Noncontrast-enhanced MRI for Evaluation of Breast Lesions: Comparison of Noncontrast-enhanced High Spectral and Spatial Resolution (HiSS) Images versus Contrast-enhanced Fat-suppressed Images

Abstract

This issue of Academic Radiology contains a report by Medved et al (1) on their experience with noncontrast breast magnetic resonance imaging (MRI) in the evaluation of breast lesions using high spectral and spatial resolution (HiSS). Within the constraints of the study protocol, the analysis of their data shows that differentiation of benign from malignant lesions using their noncontrast technique was comparable to that achieved with dynamic contrast MRI. The transformation of breast MRI into a noncontrast examination remains hypothetical, but some of the advantages that could be conveyed by noncontrast MRI technology are obvious. Contrast is expensive and requires placement of an intravenous line for administration. Its elimination would decrease cost and discomfort. For those few women with allergy to the contrast material or impaired renal function, MRI could become a feasible study. The usefulness of an imagining technique that is not limited by the time constraints of contrast washout in performing biopsy, particularly multiple sites or both breasts, is also self-evident. In the analysis of specific sites within the breast, the use of HiSS with other noncontrast MRI techniques could convey additional advantage to noncontrast MRI. Spectroscopy requires identification of the volume of the breast to be evaluated, as does the HiSS technique reported in this journal. Spectroscopy does not require contrast. If identification of the breast volume undergoing analysis could be done without usingcontrast,a noncontrastexamination could beperformed specifically to obtain high spatial resolution MRI images with spectroscopy data. Because HiSS enables MRI to be done with increased spatial resolution, significant improvement in the ability to diagnose disease could result. It is well known in breast imaging that fine imaging details can hold the key to diagnosis. Small spicules, not seen on routine mammogram but visualized only with magnification technique, convert the breast imager’s impression of a benign entity to that of a possible malignancy. Within the context of MRI, the failure of MRI to image microcalcifications associated with breast carcinoma is a well-known cause of false-negative studies (2). If spatial resolution on MRI could be developed to the extent that microcalcifications were included in the data acquired during MRI, this would represent a significant advance in MRI imaging of breast disease. The ability to image such fine detail has been beyond the capabilities of MRI but has been one of the goals of improved MRI technology. Higher strength magnets have been incorporated into clinical MRI to achieve improved of spatial resolution, among other goals. This has led to the progressive increase in magnet strength from early equipment using 0.5 Tesla magnets to current technology incorporating 3.0 Tesla magnets. Although limited by its single-slice application in this report, HiSS imaging of specific lesions within the breast might improve diagnostic accuracy. As an isolated MRI technique eliminating the need to administer contrast, HiSS has the obvious limitation of sacrificingkineticdata.Thereislittledoubtthatasspatialreso