Spiral computed tomographic scanning of the chest with three dimensional imaging in the diagnosis and management of paediatric intrathoracic airway obstruction

Use of 3-Dimensional Computed Tomography Reconstruction Studies in the Preoperative Assessment of Patients Undergoing Balloon Dilatation for Tracheobronchial Stenosis

BACKGROUND

Balloon dilatation (BD) is a useful method of treating tracheobronchial stenosis (TBS); however, accurate preoperative identification of the lesion is difficult. Three-dimensional computed tomography (3D-CT) is an imaging method that may allow more accurate definition of the lesion(s) preoperatively.

STUDY OBJECTIVE

It is the aim of this study to present our finding using 3D-CT as a part of the preoperative evaluation of patients with TBS undergoing BD.

METHODS

We studied a prospective case series of 17 consecutive patients who underwent 29 BDs for TBS from a variety of benign and malignant causes at a tertiary care hospital. All patients had a preoperative spiral CT; these data were processed by a software program, VIDA, which was developed at this institution, and 3D-CT reconstruction images of the TBS were created. This enabled accurate preoperative anatomic definition of the lesion. The patients subsequently underwent BD.

RESULTS

All 17 patients had lesions identified with 3D-CT. Six patients had tracheal lesions and 12 patients had main stem lesions. One patient had combined tracheal and main stem lesions and 2 other patients had bilateral main stem lesions. Nine out of 17 patients required only one BD. One patient had a failed BD. The remaining 6 patients required more than one BD for optimal results (up to a maximum of 4). The follow-up period ranged from 1 to 34 months.

CONCLUSIONS

3D-CT offers accurate definition of TBS, including anatomic location, number of lesions present and status of airway distal to lesion. In this study, all preoperative lesions were correctly identified prior to BD.

Preoperative and postoperative evaluation of airways compression in pediatric patients with 3-dimensional multislice computed tomographic scanning: Effect on surgical management

OBJECTIVES

Surgical management of airway compression of vascular origin requires an accurate analysis of anatomy and various mechanisms of compression. This study assessed the usefulness of 3-dimensional computed tomographic scanning in the preoperative and postoperative evaluation of airways compression in a pediatric population.

METHODS

Thirty-seven consecutive patients (median age, 4 months) were examined with multislice 3-dimensional computed tomographic scanning: 18 patients before surgical treatment of anomalies of vascular rings, 2 patients because of respiratory symptoms after repair of esophageal atresia, and 17 patients because of persisting respiratory symptoms or prolonged mechanical ventilation after cardiac surgery for congenital heart disease.

RESULTS

The procedure was successful, with high-quality diagnostic imaging obtained in all cases without any complications. The anatomy and relationship between the vascular arches and airways was analyzed in all referred patients with vascular arch anomalies confirmed on the basis of the surgical findings, and this helped the surgeon to plan the procedure and choose the best approach. After cardiac surgery, the airway and vascular structures involved and the mechanism of compression were specified in all but one case, and the 3-dimensional computed tomographic scan serves as an important tool for deciding whether to perform reoperation on patients requiring prolonged mechanical ventilation.

CONCLUSION

Three-dimensional computed tomographic scanning is a safe, fast, and noninvasive method useful for accurately analyzing the mechanisms of airway compression of vascular origin and thus possible improving the surgical management of pediatric patients.

Usefulness of three-dimensional electron beam computed tomography for evaluating tracheobronchial anomalies in children with congenital heart disease

This study was undertaken to delineate tracheobronchial anomalies associated with congenital heart disease. From June 1995 to December 2000, 1,245 children with congenital heart disease underwent cardiac electron beam computed tomography with 3-dimensional reconstruction on an independent workstation. Tracheobronchial anomalies are strongly associated with congenital heart disease and accompanying tracheal stenosis is not uncommon. With 3-dimensional reconstruction, electron beam computed tomography provided excellent anatomic definition of the central tracheobronchial abnormalities.

Effects of childhood respiratory diseases on the anatomical and functional development of the respiratory system

The anatomical and functional development of the lung appears especially vulnerable to a whole range of insults during gestation and the first few years of life. A significant proportion of adult lung disease originates in utero or early infancy. Most publications on this topic are descriptive retrospective studies. An important limitation of these is that structural changes may precede abnormalities in lung function and development of symptoms. Little is known with certainty with respect to the long-term effects of early insults to the respiratory system. Furthermore, the reversibility of the functional and/or structural defects is hardly ever adequately investigated and it is probably not correct to extrapolate findings from adult studies to paediatric pulmonary diseases. Promoting or facilitating optimal lung growth in fetuses and infants and reducing the incidence of lower respiratory tract infection in infancy may reduce the incidence of adult chronic lung disease in generations to come.

