Conventional Chest Computed Tomography Research Articles

Low-Dose Chest CT Protocols for Imaging COVID-19 Pneumonia: Technique Parameters and Radiation Dose.

Chest computed tomography (CT) plays a vital role in the early diagnosis, treatment, and follow-up of COVID-19 pneumonia during the pandemic. However, this raises concerns about excessive exposure to ionizing radiation. This study aimed to survey radiation doses in low-dose chest CT (LDCT) and ultra-low-dose chest CT (ULD) protocols used for imaging COVID-19 pneumonia relative to standard CT (STD) protocols so that the best possible practice and dose reduction techniques could be recommended. A total of 564 articles were identified by searching major scientific databases, including ISI Web of Science, Scopus, and PubMed. After evaluating the content and applying the inclusion criteria to technical factors and radiation dose metrics relevant to the LDCT protocols used for imaging COVID-19 patients, data from ten articles were extracted and analyzed. Technique factors that affect the application of LDCT and ULD are discussed, including tube current (mA), peak tube voltage (kVp), pitch factor, and iterative reconstruction (IR) algorithms. The CTDIvol values for the STD, LDCT, and ULD chest CT protocols ranged from 2.79-13.2 mGy, 0.90-4.40 mGy, and 0.20-0.28 mGy, respectively. The effective dose (ED) values for STD, LDCT, and ULD chest CT protocols ranged from 1.66-6.60 mSv, 0.50-0.80 mGy, and 0.39-0.64 mSv, respectively. Compared with the standard (STD), LDCT reduced the dose reduction by a factor of 2-4, whereas ULD reduced the dose reduction by a factor of 8-13. These dose reductions were achieved by applying scan parameters and techniques such as iterative reconstructions, ultra-long pitches, and fast spectral shaping with a tin filter. Using LDCT, the cumulative radiation dose of serial CT examinations during the acute period of COVID-19 may have been inferior or equivalent to that of conventional CT.

Importance of incidental coronary artery calcification in early diagnosis of obstructive coronary artery disease.

The early diagnosis of coronary artery disease (CAD) enables early intervention for the modifiable risk factors of the disease. Coronary artery calcification (CAC) detected incidentally on standard noncontrast chest computed tomography (CT) provides an opportunity for the early diagnosis of CAD. The purpose of this study was to demonstrate that CAC should be routinely reported when evaluating thoracic CT examinations. Routine reporting of CAC will contribute to the early diagnosis of CAD. The present study included 279 patients who underwent conventional coronary angiography (CAG) and CT within one month before undergoing CAG. The CAG and CT images of the patients were evaluated retrospectively. The levels of coronary artery stenosis were determined in reference to the CAG images. The CAC scores of the patients were calculated using the Weston method based on their chest CT images. The mean age of the patients was 63.2 ± 11.5 (range, 41-93) years, and 172 (61.6%) of them were men. The Weston score (WS) was 0 in 18.9% of the patients with obstructive CAD (OCAD), whereas it was ≥ 7 in 27.9% of patients. All patients with a WS of ≥ 7 had OCAD. All patients without luminal stenosis or < 50% stenosis had a WS of < 7. The CAC score is useful for the diagnosis of CAD and OCAD. If CAC is identified on standard noncontrast chest CT, it should be scored and reported accordingly. The WS can be used for CAC scoring.

Evaluation of AI-Based Segmentation Tools for COVID-19 Lung Lesions on Conventional and Ultra-low Dose CT Scans.

A reliable diagnosis and accurate monitoring are pivotal steps for treatment and prevention of COVID-19. Chest computed tomography (CT) has been considered a crucial diagnostic imaging technique for the injury assessment of the viral pneumonia. Furthermore, the automatization of the segmentation methods for lung alterations helps to speed up the diagnosis and lighten radiologists’ workload. Considering the assiduous pathology monitoring, ultra-low dose (ULD) chest CT protocols have been implemented to drastically reduce the radiation burden. Unfortunately, the available AI technologies have not been trained on ULD-CT data and validated and their applicability deserves careful evaluation. Therefore, this work aims to compare the results of available AI tools (BCUnet, CORADS AI, NVIDIA CLARA Train SDK and CT Pneumonia Analysis) on a dataset of 73 CT examinations acquired both with conventional dose (CD) and ULD protocols. COVID-19 volume percentage, resulting from each tool, was statistically compared. This study demonstrated high comparability of the results on CD-CT and ULD-CT data among the four AI tools, with high correlation between the results obtained on both protocols (R > .68, P < .001, for all AI tools).

