This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Tumors of the adrenal glands are common in the general population. As a result of the widespread use of cross sectional imaging techniques, such tumors are often incidentally detected. Adrenal tumors are found in approximately 0.35% - 4.36% of patients who undergo CT imaging for reasons unrelated to the adrenal glands, and the incidence of these tumors increases with age. The majority of adrenal tumors are harmless, and can be left alone. Therefore, it is necessary to characterize these tumors to avoid unnecessary surgery or diagnostic procedures. Benign adrenal tumors will be further referred to as 'adrenal adenomas'. Many adrenal adenomas can be easily identified on computed tomography without the use of intravenous contrast material, by demonstrating their fat content. Fat is typically seen in benign adrenal tumors and is rare in malignant adrenal lesions. There is, however, a subgroup of adrenal adenomas, the so-called lipid poor adrenal adenomas, whose fat content is too low to be easily detected. Such lesions pose a serious diagnostic problem, especially in patients with history of malignancy. Definitive characterization of such lesions is often achieved with contrast enhanced CT, which involves exposure to ionizing radiation and the risks associated with the use of iodinated contrast medium. Such risks include possible contrast allergy and toxic impairment of marginally functioning kidneys. Iodinated contrast related kidney impairment is kidney function and contrast dose dependent. MR imaging is an effective alternative method for characterizing adrenal masses. It does not involve ionizing radiation or use of intravenous iodinated contrast material. A technique called chemical shift is used in MR imaging to characterize adrenal lesions. This technique exploits imaging the additive and subtracted signal of fat and water in a volume of tissue. While chemical shift MR imaging is as good as non-contrast CT for diagnosing adenomas with high fat content, there is no consensus regarding its utility for characterizing adrenal adenomas with minimal fat content that cannot be characterized by non-contrast CT. This in part is due to the outdated techniques used in older studies addressing this subject. Technical advances in MR imaging with the use of specialized coils for abdominal imaging, and new sequences, allow detection of small amounts of fat in adrenal lesions. A new MRI sequence called the Dual Echo gradient echo, which can be acquired in a single breath-hold, helps eliminate potential sources for imprecise measurements of fat in adrenal tumors, such as misregistration artifacts. So far, no studies have been published to evaluate the accuracy of dual echo chemical shift MR imaging for characterizing lipid poor adrenal lesions. We plan to recruit men and women 18 years of age or older with adrenal masses who have undergone a dedicated CT of the adrenal gland. These patients will undergo an MRI scan, usually 15-20 minute scan without intravenous contrast. If dual echo chemical shift MR imaging proves to be an accurate imaging tool for identifying adrenal adenomas with low fat content that cannot be reliably identified by non-contrast CT, patients will benefit from the advantages of this imaging method including the lack of ionizing radiation, and absence of risk of nephrotoxicity and allergy to iodinated intravenous contrast material.
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