Clinical applications of 2D and 3D CT imaging of the airways--a review

Evolution of Three-Dimensional Computed Tomography Imaging in Thoracic Surgery

Radiologic reconstruction technology allows the wide use of three-dimensional (3D) computed tomography (CT) images in thoracic surgery. A minimally invasive surgery has become one of the standard therapies in thoracic surgery, and therefore, the need for preoperative and intraoperative simulations has increased. Three-dimensional CT images have been extensively used, and various types of software have been developed to reconstruct 3D-CT images for surgical simulation worldwide. Several software types have been commercialized and widely used by not only radiologists and technicians, but also thoracic surgeons. Three-dimensional CT images are helpful surgical guides; however, in almost all cases, they provide only static images, different from the intraoperative views. Lungs are soft and variable organs that can easily change shape by intraoperative inflation/deflation and surgical procedures. To address this issue, we have developed a novel software called the Resection Process Map (RPM), which creates variable virtual 3D images. Herein, we introduce the RPM and its development by tracking the history of 3D CT imaging in thoracic surgery. The RPM could help develop a real-time and accurate surgical navigation system for thoracic surgery.

No-Reference-Based and Noise Level Evaluations of Cinematic Rendering in Bone Computed Tomography

Cinematic rendering (CR) is a new 3D post-processing technology widely used to produce bone computed tomography (CT) images. This study aimed to evaluate the performance quality of CR in bone CT images using blind quality and noise level evaluations. Bone CT images of the face, shoulder, lumbar spine, and wrist were acquired. Volume rendering (VR), which is widely used in the field of diagnostic medical imaging, was additionally set along with CR. A no-reference-based blind/referenceless image spatial quality evaluator (BRISQUE) and coefficient of variation (COV) were used to evaluate the overall quality of the acquired images. The average BRISQUE values derived from the four areas were 39.87 and 46.44 in CR and VR, respectively. The difference between the two values was approximately 1.16, and the difference between the resulting values increased, particularly in the bone CT image, where metal artifacts were observed. In addition, we confirmed that the COV value improved by 2.20 times on average when using CR compared to VR. This study proved that CR is useful in reconstructing bone CT 3D images and that various applications in the diagnostic medical field will be possible.

Identification of anatomical types of segmental bronchi in left superior and lingular lobes using multi-slice CT

PURPOSE

The objectives of this study were to evaluate various branching patterns of segmental bronchi in the left superior and lingular lobes and to survey the anatomical diversity and sex-related differences of these branches in a large sample of the study population.

MATERIALS AND METHODS

Overall, 10,000 participants (5428 males, and 4572 females, mean age 50 ± 13.5 years [SD] years; age range: 3-91 years) who underwent multi-slice CT (MSCT) scans between September 2019 and December 2021 were retrospectively included. Using the syngo.via post-processing workstation, the data were applied to generate three-dimensional (3D) and virtual bronchoscopy (VB) simulations of a bronchial tree. The reconstructed images were then interpreted to identify and categorize distinct bronchial patterns in the left superior and lingular lobes. Cross-tabulation analysis and the Pearson Chi-square (χ2) test were used to calculate the constituent ratios of bronchial branch types and determine their significance between male and female groups.

RESULTS

Our results revealed mainly four distinct types for the left superior lobe (LSL) bronchial tree, i.e., (B1 + 2, B3, 76.13%); (B1 + 2 + 3, 17.32%); (B1 + 3, B2, 5.74%); (B1a + B3, B1b + B2, 0.81%) and two types for the left lingular lobe (LLL) bronchial tree, i.e., (B4, B5, 91.05%); (B4, B5, B*, 8.95%). There were no significant sex-related differences in the proportion of bronchial branches in LLL (P > 0.05). However, sex-related differences were significant in the proportion of bronchial branches in LSL (P < 0.05).

CONCLUSION

The current study has validated the presence of segmental bronchial variations in the left superior and lingular lobes. These findings may have a crucial effect on the diagnosis of symptomatic patients, as well as in carrying out procedures such as lung resections, endotracheal intubation, and bronchoscopies.