Evaluation of the long-term effect of polyhexamethylene guanidine phosphate in a rat lung model using conventional chest computed tomography with histopathologic analysis.

There have been no studies on the effects of polyhexamethylene guanidine phosphate (PHMG) after a long period of exposure in the rodent model. We aimed to evaluate long-term lung damage after PHMG exposure using conventional chest computed tomography (CT) and histopathologic analysis in a rat model. A PHMG solution was intratracheally administrated to 24 male rats. At 8, 26, and 52 weeks after PHMG instillation, conventional chest CT was performed in all rats and both lungs were extracted for histopathologic evaluation. At 52 weeks after PHMG instillation, four carcinomas had developed in three of the eight rats (37.5%). Bronchiolo-alveolar hyperplasia and adenoma were found in rats at 8, 26, and 52 weeks post-instillation. The number of bronchiolo-alveolar hyperplasia significantly increased over time (P-value for trend< 0.001). The severity of lung fibrosis and fibrosis scores significantly increased over time (P-values for trend = 0.002 and 0.023, respectively). Conventional chest CT analysis showed that bronchiectasis and linear density scores suggestive of fibrosis significantly increased over time (P-value for trend < 0.001). Our study revealed that one instillation of PHMG in a rat model resulted in lung carcinomas and progressive and irreversible fibrosis one year later based on conventional chest CT and histopathologic analysis. PHMG may be a lung carcinogen in the rat model.

VMAT Planning With Xe-CT Functional Images Enables Radiotherapy Planning With Consideration of Lung Function.

The most severe adverse event of radiotherapy in lung cancer is radiation pneumonitis (RP). Some indices commonly used to prevent RP are evaluated based on the anatomical lung volume. The irradiation dose may be more accurately assessed by using functional lung volume. We evaluated the usefulness of computed tomography (CT) incorporating functional ventilation images acquired by the inhalation of xenon (Xe) gas (Xe-CT functional images). Two plans were created for twelve patients: volumetric modulated arc therapy (VMAT) planning using conventional chest CT images (anatomical plans) and VMAT planning using Xe-CT functional images (functional plans), and the dosimetric parameters were compared. Compared to the anatomical plans, the functional plans had significantly reduced V 20Gy in the high-functional lungs (p=0.005), but significant differences were not seen in the moderate-functional and low-functional lungs. The incorporation of Xe-CT functional images into VMAT plans enables radiotherapy planning with consideration of lung function.

Application of Mobile Helical Computed Tomography in Combatting COVID-19

Background: Chest computed tomography (CT) is a recommended screening and assessment tool for patients with suspected coronavirus disease (COVID-19). However, CT units are currently not available in many temporary hospitals and centralized isolation places. Objectives: To delineate the workflow of mobile CT unit and evaluate its role in screening for COVID-19 infection in temporary hospitals and centralized isolation locations. Patients and Methods: Two hundred and twenty-three patients under medical observation in temporary centralized isolation were enrolled in this study. All patients underwent reverse-transcription polymerase chain reaction (RT-PCR) testing and mobile CT chest examinations. Communication, storage, and browsing of CT data were performed with 4G and cloud technology. Image quality and radiation dose were evaluated and compared with a commercial conventional 64-row CT scanner. Additionally, the sensitivity of initial chest CT and the initial RT-PCR for COVID-19 were compared. Results: CT examination of 223 patients was completed within 19 work hours. Communication, storage, and browsing of CT data via 4G and cloud technology were seamless. There were no significant differences in subjective image quality scores between groups (P &gt; 0.05). COVID-19 pneumonia was eventually confirmed in 49 patients (21.97%). The sensitivity of initial chest CT was greater than that of the initial RT-PCR (85.71% and 67.35%, respectively) (P &lt; 0.05). Conclusion: Screening suspected patients for COVID-19 by mobile CT in temporary hospitals and isolation points is a simple, efficient, and highly sensitive technique for early diagnosis and control of COVID-19.

Image quality and clinical usefulness of automatic tube current modulation technology in female chest computed tomography screening.

