[Somatostatin receptor scintigraphy. When would a SPECT study be performed?]

Area of Science:

• Nuclear Medicine
• Oncology
• Radiology

Background:

• Somatostatin receptor scintigraphy is crucial for carcinoid tumor (CaT) and pancreatic neuroendocrine tumor (PNET) management.
• The diagnostic contribution of SPECT imaging for these tumors remains underexplored.

Purpose of the Study:

• To evaluate if SPECT enhances the sensitivity of planar imaging in diagnosing CaT and PNET.
• To determine optimal circumstances for utilizing SPECT in tumor diagnosis and staging.

Main Methods:

• 49 patients with suspected or known CaT/PNET underwent both planar and SPECT 111In-DTPAOC imaging.
• Patients were categorized by clinical indication: indolent symptoms, known tumors, or post-surgical follow-up.
• SPECT findings were correlated with surgical, biochemical, clinical, and CT data.

Main Results:

• SPECT detected more primary lesions (18) than planar imaging (16), including two missed by planar scans.
• SPECT sensitivity for metastases was higher (90.4%) than planar imaging (76.1%).
• SPECT provided added value in 21.8% of studies with abnormal planar images and identified lesions missed by planar imaging in 15.6% of cases.

Conclusions:

• SPECT imaging is recommended for patients with functional syndromes or known CaT/PNET and normal planar images.
• Utilize SPECT to confirm primary tumors when planar images are equivocal, assess metastases, and precisely locate lesions.
• SPECT enhances the detection of low receptor density lesions and uncertain findings on planar scans.