Protective effect on subjects receiving lung CT scan / 中国辐射卫生

Objective To determine the radiation dose of sensitive organs under different protective methods in lung CT scanning environment, and to explore the best protective scheme of corresponding organs. Methods Annealed thermoluminescence dose elements were placed in the stomach, liver, colon, and thyroid gland of a simulated human body model. The dose effect experiment of protective methods included non-protective group, half lead apron group, and full lead apron group. The dose effect experiment of protective thickness included 0.50 mmpb full lead apron group and 0.35 mmpb full lead apron group. The same exposure conditions of lung CT scan were used in the above experiments. Results Compared with the non-protective group, the exposure dose of the stomach, liver, colon, and thyroid gland increased significantly in the half lead apron group (P < 0.05), and the exposure dose of the thyroid gland and colon decreased significantly in the full lead apron group (P < 0.05). There were no significant differences in the exposure dose of the liver, stomach, and colon in the simulated human body model between the 0.35 mmpb full lead apron group and the 0.50 mmpb full lead apron group. Conclusion For lung CT scan, the protective measure of lead apron may not reduce the exposure dose of subjects. The protective thickness of lead apron does not necessarily have a substantial influence on the exposure dose of human body.

Analysis of clinical features and related factors of coronavirus disease 2019 in Shanghai / 上海交通大学学报（医学版）

Objective • To explore the common clinical features of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-infected local patients in Shanghai and their related influencing factors. Methods • A total of 320 patients admitted to Shanghai Public Health Clinical Center from January to March 2020 and diagnosed as having coronavirus disease 2019(COVID-19) were selected. Clinical data of the patients were collected to analyze their characteristics. Using the statistical operation formula of R language, the correlation analysis of hospitalization days, days of increased hypersensitive C-reactive protein concentration (allergic days), days of lung CT improvement (CT days), and days required for nucleic acid turning negative with the main clinical manifestations and laboratory data was carried out. The correlation factors affecting the above four variables were analyzed. Results • Among the 320 patients, the proportions of mild type, moderate type, serious type and critical type were 6.25%, 83.44%, 6.88% and 3.44%, respectively; 91.25% of them had a history of exposure to Hubei. The proportions of fever, cough, sputum and fatigue were 79.06%, 46.56%, 21.56% and 15.31%, respectively. Spearman correlation analysis showed that the concentrations of lactate dehydrogenase, interleukin-2(IL-2) and IL-6 were positively correlated with the above four variables, respectively (all P<0.05), albumin concentration was negatively correlated with allergic days (P=0.018), and CD4+ cell count was negatively correlated with CT days and days required for nucleic acid turning negative (both P<0.05). Stepwise multiple linear regression analysis showed that procalcitonin (PCT) concentration was negatively correlated with hospitalization days, CT days and allergic days (both P<0.05), and disease type was positively correlated with hospitalization days, allergic days, CT days and days required for nucleic acid turning negative (all P<0.05). Conclusion • Moderate type is common in the local patients in Shanghai; fever, cough and fatigue are common symptoms, and most of the patients are accompanied by lung CT abnormalities. The therapeutic effect and prognosis of these patients are closely related to disease type, concentrations of PCT and IL-6, as well as CD4+ cell count.

Three-year clinical application practice report of lung ultrasound in our NICU / 中国小儿急救医学

Objective To retrospectively analyze the application of lung ultrasound in neonatal de-partment of our hospital in the past three years,and summed up the clinical diagnosis and treatment changes brought by it. Methods The clinical data of infants accepted the bedside lung ultrasound examination from May to December 2016(early carry out stage),from January to December 2017(adaptation stage),from Jan-uary to August 2018(normal conduct stage) in our NICU of Jingzhou Central Hospital were collected. The clinical data of 878 infants with different stages of application were compared and analyzed. Results In 878 children,1 225 of lung ultrasound were performed,64. 1% of patients had pulmonary disease,and 35. 9% had no lung disease. There were 67 cases of neonatal respiratory distress syndrome,278 cases of wet lung,259 ca-ses of pneumonia,64 cases of meconium aspiration syndrome,72 cases of acute respiratory distress syn-drome,63 cases of atelectasis and 14 cases of pleural effusion. A total of 1 122 times of lung X-ray examina-tion were performed in 878 children. The number of X-ray examinations per capita decreased from 2. 48 times in 2016 to 1. 40 times in 2017 and 0. 84 times in 2018. A total of 32 times of pulmonary CT examination were performed. The number of lung CT inspection decreased from 0. 060 times in 2016 to 0. 038 times in 2017 and 0. 029 times in 2018. Lung ultrasound was convenient for dynamic observation,and could be used to de-termine the improvement,aggravation or new pulmonary lesions. Conclusion Lung ultrasound is accurate in the diagnosis of lung disease in NICU,especially for children with long hospital stay,repeated illness and dif-ficult to withdraw. It is easy to carry out in clinic,at the bedside,which can reduce the times of chest X-ray and CT per capita examination. Lung ultrasound is an effective and feasible method for NICU to diagnose lung diseases and it is worth promoting.

