Tracheobronchial tree: three-dimensional spiral CT with bronchoscopic perspective

Inhaled Foreign Bodies: Presentation, Management and Value of History and Plain Chest Radiography in Delayed Presentation

OBJECTIVES: To assess the clinical and management aspects of tracheobronchial foreign body (FB) in children and adults; to judge the influence of the operator's experience on the outcome of the procedure and to evaluate the factors associated with delayed diagnosis of FB aspiration (FBA) in children; and to compare clinical, radiologic and bronchoscopic findings in the patients with suspected FB inhalation (FBI).

STUDY DESIGN AND SETTING: Retrospective review of a 10-year experience (from 1995 to 2005), involving a 1512-bed Mansoura university hospital and a 184-bed Mansoura emergency hospital.

MATERIAL AND METHODS: Three thousand three hundred patients underwent rigid bronchoscopy for suspected FBI between 1995 and 2005 in Mansoura, Egypt. The data were analyzed in 3 groups: the patients with negative bronchoscopy for FBI (group 1), early (group 2), and delayed diagnosis (group 3). Foreign body was removed using the rigid bronchoscope with or without using the extracting forceps (Egyptian novel technique; Sersar technique).

RESULTS: The penetration syndrome and decreased breath sounds were determined in a significantly higher number of the patients with FBI. The plain chest radiography revealed radiopaque foreign bodies (FBs) in 23.56% of all patients with FBI. Pneumonia and atelectasis were more common in the groups with negative bronchoscopy and with delayed diagnosis ( P < 0.01). The FBs were mostly of vegetable origin, such as seeds and peanuts. The Egyptian novel (Sersar) technique was used since 2004 April in 100 cases (4.62%) with a history of FBI (pins and or small rounded materials). It was successful in 73 cases of nonimpacted inhaled pins.

CONCLUSIONS: Bronchoscopy is indicated on appropriate history and on suspicion. To prevent delayed diagnosis, characteristic symptoms, and clinical and radiologic signs of FBI should be checked in all suspected cases. Because clinical and radiologic findings of FBI in delayed cases may mimic other disorders, the clinician must be aware of the likelihood of FBI.

EBM rating: C-4

Computed tomography findings of tracheobronchial system diseases: a pictorial essay

The diseases affecting the trachea and main bronchi can be categorized into congenital or acquired abnormalities and also into focal or diffuse diseases. Major congenital bronchial abnormalities cover accessory cardiac bronchus and tracheal bronchus. Tracheobronchial strictures, such as post-intubation and post-infectious stenosis and tracheobronchial neoplasms are regarded as focal diseases, whereas tracheobronchomegaly, relapsing polychondritis, tracheobronchopathia osteochondroplastica, amyloidosis, granulomatosis with polyangiitis, tracheobronchomalacia, saber-sheath trachea and tracheobronchitis associated with ulcerative colitis are examples of diffuse diseases. Computed tomography (CT) is the best non-invasive method for evaluation of tracheobronchial lesions. In this pictorial review we aimed to demonstrate CT features of central airway diseases.

Virtual 18F-FDG PET/CT bronchoscopy for lymph node staging in non-small-cell lung cancer patients: present and future applications

Virtual (18)F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) bronchoscopies provide virtually realistic, 3D endoscopic views of the airways combining anatomical and functional data at a high resolution. Today, even very small airways can be imaged by virtual bronchoscopy. (18)F-FDG PET/CT bronchoscopy images are generated from standard whole-body (18)F-FDG PET/CT scan source data without any additional radiation exposure. The purpose of this review was to give an overview over the studies that are currently available, to provide the technical background of (18)F-FDG PET/CT bronchoscopy and to explain the diagnostic accuracy of (18)F-FDG PET/CT bronchoscopy. Moreover, this manuscript highlights potential future applications of this promising new imaging technique.

Virtual and fiber-optic bronchoscopy in patients with indication for tracheobronchial evaluation

OBJECTIVE

The aim of this study was to compare the results of virtual bronchoscopy (VB) images in defining tracheobronchial pathologies with those of fiber-optic bronchoscopy (FOB) in patients with clinical indication for bronchoscopy.

METHODS

Twenty-two patients with bronchoscopy indication were evaluated with FOB and VB. The VB results were evaluated blindly, independent of the FOB results.

RESULTS

In 19 of the 22 patients, tracheobronchial abnormalities were present on FOB, whereas 3 patients had normal findings on FOB. In 17 of 19 patients, VB demonstrated the FOB diagnosis of tracheobronchial abnormality. While FOB detected 11 endoluminal lesions, VB detected 6. While FOB detected 20 obstructive lesions, VB detected 26. In evaluating external compression, FOB detected 2 lesions and VB detected 15.

