RESULTS
The mean age, PSA, prostate volume and mean PSAd values for the 84 cases
included in the study were 63.5±7.5 years, 11.68±17.34ng/ml,
62.4±38.08cm3, and 0.23±0.39ng/ml2,
respectively. There were no statistically significant differences
between malignant and benign diseases for age and PSA values. Prostate
volume in the malignant group was found to be significantly lower and
PSAd higher than the benign group
(p<0.001,p<0.001)(Table-3 ).
Of the 106 lesions examined in this study from the 84 patients,
26(24.5%) were benign prostatic tissue, 36(33.96%) were prostatitis,
43(40.46%) were malignant lesions and 1(0.94%) was high-grade
prostatic intraepithelial neoplasia. Among malignant lesions, 65.1%
were localized in the PZ, 14% in the TZ, and 20.9% were diffuse
cancers.
In the PI-RADS groups 1, 2, 3, 4, and 5, there were 5, 4, 54, 25, and 18
lesions identified respectively. No malignancy was detected in any of
the 9 lesions who had PI-RADS-1 and 2. Systematic biopsy was performed
to these patients with the decision of the clinician due to the increase
in PSA, rectal examination findings and the age of the patient. Of the
PI-RADS-3, 4, and 5 lesions, the PCa ratios were 22.2%, 56% and
94.45%, respectively.
Table-4 shows the statistical
parameters in PZ and TZ when the cut-off value PI-RADS≥3 and PI-RADS≥4
taken as positive for cancer detection when T2W and DWI are
independently evaluated. In TZ, there was no patient with a
PI-RADS<3, so the diagnostic parameters for this variable
could not be calculated.
The success of the PI-RADS score to predict cancer was found to have an
AUC value of 0.764 (0.646-0.882) for PZ and 0.629 (0.347-0.910) for TZ
when PI-RADS≥3 positive is considered. Evaluation by excluding the zonal
anatomy and taking the PI-RADS score as ≥3 positive found the cancer
prediction success had AUC values of 0.773 (0.683-0.864), 0.722
(0.621-0.824), 0.740 (0.641-0.838), 0.619 (0.514-0.724), and 0.764
(0.646-0.882) for T2W, DWI, DCE, T2W and DWI combinations
(biparametric), and the T2W, DWI and DCE combination (MpMRI),
respectively.
The sensitivity, specificity, NPV, and PPV values for prostate cancer
detection according to PI-RADSv2.1 and regardless of the zone, for T2W
and DWI independently, for biparametric and MpMRI assessment when
PI-RADS≥3 and ≥4 taken as positive are summarized inTable-5 . When the results for cut-off
value of ≥3 are compared with the results for cut-off value ≥4 inTable-4 andTable-5 , the differences between the
two cut-off values were statistically significantly
different(p<0.001). Accordingly, when the PI-RADS score
cut-off value of ≥4 was taken as positive, the sensitivity and NPV
moderately fall, while specificity and PPV increase.
All lesions in the ISUP>1 group (n=27) were evaluated as
PI-RADS-4 or 5. While 25.47% of all lesions had ISUP>1
observed, 40.56% of the lesions (n=43) were identified to have
PI-RADS-4 and 5. When PI-RADS-3 lesions are evaluated, 22.2% of these
lesions received PCa. In this group, there were no lesions with
ISUP>1 diagnosis. There was a positive correlation between
PI-RADSv2.1 score with ISUP score and the correlation value was
0.814(p<0.001) (Table-6)
In PZ, for the ISUP grades 1, 2, 3, 4, and 5, there were 4(57.1%),
2(28.6%), 0(0%), 0(0%), and 1(14.3%) lesions which upgraded to
PI-RADS group 4 with DWI score 3 and DCE positivity, identified
respectively(Table-7) . For lesions with DWI score 4 and PIRADS 4,
0(%0), 2(33.3%), 2(33.3%), 2(33.3%), and 0 lesions identified
respectively for the ISUP grades 1, 2, 3, 4, and 5. Lesions that are
primary PI-RADS4, were observed to have higher ISUP grades. When grouped
according to ISUP grade 1 and >1, there were significant
differences in terms of the DWI score 3 and 4 percentages
(p:0.03)(Figure-1 ,Figure-2 ).
The interobserver agreement kappa value(κ) for the PI-RADS score,
without applying the cut-off value, was 0.562 which represents moderate
agreement. When PI-RADS cut-off value of ≥3 positive is considered,
kappa was 0.320, which represents fair agreement but when the cut-off
value was determined as ≥4, the kappa is 0.770 which corresponds to a
substantial agreement. Interobserver agreement for T2W was moderate with
kappa:0.575 when PI-RADS≥3 positive taken as the cut-off and reached the
substantial agreement with kappa: 0.814 when PI-RADS≥4 is taken.
Interobserver agreement for DWI was fair with kappa:0.321, when
PI-RADS≥3 is taken as the cut-off value but reached the substantial
level when PI-RADS≥4 is taken as the cut-off(κ=0.757). For DCE
investigation with positive and negative scores evaluation,
interobserver agreement was at substantial levels with κ=0.721.