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Biomedical subjects

D D Blatter

Publications and source records attributed to D D Blatter.

At least 37 records · Page 2Linked to original sources
PubMed1995

Trauma-induced degenerative changes in brain injury: a morphometric analysis of three patients with preinjury and postinjury MR scans.

Three patients with pretraumatic and posttraumatic brain injury (TBI) MR imaging of the brain are presented. Two patients had moderate to severe injury, whereas the third patient sustained a mild injury. Using imaging software to conduct morphometric analyses, quantitative neuropathologic change was ascertained in each TBI patient. Each case was compared quantitatively to preinjury scans as well as to an age-matched control group. For the moderately to severely injured patients, extensive degenerative changes were found throughout the various cortical structures and the cerebellum, whereas most midbrain and brainstem measures did not demonstrate significant change. For these two patients, the most significant changes occurred within the ventricular system, where generalized ventricular dilation was observed post-TBI. In the mild case, no significant anatomic changes were evident. These case studies demonstrate the use of quantitative methods for examining the structural basis of TBI sequelae.

Adult↗
PubMed1995

Candidal brain abscess associated with vascular invasion: a devastating complication of vascular catheter-related candidemia.

We describe a patient who developed Candida albicans brain abscess associated with prominent vascular invasion following an episode of central venous catheter-related fungemia. The increasing population of immunosuppressed patients and the frequent use of broad-spectrum antimicrobials, corticosteroids, chemotherapeutics, organ transplantation, and prolonged supportive measures are responsible for an increasing incidence of candidal infections. Brain abscess is a rare complication of candidemia but may be expected to become more common as venous catheter-related fungemia is encountered more frequently.

Amphotericin B↗
PubMed1995

Quantitative volumetric analysis of brain MR: normative database spanning 5 decades of life.

PURPOSE: To present a normative volumetric database, spanning 5 decades of life, of cerebrospinal fluid, subarachnoid cerebrospinal fluid, total brain volume, total ventricular volume (component ventricular volumes of lateral, temporal horn, and third and fourth ventricles) and estimates of white and gray matter, based on a multispectral segmentation of brain MR. This database is presented as a reference for future studies comparing pathologic states. METHOD: One hundred ninety-four healthy subjects, ranging in age from 16 to 65 years, received standard axial intermediate- and T2-weighted spin-echo MR images. Multispectral segmentation and volume analysis were performed using ANALYZE. RESULTS: Normative volumetric estimates, both uncorrected and corrected for differences in total intracranial volume, were obtained for all subjects and presented by decade and sex. Age-related cerebrospinal fluid changes were evident for both male and female subjects. Most gender differences were eliminated by correction for differences in total intracranial volume. Standard and fast spin-echo acquisition methods gave comparable volume estimates. Total brain volume measurements from MR compare favorably with data from large autopsy series. CONCLUSION: Although there may be limitations to generalizations, these normative data tables can provide a comparison index for contrasting pathologic groups with a normative sample.

Adolescent↗
PubMed1994

Corpus callosum surface area across the human adult life span: effect of age and gender.

This magnetic resonance (MR) imaging study analyzed and provides normative data on the midsagittal surface area of the corpus callosum (CC) across the human adult life span in 200 normal volunteers. Using MR imaging scans, CC midsagittal surface area was quantified, along with midsagittal intracranial surface area and total intracranial volume (measures of cranial size). Results demonstrate that when head size is controlled, no major changes associated with normal aging are evident in the CC during the more active years of adult life span (up through 65). Overall, females had significantly larger CC relative to total intracranial volume. Results are discussed in terms of potential gender differences in CC size and the clinical application of this normative data.

Adolescent↗
PubMed1994

Intracranial MR angiography: comparison of single-volume three-dimensional time-of-flight and multiple overlapping thin slab acquisition techniques.

OBJECTIVE: Time-of-flight (TOF) MR angiography has continued to evolve during the past few years. Signal loss due to flow saturation is a major problem of single-volume (slab) three-dimensional (3D) TOF technique. A multislab 3D TOF method, multiple overlapping thin slab acquisition (MOTSA), shows decreased sensitivity to the effects of flow saturation and therefore should result in better images. SUBJECTS AND METHODS: To evaluate the difference between MOTSA and the traditional single-volume 3D TOF techniques, we performed sequential, location-matched studies in 17 prospectively chosen patients with intracranial vascular abnormalities. All MOTSA and 3D TOF images were obtained after cut-film or 1024 digital angiography. RESULTS: According to specific criteria, abnormalities were better visualized with the MOTSA technique than with the single-volume 3D TOF technique. The difference was most marked in patients with more complex vascular abnormalities. CONCLUSION: We conclude that MOTSA is better than single-volume 3D TOF for showing intracranial abnormalities. The major advantage of MOTSA is decreased sensitivity to flow saturation.