The Role of 3D Printing in Treatment Planning of Spine and Sacral Tumors

Three-dimensional (3D) printing technology has proven to have many advantages in spine and sacrum surgery. 3D printing allows the manufacturing of life-size patient-specific anatomic and pathologic models to improve preoperative understanding of patient anatomy and pathology. Additionally, virtual surgical planning using medical computer-aided design software has enabled surgeons to create patient-specific surgical plans and simulate procedures in a virtual environment. This has resulted in reduced operative times, decreased complications, and improved patient outcomes. Combined with new surgical techniques, 3D-printed custom medical devices and instruments using titanium and biocompatible resins and polyamides have allowed innovative reconstructions.

Identification of anatomical types of segmental bronchi in right middle lobe using multi-slice CT

PURPOSE

The objectives of this study were to evaluate the various branching patterns of segmental bronchi in the right middle lobe (RML) and to survey the anatomical diversity and sex-related differences of these branches in a large sample of the study population.

MATERIALS AND METHODS

In this retrospective board-approved study with informed consent, 10,000 participants (5428 males and 4,572 females, mean age 50 ± 13.5 years [SD]; age range: 3-91 years) who underwent multi-slice CT (MSCT) scans from September 2019 to December 2021 were retrospectively included. The data were applied to generate three-dimensional (3D) and virtual bronchoscopy (VB) simulations of a bronchial tree using the syngo.via post-processing workstation. The reconstructed images were then interpreted to locate and classify distinct bronchial patterns in the RML. Cross-tabulation analysis and the Pearson chi-square test were used to calculate the constituent ratios of bronchial branch types and determine their significance between male and female groups.

RESULTS

Our results revealed that the segmental bronchial ramifications of the RML were classified into two types mainly, i.e., bifurcation (B4, B5, 91.42%) and trifurcation (B4, B5, B*, 8.58%). There were no significant sex-related differences in the proportion of bronchial branches in the RML (P > 0.05).

CONCLUSION

The current study has confirmed the presence of segmental bronchial variations in the RML lobe using 3D reconstruction and virtual bronchoscopy. These findings may have significant implications for the diagnosis of symptomatic patients and for carrying out specific procedures like bronchoscopy, endotracheal intubation, and lung resection.

Three-dimensional label-free histological imaging of whole organs by microtomy-assisted autofluorescence tomography

Three-dimensional (3D) histology is vitally important to characterize disease-induced tissue heterogeneity at the individual cell level. However, it remains challenging for both high-throughput 3D imaging and volumetric reconstruction. Here we propose a label-free, cost-effective, and ready-to-use 3D histological imaging technique, termed microtomy-assisted autofluorescence tomography with ultraviolet excitation (MATE). With the combination of block-face imaging and serial microtome sectioning, MATE can achieve rapid and label-free imaging of paraffin-embedded whole organs at an acquisition speed of 1 cm3 per 4 h with a voxel resolution of 1.2 × 1.2 × 10 μm3. We demonstrate that MATE enables simultaneous visualization of cell nuclei, fiber tracts, and blood vessels in mouse/human brains without tissue staining or clearing. Moreover, diagnostic features, including nuclear size and packing density, can be quantitatively extracted with high accuracy. MATE is augmented to the current slide-based 2D histology, holding great promise to facilitate histopathological interpretation at the organelle level.

Investigation of the applicability of virtual gastroscopy based on postmortem computed tomography to detect changes in the stomach, along with reports of three rare cases

Postmortem computed tomography is now being used more commonly for routine forensic investigation. The use of 3D reconstruction techniques including virtual gastroscopy is effective and also improves the speed of interpretation, recognition, and description of specific clinical conditions. However, it has been unclear whether postmortem virtual endoscopy could be applicable for medicolegal autopsy or whether it could complement pathological examination at autopsy. Here, we investigated the applicability of postmortem virtual gastroscopy by reviewing 295 medicolegal autopsy cases seen at our institution, and found four cases in which the technique had been able to demonstrate features corresponding to changes that were evident at autopsy. Thus,postmortem virtual gastroscopy would have only rarely been effective forvisualizing any change in the stomach in such cases. In addition, we describe in detail three of those cases in which virtual gastroscopy had been able to visualize changes in the stomach, including a gastric ulcer, a polyp, and the presence of foamy fluid, which were all verified at autopsy. In those cases, virtual gastroscopy was useful for understanding features in the stomach of the deceased, which were revealed by axial images of the abdomen, to forensic pathologists who were not familiar with PMCT 2D images. Taken together, our findings suggest that postmortem virtual gastroscopy might help facilitate clear, straightforward sharing of information about PMCT images of complex anatomical structures among radiologists and forensic pathologists, as well as non-medical professionals with a limited knowledge of anatomy and physiology.

