64-slice computed tomography assessment of coronary artery stents: a phantom study

Purpose: To compare the use of a new 64-slice computed tomography (CT) scanner with 16-slice CT in the visualization of coronary artery stent lumen.

Material and Methods: Eight different coronary artery stents, each with a diameter of 3 mm, were placed in a static chest phantom. The phantom was positioned in the CT gantry at an angle of 0° and 45° towards the z-axis and examined with both a 64-slice and a 16-slice CT scanner. Effective slice thickness was 0.6 mm with 64-slice CT and 1 mm with 16-slice CT. A reconstruction increment of 0.3 mm was applied in both scanners. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using paired Wilcoxon tests.

Results: Artificial lumen reduction was significantly less with 64-slice than with 16-slice CT. Average visible stent lumen was 53.4% using 64-slice CT and 47.5% with 16-slice MSCT. Most severe artifacts were seen in stents with radiopaque markers. Using 64-slice CT, image noise increased by approximately 30% due to thinner slice thickness.

Conclusion: Improved spatial resolution of 64-slice CT resulted in superior assessment of coronary artery stent lumen compared to 16-slice CT. However, a relevant part of the stent lumen is still not assessable with multi-slice CT.     

A new computed tomography-based radiographic method to detect early loosening of total wrist implants

Background: Diagnosis of loosening of total wrist implants is usually late using routine radiographs. Switching modality to computed tomography (CT) should aid in early diagnosis.

Purpose: To propose and evaluate the accuracy of a new CT method for assessing loosening of the carpal component in total wrist arthroplasty.

Material and Methods: A protocol encompassing volume registration of paired CT scans of patients with unexplained pain in a prosthetically replaced wrist (used in clinical routine) is presented. Scans are acquired as a dynamic examination under torsional load. Using volume registration, the carpal component of the prosthesis is brought into spatial alignment. After registration, prosthetic loosening is diagnosed by a shift in position of the bones relative to the prosthesis. This study is a preclinical validation of this method using a human cadaverous arm with a cemented total wrist implant and tantalum markers. Seven CT scans of the arm were acquired. The scans were combined into 21 pairs of CT volumes. The carpal component was registered in each scan pair, and the residual mismatch of the surrounding tantalum markers and bone was analyzed both visually and numerically.

Results: The detection limit for prosthetic movement was less than 1 mm.

Conclusion: The results of this study demonstrate that CT volume registration holds promise to improve detection of movement of the carpal component at an earlier stage than is obtainable with plain radiography.     

Ultrasound guidance for puncture and injection in the radiocarpal joint

Background: The use of intra-articular contrast agent has been shown to increase the diagnostic accuracy of wrist magnetic resonance (MR) in patients with suspected trauma of the wrist ligaments. Traditionally, the contrast agent has been applied under fluoroscopic guidance.

Purpose: To present a method based on ultrasound guidance for the injection of intra-articular contrast agent in wrist MR.

Material and Methods: One hundred eight patients (56 female and 52 male, mean age 36 years) referred for wrist MR arthrograms due to suspected ligament rupture were included in this retrospective study. The preferred injection point is about 1 cm distal to Lister's tubercle in the distal radius. A correct positioning of the injection needle can be ensured using ultrasound guidance.

Results: Using this technique, the injection was intra-articular in 93.5% of the 108 injections over a 2-year learning period.

Conclusion: Ultrasound guidance of the contrast injection in radiocarpal MR arthrograms is a cost-effective and safe alternative to fluoroscopically guided procedures. Furthermore, the use of ultrasound guidance provides clues about possible fluid collections within the joint.     

Reduction in dose from CT examinations of liver lesions with a new postprocessing filter: a ROC phantom study

Background: It is desirable to lower the dose from computed tomography (CT) examinations as much as possible without reducing diagnostic performance. Mathematical postprocessing filters are one tool to achieve dose reduction.

Purpose: To evaluate the possibilities of reducing CT doses from liver examinations using a new postprocessing filter.

Material and Methods: An anthropomorphic upper-abdomen phantom was used in receiver operating characteristic (ROC) studies of the detectability of liver lesions. A standard abdominal CT protocol was used. Only mA settings were changed; all other scan parameters were constant. The postprocessing filter used was SharpView CT, which provides context-controlled restoration of digital images using adaptive filters. Six readers were given a set of 10 images obtained at five different dose levels, each image with 32 predefined areas to be evaluated on a five-point scale. In total, 1920 areas were evaluated. At each dose level, the readers evaluated five images without enhancement and five images based on postprocessing filters. All images were randomized with respect to dose level.

