In a small patient population, 188Re-HEDP therapy for bone pain palliation was effective and was associated with minimal toxicity.

Telecobalt irradiation in combination with intrathecal (IT) methotrexate has been replaced by IT 198Au-colloid and methotrexate for meningosis prophylaxis in leukemia. Seventy-seven children received 56-200 MBq 198Au-colloid. The distribution was measured with a scintillation camera having a data processing facility. The radiopharmaceutical is adsorbed at the surface of the spaces with cerebrospinal fluid (CSF) 10-20 h after application. The normal retention of the administered radioactivity in the intracranial subarachnoid space (ISS) and in the spinal subarachnoid space (SSS) were 52 +/- 10% and 26 +/- 9%, respectively. An impairment of the normal distribution was observed after IT methotrexate and also postinjection CSF leakage. The calculated radiation absorbed doses in the cerebral and spinal meninges at a depth of 0.01 cm, i.e. the thickness of the pia, were 45 +/- 17 mGy and 189 +/- 91 mGy, respectively, for 1 MBq administered 198Au-colloid. The dosimetry shows that an effective radiation absorbed dose of 18 Gy can be delivered to the cerebral meninges by the application of 400 MBq 198Au-colloid.

Coincidence imaging with a dual-head gamma camera may offer a cost-effective alternative to dedicated PET. The aim of this study was to compare the diagnostic accuracy of coincidence imaging and PET in patients with differentiated thyroid cancer. Thirty-one patients were studied after thyroidectomy and radioiodine ablation. They were injected with a single dose of 300 MBq 18F-FDG. Scanning was performed on a dedicated PET system after 1 hr, and on a coincidence gamma camera after 4 hrs. Based on a lesion-by-lesion comparison, coincidence imaging and PET concurred in 69% of 118 lesions. Based on lesion size, concurrence was 96% in lesions larger than 1.5 cm, and 62% in those between 1 and 1.5 cm. Lesions smaller than 1 cm could not be identified with coincidence imaging. Identical staging was obtained with coincidence imaging and PET in 26/31 patients (84%). In four patients FDG accumulating lesions were shown by both the coincidence camera and the dedicated scanner, but not detectable with any other imaging means and were confirmed histologically on surgery. Although a coincidence camera is technically inferior to a dedicated PET scanner, it may provide clinically useful results in situations were a lesion of sufficient size and FDG uptake is to be expected, e.g. when evaluating a known lesion for malignancy.

Summary Aim: Several radiopharmaceuticals were compared previously with regard to the efficiency in pain palliation of bone metastases. Furthermore, first results were reported on the suitability for such kind of therapy of the generator produced radionuclide rhenium-188. Method: Influence of Rhenium-188-HEDP (Re-188), Rhenium-186-HEDP (Re-186) and Strontium-89 (Sr-89) on pain symptoms and bone marrow function were obtained in 44 patients (pts). These were 16 pts. with Re-188 (2943 ± 609 MBq), 13 pts. with Re-186 (1341 ± 161 MBq) and 15 pts. with Sr-89 (152 ±18 MBq) (6 woman with breast cancer and 38 mens with prostata cancer). Results: 81 of pts. after Re-188,77% after Re-186 and 80 % after Sr-89 reported relief of pain. The Karnofsky-lndex established by pts. increased from 74 ± 9% to 85 ± 11 % after Re-188, from 70 ± 1 1 % to 76 ± 1 1 % after Re-186 and from 62 ± 10% to 69 ± 10% after Sr-89. However, the difference between the pre- and the post-therapeutic value is only statistically significant in the case of Re-188 therapy (p = 0.001 ). A decrease of platelets of 30 ± 14% after 2.8 ± 0.7 for pts. treated with Re-188, of 39 ± 20% after 3.7 ± 1.0 weeks for pts. treated with Re-186 and of 34 ± 26% after 4.4 ± 1.0 weeks for pts. treated with Sr-89 compared to the value before therapy was observed. The difference was not significant between the 3 groups of pts. (p= 0.125 to 0.862). Conclusion: All tried radiopharmaceuticals were effective in pain palliation. The various radionuclides had no significant difference in the pain relief or the bone marrow impairment. If only the Karnofsky-lndex after Re-188 HEDP seems to be a little more increase.

Methods of parametric imaging of radionuclide angiography using parameters like appearance time, peak time, transit time, height of peak, arterial slope and area of inflow were developed and evaluated regarding their diagnostic meaning in 111 patients suffering from TIA or PRIND and in 30 normal persons. The meaning of these single parameters could shown depended on the specificity of the diagnostic question. Local cerebral blood flow can be estimated most favourably by parametric images of area of inflow whereas transit time is most promising as a diagnostic tool for evaluation of total cerebral blood flow classified with reference to severity of the perfusion disturbance. Appearance time is suited very well to estimation of collateral perfusion. Blood flow in great cerebral arteries could be seen well by non parametric imaging of radioactivity inflow in the brain supplying arterial vessels in the cranial floor. Applying a combination of the parametric images, the sensitivity for detection of disturbances of cerebral blood flow amounts to 0.91. A specificity of 0.88 and accuracy of 0.90 were found. The described combination of evaluation of RNA using various parameters is considered a well suited method for detection of disturbances in local and total cerebral blood flow by means of planar imaging.