Combined Electrocardiography- and Respiratory-Triggered CT of the Lung to Reduce Respiratory Misregistration Artifacts between Imaging Slabs in Free-Breathing Children: Initial Experience

OBJECTIVE: Cardiac and respiratory motion artifacts degrade the image quality of lung CT in free-breathing children. The aim of this study was to evaluate the effect of combined electrocardiography (ECG) and respiratory triggering on respiratory misregistration artifacts on lung CT in free-breathing children. MATERIALS AND METHODS: In total, 15 children (median age 19 months, range 6 months–8 years; 7 boys), who underwent free-breathing ECG-triggered lung CT with and without respiratory-triggering were included. A pressure-sensing belt of a respiratory gating system was used to obtain the respiratory signal. The degree of respiratory misregistration artifacts between imaging slabs was graded on a 4-point scale (1, excellent image quality) on coronal and sagittal images and compared between ECG-triggered lung CT studies with and without respiratory triggering. A p value < 0.05 was considered significant. RESULTS: Lung CT with combined ECG and respiratory triggering showed significantly less respiratory misregistration artifacts than lung CT with ECG triggering only (1.1 ± 0.4 vs. 2.2 ± 1.0, p = 0.003). CONCLUSION: Additional respiratory-triggering reduces respiratory misregistration artifacts on ECG-triggered lung CT in free-breathing children.

Pulmonary Cryptococcosis: Imaging Findings in 23 Non-AIDS Patients

OBJECTIVE: We aimed to review the patterns of lung abnormalities of pulmonary cryptococcosis on CT images, position emission tomography (PET) findings of the disease, and the response of lung abnormalities to the therapies in non-AIDS patients. MATERIALS AND METHODS: We evaluated the initial CT (n = 23) and 18F-fluorodeoxyglucose (FDG) PET (n = 10), and follow-up (n = 23) imaging findings of pulmonary cryptococcosis in 23 non-AIDS patients. Lung lesions were classified into five patterns at CT: single nodular, multiple clustered nodular, multiple scattered nodular, mass-like, and bronchopneumonic patterns. The CT pattern analyses, PET findings, and therapeutic responses were recorded. RESULTS: A clustered nodular pattern was the most prevalent and was observed in 10 (43%) patients. This pattern was followed by solitary pulmonary nodular (n = 4, 17%), scattered nodular (n = 3, 13%), bronchopneumonic (n = 2, 9%), and single mass (n = 1, 4%) patterns. On PET scans, six (60%) of 10 patients showed higher FDG uptake and four (40%) demonstrated lower FDG uptake than the mediastinal blood pool. With specific treatment of the disease, a complete clearance of lung abnormalities was noted in 15 patients, whereas a partial response was noted in seven patients. In one patient where treatment was not performed, the disease showed progression. CONCLUSION: Pulmonary cryptococcosis most commonly appears as clustered nodules and is a slowly progressive and slowly resolving pulmonary infection. In two-thirds of patients, lung lesions show high FDG uptake, thus simulating a possible malignant condition.

Pulmonary Venous Malformation in a 4-Year-Old Boy: a Case Report

We report a case of a pulmonary venous malformation in a 4-year-old boy who presented with recurrent pneumonia. A radiograph revealed a right infrahilar mass and a hyperlucent right lung. Computed tomography (CT) demonstrated a mass containing intensely enhancing areas and multiple phleboliths located in the right lower lobe and encasing the right bronchus and right inferior pulmonary vein. Magnetic resonance imaging (MRI) precisely revealed the mass demarcation. A right lower lobectomy was performed and a pathological examination confirmed the diagnosis of a venous malformation. To the best of our knowledge, a venous malformation in pulmonary tissue has not been reported in the English literature. Herein, we report a case of a pulmonary venous malformation, with the radiograph, CT, MRI, and blood pool scan findings, along with its pathologic correlation.

