Unenhanced breast magnetic resonance imaging: detection of breast cancer.

OBJECTIVE: To evaluate the diagnostic performance of unenhanced MRI (UE-MRI) 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 <0.001). 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 DWI). CONCLUSIONS: UE-MRI may be employed in patients with contraindication to gadolinium. It has considerable specificity and positive predictive value and good reproducibility.

MRI evaluation of neoadjuvant low-dose fractionated radiotherapy with concurrent chemotherapy in patients with locally advanced breast cancer.

OBJECTIVES: We address the diagnostic performance of breast MRI and the efficacy of neoadjuvant radiochemotherapy (NRC) treatment (NRC protocol) vs conventional neoadjuvant chemotherapy (NAC) in patients with locally advanced breast cancer. METHODS: The NRC protocol consists of six anthracycline/taxane cycles and concomitant low-dose radiotherapy on breast tumour volume. Breast MRI was performed at baseline and after the last therapy cycle in 18 and 36 patients undergoing the NRC protocol or conventional NAC (propensity matching). RESULTS: In both groups, we observed reduced tumour dimensions after the last cycle (p<0.001), and the response evaluation criteria in solid tumours (RECIST) class directly correlated with the tumour regression grade class after the last cycle (p<0.001). Patients in the NRC group displayed a higher frequency of complete/partial response than those in the NAC group (p=0.034). 17 out of 18 patients in the NRC group met the criteria for avoiding mastectomy based on final MRI evaluation. The RECIST classification displayed a superior diagnostic performance in the prediction of the response to treatment [area under the receiver operating characteristic curve (AUC)=0.72] than time-to-intensity curves and apparent diffusion coefficient (AUC 0.63 and 0.61). The association of the three above criteria yielded a better diagnostic performance, both in the general population (AUC=0.79) and in the NRC and the NAC group separately (AUC=0.82 and AUC=0.76). CONCLUSIONS: The pathological response is predicted by MRI performed after the last cycle, if both conventional MRI and diffusion imaging are integrated. The NRC treatment yields oncological results superior to NAC. Advances in knowledge MRI could be used to establish the neoadjuvant protocol in breast cancer patients.