- Email: [email protected]
Choice of biopsy devices for post-mortem CT-guided biopsy
Journal of Forensic Radiology and Imaging 5 (2016) 15–19
Contents lists available at ScienceDirect
Journal of Forensic Radiology and Imaging journal homepage: www.elsevier.com/locate/jofri
Technical note
Choice of biopsy devices for post-mortem CT-guided biopsy Samantha Higgins a,b,c,n, Sarah Parsons a,b, Noel Woodford a,b, Christopher Briggs a,b,c, David Cauchi a,b, Chris O’Donnell a,b a
Victorian Institute of Forensic Medicine, 65 Kavanagh St, Southbank, Victoria 3006, Australia Department of Forensic Medicine, Monash University, 65 Kavanagh St, Southbank, Victoria 3006, Australia c Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia b
art ic l e i nf o
a b s t r a c t
Article history: Received 31 August 2015 Received in revised form 24 November 2015 Accepted 8 December 2015 Available online 9 December 2015
Aim: To assess technical features of multiple biopsy devices for post-mortem CT-guided biopsy (PMCTB). Methods: Five different BARDs clinical biopsy devices, including spring-loaded and vacuum-assisted, were used to perform percutaneous biopsy of the liver in a deceased person using the largest gauge needle size available in each. A standard co-axial biopsy technique was used for all devices except SenoRXs. Specimens were placed on sponge in cassettes for initial fixation and then processed using routine histological techniques. The devices were assessed by a team consisting of a forensic technician, forensic radiologist and two forensic pathologists (one blinded to the type of device used). Assessment parameters included technical performance, cost of device, and specimen review under light microscopy. Results/discussion: The Max-cores and Magnums devices were mechanically easy to load, fire and retrieve specimens. The Finesses and Vacoras provided advanced technical features. On histological review the tissue sample from the Vacoras was judged to be of higher quality. Due to the permanent needle attachment to the vacuum machine, the SenoRXs was deemed impractical. Histological artefacts identified included stretch-crush cellular damage likely from the use of vacuum-assisted devices, and tissue breakage from the use of cassette sponges. Conclusion: The 2 spring-loaded biopsy devices are considered the most appropriate for PMCTB tissue sampling based on ease-of-use, lowest cost and provision of diagnosable biopsy specimens. & 2015 Elsevier Ltd. All rights reserved.
Keywords: Post-mortem biopsy CT biopsy Post-mortem histology Histology artefact
1. Introduction Post-mortem CT-guided biopsy (PMCTB) is an established, minimally invasive technique for tissue or fluid sampling. It is used as a supplement to minimally invasive autopsy or as an alternative where there is family objection to autopsy [1–3]. Biopsy devices used in PMCTB have been developed specifically for clinical practice and to date there has been no systematic analysis of their use in the deceased. Factors that need to be considered include changes to body tissue after death and the ability to use larger diameter sampling needles. Previous clinical biopsy studies have highlighted the importance of device selection in determining quality of the histological specimen and the potential for needle mechanical artefacts [4,5]. The aim of this study was to assess a Abbreviations: PMCTB, Post-mortem computed tomography biopsy n Corresponding author at: Victorian Institute of Forensic Medicine, 65 Kavanagh St, Southbank, Victoria 3006, Australia. E-mail address: [email protected] (S. Higgins). http://dx.doi.org/10.1016/j.jofri.2015.12.005 2212-4780/& 2015 Elsevier Ltd. All rights reserved.
range of modern clinical biopsy devices to establish the most appropriate for use in PMCTB.
