MRI-Directed Contrast-Enhanced Mammography Improves Detection of Breast Lesions

Suspicious lesions detected on contrast-enhanced breast MRI often undergo targeted ultrasound evaluation to determine if they are amenable to ultrasound-guided biopsy. A new study aimed to assess the utility of MRI-directed contrast-enhanced mammography (CEM) performed for biopsy planning of suspicious MRI-detected breast lesions, with comparison to MRI-directed ultrasound. The study found that MRI-directed CEM detects a higher fraction of suspicious MRI lesions than MRI-directed ultrasound and also detects a higher fraction than either method individually.

The retrospective study by researchers at the University of Virginia Health System (Charlottesville, VA, USA) included 120 patients (median age, 50.3 years) who underwent MRI-directed CEM from September 2014 to July 2020 for biopsy planning of a total of 140 suspicious breast MRI lesions; 109 lesions were also evaluated by MRI-directed ultrasound at the same visit. Reference standard was histopathology or at least two years of imaging follow-up for benign lesions. Rates of detecting a correlate for the MRI lesion, among all lesions and among malignant lesions, were compared between MRI-directed CEM, MRI-directed ultrasound, and combined MRI-directed CEM and ultrasound (i.e., correlate detected on either modality) using McNemar's test. Frequencies of imaging modalities used for biopsy guidance after MRI-directed imaging were determined.

The study revealed that 21 of 109 lesions were malignant. The lesion detection rate was higher for MRI-directed CEM than for MRI-directed ultrasound [69.7% (76/109) vs 45.9% (50/109); p<.001], and higher for combined MRI-directed CEM and ultrasound [77.1% (84/109)] than for either MRI-directed CEM (p=.008) or MRI-directed ultrasound (p<.001). The malignant lesion detection rate was not significantly different between MRI-directed CEM and MRI-directed ultrasound [95.7% (22/23) vs. 78.3% (18/23); p=.13]. A total of 31.2% (34/109) of lesions were seen only on MRI-directed CEM, and 7.3% (8/109) were seen only on MRI-directed ultrasound. A total of 17.4% (4/23) of malignant lesions were seen only on MRI-directed CEM, and none were seen only on MRI-directed ultrasound. Among lesions recommended for biopsy, stereotactic- or tomosynthesis-guided biopsy was recommended for 25.2% (26/103), ultrasound-guided biopsy for 35.9% (37/103), and MRI-guided biopsy for 38.8% (40/103).

Based on these findings, the researchers concluded that MRI-directed CEM detects a higher fraction of suspicious MRI lesions than does MRI-directed ultrasound. MRI-directed CEM/ultrasound detects a higher fraction than either method individually. The researchers have suggested that MRI-directed CEM can be a useful alternate or complementary tool to MRI-directed ultrasound in biopsy planning for suspicious MRI lesions, facilitating use of biopsy guidance methods other than MRI guidance.