The study was aimed to evaluate the image quality and radiation dose during female chest computed tomography (CT) screening using organ-based tube current modulation technology X-ray combined applications to reduce exposure (XCARE).Five hundred sixty female individuals undergoing chest CT scan were prospectively enrolled and divided into 4 groups based on body mass index (BMI). Then they were randomly and equally divided into control and experimental subgroup and respectively accepted conventional low-dose and XCARE technology spiral CT scan with same parameters. Signal-to-noise ratio and contrast-to-noise ratio were calculated. The quality of the images was evaluated by 2 radiologists using a 5-point scale.Among experimental subgroups of the 4 BMI groups, Signal-to-noise ratios, CT dose index of volume, dose-length product, effective dose, and contrast-to-noise ratio all displayed significant differences, as well as in control subgroups (P < .001). Both the experimental and control subgroups showed an increasing trend in radiation dose with the increasing of BMI. Parameters of image quality and radiation dose displayed no significant differences between control and experimental subgroups in the 4 groups. In multiple linear regression analysis, age and scanning protocol were not associated with radiation dose (P > .05), while BMI was significantly associated with increased CT dose index of volume (P < .05). The display of the lesions for the patients in the control and experimental subgroups of the 4 groups with different BMIs exhibited no statistically significant difference.The same image quality and radiation dose can be obtained using XCARE technology compared to conventional chest CT scans, which can be used regularly in female patients.Advances in knowledge: Using automatic tube current modulation technology to reduce exposure in breast. In this study, we sought a radiation protection method for sensitive tissue in chest CT screening.

Lasting lessons learnt in the radiology department from the battle with COVID-19

Lasting lessons learnt in the radiology department from the battle with COVID-19

OPTimal IMAging strategy in patients suspected of non-traumatic pulmonary disease at the emergency department: chest X-ray or ultra-low-dose chest CT (OPTIMACT) trial\u2014statistical analysis plan

BackgroundA chest X-ray is a standard imaging procedure in the diagnostic work-up of patients suspected of having non-traumatic pulmonary disease. Compared to a chest X-ray, an ultra-low-dose (ULD) chest computed tomography (CT) scan provides substantially more detailed information on pulmonary conditions. To what extent this translates into an improvement in patient outcomes and health care efficiency is yet unknown. The OPTimal IMAging strategy in patients suspected of non-traumatic pulmonary disease at the emergency department: chest X-ray or ultra-low-dose chest CT (OPTIMACT) study is a multicenter, pragmatic, non-inferiority randomized controlled trial designed to evaluate replacement of chest X-ray by ULD chest CT in the diagnostic work-up of such patients, in terms of patient-related health outcomes and costs. During randomly assigned periods of 1 calendar month, either conventional chest X-ray or ULD chest CT scan was used as the imaging strategy. This paper presents in detail the statistical analysis plan of the OPTIMACT trial, developed prior to data analysis.Methods/resultsFunctional health at 28 days is the primary clinical outcome. Functional health at 28 days is measured by the physical component summary scale of the Short Form (SF)-12 questionnaire version 1. Secondary outcomes are mental health (mental component summary scale of the SF-12), length of hospital stay, mortality within 28 days, quality-adjusted life year equivalent during the first 28 days (derived from the EuroQol five-dimension, five-level instrument), correct diagnoses at emergency department discharge as compared to the final post hoc diagnosis at day 28, number of patients in follow-up because of incidental findings on chest X-ray or ULD chest CT, and health care costs.ConclusionsAfter this pragmatic trial we will have precise estimates of the effectiveness of replacing chest X-ray with ULD chest CT in terms of patient-related health outcomes and costs.Trial registrationNetherlands National Trial Register: NTR6163. Registered on 6 December 2016.

Imaging patterns of Pneumocystis jirovecii pneumonia in HIV-positive and renal transplant patients - a multicentre study.

