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At least 1,207 records · Page 67Linked to original sources
PubMed1991

Magnetic resonance appearance of peripheral nerve sheath tumors.

Magnetic resonance imaging (MRI) was used to evaluate 22 histologically proven peripheral nerve sheath tumors, approximately two-thirds of which arose in the lower extremity. The histologic distribution was as follows: 12 schwannomas, 7 neurofibromas, and 3 malignant peripheral nerve sheath tumors (2 of which occurred in patients with neurofibromatosis). Most lesions demonstrated an intermediate to moderately bright signal on T1-weighted images and were minimally inhomogeneous. All lesions were moderately bright on proton-density-weighted images and bright on T2-weighted images, again with variable inhomogeneity. The extent of the tumor was best assessed on proton-density- and T2-weighted images. Smooth margins were noted in 19 lesions. Of the 3 remaining lesions, 2 were malignant (but had been subjected to biopsy prior to MRI), and the other lesion was a plexiform neurofibroma. MRI accurately determined the relationship between the lesion and the adjacent neurovascular structures and muscles, thereby assisting surgical management. On MRI, 5 lesions demonstrated coexistent subtle muscle atrophy along the longitudinal axis of surrounding or distally innervated musculature. This latter finding, together with the presence of a tumor in the vicinity of a large nerve trunk, suggests a peripheral nerve sheath neoplasm.

Adult↗
PubMed2003

Magnetic resonance images of the brain of a dwarf sperm whale (Kogia simus).

Cetacean (dolphin, whale and porpoise) brains are among the least studied mammalian brains because of the difficulty of collecting and histologically preparing such relatively rare and large specimens. Among cetaceans, there exist relatively few studies of the brain of the dwarf sperm whale (Kogia simus). Magnetic resonance imaging (MRI) offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Therefore, MRI has become a critical tool in the study of the brain of cetaceans and other large species. This paper represents the first MRI-based anatomically labelled three-dimensional description of the dwarf sperm whale brain. Coronal plane sections of the brain of a sub-adult dwarf sperm whale were originally acquired and used to produce virtual digital scans in the other two orthogonal spatial planes. A sequential set of images in all three planes has been anatomically labelled and displays the proportions and positions of major neuroanatomical features.

Animals↗
PubMed2001

Anatomy of the anal canal and perianal structures as defined by phased-array magnetic resonance imaging.

BACKGROUND: The anatomy of the anal canal and perianal structures has been imaged using endoluminal magnetic resonance imaging (MRI). Phased-array MRI avoids the use of an endoluminal coil that may distort anatomy. The aim of this study was to describe the anatomy of the anal canal and perianal structures using phased-array MRI. METHODS: Imaging was performed in 14 men and 19 nulliparous women. The dimensions of the anal canal, puborectalis, external anal sphincter, perineal body, superficial transverse perineal muscle, bulbospongiosus, ischiocavernosus and anococcygeal body were measured in different planes, and sex differences were calculated. RESULTS: The lateral canal was significantly longer than its anterior and posterior part (P < 0.001). The anterior external anal sphincter was shorter in women than in men (P = 0.01) and occupied, respectively, 30 and 38 per cent of the anal canal length (P = 0.001). The caudal ends of the external anal sphincter formed a double layer. The perineal body was thicker in women than in men (P < 0.001) and easier to define. The superficial transverse muscles had a lateral and caudal extension to the ischiopubic bones. The bulbospongiosus was thicker in men than in women (P < 0.001). The ischiocavernosus and anococcygeal body had the same dimensions in both sexes. CONCLUSION: Phased-array MRI is a non-invasive technique that allows an accurate description of the normal anatomy of the anal canal and perianal structures.

Adult↗
PubMed2003

Clinical application of neuroimaging in epilepsy.

