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PubMedDate not supplied

High resolution MRI of the deep brain vascular anatomy at 8 Tesla: susceptibility-based enhancement of the venous structures.

PURPOSE: The purpose of this work was to describe the deep vascular anatomy of the human brain using high resolution MR gradient echo imaging at 8 T. METHOD: Gradient echo images were acquired from the human head using a transverse electromagnetic resonator operating in quadrature and tuned to 340 MHz. Typical acquisition parameters were as follows: matrix = 1,024 x 1,024, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, FOV = 20 cm, slice thickness = 2 mm. This resulted in an in-plane resolution of approximately 200 microm. Images were analyzed, and vascular structures were identified on the basis of location and course. RESULTS: High resolution ultra high field magnetic resonance imaging (UHFMRI) enabled the visualization of many small vessels deep within the brain. These vessels were typically detected as signal voids, and the majority represented veins. The prevalence of the venous vasculature was attributed largely to the magnetic susceptibility of deoxyhemoglobin. It was possible to identify venous structures expected to measure below 100 microm in size. Perforating venous drainage within the deep gray structures was identified along with their parent vessels. The course of arterial perforators was more difficult to follow and not as readily identified as their venous counterparts. CONCLUSION: The application of high resolution gradient echo methods in UHFMRI provides a unique detailed view of particularly the deep venous vasculature of the human brain.

Arteries↗
PubMed2003

MRI and 1H MRS findings in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder characterized by a defect in cholesterol biosynthesis, associated with mental retardation and multisystem structural abnormalities. This study investigated the prevalence of congenital CNS abnormalities by MRI in a large series of patients with SLOS and the correlation of the clinical and biochemical findings with the results of MRI and 1H MRS. Eighteen patients were studied; all underwent MRI of the brain, and 16 had 1H MRS of the cerebral white matter. The ratios choline:NAA, lipid:NAA, and lipid:choline metabolite were found to be correlated with the clinical degree of disease severity, serum total sterol ratios (cholesterol/cholesterol + 7-dehydrocholesterol + 8-dehydrocholesterol) and in two cases with the effect of cholesterol therapy. Abnormal CNS findings were noted in five patients, including callosal abnormalities (n = 4), Dandy-Walker variant (n = 1), and arachnoid cyst (n = 1). Holoprosencephaly was noted in one patient with a prevalence of 6%. Choline:NAA was elevated in seven patients. There was a statistically significant positive correlation between the lipid:choline ratio and the serum cholesterol precursor, 8-dehydrocholesterol. In two patients 1H MRS demonstrated abnormally elevated lipids prior to cholesterol therapy, which improved on therapy. The use of MRI and 1H MRS is an effective way to demonstrate brain structural abnormalities in patients with SLOS and may prove to be an effective method for the assessment of the effects of cholesterol replacement therapy in the brain.

Adolescent↗
PubMed1991

Magnetic resonance imaging in schizophrenia: altered brain morphology associated with P300 abnormalities and eye tracking dysfunction.

This study was designed to investigate whether auditory P300 event-related potential and smooth pursuit eye-movement abnormalities in schizophrenia are associated with brain structural changes measured using magnetic resonance imaging (MRI). Serial coronal MRI scans obtained from 31 schizophrenic subjects and 33 volunteer controls were analysed by a rater who had no knowledge of the subjects' diagnoses. The brain areas measured bilaterally were the temporal lobe, hippocampus, amygdala, parahippocampal gyrus, head of caudate, cingulate cortex, frontal cortex, and the lateral ventricles. The area of the third ventricle, the thickness of the corpus callosum, and the intracranial area were also measured. Auditory P300 and eye tracking performance were recorded on all subjects. There was a significant increase in the latency and a reduction in amplitude of the P300 in the schizophrenic group. Only in the schizophrenic group was P300 latency correlated negatively with the area of the right and left cingulate cortex and positively with the difference in size between the right and left amygdala. In the subgroup of schizophrenic subjects whose P300 latency was greater than 2 standard deviations above the control mean, the area of the left cingulate cortex was significantly smaller than in controls, and the absolute right-left difference in the area of the amygdala was significantly increased. Eye tracking dysfunction in schizophrenia was not related to changes in the amygdala or cingulate cortex but was significantly correlated with enlargement of the lateral ventricles. Schizophrenic subjects with poor eye tracking had significantly larger lateral ventricles than controls. Eye tracking dysfunction, but not P300 abnormality, was correlated with the severity of both positive and negative symptom of schizophrenia. These findings demonstrate that psychophysiological abnormalities are associated with altered brain structure in schizophrenia.

