Detection of bronchial abnormalities: comparison of CT and bronchoscopy

Evidence based imaging strategies for solitary pulmonary nodule

Solitary pulmonary nodule (SPN) is defined as a rounded opacity ≤3 cm in diameter surrounded by lung parenchyma. The majority of smokers who undergo thin-section CT have SPNs, most of which are smaller than 7 mm. In the past, multiple follow-up examinations over a two-year period, including CT follow-up at 3, 6, 12, 18, and 24 months, were recommended when such nodules are detected incidentally. This policy increases radiation burden for the affected population. Nodule features such as shape, edge characteristics, cavitation, and location have not yet been found to be accurate for distinguishing benign from malignant nodules. When SPN is considered to be indeterminate in the initial exam, the risk factor of the patients should be evaluated, which includes patients' age and smoking history. The 2005 Fleischner Society guideline stated that at least 99% of all nodules 4 mm or smaller are benign; when nodule is 5-9 mm in diameter, the best strategy is surveillance. The timing of these control examinations varies according to the nodule size (4-6, or 6-8 mm) and the type of patients, specifically at low or high risk of malignancy concerned. Noncalcified nodules larger than 8 mm diameter bear a substantial risk of malignancy, additional options such as contrast material-enhanced CT, positron emission tomography (PET), percutaneous needle biopsy, and thoracoscopic resection or videoassisted thoracoscopic resection should be considered.

Pulmonary nodule: a comprehensive review and update

The incidental detection of solitary pulmonary nodules and ground-glass nodules has increased substantially with the use of computed tomography as a diagnostic modality and is expected to rise exponentially as lung cancer screening guidelines are more widely implemented by primary care physicians. The lesions should then be classified as low, indeterminate, or high risk for malignancy, depending on the clinical and radiological characteristics. Once classified, these lesions should be evaluated and managed as per expert consensus-based recommendations for performing follow-up computed tomography scans and tissue sampling depending on the pretest probability. When weighing the risks and benefits of further investigations, patient preference and suitability for surgery should be taken into consideration as well.

Lung cancer screening: making the transition from research to clinical practice

PURPOSE OF REVIEW

The purpose of this review is to examine the literature on lung cancer screening with an emphasis on the prevalence of cancer in screen-detected nodules. On the basis of the evidence, we will then develop a practical approach to screen-detected lung nodules.

RECENT FINDINGS

The first large randomized controlled trial using low-dose computed tomography (LDCT) found that persons undergoing three annual screening examinations with LDCT had a 20% relative reduction in lung cancer mortality as compared with those screened with annual chest X-rays. The probability of cancer in screen-detected nodules depends on their size and whether the nodules are detected on prevalence or incidence screens. The probability of cancer in screen-detected nodules ranges from 2.4 to 5.2%. Management strategies for screen-detected nodules that have been used successfully include careful observation using serial CT imaging, CT-guided fine needle biopsy, and surgery in carefully selected cases. The most frequently used strategies involve serial CT imaging and CT-guided biopsy for larger nodules and those that demonstrate growth on follow-up.

SUMMARY

There is now evidence that LDCT in carefully selected high-risk populations can lead to better outcomes but the cost effectiveness of mass screening with LDCT is still unknown. Only patients at high risk for cancer should be screened.

Decision making in patients with pulmonary nodules

Integrating current evidence with fundamental concepts from decision analysis suggests that management of patients with pulmonary nodules should begin with estimating the pretest probability of cancer from the patient's clinical risk factors and computed tomography characteristics. Then, the consequences of treatment should be considered, by comparing the benefits of surgery if the patient has lung cancer with the potential harm if the patient does not have cancer. This analysis determines the "treatment threshold," which is the point around which the decision centers. This varies widely among patients depending on their cardiopulmonary reserve, comorbidities, and individual preferences. For patients with a very low probability of cancer, careful observation with serial computed tomography is warranted. For those with a high probability of cancer, surgical diagnosis is warranted. For patients in the intermediate range of probabilities, either computed tomography-guided fine-needle aspiration biopsy or positron emission tomography, possibly followed by computed tomography-guided fine-needle aspiration biopsy, is best. Patient preferences should be considered because the absolute difference in outcome between strategies may be small. The optimal approach to the management of patients with pulmonary nodules is evolving as technologies develop. Areas of uncertainty include quantifying the hazard of delayed diagnosis; determining the optimal duration of follow-up for ground-glass and semisolid opacities; establishing the roles of volumetric imaging, advanced bronchoscopic technologies, and limited surgical resections; and calculating the cost-effectiveness of different strategies.

