Gadolinium Contrast Medium (MRI Contrast agents)
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An octreotide scan is a form of somatostatin receptor imaging used to detect neuroendocrine tumours. These tumours, which arise from neuroendocrine hormone secreting cells, are characterised by an overexpression of somatostatin receptors.
The scan uses an isotope of indium, Indium-111, which is bound to pentetreotide to form 111In-pentetreotide, a radiopharmaceutical with a somatostatin analogue that binds to somatostatin receptors. The radiopharmaceutical is actively taken up by the overexpressed somatostatin receptors on neuroendocrine tumours (predominantly type 2 and 5).
Identifying a primary neuroendocrine tumour in the appropriate clinical setting, preoperative staging, restaging and assessment of treatment response.
Examples of tumours that have high overexpression of somatostatin receptors include, but are not limited to:
This study may not be suitable for pregnant women due to the low radiation risk to the both developing foetus and the mother. The benefit versus risk should be discussed with the nuclear medicine specialist.
Given that there is a small amount of radioactivity released for a while after the test, women who are breast-feeding may need to make special preparations after the test to stop breast-feeding for a short time. Similarly, close contact with young children should be avoided for a short time (see below).
The doctor should contact the hospital or radiology practice and check the scanner bed limits if their patient is morbidly obese.
There are no adverse affects from an octreotide scan. The amount of radiation exposure is quite safe and should not result in any short- or long-term hazardous effects.
111In-pentetreotide scan is eliminated from the body predominantly via the kidneys. Patients should be well hydrated before and after the scan. The biological half-life is approximately 6 hours.
If the scan was deemed medically necessary in pregnant and/or breast-feeding patients, hydration is crucial. The patient can express breast milk before the scan to use on the days of the scan. After the scan, milk should be discarded for the next 48 hours. The patient should minimise close contact with the baby and children under the age of 5 years for the next 24 hours. Patients should discuss this with their referring doctor or the nuclear medicine practice where they will have the test. See Nuclear Medicine for further information about the precautions to take with nuclear medicine studies for breast-feeding patients and those in close contact with children.
Other functional imaging includes 68Ga DOTA-Octreotate PET-CT scan and 123I/124I MIBG scan. PET imaging can be particularly useful in aggressive, rapidly-growing tumours that may not be seen on octreotide scanning.
CT and MRI can better delineate the anatomical relationships of any identifiable tumour.
Page last modified on 31/8/2018.
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