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PubMed2003

Bursitis, adventitious bursa, localized soft-tissue inflammation, and bone marrow edema in tibial stumps: the contribution of magnetic resonance imaging to the diagnosis and management of mechanical stress complications.

OBJECTIVE: To assess the contribution of magnetic resonance imaging (MRI) in the diagnosis of tibial stump bursitis, in the establishment of differential diagnosis, and in the therapeutic management prosthetic-stump interface, mainly by adaptation of the prosthetic device. DESIGN: Two-year, prospective, consecutive series. SETTING: University-affiliated prosthetic and rehabilitation center and university department of radiology. PARTICIPANTS: A group of 17 persons with stump problems identified from a total of 139 consecutive below-knee amputees with prosthesis problems. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Clinical symptoms and MRI. RESULTS: Clinical symptoms (variable stump volume, fluctuating mass at palpation with or without mechanical pain) were suggestive of bursitis in 10 patients. MRI confirmed bursitis in 9 and identified 1 in whom clinical signs suggested neuroma, giving an incidence of 10 of 139 amputees (7.2%). MRI identified 13 sites of bursitis (adventitious bursa, 11; synovial bursitis, 2) and 5 localized areas of soft tissue inflammation. MRI showed diffuse muscular edema at 1 site of clinically suspected bursitis, and bursitis at another site of suspected neuroma. Calcified bursitis was observed in 1 case. Bone abnormalities associated with bursitis (n=7) included osteophytes or fracture (n=4) or bone marrow edema (n=3). Two asymptomatic neuromas were also identified. MRI-guided modifications of the prosthetic interface led to favorable outcome in all cases. CONCLUSION: Bursitis, adventitious bursae, and areas of localized soft-tissue inflammation are different aspects of the same disorder resulting from a mechanical conflict between the stump and the prosthesis socket. Besides contributing to diagnosis, MRI provides a precise assessment necessary for correcting the prosthesis-stump interface in a way that reduces mechanical stress and subsequently cures bursitis.

Adolescent↗
PubMed1998

Acute, relapsing brain oedema with diffuse blood-brain barrier alteration and axonal damage in the acquired immunodeficiency syndrome.

A 38-year-old homosexual male with AIDS suffered four neurological episodes including headaches, confusion, visual impairment, memory disturbances, and dysarthria which resolved spontaneously in a few days. He was admitted to hospital during a fifth episode. Neurological examination revealed a cerebellar syndrome. General examination was normal. CD4 count was 90. CSF contained two WBCs/mm(3) and 12.30 mg/dL protein. MRI revealed diffuse ill defined increased signal on T2-weighted images in the white matter. His condition worsened rapidly with vomiting and he died 1 month after admission. Neuropathological examination revealed diffuse brain oedema with ventricular compression, central diencephalic herniation and bilateral tonsilar herniation in the absence of a focal lesion. Microscopical examination revealed predominant involvement of the white matter with diffuse myelin pallor and massive perivascular dilatation containing an exudate expressing serum proteins and occasional macrophages. The same exudate was also diffuse in the leptomeninges. Parenchymal damage predominated around the perivascular spaces and included loosening of tissue, axonal damage with spheroids and reactive astrocytosis. There was no evidence of productive HIV encephalitis, no multinucleated giant cells; p24 immunostaining and RT-PCR for HIV genome were negative. There was neither significant inflammation nor microglial activation. In this illustrative case, the relapsing course of the neurological signs, the diffuse topography of the blood-brain barrier breakdown and the absence of local cause make it likely that the diffuse leak and axonal damage could be related to circulating factors.

Acquired Immunodeficiency Syndrome↗
PubMed2001

A new method to investigate brain stem structural-functional correlations using digital post-processing MRI--reliability in ischemic internuclear ophthalmoplegia.

We investigated the reliability of a new digital post-processing magnetic resonance imaging (MRI) technique in ischemic brain stem lesions to identify relations of the lesion to anatomical brain stem structures. The target was a medial longitudinal fasciculus (MLF) lesion, which was evident from ipsilateral internuclear ophthalmoplegia (INO). Sixteen patients with acute unilateral INO and an isolated acute brain stem lesion in T2- and EPI-diffusion weighted MRI within 2 days after the onset of symptoms were studied. The MRI slice direction was parallel and perpendicular to a slice selection of a stereotactic anatomical atlas. The individual slices were normalized and projected in the digitalized atlas. The eye movement disorder was monitored by electro-oculography. In all patients with clinical or subclinical electro-oculographically documented INO and MRI proven brain stem infarction the lesion covered or at least partially overlapped the ipsilateral MLF at one or more atlas levels. We conclude that digital post-processing MRI with normalizing and projecting brain stem lesions in an anatomical atlas is a reliable method to demonstrate the anatomical structures involved by the lesion. Combined with electrophysiological brain stem testing, this method may be a useful tool to identify incompletely understood pathways mediating brain stem reflexes or the generators of evoked potentials.

