Page 113 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt
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volumes are subtracted from the end-diastolic volumes yielding stroke volumes. From the contours of epicardial and endocardial tracings, ventricular wall volume is derived and wall mass is the product of myocardial volume and muscle density (1.05 g/cm3). From the volume changes of the RV over time, parameters of systolic and diastolic function can be derived [4, 6, 7]. Previously, post processing was time consuming since all the contours were drawn manually, but new software solutions make a semiautomatic analysis possible.
The accuracy and inter-study reproducibility of volume measurements using semiautomatic analysis has been validated in several reports [5, 8-11] and appears to be superior to echocardiography [12]. Another advantage of MRI-based ventricular measurements is that this technique does not require geometric assumptions and can also be assessed in subset of patients difficult to study by means of echocardiography, such as is the case in COPD [13]. Bottini et al. showed that estimates of RV mass measured by MRI acquired pre-mortem in COPD patients corresponds closely with RV mass measured at autopsy [14].
Figure 2: Long axis view of a healthy subject (A) and a patient with severe pulmonary arterial hypertension. RV = right ventricle, LV = left ventricle, PE= Pleural effusion, TI= tricuspid regurgitation.
The clinical value of the different MRI parameters in PH has been assessed in several studies. Earlier MRI studies revealed that in PH, RV volumes at end-diastole and end-systole are increased together with an increase in RV mass, whereas LV end-diastolic volume and stroke volume are decreased [2, 3, 15, 16]. As a consequence, RV ejection fraction is decreased, whereas LV ejection fraction is preserved or even increased [6, 7, 17]. Figure 2 shows a long axis image of a healthy control and a
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