Traumatic Airway Injuries: Role of Imaging

Airway Injuries are rare but often immediately life threatening. Incidence ranges from 0.5-2 % in blunt and 1-6 % in penetrating trauma. Upper airway injuries (UAI) are often clinically apparent and get shunted during the primary survey in the emergency department. Few UAI and majority of lower airway injuries (LAI) are occult on primary survey and need a high suspicion index. Clinically, the diagnosis of tracheobronchial injury is delayed in many patients because the airway column is maintained by the peribronchial tissue. Imaging in the form of MDCT, in conjunction with endoscopy, plays a role in delineating the exact site and extent of injury and ruling out associated vascular and esophageal injuries for definitive management of UAI. Chest radiographs and ultrasonography help raise suspicion of LAI by detection of pneumomediastinum, persistent pneumothorax and/or subcutaneous emphysema and should be followed up with multidetector computed tomography (MDCT) which is the mainstay of diagnosis. However, it requires careful evaluation of the airway tract and a thorough knowledge about the mechanism of trauma for detection of subtle injuries. Reconstructions in multiple planes and use of various post-processing techniques including minimum intensity projection (MinIP) images enhance the detection rate. The specific signs of LAI on CT include discontinuity in the tracheobronchial tree, focal intimal flap projecting in the lumen, focal soft tissue attached to the tracheal/bronchial wall, complete cut off of the bronchus/trachea and the fallen lung sign. We, hereby, illustrate the imaging spectrum of traumatic airway injuries in detail and discuss their management implications.

Variations of right bronchial tree: a study with multi-detector CT

PURPOSE

The aim was to display variations of right bronchial tree.

METHODS

The bronchial tree images of 238 patients were reconstructed using the postprocessing technique of CT.

RESULTS

We revealed four cases rare bronchial branching patterns of right superior lobe. 1 case was referred to as tracheal bronchus. In 1 case, B1 was located in the place of the right superior lobar bronchus and B2 + 3 arose from the right merge of the IB. In 1 case, the right superior lobar bronchus has only two divisions for B1 and B3, and the bronchus B2 arose from the right merge of the IB. In 1 case, B1 branched into four bronchi. We revealed 15 cases of rare bronchial branching patterns of right inferior lobe. In nine cases, the basal trunk bronchus bifurcated into B7 + 8 and B9 + l0. In three cases, B8 branched from the basal trunk bronchus before B7. In two cases, basal trunk bronchus bifurcated into B7 + 8 + 9 and B10. In 1 case, the basal trunk bronchus bifurcated into the common stem of B7 + 10 and B8 + 9.

CONCLUSIONS

Variations of right bronchial tree were displayed in the present study. This information may have important implications for diagnosis of symptomatic patients and performing certain procedures, including bronchoscopy, endotracheal intubation, and lung resection.

Sex-related differences in bronchial parameters and pulmonary function test results in patients with chronic obstructive pulmonary disease based on three-dimensional quantitative computed tomography

Objective

This study was performed to evaluate the effect of sex on bronchial parameters and the predicted forced expiratory volume in 1 s expressed as a percentage of the forced vital capacity (FEV1% pred) on pulmonary function testing.

Methods

The data of 359 patients with chronic obstructive pulmonary disease (COPD) with available FEV1% pred and computed tomography (CT) images were retrospectively reviewed. FACT-Digital lung TM software (DeXin, Xi’an, China) was used to perform fully automated three-dimensional CT quantitative measurements of the bronchi. Generation 5 to 7 bronchi were measured, and the parameters analyzed were the lumen diameter (LD), wall thickness (WT), lumen area (LA), and WA% [WA / (WA + LA) × 100%].

Results

In the smoking, smoking cessation, and nonsmoking groups, women had a significantly larger WA% and smaller LD, WT, and LA than men. The FEV1% pred was significantly lower in women than men in the smoking and smoking cessation groups. The FEV1% pred was significantly higher in women than men in the nonsmoking group.

Conclusion

Sex-related differences may partially explain why smoking women experience more severe pulmonary function impairment than men among patients with COPD.

