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PubMed1997

Popliteal artery entrapment syndrome: diagnosis and management.

A variety of anatomical abnormalities may product an external compression of the popliteal artery, resulting in a thrombotic occlusion. Between 1983 and 1995, 9 patients presented a popliteal artery entrapment syndrome, bilateral in two cases. Ultrasonography, Angio-CT scan and MRI showed the abnormal structures and position of the popliteal artery on popliteal fossa. Arteriography detected an arterial compression in 6 limbs and occlusion in 4 limbs as well as an associated popliteal aneurysm in one patient and distal embolism in four. The abnormal medial head of the gastrocnemius muscle was resected in 8 limbs, while fibrous membranes were resected in 3 limbs. Autogenous vein replacement was performed in 4 cases of popliteal artery occlusion and following resection of a popliteal artery aneurysm in one case. All patients recovered. In the followup period, the occlusion of the arterial reconstruction occurred after 28 months in one patient, with a mild claudication. Noninvasive vascular imaging techniques may allow early diagnosis and management of PAES, avoiding popliteal arterial wall lesions and its occlusion, with a better outcome.

Adolescent↗

PubMed1989

[A surgical case of mediastinal cystic lymphangioma].

A surgical case of a 33-year-old male with mediastinal cystic lymphangioma is reported. He was referred to our hospital for examination of mediastinal tumor. Chest X-ray film revealed an abnormal shadow in the left aorto-pulmonary window. CT scan of the chest visualized a smooth-walled, homogenous structure of this mass. MRI showed same findings as CT scan but could not suggest further information. He was operated on under the diagnosis of Castleman's lymphoma or thymic cyst. On thoracotomy, a bulging cystic mass was found in the middle mediastinum just beneath the aortic arch. The cyst was completely removed, and his postoperative course was uneventful. Pathological diagnosis was a mediastinal cystic lymphangioma. Cystic lymphangioma usually occurs in the neck, and rarely occurs in the mediastinum. Only about 30 cases of mediastinal cystic lymphangioma have been reported in the Japanese literatures.

Adult↗

PubMed1999

Functional anatomy of neuropsychological deficits after severe traumatic brain injury.

BACKGROUND: Neurobehavioral disorders after severe traumatic brain injury (TBI) are poorly correlated with focal lesions detected by structural neuroimaging techniques such as CT scan or MRI. OBJECTIVE: To explore the relationships between regional cerebral glucose metabolism at rest, as measured by PET, and neurobehavioral status after severe TBI at the subacute stage. METHODS: Thirteen patients without focal structural lesion on MRI were studied. Neuropsychological assessment included tests of memory, attention and speed of information processing, and executive functions, and a global neurobehavioral assessment. Regional cerebral glucose metabolism at rest was measured with (18F)-fluorodeoxyglucose and PET. RESULTS: A close link was found between cognitive and behavioral disorders and decreased cortical metabolism in prefrontal and cingulate cortex. Tests of memory and executive functions significantly correlated with regional metabolism in the mesial and lateral prefrontal cortex and the cingulate gyrus. Behavioral disorders correlated significantly with mesial prefrontal and cingulate metabolisms. CONCLUSION: These results suggest a predominant role of prefrontal and cingulate dysfunction in cognitive and behavioral disorders of patients with severe traumatic brain injury, even in the absence of focal structural lesion of the brain. Further cognitive functional activation research using PET or functional MRI might help clarify the relative contributions of both areas to dysfunction.

Adolescent↗

PubMed1985

Chemical shift artifact in clinical magnetic resonance images at 0.35 T.

A thin, low-intensity line, which partially surrounds many structures on magnetic resonance imaging (MRI), is an artifact due to the phenomenon of chemical shift and should not be mistaken for a normal or abnormal morphologic structure. This artifact can be recognized by its characteristic appearance perpendicular to the direction of the frequency-encoding gradient at the interface of tissues with different chemical shift properties. Confinement within or extension beyond this thin, low-intensity line cannot be used as a criterion for staging neoplasms. Once recognized, the chemical shift artifact should not impede the use of MRI for clinical imaging at 0.35 T.

