Many patients with Parkinson disease-including all those with sympathetic neurocirculatory failure-have evidence of cardiac sympathetic denervation. This suggests that loss of catecholamine innervation in Parkinson disease occurs in the nigrostriatal system in the brain and in the sympathetic nervous system in the heart

Abstract-The diagnosis and treatment of pheochromocytoma depend critically on effective means to localize the tumor.Computed tomography and magnetic resonance imaging have good sensitivity but poor specificity for detecting pheochromocytoma, and nuclear imaging approaches such as 131 I-metaiodobenzylguanidine scintigraphy have limited sensitivity. Here we report initial results using 6-[18 F]fluorodopamine positron emission tomography (PET) scanning in the diagnostic localization of pheochromocytoma. Twenty-eight patients with known or clinically suspected pheochromocytoma underwent PET scanning after intravenous injection of 6-[18 F]fluorodopamine. Of the 28 patients, 9 had surgical confirmation of the tumor, 8 had previously diagnosed metastatic pheochromocytoma, and 11 had plasma levels of metanephrines that were within normal limits. All 9 patients with surgically proven pheochromocytoma had abnormal 6-[18 F]fluorodopamine PET scans that identified the tumors. All 8 patients with metastatic pheochromocytoma had extra-adrenal sites of 6-[18 F]fluorodopamine-derived activity. Of the 11 patients with normal plasma levels of metanephrines, 9 had negative 6-[18 F]fluorodopamine PET scans, 1 had extra-adrenal foci of 6-[ 18 F]fluorodopaminederived activity, and 1 had symmetric uptake of 6-[18 F]fluorodopamine in the region of the adrenal glands. In patients with known disease, 6-[18 F]fluorodopamine PET scanning can detect and localize pheochromocytomas with high sensitivity. In patients in whom the diagnosis of pheochromocytoma is considered but excluded because of negative plasma metanephrine results, 6-[ Key Words: fluorodopamine Ⅲ pheochromocytoma Ⅲ positron emission tomography Ⅲ metanephrines P heochromocytoma is a rare but clinically important tumor of chromaffin cells, 1 characterized by production and secretion of catecholamines and often-but not alwayshypertension. Most pheochromocytomas are benign, so that pheochromocytoma constitutes a form of surgically curable hypertension, and failure to diagnose the tumor can result in sudden, unexpected, and potentially lethal complications. Therefore, clinicians often wish to evaluate patients for pheochromocytoma, when hypertension and symptoms or signs suggest catecholamine excess.Ideally, the diagnosis of pheochromocytoma using imaging techniques requires specific localization in tumor with a high sensitivity for tumor detection. Computed tomography (CT) and magnetic resonance imaging (MRI) have good sensitivity but poor specificity, 2,3 and commonly available nuclear imaging modalities such as 131 I-metaiodobenzylguanidine scintigraphy have high specificity but limited sensitivity. 4 -8 Positron emission tomographic (PET) scanning is a physiology-based method of imaging, dependent on selective-binding or uptake and retention of radiopharmaceuticals by different tissues. The use of short-lived positronemitting radionuclides allows administration of large tracer doses, resulting in high count density and superior resolution compared with that of single photon ...

Parkinson's disease patients frequently have symptoms and signs of autonomic nervous dysfunction that are the source of considerable disability. Recent studies have revealed that most patients with Parkinson's disease, and all with Parkinson's disease-associated orthostatic hypotension, have a loss of cardiac sympathetic innervation. Familial Parkinson's disease, caused by mutation of the gene encoding alpha-synuclein, also features orthostatic hypotension, sympathetic neurocirculatory failure and cardiac sympathetic denervation. We have recently described a whole-gene triplication of alpha-synuclein causing Lewy body parkinsonism in a large, well characterized family called the 'Iowa kindred'. Here we report the results of cardiac PET scanning using the sympathoneural imaging agent, 6-[18F]fluorodopamine in affected and unaffected members of this kindred. Four family members were studied, two with parkinsonism, one clinically normal and one with benign essential tremor alone. Both affected members had obvious loss of cardiac sympathetic innervation; the unaffected member had normal innervation, as did the member with isolated essential tremor. The results indicate that, in this family, where disease is caused by overexpression of normal alpha-synuclein, cardiac sympathetic denervation cosegregates with parkinsonism. Post-mortem studies have demonstrated synuclein-positive Lewy body formation in the brains of individuals with parkinsonism who were also in the family described here and who also carry this triplication. These results indicate that both parkinsonism and cardiac sympathetic denervation can result from an excess of normal synuclein.