Airway Evaluation with Multidetector Computed Tomography Post-Processing Methods in Asthmatic Patients

Asthma is a chronic inflammatory obstructive airways disease. The disease occurs regardless of age and manifests with cough, attacks of breathlessness, and tightness in the chest. The pathophysiology of asthma is complex and still not fully understood. It is essential to find answers concerning the role of each part of the bronchial tree in asthma, especially the role of small bronchioles. With the development of newer generations of multidetector computed tomography (MDCT) and advanced post-processing methods it is possible to obtain more detailed images and gain insight into further aspects of asthma. MDCT post-processing methods can be divided into two-dimensional (2D) and three-dimensional (3D). In 2D projections, visualized hypodense regions correspond to the airway flow limitations. With the more advanced methods, such as multi planar reconstructions (MPR), images in different planes (axial, coronal, or sagittal) can be created. In the MPR technique only the voxels which are adjacent to each other in the predetermined plane can be extracted from the data set. Using the minimal/maximal intensity projections and shaded surface display, the volume of interest (VOI) can be extracted. High resolution CT scans can be used to create a more advanced imaging tool - the virtual bronchoscopy (VB). Using the VB makes it possible to visualize regions of obturation in the bronchi of up to the 5-8th generation. The MDCT with advanced post-processing methods is likely to assume an important role in the differential diagnosis of asthma, particularly when the diagnosis is dubious or hard to settle due to accompanying other lung diseases.

PET imaging approaches for inflammatory lung diseases: Current concepts and future directions

Inflammatory lung disease is one of the most common clinical scenarios, and yet, it is often poorly understood. Inflammatory lung disorders, such as chronic obstructive pulmonary diseases, which are causing significant mortality and morbidity, have limited therapeutic options. Recently, new treatments have become available for pulmonary fibrosis. This review article will describe the new insights that are starting to be gained from positron emission tomography (PET) methods, by targeting molecular processes using dedicated radiotracers. Ultimately, this should aid in deriving better pathophysiological classification of these disorders, which will ultimately result in better evaluation of novel therapies.

Optimal imaging protocol for measuring dynamic expiratory collapse of the central airways

AIM

To compare measurements of expiratory collapse obtained using multidetector computed tomography (MDCT) of the central airways on routine axial and multiplanar reformatted (MPR) images.

MATERIALS AND METHODS

Fifty volunteers with normal pulmonary function and no smoking history were imaged using a 64 MDCT system (40 mAs, 120 kVp, 0.625 mm collimation) with spirometric monitoring at end-inspiration and during forced expiration. Measurements of the trachea, right main (RMB) and left main bronchus (LMB) were obtained on axial and MPR images. Inspiratory and dynamic-expiratory cross-sectional area (CSA) measurements were used to calculate the mean percentage expiratory collapse (%Collapse). A paired t-test was used to assess within-subject differences and a Bland-Altman plot was used to assess agreement between the methods.

RESULTS

Among 24 men and 26 women (mean age±standard deviation 50±15 years), CSA values were significantly greater on axial than MPR images (all p<0.001); however, the mean difference in %Collapse values for axial versus MPR were small: trachea ≈1% (55 ±19 versus 56±18, p=0.338); LMB identical (60±20 versus 60±17 p=0.856); and, RMB 4% (62 ±19 versus 66±19 p<0.001). On average, creation of MPR required 12 minutes of additional time per case (range=10-15 min).

CONCLUSION

Differences in mean %Collapse for axial versus MPR images were small and unlikely to influence clinical management. This finding suggests that MPR may not be indicated for routine assessment of central airway collapse.

Multi-detector CT features of acute intestinal ischemia and their prognostic correlations

Acute intestinal ischemia is an abdominal emergency occurring in nearly 1% of patients presenting with acute abdomen. The causes can be occlusive or non occlusive. Early diagnosis is important to improve survival rates. In most cases of late or missed diagnosis, the mortality rate from intestinal infarction is very high, with a reported value ranging from 60% to 90%. Multi-detector computed tomography (MDCT) is a fundamental imaging technique that must be promptly performed in all patients with suspected bowel ischemia. Thanks to the new dedicated reconstruction program, its diagnostic potential is much improved compared to the past and currently it is superior to that of any other noninvasive technique. The increased spatial and temporal resolution, high-quality multi-planar reconstructions, maximum intensity projections, vessel probe, surface-shaded volume rending and tissue transition projections make MDCT the gold standard for the diagnosis of intestinal ischemia, with reported sensitivity, specificity, positive and negative predictive values of 64%-93%, 92%-100%, 90%-100% and 94%-98%, respectively. MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease. The purpose of this review is to examine the diagnostic and prognostic role of MDCT in bowel ischemia with special regard to the state of art new reconstruction software.

