It was the aim of this study to compare benzodiazepine (Bz) receptor binding and cerebral perfusion in patients with partial epilepsy. Single photon emission tomography (SPET) studies with the flow-marker technetium 99m hexamethylpropylene amine oxine (99mTc-HMPAO) and with the 123I-labelled Bz-receptor ligand Ro 16-0154 (123I-Iomazenil) were performed in 12 patients with partial epilepsy, all with normal magnetic resonance imaging (MRI) and computed tomography (CT) scans. The SPET studies with 123I-Iomazenil were carried out 5 min and 2 h after injection. At 2 h the distribution of activity was very similar to the expected distribution of Bz-receptors in the human brain, known from positron emission tomography (PET) work and post-mortem studies. Early images showed a significantly higher tracer accumulation in the area of the basal ganglia, cerebellum, and naso-pharyngeal space. This finding is caused by non-specific binding and the contribution of the tracer in the blood pool in this phase. Also after 2 h p.i. of 123I-Iomazenil, 9 of the 12 patients showed a focal decrease of of Bz-receptor binding. Ten patients had focal flow abnormalities with 99mTc-HMPAO SPET. In 8 subjects impairment of flow was seen in sites of reduced 123I-Iomazenil uptake. 123I-Iomazenil is suitable for Bz-receptor mapping. In this series of patients, Bz-receptor mapping with SPET seems to offer no advantage over 99mTc-HMPAO in the detection of epileptic foci.

It was the aim of this study to compare benzodiazepine (Bz) receptor binding and cerebral perfusion in patients with partial epilepsy. Single photon emission tomography (SPET) studies with the flow-marker technetium 99m hexamethylpropylene amine oxine (99mTC-HMPAO) and with the 12q-labelled Bz-receptor ligand Ro 16-0154 (~23I-Iomazenil) were performed in 12 patients with partial epilepsy, all with normal magnetic resonance imaging (MRI) and computed tomography (CT) scans. The SPET studies with 123I-Iomazenil were carried out 5 min and 2 h after injection. At 2 h the distribution of activity was very similar to the expected distribution of Bz-receptors in the human brain, known from positron emission tomography (PET) work and post-mortem studies. Early images showed a significantly higher tracer accumulation in the area of the basal ganglia, cerebellum, and naso-pharyngeal space. This finding is caused by non-specific binding and the contribution of the tracer in the blood pool in this phase. Also after 2 h p.i. of 123I-Iomazenil, 9 of the 12 patients showed a focal decrease of of Bz-receptor binding. Ten patients had focal flow abnormalities with 99mTC-HMPAO SPET. In 8 subjects impairment of flow was seen in sites of reduced *23I-Iomazenil uptake. 123I-Iomazenil is suitable for Bz-receptor mapping. In this series of patients, Bz-receptor mapping with SPET seems to offer no advantage over 99mTc-HMPAO in the detection of epileptic foci.

N-Isopropyl-p-¹²³I-amphetamine (¹²³I-IMP) single photon emission computer tomography studies were performed on 17 patients suffering from amyotrophic lateral sclerosis (ALS). All patients displayed varying degrees of impaired fixation of ¹²³I-IMP in the whole brain. These findings were not related to the clinical variants of ALS and the age of the patients. A correlation between the severity of the disease and the degree of impaired fixation could be observed. In addition, patients suffering from ALS for longer periods showed more pronounced impairment of ¹²³I-IMP fixation.

Summary Aim: In an earlier study (study I) we had calculated the costs for FDG-PET investigations with our satellite concept (19). 433 patients were included in the study. Compared to the general indications for PET examinations the proportions of investigations were somewhat untypical: Both parameters have changed actually. Therefore we carried out a renewed data analysis (study II). Methods: All economic parameters were kept, in order to ensure the comparability of both studies. Only an adjustment of the costs to actual conditions was performed. Results: Proportions of investigations: Oncology 63%, Neurology 28%, Cardiology 9%; 3.5 investigations per working day. According to the increased number of investigations the structure of the total costs (DM 1601831) shows a small rise of the percentage costs for the FDG (41% to 42%) and a percentage decrease of the fixed overheads (48% to 43%). The percentage of personnel costs has increased (11% to 15%), the average cost per investigation has diminished: They amounted to DM 2783 in the earlier study (ranging from DM 2458 to 3463). The new data analy-sis results in the average cost of DM 2366 (-15%) per investigation (ranging from DM 2114 to 2840). Exemplary calculations show that a minimum of the costs will be achieved, if four investigations per day are performed. Retaining all parameters, which do not refer to the costs of the FDG, the average amount for one investigation would vary from DM 2000 (no delivery time) to DM 3300 (4 hours of delivery time). Conclusions: The results are in good agreement to the general laws of economic science, according to which an increase of the “number of units” with the same fixed overheads will result in a relative reduction of the costs of the “products”. A further increase in the frequency of investigations will lead to a rise of the average costs per investigation, because of the physical decay of the FDG delivered once a day.

To date, positron emission tomography (PET) is the most powerful tool for the non-invasive study of biochemical processes. Besides its usefulness for basic research PET has been proven to be superior to conventional diagnostic methods in several clinical indications. However, the introduction of PET into clinical practice has been hindered considerably by its costs. Several American studies lend support to the hypothesis that PET may be more cost-effective than the conventional diagnostic work-up-at least for some of its clinical indications. In Germany, however, this hypothesis has still not been verified.