Results: The postprocessing filter improved the diagnostic performance significantly compared to the unenhanced images at all dose levels. Radiation dose for abdominal CT examinations of liver lesions in the range 2-7 mm was reduced by 30% using postprocessing filters, while diagnostic performance of the examination was maintained or even improved.

Conclusion: This study indicates great potential for lowering doses for CT examinations of liver lesions using the new postprocessing filter. The software must be fully tested clinically to reliably assess the benefits of this filtration.     

Preoperative computed tomography-guided percutaneous hookwire localization of metallic marker clips in the breast with a radial approach: initial experience

Background: Hookwire localization is the current standard technique for radiological marking of nonpalpable breast lesions. Stereotactic directional vacuum-assisted breast biopsy (SVAB) is of sufficient sensitivity and specificity to replace surgical biopsy. Wire localization for metallic marker clips placed after SVAB is needed.

Purpose: To describe a method for performing computed tomography (CT)-guided hookwire localization using a radial approach for metallic marker clips placed percutaneously after SVAB.

Material and Methods: Nineteen women scheduled for SVAB with marker-clip placement, CT-guided wire localization of marker clips, and, eventually, surgical excision were prospectively entered into the study. CT-guided wire localization was performed with a radial approach, followed by placement of a localizing marker-clip surgical excision. Feasibility and reliability of the procedure and the incidence of complications were examined.

Results: CT-guided wire localization surgical excision was successfully performed in all 19 women without any complications. The mean total procedure time was 15 min. The median distance on CT image from marker clip to hookwire was 2 mm (range 0-3 mm).

Conclusion: CT-guided preoperative hookwire localization with a radial approach for marker clips after SVAB is technically feasible.     

Pediatric multidetector computed tomography using tube current modulation and a patient image gallery

Background: Dose reduction is crucial in pediatric multidetector computed tomography (MDCT).

Purpose: To perform pediatric 16-slice MDCT using tube current modulations and to adjust prospectively the tube current using a patient image gallery (IG) providing simulated dose-reduced protocols; and to evaluate and compare the image quality of the IG and the clinical MDCT.

Material and Methods: 30 examinations (thorax, n=15; abdomen, n=8; pelvis, n=7) in 20 patients (nine male, age 8.05±7.33 years, weight 29.8±24.02 kg) were performed according to an IG on a 16-slice MDCT with additional use of online tube current modulation (CARE Dose). Three radiologists visually assessed image quality from the IG and actual 16-slice MDCT scans. For objective analysis, image noise was determined.

Results: Statistical analysis showed moderate concordance in objective (K =0.68-0.78) and subjective (K =0.33-0.64) image assessment between the IG and clinical 16-slice MDCT scans. Depending on the weight group and clinical question, no or only minor dose reductions in the chest, but moderate to considerable reductions in the abdominal/pelvic 16-slice MDCT scans compared to previously used pediatric protocols were achieved. Extra dose reduction was achieved due to additional use of CARE Dose depending on age group and scan region (mean 8.6-23.9%).

Conclusion: The IG enabled us to prospectively reduce the tube current and adapt the required image quality to the clinical question. Additional dose reduction was achieved with application of CARE Dose; nevertheless, the images are comparable to the simulated images of the IG.     

Limited cone-beam computed tomography imaging of the middle ear: a comparison with multislice helical computed tomography

Purpose: To determine the applicability of cone-beam computed tomography (CBCT) in otological imaging, and to compare its accuracy with the routinely used multislice helical CT (MSCT) for imaging of the middle- and inner-ear areas.

Material and Methods: Thirteen unoperated human cadaver temporal bones were imaged with CBCT and MSCT. Sixteen landmarks of the middle and adjacent inner ear were evaluated and compared for their conspicuity according to a modified Likert scale. Total scores and scores for subgroups including landmarks of specific clinical interest were also compared.

Results: No significant differences were found between the imaging techniques or subgroups when scores of individual structures were compared. While the middle ear itself was visible in all cases with CBCT, parts of the inner ear were “cut off” in four cases due to the limited field of view. For the same reason, the evaluation of the whole mastoid was not possible with CBCT. The cochlear and vestibular aqueducts were not visualized in either CT techniques. The contrast-to-noise ratio was more than 50% lower in CBCT than in MSCT, but still adequate for diagnostic task.

