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At least 469 records · Page 26Linked to original sources
PubMed2006

fMRI of delayed albumin treatment during stroke recovery in rats: implication for fast neuronal habituation in recovering brains.

Accumulating experimental and clinical data suggest that albumin may be neuroprotective for stroke. Here, we use functional magnetic resonance imaging (fMRI) to evaluate the therapeutic efficacy of albumin and its effects on the recovery of stimuli-induced cerebral hemodynamics. For this purpose, fMRI activity in the ipsilesional somatosensory (SS) cortex was assessed using a well established rat model of transient 90 min focal ischemia and electrical forelimb stimulation. Rats were treated with either saline or albumin via intracerebroventricular injections at 12 h post-stroke onset. Despite this delayed treatment time, when compared to the saline-treated rats (n=7), there were significant enhancements of the fMRI activation in the albumin-treated rats (n=6) for both blood oxygenation level dependence (BOLD) and functional cerebral blood volume (fCBV) responses. Interestingly, the temporal characteristics of the ipsilesional SS BOLD responses in the albumin-treated rats appeared considerably altered compared to those of contralesional responses while such temporal alterations were not pronounced for the fCBV responses. These characteristic fMRI temporal profiles of the albumin-treated brains may be due to altered neuronal responses rather than altered integrity of neurovascular coupling, which implies an unusually fast habituation of neuronal responses in the lesional SS cortex. The correlation between various MRI-derived structural parameters and the fMRI response magnitude was also characteristic for albumin and control groups. Taken together, these data suggest that restoration of fMRI response magnitudes, temporal profiles, and correlations with structure may reveal the extent and specific traits of albumin treatment associated stroke recovery.

Albumins↗
PubMed2001

Future methods in the assessment of bone mass and structure.

There have been major advances in the diagnosis of osteoporosis over the last few decades not only in the definitions that are now used but also in the technology that is available. The future will see further development of the techniques currently in common clinical use, such us dual energy X-ray absorptiometry and quantitative ultrasound. In addition new techniques for assessing bone structure, including MRI and fractal analysis of X-rays, may add significantly to our understanding of the pathophysiology of osteoporosis and to the prediction of fracture risk.

Absorptiometry, Photon↗
PubMed2004

[Low frequency repetitive transcranial magnetic stimulation (rTMS) for the treatment of chronic tinnitus--are there long-term effects?].

OBJECTIVE: Clinical, neurophysiological and neuroimaging data suggest that chronic tinnitus resembles neuropsychiatric syndromes characterised by focal brain activation. Low frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an efficient method in treating brain hyperexcitability disorders. METHODS: Patients suffering from chronic tinnitus underwent a [ (18)F]deoxyglucose-PET (positron emission tomography). Fusioning of the individual PET scan with the structural MRI-scan (magnetic resonance imaging, T1, MPRAGE) revealed an increased metabolic activation in the primary auditory cortex as target point for rTMS. A neuronavigational system enabled the positioning of the figure of eight coil in relation to the target area. rTMS (110 % motor threshold; 1 Hz; 2000 stimuli/day over 5 days) was performed using a placebo controlled cross-over design. RESULTS: Following active rTMS there was a moderate improvement of tinnitus perception. Treatment effects lasted up to six months in some patients. CONCLUSIONS: Neuronavigated rTMS offers new possibilities in the understanding and treatment of chronic tinnitus.

Adult↗
PubMedDate not supplied

[Early radiological assessment of spinal injuries. Indication for additional imaging procedures].

UNLABELLED: The question of the best radiological diagnostic pathway to explore the acute spinal trauma is discussed. METHOD: the current state of knowledge is given, based on bibliography and the authors experience. RESULTS: Standard-radiography allows fast orientation. CT ist the best procedure for high resolution imaging of bony structures and MRI is best suited for soft tissue and medullar lesions. Ligamentous lesions are still explored with functional X-ray studies, but ligament rupture can be visualized directly by MRI. CONCLUSIONS: Standard-radiography must precede all further studies. In patients without neurological deficit: CT is indicated if standard radiography suspects a bony lesion. MRI is indicated, if there is a discrepancy between a normal radiography and severe complaints of the patient. functional radiographies are indicated if ligamentous damage is suspected, but MRI can directly visualize ligament rupture. In patients with a radicular lesion, CT is indicated. In patients with a medullar or central radicular lesion, MRI or Myelo-CT are indicated.

