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Biomedical subjects

D R Enzmann

Publications and source records attributed to D R Enzmann.

At least 91 records · Page 5Linked to original sources
PubMed1984

DSA evaluation of the STA-MCA bypass.

Continuing improvements in intravenous DSA techniques have now shown it to be useful in the angiographic evaluation of STA-MCA bypass function. Both patent and non-patent bypasses were observed in this study. Diagnostically adequate spatial resolution and signal to noise ratio were achieved by electronic magnification and integration techniques. Patient positioning was important and the projection which gave optimal visualization of the STA-MCA bypass, free of vessel overlap, was a 40 degrees oblique, 20 degrees craniocaudal view on the side of interest. Intravenous DSA can complement, and in some cases may supplant, conventional arteriography in the radiologic evaluation of STA-MCA bypass surgery.

Cerebral Angiography↗
PubMed1984

A high frame-rate digital subtraction angiography imaging technique for evaluation of aortofemoral runoff.

Intravenous digital subtraction angiography was used to obtain a complete aortofemoral runoff examination of high diagnostic quality in a single patient session in eight patients. Using a 9-inch (22.9-cm) image intensifier, oblique and posteroanterior projections were obtained from the level of the aortic bifurcation to the tibial artery trifurcation. This technique is based upon the administration of one-half of the usual dose of contrast agent combined with a high frame-rate imaging technique and postacquisition integration to increase the signal-to-noise ratio. It is easily performed on an outpatient basis, lowers patient risk, and allows a significant savings of time, film, and cost compared with the conventional intra-arterial aortofemoral runoff examination.

Aortography↗
PubMed1984

Experimental anaerobic brain abscess. Computerized tomographic and neuropathological correlations.

The neuropathological progression of brain abscess formation induced by a mixed anaerobic culture of Bacteroides fragilis and Staphylococcus epidermidis was studied experimentally in dogs. Histological findings were correlated with computerized tomographic (CT) brain scans. The evolution of brain abscess formation could be divided into three stages based on histological criteria: early cerebritis (Days 1 to 3); late cerebritis (Days 4 to 9); and capsule formation (Day 10 and later). Capsule formation could not be divided into early and late stages because encapsulation was delayed compared with a previously reported model of alpha-Streptococcus brain abscess. Histologically, there was evidence for a very virulent infection. Leptomeningitis was significant even in the late stages. Early ventricular rupture occurred in 25% of the animals. A pattern of extensive purulent encephalitis was seen in 25% of the animals. In the early cerebritis stage, blood vessels near the necrotic center were engorged and were surrounded by hemorrhage and/or protein-rich fluid. Cerebral edema was extensive. Although fibroblasts appeared in late cerebritis, there was marked delay of capsule formation. Three-week-old lesions still had areas of incomplete capsule formation and foci of uncontrolled infection. In the cerebritis stages, CT scans showed an area of ring enhancement which was incomplete on early scans (at 5 minutes after injection of contrast material) but partially filled in and thickened on delayed scans (at 20 to 45 minutes). On even later delayed scans there was no decrease in intensity of ring enhancement. Lesions in which capsule formation occurred also showed ring enhancement, but delayed scans showed a decrease in the intensity of enhancement. The lesions that ruptured into the ventricular system showed atypical CT findings, with either lack of contrast enhancement (histologically there was minimal cerebritis adjacent to the abscess cavity) or a marked delay in contrast enhancement (cerebritis was more extensive and corresponded to the width of ring of enhancement). This study suggests that Bacteroides fragilis is a virulent organism in the brain. The developing abscesses enlarged quickly, were prone to early ventricular rupture, and showed incomplete and delayed encapsulation.

Animals↗
PubMed1983

CT characteristics of the normal pituitary gland.

Fifty-three patients undergoing orbital computed tomographic (CT) scanning for symptoms and signs unrelated to the pituitary gland had coronal and sagittal reformations of contiguous 1.5 mm slices through the sella. Mean male gland height was 4.1 +/- 1.1 mm, mean female gland height was 4.4 +/- 1.4 mm; no statistically significant differences with age were identified. Pituitary glands were homogeneous in 58% and inhomogeneous in 42% of patients; 91.5% had flat or concave superior surfaces. Coronal and saggital CT reformations are felt to be important in the evaluation of the pituitary gland.

Adult↗
PubMed1983

The application of matched filtering to x-ray exposure reduction in digital subtraction angiography: clinical results.

