Abstract
ObjectivesThe aim of this study was to assess the effect of hybrid iterative reconstruction and post processing on emphysema quantification in low-dose CT scans of COPD patients using pulmonary function tests (PFT) as a reference.MethodsCT scans of 23 COPD patients diagnosed with GOLD I or higher were reconstructed with iDose4 level 1 to 7 in IntelliSpace Portal (ISP) 6 and 7. ISP7 was used with and without specific denoising filter for COPD. The extent of emphysema was measured as percentage of lung voxels with attenuation < − 950 Hounsfield units (%LAA-950). The correlation between %LAA-950 and PFT, age, BMI, pack years, and the Clinical COPD Questionnaire (CCQ) and Medical Research Council dyspnea scale (MRC) was determined.ResultsDenoising significantly reduced %LAA-950 as was demonstrated by lower %LAA-950 in ISP7 with denoising filter and a significant reduction in %LAA-950 with higher iDose4 levels. All PFT except forced vital capacity (FVC) were significantly inversely correlated with %LAA-950. There was a trend toward a stronger correlation at higher iDose4 levels. %LAA-950 was also significantly correlated with BMI, GOLD class, and CCQ scores.ConclusionsOur study showed that hybrid iterative reconstruction and use of post processing denoising can optimize the use of emphysema quantification in CT scans as a complimentary diagnostic tool to stage COPD in addition to PFT.
Highlights
Chronic obstructive pulmonary disease (COPD) is globally one of the main causes of death
There was a trend toward a stronger correlation at higher iDose4 levels. %LAA-950 was significantly correlated with body mass index (BMI), Global initiative for chronic Obstructive Pulmonary Disease (GOLD) class, and Clinical COPD Questionnaire (CCQ) scores
Our study showed that hybrid iterative reconstruction and use of post processing denoising can optimize the use of emphysema quantification in computed tomography (CT) scans as a complimentary diagnostic tool to stage COPD in addition to pulmonary function tests (PFT)
Summary
Chronic obstructive pulmonary disease (COPD) is globally one of the main causes of death. The amount of people suffering from the disease is often underestimated because not all patients with airway symptoms seek medical attention [1]. More attention for early diagnosis of COPD is needed, especially because there is a higher prevalence of pulmonary cancer in COPD. COPD is mainly diagnosed based on detection of irreversible airflow limitation in pulmonary function tests (PFT). Airflow limitation is caused by airway narrowing (through inflammation or mucus) and/or emphysema (loss of recoil). Most if not all COPD patients have combined features of emphysema and chronic bronchitis. Very rarely one encounters a patient with emphysema but little or no airflow limitation [4].
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