Evaluation of air trapping at CT: comparison of continuous-versus suspended-expiration CT techniques.

PURPOSE: To compare thin-section computed tomographic (CT) scans obtained during suspended end expiration with helical CT scans obtained during continuous expiration for the assessment of air trapping. MATERIALS AND METHODS: Forty-nine patients with an airway disease were examined with suspended-end-expiration CT after a 6-8-second expiratory maneuver, which was followed with continuous-expiration CT during a 10-second expiratory maneuver. The extent of expiratory air-trapping areas was calculated by two observers by using a semiquantitative grid score. The relative decrease in attenuation in the areas of air trapping was evaluated with a visual continuous-scale score. RESULTS: Air trapping was noted in 36 and 35 patients with continuous-expiration CT and with suspended-end-inspiration CT, respectively. The extents of and relative attenuation decreases in air-trapping areas in patients with air-trapping areas on at least one expiratory CT scan increased significantly in scans obtained with continuous-expiration CT compared with those obtained with suspended-end-expiration CT, respectively, with mean extent scores of 0.24 +/- 0.20 (SD) and 0.18 +/- 0.20 (paired t test, P: =.001) respectively, and with mean relative contrast decrease scores of 0.35 +/- 0.23 and 0.27 +/- 0.23 (paired t test, P: =.007), respectively. CONCLUSION: When suspended-end-expiration CT images are ambiguous, complementary continuous-expiration CT can be used to improve the conspicuity and apparent extent of air trapping.

Contrast-enhanced helical CT for pulmonary embolism detection: inter- and intraobserver agreement among radiologists with variable experience.

OBJECTIVE: The objective of this study was to evaluate inter- and intraobserver agreement in the diagnosis of central pulmonary embolism using contrast-enhanced helical CT among observers with variable experience in the interpretation of pulmonary CT angiograms. MATERIALS AND METHODS: Helical CT angiograms of 60 patients clinically suspected of having pulmonary embolism were analyzed retrospectively and independently by two chest radiologists, one cardiovascular radiologist, and three general radiologists. The films were rated a second time by the chest radiologists to assess intraobserver variability. Findings for pulmonary embolism were categorized as positive, negative, or indeterminate at the main, lobar, and segmental pulmonary artery levels. RESULTS: The observers interpreted 19-21 CT angiograms as positive for pulmonary embolism (mean, 19.7) and one to six as indeterminate (mean, 3.2). Agreement occurred among all observers in 50 patients (83.3%), among five observers in six patients (10.0%), among four observers in three patients (5.0%), and among three observers in one patient (1.7%). Interobserver agreement was very good (kappa, .85) for the diagnosis of pulmonary embolism on a per-patient basis. Agreement on a per-artery basis for all arteries was moderate (66%; kappa, .56); for lobar arteries was good (83%; kappa, .75); and for segmental arteries was moderate (57%; kappa, .47). Mean intraobserver agreement on a per-patient basis was very good (93%; kappa, .87). CONCLUSION: Inter- and intraobserver agreement in the diagnosis of pulmonary embolism with helical CT is very good despite a wide variety of experience among radiologists.

Expiratory CT scans for chronic airway disease: correlation with pulmonary function test results.

