|Year : 2021 | Volume
| Issue : 2 | Page : 88-89
Spot the abnormality
M Vishnu Sharma, Baseer Ahmmad H Walikar
Department of Respiratory Medicine, A J Institute of Medical Sciences and Research Centre, Mangalore, Karnataka, India
|Date of Submission||26-Sep-2021|
|Date of Acceptance||12-Oct-2021|
|Date of Web Publication||21-Jan-2022|
M Vishnu Sharma
Department of Respiratory Medicine, A J Institute of Medical Sciences and Research Centre, Kuntikana, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sharma M V, Walikar BA. Spot the abnormality. J Assoc Pulmonologist Tamilnadu 2021;4:88-9
| Question|| |
What is the abnormality in the computed tomography [CT] pulmonary angiogram image [Figure 1]?
| Answer|| |
In the CT pulmonary angiogram image, diameter of the main pulmonary artery (PA) is more than that of ascending aorta which is suggestive of pulmonary arterial hypertension (PAH). Main PA diameter is measured at its bifurcation in axial CT image, perpendicular to its long axis. Diameter more than 29 mm is suggestive of PAH. This has 97% positive predictive value, 89% specificity and 87% sensitivity. In this case, it was 46.7 mm [Figure 2].
|Figure 2: Computed tomography pulmonary angiogram axial image showing measurement of main pulmonary artery diameter|
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When the diameter of main PA is larger than that of the adjacent ascending thoracic aorta in axial view in thoracic CT scan, it is suggestive of moderate or severe PAH. In mild PAH main PA diameter may be normal.
For accurate assessment of pulmonary hypertension (PH), PA pressure and pulmonary arterial wedge pressure should be measured by right heart catheterization. This invasive method requires specialist centers with experts. Hence most often PH is measured by echocardiography. PH is measured indirectly by echocardiography by measuring maximal tricuspid regurgitation velocity with continuous-wave Doppler. This can be obtained only in the presence of a measurable TR signal. Tricuspid regurgitation is found in approximately 80% of patients with systolic pulmonary pressure above >35 mmHg. It should be remembered that a small subset of patients with severe PH may have little or no tricuspid regurgitation. Hence, it is important to compare the diameter of main PA to that of ascending aorta in thoracic CT axial image.
The ratio of the diameter of PA to that of the aorta more than 1 is a reliable indicator of PH. In patients with underlying lung disease increase in diameter of PA is associated with increased PAH, more severe/extensive/advanced lung disease, frequent exacerbations and poor long-term prognosis.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]