Adrenal MRI Calculator

Disclaimer: The author makes no claims of the accuracy of the information contained herein; this information is for educational purposes only and is not a substitute for clinical judgment.

CSI ratio: lesion SIOP/spleen SIOP / lesion SIIP/spleen SIIP

SI index: lesion SIIP-lesion SIOP / lesion SIIP x 100

Signal dropout on chemical shift imaging may be limited for metastases containing intracellular lipid, such as clear cell renal cell carcinoma and hepatocellular carcinoma.

Schieda N, Siegelman E. Update on CT and MRI of adrenal nodules. AJR Am J Roentgenol 2017; 208:1-12

In a retrospective study of 42 benign adrenal masses, the CSI ratio had higher specificity than the signal intensity index for lipid-rich adenomas; however, no metastases were included.

Israel GM, Korobkin M, Hecht EN et al. Comparison of unenhanced CT and chemical shift MRI in evaluating lipid-rich adrenal adenomas. Am J Roentgenol 2004; 183:215-219

In a study of 102 adrenal tumors, all adenomas had signal intensity indexes at least 16.5%, and all metastatic tumors had signal intensity indexes at most 11.2%.

Fujiyoshi F, Nakajo M, Fukukura Y, et al. Characterization of adrenal tumors by chemical shift fast low-angle shot MR imaging: comparison of four methods of quantitative evaluation. Am J Roentgenol 2002; 180:1649-1657

One study showed MRI to be equivalent to CT for characterizing adenomas measuring 20 HU or less. However, MRI is less sensitive than CT for lipid-poor adenomas measuring more than 20 HU.

Seo JM, Park BK, Park SY, Kim CK. Characterization of lipid-poor adrenal adenoma: chemical-shift MRI and washout CT. Am J Roentgenol 2014; 202:1043-50