This new digital fluorography processing method of matched filtering generates a set of images that have been acquired at continuous video-frame rates (30 per second) over the temporal extent of the bolus (10 seconds), and it combines them to produce the equivalent of a single digital subtraction angiography (DSA) image. Because of the extensive temporal averaging used, the method can provide substantial x-ray exposure reduction per run as compared with conventional techniques for an equivalent signal-to-noise ratio in the final image. The matched filtering technique was compared with conventional pulsed (one per second) DSA images of both extracranial and intracranial arteries, and the results are presented. Matched filtered images provided image quality that was equivalent to that of conventional DSA images at about one-fourth the patient exposure per run for both carotid artery and cerebral vessel studies. Despite long integration times, patient motion irretrievably corrupted image quality in only two of five carotid artery studies and in none of three intracranial studies. Compensation for patient motion is demonstrated, and additional applications and limitations of the technique are discussed.

Angiography↗
PubMed1983

Low-dose, high-frame-rate versus regular-dose, low-frame-rate digital subtraction angiography.

Using intravenous digital subtraction angiography for carotid, cerebral, and renal arteries, a comparison was made between a single pulsed image and an integrated image composed of several pulsed images. The single image was generated with a conventional detected dose per frame while the frames composing the integrated image were generated at a lower dose per frame but at a higher frame rate. Comparisons were made for an equivalent detected dose per image. For relatively stationary arteries, the integrated images were equivalent or superior to the single images. When patient motion was present, or if pulsatile vessel motion was significant, the single image was better than the integrated image. A low-dose, high-frame-rate technique has the potential for furnishing physiologic data in addition to high-quality morphologic information.

Angiography↗
PubMed1983

Staging of human brain abscess by computed tomography.

Precontrast and postcontrast computed tomographic (CT) scans of patients with brain abscesses were quantitatively studied to determine if the degree of encapsulation could be predicted. The findings in these cases correlated closely to the CT criteria for encapsulation previously established in an experimental model. Time-density curves of serial delayed postcontrast CT scans and the precontrast CT appearance yielded accurate criteria for determining the degree of encapsulation. The effect of corticosteroid treatment on contrast enhancement of brain abscess was also studied in one patient.

Brain Abscess↗
PubMed1983

Evaluation of peripheral vascular disease using digital subtraction angiography.

Intravenous digital subtraction angiography (DSA) facilitates imaging of peripheral arteries and bypass grafts on an outpatient basis. Forty-five patients underwent intravenous peripheral angiography, 16 following placement of bypass grafts. Complex oblique and sagittal angulations optimize visualization of bifurcations and overlapping vascular structures. Reprocessing techniques using integrated masks and contrast images allow for diagnostic delineation of fine vascular detail. This is a practical, noninvasive, well tolerated method for both diagnostic screening and follow-up evaluation of patients with peripheral vascular disease.

Angiography↗
PubMed1983

Digital subtraction laryngography.

Digital subtraction laryngography was used to evaluate laryngeal function in 8 patients: 4 with normal larynxes and 4 with laryngeal disease. Subtracted digital images provided a dynamic display of the extent and symmetry of vocal cord excursions and pyriform sinus inflation, and the vocal cord resting position was also clearly depicted. The technical details of digital subtraction laryngography and its application are described.

Humans↗
PubMed1983

The application of matched filtering to contrast material dose reduction in digital subtraction angiography.

Temporal filtering methods were applied to a 50% reduction of contrast material dose in intravenous digital subtraction angiography (DSA). The performance of matched filtering was reviewed, indicating a 50% reduction of noise through the integration of an entire (greater than 10 sec) DSA image sequence spanning the contrast material bolus arrival and washout. Used in conjunction with 50% contrast material dose reduction, matched filtering could provide final iodine signal-to-noise ratios (SNR) comparable to those of conventional DSA. Half-contrast-material-dose (20 ml) filtered DSA runs were compared with full-contrast-material-dose (40 ml) unfiltered runs for 5 carotid, 2 cerebral, and 4 peripheral studies. In all but 2 studies, the half-contrast-material-dose runs were judged to be diagnostic. In all 4 peripheral studies and in some of the 7 carotid and cerebral studies the 20-ml results were judged to be equivalent to the 40-ml results. It is concluded that the half-contrast-material-dose temporally filtered approach is appropriate for peripheral runoff studies. Matched filtering was experimentally compared with simple integrated remasking. If the identical image sequence was used for each, the two had virtually identical performance for integration times less than 10 sec, consistent with theoretical predictions. Two other applications of matched filtering, SNR enhancement and x-ray exposure reduction, are discussed schematically.

Angiography↗
PubMed1983

Work in progress: the application of temporal filtering techniques to hybrid subtraction in digital subtraction angiography.

