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Since the minimal effective dosage for radiosynovectomy is not known, we have performed a doubleblind controlled trial of 1 mCi vs. 5 mCi 198Au in 60 knees of 46 patients with persistent rheumatoid synovitis. The therapeutic effect was assessed with a clinical score, 99mTc pertechnetate uptake measurements and plain X-rays. With regard to clinical parameters no statistical differences between the two groups were found, but results indicate a trend towards a better outcome in patients treated with 5 mCi. 99mTc uptake improved significantly in patients treated with the higher dose and not in the low dose group. Weighing ease of treatment and risk of side effects against the small difference in effectiveness, we conclude that the use of less than 5 mCi of 198Au may be justified. During the study the injection technique was changed, enabling a comparison of two methods. Leakage to lymph nodes and liver decreased when the needle was flushed with normal saline after administration of the radiocolloid.

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Lung volumes, calculated from 81Krm single-photon emission computed tomography (SPECT) of the lungs, were compared with functional residual capacity (FRC), measured with the helium dilution technique in controls and in patients with various pulmonary diseases. SPECT volume was greater than FRC, which was attributed to non-gas-containing structures in the lung such as the alveolar walls, the interstitium, the blood vessels and the blood, included in the SPECT volume. A good correlation (r = 0.91) was found between the two volumes and there was no difference in this relationship between patients and controls. It was concluded that the relative volume distribution, calculated from SPECT, can be used for the quantification of ventilation from 81Krm SPECT steady-state count distributions.

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In 14 patients with advanced stage pulmonary sarcoidosis the distribution of regional ventilation-perfusion ratios (V/Q) was obtained by quantitative analysis of ventilation-perfusion single photon emission computed tomography (SPECT) of the lungs. In 6 patients normal V/Q distributions were found with a decreased DLCO in only one of them. In 8 patients abnormal distributions of V/Q ratios were found. Six of these patients also had a decrease in diffusing capacity for CO (DLCO). It is suggested that the decrease in DLCO in these patients is partly a result of uneven distribution of V/Q ratios.

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The successful application of [131I]metaiodobenzylguanidine (MIBG) in diagnosis and therapy of pheochromocytoma has led to its use in other tumors which derive from the neural crest and potentially concentrate this radiopharmaceutical as well. In the present series, [131]MIBG total-body scintigraphy was used for detection of neuroblastoma in 47 patients and 47 cases of other neural crest tumors. The method was found to be as reliable in neuroblastoma (sensitivity 95%, specificity 100%), as it is in pheochromocytoma. Although other neural crest tumors may concentrate [131I]MIBG, this is not a consistent finding; however, it is useful to investigate which tumors do, as this may provide an alternative treatment modality for some patients. Although followup is still very short, preliminary results of therapeutic use of [131I] MIBG in 21 patients indicate that this treatment modality may be effective in neuroblastoma and malignant pheochromocytoma.

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To evaluate the reliability of total-body scintigraphy using [201Tl]chloride in postoperative follow-up of thyroid carcinoma, this procedure was performed in 326 patients after total thyroidectomy for thyroid carcinoma. The results were compared with those of 131I scintigraphy and thyroglobulin assays. 201Tl total-body scintigraphy was found to have the greatest sensitivity (94%), whereas 131I scintigraphy had the highest specificity (99%). It is shown that 201Tl total-body scintigraphy is a useful procedure in follow-up of thyroid cancer, however, the combination of parameters provides the greatest reliability. In medullary thyroid carcinoma, which is usually 131I negative, 201Tl total-body scintigraphy can be of great value for the localization of metastases which are indicated by elevated serum levels of calcitonin and carcinoembryonic antigen.

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N-isopropyl-p[123I]iodoamphetamine, originally designed for brain scintigraphy, has been found to be retained by the normal lung and to produce excellent camera images. Ten patients with gross abnormalities on their chest radiographs due to lung cancer have been studied with this drug. The diseased parts of the lung consistently showed less uptake and these defects matched those obtained with microspheres labelled with technetium-99m, indicating that 123I-iodoamphetamine has the characteristics of a perfusion tracer. In five out of the 10 patients studied sequential studies showed that improved iodoamphetamine uptake was encountered shortly after a favourable response to radiotherapy and reduced uptake was seen in congruence with the radiation field at a later stage. This first clinical demonstration indicates that the retention of 123I-iodoamphetamine could be a sensitive marker for pulmonary vascular integrity and a useful new tool to identify the extent of disease where the pulmonary circulation is the initial site of the disorder.

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This paper describes the radiation protection procedures that were used in caring for three children treated with therapeutic amounts of 131I-meta-iodobenzylguanidine. Since it was not possible to leave a child alone in a shielded room for several days, the presence of one parent was requested during the treatment. The dose equivalent to the parent was kept to an acceptable level of approximately 1 mSv. This dose equivalent was almost completely due to external radiation since blocking of the parent's thyroid led to a negligible dose equivalent from internal contamination.

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Scintigraphy using I-131 meta-iodobenzylguanidine has been introduced as an effective method to detect pheochromocytomas and neuroblastomas, and the radiopharmaceutical also is applied in therapy of these tumors. The authors present a case of a metastatic gastric carcinoid tumor, another neural crest tumor, concentrating I-131 MIBG, which was documented by conventional scintigraphy and SPECT in correlation with CT scans and colloid scintigrams of the liver. Two therapeutic attempts in this patient, using I-131 MIBG, are described. The metabolic basis of this phenomenon is discussed, and the importance of I-131 MIBG imaging in the detection of neural crest tumors is underlined.

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Total-body scintigraphy with 131I-meta-iodobenzylguanidine (131I-MIBG) was performed in 20 patients with neuroblastoma. In patients who were in complete remission no pathological concentration of 131I-MIBG was found. In 16 patients with residual, recurrent or metastatic neuroblastoma the tumor localizations were correctly identified by 131I-MIBG-scintigraphy In 5 patients additional tumor sites were found. In most patients an inverse relationship between myocardial and tumoral concentration of 131I-MIBG was noted. Dosimetric assessment of 131I-MIBG uptake in patients with metastatic disease revealed cases with considerable tracer concentration and long effective half lives in tumor localizations. It is concluded that 131I-MIBG total-body scintigraphy is useful in the diagnosis and follow-up of neuroblastoma and that therapeutic use of this agent is feasible, if patients are selected upon the merits of dosimetry.

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Reticulo-endothelial function was assessed in 20 patients with active rheumatoid arthritis and 11 patients with systemic lupus erythematosus with regard to the clearance of heat-damaged erythrocytes (HDE). In contrast to previous reports, no correlations were found between disease activity, levels of circulating immune complexes and splenic function. There was no evidence of an obvious hypofunction in the reticulo-endothelial system of the spleen in patients with rheumatoid arthritis or systemic lupus erythematosus. Moreover, a splenic hyperfunction is suggested to be present in some patients. A method for measuring the specific uptake by the liver, spleen and the clearance rate (T 1/2) of the HDE is also described.

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The results of 99mTc-methylene diphosphonate 99mTc-MDP scintigraphy in 37 osteosarcoma patients were evaluated. In 11 of 12 patients with pulmonary metastases these were demonstrated by the scintigram. In 2 of these 11 patients the lung metastases could be shown earlier by scintigraphy than by X-ray tomography. Uptake of 99mTc-MDP appeared to be correlated with the formation of osteoid by the tumor. 99mTc-MDP scintigraphy demonstrated metastases not only in the lungs and the skeleton, but also in the lymph nodes and soft tissues. 99mTc-MDP whole-body scintigraphy should be used routinely for the early detection of osteosarcoma metastases.

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