Brain↗
PubMed1994

MR imaging and MR angiography in the evaluation of pulsatile tinnitus.

PURPOSE: 1) To evaluate the scope of imaging findings seen with spin-echo MR and MR angiography (MRA) in patients with pulsatile tinnitus; 2) to determine whether MRA adds additional imaging information (to that provided by spin-echo MR) necessary for determining the cause of pulsatile tinnitus; and 3) to suggest MR and MRA imaging techniques for evaluation of patients with pulsatile tinnitus. METHODS: Forty-nine patients with pulsatile tinnitus were evaluated with MR and MRA. Seventeen of these patients had conventional angiography. RESULTS: Vascular lesions or paraganglioma were demonstrated in 28 patients. Of these 28 lesions, the majority were seen best (46%) or only (36%) on MRA. The spectrum of lesions detected included dural arteriovenous fistula (nine), extracranial arteriovenous fistula (three), paraganglioma (five), jugular bulb variants (three), aberrant internal carotid artery (one), internal carotid artery stenosis (one), tortuous internal carotid artery (one), carotid dissection with pseudoaneurysm (one), stenosis of the transverse sinus (two), and arteriovenous malformation (two). CONCLUSIONS: MRA, in conjunction with spin-echo imaging, markedly enhances the ability of MR to diagnose the lesions responsible for pulsatile tinnitus.

Adolescent↗
PubMed1993

Contrast-to-noise-ratio measurements in three-dimensional magnetic resonance angiography.

RATIONALE AND OBJECTIVES: The authors report on the development and preliminary validation of a technique for measuring contrast-to-noise ratio (CNR) at all points along selected vessel segments in the original three-dimensional magnetic resonance angiography (MRA) dataset. METHODS: Contrast-to-noise ratio dependencies on flow rate, field of view, and flip angle were measured on images from a conventional time-of-flight MRA pulse sequence using constant flow in a branching vascular phantom. An estimate of the inherent variability of the technique was obtained from multiple scans of a flow phantom and a human volunteer. RESULTS: The overall standard deviation (SD) of the CNR was found to be approximately 6.1% of the average CNR value for the flow phantom study and 7.3% for the human study. Vessel CNR was found to increase with field of view and was found to become nonuniform for low flow rate and/or high flip angles. CONCLUSION: In general, such CNR measurements allow the investigation of the mechanism of signal loss and general technique optimization in MRA.

Blood Vessels↗
PubMed1993

Cervical carotid MR angiography with multiple overlapping thin-slab acquisition: comparison with conventional angiography.

OBJECTIVE: Multiple overlapping thin-slab acquisition (MOTSA) is a hybrid time-of-flight MR angiography technique that combines the advantages of two- and three-dimensional methods. A venetian blind-like artifact, resulting from variations in signal intensity at slab boundaries, is a potentially significant disadvantage. The objective of this study was to determine the accuracy of MOTSA MR angiography for the measurement of stenosis and to evaluate the effectiveness of modifications to reduce the venetian blind artifact. SUBJECTS AND METHODS: Fifty-one consecutive patients undergoing conventional and MR angiography of the carotid arteries for suspected atherosclerotic disease were studied. Methods established in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) were used to measure stenosis. Measurements from the conventional angiograms were compared with those from the MR angiograms. Modifications of the MR angiographic technique that were instituted after the initial 26 patients to reduce the venetian blind artifact included new acquisition parameters and the use of a postprocessing algorithm. RESULTS: After modification, highly significant improvements in Spearman ranked correlation coefficients were observed for MR angiography interobserver comparison (.573 to .974, p < .001) and comparison of conventional and MR angiography (.774 to .949, p < .001). A corresponding reduction was observed in the standard deviation of the difference measurement for percent stenosis for both interobserver (34.5% to 11.7%, p < .001) and intertechnique (22.6% to 12.6%, p < .001) comparisons. In the postmodification group, the interobserver correlation coefficients for conventional and MR angiography were not significantly different (.969 vs .974). The areas under the receiver-operating-characteristic curves used to predict surgically significant disease for the premodification and postmodification groups were 0.79 and 0.98, respectively, for observer A and 0.85 and 0.95, respectively, for observer B. CONCLUSION: Improved acquisition parameters and postprocessing significantly reduce the severity of the venetian blind artifact and increase the accuracy of MOTSA MR angiography in the measurement of percent stenosis. With these improvements, MOTSA MR angiography shows promise for noninvasive evaluation of stenosis of the carotid arteries.

