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Reducing the Dose for CT-guided Spine Biopsies: Let’s Shift the Paradigm 2014

Category Interventional Katya Shpilberg, MD
Bradley Delman, MD
Steven Esses, MD
Lawrence N. Tanenbaum, MD, FACR
Raja Subramaniam, PhD
Amish Doshi, MD
Purpose Imaging-guided biopsies are a commonly used method to obtain tissue sample for diagnosis in suspected cases of malignancy. In particular, CT guidance provides a reliable method of image guidance for spinal lesions. The purpose of this study is to demonstrate that using a low-dose (LD) protocol for CT guided spine biopsies can be as effective in tissue sampling, procedural time and complication rate as a regular-dose (RD) protocol. Materials & Methods After obtaining Institutional Review Board approval, we retrospectively reviewed all patients who underwent CT-guided spine procedures at our institution between May 2010 and October 2013. Patients who underwent disc space aspirations for suspected discitis/osteomyelitis and spinal pain injections were excluded. Patients for whom dose reports were not available in our institution's PACS were excluded. 64 patients were included. The following data was recorded: age, gender, lesion biopsied, kVp, mAs, pitch, CT dose index (CTDIvol) per series (mGy), total CTDIvol, dose length product (DLP) per series (mGy-cm), scan range (mm), total DLP, number of biopsy-guiding scans, number of pre- and post- biopsy diagnostic scans, number of needle passes, total number of scans, duration of each biopsy, pathology results and complications. LD biopsies were defined as those with a kVp of 80, mAs of 40-60 and pitch of 0.875-1.35. RD biopsies were defined as those with a kVp of 120 and mAs >200. Scans performed at kVp and mAs parameters outside the above mentioned criteria for LD and RD biopsies were classified based on average CTDIvol (CTDIvol 10mGy RD). Age, biopsy duration, total number of scans, total CTDIvol and total DLP of LD and RD groups were compared using unpaired t-test. Diagnostic tissue yield was compared using Fisher exact test. P Results 31 patients underwent LD CT-guided spine biopsies and 33 patients underwent RD biopsies. There was no significant difference in patient age between the two groups (64.13 ± 2.44 years for LD versus 58.97 ± 2.54 years for RD; p=0.149). There was a statistically significant difference in total CTDIvol between the LD and RD groups (79.06 ± 8.336 mGy versus 289.3 ± 23.48 mGy respectively; p< 0.0001) as well as in total DLP (667.2 ± 62.2 mGy-cm for LD versus 1536 ± 115.9 mGy-cm for RD; p< 0.0001). There was no significant difference in total number of scans obtained (11.42 ± 0.78 for LD versus 12.48 ± 0.79 for RD; p=0.3422), duration of procedure (34.55 ± 2.15 min for LD versus 38.18 ± 1.57 min for RD; p=0.1732) or diagnostic tissue yield (21/31 or 67.74% for LD versus 20/33 or 60.61% for RD positive for malignancy; p=0.61). There were sufficient specimens for diagnosis in all patients in both biopsy groups. No significant complications were noted in either group. Conclusion Low CT-dose spine biopsies have a significantly lower cumulative radiation exposure (CTDIvol and DLP) when compared to regular CT-dose biopsies without significantly affecting procedural time or diagnostic tissue yield. Use of a LD protocol should be considered as an alternative to RD protocol when performing CT guided spinal biopsies, thus allowing the operator to reduce ionizing radiation dose while maintaining overall quality and efficiency of the procedure. References Chang AL, Schoenfeld AH, Brook AL, Miller TS. Radiation Dose for 345 CT-Guided Interlaminar Lumbar Epidural Steroid Injections. AJNR Am J Neuroradiol. 2013 Oct;34(10):1882-6. Patel AS, Soares B, Courtier J, Mackenzie JD. Radiation dose reduction in pediatric CT-guided musculoskeletal procedures. Pediatr Radiol. 2013 Oct;43(10):1303-8. Artner J, Cakir B, Reichel H, Lattig F. 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