Korean J Radiol.  2019 Oct;20(10):1422-1430. 10.3348/kjr.2019.0286.

Computed Tomography Pulmonary Vascular Volume Ratio Can Be Used to Evaluate the Effectiveness of Pulmonary Angioplasty in Peripheral Pulmonary Artery Stenosis

• Goo HW

• KMID: 2459161
• DOI: http://doi.org/10.3348/kjr.2019.0286

Abstract

OBJECTIVE
To explore whether computed tomography (CT) pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.
MATERIALS AND METHODS
Changes in CT pulmonary vascular volume ratio between serial cardiothoracic CT examinations were calculated in 38 patients. Fifteen patients underwent interim pulmonary artery angioplasty (group 1), while 23 did not (group 2). According to the effectiveness of pulmonary artery angioplasty, patients in group 1 were further divided into group 1A (improved or aggravated) and group 1B (ineffective). Changes in the pulmonary vascular volume percentages among the three groups (group 1A, group 1B, and group 2) on serial CT examinations were compared.
RESULTS
Pulmonary artery angioplasty on serial CT examinations was successful in seven patients, ineffective in seven patients, and aggravated in one patient. As a result, eight patients were included in group 1A and seven were included in group 1B. Changes in the CT pulmonary vascular volume percentages in group 1A were statistically significantly greater than those in group 1B (11.6 ± 5.6% vs. 2.7 ± 1.6%, p < 0.003) and group 2 (11.6 ± 5.6% vs. 1.9 ± 1.4%, p < 0.002), while no statistically significant difference was found between group 1B and group 2 (2.7 ± 1.6% vs. 1.9 ± 1.4%, p > 0.1).
CONCLUSION
CT pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.

Keyword

Cardiothoracic CT; Congenital heart disease; Pulmonary angioplasty; Pulmonary artery stenosis; Pulmonary vascular volume; Threshold-based segmentation

MeSH Terms

Angioplasty*
Constriction, Pathologic*
Heart Defects, Congenital
Humans
Pulmonary Artery*

Figure

• 

  Fig. 1 Bar graph demonstrating changes in CT pulmonary vascular volume percentages on serial cardiothoracic CT examinations among groups 1A, 1B, and 2.Changes in CT pulmonary vascular volume percentages in group 1A are statistically significantly greater than those in group 1B (11.6 ± 5.6% vs. 2.7 ± 1.6%, p < 0.003 [*]) and group 2 (11.6 ± 5.6% vs. 1.9 ± 1.4%, p < 0.002 [**]), while no statistically significant difference was found between group 1B and group 2 (2.7 ± 1.6% vs. 1.9 ± 1.4%, p > 0.1). CT = computed tomography

• 

  Fig. 2 10-year-old boy with isolated left pulmonary stenosis had undergone left pulmonary artery stent placement before initial cardiothoracic CT and underwent successful surgical left pulmonary artery angioplasty between two serial cardiothoracic CT examinations (group 1A).A. Frontal volume-rendered CT image of pulmonary vasculature obtained from initial cardiothoracic CT shows segmented right and left pulmonary vascular volumes and left pulmonary vascular volume appears smaller than right one (right:left = 63.5%:36.5%). B. Frontal volume-rendered CT image of pulmonary vasculature obtained from follow-up cardiothoracic CT after surgical left pulmonary artery angioplasty reveals increased left pulmonary vascular volumes (right:left = 55.1%:44.9%). Increase in CT pulmonary vascular volume percentage between two serial CT examinations is approximately 8.5%. C. Oblique axial CT image obtained before surgical left pulmonary artery angioplasty reveals residual focal narrowing (arrow; 3.1 mm/m2 of body surface area) in branch left pulmonary artery. Implanted left pulmonary artery stent is noted. D. Oblique axial CT image acquired after surgical left pulmonary artery angioplasty shows improved left pulmonary artery stenosis (asterisks; 6.1 mm/m2 of body surface area, approximately 96.6% increment). aA = ascending aorta, dA = descending aorta

• 

  Fig. 3 1-year-old girl with pulmonary atresia and ventricular septal defect underwent placement of right ventricle-pulmonary artery conduit and left modified Blalock-Taussig shunt before initial cardiothoracic CT.She underwent unsuccessful surgical left pulmonary artery angioplasty between two serial cardiothoracic CT examinations (group 1B).A. Frontal volume-rendered CT image of pulmonary vasculature obtained from initial cardiothoracic CT shows segmented right and left pulmonary vascular volumes, and left pulmonary vascular volume is slightly smaller than right side (right:left = 64.1%:35.9%). B. Frontal volume-rendered CT image of pulmonary vasculature acquired from follow-up cardiothoracic CT after surgical left pulmonary artery angioplasty shows unchanged pattern of asymmetrically reduced left pulmonary vascularity (right:left = 66.6%:33.4%), and left pulmonary vascular volume percentage slightly decreased by approximately 2.5%, indicating ineffective surgical left pulmonary artery angioplasty. Even though branch left pulmonary artery is dilated (arrow) as result of surgical procedure, this enlargement does not have effect on CT pulmonary vascular volume percentage. C. Oblique axial CT image obtained before surgical left pulmonary artery angioplasty reveals diffuse narrowing (arrows; 6.7 mm/m2 of body surface area) of branch left pulmonary artery. Left modified Blalock-Taussig shunt (asterisks) is noted. D. Oblique axial CT image acquired after surgical left pulmonary artery angioplasty shows dilated proximal left branch pulmonary artery (asterisk). However, distal segment still shows focal narrowing (arrow; 5.6 mm/m2 of body surface area, approximately 18.5% decrement). C = right ventricle-pulmonary artery conduit, R = right pulmonary artery

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  Fig. 4 15-year-old boy with repaired tetralogy of Fallot underwent left pulmonary artery stent placement before initial cardiothoracic CT.No interim surgical or interventional pulmonary artery angioplasty was performed between two serial cardiothoracic CT examinations (group 2).A. Frontal volume-rendered CT image of pulmonary vasculature acquired from initial cardiothoracic CT shows segmented right and left pulmonary vascular volumes, and left pulmonary vascular volume appears smaller than right (right:left = 70.5%:29.5%). B. Frontal volume-rendered CT image of pulmonary vasculature obtained from follow-up cardiothoracic CT shows unchanged pattern of asymmetrically reduced left pulmonary vascularity (right:left = 72.4%:27.6%), and left pulmonary vascular volume percentage slightly decreased by approximately 1.9%. C. Oblique axial CT image from initial cardiothoracic CT reveals focal in-stent narrowing (arrow; 2.8 mm/m2 of body surface area) in branch left pulmonary artery. Implanted left pulmonary artery stent is noted. D. Oblique axial CT image from follow-up cardiothoracic CT shows no change in focal in-stent narrowing (arrow; 3.0 mm/m2 of body surface area, approximately 7.3% increment) in branch left pulmonary artery. A = aortic arch, MPA = main pulmonary artery

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