Diagnostic potential of virtual bronchoscopy: advantages in comparison with axial CT slices, MPR and mIP?

Utility of Virtual Bronchoscopy in Tracheal Tumors

Tracheal tumors are rare neoplasms, most of which are malignant. Conventional bronchoscopy (CB) and biopsy are used in the primary evaluation of these tumors, while Contrast-Enhanced Computed Tomography (CECT) is usually used for assessing extraluminal extension and nodal spread. Virtual bronchoscopy, created by postprocessing the three-dimensional volume data acquired from CECT, attempts to recreate the endoluminal features as seen in CB. The complexity of tracheal surgery necessitates accurate preoperative localization of the lesion and planning. It can assist in evaluation of patients in whom CB cannot be performed and for airway assessment in a preoperative setting. Although it cannot replace CB, it can be resorted to, in specific clinical scenarios. In this pictorial essay, we aim to highlight the technique, role, and clinical utility of Virtual Bronchoscopy (VB) in tracheal tumors.

Accuracy of Magnetic Resonance Imaging for Grading of Subglottic Stenosis in Patients With Granulomatosis With Polyangiitis: Correlation With Pulmonary Function Tests and Laryngoscopy

OBJECTIVE

To compare magnetic resonance imaging (MRI)-based and laryngoscopy-based subglottic stenosis (SGS) grading with pulmonary function testing (PFT) in patients with granulomatosis with polyangiitis (GPA).

METHODS

In this retrospective study, we included 118 examinations of 44 patients with GPA and suspected SGS. All patients underwent MRI, laryngoscopy, and PFT. Stenosis was graded on a 4-point scale by endoscopy and MRI using the Meyer-Cotton (MC) score (score 1: ≤50%, 2: 51-70%, 3: 71-99%, and 4: 100%) and as percentage by MRI. Results were compared with peak expiratory flow (PEF) and maximum inspiratory flow (MIF) from PFT, serving as objective functional reference.

RESULTS

In MRI, 112 of 118 examinations (95%) were rated positive for SGS (grade 1 [n = 82], grade 2 [n = 26], and grade 3 [n = 4]), whereas in laryngoscopy 105 of 118 examinations (89%) were rated positive for SGS (grade 1 [n = 73], grade 2 [n = 24], and grade 3 [n = 8]). MRI and laryngoscopy agreed in 75 of 118 examinations (64%). MRI determined higher scores in 20 examinations (17%) and lower scores in 23 examinations (19%) compared to laryngoscopy. MC scores as determined by both MRI and laryngoscopy showed comparable correlations with PEF (r = -0.363, P = 0.016, and r = -0.376, P = 0.012, respectively) and MIF (r = -0.340, P = 0.024, and r = -0.320, P = 0.034, respectively). The highest correlation was found between MRI-based stenosis grading in percentage with PEF (r = -0.441, P = 0.003) and MIF (r = -0.413, P = 0.005).

CONCLUSION

MRI and laryngoscopy provide comparable results for grading of SGS in GPA and correlate well with PFT. MRI is an attractive noninvasive and radiation-free alternative for monitoring the severity of SGS in patients with GPA.

Aortopexy with preoperative computed tomography and intraoperative bronchoscopy for patients with central airway obstruction after surgery for congenital heart disease: postoperative computed tomography results and clinical outcomes

Bronchoscopy-guided aortopexy is a surgical management option for patients with central airway obstruction after congenital heart surgery. This study aimed to evaluate the usefulness of bronchoscopy-guided aortopexy based on midterm follow-up evaluation with computed tomography (CT) and clinical outcome. From January 2004 to August 2011, bronchoscopy-guided aortopexy was performed for 16 patients (median age 0.5 years, M:F = 10:6) who had central airway obstruction caused by extrinsic compression (13 in the left main bronchus, 2 in the trachea, 1 in the diffuse trachea and bronchus) after congenital heart surgery. The surgical site for aortopexy was determined by the anatomic relationship between the aorta and the compressed bronchus according to preoperative CT and intraoperative bronchoscopy. The median follow-up period was 2.3 years. The ratios of the diameter and area of stenosis at the narrowed point were estimated using pre- and postoperative CT. Almost all the patients (15/16) showed relief of their preoperative symptoms. The median extubation time was 18 h. The stenosis diameter and area ratios significantly improved, as shown by with the immediate postoperative CT (7.7-48.5%, p = 0.003; 54.8-80.5%, p = 0.006). Airway stenosis of more than 75% (p = 0.013), immediate diameter ratio improvement of <50% (p = 0.015), preoperative severe respiratory insufficiency (p = 0.038), and male sex (p = 0.024) were associated with recurrent minor respiratory susceptibility. Bronchoscopy-guided aortopexy is a safe and reliable surgical management choice for central airway obstruction after congenital heart surgery. Furthermore, airway improvement after aortopexy was maintained during the midterm follow-up evaluation, according to CT measurements.

Traumatic intrathoracic tracheobronchial injuries: a study of 78 cases

BACKGROUND

Tracheobronchial injuries are encountered with increasing frequency because of improvements in pre-hospital care. We reviewed our experience of these injuries to determine how to better recognize them and facilitate their correct management.

METHODS

Patients with traumatic non-iatrogenic intrathoracic tracheobronchial injuries managed in 2 tertiary centers in Saudi Arabia between 2000 and 2012, were studied. Clinical presentation, diagnostic evaluation, management, and outcome were reviewed.

RESULTS

78 patients with tracheobronchial injuries were included in this study. They were divided into 2 groups according to the management strategy. Forty-seven patients who were managed conservatively, and 31 underwent surgery. Surgery allowed shorter intensive care unit and hospital stays; otherwise, the results were comparable between the two groups.

