Purpose: To evaluate specimen quality and diagnostic differences between magnetic resonance (MR) compatible 16 G and 18 G biopsy needles in MR-guided biopsy (MRGB) of the prostate.
Materials and methods: Semiautomatic MR compatible biopsy needles with a diameter of 16 G (Group A) or 18 G (Group B) were used to perform MRGB in 88 patients with suspected prostate cancer. After embedding and staining, length and width of all specimens (140 cores in Group A, 143 in Group B) were measured. Fragmentation, squeezing artifacts, and overall evaluability were evaluated using a quality score from 0 (no tissue) to 3 (optimal tissue quality). Groups were statistically compared; p-values <0.05 were regarded as significant.
Results: Demographic data were not significantly different between Group A and B with a mean age of 63 ± 7.3 and 67 ± 5.7 years; and a mean prostate-specific antigen of 12.6 ± 10.3 ng/ml and 13.8 ± 11.6 ng/ml, respectively (p=0.70). Area of longitudinally sectioned histological specimens was significantly larger in Group A than in Group B with 9.38 mm(2) (8.74; 10.02) and 7.95 mm(2) (7.32; 8.59), respectively (p=0.002). However, there were significantly more cores without prostate tissue with 18 cores (12.9%) versus 3 cores (2.1%) in Groups A and B, respectively (p=0.004). Fragmentation, squeezing artifacts, and overall evaluability were not statistically different between the two groups. The rate of prostate cancer in the cores was also not significantly different between Groups A and B (22.1% and 24.5%; p=0.77).
Conclusion: 16 G biopsy needles do not provide a relevant diagnostic advantage over 18 G needles in MRGB. Therefore, use of 18 G needles is not discouraged and may even be preferred as it is not expected to result in a relevant degradation of specimen quality or compromise in prostate cancer detection rate.
Keywords: Biopsy; Diagnosis; MR guided biopsy; MRI; Prostate cancer.
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