Primary extra-adrenal pheochromocytoma: positive I-123 MIBG imaging with negative I-131 MIBG imaging

I-131 metaiodobenzylguanidine (I-131 MIBG) is a well established imaging agent that reliably detects pheochromocytoma. In some patients, however, I-131 MIBG may fail to localize pheochromocytoma. I-123 MIBG has several potential advantages over I-131 MIBG, and these advantages may enable locating pheochromocytomas which have eluded other techniques, including I-131 MIBG imaging. A patient with primary extra-adrenal pheochromocytoma is described who illustrates the superiority of I-123 MIBG for the imaging of pheochromocytoma.     

I-123 MIBG cardiac imaging in diabetic neuropathy before and after epalrestat therapy.

I-123 metaiodobenzylguanidine (MIBG) scintigraphy is a new method to evaluate cardiac sympathetic nerve disturbance in patients with diabetes mellitus. Epalrestat specifically inhibits aldose reductase and improves diabetic neuropathy. The authors report a case of improvement in cardiac sympathetic dysfunction using MIBG scintigraphy with epalrestat therapy. In this case, epalrestat effectively reversed diabetic neuropathy, and MIBG scintigraphy was useful to evaluate the effect of epalrestat.     

Estimation of I-123 metaiodobenzylguanidine (MIBG) myocardial washout

A crosstalk from I-123 to Tl-201 (Tl) window was 35 +/- 30% (mean +/- SD) and 30 +/- 10% in a myocardial phantom and the images of 6 patients respectively. However, the crosstalk from Tl to I-123 was approximately 1% in each. I-123 MIBG (MIBG) and Tl myocardial SPECT images were recorded in 3 normal volunteers (N), 10 patients with myocardial infarction (MI), and 4 with dilated cardiomyopathy (DCM). The MIBG and Tl imagings were performed on the other day to avoid the crosstalk. Myocardial washout rates (WR) of Tl and MIBG were derived from 15 min and 4 hour images. WR of Tl was approximately 36% in each group. On the other hand, WR of MIBG in DCM (52 +/- 7%) and MI (41 +/- 14%) groups were statistically higher than in N (24 +/- 7%) group. Thus WR of MIBG would be useful to detect abnormalities in adrenergic nervous system.     

I-123 MIBG scintigraphy in idiopathic dilated cardiomyopathy: Where next?

Conclusion  The study of Parthenakis et al4 represents a step toward further documenting the relationship between myocardial blood flow, left ventricular wall motion, and presynaptic sympathetic neuronal function in the disease process of idiopathic dilated cardiomyopathy. However, more questions remain to be answered. With a large future increase predicted in the number of patients developing congestive heart failure, perhaps it is time for carefully planned imaging studies to be incorporated into new clinical trials of medical therapies for heart failure. These may provide further important information concerning the utility of quantitative MIBG imaging in assessing pathophysiology, approaches to medical therapy, and prediction of prognosis in patients with idiopathic dilated cardiomyopathy.     

Unusual Tc-99m MDP and I-123 MIBG images in focal pyelonephritis

A 6-year-old boy presented with an inflammatory syndrome. Because Tc-99m MDP bone scintigraphy revealed increased tracer uptake at the upper pole of the right kidney, further studies were oriented towards a diagnosis of renal or adrenal pathology. I-123 metaiodobenzylguanidine (MIBG) accumulated at the site of the abnormal MDP uptake. The diagnosis of neuroblastoma or allied disorder was excluded on the basis of other investigations and further evaluation, suggesting that the MIBG uptake was a false-positive. Findings on clinical imaging, laboratory findings, Tc-99m DMSA imaging, sonography, and CT scanning were highly suggestive of acute focal pyelonephritis.     

Doxorubicin cardiotoxicity: Prevention of congestive heart failure with serial cardiac function monitoring with equilibrium radionuclide angiocardiography in the current era