To investigate differences in chest computed tomography (CT) and chest radiographs (CXRs) of Pneumocystis jirovecii pneumonia (PJP) between renal transplant recipients (RTRs) and human immunodeficiency virus (HIV)-positive patients. From 2005 to 2012, 84 patients with PJP (RTR n = 24; HIV n = 60) were included in this retrospective multicentre study. Written informed consent was obtained. CT scans and CXRs were recorded within 2 weeks after the onset of symptoms. PJP diagnosis was confirmed either by cytology/histology or successful empirical treatment. Two blinded radiologists analysed the conventional chest films and CT images, and recorded the radiological lung parenchyma patterns, lymph node enlargement and pleural pathologies (pneumothorax, effusion). The radiological features of the two subgroups were compared. Consolidations and solid nodules prevailed on CT in RTRs (91.7 &plusmn; 5.6% vs 58.3 &plusmn; 6.4% with HIV, p = 0.019 and 91.7 &plusmn; 5.6% vs 51.6 &plusmn; 6.5% with HIV, p = 0.005). HIV-positive patients with PJP showed more atelectasis (41.7 &plusmn; 6.4% vs 4.2 &plusmn; 4.1% in RTRs, p = 0.017) and hilar lymph node enlargement (23.3 &plusmn; 5.5% vs 0.0 &plusmn; 0.0% in RTRs, p = 0.088). Ground glass opacification was found in all cases. Pneumothorax was a rare complication, occurring in 3% of the HIV-positive patients; no pneumothorax was found in the RTRs. On CXR, the basal lungs were more affected in HIV-positive patients as compared with RTRs (p = 0.024). PJP on CT differs substantially between RTRs and HIV-positive patients. Physicians should be aware of such differences in order not to delay treatment, particularly in renal transplant recipients.

Preoperative assessment of parietal pleural invasion/adhesion of subpleural lung cancer: advantage of software-assisted analysis of 4-dimensional dynamic-ventilation computed tomography.

To evaluate the accuracy of four-dimensional (4D) dynamic-ventilation computed tomography (CT) scanning coupled with our novel image analysis software to diagnose parietal pleural invasion/adhesion of peripheral (subpleural) lung cancer. Eighteen patients with subpleural lung cancer underwent both 4D dynamic-ventilation CT during free breathing and conventional (static) chest CT during preoperative assessment. The absence of parietal pleural invasion/adhesion was surgically confirmed in 13 patients, while the presence of parietal pleural invasion/adhesion was confirmed in 5 patients. Two chest radiologists, who were blinded to patient status, cooperatively evaluated the presence of pleural invasion/adhesion using two different imaging modalities: (i) conventional high-resolution CT images, reconstructed in the axial, coronal, and sagittal directions, and (ii) 4D dynamic-ventilation CT images combined with a color map created by image analysis software to visualize movement differences between the lung surface and chest wall. Parameters of diagnostic accuracy were assessed, including a receiver operating characteristic analysis. Software-assisted 4D dynamic-ventilation CT images achieved perfect diagnostic accuracy for pleural invasion/adhesion (sensitivity, 100%; specificity, 100%; area under the curve [AUC], 1.000) compared to conventional chest CT (sensitivity, 60%; specificity, 77%; AUC, 0.846). Software-assisted 4D dynamic-ventilation CT can be considered as a novel imaging approach for accurate preoperative analysis of pleural invasion/adhesion of peripheral lung cancer. • 4D dynamic-ventilation CT can correctly assess parietal pleural invasion/adhesion of peripheral lung cancer. • A unique color map clearly demonstrates parietal pleural invasion/adhesion. • Our technique can be expanded to diagnose "benign" pleural adhesions for safer thoracoscopic surgery.

Background: Coronary artery calcification, of established predictive value, can be assessed by conventional chest computed tomography (CT). Objective: To assess the prognostic value of nomograms for global plaque burden applied to data obtained by convent

Background: Coronary artery calcification, of established predictive value, can be assessed by conventional chest computed tomography (CT). Objective: To assess the prognostic value of nomograms for global plaque burden applied to data obtained by conventional chest CT scan. Methods: Consecutive patients between 40 and 74 years undergoing clinically indicated conventional chest CT scan at our institution were included between August and December 2012. The presence and extent of coronary artery calcifications was evaluated and the patients were grouped according to age- and sex-adjusted percentiles of segment involvement score (CACSIS). Results: A total of 1,194 patients were included in the study. After a mean follow-up of 3.7±0.5 years, 53 (4.4%) patients died. There was a significant association between sex- and age-adjusted survival rates and CACSIS (RR1.27; 95% CI, 1.01-1.60, p=0.040). Conclusions: Age-adjusted nomograms for global atherosclerotic plaque burden applied to conventional chest CT scan were predictors of mortality.