Pulmonary Complication of Novel Influenza A (H1N1) Infection: Imaging Features in Two Patients

Novel influenza A (H1N1) virus is the pathogen of recent global outbreaks of febrile respiratory infection. We herein report the imaging findings of pulmonary complication in two patients with novel influenza A (H1N1) infection. The first patient without secondary infection showed the ill-defined ground-glass opacity nodules and patch areas of ground-glass opacities. The second patient with secondary pneumococcal pneumonia showed areas of lobar consolidation in the right middle lobe and left lower lobe and ground-glass opacities.

Radiofrequency Ablation Using a Monopolar Wet Electrode for the Treatment of Inoperable Non-Small Cell Lung Cancer: a Preliminary Report

OBJECTIVE: To assess the technical feasibility and complications of radiofrequency ablation (RFA) using a monopolar wet electrode for the treatment of inoperable non-small cell lung malignancies. MATERIALS AND METHODS: Sixteen patients with a non-small cell lung malignancy underwent RFA under CT guidance. All the patients were non-surgical candidates, with mean maximum tumor diameters ranging from 3 to 6 cm (mean: 4.6 +/- 1.1 cm). A single 16-gauge open-perfused electrode with a 2 cm exposed tip was used for the procedure. A 0.9% NaCl saline solution was used as the perfusion liquid with the flow adjusted to 30 mL/h. The radiofrequency energy was applied for 10-40 minutes. The response to RFA was evaluated by performing contrast-enhanced CT immediately after RFA, one month after treatment and then every three months thereafter. RESULTS: Technical failure was observed in six (37.5%) of 16 patients: intractable pain (n = 2) and non-stop coughing (n = 4). The mean follow-up interval was 15 +/- 8 months (range: 9-31 months). The mean maximum ablated diameter in the technically successful group of patients ranged from 3.5 to 7.5 cm (mean 5.1 +/- 1.3 cm). Complete necrosis was attained for eight (80%) of 10 lesions, and partial necrosis was achieved for two lesions. There were two major complications (2/10, 20%) encountered: a hemothorax (n = 1) and a bronchopleural fistula (n = 1). CONCLUSION: Although RFA using a monopolar wet electrode can create a large ablation zone, it is associated with a high rate of technical failure when used to treat inoperable non-small cell lung malignancies.

Bronchial Asthma: Correlation of Quantitative CT and the Pulmonary Function Test

PURPOSE: The purpose of this study was to assess the availability of quantitative computed tomography (QCT) in the evaluation of asthma patients and to correlate its use with the pulmonary function test (PFT). MATERIALS AND METHODS: Thirty asthmatic patients and thirty normal volunteers were prospectively evaluated by the use of HRCT and the PFT. By using 16 slice MDCT, HRCT was performed from the apex to the base of both lungs at the end inspiration and end expiration periods in all patients and images were reconstructed to a thickness of 1 mm (window level: -750 HU, window width: 1,500 HU). We analyzed each image for the whole lung using the Pulmo CT program. PFTs including FVC and FEV1 were performed one week prior and one week after the completion of a HRCT. The Difference of QCT (the mean lung density and subrange ratio) between volunteers and asthmatic patients was analyzed by using the Student's t-test. Spearman's correlation test was used to determine the association between PFT and QCT. RESULTS: The mean lung density (MLD) and subrange ratio were lower in asthmatic patients than in volunteers for end expiration and no difference was seen between asthmatic patients and volunteers for end inspiration. FVC and FEV1 were lower in asthmatic patients than in volunteers. A decrease in FVC and FEV1 correlated with changes in the MLD and subrange ratio for end expiration. CONCLUSION: QCT such as MLD and the subrange ratio using HRCT can be used to indirectly assess the pulmonary function of the asthma patient. The PFT seems to correlate better with the MLD and subrange ratio for expiratory QCT of the asthma patient than with inspiratory QCT.