Usefulness of FDG PET/CT in determining benign from malignant endobronchial obstruction

OBJECTIVE

To evaluate the usefulness of FDG PET/CT to differentiate malignant endobronchial lesions with distal atelectasis from benign bronchial stenosis.

METHODS

This retrospective study reviewed 84 patients who underwent contrast-enhanced chest CT and then PET/CT and had histological (n = 81) or follow-up imaging (n = 3) confirmation. Two chest radiologists reviewed initial chest CT and determined endobronchial lesions to be malignant or benign. Two nuclear medicine physicians reviewed PET/CT for FDG uptake at the obstruction site and measured SUV. Malignancy was considered when increased FDG uptake was seen in the obstruction site, regardless of FDG within the atelectatic lung.

RESULTS

The sensitivity, specificity and accuracy of chest CT was 95%, 48% and 84%, compared with 95%, 91% and 94% for PET/CT. Benign obstructive lesions showed statistically lower FDG uptake than malignant obstructions (benign SUV 2.5 ± 0.84; malignant SUV 11.8 ± 5.95, p < 0.001). ROC analysis showed an SUV cut-off value of 3.4 with highest sensitivity of 94% and specificity of 91%.

CONCLUSION

Increased FDG PET/CT uptake at the obstruction site indicates a high probability of malignancy, while benign lesions show low FDG uptake. Careful evaluation of FDG uptake pattern at the obstruction site is helpful in the differentiation between benign and malignant endobronchial lesions.

Multimodal virtual bronchoscopy using PET/CT images

OBJECTIVE

To demonstrate the possibilities, advantages and limitations of virtual bronchoscopy using data sets from positron emission tomography (PET) and computed tomography (CT).

MATERIALS AND METHODS

Eight consecutive patients with non-small cell lung cancer (NSCLC) underwent PET/CT. PET was performed with a glucose analog, 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG), using a state-of-the-art full-ring Pico-3D PET scanner. CT was performed with a venous-dominant contrast-enhanced phase using a 16-slice CT scanner. The tracheobronchial system was segmented using the CT data set with an interactive threshold interval volume-growing segmentation algorithm. The primary tumors and lymph node metastases were segmented for virtual CT-bronchoscopy using the CT data set and for virtual hybrid bronchoscopy using the PET/CT data set. The structures of interest were visualized with a color-coded shaded-surface rendering method.

RESULTS

The use of CT and virtual CT-bronchoscopy primarily facilitates visualization of the anatomical details of the tracheobronchial system and detection of anatomical/morphologic structural changes caused by disease. PET/CT and virtual hybrid bronchoscopy, or virtual PET/CT-bronchoscopy, give superior results to virtual CT-bronchoscopy because the hybrid bronchoscopy uses both the CT information and the molecular/metabolic information about the disease obtained from PET.

CONCLUSIONS

PET/CT imaging has proven to be a highly valuable oncological diagnostic modality. Virtual hybrid bronchoscopy can be performed using a low-dose CT scan or diagnostic CT. However, it is expected to improve diagnostic accuracy in identification and characterization of malignancies, verification of infections, and differentiation of viable tumor tissue from atelectases and scar tissue, as well as assessment of tumor staging and therapeutic response, and detection of early stage recurrences that are not detectable or are liable to be misjudged using virtual CT-bronchoscopy. It could also be useful as a screening examination method for patients with suspected endobronchial malignancy. Virtual hybrid bronchoscopy with a transparent color-coded shaded-surface rendering model offers a useful alternative to fiberoptic bronchoscopy, and is particularly promising for patients for whom fiberoptic bronchoscopy is not feasible, contraindicated or refused.