Conclusion: CBCT proved to be at least as accurate as routinely used MSCT in revealing the clinically and surgically important middle-ear structures. The results show that high-quality imaging of the middle ear is possible with the current CBCT device.     

Evaluation of coronary bypass graft occlusion and stenosis with 64-detector-row computed tomography angiography

Background: A noninvasive imaging modality is desirable for the evaluation of coronary bypass graft stenosis and occlusion.

Purpose: To prospectively evaluate the effectiveness of 64-detector-row computed tomography (DCT) for the assessment of coronary bypass grafts.

Material and Methods: Forty-two patients (35 male, seven female, mean age 66.3 years) with 103 bypass grafts (32 arterial, 71 venous) were examined with 64-DCT. The evaluations were done by two radiologists blinded to the results of quantitative coronary angiography (QCA), used as the reference standard.

Results: All of the 26 occluded grafts, nine of the 10 stenosed grafts, and 66 of the 67 patent grafts were correctly diagnosed with 64-DCT angiography. The sensitivity, specificity, and positive and negative predictive values for 64-DCT in detecting graft stenosis were 90%, 99%, 90%, and 99%, respectively. For graft occlusion, all were 100%. No statistically significant difference was found between 64-DCT and QCA for the evaluation of bypass grafts. Intermodality and interobserver agreement were excellent.

Conclusion: 64-DCT angiography is a reliable, noninvasive diagnostic method for the assessment of coronary bypass grafts. It can be considered as a useful tool for follow-up purposes and may function as a gatekeeper before invasive procedures.     

Inadvertent intra-arterial drug injections: the role of angiographic and clinical findings

Purpose: To evaluate the angiographic findings of patients who have inadvertently injected oral formulations of drugs into an upper extremity artery.

Material and Methods: The radiology files for the previous 4 years were analyzed retrospectively. Seven patients were referred from the Emergency Department for angiography and possible thrombolysis during that time period.

Results: The worst clinical results were found among the patients whose angiographic examinations showed absent flow. Two patients who were treated with local thrombolysis had no better results compared to the other five patients.

Conclusion: Findings of delayed flow and absent flow in angiography should lead to intensified conservative treatment, especially among patients who have clinical findings of delayed capillary refilling or/and impaired muscular strength.     

Screening for carotid injury in trauma patients: image quality of 16-detector-row computed tomography angiography

Background: The introduction of multidetector-row computed tomography (MDCT) has revolutionized the initial management of multiply injured patients. This technology has the potential to improve the imaging of traumatic vascular injuries.

Purpose: To evaluate the quality of multidetector-row computed tomography angiography (MDCTA) of the carotid arteries in the setting of a routine whole-body trauma scan.

Material and Methods: 87 trauma patients underwent a routine whole-body CT scan in a 16-detector-row scanner including an MDCTA with a reconstructed axial slice thickness of 3 mm. Images were reviewed by three experienced radiologists with emphasis on image quality. Contrast density, severity, and origin of artifacts and the occurrence of vessel lesions were assessed for different vessel segments.

Results: 3642 separate vessel segments were evaluated. Contrast density was rated good or sufficient for diagnosis in 99.8%. A total of 67.3% of vessel segments were free of artifacts, while 27.9% of vessel segments showed minor artifacts not impairing diagnostic evaluation. Clinically relevant artifacts obscuring a vessel segment occurred in 4.7% and were mostly caused by dental hardware. Four dissections of the internal carotid artery were diagnosed by all three radiologists.

Conclusion: As a rapid screening test for blunt carotid artery injury, integration of MDCTA in the routine imaging workup of trauma patients utilizing a whole-body CT trauma scan is possible and practicable. Image quality is mostly sufficient for diagnosis, but impaired in a few cases by artifacts deriving primarily from dental hardware.     

Magnetic resonance imaging in Linburg-Comstock anomaly

Purpose: To determine the usefulness of magnetic resonance imaging (MRI) in detecting the tendinous connection in Linburg-Comstock anomaly.

Material and Methods: The study comprised 52 patients attending the orthopedic clinic for different hand problems. They were also examined for the presence of Linburg-Comstock anomaly, which was present in nine, and these patients were examined by MRI.

