MRI-directed biopsy for primary detection of prostate cancer in a population of 223 men: MRI In-Bore vs MRI-transrectal ultrasound fusion-targeted techniques

Abstract

Objectives: To compare the detection rates of overall prostate cancer (PCa) and clinically significant PCa (csPCa) and the median percentage of cancer per biopsy core between MRI-guided In-bore and MRI-TRUS fusion-targeted biopsy (TBx).

Methods: In this retrospective study, 223 patients who underwent prostate multiparametric MRI (mpMRI) and subsequent MR-directed biopsy were included. For PCa and csPCa detection rate (DR), contingency tables were tested via the Pearson's chi-squared to explore the variance of the outcome distribution. The percentage of cancer per biopsy core was tested with a two-tailed Mann-Withney test.

Results: One hundred and seventeen and 106 patients underwent MRI-TRUS fusion or MRI In-bore TBx, respectively. 402 MRI biopsy targets were identified, of which 206 (51.2%) were biopsied with the MRI-TRUS TBx and 196 (48.8%) with the MRI In-bore TBx technique. Per-patient PCa and csPCa detection rates were 140/223 (62.8%) and 97/223 (43.5%), respectively. PCa-DR was 73/117 (62.4%) and 67/106 (63.2%) for MRI-TRUS and MRI In-Bore TBx (p = 0.9), while csPCa detection rate reached 50/117 (42.7%) and 47/106 (44.3%), respectively (p = 0.81). The median per-patient percentage of malignant tissue within biopsy cores was 50% (IQR: 27-65%) for PCa and 60% (IQR: 35-68%) for csPCa, with a statistically significant difference between the techniques.

Conclusion: No statistically significant difference in the detection rate of MRI In-bore and MRI-TRUS fusion TBx was found. MRI In-bore TBx showed higher per-core percentage of malignant cells.

Advances in knowledge: MRI In-bore biopsy might impact risk stratification and patient management considering the higher per-core percentage of malignant cells, especially for patients eligible for active surveillance or focal therapy.

Figure 1.

56-year-old man with clinical suspicion of prostate cancer (PSA total value of 7.6 ng ml⁻¹. (a) T2WI acquired on the axial plane showing a hypointense nodule (index lesion) on the mid-left posterior-lateral zone, slightly hyperintense on early DCE images (b), with restriction diffusion at b-value 1500 (c) and low ADC value (d), classified as PI-RADS 4 (solid circle). An additional lesion is present on the mid-right posterior-lateral zone classified as PI-RADS 3 (dashed circle). (e) Both nodules were biopsied using MRI-TRUS TBx. (f) Histopathology confirmed the presence of ISUP 2 (GS 3 + 4, in 12.7% of the core) on the left lobe of the prostate. PSA, Prostate-specific antigen; T2WI, T ₂-weighted imaging; DCE, Dynamic contrast enhanced; TBx, Targeted biopsy; ISUP, International society of urogenital pathology; GS, Gleason score.

Figure 2.

66-year-old man with clinical suspicion of prostate cancer (PSA total value of 5.4 ng ml⁻¹. (a) T2WI acquired on the axial plane showing a hypointense nodule on the mid-left posterior zone, hyperintense on early DCE images (b), with restriction diffusion at b-value 1500 (c) and low ADC value (d), classified as PI-RADS 4. (e) The nodule was biopsied using MRI In-bore TBx, coronal images were acquired during the procedure for needle orientation and after the procedure to document the accurate targeting. (f) Histopathology confirmed the presence of ISUP 2 (GS 3 + 4, in 58% of the core) on the left lobe of the prostate. ISUP, International society of urogenital pathology; GS, Gleason score; PSA, Prostate-specific antigen; T2WI, T ₂-weighted imaging; DCE, Dynamic contrast enhanced; TBx, Targeted biopsy.

Figure 3.

LOWESS function of predicted probability of clinically significant prostate cancer per increasing median percentage of malignant positive core in the per single-lesion analysis. LOWESS, Locally Weighted Scatterplot Smoothing.