2. Methods 2.1. Ethics University and Institution approval was obtained (University of Melbourne Ethics ID 1238028 and VIFM 8/2012). A recently deceased, non-decomposed cadaver donated for medical science was used for this study. 2.2. Biopsy devices Five BARDs clinical biopsy devices (C.R. BARD Inc., Covington, GA, USA) including spring-loaded and vacuum-assisted were used for post-mortem liver sampling using the largest available needle gauge in each (Table 1). Needle gauge (G) sizes included 10 G, 12 G
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
and 14 G (Birmingham Iron Wire Gauge aka Stubbs Iron Wire Gauge system; 3.4 mm, 2.8 mm and 2.1 mm outer diameter respectively). 2.3. Imaging Toshiba 16-slice multidetector CT-scanner (Aquilion16s Toshiba Medical Systems, Minato-ku, Tokyo, Japan). 2.4. Sample collection Performed by forensic technician using a standard co-axial ‘step and shoot’ biopsy technique, except for SenoRXs where a coaxial needle is not required (Fig. 1). CT-guided needle puncture into the right lobe of liver (via the 5th intercostal space initially) with subsequent needles inserted caudal to the previous. Needle entries were parallel to the axial plane in order to avoid biopsy path crossover. Each biopsy core was placed in individual spongelined cassettes, fixed immediately in 10% neutral-buffered formalin and processed using standard histological techniques [6]. 2.5. Assessment parameters
1) Technical performance: Ease-of-use was evaluated by a forensic technician without previous biopsy experience. Assessment was subjective and based upon simplicity of the device for tissue collection and placement using CT- guidance. A radiologist (with over 25 years of clinical biopsy experience) was consulted for technical expertise when required. Skin defect size was measured and puncture wounds were monitored for fluid leak post-biopsy. 2) Approximate device cost provided by BARDs staff at the time of assessment. 3) Histological review using light microscopy by two forensic pathologists (10 years and 18 years anatomical/forensic pathology experience), one of whom was blinded to device types. For each parameter the evaluator(s) ranked devices in order of preference, and scores were cumulated (Table 2).
c
b
a
All samples showed signs of damage due to the cassette sponge. Larger gauge released onto market post study. Feature not tested in this study.
3. Results
Key.
∼$25,000 Complex to use. CT ‘step and shoot’ technique not possible. SenoRXs [10 G; 10 cm]
∼$16,000 Vacoras [10 G; 10 cm]
∼$8000
Chamber allowed for excellent visualization of tissue core but difficult removal of tissue from the chamber has the potential cause for histological artefact Auto-ejection of specimen feature minimized tissue handling
Reusable vacuum-assisted device and disposable needle with sample viewing chamber and multiple sampling featurec Reusable vacuum-assisted device and disposable needle with auto-ejection of tissue and multiple sampling featurec Reusable free-standing vacuum machine and disposable needle Finesse
s
b
[14 G ; 10 cm]
∼$3000 Mechanically easy to load, fire and retrieve specimen Reusable spring-loaded device and disposable needle
Narrow specimen Adequate for assessment Narrow specimen Adequate for assessment Narrow specimen Stretch/crush artefact Thick specimen Adequate for assessment Thick specimen Minor stretch/crush artefact Mechanically easy to load, fire and retrieve specimen Disposable spring-loaded device and attached needle
Max-cores [14 Gb; 10 cm] Magnums [12 G; 16 cm]
∼$40
Technical findings Technical summary Device [Needle Gauge; Length]
Table 1 Summary of primary findings of PMCTB analysis using 5 BARDs biopsy devices.
Unit cost (AUD) Primary histological findingsa
16
A summary of results is provided in Table 1. During the assessment of technical performance, the Max-cores and Magnums performed similarly, with the Magnums judged the preferred device due to the availability of a needle 16 cm in length. The Finesses and Vacoras were of similar complexity to use and provided similar technical features (Table 1). As the SenoRXs device comprised a heavy needle and cord permanently attached to a large freestanding machine it was deemed impractical for use in the ‘step-and-shoot’ PMCTB technique. Skin defects corresponded proportionally to needle gauge size (Fig. 2). All defects were considered to be in line with expectations of a minimally invasive biopsy procedure and they did not require reconstruction stitching. No body fluid leak from the five biopsy sites was apparent. Histological review revealed stretch/crush artefact including elongation of cells and nuclei in the tissue collected from 2 of the vacuum-assisted devices. Occasional histological processing artefacts were seen in the specimens, including folds, air bubbles and knife lines. Break of specimen and an intermittent patterned triangle artefact at some specimen edges were considered a result of fixation in the sponge-cassettes. The liver tissue exhibited no additional pathological findings.
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
17
Max-Core ®
Magnum®
Finesse®
Vacora®
SenoRX®
Fig. 1. Two-dimensional axial CT image of each device in position in the liver prior to sample collection, alongside picture of each device in use.
