Novel computed tomographic chest metrics to detect pulmonary hypertension

Abstract

BackgroundEarly diagnosis of pulmonary hypertension (PH) can potentially improve survival and quality of life. Detecting PH using echocardiography is often insensitive in subjects with lung fibrosis or hyperinflation. Right heart catheterization (RHC) for the diagnosis of PH adds risk and expense due to its invasive nature. Pre-defined measurements utilizing computed tomography (CT) of the chest may be an alternative non-invasive method of detecting PH.MethodsThis study retrospectively reviewed 101 acutely hospitalized inpatients with heterogeneous diagnoses, who consecutively underwent CT chest and RHC during the same admission. Two separate teams, each consisting of a radiologist and pulmonologist, blinded to clinical and RHC data, individually reviewed the chest CT's.ResultsMultiple regression analyses controlling for age, sex, ascending aortic diameter, body surface area, thoracic diameter and pulmonary wedge pressure showed that a main pulmonary artery (PA) diameter ≥29 mm (odds ratio (OR) = 4.8), right descending PA diameter ≥19 mm (OR = 7.0), true right descending PA diameter ≥ 16 mm (OR = 4.1), true left descending PA diameter ≥ 21 mm (OR = 15.5), right ventricular (RV) free wall ≥ 6 mm (OR = 30.5), RV wall/left ventricular (LV) wall ratio ≥0.32 (OR = 8.8), RV/LV lumen ratio ≥1.28 (OR = 28.8), main PA/ascending aorta ratio ≥0.84 (OR = 6.0) and main PA/descending aorta ratio ≥ 1.29 (OR = 5.7) were significant predictors of PH in this population of hospitalized patients.ConclusionThis combination of easily measured CT-based metrics may, upon confirmatory studies, aid in the non-invasive detection of PH and hence in the determination of RHC candidacy in acutely hospitalized patients.

Extrapulmonary comorbidities in chronic obstructive pulmonary disease: state of the art

“…In the same study, only 56% of those with obstructive lung disease had an echocardiogramderived sPAP value within 10 mmHg of that determined by right heart catheterization [49]. Measures of cardiac chamber and major vessel sizes from standard CT images show a higher degree of sensitivity and specificity for PH than has been reported for echocardiography [50]. This is not yet established in routine clinical practice.…”

State of the Art: Advanced Imaging of the Right Ventricle and Pulmonary Circulation in Humans (2013 Grover Conference Series)

“…[70][71][72] In line with these findings, single-photon emission tomography (SPECT) imaging has demonstrated that, in the hypertrophied RV of patients with PH, myocardial fatty acid uptake was decreased. 73 Although it has been shown that measuring myocardial glucose metabolism using PET with 18 F-2-deoxy-2-fluoro-D-glucose ( 18 FDG) tracers is feasible in patients with PAH, 74 inconsistent results have been reported. Some studies have shown that the ratio of RV glucose uptake to LV uptake is increased in PAH and is associated with disease severity.…”

“…In PAH, RV mass, wall thickness, and the ventricular mass index (i.e., ratio of RV mass to LV mass) measured by CMR or multidetector computed tomography (MDCT) were increased and moderately related to pulmonary pressures. [16][17][18][19] However, in PAH, RV mass is, on average, 2.5-fold increased, which might be insufficient to compensate for an often fourfold increase in pulmonary pressure. In line with these findings, Simon et al 20 demonstrated regional heterogeneity in RV structural remodeling, and it was shown that, although RV wall thickness increases during the course of disease, it remained insufficient to normalize the RV wall stress.…”

“…81 These conflicting results may be caused by differences in patient populations, scanning protocols, and data analysis. Other limitations could be that 18 FDG uptake is not a direct reflection of glycolysis, because 18 FDG uptake is also influenced by other factors, reflects the uptake of the overall myocardial tissue instead of the cellular uptake, and cannot appropriately be metabolized through all the glycolysis steps because of its chemical structure. 82 At this moment, clinical PET studies cannot provide firm answers about an eventual "metabolic switch" in the failing RV of patients with PAH, whereas this metabolic switch has been previously demonstrated in animal models.…”

“…However, PET techniques allow assessment of pathophysiological pathways of myocardial disease processes in vivo and therefore have great potential to monitor therapeutic responses longitudinally in the near future. One study has demonstrated that PET RV 18 FDG uptake might be of clinical relevance after epoprostenol therapy. 80 Future studies are required to validate RV imaging parameters to assess therapeutic effects.…”