Results: The tendinous connection between flexor pollicis longus and flexor digitorum longus in all patients was shown by MRI. The connections were in the wrist, just proximal to the radiocarpal joint or distal forearm.

Conclusion: MRI can show localization of the connection in this anomaly and helps the surgeon perform the operation with a limited incision. The operation time is therefore shorter and wound scarring less prominent.     

Coraco- or costoclavicular paraosteoarthropathies in patients with severe central neurological disorders

Background: Paraosteoarthropathy (POA) is a frequent disabling orthopedic complication after severe central neurological impairment. The hip is the most frequently affected joint (32.1%) followed by the elbow and the shoulder (25%).

Purpose: To evaluate coraco- and costoclavicular paraosteoarthropathy in patients with severe central neurological disorders.

Material and Methods: We report a series of five consecutive patients with severe central neurological disorders who developed a POA of the clavicular region (coracoclavicular or costoclavicular POA). Every patient underwent a clinical, radiological, and computed tomographic (CT) examination of the shoulder region.

Results: Four patients had a history of traumatic brain injury (TBI), and one an acute disseminated encephalomyelitis (ADEM). They developed POA of the clavicular region, although not around the glenohumeral joint. The patients complained of shoulder pain and of moderate limitation of movements. Radiological and CT examinations showed the presence of a bony formation in the coracoclavicular space in four cases and extending from the clavicle to the first rib around the costoclavicular joint in one case.

Conclusion: In patients with severe brain lesions suffering from shoulder pain and moderate limitation of joint movements, POAs of the clavicular region are rare but should be considered.     

What are radiologists doing to prevent contrast-induced nephropathy (CIN) compared with measures supported by current evidence? A survey of European radiologists on CIN associated with computed tomography

Background: Contrast-induced nephropathy (CIN) is a serious complication of the use of iodinated contrast media (CM), and is associated with increased morbidity and mortality.

Purpose: To investigate whether radiologists take sufficient measures to prevent CIN in computed tomography (CT).

Material and Methods: 2005 survey of 509 European radiologists who had ≥3 years' experience and performed ≥50 CT scans/week.

Results: The most common methods used to identify patients at risk of CIN were renal function measurements (64%), clinical judgment (55%), and patient questionnaires (31%); 9% made no routine attempt to identify at-risk patients. The most common preventive protocols used in at-risk patients included: intravenous (i.v.) saline volume repletion (59%) or oral hydration (52%) before/after CT; use of low-osmolar CM (LOCM; 40%) or isosmolar CM (IOCM; 36%); and N-acetylcysteine (20%); 8% used no hydration regimen. While 78% of respondents used ≤100 ml of CM in high-risk patients, 14% used ≤150 ml, and 9% set no volume limit. For 57% of respondents, osmolality was the most important attribute in choosing an iodinated CM in at-risk patients; 41% agreed that CIN risk is lower with IOCM versus LOCM (31% disagreed).

Conclusion: A European radiologist survey identified a need for increased implementation of evidence-based protocols to improve CIN prevention: routine identification of at-risk patients; withdrawal of nephrotoxic drugs; use of volume repletion regimens; lowest possible volume of CM; and appropriate CM.     

Radiological evaluation of covered self-expandable metallic stents used for palliation in patients with malignant esophageal strictures

Purpose: To study the role of self-expandable metallic stents in malignant esophageal strictures in terms of patency, improved dysphagia score, and possible associated complications.

Material and Methods: Twenty-two patients with inoperable carcinoma of the esophagus underwent stent placement. Four different varieties of covered stents were used. Stenting was performed under fluoroscopic guidance and local pharyngeal anesthesia. During follow-up, patients were examined clinically and radiologically to assess the effectiveness of stents in relieving dysphagia, to check the stent position, patency, and possible complications.

Results: Fluoroscopic placement of the stent was successful and well tolerated in all patients without any serious complications. Accurate stent placement was possible in 95% of cases. The mean dysphagia score prior to stenting was 3.5 and poststent 1.2, with an improvement of 2.3 degrees. In two patients with associated fistulas, complete closure was seen after stent insertion. There was poor stent expansion in three patients. Significant tumor overgrowth occurred in two patients, and a second overlapping stent was deployed in one case. Three patients developed food impaction, which needed endoscopic removal of impacted food in two cases.

