Keywords:
Genital / Reproductive system male, Pelvis, MR, MR-Diffusion/Perfusion, MR-Spectroscopy, Observer performance, Outcomes analysis, Structured reporting, Cancer
Authors:
D. Gutierrez, O. Chirife, C. Pineda; Barcelona/ES
DOI:
10.1594/ecr2013/C-0968
Methods and Materials
Patients: In 2008 our institution began routinely performing mpMRI of the prostate.
The gross of the studies were acquired for local staging,
restaging and postsurgical evaluation.
We reviewed our hospital records for:
- Patients referred by urologists under suspicion of prostatic carcinoma (elevation of PSA) and at least one previous TRUS biopsy in which a new targeted biopsy was considered. [Following mpMRI,
all patients underwent targeted TRUS biopsies performed by the urologists,
who were aware of the imaging findings.]
- 14 patients met the inclusion criteria.
mpMRI protocol:
- T2w images (fast spin-eco) acquired in the three planes.
- DWI using different b-values with an apparent diffusion coefficient (ADC) map in the axial plane.
- DCE MRI obtained by fat saturated T1w (fast field echo sequence) following intravenous bolus injection of 0.1 mMol/kg of Gadobutrol.
- 3D MR spectroscopic imaging of the entire prostate using a section-selected box drawn closely around the prostate and a point-resolved spectroscopic sequence.
Scoring and evaluation of image data:
- mpMRI data sets were retrospectively evaluated and scored according to the 5-point PI-RADS scale (as depicted in the ESUR 2012 guidelines) without prior knowledge of the prostate-specific antigen level or biopsy results.
- Radiologists 1 (D.G.R) and 2 (O.C.C) independently interpreted and scored all five data sets.
The two radiology residents (third year) had similar levels of experience in evaluating prostate MR images.
Data analysis: The elementary units for analysis were the prostate mpMRI results represented in PI-RADS scores (5 subscores and a total sum score),
and the presence or absence of prostate cancer in the targeted biopsy result.
- The interobserver reliability: we used a linear weighted Kappa in order to take into account the degree of disagreement between observers.
- The relationship between PI-RADS scores and histological results: were assessed by the U Mann Whitney test.
Results are given for each observer and in a conjunct manner.
All p values reported were derived at two-sided tests; P< 0.05 was considered to indicate statistical significance.