The First Experience of Using Magnetic Resonance Spectroscopy in the Differential Diagnosis of Adrenal Tumors

Abstract

Purpose: To improve the differential diagnosis of various adrenal tumors using a two-dimensional (2D) multivoxel 1 H-magnetic resonance spectroscopy (MRS) protocol. Material and methods: The study included 32 patients who underwent examination and treatment from February 2021 to February 2022, who, according to various radiation methods of research, had tumor formations in the adrenal glands. In total, 36 neoplasms were found in the adrenal glands, of which: 10 adenomas in 10 patients (27.8 %), 5 adrenocortical carcinomas in 5 patients (13.9 %), 5 pheochromocytomas in 5 patients (13.9 %), 6 metastatic nodes in 5 patients (16.7 %, 1 patient had 2 metastatic nodes in both adrenal glands), 4 affected adrenal glands with lymphoproliferative diseases with bilateral adrenal involvement in 2 patients (11.1 %), 2 myelolipomas in 2 patients (5.6 %). We evaluated the age and sex of patients, the location of the tumor and its size, as well as the amplitude of metabolites obtained by multivoxel MRS: choline (Cho), creatine (Cr), glutamine/glutamate (Glx), N-acetylaspartate (NAA), lactate (Lac) and their Cho/Cr ratios, Lac/Cr, Cho/NAA, Glx/Cr. Results: Malignant formations of the adrenal glands were larger in size compared to benign ones (p = 0.0265). The size of benign formations ranged from 1.4 cm to 8.5 cm (median 3.2 cm), malignant from 2 to 12 cm (median 5.8 cm). Statistically significant differences in the groups of malignant and benign adrenal neoplasms were determined by the creatine content detected by MRS (p = 0.0323). Creatine content in benign formations was higher and ranged from 0.415 units to 52 units. (median 4.013 units), in malignant — from 0.221 units to 16.6 units (median 2 units). With a threshold value of creatine content less than 3.42 units, the sensitivity of the trait in the differential diagnosis of malignant neoplasms was 73.3 %, specificity 66.7 %, accuracy 79.3 %. The area under the ROC curve (AUC) was 0.703, which corresponds to the good quality of the predictive model on the scale of expert assessments. There was a moderate inverse correlation between the size of the adrenal gland formations and the creatine content in it according to MRS (correlation coefficient –0.432). If the size of adrenal neoplasm increase, the creatine content in it is proportionally decrease. There were no statistically significant differences in the content of other metabolites and their ratios between malignant and benign adrenal neoplasms, also there were no statistically significant differences in the size of neoplasms, gender and age of patients.