CONCLUSIONS

Early recognition and expedient appropriate management are essential in these potentially lethal injuries. Operative management can be achieved with acceptable mortality, and conservative treatment should be considered as a valuable alternative to the well-established surgical treatment.

Comparison of virtual bronchoscopy with fiberoptic bronchoscopy findings in patients exposed to sulfur mustard gas

BACKGROUND

Fiberoptic bronchoscopy (FB) is the best modality for evaluation of tracheobronchial endoluminal lesions. Virtual bronchoscopy (VB) with the aid of computed tomography (CT) makes it possible to reconstruct endoscopic-like visualization of major airways. Sulfur mustard (SM) used during the Iraq-Iran war affects respiratory tracts and can lead to tracheobronchial stenosis.

PURPOSE

To compare VB with FB in SM-exposed patients suspected for airway stenosis.

MATERIAL AND METHODS

Thirty-one patients were evaluated with CT and bronchoscopic studies about 15 years after chemical attacks. The median age of patients was 40 years. Spiral CT scans were obtained and data were transferred to a workstation to generate VB images of major airways. Less than one week after CT scan, FB was performed.

RESULTS

For the tracheal pathologies seen in FB, the sensitivity, specificity, and accuracy of VB was 90.9%, 95%, and 93.5% for tracheal stenosis, 40%, 96.2%, and 87.1% for vocal cord problems, 100%, 100%, and 100% for postoperative changes, and 100%, 96.7%, and 96.8% for intratracheal nodule. The inflammation of mucosal surface could not be assessed by VB. The bronchial pathologies seen in FB included eight cases of stenosis, and one case of nodule. Sensitivity, specificity, and accuracy of VB for detection of bronchial stenosis was 62.5%, 97.8% and 92.6%, respectively. Overall sensitivity, specificity and accuracy of VB in detecting tracheobronchial stenosis were 78.9%, 97.0%, and 92.9%, respectively.

CONCLUSION

Our study indicates that VB is an accurate method for evaluating stenoses, endoluminal nodules, and poststenotic areas within the tracheobronchial tree of SM-exposed victims. This complementary method could be helpful in revealing hidden post-stenotic lesions and also better depict the long tracheal strictures and their actual length.

Multidetector CT evaluation of central airways stenoses: Comparison of virtual bronchoscopy, minimal-intensity projection, and multiplanar reformatted images

Aims:

To evaluate the diagnostic utility of virtual bronchoscopy, multiplanar reformatted images, and minimal-intensity projection in assessing airway stenoses.

Settings and Design:

It was a prospective study involving 150 patients with symptoms of major airway disease.

Materials and Methods:

Fifty-six patients were selected for analysis based on the detection of major airway lesions on fiber-optic bronchoscopy (FB) or routine axial images. Comparisons were made between axial images, virtual bronchoscopy (VB), minimal-intensity projection (minIP), and multiplanar reformatted (MPR) images using FB as the gold standard. Lesions were evaluated in terms of degree of airway narrowing, distance from carina, length of the narrowed segment and visualization of airway distal to the lesion.

Results:

MPR images had the highest degree of agreement with FB (Κ = 0.76) in the depiction of degree of narrowing. minIP had the least degree of agreement with FB (Κ = 0.51) in this regard. The distal visualization was best on MPR images (84.2%), followed by axial images (80.7%), whereas FB could visualize the lesions only in 45.4% of the cases. VB had the best agreement with FB in assessing the segment length (Κ = 0.62). Overall there were no statistically significant differences in the measurement of the distance from the carina in the axial, minIP, and MPR images. MPR images had the highest overall degree of confidence, namely, 70.17% (n = 40).

Conclusion:

Three-dimensional reconstruction techniques were found to improve lesion evaluation compared with axial images alone. The technique of MPR images was the most useful for lesion evaluation and provided additional information useful for surgical and airway interventions in tracheobronchial stenosis. minIP was useful in the overall depiction of airway anatomy.

Interbronchoscopist variability in endobronchial path selection: a simulation study

BACKGROUND

Endobronchial path selection is important for the bronchoscopic diagnosis of focal lung lesions. Path selection typically involves mentally reconstructing a three-dimensional path by interpreting a stack of two-dimensional (2D) axial plane CT scan sections. The hypotheses of our study about path selection were as follows: (1) bronchoscopists are inaccurate and overly confident when making endobronchial path selections based on 2D CT scan analysis; and (2) path selection accuracy and confidence improve and become better aligned when bronchoscopists employ path-planning methods based on virtual bronchoscopy (VB).

METHODS

Studies of endobronchial path selection comparing three path-planning methods (ie, the standard 2D CT scan analysis and two new VB-based techniques) were performed. The task was to navigate to discrete lesions located between the third-order and fifth-order bronchi of the right upper and middle lobes. Outcome measures were the cumulative accuracy of making four sequential path selection decisions and self-reported confidence (1, least confident; 5, most confident). Both experienced and inexperienced bronchoscopists participated in the studies.

RESULTS

In the first study involving a static paper-based tool, the mean (+/- SD) cumulative accuracy was 14 +/- 3% using 2D CT scan analysis (confidence, 3.4 +/- 1.3) and 49 +/- 15% using a VB-based technique (confidence, 4.2 +/- 1.1; p = 0.0001 across all comparisons). For a second study using an interactive computer-based tool, the mean accuracy was 40 +/- 28% using 2D CT scan analysis (confidence, 3.0 +/- 0.3) and 96 +/- 3% using a dynamic VB-based technique (confidence, 4.6 +/- 0.2). Regardless of the experience level of the bronchoscopist, use of the standard 2D CT scan analysis resulted in poor path selection accuracy and misaligned confidence. Use of the VB-based techniques resulted in considerably higher accuracy and better aligned decision confidence.

