Multiparametric MRI May Miss or Underestimate Prostate Cancer Lesions

Multiparametric magnetic resonance (MP MR) imaging may miss clinically important lesions in prostate cancer, according to a study published in Radiology.

Researchers from the National Institutes of Health in Bethesda, MD, performed a retrospective single-center study to characterize clinically important prostate cancers missed at MP MR imaging. The study included 100 consecutive patients who had undergone MP MR imaging and subsequent radical prostatectomy. A genitourinary pathologist blinded to MP MR findings outlined prostate cancers on whole-mount pathology slices.

The MP MR images were correlated by two readers who were blinded to histopathology results during prospective reading. Eighty clinically unimportant lesions (<5 mm; Gleason score, 3+3) were excluded from the study. The same two readers then retrospectively reviewed cancers missed at MP MR imaging and assigned a Prostate Imaging Reporting and Data System (PI-RADS) version 2 score to better understand false-negative lesion characteristics.

The results showed that of the 162 lesions found, 26 (16%) were missed and 136 (84%) were correctly identified with MP MR imaging. Eight lesions were underestimated for size.

The Gleason scores for the 26 missed lesions were:

• 3+4 in 17 (65%)
• 4+4 in 7 (27%)
• 4+5 in 1 (4%)

Retrospective PI-RADS version 2 scores were:

• PI-RADS 1, n = 8
• PI-RADS 2, n = 7
• PI-RADS 3, n = 6
• PI-RADS 4, n = 5

The MP MR imaging did depict clinically important prostate cancer in 99 of 100 patients, but at least one clinically important tumor was missed in 26 (26%) patients, and lesion size was underestimated in eight (8%).

The researchers concluded that clinically important lesions can be missed or their size can be underestimated at MP MR imaging.