High pitch third generation dual-source CT: Coronary and cardiac visualization on routine chest CT

BackgroundChest CT scans are frequently performed in radiology departments but have not previously contained detailed depiction of cardiac structures. ObjectivesTo evaluate myocardial and coronary visualization on high-pitch non-gated CT of the chest using 3rd generation dual-source computed tomography (CT). MethodsCardiac anatomy of patients who had 3rd generation, non-gated high pitch contrast enhanced chest CT and who also had prior conventional (low pitch) chest CT as part of a chest abdomen pelvis exam was evaluated. Cardiac image features were scored by reviewers blinded to diagnosis and pitch. Paired analysis was performed. Results3862 coronary segments and 2220 cardiac structures were evaluated by two readers in 222 CT scans. Most patients (97.2%) had chest CT for oncologic evaluation. The median pitch was 2.34 (IQR 2.05, 2.65) in high pitch and 0.8 (IQR 0.8, 0.8) in low pitch scans (p < 0.001). High pitch CT showed higher image visualization scores for all cardiovascular structures compared with conventional pitch scans (p < 0.0001). Coronary arteries were visualized in 9 coronary segments per exam in high pitch scans versus 2 segments for conventional pitch (p < 0.0001). Radiation exposure was lower in the high pitch group compared with the conventional pitch group (median CTDIvol 10.83 vs. 12.36 mGy and DLP 790 vs. 827 mGycm respectively, p < 0.01 for both) with comparable image noise (p = 0.43). ConclusionMyocardial structure and coronary arteries are frequently visualized on non-gated 3rd generation chest CT. These results raise the question of whether the heart and coronary arteries should be routinely interpreted on routine chest CT that is otherwise obtained for non-cardiac indications.

Standard chest CT using combined automated tube potential selection and iterative reconstruction: image quality and radiation dose reduction

ObjectiveTo evaluate the image quality and radiation dose reduction of chest computed tomography (CT) using combined automated tube potential selection (ATPS) and iterative reconstruction (IR). Materials and MethodsImage quality and radiation dose were compared between conventional contrast-enhanced chest CT using 120 kVp and filtered back projection (Protocol A) and CT using ATPS and IR (Protocol B) in 43 patients. ResultsThe effective radiation dose was 3.6±0.4 mSv for Protocol A and 2.2±0.6 mSv for Protocol B (mean dose reduction, 39.7%). Protocol B showed diagnostic image quality in all patients. ConclusionATPS and IR allows for radiation dose reduction while maintaining diagnostic image quality.

Incidental detection of clinically unexpected breast lesions by computed tomography

Increased use of computed tomography (CT) has resulted in greater detection of incidental breast lesions unrelated to the primary diagnostic inquiry. To investigate the morphology and clinical significance of breast abnormalities detected incidentally by conventional CT. A total of 2945 female patients underwent CT examinations of the body, including the chest, from May 2006 to April 2010. Two radiologists interpreted these CT scans independently and pointed out a mass or non-mass-like lesion as abnormalities in the breast. Patients who incidentally showed breast lesions on CT scans were identified by a computer-based search of the diagnostic reports and were enrolled in this study. The morphology and enhancement patterns of CT-detected breast lesions were evaluated according to BI-RADS-MRI. In total, 32 clinically unexpected abnormal breast lesions were found in 31 (1.1%) patients. Twenty-nine of the 32 lesions were detected by contrast-enhanced CT and three by unenhanced CT. Ten breast cancers were found in 10 patients (0.34%), which yielded the prevalence for malignancy of 31% (10/32). Invasive ductal carcinomas accounted for eight lesions, while two were ductal carcinomas in situ (DCIS). Nine lesions were depicted as a mass and one DCIS was a non-mass-like lesion. Good morphological predictors of breast cancers for a mass were an irregular shape, a lobulated shape, and an irregular margin. Benign lesions accounted for 22 lesions from 21 patients (0.71%). Of these, 13 lesions in 13 patients were depicted as a mass and nine lesions in nine patients as a non-mass-like lesion. Unexpected breast lesions can be identified as a mass or non-mass-like lesion on conventional chest CT scans. Among these, breast cancers that are not clinically apparent occur with considerable prevalence. We suggest that careful interpretation of the breast should be a routine part of CT examinations.