Arousal↗
PubMed2000

Cytoprotection does not preserve brain functionality in rats during the acute post-stroke phase despite evidence of non-infarction provided by MRI.

In animal models of stroke the promise of a therapy is commonly judged from infarct size measurements, assuming that a reduction in infarct size results in reduction of the functional deficits. We have evaluated the validity of the concept that structural integrity translates into functional integrity during the acute post-stroke period (24 h). Unilateral permanent middle cerebral artery occlusion (pMCAO) in Fischer F344 rats leads to infarcts comprising the ipsilateral striatum and cortical structures, including the somatosensory cortex. Infarct volumes were assessed using magnetic resonance imaging (MRI) methods (T(2), diffusion, perfusion MRI). The functional integrity of the somatosensory cortex was assessed by functional MRI (fMRI) measuring changes in local cerebral blood volume, and by assessing the forelimb grip strength and the beam-walking performance of the animals. Treatment with the calcium antagonist isradipine (2.5 mg/kg injected s.c. immediately after pMCAO) reduced the total infarct size by more than 40% compared to vehicle-injected controls. In particular, the ipsilateral somatosensory cortex appeared normal in diffusion- and T(2)-weighted MRI images. In sham-operated rats simultaneous electrical stimulation of both forepaws led to similar activation of both somatosensory cortices, while in pMCAO animals given vehicle only the contralateral cortex showed an fMRI response. Similarly, in pMCAO rats treated with isradipine, functional activation following bilateral electrical stimulation was only detected in the contralateral somatosensory cortex despite the normal appearance of the ipsilateral cortex in MRI images. Furthermore, fMRI responses to pharmacological stimulation with bicuculline were virtually absent in the ipsilateral somatosensory cortices both in vehicle- and isradipine-treated rats. Finally there was no significant difference between vehicle- and isradipine-treated animals upon the performance of beam-walking test or in forelimb grip strength. It is concluded that during the acute (24 h) post-occlusion period, structural integrity in the somatosensory cortex revealed by MRI does not translate into preservation of function.

Adenosine Triphosphate↗
PubMed2006

Deformation-based brain morphometry to track the course of alcoholism: differences between intra-subject and inter-subject analysis.

Substantial changes in brain morphology mark the course of alcoholism from development through dependence, recovery, and relapse. These changes can be characterized with deformation-based morphometry, which quantifies shape differences between anatomical structures, either in different subjects (cross-sectional) or in the same subject over time (longitudinal). Here we present analyses of data from a longitudinal magnetic resonance imaging (MRI) study on the effects of alcoholism on brain structure. Images were acquired from alcoholic women (n=7, mean age 47.8+/-8.3 years) and age-matched control women (n=16, mean age 51.2+/-7.5 years). From each subject, we acquired two structural MR brain images, separated by approximately 2 years (mean 21.6+/-7 months). We performed two types of morphometry using log-Jacobian maps of inter-subject and intra-subject nonrigid coordinate transformations, justified by the invariance of relevant statistics (mean, standard deviation, z-score, and t-test) under changes of the spatial and temporal reference coordinate system. With all images from one time point, a cross-sectional inter-subject morphometry determined group differences between alcoholics and normal controls. We compared these results with longitudinal intra-subject morphometry based on two images per subject acquired at different times (approximately 2 years apart). Inter- and intra-subject analysis produced partially conflicting results. Whereas the intra-subject analysis indicated faster ventricular volume increases in the alcoholics (+11% per year) than in the controls (+2% per year), the inter-subject analysis showed, on average, smaller absolute ventricle volumes in the alcoholics than in the controls (-33% relative volume). These differences were confirmed by manual planimetry and were statistically significant whether tested based on difference or change, integrated over the volume of the ventricles. Other changes and group differences were consistent between the two analyses, e.g., reduction of white matter (including corpus callosum) and increase in CSF volume, and these are in agreement with established effects of alcoholism on brain structure. We conclude that intra-subject morphometry of longitudinal data is preferable to inter-subject morphometry for detecting dynamic changes due to a disease, especially when only small samples are available. Our analysis demonstrates that the distinction between group differences observed at a point in time vs. over time is not merely academic but can substantially reduce the validity of the outcomes of actual morphometric studies. This discrepancy in results underscores the importance of distinguishing between volume differences and volume changes in morphometric analyses.