OBJECTIVE: To evaluate the use of neuroimaging in clinical practice and to assess the prevalence of detected structural abnormalities in epilepsy patients in a clinical set up. METHODS: 919 outpatients were identified and the scan results reviewed. A total of 677 patients had chronic active epilepsy (88 had idiopathic generalised epilepsy (IGE), 588 had localisation related epilepsy, one had symptomatic generalised epilepsy), 57 had a single epileptic seizure, 46 were in remission, and 139 had non-epileptic attacks. RESULTS: 391 patients had no scan (53 patients in this group had IGE, 182 had localisation related epilepsy, one had generalised symptomatic epilepsy, 18 had single epileptic attacks, 21 were in remission, 116 had non-epileptic attacks). Altogether 528 patients had a scan, the results were not available in 33, 163 had x ray computed tomography (CT) only, 178 had standard magnetic resonance imaging (MRI) (slice thickness 5 mm), and 154 had high resolution MRI (including a T1 weighted sequence with 1.5 mm thick slices). Some 252 of 495 scans (51%) were abnormal. Abnormalities were hippocampal sclerosis (n=128), atrophy or non-specific white matter lesions (n=35), vascular abnormalities (n=27), tumours (n=25), brain damage (n=24), malformations of cortical development (n=13). Excluding atrophy and non-specific white matter lesions the prevalence of detected abnormalities was 54% in localisation related epilepsy, 18% in single seizure patients, 16% in epilepsy in remission, and 0% in IGE and non-epileptic attacks. CONCLUSIONS: Abnormalities were detected in more than half of all patients with localisation related epilepsy, and in about one in five patients with single seizures or epilepsy in remission. Many patients had no scan or only CT or standard MRI. The true prevalence of structural abnormalities may be have been higher. Scanning did not add any information in patients with IGE or non-epileptic attacks.

Adolescent↗
PubMed1997

Quantitative MRI volume changes in late onset schizophrenia and Alzheimer's disease compared to normal controls.

Volumes of medial and lateral temporal lobe structures were assessed using magnetic resonance imaging (MRI) in 11 patients with late-life onset schizophrenia (LOS), 18 normal elderly controls and 12 patients with moderate cognitive impairment due to Alzheimer's disease (AD) who had no non-cognitive symptoms. While both patient groups had smaller volumes of several medial temporal regions (e.g. entorhinal cortex, left hippocampus), schizophrenics had significantly smaller anterior superior temporal gyri (STG) than normal controls, but AD patients did not. We have previously demonstrated anterior STG volume to be reduced in early life onset schizophrenia.

Age of Onset↗
PubMed2003

Staging of advanced cervical carcinoma using MRI-predictors of outcome after radical radiotherapy.

AIM: To assess the prognostic significance of imaging findings used in magnetic resonance imaging (MRI) staging of cervical carcinoma by correlation with survival after radiotherapy. MATERIALS AND METHODS: MRI examinations of 99 cervical carcinoma patients were reviewed. Tumour involvement of pelvic structures was assessed. Lymph node sites, short axis diameters and signal characteristics were recorded. MRI staging was compared with clinical [International Federation of Gynaecology and Obstetrics (FIGO)] staging. Univariate analysis was performed for MRI stage, clinical stage, nodal status and pelvic structure involvement against disease-specific (DSS) and disease-free survival (DFS). RESULTS: MRI staging correlated with DSS (p=0.006) and DFS (p=0.007) but clinical staging did not. Pelvic nodes > or = 10 mm and juxtaregional or distant nodes > or = 8 mm short axis were most strongly associated with survival (p=0.014, p=0.011 and p=0.001, respectively, for association with DSS). Tumour involvement of pelvic bowel loops, pelvic sidewall and bladder mucosa were significantly associated with poor DSS and DFS (p<0.05). Tumour dimensions and bladder muscle involvement alone were not associated with poor survival. CONCLUSION: MRI staging is a better predictor of survival than clinical staging in patients receiving radiotherapy for cervical carcinoma. MRI assessment of lymph node enlargement and tumour involvement of pelvic structures gives valuable prognostic information.

Adult↗
PubMed2000

3D MRI studies of neuroanatomic changes in unipolar major depression: the role of stress and medical comorbidity.

Increasing evidence has accumulated for structural brain changes associated with unipolar recurrent major depression. Studies of neuroanatomic structure in early-onset recurrent depression have only recently found evidence for depression-associated structural change. Studies using high-resolution three-dimensional magnetic resonance imaging (MRI) are now available to examine smaller brain structures with precision. Brain changes associated with early-onset major depression have been reported in the hippocampus, amygdala, caudate nucleus, putamen, and frontal cortex, structures that are extensively interconnected. They comprise a neuroanatomic circuit that has been termed the limbic-cortical-striatal-pallidal-thalamic tract. Of these structures, volume loss in the hippocampus is the only consistently observed change to persist past the resolution of the depression. Possible mechanisms for tissue loss include neuronal loss through exposure to repeated episodes of hypercortisolemia; glial cell loss, resulting in increased vulnerability to glutamate neurotoxicity; stress-induced reduction in neurotrophic factors; and stress-induced reduction in neurogenesis. Many depressed patients, particularly those with late-onset depression, have comorbid physical illnesses producing a high rate of hyperintensities in deep white matter and subcortical gray matter and brain damage to key structures involved in the modulation of emotion. Combining MRI studies with functional studies has the potential to localize abnormalities in blood flow, metabolism, and neurotransmitter receptors and provide a better integrated model of depression.