Interbronchoscopist variability in endobronchial path selection: a simulation study

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Virtual endoscopy of the tracheo-bronchial system: sub-millimeter collimation with the 16-row multidetector scanner

The purpose of this study was to evaluate the scope of sub-millimeter collimation reconstruction parameters using 16-row computer tomography and ECG triggering on image quality in virtual bronchoscopy. Thirty-two patients (5 women, 27 men, mean age 66.6+/-1.4) who had been admitted for coronary artery bypass graft surgery underwent CT examination of the thorax (Sensation 16, Siemens, Inc., Forchheim, Germany). All patients were examined with 16x0.75-mm collimation. Image reconstruction was performed for two groups. In group A ( n=32), slice thickness of 1.5 mm and an overlap of 0.75 mm were used. In group B ( n=32), slice thickness of 0.75 mm and an overlap of 0.4 mm were applied. Retrospective ECG triggering was performed in all patients. The maximum order of recognizable bronchi was determined in each data set. In addition to assessing the maximum order of bronchial bifurcation, bronchial diameter was determined in truly perpendicular sections in each patient. For every segment proximal to a bifurcation, image quality was subjectively graded as poor (grade 1), moderate (grade 2) or good (grade 3). The observers were asked to identify the minimum cardiac movement ECG-triggered image sets assuming that they would be of better quality than the maximum cardiac movement ECG-triggered image sets. The Mann-Whitney U-test and the Fisher's Exact Test were used for statistical evaluation. In group A, a mean of 4.8+/-0.2 bifurcations was ascertained vs. 6.5+/-0.3 bifurcations in group B [ P<0.0003]. For bronchial diameters in group A, a mean of 7.5+/-0.4 mm was determined vs. 4.6+/-0.4 mm in group B [ P<0.0001]. In group B, two independent radiologists observed a significant shift to better image quality in all segments evaluated [ P<0.006 to P<0.000001]. Motion artifacts were judged as being significantly reduced by minimum cardiac movement ECG-triggering in group B [observer 1: P=0.0007 (20/32); observer 2: P=0.008 (18/32)], but not in group A [observer 1: P=0.286 (13/32); observer 2: P=0.123 (16/32)]. Sub-millimeter collimation and minimum cardiac movement ECG-triggered data acquisition allow deeper penetration into the tracheo-bronchial system allowing visualization of the bronchial surface down to diameters below 5 mm in certain cases up to the eighth bifurcation. Along with an enhanced visualization as such, better image quality is acquired in all segments evaluated. Trade off between better image quality, of doubtful diagnostic consequence, and much higher irradiation dose must be made.

Virtual bronchoscopy: comparison of different surface rendering models

The aim of this study was to compare different representation models of surface-rendered virtual bronchoscopy. 10 consecutive patients with inoperable primary lung tumors underwent thin-section spiral computed tomography. The structures of interest, the tracheobronchial system and anatomical and pathological thoracic structures were segmented using an interactive threshold interval volume-growing segmentation algorithm and visualized with the aid of a color-coded surface rendering method. For virtual bronchoscopy, the tracheobronchial system was visualized using a triangle-surface rendering model, a shaded-surface rendering model and a transparent shaded-surface rendering model. The triangle-surface rendering model allowed optimum detailed spatial representation of the dimensions of extraluminal anatomical and pathological mediastinal structures. As the lumen of the tracheobronchial system was less well defined, the rendering model was of limited use for depiction of the airway surface. The shaded-surface rendering model facilitated an optimum assessment of the airway surface, but the mediastinal structures could not be depicted. The transparent shaded-surface rendering model provides simultaneous adequate to optimum visualization and assessment of the intraluminal airway surface and the extraluminal mediastinal structures as well as a quantitative assessment of the spatial relationship between these structures. Fast data acquisition with a multi-slice detector spiral computed tomography scanner and the use of virtual bronchoscopy with the transparent shaded-surface rendering model obviate the need for time consuming detailed analysis and presentation of axial source images by providing improved the diagnostic imaging of endotracheal and endobronchial diseases and offering a useful alternative to fiberoptic bronchoscopy.