Adult↗
PubMed2000

Application of a biomagnetic measurement system (BMS) to the evaluation of gastrointestinal transit of intestinal pressure-controlled colon delivery capsules (PCDCs) in human subjects.

PURPOSE: For determination of the transit time through various parts of the gastrointestinal (GI) tract, we developed a method that provides the location of disintegration and drug release. This method involves GI magnetomarkergraphy (GIMG) using a 129-channel Shimadzu vector biomagnetic measurement system (BMS). METHODS: To magnetically label the pressure-controlled colon delivery capsule (PCDC) containing 75.0 +/- 0.5 mg of caffeine as a tracer drug, small capsule caps containing 90 mg of ferric oxide powdered magnetite (Fe2O3) were attached to PCDCs. After orally administration to fasted human volunteers, saliva samples were collected hourly and salivary caffeine concentration was measured. At the same time, locations of the magnetic PCDC were detected by BMS just after the PCDCs were magnetized with the coils of a magnetic resonance imaging (MRI) system. The magnetic field distributions were analyzed and the estimated positions were shown on the MRI picture of the same subject's abdominal structure. RESULTS: We magnetized PCDC with permanent magnets or an electromagnet before ingestion and the estimated locations of PCDC in the GI tract exhibited high estimation error. In order to increase the precision of estimated localization of PCDCs, PCDCs were magnetized within the coils of the MRI. As a result, these PCDCs had strong magnetic dipoles that were parallel to the sensor unit of BMS in every measurement, and therefore the spatial resolution of the PCDC's two-dimensional positions in the organs of the GI tract was within a range of several millimeters. CONCLUSIONS: GIMG is a powerful tool for the study of colon delivery efficiencies of PCDCs. The main advantage of GIMG is the capability to obtain even more detailed knowledge of the behavior and fate of solid pharmaceutical formulations during GI passage.

Abdomen↗
PubMed2005

Cerebral small-vessel disease and decline in information processing speed, executive function and memory.

Cerebral small-vessel disease is common in older people and may contribute to the development of dementia. The objective of the present study was to evaluate the relationship between measures of cerebral small-vessel disease on MRI and the rate of decline in specific cognitive domains in participants from the prospective, population-based Rotterdam Scan Study. Participants were 60-90 years of age and free from dementia at baseline in 1995-1996. White matter lesions (WML), cerebral infarcts and generalized brain atrophy were assessed on the baseline MRI. We performed neuropsychological testing at baseline and repeatedly in 1999-2000 and in 2001-2003. We used random-effects models for repeated measures to examine the association between quantitative MRI measures and rate of decline in measures of global cognitive function, information processing speed, executive function and memory. There were a total of 2266 assessments for the 832 participants in the study, with an average time from the initial to last assessment of 5.2 years. Increasing severity of periventricular WML and generalized brain atrophy and the presence of brain infarcts on MRI were associated with a steeper decline in cognitive function. These structural brain changes were specifically associated with decline in information processing speed and executive function. The associations between MRI measures of cerebral small-vessel disease and cognitive decline did not change after additional adjustment for vascular risk factors or depressed mood. After exclusion of participants with an incident stroke, some of the associations of periventricular WML, brain infarcts and generalized brain atrophy with measures of information processing speed and executive function were no longer significant. This may indicate that stroke plays an intermediate role in the relationship between cerebral small-vessel disease and cognitive decline. Our results suggest that in older people cerebral small-vessel disease may contribute to cognitive decline by affecting information processing speed and executive function.

