Value of MRI in differential diagnosis of primary architectural distortion detected by mammography

Abstract

Objective The aim was to evaluate the diagnostic value of MRI in lesions with architectural distortion manifested in mammography. Methods A retrospective analysis of MRI was performed in 60 patients with 61 lesions manifested as architectural distortion in full - field digital mammography (FFDM) and subsequently confirmed by pathology or two year's follow-up, 30 were malignant and 31 were benign. All the patients underwent MRI within 2 weeks of mammography. MRI protocol included conventional MR, DWI and dynamic contrast-enhanced MRI. The breast imaging reporting and data system (BI-RADS) was used as the reference standard. BI-RADS categories 1 to 3 were considered as negative for malignancy and BI-RADS categories 4 to 5 were considered as positive for malignancy. ADCs of suspicious lesion of interest and glandular tissue were calculated. nADC was then calculated using the following formula: nADC=ADC (lesion)/ADC (glandular tissue). ADC and nADC were compared by using t test. ROC analysis was carried out to define the most effective threshold ADC and nADC value to differentiate malignant from benign lesion in the breast. Diagnostic performance of the FFDM, DCE - MRI and DCE-MRI combined nADC were calculated. Results ADC value of malignant and benign lesions was (1.35±0.31) ×10-3 mm2/s and (1.07±0.40)×10-3 mm2/s, respectively . nADC values were 0.83±0.17 and 0.59±0.25, respectively (t values were 2.82 and 4.54, P<0.01). Area under the curve of ADC and nADC were 0.829 and 0.753 respectively. When threshold of ADC was set at 1.19×10-3mm2/s, sensitivity and specificity were 71.0% and 86.7%, respectively. For a nADC value threshold of 0.589, sensitivity and specificity were 93.5% and 76.7%, respectively. Sensitivity, specificity and accuracy with FFDM were 80.0%(24/30), 9.7% (3/31) and 44.3%(27/61), Sensitivity, specificity and accuracy with DCE-MRI were 90.0%(27/30), 41.9% (13/31) and 65.6%(40/61), Sensitivity, specificity and accuracy with DCE-MRI combined nADC were 93.3% (28/30), 77.4%(24/31) and 85.2%(52/61), respectively. Conclusion Sensitivity and specificity with DCE-MRI combined nADC is higher, and DCE-MRI combined nADC values is helpful to differentiate malignant from benign lesions with architectural distortion manifested in FFDM. Key words: Breast neoplasms; Mammography; Magnetic resonance imaging