Maxime Hackx

Chronic Obstructive Pulmonary Disease: CT Quantification of Airway Dimensions, Numbers of Airways to Measure, and Effect of Bronchodilation.

PURPOSE To determine the effect of bronchodilation on airway indexes reflecting airway disease in patients with chronic obstructive pulmonary disease (COPD) and to determine the minimum number of segmental and subsegmental airways required. MATERIALS AND METHODS This study was approved by the local ethical committee, and written informed consent was obtained from all subjects. Twenty patients with COPD who had undergone pre- and postbronchodilator pulmonary function tests and computed tomographic (CT) examinations were prospectively included. Eight healthy volunteers underwent two CT examinations. Luminal area and wall thickness (WT) of third- and fourth-generation airways were measured twice by three readers. The percentage of total airway area occupied by the wall and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. The effects of pathologic status, session, reader, bronchodilation, and CT examination were assessed by using mixed linear model analyses. The number of airways to measure for a definite percentage error of √WAPi10 was computed by using a bootstrap method. RESULTS There were no significant session, reader, or bronchodilation effects on WT in third-generation airways and √WAPi10 in patients with COPD (P values ranging from .187 to >.999). WT in third-generation airways and √WAPi10 were significantly different in patients with COPD and control subjects (P = .018 and <.001, respectively). Measuring 12 third- or fourth-generation airways ensured a maximal 10% error of √WAPi10. CONCLUSION WT in third-generation airways and √WAPi10 are not significantly different before and after bronchodilation and are different in patients with COPD and control subjects. Twelve is the minimum number of third- or fourth-generation airways required to ensure a maximal 10% error of √WAPi10. (©) RSNA, 2015 Clinical trial registration no. NCT01142531 Online supplemental material is available for this article.

Effect of total lung capacity, gender and height on CT airway measurements

OBJECTIVE Testing the hypothesis that CT airway measurements could be influenced by total lung capacity (TLC), gender and height in normal individuals. METHODS In this ethics committee-approved prospective trial, 87 healthy never-smoking volunteers who provided written informed consent were included. From a helical CT scan of the chest, the wall thickness (WT) and the lumen area were twice measured in the third- and fourth-generation airways by three readers using a dedicated software. In addition, the TLC was also measured using CT (TLCCT). The percentage of airway area occupied by the wall (WA%) and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. CT airway measurements were compared between genders by using a mixed linear model. The correlations between height, TLCCT and CT airway measurements were tested by using a Pearson correlation analysis. These correlations were arbitrarily considered as significant if there was a significant correlation observed for each of the six measurement sessions. RESULTS √WAPi10, WT3rd and WT4th were significantly different between genders. For both genders, there was no significant correlation between any airway measurements and TLCCT. In females only, WT3rd and WT4th were significantly and negatively correlated with height. CONCLUSION √WAPi10, WT3rd and WT4th are different in males and females. WT3rd and WT4th are correlated with height in females only but not with TLC or in males. Advances in knowledge: CT airway measurements are influenced by gender and by height in females only but not by TLC. They should be adjusted according to gender and height in females.

Severe COPD exacerbation: CT features.

Abstract Objective: To describe CT features associated with severe exacerbations of Chronic Obstructive Pulmonary Disease (COPD). Materials and Methods: In this prospective ethical-committee-approved study, 44 COPD patients (34 men, 10 women, age range 49–83 years) who provided written informed consent were included at the time of hospital admission for severe exacerbation. Pulmonary function tests (PFT) and chest CT scans were performed at admission and after resolution of the episode following a minimum of 4 weeks free of any acute symptom. For each CT scan, two radiologists independently scored 15 features in each lobe and side. CT features and PFT results were compared for exacerbation and control through Mac-Nemar tests and paired t-tests, respectively. Results: Forced expiratory volume in 1 second and vital capacity improved significantly after exacerbation (p = 0.023 and 0.012, respectively). Bronchial wall thickening and lymphadenopathy were graded significantly higher at exacerbation than at control by both readers (p ranging from < 0.001 to 0.028). Other CT features were not observed during exacerbation, or were so only by one reader (p ranging from < 0.001 to 0.928). Conclusion: Only lymphadenopathy and bronchial wall thickening are CT features associated with severe COPD exacerbation, respectively in 25% and 50% of patients. Our findings do not advocate a role for CT in the routine work-up of patients with severe COPD exacerbation.

