely injured trauma patients [1-4]. This is mainly due to fast image acquisition, robustness, accuracy and wide availability. Nevertheless, CT scans have the disadvantage of being associated with potentially harmful radiation exposure to the often relatively young trauma population [5-7]. The Swiss government announced in 2011 a total of 12 authorized centers for treatment of severely injured trauma patients, based on various criteria including the availability of 24/7 trauma patient care including radiology services. In addition, these trauma centers have to guarantee a standardized and structured data acquisition to a registry which records the quality of processes and results. While these trauma centers are intended to deliver the primary care of severely injured trauma patients, still many injured patients are admitted and often are radiologically evaluated in other, mostly regional hospitals and are then being transferred to a Level-I trauma center [8]. Reasons for transfers of these patients to a trauma center may be an initial underestimation of the true trauma load, patients who become hemodynamically unstable or had a trauma which is not manageable in the referring hospital [9, 10]. It was observed that transferred trauma patients frequently had foregoing initial CT examinations performed at the referring institution, but many of them were rescanned based on indications of our trauma surgeons. This is in line with some recent literature from the U.S. indicating that repeated CT imaging in trauma patients occurs relatively often, and indications for duplicate CT imaging differ depending on the institution and referring networks [8-13]. Potentially unnecessary repeated CT scans, however, expose trauma patients to additional ionizing radiation and increase resource use [14]. It was sought to identify the number of CT scans repeated in trauma patients receiving a radiologic work-up before being referred to our trauma center, to define indications for 4
repeated CT scans including imaging findings, and to assess associated radiation doses and costs.
5
Materials and Methods Study Population This study was performed at our Level-I trauma center in Switzerland between January and December 2014. During this one-year period 298 trauma patients were identified (mean age 52±22 years), being either directly admitted to our trauma center (213/298, 72%) or being transferred after secondary survey (85/298, 29%) (Figure 1). Reasons for transfer to our trauma center were severe head injury (n=45, 53%) and major body trauma (n=23, 27%) being not manageable in the referring hospital, repatriation from a foreign country (n=14, 17%), and lack of local intensive care unit (ICU) capacity (n=3, 4%). All patients included were recorded in the trauma registry hosted by the German Association for Trauma Surgery (www.traumaregister-dgu.de). According to this trauma registry only patients who are admitted through the emergency room and who are in need of intensive care are recorded in the database. In the present study only those adult trauma patients were included who got a CT evaluation at our hospital’s emergency department. Repetition of CT was defined as CT examination in the referring hospital and at our trauma center within 24 hours of trauma. Patients who had been evaluated and underwent one or more CT examinations in the context of acute trauma and those who were directly referred and who had no foregoing CT were compared regarding age, sex, trauma mechanism, injury severity score (ISS) and time from trauma to our trauma center (Table 1) [15]. These data were taken from the electronic records of patients in all involved hospitals. This retrospective study had local ethics committee approval; written informed consent requirement was waived.
Data Collection and Categorization
6
A thorough database search was made to identify the trauma mechanism, the severity of trauma indicated by the ISS and the indications for repeated CT examinations in our trauma center in patients who were transferred from a regional hospital. These indications were categorized as previously shown [11, 12]: inadequate CT image data transfer, poor CT image quality, repetition of head CT after head injury together with completion to WBCT, and follow-up of trauma injury known from previous CT in the regional hospital. The four body regions comprising a whole-body CT were evaluated: head, neck/cervical spine, chest and abdomen. Imaging data from referring hospitals were either sent electronically or were provided per data carrier (CD). For electronic transfer of imaging studies we used the MedicalConnector-network (H-Net AG, Zurich, Switzerland). This network ensures a flexible and encrypted transmission of medical data in the required data format.
Image quality of CT in referring hospitals First, all CT examinations performed in the referring hospital (and which were repeated in our trauma center) were reviewed regarding image quality by one blinded radiologist (with 13 years of experience in imaging). Image quality was categorized in a dichotomic way: diagnostic or non-diagnostic because of inadequate image quality.