CONCLUSIONS

VB is a non-invasive, uncomplicated, and reproducible examination method in patients with an indication for thorax examination. Virtual bronchoscopy could find a clinically broader field of application in the future.

Rigid bronchoscopy for inhaled pen caps in children

PURPOSE

The aim of this study was to present the clinical findings and treatment of pen cap inhalation with emphasis on the importance of managing aspirated foreign bodies by rigid bronchoscopy.

METHODS AND PATIENTS

Of 1280 patients with foreign body inhalation treated from 1997 to 2007, 34 (2.65%) were because of pen cap inhalation. Medical records of these 34 patients were retrospectively reviewed and analyzed for age, sex, symptoms, location of pen cap, treatment, complications, and outcomes.

RESULTS

Of the 34 children with pen cap inhalation, 22 (64.7%) were boys and 12 (35.3%) were girls. They ranged in age from 6 to 14 years, pen caps were most frequently found in the right main stem bronchus (26 cases, 76.4%). A history of an episode of foreign body inhalation (34 cases, 100%) and acute cough (28 cases, 82.3%) were the most common presenting findings. All inhaled pen caps were successfully removed by reverse grasping forceps during rigid bronchoscopy. Tracheotomy, thoracotomy, and bronchotomy were not performed in any patients. There were no severe complications or deaths.

CONCLUSIONS

Pen cap inhalation mostly occurs in school-aged children. Patients usually can depict a clear history of pen cap inhalation, which is vital to early diagnosis. Inhaled pen caps can be removed safely by rigid bronchoscopy under general anesthesia combined with topical anesthesia. Open surgical techniques such as tracheotomy, thoracotomy, and bronchotomy can be avoided in most cases. More attention to programs of prevention, public and parent education, and awareness is needed to reduce the incidence of pen cap inhalation.

Tracheobronchial variations in Turkish population

The tracheobronchial tree exhibits highly individualistic features and many variations. As the anatomic variations among Turkish population have not been studied previously, we aimed to evaluate the type and frequency of tracheobronchial variations (TBVs) in our bronchoscopy population. In a 3-year period, 1,114 patients underwent flexible bronchoscopy (FB). Among these, 780 (70%) were male. The mean age of the patients was 51.3 +/- 15.1 (range: 17-84) years. In 639 cases, no TBV were detected. A total of 999 TBV were observed in 475 patients. Of all, 71.3% (713) of the total TBV were detected in males. Forty-nine and six-tenths percent (49.6%) of the TBV were observed on the right bronchial system, 49.2% on the left, and 1.2% in the trachea. The five most frequently observed TBV were right lower lobe basal orifice with two subsegments, left lower lobe basal orifice with two subsegments, left upper lobe with three segments, right upper lobe with two segments, and right lower lobe with a subapical segment. In the same lobe bronchus, single variation and two different TBV were seen in 85% and 15% of patients, respectively. Number of TBV increased linearly with the number of lobes involved. The availability and popularity of FB in recent years has led to the increase in identification and reporting of TBV. TBV should be correctly identified and documented. This information is invaluable during follow-up bronchoscopies as well as lung resection.

Correlative anatomy for thoracic inlet; glottis and subglottis; trachea, carina, and main bronchi; lobes, fissures, and segments; hilum and pulmonary vascular system; bronchial arteries and lymphatics

Because it is relatively inexpensive and universally available, standard radiographs of the thorax should still be viewed as the primary screening technique to look at the anatomy of intrathoracic structures and to investigate airway or pulmonary disorders. Modern trained thoracic surgeons must be able to correlate surgical anatomy with what is seen on more advanced imaging techniques, however, such as CT or MRI. More importantly, they must be able to recognize the indications, capabilities, limitations, and pitfalls of these imaging methods.

[Volume CT: recent advances in acquired abnormalities of the trachea]

OBJECTIVES

To show the recent improvements in CT imaging of the trachea due to the introduction of multidetector computed tomography (MDCT).

MATERIAL AND METHODS

MDCT technology, which was introduced in the early 00's, allows acquiring the entire airways within few seconds while using low dose parameters thanks to the natural high contrast of the airways.

RESULTS

Volume acquisition with isotropic voxels offers an excellent anatomical resolution in all directions, improving the quality of multiplanar reformations and 3D reconstructions, including virtual bronchoscopy. Therefore, the ability of CT for detecting and localizing tracheal abnormalities are improved, which is useful for planning endoscopy or open surgery, or assess their results. Dynamic acquisition during expiration is the last refinement permitted by MDCT, which is of value to detect tracheomalacia.

CONCLUSIONS

MDCT is a non-invasive technique to image the trachea. Its applications are numerous, such as depiction of anatomical or functional abnormalities, evaluation of local extent of the disease, planning and assessing open surgery or interventional endoscopy.