Table 2 Ranking of five BARDs biopsy devices used for the assessment of the most appropriate device for PMCTB. Device
Max-cores Magnums Finesses Vacoras SenoRXs
Parameters Technical performance
Unit cost Histology review Pathologist 1 (Non-blind)
Histology review Pathologist 2 (Blind)
Cumulative Scorea
2 1 3 4 5
1 2 3 4 5
1 2 5 3 4
5 9 16 13 17
1 4 5 2 3
Key. a
Lowest accumulative scores indicate preferred devices.
Rank order evaluation of the devices is provided in Table 2. The cumulative scores provided semi-quantitative results as to overall device performance. At histological review the pathologists agreed that tissue from Max-cores was superior to all others in terms of adequate specimen size, number of central veins and portal tracts. There was also agreement that tissue from Finesses was the least preferred due to the thin specimen size and lack of portal tracts. Of the three devices remaining, the pathologist rankings differed slightly. Findings likely to have influenced the rank differences included the small size of the
Fig. 2. Device insertion points into lateral right torso with corresponding Gauge (defects measured in cm). Device order from left to right was Max-cores; Magnums; Finesses; Vacoras; SenoRXs.
Magnums sample (Pathologist 1) and the detection of an undesirable stretch/crush artefact in tissue collected with the Finesses and SenoRXs devices (Pathologist 2) (Fig. 3).
18
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
Fig. 3. Stretch/crush artefact including elongation of cells and nuclei in liver sampled with Finesses thought to be as a result of the suction of the vacuumassisted device (hematoxylin and eosin stain, 40 magnification).
Cost evaluation included consideration of initial device (Table 1) and ongoing consumable costs of Max-cores and Magnums devices (respective costs of ∼AU$22 for co-axial, and ∼AU$46 for co-axial and the disposable needle). As device consumables were considered relatively inexpensive overall, cost rankings were allocated in order of least to most expensive according to device cost.
4. Discussion Our examination of five clinical biopsy devices revealed that due to their ease-of-use, low cost and adequate tissue specimens, the two spring-loaded devices were the most appropriate for PMCTB compared with the more complex, vacuum-assisted devices. Post-mortem biopsy equipment choice is typically based on cost or availability of devices, previous clinical success, and experience or research interests of the operator(s) [2,7–11]. Undergoing a systematic analysis for the selection of a biopsy device proved critical in the implementation of PMCTB at our institute. Biopsy device mechanics have the potential to produce undesirable histological artefacts. Pathological review revealed stretch/crush effect on tissues from 2 of the vacuum-assisted devices (Fig. 3). These vacuum-assisted devices are relatively new in clinical practice thus there is limited understanding of the effects, if any, of the suction mechanism on tissues after death [12]. The stretch/crush artefacts seen were unique compared with the other histological artefacts detected, and a study with increased sample numbers is recommended to further evaluate the vacuum-assisted devices in PMCTB sampling. Sample handling of the specimens and type of cassette used for PMCTB play a role in the overall histological quality [4,5]. Use of sponge-cassettes for initial tissue fixation of all samples resulted in difficulty removing the small fixed biopsy samples from the sponge without breakage. Subsequent to this finding fine-mesh cassettes have been used for PMCTB at our institute with no further tissue disruption. Evaluation of ease-of-use for PMCTB revealed the SenoRXs to be impractical due to the permanent connection of the needle to the vacuum machine. The accuracy of placement in the liver was reduced as the needle tip moved from the initial point of placement due to the heavy needle and cord weight. As a co-axial needle was not available, the needle was inserted into the liver and ‘step and shoot’ imaging was performed while the needle