Temporal filtering methods were applied to iodine signal-to-noise ratio (SNR) restoration in intravenous hybrid subtraction digital subtraction angiography (DSA). For equal detected exposure rates hybrid subtraction had approximately 35% of the SNR of temporal subtraction. When matched filtering was applied to a DSA run, the filtered result had approximately two times higher SNR than the peak contrast image in the run. Thus, when matched filtering techniques were applied to the hybrid image sequence, the resultant SNR increased to about 70% of that of temporal subtraction. With an additional factor-of-two increase in exposure rate for the hybrid run, SNR parity with temporal subtraction could be achieved. This compared with a factor-of-nine increase in exposure that would be required if no filtering were performed. Experimental hybrid matched filter results, generated with intravenous canine DSA studies, supported the predictions in SNR performance.

Angiography↗
PubMed1983

Brain nuclear magnetic resonance imaging enhanced by a paramagnetic nitroxide contrast agent: preliminary report.

Contrast-enhancing agents for demonstrating abnormalities of the blood-brain barrier may extend the diagnostic utility of proton nuclear magnetic resonance (NMR) imaging. "TES," a nitroxide stable free radical derivative, was tested as a central nervous system contrast enhancer in dogs with experimentally induced unilateral cerebritis or radiation cerebral damage. After intravenous injection of TES, the normal brain showed no change in NMR appearance, but areas of disease demonstrated a dramatic increase (up to 45%) in spin-echo intensity and a decrease in T1 relaxation times. The areas of disease defined by TES enhancement were either not evident on the nonenhanced NMR images or were better defined after contrast administration. In-depth tests of toxicity, stability, and metabolism of this promising NMR contrast agent are now in progress.

Animals↗
PubMed1983

Fusarium brain abscess. Case report.

The common soil fungus, Fusarium, is rarely pathogenic in man but occasionally causes serious disease, particularly in immunocompromised hosts. A case is reported of Fusarium brain abscess and meningitis occurring in a patient with chronic infectious mononucleosis syndrome and immunodeficiency. The patient died despite aspiration of the abscess and treatment with amphotericin B. This case demonstrates the importance of identifying the offending pathological organism through abscess aspiration in immunocompromised patients.

Adolescent↗
PubMed1983

Clinical stages of human brain abscesses on serial CT scans after contrast infusion. Computerized tomographic, neuropathological, and clinical correlations.

The authors describe a classification of human brain abscesses into stages of development as demonstrated on computerized tomography (CT) scans. The results of CT staging of 14 human brain abscesses are compared with the previously published findings in an experimental brain abscess model developed by the same authors. The CT criteria for categorizing brain abscesses into cerebritis and capsule stages were based on the pattern of contrast enhancement and the time-density curve of enhancement obtained from sequential CT scans after contrast infusion. Using these CT criteria, it was possible to accurately categorize all 14 brain abscesses into cerebritis and capsule stages. Histological examination of surgical and autopsy specimens provided immediate confirmation of the abscess stage in six patients. Indirect staging, based on surgical findings and/or subsequent autopsy findings, was possible in eight patients. Corticosteroid administration greatly reduced contrast enhancement in the cerebritis stage, but had little effect in the capsule stage. A systematic approach utilizing CT for establishing the diagnosis, staging, and treatment planning of brain abscess is proposed.

Adolescent↗
PubMed1982

Intravenous arteriography using digital subtraction techniques.

The application of digital computers to electronic x-ray imaging devices has rejuvenated interest in the field of intravenous arteriography. By utilizing computer image subtraction techniques, digital roentgenographic systems based on fluoroscopy or computed tomography (scanned projection radiography) provide significantly improved vascular imaging compared with conventional film subtraction methods. Digital subtraction angiography schemes isolate contrast media in the vessel by detecting differences in images obtained before and after the injection of contrast medium or changes in the relative attenuation of contrast media at different x-ray energies. Present applications include carotid and peripheral arteriography, thoracic and abdominal aortography, pulmonary arteriography, and ventriculography. Future applications may include intracerebral and coronary arteriography. These systems should provide low-risk outpatient screening arteriography.

Angiography↗
PubMed1982

Intracranial intravenous digital subtraction angiography.

Intravenous digital subtraction angiography (iDSA) promises to significantly alter the use of conventional cerebral angiography in the workup of neurological patients. Understanding its diagnostic potential and its limitations are important in incorporating this new examination into the diagnostic thought process of neuroradiologic tests. Different image processing techniques such as integration of mask and contrast images promise to improve image quality for neuroradiologic application. At present, iDSA is suitable for the diagnosis and follow-up of vascular lesions (atherosclerosis, aneurysms, arteriovenous malformations, venous sinus occlusion), and tumor (meningioma). Although limited, the spatial resolution of iDSA studies is capable of demonstrating diffuse vascular disease such as arteritis and vasospasm after subarachnoid hemorrhage. In some patients in conjunction with the CT scan, iDSA may prove sufficient as the primary and only diagnostic angiographic test necessary, supplanting conventional angiography.

Arteriosclerosis↗