PurposePrior studies have suggested that 18F-FDG PET/CT can help characterize adrenal lesions and differentiate adrenal metastases from benign lesions. The aim of this study was to assess the value of 18F-FDG PET/CT for the differentiation of malignant from benign adrenal lesions.MethodsThis retrospective study included 85 patients (47 men and 38 women, age 63.8 ± 10.8 years) who had undergone 18F-FDG PET/CT (60 min after injection 300 – 370 MBq 18F-FDG; Biograph 64 scanner) for evaluation of 102 nonsecreting adrenal masses. For semiquantitative analysis, the maximum standardized uptake value (SUVmax), adrenal to liver (T/L) SUVmax ratio, mean CT attenuation value and tumour diameter were measured in all lesions and compared with the pathological findings.ResultsMalignant adrenal tumours (68 % of evaluated tumours) had a significantly higher mean SUVmax (13.0 ± 7.1 vs. 3.7 ± 3.0), a higher T/L SUVmax ratio (4.2 ± 2.6 vs. 1.0 ± 0.9), a higher CT attenuation value (31.9 ± 16. 7 HU vs. 0.2 ± 25.8 HU) and a greater diameter (43.6 ± 23.7 mm vs. 25.6 ± 13.3 mm) than benign lesions. The false-positive findings were tuberculosis and benign phaeochromocytoma. Based on ROC analysis, a T/L SUVmax ratio >1.53, an adrenal SUVmax >5.2, an attenuation value >24 HU and a tumour diameter >30 mm were chosen as the optimal cut-off values for differentiating malignant from benign tumours. The areas under the ROC curves for the selected cut-off values were 0.96, 0.96, 0.88 and 0.77, respectively. A multivariate logistic regression model revealed that the T/L SUVmax ratio was an independent prognostic factor for malignancy (p < 0.001); a CT attenuation value of >25 HU and a tumour diameter >30 mm had no additional individual importance in the diagnosis of malignancy.ConclusionUsing a T/L SUVmax ratio >1.53 and an adrenal SUVmax >5.2 in 18F-FDG PET/CT led to high diagnostic sensitivity, specificity and negative predictive value for characterizing adrenal tumours. The diagnostic accuracies of the two parameters were comparable, but T/L SUVmax ratio was an independent predictor of malignancy.

Radioguided surgery using 68-gallium labelled somatostatin analogues is a promising method for detection of small, intra-abdominal, neuroendocrine neoplasm (NEN). However, due to high background activity (physiological uptake in e.g. spleen, adrenal glands and kidneys) tumours of the tail and body of pancreas might be impossible to detect with hand-held gamma probe. Therefore a new concept of intraoperative PET/CT scan of the resected tissue can be helpful in determining whether the tumour has been excised within the margins of healthy tissue. A 71-year-old woman with primary, non-metastatic NEN of the tail of pancreas is described. The tumour was diagnosed using MRI and PET/CT scan. Before operation patient was administered intravenously 80 MBq of ⁶⁸Ga-DOTATATE. The surgery procedure was performed 60-180 minutes post injection. During the procedure pancreas was visualized, but the tumour could not be localized neither with palpation nor gamma probe. The tail of the pancreas was resected en bloc with spleen and adjacent lymph nodes. PET/CT scan of the tissue specimen was performed immediately followed by pathological examination. PET/CT scan of the resected tissue showed moderate activity in the tail of pancreas, and a small focus of high activity in the tail. Area of high SSTR expression in the tail corresponded with preoperative findings in MRI and whole-body PET/CT. Histopathological examination of the specimen confirmed the presence of neuroendocrine tumour grade 1. Immediate PET/CT scan of the surgical specimen can bring new quality to intraoperative assessment of completeness of resection of neuroendocrine tumours.

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A case of 25- years-old female with NET deriving from Meckel's diverticulum is described. The patient had one year history of dermatological skin problems. Ultrasound examination of abdomen performed because of arterial hypertension, revealed multiple hepatic lesions, which was confirmed in contrast enhanced CT. The typical contrast enhanced metastatic lesions in CT and elevated levels of chromogranin A suggested NET of unknown origin. SRS with 99mTc-HYNICTOC was perform for primary tumor localization, and revealed liver and paraaortic lymph nodes metastases, but no sign of primary tumor location. As a next step for primary tumor localization 68Ga-DOTATATE PET/CT was done, which revealed focus of increased uptake in small intestine considered to be the primary tumor site. The imaging and clinical history of patient was discussed on ENETS Tumor Board. Due to location of primary tumor in the small intestine with no anatomical changes in CT, laparotomy guided with gamma probe after 68Ga-DOTATATE injection was performed. During surgery procedure, the primary tumor was hardly palpable in the tip of Meckel's diverticulum, confirmed by gamma probe. After surgery, tandem peptide receptor radionuclide therapy (PRRT) was started. Patient received 4 doses of 90Y/177Lu-DOTATATE with total activity of 360 mCi (13.32 GBq). The three months follow up 68Ga-DOTATATE PET/CT had shown stable disease of patient. The presented case showed importance role of multidisciplinary team cooperation in patient management. Use of RGS is essential in cases like presented, when the tumor cannot be localized only by surgical palpation.