Airflow limitation and airway dimensions in chronic obstructive pulmonary disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation caused by emphysema and/or airway narrowing. Computed tomography has been widely used to assess emphysema severity, but less attention has been paid to the assessment of airway disease using computed tomography.

OBJECTIVES

To obtain longitudinal images and accurately analyze short axis images of airways with an inner diameter>or=2 mm located anywhere in the lung with new software for measuring airway dimensions using curved multiplanar reconstruction.

METHODS

In 52 patients with clinically stable COPD (stage I, 14; stage II, 22; stage III, 14; stage IV, 2), we used the software to analyze the relationship of the airflow limitation index (FEV1, % predicted) with the airway dimensions from the third to the sixth generations of the apical bronchus (B1) of the right upper lobe and the anterior basal bronchus (B8) of the right lower lobe.

MEASUREMENTS AND MAIN RESULTS

Airway luminal area (Ai) and wall area percent (WA%) were significantly correlated with FEV1 (% predicted). More importantly, the correlation coefficients (r) improved as the airways became smaller in size from the third (segmental) to sixth generations in both bronchi (Ai: r=0.26, 0.37, 0.58, and 0.64 for B1; r=0.60, 0.65, 0.63, and 0.73 for B8).

CONCLUSIONS

We are the first to use three-dimensional computed tomography to demonstrate that airflow limitation in COPD is more closely related to the dimensions of the distal (small) airways than proximal (large) airways.

Quantitative computed tomography of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is described as airflow limitation that is not fully reversible. Quantitative assessment of structural changes within the lung that are responsible for this airflow limitation has relied on the examination of tissue obtained from surgical or postmortem specimens. However, in the past two decades, researchers have developed novel and robust tools to measure the structure of the lung parenchyma and airway wall by using computed tomographic (CT) scans, which do not require the removal of lung tissue. These techniques are extremely important because they allow longitudinal studies of the pathogenesis of COPD and the assessment of therapeutic interventions. Another application of this approach is that it potentially allows phenotyping of individuals who predominately have emphysema or small-airway disease, which may be important for the evaluation of pathogenesis and prescription of treatment options. This review describes some of these CT techniques for quantitative assessment of lung structure.

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.

Effects of ECG Gating and Postprocessing Techniques on 3D MDCT of the Bronchial Tree

OBJECTIVE

Our goal was to determine the impact of ECG gating and different postprocessing techniques on 3D imaging of the bronchial tree. SUBJECTS AND METHODS. Retrospective ECG-gated MDCT and non-ECG-gated MDCT of the chest were performed in 25 patients. ECG-gated MDCT data were reconstructed mid diastole using a fixed interval of -400 msec in 25 patients and then additionally at -200, -300, and -500 msec in 10 of those patients. Shaded surface display and volume rendering of the bronchial tree combined with virtual bronchoscopy were performed using all data sets. The extent of bronchial tree visualization in shaded surface display-virtual bronchoscopy and volume rendering-virtual bronchoscopy and the presence of artifacts in volume-rendered images were scored by three blinded reviewers. The effective radiation doses of the ECG-gated and nongated acquisitions were compared.

RESULTS

The summary scores of all bronchial segments for gated shaded surface display-virtual bronchoscopy and gated volume rendering-virtual bronchoscopy did not differ significantly. The summary scores for nongated shaded surface display-virtual bronchoscopy and nongated volume rendering-virtual bronchoscopy were not significantly different. Non-gated acquisition yielded significantly better visualization of the bronchial tree for both post-processing techniques, regardless of the time interval used for reconstruction of the ECG-gated series. Artifact scores in volume-rendered images were significantly higher for ECG-gated MDCT compared with nongated MDCT. Effective radiation dose was significantly higher for the ECG-gated acquisition.

CONCLUSION

Given the advantage of volume rendering for representing the entire data set and given the lower radiation dose and better 3D image quality of nongated acquisition, volume rendering performed on nongated MDCT data is the method of choice for 3D visualization of the bronchial tree.

Diagnosis of a proximal tracheoesophageal fistula using three-dimensional CT scan: a case report

Missed proximal tracheoesophageal fistulas (TEF) after repair of an esophageal atresia (EA) with distal TEF are rare. The diagnosis usually is made on the basis of bronchoscopy and esophagoscopy, which can be inaccurate. Recent advances in computerized tomography (CT) have allowed saggital, coronal, and 3-dimensional reconstruction of any structure or organ. The authors report a case in which 3-dimensional CT was used to assist in the diagnosis of a missed proximal TEF in a 16-year-old girl.

