LIPID-POOR ADRENAL MASSES: EVAL W/ DUAL ECHO CHEMICAL SHIFT MR IMAGING

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。肾上腺肿瘤在普通人群中很常见。由于广泛使用的横断面成像技术，这类肿瘤经常被偶然发现。由于与肾上腺无关的原因接受CT成像的患者中，约0.35% - 4.36%的患者发现肾上腺肿瘤，并且这些肿瘤的发病率随着年龄的增长而增加。大多数肾上腺肿瘤是无害的，可以任其发展。因此，有必要确定这些肿瘤的特征，以避免不必要的手术或诊断程序。良性肾上腺肿瘤将进一步被称为“肾上腺腺瘤”。许多肾上腺腺瘤可以在计算机断层扫描上很容易地识别，而无需使用静脉造影剂，通过显示其脂肪含量。脂肪通常见于良性肾上腺肿瘤，而在恶性肾上腺病变中少见。然而，有一种肾上腺腺瘤亚组，即所谓的低脂肾上腺腺瘤，其脂肪含量过低，不易检测。这样的病变造成了严重的诊断问题，特别是在有恶性肿瘤病史的患者中。这种病变的明确特征通常是通过增强CT来确定的，这涉及到电离辐射暴露和使用碘化造影剂的风险。这些风险包括可能的造影剂过敏和对肾功能的毒性损害。碘造影剂相关肾损害是肾功能和造影剂剂量依赖性的。磁共振成像是表征肾上腺肿块的有效替代方法。它不涉及电离辐射或使用静脉碘化造影剂。一种称为化学位移的技术被用于磁共振成像来表征肾上腺病变。这项技术利用成像的脂肪和水的加法和减法信号的组织体积。虽然MR化学位移成像在诊断高脂肪含量的腺瘤方面与非对比CT一样好，但对于其在诊断非对比CT无法诊断的低脂肪含量肾上腺腺瘤方面的应用，尚未达成共识。这在一定程度上是由于在解决这个问题的旧研究中使用了过时的技术。磁共振成像技术的进步，使用专门的线圈进行腹部成像，以及新的序列，可以检测到肾上腺病变中的少量脂肪。一种新的MRI序列称为双回声梯度回波，可以在一次屏气中获得，有助于消除肾上腺肿瘤中脂肪测量不精确的潜在来源，如误配伪影。到目前为止，还没有发表研究来评估双回波化学位移磁共振成像在表征脂质不良肾上腺病变方面的准确性。我们计划招募年龄在18岁或以上的有肾上腺肿块的男性和女性，他们已经接受了专门的肾上腺CT检查。这些患者将接受核磁共振扫描，通常是15-20分钟的扫描，不需要静脉造影剂。如果双回声MR化学位移成像被证明是一种准确的成像工具，可以识别非对比CT无法可靠识别的低脂肪含量肾上腺腺瘤，患者将受益于这种成像方法的优点，包括缺乏电离辐射，没有肾毒性和对碘静脉对比剂过敏的风险。

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.