Selection of patients for lung volume reduction surgery using a power law analysis of the computed tomographic scan

• Published in: Thorax Vol. 58; no. 6; pp. 510 - 514
• Main Authors: Coxson, H O, Whittall, K P, Nakano, Y, Rogers, R M, Sciurba, F C, Keenan, R J, Hogg, J C
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Thoracic Society 01.06.2003; BMJ; BMJ Publishing Group Ltd; BMJ Publishing Group LTD; BMJ Group
• Subjects: Biological and medical sciences; Carbon monoxide; Care and treatment; Chronic Obstructive Pulmonary Disease; computed tomography; Development and progression; Emphysema; Emphysema, Pulmonary; Exercise Tolerance; Humans; Investigative techniques, diagnostic techniques (general aspects); lung volume reduction surgery; Lungs; Medical imaging; Medical sciences; Methods; Middle Aged; Patient outcomes; Patient Selection; Physiology; Pneumonectomy - methods; Postoperative Care - methods; Preoperative Care - methods; Pulmonary Emphysema - diagnostic imaging; Pulmonary Emphysema - surgery; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Respiratory Function Tests; Respiratory system; Surgery; Tomography, X-Ray Computed; Canada; United States; Human; Lung disease; Open reduction; Radiodiagnosis; Physical performance; Respiratory disease; Decision making; Treatment efficiency; Exploration; Lung volume; Treatment; Surgery; Bronchus disease; Medical imagery; Exercise tolerance test; Computerized axial tomography; Obstructive pulmonary disease; Technique; Emphysema
• ISSN: 0040-6376; 1468-3296
• DOI: 10.1136/thorax.58.6.510

Background: A study was undertaken to test the hypothesis that patients respond better to lung volume reduction surgery (LVRS) if their emphysema is confluent and predominantly located in the upper lobes. Methods: A density mask analysis was used to identify voxels inflated beyond 10.2 ml gas/g tissue (−910 HU) on preoperative and postoperative CT scans from patients receiving LVRS. These hyperinflated regions were considered to represent emphysematous lesions. A power law analysis was used to determine the relationship between the number (K) and size (A) of the emphysematous lesions in the whole lung and two anatomical regions using the power law equation Y=KA−D. Results: The analysis showed a positive correlation between the change in the power law exponent (D) and the change in exercise (Watts) after surgery (r=0.47, p=0.03). There was also a negative correlation between the power law exponent D in the upper region of the lung preoperatively and the change in exercise following surgery (r=−0.60, p<0.05). Conclusions: These results confirm that patients with large upper lobe lesions respond better to LVRS than patients with small uniformly distributed disease. Power law analysis of lung CT scans provides a quantitative method for determining the extent and location of emphysema within the lungs of patients with COPD.