The Differential Diagnosis Between Benign And Malignant Adrenal Lesions By Spectral CT Imaging

Objective: To distinguish benign and malignant adrenal lesions by quantitativeanalysis in gemstone computed tomography (CT) spectral imagingMaterials and Methods: This study was approved by local ethics committeeand the patient informed consent was obtained. From Jun．2011to Mar．2012，retrospective analysis72patients (33men,39women) with adrenal mass and10(6men,4women)patients with normal adrenals，scanned on a64-slice CT scanner(Discovery CT750HD, GE) with gemstone spectral imaging in the arterial phase.101sets of monochromatic images (40-140keV), iodine-and fat-based maps weregenerated automatically. Spectral curve and material content of different lesions andareas were obtained. The iodine and fat concentrations, slope of the spectral curve(λ_HU) and CT values on quality check images were recorded and compared amongdifferent pathologic categories. All the lesions were confirmed by pathologicfindings，sampling through adrenal gland vein or clinical follow-up.Results: A total of128lesions including54adrenal hyperplasia (group A),33adrenal adenomas (group B),21adrenal metastases (group C) as well as20normaladrenals (group D) were analyzed. One-factor analysis of variance showed that theiodine concentration, fat concentration, and λ_HUvalues of the malignant lesions(group C,3.40±0.98,985.12±6.52and1.55±0.13) were significantly lower thanthose of benign lesions (group A,4.18±0.76,993.37±3.65and1.84±0.13, group B,4.65±0.89,997.95±4.32and1.98±0.12)(both P＜0.001). There were alsosignificant difference in iodine concentration, fat concentration, and λ_HUvalues between group B/C and D (both P＜0.01). No significant difference was found iniodine concentration (P=0.96), fat concentration (P=0.37) and λ_HU(P=0.14) betweengroup A and D. Regarding average CT values, no statistical differences existedamong groups A, B, C and D (P=0.70).Conclusion: CT spectral imaging in the arterial phase has potential indifferential diagnosis between benign and malignant adrenal lesions anddistinguishing adrenal hyperplasia and neoplasm.