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Results for “Structural MRI”

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At least 1,441 records · Page 80Linked to original sources
PubMed2004

Histologic findings in patients with clinical and instrumental diagnosis of sporadic arrhythmogenic right ventricular dysplasia.

OBJECTIVES: We sought to analyze the histologic findings of 30 patients with a diagnosis of arrhythmogenic right ventricular dysplasia (ARVD) based on established clinical and instrumental criteria, who did not have a family history of ARVD. BACKGROUND: The diagnostic role of endomyocardial biopsy (EMB) in patients with a clinical profile of ARVD is still debated. METHODS: Thirty patients (19 male, 11 female, mean age 27 +/- 10 years) with left bundle branch block morphology ventricular tachyarrhythmias and echocardiographic, angiographic, and magnetic resonance imaging (MRI) findings diagnostic of ARVD were studied. All patients, besides diagnostic, noninvasive, and invasive cardiac studies, underwent EMB in the apex, anterior free wall, inferior wall of the right ventricle (RV) and in the septal-apical region of the left ventricle. RESULTS: Diagnostic histologic features of ARVD were found only in 9 (30%) patients and a myocarditis, according to the Dallas criteria, in the remaining 21 (70%) patients. Morphometric evaluation of RV samples showed significant differences in fatty tissue and myocyte percent area between ARVD and myocarditis (p < 0.001). Conversely, no difference was found between the two groups in arrhythmic patterns and structural and functional echocardiographic, angiographic, and MRI RV alterations. Magnetic resonance imaging showed hyperintense signals in 67% of ARVD and in 62% of myocarditis group (p = NS). During follow-up (mean, 23 +/- 14 months), all patients with myocarditis remained stable on antiarrhythmic therapy while five patients with ARVD required implantation of an implantable cardioverter defibrillator. CONCLUSIONS: A myocarditis involving the RV can mimic ARVD. An EMB appears the most reliable diagnostic technique, with significant prognostic and therapeutic implications.

Adolescent↗
PubMed2005

In vivo 3D MRI of insect brain: cerebral development during metamorphosis of Manduca sexta.

High-resolution 3D MRI of male pupae of Manduca sexta was performed at 2.35 T in order to evaluate its potential for an in vivo characterization of insect brain during metamorphosis. T1-weighted 3D FLASH (TR/TE = 20/7.8 ms, 25 degrees flip angle) and T2-weighted 3D fast SE MRI data sets (TR/TEeff = 3000/100 ms) were acquired at different developmental stages with an isotropic resolution of 100 microm. Both T1- and T2-weighted 3D MRI allowed for the identification of cerebral structures such as the antennal nerve, antennal and optical lobe, and central brain. Pronounced developmental alterations of the morphology were observed during metamorphosis. The results demonstrate the feasibility of 3D MRI at nanoliter resolution to identify major brain systems of M. sexta and respective changes during pupal development from caterpillar to sphinx moth. Together with the use of suitable contrast agents, this approach may provide new ways for studying the axonal connectivity and neural function of the developing insect brain.

Animals↗
PubMedDate not supplied

Magnetic resonance imaging of a choroid plexus carcinoma and meningeal carcinomatosis in a dog.

A 6-year-old neutered female Boston Terrier had a slow onset of blindness and behavior changes. Neurologic abnormalities included bilateral visual loss with absent menace responses and visual tracking, mydriatic pupils, slow pupillary light responses and papilledema. On magnetic resonance imaging (MRI) there were multiple cyst-like structures found in the parenchyma of the cerebrum, cerebellum and brainstem. Histopathologically the diagnosis was a choroid plexus carcinoma with meningeal carcinomatosis. The findings differ from previous descriptions of the MRI characteristics of choroid plexus tumors.

Animals↗
PubMed1999

[Analysis of MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos].

OBJECTIVE: To study the MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos. METHODS: MRI and CT scans of 51 patients were examined. RESULTS: MRI offers more information for evaluation of soft tissue lesions; the cavernous hemangioma and dermoid cyst were found to present rather characteristic images. Whereas in evaluation of lesions involving bony structures and calcifications, CT was superior to MRI. CONCLUSION: CT and MRI may evaluate the tumor location, extension into adjacent areas and are valuable in differential diagnosis of paranasal sinuses and orbitocranial disorder with secondary exophthalmos.

Adolescent↗
PubMed2006

Reduced size of the pre-supplementary motor cortex and impaired motor sequence learning in first-episode schizophrenia.