remained attached to the machine. Placing the body into the CTgantry with needle and cord attached reduced the ability to retrieve a 2D image confirming the needle tip was in the desired location. The SenoRXs device is designed to be used in clinical breast biopsy sampling, and would require modifications for PMCTB of internal organs. During sampling with the Finesses device the liver core retracted (Fig. 1) and required diligent removal of the tissue from the chamber. It is hypothesized that soft post-mortem liver tissue behaves differently compared to clinical sampling. Due to the potential for introduction of histological artefact, further testing of this feature for post-mortem tissue sampling is recommended. The auto-ejection of tissue was a desirable feature of the Vacoras device as it removed all manual handling of the sample, reducing mechanical artefact. The Magnums and the Max-cores devices were easy-to-use for co-axial ‘step and shoot’ sampling, and tissue retrieval and dispensing into the histology cassette did not appear to introduce mechanical artefact. The Magnums was the preferred in overall technical performance as it offered the longest needle size (16 cm) at the time. It is envisaged that needle length will be necessary for PMCTB sampling in overweight individuals or sampling of deep internal organs such as the kidney. The devices were tested using the largest gauge needle available at the time. Skin defects were minor with no fluid leak and therefore no reconstruction stitching was required. At most a tape dressing may be required for aesthetics or leak as decomposition progresses. As expected, tissue collected with the larger gauge needle corresponded to larger tissue samples under the microscope. This is likely to have influenced the pathologist assessments (Table 2). However, in comparison to clinical examinations that are constrained by patient safety, post-mortem sampling can utilize a larger needle caliber with minimal disadvantage. Between 18Gauge to 14-Gauge needle caliber has previously been recommended for post-mortem biopsy procedures [7–9,13,14]. Our results suggest that even larger needle calibers should be considered for post-mortem sampling. Following this study, we have successfully implemented the BARDs Magnums device using a 12-Gauge needle for PMCTB in our institute. Cost rank was allocated in order of least to most expensive according to outright device cost (Table 2). Although cost evaluation included consideration of ongoing consumable costs, these were estimated to be relatively low given that PMCTB is intended for occasional case sampling at our institute. Unlike in clinical practice, post-mortem biopsy consumables can theoretically be reused for multi-organ case sampling or shared across cases, contributing to minimum overall consumable costs. For cases where infectious diseases are suspected or known, an inexpensive, disposable device and needle (such as the Max-cores) is most appropriate for PMCTB sampling. 4.1. Limitations Technician inexperience was mitigated by technical support from BARDs equipment specialists and an experienced clinical radiologist closely supervising device manipulation and CT biopsy techniques. Review bias likely contributed to pathologist disagreement (Table 2), as pathologist 1 was not blinded to the device type. Other limitations in this study include use of a single cadaveric specimen, single organ (liver with no specific pathology) sampling, presence of occasional histological processing artefacts, and reliance on subjective analysis. Nevertheless, systematic analysis of biopsy equipment tailored towards specific sampling requirements proved fruitful, and our results indicate that equipment evaluation prior to the implementation of PMCTB into forensic practice is essential.
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
5. Conclusions The 2 spring-loaded biopsy devices (Max-cores and Magnums) ranked highest for PMCTB tissue sampling in the liver based on technical performance, cost and quality of histological specimens. A major source of histological artefact in all specimens was fragmentation induced by the cassette sponge. Spongeless cassettes are now used at our institute for all PMCTB specimens.
Conflict of interest BARDs provided the 5 devices free-of-charge and on-site technical advice at the time of the experiment. BARDs did not contribute to the evaluation of the devices or preparation of this manuscript.
Acknowledgements Clair Richards for photography expertise, and the VIFM Histology staff for ongoing histological support.
References [1] B. Huston, N. Malouf, H. Azar, Percutaneous needle autopsy sampling, Mod. Pathol. 9 (1996) 1101–1107.
