Abstract
Purpose
To evaluate the effect of varying spectral resolution on image quality of high spectral and spatial resolution (HiSS) images.
Materials and Methods
Eight women with suspicious breast lesions and six healthy volunteers were scanned using echo‐planar spectroscopic imaging (EPSI) at 1.5 Tesla with 0.75‐ to 1‐mm in‐plane resolution and 2.3‐ to 2.6‐Hz spectral resolution. Time domain data were truncated to obtain proton spectra in each voxel with varying (2.6–83.3 Hz) resolution. Images with intensity proportional to water signal peak heights were synthesized. Changes in water signal line shape following contrast injection were analyzed.
Results
Fat suppression is optimized at ∼10‐Hz spectral resolution and is significantly improved by removal of wings of the fat resonance. This was accomplished by subtracting a Lorentzian fit to the fat resonance from the proton spectrum. The water resonance is often inhomogeneously broadened, and very high spectral resolution is necessary to resolve individual components. High spectral resolution is required for optimal contrast in anatomic features with very high T~2~* (e.g., within a lesion) and for detection of often subtle effects of contrast agents on water signal line shape.
Conclusion
Despite a trade‐off between the spectral resolution and signal‐to‐noise ratio, it is beneficial to acquire data at the highest spectral resolution currently attainable at 1.5 Tesla. J. Magn. Reson. Imaging 2003;18:442–448. © 2003 Wiley‐Liss, Inc.