CONCLUSIONS

Endobronchial path selection is a source of error in the bronchoscopy workflow. The use of VB-based path-planning techniques significantly improves path selection accuracy over use of the standard 2D CT scan section analysis in this simulation format.

A virtual bronchoscopic navigation system under X-ray fluoroscopy for transbronchial diagnosis of small peripheral pulmonary lesions

We had reported the utility of virtual bronchoscopic navigation system under CT-guidance for the diagnosis of small peripheral pulmonary lesions (PPLs). This study investigated the efficacy of virtual bronchoscopic navigation system for the diagnosis of small PPLs under X-ray fluoroscopy. We performed bronchoscopy with this system for 94 consecutive patients with 96 PPLs (< or =30mm in longest diameter; mean longest diameter, 16.2mm). A standard bronchoscope was used in 38 cases, and an ultrathin bronchoscope in 58 cases. Virtual bronchoscopic images were reconstructed from helical CT data. All the examinations were performed under X-ray fluoroscopy with virtual bronchoscopic navigation system, we referred both virtual bronchoscopic images and actual bronchoscopic images simultaneously to navigate the bronchoscopic pathway to the PPLs. Specimens for pathological examination were collected by transbronchial biopsy (TBB) and/or brushing. Virtual images accorded well with actual bronchoscopic images. The average total examination time was 24.1+/-7.4min (mean+/-S.D.). The overall diagnostic yields were 62.5% (60 of 96 PPLs), 71.1% (27 of 38 PPLs) with the standard bronchoscope, and 56.9% (33 of 58 PPLs) with the ultrathin bronchoscope. Diagnostic rates were 35%, 61.4% and 94.7% for lesions < or =10, 10-20, and >20mm, respectively. There were eight ground glass opacity (GGO) lesions confirmed only on CT scans; seven cases were pathologically diagnosed. All the examinations were performed safely with no complications. Bronchoscopy with virtual bronchoscopic navigation under X-ray fluoroscopy is useful for the diagnosis of small PPLs.

Tumoral and non-tumoral trachea stenoses: evaluation with three-dimensional CT and virtual bronchoscopy

BACKGROUND

We evaluated the ability of 3D-CT and virtual bronchoscopy to estimate trachea stenosis in comparison to conventional axial CT and fiberoptic bronchoscopy, with a view to assist thoracic surgeons in depicting the anatomical characteristics of tracheal strictures.

METHODS

Spiral CT was performed in 16 patients with suspected tracheal stenoses and in 5 normal subjects. Tracheal stenoses due to an endoluminal neoplasm were detected in 13 patients, whilst post-intubation tracheal stricture was observed in the other 3 patients. Multiplanar reformatting (MPR), volume rendering techniques (VRT) and virtual endoscopy (VE) for trachea evaluation were applied and findings were compared to axial CT and fiberoptic bronchoscopy. The accuracy of the procedure in describing the localization and degree of stenosis was tested by two radiologists in a blinded controlled trial.

RESULTS

The imaging modalities tested showed the same stenoses as the ones detected by flexible bronchoscopy and achieved accurate and non-invasive morphological characterization of the strictures, as well as additional information about the extraluminal extent of the disease. No statistically significant difference was observed between the bronchoscopic findings and the results of axial CT estimations (P = 1.0). No statistically significant differences were observed between bronchoscopic findings and the MPR, VRT and VE image evaluations (P = 0.705, 0.414 and 0.414 respectively).

CONCLUSION

CT and computed generated images may provide a high fidelity, noninvasive and reproducible evaluation of the trachea compared to bronchoscopy. They may play a role in assessment of airway patency distal to high-grade stenoses, and represent a reliable alternative method for patients not amenable to conventional bronchoscopy.

Do technical parameters affect the diagnostic accuracy of virtual bronchoscopy in patients with suspected airways stenosis?

PURPOSE

Virtual bronchoscopy has gained popularity over the past decade as an alternative investigation to conventional bronchoscopy in the diagnosis, grading and monitoring of airway disease. The effect of technical parameters on diagnostic outcome from virtual bronchoscopy has not been determined. This meta-analysis aims to estimate accuracy of virtual compared to conventional bronchoscopy in patients with suspected airway stenosis, and evaluate the influence of technical parameters.

MATERIALS AND METHODS

A MEDLINE search was used to identify relevant published studies. The primary endpoint was the "correct diagnosis" of stenotic lesions on virtual compared to conventional bronchoscopy. Secondary endpoints included the effects of the technical parameters (pitch, collimation, reconstruction interval, rendering method, and scanner type), and date of publication on the diagnostic accuracy of virtual bronchoscopy.

RESULTS

Thirteen studies containing 454 patients were identified. Meta-analysis showed good overall diagnostic performance with 85% calculated pooled sensitivity (95% CI 77-91%), 87% specificity (95% CI 81-92%) and area under the curve (AUC) of 0.947. Subgroups included collimation of 3mm or more (AUC 0.948), pitch of 1 (AUC 0.955), surface rendering technique (AUC 0.935), and reconstruction interval of more than 1.25 mm (AUC 0.914). There was no significant difference in accuracy accounting for publication date, scanner type or any of the above variables. Weighted regression analysis confirmed none of these variables could significantly account for study heterogeneity.

CONCLUSION

Virtual bronchoscopy performs well in the investigation of patients with suspected airway stenosis. Overall sensitivity and specificity and diagnostic odds ratio for diagnosis of airway stenosis were high. The effects of pitch, collimation, reconstruction interval, rendering technique, scanner type, and publication date on diagnostic accuracy were not significant.

Accuracy of Virtual Bronchoscopy for Grading Tracheobronchial Stenosis

STUDY OBJECTIVES

To compare the accuracy of virtual bronchoscopy (VB) with fiberoptic bronchoscopy (FOB) and pulmonary function testing (PFT) for the assessment of tracheal stenosis and bronchial anastomotic stenosis.

