Treatment of malignant pheochromocytoma with [131I]metaiodobenzylguanidine: a French multicenter study.

Six Medical Centers in France were involved in a prospective study evaluating the efficacy of [131I]metaiodobenzylguanidine (131I-MIBG) in the treatment of malignant pheochromocytoma. Fifteen patients aged from 28 to 75 years bearing tumor sites demonstrating a good MIBG uptake were included in this study. Catecholamines were elevated in 13/14 cases, VMA in 9/14 and metanephrines in 13/14. Two to 11 therapeutic activities of 131I-MIBG were administered, with a mean number of therapeutic doses per patient of 4 and a mean single activity of 4.7 GBq (range 2.9 to 9.25 GBq). Seven patients were alive, and seven patients died 6 to 29 months after their first MIBG administration (mean follow-up of 36 months); 1 patient was lost to follow-up. Two patients had a partial tumor response only, 4 had a hormonal response only, and 3 had both a partial tumor response and a hormonal response (complete in 2 cases). Six patients did not respond to the treatment, 4 of them died. Of the 9 responding patients, 4 relapsed, 3 of whom died subsequently. Haematological toxicity was always transient and mild, except in 1 case.

Use of m-[131I]iodobenzylguanidine in the treatment of malignant pheochromocytoma.

The efficacy and safety of m-[131I]iodobenzylguanidine ([131I]MIBG) were assessed in 15 patients with malignant pheochromocytomas in a nonrandomized, single arm trial, in which patients were treated with [131I]MIBG (SA, 740 megabequerel/mg) every 3 months. Seven of these patients had bone and soft tissue metastases, 4 had only soft metastases, and 4 had only bone metastases. The follow-up period ranged from 6-54 months; the number of doses ranged from 2-11, with 2.9 (78.4 mCi) to 9.25 gigabequerel (GBq) (250 mCi)/administration and a cumulative activity from 11.1-85.90 GBq (300-2322 mCi). The absorbed cumulative dose in tumors ranged from 12-155 Gy. A beneficial effect of the treatment was observed in 9 patients (60%). No complete remission of the disease was observed. Seven patients died during the study, among whom 4 never responded to the treatment. Seven had hormonal responses (4 complete and 3 partial), with a duration ranging from 5-48 months. Among these patients, 4 relapsed, and 3 died within 3 months. Five patients had partial tumoral responses mainly located in soft tissues and for a duration ranging from 29-54 months. All patients with a hormonal response had objective improvement in clinical status and blood pressure. There was no clear-cut relationship between the cumulative dose and the responses. The main side-effect observed in 1 patient with widespread bone metastases after three doses (12.9 GBq) was a pancytopenia, which resolved after treatment was discontinued. This study suggests that repeated [131I]MIBG treatment could be effective in patients with advanced malignant pheochromocytoma.

Low levels of serum thyroglobulin after withdrawal of thyroid suppression therapy in the follow up of differentiated thyroid carcinoma.

We evaluated the reliability of very low serum thyroglobulin (Tg) levels (less than 3 ng/ml) obtained after withdrawal of thyroid suppression therapy in 224 patients without anti-Tg antibodies, who had undergone total thyroidectomy (125 patients) or thyroidectomy followed by 1 or more courses of 131I therapy (99 patients), by performing whole body scans after a therapeutic course of 131I given at the same time of Tg measurement. In 79 patients (35%) a positive scan, associated with a very low level of Tg, was noted. The 131I uptake was limited to the thyroid bed in 60 patients, but metastases were demonstrated in 19 patients (8.5%). These results are mainly explained by the much improved performance of scintigraphy after administration of therapeutic doses of 131I. In the majority of patients, especially those whose 131I uptake was limited to the thyroid bed, further scans were negative. Therefore, in these cases, negative Tg values can generally be considered an early indication of satisfactory evolution. However, in 8.5% of all cases, very low Tg levels were associated with metastases. Thus the follow up of thyroid cancer should not rely only upon Tg determination, even after suppression therapy withdrawal.

Thallium-201 imaging in the follow-up of differentiated thyroid carcinoma.

