In-111 Pentetreotide Research Articles

The role of radiolabeled somatostatin analogs in adrenal imaging

We investigated the role of radiolabeled somatostatin analogs (SAs) in adrenal imaging. We evaluated 15 patients (6 men and 9 women, mean age 47 ± 17 years) with imaging-detected adrenal tumors. Patient population was divided into two groups on the basis of the nature of adrenal lesions. Group 1 consisted of patients with benign adrenal lesions ( n = 10). Group 2 consisted of patients with malignant adrenal lesions ( n = 5). Pathology examinations were obtained in 13 cases: 7 pheochromocytomas, 2 adenomas, 2 cysts, 1 carcinoma, and 1 fibro-histiocytoma. One patient had a proven diagnosis of non-small-cell lung cancer associated with the presence of a right adrenal mass. The last patient had a clinical diagnosis of Werner syndrome associated with the presence of a large left adrenal mass. All patients underwent scintigraphic studies using radiolabeled SAs, of which indium-111 (In-111) pentetreotide was used in 11 cases and technetium-99m (Tc-99m)-labeled peptides (P-587 or P-829) were used in the remaining four cases. No significant labeled SAs uptake was observed in the majority (8 of 10, 80%) of the benign adrenal lesions (Group 1); however, increased uptake was found in two benign pheochromocytomas. Conversely, significant labeled SAs uptake was observed in the majority (4 of 5, 80%) of the malignant adrenal lesions (Group 2); however, the last lesion (carcinoma) did not show abnormal uptake. Results of this study show that the majority of benign adrenal tumors do not concentrate radiolabeled SAs; conversely, the majority of malignant adrenal lesions show significant SAs uptake, suggesting the presence of somatostatin receptors. This finding may allow the use of somatostatin as a treatment agent in malignant adrenal tumors. Thus, the main role of labeled SAs in adrenal imaging consists of lesion characterization rather than tumor detection and localization.

Axillary lymph node metastases detection with nuclear medicine approaches in patients with newly diagnosed breast cancer

Three different tracers, Tc-99m-Sesta MIBI, In-111-Pentetreotide and F-18-FDG, were evaluated in a preliminary study in three different groups of 10 breast cancer patients programmed for breast cancer resection and axillary dissection. Planar scintigraphy and single photon emission tomography (SPET) technique were used for imaging with Tc-99m-Sesta-MIBI and In-111-Pentetreotide, positron emission tomography (PET) was used for imaging with F-18-FDG. We studied 30 breast cancer patients; their clinical stage according to the TNM classification was 30 T1-T2, 1 T4 and 1 Tx (one patient had bilateral cancer and one had bifocal cancer). The lymph nodal status ranged from NO to N2 (14 NO, 16 N1, 1 N2). Tc-99m-Sesta MIBI, In-111 Pentetreotide SPET and F-18-FDG PET were randomly performed before surgery to visualize the primary tumors and to detect axillary lymph node invasion. Tc-99m-Sesta MIBI correctly visualized 10 out of 11 primary cancers in 10 patients. In-111-Pentetreotide detected 9 out of 10 primary cancers. F-18-FDG imaged all the tumors (10). As regards the axillary nodes, Tc-99m-MIBI excluded axilla involvement in 7 out of 7 negative axillae (N-), while it was positive in 2 out of 3 positive cases (N+); In-111-Pentetreotide correctly identified 7 out of 8 negative axillae (N-), while it detected 2 of 3 positive sites. F-18-FDG visualized all positive axillary lymph nodes (4 out of 4 N+ patients) and correctly excluded involvement in all negative patients (6 out of 6 N- cases). This study demonstrated that all three tracers are adequate to be proposed as tumor seeking agents with the aim of developing non-invasive diagnostic methods for pre-operative detection of axillary metastases, so that surgical dissection can be limited to selected patients. The authors discuss the advantages and disadvantages of the different radiopharmaceuticals and conclude that in centers with PET facilities F-18-FDG is the best tumor seeking agent for the evaluation of axillary status. Between Tc-99m-Sesta MIBI and In-111-Pentetreotide the former seems to present more advantages in this kind of application, considering also its lower cost and easier availability. These results encourage further study, including the simultaneous comparison of these tracers in breast cancer staging.

Somatostatin Receptors in the Orbits

In-111 pentetreotide has been recommended for the detection of somatostatin receptor (SSR) positive tumors. Sites with increased numbers of activated lymphocytes may also show In-111 pentetreotide with Graves' ophthalmopathy (GO) compared to various other orbital disorders. Five patients with GO, three patients with necrotizing scleritis, and two patients with orbital pseudotumor were imaged at 4 hours, 24 hours, and 48 hours after injection of In-111 pentetreotide. Although planar images did not show considerable uptake, SPECT slices showed marked and persistent uptake in the orbits unilaterally in one patient, and bilaterally in three patients with GO. There was no significant correlation between the In-111 pentetreotide activity and the degree of opthalmopathy determined by Werner's classification. Pseudotumors also showed positive uptake. Early uptake was present in one patient with necrotizing scleritis because of Wegener's granulomatosis, and was completely diminished at 24 hours. Octreotide treatment in three patients with GO did not cause any clinical improvement. Although the presence of SSR, either on the infiltrated lymphocytes or on fibroblasts, implies that octreotide treatment for GO can be considered, the results are not encouraging. Nonspecific binding might be present when uptake patterns of orbits and persistence of activity during octreotide treatment are considered.

In-111 pentetreotide in the diagnostic work-up of patients with bronchogenic carcinoma : J.v. Pawel ∗, H. Wagner ∗, C.-M. Kirsch, K. Latsch Div. Nuclear-Medicine, Dept. Radiology, University of Munich, FRG, ∗Div. Oncology, Zentralkrankenhaus Gauting, FRG

In-111 pentetreotide in the diagnostic work-up of patients with bronchogenic carcinoma : J.v. Pawel ∗, H. Wagner ∗, C.-M. Kirsch, K. Latsch Div. Nuclear-Medicine, Dept. Radiology, University of Munich, FRG, ∗Div. Oncology, Zentralkrankenhaus Gauting, FRG

Somatostatin-receptor imaging of medullary thyroid carcinoma.

In-111 pentetreotide scintigraphy of 10 patients with residual or metastatic medullary thyroid carcinoma is described. Six patients had sporadic tumor and 4 had MEN IIB. Foci of increased tracer uptake were observed in 9 patients: in the thyroid bed (4 patients), the mediastinum (3 patients.), the shoulder area and left lower abdomen (1 patient), and the left upper abdomen (1 patient). The 10th patient had no abnormal uptake. CT confirmed 2 mediastinal lesions and 2 out of 3 thyroid masses, but did not detect the thyroid remnants or the lesions in the shoulder area and abdomen. Lung lesions < or = 1 cm in diameter and ill-defined liver foci (2 patients) were seen on CT, but not on scintigraphy. Small liver metastases not demonstrated on CT or on scintigraphy were identified at surgery in a MEN IIB patient. Elevated urinary epinephrine was found in 2 out of 4 MEN IIB patients. In one, tracer uptake in the left adrenal corresponded to a mass on CT, to pathological uptake of MIBG and DMSA, and to a tumor removed at surgery. The second patient had peritoneal spread of malignant pheochromocytoma (at surgery), but negative CT and only a single focus in the left lower abdomen on scintigraphy. Somatostatin-receptor imaging is useful for the detection of residual and recurrent medullary thyroid carcinoma, and may identify pheochromocytoma in MEN IIB patients.