Adult↗
PubMed2006

Collateral nerve fibers in human spinal cord: visualization with magnetic resonance diffusion tensor imaging.

Diffusion tensor magnetic resonance imaging provides structural information about nerve fiber tissue. The first eigenvector of the diffusion tensor is aligned with the nerve fibers, i.e., longitudinally in the spinal cord. The underlying hypothesis of this study is that the presence of collateral nerve fibers running orthogonal to the longitudinal fibers results in an orderly arrangement of the second eigenvectors. Magnetic resonance diffusion tensor scans were performed with line scan diffusion imaging on a clinical MR scanner. Axial sections were scanned in a human cervical spinal cord specimen at 625 microm resolution and the cervical spinal cord of four normal volunteers at 1250 microm resolution. The spinal cord specimen was fixed and stained for later light microscopy of the collateral fiber architecture at 0.53 microm resolution. Diffusion measured by MR was found to be anisotropic for both white and gray matter areas of the spinal cord specimen; the average fractional anisotropy (FA) was 0.63 +/- 0.09 (diffusion eigenvalues lambda1 0.38 +/- 0.05 micros/mm2, lambda2 0.14 +/- 0.03 micros/mm2, lambda3 0.10 +/- 0.03 micros/mm2) in white matter and 0.27 +/- 0.04 (lambda1 0.36 +/- 0.04 micros/mm2, lambda2 0.28 +/- 0.03 micros/mm2, lambda3 0.21 +/- 0.04 micros/mm2 in gray matter. The normal-volunteer FA values were similar, i.e., 0.66 +/- 0.04 (lambda1 1.66 +/- 0.14 micros/mm2, lambda2 0.55 +/- 0.02 micros/mm2, lambda3 0.40 +/- 0.01 micros/mm2) in white matter and 0.35 +/- 0.03 (lambda1 1.14 +/- 0.07 micros/mm2, lambda2 0.70 +/- 0.03 micros/mm2, lambda3 0.58 +/- 0.02 micros/mm2) in gray matter. The first eigenvector pointed, as expected, in the longitudinal direction. The second eigenvector directions exhibited a striking arrangement, consistent with the distribution of interconnecting collateral nerve fibers discerned on the histology section. This finding was confirmed for the specimen by quantitative pixel-wise comparison of second eigenvector directions and collateral fiber directions assessed on light microscopy image data. Diffusion tensor MRI can reveal non-invasively and in great detail the intricate fiber architecture of the human spinal cord.

Adult↗
PubMed2004

Persistent severe amnesia due to seizure recurrence after unilateral temporal lobectomy.

Anterograde amnesia is a severely disabling state which has been reported as a consequence of bilateral mesiotemporal lesions in humans. In the present paper, recurrent epileptic seizures after temporal lobectomy are described as a rare cause of severe amnesia in two patients. Diffusion-weighted MRI in one patient showed cytotoxic edema during a nonconvulsive status epilepticus and subsequent progressive hippocampal atrophy within the following month. In the other patient, repeated conventional MRI revealed no structural abnormalities in the contralateral temporal lobe.

Adult↗
PubMed2001

Early MRI findings of rapidly destructive coxopathy.

To diagnose rapidly destructive coxopathy (RDC) in its early stages and understand the pathomechanism of associated joint destruction, ten cases of RDC were followed by periodic MRI from onset of the disease. In the initial stage (stage 1) of RDC, when radiographs revealed slight narrowing of the joint space, a small subchondral area of low signal intensity was observed on T(1)-weighted images (T1WI) and inhomogeneous high intensity was observed on T(2)-weighted images (T2WI) in the antero-lateral portion of the femoral head. When radiographs showed obliteration of the joint space (stage 2), MRI revealed a diffuse area of low intensity on TIWI and high intensity on T2WI in the proximal femur, including the femoral neck and head, suggesting extensive bone marrow edema. The femoral head and acetabulum were aggressively destroyed (stage 3) in all cases 3 to 6 months after the diffuse abnormal pattern was observed on MRI. MRI in stage 3 cases showed low intensity areas on both T1WI and T2WI. RDC did not show the band-like pattern of low intensity on T1WI and high intensity on T2WI that typify MRI findings in cases of osteonecrosis. When joint space narrowing is observed radiographically, the diffuse abnormal pattern of low intensity on T1WI and high intensity on T2WI induced by a subchondral small lesion might be an early sign of RDC.

