Patient selection Fig. 1
84 patients suspected to have PCa on the basis of clinical or laboratory data were enrolled in this retrospective study.
The median age of the patients was 69,4 (64,2-72,3) and the median serum PSA level was 11,2 ng/mL.
All recruited patients underwent a mp-MRI and a TRUS-biopsy was perfomed with a time gap not exceeding 2 months or within at last 6 weeks before mp-MRI.
No one of the enrolled patients had a MRI/TRUS-fusion biopsy.
Patients under pharmacological treatment for Benign Prostate Hypertrophy (BPH) with 5-alpha reductase inhibitors (Finasterid or Dutasterid) and α1-blockers (Tamsulosin) and patients under treatment for cardiovascular disease were excluded since these drugs can affect prostate vascularization and cellularity,
distorting TTP and ADC measurements,
respectively.
They were also excluded if the images were not satisfactory (multiple artifacts from,
for example,
total hip replacements,
patient movements).
Acquisition Protocol Fig. 2
Each patient underwent mp-MRI on a 3T MRI scanner (Signa EXCITE®HDxT,
GE,
Milwaukee,
USA) according to Prostate Imaging and Reported Data System Version 2 (Pi-RADS v2) guidelines of 2015 with a pelvic coil (Phased Array,
8 channels).
To suppress peristalsis of the bowels,
intravenous injection of hyoscine butylbromide (Buscopan®,
20 mg,
Boehringer,
Taiwan) was administered immediately before the examination started.
All patients underwent para-axial T2-WI (Fast Recovery Fast Spin Echo-XL 90) parallel to the short axis of prostate and sagittal and paracoronal T2-WI parallel to the long axis. The diffusion study was then done by acquiring a single-shot echoplanar imaging sequence (DWI EPI) using two different b values (0,
1000) in a single acquisition. T1 Spoiled Gradient Echo was acquired before and after contrast administration.
Bolus injection of Gd-DTPA (Prohance® 279,3 mg/ml,
flac.
15 ml i.v.,
Bracco,
Italy) was performed by a power injector (Medrad®) with an injection rate of 4 ml/sec.
followed by a 20 ml flush with saline.
Image analysis Fig. 3
Image interpretation was carried out simultaneously by a specialized radiologist and a resident in radiology with respectively 14 years and 3 years of experience in prostate MRI.
Regions of Interest (ROIs) were settled on suspected foci and on contralateral healthy tissue.
Post processing quantitative data were recorded on DWI and DCE-MRI sequences: ADC and TTP were matched to GS after sextant biopsy and/or radical prostatectomy.
Histological Evaluation
All sample obtained at biopsy were fixed in paraffin and stained with Ematoxylin-Eosin (EE).
Each lesion was graded according to the Gleason Score System.
Only 7 patients,
after TRUS-biopsy,
underwent to Radical Prostatectomy and surgical specimens obtained were processed: gross histological sections were fixed in paraffin,
stained with EE and then evaluated according to modified Gleason Score System.
Measurements and Statistical Analysis
Data from mp-MRI were matched with the prostate biopsy or radical prostatectomy,
which were considered as the standard of reference.
Each pathological sample was matched to a corresponding MR image on the basis of the location.
A one-way ANOVA was used to analyse whether mean ADC and TTP values depend on clinical and histological features of the cancer.
A p value of 0,05 or less was considered to indicate statistically significant difference between the three protocols.
Statistical Analysis was performed using MedCalc® software,
version 13.0.6.