Application of I-123 HIPDM as a lung imaging agent

N,N,N-Trimethyl-N-(2-Hydroxyl-3-Methyl-5-¹²³I Iodobenzyl)-1,3-Propanediamine · Hcl (¹²³I-HIPDM) has been used for diagnosis of patients with strokes and dementias. Since this radiopharmaceutical is also accumulated in the lung, we routinely performed a lung image or images immediately prior to cerebral planar and SPECT images after a 3–5 mCi ¹²³I-HIPDM injection. During the past 14 months, we obtained 78 (age from 41 to 92 years, average 66.7±8.9 years; 64 males, 14 females) suspected stroke or dementia patients' lung images. All lung images were correlated to chest X-ray (CXR) or CT and other clinical data. Sixty five of 78 patients had normal lungs showing homogeneous distribution of activity throughout the lungs which correlated well to normal CXR and/or CT studies. Abnormal scintigraphic patterns of the 13 patients included lung defect (5 bronchogenic carcinoma with or without atelectasis) and decreased uptake in apices (8 chronic obstructive pulmonary disease). The findings of pulmonary intrathoracic pathologies on lung images with ¹²³I-HIPDM suggests further evaluation of the agent for detection of localized pulmonary diseases and pulmonary physiological studies relating to amine metabolism.This investigation was supported in part by Biomedical Research Support Grant no. RR05374 from the Biomedical Research Support Branch, Division of Research Facilities and Resources, NIH     

SPECT perfusion imaging with 123I-HIPDM in a patient with pulmonary embolism

The use of 123I-N,N,N'trimethyl-N'-2-hydroxy-3-methyl-5-iodobenzyl-1,3-propanediami ne (123I-HIPDM) as a lung perfusion tracer in a patient with pulmonary embolism is shown. 123I-HIPDM is compared with 99mTc-labeled human albumin microspheres (HAM) using both planar and tomographic (SPECT) imaging. Pulmonary segmental defects are shown by 123I-HIPDM as well as by HAM, with a slightly better definition of perfused areas. Tomograms better show segmental shape of perfusion defects. 123I-HIPDM may be proposed as lung perfusion tracer for both clinical and experimental purposes.     

Pulmonary infections in the late period after allogeneic bone marrow transplantation: chest radiography versus computed tomography

PURPOSE: To analyze the capabilities of chest roentgenogram (CXR) and computed tomography (CT) in the evaluation of pulmonary infectious disease in the late period (>100 days) after allogeneic bone marrow transplantation (BMT). METHODS: Ninety-four matched CXR and CT examinations were performed for clinical suspicion of infectious lung disease. The time gap between CXR and CT was 48 h at maximum. The image pairs were correlated with the patients' clinical course and with the results of diagnostic bronchoalveolar lavage (BAL). An unremarkable clinical course over the subsequent seven days after imaging and/or negative microbiological culture served as the basis for excluding infectious lung disease. Positive microbiological culture and/or improvement of symptoms after antibiotic therapy were considered as evidence of infectious disease. RESULTS: The correlation with the clinical course and/or BAL revealed a significantly higher sensitivity, negative predictive value, and accuracy for CT than for CXR (89% versus 58%, P < 0.0001; 78% versus 47%, P < 0.0001; 90% versus 68%, P < 0.0001, respectively). CT was significantly more diagnostic in BAL verified fungal and bacterial infections (P < 0.05). CONCLUSION: CT is significantly superior to CXR in the evaluation of infectious pulmonary disease in the late phase after BMT. Therefore, an unremarkable CXR should be followed by a CT scan to reliably detect or to accurately exclude early pulmonary infection in these patients.     