OBJECTIVE: The purpose of our study was to correlate findings on expiratory CT scans with results of pulmonary function tests (PFTs) and to determine whether these techniques may be complementary in assessing airway obstruction. MATERIALS AND METHODS: Seventy-four patients with suspected chronic airway disease and 10 healthy nonsmokers underwent inspiratory and expiratory CT scans and PFTs. An air trapping score, corresponding to the ratio of the cross-sectional air trapping area versus the total cross-sectional lung area on expiratory CT, and a reduction score, representing the change in cross-sectional lung area at inspiration and expiration, were calculated using a quantitative grid. The two scores were then correlated with the results of the PFTs. RESULTS: Expiratory air trapping was seen in 18 (51%) of 35 patients with severe airway obstruction (forced expiratory volume in 1 sec [FEV1]:vital capacity < 80%) (group A), in 21 (72%) of 29 patients with predominantly small airways obstruction (abnormal flow-volume curve and FEV1:vital capacity > or = 80%) (group B1), and in four (40%) of 10 patients with normal PFT results (group B2). Expiratory air trapping was never seen in the 10 healthy subjects. Air trapping scores were 27%, 12%, and 8% for groups A, B1, and B2, respectively, with significant negative correlations with FEV1 (r = -.45), FEV1:vital capacity (r = -.31), and forced expiratory flow at 25% of vital capacity (r = -.57). Reduction scores were 18%, 30%, 35%, and 43%, for the groups A, B1, B2, and the healthy group, respectively, with significant correlations with all the PFT indexes (r = .35 to .66) except total lung capacity. CONCLUSION: Air trapping may permit detection of airway obstruction in patients with clinically suspected chronic airway disease even when PFTs are normal. Furthermore, expiratory CT allows one to calculate a reduction score for a cross-sectional lung area that appears to be better correlated with the degree of airway obstruction measured on PFTs.

Transient global amnesia after cerebral angiography. A case report.

We report on a case of transient global amnesia after cerebral angiography in which a nonionic contrast medium was used. The complication observed showed no evidence of any definite cause.

[Comparative evaluation of iopamidol 300 versus 370 during spiral x-ray computed tomographic studies of the thorax]. / Evaluation comparative du iopamidol 300 versus 370 au cours des explorations tomodensitométriques hélicoïdales du thorax.

PURPOSE: A retrospective study was performed to assess the role of iodine concentration on the opacification of different vascular compartments of the chest with a nonionic contrast agent (Iopamidol) during routine spiral CT examination. MATERIAL AND METHOD: 105 injected spiral CTs of the chest were studied. 50 examinations were done with Iopamidol 300 (iodine concentration 300 g/L) (I300). 55 examinations were done with Iopamidol 370 (iodine concentration 370 g/L) (I370). A constant 24- g total iodine dose was delivered with no difference in the injected iodine flow rates (respectively 0.6 and 0.55 g/s). Images were scored for opacification success, opacification quality and for artefacts in each vascular, of the chest. RESULTS: There was no statistically significant difference in opacification success or in opacification quality, in each chest vascular compartment between the group receiving I300 and the group receiving I370. Artefact frequencies on the lower part of superior vena cava were however different, 24% and 41.8% respectively. CONCLUSION: For a constant injected iodine flow rate, a moderate increase in iodine concentration, with decreased injection volume and flow rate, had little or no effect on opacification of the aorta and the pulmonary artery. The presence of artefacts on the lower part of the superior vena cava would suggest that the use of lower concentration contrast media would be advisable for specific vena cava examinations.

Abnormalities of the airways and lung parenchyma in asthmatics: CT observations in 50 patients and inter- and intraobserver variability.

The purpose of the study was to evaluate the CT abnormalities of airways and lung parenchyma in asthmatic patients and to assess inter- and intraobserver variability for these abnormalities. The CT scans of 50 asthmatic patients and 10 healthy volunteers were assessed independently by four independent chest radiologists who were masked with respect to the clinical information. Bronchiectasis involving mostly subsegmental and distal bronchi was noted in 28.5% of the asthmatic subjects and none of the non-asthmatics. Bronchial wall thickening, small centrilobular opacities and decreased lung attenuation were observed in 82%, 21% and 31% of asthmatic patients respectively, compared with 7%, 5% and 7% of healthy subjects. The intra- and inter-observer agreements for these four CT abnormalities were measured by the kappa statistic and ranged from 0.60 to 0.79 and from 0.40 to 0.64, respectively. It is concluded that asthmatic patients may exhibit bronchial wall thickening, bronchiectasis and morphological abnormalities suggestive of distal airways disease that can be assessed on CT scans with a clinically acceptable observer variability.