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What is Neuroendocrinal tumors (NET) can be best detected by : and explain in detail?
Ans. is 'd' i.e. Radio nucleotide scan * "Somatostatin receptor scintigraphy (SRS type of radio nucleotide scan) is now the imaging modality of choice for localizing both primary and metastatic NET tumor." - HarrisonNeuroendocrine for NET) tumors refers to two types of tumor:Carcinoids & Pancreatic endocrine tumors (PETs) e.g. Insulinoma Gastrinoma VIPomas GRFomas Somatostatinoma etc.SRS is an investigating modality for localizing the NETs as are CT, MRI, Endoscopic U/SNote that it not a diagnostic investigation.Diagnosis of NETs, is made by detecting the peptides or amines (or their metabolites) secreted by the tumors, in urine or serum.For e.g. -In carcinoid tumor - Serotonin*5-HIAA (Best)*5-HTP*5-//T*Glucagonoma - Elevated plasma glucagon level*Somatostatinoma - Elevated plasma level of somatostatin*Investigating modalities for localization of NET tumors:CT ScanMRITransabdominal U/SSelective angiographySRSEndoscopic U/SSRS is the imaging modality of choice for localizing both primary and metastatic NET tumors.Insulinomas are an exception to this :They have low densities of SST receptors, therefore SRS is not effective modality for them.Best modality for localizing insulinomas is Endoscopic U/S.Also note that though SRS is the imaging modality of choice for localizing the NETs, it does not provide reliable information on tumor size (CT & MRI are much better).