Diagnostic Errors↗

PubMed1996

Arterial territories of human brain: brainstem and cerebellum.

The development of neuroimaging has allowed clinicians to improve clinicoanatomic correlations in patients with strokes. Brainstem and cerebellum structures are well delineated on MRI, but there is a lack of standardization in their arterial supply. We present a system of 12 brainstem and cerebellum axial sections, depicting the dominant arterial territories and the most important anatomic structures. These sections may be used as a practical tool to determine arterial territories on MRI, and may help establish consistent clinicoanatomic correlations in patients with brainstem and cerebellar ischemic strokes.

Brain Mapping↗

PubMed1997

Three-dimensional imaging of cortical structure, function and glioma for tumor resection.

UNLABELLED: A three-dimensional brain imaging protocol with PET and MRI was used to visualize the cortical structure in relation to brain function and glioma infiltration to determine tumor resectability. METHODS: Sixteen patients with glioma had a PET scan with 11C-methionine to visualize tumor infiltration. The PET images were co-registered to the patients' own MRI reconstructed to the three-dimensional brain surface images to indicate the gyral structure and the extent of tumor infiltration. Thirteen patients, who bore tumors adjacent to the language or motor cortex, had H2 15O activation study to locate the eloquent cortex. The area of tumor infiltration was superimposed on the brain surface images together with the language and/or motor cortex. RESULTS: When a tumor was located within a single gyrus without influencing surface cortical gyrus pattern, the motor and language areas were identified morphologically by three-dimensional surface image alone. However, when the tumor caused swelling and deformation of cortical structure, functional mapping with H2(15)O activation technique was essential in locating them correctly. In such cases, the combined mapping of the facial motor area with oral movement and the language area with word repetition was the most useful method to identify the parasylvian structure in the dominant hemisphere. Total or near total resection of low-grade glioma in eight patients and the effective decompression of the active part of the malignant glioma in four patients was completed without causing functional neurological deterioration. CONCLUSION: The three-dimensional expression of cortical structure and function combined with PET glioma imaging with 11C-methionine is useful for radical resection of cerebral glioma.

Adult↗

PubMed1991

[Magnetic resonance in the diagnosis of aneurysmal bone cyst].

A patient of 12 suffering from aneurysmal cyst of the ischium was studied with traditional radiology, computed tomography (CT) and magnetic resonance imaging (MRI). The advantages of MRI in the study of this pathology compared to traditional radiography and CT are assessed. It was shown that the CT and MRI techniques are superior to standard X-ray examinations in anatomic definition and in evaluating the lesions's relationships with neighbouring structures and, in particular, that MRI is superior to CT in extension.

Bone Cysts↗

PubMed1999

Novel brain ischemic change on MRI. Delayed ischemic hyperintensity on T1-weighted images and selective neuronal death in the caudoputamen of rats after brief focal ischemia.

