microUSG vs MRI guided prostate Bx

MicroUSG is a 29MHz USG device specially designed for prostate imaging and biopsy. Its 70micron resolution is equivalent to the diameter of of prostatic duct, permitting the visualisation of prostate cancer as it alters the architecture of the prostate gland. Similar to MRI, the suspicious lesions are categorised according to prostate risk identification using microultrasound (PRI-MUS) system into 1 to 5 categories, where 1&2 are low risk, 3 is equivocal and 4,5 are suspicious for prostate cancer. It has the potential to convert the 2 step process of biopsy i.e. MRI followed by USG guided prostate biopsy into a single step process of micro-USG and guided biopsy if needed. OPTIMUM trial was a multicenter non-inferiority RCT involving 20 centres in 8 countries and randomised patients suspected of having prostate cancer into 1:2:3 ration of micro-USG alone and guided Bx vs micro-USG guided BX + MRI guided BX vs MRI fusion biopsy. The patients in mirco-USG + MRI guided Bx underwent micro-USG guided Bx initially, where the operator was unaware of MRI findings. Once the TB was performed, MRI guided TB were performed. Such a protocol reduced the risk of under detection of CaP if micro-USG was found to be inferior. 802 patients were included and randomised into 3 arms. Detection of csCaP in microUSG arm and MTI fusion biopsy was similar (46% vs 43%) as was the detection of GG1 cancer (11% vs 15.4% vs 17.3%). The NPV of PRI-MUS <3 was 83.1% vs 89.4% for MRI PIRADS <3 for detecting csCaP. The target biopsy only detection rate was also similar (38% vs 34%). When both the imaging were negative, csCaP was detected in 8.8% of the patients whereas, the detection was 73.6% when both the imaging studies were positive. Thus micro-USG guided prostate biopsy was found to be non-inferior to MRI guided prostate biopsy. Micro-USG also has a learning curve and all the surgeon involved had a training of at least 50 cases prior to enrolment in the study and some had an experience of 90 cases. Besides, micro-USG has the potential to become a single investigation where a lesion in the prostate can be scored with PRI-MUS and biopsied immediately, thus avoiding repeated scheduling and separate sitting.