Right upper lobe tracheal bronchus: anesthetic challenge in one-lung ventilated patients -A report of three cases-

Tracheal bronchus (TB) is an aberrant, accessary or ectopic bronchus arising almost exclusively from the right side of the tracheal wall above the carina. In our center, 673 bronchoscopic examinations were performed from 2009 to 2011 in patients undergoing one lung ventilation (OLV) and 3 TB were found. The incidence of a TB at bronchoscopy was 0.45% in our research, which is consistent with the reported incidence range from 0.1-5%. The clinician should consider the possibility of anomalous right upper lobe bronchus and perform bronchoscopy prior to the right bronchial blocker insertion, when left-sided OLV using bronchial blocker is planned. Also, for the patient with TB, a double lumen tube insertion is recommended than a blocker insertion to achieve OLV completely.

Current oncologic concepts and emerging techniques for imaging of head and neck squamous cell cancer

The incidence of head and neck squamous cell carcinoma (HNSCC) is increasing and currently they account for 5% of all malignancies worldwide. Inspite of ongoing developments in diagnostic imaging and new therapeutic options, HNSCC still represents a multidisciplinary challenge.One of the most important prognostic factors in HNSCC is the presence of lymph node metastases. Patients with confirmed nodal involvement have a considerable reduction of their 5-year overall survival rate. In the era of individually optimised surgery, chemotherapy and intensity modulated radiotherapy, the main role of pre- and posttherapeutic imaging remains cancer detection at an early stage and accurate follow-up. The combined effort of early diagnosis and close patient monitoring after surgery and/or radio-chemotherapy influences disease progression and outcome predicition in patients with HNSCC.This review article focuses on currrent oncologic concepts and emerging tools in imaging of head and neck squamous cell cancer. Besides the diagnostic spectrum of the individual imaging modalities, their limitations are also discussed. One main part of this article is dedicated to PET-CT which combines functional and morphological imaging. Furthermore latest developments in MRI are presented with regard to lymph node staging and response prediction. Last but not least, a clinical contribution in this review explains, which information the head and neck surgeon requires from the multimodality imaging and its impact on operation planning.

Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

Background

Multidetector computed tomography (MDCT) provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment.

Methods

This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D) was determined from the average between D upper and D lower.

Results

Fifty-six patients, 14 (25%) women and 42 (75%) men, mean age 55.3 ± 13.2 years (range: 16-79 years), were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT.

Conclusions

MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

Multidetector computed tomography of pediatric large airway diseases: state-of-the-art

Advances in multidetector computed tomography (MDCT) technology have given rise to improvements in the noninvasive and comprehensive assessment of the large airways in pediatric patients. Superb two-dimensional and three-dimensional reconstruction MDCT images have revolutionized the display of large airways and enhanced the ability to diagnose large airway diseases in children. The 320-MDCT scanner, which provides combined detailed anatomic and dynamic functional information assessment of the large airways, is promising for the assessment of dynamic large airway disease such as tracheobronchomalacia. This article discusses imaging techniques and clinical applications of MDCT for assessing large airway diseases in pediatric patients.

Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature

A systematic review of the literature concerning upper airway imaging and analysis using cone-beam computed tomography (CBCT) was performed. A PubMed search (National Library of Medicine, NCBI; revised 9th January 2011) yielded 382 papers published between 1968 and 2010. The 382 full papers were screened in detail. 46 articles were considered clinically or technically relevant and were included in this systematic review. These were classified as articles on accuracy and reliability of CBCT imaging of the upper airway (n=4), accuracy and reliability of DICOM viewers (n=2), synopsis (n=10), technical (n=7) and clinical applications (n=27). When one paper was considered related to two or more categories, it was assigned to each relevant group. Results indicate that three-dimensional (3D) analysis of the upper airway using CBCT can be achieved in an accurate and reliable manner. Important obstacles still need to be addressed, including the impact of respiration phase, influence of tongue position and mandible morphology, longitudinal and cross-sectional 3D CBCT upper airway evaluation, and 3D CBCT definition of the anatomical boundaries of the upper airway.

