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Biomedical subjects

D D Blatter

Publications and source records attributed to D D Blatter.

At least 19 recordsLinked to original sources
PubMed2001

Verbal memory deficits associated with fornix atrophy in carbon monoxide poisoning.

Magnetic resonance (MR) images and neuropsychological testing data of 69 carbon monoxide (CO) poisoned patients were prospectively obtained within 1 day of CO poisoning, two weeks and six months. CO patients' Day 1 cross-sectional fornix surface area measurements, corrected for head size by using a fornix-to-brain ratio (FBR), were compared to normal age and gender-matched controls. Additionally, a within-subjects analysis was performed comparing the mean areas between CO patients' Day 1, 2 weeks and 6-month FBR. The FBR was correlated with patients' neuropsychological data. There were no significant differences between CO patients' Day 1 fornix measurements compared to normal control subjects. However, significant atrophic changes in the fornix of CO poisoned patients occurred at two weeks with no progressive atrophy at 6 months. By 6 months, CO patients showed significant decline on tests of verbal memory (when practice effects were taken into account), whereas visual memory, processing speed and attention/concentration did not decline. This study indicates that CO results in brain damage and cognitive impairments in the absence of lesions and other neuroanatomic markers.

Adolescent↗
PubMed1999

Evaluation of measures of technical image quality for intracranial magnetic resonance angiography.

We evaluate three measures of technical image quality for intracranial magnetic resonance angiography (MRA): (1) a two-alternative forced choice (2AFC) evaluation of vessel visibility, (2) vessel-to-background signal-difference-to-noise ratio (SDNR), and (3) observer ranking of the fidelity of vessel morphology compared to that in a gold standard image. The gold standard used for both the 2AFC and ranking measures is intraarterial catheter angiography. These measures are applied to healthy arterial segments. The 2AFC and SDNR measures directly evaluate the visibility of artery segments for which the existence is known from the gold standard images. We argue that (1) 2AFC evaluates the carrier signals on which any vascular disease process is modulated and provides an upper bound on the detectibility of vascular lesions, (2) SDNR is a predictor of 2AFC, and (3) ranking may be used to predict the relative performance of techniques in the detection of vascular lesions.

Adult↗
PubMed1999

Polysubstance abuse and traumatic brain injury: quantitative magnetic resonance imaging and neuropsychological outcome in older adolescents and young adults.

Few studies have examined the consequences of alcohol and drug abuse on TBI though they commonly co-occur. Both TBI and substance abuse independently result in neuropathological changes in the brain such as ventricular enlargement and cortical atrophy, thus it is reasonable to hypothesize that the combination of the two would result in more significant cerebral damage. In this study, 3 groups of patients--traumatically brain injured (TBI) with substance abuse (N = 19), TBI without substance abuse (N = 19), and substance abuse with no TBI (N = 16)--were compared with normal controls (N = 20) on several quantitative MRI (QMRI) measures. Since TBI most frequently occurs in older adolescents and young men, we examined only male participants between 16 and 30 years of age. Comparing young substance abusers to controls resulted in no QMRI differences. When controlling for head injury severity, the effects of substance abuse in combination with TBI resulted in greater atrophic changes than seen in any other group. TBI and substance abuse patients' neuropsychological test performances also were examined, and no differences were found among patient groups on any measures. These findings have implications for the deleterious interaction of substance abuse combining with TBI to result in greater neuropathological changes that can be detected by QMRI techniques.

Adolescent↗
PubMed1999

MRI, quantitative MRI, SPECT, and neuropsychological findings following carbon monoxide poisoning.