DESIGN

Prospective case series.

SETTING

Pulmonary institute of major tertiary university-affiliated center.

PATIENTS

The study group included 10 lung transplant recipients and 13 patients with central airway stenosis.

INTERVENTIONS

All patients underwent PFT, VB, and FOB. All cases were graded by each modality on a scale of 1 to 3, and the findings were compared between modalities.

RESULTS

Mean +/- SD stenosis score was 2.0 +/- 0.79 for PFT, 1.62 +/- 0.73 for FOB, and 1.82 +/- 0.77 for VB. A statistically significant correlation was found between VB and FOB scores (p < 0.0001, r = 0.76) and between VB scores and PFT (p = 0.03, r = 0.45). There was no correlation between PFT and FOB.

CONCLUSIONS

VB grading of tracheobronchial stenosis is well correlated with PFT. VB may be used to evaluate patients with known tracheobronchial stenosis after treatment and thereby reduce the frequency of repeated invasive FOB performed for that purpose. The correlation of VB with PFT may improve the reliability of this approach.

Virtual Bronchoscopy: Accuracy and Usefulness—An Overview

Multidetector CT generated virtual bronchoscopy (VB) represents one of the most recent developments in three-dimensional (3D) visualization techniques which allows a 3D evaluation of the airways down to the sixth- to seventh-generation. In comparison with real bronchoscopy, VB has some advantages: it is a non-invasive procedure that can visualize areas inaccessible to the flexible bronchoscope. Virtual bronchoscopy is able to evaluate bronchial stenosis and obstruction caused by both endoluminal pathology (tumor, mucus, foreign bodies) and external compression (anatomical structures, tumor, lymph nodes), can be helpful in the preoperative planning of stent placement and can be used to evaluate surgical sutures after lung transplantations, lobectomy or pneumectomy. In children, in some indications, VB can replace fiber optical bronchoscopy (FB) when this technique is considered too invasive. Finally, VB can also be used to evaluate anatomical malformations and bronchial variants. Virtual bronchoscopy is accurate but its accuracy is not 100% because false-positives and false-negatives occur. Virtual bronchoscopy contributes to a better understanding of tracheo-bronchial pathology. Fiber optical bronchoscopy will, without doubt, remain the golden standard but it can be expected that in the near future, the technique of VB will find a place in the daily routine.

The relationship between solitary pulmonary nodules and bronchi: multi-slice CT-pathological correlation

AIM

To investigate the relationship between solitary pulmonary nodules (SPN) and bronchi and its value in predicting the nature of the SPN.

MATERIALS AND METHODS

We performed volumetric targeted scans of 0.5 mm collimation with multi-slice computed tomography (MSCT), reconstructing multiplanar reconstructions (MPR), curved multiplanar reconstructions (CMPR) and surface-shaded display (SSD) images of bronchi in 78 consecutive patients with SPN (53 malignant and 25 benign) and correlated the findings with those of macroscopic and microscopic specimens.

RESULTS

With this CT protocol, the third to seventh-order bronchi were shown continuously and very clearly in all patients. CT findings were consistent with those of specimens. CT demonstrated the relationship between the SPN and bronchi in 46 (86.8%) malignant and 18 (75.0%) benign nodules. Five types of tumour-bronchus relationships were identified with MSCT. Type I: the bronchus was obstructed abruptly by the SPN; type II: the bronchus penetrated into the SPN with tapered narrowing and interruption; type III: the bronchial lumen shown within the SPN was patent and intact; type IV: the bronchus ran around the periphery of the SPN with intact lumen; type V: the bronchus was displaced, compressed and narrowed by the SPN. Malignant nodules were most commonly of type I (58.5%), secondly of type IV (26.4%) and rarely of type V (1.9%). Benign nodules were most often of type V (36.0%), followed by type III (20.0%), type I (16.0%), and there were no type II. Types I, II and IV were more common in malignant nodules, whereas type V was seen more frequently seen in benign nodules (p<0.05). There was no statistically significant difference between the two groups regarding type III.

CONCLUSION

Ultra-thin section with MSCT and MPR, CMPR and SSD reconstruction can improve the demonstration of the patterns of tumour-bronchus relationships, which can reflect the pathological changes of the nodules to some extent and help differentiate malignant from benign tumours.

Is Virtual Bronchoscopy an Efficient Diagnostic Tool for the Thoracic Surgeon?

Virtual bronchoscopy has emerged over the past decade as a potentially complementary investigation to conventional bronchoscopy in the diagnosis, grading, and monitoring of pulmonary disease. A meta-analysis reporting on the use of virtual bronchoscopy has not yet been performed. The primary aim of this study is to evaluate its diagnostic accuracy compared to the gold standard investigation of conventional bronchoscopy (fiberoptic or rigid). Quantitative data synthesis included the calculation of independent sensitivity and specificity, construction of summary receiver operating characteristic curves, pooled analysis, and sensitivity analysis. Seventeen studies were identified comprising 459 patients. The calculated pooled sensitivity was 84% (95% CI, 78% to 89%), specificity 75% (95% CI, 62% to 85%) and area under the curve was 0.92, which shows good diagnostic performance. Meta-analysis confirms virtual bronchoscopy is very discriminating in the evaluation of patients with significant airway stenosis that is due to a wide spectrum of pathologic conditions. It can potentially have a beneficial role in selected thoracic patients (with bronchoesophageal fistulas, postlung transplantation, anastomoses, and suspected foreign body aspiration).