Increasing evidence suggests that schizophrenia is associated with various morphological and functional abnormalities of the frontal cortex. So far research has concentrated on the dorsolateral and orbitofrontal cortex. Behavioral evidence suggests however that regions responsible for higher motor control are compromised in schizophrenia as well. The current study assessed volumes of the anterior supplementary motor area (pre-SMA) and implicit motor sequence learning in 15 subjects with first-episode schizophrenia and 15 healthy matched controls. Pre-SMA volumes were assessed by three-dimensional structural magnetic resonance imaging (3D-MRI) and manual parcellation according to an established protocol. Implicit motor sequence learning was assessed using the Serial Reaction-Time Task (SRTT). Compared with control subjects, schizophrenia subjects had significantly smaller volumes of the left pre-SMA (16%). Subjects with schizophrenia were severely impaired on sequence-specific implicit motor learning. Size of the left pre-SMA of schizophrenia subjects was significantly related to impaired implicit learning. We conclude that subjects with first-episode schizophrenia have a morphological abnormality of the left pre-SMA that might predispose them to develop disturbances of higher motor control during acute episodes of psychosis. These structural and behavioral abnormalities might be conceptualized within a broader model that views schizophrenia as a disorder of disturbed coordination of thought and action.

Adult↗
PubMed2005

Early changes of cardiac structure and function in COPD patients with mild hypoxemia.

BACKGROUND: COPD is often associated with changes of the structure and the function of the heart. Although functional abnormalities of the right ventricle (RV) have been well described in COPD patients with severe hypoxemia, little is known about these changes in patients with normoxia and mild hypoxemia. STUDY OBJECTIVES: To assess the structural and functional cardiac changes in COPD patients with normal Pa(O2) and without signs of RV failure. METHODS: In 25 clinically stable COPD patients (FEV1, 1.23 +/- 0.51 L/s; Pa(O2), 82 +/- 10 mm Hg [mean +/- SD]) and 26 age-matched control subjects, the RV and left ventricular (LV) structure and function were measured by MRI. Pulmonary artery pressure (PAP) was estimated from right pulmonary artery distensibility. RESULTS: RV mass divided by RV end-diastolic volume as a measure of RV adaptation was 0.72 +/- 0.18 g/mL in the COPD group and 0.41 +/- 0.09 g/mL in the control group (p < 0.01). LV and RV ejection fractions were 62 +/- 14% and 53 +/- 12% in the COPD patients, and 68 +/- 11% and 53 +/- 7% in the control subjects, respectively. PAP estimated from right pulmonary artery distensibility was not elevated in the COPD group. CONCLUSION: From these results, we conclude that concentric RV hypertrophy is the earliest sign of RV pressure overload in patients with COPD. This structural adaptation of the heart does not alter RV and LV systolic function.

Aged↗
PubMed2000

Hippocampal and cerebellar volumetry in serially acquired MRI volume scans.

In this work, we describe methodologies for serial volumetric measurements of hippocampi and cerebella. Serial scans were co-registered and intensity matched prior to the volumetric measurements. Manual drawing was used to define the boundaries of the hippocampi. For the cerebellar volumetric measurements, the brain was automatically segmented from the co-registered scans; manual drawing was used to define the boundary between the cerebellum and the cerebrum and brainstem. The operator was blinded to the nature of the subject (patient or normal control) and the chronological order of the scans. The coefficient of reliability of hippocampal volume measurements in a group of 20 controls was 0.078 cm(3) (3.1% of the mean baseline volume); for the cerebellum, the value was 3.8 cm(3) (3.0% of the mean baseline volume). We conclude that the methods presented are valid and that the software provides a useful integrated tool for the quantitative analysis of structural changes in serially acquired volume MRI data in prospective, blinded studies.

Adult↗
PubMed2005

[Nonsymptomatic changes in magnetic resonansce imaging of spine among airforce candidates].

BACKGROUND: Problems of low back and neck pain are were important for persons, who decided to participate in sport or to educate and work in jobs requiring high accelerations and loads. The aim of the study was evaluate a structure the whole spine on magnetic resonansce imaging among airforce candidates. MATERIAL AND METHODS: MRI of 98 young, healthy persons, with no abnormalities in structure and function of musclosceletal system, were analysed. RESULTS: Analysed material revealed dehydratation of intervertebral discs L4-L5 and L5-S1 among 23 persons (23.5%). In this group 21 persons (22%) had protrusions, while Schmorl nodules were present among 14 (14.7%) persons. Only one persons had protrusion in cervical spine. Candidates who had changes in MRI were excluded from futher qualifying selection. An exeption was Schmorl nodules in thoracal spine due to good stabilisation of this part of spine gained by rips. CONCLUSION: (1) Intervertebral disc degeneration without clinical symptoms were found among 23% examined persons and starts in second decade of life. (2) Aboved mentioned changes are a serius problem for airforce candidates. (3) Airforce candidates, who have degenerative changes in lumbar and cervical spine on MRI findings should not be exepted to futher qualifying selection.