Typical US, CT and MR findings in multiple biliary hamartomas

A 38-year-old woman without known malignancy was referred to the Department of Radiology for acute epigastric pain. An abdominal US was first performed that revealed multiple small hyperechoic liver lesions with comet-tail echoes (Figure 1). An abdominal CT was performed that revealed multiple small hypodense liver lesions with no enhancement after intravenous administration of iodine contrast (Figure 2). On the basis of these US and CT findings, the diagnosis of multiple biliary hamartomas (MBHs) was suggested. A month later, an abdominal MRI was performed revealing multiple small liver lesions hyperintense on T2-weighted images and hypointense on T1-weighted image with no enhancement after intravenous administration of gadolinium. In addition, MR cholangiography showed multiple small cystic liver lesions scattered through both liver lobes, with normal appearances of the intrahepatic and extrahepatic bile ducts. There was no communication between the lesions and the draining bile ducts (Figure 3). As the patient had no known malignancy, and as the US, CT and

Value of the “spine sign” on lateral chest views

OBJECTIVE To determine the performance of the spine sign in detecting lower chest abnormalities in the lateral view. METHODS This retrospective study included 200 patients who had undergone lateral view and CT scans of the chest within 1 week. Two radiologists independently read the lateral views, and a third radiologist, blinded to the aim of the study, read the scans. The spine sign was considered as positive if the progressive increase in lucency of the vertebral bodies was altered. Interreader agreement was calculated through k-statistics. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were calculated compared with CT. RESULTS Agreements between readers ranged from 0.12 to 0.68. Positive spine sign could appear in two ways: absent or inversed progressive increase in lucency of the vertebral bodies. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were, respectively, 60% and 70%; 64% and 84%; 91% and 97%; 19% and 29%; and 61% and 72% for each reader (p-value ranging from 0.026 to 0.196). Abnormalities most frequently associated with positive spine sign were plate-like atelectasis, ground-glass opacity, pleural effusion and consolidation. CONCLUSION The spine sign can present as an absent or inversed progressive increase in lucency of the vertebral bodies. It has a moderate sensitivity but a good positive-predictive value, so it can be useful especially when it appears as inversed progressive increase in lucency of the vertebral bodies to detect various abnormalities usually identifiable on chest radiographs. ADVANCES IN KNOWLEDGE On lateral chest radiographs, the spine sign is useful to detect lower chest abnormalities and is related to various underlying abnormalities and is, per se, non-specific.

Variability of CT Airways Measurements in COPD Patients Between Morning and Afternoon: Comparisons to Variability of Spirometric Measurements

RATIONALE AND OBJECTIVES Computed tomography (CT) airways measurements can be used as surrogates to spirometric measurements for assessing bronchodilation in a particular patient with chronic obstructive pulmonary disease. Although spirometric measurements show variations within the opening hours of a hospital department, we aimed to compare the variability of CT airways measurements between morning and afternoon in patients with chronic obstructive pulmonary disease to that of spirometric measurements. MATERIALS AND METHODS Twenty patients had pulmonary function tests and CT around 8 am and 4 pm. Luminal area (LA) and wall thickness (WT) of third and fourth generation airways were measured twice by three readers. The percentage of airway area occupied by the wall (WA%) and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. The effects of examination time, reader, and measurement session on CT airways measurements were assessed, and the variability of these measurements was compared to that of spirometric measurements. RESULTS Variability of LA3rd and LA4th was greater than that of spirometric measurements (P values ranging from <.001 to .033). There was no examination time effect on √WAPi10, WT3rd, LA4th, or WA%4th (P values ranging from .102 to .712). There was a reader effect on all CT airways measurements (P values ranging from <.001 to .028), except in WT3rd (P> .999). There was no effect of measurement session on any CT airway measurement (P values ranging from .535 to >.999). CONCLUSION As the variability of LA3rd and LA4th is greater than that of spirometric measurements, clinical studies should include cohorts with larger numbers of patients when considering LA than when considering spirometric measurements as end points.

CT Imaging of the Airways

Abnormalities of the airways are found in a wide spectrum of diseases and conditions, with CT features that can overlap. CT features include bronchiectasis/bronchiolectasis, mucous plugging, bronchial wall thickening, and tree-in-bud pattern/centrolobular micronodules. They can be accurately assessed through image processing available on a console or workstation, such as MPR or VRT (SSD, minIP, and MIP). Recent advances in software have provided airway tree segmentation and virtual bronchoscopy navigation, as well as objective quantification of airway changes. Future developments in this objective quantification and in the reduction of the radiation dose are mandatory if CT is to play a more important role in the routine diagnosis, prognosis, and monitoring of airway diseases.