CT examination All CT examinations in our center were performed using a 128-slice CT scanner (SOMATOM Definition Flash; Siemens Healthcare) located adjacent to the emergency room and included non-enhanced CT of the head, non-enhanced CT of the cervical spine and contrast-enhanced CT of the chest and abdomen. The contrast media protocol aimed at an arterio-venous phase for the chest and a portal-venous phase of the abdomen. For this, a total of 100 ml non-ionic iodinated contrast material (Iopromidum, Ultravist 300, 300mg/ml, 7
Bayer, Leverkusen, Germany) with a flow rate of 4 ml/sec was injected through an antecubital vein. Contrast agent application was controlled by bolus tracking in the descending aorta (attenuation threshold 120 HU at 120 kVp). Image acquisition started 5 sec and 40 sec after the signal density reached the predefined threshold. All CT scans in our department were performed with our institutional standard protocol settings using a tube voltage of 120kVp and with quality reference tube current-time products adjusted to the respective body region (head: 320mAs, cervical spine: 200mAs, chest and abdomen: 150mAs). Images were reconstructed and reformatted with slice thicknesses ranging from 1-2mm using sinogram-affirmed iterative reconstruction at a strength level of 3.
Imaging findings in repeated CT All repeated CT examinations in our hospital were analyzed regarding their imaging findings and were compared to those from the previous CT examinations in the referring hospitals. Imaging findings were categorized by indications for repeated CT and by each body region (head, C-spine/neck, chest, and abdomen) as follows: no new imaging findings related to trauma, stable trauma injury known from previous CT, progression of trauma injury known from previous CT, progression of trauma injury requiring intervention and/or surgery.
Radiation Dose Estimation The radiation exposure per CT scan was collected from the radiation dose reports automatically generated by the scanner. The metric dose length product (DLP, in mGy*cm) was used as the most suitable radiation dose parameter for such studies, as previously shown [12]. Effective radiation doses (in mSv) were estimated using conversion coefficients (k) for adults specific to the respective body regions at 120kVp reported in the 2007
8
Recommendations of the International Commission on Radiological Protection (ICRP [16]) using the following equation : ED ≈ k* DLP.
Cost Calculation A nation-wide fee schedule was used to obtain the hospital charges for each repeated CT scan. Costs of head, c-spine/neck, and chest/abdomen CT were assessed separately. Detailed information about the fee schedule is provided in Table 2. These costs in trauma patients in the emergency department equal those for outpatients plus an additional fee for the required intensive care.
Statistical Methods Quantitative variables were expressed as means ± standard deviations for normally distributed, and as medians ± interquartile ranges for non-normally distributed values. Percentages were used for categorical parameters. Normality was tested using the ShapiroWilk test. Student’s t-test for independent samples was used for differences between patient groups regarding age. Mann-Whitney U test was used to test for differences between patient groups regarding the injury severity score (ISS). The 2 test was used for differences between patient groups regarding sex and trauma mechanism. The Levene’s test was conducted for differences between patient groups regarding the time from trauma until arrival at our trauma center. For economic calculations we used the exchange rate from January 8th 2016 (1 CHF = 0.9207 €). Data were analyzed using commercially available software (IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp). The level of significance was set at a two-tailed p-value < 0.05.
9
Results Study Population Seventy-four of the 85 referred patients (87%) underwent repeated CT, whereas 11/85 patients (13%) had no repeated CT examination (Figure 2). There were no significant differences between patients with repeated CT as compared to those without repeated CT regarding sex (p=0.43), age (p=0.08) and ISS (p=0.58). Fall and motor vehicle accidents were the mechanisms responsible for most traumas in both patient populations, with no differences between groups (p=0.98). The mean time from trauma to admission to our center was significantly shorter in patients without repeated CT (median 1.5 ± 3 hours) as compared to those with repeated CT (median 3.0 ± 19 hours, p<0.001), which was mainly due to their stay in the referring hospitals (Table 1).
Indications for repeated CT Indications for repeated CT scans included inadequate CT image data transfer (n=29, 39%), repetition of head CT after known head injury together with completion to WBCT (n=24, 32.5%) and follow-up of known trauma injury from previous CT (n=21, 28.5%). Image quality assessment showed that none of the examinations was repeated in our hospital because of poor image quality of the CT performed in the referring hospital.
