Characterizing an ectopic secreting carcinoid with indium-111-DTPA-D-Phe-pentetreotide.
This report describes a technique that increases the specificity of 111In-pentetreotide as evaluated in a patient with ectopic Cushing syndrome.


METHODS
Two separate SPECT studies were performed with different pharmacologic protocols, both including treatment with cold octreotide. The imaging protocol provides acquisitions at 4 and 24 hr after injection. The quantitative approach was based on the ROI activity (manually designed) of an area of pathological lung uptake (ROI-T) versus background (ROI-NT). Histological, histochemical and specific mRNA measurements confirmed the presence of an SSR2 receptor carcinoid in the lung.


RESULTS
The time course of ROI-T/ROI-NT is a linear increase between 4 and 24 hr. Washout with cold octreotide diminished the ROI-T activity content and the saturation protocol increased ROI-T/ROI-NT, confirming the specific nature of the uptake.


CONCLUSIONS
Displacement and saturation protocols in 111In-pentetreotide imaging demonstrated the specificity of tumor binding.
Briganti
V
V
Department of Nuclear Medicine, Azienda Hospital Careggi-Florence, Italy.
Mannelli
M
M
La Cava
G
G
Peri
A
A
Meldolesi
U
U
Masi
R
R
Pupi
A
A
D000182:ACTH Syndrome, Ectopic / Q000000981:diagnostic imaging*; D000328:Adult; D002276:Carcinoid Tumor / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015282:Octreotide / Q000031:analogs & derivatives*; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin / Q000032:analysis; D012680:Sensitivity and Specificity; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; C071632:SDZ 215-811; D004369:Pentetic Acid; C093733:somatostatin receptor 2; D015282:Octreotide