CT Findings of Swyer-James-MacLeod Syndrome in Adults: Are There Any Different Findings with Aging?

PURPOSE: We wanted to evaluate whether there is any different finding on CT with aging for the patients suffering with adult Swyer-James-MacLeod Syndrome (SJMS). MATERIALS AND METHODS: We included 11 patients (7 males and 4 females) who underwent chest CT scan among 18 patients who were suspected of suffering with SJMS on chest radiographs. The range of age was from 28 to 85 years (mean: 58.5). We evaluated the diameter of both the main pulmonary artery (MPA) with its ratio, and the diameter of the pulmonary trunk (PT) to evaluate the possibility of pulmonary arterial hypertension, and the presence or absence of bronchiectasis. We also evaluated the relationships between these findings and aging. RESULTS: SJMS affected the left lung in 10 of 11 patients. The mean diameter of the main pulmonary artery of the normal lung was 2.5 cm and it was 1.6 cm in the involved site. The mean ratio of the normal MPA diameter to the involved one was 1.6 and this did not correlate with age (p>0.1). The mean diameter of the pulmonary trunk was 2.8 cm and this increased with age (p0.5). CONCLUSION: SJMS absolutely affected the left lung much more than the right lung. All the patients demonstrated about 1.6 times the compensatory hypertrophy of MPA of the normal lung compared with that of the affected lung on chest CT, which was irrespective of age. The presence or absence of bronchiectasis has no correlation with age.

Pulmonary Tuberculosis Involving the Right Middle Lobe of the Lung: CT and Clinical Characteristics

PURPOSE: To describe the CT and clinical features of tuberculosis involving the right middle lobe of the lung. MATERIALS AND METHODS: Among patients diagnosed with pulmonary tuberculosis at our hospital during the past three years, 16 cases (mean age of patients: 72 years) were reviewed for radiological and clinical presentation of patients that underwent CT and chest radiography and showed mainly right middle lobe involvement. RESULTS: Middle lobe collapse or consolidation (n=16) and bronchial stenosis or obstruction without the presence of soft tissue masses (n=15) were the main findings. Enlarged mediastinal or hilar lymph nodes (n=15), cavities within consolidated tissue (n=2), ill-defined centrilobular nodules (n=12), a tree-in-bud appearance (n=10), focal consolidations (n=7) and small nodules (n=4) were found. All patients were older than 64 years and most complained of non-specific symptoms. A sputum smear for AFB was positive in four cases. CONCLUSION: A diagnosis of tuberculosis in the right middle lobe is suggested in older patients with following CT findings: 1) middle lobe collapse or consolidation; 2) middle lobe bronchus stenosis or obstruction without the presence of soft tissue masses; 3) mediastinal or hilar lymphadenopathy; 4) cavities within consolidation, and centrilobular nodules with branching linear structure in the adjacent lungs. Further evaluation such as bronchoscopy is recommended for confirmation even when the sputum smear for AFB is negative.

Nodular Ground-Glass Opacities on Thin-section CT: Size Change during Follow-up and Pathological Results

OBJECTIVE: To evaluate the inter-group differences in growth and the pathological results of nodular ground-glass opacities (GGOs) according to their size and focal solid portions. MATERIALS AND METHODS: Ninety-six nodular GGOs in 55 individuals followed by CT for at least one month from an initial chest CT were included. Forty nodular GGOs in 30 individuals were pathologically confirmed to be: adenocarcinoma (n = 15), bronchioloalveolar carcinoma (BAC) (n = 11), atypical adenomatous hyperplasia (AAH) (n = 8), focal interstitial fibrosis (n = 5) and aspergillosis (n = 1). Lesions were categorized based on high-resolution CT findings: pure nodular GGO (PNGGO) 10 mm, mixed nodular GGO (MNGGO) 10 mm. In each group, the change in size during the follow-up period, the pathological results and the rate of malignancy were evaluated. RESULTS: Three MNGGO lesions, and none of the PNGGO, grew during the follow-up period. Resected PNGGOs 10 mm were focal interstitial fibrosis (n = 4), AAH (n = 2), BAC (n = 2), and adenocarcinoma (n = 2). Resected MNGGOs 10 mm were adenocarcinoma (n = 11), BAC (n = 3), and aspergillosis (n = 1). CONCLUSION: Mixed nodular GGOs (MNGGOs) had the potential for growth; most were pathologically adenocarcinoma or BAC. By contrast, PNGGOs were stable for several months to years; most were AAH, BAC, or focal interstitial fibrosis.