Tetralogy of Fallot with absent pulmonary valve: a case complicated by bilateral relapsing pneumothorax

We report a case of a neonate with tetralogy of Fallot with aneurysmal dilatation of the pulmonary artery, complicated by bilateral relapsing pneumothorax. The relapsing air leak made it necessary to place up to five chest drains and to switch from conventional ventilation to high frequency ventilation. In the course of 30 days, all drains were removed. Once other anatomical and functional malformations of the respiratory system had been appropriately excluded and reasonable haemodynamic stability had been achieved, the patient underwent successful radical corrective heart surgery in hypothermia and cardioplegia. We emphasize the advantage of resolving respiratory failure preoperatively to guarantee the success of corrective heart surgery and treatment of other surgically severe cases.

Spiral CT optimization for measurement of bronchial lumen diameter using an experimental model

The aim of the study was to determine optimal parameters for demonstrating sublobar bronchi on spiral CT. Measurements were obtained from five parallel polyethylene tubes embedded in foam matrix with similar radiographic characteristics to segmental and subsegmental bronchi and to lung parenchyma, respectively. Collimation widths of 1.5, 2, 3 and 4 mm were used, with a pitch of 1 or 1.5 and a reconstruction interval of 1 mm or 2 mm. Various slice planes were used. Images acquired orthogonally were viewed normally. Images acquired in planes oblique or parallel to the long axes of the tubes were reformatted into a plane orthogonal to the long axes of the tubes to be comparable with the directly acquired orthogonal images. Tube diameters were measured at lung window settings (L, -400; W, 1300) and compared with known true inner and outer tube diameters. Measurements from images acquired orthogonal to the tube long axes were accurate regardless of slice thickness. Images acquired obliquely or parallel only produced accurate measurements at the lowest slice thickness (1.5 mm). Pitch and reconstruction interval had no effect on measurement error in any scan plane. It is concluded that a slice thickness of 1.5 mm or less, with a pitch of 1.5, should be used when acquiring images at angles other than orthogonal to the long axes of experimental tubes equivalent to the segmental and subsegmental bronchi. It is suggested that similar parameters should be used in vivo and that the examination should be targeted to the area of the bronchial tree in question to reduce patient dose and length of breath-hold.

Evaluation of tracheobronchial diseases: comparison of different imaging techniques

OBJECTIVE

To compare the clinical utility of the different imaging techniques used for the evaluation of tracheobronchial diseases.

MATERIALS AND METHODS

Forty-one patients with tracheobronchial diseases [tuberculosis (n = 18), bronchogenic carcinoma (n = 10), congenital abnormality (n = 3), post-operative stenosis (n = 2), and others (n = 8)] underwent chest radiography and spiral CT. Two sets of scan data were obtained: one from routine thick-section axial images and the other from thin-section axial images. Multiplanar reconstruction (MPR) and shaded surface display (SSD) images were obtained from thin-section data. Applying a 5-point scale, two observers compared chest radiography, routine CT, thin-section spiral CT, MPR and SSD imaging with regard to the detection, localization, extent, and characterization of a lesion, information on its relationship with adjacent structures, and overall information.

RESULTS

SSD images were the most informative with regard to the detection (3.95+/-0.31), localization (3.95+/-0.22) and extent of a lesion (3.85+/-0.42), and overall information (3.83+/-0.44), while thin-section spiral CT scans provided most information regarding its relationship with adjacent structures (3.56+/-0.50) and characterization of the lesion (3.51+/-0.61).

CONCLUSION

SSD images and thin-section spiral CT scans can provide valuable information for the evaluation of tracheobronchial disease.

Primary bronchomalacia and patent ductus arteriosus: simultaneous surgical correction in an infant

We report the clinical course of a 6-month-old girl with recurrent infection of the left lung, persistent wheezing, and a suspected congenital heart anomaly (patent ductus arteriosus. Chest radiography revealed hyperinflation and slight inflammation of the left lung. Tracheobronchoscopy and left-sided bronchography showed a collapsed segment of the left main bronchus, 3 cm long. Computed tomography confirmed hyperinflation of the left lung and atelectasis of the superior lobe. There were no signs of extramural compression. Color-flow Doppler echocardiography confirmed the suspicion of patent ductus arteriosus. To the best of our knowledge, there is no other report in the literature of a patient with this combination of anomalies. After receiving 2 weeks of antibiotic treatment, the patient underwent surgical repair The patent ductus arteriosus was closed by means of a triple-ligature procedure, and during the same operation a bronchopexy was performed, securing the left main bronchus to the closed ductus tissue by means of sutures. There have been no complications in the postoperative period. Clinical follow-up, as well as echocardiography and bronchoscopy, have yielded normal results 14 months after surgery.