Imaging findings categorized by indications for repeated CT Detailed information about the imaging findings in repeated CT in each category and for each body region is provided in Table 3. Inadequate CT image data transfer: Of the 29 patients in whom CT was repeated because of inadequate CT image data transfer, 5 (17%) with head injury and 17 (59%) with injury of the chest and abdomen showed a progression of traumatic injury requiring immediate intervention/surgery. 10
Repetition of head CT and completion to WBCT: Of the 24 patients in whom head CT was repeated and WBCT was completed, 4 (17%) with head injury and 2 (8%) with injury of chest and abdomen showed a progression of traumatic injury requiring immediate intervention/surgery. Follow-up of known trauma injury: Of the 21 patients in whom CT was repeated because of known injury 3 (14%) head and 6/21 (29%) chest and abdomen injuries showed a progression requiring immediate intervention/surgery.
Radiation Dose Estimation The additional estimated effective radiation dose of repeated CT scans separately assessed for the different indications ranged from 2-3mSv (DLP: 1050-1580 mGy*cm) for head CT, from 0.5-1mSv (DLP: 100-200 mGy*cm) for the C-spine/neck, and from 8-18mSv (DLP: 540-1200 mGy*cm) for the chest and abdomen per patient (Table 4). The estimated effective radiation dose of repeated CT scans separately determined for each body region were as follows: DLP head: 1411 mGy*cm ± 236 mGy*cm; DLP Cspine/neck: 296 mGy*cm ± 55 mGy*cm; DLP chest and abdomen: 1366 mGy*cm ± 549 mGy*cm. Inadequate CT image data transfer and poor CT image quality were defined as potentially preventable radiologic work-up and showed a peak of additional radiation dose between 20-30mSv (DLP:1340-2015 mGy*cm) per patient and consisted mainly of chest/abdomen and head CT examinations. In distinction, clinically indicated CT examinations (follow-up of known trauma injury from foregoing CT, repetition of head CT after known head injury with completion to WBCT) showed a peak of additional dose exposure between 0-10mSv (DLP: 0-1060mGy*cm) per patient. Most patients in the latter group suffered from intracranial hemorrhage (Figure 3).
11
Total cumulative radiation doses of potentially preventable repeated CT examinations were 81’304mGy*cm (631mSv) per annum and 2’803mGy*cm (21.8mSv) per patient.
Cost Calculation Additional hospital charges ranged from 425CHF (391€) to 1’921CHF (1’769€) per patient that had one or more repeated CT scans. The combined additional annual costs in the entire population of 74 patients with repeated CT examination totaled 69’172CHF (63’694€): head: 26’359CHF (24’272€), C-spine: 8’731CHF (8’040€), chest/abdomen: 34’081CHF (31’382€). The total additional annual costs for preventable repeated CT amounted 38’263CHF (35’233€): head: 9’787CHF (9’012€), C-spine 5’675CHF (5’226€), chest/abdomen: 22’810CHF (21’004€).
12
Discussion Previous studies reported a considerable rate of duplicate CT studies in transferred trauma patients [8, 9, 11-13, 17]. However, most of these studies did either not evaluate radiation doses [8, 17] or provided only estimations [9, 13] and extrapolations [11] of applied radiation doses. The present study aimed at a quantification of the number of repeated CT scans in trauma patients in a European level-I trauma center including assessments of radiation doses and additionally of related costs of these repeated CT examinations. It was found that of all transferred severely injured trauma patients over a one-year period 87% received at least one repeated CT examination, of which 39% were potentially preventable because of problems with the CT image data transfer to our hospital. These repeated CT examinations in trauma patients were associated with a cumulative radiation dose penalty of 81’304mGy*cm (631 mSv) (2’803 mGy*cm and 21.8 mSv per patient) and with additional annual total costs of 35’233€ (1’215 € per patient).