Adult↗
PubMed2001

Two- and 3-dimensional MRI comparison of levator ani structure, volume, and integrity in women with stress incontinence and prolapse.

OBJECTIVE: The aim of this study was to identify imaging markers for genuine stress incontinence and pelvic organ prolapse by using magnetic resonance imaging and reconstructed 3-dimensional models. STUDY DESIGN: Thirty women were studied, 10 with prolapse, 10 with genuine stress incontinence, and 10 asymptomatic volunteers. Axial and sagittal T1 and T2 weighted pelvic magnetic resonance scans were obtained with the patient in the supine position. Source images were measured to determine levator hiatus height, bladder neck to pubococcygeal line, levator plate angle, and perineal descent at rest and maximum Valsalva. Manual segmentation and surface modeling was applied to build 3-dimensional models of the organs. The 3-dimensional models were measured to determine levator muscle volume, shape and hiatus width, distance between symphysis and levator sling muscle, posterior urethrovesical angle, bladder neck descent, and levator plate angle. RESULTS: The 3 groups of subjects were comparable in age, parity, and body mass index. In the control, genuine stress incontinence, and prolapse groups, the menopausal rate was 40%, 60%, and 55% (P =.7). In the same order, significant mean 2-dimensional measures were: resting bladder neck descent of 24, 17, and 3 mm (P <.005), straining levator plate angle of -4.3, -11.5, and -31 degrees (P =.01), straining levator hiatus height of 48.5, 51.1, and 65.3 mm (P <.005), and straining perineal descent of 17.2, 22.5, 27.2 mm (P =.02). Similarly ordered mean 3-dimensional parameters showed levator volumes of 32.2, 23.3, and 18.4 cm(3) (P <.005); hiatus widths of 25.7, 34.7, and 40.3 mm (P <.005); left levator sling muscle gaps of 15.6, 20.3, and 23.8 mm (P =.03), right levator sling muscle gaps of 15.6, 22.5, and 30.8 mm, (P = 0.003), and levator shape (90%, 40%, and 20% dome shaped; P <.005). CONCLUSION: Both 2-dimensional magnetic resonance images and 3-dimensional models yield findings that differ among asymptomatic subjects compared with those with genuine stress incontinence and prolapse. Our 3-dimensional data demonstrate a statistically significant continuum in levator volume, shape, and integrity across groups of asymptomatic, genuine stress incontinence, and prolapse subjects.

Adult↗
PubMed1997

Tc-HMPAO SPECT in persistent post-concussion syndrome after mild head injury: comparison with MRI/CT.

The purposes of this study were: (1) to determine the prevalence of abnormal 99mTc-HMPAO SPECT scans in patients suffering from persistent post-concussive syndrome (PPCS) after mild closed head injury (CHI); (2) to compare SPECT with structural neuroimaging (MRI and CT) in patients with mild CHI; and (3) to investigate correlations between SPECT and clinical data obtained from the patient sample (neuropsychological testing, demographics, psychiatric diagnoses). Forty-three patients were included. SPECT was read as abnormal in 53% of patients and showed a total of 37 lesions while MRI was read as abnormal in 9% and CT scan in only 4.6% of patients after mild CHI. SPECT appears to be more sensitive in detecting cerebral abnormalities after mild CHI, especially in patients with PPCS symptoms, than either CT or MRI. No statistically significant relationship was found between SPECT scan abnormalities and age, past psychiatric history, history of substance abuse, or history of multiple CHI. Education level did not differ between patients with normal and abnormal SPECT. Current neuropsychiatric symptoms did not seem to have any impact on the results of SPECT scan.

Adolescent↗
PubMed2001

Central benzodiazepine receptors in malformations of cortical development: A quantitative study.

We calculated [(11)C]flumazenil volume of distribution ([(11)C]FMZ-V(d)) after correction for partial volume effect in 10 patients with malformations of cortical development (MCDs) and partial seizures, to quantify the GABA(A)-central benzodiazepine receptor complex. Abnormal grey matter and adjacent or overlying cortex were outlined individually and added to an individualized anatomical template for correction for partial volume effect. Nine of 10 patients showed single or multiple increases or decreases in [(11)C]FMZ-V(d) in or around MCDs. Two of three patients with band heterotopia showed multiple increases in the overlying cortex. In three of four patients with subependymal nodular heterotopia, nodules had lower [(11)C]FMZ-V(d) than the overlying cortex, which was normal. Decreases in [(11)C]FMZ-V(d) were found in two of three clefts and one of six adjacent regions in one schizencephalic patient; another had normal [(11)C]FMZ-V(d) in the thickened cortex itself but increases in all adjacent regions. Binding was reduced within focal cortical dysplasia but increased in adjacent cortex. [(11)C]FMZ-V(d) was normal within one patient's polymicrogyric cortex but increased in one of six adjacent volumes of interest. The localization of abnormalities correlated with EEG and clinical data in cortical MCDs. Flumazenil binding was decreased in some MCDs with increased grey matter volume and increased in some adjacent or overlying areas of normal-appearing cortex, suggesting functional abnormalities beyond MRI- detectable structural changes.

