Octreotide scan | |
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Synonyms | ocreoscan |
ICD-9-CM | 92.18 |
OPS-301 code | 3-70c |
An octreotide scan is a type of SPECT scintigraphy used to find carcinoid, pancreatic neuroendocrine tumors, and to localize sarcoidosis. It is also called somatostatin receptor scintigraphy (SRS). Octreotide, a drug similar to somatostatin, is radiolabeled with indium-111, [1] and is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to tumor cells that have receptors for somatostatin (i.e. gastrinoma, glucagonoma, etc.). A gamma camera detects the radioactive octreotide, and makes pictures showing where the tumor cells are in the body, typically by a SPECT technique. A technetium-99m based radiopharmaceutical kit is also available. [2] [3]
Octreotide scanning is reported to have a sensitivity between 75% and 100% for detecting pancreatic neuroendocrine tumors. [4]
Instead of gamma-emitting 111In, certain octreotide derivatives such as edotreotide (DOTATOC) or DOTATATE are able to be linked by chelation to positron-emitting isotopes such as gallium-68 and copper-64 which in turn can be evaluated with more precise (compared with SPECT) scanning techniques such as PET-CT. Thus, the octreotide scan is now being replaced in most centers with gallium-68 DOTATATE and copper-64 DOTATATE scans. Somatostatin receptor imaging can now be performed with positron emission tomography (PET) which offers higher resolution and more rapid imaging. [5]
An octreotide scan may be used to locate suspected primary neuroendocrine tumours (NET) or for follow-up or staging after treatment. [6] [7] [8]
Where indicated, octreotide scanning for NET tumors is being increasingly replaced by gallium-68 DOTA and copper-64 DOTATATE scans. [9]
Clinical data | |
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Trade names | Octreoscan |
Other names | MP-1727 |
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Routes of administration | Intravenous |
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The indium-111 pentetreotide radiopharmaceutical is prepared from a kit in a radiopharmacy. Pentetreotide is a DTPA conjugate of octreotide. [6] [11]
Approximately 200 megabecquerels (MBq) of indium-111 is injected intravenously. Imaging takes place 24 hours after injection, but may also be carried out at 4 and 48 hours. [7] [12]
The 99mTc product is supplied as a kit with two vials, one containing the chelating agent ethylenediaminediacetic acid (EDDA) and the other the HYNIC-Tyr3-octreotide chelator and somatostatin analog. [13] Approximately 400-700 MBq may be administered, with imaging at 2, 4, and occasionally 24 hours post administration. [14] 99mTc based octreotide imaging shows slightly higher sensitivity than 111In. [2] [15]
Single-photon emission computed tomography is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera, but is able to provide true 3D information. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required.
Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging, in a sense, is "radiology done inside out" because it records radiation emitted from within the body rather than radiation that is transmitted through the body from external sources like X-ray generators. In addition, nuclear medicine scans differ from radiology, as the emphasis is not on imaging anatomy, but on the function. For such reason, it is called a physiological imaging modality. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans are the two most common imaging modalities in nuclear medicine.
Scintigraphy, also known as a gamma scan, is a diagnostic test in nuclear medicine, where radioisotopes attached to drugs that travel to a specific organ or tissue (radiopharmaceuticals) are taken internally and the emitted gamma radiation is captured by gamma cameras, which are external detectors that form two-dimensional images in a process similar to the capture of x-ray images. In contrast, SPECT and positron emission tomography (PET) form 3-dimensional images and are therefore classified as separate techniques from scintigraphy, although they also use gamma cameras to detect internal radiation. Scintigraphy is unlike a diagnostic X-ray where external radiation is passed through the body to form an image.
Natural gallium (31Ga) consists of a mixture of two stable isotopes: gallium-69 and gallium-71. Twenty-nine radioisotopes are known, all synthetic, with atomic masses ranging from 56 to 86; along with three nuclear isomers, 64mGa, 72mGa and 74mGa. Most of the isotopes with atomic mass numbers below 69 decay to isotopes of zinc, while most of the isotopes with masses above 71 decay to isotopes of germanium. Among them, the most commercially important radioisotopes are gallium-67 and gallium-68.
A bone scan or bone scintigraphy is a nuclear medicine imaging technique of the bone. It can help diagnose a number of bone conditions, including cancer of the bone or metastasis, location of bone inflammation and fractures, and bone infection (osteomyelitis).
A gallium scan is a type of nuclear medicine test that uses either a gallium-67 (67Ga) or gallium-68 (68Ga) radiopharmaceutical to obtain images of a specific type of tissue, or disease state of tissue. Gallium salts like gallium citrate and gallium nitrate may be used. The form of salt is not important, since it is the freely dissolved gallium ion Ga3+ which is active. Both 67Ga and 68Ga salts have similar uptake mechanisms. Gallium can also be used in other forms, for example 68Ga-PSMA is used for cancer imaging. The gamma emission of gallium-67 is imaged by a gamma camera, while the positron emission of gallium-68 is imaged by positron emission tomography (PET).
Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lung, and the rest of the body.
ATC code V09Diagnostic radiopharmaceuticals is a therapeutic subgroup of the Anatomical Therapeutic Chemical Classification System, a system of alphanumeric codes developed by the World Health Organization (WHO) for the classification of drugs and other medical products. Subgroup V09 is part of the anatomical group V Various.
Immunoscintigraphy is a nuclear medicine procedure used to find cancer cells in the body by injecting a radioactively labeled antibody, which binds predominantly to cancer cells and then scanning for concentrations of radioactive emissions.
Indium-111 (111In) is a radioactive isotope of indium (In). It decays by electron capture to stable cadmium-111 with a half-life of 2.8 days. Indium-111 chloride (111InCl) solution is produced by proton irradiation of a cadmium target in a cyclotron, as recommended by International Atomic Energy Agency (IAEA). The former method is more commonly used as it results in a high level of radionuclide purity.
DOTA-TATE is an eight amino acid long peptide, with a covalently bonded DOTA bifunctional chelator.
Edotreotide (USAN, also known as (DOTA0-Phe1-Tyr3) octreotide, DOTA-TOC, DOTATOC) is a substance which, when bound to various radionuclides, is used in the treatment and diagnosis of certain types of cancer. When used therapeutically it is an example of peptide receptor radionuclide therapy.
Advanced Accelerator Applications is a France-based pharmaceutical group, specialized in the field of nuclear medicine. The group operates in all three segments of nuclear medicine to diagnose and treat serious conditions in the fields of oncology, neurology, cardiology, infectious and inflammatory diseases.
The Krenning score is used to grade the uptake intensity of neuroendocrine tumors on somatostatin receptor imaging such as octreotide scan. Typically, peptide receptor radionuclide therapy (PRRT) is considered when the Krenning score is greater than 2.
Siroos Mirzaei is an Iranian specialist in Nuclear Medicine. He is Head of the Department of Nuclear Medicine of the Wilhelminen Hospital in Vienna. Mirzaei is well known for his scientific work on torture diagnostics with molecular imaging methods.
A PSMA scan is a nuclear medicine imaging technique used in the diagnosis and staging of prostate cancer. It is carried out by injection of a radiopharmaceutical with a positron or gamma emitting radionuclide and a prostate-specific membrane antigen (PSMA) targeting ligand. After injection, imaging of positron emitters such as gallium-68 (68Ga), copper-64 (64Cu), and fluorine-18 (18F) is carried out with a positron emission tomography (PET) scanner. For gamma emitters such as technetium-99m (99mTc) and indium-111 (111In) single-photon emission computed tomography (SPECT) imaging is performed with a gamma camera.
Peptide receptor radionuclide therapy (PRRT) is a type of radionuclide therapy, using a radiopharmaceutical that targets peptide receptors to deliver localised treatment, typically for neuroendocrine tumours (NETs).
Lutetium (177Lu) oxodotreotide (INN) or 177Lu DOTA-TATE, trade name Lutathera, is a chelated complex of a radioisotope of the element lutetium with DOTA-TATE, used in peptide receptor radionuclide therapy (PRRT). Specifically, it is used in the treatment of cancers which express somatostatin receptors.
Somatostatin receptor antagonists are a class of chemical compounds that work by imitating the structure of the neuropeptide somatostatin. The somatostatin receptors are G protein-coupled receptors. Somatostatin receptor subtypes in humans are sstr1, 2A, 2 B, 3, 4 and 5. While normally expressed in the gastrointestinal (GI) tract, pancreas, hypothalamus, and central nervous system (CNS), they are expressed in different types of tumours. The predominant subtype in cancer cells is the ssrt2 subtype, which is expressed in neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell carcinomas, paragangliomas, small cell lung carcinomas and hepatocellular carcinomas.
Somatostatin receptor antagonists are a class of chemical compounds that work by imitating the structure of the neuropeptide somatostatin, which is an endogenous hormone found in the human body. The somatostatin receptors are G protein-coupled receptors. Somatostatin receptor subtypes in humans include sstr1, 2A, 2 B, 3, 4, and 5. While normally expressed in the gastrointestinal (GI) tract, pancreas, hypothalamus, and central nervous system (CNS), they are expressed in different types of tumours. The predominant subtype in cancer cells is the ssrt2 subtype, which is expressed in neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell carcinomas, paragangliomas, small cell lung carcinomas, and hepatocellular carcinomas.
This article incorporates public domain material from Dictionary of Cancer Terms. U.S. National Cancer Institute.