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6. Analysis of Diagnostic Accuracy with Low Dose versus standard dose computed Tomography Fluoroscopy Guided Biopsies
Mariam Malik and Rana Bilal Idrees
ABSTRACT
Objective To compare low dose Computed Tomography Fluoroscopy (CTF) versus standard dose CT guided biopsy procedures in terms of diagnostic accuracy, intervention time and number of needle passes required for biopsy to be completed successfully.
Study Design: Retrospective study
Place and Duration of Study: This study was conducted at the Radiology Department of CMH Rawalpindi from April 2016 to April 2017.
Methods: Total 65 consecutive patients comprising 51 males and 14 females, mean age 41.52 ± 13.40 years, underwent CT guided biopsies of lung, pleura, mediastinal and muscle lesions on Philips Brilliance 16 slice CT-scanner under low dose CTF guidance comprising tube current 30mAs and voltage 120kVp. Diagnostic accuracy, intervention time and number of needle passes performed for completion of procedure were recorded. These were compared with biopsies performed at standard dose protocol over 12 months before introduction of low dose technique. During this time 60 consecutive patients, mean age 40.62 ± 11.32 years, were included who underwent biopsies performed on the same machine under standard dose CT. The standard dose comprised tube current 200-250mAs and tube voltage 120kVp.
Results: In the low-dose protocol, needle passes ranged from 3 to 6 (mean: 4.09 ± 0.81), while the standard dose required 6 to 8 passes (mean: 7.41 ± 0.68), with a significant statistical difference (p-value <0.05). Low-dose DLP ranged from 130 to 386.9 mGy.cm (mean: 190.39 ± 23.3), while standard dose DLP was 1270 to 1976 mGy.cm (mean: 1664.7 ± 342.11), showing a significant reduction (p-value <0.05). Intervention time for standard dose biopsies was 30 to 50 minutes (mean: 39.85 ± 4.84), whereas low-dose biopsies took 5 to 13 minutes (mean: 7.04 ± 1.40), also with a significant difference (p-value <0.05).
Conclusion: Biopsies performed under low dose CTF have success rate comparable to standard dose protocol with 85% reduction in radiation dose, fewer number of needle passes and overall shorter intervention time in comparison to standard dose technique.
Key Words: Diagnostic Accuracy, Low Dose, Standard Dose, Computed Tomography, Fluoroscopy Guided Biopsies