Introduction: We have developed a new method for spectroscopic imaging of adrenal masses. Adrenal masses are common, occurring in up to 9% of the population. While benign adrenal adenomas are the most common type of adrenal mass, both primary and metastatic neoplasms occur as well. Opposed phase GRE imaging with MRI has shown good results, but the degree of signal overlap between benign and malignant lesions evaluation of disease in individual patients difficult. Spectroscopic imaging of the adrenal glands may provide insight into the nature of adrenal masses and increase our ability to distinguish benign from malignant neoplasms. Methods: Our short echo time spectroscopic imaging sequence is based upon half-pulse excitation, in which two excitations are combined to form a slice. The excitation is immediately followed by PR spectroscopic readout gradients. Results: Twelve patients with adrenal masses have been studied. Mass types were determined by either biopsy, long-term stability and imaging findings, or imaging and clinical findings. Adenomas, primary neoplasms, and metastatic lesions were imaged. Short echo time spectroscopic data showed excellent correlation with the opposed phase GRE images. The primary and metastatic lesions studied showed no lipid peaks visible above noise. Figure 1a shows a water frequency image from a multi-slice data set of a patient with a 2 cm left adrenal adenoma. Figure 1b shows a spectra from within the adenoma. This voxel contained approximately 17 % lipid by the ratio of the lipid to water peak. Conclusion: Short echo time spectroscopic imaging of adrenal masses may provide a new way help differentiate benign from malignant lesions. Since spectra from each voxel can be examined, this method may prove more specific than current techniques.
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