Diagnostic performances of FDG-PET/CT and diffusion-weighted imaging indices for differentiating benign pheochromocytoma from other benign adrenal tumors

Abstract

FDG-based indices and ADC appear comparably useful for differentiating pheochromocytoma from other benign adrenal tumors.

ADC histogram analysis for adrenal tumor histogram analysis of apparent diffusion coefficient in differentiating adrenal adenoma from pheochromocytoma

“…However, Tsushima et al have reported that the ADC value of pheochromocytoma was significantly higher than that of adenomas. In contrast, Nakajo et al found that the mean ADC was significantly lower in pheochromocytoma than in lipid‐poor adenoma. Although it is difficult to speculate on the exact reasons for the variation of ADC values, the following explanation may be plausible: the choice of ROI has a considerable influence on the tumor ADC values and interobserver variability, and most of the previous researchers measured mean ADC values by placing the ROI on the solid area of a tumor, avoiding cystic or necrotic areas, which may contribute to the large variety in reported ADC results because selecting a location is subjective …”

“…We used size stability during a 6‐month or longer follow‐up to confirm adrenal adenomas. In several previous studies, this has been an accepted criterion for classifying a lesion as benign . Third, the choice of b‐value plays an important role for the ADC value, because ADC represents perfusion as well as molecular diffusion .…”

“…Among them, 64 patients were diagnosed with adrenal adenoma or pheochromocytoma, as identified through a review of clinical charts with the radiology information system, and records of the Department of Human Pathology. Adrenal adenomas were diagnosed by pathology or based on stability for at least 6 months of follow‐up CT studies . Seventeen patients with adrenal adenomas were excluded due to tumor size that was very small (<10 mm) for evaluation and may affect the ADC values on DW imaging …”

“…Through the measurement of apparent diffusion coefficient (ADC), DW MRI provides qualitative and quantitative information that is pertinent to tissue structure. However, there are limited studies on the characterization of adrenal lesions using DW MRI . In particular, the ability of ADC values in differentiating adrenal adenomas from pheochromocytomas has been controversial …”

18F-FDG PET/CT in the post-operative monitoring of patients with adrenocortical carcinoma

“…Several studies have reported the effectiveness of FDG PET or PET/CT to differentiate benign from malignant adrenal tumors (4,5,6,7,8,9,10,11) but only a few studies reported on the use of functional imaging techniques in the follow-up of adrenocortical carcinoma (ACC) (9,10,11). Thus, there is limited evidence that PET/CT may refine staging of ACC patients at initial diagnosis or during follow-up.…”