ABSTRACT
OBJECTIVES: Conventional methods of imaging neuroendocrine tumors with computed tomography, magnetic resonance imaging, indium-111-octreotide, or radiolabeled metaiodobenzilguanidine scintigraphy have limitations. This pilot study tried to improve the localization of these tumors with fluorine-18-fluorodihydroxyphenylalanine (F-DOPA) positron-emission tomography (PET) scanning. MATERIALS AND METHODS: We studied 22 patients, the majority of whom were referred with clinical diagnosis or suspicion of carcinoid (n = 11), neuroendocrine tumors (n = 7) or pheochromocytoma/paraganglioma (PGL) (n = 4). The comparison was made with the prior conventional imaging. RESULTS: The F-DOPA findings were compared with the results of subsequent surgery (2), endoscopy (1), or a long-term follow-up (mean duration, 49 months) for 17 patients. Two patients were lost to follow-up. Foci of F-DOPA deposition were detected in eight patients (final diagnosis of carcinoid in six, of neuroendocrine tumors in one, and of PGL in another). Comparison with the final diagnoses revealed concordance in 16 of the 22 patients. F-DOPA results appeared superior to those obtained with conventional imaging. Despite the small number and diagnostic heterogeneity, in a substantial fraction of patients F-DOPA PET added information relevant to clinical management. CONCLUSION: F-DOPA scanning added prognostic value, particularly when multiple abnormal foci versus a negative examination were considered.
ABSTRACT
PURPOSE: To determine whether the perfusion index (PI) can be used as a noninvasive measure to diagnose and predict the severity of disease in patients with pulmonary arterial hypertension (PAH). MATERIALS AND METHODS: Twenty-two patients were included in this retrospective investigation: 9 controls and 13 patients with PAH. Controls had no evidence of PAH [mean pulmonary arterial pressure (MPAP) ≤25 mm Hg and pulmonary capillary wedge pressure ≤18 mm Hg]. The study patients had PAH (MPAP ≥25 mm Hg and pulmonary capillary wedge pressure ≤18 mm Hg) and no diagnosis of pulmonary embolism. Due to the retrospective nature of the study, the PI was calculated from the posterior perfusion image of a ventilation perfusion scan. The PI was computed as the sum of differences versus control for the 9 deciles above background. Receiver operating characteristic curve analysis was used to compare PI with other parameters for predicting PAH. RESULTS: Linear correlations of PI were found to be significant with the following parameters: pulmonary vascular resistance (r=0.81, P=0.00009), total pulmonary vascular resistance (MPAP/cardiac output) (r=0.80, P=0.00013), pulmonary artery systolic pressure (r=0.73, P=0.00018), MPAP (r=0.72, P=0.00022), pulmonary diastolic pressure (r=0.53, P=0.01), and right atrial pressure (r=0.50, P=0.03). Using logistic regression, the PI was significant in separating patients with PAH from controls (χ²=5.6, P=0.02). CONCLUSION: The data suggest that PI can be used for the noninvasive diagnosis and measurement of severity of PAH.