Value of 18F-FDG-PET/CT in patients with fever of unknown origin and unexplained prolonged inflammatory syndrome: a single centre analysis experience

The aim of our study was to evaluate the diagnostic contribution of (18)F-fluoro-deoxyglucose ((18)F-FDG)-positron emission tomography (PET)/computed tomography (CT) in patients with fever of unknown origin (FUO) or unexplained prolonged inflammatory syndrome (UPIS) in real life. We performed a retrospective study including 14 patients with FUO or UPIS hospitalised in our institution (Strasbourg University Hospital, France) between January 2005 and July 2006. (18)F-FDG-PET/CT was considered helpful when abnormal results allowed an accurate diagnosis. (18)F-FDG-PET/CT was helpful in half the patients (7/14) for final diagnosis. A diagnosis was reached in 87.5% of the patients (7/8) with an abnormal (18)F-FDG-PET/CT but only in 50% of the patients (3/6) with a normal (18)F-FDG-PET/CT. Conventional chest and abdominal CT was performed in 13 patients before ordering (18)F-FDG-PET/CT. We considered that (18)F-FDG-PET/CT was essential to establish the final diagnosis in only 23% of the patients (3/13) since neither chest nor abdominal CT identified abnormalities consistent with the final diagnosis. However, among the three patients, two were diagnosed with large vessel vasculitis and one patient with local prosthetic infection. Our study supports the potential interest of (18)F-FDG-PET/CT in the diagnostic workup of FUO and UPIS as it helped establish a fine diagnosis in half of the cases. However, (18)F-FDG-PET/CT appeared to be essential to the final diagnosis in only 23% of the cases. In our opinion, this protocol should be performed as a second level test, especially when conventional CT is normal or is unable to discriminate between active and silent lesions.

Simulated dose reduction in conventional chest CT: validation study.

To validate a technique of computer-simulated dose reduction for conventional chest computed tomography (CT). In 27 patients, CT scans were obtained at 200, 100, and 40 mAs at two levels. The raw data from the 200-mAs scan were modified on a computer workstation to simulate the increased noise present on 100- and 40-mAs scans. Real and simulated 100- and 40-mAs images were independently assessed in random order for overall image quality and radiologic findings by four subspecialty-trained chest radiologists who were blinded to the technique. The four observers were given paired real and simulated images. They were asked to identify the real image and note any difference in diagnostic quality. No difference was seen in overall image quality or radiologic findings between real and simulated images (P > .05). In the paired comparison, 433 of 864 (50.1%) real images were correctly identified. Computer modification of 200-mAs raw scan data to simulate 100- and 40-mAs noise levels produces reconstructed images indistinguishable from real 100- and 40-mAs scans. This technique provides realistic reduced-dose images without patient radiation exposure and with identical image registration and motion artifact.

Imaging of thoracic Wegener's granulomatosis: The computed tomographic appearance

purpose: Computed tomography (CT) can play a major role in the examination of patients with diffuse infiltrative disorders of the lung. CT patterns of thoracic Wegener's granulomatosis were retrospectively evaluated in this study. The CT appearance was compared with imaging obtained by conventional plain roentgenograms.patients and methods: Fourteen patients with Wegener's granulomatosis seen during the last 5 years are described. Conventional chest roentgenograms and CT scans from these patients are reviewed.results: The most frequent manifestation found in the lungs of patients with Wegener's granulomatosis was that of rounded opacities with or without cavitation. This was observed in 7 of 14 patients. Relatively unexpected was the frequent occurrence of bronchovascular bundle cuffing with a quite constant and characteristic bronchocentric distribution. This finding was observed in 5 of 14 patients. Vasculitis sign was demonstrated in 2 of 14 patients. Widespread acinar infiltrates, usually confluent, were common and were seen in 5 of 14 of our patients; in 2 of the patients, these infiltrates were due to diffuse pulmonary hemorrhage. Tracheal stenosis was the cause of sudden acute respiratory failure that was observed in one patient. Pleural disease was present in 3 of 14 patients. Hilar and mediastinal lymphadenopathy was observed in one patient. An interstitial pattern was observed in 3 of 14 patients.conclusions: We conclude that an extremely wide spectrum of radiologic findings may be observed in this disease. In 14 patients we found 11 different roentgenographic manifestations; moreover, in 8 patients it was possible to describe more than 1 radiologic manifestation at the same time or during the course of the disease. This observation is not surprising, if we consider the wide variability and broad spectrum of pathologic features in pulmonary Wegener's granulomatosis. Because conventional roentgenograms failed in a great number of cases to visualize the exact pattern and the extent of thoracic involvement, we believe that CT is particularly helpful for the assessment of pulmonary involvement in Wegener's granulomatosis.