HIGH SPECTRAL AND SPATIAL RESOLUTION IMAGING

Conventional magnetic resonance imaging has good sensitivity for detecting breast lesions but its specificity is inadequate. High Spectral and Spatial Resolution (HiSS) Magnetic Resonance Imaging (MRI) of water and fat signals may increase both sensitivity and specificity of MRI. HiSS MRI equals or exceeds the spatial resolution of conventional MRI and provides detailed spectra of the water and fat in each voxel. The water and fat lineshapes are analyzed to produce images proportional to water resonance linewidth, peak height, integral, changes following contrast media injection, and other parameters. HiSS MRI images are acquired with clinically acceptable run times using echo-planar spectroscopic methods.

For a 3D view composed of water peak height images click here.

HISS FOR EARLY DETECTION OF DCIS

NIH-funded work in this laboratory demonstrated quantitatively that contrast, edge delineation, and sensitivity to contrast agents in breast images derived from HiSS data are improved compared to conventional images. We are now working to test the method in a large group of women with focal breast abnormalities in order to evaluate whether HiSS MRI improves diagnostic accuracy when combined with conventional MRI, and to extend the quantitative comparisons between HiSS and conventional MRI. We will test HiSS MRI in women with suspicious microcalcifications that may be associated with ductal carcinoma in situ (DCIS). In clinical practice these patients are referred for biopsy, and the biopsies are frequently negative. As a result there is unnecessary anxiety, discomfort, and cost. In addition, some cancers may be missed because of inadequate sampling on biopsy.

We are using HiSS MRI to scan the location of the microcalcifications. This is an appropriate target for HiSS MRI in its current form because it is localized and has complex morphology. We will test the hypothesis that: Addition of HiSS to conventional MRI exams in women who may have DCIS increases diagnostic accuracy. Women with suspicious breast lesions (n=300) who are scheduled for routine clinical MRI scans prior to biopsy are recruited for this study. Experimental HiSS MRI scans will be integrated into the conventional MRI protocol. We will determine whether addition of HiSS data to conventional data increases sensitivity and specificity. In addition, HiSS images will be quantitatively compared to conventional images. Biopsy results serve as the ‘gold standard’.

HISS WITH PARALLEL IMAGING

MULTISLICE HISS

IMPROVED ACQUISITION AND PROCESSING FOR HISS DATA

The specificity for detection of DCIS based on micro-calcifications is unacceptably low – only 20%-30% of women with MC’s on mammography are found to have DCIS when they are biopsied. This means that the majority of biopsies secondary to suspicious MC’s are unnecessary. Diagnostic accuracy might be improved by using dynamic contrast enhanced magnetic resonance imaging (DCEMRI) as an adjunct to conventional X-ray mammography. DCEMRI has excellent soft tissue contrast as well as sensitivity to tumor blood flow but a number of recent studies suggest that its specificity is not high enough for routine clinical use. We believe that this is in part because the temporal resolution of most DCEMRI studies has not been adequate to detect small regions of dense vasculature associated with rapidly proliferating cancer. These regions may be characterized by rapid uptake and washout of contrast media following injection and could be missed by conventional low time resolution imaging. We are working to determine whether high temporal resolution (HiTs) MRI can identify breast abnormalities in the vicinity of micro-calcifications and distinguish DCIS from benign conditions. HiTs images from the breast are acquired with temporal resolution of a few seconds during the first pass of the contrast media bolus following I.V. injection.

The research tests the hypothesis that: Contrast-enhanced high temporal resolution MRI yields increased sensitivity to the angiogenic, invasive, and structural properties of ductal carcinoma in-situ. As a result, HiTs MRI can be used to more accurately identify and stage DCIS associated with suspicious MC’s found on mammography.