Pulmonary imaging of pandemic influenza H1N1 infection: relationship between clinical presentation and disease burden on chest radiography and CT

The potential for pulmonary involvement among patients presenting with novel swine-origin influenza A (H1N1) is high. To investigate the utility of chest imaging in this setting, we correlated clinical presentation with chest radiographic and CT findings in patients with proven H1N1 cases. Subjects included all patients presenting with laboratory-confirmed H1N1 between 1 May and 10 September 2009 to one of three urban hospitals. Clinical information was gathered retrospectively, including symptoms, possible risk factors, treatment and hospital survival. Imaging studies were re-read for study purposes, and CXR findings compared with CT scans when available. During the study period, 157 patients presented with subsequently proven H1N1 infection. Hospital admission was necessary for 94 (60%) patients, 16 (10%) were admitted to intensive care and 6 (4%) died. An initial CXR, carried out for 123 (78%) patients, was abnormal in only 40 (33%) cases. Factors associated with increased likelihood for radiographic lung abnormalities were dyspnoea (p<0.001), hypoxaemia (p<0.001) and diabetes mellitus (p = 0.023). Chest CT was performed in 21 patients, and 19 (90%) showed consolidation, ground-glass opacity, nodules or a combination of these findings. 4 of 21 patients had negative CXR and positive CT. Compared with CT, plain CXR was less sensitive in detecting H1N1 pulmonary disease among immunocompromised hosts than in other patients (p = 0.0072). A normal CXR is common among patients presenting to the hospital for H1N1-related symptoms without evidence of respiratory difficulties. The CXR may significantly underestimate lung involvement in the setting of immunosuppression.In late March 2009, an outbreak of respiratory illness caused by novel swine-origin influenza A virus (H1N1) was identified in Mexico [1]. In June that year, the World Health Organization (WHO) declared a global pandemic [2]. Since then the virus has spread worldwide and by 8 November 2009 more than 206 countries had reported laboratory-confirmed cases of H1N1 to the WHO, with more than 6250 related deaths [2, 3].Risk factors and clinical manifestations associated with H1N1 have been previously reported [4–9]. Significantly less attention has been given to the imaging findings of H1N1 that may serve as early indicators of the presence and impending severity of disease. Early recognition of radiological patterns may have an impact in timely management of critically ill patients with H1N1. We examined the chest X-ray (CXR) and CT findings in newly diagnosed cases of H1N1, and evaluated the relationship between risk factors, symptoms and extent of disease on the CXR compared with CT.     

Pulmonary function–morphologic relationships assessed by SPECT–CT fusion images

Pulmonary single photon emission computed tomography-computed tomography (SPECT-CT) fusion images provide objective and comprehensive assessment of pulmonary function and morphology relationships at cross-sectional lungs. This article reviewed the noteworthy findings of lung pathophysiology in wide-spectral lung disorders, which have been revealed on SPECT-CT fusion images in 8?years of experience. The fusion images confirmed the fundamental pathophysiologic appearance of lung low CT attenuation caused by airway obstruction-induced hypoxic vasoconstriction and that caused by direct pulmonary arterial obstruction as in acute pulmonary thromboembolism (PTE). The fusion images showed better correlation of lung perfusion distribution with lung CT attenuation changes at lung mosaic CT attenuation (MCA) compared with regional ventilation in the wide-spectral lung disorders, indicating that lung heterogeneous perfusion distribution may be a dominant mechanism of MCA on CT. SPECT-CT angiography fusion images revealed occasional dissociation between lung perfusion defects and intravascular clots in acute PTE, indicating the importance of assessment of actual effect of intravascular colts on peripheral lung perfusion. Perfusion SPECT-CT fusion images revealed the characteristic and preferential location of pulmonary infarction in acute PTE. The fusion images showed occasional unexpected perfusion defects in normal lung areas on CT in chronic obstructive pulmonary diseases and interstitial lung diseases, indicating the ability of perfusion SPECT superior to CT for detection of mild lesions in these disorders. The fusion images showed frequent "steal phenomenon"-induced perfusion defects extending to the surrounding normal lung of arteriovenous fistulas and those at normal lungs on CT in hepatopulmonary syndrome. Comprehensive assessment of lung function-CT morphology on fusion images will lead to more profound understanding of lung pathophysiology in wide-spectral lung disorders.     

