Quantitative estimation of the right ventricular overloading by thallium-201 myocardial scintigraphy

Right and left ventricular uptake with Rb-82 PET myocardial perfusion imaging: markers of left main or 3 vessel disease

BACKGROUND

Relative myocardial perfusion imaging may underestimate severity of coronary disease (CAD), particularly in cases of balanced ischemia. Can quantification of peak left (LV) and right (RV) ventricular Rb-82 uptake measurements identify patients with left main or 3 vessel disease?

METHODS

Patients (N = 169) who underwent Rb-82 PET MPI and coronary angiography were categorized as having no significant coronary stenosis (n = 60), 1 or 2 vessel disease (n = 81), or left main disease/3 vessel disease (n = 28), based on angiography. Maximal LV and RV ventricular myocardial Rb-82 uptake was measured during stress and rest.

RESULTS

Failure to augment LV uptake by >or= 8500 Bq/cc at stress, predicted left main or 3 vessel disease with a sensitivity of 93% and specificity of 61% (area under curve = 0.83). A >or=10% increase in RV: LV uptake ratios with stress over rest was 93% specific (area under curve = 0.74) for left main or 3 vessel disease. These indices incrementally predicted left main or 3 vessel disease compared to models including age, gender, cardiac risk factors, and summed stress and difference scores.

CONCLUSION

Quantifying maximal rest and stress LV and RV uptake with PET myocardial perfusion imaging may independently and incrementally identify patients with left main or 3 vessel disease.

Use of [123I]-BMIPP myocardial scintigraphy for the clinical evaluation of a fatty-acid metabolism disorder of the right ventricle in chronic respiratory and pulmonary vascular disease

The objective of this study was to evaluate whether or not right ventricle (RV) uptake of iodine-123-labelled-beta-methyliodophenylpentadecanoic acid ([123I]-BMIPP) correlated with the degree of right ventricular pressure overload (RVPO). Myocardial scintigraphy of [123I]-BMIPP and thallium-201 (201Tl) was performed on 46 patients with RVPO. We determined the right ventricle (RV)/left ventricle (LV) ratio = (radioactivities of RV)/(radioactivities of LV), and the RV metabolic index (RVMI) = (RV/LV ratio of [123I]-BMIPP)/(RV/LV ratio of 201Tl). We also evaluated the correlation between RVMI and mean pulmonary arterial pressure (mPAP), and between RVMI and total pulmonary resistance (TPR). Significant correlations were found between the RV/LV ratio of [123I]-BMIPP and mPAP and between the RV/LV ratio of [123I]-BMIPP and TPR. In addition, a significant negative correlation was observed between RVMI and mPAP and between RVMI and TPR. RVMI declined as RVPO increased, suggesting the presence of a fatty-acid metabolism disorder of the RV. Moreover, [123I]-BMIPP myocardial scintigraphy could be useful for evaluating a disorder of the fatty-acid metabolism of the RV with RVPO.

Evaluation of cor pulmonale on a modified short-axis section of the heart by magnetic resonance imaging

Magnetic resonance imaging (MRI) of a modified short-axis section of the heart, in 36 patients with chronic pulmonary diseases, consisting of 19 patients with pulmonary hypertension (PH group; mean pulmonary arterial pressure > or = 20 mm Hg) and 17 patients without pulmonary hypertension (non-PH group) was evaluated to study the configuration of the right ventricle. Parameters of right ventricular hypertrophy, including right ventricular wall thickness (RVWT) and the ratio of RVWT to left ventricular posterior wall thickness (RVWT/LVPWT), with this method were significantly larger in the PH group than in the non-PH group (p < 0.01). RVWT and RVWT/LVPWT correlated well with mean pulmonary arterial pressure (r = 0.90, p < 0.001 and r = 0.89, p < 0.001), total pulmonary resistance (TPR; r = 0.88, p < 0.001 and r = 0.85, p < 0.001), and pulmonary arteriolar resistance (PAR; r = 0.83, p < 0.001 and r = 0.81, p < 0.001). This method of setting a patient in a supine position and slicing with single-oblique sections may seem overly simple compared with Dinsmore's double-oblique short-axis section of the heart, but it is more convenient in practice. These results suggest that a modified short-axis section of the heart by MRI provides valid clinical configurational information concerning the right ventricle on which to base a noninvasive diagnosis of cor pulmonale.