- Email: [email protected]
Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT
Clinical Radiology xxx (2016) 1e2
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
Correspondence
Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT SirdIn the recent paper by Davies et al.,1 the new National Institute for Health and Care Excellence (NICE) guidelines are reported as “broader”,1 resulting in more cervical-spine computed tomography (CT) examinations. The main criticism of Davies et al. is levelled at the 85% of additional CT examinations of patients already in the CT scanner.1 At the core of the authors’ rationale lies a significant misrepresentation of the riskebenefit balance that CT “must always be mitigated by the desire to minimise radiation dose in paediatric patients”.1 This is supported by reports of increased risks of thyroid cancer from CT performed in childhood. The authors conclude prematurely that “to minimise thyroid radiation exposure it is therefore, important to target the use of CT to only those cases in which plain radiographs have not reliably excluded bony injury”.1 Such unwarranted concern about radiation risk, can harm a patient2 by denying them access to an examination of choice.3 Guillerman warned that “informed decision-making” “requires appropriate framing of the risks of radiation from CT” and “the benefits of imaging”.4 Considering a mortality of 40% for a missed cervical spine fracture1 “the risk of radiation-induced cancer may lose importance”.2 In June 2016, the American Journal of Roentgenology printed an acknowledgement from medical physicist, Cynthia McCullough, that the overall risk of CT is low or has non-existent risk5: “although there is a perception among some physicians and patients that the low doses of ionising radiation associated with.CT, are dangerous, this inaccurate perception is not consistent with current consensus opinions from radiation protection and medical physics organisations”.5 Biological responses to low-dose (<100 mGy) radiation do not follow the linear no-threshold model4 and use of this model for calculating individual risks is discouraged.3 The American Association of Physicists in Medicine states that “the risks of medical imaging using a radiation dose less than 50 mSv at one time or 100 mSv in multiple doses over a short period of time are too low to be detectable and may be non-existent”2,3dtypical CT head doses are 0.5e2 mSv and chest/abdomen 2e7
DOI of original article: http://dx.doi.org/10.1016/j.crad.2016.11.022.
mSv.5 Papers by Pearce et al. (2012)6 and Mathews et al. (2013),7 cited as proof of a link between CT scans and cancer, have been criticised for “a very real possibility of reverse causation in the absence of proper controls”.3 For argument’s sake, if a calculated risk is accepted, then the 0.04% radiation risk of cancer from a CT examination increases the existing risk in adulthood by very little, i.e., if 44% of males and 38% of females have a natural lifetime risk of cancer, then the additional risk from a CT will increase this to 44.04% and 38.04%, respectively.8 Imaging decisions based on the notion that cervical spine fractures in younger children occur in the upper cervical spine9 need to be reviewed considering the findings from the National Trauma Data Bank of 1,523 children <3 years of age, which showed that 48% of all cervical spine fractures involved the lower cervical spine (C5e7)10; a region possibly harder to visualise on low-quality radiographs. Davies et al. reported that only 11% of patients with inadequate radiographs underwent CT, even though inadequate radiographs were in the majority.1 Rana et al.11 report that the major contributors to the poor performance of plain cervical spine radiographs are low radiographic quality and errors of interpretation. They also reported that 28% of cervical spine fractures would have been missed on plain radiographs.11 This is important considering that “formal radiology reports” of plain radiographs were only generated the next day in the scenario of Davies et al.’s paper,1 which suggests that most clinical decisions were made using registrar or physician interpretations. Davies et al. do not acknowledge that undertaking a CT examination of the cervical spine in patients already in the scanner may be faster to achieve than an adequate plain radiograph. Rana et al.11 found faster times for clearing the cervical spine with CT than with plain radiographs.11 Radiologists need consensus with emergency physicians12 who face increased risks due to physical characteristics inherent to children and the inability of young children to communicate.13 CT provides a definitive diagnosis rapidly and is considered essential by emergency physicians.12 The sensitivity and specificity for cervical spine fractures should not have been provided by Davies et al. because the calculation of sensitivity requires that true positives and
http://dx.doi.org/10.1016/j.crad.2016.10.023 0009-9260/Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Andronikou S, Hussien M, Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT, Clinical Radiology (2016), http://dx.doi.org/10.1016/j.crad.2016.10.023
2
Correspondence / Clinical Radiology xxx (2016) 1e2
false negatives be known, while specificity requires that true negatives and false positives be known based on a reference standard test: not all patients underwent CT, the reference standard. Davies et al. acknowledge that occult fractures could have been missed, but present sensitivity and specificity results despite this. The low number of actual fractures also compromises the comparison of CT and plain radiography. In conclusion, Davies and colleagues fail to frame currently accepted risks and benefits of CT, provide sensitivity and specificity inappropriately, ignore the familiarity of younger radiologists with CT, and avoid presenting the pressures on emergency physicians not to miss fractures. The new NICE guidelines have been devised with a sound rationale, erring on the side of patient safety in a highstakes assessment, whilst understanding the minimal risks from CT.