双源CT双能量肺灌注成像对肺栓塞的初步研究

目的 探讨双源CT双能量扫描肺灌注成像的临床诊断价值.方法 选择临床怀疑肺动脉栓塞30例患者行双源CT双能量扫描,生成140、80 kV和融合系数为0.3的3组数据.根据融合数据的CT肺动脉造影(CTPA)图像将患者分为肺栓塞组和正常组.采用双能量评估软件将薄层重建数据进行灌注成像分析,将双肺野分为上、中、下3部分,正常组受试者肺组织灌注定量的双侧比较行配对t检验,2组间肺组织灌注量比较行独立样本t检验,并对融合图像行MinIP,评估肺组织通气情况.结果 正常组(16例)肺灌注均匀,无明显灌注缺损及减弱,灌注定量分析显示左、右全肺的灌注量分别为(27±7)、(28±8)HU,两侧比较差异无统计学意义(t=-1.73,P＞0.05);左肺上、中、下部的灌注量分别为(23±6)、(24±6)、(28±8)HU,右肺上、中、下部灌注量分别为(26±8)、(27±8)、(28±9)HU,两侧分别比较差异均无统计学意义(t值分别为-1.91、-1.96、-1.73,P值均＞0.05).肺栓塞组(14例)CTPA图像显示肺动脉干、段及亚段充盈缺损,肺灌注成像表现为栓塞血管所支配肺野区域的灌注缺损或缺失,灌注定量分析显示全肺及中、下肺的灌注量分别为(22±5)、(22±8)、(21±8)HU,与正常组分别比较差异均有统计学意义(t值分别为-2.10、-2.32、-2.63,P值均＜0.05＝.MinIP显示通气异常区与灌注异常区具有良好的一致性.结论 双源CT双能量扫描可用于肺栓塞的诊断,有利于肺栓塞的早期发现和精确解剖定位.

Abstract：

Objective To explore the diagnostic values of dual energy lung perfusion in the diagnosis of pulmonary embolism by using dual-source CT (DSCT). Methods Thirty patients with clinically suspected pulmonary embolism underwent dual-energy scanning with dual-source CT. The scanned data were integrated into three groups including 140, 80 kV and coefficient of 0.3. According to the CT pulmonary angiography (CTPA) of the fusion data, the patients were divided into pulmonary embolism group and normal group. The thin-slice reconstruction of data was analyzed using dual-energy perfusion imaging analysis software. The lung field was divided into upper, middle and lower part to make quantitative analysis of lung tissue perfusion. Paired t-tests were used in the normal patients to compare bilateral lungs, and independent samples t-tests were applied to compare the embolism group and normal group, while minimum intensity projection images (MinIP) were utilized in the assessment of lung ventilation. Results Dual energy CT showed symmetrical homogeneous perfusion in 16 normal cases, without significant perfusion defects. Quantitative analysis showed that left and right lung perfusion were (27 ± 7) and (28 ± 8 ) HU respectively, and no significant difference was found between the two sides ( t=-1.73, P ＞0.05 ).Perfusion of the left upper, middle and lower lung was ( 23 ± 6), (24 ± 6), and (28 ± 8) HU respectively, while the perfusion of right upper, middle and lower lung was (26 ±8), (27 ±8), and (28 ±9) HU respectively, showing no statistical significant difference between the two sides (t=-1.91, -1.96,-1.73 ,P＞0.05 ). Angiography of pulmonary embolism group(14 cases)showed filling defects in the pulmonary trunk, segments and sub-segments. Pulmonary perfusion imaging showed low perfusion or defectsin lung field that dominated by embolic vessels. Quantitative analysis showed that the perfusion of the whole lung and the middle and lower lung were (22 ±5), (22 ±8), and (21 ±8) HU in the embolism group,which were significantly different from the normal group (t=-2. 10, -2.32, -2.63, P＜0.05).Minimum intensity projection images showed a good consistency of abnormal ventilation zone area and perfusion abnormalities. Conclusions Pulmonary perfusion status, especially pulmonary embolism, can be analyzed by dual energy CT scanning. It helps to early discover and precisely locate the embolism.     

