Efficacy of digital radiography for the detection of pneumothorax: comparison with conventional chest radiography.

As part of our continuing evaluation of the clinical applicability of digital radiography, we compared the abilities of radiologists to detect pneumothoraces on conventional chest radiographs with their performances when using three formats of digitally obtained images. Twenty-three frontal-view chest radiographs with pneumothoraces and 22 other chest radiographs, either normal or showing miscellaneous abnormalities, were interpreted by five experienced radiologists in each of four formats: conventional film-screen chest radiographs, small-format (17.8 x 21.6 cm) computed radiographs, large-format (35.6 x 43.1 cm) computed radiographs, and digital images viewed on an interactive electronic workstation. The receiver-operating-characteristic curve areas for each observer for the four types of images were compared by a z test on a critical ratio, and the mean sensitivity and specificity values were compared by the sign rank test. The mean areas under the receiver-operating-characteristic curves ranged from 0.869 for the digital workstation to 0.915 for film-screen images. The differences observed among formats were not statistically significant. Mean specificities also were not significantly different, ranging from 0.90 for large-format computed radiographs to 0.96 for the digital workstation. Mean sensitivity ranged from 0.65 for the digital workstation to 0.82 for film-screen images. Radiologists interpreting digital workstation images were significantly less sensitive in detecting pneumothoraces than with film-screen and small-format computed images (p = .06). In this study, radiologists detected pneumothoraces equally well on conventional film-screen radiographs and digital images printed on film; however, they detected pneumothoraces less well on electronic viewing consoles. This latter finding reflects an important practical difference in the working behavior of radiologists interacting with a digital workstation.     

Intrafissural fat: CT correlation with chest radiography

A small collection of supradiaphragmatic fat is occasionally present invaginating into the inferior aspect of the major interlobar fissure. In a review of 212 computed tomography (CT) scans obtained in the immediate supradiaphragmatic region, 39 cases demonstrated some degree of this intrafissural fat collection either unilaterally or bilaterally. On lateral chest radiographs, the intrafissural fat corresponded to a sharply marginated triangular density, the base of which abutted the anterior diaphragmatic surface and the apex of which tapered into the major fissure. The triangular density seen on the chest radiographs was superimposed over the heart and cardiac fat pad but was always easy to distinguish from these owing to the continuity of the density with the oblique fissure.     

Unknown primary tumors: detection with dual-modality PET/CT--initial experience

PURPOSE: To retrospectively evaluate fused positron emission tomography (PET)/computed tomography (CT) in depicting the primary lesion in cancer of an unknown primary tumor, compared with PET, CT, and PET and CT side-by-side evaluation. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Forty-five patients (26 men and 19 women) with metastatic cervical adenopathy (n = 18) or extracervical metastases (n = 27) of unknown primary tumor were included. The mean age of the patients was 57 years (range, 29-95 years). PET/CT imaging was performed in all patients 1 hour after administration of 350 MBq of fluorodeoxyglucose with a whole-body field of view. Contrast agents were administered orally and intravenously in all patients to ensure diagnostic CT data. PET/CT data sets were evaluated for the primary tumor, and imaging results were compared with those of CT, PET, and PET and CT side-by-side evaluation. Differences in diagnostic performance were assessed by using the McNemar test with Bonferroni correction, which accounts for multiple comparisons. RESULTS: PET/CT depicted the primary tumor in 15 (33%) of 45 patients. In 30 (67%) patients, the primary tumor site remained occult (P > .05). PET and CT side-by-side evaluation depicted 13 (29%) of 45 tumors (P > .05). PET alone revealed the primary tumor in 11 (24%) of 45 patients (P > .05), while CT alone helped in the correct diagnosis in eight (18%) of 45 patients (P > .05). There were no significant differences between the diagnostic accuracies of PET/CT and the other imaging modalities. CONCLUSION: PET/CT was able to depict more primary tumors, though not significantly, than either of the other imaging modalities, but larger patient cohorts are required to finally judge its value for revealing the primary tumor site.     

Aortopulmonary window lesions: detection with chest radiography

A retrospective morphologic study of 80 cases was undertaken to determine factors affecting detectability of computed tomographically (CT) proved aortopulmonary (AP) window lesions on conventional posteroanterior (PA) and lateral chest radiographs. Criteria used for determining abnormality were: solitary lymph node enlargement over 1.5 cm or three or more 1-cm nodes and obvious large masses or vascular anomalies. CT scans and corresponding PA and lateral radiographs were analyzed for lesion detectability, size, and location. In 49% of cases there was no detectable lesion in the AP window on radiographs; a definite AP window lesion was seen in 41%, and 10% were equivocal. Major contributing factors to low detectability of AP window lesions on radiographs include size and, more important, location of the lesion. An additional 45 cases of CT-proved normal AP windows were retrospectively reviewed to determine the false-positive rate of PA and lateral radiographs in detection of AP window lesions: 43 (96%) were classified as negative, the remaining two (4%) as equivocal. Although the AP window is a small space, it is the site of many pathologic conditions; the study results indicate that CT may be an essential procedure for its evaluation.     

