| Octreotide scan | |
| Synonyms: | ocreoscan |
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]
| Drug Name: | Indium In-111 pentetreotide |
| Width: | 250px |
| Tradename: | Octreoscan |
| Dailymedid: | Indium_in-111_pentetreotide |
| Routes Of Administration: | Intravenous |
| Atc Prefix: | V09 |
| Atc Suffix: | IB01 |
| Legal Us: | Rx-only |
| Legal Us Comment: | [10] |
| Cas Number: | 139096-04-1 |
| Pubchem: | 131704321 |
| Drugbank: | DB11835 |
| Unii: | M312JJ6Z32 |
| Synonyms: | MP-1727 |
| Smiles: | [111In+3].CC(O)C(CO)N=C(O)C1CSSCC(N=C(O)C(CC2=CC=CC=C2)N=C([O-])CN(CCN(CCC(C(O)=O)C(O)=O)CC([O-])=O)CC([O-])=O)C(O)=NC(CC2=CC=CC=C2)C(O)=NC(CC2=CNC3=CC=CC=C23)C(O)=NC(CCCCN)C([O-])=NC(C(C)O)C(O)=N1 |
| Stdinchi: | 1S/C62H84N12O19S2.In/c1-35(76)47(32-75)69-59(88)49-34-95-94-33-48(70-55(84)44(25-37-13-5-3-6-14-37)65-50(78)29-74(31-52(81)82)24-23-73(30-51(79)80)22-20-41(61(90)91)62(92)93)58(87)67-45(26-38-15-7-4-8-16-38)56(85)68-46(27-39-28-64-42-18-10-9-17-40(39)42)57(86)66-43(19-11-12-21-63)54(83)72-53(36(2)77)60(89)71-49;/h3-10,13-18,28,35-36,41,43-49,53,64,75-77H,11-12,19-27,29-34,63H2,1-2H3,(H,65,78)(H,66,86)(H,67,87)(H,68,85)(H,69,88)(H,70,84)(H,71,89)(H,72,83)(H,79,80)(H,81,82)(H,90,91)(H,92,93);/q;+3/p-4/i;1-4 |
| Stdinchikey: | ZKZPXKKVDJOAIS-JWFOFJTQSA-J |
The indium-111 pentetreotide radiopharmaceutical is prepared from a kit in a radiopharmacy. Pentetreotide is a DTPA conjugate of octreotide.[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.[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]