Aged↗
PubMed2006

[Evolution rules and clinical value of apparent diffusion coefficient in cerebral infarction].

OBJECTIVE: To determine the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the stage, guiding treatment or judging the prognosis in infarction. METHODS: Eighty-eight work-ups in 69 patients with cerebral infarction (8 hyperacute, 35 acute, 20 subacute, and 25 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC, the average relative ADC (rADC), and the ADC or rADC from the center to the periphery of the lesion were calculated. RESULTS: The average ADC and the average rADC of hyperacute and acute infarction lesion depressed obviously. The average ADC and the average rADC of subacute infarction lesion were significantly higher than those of hyperacute and acute infarction lesion (P < 0.05), and some approached the values of uninjured side which appeared "pseudonormal values" at 10 to 14 days. The average ADC and the average rADC in chronic infarction lesion were the highest (P < 0.05). The longer the prognosis, the higher the average ADC and the average rADC of infarction lesion. The ADC and the rADC in 7 hyperacute and 26 acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC and the rADC in 15 subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. CONCLUSION: The ADC and the rADC of infarction lesions have evolution rules with time and space corresponding to the pathophysiological foundation. The evolution rules with time and those in space can be helpful to decide the clinical stage and pathophysiological phase of infarction, and to provide the evidence in guiding the treatment or judging the prognosis in infarction.

Aged↗
PubMedDate not supplied

Qualitative evaluation of chronic diffuse liver disease by STIR MRI.

OBJECTIVE: The purpose of our study was to characterize the relationship between signal intensity on STIR MRI, histology, and liver function. MATERIALS AND METHODS: MRI was performed in 39 patients with chronic liver diseases [chronic persistent hepatitis (CPH), chronic active hepatitis (CAH), liver cirrhosis (LC)] and 11 patients without liver dysfunction (normal). RESULTS: On STIR images, very low signal intensities compared with those of the spleen were seen in all 11 normal livers (100%), and brighter intensities were seen in chronic diffuse liver diseases (10 patients with CPH, 11 patients with CAH, and 18 patients with LC) (100%). The higher the signal grade on STIR images (moderate, marked), the more advanced was the chronic diffuse liver disease (p < 0.02). The levels of serum glutamic-oxaloacetic and glutamic-pyruvic transaminase increased in parallel with increasing signal intensity on STIR images (both p < 0.01). CONCLUSION: We found that the signal intensity of liver on STIR images appeared to be associated with the degree of histologic and/or clinical severity in patients with chronic liver disease.

Adult↗
PubMed2002

[A case of herpes simplex virus encephalitis characterized by prolonged psychotic symptoms in convalescence--a case report].

A 14-year-old girl was diagnosed as having herpes simplex encephalitis by a polymerase chain reaction examination of the cerebrospinal fluid. MRI showed diffuse high signal areas at the bilateral temporal lobes and right frontal lobe. She was treated with a total of 350 mg/kg of acyclovir for 23 days, and discharged without abnormal neurological findings. On the 90th day after the onset, however, she became excitable and aggressive to her family. She excessively seeked relations with several boy friends. MRI revealed dilation of the bilateral ventricles and atrophy of the temporal lobes. These pathologic changes including the atrophy of hippocampus may be responsible for the character changes in this case.

Adolescent↗
PubMed2003

Spontaneous intracranial hypotension in a patient with reversible pachymeningeal enhancement and brain descent.

A 56-year-old woman presented with severe orthostatic headache in association with nausea and vomiting. Lumbar puncture for the patient revealed significantly low cerebrospinal fluid pressure (CSF) and the clinical diagnosis of intracranial hypotension syndrome was made. An initial gadolinium-enhanced brain magnetic resonance imaging (MRI) disclosed diffuse meningeal enhancement as well as brain sagging. No definite CSF leakage was found using radionuclide cisternography. Her headaches abated with proper usage of analgesics, strict bed rest, and intravenous hydration. Follow-up neuroimaging studies showed partially resolved meningeal enhancement 2 months after treatment and complete resolution 6 months after treatment. The temporal changes found on MRI suggest that the pachymeningeal enhancement is reversible in patients with spontaneous intracranial hypotension. Moreover, proliferation of meninges is likely to be responsible for this type of delayed resolution phenomenon.