References 1. Davies J, Cross S, Evanson J. Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guidelines on the use of CT. Clin Radiol 2016;71(9):844e53. 2. Brody AS, Guillerman RP. Don’t let radiation scare trump patient care: 10 ways you can harm your patients by fear of radiation-induced cancer from diagnostic imaging. Thorax 2014;69(8):782e4. 3. Ulsh BA. Are risks from medical imaging still too small to be observed or nonexistent? Dose Response 2015;13(1).
4. Guillerman RP. From “Image Gently” to image intelligently: a personalized perspective on diagnostic radiation risk. Pediatr Radiol 2014;44(Suppl. 3):444e9. 5. McCollough CH. The role of the medical physicist in managing radiation dose and communicating risk in CT. AJR Am J Roentgenol 2016;206(6):1241e4. 6. Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012;380(9840):499e505. 7. Mathews JD, Forsythe AV, Brady Z, et al. Cancer risk in 680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ 2013;346:f2360. 8. Cohen MD. CT radiation dose reduction: can we do harm by doing good? Pediatr Radiol 2012;42(4):397e8. 9. Booth TN. Cervical spine evaluation in pediatric trauma. AJR Am J Roentgenol 2012;198(5):W417e25. 10. Polk-Williams A, Carr BG, Blinman TA, et al. Cervical spine injury in young children: a National Trauma Data Bank review. J Pediatr Surg 2008;43(9):1718e21. 11. Rana AR, Drongowski R, Breckner G, et al. Traumatic cervical spine injuries: characteristics of missed injuries. J Pediatr Surg 2009;44(1):151e5. discussion 155. 12. Amis Jr ES. CT radiation dose: trending in the right direction. Radiology 2011;261(1):5e8. 13. Frush K. Why and when to use CT in children: perspective of a pediatric emergency medicine physician. Pediatr Radiol 2014;44(Suppl 3):409e13.
a
S. Andronikoua, M. Hussienb Bristol Royal Hospital for Children, Bristol, UK b
Bristol Royal Infirmary, Bristol, UK E-mail address: [email protected] (S. Andronikou)
Please cite this article in press as: Andronikou S, Hussien M, Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT, Clinical Radiology (2016), http://dx.doi.org/10.1016/j.crad.2016.10.023
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
Correspondence
Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT SirdIn the recent paper by Davies et al.,1 the new National Institute for Health and Care Excellence (NICE) guidelines are reported as “broader”,1 resulting in more cervical-spine computed tomography (CT) examinations. The main criticism of Davies et al. is levelled at the 85% of additional CT examinations of patients already in the CT scanner.1 At the core of the authors’ rationale lies a significant misrepresentation of the riskebenefit balance that CT “must always be mitigated by the desire to minimise radiation dose in paediatric patients”.1 This is supported by reports of increased risks of thyroid cancer from CT performed in childhood. The authors conclude prematurely that “to minimise thyroid radiation exposure it is therefore, important to target the use of CT to only those cases in which plain radiographs have not reliably excluded bony injury”.1 Such unwarranted concern about radiation risk, can harm a patient2 by denying them access to an examination of choice.3 Guillerman warned that “informed decision-making” “requires appropriate framing of the risks of radiation from CT” and “the benefits of imaging”.4 Considering a mortality of 40% for a missed cervical spine fracture1 “the risk of radiation-induced cancer may lose importance”.2 In June 2016, the American Journal of Roentgenology printed an acknowledgement from medical physicist, Cynthia McCullough, that the overall risk of CT is low or has non-existent risk5: “although there is a perception among some physicians and patients that the low doses of ionising radiation associated with.CT, are dangerous, this inaccurate perception is not consistent with current consensus opinions from radiation protection and medical physics organisations”.5 Biological responses to low-dose (<100 mGy) radiation do not follow the linear no-threshold model4 and use of this model for calculating individual risks is discouraged.3 The American Association of Physicists in Medicine states that “the risks of medical imaging using a radiation dose less than 50 mSv at one time or 100 mSv in multiple doses over a short period of time are too low to be detectable and may be non-existent”2,3dtypical CT head doses are 0.5e2 mSv and chest/abdomen 2e7
DOI of original article: http://dx.doi.org/10.1016/j.crad.2016.11.022.