Bronchoscopy and surgical staging procedures and their correlation with imaging

Bronchoscopy, computed tomography (CT) and surgical staging procedures are complimentary methods of investigating patients with lung cancer. CT has been shown to be of value prior to bronchoscopy in the investigation of haemoptysis and malignancy, with excellent correlation between the detection of disease within the large airways on CT and direct visualisation at bronchoscopy. The utility of CT has been further increased by the development of multislice scanners with the generation of volumetric data enabling multiplanar image acquisition. Additionally the advent of CT co-registered with positron emission tomography will play an important role in guiding the choice of surgical staging procedures The increasing use of multidisciplinary medical care requires radiologists to have a greater understanding of the abilities and limitations of both bronchoscopy and surgical staging procedures in evaluating disease demonstrated on imaging.

Low-dose spiral CT: application to surface-rendered three-dimensional imaging of central airways

PURPOSE

The purpose of this work was to assess the utility of low-dose spiral CT for three-dimensional imaging of the central airways.

METHOD

Spiral CT was performed in 15 patients using two tube currents (50 and 240 mA), producing 30 CT data sets. Surface-rendered virtual bronchoscopy (VB) and shaded surface display (SSD) images were assessed by three radiologists for image quality. The radiologists were also asked to compare 15 matched pairs each of 50 and 240 mA VB and SSD images, blindly select the 240 mA image, and record differences in diagnostic quality between the matched images.

RESULTS

No significant difference in image quality was noted with 50 or 240 mA. Only 51.1% of 240 mA SSD and 51.1% of 240 mA VB images were correctly identified. Differences in diagnostic quality, noted in 84.4% of SSD and 33% of VB image pairs, were not ascribed to image noise.

CONCLUSION

Image quality of surface-rendered three-dimensional images of the central airways is preserved using a lower tube current.

Hybrid 3D visualization of the chest and virtual endoscopy of the tracheobronchial system: possibilities and limitations of clinical application

OBJECTIVE

A hybrid rendering method which combines a color-coded surface rendering method and a volume rendering method is described, which enables virtual endoscopic examinations using different representation models.

MATERIALS AND METHODS

14 patients with malignancies of the lung and mediastinum (n=11) and lung transplantation (n=3) underwent thin-section spiral computed tomography. The tracheobronchial system and anatomical and pathological features of the chest were segmented using an interactive threshold interval volume-growing segmentation algorithm and visualized with a color-coded surface rendering method. The structures of interest were then superimposed on a volume rendering of the other thoracic structures. For the virtual endoscopy of the tracheobronchial system, a shaded-surface model without color coding, a transparent color-coded shaded-surface model and a triangle-surface model were tested and compared.

RESULTS

The hybrid rendering technique exploit the advantages of both rendering methods, provides an excellent overview of the tracheobronchial system and allows a clear depiction of the complex spatial relationships of anatomical and pathological features. Virtual bronchoscopy with a transparent color-coded shaded-surface model allows both a simultaneous visualization of an airway, an airway lesion and mediastinal structures and a quantitative assessment of the spatial relationship between these structures, thus improving confidence in the diagnosis of endotracheal and endobronchial diseases.

CONCLUSIONS

Hybrid rendering and virtual endoscopy obviate the need for time consuming detailed analysis and presentation of axial source images. Virtual bronchoscopy with a transparent color-coded shaded-surface model offers a practical alternative to fiberoptic bronchoscopy and is particularly promising for patients in whom fiberoptic bronchoscopy is not feasible, contraindicated or refused. Furthermore, it can be used as a complementary procedure to fiberoptic bronchoscopy in evaluating airway stenosis and guiding bronchoscopic biopsy, surgical intervention and palliative therapy and is likely to be increasingly accepted as a screening method for people with suspected endobronchial malignancy and as control examination in the aftercare of patients with malignant diseases.