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[2] S. Ross, et al., Sudden death after chest pain: feasibility of virtual autopsy with postmortem CT angiography and biopsy, Radiology 264 (1) (2012) 250–259. [3] A. Weustink, et al., Minimally invasive autopsy: an alternative to conventional autopsy? Radiology 250 (3) (2009) 897–904. [4] P. Walker, T. Cavallo, S. Bonsib, Practice guidelines for the renal biopsy, Mod. Path 17 (2004) 1555–1563. [5] C. Mladinich, et al., Evaluation and comparison of automated biopsy devices: work in progress, Radiology 184 (3) (1992) 845–847. [6] J. Bancroft, M. Gamble, Theory and Practice Of Histological Techniques, 6th ed., Churchill Livingstone, Edinburgh, 2008. [7] E. Aghayev, et al., Post-mortem tissue sampling using computed tomography guidance, Sci. Int. 166 (2–3) (2007) 199–203. [8] E. Aghayev, et al., CT data-based navigation for post-mortem biopsy-a feasibility study, J. Forensic Leg. Med. 15 (6) (2008) 382–387. [9] S. Bolliger, et al., Postmortem imaging-guided biopsy as an adjuvant to minimally invasive autopsy with CT and postmortem angiography: a feasibility study, Am. J. Roentgenol. 195 (5) (2010) 1051–1056. [10] L. Filograna, et al., Diagnosis of fatal pulmonary fat embolism with minimally invasive virtual autopsy and post-mortem biopsy, Leg. Med. 12 (5) (2010) 233–237. [11] R.M. Martinez, et al., CT-guided, minimally invasive, postmortem needle biopsy using the B-Rob II needle-positioning robot, Forensic Sci. 59 (2) (2014) 517–521. [12] G. Crisi, L. Pantanowitz, C. Otis, Mammotome footprints: histologic artefacts in the era of stereotactic vacuum mammotome biopsy, Int. J. Surg. Pathol. 14 (3) (2006) 221–222. [13] L. Filograna, et al., A minimally invasive technique for the detection and analysis of pulmonary fat embolism: a feasibility study, J. Forensic Sci. 57 (5) (2012) 1329–1335. [14] In: M. Thali, M. Viner, B.E. Brogdon, (eds.), Brogdon's Forensic Radiology, 2nd ed., CRC Press, Boca Raton, 2011.
Contents lists available at ScienceDirect
Journal of Forensic Radiology and Imaging journal homepage: www.elsevier.com/locate/jofri
Technical note
Choice of biopsy devices for post-mortem CT-guided biopsy Samantha Higgins a,b,c,n, Sarah Parsons a,b, Noel Woodford a,b, Christopher Briggs a,b,c, David Cauchi a,b, Chris O’Donnell a,b a
Victorian Institute of Forensic Medicine, 65 Kavanagh St, Southbank, Victoria 3006, Australia Department of Forensic Medicine, Monash University, 65 Kavanagh St, Southbank, Victoria 3006, Australia c Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia b
art ic l e i nf o
a b s t r a c t
Article history: Received 31 August 2015 Received in revised form 24 November 2015 Accepted 8 December 2015 Available online 9 December 2015
Aim: To assess technical features of multiple biopsy devices for post-mortem CT-guided biopsy (PMCTB). Methods: Five different BARDs clinical biopsy devices, including spring-loaded and vacuum-assisted, were used to perform percutaneous biopsy of the liver in a deceased person using the largest gauge needle size available in each. A standard co-axial biopsy technique was used for all devices except SenoRXs. Specimens were placed on sponge in cassettes for initial fixation and then processed using routine histological techniques. The devices were assessed by a team consisting of a forensic technician, forensic radiologist and two forensic pathologists (one blinded to the type of device used). Assessment parameters included technical performance, cost of device, and specimen review under light microscopy. Results/discussion: The Max-cores and Magnums devices were mechanically easy to load, fire and retrieve specimens. The Finesses and Vacoras provided advanced technical features. On histological review the tissue sample from the Vacoras was judged to be of higher quality. Due to the permanent needle attachment to the vacuum machine, the SenoRXs was deemed impractical. Histological artefacts identified included stretch-crush cellular damage likely from the use of vacuum-assisted devices, and tissue breakage from the use of cassette sponges. Conclusion: The 2 spring-loaded biopsy devices are considered the most appropriate for PMCTB tissue sampling based on ease-of-use, lowest cost and provision of diagnosable biopsy specimens. & 2015 Elsevier Ltd. All rights reserved.
Keywords: Post-mortem biopsy CT biopsy Post-mortem histology Histology artefact
1. Introduction Post-mortem CT-guided biopsy (PMCTB) is an established, minimally invasive technique for tissue or fluid sampling. It is used as a supplement to minimally invasive autopsy or as an alternative where there is family objection to autopsy [1–3]. Biopsy devices used in PMCTB have been developed specifically for clinical practice and to date there has been no systematic analysis of their use in the deceased. Factors that need to be considered include changes to body tissue after death and the ability to use larger diameter sampling needles. Previous clinical biopsy studies have highlighted the importance of device selection in determining quality of the histological specimen and the potential for needle mechanical artefacts [4,5]. The aim of this study was to assess a Abbreviations: PMCTB, Post-mortem computed tomography biopsy n Corresponding author at: Victorian Institute of Forensic Medicine, 65 Kavanagh St, Southbank, Victoria 3006, Australia. E-mail address: [email protected] (S. Higgins). http://dx.doi.org/10.1016/j.jofri.2015.12.005 2212-4780/& 2015 Elsevier Ltd. All rights reserved.
range of modern clinical biopsy devices to establish the most appropriate for use in PMCTB.
