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At least 19 recordsLinked to original sources
PubMed2004

Neuroimaging and presurgical evaluation of symptomatic epilepsies.

The goal of presurgical evaluation of intractable epilepsy is to identify epileptogenic regions in the brain. From our experience of 38 cases of resective epilepsy surgery from the last 3 years, ictal SPECT was considered the most sensitive at detecting focal changes relating to seizures compared to other neuroimaging modalities, such as MRI, FDG-PET, SPECT and MEG. At interictal state, on the other hand, FDG-PET was most sensitive, especially in cases with focal cortical dysplasia, which is often MRI-invisible. In dysplastic tumors, MRI showed the highest concordance rate to clinically verified epileptogenic regions. Activation studies using functional neuroimaging such as PET and fMRI is useful to evaluate brain functions at epileptogenic regions presurgically. The role of functional brain imaging in epilepsy surgery is considered to be: (i). case selection for resective surgery, (ii). case selection for invasive EEG monitoring, and (iii). navigation of electrode placement and cortical resection.

Brain↗
PubMed2024

Histopathologic Features and Transcriptomic Signatures Do Not Solve the Issue of Magnetic Resonance Imaging-Invisible Prostate Cancers: A Matched-Pair Analysis.

BACKGROUND: Multiparametric magnetic resonance imaging (mpMRI) is pivotal in prostate cancer (PCa) diagnosis, but some clinically significant (cs) PCa remain undetected. This study aims to understand the pathological and molecular basis for csPCa visibility at mpMRI. METHODS: We performed a retrospective matched-pair cohort study, including patients undergoing radical prostatectomy (RP) for csPCa (i.e., ISUP grade group ≥ 2) from 2015 to 2020, in our tertiary-referral center. We screened for inclusion in the "mpMRI-invisible" cohort all consecutive men (N = 45) having a negative preoperative mpMRI. The "mpMRI-visible" cohort was matched based on age, PSA, prostate volume, ISUP grade group. Included patients underwent radiological and pathological open-label revisions and characterization of the tumor mRNA expression profile (analyzing 780 gene transcripts, signaling pathways, and cell-type profiling). We compared the clinical-pathological variables and the gene expression profile between matched pairs. The analysis was stratified according to histological characteristics and lesion diameter. RESULTS: We included 34 patients (17 per cohort); mean age at RP and PSA were 70.5 years (standard deviation [SD] = 7.7), 7.1 ng/mL (SD = 3.3), respectively; 65% of men were ISUP 2. Overall, no significant differences in histopathological features, tumor diameter and location, mRNA profile, pathways, and cell-type scores emerged between cohorts. In the stratified analysis, an upregulation of cell adhesion and motility, of extracellular matrix remodeling and of metastatic process pathways was present in specific subgroups of mpMRI-invisible cancers. CONCLUSIONS: No PCa pathological or gene-expression hallmarks explaining mp-MRI invisibility were identified. Aggressive features can be present both in mpMRI-invisible and -visible tumors.

Humans↗
PubMed2001

Development of growth hormone and adrenocorticotropic hormone deficiencies in patients with prenatal or perinatal-onset hypothalamic hypopituitarism having invisible or thin pituitary stalk on magnetic resonance imaging.