CT virtual bronchoscopy in the evaluation of children with suspected foreign body aspiration

OBJECTIVE

Computed tomography (CT) virtual bronchoscopy is a noninvasive technique that provides an internal view of trachea and major bronchi by three-dimensional reconstruction. The aim of this study was to investigate the usefulness of virtual bronchoscopy in the evaluation of suspected foreign body aspiration in children.

MATERIALS AND METHODS

Twenty-three children (12 girls, 11 boys) with a mean age of 2.4 years (8 months-14 years) who were admitted to emergency room with a suspicion of foreign body aspiration were included in this study. Chest radiograms, spiral computed tomography scans and virtual bronchoscopy images were obtained. Then, rigid bronchoscopy was performed within 24 h.

RESULTS

CT virtual bronchoscopy and conventional bronchoscopy revealed the location of the foreign body in seven patients. It was in the right main bronchus in four patients, in the right lower lobe bronchus in one patient, and in the left main bronchus in two patients. There was no discordance between two modalities. CT examination revealed hyperaeration of the ipsilateral lung in four patients, hyperaeration of the ipsilateral lung and mediastinal shift in one patient and bronchiectatic changes in one patient. CT detected no additional finding in one patient with a foreign body in the right main bronchus. In 10 of 16 patients without foreign body, CT examination demonstrated atelectasis, infiltration, peribronchial thickening, and paratracheal lymphadenpoathy.

CONCLUSION

Helical CT scanning with virtual bronchoscopy should be performed in only selected cases with suspected foreign body aspiration. When the chest radiograph is normal and the clinical diagnosis suggests aspirated foreign body, helical CT and virtual bronchoscopy can be considered in order to avoid needless rigid bronchoscopy.

3-D imaging with MDCT

Without doubt, the greatest challenge of multidetector-row CT is dealing with 'data explosion'. For our carotid/intracranial CT angiograms, we routinely have 375 images to review (300 mm coverage reconstructed every 0.8 mm); for aortic studies we have 450-500 images ( approximately 600 mm coverage reconstructed every 1.3 mm); and for a study of the lower extremity inflow and run-off, we may generate 900-1000 transverse reconstructions. While we could reconstruct fewer images for these data, experience with single-detector row CT scanners indicates that longitudinal resolution and disease detection is improved when at least 50% overlap of cross-sections is generated [Radiology 200 (1996) 312]. If we are to optimize our clinical protocols and take full advantage of these CT scanners, we will need to change the way that we interpret, transfer, and store CT data. Film is no longer a viable option. Workstation based review of transverse reconstructions for interpretation is a necessity, but the workstations must improve to provide efficient access to these data, and we must have a way of providing our clinicians with images that can be transported to clinics and the operating room. Alternative visualization and analysis using volumetric tools, including 3-D visualization must evolve from luxury to necessity. We cannot rest on historical precedent to interpret these near isotropically sampled volumetric data using transverse reconstructions alone [Radiology 173 (1989) 527]. Although the tools for volumetric analysis on 3-D workstations have evolved over recent years, they have probably not yet evolved to a level that routine interpretation can be performed as efficiently and accurately as transverse section review. Both hardware and software developments must occur. While current computer workstations and visualization software are certainly adequate for assessing these MDCT data volumetrically, the process is very time consuming. What follows are a description of current workstation capabilities and a brief discussion of where development needs to go to facilitate the complete integration of volumetric analysis into the interpretive process of CT data.

CT virtual bronchoscopy of the central airways in patients with Wegener's granulomatosis

OBJECTIVES

To compare CT virtual bronchoscopy (VB) to CT alone and to conventional bronchoscopy for evaluation of central airway stenoses in patients with Wegener's granulomatosis.

DESIGN

Prospective observer study, in which 18 thin-section helical CT scans of the trachea and bronchi of 11 patients with Wegener's granulomatosis were obtained. VB was performed using surface rendering and was evaluated by one bronchoscopist and one radiologist in a blinded fashion. Bronchoscopic correlation within an average of 1.8 days of CT was available.

MEASUREMENTS AND RESULTS

VB displayed 188 of 198 bronchi (95%). Thirty-two of 40 stenoses (80%) were detected by VB by at least one of two physicians (double reading), and 22 of 40 stenoses (55%) were detected by a third physician reading only the CT.

CONCLUSIONS

VB depicts bronchi to the segmental level and detects the majority of central airway stenoses in patients with Wegener's granulomatosis. A team approach is useful to attain optimal clinical benefit from VB for these patients.

Transbronchial biopsy with virtual CT bronchoscopy and nodal highlighting

Transbronchial biopsy to sample lymph nodes and tumors that are not visible at endoscopy has a poor (<50%) success rate. These nodes can be highlighted easily at virtual computed tomographic (CT) bronchoscopy to provide a guide. This study was performed to evaluate if the addition of this information to the bronchoscopist improved the success rate of transbronchial biopsy of subcarinal and aortopulmonary lymph nodes. The addition of virtual CT bronchoscopy with lymph node highlighting significantly (P < .5) increased biopsy success rates for pretracheal, hilar, and high pretracheal adenopathy.

