Abstract. – OBJECTIVE: To evaluate the diagnostic
performance of unenhanced MRI (UEMRI)
for malignant breast lesions and its reproducibility.
PATIENTS AND METHODS: We retrospectively
included 118 patients who had breast MRI.
DWI and STIR images were read in combination
and referred to as UE-MRI; the presence or absence
of the malignant lesion was noted by two
observers. Their results were compared with
those of final histopathology or with a two-year
negative follow-up for diagnostic performance
assessment; ROC curves were built. Diagnostic
performance was stratified according to lesion
site and size. Interobserver agreement was evaluated
through the Cohen’s k statistic.
RESULTS: Specificity of STIR and DWI was
99.3% and 95.7% for Reader 1; 99.3% and 96.4%
for Reader 2. Sensitivity was 76.5% and 76.5%
for Reader 1; 77.5% and 77.6% for Reader 2. The
ROC AUC (Reader 1) was 0.869 and 0.844 for
STIR and DWI, respectively (p<0.001 both); for
Reader 2, values were 0.874 and 0.853 respectively
(p<0.001 both). Lesion dimension ≤10 mm
was associated with lower AUC values. Lesion
site didn’t influence the diagnostic performance.
Interobserver agreement was very good for
STIR and DWI (k=0.887, p <0.001, and k=0.867, p
DISCUSSION: UE-MRI has a good overall diagnostic
performance in the detection of breast
cancer and a very good specificity for both
STIR and DWI sequences. We observed reduced
diagnostic performance for lesions ≤10
mm in size. Lesion’s site isn’t associated with
a significantly decreased diagnostic performance
of UE-MRI. There’s a good interobserver
agreement for both sequences (STIR and
CONCLUSIONS: UE-MRI may be employed in
patients with contraindication to gadolinium. It
has considerable specificity and positive predictive
value and good reproducibility.