DYNAMIC GRADIENT-ECHO AND FAT-SUPPRESSED SPIN-ECHO CONTRAST-ENHANCED MRI OF THE BREAST

Purpose: To evaluate heavily TZ-weighted, dynamic contrast-enhanced an d fat-suppressed magnetic resonance imaging (MRI) of the breast in com parison with conventional imaging and fine needle aspiration cytology (FNAC). Patients and Methods: Fifty patients with surgically/pathologi cally proven breast disease were examined pre-operatively by MRI. The majority, 45 patients, had invasive carcinoma, T1-weighted spin-echo, TZ-weighted fast spin-echo (with chemical-shift-selective fat-suppress ion in 20 cases), rapid dynamic contrast-enhanced gradient-echo and po st-contrast fat-suppressed T1-weighted images were obtained. Signal in tensity changes during dynamic scanning were assessed qualitatively an d quantitatively. Comparison was made with the results of X-ray mammog raphy, ultrasound and fine needle aspiration cytology. Results: Unenha nced MRI was inadequate for determining the location, extent or nature of most lesions even when fat-suppressed TZ-weighted images were obta ined. Following contrast injection, there was significantly greater en hancement of invasive carcinomas than normal parenchyma. Invasive carc inomas of ductal and lobular subtypes did not differ significantly in their enhancement profiles, Prominent enhancement of the lesion periph ery, which was a feature in 33 out of 50 cases (the majority of which were invasive carcinomas) was not due to central tumour necrosis. In f our cases, invasive carcinomas which were clearly visible on early dyn amic scans could not be identified on post-contrast fat-suppressed ima ges. Lesions that were more numerous or extensive than had been recogn ised clinically or mammographically were revealed by MRI in 14 patient s, though MRI: was no more specific than conventional assessment. Inva sion of the chest wall was accurately predicted by MRI in three cases. There was excellent correlation between tumour size shown by MRI and histopathology, FNAC was accurate in predicting the final histological diagnosis except in those cases where samples were unsatisfactory. Co nclusions: Contrast-enhanced MRT appears useful in the assessment of s uspected malignant breast masses, especially in younger women with pre dominantly glandular breast tissue. Specificity is no better than FNAC but tumour extent and multifocality are more accurately disclosed tha n by conventional imaging techniques. Contrast-enhanced chemical-shift -selective fat-suppressed images are sub-optimal in a small proportion of cases (particularly where lesions are located posteriorly) and som e benign breast disease may appear misleadingly conspicuous on such im ages. Morphological features and quantification of lesion enhancement during dynamic scanning presently offer only limited prospects for dis crimination between various pathologies. Heavily TZ-weighted sequences appear of marginal value.