br MATERIALS AND METHODS br Study Population br This Health
MATERIALS AND METHODS
This Health Insurance Portability and Accountability Act-compliant retrospective evaluation of prospectively acquired data was approved by local ethics committee. Written informed consent was given by all patients. Flow diagram illustrating patient exclusion and inclusion is given in Figure 1. All patients underwent complete mpMRI (T2W MRI, DWI [apparent Actinomycin D coefficient ADC map, b-2000 DWI acquisition], and DCE MRI) at 3-Tesla with endorectal coil performed at one institution. In population of consecutive patients imaged between April 2012 and June 2015 consid-ered for inclusion, 179 underwent radical prostatectomy and 92 had no lesions detected on mpMRI and subsequent nega-tive 12-core systematic biopsy guided by mpMRI-transrectal ultrasound fusion technique using the Uronav platform. Patients were excluded for receiving any prior treatment and for having artifacts arising from hip prostheses, or if acquired
Figure 1. Study design. Flow diagram shows exclusion criteria as well as ran-dom selection of patients for inclusion in study. MRI, magnetic resonance imaging; mpMRI, multiparametric MRI. (Color ver-sion of figure is available online.)
Academic Radiology, Vol 26, No 1, January 2019 PROSTATE MPMRI INDIVIDUAL SEQUENCE CANCER DETECTION
mpMRI was missing any sequences. Cases were additionally excluded if whole-mount specimen mapping with lesion-specific Gleason scores was not available (total exclusions n = 69 cases, n = 3 controls). From remaining eligible patients, 45 (n = 30 cases, n = 15 controls) were randomly selected in a two:one ratio of cases:controls for study inclusion. Indications for imaging included rising prostate-specific antigen (PSA) with prior negative biopsy (n = 12 controls), high measured PSA without prior biopsy (n = 3 controls), referral for fusion-guided biopsy and cancer staging (n = 29 cases), and referral for cancer staging after a positive biopsy (n = 1 case). Patients originally presented to the National Institutes of Health as part of accrual for an approved prostate cancer protocol.
As this method of studying independent sequence cancer detec-tion did not suggest an ideal set point for facilitating statistical powering, the study was conducted as a small pilot study and the sample size utilized reflects its exploratory purpose. The patient population is a subset of patients from a larger ongoing multireader study of a computer-aided diagnosis system.
Three radiologists participated as readers. All were from different institutions, highly experienced in prostate mpMRI (>2000 cases each in the last 2 years), and familiar with read-ing endorectal coil mpMRI. The readers were blinded to clinical and pathologic data while conducting reads. The readers were asked to independently evaluate each sequence in the following manner:
Each complete mpMRI data per patient were split into three individual MRI sequences and separately anonymized within the following groupings: T2W MRI (axial and sagittal sets), DWI (ADC map and b-2000 DWI sets), and DCE MRI (raw data of time points at each slice location). The resultant 135 anonymized pulse sequence datasets were ran-domly ordered and distributed to readers for interpretation.
All magnetic resonance images were acquired at 3-Tesla (Achieva 3.0T-TX, Phillips Healthcare, Best, Netherlands) using an endorectal coil (BPX-30, Medrad, Pittsburgh, PA) filled with 45-mL perfluorocarbon-based fluid (Fluorinert, 3M, Maplewood, MN) and anterior half of a 32-channel car-diac SENSE coil (InVivo, Gainesville, FL). All patients underwent complete mpMRI protocol, which consisted of the following sequences: T2W MRI (axial, coronal, sagittal), DWI (ADC map calculated from five evenly spaced b-values between 0 750 s/mm2 and an acquired high b-value image of b-2000 s/mm2), and DCE MRI. Full mpMRI parameters are given in Table 1.