Introduction:

MRI-Targeted Fusion prostate biopsies have demonstrated improved clinically significant cancer compared to systematic biopsy. However, despite MRI-targeted biopsy improved detection there remain critically important cases of missed clinically significant cancer. We sound to understand the reason for these “MRI-Targeted biopsy misses”.

Methods:

Patients were enrolled in a prospective study comparing transrectal MRI-targeted fusion biopsy with systematic 12 core biopsy.  Patients with an elevated PSA, abnormal rectal exam, or imaging finding concerning for prostate cancer underwent prostate MRI followed by MRI-targeted and systematic biopsies, in the same setting, if a prostate lesion was detected on MRI. The subset of patients with clinically significant (GG≥3) cancer found on systematic biopsy and GG≤2 cancer on MRI-targeted biopsy were classified as MRI-targeted biopsy misses. A retrospective analysis of the MRI lesion with an expert genitourinary radiologist was performed to assess for the cause of MRI-targeted biopsy miss. The possible reasons for biopsy misses included MRI-invisible lesions, MRI-Invisible lesions, and MRI-visible lesions missed on biopsy.  

Results:

Over the study period of 2007 to 2019, 2103 patients met study inclusion criteria and underwent combine MRI-targeted and systematic prostate biopsies. 42(2.0%) men demonstrated clinically significant cancer detected on systematic biopsy only. The majority of MRI targeted biopsy misses were due to errors in lesion targeting (n=22, 52.4%), followed by MRI-invisible lesions (n=17, 40.5%). MRI lesions missed by the radiologist accounted for a 7.1% (n=3) of MRI-targeted biopsy misses. Of the lesions missed due to targeting errors, 29.4% (n=5) were due to poor co-registration of the MRI with the ultrasound.

Conclusion:

MRI-targeted biopsies can miss clinically significant cancers. Most of these misses are due to errors in lesions targeting, which highlights the importance of accurate co-registration and targeted when using software based fusion platforms. Additionally, some patients will harbor MRI-invisible lesions which are un-targetable by MRI-targeted platforms. Among highly experienced genitourinary radiologists, the rates of MRI visible lesion misses of clinically significant cancer can be low.

Funding: NIH Intramural Fund