Computed tomography in the emergency department.

A study was conducted to determine parameters indicating the current use of computed tomography (CT) in the emergency department (ED). Computerized data regarding patients seen in the ED between 1/1/92 and 9/30/95 were retrieved. A rate of 36/1,000 patients underwent CT in the ED (ED CT). Of patients eventually hospitalized, 6.04% had ED CT, whereas 2.81% of the discharged patients had undergone ED CT (P < .001). The most common region examined by ED CT was the head (55.38%), followed by the abdomen (14.19%), pelvis (11.96%), spine (11.46%), and chest (5.57%). The hospitalization rates for patients undergoing head and spine ED CT were 35.99% and 36.84%, respectively. The hospitalization rates for patients undergoing abdomen, pelvis, and chest ED CT were 50.76%, 51.46%, and 55.61%, respectively. The mean number of patients undergoing ED CT increased according to age with a positive linear correlation. Head CT was most common in the very young and the very old. Some parameters about the use of ED CT were identified. The information obtained will allow comparison of practice between EDs in different medical centers and will be useful to hospital administrators, health planners, and clinicians. This retrospective analysis is to be followed by more comprehensive prospective studies involving different EDs in various sections of the country.

Fracture of the occipital condyles and associated craniocervical ligament injury: incidence, CT imaging and implications.

Thin section contiguous axial computer tomography (CT) was used to demonstrate fractures of the occipital condyle and craniocervical ligament injury. During a 12-month period, 55 consecutive patients who had sustained high energy blunt trauma to the head or upper cervical region were examined (38 male and 17 female, age range 3-80 years, median 24 years). If occipital condyle fracture was suspected clinically, CT was performed from C2 to the foramen magnum with two dimensional sagittal, coronal, and curvilinear reconstructions and employing bone and soft tissue windows. Occipital condyle fractures were classified according to Anderson and Montesano types 1, 2 or 3. Injury to the internal craniocervical ligaments was described. Nine of 55 patients had occipital condyle fractures (16.4%). Injury of the alar ligaments was demonstrated in four and tectorial membrane injury in two patients. Three of the nine patients had associated fractures of cervical vertebrae. Five of nine patients had a normal Glasgow coma scale on admission (55%) and in two patients the occupital condyle fracture was the only significant injury. Plain cervical radiographs were non-diagnostic. Two patients had significant pain and limited motion of the craniocervicum several months following injury. In conclusion, CT should be performed where there is a high clinical suspicion of occipital condyle fracture, that is based mainly on the mechanism of injury.

CT appearances of involvement of the peritoneum, mesentery and omentum in Wilms' tumor.

BACKGROUND: Peritoneal involvement by Wilms' tumor indicates stage III disease. CT is the single preferred modality in determining the extent and staging of Wilms' tumor; however, the CT appearances of Wilms' tumor involvement of the peritoneum have not been specifically addressed in the literature. OBJECTIVE: The objective of this study was to demonstrate the CT manifestations when there is involvement of the peritoneum, mesentery and/or omentum in Wilms' tumor. MATERIALS AND METHODS: Four cases of Wilms' tumor form the basis of this report. They were examined on Elscint CT scanners. RESULTS: Masses ("dropped metastases") in the pelvis were present in all four patients. Three patients had masses in the mesentery of the small bowel and sigmoid colon. Infiltration of the greater omentum was identified in two patients as a mantle of tumor separating bowel from the anterior abdominal wall. Ascites was present in two patients. In one patient broad-based solid masses of varying sizes were noted on the parietal and on the visceral surfaces of the peritoneum, and in a different patient a discrete mass was noted in the lesser omentum. CONCLUSION: The peritoneal spaces, recesses, ligaments and folds are invisible unless invaded by disease which is well demonstrated on CT.

Branchial pouch sinus tract from the piriform fossa causing acute suppurative thyroiditis, neck abscess, or both: CT appearance and the use of air as a contrast agent.

OBJECTIVE: Our objective was to describe the CT appearance of acute suppurative thyroiditis and neck abscess associated with a congenital sinus tract arising from the piriform fossa. In addition, we describe our observations on the use of air as a contrast agent during CT of the pharynx. CONCLUSION: The thyroid is extremely resistant to acute bacterial infection; hence, when such an infection does occur, an underlying anomaly of the thyroid should be suspected, particularly when the infection is recurrent. In such a case, sonography or CT must be used to confirm the diagnosis of acute thyroiditis, neck abscess, or both. Then the sinus tract must be revealed by barium esophagography, CT scanning that use air as a contrast agent, or endoscopy.

Lingual mandibular bony defects: CT in the buccolingual plane.

