The Value Of CT Spectral Imaging In Differential Diagnosis Of Adrenal Cortical Adenoma And Small Metastasis From Lung Adenocarcinoma

Objective To study the value of Gemstone spectral imaging in differential diagnosisby a comparison of the differences of CT spectral imaging parameters between adrenalcortical adenoma and small metastasis from lung adenocarcinomaMethods CT spectral imaging was performed on nineteen cases of pathologicallyproven adrenal cortical adenoma (total20nodes), recorded as adenoma group, andtwelve cases of small metastasis from lung adenocarcinoma (total18nodes) withclinical data and pathological diagnosis, recorded as metastasis group. The spectralanalysis were used to calculate the difference of CT spectral imaging parameters, suchas the CT values at different energy level (40～140keV), spectral curves, Effective-Z,fat(calcium) concentration, iodine(water) concentration between two groups. Thedifference of these spectral characteristic parameters were evaluated statistically byindependent-samples t Test.Results The difference of CT value on different monochromatic imaging betweentwo groups was found more obvious in lower keV and the difference of CT value oftwo groups was the largest on40keV images, the mean value of metastasis[(77.7±6.6)HU] was significantly higher than that of adenoma[(16.1±22.1) HU](t＝11.372，P＜0.01). The energy spectral curves of adrenal cortical adenoma included sloopascending type(n＝6) and slow descending type(n＝13), while fast descending typecurves were shown in small metastasis from lung adenocarcinoma(n＝12). TheEffective-Z, fat(calcium)concentration， calcium(fat)concentration， water(iodine)concentration，iodine(water) concentration in metastasis were significantly higher thanthose adenomas. Conclusions There are great differences between adrenal cortical adenoma and smallmetastasis from lung adenocarcinoma in spectral curve and spectral imagingparameters. Gemstone spectral CT imaging provides a new multiparameter method todifferentiate adrenal mass.