The Emerging Role of Magnetic Resonance Imaging in the Diagnosis and Management of Pulmonary Hypertension

Abstract

Pulmonary hypertension is a life-threatening chronic disorder of the pulmonary circulation. Elevated pressure and resistance in the pulmonary vessels lead to progressive right heart failure which results in functional limitations and ultimately the death of most patients. Thus, the monitoring of right ventricular (RV) function is of great importance. Cardiac magnetic resonance imaging (cardiac MRI) has several advantages over other imaging methods. The use of cine acquisition techniques allows precise description of characteristic volumetric and functional variables, such as right ventricular volumes, muscle mass, stroke volume, ejection fraction, or cardiac output. Impaired right ventricular contractility and function have also been assessed using measures like ventricular septal bowing and pressure-volume loops. MRI investigations have been performed to monitor medical treatment, and the improvement in well-established prognostic factors, such as the 6-min walk, were correlated with measures of right ventricular function. Flow-derived parameters of the pulmonary arteries (such as peak velocity, acceleration time and volume, or pulmonary flow profile) are available using velocity-encoded imaging, and may detect early signs of remodelling. Additionally, magnetic resonance angiography is a promising new tool to visualise pulmonary perfusion and to diagnose chronic thromboembolic pulmonary hypertension. The purpose of this review is to summarise recent advances of cardiovascular magnetic resonance imaging, which will play an increasing role in the comprehensive diagnostic work-up of patients with pulmonary hypertension as a tool to monitor the course of the disease and to evaluate new therapeutic approaches.

The role of the right ventricle in pulmonary arterial hypertension

“…CMRI allows for the visualisation and measurement of complex threedimensional geometry and it is therefore particularly suited to the complex morphology of the right ventricle. Precise, noninvasive assessment of cardiac volumes and function is possible, without the need for geometric approximations, while assessments such as flow measurements in the heart and great vessels using techniques such as cine phase-contrast provide more comprehensive data on cardiac function than ECHO [43,50,51]. However, in comparison with ECHO, CMRI is expensive and not widely available.…”

“…The need for breath holding may be a problem in patients with PAH and claustrophobia when using smaller diameter magnets can be problematic for some, although these problems are decreasing with improving technology. In addition, the use of magnetic resonance imaging is incompatible with ferromagnetic objects such as pacemakers and defibrillators, and infusion pumps, which could also limit its use in some patients [43,50,51].…”

Assessment of Patients with Pulmonary Hypertension

“…MRI has potential advantages in this respect, in that additional diagnostic The assessment of PH, then, requires a number of investigational and imaging modalities to fully define the nature and severity of the disease, including an invasive assessment of RV function, which is the main determinant of survival in these patients. In this issue of Respiration , Kovacs et al [4] critically look at the role of MRI in the assessment of PH, and in particular at its pivotal role in the accurate assessment of RV anatomy and function. By providing a comparison with the more traditional assessment techniques, they also provide a cogent rationale for the increasing reliance on this technique in clinical practice.…”

The Use of Contrast-Enhancement Cardiovascular Magnetic Resonance Imaging in Cardiomyopathies

“…Pulmonary arterial hypertension, both primary and secondary, is characterized by an increased pulmonary vascular resistance that results in pressure overload on the right ventricle (Kovacs et al, 2008). Cine CMR permits accurate assessment of right ventricular mass and volumes which is often difficult to accomplish with other imaging modalities (Marcu et al, 2007).…”