A gradual loss of anterior pituitary hormones is suspected in patients treated with irradiation due to brain tumors. Development of growth hormone deficiency (GHD) with age has been documented in patients with idiopathic GHD. A gradual loss of adrenocorticotropic hormone (ACTH) secretion has been also shown in a patient with severe GHD and an invisible pituitary stalk on magnetic resonance imaging (MRI). The purpose of this longitudinal and cross-sectional study was to evaluate the gradual loss of growth hormone (GH) and ACTH in a homogeneous group of patients with hypopituitarism. Twenty-eight patients (23 males, 5 females) from four hospitals were diagnosed as having prenatal or perinatal-onset hypothalamic hypopituitarism. They had an abnormal pituitary stalk on MRI (invisible in 18 patients, thin in 10 patients) without any other organic disease of the brain. Each patient had GHD upon initial evaluation. Height (n=20) was analyzed as standard deviation score (SDS). Longitudinal (n=8) and cross-sectional (n=28) GH secretion capacity was evaluated by GH peaks, in response to insulin tolerance test (ITT) and growth hormone releasing factor test (GRF test). Longitudinal (n=10) and cross-sectional (n=28) ACTH secretion capacity was evaluated by cortisol peaks in response to ITT. Height SDS decreased each year in all the untreated patients after birth. GH peaks decreased gradually with age. Longitudinal data showed decreased GH peaks with age in seven out of eight patients using ITT and in all four patients using GRF tests. Cortisol peaks also decreased gradually together with signs and symptoms for adrenal deficiency such as general fatigue. Cortisol peaks of less than 414 nmol/L (15 microg/dl) in response to ITT were seen in 24% of the tests before age 10 and 56% before age 25. In conclusion, GHD and ACTH deficiency developed gradually in patients with prenatal or perinatal-onset hypothalamic hypopituitarism who had invisible or thin pituitary stalks examined by MRI.

Adolescent↗
PubMed1994

Vascular interventions guided by ultrafast MR imaging: evaluation of different materials.

The ability of MRI to acquire not only anatomical but also functional information makes MRI guided vascular interventions an interesting goal. Recent developments in ultrafast MR imaging sequences such as fast gradient echo or echo planar (EPI) mean that not only real time MRI but also MRI guided vascular interventions are real possibilities for the not too distant future. However, currently available guide wires and catheters are potentially unusable in MRI because they are either ferromagnetic or MRI invisible. In order to find different materials suitable for real time MRI, various devices were examined with fast gradient echo and interleaved EPI pulse sequences. The measurements were performed using a continuously running, pseudo real time MRI system to investigate the dynamic imaging behavior under guide wire insertion. Suggestions are made as how to construct guide wires and catheters, which can be visualized with ultrafast imaging sequences, while not causing prohibitive artifacts or image distortions.

Alloys↗
PubMed2004

MRI detection of early endothelial activation in brain inflammation.

MRI is an increasingly important clinical tool, but it is clear that conventional imaging fails to identify the full extent of lesion load in certain conditions, such as multiple sclerosis. The aim of this study was to determine whether a novel contrast agent (Gd-DTPA-B(sLeX)A, which contains an sLeX mimetic moiety that enables it to bind to the adhesion molecule E-selectin) can be used to identify endothelial activation in the brain. Microinjection of the proinflammatory cytokines IL-1beta or TNF-alpha into the striatum of Wistar rats rapidly induces focal adhesion molecule expression on the endothelium in the absence of MRI-visible changes. This phenomenon was used to investigate the potential of Gd-DTPA-B(sLeX)A to reveal MRI-invisible brain pathology. T1-weighted serial images were acquired in anesthetized animals before and after administration of Gd-DTPA-B(sLeX)A, 3-4 hr after cytokine was injected intracerebrally. Both TNF-alpha and IL-1beta up-regulated E-selectin on the brain endothelium, which correlated with increased signal intensity observed after administration of the novel contrast agent. No enhancement was visible with the nonselective contrast agent Gd-DTPA-BMA, indicating that there was no leakage of the agent across the blood-brain barrier (BBB) or nonselective binding to the endothelium. These data demonstrate the potential of such contrast agents for the early detection of brain injury and inflammation.

Animals↗
PubMed2005

Swallowing therapy--a prospective study on patients with neurogenic dysphagia due to unilateral paresis of the vagal nerve, Avellis' syndrome, Wallenberg's syndrome, posterior fossa tumours and cerebellar hemorrhage.

