The pituitary uptake of 111In-DTPA-D-Phe1-octreotide in the normal pituitary and in pituitary adenomas
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The aim of this study was to compare the pituitary 111In-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 111In-DTPAD- 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 α-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 111In-DTPA-DPhe1-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 111In-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 α-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 (≥30% of baseline size) during long-term octreotide therapy. Both in GHsecreting and in NFA, a significant correlation was found between percent GH or α-subunit suppression after 6-12 months of octreotide therapy and T-to-B ratios both in early (r=0.626; p<0.0001 and r=0.738, p=0.003, respectively) and late images (r=0.569; p=0.002 and r=0.8, p=0.01, respectively). In conclusion, the 111In-DTPA- D-Phe1-octreotide uptake in pituitary adenomas was significantly correlated to octreotide treatment. However, since pituitary 111In-DTPAD- Phe1-octreotide uptake was clearly detectable in 40% of patients with SS-ET not located in the pituitary region at 24 hr post-injection, 111In-DTPA- D-Phe1-octreotide scintigraphy with late pituitary images can not be considered an useful method to predict the chronic responsiveness to octreotide in individual patients. Caution should also be taken in evaluating the results of the scintigraphy with early images in patients with scant uptake before excluding them from treatment.
Key-wordsPituitary adenomas GH neuroendocrine tumors somatostatin somatostatin receptors octreotide
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- 5.Reubi J.C. Use of receptors autoradiography to measure the somatostatin receptor status in pituitary adenomas and other neuroendocrine tumors. In: Casanueva F.F., Dieguez C. (Eds.), Recent advances in basic and clinical neuroendocrinology. Int. Congr. Ser. 864. Amsterdam, Excepta Medica, 1989, p. 285.Google Scholar
- 6.Lamberts S.W.J., Uitterlinden P., Schuijff P.C., Klijn G.C. Therapy of acromegaly with sandostatin: the predictive value of an acute test, the value of serum somatomedin-C measurements in dose adjustement and the definition of a biochemical “cure”. Clin. Endocrinol. 29: 411, 1988.CrossRefGoogle Scholar
- 9.Faglia G., Bazzoni N., Spada A., Arosio M., Ambrosi B., Spinelli F., Sara R., Bonino C., Lunghi F. In vivo detection of somatostatin receptors in patients with functionless pituitary adenomas by means of radioiodinated analog of somatostatin ([123-I]SDZ 204-090). J. Clin. Endocrinol. Metab. 73: 850, 1991.PubMedCrossRefGoogle Scholar
- 11.Broson-Chazot F., Houzard C., Ajzenberg C., Noucaudie M., Duet M., Mundler O., Marchandise X., Epelbaum J., Gomez De Alzaga M., Scäfer J., Meyerhof W., Sassolas G., Warnet A. Somatostatin receptor imaging in somatroph and non-functioning pituitary adenomas: correlation with hormonal and visual responses to octreotide. Clin. Endocrinol. 47: 589, 1997.CrossRefGoogle Scholar
- 12.Plöckinger U., Reichel M., Fett U., Saeger W., Quabbe H-J. Preoperative octreotide treatment of growth hormone- secreting and clinically non-functioning pituitary macroadenomas: Effects on tumor volume and lack of correlation with immunohistochemistry and somatostatin receptor scintigraphy. J. Clin. Endocrinol. Metab. 79: 1416, 1994.PubMedGoogle Scholar
- 15.Colao A., Di Sarno A., Landi M.L., Cirillo S., Sarnacchiaro F., Facciolli G., Pivonello R., Cataldi M., Merola B., Annunziato L., Lombardi G. Long-term and low dose treatment with cabergoline induces macroprolactinoma shrinkage. J. Clin. Endocrinol. Metab. 82: 3574, 1997.PubMedCrossRefGoogle Scholar
- 16.Bakker W.H., Albert R., Bruns C., Breeman W.A.P., Hofland L.J., Marbach P., Pless J., Pralet V., Stolz B., Koper J.W., Lamberts S.W.J., Visser T.J., Krenning E.P. [111In-DTPA-D-Phe1]-octreotide, a potential radiopharmaceutical for imaging of somatostatin receptor-positive tumors: synthesis, radiolabeling and in vitro validation. Life Sci. 49: 1583, 1991.PubMedCrossRefGoogle Scholar