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.

Virtual tools for imaging of the thorax

Helical computed tomography (HCT) allows for volume acquisition of the entire thorax during a single apnoea. Combination of HCT acquisition with synchronous vascular enhancement gives rise to HCT angiography (HCTA). In the last decade, HCT and HCTA have revolutionized the diagnosis of thoracic diseases, modifying many diagnostic algorithms. Because HCT provides for a true volume acquisition free of respiratory misregistration, three-dimensional (3D) rendering techniques can be applied to HCT acquisitions. As these 3D rendering techniques present the HCT information in a different format to the conventional transaxial CT slices, they can be summarized as virtual tools. The purpose of this review is to give the readers the most important technical aspects of virtual tools, to report their application to the thorax, to answer clinical and scientific questions, and to stress their importance for patient management, clinical decision making, and research.

Mediastinal tumors

Mediastinal tumors are comprised of various benign and malignant neoplasms that share the same anatomic location within the thorax. The mediastinum is traditionally divided into three compartments: the anterior, middle, and posterior mediastinum. This division, based on lateral chest radiographs, helps clinicians establish appropriate differential diagnoses and plan further imaging, diagnostic, and treatment strategies. With the continued and complex advances in imaging, medical treatment, and surgery, we recommend a multidisciplinary approach to the management of mediastinal tumors. This discussion is intended to guide the pulmonary specialist through this potentially complex approach.

Virtual CT endoscopy of ossicles in the middle ear

The purpose of this study is to evaluate how virtual computed tomography (CT) endoscopy may help in assessing ossicles in the middle ear. Our series consisted of 96 ears of 68 consecutive patients with conducting hearing loss. All examinations were performed with a high-resolution spiral CT using axial and direct coronal planes of the temporal bone. Perspective virtual endoscopy was processed using the virtual endoscopic software. Superstructure of the stapes was difficult to evaluate on the virtual endoscopy; however, virtual endoscopy of the middle ear provides further information on the pathological conditions including congenital anomaly, posttraumatic, and inflammatory processes.

Virtual endoscopy

Virtual endoscopy is a technique in which three-dimensional viewing of hollow structures is conducted through the utilization of high-resolution imaging and unique computer processing methods. The basic components of this technique and its applications for urology and other clinical disciplines are reviewed.

Three-dimensional CT of congenital esophageal atresia and distal tracheoesophageal fistula in neonates: preliminary results

OBJECTIVE

Radiography was traditionally used in the preoperative treatment of neonates with tracheoesophageal atresia and tracheoesophageal fistula. The aim of this study was to assess the potential use of three-dimensional CT in the evaluation of this complex congenital malformation.

CONCLUSION

Three-dimensional CT coupled with reformations in the three orthogonal planes may have a complementary diagnostic role in congenital esophageal atresia.

Data explosion: the challenge of multidetector-row CT

The development of multi detector-row CT has brought many exciting advancements to clinical CT scanning. While multi detector-row CT offers unparalleled speed of acquisition, spatial resolution, and anatomic coverage, a challenge presented by these advantages is the substantial increase on the number of reconstructed cross-sections that are rapidly created and in need of analysis. This manuscript discusses currently available alternative visualization tecvhniques for the assessment of volumetric data acquired with multi detector-row CT. Although the current capabilities of 3-D workstations offer many possibilities for alternative analysis of MCDT data, substantial improvements both in automated processing, processing speed and user interface will be necessary to realize the vision of replacing the primary analysis of transverse reconstruction's with alternative analyses. The direction that some of these future developments might take are discussed.

Evaluating laryngotracheal stenosis in a canine model with virtual bronchoscopy

We performed a prospective masked animal study to determine whether virtual bronchoscopy, a noninvasive computed tomography technique, can accurately measure upper airway stenosis. Virtual bronchoscopy creates a 3-dimensional endoscopic image from spiral computed tomography data. Laryngotracheal stenosis was endoscopically induced in 18 dogs. The excised larynges were examined by endoscopy, virtual bronchoscopy, and macrodissection. Measurements were made of the anteroposterior (A-P) diameter, the left-right (L-R) diameter, the full length of stenosis in the sagittal plane, and the length of the tightest stenotic segment. Each measurement method was performed independently. All investigators were unaware of measurements made by others. The measurements obtained through virtual bronchoscopy and actual endoscopy were compared to those made at dissection by interclass correlation coefficients (ICCs). Endoscopy was better than virtual bronchoscopy in measuring the A-P diameter (ICC = .79, p < .0001; ICC = .42, p = .01). Both were equally effective in measuring the L-R diameter (ICC = .53, p = .0062; ICC = .52, p = .0064). The endoscopes could not assess the full length of the stenosis, whereas virtual bronchoscopy measured it fairly accurately (ICC = .72, p = .0001). Virtual bronchoscopy relatively accurately measured the length of the tightest stenotic segment (ICC = .68, p = .0002), whereas endoscopy produced measurements in only 11 of 18 larynges, and the measurements were less accurate (ICC = .45, p = .0068). Virtual bronchoscopy can provide good measurements of stenotic lesions in the airway. It is more accurate than actual endoscopy in determining the length of stenosis. It may therefore be useful as an adjunct imaging method in preoperative planning for reconstructive surgery.

