Biomedical subjects
Publications and source records attributed to J Wittenberg.
Clinical examinations with the whole body CT scanner require considerable individualization of examination technique in relation to specific organs, anatomic areas, and clinical problems. Careful selection of radiographic factors, patient position, contrast agents, and pharmacologic adjuncts will optimize diagnostic results and patient throughput.
A method for assessing the effect of computed body tomography on diagnostic understanding and therapeutic decision making is described and the results in the first 184 patients are presented. The patients' referring physicians provided the primary data used for the evaluation. CT improved diagnostic understanding in 41% of patients, reassured the physician about previously planned therapy in 43%, contributed to a change in therapy in 17%, and improved precision of previously planned treatment in an additional 10%. CT contributed to a decision not to perform surgery in 21% of patients in whom an operation had been provisionally planned While CT can play an important role in patient management, its measured value depends on the clinical problems investigated and the level of efficacy on which it is judged.
Computerized axial tomography of the brain is a revolutionary noninvasive technique that has provided remarkable resolution of intracerebral structures. This study was undertaken to determine the potential of computerized tomography for defining the anatomy of 40 arrested and 9 beating (ejecting left heart preparation) canine hearts. Using an EMI cranial unit, scanning was performed in hearts under in vitro conditions with a lactated Ringer's interface. The tomographic scans obtained were later compared with comparable 8 mm thick sections of the heart. At physiologic levels of hematocrit (range 36 to 45%) external structures were well defined, but because of the lack of a differential between cavitary and myocardial densities, it was not possible to distinguish intracardiac structures. With very small amounts of iodinated contrast material (remotely administered in the case of the beating hearts) or with anemia (hematocrit less than 33%), the right and left ventricular cavities became clearly visible in both horizontal and longitudinal tomographic scans. It was possible to distinguish readily the boundaries of the ventricular and atrial cavities, the papillary muscles, the major trabeculae and the aorta. Rhythmic motion of the beating heart, suspended in its pericardium, did not eliminate structural definition. Thus, computerized tomography provides a new approach to the definition of cardiac structure with a relatively high degree of resolution. These observations point to the potential usefulness of this noninvasive technique for the evluation of both cardiac function and ventricular wall abnormalities.
The effect of formalin, freezing, and refigeration on the attenuation coefficient of fresh abdominal tissue of rhesus monkeys and dogs was investigated over a 1-week period. These techniques were used individually and in combinations designed to simulate circumstances involved in future in vitro investigations of human specimens. Statistically significant alterations of attenuation coefficients were found to occur at all scanning times within the first week except for the first 48 hr of formalin storage. Refrigeration resulted in the largest alteration. The results indicate the attenuation coefficients of tissues preserved by these three methods may be altered and that the magnitude of the change will vary according to the preservation techniques, tissue, and duration between tissue death and scanning.
The recent wide acceptance of Chiba needle transhepatic cholangiography prompted this elaboration of present techniques, intraprocedure observations, and special interpretive considerations based on a series of 100 consecutive examinations. The established safety margin of this technique now permits up to 15 needle passes to obtain a cholangiogram; thus success rates of duct opacification presently approach 100%. Special phenomena related to the small caliber of the needle include duct filling from "invisible" radicles, perivenous or periductal dissection of contrast, and pseudolesions in an incompletely decompressed stagnant bile column. The role of fine needle cholangiography in light of other present day technology for evaluating obstructive jaundice (ultrasonography, computed tomography, and endoscopic retrograde cholangiography) is discussed.
Computed tomographic (CT) images of in vitro hearts filled with iodinated contrast medium have delineated right and left ventricular cavities, papillary muscles, major trabeculae, pulmonary artery, and the aorta. Because of relatively good structural definition, this study was undertaken to determine the potential use of CT in the measurement of cardiac dimensions and cavity volumes. Ten isolated arrested canine hearts were filled with an iodinated oil-paraffin mixture and scanned transversely from base to apex. Measurements of the thickness of the interventricular septum and of the left ventricular posterior wall (indexes of cardiac hypertrophy) had a high degree of correlation to similar measurements of corresponding heart specimens. Using serial tomographic images, the cavity volumes of individual tomographic scans were totaled. The volume of each scan of given thickness was obtained either by the use of planimetry or from a numerical computer printout. Both the planimetric and computer methods gave right and left ventricular volumes which correlated well (P less than .05) with the volumes of paraffin casts. Unlike other techniques widely used for ventricular volume measurement, the method described does not depend on an assumption that the chamber resembles a specific geometric model. This method of volume measurement is applicable to both the left ventricle, regardless of its shape, and to the concave irregularly shaped right ventricle.
Hypotonic cholangiography was performed with intravenous glucagon in 12 patients who demonstrated complete nonspecific obstruction of the distal common bile duct during postoperative T-tube or transhepatic cholanglography. In 8 cases (67%), a diagnostic result was obtained. Abolition of smooth-muscle spasm at the choledochal sphincter by glucagon-induced hypotonia appears to be a useful adjunct to roentgenography of the bile ducts.
Transhepatic cholangiography performed with a newly introduced fine caliber (0.7 mm OD) "Chiba" needle produces a significantly higher success rate of biliary duct opacification with fewer complications than conventional needle or flexible cannula techniques. Distinct advantages over endoscopic retrograde cholangiography are also apparent, including more frequent bile duct opacification, ease of performance, and lower overall cost. In a group of 50 consecutive patients examined with the fine needle puncture technique, duct opacification was achieved in 92%, including 33 of 33 (100%) of patients with surgically obstructed ducts and 14 of 17 (82%) with normal caliber or narrowed ducts. Fine needle hepatic puncture is recommended as the preferred approach for direct biliary duct opacification in jaundiced patients.
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B-mode ultrasound examinations have been useful in demonstrating cholelithiasis and obstructive dilatation of the gallbladder. It is now possible with gray scale ultrasound technique to demonstrate dilatation of the common bile duct, as differentiated from the gallbladder, and also to show fluid containing spaces within the liver. Discrimination between solid and fluid filled intrahepatic structures is readily made, and dilated biliary radicles are frequently discernible.
A patient with a clinical and angiographic diagnosis of nonocclusive mesenteric ischemia had phenoxybenzamine directly infused into the superior mesenteric artery to counteract the existing splanchnic vasoconstriction. The diagnosis was confirmed by later operative intervention and the patient recovered. Vasodilatory drugs may play a significant role in the management of patients with nonocclusive mesenteric ischemia.
Four cases of ischemic colitis occurring at intervals from 3 months to 7 years after abdominoperineal resection are described. In 3 of the 4 cases patency of the direct arterial supply to the ischemic segment was documented. The lack of collateral circulation provided by the resected colon probably increases the risk of developing ischemic colitis in the remaining colon.
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