An Automated Classification System for the Differentiation of Obstructive Lung Diseases based on the Textural Analysis of HRCT images

PURPOSE: To develop an automated classification system for the differentiation of obstructive lung diseases based on the textural analysis of HRCT images, and to evaluate the accuracy and usefulness of the system. MATERIALS AND METHODS: For textural analysis, histogram features, gradient features, run length encoding, and a co-occurrence matrix were employed. A Bayesian classifier was used for automated classification. The images (image number n=256) were selected from the HRCT images obtained from 17 healthy subjects (n=67), 26 patients with bronchiolitis obliterans (n=70), 28 patients with mild centrilobular emphysema (n=65), and 21 patients with panlobular emphysema or severe centrilobular emphysema (n=63). An five-fold cross-validation method was used to assess the performance of the system. Class-specific sensitivities were analyzed and the overall accuracy of the system was assessed with kappa statistics. RESULTS: The sensitivity of the system for each class was as follows: normal lung 84.9%, bronchiolitis obliterans 83.8%, mild centrilobular emphysema 77.0%, and panlobular emphysema or severe centrilobular emphysema 95.8%. The overall performance for differentiating each disease and the normal lung was satisfactory with a kappa value of 0.779. CONCLUSION: An automated classification system for the differentiation between obstructive lung diseases based on the textural analysis of HRCT images was developed. The proposed system discriminates well between the various obstructive lung diseases and the normal lung.

The Rapid Evolution of CT Findings in Pulmonary Langerhans Cell Histiocytosis: A Case Report

Imaging findings of pulmonary Langerhans cell histiocytosis (PLCH) demonstrate evolving changes over time, and the radiological transitions shown by imaging tools may allow a prediction of histopathological activity in PLCH. However, there are no reports describing how rapidly CT findings change with time. We describe a case of PLCH that showed a rapid evolutional change of the pulmonary lesions in a 48-year-old man, in which the nodular lesions showed cystic changes within two-month follow-up periods on chest CT scans.

Radiologic Approach to Diffuse Infiltrative Lung Disease

The Radiology approach to diffuse infiltrative lung disease (DILD) is based on a chest radiography and CT. Chest radiography can categorize DILD into five main patterns of abnormality: linear, reticular, cystic, nodular, and ground-glass patterns. The CT patterns of DILD can be classified into six patterns including thickened interlobular septa, reticular, cystic, nodular, ground-glass, and consolidation patterns. The pertinent differential diagnosis of DILD is based on the pattern recognition approach of abnormalities, and a specific diagnosis can often be made using chest radiography and CT. This pictorial essay illustrates the radiology pattern recognition approach for DILD using chest radiography and CT.

Usefulness of Perfusion CT in Progressive Massive Fibrosis

PURPOSE: We wanted to evaluate the usefulness of perfusion CT for the diagnosis of progressive massive fibrosis. MATERIALS AND METHODS: We retrospectively analyzed the perfusion CT images of 20 lesions that showed progressive massive fibrosis in 13 patients. Using 16 channel multi-detector CT, a dynamic study was performed with the multiple spiral acquisition technique at 0 (precontrast), 15, 30, 45, 60, 90, 120, 180, and 300 seconds after contrast injection. The perfusion image was reformatted using these source images; it was scored on the volume map and washout map by visual inspection and then compared with 20 lesions of lung cancer. RESULTS: The volume map showed either middle or low perfusion for 19 among the 20 lesions. The washout map also showed a weak or moderate washout pattern. The kappa values (>0.818) for the inter-reader agreement reached statistical significance (p<0.01). High perfusion on the volume map was seen in 1 case (5%) in the PMF group and in 19 cases (95%) in the lung cancer group. Intense washout on the washout map was seen in 1 case (5%) in the PMF group and in 14 cases (70%) in the lung cancer group. There was a significant difference between the two groups (x2=32.129, p<0.01). CONCLUSION: Perfusion CT consisting of the volume map and washout map can be a useful method for the differential diagnosis between PMF and lung cancer.