2. Methods 2.1. Ethics University and Institution approval was obtained (University of Melbourne Ethics ID 1238028 and VIFM 8/2012). A recently deceased, non-decomposed cadaver donated for medical science was used for this study. 2.2. Biopsy devices Five BARDs clinical biopsy devices (C.R. BARD Inc., Covington, GA, USA) including spring-loaded and vacuum-assisted were used for post-mortem liver sampling using the largest available needle gauge in each (Table 1). Needle gauge (G) sizes included 10 G, 12 G
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
and 14 G (Birmingham Iron Wire Gauge aka Stubbs Iron Wire Gauge system; 3.4 mm, 2.8 mm and 2.1 mm outer diameter respectively). 2.3. Imaging Toshiba 16-slice multidetector CT-scanner (Aquilion16s Toshiba Medical Systems, Minato-ku, Tokyo, Japan). 2.4. Sample collection Performed by forensic technician using a standard co-axial ‘step and shoot’ biopsy technique, except for SenoRXs where a coaxial needle is not required (Fig. 1). CT-guided needle puncture into the right lobe of liver (via the 5th intercostal space initially) with subsequent needles inserted caudal to the previous. Needle entries were parallel to the axial plane in order to avoid biopsy path crossover. Each biopsy core was placed in individual spongelined cassettes, fixed immediately in 10% neutral-buffered formalin and processed using standard histological techniques [6]. 2.5. Assessment parameters
1) Technical performance: Ease-of-use was evaluated by a forensic technician without previous biopsy experience. Assessment was subjective and based upon simplicity of the device for tissue collection and placement using CT- guidance. A radiologist (with over 25 years of clinical biopsy experience) was consulted for technical expertise when required. Skin defect size was measured and puncture wounds were monitored for fluid leak post-biopsy. 2) Approximate device cost provided by BARDs staff at the time of assessment. 3) Histological review using light microscopy by two forensic pathologists (10 years and 18 years anatomical/forensic pathology experience), one of whom was blinded to device types. For each parameter the evaluator(s) ranked devices in order of preference, and scores were cumulated (Table 2).
c
b
a
All samples showed signs of damage due to the cassette sponge. Larger gauge released onto market post study. Feature not tested in this study.
3. Results
Key.
∼$25,000 Complex to use. CT ‘step and shoot’ technique not possible. SenoRXs [10 G; 10 cm]
∼$16,000 Vacoras [10 G; 10 cm]
∼$8000
Chamber allowed for excellent visualization of tissue core but difficult removal of tissue from the chamber has the potential cause for histological artefact Auto-ejection of specimen feature minimized tissue handling
Reusable vacuum-assisted device and disposable needle with sample viewing chamber and multiple sampling featurec Reusable vacuum-assisted device and disposable needle with auto-ejection of tissue and multiple sampling featurec Reusable free-standing vacuum machine and disposable needle Finesse
s
b
[14 G ; 10 cm]
∼$3000 Mechanically easy to load, fire and retrieve specimen Reusable spring-loaded device and disposable needle
Narrow specimen Adequate for assessment Narrow specimen Adequate for assessment Narrow specimen Stretch/crush artefact Thick specimen Adequate for assessment Thick specimen Minor stretch/crush artefact Mechanically easy to load, fire and retrieve specimen Disposable spring-loaded device and attached needle
Max-cores [14 Gb; 10 cm] Magnums [12 G; 16 cm]
∼$40
Technical findings Technical summary Device [Needle Gauge; Length]
Table 1 Summary of primary findings of PMCTB analysis using 5 BARDs biopsy devices.
