R. Gilbert Jost

Accuracy of computed tomography of the liver and biliary tract.

Computed tomography (CT) is a highly accurate method of detecting and clarifying the nature of space-occupying lesions within the liver. Obstructive (surgical) jaundice can be differentiated from nonobstructive (medical) jaundice very accurately using CT scanning; when obstruction is present, its level and cause can often be diagnosed. CT is not a sensitive method of detecting hepatocellular disease. Sources of error in CT scan interpretation are analyzed.

Are Excretory Urograms Necessary in Evaluating Women with Urinary Tract Infection

Of 164 excretory urograms obtained from women with a history of recurrent urinary tract infections 88 per cent were perfectly normal. Eleven (6.7 per cent) had minor, normal, anatomic variations. Nine (5.5 per cent) were considered to have positive findings but in no case a significant finding present that required surgical intervention or altered the therapeutic approach. The total cost of the studies to the patients involved was

Gated Computed Tomography of the Human Heart

17,930. Thus, an extremely negative cost-benefit ratio emerged. The routine use of excretory urograms as part of the evaluation of a woman with a urinary tract infection is expensive, unrewarding and has little justification.

Complementary use of ultrasound and computed tomography in studies of the pancreas and kidney.

Production of in vivo images of the human heart, with delineation of the individual cardiac chambers and myocardial wall thickness, was accomplished by coupling a relatively simple electrocardiographic gating device to a translate-rotate type of computed body tomographic scanner. Differentiation between the myocardial wall and the intracardiac blood pool was attainable in the patient with a normal hematocrit only when intravenous iodinated contrast media was used.

Progressive Coding and Transmission of Digital Diagnostic Pictures

113 cases of pancreatic and renal disease studied by both ultrasound and computed tomography (CT) were analyzed retrospectively. CT provided a diagnosis when pancreatic ultrasound was unsuccessful due to overlying bowel gas or obesity and when renal ultrasound was unsuccessful due to obesity, reverberations from ribs, small lesions, or multiple lesions. Conversely, ultrasound provided a diagnosis when CT was unsuccessful due to lack of fat planes or respiratory motion. CT usualy distinguished carcinoma from pancreatitis when ultrasound showed a focal echogenic mass. CT resolved renal cyst from neoplasm when ultrasound showed a mixed echo pattern mass.

The clinical efficacy and cost analysis of cranial computed tomography and the radionuclide brain scan

In radiology, as a result of the increased utilization of digital imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), over a third of the images produced in a typical radiology department are currently in digital form, and this percentage is steadily increasing. Image compression provides a means for the economical storage and efficient transmission of these diagnostic pictures. The level of coding distortion that can be accepted for clinical diagnosis purposes is not yet well-defined. In this paper we introduce some constraints on the design of existing transform codes in order to achieve progressive image transmission efficiently. The design constraints allow the image quality to be asymptotically improved such that the proper clinical diagnoses are always possible. The modified transform code outperforms simple spatial-domain codes by providing higher quality of the intermediately reconstructed images. The improvement is 10 dB for a compression factor of 256:1, and it is as high as 17.5 dB for a factor of 8:1. A novel progressive quantization scheme is developed for optimal progressive transmission of transformed diagnostic images. Combined with a discrete cosine transform, the new approach delivers intermediately reconstructed images of comparable quality twice as fast as the more usual zig-zag sampled approach. The quantization procedure is suitable for hardware implementation.

A Computer-Assisted Method to Determine the Diagnostic Efficacy of Computed Tomography of the Body

Cranial computed tomography (CCT) has already been demonstrated to provide significant diagnostic information in patients with neurologic disease and to reduce the need for special neuroradiologic procedures. The important question remaining is: Should CCT replace the radionuclide brain scan (RBS) as the first diagnostic study in most patients with suspected intracranial pathology? Data are now available to define the costs and benefits of this substitution. The technical costs of CCT have been determined by a national survey and have shown to be

A distributed approach to integrated inquiry and display for radiology

130 per patient at a volume of 50 patients per week. The costs of RBS at the Mallinckrodt Institute have been estimated at

Economic Analysis of Body Computed Tomography Units including Data on Utilization

51 per patient. Data from the literature indicate that CCT is slightly more sensitive and considerably more accurate than RBS. Eighteen to twenty-eight percent of patients studied by CCT and RBS have abnormalities (e.g. cerebral atrophy and ventricular dilatation) that are only detected by CCT, and the overall accuracy of CCT is 95%, while the accuracy of RBS is approximately 70%. Substituting CCT for RBS is cost-beneficial. Although CCT is more costly, it increases overall accuracy by approximately 25%. The cost benefit is further increased by the reduction of complicated diagnostic procedures (and associated hospitalization and morbidity) and improvement in diagnostic information for the individual patient. Substituting CCT for RBS may not be more costly because a positive RBS will be followed by CCT (because of increased diagnostic information), and a negative RBS may be followed by CCT (because of increased accuracy), whereas a positive or negative CCT is unlikely to be followed by RBS.

Filmless digital chest radiography within the radiology department

A computer-assisted system has been devised to provide objective measurements of the diagnostic efficacy of CT of the body. The diagnostic efficacy of CT is compared with that of UGI examinations for 574 patients. The potential usefulness of this system in cost effectiveness studies, diagnostic efficacy studies, and clinical efficacy studies is examined.