High resolution volume imaging of airways and lung parenchyma with multislice CT

The value of multislice CT (MSCT) in imaging the peripheral airways and lung parenchyma has not been widely investigated. In this article the authors' experience in the use of MSCT (4-slice scanner) in imaging patients with suspected parenchymal lung disease or airways abnormalities will be presented. The technique described should be modified with the more modern 8-slice or 16-slice scanners. The whole thorax is scanned contiguously using 4 x 1 mm collimation from the lung bases up to apices in end-inspiration while the patient is in the prone position. Collimation of 2 x 0.5 mm is used at 8-10 levels evenly spaced in expiratory scans and also in the breathless patient who is scanned during gentle breathing. High resolution images of the lungs (1 mm slice thickness) are reconstructed in the following planes: axial (10 mm apart from apices to bases), coronal (six evenly spaced through the chest) and sagittal (four images evenly spaced through each lung). Paddlewheel reconstruction is used if further assessment of the airways is required, and three-dimensional imaging is used mainly for assessment of the trachea and major bronchi. Contiguous axial images (10 mm slice thickness) of the whole lung and mediastinum are also produced and referred to as a screenogram. Axial images of 1 mm slice thickness are produced with expiratory scans and for breathless patients. All the images are produced independently by the radiographic staff and are provided as hard copies (20 frames/film) for reporting. However, if facilities are adequate, direct reporting from the workstation is more effective in reviewing large number of images. The technique is effective in assessment of infiltrative lung disease, emphysema, bronchiectasis and central airways. The screenogram offers comprehensive evaluation of the lung and mediastinum, but the radiation dose associated with high resolution volume imaging remains a source of concern.

Peripheral anatomic evaluation using 3D CT hepatic venography in donors: significance of peripheral venous visualization in living-donor liver transplantation

OBJECTIVE

The purpose of this study was to determine clinical roles for 3D CT hepatic venography in the evaluation of peripheral hepatic venous anatomy during living-donor liver transplantation.

MATERIALS AND METHODS

Subjects comprised 54 donors (age range, 20-60 years) who had undergone surgery to donate a liver for transplantation. Visualization of each hepatic venous branch and total visualization using 3D CT hepatic venography were evaluated. Maximum venous branch order visualized was graded as nil, first branch, second branch, or third branch or more. The distance between the hepatic surface and the tip of each hepatic venous branch was classified as 0-5 mm, 6-10 mm, 11-15 mm, 16-20 mm, or 21-25 mm. Quality of total 3D CT hepatic venography was evaluated subjectively as poor, good, fair, or excellent. Dominance of large hepatic veins in the right lobe, peripheral branching pattern of the middle hepatic vein, and branching pattern of the vein draining segment IVb were also assessed.

RESULTS

Most hepatic venous branches (96.2% [275/286]) were visualized up to at least the second-order branches, and 93.7% (268/286) of branches were within 10 mm of the hepatic surface. As for total visualization, 98% (53/54) of cases were regarded as excellent. The dominant vein in the right lobe was the right hepatic vein in 27 cases, inferior hepatic vein in 25, and middle hepatic vein in one. The branching pattern of the middle hepatic vein was type 1 in 36 cases, type 2 in nine, and type 3 in eight. Segment IVb vein branched from the middle hepatic vein in 20 patients, and from the left hepatic vein in 34.

CONCLUSION

Because 3D CT hepatic venography visualizes peripheral hepatic venous branches in detail, the technique is useful for determining operative indications in living-donor liver transplantation.

Transthoracic CT-guided biopsy with multiplanar reconstruction image improves diagnostic accuracy of solitary pulmonary nodules

OBJECTIVE

To evaluate the utility of multiplanar reconstruction (MPR) image for CT-guided biopsy and determine factors of influencing diagnostic accuracy and the pneumothorax rate.

MATERIALS AND METHODS

390 patients with 396 pulmonary nodules underwent transthoracic CT-guided aspiration biopsy (TNAB) and transthoracic CT-guided cutting needle core biopsy (TCNB) as follows: 250 solitary pulmonary nodules (SPNs) underwent conventional CT-guided biopsy (conventional method), 81 underwent CT-fluoroscopic biopsy (CT-fluoroscopic method) and 65 underwent conventional CT-guided biopsy in combination with MPR image (MPR method). Success rate, overall diagnostic accuracy, pneumothorax rate and total procedure time were compared in each method. Factors affecting diagnostic accuracy and pneumothorax rate of CT-guided biopsy were statistically evaluated.

RESULTS

Success rates (TNAB: 100.0%, TCNB: 100.0%) and overall diagnostic accuracies (TNAB: 96.9%, TCNB: 97.0%) of MPR were significantly higher than those using the conventional method (TNAB: 87.6 and 82.4%, TCNB: 86.3 and 81.3%) (P < 0.05). Diagnostic accuracy were influenced by biopsy method, lesion size, and needle path length (P < 0.05). Pneumothorax rate was influenced by pathological diagnostic method, lesion size, number of punctures and FEV1.0% (P < 0.05).

CONCLUSION

The use of MPR for CT-guided lung biopsy is useful for improving diagnostic accuracy with no significant increase in pneumothorax rate or total procedure time.

Virtual bronchoscopy for evaluation of airway disease

The data presented above indicate that VB is a novel and extremely useful modality for airway evaluation in patients who have benign and malignant disease. VB is noninvasive, with no additional radiation exposure relative to standard CT scans of the chest. Commercial software allows for the interactivity of 2D and 3D images. The ability to examine 2D and 3D anatomic detail from multiple directions enables precise assessment of intraluminal and extraluminal pathology. The authors' experience indicates that VB is a superb modality for assessing the length of airway stenoses and ascertaining airway patency distal to these lesions (Fig. 6). As such, VB has proven to be extremely useful for determining the feasibility of endobronchial procedures such as dilations, stent placements, and laser ablation of endobronchial tumors. Ferretti et al [27] observed that VB is an excellent noninvasive means for long-term monitoring of tracheobronchial stents. Furthermore, the authors have found VB useful for guiding the bronchoscopic evaluation of patients who have intermittent hemoptysis secondary to lesions in peripheral airways. The 3D anatomic detail provided by VB has proven useful for assessing the feasibility of lung-sparing procedures in patients who have limited pulmonary reserve and for sequentially evaluating treatment response in patients who have inoperable disease. Currently, the main limitation of VB pertains to its inability to evaluate the mucosal surface of the respiratory tract reliably. Although form can be detected, mucosal color, irregularity, or friability cannot be assessed. As such, VB cannot be used for routine surveillance of patients at high risk of developing airway malignancies. The development of novel aerosolized contrast agents or spectroscopic techniques that can discriminate benign versus malignant mucosal tissues might enhance the sensitivity and specificity of VB for the detection of preinvasive cancers within the respiratory tract.