Utility of spiral CT in minimally invasive approach for aortic valve replacement

OBJECTIVE

Several surgical approaches exist for a minimally invasive replacement of the aortic valve. A great concern exists about the variable exposure of the aortic root. We suggest the use of spiral CT as a non-invasive method for accurate determination of aortic annulus position.

METHODS

Three patients scheduled for minimally invasive aortic valve replacement underwent chest spiral CT, (Select SP, Elscint, Haifa, Israel). Scanning was performed during breath holding using 5-mm thick slices, reconstructed every 2 mm (3 mm overlap), and a 1.5 pitch. Average scanning time was 30 s. No intravenous contrast media was used. Multiplannar and 3D images were reconstructed, using an Omnipro work station (Elscint LTD, Haifa, Israel). The position of the aortic valve annulus, in relation to the anterior chest wall was defined on these images.

RESULTS

In all patients, the length and location of the incision were determined by the preoperative measurements. The location of the aortic valve was found highly correlative to the preliminary study. There was no need to extend the length of the incision, or change the surgical approach.

CONCLUSIONS

We find spiral CT scanning enables accurate pre-operative anatomical assessment. This assessment, provides the surgeon with the advantage of preliminary planning of the appropriate approach for minimally invasive aortic valve replacement.

Lung volume histograms after computed tomography of the chest with three-dimensional imaging as a method to substantiate successful surgical expansion of the rib cage in achondroplasia

The authors describe a radiographic method to quantify a surgical procedure of thoracic expansion in a 2-year-old patient with achondroplasia, small chest cage, and severe restrictive lung disease. The patient had undergone three surgical procedures of thoracic expansion since birth. The authors utilized computer-generated lung volume histograms after spiral computed tomographic scanning and three-dimensional imaging of the lungs to calculate his lung volumes before and after the third surgical thoracic expansion. The lung volumes, calculated by the histograms, were 363 mL and 406 mL before and after surgery, respectively. This 40-mL difference in the patient's lung volumes (4 mL/kg) accounted for a significant clinical improvement. Lung volume histograms obtained by this radiographic method are very helpful in substantiating a successful surgical chest expansion or provide an explanation for an unsuccessful repair.

Cystic fibrosis: when should high-resolution computed tomography of the chest Be obtained?

OBJECTIVE

To provide indications for high-resolution computed tomography (HRCT) of the chest in patients with cystic fibrosis (CF).

DESIGN

We compared the HRCT and conventional chest radiography (CCR) scores and assessed their correlation with clinical scores and pulmonary function tests.

SETTING

Department of Pediatrics, Federico II University, Naples, Italy.

SUBJECTS

A total of 30 patients with CF 6.75 to 24 years of age.

RESULTS

CCR scores correlated highly with HRCT (r = -0.8) and clinical (r = 0.5) scores, whereas total HRCT scores were not related to clinical scores. Of all the specific HRCT findings, only bronchiectasis appeared related significantly to the clinical score (r = 0.6). Most pulmonary function tests were related to CCR and total HRCT scores, but not to HRCT scoring of specific changes. Forced vital capacity and CCR scores appeared the best predictors of the HRCT score (multiple R = 0.58 and 0.79, respectively). In patients with mild lung disease, HRCT detected bronchiectasis and air trapping in 57% and 71% of the cases, respectively. In patients with more abnormal chest radiographs, bronchiectasis and air trapping were demonstrated on HRCT in all cases.

CONCLUSIONS

These findings suggest that HRCT of the chest is most useful in the identification of early lung abnormalities in patients with CF with mild respiratory symptoms, whereas for established disease, CCR is still the first-line imaging technique. The advantage of detecting early changes on CT imaging awaits additional confirmation, at least until early therapeutic interventions affecting significantly the final outcome of the disease are demonstrated. In patients with advanced disease, HRCT may be useful in the evaluation of specific lung changes when more aggressive treatment such as chest surgical interventions is indicated. Given the cost of the procedure and the high radiation dosage compared with CCR, a careful assessment of the cost:benefit ratios of HRCT is strongly recommended in CF.

Thin-section spiral volumetric CT for the assessment of lobar and segmental bronchial stenoses

Thin-section volumetric computed tomography (CT) was used to examine the lobar and segmental bronchi of five patients who had stenoses of these airways diagnosed by previous bronchography and/or bronchoscopy. Four of 23 lobar bronchi and 42 of 72 segmental bronchi were judged to be stenotic by CT. Our findings in this small group suggest that thin-section volumetric CT is a promising non-invasive technique that is likely to prove useful in the assessment of such stenoses in the future.