Role of computed tomographic scanning of the thorax prior to bronchoscopy in the investigation of suspected lung cancer

BACKGROUND

Fibreoptic bronchoscopy (FOB) is the usual initial investigation of choice in patients with suspected endobronchial carcinoma, but it is often non-diagnostic. Once a positive diagnosis has been made, many patients undergo staging by computed tomographic (CT) scanning to assess the extent of the disease and its suitability for radical treatment. To determine whether initial CT scanning before FOB is a cost effective way of reducing subsequent unnecessary or unhelpful invasive diagnostic procedures, a study was undertaken in 171 patients with suspected endobronchial carcinoma.

METHODS

A randomised two group study was performed with all patients undergoing an initial CT staging scan. In group A the CT scans were reviewed before FOB, allowing cancellation or a change to an alternative invasive procedure if considered appropriate. In group B all patients proceeded to FOB with the bronchoscopist blinded to the result of the CT scan until after the procedure.

RESULTS

In group A six of 90 patients (7%) required no further investigations as the CT scan was either normal, consistent with benign disease, or consistent with widespread metastatic disease. Of the remainder, bronchoscopy was diagnostic in 50 of 68 (73%) in group A compared with 44 of 81 (54%) in group B (p = 0.015). Overall, a positive diagnosis was made after a single invasive investigation in 64 of 84 patients (76%) in group A compared with only 45 of 81 patients (55%) in group B (p = 0.005). Only seven of 90 patients (8%) in group A required more than one invasive investigation compared with 15 of 81 patients (18.5%) in group B. In patients with malignancy, bronchoscopy was more likely to be diagnostic in group A (50 of 56 patients (89%)) than in group B (44 of 62 (71%); p = 0. 012), and the diagnosis was more frequently made on the initial invasive investigation (group A, 63 of 70 (90%); group B, 44 of 62 (71%); p = 0.004). Because of the lower number of invasive procedures performed in group A than in group B, the cost of performing CT scans before FOB in all patients in group A would have equated to a projected cost of performing CT scans in 60% of patients after FOB in group B.

CONCLUSIONS

Performing initial CT thoracic scans before bronchoscopy in patients with suspected endobronchial malignancy is a cost effective way of improving diagnostic yield from invasive diagnostic procedures and occasionally may obviate the need for any further investigation.

Benign abnormalities and carcinoid tumors of the central airways: diagnostic impact of CT bronchography

OBJECTIVE

The purpose of this retrospective study was to determine the added diagnostic value, if any, of CT bronchography for the detection and characterization of benign abnormalities and typical carcinoid tumors of the central airways.

MATERIALS AND METHODS

We used bronchoscopy and helical CT to examine 238 bronchial sections in 28 patients with 32 bronchial abnormalities and in five patients with normal bronchoscopy results. Postprocessing consisted of CT bronchography based on surface rendering. Images were interpreted independently by two observers (a radiologist and a pneumonologist) who were not informed of the bronchoscopy results. After initial interpretation of axial CT scans, the observers analyzed the axial CT scans with CT bronchograms. Results were evaluated for gain in diagnostic accuracy and in confidence.

RESULTS

Mean sensitivity for detection of abnormal bronchial sections was 89% (range, 87-90%) for axial CT and 92% (range, 90-94%) for axial CT with CT bronchography (not significant). Mean specificity of both approaches exceeded 99%. A correct diagnosis of the nature of the bronchial abnormalities was proposed for 68% of the cases in which axial CT was used alone and in 76% in which both axial CT and CT bronchography were used (not significant). The addition of CT bronchography significantly increased the confidence of the pneumonologist in the diagnoses.

CONCLUSION

Axial CT remains the technique of choice to detect and characterize benign abnormalities of the airways. CT bronchography provides little diagnostic gain but increases the confidence of chest physicians in the interpretation of CT scans for the assessment of benign abnormalities and typical carcinoids of the central airways.