Evaluation of tracheobronchial anomalies in children using low-dose multidetector CT: report of a 13-year-old boy with a tracheal bronchus and recurrent pulmonary infections

Tracheobronchial anomalies in children may be associated with recurrent episodes of pulmonary infections and symptoms of recurrent or persistent airway obstruction. Diagnosis by conventional imaging may be difficult. Multidetector computed tomography (MDCT) offers the possibility to generate a virtual three-dimensional bronchoscopy, thus enabling detailed overview of the tracheobronchial system. We report on a 13-year old boy, admitted to hospital after recurrent episodes of bronchial infections. Functional studies showed airway obstruction with no response to bronchodilators. A chest radiograph was normal. Flexible bronchoscopy revealed tracheobroncho malacia of the distal trachea and the right main bronchus. The ostium of an accessory right-sided tracheal bronchus, which could not be entered by the endoscope, was also detected. MDCT using a low-dose protocol was performed on a four-section scanner (Somatom Volume Zoom, Siemens, Erlangen, Germany). A three-dimensional virtual bronchoscopy based on surface rendering was generated, which confirmed moderate narrowing of the trachea and right main bronchus. Furthermore, an accessory and stenotic tracheal bronchus including poststenotic segments, ventilating parts of the right upper lobe, could be clearly visualized. MDCT can be a valuable instrument in the diagnostic pathway of assessing tracheobronchial anomalies in children, including visualization of poststenotic bronchial structures. The use of low-dose protocols provides adequate image quality to perform virtual bronchoscopy, thus reducing administered radiation to a tolerable amount.

Accuracy of virtual bronchoscopy to detect endobronchial lesions

BACKGROUND

Virtual bronchoscopy (VB) could obviate flexible bronchoscopy (FB) if no endobronchial lesion is detected in patients presenting with a suspicion of malignancy. Our objectives were to evaluate the accuracy (in terms of sensitivity and specificity) of VB in detecting endobronchial lesions, and to determine the anatomical limit of detection of endobronchial lesions by VB.

METHODS

This study involved, in a blind comparison of VB and FB, consecutive patients presenting with symptoms or plain chest radiography abnormalities raising the suspicion of pulmonary neoplasm. After the standard chest computed tomography (CT), additional helical CT data were acquired from the aortic arch to the origin of the segmental bronchi of the inferior lobes in one 20-second breath hold using an helicoidal CT scan (3.0-mm collimation with a pitch of 1.5 and 1.5-mm reconstruction intervals).

RESULTS

One hundred ninety patients were enrolled; 136 patients (including 63 with an endobronchial lesion at FB) contributed to the primary analysis. The sensitivity and specificity of VB to detect endobronchial lesions were 68% (95% confidence interval [CI]: 55% to 79%) and 90% (95% CI: 81% to 96%), respectively. Overall, the agreement between VB and FB regarding the location on endobronchial lesions was substantial (weighted kappa: 0.66). However, VB detected only 26 of the 34 lobar lesions (sensitivity: 76%; CI: 59% to 89%) and 11 of the 23 segmental lesions (sensitivity: 48%; CI: 27% to 69%).

CONCLUSIONS

Beyond the mainstem bronchi, VB is not accurate enough to detect endobronchial lesions and to obviate FB in patients presenting with a suspicion of malignancy.

Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy

OBJECTIVE

To assess the sensitivity of noninvasive virtual bronchoscopy based on multirow detector CT scanning in detecting and grading central and segmental airway stenosis using flexible bronchoscopic findings as the reference standard.

MATERIALS AND METHODS

In a blinded controlled trial, multirow detector CT virtual bronchoscopy and flexible bronchoscopy were used to search for and grade airway stenosis in 20 patients. CT scan data were obtained with a multirow detector CT scanner using 4 x 1 mm collimation. Flexible bronchoscopy findings were graded by a pulmonologist and served as the reference standard for 176 central airway regions (ie, trachea, main bronchi, and lobar bronchi) and 302 segmental airway regions. The extent of airway narrowing was categorized as grade 0 (no narrowing), grade 1 (< 50%), or grade 2 (> or =50%).

RESULTS

Flexible bronchoscopy revealed 30 stenoses in the central airways and 10 in the segmental airways. Virtual bronchoscopy detected 32 stenoses in the central airways (sensitivity, 90.0%; specificity, 96.6%; accuracy, 95.5%) and 22 in the segmental airways (sensitivity, 90.0%; specificity, 95.6%; accuracy, 95.5%). The number of false-positive findings was higher in the segmental airways (13 false-positive findings) than in the central airways (5 false-positive findings), which caused a lower positive predictive value for the segmental airways (40.9%) than for the central airways (84.4%). Flexible and virtual bronchoscopic gradings correlated better for central airway stenosis (r = 0.87) than for segmental airway stenosis (r = 0.61).

CONCLUSION

Although a high sensitivity was found for the detection of both central and segmental airway stenosis, the number of false-positive findings was higher for segmental airways. However, noninvasive multirow detector CT virtual bronchoscopy enables high-resolution endoluminal imaging of the airways down to the segmental bronchi.

