New MRI technique helps target ultrasound-guided prostate biopsy

2019 04 17 20 48 2514 Prostate 3 D 400

A new microstructure imaging technique, hybrid multidimensional MRI (HM-MRI), could enable better targeting of areas in the prostate that need to be biopsied, according to a presentation at the American Roentgen Ray Society annual meeting in Honolulu.

"This study validates [that an] HM-MRI based tool can identify clinically significant prostate cancer -- equal to or more than Gleason 3 + 4 -- more reliably than random biopsy and/or areas detected by a radiologist in patients undergoing MR-ultrasound fusion biopsy," presenter Aritrick Chatterjee, PhD, of the University of Chicago told session attendees.

HM-MRI depicts volumes of tissue components such as the stroma, epithelium, and lumen by "fitting the MRI data into a three-compartment signal model," Chatterjee explained.

He and colleagues conducted a study that included 85 patients with a mean prostate-specific antigen (PSA) score of 8.1 ng/ml; median time between MR imaging and biopsy was seven days. Patients underwent both a standard prostate MRI and an HM-MRI exam; all had a transrectal ultrasound (TRUS)-guided biopsy. The median time between MR imaging and biopsy was seven days.

The group found that HM-MRI had higher sensitivity per tumor of the prostate but not per patient. It had a lower negative predictive value on a per-patient basis.

Comparison of mpMRI and HM-MRI for identifying clinically significant prostate cancer
Measure mpMRI HM-MRI
Sensitivity 100% 90%
Specificity 15% 40%
Positive predictive value 41% 47%
Negative predictive value 100% 88%
Accuracy 46% 58%
Area under ROC curve 0.58 0.65
Sensitivity 70% 78%
Positive predictive value 22% 34%
By sextant (i.e., from ultrasound-guided biopsies of six different areas of the prostate)
Sensitivity 50% 68%
Specificity 82% 86%
Positive predictive value 19% 29%
Negative predictive value 95% 97%
Accuracy 79% 85%
Area under the ROC curve 0.66 0.77

The findings highlight the fact that radiologists need to consider the HM-MRI data with care.

"[We] have to look at these results very carefully and consider all three," he said.

HM-MRI shows promise for improving MR-ultrasound fusion biopsy results by offering more accurate clinical information compared to PI-RADS-based radiologist evaluation, Chatterjee concluded.

"The advantage of this tool is its ability to provide automated, quantitative, reproducible results," he said.

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