Elsevier

Academic Radiology

Volume 17, Issue 1, January 2010, Pages 93-99
Academic Radiology

Original investigation
Quantitative CT Measurement of Cross-sectional Area of Small Pulmonary Vessel in COPD: Correlations with Emphysema and Airflow Limitation

https://doi.org/10.1016/j.acra.2009.07.022Get rights and content

Rationale and Objectives

Pulmonary vascular alteration is one of the characteristic features of chronic obstructive pulmonary disease (COPD). Recent studies suggest that vascular alteration is closely related to endothelial dysfunction and may be further influenced by emphysema. However, the relationship between morphological alteration of small pulmonary vessels and the extent of emphysema has not been assessed in vivo. The objectives of this study are: to evaluate the correlation of total cross-sectional area (CSA) of small pulmonary vessels with the extent of emphysema and airflow obstruction using CT scans and to assess the difference of total CSA between COPD phenotypes.

Materials and Methods

We measured CSA less than 5 mm2 and 5–10 mm2, and calculated the percentage of the total CSA for the lung area (%CSA < 5, and %CSA5–10, respectively) using CT scans in 191 subjects. The extent of emphysema (%LAA-950) was calculated, and the correlations of %CSA < 5 and %CSA5–10 with %LAA-950 and results of pulmonary function tests (PFTs) were evaluated. The differences in %CSA between COPD phenotypes were also assessed.

Results

The %CSA < 5 had significant negative correlations with %LAA-950 (r = -0.83, P < .0001). There was a weak but statistically significant correlation of %CSA < 5 with forced expiratory volume in 1 second (FEV1)% predicted (r = 0.29, P < .0001) and FEV1/forced vital capacity (r = 0.45, P < .0001). A %CSA 5–10 had weak correlations with %LAA-950 and results of PFTs. %CSA < 5 was significantly higher in bronchitis phenotype than in the emphysema phenotype (P < .0001).

Conclusions

Total CSA of small pulmonary vessels at sub-subsegmental levels strongly correlates with the extent of emphysema (%LAA-950) and reflects differences between COPD phenotypes.

Section snippets

Subjects

All subjects in our study were enrolled in the National Lung Screening Trial (NLST), a full description for which is available on the website (http://www.cancer.gov/nlst). Subjects were eligible to participate in the NLST if they were between the ages of 55 and 74 and had a history of at least 30 pack-years of cigarette smoking. All subjects in the trial gave written informed consent. This study and manuscript were reviewed and approved according to the NLST/Lung Screening Study Publications,

Characteristics of the Study Subjects

Characteristics of the patients including the results of PFT are presented in Table 1. According to the CT criteria in this study, 68 subjects were excluded. In addition, 44 subjects were excluded because of obvious abnormal parenchymal lesions other than emphysema (n = 2 for interstitial pneumonia, n = 1 for multiple nodules, n = 1 for atelectasis), pleural effusion (n = 1), and image noise (n = 39). Thus 191 patients (mean age, 62 ± 5 years; range, 56–74 years; 78 women, 61 ± 4 years and 113

Discussion

In the present study, we found that %CSA < 5 had a negative strong correlation with the extent of emphysema. Meanwhile, the correlations of %CSA < 5 with FEV1 % predicted and FEV1/FVC were significant but weak. These results support the concept that the vascular alteration closely correlates with the extent of emphysema rather than airway obstruction (13). Moreover, %CSA < 5 was significantly higher in subjects with bronchitis phenotype than in emphysema phenotype. In addition, this difference

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    Dr. Washko was supported by k23 NIH Grant: 1K23HL089353-01A1 and the Parker B. Francis Foundation.

    The NLST (NCT00047385) is registered at www.clinicaltrials.gov. Registered at www.clinicaltrials.gov; no.NCT00047385.

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