[131I]metaiodobenzylguanidine in neuroblastoma patients at diagnosis.

Treatment of resistant neuroblastoma with high dosage [131I]metaiodobenzylguanidine (131I-MIBG) appears effective since encouraging results have been obtained so far even in patients with very advanced, intensively pre-treated disease. We have already reported a stage III NB patient treated at diagnosis, who is at present in complete remission with a 4-year follow-up. To further explore the potential role of this new drug in untreated patients, we administered radionuclide to two children with stage III neuroblastoma. Both cases received 131I-MIBG at relatively low doses, and showed a significant reduction of the tumor mass and, interestingly enough, no evidence of 131I-MIBG uptake of a tracer dose in the remaining tumor. Particularly in case 1, the permanence and subsequent progression of the part of the tumor mass without 131I-MIBG uptake, after therapeutic doses of 131I-MIBG which apparently destroyed the 131I-MIBG-positive cell population, clearly suggest heterogeneity at diagnosis, with a dual neuroblastoma cell population, one with 131I-MIBG uptake and the other without. Aside from the biological implications of the heterogeneous MIBG uptake in neuroblastoma at diagnosis, our findings suggest that in stage III neuroblastoma patients even a relatively small dose of 131I-MIBG administered at diagnosis is sufficient to either completely destroy the primary tumor, as reported by our group, or to destroy that part of the tumor which shows 131I-MIBG uptake (as in the present cases), without any significant hematologic toxicity. Furthermore, a single course of 131I-MIBG at the dosage employed here does not appear to jeopardize the subsequent use of chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

[A comparison of scintigraphy with radioiodinated MIBG and CT in localizing pheochromocytomas]. / Confronto tra scintigrafia con MIBG radioiodata e TC nella localizzazione dei feocromocitomi.

In order to define the diagnostic roles of MIBG imaging and CT in the detection of pheochromocytomas (pheos), the results obtained in 45 patients suspected of bearing pheo and studied with both modalities were analyzed and compared. Scintigraphy was correctly negative in 22/23 cases, correctly positive in 11/12 adrenal and 5/5 extra-adrenal pheos, and in 4/5 malignant pheos (metastases present in 2 cases were also identified). CT was correctly negative in 20/23 cases (a mass other than a pheo was detected in 3 patients); correctly positive in 12/12 adrenal and 4/5 extra-adrenal pheos and in 5/5 malignant pheos. Sensitivity, specificity and accuracy of scintigraphy and CT were 91% and 95.4%, 95.6% and 87%, 93.3% and 91.1% respectively (differences were not statistically significant). The overall data emphasize the complementary role of 123/131I-MIBG imaging and CT in the location of pheochromocytomas. A flow-chart essentially grounded on the combined use of both these diagnostic modalities is proposed which includes 123/131I-MIBG scintigraphy as a first choice examination.

Scintigraphic localization of a disseminated malignant pheochromocytoma with the use of 131I-meta-iodobenzylguanidine.

Preliminary clinical studies with 131I-meta-iodobenzylguanidine, a newly synthesized radiopharmaceutical and guanethidine analog capable of imaging the adrenal medulla, have led to the identification of a case of disseminated malignant pheochromocytoma with the localization of brain and bone metastases. The result is of particular interest as the symptomatology in this case appeared rather equivocal and various investigations had led to a completely different diagnosis. This new scintigraphic technique has proved to be safe, specific and noninvasive, and it may have a clinical application as a complementary or alternative technique to conventional diagnostic tests.

Radioisotopic study of the adrenal glands using 131I-19-iodocholesterol.

Scintigraphy of the adrenal gland with 131I-19-iodocholesterol has recently been added to radiological techniques in adrenal imaging and has been used successfully to demonstrate anatomical and functional disorders of the adrenals in a variety of clinical situations. A review of the authors' experience stresses the diagnostic value of this method. Radiological findings and results of scintillation imaging are complementary: their comparison improves and clarifes indications for scintigraphy. Hyperadrenal cortical diseases always gave satisfactory scintigrams, the most interesting results being obtained in adrenal cortical hyperplasia and unilateral hyperfunctioning adenomas. In these cases the evaluation of the response to stimulation or suppression tests was very useful. On the other hand scintigraphy was less valuable in demonstrating malignant and non malignant tumours.