BACKGROUND AND PURPOSE: Specific change of persistent hyperintensity/hypointensity on T1-weighted (T1W) and T2-weighted (T2W) MRI, respectively, has been reported to develop in the human basal ganglia after brief hemispheric ischemia. We investigated whether this ischemic change observed in humans could be reproduced experimentally in rats after brief middle cerebral artery (MCA) occlusion (MCAO), and if so, what the neuroradiological change represented histologically. METHODS: The origin of the right MCA of male Wistar rats (n=25) was occluded for 15 minutes by inserting a silicon-coated nylon thread from the external carotid artery into the internal carotid artery. After 15 minutes' MCAO, coronal MR images (T1W, T2W, and T1W with fat saturation pulse) were obtained once at 3-day reperfusion (n=5) and twice at 3- and 7-day reperfusion (n=20). Brain specimens were examined histologically immediately after the last MRI study in all rats. RESULTS: Neither T1W nor T2W MRI showed marked signal changes 3 days after reperfusion following 15-minute MCAO. However, the ischemic change of hyperintensity and hypointensity on T1W and T2W MRI, respectively, appeared in the striatum following 7-day reperfusion after 15-minute MCAO (n=19/20). Histological examination revealed that the specific lesion in the rat striatum on MRI corresponded to selective neuronal death and proliferation of reactive astrocytes and microglia without infarct, hemorrhage, lipid accumulation, or calcification. CONCLUSIONS: Brief MCAO with reperfusion induces the delayed ischemic changes of hyperintensity and hypointensity on T1W and T2W MRI, respectively, in the rat striatum with high reproducibility. This specific ischemic change on MRI histologically corresponded to selective neuronal death and gliosis with preservation of the macroscopic structure of the brain. A similar MRI pattern reported in patients who have sustained brief ischemia may represent similar histology. We speculate that the ischemic change reflects some biochemical changes affecting the magnetic field as the brain tissue undergoes subtle structural changes.

Animals↗

PubMed2001

[MRI of the cerebellopontine angle in patients with cleidocranial dysostosis].

PURPOSE: Cleidocranial dysostosis (CCD) is an autosomal dominant bone disorder in which deafness is common secondary to malformation of the middle ear structures. The study aimed at MRI evaluation of the cerebellopontine angle in 7 patients with a history of CCD--two generation spanned relatives. MATERIAL AND METHODS: Cranial MRI in 7 patients with CCD (4 women/3 men aged between 8 and 46 years) was performed. In two patients hearing disorders were present. The examinations encompassed multi-planar spinecho sequences of the cerebellopontine angle in 3-mm slice thickness before and after administration of contrast medium. RESULTS: The clinically most conspicuous female patient (hearing loss, ataxia, headache) showed a strongly contrast-enhancing tumor in MRI that was histologically proved to be an acoustic schwannoma. Concerning the other family members, no pathological findings were noted except for non-pneumatized mastoids. CONCLUSION: The first report of a patient with CCD and an acoustic schwannoma shows that in case of hearing loss in these patients also a retrocochlear cause must be considered.

Adolescent↗

PubMed1990

Auditory hallucinations and smaller superior temporal gyral volume in schizophrenia.

Recent neuropathologic investigations in schizophrenia report smaller volume of medial temporal lobe structures. These findings are confirmed by preliminary magnetic resonance imaging (MRI) studies. Direct stimulation of lateral temporal lobe structures in the region of the superior temporal gyrus provokes hallucinations. The authors' MRI study of young schizophrenic patients demonstrates smaller volume of the superior temporal gyrus (an auditory association area) and of the left amygdala. Smaller size of the left superior temporal gyrus and left amygdala is not accounted for by smaller size of the overall brain or temporal lobe. Shrinkage of the left superior temporal gyrus is strongly and selectively correlated with severity of auditory hallucinations.

Adult↗

PubMed1997

Sonography, CT, CT sialography, MRI and MRI sialography in investigation of the facial nerve and the differentiation between deep and superficial parotid lesions.

Our aim was to explore the possibility of delineation of the facial nerve within the parotid gland and to differentiate between superficial and deep parotid lesions in relationship to it, using ultrasound, CT, MRI, MRI sialography (MRIS) and CT sialography (CTS). We examined 47 patients with clinically suspected parotid tumours by US, 31 of them also by CT, MRI and CTS, and 13 by MRIS as well. Low-intensity curvilinear structures seen on T1-weighted MRI were delineated better after intraductal gadolinium injection and proved to represent parotid ducts on CTS. Using the main parotid duct as a landmark, we distinguished parotid lesions as deep or superficial to the facial nerve by T1-weighted MRI images in 69% and by MRIS in all cases. The facial nerve itself was indistinguishable from the parotid gland in all our imaging methods.

