Detection Of Neuroendocrine Tumors Research Articles

Radio-guided surgery with the use of [99mTc-EDDA/HYNIC]octreotate in intra-operative detection of neuroendocrine tumours of the gastrointestinal tract

Radio-guided surgery (RGS) is an intra-operative localising technique which enables identification of tissue "marked" by a specific radiotracer injected before surgery. It is mainly used for sentinel node mapping and for detection of parathyroid adenomas and other tumours, including neuroendocrine tumours of the gastrointestinal tract (GEP-NET). The aim of this study was to determine whether intra-operative radio-detection with the use of [(99m)Tc-EDDA/HYNIC]octreotate, a new somatostatin analogue, is able to reveal an unknown primary and secondary sites, thereby improving surgical treatment and the final outcome of GEP-NET. The study group included nine patients with suspected GEP-NET (four carcinoids, five pancreatic NET) localised with somatostatin receptor scintigraphy (with [(99m)Tc-EDDA/HYNIC]octreotate), who had negative results on other pre-operative imaging tests. At surgery, suspected tumours were measured in situ and ex vivo and precise exploration of the abdominal cavity was performed with the intra-operative scintillation detector (Navigator). Intra-operative gamma counting localised three carcinoids. In one patient SRS was false positive (owing to inflammatory infiltration). Compared with SRS, RGS revealed additional lymph node metastases in one case. RGS resulted in successful localisation of all pancreatic NET (the smallest lesion was 8 mm in diameter). [(99m)Tc-EDDA/HYNIC]octreotate SRS followed by RGS is a promising technique to improve the rate of detection and efficacy of treatment of GEP-NET, especially in the presence of occult endocrine tumours. The imaging properties of [(99m)Tc-EDDA/HYNIC]octreotate and the 1-day imaging protocol offer opportunities for more widespread application of this tracer followed by RGS in oncology.

Ga-68-DOTATOC: Feasibility of high throughput screening by small animal PET using a clinical high-resolution PET/CT scanner

As radio peptide tracers have been developed in recent years for the high sensitive detection of neuroendocrine tumors, still the broad application of other peptides to breast and prostate cancer is missing. A rapid screening of new peptides can, in theory, be based on in vivo screening in animals by PET/CT. To test this hypothesis and to asses the minimum screening time needed per animal, we used the application of Ga-68-DOTATOC PET/CT in rats as test system. The Ga-68-DOTATOC yields in a hot spot imaging with minimal background. To delineate liver and spleen, we performed PET/CT of 10 animals on a SIEMENS Biograph 16 LSO HIGHREZ after intravenous injection of 1.5 MBq Ga-68-DOTATOC per animal. Animals were mounted in an ‘18 slot’ holding device and scanned for a single-bed position. The emission times for the PET scan was varied from 1 to 20 min. The images were assessed first for “PET only” and afterwards in PET/CT fusion mode. The detection of the two organs was good at emission times down to 1 min in PET/CT fusion mode. In the “PET only” scans, the liver was clearly to be identified down to 1 min emission in all animals. But the spleen could only be delineated only by 1 min of emission in the PET/CT-fusion mode. In conclusion the screening of “hot spot” enriching peptides is feasible. “PET only” is in terms of delineation of small organs by far inferior to PET/CT fusion. If animal tumors are above a diameter of 10 mm small, animal PET/CT using clinical high resolution scanners will enable rapid screening. Even the determination of bio-distributions becomes feasible by using list mode tools. The time for the whole survey of 18 animals including anesthesia, preparation and mounting was approximately 20 min. By use of several holding devices mounted simultaneously, a survey time of less than 1 h for 180 animals can be expected.