Influenza A virus: radiological and clinical findings of patients hospitalised for pandemic H1N1 influenza

Purpose

This paper describes the radiological and clinical findings identified in a group of patients with H1N1 influenza.

Materials and methods

Between May and mid-November 2009, 3,649 patients with suspected H1N1 influenza presented to our hospital. Our study population comprised 167 (91 male, 76 female patients, age range 11 months to 82 years; mean age 29 years) out of 1,896 patients with throat swab positive for H1N1 and clinical and laboratory findings indicative of viral influenza. All 167 patients were studied by chest X-ray (CXR), and 20 patients with positive CXR and worsening clinical condition also underwent computed tomography (CT). The following findings were evaluated on both modalities: interstitial reticulation (IR), nodules (N), ground-glass opacities (GGO), consolidations (CONS), bacterial superinfection and pulmonary complications.

Results

Ninety of 167 patients had positive CXR results. Abnormalities identified on CXR, variously combined and distributed, were as follows: 53 IR, 5 N, 13 GGO, 50 CONS; the predominant combination was represented by six GGO with CONS. Of the 20 CXR-positive cases also studied by CT, 17 showed pathological findings. The abnormalities identified on CT, variously combined and distributed, were as follows: 14 IR, 2 N, 5 GGO; the predominant combination was 10 GGO with CONS. Despite the differences between the two modalities, the principle radiological findings of bacterial superinfection were tree-in-bud pattern, consolidation with air bronchogram, and pleural and pericardial effusion. Fifteen of the 20 patients studied by both CXR and chest CT showed respiratory complications with bilateral and diffuse CONS on CXR and CT. Six of 15 died: 4/6 of acute respiratory distress syndrome and 2/6 of multiple organ failure.

Conclusions

Our study describes the radiological and clinical characteristics of a large population of patients affected by H1N1 influenza. CXR and chest CT identified the site and extent of the pulmonary lesions and documented signs of bacterial superinfection and pulmonary complications.     

Comprehensive assessment of lung CT attenuation alteration at perfusion defects of acute pulmonary thromboembolism with breath-hold SPECT-CT fusion images

Regional computed tomography attenuation (CTA) alteration at perfusion defects in acute pulmonary thromboembolism (PTE) was comprehensively assessed using deep-inspiratory breath-hold SPECT-CT fusion images. Subjects were 14 acute and 9 chronic PTE patients and 13 control subjects. Regional perfusion, CTA, and intravascular clots were correlated on deep-inspiratory breath-hold SPECT-unenhanced/angiographic CT fusion images. Fusion images visualized hypo-CTA in 57% of the acute PTE patients, which preferentially occurred at extensively and severely decreased perfusion areas caused by central clots. CTA at 35 defects of acute PTE was significantly decreased compared with that of normal lungs (P<0.001), but the degree was less compared with chronic PTE (P<0.0001). Fusion images also revealed variable relationships of clots and regional perfusion/CTA in the distal lungs of each central clot. Fusion images provide important information about the actual effects of intravascular clots on peripheral perfusion/CTA and indicate that lung CTA can be decreased at perfusion defects in acute PTE.     

Evaluation of lung injury after three-dimensional conformal stereotactic radiation therapy for solitary lung tumors: CT appearance

PURPOSE: To evaluate the computed tomographic (CT) appearance of tumors and lung injury in patients who have undergone stereotactic radiation therapy (SRT) for solitary lung tumors. MATERIALS AND METHODS: Twenty-seven patients with primary lung cancer and four with metastatic lung cancer who underwent SRT for solitary lung tumors were enrolled for evaluation. SRT was delivered by using a three-dimensional conformal technique with a stereotactic body frame. A total dose of 48 Gy was administered in four fractions during a period of 2 weeks. After SRT, follow-up CT images were obtained every 2-3 months. Radiation-induced pulmonary injuries were classified into four patterns on CT images. The minimal lung dose to areas demonstrating pulmonary injury at CT was evaluated, and the correlation between the dose and the percentage volume of the whole lung irradiated by more than 20 Gy in total (V20) was assessed by using Spearman rank correlation. RESULTS: Tumor shrinkage continued for 2-15 months after SRT. Asymptomatic changes in the irradiated lung were noted at CT in all patients within 2-6 months (median, 4 months) after SRT. As the pattern at pulmonary CT changed, patchy consolidation was more predominantly seen as an acute change than were slight homogeneous increase in opacity, discrete consolidation, or solid consolidation; solid consolidation was the more predominantly seen late change. The minimal lung dose to the area demonstrating pulmonary injury in each patient ranged between 16 and 36 Gy (median, 24 Gy). The dose was significantly (P <.001) inversely correlated with the V20 in each patient. CONCLUSION: The reaction to SRT of the lungs seems similar to the reaction to conventional radiation therapy.     

