Localized compliance of small airways in excised rat lungs using microfocal X-ray computed tomography. (17/132)

Airway compliance is a key factor in understanding lung mechanics and is used as a clinical diagnostic index. Understanding such mechanics in small airways physiologically and clinically is critical. We have determined the "morphometric change" and "localized compliance" of small airways under "near"-physiological conditions; namely, the airways were embedded in parenchyma without dehydration and fixation. Previously, we developed a two-step method to visualize small airways in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam microfocal X-ray computed tomography system (Sera et al. J Biomech 36: 1587-1594, 2003). In this study, we used this technique to analyze changes in diameter and length of the same small airways ( approximately 150 microm ID) and then evaluated the localized compliance as a function of airway generation (Z). For smaller (<300-microm-diameter) airways, diameter was 36% larger at end-tidal inspiration and 89% larger at total lung capacity; length was 18% larger at end-tidal inspiration and 43% larger at total lung capacity than at functional residual capacity. Diameter, especially at smaller airways, did not behave linearly with V(1/3) (where V is volume). With increasing lung pressure, diameter changed dramatically at a particular pressure and length changed approximately linearly during inflation and deflation. Percentage of airway volume for smaller airways did not behave linearly with that of lung volume. Smaller airways were generally more compliant than larger airways with increasing Z and exhibited hysteresis in their diameter behavior. Airways at higher Z deformed at a lower pressure than those at lower Z. These results indicated that smaller airways did not behave homogeneously.  (+info)

Tracheal injury diagnosed with three-dimensional imaging using multidetector row computed tomography. (18/132)

Tracheobronchial injury is a rare and serious complication of blunt chest trauma. Diagnosis of this injury requires a high index of clinical suspicion. Delay in diagnosis is the single most important factor influencing the outcome. Diagnosis of this injury may be delayed because of subtle and nonspecific clinical and radiological findings and the much more overt clinical signs of other more-frequently associated injuries. Although the radiographic findings and axial computed tomographic (CT) findings of this type of injury have been reported in the literature, to the best of our knowledge. the use of 3-dimensional (3D) CT has never been reported. We report a case of such an injury demonstrated by multiplanar and 3D imaging using a multidetector row computed tomographic scanner. A large carinal laceration was clearly depicted on multiplanar and 3D CT images.  (+info)

Multidetector CT-generated virtual bronchoscopy: an illustrated review of the potential clinical indications. (19/132)

Multidetector computed tomography-generated virtual bronchoscopy (VB) is a recent technical development that allows visualisation of the lumen and wall of the trachea and proximal part of the bronchial tree. A dynamic image is produced that resembles what is seen with fibreoptic bronchoscopy (FB). Although the technique has not yet reached daily clinical practice and it can never replace FB, performing VB can be useful in well-defined clinical situations. In this paper, the value and limitations of virtual bronchoscopy will be reviewed, to illustrate the potential role of virtual bronchoscopy in the evaluation of trachea and bronchial tree pathology.  (+info)

Endobronchial ultrasound to assess airway wall thickening: validation in vitro and in vivo. (20/132)

Endobronchial ultrasound (EBUS) allows identification of airway wall structures and could potentially be utilised for in vivo studies of airway thickening in asthma. The present study investigated whether inflation of the fluid-filled balloon sheath over the transducer (necessary to provide sonic coupling with the airway wall) influenced in vitro measurements. In vivo comparability of EBUS with high resolution computed tomography scanning (HRCT), an established method for measuring wall thickness, was determined in control subjects. The airway diameter and wall thickness were studied using EBUS in 24 cartilaginous airways obtained from four sheep, before and after balloon sheath inflation during immersion in saline. To assess EBUS versus HRCT comparability of airway measures in vivo, 12 control subjects underwent imaging of the posterior basal bronchus of the right lower lobe by both techniques. Intra- and interobserver agreement were also assessed. Results with and without the balloon sheath gave comparable measures of airway internal diameter and wall thickness in vitro. Statistical analysis showed agreement between EBUS and HRCT, and intra- and interobserver variability in vivo. The current study concludes that endobronchial ultrasound, which does not present a radiation risk, could be utilised in the in vivo study of cartilaginous airway wall remodelling in respiratory diseases, such as asthma.  (+info)

Bronchiolitis obliterans after allogenic bone marrow transplantation: HRCT findings. (21/132)

OBJECTIVE: To evaluate the high resolution computed tomography (HRCT) findings of bronchiolitis obliterans (BO) after bone marrow transplantation (BMT). MATERIALS AND METHODS: During the past three years, 11 patients were diagnosed as having BO after BMT when they developed irreversible air flow obstruction, with an FEV(1) value of less than 80% of the baseline value, without any clinical evidence of infection. All 11 patients underwent HRCT, of whom eight also underwent follow-up HRCT. The HRCT images were assessed retrospectively for the presence of decreased lung attenuation, segmental or subsegmental bronchial dilatation, diminution of peripheral vascularity, centrilobular nodules, and branching linear structure on the inspiratory images. The lobar distribution of the decreased lung attenuation and bronchial dilatation was also examined. The presence of air trapping was investigated on the expiratory images. The interval changes of the HRCT findings were evaluated in those patients who had followup images. RESULTS: Abnormal HRCT findings were present in all cases; the most common abnormalities were decreased lung attenuation (n=11), subsegmental bronchial dilatation (n=6), diminution of peripheral vascularity (n=6), centrilobular nodules or branching linear structure (n=3), and segmental bronchial dilatation (n=3). Expiratory air trapping was noted in all patients. The decreased lung attenuation and bronchial dilatations were more frequent or extensive in the lower lobes. Interval changes were found in all patients with follow-up HRCT: increased extent of decreased lung attenuation (n=7); newly developed or progressed bronchial dilatation (n=4); and increased lung volume (n=3). CONCLUSION: HRCT scans are abnormal in patients with BO, with the most commonly observed finding being areas of decreased lung attenuation. While the HRCT findings are not specific, it is believed that their common features can assist in the diagnosis of BO in BMT recipients.  (+info)