mSv.5 Papers by Pearce et al. (2012)6 and Mathews et al. (2013),7 cited as proof of a link between CT scans and cancer, have been criticised for “a very real possibility of reverse causation in the absence of proper controls”.3 For argument’s sake, if a calculated risk is accepted, then the 0.04% radiation risk of cancer from a CT examination increases the existing risk in adulthood by very little, i.e., if 44% of males and 38% of females have a natural lifetime risk of cancer, then the additional risk from a CT will increase this to 44.04% and 38.04%, respectively.8 Imaging decisions based on the notion that cervical spine fractures in younger children occur in the upper cervical spine9 need to be reviewed considering the findings from the National Trauma Data Bank of 1,523 children <3 years of age, which showed that 48% of all cervical spine fractures involved the lower cervical spine (C5e7)10; a region possibly harder to visualise on low-quality radiographs. Davies et al. reported that only 11% of patients with inadequate radiographs underwent CT, even though inadequate radiographs were in the majority.1 Rana et al.11 report that the major contributors to the poor performance of plain cervical spine radiographs are low radiographic quality and errors of interpretation. They also reported that 28% of cervical spine fractures would have been missed on plain radiographs.11 This is important considering that “formal radiology reports” of plain radiographs were only generated the next day in the scenario of Davies et al.’s paper,1 which suggests that most clinical decisions were made using registrar or physician interpretations. Davies et al. do not acknowledge that undertaking a CT examination of the cervical spine in patients already in the scanner may be faster to achieve than an adequate plain radiograph. Rana et al.11 found faster times for clearing the cervical spine with CT than with plain radiographs.11 Radiologists need consensus with emergency physicians12 who face increased risks due to physical characteristics inherent to children and the inability of young children to communicate.13 CT provides a definitive diagnosis rapidly and is considered essential by emergency physicians.12 The sensitivity and specificity for cervical spine fractures should not have been provided by Davies et al. because the calculation of sensitivity requires that true positives and
http://dx.doi.org/10.1016/j.crad.2016.10.023 0009-9260/Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Andronikou S, Hussien M, Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT, Clinical Radiology (2016), http://dx.doi.org/10.1016/j.crad.2016.10.023
2
Correspondence / Clinical Radiology xxx (2016) 1e2
false negatives be known, while specificity requires that true negatives and false positives be known based on a reference standard test: not all patients underwent CT, the reference standard. Davies et al. acknowledge that occult fractures could have been missed, but present sensitivity and specificity results despite this. The low number of actual fractures also compromises the comparison of CT and plain radiography. In conclusion, Davies and colleagues fail to frame currently accepted risks and benefits of CT, provide sensitivity and specificity inappropriately, ignore the familiarity of younger radiologists with CT, and avoid presenting the pressures on emergency physicians not to miss fractures. The new NICE guidelines have been devised with a sound rationale, erring on the side of patient safety in a highstakes assessment, whilst understanding the minimal risks from CT.
References 1. Davies J, Cross S, Evanson J. Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guidelines on the use of CT. Clin Radiol 2016;71(9):844e53. 2. Brody AS, Guillerman RP. Don’t let radiation scare trump patient care: 10 ways you can harm your patients by fear of radiation-induced cancer from diagnostic imaging. Thorax 2014;69(8):782e4. 3. Ulsh BA. Are risks from medical imaging still too small to be observed or nonexistent? Dose Response 2015;13(1).
4. Guillerman RP. From “Image Gently” to image intelligently: a personalized perspective on diagnostic radiation risk. Pediatr Radiol 2014;44(Suppl. 3):444e9. 5. McCollough CH. The role of the medical physicist in managing radiation dose and communicating risk in CT. AJR Am J Roentgenol 2016;206(6):1241e4. 6. Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012;380(9840):499e505. 7. Mathews JD, Forsythe AV, Brady Z, et al. Cancer risk in 680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ 2013;346:f2360. 8. Cohen MD. CT radiation dose reduction: can we do harm by doing good? Pediatr Radiol 2012;42(4):397e8. 9. Booth TN. Cervical spine evaluation in pediatric trauma. AJR Am J Roentgenol 2012;198(5):W417e25. 10. Polk-Williams A, Carr BG, Blinman TA, et al. Cervical spine injury in young children: a National Trauma Data Bank review. J Pediatr Surg 2008;43(9):1718e21. 11. Rana AR, Drongowski R, Breckner G, et al. Traumatic cervical spine injuries: characteristics of missed injuries. J Pediatr Surg 2009;44(1):151e5. discussion 155. 12. Amis Jr ES. CT radiation dose: trending in the right direction. Radiology 2011;261(1):5e8. 13. Frush K. Why and when to use CT in children: perspective of a pediatric emergency medicine physician. Pediatr Radiol 2014;44(Suppl 3):409e13.
a
S. Andronikoua, M. Hussienb Bristol Royal Hospital for Children, Bristol, UK b
Bristol Royal Infirmary, Bristol, UK E-mail address: [email protected] (S. Andronikou)
Please cite this article in press as: Andronikou S, Hussien M, Re: Radiological assessment of paediatric cervical spine injury in blunt trauma: the potential impact of new NICE guideline on the use of CT, Clinical Radiology (2016), http://dx.doi.org/10.1016/j.crad.2016.10.023