Quantitation of emphysema with three-dimensional CT densitometry: comparison with two-dimensional analysis, visual emphysema scores, and pulmonary function test results

PURPOSE: To compare lung densitometric measurements that use a three-dimensional (3D) reconstruction of the lungs with those obtained from analysis of two-dimensional (2D) computed tomographic (CT) images, visual emphysema scores, and data from pulmonary function tests. MATERIALS AND METHODS: Thoracic helical CT scans were obtained in 60 adult patients (35 with no visual evidence of emphysema and 25 with emphysema). The lungs were reconstructed as a 3D model on a commercial workstation, with a threshold of -600 HU. By analysis of histograms, the proportions of lung volumes with attenuation values below -950, -910, and -900 HU were measured, in addition to mean lung attenuation. These values were compared with lung densitometric results obtained from 2D CT images, visual emphysema scores, and data from pulmonary function tests. RESULTS: Quantitation of emphysema with 3D reconstruction was efficient and accurate. Correlation was good among densitometric quantitation with 3D analysis, that obtained with 2D analysis (r = 0.98-0.99), and visual scoring (r = 0.74-0.82). Correlation was reasonable between 3D densitometric quantitation and the diffusing capacity of the lungs for carbon monoxide (DLCO) (r = -0.57 to -0.64), total lung capacity (r = 0.62-0.71), forced expiratory volume in 1 second (FEV1) (r = -0.57 to -0.60), and the ratio of FEV1 to forced vital capacity (FVC) (r = -0.75 to -0.82). The visual CT quantitation of emphysema correlated best with DLCO (r = -0.82) and FEV1/FVC (r = -0.89). CONCLUSION: Lung densitometry with 3D reconstruction of helical CT data is a fast and accurate method for quantifying emphysema.     

Pulmonary imaging using dual-energy CT, a role of the assessment of iodine and air distribution

Aim

The aim of the study is to present the feasibility of using dual-energy CT and the evaluation of iodine and air distribution in differentiation of pathological conditions.

Material and method

We used the data of 50 CT examinations performed due to suspected pulmonary embolism with any pathological finding except consolidation of the parenchyma. The patients underwent CT angiography of the pulmonary arteries on a dual-source CT (DSCT), with the two tubes independently operated at 140 and 80 kV. By exploiting the dual-energy information, iodine distribution maps were obtained in addition to the conventional CT images which served as a marker of pulmonary perfusion. Minimum intensity projections (MinIP) were used as a marker of air content.

Results

By comparing the iodine distribution maps and MinIP images, it was possible to differentiate between the following templates of lung parenchyma: A - normal iodine and air distribution; B - iodine content deficit with minimal or with no redistribution of air; C - reduced iodine content and increased content of air; D - deficit of iodine content and increased content of air; E - increased iodine content and normal content of air; F - increased iodine content and reduced content of air; G - reduced perfusion and reduced content of air. The type A (five cases) was typical for the pulmonary embolism with preserved normal conditions of perfusion and ventilation. Type B (18 cases) occurred in pulmonary embolism; type C was found in case of inflammation of small respiratory airways (five cases); emphysema was typical for type D (nine cases); increased perfusion was observed in the parenchyma preserved from emphysema or preserved from embolism in cases of emphysema or pulmonary embolism; type F occurred in pulmonary interstitial edema (four cases) both with pulmonary infection; finally type G was found in interstitial lung diseases (five cases).

