Prostate Cancer Risk Stratification Enhanced by Novel MRI Protocol

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Researchers compared targeted prostate biopsy based on biparametric magnetic resonance imaging with standard 12-core systematic biopsy.
Researchers compared targeted prostate biopsy based on biparametric magnetic resonance imaging with standard 12-core systematic biopsy.

Targeted prostate biopsy based on the findings of a novel biparametric magnetic resonance imaging (bpMRI) protocol improves risk stratification among men with a clinical suspicion of prostate cancer (PCa), researchers concluded.

Ivan Jambor, MD, and colleagues at the University of Turku in Turku, Finland, enrolled 175 men with a clinical suspicion of PCa (2 repeated PSA values in 2.5 to 20 ng/mL range and/or abnormal digital rectal examination) to compare PCa detection rates for bpMRI-targeted transrectal ultrasound (TRUS) biopsy (TB) and systematic 12-core biopsy (SB).

European Association of Urology guidelines recommend the use of multiparametric MRI followed by TRUS and MRI-targeted prostate biopsy if suspicion of PCa persists despite a prior a negative systematic biopsy, Dr Jambor's team noted. Routine multiparametric prostate MRI, they pointed out, has long acquisition times, requires the use of intravenous contrast media, and is expensive. “A more rapid and less expensive MRI protocol with shorter imaging times, no endorectal coil, and no intravenous contrast might encourage greater use of prebiopsy MRI in men with clinical suspicion of PCa,” they stated. “Targeting suspicious areas, some of which may be outside the normal biopsy template, could also improve the diagnostic sensitivity.”

Dr Jambor's team (#jambor_ivan) developed a novel biparametric MRI protocol that includes T2-weighted imaging and 3 separate diffusion-weighted imaging acquisitions.

The investigators reported their findings in the Journal of Magnetic Resonance Imaging (2017; published online ahead of print).

Of the 161 men who completed the trial (clinicaltrial.gov registration number: NCT01864135), 72 (45%) had PCa detected by TB and 63 (39%) had PCa detected by SB, a non-significant difference.  Twenty-five men (16%) were upgraded to an intermediate- or high-risk category based on TB, whereas only 12 men (8%) were upgraded based on SB, a significant difference in upgrading rate.

Clinically significant PCa (SPCa)—defined as Gleason score 3 + 4 or higher—was diagnosed in 18 patients (11%) in TB cores only and 9 patients (6%) based on SB, a significant difference in detection rate.

“This newly developed biparametric MRI imaging protocol enabled a significant improvement in the selection of men with SPCa for biopsy, and in combination with targeted biopsy was also significantly more accurate than SB of the prostate,” the investigators concluded.

If biopsy was restricted to men with equivocal to highly suspicious bpMRI findings, 38 men (24%) would have avoided undergoing biopsy, according to the researchers. SPCa would have been missed in only 4 patients (2%). This is the first prospective registered clinical prostate MRI trial that provides free public access to all anonymized datasets, including bpMRI reports and follow up information.

Reference

1. Jambor I, Boström PJ, Taimen P, et al. Novel biparametric MRI and targeted biopsy improves risk stratification in men with clinical suspicion of prostate cancer (IMPROD Trial). J Magn Reson Imaging; 2017; published online ahead of print.

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