Biomedical subjects
Publications and source records attributed to S E Seltzer.
A technique is presented for rectal opacification by the administration of oral contrast medium given the night before a computed tomography scan. This has eliminated the need for enemas in most cases.
The contributions of computed tomographic (CT) images to the planning of medical and surgical treatment of osteomyelitis were assessed in seven patients. The scans helped medical therapy in two cases by guiding nonsurgical percutaneous biopsy of infected tissue, permitting prompt institution of proper antibiotics. The scans indicated the need for surgery and provided vital information on disease extent that helped plan the appropriate operation in five patients. Sequestra, medullary involvement, and the extent of sinus tracts that could not be seen on conventional imaging tests were detectable on CT. It is concluded that CT plays an important role in proper choices of both medical and surgical treatment in patients with osteomyelitis.
This investigation used computed tomography (CT) to study the normal anatomy of the hindfoot and to demonstrate abnormalities in patients with rheumatoid arthritis, pes planovalgus , old trauma, and soft-tissue masses. The hindfeet of 10 normal volunteers and 17 patients were scanned in the coronal and axial transverse planes. The articular surfaces of the tibia, talus, and calcaneus were assessed, as were the relationships of each bone to the others. Normal subjects had markedly symmetrical hindfeet . The "heel valgus angle" (relating the calcaneus to the tibia) was 5.2 +/- 1.6 degrees (mean +/- standard error of the mean). The "sustentacular angle" (indicating the angle of elevation of the sustentaculum tali at the midsubtalar joint) was 18.3 +/- 1.3 degrees. The "medial offset" of the talar head with respect to the calcaneus (measured at the anterior subtalar joint) averaged 5.2 +/- 1.8 mm. Patients with rheumatoid arthritis had erosions involving both sides of the subtalar joint, leading to talocalcaneal alignment abnormalities. In patients with pes planovalgus the heel valgus angle was greater and the elevation of sustentaculum tali lower in the foot that was most severely affected. Bony talocalcaneal fusions, fractures, and the erosions of pigmented villonodular synovitis were detected on CT. The pattern of postoperative bone healing after attempted subtalar fusion could be demonstrated. We conclude that CT is a useful tool for pre- and postoperative evaluation of the hindfoot.
In carefully selected diagnostic problem cases prenatal CT of the fetus was performed. In three of five cases anatomic or physiologic information was obtained that proved useful in the management of the pregnancy.
The authors performed direct sagittal computed tomography (CT) on 4 cadaver temporomandibular joints (TMJ) and examined 51 TMJs in 47 patients clinically. The results were correlated with cadaver anatomical sections and clinical arthrographic findings. A fat plane between the bellies of the lateral pterygoid muscles, termed the "lateral pterygoid fat pad," served as the anatomical basis for detection of internal derangements by CT. CT was 94% accurate in detecting meniscal derangements and 96% accurate in detecting degenerative arthritis. The authors suggest that CT rather than arthrography be employed as the primary TMJ imaging modality when internal derangement or arthritis is suspected.
The computed tomographic (CT) appearance of splenic infarction has classically been described as peripheral, wedge-shaped, and low in density. Two investigations were designed to determine the appearance of splenic infarcts: (a) a clinical study of 12 patients and (b) a canine experimental model. In the clinical study, two previously undescribed patterns of splenic infarction were found. The classic peripheral, wedge-shaped defects were seen in four patients; multiple, heterogeneous lesions were seen in five; and massive hypodense lesions were noted in three. In three of the nine patients who had both precontrast and postcontrast CT scans, the unenhanced images alone would not have permitted the diagnosis. Contrast enhancement markedly improved infarct visualization in the remaining six. The experimental study of splenic infarction in dogs indicated that CT images can accurately depict the various phases of an infarct as it evolves through stages of congestion, hemorrhage, inflammation, organization, and fibrosis. In addition, a new contrast material--liposome-encapsulated diatrizoate--was used in one of the dogs and was found to produce greater and more sustained differences between normal and abnormal tissue than did conventional contrast material.
Losefamate, a hepatobiliary contrast agent, was encapsulated into liposomes to increase its ability to opacify the liver and spleen on computed tomographic (CT) images. Multilamellar lipid vesicles (lecithin, cholesterol, and stearylamine, in 4:1:1 molar ratio) containing iosefamate in their aqueous phase were prepared. Seven dogs received intravenous injections of 100-300 mg I/kg in one of three forms: encapsulated, unencapsulated, or a mixture of the two in equal parts. Animals that received the opaque vesicles had marked opacification of their livers, bile ducts, gallbladders, spleens (maximum 106 H enhancement), and gastrointestinal tracts. Spleen CT values (an indicator of encapsulated material uptake) were always higher in these dogs than in the animals receiving equivalent amounts of unencapsulated iosefamate alone. At the high-dose level, liver uptake of the encapsulated materials was also greater. Liposome-encapsulated hepatobiliary contrast agents are effective liver and spleen opacifiers for CT imaging in the dog.
Mediastinal lesions containing three types of fluid levels were studied by computed tomography. Air-fluid, fat-fluid, and fluid-fluid levels were easily recognized and were caused by a colonic interposition, a cystic teratoma, and a hematoma, respectively. Computed tomography can be useful for detection and precise diagnosis of mediastinal lesions that contain fluid levels.