Animals↗
PubMed1986

[Nuclear magnetic resonance tomography in the diagnosis of parotid tumors. A comparison of methods].

The diagnostic value and the limitations of magnetic resonance imaging (MRI) in the management of large parotid masses were evaluated in a prospective clinical study. The results were compared with computed tomography (CT) and B-mode ultrasonography (US). MRI was performed using a Siemens 1.5 Tesla Magnetom with a RF head coil and surface RF coils. The images were evaluated by the following parameters of clinical importance: tumour detectability and marginal appearance, internal architecture, regional extension, and artifact degradation. MR imaging of parotid masses was superior to CT and US for the following reasons. The marginal appearance of the tumour was sharp and further enhanced in T2 weighted pictures. The extension of the tumour can be well seen by use of transaxial and frontal projections. This is an advantage especially when the mass extends to the retromandibular fossa or even to the pterygopalatine fossa. The position of the jaw, external ear canal, mastoid, skull base, and vessels of the neck are clearly shown without artifact degradation. Benign neoplasms can be well differentiated from malignant tumours which show local infiltration into the adjacent anatomical structures as well as irregularities of their internal structure. However, their appearance in MRI can be identical to that of an acute inflammation of the parotid gland. In summary MRI is the imaging technique of choice for extensive parotid masses, whereas US is effective for small tumours not situated in the retromandibular fossa.

Humans↗
PubMed1991

MR-anatomy of infants hip: comparison to anatomical preparations.

The correlation between anatomical preparations and MRI images of the most important structures of newborn hips in coronal and axial orientation was performed in 18 post mortem babies. T1-weighted images present a good differentiation between cartilage, bone, ligaments and surrounding soft tissues. Coronal images give the best opportunity to study the clinically important structures of the roof of acetabulum including the labrum and the ground of the acetabulum. The latter is shown in a more detailed way by MRI than by sonography. Axial images allow additional examinations of the ventral and dorsal parts of the joint. By using both coronal and axial images the exact determination of the centering of the femur head in the hip joint is possible.

Acetabulum↗
PubMed1997

Mesenteric plexiform neurofibroma associated with Recklinghausen's disease.

We present a rare case of plexiform neurofibroma involving the ileal mesentery of a 10-year-old boy with Recklinghausen's disease. MRI showed multiple ring-like structures in the masses on T2-weighted and contrast enhanced T1-weighted images. Probably these findings reflect enlarged peripheral nerves with myxoid degeneration. MRI is useful for the diagnosis of mesenteric plexiform neurofibroma because of this characteristic appearance.

Child↗
PubMed2003

Magnetization transfer imaging in focal epilepsy.

OBJECTIVES: To test the hypothesis that magnetization transfer imaging (MTI), analyzed on a voxel-by-voxel basis, would identify areas of abnormal magnetization transfer ratio (MTR) in patients with focal epilepsy. METHODS: The authors used MTI maps and statistical parametric mapping (SPM) to objectively compare the cerebral structures of 15 patients with malformations of cortical development (MCD), 10 with partial seizures and acquired lesions, and 42 with partial seizures and normal conventional MRI with those of 30 control subjects. RESULTS: Significant reductions of MTR were identified in all 10 patients with acquired nonprogressive cerebral lesions and partial seizures. In all, the areas of decreased MTR concurred with abnormalities identified on visual inspection of conventional MRI. In 13 of the 15 patients with MCD, SPM detected regions of significantly reduced MTR, all of which corresponded to abnormalities identified on visual inspection of conventional MRI. In addition, in both groups, there were areas that were normal on conventional imaging that demonstrated abnormal MTR. There was a significant reduction of MTR in 15 of the 42 patients with cryptogenic focal epilepsy. In all of these, the areas of reduced MTR concurred with epileptiform EEG abnormality and clinical seizure semiology. CONCLUSIONS: Magnetization transfer imaging analyzed using statistical parametric mapping was sensitive in identifying malformations of cortical development and acquired cerebral lesions. Abnormalities of magnetization transfer ratio in individual MRI-negative patients suggest that minor structural disorganization exists in occult epileptogenic cerebral lesions.

