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Biomedical subjects

S B Gay

Publications and source records attributed to S B Gay.

47 records · Page 3Linked to original sources
PubMed1991

Magnetization prepared rapid gradient-echo (MP-RAGE) MR imaging of the liver: comparison with spin-echo imaging.

We have implemented an MR technique that employs a rapid gradient echo sequence, preceded by magnetization preparation pulses to provide T1- and T2-weighted tissue contrast. With this technique, which can be identified as a member of a new family of pulse sequences, generically named Magnetization Prepared RApid Gradient Echo (MP-RAGE), very short repetition times are used, allowing acquisition times of less than one second and images virtually free of motion-induced artifacts during quiet respiration. Fifteen patients with known liver lesions (metastases, hemangiomas, and cysts) were examined using T1- and T2-weighted 2-dimensional MP-RAGE sequences, and the images were compared with conventional T1- and multi-echo T2-weighted spin-echo (SE) sequences. Signal difference-to-noise ratios (SD/Ns) of the lesions were calculated for all pulse sequences using corresponding axial images and were normalized for voxel volume. The mean normalized SD/Ns of the MP-RAGE sequences were generally comparable to those for the SE sequences. In addition, there were no noticeable respiratory artifacts on the MP-RAGE images whereas these were clearly present on the T2-weighted SE images and to a lesser degree on the T1-weighted SE images. It is concluded that the MP-RAGE technique could become an important method for evaluating the liver for focal disease.

Cysts↗
PubMed1991

Left infrarenal region: anatomic variants, pathologic conditions, and diagnostic pitfalls.

Computed tomography (CT) is the preferred method for evaluating the left periaortic infrarenal region. Structures larger than 11 mm in cross-sectional diameter in this region are considered abnormal and should be evaluated for lymphadenopathy, hydroureter, or a vascular abnormality such as venous thrombosis or varicoceles. Normal structures include inferior mesenteric vessels, left gonadal vein and artery, and ureter. The diagnostic process may be complicated by variations in anatomy, including double inferior vena cava, left inferior vena cava, retroaortic left renal vein, circumaortic left renal vein, horseshoe kidney, crossed-fused renal ectopia, renal agenesis, and ureteral duplication. Familiarity with the anatomy of this region and awareness of normal variants are necessary to avoid errors in diagnosis. Radiologists should also be aware of problems in CT technique (nonopacified bowel, dynamic and unenhanced scanning) that can confuse the diagnosis.

Aneurysm↗
PubMed1991

Dynamic CT of the neck.

The authors describe a technique for dynamic incremental computed tomography (CT) of the neck with use of slow-power intravenous injection of contrast material. CT scans of the necks of 55 subjects were evaluated with this technique and were found to exhibit adequate opacification of the neck vessels. This method of contrast enhancement enables vessels to be confidently distinguished from enlarged lymph nodes or masses. It also provides information about the boundaries of masses, their vascularity, and their relationship to surrounding structures. In addition, the authors have optimized this technique by reducing contrast material volume while maintaining diagnostic quality.

Humans↗
PubMed1991

Extravasation of iopamidol and iohexol during contrast-enhanced CT: report of 28 cases.

Extravasation of intravenously injected contrast medium is a well-known complication of radiologic procedures. Records from a 27-month period were reviewed of 28 patients in whom extravasation of nonionic contrast medium occurred during computed tomographic (CT) scanning. Extravasated amounts ranged from 3 mL in an infant to 100 mL in an adult. There were seven documented major (50-100-mL) events and nine documented moderate (10-49-mL) events. Follow-up showed that none of these patients required medical or surgical intervention as a result of extravasation. The rate of extravasation during neurologic CT scanning (head, orbits, and spine) was 0.09%, while the rate for the rest of the body (chest, abdomen, pelvis, neck) was 0.17%; the overall rate was 0.14%. The higher rate for non-neurologic studies was related to the use of a power injector. Nonionic contrast medium seemed to cause fewer systemic reactions.

Extravasation of Diagnostic and Therapeutic Materi↗
PubMed1990

Autoradiology: patient heal thyself.

All in all, our program has been a great success, endorsed by everyone from patients to health care providers and hospital administrators. The PPP will revolutionize diagnostic and interventional radiologic procedures and will free the radiologist to perform more critical maneuvers--the out-of-department lunch, the extended afternoon off, and perfection of the golf swing.

Humans↗
PubMed1988

Pericardial cyst. A rare mass abutting the aorta.

Pericardial cysts are infrequently found. They are generally located in the cardiophrenic angle, dominantly on the right side. We present an example of a pericardial cyst in the anterior mediastinum abutting the ascending aorta.

Aged↗
PubMed1988

Chest CT of unresectable lung cancer.

A major role of CT in lung cancer patients is to spare those with unresectable lesions unnecessary surgery. Here the CT findings of inoperable lesions (Stages IIIB and IV in the new International Staging System) are illustrated.

Aged↗
PubMedDate not supplied

Gadolinium-enhanced MRI of tumors of the head and neck.

High-resolution computed tomographic (CT) scanning and, more recently, magnetic resonance imaging (MRI) have provided more accurate evaluation of the extent of head and neck neoplasms. With increasing experience, better methodology is being developed to improve imaging accuracy. We present a series of patients with clinically proven neoplasms of the oropharynx and larynx, evaluated by MR using T1-weighted, T2-weighted, and post-gadolinium (Gd)-DTPA T1-weighted imaged. The concept behind the use of Gd-DTPA was that it might permit the use of only pre- and postcontrast T1-weighted sequences, reducing examination time and increasing the sensitivity of the examination. It was also anticipated that Gd-DTPA could increase tumor conspicuity and edge definition. Imaging planes were chosen to best define the tumor extent and axial images were performed to evaluate adenopathy. The imaging results were compared with the clinical evaluation and with non-Gd-enhanced MRI. We present examples of the significantly improved soft tissue contrast with Gd-DTPA T1-weighted images and discuss the improved tumor margin definition with Gd-DTPA. Those cases in which it does not provide improved information will also be presented.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

"Segmental" prolonged cortical nephrogram as a result of radiation damage to the kidneys.

We present two cases showing bilateral segmental delayed nephrograms secondary to radiation injury which occurred during radiation therapy for retroperitoneal adenopathy. The abnormal areas in the affected kidneys were not devoid of a nephrogram, but rather showed a persistent corticomedullary separation indicative of slowed perfusion. Linear margins not conforming to the normal renal lobular configuration were a confirmatory feature. Radiation injury should be included in the differential of both the asymmetric prolonged nephrogram and the "segmental" nephrogram.

Adolescent↗
PubMedDate not supplied

Thoracic sonography for diagnosis and intervention.

Many physicians believe that ultrasound has limited usefulness in chest disease. Our clinical experiences and a review of the literature in preparation for this monograph have convinced us that sonography can be a very useful and versatile tool for thoracic diagnosis and intervention. Although there are some limitations caused by interposed ribs and air-containing lung, almost all of the compartments of the chest can be evaluated with ultrasound, which gives unique and clinically useful information. Ultrasound guidance for biopsy and drainage does take some time to learn, but we feel that the effort is very worthwhile. The same advantages ultrasound enjoys for other body regions make it a modality that will see increased use in the chest as well. We hope that this monograph will stimulate our colleagues to explore and expand upon the techniques described.

Humans↗