An approach to mid-facial fractures.

The purpose of this article is to present a concept which facilitates the plain film identification of mid-face fractures. The concept evolves from a logical classification of mid-face fractures based upon the region(s) of involvement (orbit, zygoma, maxilla), the extent of the fractures (unilateral or bilateral) and the characteristic distribution of the fracture lines. Recognition of these fractures depends upon an awareness of the fact that the radiographic signs of mid-face fractures differ in certain respects from those involving other skeletal parts. In addition to skeletal disruption, the radiographic signs of mid-face fractures include soft tissue abnormalities which may be localized or diffuse, and which may be either extrinsic or intrinsic to the facial skeleton, alterations of normal skeletal contour, the "bright white line" of displaced fragments, and the subcutaneous emphysema which may also be localized or diffuse. The application of this concept to the roentgen diagnosis of mid-face fractures will be described and illustrated.

High-dose computed tomography in the evaluation of low attenuation lesions in the neck.

Recent reports have established the clinical utility of computed tomography (CT) in the evaluation of jugular vein thrombosis. Other abnormalities of the soft tissues in the neck can mimic this condition. This study reviews the pertinent normal soft tissue and vascular anatomy of the neck and describes the use of high-dose CT in the evaluation of low attenuation lesions in this area. Various abnormalities are compared and contrasted, including cystic hygroma, neoplasm, abscess, and venous thrombosis.

Gallbladder enhancement following angiography: a normal CT finding.

The authors reviewed computed tomography (CT) studies that had been preceded within 2 days by angiography. Twenty-one patients were selected who showed no laboratory evidence of liver or renal disease. Eighteen patients received greater than 37 g of iodine at angiography. Eight of these underwent CT within 2 h of angiography and showed enhancement of the gallbladder wall, nine underwent CT 15 to 48 h after angiography and showed enhancement of the gallbladder contents, and one had no gallbladder enhancement. Three patients received less than 22 g of iodine at angiography and none had gallbladder enhancement on CT. The necessity of differentiating normal gallbladder enhancement from pathology on CT is stressed. In addition, the physiologic mechanisms responsible for gallbladder enhancement are presented, and the relationship of our findings to the total body opacification effect and to infusion tomography of the gallbladder is discussed.

Evaluation of a digital subtraction angiography unit.

The operating characteristics of a digital subtraction angiography unit were evaluated. Measurements included image intensifier and system linearity, uniformity, quantum and system noise, and iodine contrast. Various approaches to noise measurement were analyzed and tested, leading to the following conclusions: the video level should be maximized; changes in signal-to-noise ratio (SNR) due to changes in x-ray exposure do not necessarily reflect changes in quantum SNR alone, due to dependence of video levels on x-ray exposure; an understanding of the separate contributions of quantum and video SNRs to the total SNR guides proper selection of variables to minimize patient dose and x-ray tube heat loading.

Computed tomography of renal inflammatory disease.

The value of computed tomography (CT) in patients with severe renal inflammatory disease has not been previously emphasized. This paper presents the authors' experience using this modality in 17 patients with acute intrarenal inflammatory conditions. A spectrum of various renal abnormalities and their CT appearance ranging from lobar nephronia (focal pyelonephritis) to xanthogranulomatous pyelonephritis is presented. These cases demonstrate that CT provides more precise anatomic information than does urography and is helpful in distinguishing uncomplicated patterns of renal infection from other types of renal inflammatory disease. In this way, patients who may be managed medically can be differentiated from those who require surgical intervention.

133xe uptake in focal hepatic fat accumulation: CT correlation.

Irregular fatty infiltration of the liver appears as focal areas of decreased attenuation on computed tomography (CT) and often cannot be distinguished from other, clinically more significant space-occupying lesions. Six patients with CT and clinical findings suggestive of fatty infiltration had xenon-133 ventilation scans of the liver. Four of these patients showed uptake and retention of 133Xe in the corresponding area of the liver, confirming the presence of fatty infiltration. The two patients in whom there was no uptake or retention of xenon by the liver were subsequently proven to have liver abscess and metastatic adenocarcinoma, respectively.

Computed tomography of hepatic fracture: a case report.

A case of hepatic fracture is presented in which computed tomography (CT) played a major role in the diagnosis. The fracture, which was suggested on scintigraphy, was easily demonstrated on CT as a low-density hematoma. The advantages and potential use of CT in this clinical setting are discussed.

Assessment of bone mass in the radius by computed tomography.

A reproducible method for quantitative analysis of computed tomographic cross-sections of the distal radius of patients with various metabolic bone diseases is described. A statistically significant correlation between the CT measurements in the radius and quantitative histomorphometric measurement of the trabecular bone volume of corresponding transilial bone biopsies is demonstrated. Selected longitudinal studies are presented to demonstrate the possible clinical applications of this type of CT analysis.

Bone mineral analysis using single-energy computed tomography.

We present a new method for evaluating in vivo changes in bone mineralization in the peripheral skeleton, using computed tomography (CT). A set of bone mineralization indices are generated from numerous CT images of the patient's distal radius. The cross-sectional anatomy displayed by the CT scan allows for separate evaluation of the cortical and trabecular bone. Correction for possible drift of the CT number scale (Hounsfield scale) is achieved by scanning standard solutions of dipotassium hydrogen phosphate simultaneously with the forearm. Preliminary data indicate that this is a precise method for evaluating in vivo changes in bone mineralization.