Adolescent↗
PubMed1998

Noninvasive MRI evaluation of cerebral blood flow in cerebrovascular disease.

Previous studies have demonstrated that cerebral blood flow (CBF) can be assessed noninvasively by MRI using magnetic labeling of arterial water as a diffusible flow tracer. The purpose of this study was to assess the quality of CBF images obtained from patients with cerebrovascular disease using this method, and to begin to evaluate the potential clinical role for this technique. We recruited 14 patients who presented with stroke, TIA, or severe carotid stenosis and were likely to have altered CBF based on clinical assessment. In many of these patients, CBF imaging disclosed both focal and hemispheric hypoperfusion, either in vascular territories or in watershed regions. In 11 patients with significant proximal arterial stenosis, hemispheric CBF abnormalities localized to the side of most significant stenosis for the anterior circulation distribution. In several patients watershed hypoperfusion was even more pronounced. Our results suggest that good-quality MR CBF images can be obtained reliably from patients with cerebrovascular disease. CBF imaging can be combined with standard structural imaging within a single MRI examination, and provides clinically meaningful information. The capability of measuring CBF easily provides a potentially useful tool for clinical assessment and further investigation of stroke pathophysiology.

Adult↗
PubMed1992

[MRI of the wrist joint].

Due to the development of new surface coils and the use of thin slices, MRI has become an essential diagnostic tool in wrist pathology. After several technical considerations, the authors describe the normal MRI appearance of the various anatomical structures of the wrist, particularly the triangular fibrocartilaginous complex of the wrist and the elements of the carpal tunnel. They review the principal indications for MRI: chronic diseases such as carpal tunnel syndrome and traumatic ligamentous and cartilaginous lesions. The bone marrow lesions detected in the presence of occult fractures and osteonecrosis of the lunate or scaphoid are then briefly considered. The diagnostic criteria of median nerve compression (carpal tunnel syndrome) include morphological and signal changes in the nerve, abnormal palmar convexity of the flexor retinaculum and signs of tenosynovitis of the intracarpal flexor tendons. However, in practice, MRI is only useful when there is disagreement between the clinical and EMG findings and in postoperative recurrences, in which case it may reveal insufficient section of the retinaculum or the presence of exuberant postoperative fibrosis responsible for persistent nerve compression. Traumatic tears of the triangular fibrocartilage are characterised by a linear high signal intensity image (on T1 and T2 weighted sequences), usually situated in the periphery of the articular disk. Degenerative lesions tend to be central, within the disk and are frequently observed after the age of 40 years.

Carpal Bones↗
PubMed1998

A brain MRI study in subjects with borderline personality disorder.

BACKGROUND: There have been only a few brain computed tomography imaging studies, with mostly negative findings, in subjects with borderline personality disorder (BPD). This is the first MRI study which evaluated the structural abnormalities of the brain in subjects with the sole diagnosis of BPD. METHODS: Twenty-five subjects with BPD were compared with age-, gender-matched healthy comparison subjects (n=25) on volumes of the frontal lobes, the temporal lobes, the lateral ventricles, and the cerebral hemispheres in brain magnetic resonance imaging. RESULTS: Subjects with BPD had a significantly smaller frontal lobe compared to comparison subjects (multivariate regression analysis, t=2.225, df=46, P=0.031). There were no significant differences in volumes of the temporal lobes, the lateral ventricles, and the cerebral hemispheres between subjects with and without BPD. LIMITATIONS: Strict inclusion and exclusion criteria employed in the present study may make it difficult to generalize our findings. The gray matter and white matter of the brain were not measured separately. Differences in head tilt during image acquisition were not corrected. CONCLUSIONS: The current study reports a smaller frontal lobe volume on brain MRI in subjects with BPD compared with healthy comparison subjects. This finding may serve as a potentially useful biological variable that may allow for subtyping BPD.

Adolescent↗
PubMed1990

Diagnostic imaging of maxillofacial lesions with CT and MRI.

Normal anatomy of the maxillofacial regions is clearly shown by both CT and MRI. The use of dental devices causes deterioration in CT and MRI of the tongue and oral floor. A high-resolution bone window display is highly useful in examining bony structures. Contrast CT is useful in diagnosis of tumorous, inflammatory, and vascular lesions. MRI shows the extensions of tumors more clearly than CT, and MRI enhanced with Gd-DTPA is very useful in determining tumor extensions into bony structures. Both CT and MRI should be used in diagnosis of maxillofacial lesions.