Adult↗
PubMed2000

MRI evaluation of aseptic osteonecrosis in children over the course of hyperbaric oxygen therapy.

PURPOSE: The study aimed at MRI evaluation of aseptic osteonecrosis (AON) in children over the course of hyperbaric oxygen (HBO) therapy. MATERIAL AND METHODS: Retrospective analysis of 72 MRI studies in 20 children presenting with AON during chemotherapy. Two groups were differentiated: Gr. I (n = 8) was treated exclusively with relief of weightbearing structures, Gr. II (n = 12) was additionally treated with HBO therapy. The MRI examinations were evaluated by a point-score system (1-6 points) by two radiologists. RESULTS: Gr. II initially showed more severe findings (average score: 3.4) in comparison to Gr. I (average score: 2.65). During the follow-up time period the average scores rose to 3.2 score-points in Gr. I and 4.1 points in Gr. II. No statistically significant difference was evident between the two groups in the course of AON. CONCLUSION: The majority of chemotherapy associated AON which initially present with advanced findings show a progression in MRI over their further course. HBO therapy in addition to the relief of affected weightbearing structures statistically shows no significant improvement in MRI morphology during the course of the treatment.

Antineoplastic Agents↗
PubMedDate not supplied

High-resolution magnetic resonance imaging of the anorectal region without an endocoil.

BACKGROUND: To evaluate the feasibility of a high-resolution magnetic resonance imaging (MRI) technique in detailed imaging of the anal sphincter and lower pelvic region without the use of an endoluminal coil. METHODS: MRIs with an external phased array coil (T1- and T2-weighted turbo spin echo) were performed in 22 volunteers and 12 patients with an anal fistula, an anal sphincter defect, or a rectal tumor. The normal scans were evaluated by three independent observers. The scans of the patients were compared with surgical and/or histologic findings. RESULTS: The anal sphincter was visualized with detail. In the anal canal, hemorrhoidal tissue and the submucosae ani muscle could be seen. The MRI technique also allowed detailed imaging of anatomical structures above the pelvic floor. The MR findings in the 12 patients showed exact correlation with surgery and/or histology. CONCLUSIONS: High-resolution MRI of the anorectal region without an endoluminal coil is feasible. The MR technique with an external phased array coil allows detailed imaging of the anal sphincter at rest, the rectum, and the surrounding pelvic structures with one single investigation. The results are promising and suggest useful applications in the management of anorectal diseases.

Anal Canal↗
PubMed1998

A neuropsychological analysis of schizophrenic thought disorder.

We examined the relationship of schizophrenic thought disorder, as measured by the Thought Disorder Index (TDI), with (1) neuropsychological measures of verbal memory, abstraction, executive function, visual memory, and working memory; and (2) quantitative MRI measures of prefrontal and basal ganglia structures. TDI scores correlated strongly with tests of verbal memory, abstraction and executive functions, modestly with tests of working memory, but did not correlate with scores on tests of visual memory. Neither TDI scores nor their neuropsychological correlates were associated with frontal or basal ganglia magnetic resonance imaging (MRI) measures, with the exception of the measures of working memory that demonstrated a modest relationship with frontal and basal ganglia structures. These findings suggest that schizophrenic thought disorder may be strongly related to neuropsychological impairments in verbal memory, abstraction and executive functions, and modestly related to problems with working memory in this sample of patients.

Adult↗
PubMed2004

Heterozygous PAX6 mutation, adult brain structure and fronto-striato-thalamic function in a human family.