Conclusion

Imaging of the pulmonary circulation by means of dual-energy CT opens the potential to study pathological changes of circulatory and pulmonary perfusion impairments, our presented work signs the important relations between iodine and air distribution which have to be thought in the interpretation of dual-energy perfusion imaging of the lungs.     

CT evaluation of pulmonary metastases: usefulness in comparison with chest radiography

The purpose of this study was to evaluate the usefulness of follow-up CT for screening pulmonary metastases, in comparison with chest radiography (CXR). Two hundred sixty CT examinations performed on 200 patients with known malignancy formed the basis of the study. One hundred sixty-five metastatic nodules were detected from 52 CT examinations in 36 patients. The detectability of these nodules on CXR was relatively good, but it was better on CT, which detected more nodules of smaller size, those overlying the mediastinum or hilus, and those showing ground-glass attenuation. As for the relationship between treatment and pulmonary metastases, pulmonary metastases treated surgically were detected on CXR in all patients. Pulmonary metastases showed a tendency to recur within one year after the initial treatment. The author concluded that routine CT to screen occult lung metastases in every patient with malignancy is not cost-effective. However, CT may be added at the start of the initial treatment and within one year thereafter, particularly for patients with lung cancer.     

CT-pathologic correlation in small peripheral lung cancers

To evaluate the morphology of small peripheral lung cancers, we studied thin-section CT images of 18 small peripheral lung cancers (14 adenocarcinomas, two squamous-cell carcinomas, one large-cell carcinoma, and one carcinoid) in 17 patients. After surgical resection, specimens were sliced transversely, and the gross morphology and histology were correlated with the appearance of the lesion on preoperative thin-section CT images. CT images showed fine speculations in 78%, a notch in 83%, pleural retraction in 78%, and convergence of peripheral vessels in 83% of the 18 lung cancers. Furthermore, in cases of papillary adenocarcinoma, the lesions had heterogeneous densities (78%) and small cavitations (67%). CT showed a peripheral fluffy zone in most of the well- or moderately differentiated papillary adenocarcinomas. This correlated well with tumor cells lining the alveolar walls, observed in pathologic studies. Comparison of thin-section CT images with pathologic data suggests that the demonstration of the lung-tumor interface and the tumor's internal texture, while not specific for malignant lesions, can make the CT diagnosis of small peripheral lung cancers more accurate.     

Assessment of anatomic relation between pulmonary perfusion and morphology in pulmonary emphysema with breath-hold SPECT-CT fusion images

OBJECTIVE: Anatomic relation between pulmonary perfusion and morphology in pulmonary emphysema was assessed on deep-inspiratory breath-hold (DIBrH) perfusion single-photon emission computed tomography (SPECT)-CT fusion images. METHODS: Subjects were 38 patients with pulmonary emphysema and 11 non-smoker controls, who successfully underwent DIBrH and non-BrH perfusion SPECT using a dual-headed SPECT system during the period between January 2004 and June 2006. DIBrH SPECT was three-dimensionally co-registered with DIBrH CT to comprehend the relationship between lung perfusion defects and CT low attenuation areas (LAA). By comparing the appearance of lung perfusion on DIBrH with non-BrH SPECT, the correlation with the rate constant for the alveolar-capillary transfer of carbon monoxide (DLCO/VA) was compared between perfusion abnormalities on these SPECTs and LAA on CT. RESULTS: DIBrH SPECT provided fairly uniform perfusion in controls, but significantly enhanced perfusion heterogeneity when compared with non-BrH SPECT in pulmonary emphysema patients (P < 0.001). The reliable DIBrH SPECT-CT fusion images confirmed more extended perfusion defects than LAA on CT in majority (73%) of patients. Perfusion abnormalities on DIBrH SPECT were more closely correlated with DLCO/VA than LAA on CT (P < 0.05). CONCLUSIONS: DIBrH SPECT identifies affected lungs with perfusion abnormality better than does non-BrH SPECT in pulmonary emphysema. DIBrH SPECT-CT fusion images are useful for more accurately localizing affected lungs than morphologic CT alone in this disease.     

