Reproducibility of quantitative, spirometrically controlled CT.

Kohz, P.; Stäbler, Axel; Beinert, T.; Behr, Jüergen; Egge, Tor; Heuck, A.; Reiser, M.

doi:10.1148/radiology.197.2.7480708

Cited by 61 publications

(31 citation statements)

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“…Reproducibility aspects have to be taken into account before application of this technique in practice. At 50% VC, the standard deviation of the estimat-ed mean attenuation values was after a 5 minute pause 10 HU [13]. This level of inspiration is suitable to differentiate between patients suffering from idiopathic lung fibrosis and patients with COPD.…”

Section: Discussionmentioning

confidence: 92%

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Reproducibility of spirometrically controlled CT lung densitometry in a clinical setting

Lamers

Kemerink²,

Drent³

et al. 1998

Eur Respir J

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aaDensitometry of the lung is extensively used in pulmonary research. It has the potential to become an important addition to standard lung function tests in diagnosing and following the extent of pulmonary emphysema and interstitial lung disease. For recent reviews of this extensive work we refer to the literature [1,2]. The value of the technique is clearly proven in pulmonary emphysema. During inspiration, computed tomography (CT) correlates well with the pathologic score of emphysema [3]. Expiratory CT reflects airway obstruction and air-trapping more than it does emphysema [4,5]. Densitometric data may contribute to improved patient selection and to better evaluation of the response to volume reduction surgery [6,7]. Densitometry may provide an additional measure in selecting the side of greatest severity for unilateral lung reduction surgery [7].The methodologogy of CT densitometry has been established as well as factors affecting parameters derived from a histogram of Hounsfield units (HU). The accuracy and conformity of modern CT scanners have proved to be adequate after correction for poor air calibration [8,9]. CT number histograms of the lung are strongly dependent on section thickness and reconstruction filter [10][11][12]. To optimize CT evaluation procedures, semi-automatic algorithms isolating lung parenchyma by fast contour tracking have been developed, as well as automatic evaluation algorithms calculating various densitometric parameters automatically. Usually, mean lung density is determined as an average over a relatively large area. Unfortunately, it can be spuriously misleading especially at localized disease onset [13]. Mean lung density, however, is not the only densitometric parameter which can be extracted from the CT data. Pixel index analysis [3,4,14] and the lowest 10th percentile of the frequency distribution of densities [15] have shown promising results in the assessment of emphysema.If densitometry of the lung is used for diagnosis and follow-up of pulmonary emphysema or interstitial lung disease, the overall precision of the procedure has to be established. Reproducibility errors due to instrumental and technical factors have generally been considered to be smaller than patient-related factors. The CT density of the lung is considerably influenced by the level of inspiration at which the CT images are obtained. Control and monitoring this level of inspiration during scanning is of major importance to obtain reproducible CT lung density measurements. A spirometrically controlled CT technique has been developed, offering the opportunity to obtain CT scans at defined levels of inspiration [16].The purpose of this study was to assess the reproducibility of a number of histogram-related parameters of single CT slices through the upper and the lower zones of the lungs at 90 and 10% of the vital capacity (VC) in a hospitalized patient population. Reproducibility of spirometrically controlled CT lung desitometry in a clinical setting. R.J.S. Lamers, G.J. Kemerink, M. Drent, J.M.A. van E...