Since thallium-201 imaging has been reported as a potential means of follow-up of patients with differentiated thyroid carcinoma (DTC) during ongoing thyroid suppression therapy, the authors evaluated the diagnostic sensitivity of this procedure in 31 patients known to have metastases or local recurrence. Among 51 tumor sites 201TI imaging had a detection rate of 45% whereas 84% was noted for imaging with 131I administered in therapeutic doses. Thus, even though the effectiveness of the two radionuclides is not strictly comparable due to the difference in the administered doses, Thallium imaging cannot be recommended as the only modality for the follow-up of patients with DTC. Six of the eight tumor sites negative with 131I were positive with 201TI (especially metastatic cervico-mediastinal lymph nodes). So 201TI imaging may particularly be helpful in localizing metastases or recurrences in patients with a negative 131I scan and abnormal levels of serum thyroglobulin.

[Treatment of malignant pheochromocytoma by 131-I-metaiodobenzylguanidine]. / Le traitement des phéochromocytomes malins par la 131-I-métaiodobenzylguanidine.

Twelve patients (2 with only bone metastases, 3 with only soft tissues metastases and 7 with bone and soft tissues metastases) were treated with 131-I-MIBG (specific activity: 20 mCi/mg), 100 to 200 mCi every 3-6 months. A dosimetric study was carried out before each administration. The follow-up ranged from 6 to 24 months and the number of doses ranged from 1 to 8, with 1.85-9 GBq per administration and a cumulative activity of 1.85-62. 2 GBq according to patients. The cumulative absorbed activity ranged from 850 to 9700 cGy. The following side effects were observed: a bone marrow hypoplasia (1 patient) and a transient increase in catecholamines (3 patients). The treatment was successful in 7 patients (3 with soft tissue metastases, 3 with bone and soft tissue metastases and one with bone metastases). This success consisted in clinical improvement and a decrease greater than 50% of hormonal values in the 7 patients and a decrease greater than 50% of tumoral masses in only 3 patients. No complete remission was obtained at this stage of the study. The disease recurred in 1 patient after a year of partial remission. There was no clear-cut relation between the number of doses and the results. This study shows that 131-I-MIBG can give encouraging though limited results.

Detection of anomalous systemic venous return and intraatrial baffle leakage by radionuclide angiocardiography.

The case presented here is a 27-year-old patient who was born with common atrium and left superior vena cava (LSVC). Construction of interatrial septum and intraatrial baffle with pericardium was performed 16 years ago. Radionuclide angiocardiography (RAC) showed that a substantial amount of blood flow from the LSVC was directed to the inferior vena cava through the hemiazygos vein (HAV). It also detected a baffle leak and a left to right shunt at the atrial level. Subsequent RAC after reoperation initially showed insignificant flow through the atrial baffle, major flow through the HAV, and no shunt. Repeat RAC one year after surgery showed increased flow through the baffle and diminished flow through the HAV, without a satisfying explanation. This case illustrates the value of RAC in detecting various types of cardiovascular abnormality and subtle hemodynamic changes.

Single photon emission computed tomography (SPECT), planar scintigraphy, and transmission computed tomography: a comparison of accuracy in diagnosing focal hepatic disease.

A prospective evaluation of conventional planar scintigraphy (PS), single photon emission computed tomography (SPECT), and transmission computed tomography (TCT) was performed in 98 patients with suspected focal hepatic disease (FHD). The three examinations were performed on the same day. TCT had slightly higher sensitivity (91%) and specificity (96%) than either PS or SPECT. The sensitivity and specificity of TCT was also higher than that of the combination of PS and SPECT, which was more accurate than either radionuclide technique alone, with a sensitivity of 85-87% and a specificity of 90%. These differences were not statistically significant. However, receiver operating characteristic (ROC) analysis showed that the performance of TCT was significantly better. The ROC curves also showed, without statistical significance, that SPECT appears to have better diagnostic accuracy than PS and that it seems desirable to complement SPECT imaging with PS views, to reduce the number of equivocal results.

Transient intense gastric fixation of 99mTc-MDP.

A case is described of reversible, intense gastric uptake of 99mTc-MDP in the fundal region of a patient with myeloma, while very little transient pulmonary fixation was seen. The significance of this unusual finding in terms of relevant blood chemistry, results of gastric biopsies, which failed to show metastatic calcification, and the drugs administered is discussed.