BACKGROUND: No studies exist dealing with the outcome of dysphagic patients with posterior fossa (IV. ventricle) tumours (PFT) or cerebellar hemorrhage (CH), and the outcome of patients with Wallenberg's syndrome (WS) after functional swallowing therapy (FST) has so far not been studied in detail. Patients and methods. 208 patients with neurogenic dysphagia (ND) who were consecutively admitted for functional swallowing therapy (FST) over a 3 year period to our hospital were examined clinically, by use of a videofluoroscopic swallowing study (VFSS) and/or fibreoptic evaluation of swallowing (FEES). The most frequent etiology was stroke (48%), followed by CNS tumours (13%). In the present study we defined three groups. Group 1 comprised 8 patients with PFT or CH. Group 2 consisted of 27 patients with WS, which was the leading cause among patients with non-hemispheric stroke. Since in WS a vagal nerve paresis due to affection of the Nucleus ambiguus occurs, 8 patients with Avellis' syndrome or unilateral paresis of the vagal nerve served as controls and were defined as group 3. Findings. In the three groups, functional feeding status showed significant improvement after FST comprising methods of restitution, compensation and adaptation, each of which were applied in more than 80% of patients. Outcome was, however, significantly worse in group 1 as compared to group 2 and in group 2 as compared to group 3. Dysfunction of the upper esophageal sphincter and reflex triggering were significantly more severely disturbed in groups 1 and 2 as compared to group 3. Group 1 showed significantly more severe disturbances of the oral phase as compared to groups 2 and 3. After FST, more than 50% (5/8) of group 1 and 30% (8/27) of WS patients (group 2) were dependent on tube feeding, whereas all patients of group 3 were full-oral feeders. Interpretation. This is the first study dealing with the outcome of dysphagic patients with PFT or CH. Based on our results it can be assumed that in these patients pressure is exerted on both dorsomedial central pattern generators (DMCPGs) for swallowing in a posterior-anterior direction. Due to the importance of the DMCPGs for swallowing, bilateral (and often MRI-invisible) lesions seem to be very harmful. For a better understanding of the pathomechanism responsible for ND in patients with PFT or CH, modern imaging methods such as proton magnetic resonance spectroscopy should be used for studying metabolic changes in the dorsal medulla in the future. Since the outcome of patients with WS with regard to dependence of tube feeding was not associated with the site or size of the lesion, it may due to the individual asymmetry of the swallowing-dominant forebrain hemisphere - depend on the side of the medullary infarction.

Adult↗
PubMed2006

Assessment of absolute blood volume in carcinoma by USPIO contrast-enhanced MRI.

OBJECTIVES: The characterization of tumor vasculature is essential in studying tumor physiology. The aim of this study was to develop a new method - based on water proton MR density measurements, in combination with ultrasmall superparamagnetic iron oxide (USPIO) administration - to measure absolute blood volume (BV) in murine colon carcinoma. MATERIALS AND METHODS: MRI experiments were performed at 7 T. CPMG imaging was performed on subcutaneous murine colon carcinoma in six mice before and after administration of an USPIO blood-pool contrast agent. Density maps were obtained from the signal amplitude at TE=0 of the CPMG decay fit. Post-USPIO density maps were subtracted from pre-USPIO density maps to quantitatively yield absolute tumor BV maps. In a separate group of mice (n=6), the relative vascular area (RVA) of tumors was determined by immunohistochemistry. RESULTS: Ultrasmall superparamagnetic iron oxide administration resulted in a small decrease in the water proton MR density. The BV averaged over the six tumors was 4.6+/-1.6%. The value of the RVA measured by immunohistochemical staining was equal to 3.9+/-2.2%. CONCLUSIONS: After administration of an USPIO blood-pool agent (T(2) relaxivity > 100 mM(-1) s(-1)), the blood water protons become MRI invisible, and pixel-by-pixel BV map can be obtained by subtracting the calculated post-USPIO density map from the pre-USPIO density map. The value of absolute BV obtained with this novel MR approach is in good agreement with the value of the relative vascular measured by immunohistochemical staining.

Animals↗
PubMed1993

Sequential changes on 23Na MRI after cerebral infarction.