Adolescent↗

PubMed1993

MRI and intraocular tamponade media.

Thirteen patients who underwent surgery for retinal detachment and injection of intraocular tamponade media (silicone oil, fluorosilicone oil, or perfluorocarbon liquid) underwent magnetic resonance imaging (MRI), using spin-echo T1- and T2-weighted images. The ophthalmic tamponade media showed different signal intensity, according to their chemical structure. Unlike ophthalmoscopy or ultrasonography, MRI showed no oil-related artefact, making possible recognition of recurrent retinal detachment.

Humans↗

PubMed1988

[Magnetic resonance tomographic results in bone changes associated with sclerosis].

We have compared the value of MRI with conventional radiography and CT in 40 predominantly sclerotic skeletal lesions. We have found that sclerosis and other changes in the bone structure can be demonstrated by MRI in much the same way as with conventional radiography and CT. Using high resolution surface coils, it is possible to demonstrate small areas of new bone formation such as periosteal new bone or the calcification within the nidus of an osteoid osteoma. MRI is particularly appropriate if it is necessary to show soft tissue changes within an area of sclerosis, which may be responsible for the new bone formation and which may be masked on radiographs and CT by the surrounding sclerosis.

Bone Diseases↗

PubMed2001

A comparison of (18)F-dopa PET and inversion recovery MRI in the diagnosis of Parkinson's disease.

OBJECTIVE: To quantify structural changes in the substantia nigra of patients with PD with inversion recovery MRI and to compare these with striatal dopaminergic function measured with (18)F-dopa PET. METHODS: The authors studied 10 patients with PD and eight age-matched control subjects with a combination of MR sequences previously reported to be sensitive to nigral cell loss. Striatal regions of interest were defined on T1-weighted MRI coregistered to (18)F-dopa PET in all subjects. RESULTS: Discriminant function analysis of the quantified MR nigral signal correctly classified 83% of the combined PD patient/control group; three of 10 PD cases were incorrectly classified as "normal" (Wilks' lambda = 0.724, p > 0.05). Discriminant function analysis correctly classified 100% of PD patients and control subjects with (18)F-dopa PET based on mean caudate and putamen K(i) values (Wilks' lambda = 0.065, p < 0.001). Correlations between mean putamen K(i) and rostral and caudal nigral MR signal changes and mean caudate K(i) and caudal nigral MR signal changes were found (r = -0.76, -0.69, -0.80, p < 0.05). CONCLUSION: (18)F-dopa PET is more reliable than inversion recovery MRI in discriminating patients with moderately severe PD from normal subjects. However, the structural changes detected within the substantia nigra of patients with PD found using inversion recovery MRI correlate with measures of striatal dopaminergic function using (18)F-dopa PET.

Brain↗

PubMedDate not supplied

Visualisation of structure and flow in packed beds.

Magnetic resonance imaging (MRI) volume- and velocity-measurement techniques are used to probe structure-flow correlations within the interparticle space of a packed bed of ballotini. Images of the three mutually orthogonal components of the velocity field are obtained in axial and radial image slices within a bed of 5-mm-diameter ballotini, packed within a glass column of internal diameter 4.6 cm. A three-dimensional volume image of the bed is also obtained and analysed to partition the interparticle space into individual pores and determine the location of pore necks. Significant heterogeneity in the flow is observed; in one slice approximately 8% of the pores carry 40% of the volume flow. The characteristics of pores carrying anomalously high values of fluid flow rate and velocity are investigated.

Humans↗

PubMed1998

Herpes simplex virus encephalitis: cranial magnetic resonance imaging and neuropathology in a mouse model.