Lung micronodules: automated method for detection at thin-section CT--initial experience

An automated system was developed for detecting lung micronodules on thin-section computed tomographic images and was applied to data from 15 subjects with 77 lung nodules. The automated system, without user interaction, achieved a sensitivity of 100% for nodules (>3 mm in diameter) and 70% for micronodules (相似文献   

Vertical fissure: computed tomographic observation and correlation with chest radiography

Purpose The purpose of this study was to assess radiographic and computed tomography (CT) findings of the vertical fissure. Materials and methods We assessed whether the vertical fissures appeared as a fine linear shadow or as a linear edge with lateral opacity and medial lucency on chest radiographs. The CT scans were evaluated for the presence of volume loss in the lower lobes and for the presence of a portion of the fissure that is orientated tangential to the X-ray beam. Results We observed vertical fissures in six patients. CT studies revealed volume loss in the lower lobes in all patients and showed the presence of a portion of the fissure that is orientated tangential to the X-ray beam in only two patients whose vertical fissures were not associated with lateral opacity and medial lucency on chest radiographs. Conclusion We believe that the vertical fissure is closely related to volume loss in the lower lobe and represents the edge of the anterobasal segment of a major fissure or a portion of the fissure that is orientated tangential to the X-ray beam, with or without lateral opacity and medial lucency.     

Esophageal cancer: evaluation with triple-phase dynamic CT--initial experience

PURPOSE: To prospectively assess which phase of a triple-phase dynamic contrast material-enhanced multi-detector row computed tomography (CT) protocol is optimal for visualization of esophageal cancer. MATERIALS AND METHODS: The study was supported by the local ethical committee; all patients gave written informed consent. Thirty-one lesions in 28 consecutive patients (26 men, two women; mean age, 65 years; range, 53-87 years) with histopathologically confirmed esophageal cancer were evaluated with triple-phase dynamic CT performed at 5, 35, and 65 seconds (first arterial, second arterial, and venous phases) after attenuation of 200 HU was obtained at the descending aorta. Qualitative image analysis was performed to assess appearance and conspicuity of the tumor. Appearances of all 31 lesions were classified into three categories-not identifiable, focal enhancement with or without minimal (<1 cm) wall thickening, and focal mass lesion or obvious (>1 cm) wall thickening. Results were compared with surgical or endoscopic ultrasonographic findings. Quantitative assessment included regions-of-interest measurement of the tumor and normal esophageal wall and the difference between those measurements. A paired t test was used to determine which phase showed the highest tumor attenuation and tumor-to-normal esophageal wall attenuation differences. RESULTS: At visual assessment, 30 lesions were identified in the second arterial phase. Of these 30 lesions, eight were focal enhancements; the best conspicuity was during the second arterial phase. Furthermore, seven of these eight lesions were T1 cancers. The remaining 22 lesions were enhanced masses or wall thickening. Twenty-one of these 22 tumors also showed best conspicuity in the second arterial phase. The greatest attenuation of tumors in the second arterial phase was 130.0 HU, and the difference in attenuation between tumor and normal esophageal wall was 50.6 HU in the second arterial phase, which were significantly higher than those in the other two phases (P<.01, each). CONCLUSION: The second arterial phase of dynamic CT is the optimal phase for visualization of esophageal cancer.     

Postbiopsy pneumothorax: estimating the risk by chest radiography and pulmonary function tests

Pulmonary function tests and chest radiographs of 160 patients who had had percutaneous needle biopsy of lung lesions were reviewed to determine the value of these examinations in estimating the risk of postbiopsy pneumothorax. Chest radiographs were evaluated subjectively for changes of obstructive and restrictive airway disease and for size and depth of lesion. Pulmonary function tests, consisting of simple spirometry (forced vital capacity, percentage of predicted forced vital capacity, forced expiratory volume in 1 sec, percentage of predicted forced expiratory volume in 1 sec, and [forced expiratory in 1 sec/forced vital capacity] X 100), and the pulmonologist's interpretation were evaluated. Pneumothorax developed in 46% (31/67) of patients who had obstructive airway disease according to the results of pulmonary function tests and in 42% (34/81) of those who had obstructive airway disease according to changes on chest radiographs, compared with 19% (10/53) and 25% (17/67) of those who had normal pulmonary function tests and chest radiographs, respectively. Pneumothorax developed in 46% (23/50) of patients who had findings of obstructive airway disease on both pulmonary function tests and on chest radiographs, compared with 7% (2/28) of patients who were classified as normal by both criteria. None of the patients who had normal pulmonary function tests required placement of a chest tube, whereas 19% (13/67) of those who had obstructive airway disease required chest tubes. Decreasing size of lesion and increasing depth of lesion were associated with a significant increase in the risk of pneumothorax. We conclude that the results of chest radiographs and pulmonary function tests are useful parameters for estimating the risk of postbiopsy pneumothorax.     