Aged↗
PubMed2000

The use of cardiac magnetic resonance imaging in coronary artery disease.

A new noninvasive imaging technique, magnetic resonance imaging (MRI), has been developed that has the potential to assess anatomical and functional data of patients with coronary artery disease. None of the other cardiac investigations to date can combine all aspects of information. Cardiac MRI is a challenging task because of the motion of the structure during cardiac contraction and the motion with respiration. We reviewed the technique and the use of cardiac MRI in various aspects. The emerging area in cardiac MRI is the analysis of the plaque morphology information, and the use of the new contrast agents. Further investigation is needed in order for cardiac MRI to achieve a better image information within a shorter period of time.

Coronary Disease↗
PubMed2005

The sartorial branch of the saphenous nerve: its anatomy at the joint line of the knee.

PURPOSE: Injury to the saphenous nerve accounts for the majority of neurovascular complications during arthroscopic meniscal repairs. Although the anatomy of the infrapatellar branch has been studied, the location of the sartorial branch at the level of the joint line has not been defined adequately. The purpose of this study was to define the location of the sartorial branch in relation to surrounding structures at the level of the knee joint/meniscus. TYPE OF STUDY: Cadaveric anatomic study and imaging study. METHODS: We dissected 42 cadaveric knees and studied an additional 100 knees with axial magnetic resonance imaging (MRI). We measured distances from the nerve to adjacent structures and evaluated and graphically recorded 2-dimensional axial relationships. Dissections and MRIs were performed with the knee in full extension. RESULTS: In the dissected cadaveric knees, the distance from the nerve to the anterior border of the sartorius averaged 16.0 mm, with 90% greater than 10.0 mm. The nerve was extrafascial at the joint line in only 43% of the specimens. Axial MRI examinations found the average distance to the anterior border of the sartorius to be 16.5 mm, with 82% greater than 1.0 cm. The average distance to the gracilis tendon was 9.4 mm; 91% were within 1.0 cm and 51% within 5 mm. The average distance to the semitendinosus was 14.9 mm; none was within 5 mm. The nerve was never posterior or lateral to the semitendinosus, never posterolateral or lateral to the gracilis, and was anterior to the sartorius in only 3% of knees. CONCLUSIONS: This study describes the most common location of the sartorial branch of the saphenous nerve and the potential variability that may be encountered. CLINICAL RELEVANCE: Understanding the anatomy of the sartorial branch at the level of the joint line and its relationships to surrounding structures will help to minimize the risk of injury to the nerve during common surgical procedures at the posteromedial corner of the knee.

Aged↗
PubMed1998

Stereotactic pallidotomy and thalamotomy using individual variations of anatomic landmarks for localization.

OBJECTIVE: The optimal choice of imaging and localization for stereotactic surgery for movement disorders remains uncertain, with controversy surrounding the use of microelectrode recording and the role of distortion of magnetic resonance imaging (MRI) scans in reducing the accuracy of lesion placement. We review our experience with 67 pallidotomies and 35 thalamotomies performed without microelectrode recording, using instead individual variations in anatomic landmarks. METHODS: Computed tomography is used as the primary modality, with comparison with carefully angled MRI scans and the use of neural structures, such as the mamillary bodies and the vascular anatomy. Pallidal target sites are chosen immediately lateral and superior to the optic tract on a line bisecting the axis of the peduncle, with macrostimulation guiding the final adjustment of target position. Forty-seven patients undergoing unilateral pallidotomies were studied in the "off" state and the "on" state using a modified Unified Rating Scale for Parkinson's disease (URSP) score and a dyskinesia scale, preoperatively and postoperatively at 2 weeks, 2 months, 6 months, and 12 months. In the 31 patients undergoing thalamotomy, tremor was rated preoperatively and postoperatively as near-complete resolution, partial resolution, and failure. RESULTS: The "off" state Unified Rating Scale for Parkinson's disease motor score declined from 42.0 to 32.2 at 2 weeks after surgery (P < 0.0001, n = 42). The Unified Rating Scale for Parkinson's disease motor score was 34.2 at 2 months (P < 0.0001, n = 35), 29.4 at 6 months (P < 0.0001, n = 27), and 24.9 at 12 months (P = 0.005, n = 12), representing an overall improvement in "off" state motor function of approximately 25 to 40%. The "on" state dyskinesia score fell from 5.5 to 2.0 at 2 weeks (P < 0.0001) and persisted in the later visits. The dyskinesia score for the contralateral side fell from 2.5 preoperatively to 0.26 at 2 weeks, 0.28 at 2 months, 0.22 at 6 months, and 0.0 at 12 months. Of the patients undergoing thalamotomies, 65% experienced near-complete or complete tremor resolution, 23% experienced partial tremor relief, and 13% were considered treatment failures. CONCLUSION: Stereotactic procedures for movement disorders requiring high precision can be safely and successfully performed without the use of microelectrode recording techniques. Meticulous alignment of MRI and computed tomographic scans based on visualized anatomy allows precise lesion placement and avoids the distortion inherent in MRI scans.