Blood clots mimicking peripheral intrabronchial tumors in patients with hemoptysis: CT and bronchoscopic findings

We report radiographic and clinical findings in two cigarette-smoking patients presenting with hemoptysis. On CT, both patients had peripheral intrabronchial masses together with parenchymal opacities. Bronchoscopy revealed the intrabronchial masses to be blood clots and the parenchymal opacities to correspond to areas of parenchymal hemorrhage. Our cases are novel in that both bronchial and parenchymal sequelae of hemorrhage were simultaneously visualized by CT. Also, our findings suggest that bronchial blood clots should be included in the differential diagnosis of peripheral intrabronchial lesions, notably in patients presenting with hemoptysis.

High-resolution CT in patients with intraluminal typical bronchial carcinoid tumors treated with bronchoscopic therapy

STUDY OBJECTIVE

To evaluate the extent to which high-resolution CT (HRCT) can predict the clinical outcome of bronchoscopic treatment with curative intent in patients with intraluminal typical bronchial carcinoid tumors.

DESIGN

An observational study.

SETTING

Bronchoscopy unit and radiology department of a university hospital.

PATIENTS AND INTERVENTIONS

Eighteen patients with intraluminal typical bronchial carcinoid tumors in the absence of nodal and distant disease were treated with bronchoscopic electrocautery or Nd-YAG laser as an alternative to surgical resection. Prior to treatment, HRCT was performed.

RESULTS

In 10 patients, HRCT showed no peribronchial tumor extension, and 9 of these patients were found to be tumor free after bronchoscopic treatment. So far during follow-up, none of these patients has had a recurrence of the tumor. The median duration of follow-up was 33 months (range, 13 to 68 months). In five patients, HRCT showed signs of peribronchial tumor extension. In three of these patients, specimens taken from biopsies performed after bronchoscopic treatment showed residual tumors, and salvage surgery was carried out. In three patients, HRCT was unable to assess peribronchial tumor extension: in two because of insufficient connective tissue contrast between the hilar structures and in one patient because of suboptimal scan technique.

CONCLUSION

HRCT findings were complementary but not conclusive in patients with intraluminal typical bronchial carcinoid tumors treated with bronchoscopic therapy. However, in a category of patients in whom HRCT showed strictly intraluminal tumors, bronchoscopic resection as an alternative for surgical resection seems justified.

Imaging the airways. Hemoptysis, bronchiectasis, and small airways disease

Advances in technology have increased the contribution of radiology in understanding and evaluating diseases of the airways. In patients with hemoptysis, CT is now established as a complementary technique to bronchoscopy, or as an alternative to bronchoscopy in selected cases. The introduction of high-resolution CT has improved the detection and assessment of bronchiectasis and small airways disease, allowed better correlation between pathologic changes and radiologic appearances, and provided new insights into possible links between small airways disease and bronchial disease.

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.

Can chest CT decrease the use of preoperative bronchoscopy in the evaluation of suspected bronchogenic carcinoma?

BACKGROUND

Fiberoptic bronchoscopy (FOB) is frequently used to diagnose and stage bronchogenic carcinoma (BC). However, the value of FOB in diagnosis/staging BC presenting as a pulmonary nodule or mass (PNM) is controversial. Since chest CT is usually obtained in these patients, it may be used in patient selection for preoperative FOB.

OBJECTIVE

Evaluation of the role of chest CT in determining the predictive value of FOB in diagnosing/staging a PNM, by comparing the results of CT and bronchoscopy.

DESIGN

Retrospective review of chest CTs and medical records.

PATIENTS

Consecutive patients with BC between 1992 and 1994 who had diagnostic FOB and CT in our institution, but without radiographic evidence of (1) pulmonary atelectasis, (2) endobronchial tumor or narrowing of the central airways, and (3) the PNM abutting the central airways.

RESULTS

Sixty-four patients met the selection criteria. The size of the PNM ranged from 1.5 to 10 cm; the size was < or = 4 cm in 62 patients. FOB provided a diagnosis in 22 patients. Bronchoscopy detected endobronchial lesions in 11 patients (17%); 3 had lesions in more than one lobe. In three patients, the PNM was <3 cm. The radiographically undetected endobronchial tumor increased the tumor stage in only two patients. The "CT bronchus" sign had a positive and negative predictive value of 75% and 68%, respectively.