Approach to pulmonary metastases

The prognosis and response to therapy of metastases to the lungs are variable and highly dependent on the origin of the primary tumor and on the extent and pattern of spread. Due to the complex pathogenesis underlying the development of pulmonary metastases, specific tumor types often display characteristic clinical and radiographic patterns. Understanding these concepts is of paramount importance when planning a diagnostic work-up for patients with possible pulmonary metastases. This review presents state of the art strategies in imaging, medical therapy, and surgery. It should provide the busy pulmonologist with the information needed to devise safe and efficient diagnostic and treatment strategies for patients with pulmonary metastases of extrathoracic origin.

Usefulness of CT virtual endoscopy in imaging a large esophagorespiratory fistula

A 73-year-old woman with a large esophagorespiratory fistula underwent bronchoscopy and computed tomographic (CT) virtual endoscopy before stenting. Noninvasive CT virtual endoscopy showed the large fistula, and the CT findings agreed with the bronchoscopic findings.

Esophageal atresia and tracheal stenosis: use of three-dimensional CT and virtual bronchoscopy in neonates, infants, and children

OBJECTIVE

The objective of this study was to evaluate the use of three-dimensional CT and virtual bronchoscopy in the treatment of neonates, infants, and children with esophageal atresia and tracheal stenosis.

CONCLUSION

Long-gap (n = 1) and short-gap (n = 5) esophageal atresia, long-segment stenosis (n = 2), patent poststenting trachea (n = 1), normal trachea without fistula (n = 1), and tracheal bronchus (n = 1) were studied. Fistulas between the lower esophagus and carina were noted in all six cases of esophageal atresia. All CT findings correlated with operative or bronchoscopy findings. Sensitivity and specificity were 100%. Three-dimensional CT and virtual bronchoscopy are accurate and useful techniques in the preoperative assessment of esophageal atresia and tracheal stenosis in neonates, infants, and children.

Evaluation of airway obstruction using virtual endoscopy

OBJECTIVES

This study examines the use of virtual endoscopy (VE) in the evaluation of patients with upper airway obstruction. The utility of VE compared with actual endoscopy was investigated with respect to accuracy of diagnosis and reproduction of endoscopic images.

STUDY DESIGN

A random cohort of 30 patients with various causes of airway obstruction was examined.

METHODS

The computed tomography (CT) data were reconstructed using a proprietary VE software program, FreeFlight, blind to the actual endoscopic findings. The cause of obstruction was identified and compared with actual endoscopic findings. This included 21 patients with airway stenoses, 8 patients with laryngotracheomalacia, 3 tracheal tumors, 2 glottic webs, 5 patients with innominate artery compression, 2 tracheal granulomas, and 7 patients with impaired true vocal cord mobility.

RESULTS

Virtual endoscopic evaluation was accurate in assessing stenosis width and length of fixed airway lesions. Correlation of stenosis shape and contour between actual endoscopy and VE was excellent. The stenosis-to-lumen ratios were compared between VE and actual endoscopy and were found to be within 10% (SD = 8). However, virtual endoscopic evaluation could not illustrate one of the glottic webs, half of the cases of tracheomalacia, or any of the cases of impaired true vocal cord mobility.

CONCLUSIONS

Virtual endoscopy was not as sensitive as actual endoscopy in detecting the cause of airway obstruction that was based on dynamic movement. However, VE was excellent for the measurement and definition of fixed airway lesions.