Brain↗
PubMed1999

MRI edge enhancement as a diffusive discord of spin phase structure.

The enhancement of magnetic resonance image intensity near impermeable boundaries can be nicely described by a new approach where the diffusional spin echo attenuation is linked to the correlation function of molecular motion. In this method the spin phase structure created by the applied gradient is considered to be a composition of plane waves with the wave vectors representing feasible momentum states of a particle in confinement. The enhancement of edges on the magnetic resonance images (MRI) comes out as a discord of plane waves due to particle motion. It results from the average of the wave phase by using the cumulant expansion in the Gaussian approximation. The acquired analytical expression describes the MRI signal space distribution where the enhancement of edges depends on the intensity and the duration of gradient sequence as well as on the length of the mean squared particle displacement in restricted geometry. This new method works well with gradients of general waveform and is, therefore, suitable for imaging sequences where finite or even modulated gradients are usually used.

Artifacts↗
PubMed1996

Serial MRI and neurophysiological studies in late-infantile Krabbe disease.

We report serial clinical, radiological, and neurophysiological findings of a patient with late-infantile Krabbe disease. At age 13 months, the patient was hospitalized for sudden stiffness and irritability and a diagnosis of spastic diplegia was made. At age 24 months, he was readmitted because of further psychomotor deterioration; neurologically, he manifested severe spastic tetraplegia with optic atrophy. MRI disclosed diffuse high intensity in the cerebral white matter on T2-weighted images. Nerve conduction velocity and evoked potential studies were markedly abnormal, as were the EEG and the EMG. Assay of galactocerebroside beta-galactosidase activity in leukocyte culture disclosed a marked deficiency of the enzyme, confirmatory of the diagnosis of late-infantile Krabbe disease. Serial MRI and neurophysiological studies performed every 6 months for 18 months demonstrated the progressive nature of the disorder, correlating with the clinical deterioration.

Brain↗
PubMed2004

[Efficacy and safety of treatment of acute ischemic stroke with glycoprotein IIb/IIIa receptor blocker in routine clinical practice].

BACKGROUND: Platelet aggregation plays an important pathophysiological role in the incidence of myocardial infarction and ischemic stroke. The expression of glycoprotein IIb/IIIa receptors on the surface of activated platelets is the final common pathway of platelet aggregation. PATIENTS AND METHODS: Encouraged by the favorable outcome in acute coronary syndromes and by preliminary results, which substantiate the efficacy and safety of GP IIa/III antagonists (GP) in ischemic stroke, we treated 21 cases/20 patients (13 male, 7 female, age 39-79 y.) and conducted a retrospective study using a clinical graduation scale (Modified Rankin Scale MRS). Patients received tirofiban (n = 18) or eptifibatide (n = 3) in the usual cardiological dose 3 h (0.5-8 h) after beginning of symptoms together with "full dose " heparin (n = 8) or "low dose" heparin (n = 12) in the acute phase, with aspirin 100 mg (n = 4), Clopidrogel 75 mg (n = 5), aspirin + clopidogrel (n = 4) in the chronic phase. All patients had a cranial CT, 95% an echocardiography and Doppler sonography of the carotid artery system and some cranial MRI (43%). RESULTS: There was no significant clinical deterioration. All except one patient showed a rapid and impressive improvement during the first 24 h after initiation of treatment (median MRS pre/post 3/1). CONCLUSION: The results with GP in acute ischemic stroke are promising and further studies should be initiated using especially tirofiban, but with monitoring by cerebral diffusion-weighted MRI before and after treatment.

Adult↗
PubMed2003

Pharmacokinetic mapping of breast tumors: a new statistical analysis technique for dynamic magnetic resonance imaging.

