Diagnostic Efficacy of Biochemical Studies and MIBG Scan in Pheochromocytoma / 대한비뇨기과학회지

We evaluated the role of clinical symptoms, biochemical studies and metaiodobenzylguanidine (MIBG) scan in the diagnosis of pheochromocytoma. From August 1991 to June 1997, 42 patients with complaints of hypertension or adrenal mass were evaluated with MIBG scan, 24 hour urinary vanillylmandelic acid (VMA), serum and 24 hour urinary catecholamine and radiologic studies such as CT, MRI or ultrasonography. Initial 9 patients were evaluated with 131 I-MIBG scan and the rest 33 patients with 123 I-MIBG scan. Of 42 patients, histologic diagnosis was obtained in 32 patients including 23 patients with pheochromocytoma or paraganglioma and 9 patients with other adrenal or extra-adrenal tumors. Remaining 10 patients had no evidence of adrenal disease on radiologic studies. Paroxysmal symptoms or hypertension was noted in 14 patients with pheochromocytoma or paraganglioma, while it was also found in 12 out of 19 patients without pheochromocytoma or paraganglioma. Sensitivity, specificity and positive predictive value (PPV) of each diagnostic modality were 60.9%, 92.9% and 93.3% in 24 hour urinary VMA, 61.9%, 75.0%, and 81.3% in 24 hour urinary catecholamine, 82.6%, 94.7%, and 95.0% in MIBG scan, respectively. Sensitivity and specificity were improved to 86.9% and 100% when 24 hour urinary VMA and MIBG scan were combined. In conclusion, MIBG scan was the most useful single screening method for the diagnosis of pheochromocytoma, and combination of MIBG scan and 24 hour urinary VMA would enhance the diagnostic accuracy.

Iodine-123-Metaiodobenzylguanidine Myocardial Scintigraphy in Patients with Dilated Cardiomyopathy : Correlation between Myocardial MIBG Uptake and Echocardiographic Parameters

BACKGROUND: The prognosis of patients with dilated cardiomyopathy remains poor. Doppler echocardiography and cardiac iodine-123-metaiodobenzylguanidine(MIBG) myocardial scintigraphy are useful non-invasive diagnostic modalities to assess the prognosis in these patients. However, the relationship between myocardial MIBG uptake and Doppler echocardiographic. variables was not well investigated. We analyzed the cardiac MIBG imaging in 40 patients with dilated cardiomyopathy and assessed the correlation between the echocardiographic parameters and myocardial MIBG uptake. MIBG uptake(DHM), assessed as the heart/mediastinum ratio measured on anterior view image obtained 4 hours after injection, was compared with M-mode(left ventricular end-diastolic dimension, left ventricular ejection fraction) and Doppler parameters. RESULTS: 1) Early and delayed MIBG uptake of heart were significantly lower in patient group compared with normal control subjects. There were no significant differences in lung and mediastinum uptake of MIBG between the two groups. 2) Early and delayed MIBG uptake ratios of the heart to lung and heart to mediastinum were significantly lower in patient group compared with those of normal control subjects. 3) DHM was significantly lower in patients with NYHA functional class 3, 4 than those with NYHA functional class 1, 2 in patient group. There was, however, no significant difference of DHM in patient group divided by the degree of mitral regurgitation and left ventricular diastolic filling pattern. 4) There were no significant correlations between DHM and other prognostic factors(left ventricular end-diastolic dimension, left ventricular ejection fraction, peak velocity of early diastolic filling(E velocity), deceleration time of E wave, cardiac output, pulmonary capillary wedge pressure, left ventricular end-diastolic pressure and 24hr urine norepinephrine). CONCLUSION: Iodine-123-MIBG scan is a useful noninvasive imaging modality in the assessment of cardiac sympathetic neuronal integrity in patients with dilated cardiomyopathy. There were no significant correlations between cardiac MIBG uptake and other prognostic factors. The cardiac MIBG uptake probably can be utilized as an independent prognostic factor, hence it would be suggested that a large prospective clinical study is needed to consolidate these findings.