Artifacts↗
PubMed1992

Cerebral MR angiography with multiple overlapping thin slab acquisition. Part II. Early clinical experience.

In a prospective, multicenter study of 164 patients, cerebral magnetic resonance (MR) angiography with multiple overlapping thin slab acquisition was evaluated for image quality and diagnostic accuracy. Of the 164 patients, 87 (53%) underwent either correlative cut-film angiography or surgery. The overall image quality was excellent in 90% of patient studies. Eighteen of 19 aneurysms were detected with MR angiography. The parent artery, the anatomy of the neck and dome, and the size were correctly shown in 17 of the 19 aneurysms. All 19 vascular malformations were seen with MR angiography. Venous malformations and single pedicle arteriovenous malformations were completely defined with MR angiography, while complete definition of complex arteriovenous malformations was frequently difficult. In cerebral tumors, the arteries and veins important in surgical planning were accurately shown in all cases. In ischemic cerebrovascular disease, MR angiography depicted all stenoses and occlusions of first- and second-order cerebral arteries. The inability to depict intraluminal filling defects in any but the large central arteries limited the ability of MR angiography to enable the specific diagnosis of embolic stroke.

Brain Ischemia↗
PubMed1991

MR angiography by multiple thin slab 3D acquisition.

Multiple overlapping thin 3D slab acquisition is presented as a magnitude contrast (time of flight) technique which combines advantages from multiple thin slice 2D and direct 3D volume acquisitions to obtain high-resolution cross-sectional images of vessel detail. Details of implementation and example images are presented.

Blood↗
PubMed1991

Hybrid MR angiography and Fourier velocity imaging using two echo 3D acquisition.

Fourier velocity imaging can be accomplished without cardiac gating from the second echo of a standard 3D MR angiography sequence. The stepped bipolar velocity encoding gradient is obtained by adding a gradient pulse opposite in area to the spatial phase encoding gradient. In this technique, Fourier images of three spatial coordinates are obtained from the first echo and images of two spatial coordinates and one velocity component are obtained from the second echo.

Blood Flow Velocity↗
PubMed1991

Cerebral MR angiography with multiple overlapping thin slab acquisition. Part I. Quantitative analysis of vessel visibility.

Multiple overlapping thin slab acquisition (MOTSA) is a novel time-of-flight magnetic resonance (MR) angiography technique that combines many of the advantages of multiple-section two-dimensional and direct three-dimensional volume methods. To rigorously evaluate the vascular detail that can be obtained with MOTSA MR angiography, the authors have quantified the frequency of visibility of intracranial arterial segments and have correlated their visibility with vessel size as measured at cut-film angiography and with the position and orientation of the arterial segment. Intracranial arterial segments at least 0.9 mm in diameter (the voxel dimension used in the current application) are consistently visualized with the MOTSA technique. The fraction of small vessels visualized is improved when voxel dimensions are reduced. Visibility is noticeably better in the primary images compared with the maximum-intensity-projection (MIP) images. Top-of-slab saturation and resulting decreased vessel intensity occurred infrequently and did not result in marked image degradation in the axial images.

Adult↗
PubMed1990

Nuclear magnetic resonance of hepatic graft-versus-host disease in mice.

The liver is a major target organ of graft-versus-host disease. We have induced graded intensities of acute GVHD to minor histocompatibility antigens in a well-characterized murine bone marrow transplant model and analyzed hepatic pathology one month after BMT. Nuclear-magnetic-resonance relaxation times and proton spectra were compared to systemic clinical disease, serum biochemistries, and histologic findings. T2 relaxation times correlated directly with the intensity of histologic abnormalities, but the hepatic histology remained mild even in animals with moderate GVHD. In contrast, NMR proton spectra of hepatic tissue showed large decreases in metabolite levels (acetate and glycogen) in animals with moderate systemic disease despite mild hepatic histology. We conclude that NMR of the liver can be used to differentiate hepatic from systemic GVHD in this model and may help to elucidate the differential effects of GVHD in various target organs.

Animals↗
PubMed1987

Phosphorus-31 magnetic resonance spectroscopy of experimentally induced arthritis in rats.