23Na MRI changes from the acute to chronic phase were investigated in seven patients with cerebral infarcts. They showed no signal increase during the first 13 h after the stroke and revealed a definite signal increase thereafter. This reached a maximum 45-82 h after stroke and became slightly less marked in the subacute and chronic phases, probably as a result of disappearance of cerebral oedema. In the early acute phase of stroke, 23Na MRI appears to fail to demonstrate Na+ increases in the ischaemic area, due presumably to the invisibility on MRI of intracellular 23Na in the intact brain. The increase more than 13 h after stroke, during which ischaemic cells are likely to die, is presumably because of increased visibility of intracellular 23Na in the dead cells. 23Na MRI is apparently insensitive to early ischaemic changes, but may be useful for assessing the cell viability in the ischaemic brain.

Aged↗
PubMed2004

Primary hypothalamic lymphoma with panhypopituitarism presenting as stiff-man syndrome.

We report an unusual case of primary hypothalamic lymphoma with hypopituitarism presenting as Stiff-man syndrome (SMS). A 64-year-old man was hospitalized due to a 3-week history of general weakness, anorexia, vomiting, weight loss, and muscle pain and spasms precipitated by motion and tactile stimuli resulting in muscle stiffness and difficulty in mobility. Physical examination revealed normal sensorimotor function and reflexes, except for bitemporal visual field defect. Routine laboratory and gastrointestinal examinations provided no remarkable clues. Endocrine assessment revealed low levels of morning cortisol, thyroxine, and anterior pituitary hormones but an increase in prolactin level. The patient's muscle pain and stiffness improved dramatically within 2 days after hydrocortisone therapy and thyroxine replacement. Magnetic resonance imaging (MRI) of the brain confirmed an 18-mm enhancing hypothalamic tumor with optic chiasm involvement, which proved to be a B-cell lymphoma. The results of the extensive studies for systemic lymphoma were negative, suggesting a primary hypothalamic lymphoma. The tumor regressed completely and was invisible on MRI scan after adjuvant radiotherapy. The patient's condition was satisfactory and there was no recurrence of SMS during the 2-year follow-up period. This case demonstrated that primary hypothalamic lymphoma complicated with adrenal insufficiency may manifest as SMS. Early diagnosis and prompt intervention can lead to a favorable outcome and reduce morbidity.

Adrenal Insufficiency↗
PubMed2005

Noninvasive in vivo MRI detection of neuritic plaques associated with iron in APP[V717I] transgenic mice, a model for Alzheimer's disease.

Transgenic mice overexpressing the London mutant of human amyloid precursor protein (APP[V717I]) in neurons develop amyloid plaques in the brain, thus demonstrating the most prominent neuropathological hallmark of Alzheimer's disease. In vivo 3D T2*-weighted MRI on these mice (24 months of age) revealed hypointense brain inclusions that affected the thalamus almost exclusively. Upon correlating these MRI observations with a panel of different histologic staining techniques, it appeared that only plaques that were positive for both thioflavin-S and iron were visible on the MR images. Numerous thioflavin-S-positive plaques in the cortex that did not display iron staining remained invisible to MRI. The in vivo detection of amyloid plaques in this mouse model, using the intrinsic MRI contrast arising from the iron associated with the plaques, creates an unexpected opportunity for the noninvasive investigation of the longitudinal development of the plaques in the same animal. Thus, this work provides further research opportunities for analyzing younger APP[V717I] mouse models with the knowledge of the final outcome at 24 months of age.

Alzheimer Disease↗
PubMed2006

Are bone erosions detected by magnetic resonance imaging and ultrasonography true erosions? A comparison with computed tomography in rheumatoid arthritis metacarpophalangeal joints.