We tabulated the computed tomographic (CT) findings in 14 consecutive patients who had proven malignant pleural mesotheliomas and were studied over a 3-year period. We also staged the disease in these patients, all of whom were men, aged 40-75 years (mean, 59), and had been exposed to asbestos at work. Common presenting symptoms were shortness of breath or chest pain. Pleural thickening was found on the side of the tumor in all of the patients, characterized as nodular and circumferential (6/14 cases), plaque-like (4/14), or strictly nodular (4/14) in appearance. In addition, 86% of the patients demonstrated contralateral pleural thickening, but these lesions did not prove to be tumor deposits. Other common CT findings in the involved hemithorax included: pleural effusions (79% of cases), lung parenchymal disease (79%), decreased hemithorax size (62%), and pleural calcification (50%). Before the chest scans were performed, 13 patients were felt to have Stage I disease and one to have Stage IV. The CT information revised these opinions: four of the Stage I patients were assigned to Stage II (on the basis of chest wall involvement or enlarged hilar/mediastinal lymph nodes). Therapy was altered in these four cases. In two patients pericardial thickening was seen, but it was not possible to determine if this was due to tumor involvement. We conclude that CT can identify several abnormalities that are commonly associated with mesotheliomas. By demonstrating lesions not detectable on conventional imaging studies, CT may alter staging and therapy in many patients with this disease.
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The initial clinical presentation of intraabdominal disease can be in an extraabdominal location. This phenomenon most commonly occurs in the setting of bowel perforation secondary to diverticulitis, appendicitis, or carcinoma, with resultant spread of infection caudal to the abdomen. Hematomas and pancreatic fluid collections may also dissect out of the abdomen. The spread of these disease processes is likely to occur in a predictable fashion along anatomic tissue planes. Computed tomography (CT) is well suited to demonstrate the extraabdominal site of disease, the pathway of spread from the abdomen, and the occult intraabdominal process. We describe four such cases in which CT was useful and discuss the anatomic pathways involved.
We used a stepwise approach to identify, design, synthesize, and test new high atomic number particulate contrast agents that would be especially well suited for use with computed tomography (CT). Our goal was to produce extremely radiopaque compounds with highly selective biodistribution to the normal liver. In this way, dose requirements could be lessened and toxicity minimized. Suspensions of cerium, gadolinium, and dysprosium oxide particles and silver iodide colloid were tested and compared with standard agents. All four experimental agents were selectively concentrated in the reticuloendothelial systems of rats and rabbits. These compounds produced greater and longer opacification of normal livers and larger liver-to-tumor differences in rabbits with hepatic tumors than did equivalent amounts of standard, iodinated agents. Lesions as small as 5 mm were visible with CT. These experimental materials have favorable characteristics as hepatic contrast agents, but their toxicity and long term retention may limit clinical use.
Radiopaque, positively charged liposomes were made from lecithin, cholesterol, and stearylamine and carried diatrizoic acid salts (Renografin). Following intravenous administration of radiopaque liposomes in rats and rabbits, the spleen had the highest iodine concentration and was opacified on CT images. Contrast concentrations peaked at 30 minutes and gradually declined over a period of 24 hours. At 30 minutes, spleen CT values in rats had increased by 2.9 HU for each milligram of injected iodine (4 mg I/kg); maximum values were more than 6 times those obtained with an equivalent amount of Renografin alone. Peak spleen CT numbers of over 100 HU were consistently achieved following injections of 133 mg I/kg of opaque liposomes in rats. No acute toxicity was observed. These new contrast agents seem promising for CT of the spleen.
In this department 22% of examinations are interpreted independently by residents outside of normal hours. Staff radiologists review these studies in a process designed to train residents and assure appropriate radiologic consultation. The resident's written reports on 2,619 examinations were analyzed before and after staff review. Each film review session lasted an average of 1.1 hr. Potential changes were discussed in 9.1% of cases and mandated in 6.3%. About two-thirds of corrections were important enough to influence patient care. Correction rates declined significantly between the first and second/third years of residency; the proportion of clinically important changes also decreased. Omissions (false-negatives) were much more common than overcalls (false-positives). Residents correctly interpreted 89% of abnormal films and 96% of normal radiographs. Staff review resulted in a net improvement in interpretation of 4% of cases initially read by first-year residents and 2% by second- and third-year. The film review process provides opportunities for close resident-staff interaction and teaching and also ensures appropriate final reports.
The plain radiographic findings on 20 patients with traumatic aortic rupture were analyzed. A mediastinal-width to chest-width (M/C) ratio was calculated at three thoracic levels and compared to two matched groups of patients without aortic tears. Defining an M/C ratio of 0.25 or larger at the level of the aortic arch as abnormal would identify 95% of cases with ruptured aortas, and result in 25% false-positive studies in traumatized patients. A ratio greater than 0.28 retains 85% sensitivity for aortic rupture while increasing specificity to 100%. An analysis of the prevalence and location of rib fractures showed that there was little relation between the presence of fracture and existence of an aortic tear. Therefore, an acutely injured patient with an M/C ratio of greater than 0.25 should be considered highly likely to have an aortic rupture.