The diagnostic contribution of CT volumetric rendering techniques in routine practice

Computed tomography (CT) volumetric rendering techniques such as maximum intensity projection (MIP), minimum intensity projection (MinIP), shaded surface display (SSD), volume rendering (VR), and virtual endoscopy (VE) provide added diagnostic capabilities. The diagnostic value of such reconstruction techniques is well documented in literature. These techniques permit the exploration of fine anatomical detail that would be difficult to evaluate using axial reconstructions alone. Although these techniques are now widely available, many radiologists are either unfamiliar with them or do not fully utilize their potential in daily clinical practice. This paper is intended to provide an overview of the most common CT volumetric rendering techniques and their practical use in everyday diagnostics.

The developmental relation between adenoid tissue and paranasal sinus volumes in 3-dimensional computed tomography assessment

OBJECTIVE

The aim of this study was to evaluate the developmental relationship between the volumes of paranasal sinuses and adenoid tissue by using a 3-dimensional (3D) reconstruction technique.

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Multislice computed tomography (MSCT) images were obtained using 3D reconstructions and a volume-rendering technique (VRT) in 69 boys and 35 girls aged 3 to 16 years, and bilateral maxillary, frontal, and sphenoid sinus volumes, as well as adenoid tissue volume marked in axial-coronal-sagittal planes, were calculated. The patients were grouped in 3 categories according to adenoid tissue volumes, and comparisons were made.

RESULTS

There was no significant difference between the right maxillary volume and left maxillary volume (P = .93). No significant difference was noted between the groups in terms of age and gender. There was no significant correlation between frontal, sphenoid, right and left maxillary, or total maxillary sinus volumes in all 3 groups of patients.

CONCLUSION

When classified according to adenoid tissue size, it was observed that increasing adenoid tissue volumes did not significantly affect the development of paranasal sinuses. Developmentally, there are no statistically significant correlations between the volumes of paranasal sinuses and adenoid tissues.

Update on multidetector computed tomography imaging of the airways

Recent advances in multidetector computed tomography (MDCT) technology have transformed the imaging evaluation of the trachea and bronchi. Multiplanar 2-dimensional and 3-dimensional volume reconstruction techniques, including external rendering and virtual bronchoscopy, can be generated in mere minutes, thereby complementing conventional axial CT imaging in the depiction of various central airway disease processes including airway stenoses, central airway neoplasms, and congenital airway disorders. Paired inspiratory and dynamic expiratory MDCT imaging, along with newer cine CT imaging methods, have enhanced the assessment of tracheobronchomalacia in both adults and the pediatric population. In addition, MDCT imaging plays an essential complementary role to conventional bronchoscopy, facilitating planning and guidance of bronchoscopic interventions, and providing a noninvasive method for postprocedural surveillance.

Comparing three-dimensional volume-rendered CT images with fibreoptic tracheobronchoscopy in the evaluation of airway compression caused by tuberculous lymphadenopathy in children

BACKGROUND

Lymphobronchial tuberculosis (TB) causes airway compression in 38% of patients. The airway obstruction is conventionally assessed with fibreoptic tracheobronchoscopy (FTB). Multidetector-row spiral computed tomography (MDCT) with three-dimensional volume rendering (3-D VR) has significantly improved the imaging of the airways. No previous studies have assessed the accuracy of 3-D VR in determining the degree of airway compression in children due to TB lymphadenopathy.

OBJECTIVE

To compare 3-D VR CT to FTB for the assessment of airway compression due to TB lymphadenopathy in children.

MATERIALS AND METHODS

Included in the study were 26 children presenting with symptoms of airway compression caused by pulmonary TB. MDCT of the chest and FTB were performed in all patients. Retrospective 3-D VR reconstruction of the major airways was performed from the original CT raw data and used to evaluate the tracheobronchial tree for site and degree of airway compression and then compared to the FTB findings. FTB was used as the reference standard

RESULTS

By FTB 87 sites of airway compression were identified. Using the 3-D VR technique, 138 sites of airway compression were identified, of which 78 (90%) matched with the sites identified by FTB. The sensitivity and specificity of 3-D VR when compared with that of FTB was 92% and 85%, respectively. In four patients (15%), severe narrowing of the bronchus intermedius made FTB evaluation of the right middle and right lower lobe bronchi impossible. VR demonstrated significant distal obstruction in three of these four patients

CONCLUSION

3-D VR demonstrates a very good correlation with FTB in determining airway compression caused by TB lymphadenopathy in children. In combination with FTB, 3-D VR adds confidence to the bronchoscopy findings and complements FTB by adding additional information on the status of the airway distal to severe obstructions unreachable by FTB.

