Increased Opacity of Left Pericardiac Area on Chest Radiograph: Correlation with CT Findings and its Frequency

PURPOSE: The purpose of this study was to evaluate the incidcnce of extrapericardial fat in the left cardiacborder, and with regard to left extrapericardial fat, to correlate chest radiographs with CT scans. MATERIALS AND METHODS: This study involved 132 consecutive patients who underwent chest PA and lateral radiographs, and chestCT scans. According to the results of chest PA radiograph, patients were divided into three groups: those with aclear left cardiac border; those with an indistinct left cardiac border; and those with an indistinct left cardiacborder with increased density; cardiophrenic angle, as seen on lateral radiograph, the presence of increaseddensity in the anterior cardiophrenic angle, as seen on lateral radiograph radiographs was evaluated. On the basisof the results of CT scanning, patients were classified into four groups according to the amount of leftextrapericardial fat: negative, minimum, moderate, and maximum. Left extrapericardial fat, as seen on CT, wascorrelated with the conspicuity of left cardiac border seen on PA radiograph and the presence of increased densityin the anterior cardiophrenic angle, as seen on lateral radiograph. RESULTS: On CT, left extrapericardial fat wasobserved in 51 patients (38.6%). In 38 of these (28.8%), the amount was minimal, in 12 (9.1%), it was moderate,and in one (0.8%), it was maximal. On posteroanterior chest radiograph, clear, indistinct, and indistinct andincreased density of the left cardiac border was seen in 89 (67.4%), 28 (21.2%), and 15 cases (11.4%),respectively. On lateral radiograph, increased density of the anterior cardiophrenic angle was seen in 115 cases(87.1%) but in 17 (12.9%), increase density was not apparent. There was significant correlation between chestradiographs and CT(p<0.001) (sensitivity: 53%; specificity: 100%; positive predictive value: 100%; negativepredictive value: 84%). CONCLUSION: The conspicuousness of the left cardiac border, as seen on PA chestradiograph, correlated with the presence of left extrapericardial fat, as seen on CT, and was related to theamount of left extrapericardial fat. Increased density of the anterior cardiophrenic angle, as seen on lateralradiographs, correlated with the presence of left extrapericardial fat on CT, but the absence of increased densityon lateral radiograph corresponds to the absence or a minimal amount of left extrapericardial fat, as seen on CT.

Can Anterior Junction Line be Used to Distinguish Right Middle from Right Upper Lobe on CT Scan?

PURPOSE: To evalvate the usefulness on a CT chest scan, of the anterior junction line as an anatomical landmark to distinguish the right middle and the right upper lobe MATERIALS AND METHODS: We found that the anterior junction line has a constant anatomical relationship with the right upper and middle lobe, and with this in mind, analysed connvcntional CT films of 86 patients with normal lung (group A) and 30 with architectural distortion (group B). On a series of slices, we compared the location of slice 1 with that of slice 2 (slice 1: the slice which includes the lowest portion of the anterior junction line, slice 2: the initial slice, in which the right middle lobe occupies the whole of the lung anterior to the right major fissure). RESULTS: In group A (n=86), the right upper lobe, as seen in the anteromedial zone of slice 1, was present in 83 cases (96.5%). The right upper lobe on slice 1 was absent in two cases (2.3%) in which a minor fissure was almost completely abent. In group B (n=30), the right upper lobe on slice 1 was absent in 19 cases (63.3%). CONCLUSION: We suggest that on a CT chest scan, the anterior junction line can be used as an anatomical landmark in the differentiation of the right middle from the right upper lobe, and as an indicator of the presence of architectural distortion.

The Oblique Interface in the Right Cardiophrenic Angle: Chest Radiographic-CT Correlation

PURPOSE: An oblique interface in the right cardiophrenic angle, extending superomedially from rightretrocardiac or supradiaphragmatic region inferolaterally to peridiaphragmatic region, is occasionally observed onposteroanterior chest radiograph. The aim of this study was to evaluate the frequency of visualization of the interface on chest radiographs and to elucidate its nature on radiographic-CT correlation. MATERIALS AND METHODS: Posteroanterior chest radiographs from 300 consecutive subjects were analyzed to evaluate the frequency and demographic data about an oblique interface in the right cardiophrenic angle. Thin-section CT scans(1-mmcollimation and 5-mm intervals) were obtained from the subjects with positive interface on chest radiograph for assessment of the nature of the interface. The demographic data in the subjects with and without the interface were tested statistically to note any difference between two groups. RESULTS: Oblique interface in the right cardiophrenic angle was present in 29 subjects(9.7%) on chest radiograph. The age of the subjects with positive interface(13 men and 16 women) ranged from 19 to 70 years(mean +/-SD, 47+/- 12.7 years) whereas the age of thesubijects without the interface from 16 to 82 years (mean +/-SD, 50+/-9.1 years)(p>0.1). The body weight of thesubjects with the interface ranged from 41 to 72 Kg(mean +/-SD, 60 +/- 8.0Kg) whereas the body weight of thesubjects without the interface from 41 to 85 Kg(mean +/-SD, 63+/-10.1Kg)(p>0.1). On CT scan, it was formed due tocontact between the epipericardial fat and the right middle lobe of the lung in 27 subjects(93%) and between the inferior vena cava and the medial basal segment of the right lower lobe of the lung in two(7%). CONCLUSION: Oblique interface in the right cardiophrenic angle is occasionally visualized on chest radiograph. It is formed due to contact between the right middle lobe of the lung and pericardial fat in most cases. The frequency of visualization of the interface has no relationship to age and body weight of the subjects.