Quantification of thin-section CT lung attenuation in acute pulmonary embolism: correlations with arterial blood gas levels and CT angiography.

OBJECTIVE: The purposes of this study were to investigate the frequency histogram of lung attenuation on CT angiography (CTA) in patients with and without acute pulmonary embolism (PE) and to evaluate the relation of the frequency histogram of lung attenuation and hypoxemia. MATERIALS AND METHODS: Twenty-six patients with PE and 11 patients without PE who underwent CTA were evaluated with frequency histograms. We obtained quantitative parameters such as mean lung attenuation, median lung attenuation, SD, skewness, kurtosis, and the proportion of lung attenuation except for the median +/- 50 H (P +/- 50 H). Lung attenuation was also assessed visually and scored. The relationship between those histogram parameters, or visual score, and Pa(O2) was evaluated. CTA scores for evaluation of the degree of pulmonary artery obstruction were obtained, and the relation with Pa(O2) was assessed. RESULTS: No significant differences were found in mean lung attenuation and median lung attenuation between patients with and without PE. Meanwhile, SD, skewness, kurtosis, and P +/- 50 H were significantly different between patients with and without PE (p = 0.0003, 0.0071, 0.0047, and 0.0028, respectively) and significantly correlated with Pa(O2) (r = -0.770, 0.797, 0.786, -0.871, respectively). Significant differences were found in visual scores between patients with and without PE (p < 0.0001). There were significant but relatively low correlations between CTA score and arterial blood gas levels (r = -0.442, p = 0.03). CONCLUSION: In patients with acute PE, heterogeneity in lung attenuation is more prominent than in patients without PE.

Thin-section CT assessment of spontaneous pneumomediastinum in interstitial lung disease: correlation with serial changes in lung parenchymal abnormalities.

PURPOSE: The purpose of this study was to analyze thin-section computed tomography (CT) appearances of interstitial lung diseases before and at the time of detection of pneumomediastinum, and to evaluate the relationship between pneumomediastinum and parenchymal changes on thin-section CT. MATERIALS & METHODS: We reviewed CT images before and at the time of detection of pneumomediastinum in 13 patients with idiopathic pulmonary fibrosis (8 patients) and collagen vascular diseases (5 patient). The extent of the total area of reticular opacity, increased opacity (ground-glass opacity and consolidation), and honeycombing were scored, and these scores were compared before and at the time of detection of pneumomediastinum. We also divided patients into two groups according to therapy received. Patients in group 1 experienced pneumomediastinum after or during treatment with corticosteroids or immunosuppressive agents for acute or subacute exacerbation of interstitial lung disease. Patients in group 2 experienced pneumomediastinum without therapy. RESULTS: The mean score of all patients for honeycombing significantly increased at the time of detection of pneumomediastinum (P=0.003). In group 1, the extent of increasing opacity had been decreased significantly at the time of detection of pneumomediastinum (P=0.028). In group 2, the mean CT score of reticular opacity, increasing opacity, and honeycombing significantly increased at the time of detection of pneumomediastinum (P=0.028, 0.018, and 0.018, respectively). CONCLUSIONS: Spontaneous pneumomediastinum associated with interstitial lung disease appears to have a tendency to occur under conditions of altered of parenchymal interstitial lesions.

Peripheral solitary pulmonary nodule: CT findings in patients with pulmonary emphysema.

PURPOSE: To analyze retrospectively the computed tomographic (CT) features of peripheral noncalcified solitary pulmonary nodules in patients with and those without emphysema. MATERIALS AND METHODS: The authors' institutional review board required neither its approval nor patient informed consent for this retrospective study. The authors retrospectively reviewed 2-mm-thick CT images of 41 nodules (21 malignant, 20 benign) in 41 patients with emphysema (age range, 58-88 years; mean, 71.9 years) and 40 nodules (20 malignant, 20 benign) in 40 patients without emphysema (age range, 50-85 years; mean, 69.2 years). Two radiologists who were unaware of the diagnosis independently evaluated the shape and margin of the nodule, recorded the presence of ground-glass opacities and air bronchograms, and classified nodules into two diagnostic categories: malignant and benign. Final decisions were reached by consensus. For quantitative assessment of the nodules, the fractal dimensions of the nodule interfaces and circularity of the nodule shape were calculated with an image-processing program, and the percentage of the nodule surrounded by emphysema was obtained. Statistical comparisons were made with a chi(2) or Fisher exact test and the Mann-Whitney U test. RESULTS: In patients with emphysema, there were no significant differences in fractal dimension, circularity, or frequency of lobulation or spiculation between malignant and benign nodules. Of the 41 nodules in patients with emphysema, 26 (63%) were correctly diagnosed. Thirteen benign nodules (65%) were diagnosed as malignant in patients with emphysema. Of the 40 nodules in nonemphysematous lungs, 37 (93%) were correctly diagnosed. The mean percentage of emphysema around the nodule was greater for misdiagnosed nodules than for correctly diagnosed nodules (P = .003). CONCLUSION: Malignant and benign nodules associated with emphysema exhibited considerably more overlap in CT features than did nodules in nonemphysematous lungs.

