CXR is the first-line imaging investigation in most patients. CXRs are abnormal in 90% of patients with bronchial carcinoid.
CT is useful for detecting lesions not visible on CXR, for assessing endobronchial lesions, and also for characterizing and staging of the tumors.
Because the tumors are slow growing, and ancillary findings due to bronchial obstruction may also be seen. These findings include atelectasis; bronchiectasis; pneumonitis; mucous impaction (bronchocele) of a distal bronchus; and, occasionally, distal abscess formation.
Calcification is common and is seen in 30%. The incidence of calcification is significantly higher in centrally placed tumors.
Lesions are also highly vascular and usually demonstrate marked homogeneous enhancement on CT scans obtained after the intravenous administration of contrast material. However, some carcinoid tumors (particularly atypical carcinoids) may show heterogeneous or no enhancement.
Bronchial carcinoids metastasize to the mediastinal lymph nodes in 25% of cases.
OCTREOSCAN:Known primary and metastatic tumor sites can be imaged with somatostatin analogue scintigraphy,Octreoscan. Octreoscan uses pentetreotide,a long acting conjugate of octreotide (a somatostatin analog that predominately binds to the sst2 and sst5 somatostatin receptors). This is conjugated to Indium 111 ( Half life 67 hrs, Photopeaks 172 and 245 keV). This agent binds to somatostatin receptors which are found in many tumors, including carcinoid tumors. It is used to further detection of previously undiagnosed and unsuspected deposits and facilitates the selection of patients with carcinoids that are likely to respond favorably to octreotide treatment.
The sensitivity for carcinoid tumors is 86-95%B
The sensitivity for carcinoid tumors is 86-95%B
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