(dtpa-phe(1))-octreotide and Adenoma

The medical approach to patients with secreting or clinically non-functioning pituitary adenoma as made considerable progress thanks to the use of new somatostatin analogs. They were first used to treat acromegaly in the mid 1980s and numerous studies have shown a reduction in GH concentration in over 90% of acromegalic patients. Good results were obtained using slow-release analog treatment also in TSH-secreting adenomas, whereas the therapeutic efficacy of these peptides in clinically non-functioning adenomas is still controversial. Treatment with somatostatin analogs improves symptoms, normalises hormone secretion and in some cases may induce a reduction in the volume of pituitary adenomas. Scintigraphy with octreotide may help to select patients who respond to this form of treatment.

Topics: Acromegaly; Adenoma; Adolescent; Adrenal Gland Neoplasms; Adult; Aged; Antineoplastic Agents, Hormonal; Carcinoma; Humans; Indium Radioisotopes; Insulin-Like Growth Factor I; Kidney Neoplasms; Melanoma; Middle Aged; Octreotide; Pentetic Acid; Peptides, Cyclic; Pheochromocytoma; Pituitary Neoplasms; Predictive Value of Tests; Prolactinoma; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Somatostatin; Thymoma; Thymus Neoplasms; Thyroid Neoplasms; Thyrotropin; Treatment Outcome

Topics: Adenoma; Aged; Empty Sella Syndrome; Female; Humans; Indium Radioisotopes; Magnetic Resonance Imaging; Octreotide; Pentetic Acid; Pituitary Neoplasms; Radiopharmaceuticals; Receptors, Dopamine D2; Receptors, Somatostatin; Sodium Pertechnetate Tc 99m; Thyrotropin; Tomography, Emission-Computed, Single-Photon

The aim of this study was to compare the pituitary (111)In-DTPA-D-Phe1-octreotide uptake measured in 49 patients subjected to the scintigraphy for SS-R expressing tumors not located in the sellar region with that measured in 38 patients with pituitary adenomas. The 87 subjects enrolled in this study were divided into two groups: the first included SSR-expressing tumors (SS-ET), 10 thymomas, 13 differentiated thyroid carcinomas, 4 carcinoids, 5 neuroendocrine tumors, 5 insulinomas, 6 melanomas, 2 renal carcinomas, 2 pheocromocytomas, and 2 parathyroid tumors, while the second included pituitary adenomas, 25 GH-secreting, 4 GH/PRL-mixed and 9 clinically nonfunctioning adenomas (NFA). Planar and single-photon-emission tomography images of the head were obtained 2-4 and 24 hours after the injection of 77-103 MBq of (111)In-DTPA-D-Phe1-octreotide and pituitary uptake was measured by the region of interest method. A 4 point score was used to grade the pituitary-to-blood (T-to-B) ratios: 0=negative; 1 =faint (T-to-B=<1.5); 2=moderate (T-to-B=1.6-3.5); 3=intense (T-to-B=>3.5). In patients with pituitary adenomas, the percent suppression of GH and alpha-subunit levels after 6-12 months of octreotide treatment (0.3-0.6 mg/day) was correlated to T-to-B ratios. After 2-4 hr from injection, pituitary (111)In-DTPA-D-Phe1-octreotide uptake was moderate/intense in 2 out of 49 SS-ET (4%), 18 out of 29 acromegalics (62%) and 6 NFA (66.6%), while a faint uptake was detected in 4 SS-ET (8%), 8 GH-secreting adenomas (27.5%) and 3 NFA (33.3%). Negative scan was detected in the remaining 43 SS-ET (87.7%) and 3 GH-secreting microadenomas (10.3%). 24 hr after injection, pituitary (111)In-DTPA-D-Phe1-octreotide uptake was moderate/intense in SS-ET (10.2%), 21 GH-secreting adenomas (72.4%), and 9 NFA (100%) while a faint uptake was detectable in 15 SS-ET (30.6%), and 6 GH-secreting adenomas (20.7%). No uptake was visualized in 29 SS-ET, and 2 GH-secreting adenomas. By MRI a pituitary tumor was shown in the 2 SS-ET with early moderate tracer uptake. Normalization of circulating GH/IGF-I levels and suppression of alpha-subunit levels was achieved in 16 of 18 acromegalics (88.9%) and 5 of 6 NFA-bearing patients, respectively, with scan scored 2-3 at early images. Eleven acromegalics (37.9%) and 2 NFA (22.2%) displayed significant tumor shrinkage (> or =30% of baseline size) during long-term octreotide therapy. Both in GH-secreting and in NFA, a significant correlation was found betwee

Topics: Adenoma; Adolescent; Adult; Aged; Female; Humans; Indium Radioisotopes; Male; Middle Aged; Octreotide; Pentetic Acid; Pituitary Gland; Pituitary Neoplasms; Radionuclide Imaging; Radiopharmaceuticals

