Performance Characteristics of MR Imaging in the Evaluation of Clinically Low-Risk Prostate Cancer: A Prospective Study

Abstract

Dr(hc) Purpose:To prospectively evaluate diagnostic performance of T2-weighted magnetic resonance (MR) imaging and MR spectroscopic imaging in detecting lesions stratified by pathologic volume and Gleason score in men with clinically determined low-risk prostate cancer. Materials and Methods:The institutional review board approved this prospective, HIPAA-compliant study. Written informed consent was obtained from 183 men with clinically low-risk prostate cancer (cT1-cT2a, Gleason score  6 at biopsy, prostatespecific antigen [PSA] level , 10 ng/mL [10 mg/L]) undergoing MR imaging before prostatectomy. By using a scale of 1-5 (score 1, definitely no tumor; score 5, definitely tumor), two radiologists independently scored likelihood of tumor per sextant on T2-weighted images. Two spectroscopists jointly recorded locations of lesions with metabolic features consistent with tumor on MR spectroscopic images. Whole-mount step-section histopathologic analysis constituted the reference standard. Diagnostic performance at sextant level (T2-weighted imaging) and detection sensitivities (T2-weighted imaging and MR spectroscopic imaging) for lesions of 0.5 cm 3 or larger were calculated. Results:For T2-weighted imaging, areas under the receiver operating characteristic curves for sextant-level detection were 0.77 (reader 1) and 0.82 (reader 2). For lesions of 0.5 cm 3 and ,1 cm 3 , sensitivities were significantly lower when the lesion Gleason score was 6 (0. Conclusion:In men with clinically low-risk prostate cancer, detection of lesions of ,1 cm 3 with T2-weighted imaging is significantly dependent on lesion Gleason score; detection of lesions of 1 cm 3 is significantly better than detection of smaller lesions and is not affected by lesion Gleason score. The role of MR spectroscopic imaging alone in this population is limited.q RSNA, 20121 From the Departments of Radiology (H

Defining the threshold for significant versus insignificant prostate cancer

“…Also, the inability of current imaging tools to provide an accurate assessment of prostate cancer volume has contributed to the difficulty of reliably identifying insignificant prostate cancers. 13,14 Since the original definition of pathologically insignificant prostate cancer was proposed more than 15 years ago, prostate cancer diagnostics have evolved. A stage and grade migration of detected prostate cancers has occurred [15][16][17] and pathologists have modified the criteria for Gleason grading, particularly with respect to grading prostate needle biopsies.…”

Information of prostate biopsy positive core: does it affect MR detection of prostate cancer on using 3T-MRI?

“…Vargas et al [16] reported that the detection of lesions less than 1 cm 3 with T2-WI was significantly dependent on their GS. They further noted that the detection of lesions greater than or equal to 1 cm 3 was significantly better than the detection of smaller lesions, and is not affected by the lesion's GS, demonstrating that the tumor volume affects detectability on T2-WI.…”

Prostate Imaging – An Update

“…This is true in particular for anterior and apical prostate cancers [38]. Prostate cancers with a volume of > 0.5 cm³ are detected with the help of MRI with a diagnostic accuracy of 0.91 to 0.94 [39]. If the Gleason score is taken into consideration in this analysis, the sensitivity for the detection Fig.…”