68 Ga-DOTATATE uptake in pineal gland, a rare physiological variant: case series
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CASE REPORT
68
Ga-DOTATATE uptake in pineal gland, a rare physiological variant: case series
Saima Riaz1 • Rizwan Syed1 • Evangelia Skoura1 • Alshaima Alshammari1 Mark Gaze2 • Rakesh Sajjan1 • Richard Halsey1 • Jamshed Bomanji1
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Received: 9 March 2015 / Accepted: 3 July 2015 Ó The Japanese Society of Nuclear Medicine 2015
Abstract 68Ga-DOTATATE PET–CT is widely used for the evaluation of neuroendocrine tumours. Knowledge of the physiological distribution of the radiotracer is of critical importance in characterizing focal areas of uptake. In this case series, we report three paediatric cases (average age 4.7 years ± 0.6 SD) with diagnosed advanced stage IV Neuroblastoma. Two had 68Ga-DOTATATE PET–CT scans and one underwent 68Ga-DOTATATE PET–MRI scan to assess for suitability of molecular therapy. Focal increased tracer uptake in the pineal gland was noted in all cases with no morphological abnormality on the corresponding CT and MRI scans. The uptake within the gland was thought to be a physiological variant rather than metastases owing to the heterogeneity of somatostatin receptors expression. The pineal gland has been reported to express somatostatin receptors. The physiological distribution of 68Ga-DOTATATE uptake in the pineal gland is not routinely seen. Furthermore, the possibility of pineal meningioma is very unlikely as pineal meningiomas are very rare and there was no convincing morphological evidence of meningiomas on CT/MRI scan. Keywords Somatostatin receptor 68Ga-DOTATATE PET–CT scan PET–MRI scan Pineal gland
Introduction 68
Ga-DOTATATE is a somatostatin analogue with high affinity for somatostatin receptor subtype 2 (SST2). 68GaDOTATATE is used for PET imaging of neuroendocrine tumours with over-expression of somatostatin receptors [1]. The recognised physiological bio-distribution of 68GaDOTATATE is to pituitary, salivary glands, thyroid, gastric lining, liver, spleen, adrenal glands, pancreas and the prostate. All these organs express SST2 receptors. Urinary and bowel activities are the excretory routes for the tracer [2]. In the head and neck region, somatostatin receptors have been reported in the cerebral cortex and subcortical structures including the limbic system and basal nuclei [3]. However, the hydrophilic 68Ga-DOTATATE does not cross the blood– brain barrier and shows no brain uptake. Occasionally small foci of increased activity are seen over the cerebral convexities or at the base of skull, which are usually indicative of meningiomas, in the absence of clinical symptoms [2]. The pineal gland is a part of the epithalamus and expresses somatostatin receptors. This small endocrine gland produces melatonin and maintains the circadian rhythm [4]. In this case series, we describe 3 patients with stage IV Neuroblastoma with unusual 68Ga-DOTATATE uptake in the pineal gland and no corresponding morphological abnormality on CT and MRI scans. Informed consent was attained prior to the PET/CT or PET/MRI imaging in all three cases.
& Saima Riaz [email protected] 1
Institute of N
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