Carbon monoxide (CO) poisoning has been shown to result in neuropathologic changes and cognitive impairments due to anoxia and other related biochemical mechanisms. The present study investigated brain-behaviour relationships between neuropsychological outcome and SPECT, MRI, and Quantitative magnetic resonance imaging (QMRI) in 21 patients with CO poisoning. Ninety-three per cent of the patients exhibited a variety of cognitive impairments, including impaired attention, memory, executive function, and mental processing speed. Ninety-five per cent of the patients experienced affective changes including depression and anxiety. The results from the imaging studies revealed that 38% of the patients had abnormal clinical MRI scans, 67% had abnormal SPECT scans, and 67% had QMRI findings including hippocampal atrophy and/or diffuse cortical atrophy evidenced by an enlarged ventricle-to-brain ratio (VBR). Hippocampal atrophy was also found on QMRI. SPECT and QMRI appear to be sensitive tools which can be used to identify the neuropathological changes and cerebral perfusion defects which occur following CO poisoning. Cerebral perfusion defects include frontal and temporal lobe hypoperfusion. Significant relationships existed between the various imaging techniques and neuropsychological impairments. The data from this study indicate that a multi-faceted approach to clinical evaluation of the neuropathological and neurobehavioural changes following CO poisoning may provide comprehensive information regarding the neuroanatomical and neurobehavioural effects of CO poisoning.

Adult↗
PubMed1999

Head trauma and intellectual status: relation to quantitative magnetic resonance imaging findings.

This article contrasts 2 groups that sustained somewhat similar moderate to severe closed-head traumatic brain injury (TBI), but were deliberately selected to be different with regard to postinjury intellectual status--one group average or above, the other below. The purpose of this comparison was to describe any morphological characteristics of the 2 groups ascertained from quantitative magnetic resonance (QMR) imaging. Thirty-five TBI participants with Full Scale IQ (FSIQ) less than or equal to 90 were compared to 33 TBI participants whose FSIQ was above 90. A group of normal volunteer participants, age and gender matched, constituted a third magnetic resonance comparison group. All participants received uniform MRI from which QMR analysis was performed, including total cranial volume, subarachnoid cerebral spinal fluid ventricular volume, and hippocampal volume. Both TBI groups received neuropsychological testing in the course of clinical follow-up. Morphological comparisons between groups were made using multivariate analysis of variance. The TBI group with an IQ less than or equal to 90 had significantly enlarged third and temporal horn compartments. Total intracranial volume was smaller in this group as well. Lower psychometric intelligence postinjury may be associated with more temporal lobe atrophy and subcortical pathology. Smaller premorbid brain size may be another risk factor.

Adult↗
PubMed1998

Optimized visualization of vessels in contrast enhanced intracranial MR angiography.

In this study, the problem of small vessel visualization in magnetic resonance angiography is addressed. The loss of vessel contrast due to slow flow-related signal saturation can be compensated by the T1 reduction obtained from the use of an MR contrast agent, such as Gd-DTPA. The vessel/background signal-difference-to-noise ratio (SDNR) is shown to strongly depend on the imaging parameters, as well as on the time course of the blood T1 values obtained from the contrast injection. Specifically, it was found that vessel SDNR increases almost linearly with TR, if the sampling bandwidth is reduced proportionately.

Artifacts↗
PubMed1997

Observer performance methodologies for evaluating blood vessel visibility in MR angiograms using accurate geometric registration to high resolution x-ray angiograms.

Receiver operator characteristic (ROC) and two alternative forced choice (2AFC) methodologies for quantitatively assessing vessel visibility in MR angiography (MRA) were examined using x-ray angiography images as truth. The methodologies required MRA projection images with the same orientation and magnification as the x-ray images. Geometric distortions limited the quality of the registration. The observer performance measurements were compared to vessel contrast-to-noise ratio (CNR) measurements. Receiver bandwidth (RBW) and magnetization transfer (MT) effects in 3D time-of-flight MRA were evaluated. Overall, applying MT significantly increased all three measurements while decreasing the RBW significantly improved the 2AFC and CNR measurements. The relative importance of both effects on the 2AFC measure increased as vessel diameter decreased, although statistical significance was limited by small samples for diameters less than approximately 0.7 mm. These results demonstrate the usefulness of these observer performance methodologies for MRA technique assessment.

Angiography, Digital Subtraction↗
PubMed1997

Velocity measurement based on bolus tracking with the aid of three-dimensional reconstruction from digital subtraction angiography.