Comparison of the CT and Pathologic Findings of Pulmonary Fat Embolism Induced by Triolein and Oleic Acid in Rabbits

PURPOSE: The aim of this study was to evaluate the CT findings of pulmonary fat embolism syndrome that was induced by triolein and oleic acid, along with its pathologic correlation. MATERIALS AND METHODS: 16 rabbits were included in this study. The rabbits in group I (n=8) were embolized with 0.2 mL triolein and the rabbits of group II (n=8) were embolized with 0.2 mL oleic acid through ear veins. HRCT scans were done prior to embolization and at 0.5, 4, 24, 48 and 72 hours post-embolization. The pathologic correlations were determined at 0.5, 24, 48 and 72 hours. RESULTS: At 24 hours, one group I rabbit showed abnormal CT findings that were composed of several 2-3 mm nodules and multiple ill-defined peripheral ground glass opacities. The pathologic finding of this rabbit at 48 hours was mainly intraarveolar edema. All the group II rabbits (n=8/8) showed ill-defined bilateral and peripheral ground glass opacities with (n=6/8) or without consolidations (n=2/8) on the 0.5 hour CT. All the rabbits (n=7/7) showed that the new ground glass opacities and ground glass opacities noted on the 0.5 hour CT were changed into consolidation. The margins of the ground glass opacities and consolidations were more sharpened on the 24 hours CT. All 6 rabbits (n=6/6) showed consolidations without ground glass opacities and the margins of the consolidations were more sharpened on the 48 hours CT. There was no significant interval change on the 72 hours CT. The pathologic findings of ground glass opacities were interstitial edema or mild intraalveolar edema. The pathologic findings of consolidation were intraalveolar edema, hemorrhage and coagulation necrosis. CONCLUSION: The CT findings after fat embolization using triolein and oleic acid were ill-defined peripheral ground glass opacities with/without consolidations. These findings occurred in only one triolein group with the time lag, but these findings were immediately and extensively seen in all group II rabbits. These CT findings may be important for making a diagnosis of pulmonary fat embolism syndrome.

Effect of High Dose Steroids on Oleic Acid-induced Lung Injury in Rabbits: CT Findings

PURPOSE: The purpose of this study is to evaluate the therapeutic efficacy, on the basis of CT findings, of high dose methyl prednisolone for treating acute lung injury that was induced by oleic acid injection. MATERIALS AND METHODS: A total of 30 healthy rabbits (1.8-2.2 kg) were included in this study. Group I included 10 rabbits in which 0.2 mL oleic acid was injected through their ear veins. Group IIa included 10 rabbits in which 30 mg/kg methyl prednisolone and 0.2 mL oleic acid were intravenously injected at the same time. Group IIb included 5 rabbits in which 30 mg/kg methyl prednisolone was injected 6 hours prior to the 0.2 mL oleic acid intravenous injection. The other 5 rabbits (Group III) were injected intravenously with 30 mg/kg methyl prednisolone without the oleic acid. After that, 30 mg/kg methyl prednisolone per every 12 hours was injected in the non-sacrificed rabbits of Group II and Group III. Nonenhanced Chest CT scans were performed prior to and 30 minutes, 4 hours, 24 hours, 48 hours, and 72 hours after the intravenous injection of oleic acid or methyl prednisolone. We randomly sacrificed one rabbit of groups I, II and III 30 minutes, 4 hours, 24 hours, 48 hours and 72 hours after CT scanning. The distribution, extent, and pattern of the lesions on the CT scan were analyzed. The analyzed pattern of the lesions was ground glass attenuation, consolidation and interstitial thickening. Pathologic correlation was then done. RESULTS: The main CT findings of Group I were peripheral, wedge shaped, ill-defined ground glass attenuations and/or consolidations. The pathologic findings of Group I were interstitial or intraalveolar edema, intraalveolar hemorrhage and coagulation necrosis. Diffuse ground glass opacities with interstitial thickening were noted in 20% (n=2/10) of Group I and in 60% (n=9/15) of Group II at the 30 minute CT; however, there was no statistical difference between the two groups (p=0.09). Consolidations with air bronchogram were noted in 22.2% (2/9) of Group I and in 38.5% (5/13) of Group II at the 4 hour CT. The main pathologic findings of consolidations were intraalveolar hemorrhage and coagulation necrosis. There was no statistical difference in the extent of the lesions between Group I and Group II (p=0.20, 0.14, 0.59 and 0.46 at 4, 24, 48 and 72 hours, respectively). The CT findings of Group IIa and Group IIb were not significantly difference. The CT findings of Group III were normal in all 5 rabbits. CONCLUSION: Because there was no significant difference for the extent of lung injury induced by oleic acid between the group treated with high dose methyl prednisolone and non-treated group on CT scans, high dose steroid therapy for acute respiratory distress syndrome and pulmonary fat embolism may not be effective in the acute stage.