Comparative evaluation of super high-resolution CT scan and virtual bronchoscopy for the detection of tracheobronchial malignancies

OBJECTIVES

Novel imaging modalities are currently available for the noninvasive evaluation of the tracheobronchial tree. This study was undertaken to compare the diagnostic potentials of conventional CT scanning, super high-resolution CT (SHR-CT) scanning, and virtual bronchoscopy (VB) directly with fiberoptic bronchoscopy (FB) for the detection of tracheobronchial neoplasms.

DESIGN

Prospective observer study, in which 44 consecutive patients with thoracic malignancies were evaluated using several diagnostic imaging modalities. Images of the thorax were interpreted by individuals blind to the results of FB for the detection of endoluminal, obstructive, or mucosal lesions.

MEASUREMENTS AND RESULTS

Image acquisition and simulation of the tracheobronchial anatomy were created successfully in all patients. Thirty-two patients who underwent both SHR-CT scanning and VB had correlative FBs within 1 month. In all nine patients who had a normal anatomy, SHR-CT scanning and VB accurately correlated with the FB findings. However, CT scanning demonstrated two false-positive obstructive lesions in one patient. Twenty-three patients had a total of 35 abnormal FB findings. The sensitivities of SHR-CT scanning and VB for the detection of endoluminal, obstructive, and mucosal lesions were 90%, 100%, and 16%, respectively. The overall sensitivities and specificities of SHR-CT scanning and VB were 83% and 100%, respectively. In contrast, CT scanning had sensitivities of 50%, 72%, and 0% for the detection of endoluminal, obstructive, and mucosal lesions with an overall sensitivity and specificity of 59%, and 85%, respectively. There was no case in which conventional CT scanning was better at detecting lesions than either SHR-CT scanning or VB.

CONCLUSIONS

SHR-CT scanning and VB are accurate, noninvasive methods for identifying obstructions and endoluminal lesions within the respiratory tract. Thus, these novel imaging techniques are valuable as complementary modalities to FB, providing information that is useful for the detection and management of airway malignancies.

[Low dose multislice CT in the pediatric patient]

In the past years, multislice CT (MS-CT) has become an important diagnostic modality for the radiological evaluation of the thorax in children and adolescents. However, the higher stochastic radiation risks in pediatric patients, as compared to adults, necessitate a prudent use of MS-CT. This article presents an overview of the benefits of multislice CT and a variety of possibilities for radiation reduction in pediatric patients of different ages.

Multiplanar and three-dimensional multi-detector row CT of thoracic vessels and airways in the pediatric population

Multi-detector row computed tomography (CT) has changed the approach to imaging of thoracic anatomy and disease in the pediatric population. At the author's institution, multi-detector row CT with multiplanar and three-dimensional reconstruction has become an important examination in the evaluation of systemic and pulmonary vasculature and the tracheobronchial tree. In some clinical situations, multi-detector row CT with reformatted images is obviating conventional angiography, which is associated with higher radiation doses and longer sedation times. Although multi-detector row CT with multiplanar and three-dimensional reconstruction is expanding the applications of CT of the thorax, its role as a diagnostic tool still needs to be better defined. The purposes of this article are to describe how to perform multi-detector row CT with multiplanar and three-dimensional reconstruction in young patients, to discuss various reconstruction techniques available, and to discuss applications in the evaluation of vascular and airways diseases.

Virtual bronchoscopy for evaluation of malignant tumors of the thorax

OBJECTIVE

Virtual bronchoscopy is a novel technique making use of 3-dimensional reconstruction of 2-dimensional helical computed tomographic images for noninvasive evaluation of the tracheobronchial tree. This study was undertaken to evaluate the diagnostic potential of virtual bronchoscopy by comparing virtual bronchoscopic images with fiberoptic bronchoscopic findings in patients with thoracic malignant disease.

METHODS

Thirty-two consecutive patients with thoracic malignant tumors underwent virtual bronchoscopy for evaluation of suspected tracheobronchial lesions. For each virtual bronchoscopic examination, 200 to 300 contiguous 1.25-mm images of the thorax were obtained in only one or two 17-second breath holds by using a multislice computed tomographic scanner. Virtual bronchoscopy images were reconstructed and interpreted blind to the actual endoscopic findings. Results of virtual bronchoscopy were compared with fiberoptic bronchoscopic findings in 20 patients.

RESULTS

Anatomic computer simulation of the bronchial tree was successfully created in all patients. In 7 (35%) of 20 patients, results of fiberoptic bronchoscopy were found to be within normal limits. In all patients with normal anatomy, virtual bronchoscopy accurately correlated with the fiberoptic findings. Thirteen (65%) patients had a total of 22 abnormal findings on fiberoptic bronchoscopy. Virtual bronchoscopy detected 18 of 22 abnormal fiberoptic bronchoscopic findings: 13 of 13 obstructive lesions, 5 of 6 endoluminal lesions, and 0 of 3 mucosal lesions. The sensitivity of virtual bronchoscopy was 100% for obstructive lesions, 83% for endoluminal lesions, 0% for mucosal lesions, and 82% for all abnormalities; the specificity of virtual bronchoscopy was 100%.

CONCLUSIONS

Preliminary evaluation indicates that virtual bronchoscopy may be a promising and noninvasive modality for identifying bronchial obstructions and endoluminal lesions, as well as for assessing the tracheobronchial tree beyond stenoses. However, at present, virtual bronchoscopy does not enable the detection of subtle mucosal lesions, and as such, this modality may not be appropriate for identifying premalignant lesions in the respiratory tract. Although fiberoptic bronchoscopy remains the standard modality for evaluating airway patency and mucosal lesions, virtual bronchoscopy may provide additional information that may be useful in the management of pulmonary malignant tumors.