In this study it was noted that the most common reason for potentially preventable CT scans was inadequate CT image data transfer, which occurred in 39% of all repeated CT examinations. Of those, 17% underwent immediate intervention/surgery of the head and 59% of the chest and abdomen only after repeated CT was available, which indicates that a time delay potentially affecting the outcome occurred in a considerable number of these patients. CT image data transfer of trauma patients to our hospital is performed either by manual transfer of CD’s or via internet. Use of CD’s is known to be hampered by incompatibilities of different computer and software systems, while there is need for making CT images available to local radiologists and clinicians as fast as possible – especially in the setting of acute trauma. Regarding the transfer of images through the internet, we noticed in our daily clinical routine that this approach is feasible in patients who are being transferred in
13
the non-trauma setting very well, but appears to be not fast enough for some emergency situations. Such problems should have been solved already, considering the various initiatives for sharing radiologic images such as the Integrating the Healthcare Enterprise (IHE), which provides a standard-based approach for establishing and accepting solutions [18, 19]. Nearly all vendors producing radiological systems for image acquisition and processing implement the open digital imaging and communications in medicine (DICOM) protocol in their products. DICOM not only serves as an open standard for storing multimodal medical images (as well as supplemental information such as reports, segmentation, or registration information), but also defines communication protocols for the exchange of these data entities. Use of a DICOM-email protocol has been recently proposed as a potential solution for fast and secure connections between hospitals causing minimal problems with existing firewall policies [20]. The used basic email protocol guarantees a mandatory encryption and signature of electronically transferred patient data. In distinction to data transfer, there exists also the option of streaming which allows physicians at the trauma center to electronically access the images obtained in the regional hospital’s emergency department [9]. This provides trauma surgeons to review and evaluate CT images well ahead of patient arrival at the trauma center. Despite of these technical possibilities, however, potentially preventable repetition of CT examinations remains an issue, which often can only be solved by making use of several measures at the same time [13]. Our study indicates that with a consistently functioning and fast image data transfer system, a decrease in the rate of repeated CT could have been achieved, which would go along with a reduction of radiation dose and costs because of unnecessary resource usage. Specifically, each patient undergoing potentially preventable
14
repeated CT in our study received a radiation dose penalty of 21.8mSv on average, and costs accounted to 1’214 € per patient. Interestingly, insufficient image quality was not the reason for unnecessarily repeated CT scans in any of our patients. This indicates a high and homogeneous standard in CT image data acquisition along with standardized protocols in trauma patients in the national and international referring hospitals of this study. A total of 33% patients underwent CT imaging in the early trauma care in our hospital for both, repeating head CT in case of known brain injury and completing the imaging workup to a WBCT. WBCT is increasingly considered the imaging tool of choice in patients with trauma during the early resuscitation phase, based on data suggesting an increased probability of survival [21, 22]. It must be kept in mind, however, that the benefits of completion of CT to WBCT are not justified in all patients. Heller et al. [10] demonstrated that clinical management of trauma patients undergoing additional CT examinations of the chest and abdomen after known acute head injury changed only rarely, and occult traumatic findings in the chest and abdomen were found in only 2% of the examinations. Kelleher et al. [23] recently indicated that an additional chest and abdominal CT in patients with known head trauma who otherwise are asymptomatic is not justified in case of low-velocity trauma or fall from a standing position. In our study population, repetition of head CT together with completion to WBCT yielded previously unknown injury of the c-spine/neck in 21% and of the chest and abdomen in 25% of patients, of which 8% required immediate intervention/surgery. Although these relatively high numbers appear to justify a completion to WBCT in polytrauma patients when only head CT was performed, a certain bias must be taken into account because transferred trauma patients are more likely to show a higher injury severity, while less severe trauma patients are kept in the primary center. In accordance with the literature [9], the most commonly repeated examination in this study was head CT. In our patient population, 28.5% of the transferred patients received a 15
follow-up CT scan of the head because of known injury, and 76% of repeated head CT’s were performed together with completion to WBCT. Additional radiation exposure due to repeated head CT was substantially lower as compared to that from chest/abdominal CT, with a cumulative DLP of 37’845mGy*cm (mean 1’892mGy*cm per patient), whereas additional costs were similar with a total of 15’416 CHF (14’080 € per patient). This is explained by the tissue weighting factors for chest and abdominal organs (that are used for calculating the effective dose) being higher than those for the head [16]. Still, head CT is known to be subject to overutilization and often is performed routinely without consequences in treatment nor benefits for the patient [24]. In our study follow-up CT of know injury revealed stable head injury in 43% of patients, whereas 29% showed progression of the known brain injury with 14% requiring immediate surgery/intervention. Again, these high numbers appear to justify repetition of head CT in those polytrauma patients with known head injury.