The problem of blood flow measurement in x-ray angiography using measurements of the leading edge of the contrast bolus as it traverses the vascular bed is considered. A new technique for velocity measurement is presented based upon the ratio of the temporal derivative to the spatial derivative of the contrast bolus in the direction of flow. With the addition of a small correction factor, the value obtained is shown to reflect the transport velocity, or the velocity at which the contrast is transported down the vessel of interest. Most blood flow measurements based on bolus tracking techniques are actually using the contrast transport velocity to represent the blood flow velocity. Because of the streaming that occurs due to laminary flow conditions, the measured transport velocity is found to be somewhere between the average and the peak (central) fluid velocities for measurements taken during the traversal of the bolus leading edge. The spatial and temporal variation of the transport velocity are found to be consistent with the bolus motion expected in the presence of laminar flow. From x-ray images of contrast passage through simple tubes, we find that the derivative method measures the transport velocity during passage of the bolus leading edge. In most cases of laminar blood flow, the leading edge transport velocity can be 20%-40% higher than the average blood velocity.

Angiography, Digital Subtraction↗
PubMed1997

MR-based brain and cerebrospinal fluid measurement after traumatic brain injury: correlation with neuropsychological outcome.

PURPOSE: To determine the magnitude and time course of changes in the volume of brain and intracranial cerebrospinal fluid (CSF) spaces in patients who have sustained traumatic brain injury and to assess the relationship between these findings and long-term cognitive traumatic outcome. METHODS: Axial intermediate and T2-weighted MR images of 123 patients with traumatic brain injury were quantified using a multispectral segmentation algorithm. Measurements were corrected for differences in age, sex, and head size using a previously reported normative database. Brain morphology was compared across groups formed on the basis of chronicity of injury. Cognitive functioning and severity of injury were statistically correlated with brain measurements. RESULTS: Time-dependent expansion of CSF spaces and decreases in brain volume were observed. Increases in ventricular CSF volume, particularly in the temporal horns and third ventricle, preceded subsequent changes in total brain and subarachnoid CSF. High and moderate correlation was observed between volume measures and cognitive outcome and injury severity. Particularly strong was the relation between the volume of the left temporal horn and verbal IQ scores. CONCLUSION: Predictable time-dependent atrophic changes occurring after traumatic brain injury can be quantified using MR volumetric studies. Our results suggest significant contributions by both diffuse and focal mechanisms of injury. In the postacute period (more than 70 days after injury), MR volumetric studies may be predictive of eventual cognitive outcome.

Adolescent↗
PubMed1997

Hippocampal volume in normal aging and traumatic brain injury.

PURPOSE: To present a normative database of hippocampal and temporal horn volume and to clarify the relationship between these measures and cognitive outcome in patients with traumatic brain injury. METHODS: Ninety-six healthy volunteers and 94 patients with traumatic brain injury were examined with coronal intermediate and T2-weighted MR imaging. Multispectral segmentation and volume analyses were performed. The volumetry of the hippocampus and temporal horn was characterized in the control subjects. Volumetric measures in a group of patients with traumatic brain injury who had received MR imaging 3 months or less after injury were compared with measurements in other patients in the chronic phase of recovery. The relationship between neuropsychological testing and volumetric measures was analyzed with particular emphasis on the correlation between cognitive outcome and hippocampal and temporal horn volumes. RESULTS: No significant age group differences were found in the normative group from age 16 to 65. Left and right hippocampal volumes were interrelated and did not differ from each other. This was also true for the temporal horns. Hippocampal and temporal horn volumes were not significantly related. Women had larger hippocampi relative to cranial volume. Comparisons between patients with traumatic brain injury and control subjects showed significant yet modest bilateral atrophic changes in hippocampal and temporal horn enlargement in the patients with brain injury. Hippocampal and temporal horn volumes correlated significantly with each other in the group with traumatic brain injury. Cognitive outcome was modestly related to hippocampal and temporal horn volumes. However, in a specific subgroup whose images were acquired between 71 and 210 days after injury, strong correlations were noted in which temporal horn volume correlated highly with IQ and hippocampal volume correlated with verbal memory function. CONCLUSION: Hippocampal and temporal horn volumes appear to be independent variables in healthy control subjects. Traumatic brain injury results in significant hippocampal atrophy and temporal horn enlargement. The hippocampus and temporal horn volumes were inversely correlated in the group with traumatic brain injury, suggesting a differential relationship of these structures in patients with brain injury as compared with control subjects. In the subacute phase, the volume of the temporal horn may be indicative of intellectual outcome and that of the hippocampus appears to be indicative of verbal memory function.