Conclusion: Fluoroscopic placement of self-expandable metallic stents is a safe and effective method of palliating severe dysphagia and fistulas in patients with inoperable esophageal carcinoma. However, complications such as tumor overgrowth and food impaction may require reintervention after stent placement.     

Bronchial stump fistula: treatment with covered, retrievable, expandable, hinged stents--preliminary clinical experience

Purpose: To evaluate the preliminary clinical efficacy and retrievability of a covered, retrievable, metallic hinged stent in the treatment of bronchial stump fistula (BPF).

Material and Methods: Between April 2003 and March 2005, eight patients with bronchial stump fistula after pneumonectomy or lobectomy were treated with two types of covered, retrievable, metallic hinged stents. Type A stent was placed in six patients and type B in two under fluoroscopic guidance. The stent was removed with a retrieval set when BPF was healed or complications occurred.

Results: Stent placement in the bronchial tree was technically successful in all patients, without procedure-related complications. Immediate closure of the BPF was achieved in all patients after the procedure. Stents were removed from all patients but one. Removal of the stents was difficult in two patients due to tissue hyperplasia. Patients were followed for 4-16 months. Placement of the stents remained stable in all patients except one due to severe cough. Permanent closure of BPF was achieved in seven (87.5%) of eight patients.

Conclusion: Use of a covered, retrievable, expandable, metallic hinged stent is a simple, safe, and effective procedure for the closure of bronchial stump fistula. Retrieval of the stent seems feasible.     

Pulmonary cement embolism: a complication of percutaneous vertebroplasty

Background: Percutaneous vertebroplasty (PV) has recently become a very common procedure for vertebral compression fractures. Extravasation of cement, a common event associated with vertebroplasty, may lead to cement emboli in the lungs.

Purpose: To determine the frequency of pulmonary cement embolism after percutaneous vertebroplasty.

Material and Methods: Between 2002 and 2006, 128 percutaneous vertebroplasties were performed in 73 patients (56 women and 17 men) in our institution. Postprocedural chest radiographs were obtained for all patients and assessed for the presence of pulmonary cement emboli.

Results: Pulmonary cement embolism was detected on chest radiographs and confirmed with chest computed tomography (CT) in four patients treated with percutaneous vertebroplasty for osteoporotic collapse and one patient treated for multiple myeloma. The imaging finding of pulmonary cement embolism was solitary or multiple fine radiodense lines with occasional branching patterns. The frequency of pulmonary cement embolism was 6.8%.

Conclusion: An incidence of pulmonary cement embolism of 6.8% during PV was found. Close clinical follow-up, postprocedural chest radiographs, and chest CT scans, if necessary, are important for the detection of pulmonary cement embolism at an early stage.     

Diffusion-weighted magnetic resonance imaging of cerebrospinal fluid in patients with and without communicating hydrocephalus

Background: Recent concepts about cerebrospinal fluid (CSF) circulation in communicating hydrocephalus (CoHy), which is also termed “restricted arterial pulsation hydrocephalus,” suggest reduced arterial pulsations of subarachnoid vessels with a smaller amount of CSF shifted in subarachnoid spaces during the early systole. The postulated restriction of subarachnoid arterial pulsations in CoHy should induce a smaller motion artifact and reduced local stream effects in CSF in magnetic resonance (MR) diffusion-weighted imaging (DWI).

Purpose: To investigate the maximum diffusivity in CSF in patients with and without CoHy using DWI.

Material and Methods: 12 patients without CSF circulation disturbances and six cases with proven CoHy were assessed. Diffusion was measured in six noncollinear directions without triggering the arterial pulse wave (scan time 6:45 min, voxel size 2×2×2 mm). Due to expected artifacts, the calculated maximum diffusivity was called apparent diffusivity. Regional high and low apparent diffusivity was assessed in CSF spaces on newly created 3D CSF motion maps.

Results: Patients with regular CSF circulation exhibited high apparent diffusivity in CSF in basal subarachnoid spaces, whereas apparent diffusivity was low there in patients with CoHy.

Conclusion: DWI opens a feasible approach to study CSF motion in the neurocranium. Restricted arterial pulsations seem to be involved in CoHy.     

Cervical lymph node metastases of unknown origin: primary tumor detection with whole-body positron emission tomography/computed tomography

Background: Identification of primary tumor in patients with cervical lymph node metastasis of unknown primary (MUO) has a great impact on therapy approach and potentially on patient prognosis.

