Carcinoid Tumor Case Study

Clinical History

This case describes a patient with a history of primary carcinoid tumor (neuroendocrine tumor) of the appendix. The patient underwent an appendectomy and partial liver resection one year ago and presented with carcinoid syndrome-like symptoms, which reappeared two months ago.

The patient underwent a contrast CT scan, which showed a small, solitary focal area of contrast enhancement in the posterior aspect of the right lobe of the liver, which was suspicious of tumor recurrence.

The patient was referred for 111In SPECT•CT scan to evaluate neuroendocrine tumor metastases.

Imaging Findings

The SPECT•CT study showed focal areas of increased tracer uptake in the right lobe the liver, with two solitary focal areas in segment VII, and one in segment V, at the lower end of the free border of the right lobe of the liver. The noncontrast CT, performed as part of SPECT•CT showed no corresponding abnormalities in these focal areas. Evidence of previous hepatic resection at the posterior part of segment VII was visualized on the CT scan.

A three-phase liver study was performed immediately following the SPECT•CT procedure on the Symbia T6 system, after an intravenous injection of 80 ml CT contrast at a flow rate of 2.5 ml/sec. Breathold thin slice acquisitions were acquired for the arterial and venous phases.*

The contrast CT study showed a minor focal blush of contrast enhancement in the posterior part of the right lobe in segment VII, corresponding to the region demonstrated in the previous CT scan. Coregistration of CT and SPECT data showed the focal area of contrast enhancement in CT to exactly correspond to the main focal area of increased uptake of 111In octreotide. This demonstrated that site as the site for metastatic carcinoid tumor. The other focal areas of increased tracer uptake in segment VII and segment V did not show significant CT contrast enhancement.

The tracer uptake seen in the gall bladder region and in the colon was physiological. Hepatic arteries, portal and hepatic veins and inferior vena cava that were seen on contrast CT appeared normal.

Surgery

Surgical resection was planned following the illustration of multiple metastatic foci in segment VII and single foci in segment V. Pre surgical assessment showed the lesion to be resectable.

Treatment / Follow-up Report

The patient was referred for a surgical resection of segment VII and part of segment V of the liver.

Discussion

Although previous contrast CT suggested a suspicious lesion in the posterior part of right lobe, the SPECT•CT study using 111In octreotide clearly delineated multiple metastases in segment VII and V of the liver. Although the largest metastatic foci were visualized both in SPECT as well as in three-phase contrast CT, several smaller metastatic foci visualized in the octreotide SPECT scan did appear abnormal in the contrast CT study. SPECT•CT, thus, clearly provided additional benefit to the evaluation by illustrating the true extent of metastatic disease and helped in the planning of the surgical resection.

Carcinoids are the most common neuroendocrine tumors, primarily arising from the gut but may also arise in liver, pancreas and bronchus.

Depending on the size and location, carcinoid tumors can produce typical symptoms referred to as carcinoid syndrome. Carcinoid tumors of the ileum and jejunum, especially when larger than 1 cm, are more prone to produce this syndrome. Carcinoid tumors arising from the second portion of the duodenum, the jejunum, the ileum, and the right colon account for 60-80% of all carcinoid tumors in adults. The appendix and distal ileum are the most common sites.

Carcinoid tumors are neuroendocrine tumors which possess somatostatin receptors and are visualized with radiolabelled somatostatin analogs like 111In diethylenetriaminepentaacetic acid (DTPA) octreotide. SPECT with 111In octreotide has been shown to be more sensitive when compared with CT or MRI. Studies have demonstrated octreotide SPECT to pick up carcinoid tumor metastasis when contrast CT or MRI was normal (1).

One study comparing somatostatin receptor scintigrapy (SRS) to CT in 31 patients of gastropancreatic carcinoid tumors showed higher sensitivity of SRS for intestinal and pancreatic lesions compared to CT. However, the detection rate for liver lesions was lower with SRS than CT (2). This could be related to the quality of octreotide scanning, including the amount of peptide injected and the scanning protocol. In this study, the scan performed 24 hours post-injection yielded the best SPECT image quality and demonstrated the maximum number of lesions. However, some metastatic carcinoid tumors may not express somatostatin receptors nor express receptors that bind to octreotide.

This case demonstrates the power of combined high quality spiral CT and SPECT imaging for improved diagnostic clarity. The contrast three-phase liver study, coregistered with attenuation corrected SPECT clearly demonstrates that the metastasis enhanced with CT contrast were somatostatin avid. However, additional octreotide positive but contrast CT negative metastasis is also demonstrated, thereby changing the treatment decision from radiofrequency ablation to surgical resection.

Data courtesy of Dr. Shahid Mahmood of Gleneagles Hospital, Singapore

References:

1. 111In -pentetreotide and 123I-MIBG for detection and resection of lymph node metastases of a carcinoid not visualized by CT, MRI or FDG-PET - Yuksel et al. - Ann Nucl Med. 2005 Oct;19(7):611-5.
2. Scintigraphic detection of carcinoid tumors with a cost effectiveness analysis - Dimitroulupoulos et al. - World J Gastroenterol. 2004 Dec 15;10(24):3628-33.
*Any of the protocols presented herein are for informational purposes and are not meant to substitute for any clinicians' judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education, learning and experience.