Carcinoid syndrome other imaging findings: Difference between revisions
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*Angiography | *Angiography | ||
===Somatostatin Receptor Scintigraphy=== | ===Somatostatin Receptor Scintigraphy=== | ||
There are five different somatostatin receptor (SSTR) subtypes; more than 70% of NETs of both the GI tract and pancreas express multiple subtypes, with a predominance of receptor subtype 2 [sst(2)] and receptor subtype 5 [sst(5)].[50,51] The synthetic radiolabeled SSTR analog 111In-DTP-d-Phe10-{octreotide} affords an important method, somatostatin receptor scintigraphy (SRS), to localize carcinoid tumors, especially sst(2)-positive and sst(5)-positive tumors; imaging is accomplished in one session, and small primary tumors and metastases are diagnosed more readily than with conventional imaging or imaging techniques requiring multiple sessions. | There are five different somatostatin receptor (SSTR) subtypes; more than 70% of NETs of both the GI tract and pancreas express multiple subtypes, with a predominance of receptor subtype 2 [sst(2)] and receptor subtype 5 [sst(5)].[50,51] The synthetic radiolabeled SSTR analog 111In-DTP-d-Phe10-{octreotide} affords an important method, somatostatin receptor scintigraphy (SRS), to localize carcinoid tumors, especially sst(2)-positive and sst(5)-positive tumors; imaging is accomplished in one session, and small primary tumors and metastases are diagnosed more readily than with conventional imaging or imaging techniques requiring multiple sessions. Overall sensitivity of the octreotide scan is reported to be as high as 90%; however, failed detection may result from various technical issues, small tumor size, or inadequate expression of SSTRs. | ||
===Endoscopic Ultrasonography (EUS)=== | ===Endoscopic Ultrasonography (EUS)=== | ||
Revision as of 14:17, 23 September 2015
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]
Overview
Other Imaging Findings
Other imaging modalities for GI carcinoids include the use of:
- Somatostatin scintigraphy with 111Indium-octreotide
- Bone scintigraphy with 99mTc-methylene diphosphonate (99mTcMDP)
- 123 I-metaiodobenzylguanidine (MIBG) scintigraphy
- Capsule endoscopy (CE)
- Enteroscopy
- Angiography
Somatostatin Receptor Scintigraphy
There are five different somatostatin receptor (SSTR) subtypes; more than 70% of NETs of both the GI tract and pancreas express multiple subtypes, with a predominance of receptor subtype 2 [sst(2)] and receptor subtype 5 [sst(5)].[50,51] The synthetic radiolabeled SSTR analog 111In-DTP-d-Phe10-{octreotide} affords an important method, somatostatin receptor scintigraphy (SRS), to localize carcinoid tumors, especially sst(2)-positive and sst(5)-positive tumors; imaging is accomplished in one session, and small primary tumors and metastases are diagnosed more readily than with conventional imaging or imaging techniques requiring multiple sessions. Overall sensitivity of the octreotide scan is reported to be as high as 90%; however, failed detection may result from various technical issues, small tumor size, or inadequate expression of SSTRs.
Endoscopic Ultrasonography (EUS)
Endoscopic ultrasonography (EUS) may be a sensitive method for the detection of gastric and duodenal carcinoids and may be superior to conventional ultrasound, particularly in the detection of small tumors (2 mm–3 mm) that are localized in the bowel lumen. In one study, the EUS was reported to have an accuracy of 90% for the localization and staging of colorectal carcinoids.
Positron Emission Tomography (PET)
A promising approach for positron emission tomography (PET) as an imaging modality to visualize GI carcinoids appears to be the use of the radioactive-labeled serotonin precursor 11C-5-hydroxytryptophan (11C-5-HTP). With 11C-5-HTP, tumor detection rates have been reported to be as high as 100%, and some investigators have concluded that 11C-5-HTP PET should be used as a universal detection method for detecting NETs.
Angiography
MRI angiography has replaced angiography to a large extent. However, selective and supraselective angiography may be useful to:
- Demonstrate the degree of tumor vascularity
- Identify the sources of vascular supply
- Delineate the relationship of the tumor to adjacent major vascular structures
- Provide information regarding vascular invasion
Localization
Tumour localization may be extremely difficult. Barium swallow and follow-up examination of the intestine may occasionally show the tumour. Capsule video endoscopy has recently been used to localized the tumour. Often laparotomy is the definitive way to localize the tumour.