The following study limitations must be acknowledged. First, there are inherent drawbacks of the retrospective study design. This holds particularly true for the type of data transfer error, which could not be evaluated specifically in this study design. Although a database search was made to clarify in detail which of the data transfer options failed, it was not possible to distinguish further due to the lack of documentation regarding this specific aspect. Since the definition of potentially preventable examinations is based on technical aspects, this limits the conclusions of the study. Second, this study was a single-center study, and results may not be generalizable to other centers and/or others countries. A multicentre trial would have a higher scientific impact and would better help in deducing the financial implications in a wider scale. Third, we estimated the effective radiation dose using the DLP with equation ED ≈ k x DLP, however, this method was shown to underestimate the effective dose when compared with direct measurements [25]. Thus, the true additional radiation dose to patients undergoing repeated CT probably is slightly higher than our estimated values. 16
Finally, we did not calculate the time delay resulting from repeated CT, which is another clinically relevant factor potentially affecting the outcome of patients with acute trauma.
Conclusion In conclusion, the present study demonstrates that trauma patients often undergo repeated CT examinations when being initially surveyed in another hospital and then are being transferred to a trauma center. Problems with the CT image data transfer were identified as the main reason for repetition of CT, which adds additional, potentially preventable radiation dose to the patients and costs to the health care system. This underlines the value of efforts in establishing powerful and secure eHealth solutions on regional or national levels, as they are currently in work in many European countries to improve reliable and timely access to medical information.
17
References [1] L.L. Geyer, M. Koerner, S. Wirth, F.G. Mueck, M.F. Reiser, U. Linsenmaier, Polytrauma: optimal imaging and evaluation algorithm, Semin Musculoskelet Radiol 17(4) (2013) 371-9. [2] K. Buch, T. Nguyen, E. Mahoney, B. Libby, P. Calner, P. Burke, A. Norbash, A. Mian, Association between cervical spine and skull-base fractures and blunt cerebrovascular injury, Eur Radiol 26(2) (2016) 524-31. [3] C. Faget, P. Taourel, J. Charbit, A. Ruyer, C. Alili, N. Molinari, I. Millet, Value of CT to predict surgically important bowel and/or mesenteric injury in blunt trauma: performance of a preliminary scoring system, Eur Radiol 25(12) (2015) 3620-8. [4] P.H. Fung Kon Jin, A.R. van Geene, K.F. Linnau, G.J. Jurkovich, K.J. Ponsen, J.C. Goslings, Time factors associated with CT scan usage in trauma patients, European journal of radiology 72(1) (2009) 134-8. [5] G. Schueller, M. Scaglione, U. Linsenmaier, C. Schueller-Weidekamm, C. Andreoli, M. De Vargas Macciucca, G. Gualdi, The key role of the radiologist in the management of polytrauma patients: indications for MDCT imaging in emergency radiology, Radiol Med 120(7) (2015) 641-54. [6] H. Oikarinen, S. Merilainen, E. Paakko, A. Karttunen, M.T. Nieminen, O. Tervonen, Unjustified CT examinations in young patients, Eur Radiol 19(5) (2009) 1161-5. [7] V. Miele, C. Andreoli, R. Grassi, The management of emergency radiology: key facts, European journal of radiology 59(3) (2006) 311-4. [8] A.J. Young, K.S. Meyers, L. Wolfe, T.M. Duane, Repeat computed tomography for trauma patients undergoing transfer to a level I trauma center, The American Surgeon 78(6) (2012) 675-678. [9] T.J. Berkseth, M.A. Mathiason, M.E. Jafari, T.H. Cogbill, N.Y. Patel, Consequences of increased use of computed tomography imaging for trauma patients in rural referring hospitals prior to transfer to a regional trauma centre, Injury 45(5) (2014) 835-839. 18