Recent progress in developmental neurobiology and neuroimaging can be drawn together to provide new insight into the links between genetically specified processes of embryonic brain development and adult human brain structure and function. We used magnetic resonance imaging (MRI) to show that individuals with aniridia and deficits in executive and social cognition, due to heterozygous mutation of the neurodevelopmental control gene PAX6, have structural abnormalities of grey matter in anterior cingulate cortex, cerebellum and medial temporal lobe, as well as white matter deficits in corpus callosum. Functional MRI demonstrated reduced activation of fronto-striato-thalamic systems during performance of overt verbal fluency and nonsense sentence completion; the most consistent abnormality of verbal executive activation was located in the thalamus. These results provide the first evidence for brain functional differences in humans with PAX6 mutation that are compatible both with anatomical abnormalities in the same subjects and, more circumstantially, with the known roles of murine Pax6 in regional differentiation, axonal guidance and other aspects of early forebrain development. Highly conserved homeobox genes may be critical for normal ontogenesis of large-scale neurocognitive networks supporting phylogenetically advanced mental functions.

Adolescent↗
PubMed1998

[Value of ultrasound and magnetic resonance imaging in the control of the postoperative progress after Achilles tendon rupture].

AIM: A comparison of clinical examination, sonography and MRI in the follow-up of suture of the Achilles tendon. METHOD: 60 patients were examined in a prospective study for 6-78 months following suture of the Achilles tendon repair; both sides were compared clinically and sonographically; in 30 patients MRI was also used. Morphometric measurements (antero-posterior and transverse measurements) and changes in morphological structure were correlated with clinical results. RESULTS: All patients showed thickening of the Achilles tendon postoperatively. Morphometric and morphological changes showed positive and significant correlation between sonography and MRI (p = < 0.001, p = 0.004). Structural changes in sonography had positive correlation with general symptoms (p = < 0.001), pain on movement (p = < 0.001), reduced function (p = 0.005), and reduced sporting activity (p = 0.034). MRI findings showed significant regression with time (p = 0.05). CONCLUSION: Following repair, the Achilles tendon remained thickened throughout the period of observation. Post-operative changes in the structure of the tendon regressed partially. Sonography and MRI correlate significantly with the clinical findings. Sonography is the imaging method of choice, MRI is an additional procedure.

Achilles Tendon↗
PubMed2001

Electroanatomic mapping of arrhythmogenic right ventricular dysplasia.

OBJECTIVES: We tested the hypothesis that spatial association of low-amplitude intracardiac electrograms can identify the presence, location and extent of dysplastic regions in arrhythmogenic right ventricular dysplasia (ARVD). BACKGROUND: Arrhythmogenic right ventricular dysplasia is a right ventricular (RV) cardiomyopathy characterized pathologically by fibrofatty infiltration and clinically by a spectrum of arrhythmias, sudden cardiac death and RV failure. Diagnosis of ARVD still remains a clinical challenge. METHODS: A three-dimensional electroanatomic mapping technique was used to map the RV of two groups of patients: 1) those with ARVD presenting with typical clinical, electrocardiographic and echocardiographic or magnetic resonance imaging (MRI) findings; and 2) those with structurally normal ventricles. RESULTS: The dysfunctional RV area could be identified only in the first group and was characterized by the presence of discrete areas of abnormally low-amplitude electrograms. Hence, the normal voltage values observed in the control group (unipolar: 11.9 +/- 0.3 mV; bipolar: 4.6 +/- 0.2 mV [mean +/- SEM]) and in the nonaffected zones in the ARVD group (unipolar: 10.4 +/- 0.2 mV; bipolar: 4.6 +/- 0.2 mV) were reduced significantly (p < 0.05) in the dysplastic areas (unipolar: 3.3 +/- 0.1 mV; bipolar: 0.5 +/- 0.1 mV). The pathologic process mainly involved the RV anterolateral free wall, apex and inflow and outflow tracts and ranged from patchy areas to uniform and extensive involvement. Concordance between electroanatomic findings and MRI or echocardiographic findings was noted in all patients. CONCLUSIONS: The pathologic substrate in ARVD can be identified by spatial association of low-amplitude endocardial electrograms, reflecting replaced myocardial tissue. The ability to accurately identify the presence, location and extent of the pathologic substrate may have important diagnostic, prognostic and therapeutic implications.

Adult↗
PubMed2005

Large-scale morphometric analysis of neuroanatomy and neuropathology.

Brain imaging research with MRI spans a wide area, covering both structure and function, and ranging from basic research through clinical research to drug design and clinical trials. In recent years there has been a trend towards the collection of very large MRI databases which can allow for the detection of very small group-dependent effects. However, the logistical challenges of analysing such large datasets presents new challenges. This paper describes the "pipeline" framework developed at the Montreal Neurological Institute for the fully automated morphometric analysis of large brain imaging databases. The potential use of these techniques is illustrated by examples of their applications in multiple sclerosis, Alzheimer's disease, and pediatric development.