Centrilobular emphysema: CT-pathologic correlation

Over a 5-year period, 25 patients who had undergone chest computed tomography (CT) died and were autopsied. Their lungs were fixed in the inflated state and were assessed for the presence and severity of centrilobular emphysema (CLE). Three radiologists independently evaluated the CT scans for nonperipheral low-attenuation areas, peripheral low-attenuation areas, pulmonary vascular pruning, pulmonary vascular distortion, and pulmonary density gradient. The CT criterion that best correlated with the presence and severity of CLE was the nonperipheral low-attenuation area. With this CT criterion, lung destruction was correctly identified in 13 of 15 cases. The absence of this criterion resulted in correct identification of eight of ten normal lungs. These preliminary data suggest that CLE can be reliably identified and quantified with current CT scanners.     

Chronic pulmonary thromboembolism. Air trapping on computed tomography and correlation with pulmonary function tests

OBJECTIVE: We evaluated lung attenuation on inspiratory/expiratory computed tomography (CT) and spiral CT angiography (CTA) from patients with chronic pulmonary embolism and correlated the CT findings with pulmonary function test (PFT) results. METHODS: We retrospectively reviewed 9 patients with chronic embolism (mean age, 62.3 years; 5 women and 4 men). Paired inspiratory, expiratory CT and matching CTA images were reviewed, and lung attenuation was evaluated in each segment. Lower attenuation on inspiratory images and air trapping on expiratory images were subjectively assessed and correlated with PFT results. The relationship between the presence of clot and lung attenuation was evaluated. Nine age-matched normal subjects served as controls. RESULTS: Lower attenuation with mosaic perfusion and air trapping were identified in 6 and 9 patients, respectively (mean scores, 8.1 and 11.3, respectively). Air trapping was identified in 19 (42.2%) of 45 segments with lower attenuation on inspiratory images, but was also noted in 31 segments with normal inspiratory attenuation. Air trapping was associated with the presence of proximal arterial stenosis (P<0.01), and the area showed less contrast enhancement than the adjacent lung (P<0.05). Extent of air trapping correlated inversely with PFT parameters of peripheral airway obstruction such as maximum mid-expiratory flow rate (r=-0.86, P=0.003). On the other hand, extent of mosaic perfusion did not correlate with PFT. CONCLUSIONS: Air trapping is commonly seen in chronic embolism and is found in areas of relative hypoperfusion. The extent of air trapping correlates with parameters of peripheral airway obstruction.     

胸部计算机放射摄影术与传统胸片在肺癌诊断中的对比研究

目的　研究胸部计算机放射摄影 (CR)术在肺癌诊断中的价值。方法　经手术病理证实的肺癌 5 6例 ,其中中央型肺癌3 4例 ,周围型肺癌 2 2例。 4种胸部CR图像 :平片CR( plainCR)、宽幅高频响应CR(wideCR )、高频响应CR(HE -CR )、低频响应CR (LE -CR) ;2种胸部CR体层摄影 :平片CR体层摄影 (plainCR -TOMO)、高频CR体层摄影 (HE -CR -TOMO) ;分别与传统胸片及传统体层摄影在正常结构及异常阴影的显示进行对比。结果　①正常结构的观测 :除wideCR、HE -CR对右下肺动脉的显示不如常规X线 (CXR)外 ,其余项目的各种CR图像均不同程度地优于CXR。体层摄影 :所有观测项目 ,CR体层摄影均优于CXR体层摄影。②异常阴影的观测 :中央型肺癌 ,PlainCR与LE -CR对所有观测项目的显示均优于CXR ;wideCR对受累支气管的显示优于CXR ,而对肿块内部密度分布及周围血管影的显示与CXR相同 ,对肺门肿块边缘的显示不如CXR。HE -CR所有观测项目均不如CXR。周围型肺癌 ,plainCR、LE -CR对肿块边缘特征及空洞的显示优于CXR ,而对密度分布的显示与CXR相同 ;wideCR对肿块边缘特征的显示不如CXR ;HE -CR对所有观测项目的显示均不如CXR。体层摄影 :PlainCR -TOMO及HE-CR -TOMO均优于CXR体层摄影。结论　通过对胸部正常结构及异常阴影的CR与C     

Automated measurement of single and total lung volume from CT.