[10] M.T. Heller, E. Kanal, O. Almusa, S. Schwarz, M. Papachristou, R. Shah, S. Ventrelli, Utility of additional CT examinations driven by completion of a standard trauma imaging protocol in patients transferred for minor trauma, Emergency radiology 21(4) (2014) 341-347. [11] A.D. Hill, J.S. Catapano, J.B. Surina, M. Lu, Clinical and Economic Impact of Duplicated Radiographic Studies in Trauma, (2013). [12] A.C. Jones, D. Woldemikael, T. Fisher, G.R. Hobbs, B.J. Prud’homme, G.K. Bal, Repeated computed tomographic scans in transferred trauma patients: Indications, costs, and radiation exposure, Journal of Trauma and Acute Care Surgery 73(6) (2012) 1564-1569. [13] P.T. Flanagan, A. Relyea-Chew, J.A. Gross, M.L. Gunn, Using the Internet for image transfer in a regional trauma network: effect on CT repeat rate, cost, and radiation exposure, J Am Coll Radiol 9(9) (2012) 648-56. [14] K.J. Psoter, B.S. Roudsari, J.M. Graves, C. Mack, J.G. Jarvik, Declining trend in the use of repeat computed tomography for trauma patients admitted to a level I trauma center for traffic-related injuries, European journal of radiology 82(6) (2013) 969-73. [15] M. Stevenson, M. Segui-Gomez, I. Lescohier, C. Di Scala, G. McDonald-Smith, An overview of the injury severity score and the new injury severity score, Injury Prevention 7(1) (2001) 10-13. [16] R. Protection, ICRP publication 103, Ann. ICRP 37(2.4) (2007) 2. [17] D.M. Emick, T.S. Carey, A.G. Charles, M.L. Shapiro, Repeat imaging in trauma transfers: a retrospective analysis of computed tomography scans repeated upon arrival to a Level I trauma center, J Trauma Acute Care Surg 72(5) (2012) 1255-62. [18] D.S. Mendelson, P.R. Bak, E. Menschik, E. Siegel, Informatics in radiology: image exchange: IHE and the evolution of image sharing, Radiographics 28(7) (2008) 1817-33. [19] P. Mildenberger, [Integrating the healthcare enterprise (IHE) for radiology: status 2013], Radiologe 53(2) (2013) 149-52.
19
[20] G. Weisser, M. Walz, S. Ruggiero, M. Kammerer, A. Schroter, A. Runa, P. Mildenberger, U. Engelmann, Standardization of teleradiology using Dicom e-mail: recommendations of the German Radiology Society, Eur Radiol 16(3) (2006) 753-8. [21] S. Huber-Wagner, R. Lefering, L.M. Qvick, M. Korner, M.V. Kay, K.J. Pfeifer, M. Reiser, W. Mutschler, K.G. Kanz, S. Working Group on Polytrauma of the German Trauma, Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study, Lancet 373(9673) (2009) 1455-61. [22] M. Scaglione, F. Iaselli, G. Sica, B. Feragalli, R. Nicola, Errors in imaging of traumatic injuries, Abdom Imaging 40(7) (2015) 2091-8. [23] M.S. Kelleher, Jr., G. Gao, M.F. Rolen, S.A. Bokhari, Completion CT of Chest, Abdomen, and Pelvis after Acute Head and Cervical Spine Trauma: Incidence of Acute Traumatic Findings in the Setting of Low-Velocity Trauma, Radiology (2015) 151509. [24] C.V. Brown, G. Zada, A. Salim, K. Inaba, G. Kasotakis, P. Hadjizacharia, D. Demetriades, P. Rhee, Indications for routine repeat head computed tomography (CT) stratified by severity of traumatic brain injury, J Trauma 62(6) (2007) 1339-44; discussion 1344-5. [25] L.M. Hurwitz, T.T. Yoshizumi, P.C. Goodman, D.P. Frush, G. Nguyen, G. Toncheva, C. Lowry, Effective dose determination using an anthropomorphic phantom and metal oxide semiconductor field effect transistor technology for clinical adult body multidetector array computed tomography protocols, Journal of computer assisted tomography 31(4) (2007) 544549.