OBJECTIVE: Our goal was to record the appearance of lingular mandibular bony defects (LMBD) on CT imaging of the mandible in the buccolingual plane. MATERIALS AND METHODS: During the CT evaluation of patients planning to undergo dental implant surgery, five cases of LMBD were found. Axial 1.2 x 1.00 mm overlapping CT sections of the mandible and the maxilla were obtained. Then with use of specific software (DentaCT; Elscint), panoramic and cross-sectional (buccolingual) images of the mandible and maxilla were reformatted. RESULTS: Five cases of posterior LMBD were identified; one patient had both a posterior as well as the much rarer anterior LMBD. All cases were incidental findings and all were asymptomatic. CT features of LMBD were displayed in axial, panoramic, and buccolingual planes. The characteristic opening of the bony defect in the lingual aspect of the mandible was clearly displayed on the axial as well as the buccolingual images; however, this key feature was not manifest on the panoramic images of the mandible. CONCLUSION: CT features of LMBD in the buccolingual plane are added to the known radiologic description of this entity.

Subjective and objective assessment of image quality--a comparison.

Forced-choice just noticeable difference (JND) studies are extremely sensitive to image quality variations that are below the threshold at which the differences are apparent to or definable by the observer. Paired comparisons of 4K and 2K laser-printed posteroanterior chest images consistently demonstrated that although images are viewed as comparable by radiologists, when forced to choose the better ("sharper") image, they actually select the higher-resolution images in 83% of the paired observations. We conclude that small differences in image quality may be detectable even in image sets which are considered to be comparable by subjective assessments.

Reduced dose and improved image quality with a computerized line-scan radiography system.

Diode-array digital radiography (DADR) is a patented technology which shows promise for producing improved radiographic image quality while reducing the X-ray dose to the patient. DADR combines geometric scatter rejection with a scintillator and solid-state photodiode array detector of large dynamic range to create diagnostic X-ray images which makes efficient use of the patient dose. Engineering measurements were made to determine the basic characteristics of the system. Engineering measurements were made to determine the basic characteristics of the system. A number of image postprocessing techniques were examined for further improving the image quality of the DADR system. Unsharp masking, local contrast stretching, and modified local contrast stretching were used. The modified local contrast stretching has produced the best results to date, with image quality exceeding that of standard film/screen chest images. Images have been postprocessed using facilities of the Pittsburgh Supercomputer Center.

Skeletal muscle density: effects of obesity and non-insulin-dependent diabetes mellitus.

Obesity is associated with increased lean mass but its effects on lean-tissue density are less clear. To examine the effects of obesity and non-insulin-dependent diabetes mellitus (NIDDM) on lean-tissue composition and density, cross-sectional computed tomography (CT) scans of the midthigh were obtained in 20 men of various weights. Obesity was associated with increases in thigh-adipose (r = 0.75) and lean-tissue volumes (r = 0.52) and with reduced density of lean tissue (r = -0.73). The increased lean tissue in obesity was due to a nonadipose tissue component with a density below the normal range of muscle, an effect compounded by NIDDM, whereas normal-density muscle volume was unchanged.

Sonographic characteristics of epidermoid cyst of testicle.

The ultrasonographic characteristics of an epidermoid cyst of the testicle are presented. Since these findings are similar to other published case reports, preoperative sonographic diagnosis of this lesion may be possible.

Effect of observer instruction on ROC study of chest images.

Receiver-operating characteristic (ROC) analysis has been used in many medical imaging applications during the past decade. In order to ensure that reader-confidence ratings are analyzable (well distributed to meet convergence requirements of curve-fitting algorithms) and meaningful (limit extrapolation of the data), many investigators train readers specifically for this purpose. No experimental data are available concerning the possible effects of such training on the results of ROC studies. We performed a multi-observer, multi-disease study in which 300 chest images were rated by four radiologists before and after they were trained to provide well-distributed confidence ratings. The results indicate that for our data set, reader and disease-specific accuracy was not significantly affected by the training process for interstitial disease and pneumothoraces. However, the accuracy of two readers was significantly affected for the detection of nodules (P less than 0.05), and the overall accuracy of one reader was significantly affected for the classification of normal versus abnormal images (P less than 0.01). Thus, in spite of the difficulties associated with the performance of ROC studies in a free-reading environment, one should carefully consider the possible effects of any intervention on the results prior to conducting ROC studies.

Receiver operating characteristic analysis of chest image interpretation with conventional, laser-printed, and high-resolution workstation images.

The differences among radiologists in interpreting conventional and digitized images obtained with different radiologic procedures is an important research issue in these times of implementation and growth of the digital modalities. The authors performed a multiobserver study to determine the performance of radiologists reading posteroanterior conventional radiographs, digitized radiographs laser printed onto film, and images displayed on a high-resolution workstation (video monitor). A total of 300 images were evaluated by seven radiologists who recorded their ordinal confidence rating of the presence or absence of one or more of the following abnormalities: interstitial disease, nodule, and pneumothorax. Receiver operating characteristic analysis showed statistically significant differences for the detection of different abnormalities by individual readers. The group as a whole showed a significant reduction in observer performance for the detection of interstitial disease and pneumothorax when the laser-printed radiographs or the workstation was used rather than conventional radiographs.