Morphometric changes after thermal and methacholine bronchoprovocations. (22/132)

To determine whether there are distinctions in the location and pattern of response between different bronchoprovocations, we performed high-resolution computer-assisted tomography in 10 asthmatic subjects before and after isocapnic hyperventilation of frigid air (HV) and methacholine (Meth). The luminal areas of the trachea, main stem, lobar, and segmental bronchi were computed before and after each provocation and blindly compared. Both stimuli reduced the 1-s forced expiratory volume similarly (percent change in 1-s forced expiratory volume HV = 28.1 +/- 5.5%, Meth = 25.8 +/- 5.2%; P = 0.69) but did so in different fashions. Each provocation was associated with the development of both bronchial narrowing and dilation; however, more airways constricted with HV (67.7%) than with Meth (47.0%; P < 0.001). Furthermore, there was little concordance between either the magnitude or direction of change between stimuli in any region of the lung (r = 0.25). In general, the frequency of narrowing increased with branching. Constriction became more prominent in the lobar regions and increased further in the segmental branches, but a wide range of intensity existed. These data demonstrate that provocational stimuli evoke complex morphometric changes within the tracheobronchial tree and that different agonists produce different patterns. Thermal stimuli chiefly influence the segmental level, whereas the response to Meth develops more distally. Even within this distribution, the same airway does not respond in an identical fashion to different stimuli, so there does not appear to be a uniform trigger zone.  (+info)

Airway wall thickness in patients with COPD and healthy current smokers and healthy non-smokers: assessment with high resolution computed tomographic scanning. (23/132)

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction caused by emphysema or airway narrowing, or both. Recently airway dimensions have been measured using high-resolution computed tomography (HRCT). To evaluate large and small airway dimensions by HRCT and compare them with pulmonary function tests in patients with COPD and in smokers with or without airflow obstruction. METHODS: We used HRCT scanning to measure airway wall thickness at the segmental and sub-segmental levels in COPD patients (group II, stage II, n = 17, and group III, stage III, n = 5), healthy current smokers (group I, n = 10) and healthy non-smokers (group 0, n = 10). RESULTS: FEV1 was lower in patients with severe or moderate COPD than in healthy current smokers and non-smokers. FEV1 was lower in group I than group 0 (p < 0.005). There was no statistically significant difference between patients with moderate COPD and severe COPD in the ratio of airway wall thickness to outer diameter (T/D ratio) or the percentage wall area (WA%). Both groups II and III had higher T/D ratios than group I (p < 0.01), and group I had a higher T/D ratio than group 0 (p < 0.001). Both groups II and III had higher WA% than group I (p < 0.01 and p < 0.05, respectively), and group I had a higher WA% than group 0 (p < 0.001). A negative correlation was found between airway wall thickness and FEV1. CONCLUSIONS: Computed tomography measurements of large and small airway dimensions are useful for evaluating lung function in patients with COPD and healthy current smokers. Airway wall thickening is inversely related to the degree of airflow obstruction and positively related to cumulative smoking history.  (+info)

Computed tomography versus bronchography in the diagnosis and management of tracheobronchomalacia in ventilator dependent infants. (24/132)

AIM: To assess the relative accuracy of dynamic spiral computed tomography (CT) compared with tracheobronchography, in a population of ventilator dependent infants with suspected tracheobroncho-malacia (TBM). SETTING: Paediatric intensive care unit in a tertiary teaching hospital. PATIENTS AND METHODS: Infants referred for investigation and management of ventilator dependence and suspected of having TBM were recruited into the study. Tracheobronchography and CT were performed during the same admission by different investigators who were blinded to the results of the other investigation. The study was approved by the hospital research ethics committee, and signed parental consent was obtained. RESULTS: Sixteen infants were recruited into the study. Fifteen had been born prematurely, and five had cardiovascular malformations. In 10 patients there was good or partial correlation between the two investigations, but in six patients there was poor or no correlation. Bronchography consistently showed more dynamic abnormalities, although CT picked up an unsuspected double aortic arch. Radiation doses were 0.27-2.47 mSv with bronchography and 0.86-10.67 mSv with CT. CONCLUSIONS: Bronchography was a better investigation for diagnosing TBM and in determining opening pressures. Spiral CT is unreliable in the assessment of TBM in ventilator dependent infants. In addition, radiation doses were considerably higher with CT.  (+info)