Adolescent↗
PubMed1996

Traumatic brain injury, alcohol and quantitative neuroimaging: preliminary findings.

Magnetic resonance (MR) quantitative neuroimaging analysis was undertaken with a large group of normal (n = 197) and traumatically brain injured (TBI, n = 99) adults. Of the TBI subjects 18 patients were identified with a history of substance-related abuse (TBI/Abuse group). Both the TBI/ Abuse group and the remaining sample of TBI patients (n = 81, TBI/Non-abuse group) without a history of substance-related abuse differed significantly from the control group on most quantitative MR imaging analyses. The TBI/Abuse group displayed the greatest degree of atrophic change. However, the TBI/Abuse group had a significantly lower Glasgow Coma Scale (GCS) score, ostensibly suggesting that those with substance-related abuse suffered more severe brain injury than non-abuse TBI patients. When a subset (n = 18) of the TBI/Non-abuse group was matched by GCS, gender and age to the TBI/Abuse group, both groups differed significantly from the control group on most morphometric measures, but did not differ from one another. Results are discussed in terms of the potential adverse role that substance-related abuse, particularly alcohol, plays in the individual who sustains traumatic injury to the brain.

Adolescent↗
PubMed1996

Lesion volume, injury severity, and thalamic integrity following head injury.

Magnetic resonance scans of 63 TBI patients were analyzed to examine the relationship between injury severity, lesion volume (nonthalamic cortical/subcortical lesions), ventricle-to-brain ratio (VBR), and thalamic volume. For comparison, 33 normal control subjects were used. Patients with visible nonthalamic structural lesions showed significantly smaller thalamic volumes than patients without visible lesions or control subjects. Results also indicated that patients with visible lesions had significantly more severe injuries than patients without lesions. Patients with moderate-severe injuries had significantly smaller thalamic volumes and greater VBRs than patients with mild-moderate injuries. Although several variables related to thalamic volume, the presence of nonthalamic lesions was sufficient to result in smaller thalamic volume. Decreased thalamic volume following head injury suggests that subcortical brain structures may be susceptible to transneuronal degeneration following cortical lesions, and that this can be detected by in vivo MR-based volumetric analysis.

Adult↗
PubMed1996

Lesion volume, injury severity, and thalamic integrity following head injury.

Magnetic resonance (MR) scans of 63 traumatic brain injury (TBI) patients were analyzed to examine the relationship between injury severity, lesion volume (nonthalamic cortical/subcortical lesions), ventricle-to-brain ratio (VBR), and thalamic volume. For comparison, 33 normal control subjects were used. Patients with visible nonthalamic structural lesions showed significantly smaller thalamic volumes than patients without visible lesions or control subjects. Results also indicated that patients with visible lesions had significantly more severe injuries than patients without lesions. Patients with moderate-severe injuries had significantly smaller thalamic volumes and greater VBRs than patients with mild-moderate injuries. Although several variables related to thalamic volume, the presence of nonthalamic lesions was sufficient to result in smaller thalamic volume. Decreased thalamic volume following head injury suggests that subcortical brain structures may be susceptible to transneuronal degeneration following cortical lesions, and that this can be detected by in vivo MR-based volumetric analysis.

Adult↗
PubMed1996

A quantitative study of ramped radio frequency, magnetization transfer, and slab thickness in three-dimensional time-of-flight magnetic resonance angiography in a patient population.

