Octreotide scintigraphy localizes somatostatin receptor-positive islet cell carcinomas.

Tyr-3-Octreotide is a synthetic derivative of somatostatin and a somatostatin-receptor analogue. The iodine-123-labelled compound localizes somatostatin-receptor-positive tumours. In this paper two patients are reported in whom somatostatin receptors were demonstrated in vitro. In a 60-year-old female with an islet cell carcinoma of the pancreas, multiple liver metastases and previously unrecognized bone metastases in the right acetabulum could be diagnosed as the reason for a persistent hypoglycaemia. In a 60-year-old male an islet cell carcinoma of the pancreas was localized with 123I-Tyr-3-octreotide. The somatostatin receptors were demonstrated in vitro and the tumour was successfully treated with somatostatin. These studies demonstrate that 123I-Tyr-3-octreotide offers the possibility of localizing somatostatin-receptor-positive tumours and their metastases. Moreover the method makes it possible to determine the receptor status of a tumour in vivo.     

Diffusion weighted MR imaging of pancreatic islet cell tumors

Purpose

The aim of our study is to demonstrate the feasibility of body diffusion weighted (DW) MR imaging in the evaluation of pancreatic islet cell tumors (ICTs) and to define apparent diffusion coefficient (ADC) values for these tumors.

Materials and methods

12 normal volunteers and 12 patients with histopathologically proven pancreatic ICT by surgery were included in the study. DW MR images were obtained by a body-phased array coil using a multisection single-shot echo planar sequence on the axial plane without breath holding. In addition, the routine abdominal imaging protocol for pancreas was applied in the patient group. We measured the ADC value within the normal pancreas in control group, pancreatic ICT, and surrounding pancreas parenchyma. Mann-Whitney U-test has been used to compare ADC values between tumoral tissues and normal pancreatic tissues of the volunteers. Wilcoxon Signed Ranks Test was preferred to compare ADC values between tumoral tissues and surrounding pancreatic parenchyma of the patients.

Results

In 11 patients out of 12, conventional MR sequences were able to demonstrate ICTs succesfully. In 1 patient an indistinct suspicious lesion was noted at the pancreatic tail. DW sequence was able to demonstrate the lesions in all of the 12 patients. On the DW images, all ICTs demonstrated high signal intensity relative to the surrounding pancreatic parenchyma. The mean and standard deviations of the ADC values (×10⁻³ mm²/s) were as follows: ICT (n = 12), 1.51 ± 0.35 (0.91-2.11), surrounding parenchyma (n = 11) 0.76 ± 0.15 (0.51-1.01) and normal pancreas in normal volunteers (n = 12), 0.80 ± 0.06 (0.72-0.90). ADC values of the ICT were significantly higher compared with those of surrounding parenchyma (p < 0.01) and normal pancreas (p < 0.001).

Conclusion

DW MR imaging does not appear to provide significant contribution to routine MR imaging protocol in the evaluation of pancreatic islet cell tumors. But it can be added to MR imaging protocol to detect the lesion in a limited number of patients with clinical suspicion for pancreatic ICT with negative or suspicious imaging findings.     

Differential diagnosis of non-functional islet cell tumor and pancreatic carcinoma with sonography

OBJECTIVE: To investigate the differential diagnosis of non-functional islet cell tumor (NFICT) and pancreatic ductal adenocarcinoma (pancreatic carcinoma) with clinical presentation and sonographic features. MATERIALS AND METHODS: Twenty cases of NFICT were investigated in the study, and 41 cases of pancreatic carcinoma were included as the control group. Among them, 5 NFICT and 32 pancreatic carcinomas underwent CEUS with SonoVue. Clinical presentation and sonographic characteristics were evaluated with Logistic regression analysis. Furthermore, the preliminary result of contrast enhanced ultrasound (CEUS) was analyzed. RESULTS: Statistic analysis showed four significant factors in differential diagnosis for NFICT and pancreatic carcinoma, including age (P<0.001), tumor size (P=0.006), tumor margin (P<0.001) and vascularity of tumor (P=0.004). Combined these four factors, the sensitivity, specificity and accuracy are 95.0%, 95.1% and 95.1%, respectively. When the patient is younger than 60 years, and tumor is smaller than 5 cm with well-defined margin and hypervascular, it would be most likely a NFICT other than pancreatic carcinoma. NFICT often shows early enhancement and more homogeneous infusion than pancreatic carcinoma on CEUS (P=0.005 and 0.008). CONCLUSIONS: Sonography is able to provide useful differential information for NFICT, which is often misdiagnosed as pancreatic carcinoma.