20
Figure captions
Figure 1: Flowchart of the study. ICU: intensive care unit. *not manageable in referring hospital.
Figure 2: Flowchart showing the indications for repeated CT. WBCT: whole-body CT.
Figure 3: Estimated additional effective dose radiation (mSv) for repeated CT scans, subdivided into clinically indicated and potentially preventable examinations.
21
Fig 1
Fig 2 22
Fig 3
23
Table 1: Demographic data of the trauma patients.
Number of patients Age (years) (mean ± SD)
Repeated CT
Referred without CT
No repeated CT
74
11
213
56 ± 18.9
48 ± 25
51 ± 22.9
Sex
p-values*
0.08 0.43
Male
50 (68%)
8 (73%)
154 (72%)
Female
24 (32%)
3 (27%)
59 (28%)
12.4
4.7
1.8
<0.001
25 ± 16.8
23 ± 18.4
25 ± 18.6
0.58
Time from trauma to trauma center (h) ISS Trauma mechanism
0.98
traffic accident
25 (34%)
3 (28%)
70 (33%)
fall
34 (46%)
4 (36%)
101 (47%)
others
15 (20%)
4 (36%)
42 (20%)
ISS: Injury Severity Score; SD: standard deviation *comparison between patients with repeated CT (n=74) and those who had no repeated CT (n=224)
24
Table 2: Fee-schedule for cost calculations of CT examinations. Non-enhanced CT
Contrast media-enhanced CT
Head
425 CHF (391 €*)
727 CHF§ (669 €*)
C-spine/neck
436 CHF (401 €*)
539 CHF° (496 €*)
Thorax
-
580 CHF (534 €*)
Abdomen
-
578 CHF (532 €*)
* using the exchange rate from CHF to € from January 8, 2016. ° single phase CT with contrast media § non-enhanced and contrast-enhanced CT
25
Table 3: Imaging findings in repeated CT categorized by body regions and indications. No new imaging findings
Inadequate data transfer (n=29)
Poor image quality (n=0) Repetition of head CT and completion to WBCT (n=24) Follow-up of known injury (n=21)
Stable trauma injury
Progression of trauma injury
injury
requiring intervention/surgery
Head: 2 (7%)
Head: 7 (24%)
Head: 3 (10%)
Head: 5 (17%)
C-spine/neck: 4 (14%)
C-spine/neck: 8 (28%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 2 (7%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 17 (59%)
-
-
-
-
Head: 0 (0%)
Head: 10 (42%)
Head: 10 (24%)
Head: 4 (17%)
C-spine/neck: 19 (79%)
C-spine/neck: 0 (0%)
C-spine/neck: 5 (21%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 17 (71%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 4 (17%)
Chest/Abdomen: 2 (8%)
Head: 2 (10%)
Head: 9 (43%)
Head: 3 (14%)
Head: 3 (14%)
C-spine/neck: 4 (19%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
C-spine/neck: 0 (0%)
Chest/Abdomen: 0 (0%)
Chest/Abdomen: 1 (5%)
Chest/Abdomen: 2 (10%)
Chest/Abdomen: 6 (29%)
26
Progression of trauma
Table 4: Reasons for repeated CT scans and corresponding radiation doses (effective dose and DLP) per patient. Total
Head
C-spine/neck
Chest/Abdome n
Inadequate data transfer
22 mSv
3 mSv
1 mSv
18 mSv
2803 mGy*cm
1579
196 mGy*cm
1208 mGy*cm
mGy*cm Poor image quality
Repetition of head CT and completion to WBCT
-
-
-
-
21 mSv
3 mSv
1 mSv
18 mSv
2830 mGy*cm
1579
196 mGy*cm
1208 mGy*cm
mGy*cm Follow-up of known injury
10 mSv
2 mSv
0.5 mSv
8 mSv
1802 mGy*cm
1053
98 mGy*cm
537 mGy*cm
mGy*cm
27