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

The aim of this study was to evaluate the diagnostic potential of virtual endoscopy (VE) and to compare it with axial CT slices, multiplanar reconstructions (MPR), minimal intensity projections (mIP), and bronchoscopy in patients diagnosed with bronchogenic carcinoma. Thirty patients underwent a spiral CT. Axial CT images were transferred to an Onyx workstation (Silicon Graphics, Sun Microsystems, Mountain View, Calif.) for performing virtual endoscopy. Accuracy for this procedure was tested by three radiologists on a monitor in comparison with axial CT slices, MPR, mIP, and bronchoscopy concerning the localization and degree of stenoses. Endoluminal tumors were identified by virtual bronchoscopy with no statistically significant difference of localization or grading of stenosis in comparison with bronchoscopy, axial CT slices, MPR and mIP. Axial CT slices, MPR, and mIP showed poorer results with over- or underestimation of stenoses compared with VE and bronchoscopy. Passing of stenoses was only possible with VE in 5 patients. Virtual endoscopy is a non-invasive method for identification of endoluminal tumors and is comparable to real bronchoscopy.

Virtual bronchoscopy

The sophistication of three-dimensional (3-D) radiographic imaging from CT data has accelerated with the development and ongoing advances of helical CT. Virtual bronchoscopy (VB), the ability to create 3-D models of the airways and navigate through the tracheobronchial tree lumen in realtime simulated bronchoscopy, has gained popularity over the past 3 years. The ability of VB to image the airway and mediastinal structures simultaneously and in a 3-D format has helped revolutionize CT imaging. Unlike conventional bronchoscopy, VB can display the extent of narrowing caused by an airway lesion, the presence of patentcy beyond a stenosis, and the relationship between an airway lesion and the adjacent mediastinal structures.

Virtual bronchoscopy

Three-dimensional endoluminal tracheobronchial simulations can be derived successfully from thoracic helical CT scans, and can reproduce the appearances of major endobronchial abnormalities confirmed during FB. The prospects of ever-faster CT scanners (capable of submillimeter resolution) merged with greater computer power make it likely that current versions of virtual bronchoscopy images will seem primitive in the future. Initial descriptive reports suggest great potential, but the startling visual appeal of these 3-D portrayals of a patient's airway and mediastinal anatomy and the prospects of exploring this information in real time do not establish its clinical role. Such virtual bronchoscopy findings are generally predictable on the basis of currently available axial CT images alone. The extent to which these 3-D endobronchial renderings improve the already high predictive values of CT requires critical study. In their patients with lung cancer Cicero et al observed that neither the staging nor diagnosis was modified substantially, but virtual bronchoscopy contributed to enhanced understanding of the pathology of the neoplastic process. Whether this added perspective translates to tangible benefits for patients is an intriguing possibility that has yet to be proved. The unique 3-D endobronchial view may offer particular advantages in some individuals and contribute to the patient's noninvasive evaluation. Because of the already high yield of conventional CT, diagnostic yield alone is not likely to be the sole best measure of this evolving technology. Accordingly, future multidisciplinary research investigations will also need to prospectively address nuances of decision-making and measure appropriate patient outcomes. In these efforts the active dialogue between chest clinician and radiologist will remain essential to defining and realizing the true potential of virtual bronchoscopy.

CT bronchoscopy

CT bronchoscopy with volumetric rendering can play a significant role in patients with mediastinal/hilar tumor and lymphadenopathy. By localizing (tagging) tumor foci on the axial images, volumetric rendering allows the tumors to be seen through normal-appearing mucosa. Such images can guide the bronchoscopist in finding the ideal site to biopsy and allow the bronchoscopist to become more aggressive in the biopsy of more difficulty positioned lesions. In addition, delineation of normal extraluminal vessels and other vital anatomical structures potentially decreases biopsy complications. Although further research is needed to prove the value of CT bronchoscopy, preliminary work performed to date by the author and others indicates great promise.

Virtual endoscopy for planning and simulation of minimally invasive neurosurgery

OBJECTIVE

This article demonstrates the usefulness and the problems of present-state software for virtual endoscopy as a tool for the planning and simulation of minimally invasive neurosurgical procedures.

METHODS

The software Navigator (General Electric Medical Systems, Buc, France) was applied for virtual endoscopic visualization of three-dimensional magnetic resonance data sets of healthy volunteers and neurosurgical patients, using a clinical magnetic resonance scanner (1.5-T Signa Hispeed; General Electric Medical Systems). Classical approaches for minimally invasive procedures were simulated.

RESULTS

Virtual endoscopy provided impressive three-dimensional views of intracranial and intracerebral cavities, with visualization of many anatomic details of the brain's inner and outer surfaces. The method proved to be especially suited for the simulation and planning of operations of intraventricular lesions, for which the technical limitations of the present state of development of this method have fewer implications. However, the present state of technology, as described in this article, has two major shortcomings: 1) the blood vessels cannot be visualized together with the brain tissue and cranial nerves; and 2) different tissue compartments cannot be stained in their original coloring, which would facilitate their recognition and thus orientation in space by anatomic landmarks. Another important disadvantage at this stage is time consumption for many single working steps.