Phosphorus-31 magnetic resonance spectroscopy (MRS) of the hind paws of rats was performed at 1.5 Tesla before and during the course of an experimentally-induced inflammatory arthritis. Arthritis was induced by daily subcutaneous administration of 6-sulfanilamidoindazole, an antibacterial sulfa known to produce an acute, self-limited arthritis and periarthritis in the hind paws of rats. Phosphorus-31 spectra obtained after the development of clinical arthritis showed a significant (p less than 0.01) increase in the intensity of a group of resonances occurring downfield from phosphocreatine as compared to spectra obtained before treatment. In all rats, this increase correlated well with histological evidence of inflammation as well as with the degree of inflammation judged clinically (r = 0.89, p less than 0.001), and was present before roentgenographic evidence of bony involvement. The use of 31P MRS may permit evaluation of the severity of an inflammatory arthritis with greater accuracy than the bony changes definable by plain roentgenograms.

Animals↗
PubMed1985

Asymmetric spin echo sequences. A simple new method for obtaining NMR 1H spectral images.

The nuclear magnetic resonance (NMR) signal decay produced by reversible tissue-induced dephasing of the magnetization components in the transverse plane (reversible tissue-induced dephasing) was measured and expressed as a function of a new transverse relaxation time T'2 (T2 prime) for samples of rat liver, retroperitoneal fat, inflated lung, and corn oil. Simple exponentials did not adequately describe the observed NMR signal decay. Inflated lung demonstrated the most rapid signal decay (T'2 = 4.8 ms) followed by retroperitoneal fat (T'2 = 16 ms). No reversible tissue-induced dephasing was observed in liver (T'2 immeasurably long). In tissues which contain both fat and water, the chemically shifted 1H resonance peaks from -OH and -CH-are in phase with symmetric spin echo sequences but out of phase with asymmetric sequences. The interference of these two peaks produces a beat pattern with asymmetric sequences. Subtraction images obtained from paired symmetric- and asymmetric-sequence images accurately (r = .96) reflect T'2 and can be used to indicate the presence of fat. In vivo subtraction images of ethionine-induced fatty rat livers were significantly different from similar in vivo images of normal rat livers (P less than .0005). Since for each pixel of a subtraction image, the magnitude of the difference signal should be approximately proportional to the ratio of hydroxyl and alkyl protons, this simple spin echo sequence modification may obviate the need for more time-consuming 3-dimensional Fourier transform proton chemical shift images.

Adipose Tissue↗
PubMed1985

A new nuclear magnetic resonance property of lung.

Inflated lung has a nuclear magnetic resonance (NMR) free-induction decay (FID) which is short compared with that of collapsed lung and those of other body tissues. An almost identically short FID is obtained from a slurry of 5-micron alumina particles in water. Interfaces between air and water in lung and between alumina and water in the slurry appear to be the source of spatial internal magnetic inhomogeneities which produce NMR line broadening and the short FID. Paired images that included lung, taken with paired symmetric and asymmetric NMR spin-echo sequences, permit the generation of an image, by subtraction, of the lung isolated from surrounding tissue. These new lung images are neither proton density, T1 (spin-lattice relaxation time), nor T2 (spin-spin relaxation time) images. They complement current NMR images and provide information about regional lung inflation. This previously unrecognized NMR property of lung tissue has potential application in NMR imaging, in quantitative determination of lung water and its distribution, and in the quantitation of regional lung inflation.

Animals↗
PubMed1984

Determination of lung water content and distribution by nuclear magnetic resonance.

The present study was designed to determine the value of nuclear magnetic resonance (NMR) imaging as a technique for quantifying lung water distribution and to estimate the degree of spatial resolution achieved by this technique. The spatial distribution of water was determined in six small (0.76 ml) rat lung tissue specimens by an NMR line-scan technique. After NMR imaging, each lung specimen was frozen and subdivided into slices; the gravimetric lung water content for each lung slice was compared with the integrated NMR water content over the volume corresponding to the same lung slice. In each tissue specimen, NMR and gravimetric lung water values were significantly correlated; the correlation coefficient for the pooled data for all six lung specimens was 0.91 (P less than 0.01). In two lung specimens, NMR values tended to be slightly higher than the gravimetric values. The magnitude of the difference between NMR and gravimetric values was generally less than 20% and only occasionally exceeded 25%. Our results suggest that the NMR-imaging method provides satisfactory estimates of lung water content and its distribution; the resolving power of the technique is excellent, as shown by its ability to detect water content differences between lung tissue slices of volume as small as 0.076 ml.

Animals↗