Unit cost (AUD) Primary histological findingsa
16
A summary of results is provided in Table 1. During the assessment of technical performance, the Max-cores and Magnums performed similarly, with the Magnums judged the preferred device due to the availability of a needle 16 cm in length. The Finesses and Vacoras were of similar complexity to use and provided similar technical features (Table 1). As the SenoRXs device comprised a heavy needle and cord permanently attached to a large freestanding machine it was deemed impractical for use in the ‘step-and-shoot’ PMCTB technique. Skin defects corresponded proportionally to needle gauge size (Fig. 2). All defects were considered to be in line with expectations of a minimally invasive biopsy procedure and they did not require reconstruction stitching. No body fluid leak from the five biopsy sites was apparent. Histological review revealed stretch/crush artefact including elongation of cells and nuclei in the tissue collected from 2 of the vacuum-assisted devices. Occasional histological processing artefacts were seen in the specimens, including folds, air bubbles and knife lines. Break of specimen and an intermittent patterned triangle artefact at some specimen edges were considered a result of fixation in the sponge-cassettes. The liver tissue exhibited no additional pathological findings.
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
17
Max-Core ®
Magnum®
Finesse®
Vacora®
SenoRX®
Fig. 1. Two-dimensional axial CT image of each device in position in the liver prior to sample collection, alongside picture of each device in use.
Table 2 Ranking of five BARDs biopsy devices used for the assessment of the most appropriate device for PMCTB. Device
Max-cores Magnums Finesses Vacoras SenoRXs
Parameters Technical performance
Unit cost Histology review Pathologist 1 (Non-blind)
Histology review Pathologist 2 (Blind)
Cumulative Scorea
2 1 3 4 5
1 2 3 4 5
1 2 5 3 4
5 9 16 13 17
1 4 5 2 3
Key. a
Lowest accumulative scores indicate preferred devices.
Rank order evaluation of the devices is provided in Table 2. The cumulative scores provided semi-quantitative results as to overall device performance. At histological review the pathologists agreed that tissue from Max-cores was superior to all others in terms of adequate specimen size, number of central veins and portal tracts. There was also agreement that tissue from Finesses was the least preferred due to the thin specimen size and lack of portal tracts. Of the three devices remaining, the pathologist rankings differed slightly. Findings likely to have influenced the rank differences included the small size of the
Fig. 2. Device insertion points into lateral right torso with corresponding Gauge (defects measured in cm). Device order from left to right was Max-cores; Magnums; Finesses; Vacoras; SenoRXs.
Magnums sample (Pathologist 1) and the detection of an undesirable stretch/crush artefact in tissue collected with the Finesses and SenoRXs devices (Pathologist 2) (Fig. 3).
18
S. Higgins et al. / Journal of Forensic Radiology and Imaging 5 (2016) 15–19
Fig. 3. Stretch/crush artefact including elongation of cells and nuclei in liver sampled with Finesses thought to be as a result of the suction of the vacuumassisted device (hematoxylin and eosin stain, 40 magnification).
Cost evaluation included consideration of initial device (Table 1) and ongoing consumable costs of Max-cores and Magnums devices (respective costs of ∼AU$22 for co-axial, and ∼AU$46 for co-axial and the disposable needle). As device consumables were considered relatively inexpensive overall, cost rankings were allocated in order of least to most expensive according to device cost.