CONCLUSIONS

(1) In this study, CT failed to detect endobronchial tumor in 11 of 64 patients (17%). Because of the implications of a new staging system, more studies are necessary before abandoning staging FOB. (2) The CT bronchus sign has a very high positive and negative predictive value in the use of diagnostic FOB and should be used to guide the method of biopsy of a PNM.

Detecting lung cancer as a cause of hemoptysis in patients with a normal chest radiograph: bronchoscopy vs CT

OBJECTIVE

To determine whether fiberoptic bronchoscopy (FOB) or CT results in the lowest number of tests needed to diagnose (NTND) lung cancers in patients presenting with hemoptysis and a normal chest radiograph (CXR).

DESIGN

Calculation of the NTND in a hypothetical cohort of patients presenting with hemoptysis and a normal CXR.

INTERVENTIONS

In the primary analysis, either FOB or CT is performed to detect lung cancers. FOB is used to diagnose endobronchial abnormalities, and transthoracic needle aspirate is relied on to diagnose parenchymal findings. Patients then undergo serial follow-up CXRs. In a secondary analysis, sputum cytologic tests are performed prior to FOB and CT. Abnormal cytologic results require FOB. Unremarkable cytologic results allow a choice between FOB or CT.

MEASUREMENTS

NTND and number of lung cancers detected during serial follow-up CXRs.

RESULTS

Performing FOB results in a much lower NTND than CT with a similar number of lung cancers detected during serial follow-up with each approach. Reducing the false-positive rate for lung cancers of airway evaluations by CT reduces the NTND for the CT strategy. Performing both FOB and CT results in a large NTND. Adding sputum cytology as a guide for performing FOB substantially reduces the NTND for the FOB approach.

CONCLUSION

A strategy relying on initial sputum cytologic testing as a screen for choosing either FOB as an immediate diagnostic step or serial follow-up CXR to detect lung cancer in patients presenting with hemoptysis and a normal CXR results in the lowest NTND with only a marginal reduction in the early detection of all cancers.

Virtual bronchoscopy. Relationships of virtual reality endobronchial simulations to actual bronchoscopic findings

Advances in computer technology have permitted development of virtual reality images of the tracheobronchial tree using data sets derived from helical CT of the chest. To determine the relevance of these images to actual bronchoscopic findings, we compared "virtual bronchoscopy" images with videotaped bronchoscopy results in 20 patients who had undergone both helical chest CT and fiberoptic bronchoscopy during clinical evaluation of their thoracic problems. Suboptimal endobronchial simulations in ten patients identified important, readily-addressed technical requirements for this imaging procedure. In the ten patients with technically suitable renderings of the airway, virtual bronchoscopy simulations accurately demonstrated endobronchial obstructions by tumor in five, airway distortion and/or ectasia in four, and accessory bronchi in another. These preliminary observations suggest that virtual bronchoscopy simulations accurately represent major endobronchial anatomic findings. This technique may have a role in prebronchoscopy planning, endoscopy training, and/or endobronchial therapy, and merits further study.

Transbronchial lung biopsy through the fibre optic bronchoscope. Results and complications in 452 examinations

During 1986-1989, diagnostic fibre optic bronchoscopy (FOB) was performed in local anaesthesia in 1144 consecutive patients. Of these, 405 (35%) patients, median age 59 years, had transbronchial lung biopsy (TBB) performed under fluoroscopic guidance; 47 patients had a rebronchoscopy, i.e. in total 452 FOB were evaluated. The indication for TBB was localized pulmonary lesions in 279 (69%) patients, and diffuse pulmonary lesions in 126 (31%) patients. Localized lesions: TBB yielded a clinically relevant diagnosis in 55.2% of the patients. Of the 110 patients with malignancy, the overall diagnostic strength was 45.5%. Of the 159 patients with non-malignant lesions, 65.4% were diagnosed by TBB. The diagnostic yield increased with the number of biopsy specimens (< or = 4 biopsies, 52%; > 4 biopsies, 70%. P < 0.05). In 155 patients with well defined, circumscribed lesions, the diagnostic yield of TBB increased with the size of the lesion (< 31 mm, 47%; 31-60 mm, 54%; > 60 mm, 60%, P = 0.09), and decreased with the distance of the lesion from the main carina < 61 mm, 70%; 61-100 mm, 52%; > 100 mm, 40% P < 0.02). Diffuse lesions: TBB yielded a clinically relevant diagnosis in 66.7% of the patients. Of the 15 patients with malignancy, 73.3% were diagnosed by TBB. Of the 93 patients with non-malignant lesions, 78.5% were diagnosed by TBB. The diagnostic yield showed a trend to increase with the number of biopsy specimens (< or = 4 biopsies, 65%; > 4 biopsies, 71%, P = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemoptysis: prospective high-resolution CT/bronchoscopic correlation

