FALSE POSITIVE LESIONS ON MRI FUSION PROSTATE NEEDLE BIOPSY AND INFLAMMATION
Inflammation is known to mimic prostate cancer lesions on MRI, for example chronic prostatitis or nodules following BCG treatment. However, it is unknown how commonly inflammation plays a role in MRI Fusion Ultrasound-Guided (MRI-US) prostate needle biopsies. We investigate inflammation identified on pathology reports from UroNav MRI Fusion prostate biopsy patients.
We retrospectively identified 43 men with 62 MRI lesions noted on prostate MRI prior to MRI-US fusion prostate biopsy. We utilized the UroNav system from Invivo (Gainesville, FL). Men underwent 3T MRI with Siemens TIM MRI system and lesions were identified and marked with the DynaCAD system. MRI fusion was performed with standard MRI fusion techniques to include scanning and segmentation prior to prostate biopsy attempt. The target lesions were performed prior to standard 12-core needle biopsy. A target lesion was biopsied 3 times (2 sagittal and 1 transverse views) if only one lesion was present and, if there was more than one lesion, 2 cores were taken of each lesion. Pathology was retrospectively reviewed for inflammation.
A total of 32 (52%) false positive lesions were noted with 22 having no cancer on any cores and 10 subjects with cancer noted on systematic biopsy but not in the target region. Of the men with cancer, only 1 of the false positive lesions had inflammation in the location of the targeted region of interest (10%, 1/10). However, when we examine the 22 men with an identified lesion on MRI with negative pathology in all cores (no prostate cancer identified), 54% had inflammation on prostate biopsy pathology (12/22, p=0.024). Figure 1 displays the proportion of false positive targets and corresponding PI-RADS scores. The highest proportion of inflammation was noted on PI-RADS 4 (41%) and 3 (33%) lesions.
Inflammation can confound interpretation of MRI by mimicking prostate cancer. The false positive rate for MRI-Fusion biopsies can be high and the result of several factors including: MRI quality, radiology read, importing/segmentation of images and biopsy accuracy. There appears to be differences in those patients with and without cancer with false positive lesions. We identify inflammation as one cause of false positives on MRI-Fusion biopsy that should be addressed in larger studies or combined with novel inflammatory biomarkers.
Funding: This work was supported by the Office of the Assistant Secretary of Defense for Health Affairs through the Prostate Cancer Research Program under Award No. W81XWH-15-1-0441. Opinions, interpretations, conclusions and recommendations are those of the author and are not necessarily endorsed by the Department of Defense.