Role of quantitative chemical shift magnetic resonance imaging and chemical shift subtraction technique in discriminating adenomatous from non adenomatous adrenal solid lesions

Abstract

PurposeTo evaluate role of quantitative assessment of chemical shift MR imaging and chemical shift subtraction technique in differentiating adenomatous from non-adenomatous adrenal lesions with comparison of accuracy level of each technique. Materials and methodsA prospective study was carried out from 4-2014 to 5-2016 using 1.5T MRI. In-phase/opposed phase MRI sequences were applied for 52 patients having 58 adrenal lesions, 18 were hyper functioning and 40 were non-functioning. Lesions signal changes between in- and opposed phase sequences and post processing was done to calculate different quantitative chemical shift parameters using spleen, paraspinal muscle, and liver as a reference tissues. Additionally subtraction chemical shift MR technique on selected 16 cases was applied. ResultsSignal intensity index and the two formulas of adrenal to spleen ratio were more accurate than other quantitative chemical shift MRI parameters in discrimination between adenomatous and nonadenomatous adrenal lesions with selected cutoff value 23.4% for the signal intensity index, 0.72 and −27.82% for adrenal to spleen ratio% using the old and new formulas respectively. Chemical shift subtraction technique expressed significant difference between adenomas and non-adenomatous adrenal lesions where adenomas had ratio of 108.87 or more, and the non-adenomatous lesions had ratio of 47.74 or less with selected cutoff value 173.0475. ConclusionThe signal intensity index and adrenal to spleen ratio are the most reliable quantitative chemical shift MRI methods in differentiation of adrenal adenomas from other non-adenomatous adrenal solid lesions. Chemical shift subtraction MRI is a recent technique that gives highly confident discrimination between two categories of pathology without using of any reference organ.