The precise roles of fiberoptic bronchoscopy (FOB) and computed tomography (CT) of the chest in the evaluation of patients presenting with hemoptysis have not been clearly defined. On the assumption that both procedures would likely provide unique and complementary information, a prospective study with blinded interpreters using a modified high-resolution CT technique (HRCT) and FOB was designed to evaluate 57 consecutive patients admitted to Bellevue Hospital with hemoptysis. Etiologies included bronchiectasis (25 percent), tuberculosis (16 percent), lung cancer (12 percent), aspergilloma (12 percent), and bronchitis (5 percent): in an additional 5 percent of cases, hemoptysis proved to be due miscellaneous causes, while in 19 percent hemoptysis proved to be cryptogenic. Patients with lung cancer all were at least 50 years old, smoked an average of 78 pack-years, and had less severe hemoptysis but of longer duration. All had conditions diagnosed both by HRCT and FOB. High-resolution CT proved of particular value in diagnosing bronchiectasis and aspergillomas, while FOB was diagnostic of bronchitis and mucosal lesions such as Kaposi's sarcoma. Fiberoptic bronchoscopy localized bleeding in only 51 percent of cases. The high sensitivity of CT in identifying both the intraluminal and extraluminal extent of central lung cancers in conjunction with its value in diagnosing bronchiectasis suggest that CT should be obtained prior to bronchoscopy in all patients presenting with hemoptysis.

Radiographic screening for cancer. Proposed paradigm for requisite research

Computed tomography (CT) imaging as an excellent approach to the detection and characterization of small solitary pulmonary nodules (SSPN) raises three questions: (1) How often does CT imaging lead to detection of SSPN? (2) How often is such an SSPN malignant? (3) If malignant, how curable is it? The first question pertains to decisions about screening use of CT (clinical or mass screening), the second to decisions about screening for SSPN and diagnosis of malignancy given SSPN, and the third--in the context of known curability at ordinary clinical diagnosis--to decisions about screening for SSPN, diagnosis given SSPN and intervention given malignant SSPN. We present a three component study design that addresses these questions. The first is directed primarily to the first question. Some 1000 persons at high risk for lung cancer will be screened for SSPN using screening-type CT. The primary aim is to determine the prevalence of CT-detectable SSPN as a joint function of risk-relevant aspects of the person. The second component addresses the prevalence of malignancy among the detected cases of SSPN. To develop the prevalence function, a larger series of CT-detected SSPN will be obtained by developing a multi-center SSPN "registry." A subsequent, third component will focus on the registered cases of malignant SSPN screening incidentally detected and address their curability on the basis of long-term follow-up. This design, in lieu of a randomized trial, may represent a new paradigm for applied research on radiologic technologies in cancer screening, given its advantages in terms of research efficiency and implications to decisions about diagnostic workup and therapeutic intervention.

The positive bronchus sign in patients with known lung cancer

The positive bronchus sign is the CT finding of a bronchus leading to or contained within the primary mass. A prospective study was performed for the purpose of establishing the correlation between the above sign on CT and the visual and pathological findings on bronchoscopy. The predictive value for the positive bronchus sign was found to be 94% and that of the negative bronchus sign 62%. CT is useful in predicting the likelihood of subsequent bronchoscopy providing positive results.