Ectopic ACTH-Secreting Syndrome: A Single Center Experience Report with a High Prevalence of Occult Tumor

Differentiation between the two forms of ACTH-dependent Cushing's syndrome is a challenging task. Although the majority of these cases will be diagnosed as Cushing's disease secondary to an ACTH-secreting pituitary adenoma, 10-15% result from the ectopic ACTH secretion syndrome (EAS), which is usually due to neuroendocrine tumors. In the present study we report our experience with EAS in eight patients evaluated and treated during the past 10 years. Our experience in the evaluation and management of EAS was retrospectively reviewed. The latter included a standard biochemical assessment (urinary free cortisol, low- and high-dose dexamethasone suppression tests), petrosal sinus sampling when indicated and imaging techniques such as pituitary MRI, total body CT and somatostatin receptor scintigraphy. The ectopic nature of the ACTH hypersecretion was confirmed with inferior petrosal sinus samplings in all cases. CT scanning localized a putative tumor in 6/8 patients, whereas octreotide scintigraphy was positive in only five. In all cases, the source was traced to the lungs. However, upon performing thoracotomy, a documented ACTH-secreting bronchial carcinoid tumor was found in only four patients. Thus, 4/8 patients with EAS remained "occult." All of these patients underwent adrenalectomy for hypercortisolism control. EAS is a rare cause of ACTH-dependent Cushing's syndrome. Truly "occult" tumors were frequent and these patients need to be under close surveillance for the detection of neuroendocrine tumors.

The yield of wireless capsule endoscopy in the detection of neuroendocrine tumors in comparison with CT enteroclysis

Patients with neuroendocrine tumors (NET) of the small bowel often present with metastatic disease, and localization of the primary tumor still is a diagnostic challenge. Wireless capsule endoscopy (WCE) is an established method that improves the diagnostic evaluation of diseases of the small intestine. The aim of this study was to determine the diagnostic accuracy of WCE in imaging neuroendocrine tumors of the small bowel in these patients. We retrospectively compared the findings of capsule endoscopy to the findings of CT enteroclysis in patients with histopathological confirmation of NET. Eight patients with newly established diagnosis of metastatic NET were included. All patients underwent CT enteroclysis and wireless capsule endoscopy within a maximum of 2 weeks. Number of primary tumors detected. The results of surgery were used as a gold standard for both methods. CT enteroclysis detected the primary tumor in 4 of 8 patients whereas WCE found the primary in 3 patients. On the contrary, CT enteroclysis provided more false-positive results. Frequent extraluminal tumor growth. In patients with NET, wireless capsule endoscopy may be helpful in individual cases but the general diagnostic value of this method may be limited due to frequent extraluminal growth of these tumors.

Separation of two labeled components of [111In] -OctreoScan by HPLC

[111In]-DTPA-D-Phe1-octreotide (OctreoScan®, Mallinkrodt) is widely used for detection of neuroendocrine tumors and has lately been proposed for radionuclide therapy. We found, using HPLC and a GF-250 column (Zorbax®, Hewlett Packard), that OctreoScan® can be separated in two radiolabeled components of about equal amount. The analytical conditions for a quantitative isolation indicate that the two-peptide components of OctreoScan®have different lipophilicity. The isolated components are stable and do not transform into each other at room temperature during 6 hours (shelf-life of OctreoScan®).

Imaging of neuroendocrine tumors of the pancreas.

Neuroendocrine tumors of the pancreas are uncommon neoplasms of the pancreas that can occur sporadically or in association with various syndromes such as multiple endocrine neoplasia type 1 (MEN I). Patients can present with a specific clinical syndrome related to biochemically functioning tumors or with nonspecific symptoms related to mass effect or metastases. The size, function, consistency, and malignant behavior of neuroendocrine tumors are integrally related. Imaging has a major role in the preoperative localization of the primary tumor and detection of metastases. Several techniques are available including ultrasound, endoscopic ultrasound, computed tomography (CT), MR, somatostatin receptor scintigraphy, angiography, and arterial stimulation with venous sampling; each with unique advantages and limitations. The reported performance for these techniques vary widely, and as a result, recommended imaging algorithms are controversial. Recent technical advances in ultrasound, CT, and MRI have occurred that may improve the sensitivity of some of the techniques. Further improvements are likely in the future. In this chapter we will review imaging techniques used to study the pancreas as it relates to the detection of neuroendocrine tumors, imaging findings of these tumors using various imaging modalities, and the advantages, limitations and results obtained with each technique.