Abstract No. 547 Frozen section analysis of MRI-guided transrectal prostate biopsy specimens: is it accurate?

Abstract

The standard for prostate biopsy consists of a non-targeted 12-50 core retrieval using transrectal, ultrasound techniques or template transperineal techniques performed in the operating room. With 3 Tesla multiparametric MRI now providing sensitive and specific findings for focal prostate cancers, we are targeting focal biopsies in the MRI suite. This reduces the invasiveness and damage caused by yearly indiscriminate biopsies. However, since we target prostate lesions, it is very important that we obtain a “quick stain” analysis of the tissue while the patient is still in the MRI scanner. This is standard image-guided biopsy workflow in radiology. We are simply applying it to a new organ. The purpose is to insure that frozen section biopsies of the prostate are accurate as compared to the final histopathologic diagnosis. Thirty nine consecutive prostate biopsy patients had in-bore MRI-guided, transrectal biopsy. We transport two 18g core specimens in saline and two other specimens in formalin to the surgical pathology department (the patient remains in MRI with the transrectal probe in place). Frozen section analysis of the two saline specimens gave a preliminary diagnosis. We compared the frozen section analysis with final histopathology to determine true negative and positive rate and accuracy of frozen section analysis of core prostate biopsy specimens. Of the 39 biopsy procedures, 21 patients had true positive results and 15 had true negative results by frozen section analysis. No false positives occurred and 3 false negatives resulted when the final histopathology detected small foci of atypia or low risk prostate cancer. The sensitivity, specificity, positive predictive value, and negative predictive values were 87.5%, 100%, 100%, and 83.3%, respectively. The preliminary diagnosis from frozen section analysis of targeted transrectal prostate core biopsy specimens is highly accurate when malignancy is present. False negative results occur in less than 20% of cases when traces of malignancy are discovered at final histopathology.Tabled 1Frozen versus Final Histopathology of Prostate BiopsiesFinalFrozenPositiveNegativePositive210Negative315 Open table in a new tab