Reproducibility of image interpretation in MRI of the prostate: application of the sextant framework by two different radiologists

Abstract

The aim of this study was to reproduce prostate cancer (PCA) localization by MRI based on prostatic sextants (right and left base, middle, and apex) with minimal systematic error. Combined endorectal/body-phased-array-coil MRI of the prostate at 1.5 T was retrospectively evaluated twice, with an interval of more than 1 month, by each of two independent radiologists (R1 readings R11 and R12, and R2 readings R21 and R22) in 23 patients (age 51-75 years) who had radical prostatectomy within 1 month of MRI. PCA stage was pT2 in 14 patients, and pT3 in nine. Median Gleason score was 7 (range 5-9). Histopathology showed 83 sextants with PCA and 55 without. Reproducibility of sextant positions was within one MRI slice (3 mm) in over 80% of cases. For PCA localization, ROC analysis (AUC=0.584+/-0.048-0.724+/-0.043) yielded no significant intra-reader differences. R11 and R21 differed slightly (P=0.035). Intra-observer agreement (kappa=0.52-0.58) exceeded inter-observer agreement (kappa=0.35-0.45). Intra-observer Spearman correlation (r=0.72-0.74) exceeded inter-observer correlation (r=0.43-0.51) for sextants with PCA, but not for sextants without (r=0.69-0.74). Per-sextant localization and reporting provides a highly reliable framework in MRI of the prostate. MRI of the prostate should be followed up by the same radiologists to minimize systematic error of interpretation.

ESUR prostate MR guidelines 2012

“…Reviews of the literature show that Likert-like five-grade scoring systems are often used to evaluate mp-MRI of the prostate [28, 72–76]. In keeping with this, a recent consensus meeting of prostate cancer experts used the UCLA-RAND appropriateness method and recommended that a five-point scale be used for the PI-RADS scoring:

Score 1 = Clinically significant disease is highly unlikely to be present

Score 2 = Clinically significant cancer is unlikely to be present

Score 3 = Clinically significant cancer is equivocal

Score 4 = Clinically significant cancer is likely to be present

Score 5 = Clinically significant cancer is highly likely to be present.

…”

Multiparametric Prostate Magnetic Resonance Imaging at 3 T

“…To describe lesion location, the prostate was subdivided in sextants according to Mueller-Lisse et al 6 (right and left base, middle gland and apex).…”

Bildgebende Verfahren bei Primärdiagnose und Staging des Prostatakarzinoms

“…Abb. 1; [26]), welches auch bei Planung und Durchführung der Stanzbi opsie der Prostata angewendet wird [34]. Die Testgüteparameter der MRT gelten als besser als die der TRUS.…”