We performed a long-term magnetic resonance imaging (MRI) study in a mouse model of herpes simplex virus encephalitis. Mice were infected with herpes simplex virus type 1 (HSV-1) strain F. A 1.5-T cranial MRI scanner with standard spin-echo sequences was used. Neuropathological studies included immunohistochemistry. The presence of HSV DNA in brain tissue was determined with a polymerase chain reaction assay. Clinical assessment was performed daily: within the first 2 weeks the animals were severely affected and recovered thereafter. MRI and histopathological abnormalities corresponded well. HSV DNA was detectable initially and at 6 months. Extent and severity of structural abnormalities increased at 6 months. MRI offers a new in vivo approach for the detection of structural changes in the disease course of experimental herpes simplex virus encephalitis.

Animals↗

PubMed1999

Anatomic validation of spatial normalization methods for PET.

UNLABELLED: Spatial normalization methods, which are indispensable for intersubject analysis in current PET studies, have been improved in many aspects. These methods have not necessarily been evaluated as anatomic normalization methods because PET images are functional images. However, in view of the close relation between brain function and morphology, it is very intriguing how precisely normalized brains coincide with each other. In this report, the anatomic precision of spatial normalization is validated with three different methods. METHODS: Four PET centers in Japan participated in this study. In each center, six normal subjects were recruited for both H2(15)O-PET and high-resolution MRI studies. Variations in the location of the anterior commissure (AC) and size and contours of the brain and the courses of major sulci were measured in spatially normalized MR images for each method. Spatial normalization was performed as follows. (a) Linear: The AC-posterior commissure and midsagittal plane were identified on MRI and the size of the brain was adjusted to the Talairach space in each axis using linear parameters. (b) Human brain atlas (HBA): Atlas structures were manually adjusted to MRI to determine linear and nonlinear transformation parameters and then MRI was transformed with the inverse of these parameters. (c) Statistical parametric mapping (SPM) 95: PET images were transformed into the template PET image with linear and nonlinear parameters in a least-squares manner. Then, coregistered MR images were transformed with the same parameters used for the PET transformation. RESULTS: The AC was well registered in all methods. The size of the brain normalized with SPM95 varied to a greater extent than with other approaches. Larger variance in contours was observed with the linear method. Only SPM95 showed significant superiority to the linear method when the courses of major sulci were compared. CONCLUSION: The results of this study indicate that SPM95 is as effective a spatial normalization as HBA, although it does not use anatomic images. Large variance in structures other than the AC and size of the brain in the linear method suggests the necessity of nonlinear transformations for effective spatial normalization. Operator dependency of HBA also must be considered.

Brain↗

PubMed1990

Magnetic resonance imaging in patients with inflammatory arthritis of the knee.

Magnetic resonance imaging (MRI) permits visualization of anatomic structures not appreciated by conventional radiographic imaging and may quantify inflammatory disease and its progression with greater sensitivity than available techniques. We therefore compared MRI with clinical evaluation and with radiographic examination of 17 patients with inflammatory arthritis of the knee. We sought to determine anatomic integrity of bone, cartilage, menisci, and ligaments, and to quantify joint effusion and synovial proliferation. Patients studied had rheumatoid arthritis (10 patients), juvenile rheumatoid arthritis (4 patients), ankylosing spondylitis (1 patient), and monoarticular arthritis (2 patients). In all patients MRI revealed clinically important abnormalities not detected by physical or conventional radiographic exams. These included proliferative synovitis (13 patients), cartilage thinning (2 patients), cartilage erosion (8 patients), bone infarction (1 patient), meniscal injury (1 patient), and synovial invagination into bone (1 patient). Also MRI indicated inflammatory disease to be quantitatively greater than had been appreciated on clinical examination or routine X-ray studies--proliferative synovitis (12 patients), erosion (7 patients), effusion (8 patients), cartilage thinning (11 patients), and ligamentous/meniscal damage (1 patient). These findings led to reassessment of anatomic staging and influenced therapeutic decision for these patients. Thus MRI provides clinically important information about joint integrity and inflammatory disease, with a sensitivity and resolution considerably beyond conventional techniques.

Adult↗