Improved chest disease detection with scanning equalization radiography

The efficacy of chest disease detection with scanning equalization radiography (SER) was evaluated in a clinical study of 95 patients: 51 normals and 44 with abnormal chest radiographs. A conventional and an SER image of each patient were interpreted independently by four radiologists. The increased numbers of true positives (3%) and true negatives (9%) when the SER images were interpreted were statistically significant. There was also a reduced number of false positives (7%) with SER. This improved disease detection was noted by each of the radiologists and led to more frequent agreement (11%) of the correct interpretation among the radiologists.     

Traumatic rupture of the right hemidiaphragm: Diagnosis by chest radiography

Sixteen cases of blunt trauma resulting in surgically confirmed traumatic rupture of the right hemidiaphragm were reviewed from the Trauma Registry of Allegheny General Hospital. Only 10 of the 16 cases (63%) could be retrospectively diagnosed on chest radiographs. We found that a diagnosis of right-sided diaphragmatic rupture can be suggested when the apex of the right hemidiaphragm is shifted superomedially to a position approximately midway between the mediastinum and the right chest wall. Eight of these 10 cases with positive chest radiographic findings exhibited this superomedial shift of the diaphragmatic apex. On initial assessment, without using this sign, 5 of these 10 cases were not diagnosed. We feel that the combination of elevation of the right hemidiaphragm in association with a medial shift of the apex of that diaphragmatic dome in a patient who has suffered extensive blunt thoracoabdominal trauma is strongly suggestive of traumatic rupture of the diaphragm.     

CT and chest radiography are equally sensitive in the detection of pneumothorax after CT-guided pulmonary interventional procedures

Pneumothorax is the most common complication after CT-guided pulmonary interventional procedures and should be promptly diagnosed and treated. Because it is easier to obtain CT scans than chest radiographs after CT-guided interventional procedures, it is important to know the sensitivity of CT in detecting pneumothoraces. To determine the sensitivity of CT for detecting procedure-induced pneumothoraces, we retrospectively reviewed 70 pulmonary interventional procedures performed under CT guidance. The sensitivity for detecting pneumothoraces with CT was compared with the detection rate with expiratory chest radiographs. Thirty-two (46%) of 70 procedures resulted in pneumothorax. Twenty-nine (91%) of the pneumothoraces were detected on CT scans and 27 (84%) were detected on chest radiographs. The difference between these two detection rates was not statistically significant (p less than .90). We conclude that postprocedure CT scans can replace expiratory chest radiographs for the detection of pneumothoraces after CT-directed pulmonary procedures.     

Digital radiography of the chest: clinical experience with a prototype unit

A prototype digital unit dedicated to chest radiography was used to examine 50 selected patients for a comparison study of the capability of digital images and conventional chest radiographs to reveal normal anatomic structures and a variety of pathologic states. The images in both modes were submitted for interpretation to seven experienced radiologists and a standardized questionnaire completed for each. Visibility of seven anatomic structures in the mediastinum was consistently better on the digital images than on the conventional radiographs. With minor exceptions, pathologic states were equally well seen in the two systems. Despite the less familiar viewing format of the digital images, the mean confidence levels achieved were higher than for those on the conventional radiographs; this difference was statistically significant both for normal anatomic structures (p = 0.001) and pathologic states (p = 0.01). The advantages and disadvantages of the digital technique are discussed.     

Mitral regurgitation: quantification with 16-detector row CT--initial experience

PURPOSE: To prospectively determine if retrospectively electrocardiographic (ECG)-gated multi-detector row computed tomography (CT) with a 16-detector row CT scanner can depict mitral regurgitation and enable quantification of the severity of the disease. MATERIALS AND METHODS: The study had institutional review board approval, and patients gave informed consent. Nineteen patients with mitral regurgitation (10 men, nine women; mean age, 66 years +/- 9 [standard deviation]; range, 41-83 years) and 25 patients without mitral regurgitation (14 men, 11 women; mean age, 68 years +/- 9; range, 43-83 years) as determined with transesophageal color Doppler echocardiography and ventriculography underwent retrospectively ECG-gated 16-detector row CT. Twenty CT data sets covering the entire mitral valve apparatus were reconstructed in 5% steps of the R-R interval for each patient, and data analysis was performed with four-dimensional software. Using planimetry, two readers measured in consensus the area of the regurgitant orifice during systole. These measurements were compared with semiquantitative data from transesophageal echocardiography and ventriculography by using Spearman rank order correlation coefficients. RESULTS: In the 25 patients without mitral regurgitation, no regurgitant orifice during systole could be detected with multi-detector row CT. In the 19 patients with mitral regurgitation, a regurgitant orifice could be visualized in all cases. The mean regurgitant orifice area at CT-45 mm(2) +/- 34 (range, 10-148 mm(2))-correlated significantly with the results at transesophageal echocardiography (r = 0.807, P < .001) and ventriculography (r = 0.922, P < .001). CONCLUSION: Planimetric measurements of the regurgitant orifice area at retrospectively ECG-gated 16-detector row CT enable quantification of mitral regurgitation.