How lesions proportional density shapes MRI cognitive fusion biopsy outcomes; finding the needle in the haystack

To evaluate the importance of lesion density (lesion volume/prostate volume) on prostate cancer (PCa) and clinically significant prostate cancer (csPCa) detection rates in cognitive targeted biopsy (cTB). 300 consecutive patients who underwent combined transrectal cTB and systematic transrectal prostate biopsy were included retrospectively. Lesion density was calculated as the largest lesion volume divided by prostate volume. According to ROC analysis and Youden’s index, patients were grouped into low lesion density (Low-LD) and high lesion density (High-LD) groups. Detection rates of PCa and csPCa were compared. Subgroup analyses were performed for high PI-RADS lesions ( 4–5) and anatomical zones. Mean lesion diameter and prostate volume were 14.1 ± 7.2 mm and 83.9 ± 42.8 mm³, respectively. High lesion density was independently associated with csPCa in univariate and multivariate analysis (p < 0.05). PCa and csPCa detection rates were significantly higher in the High-LD group (53.6% vs. 32.0%, p < 0.001; and 37.1% vs. 16.7%, p < 0.001, respectively). Similar results were observed when only MRI-targeted cores were analysed. Subgroup analysis of PI-RADS 4–5 lesions confirmed that csPCa detection rates were also higher in High-LD group (39.0% vs. 21.5%, p = 0.005). csPCa detection was lowest in anterior lesions, especially in Low-LD patients (6%). Lesion density significantly affects the diagnostic accuracy of cTB. Patients with low lesion density have lower csPCa detection rates and may benefit from software-assisted fusion targeting over cognitive targeting.