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Section: Discussionmentioning

confidence: 92%

“…Usually, mean lung density is determined as an average over a relatively large area. Unfortunately, it can be spuriously misleading especially at localized disease onset [13]. Mean lung density, however, is not the only densitometric parameter which can be extracted from the CT data.…”

Section: Aamentioning

confidence: 99%

Reproducibility of spirometrically controlled CT lung densitometry in a clinical setting

Lamers

Kemerink²,

Drent³

et al. 1998

Eur Respir J

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“…Second, CT densitometry is also influenced by the level of inspiration during CT scanning [17]. A spirometrically controlled CT technique has been developed, offering the opportunity to obtain CT scans at defined levels of inspiration [18, 19]. …”

Section: Discussionmentioning

confidence: 99%

Quantitative Thin-Section CT Analysis of the Enlargement and Coalescence of Low-Attenuation Clusters in Patients with Emphysema

et al. 2006

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Background: The analysis of the number and size of low-attenuation clusters has been adopted as quantitative computed tomography (CT) analysis of emphysema; however, a detailed examination has not been made on the relation between the number of various cluster sizes and the extent of emphysema. Objective: The aim of this study was to evaluate the relationship between the size and number of clusters on CT scans in patients with emphysema. Methods: This retrospective study included 31 emphysema patients. The number (LAN) and mean size (LAS) of clusters below –950 HU, and relative low-attenuation area below –950 HU (RA950) were calculated using an image-processing program. The size of clusters was divided into 3 categories, and the number in each size category was obtained as follows: small (sLAN 0.4–8 mm²), medium (mLAN 8.4–40 mm²), and large (lLAN >40 mm²). The relationships between the RA950 and sLAN, mLAN, or lLAN were evaluated. Patients were divided according to the extent of RA950 (>25% = severe emphysema, <25% = mild emphysema), and the relations between RA950 and LAN, and between RA950 and sLAN, mLAN, or lLAN were evaluated. Results: The sLAN decreased as RA950 increased (r = –0.477), whereas mLAN and lLAN increased (r = 0.421, and r = 0.819). In severe emphysema, sLAN and mLAN decreased as RA950 increased (r = –0.722, and r = –0.698). In mild emphysema, mLAN and lLAN increased as RA950 increased (r = 0.732, and r = 0.972). Conclusions: The degree of the coalescence of the clusters depends on the size of clusters and the extent of emphysema. Quantitative CT analyses of clusters are helpful to elucidate the pathophysiology and progressive nature of emphysema.

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“…During this pause, the lungs are imaged at full inflation by maintaining a positive facemask pressure (25-30 cmH 2 O) for inspiratory images, and resting end-exhalation by applying no mask pressure for expiratory images [48,66]. Both spirometer and PCV techniques have been shown to be highly reproducible [66,68].…”

Section: Standardisationmentioning

confidence: 99%

Chest computed tomography: a validated surrogate endpoint of cystic fibrosis lung disease?

et al. 2012

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Clinical trials for the treatment of cystic fibrosis (CF) lung disease are important to test and optimise new therapeutic interventions. To evaluate the effect of these interventions, sensitive and accurate outcome measures are needed. The most commonly used endpoints are spirometric variables such as the forced expiratory volume in 1 s and respiratory tract exacerbations. Unfortunately, these endpoints are relatively insensitive for monitoring progression of CF lung disease, and thus require a large number of patients when used in clinical studies. In addition, these endpoints are not suitable to study CF lung disease in young children. Chest computed tomography (CT) holds great promise for use as a sensitive surrogate endpoint in CF. A large body of evidence has been produced to validate the use of chest CT as a primary endpoint to study CF lung disease. However, before chest CT can be used in clinical trials, it has to be recognised as a validated surrogate endpoint by regulatory agencies. The aim of this review is to summarise what is currently known about the use of chest CT as surrogate endpoint in clinical trials in CF. @ERSpublications Evaluation of the use of chest CT as a sensitive surrogate endpoint in clinical trials in CF

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Reproducibility of quantitative, spirometrically controlled CT.

Cited by 61 publications

References 0 publications

Reproducibility of spirometrically controlled CT lung densitometry in a clinical setting

Reproducibility of spirometrically controlled CT lung densitometry in a clinical setting

Quantitative Thin-Section CT Analysis of the Enlargement and Coalescence of Low-Attenuation Clusters in Patients with Emphysema

Chest computed tomography: a validated surrogate endpoint of cystic fibrosis lung disease?

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