MR dynamic enhancement of breast lesions: High temporal resolution during the first-minute versus eight-minute study

Purpose: To investigate the value of the early phase of MR enhancement of b reast lesions. Method: To study 63 breast lesions (size 5-45 mm in diameter) in 56 patient s, whole-breast and lesion-targeted precontrast Tl-weighted gradient-echo 2 D sequences were acquired. After intravenous injection of Gd-DTPA (0.1 mmol /Kg), four targeted scans, each every 15 seconds during the first minute (1 -m), and seven whole-breast scans, each every minute up to 8 minutes (8-m), were performed. The subtraction technique was used, and percent enhancemen t curves were obtained. The final diagnosis was obtained by histology for 3 6 lesions, including 28 malignancies, and by Fine-needle aspiration cytolog y and at least 1-year negative follow-up for the remaining 27 benign lesion s. Results: Significant differences in enhancement between malignant and benig n lesions were found using both techniques (p < 0.0001). However the ratio between the median enhancement of malignant lesions and that of benign lesi ons was 0.7 (15 s), 4.8 (30 s), 4.6 (45 s), and 3.8 (60 s), descending from 4.3 to 2.5 from the second to the eighth minute. The overlap between the m alignant and benign curves was 9% of the malignant range with the 1-m techn ique, and 50% with the 8-m technique. Three blinded observers obtained a 10 0% sensitivity with both techniques and a specificity of 94-97% with the 1- m technique and 83-89% with the 8-m technique. Conclusion: The first minute of Gd-enhancement allows a more prominent diff erentiation between malignant and benign breast lesions than the following times.