Humans↗
PubMed2005

MR findings of nine cases of palatal tumor.

PURPOSE: To assess the magnetic resonance imaging (MRI) findings of pathologically confirmed palatal tumors. METHODS: Nine cases of palatal tumor were studied. Clinical data, MRI findings, and pathological diagnoses were evaluated. RESULTS: Five cases were tumors of the hard palate and four of the soft palate. Signal intensity on T1-weighted images varied, and hyperintensity was observed on T2-weighted images. Adenoid cystic carcinoma and diffuse large B cell lymphoma showed homogenous signal intensity. Other tumors showed heterogeneous signal intensities. On dynamic contrast analysis, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed early enhancement. On post-contrast T1-weighted images, hard palate pleomorphic adenoma, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed strong enhancement. Although the borders of the tumors were classified as clear in 6 cases treated surgically, macroscopic and microscopic borders of the tumors were unclear. Adenoid cystic carcinoma and hard palate diffuse large B cell lymphoma invaded the maxillary bone. CONCLUSION: Magnetic resonance findings of palatal tumor varied in different histologies. Even with a small palpable portion, malignant tumors could directly infiltrate surrounding structures, which demonstrated well on MRI.

Adenoma, Pleomorphic↗
PubMed2000

Six-month test-retest reliability of MRI-defined PET measures of regional cerebral glucose metabolic rate in selected subcortical structures.

Test-retest reliability of resting regional cerebral metabolic rate of glucose (rCMR) was examined in selected subcortical structures: the amygdala, hippocampus, thalamus, and anterior caudate nucleus. Findings from previous studies examining reliability of rCMR suggest that rCMR in small subcortical structures may be more variable than in larger cortical regions. We chose to study these subcortical regions because of their particular interest to our laboratory in its investigations of the neurocircuitry of emotion and depression. Twelve normal subjects (seven female, mean age = 32.42 years, range 21-48 years) underwent two FDG-PET scans separated by approximately 6 months (mean = 25 weeks, range 17-35 weeks). A region-of-interest approach with PET-MRI coregistration was used for analysis of rCMR reliability. Good test-retest reliability was found in the left amygdala, right and left hippocampus, right and left thalamus, and right and left anterior caudate nucleus. However, rCMR in the right amygdala did not show good test-retest reliability. The implications of these data and their import for studies that include a repeat-test design are considered.

Adult↗
PubMed2005

Posterolateral complex knee injuries: magnetic resonance imaging with surgical correlation.

PURPOSE: To describe the magnetic resonance imaging (MRI) findings of injuries of the posterolateral aspect of the knee and to evaluate the diagnostic capabilities of MRI in the assessment of these injuries. MATERIAL AND METHODS: The MRI studies of 14 patients (mean age 33 years) with trauma to the posterolateral aspect of the knee were retrospectively reviewed, and the imaging findings were correlated with those of surgery. RESULTS: In all patients, MRI showed an intact iliotibial (ITB) band. MRI showed injury to the biceps tendon in 11 (79%), the gastrocnemius tendon in 1 (7%)), the popliteus tendon in 5 (36%), and the lateral collateral ligament (LCL) in 14 (100%) patients. Tear of the anterior cruciate ligament (ACL) was seen in 11 (79%) patients and tear of the posterior cruciate ligament (PCL) in 4 (29%) patients. With routine MRI, visualization of the popliteofibular or fabellofibular ligaments was incomplete. On MRI, the lateral meniscus and the medial meniscus were torn with equal frequency (n = 4; 29%). Osteochondral defects were seen in 5 (36%) cases and joint effusion in all 14 (100%) cases on MRI. Using surgical findings as the standard for diagnosis, MRI proved 86% accurate in the detection of injury to the ITB band, the biceps tendon (93%), the gastrocnemius tendon (100%), the popliteus tendon (86%), the LCL (100%), the ACL (79%), the PCL (86%), the lateral meniscus (90%), the medial meniscus (82%), and the osteochondral structures (79%). Surgical correlation confirmed the MRI findings of joint effusion in all cases. CONCLUSION: MRI is well suited for demonstrating the presence and extent of injuries of the major structures of the posterolateral complex of the knee, allowing characterization of the severity of injury.

Adolescent↗