MDCT of the airways: technique and normal results

The new generation of multidetector CT (MDCT) has revolutionized noninvasive imaging of proximal and distal airways. Exquisite anatomic details of the airway lumen and airway wall on axial CT images benefit in routine practice from postprocessing tools in adequate orientation. This method ensures an excellent assessment of the morphology and location of any pathology. It may be combined with use of very low dose CT. Airway lumen and airway wall areas may be quantitatively assessed on MDCT images by using specific techniques that are reproducible and accurate.

Bronchial anatomy of left lung: a study of multi-detector row CT

Familiarity with prevailing pattern and variations in the bronchial tree is not only essential for the anatomist to explain bronchial variation in bronchial specimens, but also useful for guiding bronchoscopy and instructing pulmonary segmental resection. The purpose of this study was designed to demonstrate various branching patterns of left lung with 3D images, with special attention given to identify the major types at transverse thin-section CT. Two hundred and sixteen patients with routine thorax scans were enrolled. The images of bronchial tree, virtual bronchoscopy were reconstructed using post-processing technique of multi-detector row CT. We attempted to classify the segmental bronchi by interpreting the post-processing images, and identified them in transverse thin-section CT. Our results showed that the segmental bronchial ramifications of the left superior lobe were classified into three types mainly, i.e., common stem of apical and posterior segmental bronchi (64%, 138/216); trifurcation (23%, 50/216); common stem of apical and anterior segmental bronchi (10%, 22/216), and they could be identified at two typical sections of transverse thin-section CT. There were two major types in left basal segmental bronchi, i.e., bifurcation (75%, 163/216), trifurcation (18%, 39/216), and they could also be identified at two typical sections of transverse thin-section CT. In conclusion, our study have offered simplified branching patterns of bronchi and demonstrated various unusual bronchial branching patterns perfectly with 3D images, and have also revealed how to identify the main branching patterns in transverse thin-section CT.

Imaging of the airways with multidetector row computed tomography

The wide availability of multidetector row computed tomography (MDCT) continues to change the way we manage patients. Once the domain of the specialist paediatric centre, imaging of the paediatric thorax now routinely occurs in many general hospitals. The paediatric respiratory and radiology teams should therefore be familiar with this technique. This review examines the indications for MDCT, the different types of scan, the use of low-dose protocols for paediatric imaging and appropriate reconstruction techniques. Patient preparation, with particular respect to sedation and optimal contrast bolus delivery, is also addressed.

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.

Characterization of radiologists' search strategies for lung nodule detection: slice-based versus volumetric displays

The goal of this study was to assess whether radiologists' search paths for lung nodule detection in chest computed tomography (CT) between different rendering and display schemes have reliable properties that can be exploited as an indicator of ergonomic efficiency for the purpose of comparing different display paradigms. Eight radiologists retrospectively viewed 30 lung cancer screening CT exams, containing a total of 91 nodules, in each of three display modes [i.e., slice-by-slice, orthogonal maximum intensity projection (MIP) and stereoscopic] for the purpose of detecting and classifying lung nodules. Radiologists' search patterns in the axial direction were recorded and analyzed along with the location, size, and shape for each detected feature, and the likelihood that the feature is an actual nodule. Nodule detection performance was analyzed by employing free-response receiver operating characteristic methods. Search paths were clearly different between slice-by-slice displays and volumetric displays but, aside from training and novelty effects, not between MIP and stereographic displays. Novelty and training effects were associated with the stereographic display mode, as evidenced by differences between the beginning and end of the study. The stereo display provided higher detection and classification performance with less interpretation time compared to other display modes tested in the study; however, the differences were not statistically significant. Our preliminary results indicate a potential role for the use of radiologists' search paths in evaluating the relative ergonomic efficiencies of different display paradigms, but systematic training and practice is necessary to eliminate training curve and novelty effects before search strategies can be meaningfully compared.

Multidetector row CT for imaging the paediatric tracheobronchial tree

The introduction of multidetector row computed tomography (MDCT) scanners has altered the approach to imaging the paediatric thorax. In an environment where the rapid acquisition of CT data allows general hospitals to image children instead of referring them to specialist paediatric centres, it is vital that general radiologists have access to protocols appropriate for paediatric applications. Thus a dramatic reduction in the delivered radiation dose is ensured with optimal contrast bolus delivery and timing, and inappropriate repetition of the scans is avoided. This article focuses on the main principles of volumetric CT imaging that apply generically to all MDCT scanners. We describe the reconstruction techniques for imaging the paediatric thorax and the low-dose protocols used in our institution on a 16-slice detector CT scanner. Examples of the commonest clinical applications are also given.

