Imaging of Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) is an end result of a diverse array of complex clinical conditions that invoke hemodynamic and pathophysiological changes in the pulmonary vasculature. Many patients' symptoms begin with dyspnea on exertion for which screening tests such as chest roentgenograms and more definitive noninvasive tests such as CT scans are ordered initially. It is imperative that clinicians are cognizant of subtle clues on these imaging modalities that alert them to the possibility of PH. These clues may serve as a stepping stone towards more advanced noninvasive (echocardiogram) and invasive (right heart catheterization) testing. On the CT scan, the signs are classified into mediastinal and lung parenchymal abnormalities. In addition to suspecting the diagnosis of PH, this paper provides a pictorial essay to guide health care professionals in identifying the etiology of PH. This paper also provides concrete definitions, wherever possible, of what constitutes abnormalities in PH, such as dilated pulmonary arteries, pruning of vessels, and increased thickness of free wall of the right ventricle. The sensitivities and specificities of each sign are enumerated. The common radiographic and clinical features of many different etiologies of PH are tabulated for the convenience of the readers. Some newer imaging modalities such as dual-energy CT of the chest that hold promise for the future are also described.

Aktuelle Definition und Diagnostik der pulmonalen Hypertonie

“…Zur Abklärung bei PH sollte immer ein HR-CT durchgeführt werden, welches auch bei nur geringer oder fehlender Einschränkung der Lungenfunktion das Muster und Ausmaß von Lungenparenchymerkrankungen darstellen und so zur Abgrenzung zwischen PAH und einer PH der Gruppe 3 der aktuellen PH-Klassifikation beitragen kann [27]. Diffuse Knötchen, mediastinale Lymphknotenvergrößerung und eine Verdickung der interlobulären Septen weisen auf eine venookklusive Erkrankung, PVOD, hin [62,63]. Auch im nativen Thorax-CT kann bei entsprechender Fensterung ein Mosaikmuster als mögliches Zeichen chroni-scher Lungenembolien vorliegen [64], was zur weiteren Abklärung hinsichtlich CTEPH/CTED führen sollte.…”

Occult pulmonary arterial hypertension in patients with previous pulmonary tuberculosis

“…[27] CT is further useful in identifying other causes of PH such as pulmonary vasculature, lung parenchyma and cardiovascular structures. [28] One of the major limitations of this pilot study was the small number of participants that were recruited and enrolled in the study. Identifying participants who were previously treated for TB and had no underlying risk factors for the development of PAH is difficult in a quaternary hospital where most patients suffer from several co-existing pathologies.…”

Pulmonary hypertension and chronic lung disease: where are we headed?

“…lumen is measured, while on non-contrast exams the vessel wall is included [81]. For younger patients, the pulmonary artery/ascending aorta ratio correlates more strongly with PA pressure than with the diameter of the main pulmonary artery, while the reverse is true in patients aged >50 years [82,83].…”

“…These simple measurements are based on the evidence that PH is associated with pulmonary artery branch enlargement, which is more evident in some diseases (such as Eisenmenger syndrome or post-embolic PH or in some types of iPAH). The correlation between pulmonary artery diameter and haemodynamics may vary in different types of PH but remains moderate to strong [81,[84][85][86]. According to several studies, the CT measurements are reliable, with 96% sensitivity and >95% positive predictive value [86][87][88].…”