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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.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).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.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.

In 17 mainly coronary patients increase in blood flow due to therapeutical vasodilation was measured in the region almost totally supplied by the left coronary artery by two different methods, the 133-Xenon washout technique and via arterio-venous oxygen difference (AVDO2). With both methods similar results were obtained (r=0.89). Mean maximal increase in flow 15 min. after 40 mg Carbochromen i.v. amounted to +22.4% with the 133-Xenontechnique, +21.5% with AVDO2. 5min. after 20 mg intracoronary dipyridamol mean flow increased by 47.8% (Xenon technique) and 47.1% (AVDO2) respectively. Decrease in coronary reserve is correlated more with the amount of damaged byocardium than with the degree of coronary obstruction. The limited reliablility of all measurements of total coronary blood flow in heart diseases with regional disturbances is specially indicated.