MR imaging with gadolinium-DTPA in the differentiation of tumor, syrinx, and cyst of the spinal cord.

Intravenous Gd-diethylenetriamine pentaacetic acid was used in 16 patients to differentiate between syringomyelia, syringomyelia in association with tumor, and cystic tumor in the spinal cord. Contrast enhancement occurred in all 12 histologically proven cases of tumor and enabled clear demarcation of neoplastic tissue from syrinx or cyst. Eleven of the twelve tumors seen in association with spinal cord cavitation were malignant; all tumors apart from one (a schwannoma) were intramedullary in location. Enhanced scans were more helpful than unenhanced scans in diagnosing and defining the extent of tumors associated with a syrinx or cyst.

Digital radiography of the chest by self-scanning linear diode arrays.

Diode array digital radiography DADR is a method of radiographic imaging that combines the advantages of computer technology with self-scanning linear diode arrays. These digital images are superior to those obtained by film in recording and displaying information in the lightest and the darkest areas of the film, resulting in a balanced image of the entire thorax without compromising detail, and at reduced radiation dose. This is a direct result of the wide dynamic range, high contrast sensitivity, fiber optic coupling, small diode size, short exposure time, and rejection of scattered x-rays of the system coupled with digital post-processing enhancement of the image displayed at 1024 X 1024 pixels.

Posttransplantation cyclosporine-induced lymphoproliferative disorders: clinical and radiologic manifestations.

Fifteen allograft transplant recipients acquired lymphoproliferative disorders after immunosuppressive therapy with cyclosporine and steroids. Many of these lymphoproliferative disorders regressed or disappeared completely after reduction of cyclosporine dose. This disease has several aspects that distinguish it from usual posttransplantation lymphomas that occur with regimens that do not contain cyclosporine. The time course from transplantation to onset of lymphoma is relatively short, with an average of approximately 8 months. Organs show a wide spectrum of abnormalities typical of other immunosuppression-associated lymphomas, but there is unique sparing of the central nervous system. The tumor is also unique in that it responds to a decrease in the cyclosporine dose.

Prospective study of computed tomography in initial management of blunt abdominal trauma.

Physical examination is often unreliable in the evaluation of blunt abdominal trauma. The utility of computed tomography (CT) in the early management of abdominal trauma in the absence of definite signs is controversial. CT was prospectively evaluated as an adjunct to physical examination in the initial assessment of blunt abdominal trauma. Indications for emergency abdominal CT were a stable patient with an equivocal abdominal examination, closed head injury, spinal cord injury, hematuria, or pelvic fracture. One hundred twenty patients were studied. CT was accurate in 98.3% of these patients. With associated head injury, combining head and abdominal CT proved to be expeditious. Splenic, hepatic, and renal injuries were reliably detected with CT. Minor injuries which did not require laparotomy were reliably diagnosed. Patients with acute pancreatic injuries may have normal CT findings. Eighty-six per cent of laparotomies were therapeutic. In conjunction with close clinical monitoring, CT was reliable in evaluation of blunt abdominal trauma in a selected group of patients.

Long-term prognosis of survivors of Pneumocystis carinii pneumonia. Structural and functional correlates.

Limited data exist detailing the long-term sequelae of Pneumocystis pneumonia. Open lung biopsies were obtained in seven renal transplant recipients within 48 hours of the onset of respiratory failure. Biopsy specimens and simultaneous chest roentgenograms were graded without clinical information according to the severity of alveolar damage and pulmonary infiltrates, respectively. Evaluation of pulmonary function and exercise physiology were performed 15 to 21 months after their illness. Pulmonary function indices were normal except FRC (2.65 +/- 0.56 L or 77 +/- 16 percent of predicted) and Dsb (20.0 +/- 7.2 ml/min/mm Hg or 79 +/- 19 percent of predicted). Two patients developed arterial desaturation with exercise. Alveolar damage scores correlated with later exercise arterial desaturation (r = 0.88, p less than 0.05). Simultaneous roentgenographic scores correlated with later abnormalities of Dsb (r = 0.81, p less than 0.05). Mild residual abnormalities of pulmonary function were found in five of seven adult survivors of Pneumocystis pneumonia. These abnormalities correlated with pathologic and radiographic features of the acute illness.

Sonography of cholesterol in the biliary system.

The sonographic features of cholesterol within the biliary system are reviewed and a new sign is described. That cholesterol causes high reflecting echoes and may cause shadowing has been known; however, its ability to cause reverberatory artifactual echoes has not been previously appreciated. These sonographic features, while not specific, should favor the diagnosis of cholesterol stones and cholesterol polyps in the appropriate clinical situation.

Computed tomography appearance of melanoma of nasal cavity.

Melanoma of the nasal cavity is a mucosal lesion that is quite rare. It comprises less than 1% of all melanomas and constitutes 4% of primary malignant tumors of the nasal cavity. The computed tomography appearance of this entity is discussed and found to be nonspecific.