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.

Tracheal resection for critical tracheal occlusion due to intraluminal tumour

Anaesthesia for tracheal resection requires careful planning by an experienced team. We report a case of urgent tracheal resection for a vascular tumor in a 41-year-old man who was a heavy smoker The tumour occupied most of his trachea. A CT reconstruction of the tumor assisted in planning. Perioperative tracheal laser therapy and cardiopulmonary bypass were not used due to concerns about excessive bleeding. Intraoperative airway management involved an upper endotracheal tube placed by the anaesthetist and a second, lower, endotracheal tube placed by the surgeon. The existing evidence for anaesthesia management of tracheal resection is currently limited to case reports. This case illustrates how preoperative imaging and careful planning can lead to a successful outcome, despite the potentially life-threatening nature of the pathology and the surgery.

Pearls and pitfalls in HRCT in children

The aim of this talk is to discuss the role of thin slice high resolution CT in paediatric practice and to describe the various means by which these images can be acquired to a satisfactory [diagnostic] level in routine paediatric practice. It is also to highlight the utility of HRCT in paediatric practice to enable the various patterns of disease processes to be understood. The main role for HRCT is in the diagnosis and follow up of diffuse airways and interstitial lung diseases in children. We will focus on the utility of HRCT in diagnosis of paediatric diffuse interstitial lung disease [DILD] and the inherent strengths and weakness within the ultimate choices made to acquire images. We will emphasise and illustrate the specific conditions for which HRCT provides a powerful diagnostic tool.

Virtual Bronchoscopy for Diagnosis of Recurrent Respiratory Papillomatosis

Virtual bronchoscopy is a new method for viewing helical/spiral computed tomography (CT) images of the tracheobronchial trees. Using commercially available software to process the CT data, the tracheobronchial trees can be inspected through a series of three-dimensional images. Recently, this technique has been increasingly used to detect benign and malignant airway stenosis. We report the findings of virtual bronchoscopy in a 41-year-old man with recurrent respiratory papillomatosis (RRP). Several tiny nodules were evident in the lower trachea. Fiberoptic bronchoscopy was performed 1 month later during a planned surgery for laryngeal papillomas, and the findings were in agreement with virtual bronchoscopy. Detection of intrabronchial spreading in RRP is important since peripheral seeding of RRP can cause complications, including recurrent pneumonia, obstructive atelectasis, hemoptysis, and, rarely, may degenerate to squamous cell carcinoma. Virtual bronchoscopy is an alternative method for inspecting the tracheobronchial trees in patients with RRP when laryngeal papillomas impede fiberoptic bronchoscopy.

Multidetector CT of the central airways

Multidetector CT (MDCT) has revolutionized non-invasive imaging of the central airways. Compared to single-detector helical CT scans, MDCT results in higher spatial resolution, faster speed, greater anatomic coverage, and higher quality multiplanar reformation and 3-D reconstruction images. This article reviews recent advances in central airway imaging with MDCT. A special emphasis is placed upon the role of advanced reconstruction methods and functional imaging.

3D CT protocol in the assessment of the esophageal neoplastic lesions: can it improve TNM staging?

The purpose of this prospective observational study was the evaluation of the usefulness of MPR reconstructions and virtual endoscopy in the study of the esophageal carcinoma. Thirty-nine patients with esophageal cancer proved by means of endoscopy, underwent preoperative TNM staging with dynamic CT of the chest and abdomen with the aid of 3D rendering. Twenty-six patients underwent surgery, and the CT results were compared with histopathologic findings. In staging the T parameter, the CT with 3D reconstructions and virtual endoscopy, showed a sensitivity of 92% and an accuracy of 88%. In staging lymph nodes, the sensitivity in our study was 85%, the specificity 58%, and the accuracy 69%. Our protocol of the study of the esophageal cancer with 3D CT and virtual endoscopy, demonstrated a high concordance with the surgical and pathologic findings. The 3D reconstructed images were very helpful to the surgeons regarding preoperative planning. We performed an observational enquiry, and although this was a small study, it has, however, confirmed that the 3D imaging of the esophagus represents a valuable advantage to conventional imaging. Further studies with a larger number of patients are needed to prove its superiority to traditional CT imaging of the esophagus.

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.