Imaging in Chronic Thromboembolic Pulmonary Hypertension

Abstract

Chronic thromboembolic pulmonary hypertension (CTEPH) is one of the potentially curable causes of pulmonary hypertension and is definitively treated with pulmonary thromboendartectomy. CTEPH can be overlooked, as its symptoms are nonspecific and can be mimicked by a wide range of diseases that can cause pulmonary hypertension. Early diagnosis of CTEPH and prompt evaluation for surgical candidacy are paramount factors in determining future outcomes. Imaging plays a central role in the diagnosis of CTEPH and patient selection for pulmonary thromboendartectomy and balloon pulmonary angioplasty. Currently, various imaging tools are used in concert, with techniques such as computed tomography (CT) and conventional pulmonary angiography providing detailed structural information, tests such as ventilation-perfusion (V/Q) scanning providing functional data, and magnetic resonance imaging providing a combination of morphologic and functional information. Emerging techniques such as dual-energy CT and single photon emission computed tomography-CT V/Q scanning promise to provide both anatomic and functional information in a single test and may change the way we image these patients in the near future. In this review, we discuss the roles of various imaging techniques and discuss their merits, limitations, and relative strengths in depicting the structural and functional changes of CTEPH. We also explore newer imaging techniques and the potential value they may offer.

Chronic pulmonary embolism: diagnosis

“…Several studies have shown substantial correlation between lung iodine density and perfusion, with comparable results to V/Q scans (82)(83)(84)(85). To date, DECT role in thoracic imaging has mainly targeted at pulmonary embolic disease and PAH (61,(86)(87)(88).…”

“…In mosaic perfusion, decreased attenuation is secondary to hypoperfusion distal to the occluded/suboccluded arteries, whereas increased attenuation is related to redistribution of blood flow to patent vessels. In areas of increased attenuation, larger vessels and stronger enhancement after contrast material administration can be seen (60,61,74) (Figure 8). Although more commonly seen in patients with CTEPH, mosaic lung attenuation is nonspecific, and may be also seen in patients with PH due to cardiac or lung disease (75).…”

“…Main features of CTEPH on CTPA include occlusive or non-occlusive filling defects in the pulmonary arteries (60,61). Vessel cutoff, abrupt decrease in vessel diameter and absence of contrast enhancement distal to the obstruction are features suggestive of occlusive CTEPH (Figure 4).…”

Acute pulmonary embolism multimodality imaging prior to endovascular therapy

“…Bands are linear structures that run along the long axis of a vessel and may appear in the setting of chronic PE. Webs are networks of bands that are often found at vessel bifurcations in chronic PE and are associated with distal neovasculature [13,92,93].…”

Diagnostic accuracy of CT pulmonary angiography in suspected pulmonary hypertension

“…Computed tomography has been seen to have several technological advances over the last three decades, and the introduction of iterative reconstruction CT algorithms has led to a significant reduction in image noise and radiation dose [16]. CT is frequently used in the evaluation of breathlessness and in the assessment of lung and increasingly cardiac disease [17][18][19][20][21][22][23][24]. The majority of studies using CT as a diagnostic tool have concentrated primarily on pulmonary artery size.…”