Breast cancer is the most common malignancy among women, constituting a major health problem. Different MRI techniques have been investigated in the past in order to improve the detection and diagnosis of breast tumors. One such technique is the dynamic contrast-enhanced T1-weighted magnetic resonance imaging (DCE-MRI), using diffusible CM (contrast media), such as Gd-DTPA. Here we employ a two compartment CM kinetics model (blood plasma and surrounding interstitial space being the two compartments), where the exchange of contrast agent between these compartments is bidirectionally linear. In this study we use images from 29 suspected breast carcinoma patients who underwent whole breast DCE-MRI. Each of these studies has 64 coronal sections of the whole breast, taken at 6 or 7 time points (the sampling period being about 2 minutes). Subsequent histo-pathological analysis of these patients reveal: 22 intraductal carcinomas (IDC), 3 intralobular carcinomas (ILC), 2 ductal carcinomas in-situ (DCIS) and 3 benign tumors.

Breast Neoplasms↗
PubMed2004

Improved prediction of final infarct volume using bolus delay-corrected perfusion-weighted MRI: implications for the ischemic penumbra.

BACKGROUND AND PURPOSE: Magnetic resonance imaging (MRI)-based perfusion measures using dynamic susceptibility contrast are extremely useful for identification of ischemic penumbral tissue in acute stroke. However, errors in the measurement of cerebral blood flow (CBF) and mean transit time (MTT) can occur. The aim of this study was to investigate whether bolus delay-corrected (BDC) perfusion measures enable better delineation of the ischemic penumbra. METHODS: Diffusion-weighted MRI (DWI) and perfusion-weighted MRI data were acquired from 19 acute stroke patients. Perfusion abnormalities were manually defined on BDC perfusion maps (corrected MTT [cMTT] and corrected CBF [cCBF]), and on maps derived from an arterial input function placed within the contralateral (CBF, MTT) and ipsilateral (ipsilateral CBF [iCBF] and ipsilateral MTT [iMTT]) middle cerebral artery. Perfusion lesion volumes were correlated with 30-day T2-weighted MRI lesion volumes and with clinical outcome using the National Institutes of Health Stroke Scale (NIHSS). RESULTS: Spearman correlation coefficients for comparing lesion volumes delineated on DWI, CBF, iCBF, cCBF, MTT, iMTT, and cMTT maps with 30-day T2-weighted lesion volumes were 0.72, 0.87, 0.88, 0.90, 0.84, 0.92, and 0.96, respectively (all P<0.001). The analogous correlation coefficients for comparing 30-day National Institutes of Health Stroke Scale (NIHSS) scores were 0.39 (NS), 0.69 (NS), 0.75 (P<0.001), 0.62 (NS), 0.72 (P<0.001), 0.78 (P<0.001), and 0.83 (P<0.001), respectively. CONCLUSIONS: Uncorrected perfusion lesion volumes overestimated the extent of ischemic injury. BDC perfusion measures (cMTT) correlated more accurately with final lesion volume and clinical outcome. Such measures offer an improved estimation of the final infarct size in acute stroke.

Aged↗
PubMed2003

Diffusion weighted MR imaging of acute Wernicke's encephalopathy.

We report a case of Wernicke's encephalopathy in which diffusion-weighted MR images demonstrated symmetrical hyperintense lesions in the paraventricular area of the third ventricles and medial thalami. Apparent diffusion coefficient mapping showed isointensity in the aforementioned areas. Diffusion-weighted MR images may provide evidence of vasogenic edema associated with thiamine deficiency, proven in the histopathology of experimental animals. In addition, diffusion-weighted MRI has many advantages over T2 or FLARE-weighted brain MRI in detecting structural and functional abnormalities in Wernicke's encephalopathy.

Acute Disease↗
PubMed2005

Reconstruction as a source of artifact in non-gated single-shot diffusion-weighted EPI.

A controversy has existed over the requirement to cardiac gate diffusion-weighted MRI acquisitions of the brain. Conventional wisdom suggests gating to be a necessary requirement to allow acquisition of accurate data, but recent applications find gating not necessary. The signal-to-noise and acquisition duration of these two approaches can be quite different; thus, this difference in methodology is important. This is particularly relevant when performing quantitative work such as diffusion tensor imaging. Here, the convention to gate is explained as being due to the historical use of low spatial resolution and more recently to the use of different reconstruction approaches. It is demonstrated that the Margosian reconstruction approach only yields high quality results when used in a gated fashion. Zero padding of the acquisition matrix provides an alternative reconstruction method that is not found to accentuate the artifacts that are due to pulsatile motion in the diffusion-weighted acquisition and thus do not require a gated acquisition. The relative merits of each reconstruction approach are discussed, including estimates of the relative signal-to-noise ratio and resolution benefits. It is concluded that both gated methods and non-gated methods can each provide high quality results with appropriate reconstruction methods.

Artifacts↗