Alzheimer Disease↗
PubMed2006

Magnetic resonance imaging of the Harderian gland in piglets.

The main purpose of the present study was to investigate the value and effectiveness of functional and morphological magnetic resonance imaging (MRI), in order to assess the extent of brain injury in a hypoxic-ischaemic piglet model, and further to validate that the ischaemic injury was successfully induced. In this way, we also characterized the Harderian gland. MRI was performed at 1.5 T in anaesthetized piglets (n = 10, 12-36 h of age). Magnetic resonance perfusion and diffusion imaging were performed at different time points, before, during and after the induction of hypoxia-ischaemia. The effects following bilateral clamping of the carotid arteries were also assessed by contrast-enhanced magnetic resonance angiography. Morphological assessment included T1- and T2-weighted imaging, and fat-suppressed T1-weighted imaging before and after contrast medium enhancement. Morphological MRI revealed a prominent, well-defined structure located at the eyeball. Magnetic resonance angiography reconstructed with volume rendering showed this structure to be partially enclosed by large venous sinuses. At dissection, when compared with the magnetic resonance images, the deep gland of the third eyelid, the Harderian gland, corresponded to this structure both in topography and in size. By contrast, the lacrimal gland proper presented as a small, soft and pale structure that was difficult to distinguish from the surrounding connective tissue. At histological examination, the Harderian gland consisted mainly of compact areas of tubuloacinar glands with abundant eosinophilic granules. The present MRI demonstration of the Harderian gland was an accidental finding during an investigation to assess the extent of brain injury in a hypoxic-ischaemic piglet model. The combination of MRI and histology made it possible to detect and describe the Harderian gland in pig. It has generally been studied in rodents and lower vertebrates and is reported to possess various endocrine and exocrine functions.

Animals↗
PubMedDate not supplied

[Magnetic resonance imaging in the diagnosis of benign renal parenchymal epithelial tumors: MRI -- pathomorphological comparison].

The study evaluates the MRI diagnostic value in the discovery and characterization of the benign epithelial renal parenchyma's neoplasms. Among more than 700 patients with renal tumors, which underwent MRI, 27 histopathologicaly verified cases of adenoma (10), malignant adenoma (11) and oncocytoma (6) were selected and the retrospective analysis of these 3 groups was performed. The 30 patients with small renal cell carcinoma were accepted as a control group. The benign tumor's MRI semiotics is described in general and in the particular for each nosological form. The author considers that MRI data reliably reflect the true morphological structure of the neoplasm's growth, concerning the secondary tumor's tissue alterations (r = 0.89), the presence (r = 0.92) and safety (r = 0.81) of pseudocapsula. At the same time, the specific MRI criteria for the different types of benign and small malignant tumors were not found.

Adenoma↗
PubMed1999

Degenerative joint disease on MRI and physical activity: a clinical study of the knee joint in 320 patients.

We examined 320 patients with MRI and arthroscopy after an acute trauma to evaluate MRI in diagnosis of degenerative joint disease of the knee in relation to sports activity and clinical data. Lesions of cartilage and menisci on MRI were registered by two radiologists in consensus without knowledge of arthroscopy. Arthroscopy demonstrated grade-1 to grade-4 lesions of cartilage on 729 of 1920 joint surfaces of 320 knees, and MRI diagnosed 14% of grade-1, 32% of grade-2, 94% of grade-3, and 100% of grade-4 lesions. Arthroscopy explored 1280 meniscal areas and showed degenerations in 10%, tears in 11.4%, and complex lesions in 9.2%. Magnetic resonance imaging was in agreement with arthroscopy in 81% showing more degenerations but less tears of menisci than arthroscopy. Using a global system for grading the total damage of the knee joint into none, mild, moderate, or severe changes, agreement between arthroscopy and MRI was found in 82%. Magnetic resonance imaging and arthroscopy showed coherently that degree of degenerative joint changes was significantly correlated to patient age or previous knee trauma. Patients over 40 years had moderate to severe changes on MRI in 45% and patients under 30 years in only 22%. Knee joints with a history of trauma without complete structural or functional reconstitution showed marked changes on MRI in 57%, whereas stable joints without such alterations had degenerative changes in only 26%. There was no correlation of degenerative disease to gender, weight, type, frequency, and intensity of sports activity. Therefore, MRI is an effective non-invasive imaging method for exact localization and quantification of chronic joint changes of cartilage and menisci that recommends MRI for monitoring in sports medicine.

Adolescent↗