Purpose: To assess the diagnostic accuracy of combined positron emission tomography (PET)/computer tomography (CT) for primary tumor detection in cervical metastases of unknown origin compared to PET, CT, and PET+CT side-by-side evaluation.

Material and Methods: 39 consecutive patients (eight women, 31 men; mean age 59.9±11.2 years) with MUO were enrolled in this study. PET/CT images were obtained 1 hour after injection of 350 MBq of fluorodeoxyglucose. Oral and intravenous contrast agents were administered in all patients to ensure diagnostic CT data. Fused PET/CT data were evaluated for primary tumor detection. Diagnostic accuracy was calculated and compared with CT alone, PET alone, and side-by-side PET+CT evaluation. Statistical analysis of differences in diagnostic performance between the different imaging procedures was based on the McNemar test.

Results: Fused PET/CT depicted the primary tumor in 11 of 39 (28%) patients. In 28 (72%) patients, the primary tumor remained occult. CT revealed the primary in five (13%), PET alone in 10 (26%), and side-by-side evaluation of PET+CT in 10 (26%) of 39 patients. Statistical analysis showed no significant differences between the imaging modalities.

Conclusion: PET, side-by-side PET+CT, and PET/CT revealed similar detection rates for primary tumors in cervical MUO patients. Therefore, cervical metastases of an unknown primary may be assessed with either of these imaging modalities. Detection rates with CT were substantially lower. Thus, inclusion of functional data for assessment of cervical MUO patients must be recommended.     

Magnetic resonance imaging-guided diskography and diagnostic lumbar 0.23T MRI: an assessment study

Purpose: To describe the in vivo appearance of magnetic resonance imaging (MRI) diskograms of normal and degenerated lumbar intervertebral disks, and to evaluate the differences in imaging findings between sequential diagnostic MRI and MRI diskography.

Material and Methods: Nine consecutive patients underwent MRI-guided diskography in order to determine possible pain provocation during puncture and contrast medium injection. All patients had preceding clinical suspicion of lumbar diskogenic pain and findings of lumbar disk degeneration in diagnostic (MRI, computed tomography (CT), plain radiography). A 0.23T open MRI scanner with interventional tools was used for imaging and instrument guidance. On all patients, a complementary diagnostic MRI study of the lumbar spine before and after the MRI-guided disk injection was performed, and subsequent axial MRI diskograms were obtained.

Results: A total of 25 disk punctures were initialized, and 25 MRI diskograms were obtained and their expression described. There was a correlation between the degenerative disk findings visualized by diagnostic MRI and MRI diskograms.

Conclusion: The use of gadolinium contrast media in MRI-guided diskography enables the evaluation of MRI diskograms. Our results suggest that MRI-guided diskography can be used to substitute conventional diskography or CT-diskography and as an augmenting method to assess diagnostic information upon degenerative processes of the lumbar spine.     

Virtual bronchoscopy versus thin section computed tomography in evaluation of moderate and low grade stenoses: receiver operating characteristic curve analysis

Purpose: To evaluate the impact of virtual bronchoscopy, under proper threshold settings, on observer level of confidence in the assessment of bronchial abnormalities producing stenoses ≤75% compared to interpretation of thin section computed tomography (CT) images.

Material and Methods: Sixty-five patients with fiberoptic bronchoscopy positive for tracheobronchial abnormalities were evaluated in a blinded observer study using a commercially available virtual endoscopy software package. The findings of virtual endoscopy were compared with those of fiberoptic bronchoscopy using receiver operating characteristic curves (ROCs) and other statistical tools.

Results: A total of 102 lesions were identified by fiberoptic bronchoscopy, with 44 of these producing bronchial stenoses ≤75%. Concerning the latter lesions, for virtual bronchoscopy the areas under the ROCs were 0.93 and 0.96 for the two observers, respectively, while for thin section CT the corresponding values were 0.86 and 0.88; the differences observed were statistically significant. Contrary to thin section CT, virtual bronchoscopy did not show statistically significant differences from fiberoptic bronchoscopy regarding estimation of degree of stenosis.

Conclusion: Virtual bronchoscopy under proper threshold settings has a statistically significant impact on observer performance where moderate and low-grade bronchial stenoses are concerned and gives an estimate of the degree of stenosis more precisely than thin section CT.