Multidetector CT virtual bronchoscopy to grade tracheobronchial stenosis

OBJECTIVE

The purpose of this study was to compare the efficacy of noninvasive multidetector CT (virtual bronchoscopic images, axial CT slices, coronal reformatted images, and sagittal reformatted images) in depicting and allowing accurate grading of tracheobronchial stenosis with that of flexible bronchoscopy.

MATERIALS AND METHODS

Multidetector CT and flexible bronchoscopy were used to examine 200 bronchial sections obtained from 20 patients (15 patients with bronchial carcinoma and five without central airways disease). Multidetector CT was performed using the following parameters: collimation, 4 x 2 mm, pitch, 1.375; and reconstruction intervals, 2 mm. Postprocessing was performed using surface rendering and multiplanar reformatted images. CT images were independently interpreted by two radiologists. The tracheobronchial stenoses revealed on flexible bronchoscopy were graded by a pulmonologist.

RESULTS

Virtual bronchoscopic findings, axial CT scans, and multiplanar reformatted images were highly accurate (98% accuracy for virtual bronchoscopic images, 96% for axial slices and coronal reformatted images, and 96.5% for sagittal reformatted images) in revealing tracheobronchial stenosis. In allowing accurate grading of tracheobronchial stenosis, images from virtual bronchoscopy correlated closely (r = 0.91) with those of flexible bronchoscopy. Because use of virtual bronchoscopic images reduced the overestimation of stenosis, these images allowed better assessment of stenosis than did axial CT slices (r = 0.84) or multiplanar reformatted images (r = 0.84) alone.

CONCLUSION

Multidetector CT virtual bronchoscopy is a reliable noninvasive method that allows accurate grading of tracheobronchial stenosis. However, it should be combined with the interpretation of axial CT images and multiplanar reformatted images for evaluation of surrounding structures and optimal spatial orientation.

Virtual coronary angioscopy using multislice computed tomography

BACKGROUND

With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualisation of human coronary arteries with diagnostic image quality. In addition to conventional axial slices, virtual coronary angioscopies (VCA) can be reconstructed using MSCT datasets.

OBJECTIVE

To evaluate the feasibility of reconstructing VCA and to determine the clinical value of this new application in detecting atherosclerotic coronary artery lesions.

METHODS

Datasets obtained by contrast enhanced non-invasive coronary angiography using MSCT (Somatom VZ) were analysed from 14 consecutive patients. VCA were simulated in 14 coronary arteries (left anterior descending, n = 7; right coronary, n = 7). Lesion detection was undertaken on conventional contrast enhanced axial slices, as well as by VCA. Intracoronary ultrasound (ICUS) was used as the gold standard for in vivo plaque detection.

RESULTS

38 lesions were detected both on ICUS and on axial slices: 14 severe target lesions of > 75% area stenosis (11 calcified, three non-calcified), and 24 intermediate lesions of < or = 75% area stenosis (seven calcified, 17 non-calcified). Using VCA, all severe lesions (n = 14) and all calcified intermediate plaques (n = 7) could clearly be identified. However, non-calcified intermediate lesions (n = 17) could not be accurately distinguished from the vessel wall; they were recognised as vessel wall alterations without significant luminal narrowing.

CONCLUSIONS

Current MSCT technology allows reconstruction of VCA with good image quality. Despite a more anatomical view of heart and coronary vessels on three dimensional reconstruction, conventional axial slices were found to be superior for detecting coronary lesions. Thus further technical innovations are required before VCA can become a useful technique in clinical cardiology.

Detection of the residual lumen of intracranial aneurysms immediately after coil embolization by three-dimensional digital subtraction angiographic virtual endoscopic imaging

OBJECTIVE

Detection of a small residual lumen after coil embolization is often difficult because of the coil mass and the overlap of the cerebral arteries. The purpose of this study was to assess the usefulness of virtual endoscopic (VE) analysis of three-dimensional digital subtraction angiographic (DSA) images for evaluation of aneurysmal occlusion immediately after the procedure.

METHODS

Twenty-seven intracranial aneurysms were treated with coil embolization using a three-dimensional DSA system. Biplane and rotational DSA scanning was performed before and immediately after the procedures. VE images were obtained at a separate workstation, after transfer of the rotational images. Two-dimensional (2D) DSA images and VE images obtained after the procedure were assessed with respect to aneurysmal occlusion. Morphological outcomes and other factors, including location, size, volumetric ratio (coil volume/aneurysm volume), and residual sites, were also evaluated.

RESULTS

Seven aneurysms were evaluated as complete occlusion (CO) on both 2D DSA images and VE images. Twelve aneurysms exhibited residual lumina on both 2D DSA images and VE images. Five aneurysms were evaluated as CO on 2D DSA images and as incomplete occlusion on VE images. There were no recurrences among the aneurysms that were evaluated as CO on VE images. Two of five aneurysms that were evaluated as CO on 2D DSA images and as incomplete occlusion on VE images demonstrated regrowth in follow-up examinations. Residual sites and volumetric ratios were correlated with aneurysmal regrowth.

CONCLUSION

VE imaging can demonstrate a residual lumen more frequently than can 2D DSA imaging and is useful for evaluating aneurysmal occlusion after coil embolization.

Virtual endoscopy in the diagnosis of an adult double tracheal bronchi case

We report a case of ipsilateral double tracheal bronchi supplying a tracheal lobe in a 42-year-old man, who presented with a 10-year history of recurrent respiratory infections. Diagnosis was established by chest computed tomography (CCT), virtual endoscopy and bronchoscopy. Both bronchi were surgically resected along with the right upper lobe of the lung and the associated tracheal lobe. To our knowledge, this is the first report of ipsilateral double tracheal bronchi in the adult life to be diagnosed and treated on the basis of modern radiological techniques and especially virtual endoscopy findings.