Globus Pallidus↗
PubMed2006

Disorders of the immature carpus.

Carpal disorders in children are often associated with developmental abnormalities of structures surrounding the wrist. In addition, carpal ossification throughout childhood has unique influences on pediatric carpal injury. Because the immature carpus is composed of unossified cartilage, carpal abnormalities in young children are frequently undetectable on plain radiographs. Clinical suspicion of an abnormality may elicit further imaging with MRI, which can provide detailed information about cartilaginous structures.

Age Factors↗
PubMed1991

[Problems and errors of magnetic resonance in the diagnosis of renal masses].

Since the impact of MRI on the diagnostic evaluation of renal masses is affected by the intrinsic complexity of the modality, the problems related to the specific knowledge, on the part of the radiologist, of the examination itself to make a correct diagnosis are carefully analyzed. The problems related to the technical features of the equipment are presented as well, with a special emphasis on the still inadequate spatial resolution of MRI, and on its long acquisition time and unfavorable signal-to-noise ratio. On the other hand, its good contrast resolution is mentioned, which will be further improved by the new gradient-echo sequence (GRE) and by the use of paramagnetic contrast media. As for diagnostic problems, the results are analyzed of a series of 62 patients showing US "solid" renal mass. MRI allowed lesion detection in 59/62 cases, with 95.1% sensitivity. False negatives were due solely to the poor image quality determined by motion artifacts. MRI did not provide significant information in the structural evaluation of the lesions when tissue characterization was concerned, but was helpful in the correct assessment of necrotic foci (thus allowing the calculation of viable neoplastic mass) and in the detection of collateral vessels. Finally, the spatial relationships of the mass could be easily assessed by MRI, thanks to both its multiplanarity and to its good capabilities in the visualization of vascular involvement.

Diagnostic Errors↗
PubMed1984

Magnetic resonance imaging of vascular lesions in children. Assessment of flow patterns.

Ten children aged 1 week to 13 years with 12 vascular abnormalities were examined with magnetic resonance imaging (MRI) and other imaging modalities. MRI was the only single non-invasive modality that demonstrated all lesions and their internal structures. The vascular nature of 3 hemangiomas could not be established with MRI alone. No marked differences in MRI appearance was seen in 5 cases with vascular tumors compared with 5 cases with other vascular abnormalities. The status of the blood in the vascular lesions as flowing fast, slow, or not at all was successfully assessed in 9 of the 12 lesions.

Aortic Aneurysm↗
PubMed1993

[Ligaments of the knee].

The authors study the various ligaments of the knee and, for each one, the anatomy, mechanisms of injury, clinical diagnosis, indications for imaging (plain x-rays, arthroscopy, MRI). The anterior cruciate ligament and posterior cruciate ligament are best visualised by MRI. The tibial collateral ligament and fibular collateral ligament are also well visualised by MRI. The value of the posteromedial and posterolateral angle points, stabilising functional structures, is emphasised together with the important diagnostic distinction between isolated ligamentous lesions and associated lesions. MRI constitutes the best imaging technique for assessment of the lesions. It completes the clinical examination and should be performed early.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Postcontrast 3D-TOF-MR angiography of intracranial venous angiomas.

