[Prediction of pharmacological effect of octreotide in acromegaly by means of 111In-pentetreotide scintigraphy and calculation of a pituitary uptake index].
OBJECTIVE
The aim of our prospective study was to optimize the determination of the pituitary somatostatin receptor status by means of 111-In-pentetreotide scintigraphy and to compare it intraindividually with the pharmacological effect of octreotide in active acromegaly.


METHODS
In n = 22 patients with growth hormone (GH) secreting pituitary adenoma, 111-In-pentetreotide scintigraphy was performed, and the specific radionuclide accumulation in the pituitary area (evaluation visually as well as semiquantitatively by means of ROI technique and calculation of various uptake indices) was correlated with the acute drop of GH after administration of 100 micrograms octreotide s. c. (octreotide acute test).


RESULTS
The uptake index we propose (cts/pixel-ratio circular pituitary ROI: irregular cerebrum ROI after background correction in the sagittal SPECT slice with maximum pituitary uptake 24 h p.i.) correlates best with the pharmacological effect (acute decrease of GH levels) of octreotide; its upper normal limit amounts of 3.5.


CONCLUSIONS
As often the normal pituitary gland can be visualized scintigraphically, the purely visual differentiation between a normal and a pathological receptor status sometimes is equivocal. A pituitary uptake index, calculated by means of a standardized ROI technique, facilitates this discrimination and so contributes to select possible responders for a treatment with octreotide.
Görges
R
R
Klinik mit Poliklinik für Nuklearmedizin, Johannes Gutenberg-Universität Mainz, Deutschland.
Cordes
U
U
Engelbach
M
M
Bartelt
K M
KM
Haberern
G
G
Hey
O
O
Beyer
J
J
Bockisch
A
A
D000172:Acromegaly / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D000236:Adenoma / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D005260:Female; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D007205:Indium Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D010902:Pituitary Gland / Q000000981:diagnostic imaging* / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011379:Prognosis; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
D018931:Antineoplastic Agents, Hormonal; D007205:Indium Radioisotopes; D019382:Human Growth Hormone; D013004:Somatostatin; C081788:pentetreotide; D015282:Octreotide