The objective of the study was, with multidetector computed tomography (CT) as the reference method, to determine whether bone erosions in rheumatoid arthritis (RA) metacarpophalangeal (MCP) joints detected with magnetic resonance imaging (MRI) and ultrasonography (US), but not with radiography, represent true erosive changes. We included 17 RA patients with at least one, previously detected, radiographically invisible MCP joint MRI erosion, and four healthy control individuals. They all underwent CT, MRI, US and radiography of the 2nd to 5th MCP joints of one hand on the same day. Each imaging modality was evaluated for the presence of bone erosions in each MCP joint quadrant. In total, 336 quadrants were examined. The sensitivity, specificity and accuracy, respectively, for detecting bone erosions (with CT as the reference method) were 19%, 100% and 81% for radiography; 68%, 96% and 89% for MRI; and 42%, 91% and 80% for US. When the 16 quadrants with radiographic erosions were excluded from the analysis, similar values for MRI (65%, 96% and 90%) and US (30%, 92% and 80%) were obtained. CT and MRI detected at least one erosion in all patients but none in control individuals. US detected at least one erosion in 15 patients, however, erosion-like changes were seen on US in all control individuals. Nine patients had no erosions on radiography. In conclusion, with CT as the reference method, MRI and US exhibited high specificities (96% and 91%, respectively) in detecting bone erosions in RA MCP joints, even in the radiographically non-erosive joints (96% and 92%). The moderate sensitivities indicate that even more erosions than are seen on MRI and, particularly, US are present. Radiography exhibited high specificity (100%) but low sensitivity (19%). The present study strongly indicates that bone erosions, detected with MRI and US in RA patients, represent a loss of calcified tissue with cortical destruction, and therefore can be considered true bone erosions.

Adult↗
PubMed2002

Late onset of adrenocortical failure in GH deficiency with invisible pituitary stalk: a case report of a 48-year-old Japanese man and review of the literature.

ACTH deficiency gradually develops in patients with growth hormone deficiency (GHD) who have abnormalities of the pituitary stalk on magnetic resonance imaging (MRI) following perinatal complications. We report here a rare case of GHD manifesting ACTH deficiency in middle age. A 48-year-old male patient was admitted to our hospital due to fever and hyponatremia. He was diagnosed as GHD and hypothyroidism at the age of 9, and had received lysine treatment until age 20, which was then replaced by thyroid hormone. He was not mentally retarded, but was the shortest in his class throughout his schooldays, reaching a final height of 148 cm. Hormonal examination revealed the presence of hypoadrenalism as indicated by poor responses of plasma cortisol to intravenous administration of corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia. Plasma ACTH responded well to CRH, but not to insulin-induced hypoglycemia, indicating that his hypoadrenalism was of hypothalamic origin. MRI showed an invisible pituitary stalk and relatively small pituitary gland. Since he had a perinatal abnormality, the damage around the pituitary and GHD could have originated from birth. In the literature, around 60% of GHD patients with pituitary stalk abnormalities develop hypoadrenalism due to ACTH deficiency, and more than 90% of such cases are diagnosed by age 30. We suggest that the appearance of hypoadrenalism should be carefully monitored in GHD patients with pituitary stalk abnormalities even after they reach middle age.

Adrenocorticotropic Hormone↗
PubMed1999

Profound hearing loss attributable to cochlear nerve disease: diagnosis with combination of otoacoustic emission and magnetic resonance imaging.

OBJECTIVE: To detect the causes of deafness based on the combined findings of auditory brainstem response (ABR), distortion product otoacoustic emissions (DPOAEs), and three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) magnetic resonance imaging (MRI). STUDY DESIGN: Retrospective review of the medical records of 13 patients with unilateral profound hearing loss since childhood. METHODS: Subjects were tested with pure-tone audiometry, ABR, DPOAEs, and 3DFT-CISS imaging. RESULTS: No significant components of ABR were observable in any of the deaf ears. In 10 cases, the cochlear nerves of the deaf ears were found to be as normal as the healthy sides by 3DFT-CISS imaging, and no significant levels of DPOAEs were recorded. In the other three cases, no apparent cochlear nerves were identified by 3DFT-CISS imaging. Although no significant levels of DPOAEs were observable in two cases with cochlear nerves invisible by the MRI study, almost the same level of DPOAEs as that in the healthy side was recorded in the last case. CONCLUSIONS: In the last particular case, the cochlear nerve seemed to be mainly responsible for the profound deafness. 3DFT-CISS imaging in combination with preexisting audiological measures may provide direct evidence for the cochlear nerve disease. steady state, internal auditory canal, cochlear nerve disease.