PURPOSE: The goal of this work was to develop an automated method for calculating single (SLV) and total (TLV) lung volumes from CT images. METHOD: Patients underwent volumetric CT scanning through the entire chest in a single breath-hold, as well as pulmonary function tests. An automated, knowledge-based system was developed to segment the lungs in the CT images. Image-processing routines were used to extract sets of voxels from the image data that were identified by matching them to anatomical objects defined in a model. SLV and TLV were calculated by summing included voxels. RESULTS: For 43 patients analyzed, TLV from CT and total lung capacity from body plethysmography were strongly correlated (r = 0.90). On average, the CT-derived volume of the left lung accounted for 47.2% of the total. CONCLUSION: A knowledge-based approach to segmentation of the lungs in CT can be used to automatically estimate SLV and TLV.     

Fluorodeoxyglucose positron emission tomography pattern of pulmonary lymphangitic carcinomatosis

OBJECTIVE: The purpose of this study was to evaluate the F-fluorodeoxyglucose (FDG) positron emission tomography (PET) uptake in pulmonary lymphangitic carcinomatosis identified on computed tomography (CT) in patients with lung cancer. METHODS: This was a retrospective analysis of F-FDG PET images in 7 patients (4 male and 3 female, mean age: 56.6 +/- 6.6 years) with lung cancer with a CT-based diagnosis of lymphangitic carcinomatosis. The F-FDG PET scans in a group of 7 patients (4 male and 3 female, mean age: 42.1 +/- 5.66 years) with normal chest CT scans served as a control group. Mean standardized uptake values (SUVs) were calculated based on average tumor uptake, initial injected activity, and body weight. RESULTS: The intensity of F-FDG uptake in diseased lung is significantly greater than in corresponding normal contralateral lung or in the lungs of normal controls (P = 0.003). The ratio of the SUV of lung with lymphangitic carcinomatosis to corresponding contralateral normal lung was significantly increased (P = 0.006), and the ratio of the SUV of mediastinal blood pool to lung with lymphangitic carcinomatosis was significantly decreased (P = 0.0002). CONCLUSION: There is diffuse increased FDG uptake in the lung corresponding to the CT pattern of lymphangitic carcinomatosis.     

Pneumothorax post CT-guided lung biopsy: a comparison between detection on chest radiographs and CT

Pneumothorax is reported to be a more common complication of lung biopsy performed under computed tomography (CT) than under fluoroscopic guidance. This may simply reflect the greater sensitivity of CT over chest radiographs (CXRs) in the detection of small pneumothoraces. This study aimed to determine the incidence of pneumothorax detected by CXR and by CT after CT-guided biopsy of non-pleurally based pulmonary masses, and to compare these incidences with previous reports in the literature of pneumothorax incidence post fluoroscopic biopsy. 88 consecutive CT-guided lung biopsies of masses not abutting the pleural surface were included. Immediate post-biopsy CT images, and 1 and 4 h CXRs were assessed independently by two observers for the presence and size of pneumothorax. 72 biopsies were fine needle aspirations (FNAs) performed with 22 G spinal needles only, seven were cutting needle biopsies (CNBs) performed with 18 G cutting needles only, and nine were both. 37 patients (42%) developed a pneumothorax. 35 were detected on CT (40%) and 22 on CXR (25%). None required tube drainage. Of the patients in whom CT demonstrated a pneumothorax, the average depth of this was significantly greater for those in whom CXR also detected a pneumothorax compared with those in whom CXR was negative (7.3 mm versus 3.4 mm, p < 0.05). The incidence of pneumothorax detected on CXR post CT-guided biopsy is similar to the reported incidence post fluoroscopic biopsy.