Time to Enhancement of Foci Relative to Background Parenchymal Enhancement on Ultrafast Breast MRI: A Single-Center...

BACKGROUND. Breast MRI is a sensitive tool for detecting small cancers. However, differentiating benign and malignant lesions remains challenging, particularly for foci. Studies evaluating other lesion types have identified ultrafast MRI (UFMRI) parameters associated with malignancy. OBJECTIVE. The purpose of this study was to determine whether kinetic features of UFMRI can differentiate malignant from nonmalignant foci. METHODS. This single-center retrospective study selected consecutive UFMRI examinations conducted from July 2019 to April 2023 with subsequently performed MRI-guided biopsy. Patient characteristics and lesion features were collected from the EMR, imaging reports, and imaging review. Focus and background parenchymal enhancement (BPE), time to enhancement (TTE), and the difference between focus TTE and BPE TTE were calculated. Associations with malignancy were assessed with univariable and multivariable logistic regression. RESULTS. A total of 124 patients (mean age, 53 years old; range, 29-78 years old) underwent biopsy of 124 foci. Sixty-four patients (51.6%) were postmenopausal, 71 (57.3%) had a personal history of breast cancer, and 81 (65.3%) had a family history of breast cancer. Of the 94 patients who underwent genetic testing, 33 (35.3%) had genetic mutations. Most examinations were performed to evaluate the extent of disease (47.6% [59/124]), followed by screening (41.9% [52/124]). Patients predominantly had heterogeneous fibroglandular tissue (58.1% [72/124]) and mild BPE (57.3% [71/124]). Of 124 lesions, 21 (16.9%) were malignant; of these, 16 were invasive and five were ductal carcinoma in situ. The odds of malignancy increased 5% with each 1-second increase in the difference between lesion TTE and BPE TTE (95% CI, 2-9%; p = .006). Older age and lower BPE were associated with increased likelihood of malignancy (p = .005 and p = .02, respectively). The odds of malignancy for patients with minimal or mild BPE were 11.69 times the odds for those with moderate or marked BPE (95% CI, 1.51-90.67). No other demographic or lesion characteristics were predictive of malignancy. CONCLUSION. Earlier visualization of a focus relative to BPE on UFMRI was associated with increased likelihood of malignancy; morphologic features showed no association with malignancy. CLINICAL IMPACT. The difference between focus TTE and BPE TTE may be a useful parameter for assessing malignancy, which could help reduce unnecessary biopsies.