Somatostatin receptor scintigraphy: its sensitivity compared with that of other imaging methods in detecting primary and metastatic gastrinomas. A prospective study.

OBJECTIVE

To compare the sensitivity of somatostatin receptor scintigraphy done using [111In-DTPA-DPhe1]octreotide with that of other imaging methods in the localization of gastrinomas in patients with the Zollinger-Ellison syndrome.

DESIGN

Prospective study.

SETTING

Referral-based clinical research center.

PATIENTS

80 consecutive patients with the Zollinger-Ellison syndrome.

INTERVENTIONS

Conventional tumor localization studies (ultrasonography, computed tomography [CT], magnetic resonance imaging [MRI], selective angiography, and bone scanning) and somatostatin receptor scintigraphy done using [111In-DTPA-DPhe1]octreotide with single-photon emission CT imaging at 4 and 24 hours. Patients with possible liver metastases had biopsies done for confirmation, and 15 patients had exploratory laparotomies done to assess primary tumor localization.

RESULTS

Extrahepatic gastrinomas or liver metastases were identified by ultrasonography in 19% of patients, by CT in 38% of patients, by MRI in 45% of patients, by angiography in 40% of patients, and by somatostatin receptor scintigraphy in 70% of patients. Somatostatin receptor scintigraphy was as sensitive as the other tests combined (59%), and when the results of all other tests were added to the somatostatin receptor scintigraphy results, tumors were localized in 75% of patients. Among patients with a possible primary tumor, the results of ultrasonography were positive in 9%, the results of CT were positive in 31%, the results of MRI were positive in 30%, the results of angiography were positive in 28%, and the results of somatostatin receptor scintigraphy were positive in 58%. Somatostatin receptor scintigraphy was as sensitive as all of the other imaging studies combined; when the results of scintigraphy were added to the results of the other studies, possible primary tumors were identified in 68% of patients. In 24 patients who had histologically proven metastatic liver disease, sensitivities for the detection of any metastatic liver lesions were 46% for ultrasonography, 42% for CT, 71% for MRI, 62% for angiography, and 92% for somatostatin receptor scintigraphy. Somatostatin receptor scintigraphy was significantly better than all of the conventional imaging methods in the identification of gastrinomas later found at surgery (P = 0.004), but it still missed 20% of gastrinomas.

CONCLUSIONS

Somatostatin receptor scintigraphy is the single most sensitive method for imaging either primary or metastatic liver lesions in patients with the Zollinger-Ellison syndrome. Because of its sensitivity, simplicity, and cost-effectiveness, it should be the first imaging method used in these patients. For patients with negative results on somatostatin receptor scintigraphy, guidelines about the use of other imaging studies are proposed.