Adolescent↗
PubMed2003

Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve.

OBJECTIVE: To report on the outcome of four patients with aplasia or hypoplasia of the cochleovestibular nerve who have received a cochlear implant. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Four patients with: 1) type I aplasia; 2) type IIa aplasia; 3) type IIa hypoplasia; and 4) type IIb aplasia received a cochlear implant. All patients had corner audiograms even with hearing aids. INTERVENTION: Three patients received a LAURA multichannel implant, and one patient received a Nucleus 24 implant. MAIN OUTCOME MEASURE: Auditory performance, educational setting. RESULTS: The patients with type I and type IIb aplasia did not have auditive perception with their implant and became non-users. Both are now in a total communication educational setting. The patients with type IIa aplasia and hypoplasia had moderate audiological results with the implant with audiometrical thresholds of approximately 40-60 dB HL (pure tone average), moderate phoneme discrimination, and poor word discrimination. One child is in a total communication educational setting and the other in an oral educational setting, but the preferred mode of communication remains total communication for both. Both appear to benefit from the implant nonetheless. CONCLUSION: Patients with aplasia/hypoplasia of the cochleovestibular nerve should be counseled with caution with respect to cochlear implantation, but particular circumstances may justify the intervention. At present these circumstances seem to be a type IIa aplasia or hypoplasia in which the end organ (cochlea or common cavity) still connects to a neural structure on MRI.

Auditory Perception↗
PubMed2006

Magnetic resonance imaging assessment of craniovertebral ligaments and membranes after whiplash trauma.

STUDY DESIGN: Review article. OBJECTIVES: To review the literature on soft tissue lesions of the upper cervical spine in whiplash trauma with focus on imaging. SUMMARY OF BACKGROUND DATA: Whiplash injury is associated with chronic impairment in a substantial number of patients. There are different opinions as to the nature and prognosis of this condition, and the role of diagnostic imaging is debated. METHODS: Review the literature on the anatomic source of the chronic whiplash syndrome. Review the literature on imaging of the upper cervical spine, emphasizing on the author's own research. RESULTS: MRI shows structural changes in ligaments and membranes after whiplash injury, and such lesions can be assessed with reasonable reliability. Lesions to specific structures can be linked with specific trauma mechanisms. There is a correlation between clinical impairment and morphologic findings. CONCLUSION: Whiplash trauma can damage soft tissue structures of the upper cervical spine, particularly the alar ligaments. Structural lesions in this area contribute to the understanding of the chronic whiplash syndrome.

Accidents, Traffic↗
PubMedDate not supplied

Amnesia after unilateral temporal lobectomy: a case report.

We report a mixed handed (L > R) patient with exclusive right cerebral language representation who developed a permanent anterograde amnestic syndrome after right anterotemporal lobectomy. Preoperative neuropsychological performance consisted of impaired verbal memory and normal nonverbal memory. Wada memory performance was asymmetrical for objects presented soon after amobarbital injection in conjunction with no memory asymmetry for items presented later in the Wada evaluation. Pre- and postoperative magnetic resonance imaging (MRI) scans showed no structural lesions; however, postoperative MRI hippocampal volume measurements suggested decreased hippocampal volume for the nonresected temporal lobe. These results confirm the risk of anterograde amnesia after unilateral temporal lobectomy and demonstrate that baseline neuropsychological testing may falsely literalize material-specific memory functions in patients with atypical cerebral language dominance.

Adult↗
PubMed2005

Individual and population penalized regression splines for accelerated longitudinal designs.

