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Updated: Aug 13, 2026
Use of MRI-ultrasound Fusion to Achieve Targeted Prostate Biopsy
Published on: April 9, 2019
Quantitative core-level tumor burden and grading in MRI-targeted vs. systematic prostate biopsy: A within-patient
Assem Abdelaziz Mahmoud Mesbah1, Atef A Hassan2, Ahmed M Abdel Gawad3
1Urology Department, Faculty of Medicine, Fayoum University, Fayoum, Egypt.
Background:
Within-patient studies of MRI-targeted vs. systematic prostate biopsies compare binary detection rates, but none have quantified paired tumor burden differences using continuous histopathological metrics with independent prognostic significance. We hypothesized that MRI-targeted cores capture greater tumor burden than systematic cores within the same patient, while systematic biopsy retains an independent contribution to the detection and grading of clinically significant prostate cancer (csPCa).
Methods:
Within-patient paired analysis of 872 men with both targeted and systematic cores from The Cancer Imaging Archive Prostate-MRI-US-Biopsy dataset (2015-2020). Four continuous tumor burden metrics (total and maximum cancer length, percentage cancer per core, positive core ratio), incremental csPCa detection (Grade Group ≥2), Grade Group concordance, and PSA density-stratified subgroup analysis were assessed.
Results:
Combined csPCa prevalence was 57.2% (499/872). Forty patients (8.0% of csPCa) had cancer detected exclusively by systematic cores. Among 515 patients with cancer in both arms, targeted cores showed significantly higher total cancer length (median 16.0 vs. 5.0 mm; P < 0.001, r = 0.78), maximum cancer length (6.0 vs. 3.0 mm; r = 0.69), median percentage cancer (30% vs. 15%; r = 0.64), and positive core ratio (0.50 vs. 0.18; r = 0.90). Grade Group was higher in systematic cores in 8.4%. Among 140 patients with Grade Group 1 on targeted biopsy, 18 (12.9%) were upgraded by systematic cores. Systematic cores' contribution persisted across all PSA density subgroups (miss rate 3.4-13.7%).
Conclusions:
MRI-targeted cores capture substantially greater tumor burden, yet systematic biopsy uniquely identifies 8.0% of csPCa and upgrades Grade Group in 8.4%. These findings argue against the routine omission of systematic biopsy; however, the additional yield must be weighed against the harms of additional cores (bleeding, infection, overdiagnosis, and cost), and prospective trials with long-term outcomes are needed.