CONCLUSION

Virtual endoscopy is a promising tool for teaching and training in intracranial neuroanatomy as well as for planning and simulation of minimally invasive (e.g., endoscopic), mainly intraventricular, operations. Direct clinical application is, at this stage of development, limited by several technical shortcomings of visualization and quantification of distances and modeling of surfaces.

Increasing spiral CT benefits with postprocessing applications

This paper reviews the current and future role of various postprocessing tools for epidemiologically important diseases. It introduces a generic business system for diagnosis and treatment using Spiral CT. Postprocessing of Spiral CT data should become a routine part of radiological practice. As viewing moves from film to monitor displays, interactive postprocessing tools support evaluation of CT studies and will in some cases also improve diagnostic accuracy. Track-ball controlled browsing through the volume data may be performed on axial images or on multiplanar reformats (MPR). These tools can be expected to become an integral part of most CT evaluations in the near future. Already now, MPR are important adjuncts for most orthopaedic applications. Presently, three-dimensional (3D) displays are used mainly in orthopaedic and trauma patients. In CT angiography, 3D surface displays and maximum intensity projections are routine display modalities. New volume rendering techniques (VRT) with interactive parameter changes will make 3D imaging of soft tissues feasible as well. The key input factor for many postprocessing applications will be Spiral CT data sets with high z-axis resolution (subsecond scanning, thin collimation, overlapping image reconstruction) and optimised application of contrast media. The most important benefit of postprocessing is the communication with the referring physician since 3D representations are becoming increasingly important for treatment planning and control. Postprocessing services will become a key ingredient of a successful radiological practice. If radiology does not provide it, the other physicians will do it themselves. For treatment simulation, virtual surgical instruments and tissue motion models are still in their infancy and will keep software architects and physicians busy for the next decade of Spiral-CT.

Bronchiectasis

Imaging has a key role in the identification of bronchiectasis. Over the years, imaging tests have become increasingly accurate in depicting the features of early bronchiectasis. This article covers the clinical, pathologic, and functional features of bronchiectasis; high-resolution CT scan technique; the signs of bronchiectasis on chest radiography and high-resolution CT scan; and the causes of misdiagnosis of bronchiectasis.

Three-dimensional endoscopic mode for observation of laryngeal structures by helical computed tomography

We produced high-quality three-dimensional (3D) endoscopic images of the larynx using helical scanning computed tomography. Subjects included two normal volunteers and 10 patients: five with laryngeal cancer, four with unilateral recurrent laryngeal nerve (RLN) palsy, and one with atrophied vocal folds. Two vertically split hemilaryngeal images were displayed together with the oral and tracheal views. Although motion artifacts were seen in four patients, laryngeal structures including the vocal fold, ventricular fold, and ventricle were clearly identified in all subjects. In the patients with cancer, axial images showing the extent of the tumor in each patient provided more information than 3D endoscopic images. In the patients with RLN palsy and atrophied vocal fold, combination of 3D endoscopic and cross-sectional images offered more diagnostic information than axial images alone.

Three-dimensional computed tomography bronchoscopy using clinical datasets: a comparison with fibreoptic bronchoscopy

OBJECTIVE

To assess three-dimensional computed tomography 'bronchoscopic' (3-DCTB) reconstruction of routine CT data as a non-invasive method of airway visualization, and compare it with fibreoptic bronchoscopy (FOB).

METHODS

Fourteen datasets were acquired from 13 patients undergoing both FOB and CT examination of the chest. Standard continuous volume CT using 6 mm collimation and clinical FOB techniques were employed. Images were obtained from 3-DCTB reconstructions by segmentation and surface recognition algorithms generating surface rendered 'bronchoscopic views'. These were scored for technical quality and anatomical detail. The most distal bronchi seen in left upper and right lower lobes were recorded for FOB and 3-DCTB.

RESULTS

On FOB, the subsegmental bronchi were seen in right lower and in left upper lobe in 10/14 cases and 4/14 cases, respectively. Visualization of the subsegmental airways was not achieved with 3-DCTB, as they could not be identified with confidence. 3-DCTB never achieved a more distal view than obtained by FOB. Using 3-DCT, the right, lower lobe segmental bronchi were seen in 10/14 cases, and lobar bronchus in 14/14 cases (two occluded). In the left upper lobe, 3-DCT showed segmental bronchi in 6/14 cases, lobar bronchus in 11/14 cases (one occluded) and the left main bronchus appeared occluded in 3/14 cases. Overall, technical quality and anatomical detail scores of the carina and proximal bronchi ranked significantly higher than views of segmental bronchi.

CONCLUSIONS

3-DCTB cannot routinely replace FOB for inspection of major and segmental bronchi. Subsegmental bronchi cannot be adequately demonstrated by 3-DCTB using 6 mm collimation datasets.