In an accelerated longitudinal design (ALD), individuals enter the study at different points of their growth trajectory and are observed over a short time span relative to the entire time span of interest. ALD data are combined across independent units to provide an estimate of an overall population curve and predictions of individual patterns of change. As a modest extension of the work of Ruppert et al. (2003, Semiparametric Regression, Cambridge University Press), we develop a computationally efficient procedure for the application of longitudinal semiparametric methods under ALD sampling schemes. We compare balanced and complete longitudinal designs to ALDs using the Berkeley Growth Study data and apply our method to longitudinal magnetic resonance imaging (MRI) brain structure size (volume) measurements from an ongoing developmental study. Potential applications extend beyond growth studies to many other fields in which cost and feasibility constraints impose restrictions on sample size and on the numbers and timings of repeated measurements across subjects.

Adolescent↗
PubMedDate not supplied

Magnetic resonance imaging of normal canine carpal ligaments.

Magnetic resonance imaging was conducted on previously frozen left carpi from six normal dogs using a 1.5 Tesla magnet in combination with a transmit/receive wrist coil. Three-millimeter thick T1-weighted spin-echo images and 1-mm thick T2*-weighted gradient-recalled 3-D images were obtained in dorsal and sagittal planes. Carpi were embedded, sectioned, and stained. Anatomic structures on the histologic sections were correlated with the MR images. All of the carpal ligaments plus the radioulnar articular disc and the palmar fibrocartilage were identified on MR images. The accessorio-quartile ligament, which had not been well described previously in dogs, was also identified. It originated on the accessory carpal bone and inserted on the fourth carpal bone. The T2*-weighted gradient echo imaging technique provided better images than T1-weighted technique, largely because thinner slices were possible (1 mm vs. 3 mm), resulting in less volume averaging of thin ligaments with surrounding structures. Although MRI is currently the imaging modality of choice to identify ligamentous injury in humans, further studies are needed to determine if abnormalities can be detected in canine carpal ligaments using MRI.

Animals↗
PubMed2000

A hybrid, inverse approach to the design of magnetic resonance imaging magnets.

This paper describes a hybrid numerical method of an inverse approach to the design of compact magnetic resonance imaging magnets. The problem is formulated as a field synthesis and the desired current density on the surface of a cylinder is first calculated by solving a Fredholm equation of the first kind. Nonlinear optimization methods are then invoked to fit practical magnet coils to the desired current density. The field calculations are performed using a semi-analytical method. The emphasis of this work is on the optimal design of short MRI magnets. Details of the hybrid numerical model are presented, and the model is used to investigate compact, symmetric MRI magnets as well as asymmetric magnets. The results highlight that the method can be used to obtain a compact MRI magnet structure and a very homogeneous magnetic field over the central imaging volume in clinical systems of approximately 1 m in length, significantly shorter than current designs. Viable asymmetric magnet designs, in which the edge of the homogeneous region is very close to one end of the magnet system are also presented. Unshielded designs are the focus of this work. This method is flexible and may be applied to magnets of other geometries.

Algorithms↗
PubMed2005

MRI evaluation of the uterine structure after myomectomy.

Myomectomy is a good indication for women with uterine leiomyoma who desire to preserve their child-bearing potential. However, there are still no reports about how long it takes the uterus to reach a stable state after myomectomy. We evaluated the changes in uterine structure during the recovery process after myomectomy by MR images. MR images were used to analyze the time-dependent changes in the length of the uterine cavity, the volume of the uterus, recovery of the junctional zone, prevalence of modification of the endometrium, and uterine structure in the region of the enucleated myoma. The cavity length and the volume of the uterus, and the myometrium were stabilized at six weeks after the myomectomy. With regard to the endometrium, 12 weeks were required for it to achieve a stable state after myomectomy. However, even at 12 weeks postoperatively, 14.2% of the cases showed an unusual view near the uterine incision on MR images. We concluded that the recovery process is complete at 12 weeks after the operation if there are no clear findings of hematoma or edema formation in the myometrium on MR images.

Adult↗
PubMed1993

Idiopathic hypothalamus-pituitary dysfunction: review of five cases.