Pituitary uptake of [111In-DTPA]-octreotide is highly variable, and no formal methods for quantification have been described. Conflicting results have therefore been published as to the presence of somatostatin receptors in nonsecreting adenoma of the pituitary gland. The aim of the present study was to define the most accurate method for the analysis of [111In-DTPA]-octreotide SPECT studies of the pituitary gland.. We used a multidetector brain SPECT camera to measure pituitary uptake of [111In-DTPA]-octreotide in healthy volunteers and patients with and without pituitary adenoma. For quantification, two methods were compared, one involving a manually drawn ROI and one a fixed ROI, as to their reliability and discriminative power. The optimal time interval after injection was also studied in the volunteers.. Optimal images were obtained 24 hr after injection. Correction for background activity is not useful in view of the very low counts at that time which result in highly fluctuating ratios. Lower variability was observed in the fixed ROI method in which activity was expressed as counts corrected for dosage and body weight.. A fixed ROI method without background correction is the most reliable way to measure pituitary uptake of [111In-DTPA]-octreotide. This method allows for good separation of somatostatin-receptor-positive adenomas from normal pituitary glands.

Topics: Adenoma; Adult; Aged; Case-Control Studies; Female; Humans; Indium Radioisotopes; Male; Middle Aged; Octreotide; Pentetic Acid; Pituitary Gland; Pituitary Neoplasms; Receptors, Somatostatin; Time Factors; Tomography, Emission-Computed, Single-Photon

Scintigraphy with [111In-DTPA-D-Phe]-octreotide is a recently developed technique for imaging somatostatin receptors in many neuroendocrine tumors. A good correlation between high [111In-DTPA-D-Phe]-octreotide uptake and the response to octreotide therapy has been proved in TSH- and GH-secreting pituitary adenomas, while few and conflicting scintigraphic data on somatostatin receptors in non-functioning tumors have been reported in the literature. The present study presents the results obtained with [111In-DTPA-D-Phe]-octreotide scintigraphy in thirteen patients with GH-secreting pituitary adenoma, four patients with inappropriate TSH-secretion and twelve patients with non-functioning pituitary adenoma. Twelve out of the 13 patients with GH-secreting pituitary adenomas had a positive scan; moreover, in 5/6 patients with a GH-secreting microadenoma (tumor size range 5-8 mm) a positive scan was found. Two TSH-secreting macroadenomas had a positive scan while a negative scan was obtained for a TSH-secreting pituitary microadenoma and in a patient with non-neoplastic, inappropriate secretion of TSH. Finally, only 2/12 patients with non-functioning pituitary adenoma showed a positive scan. In conclusion, [111In-DTPA-D-Phe]-octreotide scintigraphy is a useful tool to confirm the presence of somatostatin receptors in selected patients with GH- and TSH-secreting pituitary adenoma. The role of [111In-DTPA-D-Phe]-octreotide scintigraphy in non-functioning pituitary tumors remains to be established, but it could be useful for octreotide treatment in patients who refuse surgery or who are poor surgical candidates.

Topics: Adenoma; Adult; Aged; Aged, 80 and over; Antineoplastic Agents, Hormonal; Female; Human Growth Hormone; Humans; Indium Radioisotopes; Male; Middle Aged; Neuroectodermal Tumors; Octreotide; Pentetic Acid; Pituitary Neoplasms; Radiopharmaceuticals; Receptors, Somatostatin; Skull; Thyrotropin; Tomography, Emission-Computed, Single-Photon

This study reports on 111In-octreotide scintigraphy in 20 patients affected with pituitary adenomas, including tracer uptake ratios and in vitro immunohistochemical characterization of the matostatin receptor state. 111In-octreotide uptake was already observed at 4 hours in 7/8 GH-secreting adenomas, in 5/7 non-secreting adenomas and in 1/5 prolactinomas. Concordance between the scan and the histochemical results was observed in all cases. The uptake ratios evaluated at 24 hours ranged from 2.3 to 4.2. The following conclusions were drawn: 1) 111In-octreotide is a suitable tracer to evaluate the somatostatin receptor state of pituitary adenomas; 2) Semi-quantitative measures of tracer uptake can be easily obtained with static planar scanning, but more refined techniques are needed for receptor kinetics evaluation; 3) This nuclear technique is a promising non-invasive tool to identify patients with somatostatin receptor positive pituitary adenomas who might potentially benefit from pre- and/or post-surgery cold octreotide medical treatment.

Topics: Adenoma; Antineoplastic Agents, Hormonal; Human Growth Hormone; Humans; Immunohistochemistry; Indium Radioisotopes; Octreotide; Pentetic Acid; Pituitary Neoplasms; Prolactinoma; Radionuclide Imaging; Radiopharmaceuticals; Receptors, Somatostatin