1024 Matrix Image Reconstruction: Usefulness in High Resolution chest CT

PURPOSE: We tried to evaluate whether high resolution chest CT with a 1,024 matrix has a significant advantage in image quality compared to a 512 matrix. MATERIALS AND METHODS: Each set of 512 and 1024 matrix high resolution chest CT scans with both 0.625 mm and 1.25 mm slice thickness were obtained from 26 patients. Seventy locations that contained twenty-four low density lesions without sharp boundary such as emphysema, and forty-six sharp linear densities such as linear fibrosis were selected; these were randomly displayed on a five mega pixel LCD monitor. All the images were masked for information concerning the matrix size and slice thickness. Two chest radiologists scored the image quality of each arrowed lesion as follows: (1) undistinguishable, (2) poorly distinguishable, (3) fairly distinguishable, (4) well visible and (5) excellently visible. The scores were compared from the the aspects of matrix size, slice thickness and the different observers by using ANOVA tests. RESULTS: The average and standard deviation of image quality were 3.09 (+/-.92) for the 0.625 mmx512 matrix, 3.16 (+/-.84) for the 0.625 mmx1024 matrix, 2.49 (+/-1.02) for the 1.25 mmx512 matrix, and 2.35 (+/-1.02) for the 1.25 mmx1024 matrix, respectively. The image quality on both matrices of the high resolution chest CT scans with a 0.625 mm slice thickness was significantly better than that on the 1.25 mm slice thickness (p < 0.001). However, the image quality on the 1024 matrix high resolution chest CT scans was not significantly different from that on the 512 matrix high resolution chest CT scans (p = 0.678). The interobserver variation between the two observers was not significant (p = 0.691). CONCLUSION: We think that 1024 matrix image reconstruction for high resolution chest CT may not be clinically useful.

Usefulness of CT Fluoroscopy-guided Percutaneous Needle Biopsy in the Presence of Pneumothorax During Biopsy

PURPOSE: When pneumothorax occurs during a percutaneous needle biopsy, the radiologist usually stops the biopsy. We evaluated the usefulness of computed tomographic (CT) fluoroscopy-guided percutaneous needle biopsy in the presence of pneumothorax during biopsy. MATERIALS AND METHODS: We performed 288 CT fluoroscopy guided percutaneous needle biopsies to diagnose the pulmonary nodules. Twenty two of these patients had pneumothorax that occurred during the biopsy without obtaining an adequate specimen. After pneumothoax occurred, we performed immediate CT fluoroscopy guided percutaneous needle biopsies using an 18-gauge cutting needle. We evaluated the success rate of the biopsies and also whether or not the pneumothorax progressed. We classified these patients into two groups according to whether the pneumothorax progressed (Group 2) or not (Group 1) by measuring the longest distance between the parietal pleura and the visceral pleura both in the early and late pneumothorax. Additionally, we analyzed the relationship between the progression of pneumothorax after biopsy and 1) the depth of the pulmonary nodule; 2) the number of biopsies; 3) the presence or absence of emphysema at the biopsy site; and 4) the size of the pulmonary nodule. RESULTS: Biopsy was successful in 19 of 22 nodules (86.3%). Of the 19 nodules, 12 (63.2%) were malignant and 7 (36.8%) were benign. Twelve patients (54.5%) were classified as group 1 and 10 patients (45.4%) as group 2. The distance between the lung lesion and pleura showed a statistically significant difference between these two groups: 1 cm in distance for group 1 (30%) and group 2 (70%), p 0.05). CONCLUSION: When early pneumothorax occurs during a biopsy, CT fluoroscopy guided percutaneous needle biopsy is an effective and safe procedure. Aggravation of pneumothorax after biopsy is affected by the depth of the pulmonary nodule.