We describe 5 children, 4 girls, aged 4-14 years with evolving hypothalamic-pituitary dysfunction. They had presenting features, isolated or combined, of polyuria and polydipsia (n = 3), weight gain and hyperphagia (n = 3), and growth failure (n = 1). During periods of 1-5 years per child, the following abnormalities developed: diabetes insipidus (n = 5), osmoreceptor dysfunction (hypernatraemia with absent thirst) (n = 3), hyperprolactinaemia (n = 3), growth hormone (GH) deficiency (n = 4, of whom 3 had normal linear growth), ACTH deficiency (n = 2), TSH deficiency (n = 2) and precocious puberty (n = 1, female). In 2 patients, high-resolution CT scans and MRI showed structural lesions of the hypothalamus 1.5 and 3.5 years after presentation. These were inaccessible and not biopsied. Scans in the remainder were normal. In conclusion, weight gain, impaired thirst, and hyperprolactinaemia were early features of evolving hypothalamic-pituitary dysfunction, and occurred with diabetes insipidus, accompanied by progressive anterior pituitary deficiencies. Pituitary hormone replacement with clinical and neuroradiological surveillance is important in any child with symptoms suggestive of an evolving hypothalamic lesion.

Adolescent↗
PubMed2003

Activation and functional significance of the renin-angiotensin system in mice with cardiac restricted overexpression of tumor necrosis factor.

BACKGROUND: The functional significance of cross-regulation between the renin-angiotensin system (RAS) and tumor necrosis factor (TNF) has been established in nonmyocyte cell types; however, the degree and functional significance of the interaction between RAS and TNF has not been characterized in the heart. METHODS AND RESULTS: We examined the expression of components of the RAS in a line of transgenic mice (MHCsTNF) with cardiac restricted overexpression of TNF. When examined at 4, 8, and 12 weeks of age, the MHCsTNF mice had increased activation of myocardial RAS, as shown by an increase in ACE mRNA level and ACE activity and increased angiotensin II peptide levels. Furthermore, myocardial angiotensin receptor mRNA and protein levels were reduced in the MHCsTNF mice, consistent with homologous desensitization of the receptors. However, expression of renin and angiotensinogen was not increased in MHCsTNF mice compared with littermate controls. To determine the functional significance of RAS activation in the MHCsTNF mice, we treated the mice with an angiotensin type I receptor antagonist, losartan (30 mg/kg), or diluent from 4 to 8 weeks of age. Analysis of cardiac structure with MRI showed that treatment with losartan normalized left ventricular mass and wall thickness. Furthermore, treatment with losartan reduced myocardial collagen content and reduced the incidence of myocyte apoptosis. CONCLUSIONS: Taken together, these results show that there are functionally significant interactions between RAS and TNF in the heart and that these interactions play an important role in the development and progression of left ventricular remodeling.

Age Factors↗
PubMed1998

Clinical determinants of poststroke dementia.

BACKGROUND AND PURPOSE: Frequency of poststroke dementia is high, and stroke considerably increases the risk of dementia. The risk factors for dementia related to stroke are still incompletely understood. We sought to examine clinical determinants of poststroke dementia in a large well-defined stroke cohort. METHODS: The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischemic stroke completed a comprehensive neuropsychological test battery and MRI, including structured medical, neurological, and laboratory evaluations; clinical mental status examination; interview of a knowledgeable informant; detailed history of risk factors; and evaluation of stroke type, localization, and syndrome. The DSM-III definition for dementia was used. RESULTS: Frequency of any poststroke dementia was 31.8% (107/337), that of stroke-related dementia (mixed Alzheimer's disease plus vascular dementia excluded) was 28.4% (87/306), and that of dementia after first-ever stroke was 28.9% (79/273). The patients with poststroke dementia were older and more often had a low level of education, history of prior cerebrovascular disease and stroke, left hemispheric stroke (reflecting laterality), major dominant stroke syndrome (reflecting laterality and size), dysphasia, gait impairment, and urinary incontinence. The demented patients were also more frequently current smokers, had lower arterial blood pressure values, and more frequently had an orthostatic reaction compared with the nondemented stroke patients. The correlates of dementia in logistic regression analysis were dysphasia (odds ratio [OR], 5.6), major dominant stroke syndrome (OR, 5.0), history of prior cerebrovascular disease (OR, 2.0), and low educational level (OR, 1.1). When we excluded those with cerebrovascular disease plus Alzheimer's disease or those with recurrent stroke, the order of correlates remained the same. When the patients with dysphasia (n=30) were excluded, the correlates were major dominant syndrome (OR, 4.6) and low educational level (OR, 1.1). CONCLUSIONS: Our data suggest that a single explanation for poststroke dementia is not adequate; rather, multiple factors including stroke features (dysphasia, major dominant stroke syndrome), host characteristics (educational level), and prior cerebrovascular disease each independently contribute to the risk.

Age Factors↗