4. Discussion Our examination of five clinical biopsy devices revealed that due to their ease-of-use, low cost and adequate tissue specimens, the two spring-loaded devices were the most appropriate for PMCTB compared with the more complex, vacuum-assisted devices. Post-mortem biopsy equipment choice is typically based on cost or availability of devices, previous clinical success, and experience or research interests of the operator(s) [2,7–11]. Undergoing a systematic analysis for the selection of a biopsy device proved critical in the implementation of PMCTB at our institute. Biopsy device mechanics have the potential to produce undesirable histological artefacts. Pathological review revealed stretch/crush effect on tissues from 2 of the vacuum-assisted devices (Fig. 3). These vacuum-assisted devices are relatively new in clinical practice thus there is limited understanding of the effects, if any, of the suction mechanism on tissues after death [12]. The stretch/crush artefacts seen were unique compared with the other histological artefacts detected, and a study with increased sample numbers is recommended to further evaluate the vacuum-assisted devices in PMCTB sampling. Sample handling of the specimens and type of cassette used for PMCTB play a role in the overall histological quality [4,5]. Use of sponge-cassettes for initial tissue fixation of all samples resulted in difficulty removing the small fixed biopsy samples from the sponge without breakage. Subsequent to this finding fine-mesh cassettes have been used for PMCTB at our institute with no further tissue disruption. Evaluation of ease-of-use for PMCTB revealed the SenoRXs to be impractical due to the permanent connection of the needle to the vacuum machine. The accuracy of placement in the liver was reduced as the needle tip moved from the initial point of placement due to the heavy needle and cord weight. As a co-axial needle was not available, the needle was inserted into the liver and ‘step and shoot’ imaging was performed while the needle
remained attached to the machine. Placing the body into the CTgantry with needle and cord attached reduced the ability to retrieve a 2D image confirming the needle tip was in the desired location. The SenoRXs device is designed to be used in clinical breast biopsy sampling, and would require modifications for PMCTB of internal organs. During sampling with the Finesses device the liver core retracted (Fig. 1) and required diligent removal of the tissue from the chamber. It is hypothesized that soft post-mortem liver tissue behaves differently compared to clinical sampling. Due to the potential for introduction of histological artefact, further testing of this feature for post-mortem tissue sampling is recommended. The auto-ejection of tissue was a desirable feature of the Vacoras device as it removed all manual handling of the sample, reducing mechanical artefact. The Magnums and the Max-cores devices were easy-to-use for co-axial ‘step and shoot’ sampling, and tissue retrieval and dispensing into the histology cassette did not appear to introduce mechanical artefact. The Magnums was the preferred in overall technical performance as it offered the longest needle size (16 cm) at the time. It is envisaged that needle length will be necessary for PMCTB sampling in overweight individuals or sampling of deep internal organs such as the kidney. The devices were tested using the largest gauge needle available at the time. Skin defects were minor with no fluid leak and therefore no reconstruction stitching was required. At most a tape dressing may be required for aesthetics or leak as decomposition progresses. As expected, tissue collected with the larger gauge needle corresponded to larger tissue samples under the microscope. This is likely to have influenced the pathologist assessments (Table 2). However, in comparison to clinical examinations that are constrained by patient safety, post-mortem sampling can utilize a larger needle caliber with minimal disadvantage. Between 18Gauge to 14-Gauge needle caliber has previously been recommended for post-mortem biopsy procedures [7–9,13,14]. Our results suggest that even larger needle calibers should be considered for post-mortem sampling. Following this study, we have successfully implemented the BARDs Magnums device using a 12-Gauge needle for PMCTB in our institute. Cost rank was allocated in order of least to most expensive according to outright device cost (Table 2). Although cost evaluation included consideration of ongoing consumable costs, these were estimated to be relatively low given that PMCTB is intended for occasional case sampling at our institute. Unlike in clinical practice, post-mortem biopsy consumables can theoretically be reused for multi-organ case sampling or shared across cases, contributing to minimum overall consumable costs. For cases where infectious diseases are suspected or known, an inexpensive, disposable device and needle (such as the Max-cores) is most appropriate for PMCTB sampling. 4.1. Limitations Technician inexperience was mitigated by technical support from BARDs equipment specialists and an experienced clinical radiologist closely supervising device manipulation and CT biopsy techniques. Review bias likely contributed to pathologist disagreement (Table 2), as pathologist 1 was not blinded to the device type. Other limitations in this study include use of a single cadaveric specimen, single organ (liver with no specific pathology) sampling, presence of occasional histological processing artefacts, and reliance on subjective analysis. Nevertheless, systematic analysis of biopsy equipment tailored towards specific sampling requirements proved fruitful, and our results indicate that equipment evaluation prior to the implementation of PMCTB into forensic practice is essential.
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5. Conclusions The 2 spring-loaded biopsy devices (Max-cores and Magnums) ranked highest for PMCTB tissue sampling in the liver based on technical performance, cost and quality of histological specimens. A major source of histological artefact in all specimens was fragmentation induced by the cassette sponge. Spongeless cassettes are now used at our institute for all PMCTB specimens.
Conflict of interest BARDs provided the 5 devices free-of-charge and on-site technical advice at the time of the experiment. BARDs did not contribute to the evaluation of the devices or preparation of this manuscript.
Acknowledgements Clair Richards for photography expertise, and the VIFM Histology staff for ongoing histological support.
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