The clinical value of three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) was assessed in 15 patients with intracranial venous angiomas (VAs), by comparing results thereof with those of postcontrast T1-weighted MR images (MRIs). All 15 VAs were identified both on the postcontrast MRIs and MRAs. The MRAs surpassed the MRIs in imaging entire structures, including the draining veins of the supratentorial VAs. For the infratentorial VAs, the MRAs and the MRIs were of equal value. Although the addition of MRA to the MRI procedure incurs more time and expense, the complete structure of the VA can thereby be identified three-dimensionally on MRA. Conventional angiography is apparently not required for the confirmation of a VA. Thus, it is concluded that MRA is very useful for diagnosing VAs.

Adolescent↗
PubMed1996

Magnetic resonance imaging and computed tomography in Alzheimer's disease.

Modern imaging techniques such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) are widely used in the clinical evaluation of patients with dementia disorders. Computed tomography was introduced for clinical practice in the beginning of the 1970s. The advent of MRI came later with the first equipment used for clinical purposes being introduced in the first half of the 1980s. The two modalities differ in many aspects: CT has a lower contrast resolution compared with MRI and is also faster and often more convenient for patients. In contrast, MRI gives a superior picture of the brain tissue without the use of contrast agents. Moreover, MRI, like CT, does not suffer from bone artifacts. The latter is of special importance in the study of dementia diseases (especially Alzheimer's) where structural changes are present close to the brain. The possibility of image in arbitrary imaging planes also makes MRI more suitable to study structures of relevance in Alzheimer's disease such as the medial temporal lobes and the hippocampal formation.

Aged↗
PubMed1985

Magnetic resonance imaging of soft-tissue tumors: comparison with computed tomography.

Twenty-seven patients with soft-tissue tumors were examined with a Picker 0.15-tesla resistive magnet and by computed tomography (CT). In all but one patient, MRI was better than or equal to CT in defining the anatomic extent of the tumor. We could determine whether major vascular structures were engulfed by the tumor in 80% of the MRI examinations but only in 62% of the CT scans. MRI and CT were equally effective in determining the presence or absence of bony invasion. The MRI images of all the tumors showed increased signal intensity relative to normal muscle when spin-echo (SE) pulse sequences with long repeat times were used (SE: echo time [TE], 60 ms; repetition time [TR], 2,000 ms). When T1 weighted pulse sequences were used (SE: TE, 30 ms; TR, 500 ms or inversion recovery: inversion time, 500 ms; TE, 40 ms; TR, 2,000 ms) the malignant tumors showed decreased signal intensity compared to normal muscle. Only lipomas showed high signal intensity on both T1 and T2 weighted pulse sequences.

Adolescent↗
PubMed2006

Parametric modeling of DSC-MRI data with stochastic filtration and optimal input design versus non-parametric modeling.

In the paper MRI measurements are used for assessment of brain tissue perfusion and other features and functions of the brain (cerebral blood flow - CBF, cerebral blood volume - CBV, mean transit time - MTT). Perfusion is an important indicator of tissue viability and functioning as in pathological tissue blood flow, vascular and tissue structure are altered with respect to normal tissue. MRI enables diagnosing diseases at an early stage of their course. The parametric and non-parametric approaches to the identification of MRI models are presented and compared. The non-parametric modeling adopts gamma variate functions. The parametric three-compartmental catenary model, based on the general kinetic model, is also proposed. The parameters of the models are estimated on the basis of experimental data. The goodness of fit of the gamma variate and the three-compartmental models to the data and the accuracy of the parameter estimates are compared. Kalman filtering, smoothing the measurements, was adopted to improve the estimate accuracy of the parametric model. Parametric modeling gives a better fit and better parameter estimates than non-parametric and allows an insight into the functioning of the system. To improve the accuracy optimal experiment design related to the input signal was performed.

Animals↗