Radiation-induced temporary hair loss as a radiation damage only occurring in patients who had the combination of MDCT and DSA.

As imaging technologies become increasingly advanced, it is possible to obtain detailed morphological information as well as functional imaging data. In some imaging technologies, the radiation dose increases with the ability to obtain better images or more detailed information. We encountered three cases of temporary bandage-shaped hair loss, which was caused by perfusion studies of the head by multi-detector row computed tomography (MDCT) for evaluation of cerebral blood flow in patients with vascular disorders. In all three patients with temporary hair loss, two angiographies of the head had been performed in the period of serial CT examinations. This suggested the possibility that radiation exposure from angiography performed in serial examinations, combined with the perfusion studies of the head with MDCT, played an important role in this temporary, bandage-shaped hair loss. Radiologists should be aware that a cumulative or multiplier effect of radiation exposure from multiple diagnostic techniques may result in hair loss and other types of radiation complications.

Serial change in airway lumen and wall thickness at thin-section CT in asymptomatic subjects.

PURPOSE: To retrospectively analyze serial changes in airway lumen and wall thickness (WT) at multi-detector row computed tomography (CT) in asymptomatic subjects. MATERIALS AND METHODS: Institutional review board did not require its approval or informed patient consent. Airway dimensions were analyzed in 52 patients (30 men and 22 women) without known cardiopulmonary disease. Contiguous 2-mm CT sections were obtained after reconstruction, extending from origin of right posterior basal segmental bronchi to posterior subsegmental bronchi. Following parameters were determined with semiautomatic image-processing program: luminal area (LA), total airway area (TA), short axis of lumen (LSD), and short axis of total airway (TSD). In airways in which adjacent vessel or branching of small bronchus abutted boundary of airway, extrapolated line was traced by one radiologist. Airway wall area (WA) was calculated as TA - LA, and WT was calculated as (TSD - LSD)/2. Relative WA (WA% = [WA/TA] . 100) and ratio of airway WT to total diameter (D) (WT/D = WT/TSD) were calculated. Linear regression analysis and Spearman rank correlation were used to evaluate relationship between airway parameters (LA, WA%, and WT/D ratio) and distance from origin of segmental bronchi. RESULTS: LA decreased as CT proceeded from hilum to periphery (r = -0.765, P < .001). In 308 (32.7%) of 943 bronchi, however, LA increased as CT proceeded from hilum to periphery. LA increased by 10% or more in 101 (10.7%) of 943 bronchi. Mean changes in WA% and WT/D ratio between two contiguous sections were 0.66 +/- 5.05 (standard deviation) and 0.003 +/- 0.024, respectively. WA% changed by more than 5% between two contiguous sections in 274 (29.0%) of 943 bronchi. WT/D ratio changed by more than 0.02 between two contiguous sections in 338 (35.8%) of 943 bronchi. CONCLUSION: Variation of airway lumen and WT is found in asymptomatic subjects without known cardiopulmonary disease.

Measurement of ammonia volatilization from a field, in upland Japan, spread with cattle slurry.

Ammonia volatilization from livestock manure is one of the most important pathways of nitrogen loss from agricultural cultivated fields. In this paper, we report the measurement of ammonia emission from cattle slurry manure applied to upland in Miyazaki, Japan. It has been determined that after the cattle slurry was sprayed on the upland surface, the emission flux of the first day was 110 microg N ha(-1) s(-1). The loss of NH4(+) -N in the applied slurry was 60% after 5 days following the spraying of cattle slurry.