A review of imaging modalities in pulmonary hypertension

Abstract

Pulmonary hypertension (PH) is defined as resting mean pulmonary artery pressure ≥25 mmHg measured by right heart catheterization. PH is a progressive, life-threatening disease with a variety of etiologies. Swift and accurate diagnosis of PH and appropriate classification in etiologic group will allow for earlier treatment and improved outcomes. A number of imaging tools are utilized in the evaluation of PH, such as chest X-ray, computed tomography (CT), ventilation/perfusion (V/Q) scan, and cardiac magnetic resonance imaging. Newer imaging tools such as dual-energy CT and single-photon emission computed tomography/computed tomography V/Q scanning have also emerged; however, their place in the diagnostic evaluation of PH remains to be determined. In general, each imaging technique provides incremental information, with varying degrees of sensitivity and specificity, which helps suspect the presence and identify the etiology of PH. The present study aims to provide a comprehensive review of the utility, advantages, and shortcomings of the imaging modalities that may be used to evaluate patients with PH.

Keywords: Imaging; pulmonary hypertension; pulmonary vasculature; review; right ventricle.

Figure 1

Two-dimensional echocardiogram in a patient with idiopathic pulmonary arterial hypertension. (a) The apical 4-chamber view shows large right heart chambers with hypertrophy of the right ventricle. (b) The short parasternal view with enlarged right ventricle leading to interventricular septal displacement into the left ventricle. The black arrow points toward a small pericardial effusion. LA = left atrium, LV = Left ventricle, RA = right atrium, RV = right ventricle

Figure 2

Chest X-ray in a patient with idiopathic pulmonary arterial hypertension. (a) Posteroanterior projection showing dilated pulmonary arteries (stars), cardiomegaly (horizontal line), and rapid tapering (pruning) of right pulmonary artery (arrow). In addition, there is a decrease in the pulmonary vasculature in the periphery of the lung (arrow). (b) Lateral projection depicting a decrease in the retrosternal air space (arrow)

Figure 3

Computed tomographic pulmonary angiography in a patient with idiopathic pulmonary arterial hypertension. Upper panel shows dilated pulmonary artery (star) and pericardial effusion (arrow). Center panel reveals a dilated right ventricle (star) with displacement of the interventricular septum toward the left ventricle and pericardial effusion (arrow). Lower panel shows iodine contrast in the inferior vena cava (short arrow) and pericardial effusion (long arrow)

Figure 4

Ventilation perfusion scan and computed tomography angiography in a patient with pulmonary hypertension due to fibrosing mediastinitis and absent flow to the right lung. (a) The lack of perfusion on the right lung. (b) An obstruction of the right main pulmonary artery (white arrow) due to fibrosing mediastinitis. Note the calcified adenopathies and fibrotic tissue. L = left lung, PA = pulmonary artery, R = right lung

Figure 5

Magnetic resonance imaging in a patient with sinus venosus atrial septal defect and partial anomalous pulmonary venous return. (a and b) Images from a steady state free precession cine 4-chambered stack show the superior sinus venosus defect (arrow). There is severe dilation of the right-sided chambers. (c and d) Reconstructed images from magnetic resonance angiography show dilation of the central pulmonary arteries. The patient had a significant left-to-right shunt with Qp/Qs of 3.6. RV = Right ventricle, RA = right atrium, PA = Pulmonary artery

Figure 6

Magnetic resonance imaging in a 67 male patient with long-standing severe pulmonary hypertension. Axial postgadolinium VIBE (volume interpolated breath-hold) image shows aneurysmal pulmonary arteries with layered in situ thrombus in left lower lobar pulmonary artery (arrow). Cine steady-state free precession 4-chamber supplementary video clip shows massively enlarged bilateral pulmonary arteries with layered in situ thrombus. There is associated right ventricle enlargement and right ventricular hypertrophy. The right ventricle systolic function was moderately depressed (ejection fraction-40%). Cine steady-state free precession nicely depicts the swirling of blood within the pulmonary arteries, reflecting sluggish flow. Also seen is mild tricuspid regurgitation

Figure 7

Pulmonary angiogram in a patient with chronic thromboembolic pulmonary hypertension and 50% chronic obstruction of the right main pulmonary artery. The black arrow points toward the narrowing of the right pulmonary artery. Note the diameter difference between the right and left main pulmonary arteries

Figure 8

Representative normal SPECT-CT image. The top two panels show perfusion images while bottom two images show ventilation. SPECT-CT allows better mapping of perfusion defects to the appropriate lung segments. SPECT-CT = Single-photon emission computed tomography/computed tomography

Figure 9

Dual-energy computed tomography in a patient with chronic thromboembolic pulmonary hypertension. (a) Pouch sign on the right upper pulmonary artery on a pulmonary angiogram and corresponding defect on the dual-energy computed tomography image. (b) Fused-perfused blood volume images generated by fusion of the anatomic and perfused blood volume datasets. This allows correlating anatomic and functional information. The pouch defect is again seen with corresponding wedge-shaped perfusion defect

Figure 10

Fused lung vessel and perfused blood volume map image in a patient with acute pulmonary embolism. The vessels containing iodine are coded blue. The subsegmental branch with acute PE is highlighted easily on the lung vessel map, which can be fused on perfused blood volume maps