RATIONALE AND OBJECTIVES: The authors compare the effectiveness of various magnetic resonance (MR) angiography acquisition strategies in enhancing the visibility of small intracranial vessels. METHODS: Blood vessel contrast-to-noise ratio (CNR) in time-of-flight MR angiography was studied as a function of vessel size and several selectable imaging parameters. Contrast-to-noise measurements were made on 257 vessel segments ranging in size from 0.3 mm to 4.2 mm in patients who recently had undergone intraarterial cerebral angiography. Imaging parameters studied included magnetization transfer, spatially variable radio frequency (RF) pulse profile (ramped RF), and imaging slab thickness. RESULTS: The combination of thin slabs (16 slices/slab), ramped RF, and magnetization transfer resulted in the highest CNR for all but the smallest vessel sizes. The smallest vessels (< 0.5 mm) had the highest CNR, using the thick slab (64 slices/slab) with ramped RF and magnetization transfer. Magnetization transfer always improved vessel CNR, but the improvement diminished as the slab thickness was reduced. The CNR increased with a decrease in slab thickness for all but the smallest vessel sizes. CONCLUSIONS: Overall, the results provide a quantitative demonstration that inflow enhancement of blood is reduced for small vessels. Thus, whereas magnetization transfer is important at all vessel sizes, it becomes the primary factor in improving the visibility of the smallest vessels.

Adult↗
PubMed1995

Nonspecific white matter degeneration following traumatic brain injury.

Morphometric analysis of magnetic resonance (MR) scans in 88 traumatic brain injury (TBI) patients demonstrated significantly larger ventricle-to-brain ratios (VBR) and temporal horn volumes, and significantly smaller fornix-to-brain ratios (FBR) and corpus callosum (CC) area measurements, compared to 73 controls. Additionally, TBI patients were grouped according to Glasgow Coma Scale (GCS) for a within-TBI sample comparison so that severity of injury on brain morphology could be examined. The severe TBI group (GCS = 3-6) differed from the mild and moderate injury groups on measures of the internal capsule, VBR, temporal horn volume, and CC. In a separate analysis wherein the TBI subjects were grouped by degree of fornix atrophy, the group with the smallest fornix size demonstrated the lowest memory performance. Furthermore, anatomic measures correlated with severity of injury, and tests of memory and motor function. Results demonstrate the diffuse nature of degeneration in TBI with more severe injury, and that quantified MR identified morphologic changes relate to neuropsychological outcome.

Adolescent↗
PubMed1995

Severe anoxia with and without concomitant brain atrophy and neuropsychological impairments.

Significant anoxia may cause a variety of neuropathologic changes as well as cognitive deficits. We have recently seen 3 patients who have suffered severe anoxic episodes all with initial Glasgow Coma Scores (GCS) of 3 with sustained coma for 10-14 d. All 3 patients had extended hospitalizations and rehabilitation therapy. A neuropsychological test battery was administered and volumetric analyses of MRI scans were carried out in each case at least 6 mo postinjury. Two of the patients display distinct residual cognitive and neuropathologic changes while 1 patient made a remarkable recovery without evidence of significant morphological abnormality. These three cases demonstrate, that even with similar admission GCS, the outcome is variable and the degree of neuropsychological impairment appears to match the degree of morphologic abnormalities demonstrated by quantitative MR image analysis. An important finding of this study is that even though subjects with an anoxic insult exhibit severe cognitive and memory impairments along with concomitant morphologic changes, their attention/concentration abilities appear to be preserved. MR morphometry provides an excellent means by which neural structural changes can be quantified and compared to neuropsychological and behavioral outcomes.

Adult↗
PubMed1995

Frontal lobe lesions, diffuse damage, and neuropsychological functioning in traumatic brain-injured patients.

This study quantified lesion volume in relation to damage location and executive functioning in traumatic brain-injured (TBI) patients. Magnetic resonance (MR) scans of 68 TBI patients were analyzed by taking volumetric measures of lesion sites. Patients were grouped according to the presence/absence of frontal lobe lesions. Measures of frontal lesion volume were studied as predictors for outcome on designated tests of executive functioning (Halstead Category Test and Wisconsin Card Sorting Test). Results showed no significant differences in level of deficit between groups. In addition, no significant differences were found between groups on other tests of neuropsychological functioning (Trail Making Test, Parts A and B, and Wechsler Adult Intelligence Scale-Revised). These results suggest that tests that are traditionally used to detect "frontal lobe" damage may not be adequate for distinguishing specific frontal lobe dysfunction, and do not add anything unique about frontal lobe integrity and neuropsychological functioning in TBI patients.

Brain Damage, Chronic↗