Micro-ultrasound tissue echogenicity predicts prostate cancer grade

This study aimed to evaluate the association between lesion echogenicity on micro-ultrasound (micro-US) and the presence and grade of prostate cancer.

We prospectively analysed 229 prostate lesions from 181 men undergoing micro-US-guided transperineal biopsy at UCLA. Lesions were visually graded as hyperechoic, isoechoic or hypoechoic relative to the central zone, which served as an internal reference due to its consistent tissue characteristics and low malignancy risk. Biopsy targeting was confirmed by visualizing the needle tract within the lesion. The primary outcome was the detection rate of Grade Group (GG) ≥ 2 cancer across echogenicity categories. Secondary analyses included associations with PSA density and MRI-derived apparent diffusion coefficient (ADC) values, given that ADC is associated with tissue cellularity. Statistical comparisons were performed using chi-square and Kruskal-Wallis tests, with post hoc pairwise analyses where appropriate.

GG ≥ 2 cancer detection rates increased with decreasing echogenicity: 22% in hyperechoic, 56.2% in isoechoic and 62.4% in hypoechoic lesions (p < 0.01). Hypoechoic lesions also exhibited a higher proportion of GG ≥ 3 cancers (p < 0.05). ADC values declined progressively from hyperechoic to hypoechoic lesions (median: 980, 851 and 751, respectively; p < 0.01), suggesting higher tissue cellularity. Regression analysis demonstrated no meaningful interaction between PRI-MUS and echogenicity. PSA density did not significantly differ among echogenicity groups.

Lesion hypoechogenicity on micro-US is strongly associated with higher grade prostate cancer and lower ADC values, suggesting a link to tissue cellularity. These findings support the incorporation of echogenicity as a diagnostic marker within the micro-US PRI-MUS framework, potentially enhancing the accuracy of prostate cancer risk stratification.