Audiometry, Pure-Tone↗
PubMed2000

Assessment of the damage of the cerebral hemispheres in MS using neuroimaging techniques.

The pattern of mental dysfunction in multiple sclerosis (MS) is characteristic of the so-called subcortical dementia. Cognitive dysfunction results predominantly by the disruption of communication among cortical and subcortical areas, as a consequence of the white matter damage. As expected, studies with conventional magnetic resonance imaging (MRI) demonstrated that cognitive impairment in MS patients is related to the lesion burden, although the strength of this correlation is weak. This can be partially explained by the poor pathological specificity of conventional MRI techniques and by the invisible damage in the normal-appearing white matter (NAWM). Recent studies using non-conventional MRI techniques with a higher specificity for the heterogeneous substrates of MS pathology, such as the assessment of hypointense lesion load on T1-weighted scans and the measurement of the magnetization transfer ratio (MTR) of whole brain, MS lesions and NAWM, support this interpretation. Other factors, such as the site of MS lesions and the presence of active inflammation, also seem to play an important role.

Brain Diseases↗
PubMed1992

The association of hypopituitarism with small pituitary, invisible pituitary stalk, type 1 Arnold-Chiari malformation, and syringomyelia in seven patients born in breech position: a further proof of birth injury theory on the pathogenesis of "idiopathic hypopituitarism".

We report seven cases of hypopituitarism all having a history of breech delivery, asphyxia at birth, and syringomyelia. A small pituitary gland was found on MRI or CT in six cases, invisible pituitary stalk on MRI in five cases, and type 1 Arnold-Chiari malformation in six cases. A constellation of these abnormalities are best explained by traction of brain and spinal cord of the subjects exerted during breech delivery and further support the primary role of birth trauma in the genesis of "idiopathic hypopituitarism".

Adolescent↗
PubMed2005

Retrospective cross-evaluation of an histological and deformable 3D atlas of the basal ganglia on series of Parkinsonian patients treated by deep brain stimulation.

In functional neurosurgery, there is a growing need for accurate localization of the functional targets. Since deep brain stimulation (DBS) of the Vim thalamic nucleus has been proposed for the treatment of Parkinson's disease, the target has evolved toward the globus pallidus and subthalamic nucleus (STN) and the therapeutic indications have enlarged to include psychiatric disorders such as Tourette syndrome or obsessive compulsive disorders. In these pathologies, the target has been restrained to smaller functional subterritories of the basal ganglia, requiring more refined techniques to localize smaller and smallerbrain regions, often invisible in routine clinical MRI. Different strategies have been developed to identify such deep brain targets. Direct methods can identify structures in the MRI itself, but only the larger ones. Indirect methods are based on the use of anatomical atlases. The present strategy comprised a 3D histological atlas and the MRI of the same brain specimen, and deformation methodology developped to fit the atlas toward the brain of any given patient. In this paper, this method is evaluated in the aim of being applied to further studies of anatomo-clinical correlation. The accuracy of the method is first discussed, followed by the study of short series of Parkinsonian patients treated by DBS, allowing to compare the deformed atlas with various per- and post-operative data.

Basal Ganglia↗
PubMed2003

Acquired cerebellar cavernous angioma following childhood radiotherapy in a patient with neurofibromatosis type 1.

We report the unusual case of a patient with neurofibromatosis type I, who was irradiated 16 years previously for a mesencephalic glioma causing hydrocephalus, and who developed a cerebellar haemorrhage caused by a histologically confirmed cavernous angioma, that was invisible on several earlier MRI scans. The different hypotheses concerning the de novo formation of cavernous angiomas (venous obstructive disease and genetic abnormalities) are succinctly reviewed.

Adolescent↗