Rationale and Objectives
Cross-sectional area <5 mm 2 (CSA<5) is a computed tomography (CT) metric that has been used for the evaluation of pulmonary vessel alterations and perfusion. CSA<5 is calculated from three axial slices; thus, whether CSA<5 represents the small pulmonary vessel alterations in the whole lung remains unclear. The purpose of this study was to compare the measurements of CSA<5 using three axial slices and coronal reconstructed slices in the relationship between the measured CSA<5 and pulmonary perfusion measured using lung perfusion scintigraphy.
Materials and Methods
This study comprised 28 subjects who underwent both noncontrast CT and lung perfusion scintigraphy. The present study measured CSA<5 using both three axial CT images and coronal reconstruction images and then obtained the percentage of the CSA in right lung to that in whole lung (R/W-CSA<5). Using anteroposterior and posteroanterior projections on technetium-99m macroaggregated albumin (MAA) lung perfusion scintigraphy, we obtained right and total lung counts and calculated the percentage of the right to whole lung counts (R/W-MAA). The correlations of the R/W-CSA<5 calculated using three axial slices (R/W-CSA Ax <5) and coronal reconstructed slices (R/W-CSA COR <5) with R/W-MAA were evaluated using Spearman rank correlation analysis.
Results
Both R/W-CSA Ax <5 and R/W-CSA COR <5 were significantly correlated with R/W-MAA; however, the correlation coefficient with R/W-CSA COR <5 (ρ = 0.842, P < .0001) was greater than that with R/W-CSA Ax <5 (ρ = 0.631, P = .0004).
Conclusions
Coronal reconstruction images appear suitable for quantitative measurement of CSA of small pulmonary vessels.
To understand the pathophysiologic manifestations of a variety of lung diseases, it is necessary to evaluate morphologic alterations in the pulmonary vasculature. Morphologic vascular alterations are linked with both pulmonary ventilation and perfusion. For instance, morphologic vascular alteration is one of the characteristic histologic features of chronic obstructive pulmonary disease (COPD) , while vascular alteration is related to both airflow limitation and decreased pulmonary perfusion, which can lead to pulmonary hypertension .
Pulmonary vascular alterations are difficult to evaluate quantitatively in vivo. Therefore, several investigations have been conducted on various lung diseases proposing the use of computed tomography (CT) for the quantitative evaluation of morphologic vascular alterations of the cross-sectional area (CSA) of small pulmonary vessels . In fact, significant correlations have been reported between the CSA of small pulmonary vessels and both pulmonary perfusion and degree of pulmonary hypertension .
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Materials and methods
Subjects
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CT Protocol
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CT Measurement of Small Pulmonary Vessels
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Pulmonary Perfusion Scintigraphy
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Statistical Analysis
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Results
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Table 1
CT Measurements and Scintigraphy Measurements
%CSA Ax <5 (%) 0.64 ± 0.21 %CSA COR <5 (%) 0.58 ± 0.22 R/W-CSA Ax <5 (%) 59.0 ± 10.7 R/W-CSA COR <5 (%) 57.5 ± 11.3 R/W-CSA COR-DA <5 (%) 57.5 ± 13.2 R/W-CSA COR-TR <5 (%) 55.4 ± 11.5 R/W-CSA COR-AA <5 (%) 60.8 ± 14.4 R/W-MAA (%) 59.6 ± 24.4
CSA<5, the cross-sectional area of pulmonary vessels <5 mm 2 ; MAA, macroaggregated albumin.
Table 2
Correlations Between R/W-MAA and R/W-CSA
ρ_P_ R/W-CSA Ax <5 (%) 0.631 .0004 R/W-CSA COR <5 (%) 0.842 <.0001 R/W-CSA COR-DA <5 (%) 0.727 <.0001 R/W-CSA COR-TR <5 (%) 0.764 <.0001 R/W-CSA COR-AA <5 (%) 0.897 <.0001
CSA<5, the cross-sectional area of pulmonary vessels <5 mm 2 ; MAA, macroaggregated albumin.
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Discussion
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