BACKGROUND: Congestive heart failure (CHF) is among the most serious toxicities of doxorubicin, a potent cancer chemotherapeutic agent. Serial left ventricular ejection fraction (LVEF) monitoring during doxorubicin therapy for preventing CHF was proposed over 20 years ago. The current utility and cost-effectiveness of this approach in the present era are not known. METHODS AND RESULTS: Clinical and follow-up data of 265 patients with cancer (age, 53 +/- 14 years; 76% women) undergoing doxorubicin chemotherapy with serial equilibrium radionuclide angiocardiography (ERNA) monitoring (> or =2 studies) were analyzed retrospectively. Patients with a normal baseline LVEF (> or =50%) and a 10% or greater point fall in LVEF to a final value of less than 50% during doxorubicin therapy were considered "at risk" for CHF (n = 41). Over 679 +/- 426 days of follow-up, 7 patients (2.6%) had CHF develop and 90 (34%) died (all cancer-related deaths, with none due to CHF). A comparison of "at-risk" (n = 41 [15%]) and "low-risk" (n = 224 [85%]) groups showed a higher incidence of CHF (12% vs 0.9%, P <.0001), lower baseline LVEF (58% +/- 8% vs 64% +/- 8%, P <.0001), lower value for the lowest LVEF (42% +/- 8% vs 57% +/- 7%, P <.0001), and higher rate of cancer-related deaths (59% vs 29%, P =.0003) in the former despite similar cumulative doxorubicin dose (304 +/- 124 mg/m(2) vs 284 +/- 110 mg/m(2), P = not significant). There were no differences in age, gender, cancer type, and co-morbidity. Cost analysis showed the overall cost of ERNA studies to be lower than the 1-year cost of caring for additional cases of CHF that would potentially be prevented by routine LVEF monitoring. CONCLUSIONS: An incipient fall in LVEF detected on serial ERNA during doxorubicin therapy provides an appropriate and cost-effective approach for predicting and preventing impending CHF. Use of this approach was associated with a low incidence of CHF (2.6%) and no CHF-related mortality in this study.     

I-123 MIBG imaging and intraoperative localization of metastatic pheochromocytoma: a case report

The authors describe the diagnostic use of I-123 MIBG scintigraphy in a 61-year-old man who was thought to have a recurrence 25 years after a left adrenalectomy for a pheochromocytoma. Preoperative I-123 MIBG scintigraphy was performed twice along with intraoperative gamma probe localization of the lesions. The preoperative MIBG scintigraphy revealed three pathologic processes in the upper left abdomen, whereas computed tomographic scanning identified only one site of involvement. All three metastatic lesions were removed successfully with the aid of a gamma probe. Preoperative I-123 MIBG scintigraphy, combined with intraoperative gamma probe identification of I-123 MIBG foci, is feasible and a valuable tool to detect malignant masses possibly overlooked by other imaging techniques.     

Compensatory uptake of I-123 MIBG in the contralateral adrenal gland after removal of a pheochromocytoma.

The identification of recurrent or residual tumor tissue is sometimes complicated. The authors describe a 53-year-old woman in whom I-123 metaiodobenzylguanidine (MIBG) scintigraphy revealed a pheochromocytoma in the right adrenal gland. After the tumor was removed, the patient's catecholamine levels normalized. At the 3-month follow-up examination, I-123 MIBG scintigraphy did not reveal uptake in the right adrenal region but rather showed uptake in the left adrenal region. The patient's blood pressure remained in the normal range. A third scintigram, obtained 1 year after tumor resection, no longer detected I-123 MIBG accumulation in the left adrenal gland. These findings suggest that compensatory hyperplasia of the left adrenal gland led to enhanced uptake of I-123 MIBG. They also highlight the need for careful follow-up of such patients to distinguish between physiologic and pathologic processes.     

Pheochromocytoma and the normal adrenal medulla: improved visualization with I-123 MIBG scintigraphy

The radiopharmaceutical iodine 131 metaiodobenzylguanidine (I-131 MIBG) has been shown to locate pheochromocytomas scintigraphically with a false-negative rate of approximately 13%. To improve image quality and reduce the false-negative rate, I-123 was examined as a radioactive label for MIBG, as it has many advantages over I-131, including superior dosimetry and better detection efficiency. Diagnostic doses of 0.5 mCi (18.5 MBq) I-131 MIBG and 10.0 mCi (370.0 MBq) I-123 MIBG with nearly equivalent radiation dosimetries were compared in 18 patients with known or suspected pheochromocytomas. Images of superior quality were obtained with I-123 MIBG in 18 of 18 patients, and in eight cases lesions not visualized on I-131 MIBG scintigraphy were portrayed. A further advantage of I-123 MIBG is that it permits single photon emission computed tomography (SPECT). This was performed in six cases and provided additional information in three cases. The adrenal medullae were definitely visualized using I-123 scintigraphy in eight of 14 patients still possessing adrenal glands, whereas I-131 MIBG images portrayed the adrenal medulla in only one of 14 cases. Five remaining patients had multiple abdominal tumor deposits that were difficult to differentiate from normal adrenal medullae.