OBJECTIVETo explore the influence of conventional metal materials in oral cavity on brain magnetic resonance imaging (MRI).

METHODSFour kinds of metal materials (metal ligature wire, forging hard and slotless denture, casting nichrome denture, casting copper alloy denture) in oral cavity were scanned through MRI. FSE sequence T1 weighted imaging (FSE T1), EPI diffusion-weighted imaging (DWI) sequence of ordinary, Propeller DWI imaging were used.

RESULTSIn FSE T1 sequence, metal ligature wire and forging hard and slotless denture produced serious false image, casting nichrome denture produced moderate false image, casting copper alloy denture produced only little false image. In EPI DWI sequence, obvious magnetic-sensitive false image were produced in the dissection tissue of the brain by metal ligature wire. While in Propeller DWI sequence, magnetic-sensitive false image were greatly reduced and satisfactory images were formed.

CONCLUSIONDifferent metal materials in oral cavity have different influence on the MRI. The false images produced by different metal materials are closely related to the type of the material. Magnetic-sensitive false images can be eliminated by Propeller DWI technique.

OBJECTIVE: The aim of this study is to assess the significance of an apparent diffusion coefficient(ADC) study for diagnosis of ventriculitis. METHODS: Seven patients with ventriculitis were enrolled in this study. Diffusion-weighted(DW) magnetic resonance images(MRI) and ADC maps in the dependent intraventricular collection, periventricular white matter and non-dependent cerebrospinal fluid(CSF) were obtained. The images and ADC data from the different lesions were compared. RESULTS: The DW MRI showed marked hyperintensity in the purulent pus lesion, and the corresponding ADC maps revealed prominent hypointensity and restricted ADC values compared with the non-dependent CSF and normal white matter. CONCLUSION: The decreased ADC value and increased signal intensity of the dependent intraventricular fluid on the DW MRI show restricted water diffusion in the purulent fluid, which is indicative of a pyogenic ventriculitis diagnosis.
Diagnosis ; Diffusion* ; Humans ; Magnetic Resonance Imaging ; Suppuration

PURPOSE: To evaluate diffusion-weighted imaging findings of intracerebral hematoma according to the time sequence. MATERIALS AND METHODS: Seventeen patients with intracerebral hematoma were studied. Diffusion weighted images using 1.5 tesla MRI machine were obtained with b-value of 1000 sec/mm2. The patients were grouped as hyperacute stage(within 12 hours, 5 patients), acute stage(within 3 days, 4 patients), subacute stage(within 3 weeks, 4 patients), and chronic stage(after 3 weeks,4 patients). The signal intensities were analysed as bright, high, iso, low and dark at the central and peripheral portions of the hematoma in each stage, and compared with those of T2 and T1 weighted images. RESULTS: The signal intensities of the central and peripheral portion of the intracerebral hematoma on diffusion-weighted images were high and dark in hyperacute stage, dark and high-bright in acute stage, and high-bright and dark in subacute and chronic stages. The patterns of signal change of hematoma on diffusion-weighted image according to the time sequence were similar to those on T2-weighted image, but 1 early and prominently. CONCLUSION: The intracerebral hematoma on diffusion-weighted image showed unique central and peripheral signal intensity according to the time sequence. Central portions show high to bright signals in hyperacute, subacute and chronic stage, and dark signal in acute stage, and peripheral portions show dark signals in hyperacute, subacute and chronic stage, and high to bright signal in acute stage.
Diffusion ; Hematoma* ; Humans ; Magnetic Resonance Imaging*

Diffusion Magnetic Resonance Imaging ; Humans ; Liver Diseases

Cerebral white matter tracts are altered by a brain tumor. We report a case of gliomatosis cerebri where the diffusion tensor fiber tract passes through the tumor.
Brain Neoplasms ; Diffusion Magnetic Resonance Imaging ; Diffusion* ; Neoplasms, Neuroepithelial*

Reversible splenial lesion may occur in encephalitis rarely. A 21-year-old man was admitted with viral encephalitis. High signal on the diffusion MRI and low signal on the ADC map image was showed in the splenium. As the patient improved, the lesion suggestive of cytotoxic edema was completely resolved one month later. Although the concrete pathophysiology of focal cytotoxic edema in encephalitis is unclear yet, MRI is valuable diagnostic tool to manage encephalitis in the view of prognosis.
Diffusion Magnetic Resonance Imaging* ; Diffusion* ; Edema ; Encephalitis* ; Encephalitis, Viral ; Humans ; Magnetic Resonance Imaging ; Prognosis ; Young Adult

PURPOSE: To evaluate the efficacy of superselective intra-arterial fibrinolysis for acute cerebral stroke and the usefulness of pre- and postfibrinolysis diffusion-weighted MRI (DWI). MATERIALS AND METHODS: In 41 patients with acute ischemic stroke whose treatment involved intra-arterial fibri-nolysis, the occlusion site, degree of recanalization, and clinical results were compared. In 12 patients, diffusion weighted MRI was performed before fibrinolysis, and eight of these also underwent diffusion-weighted MRI after fibrinolysis. Using diffusion-weighted MRI, neurological outcomes were compared with signal intensity ratio (SIR, or the average signal intensity within the region of interest divided by that in the contralateral, nonischemic, homologous region). RESULTS: Twenty patients showed complete recanalization, nine partial recanalization, and in twelve there was no recanalization. Fourteen patients (34 %) improved neurologically. No relationship existed between occlusion sites, degree of recanalization, and clinical outcome. Among 12 patients who underwent DWI before fibrinolysis, complete recanalization was noted in eight. Neurological improvement was seen in four patients with low SIR(<1.55),while in four with high SIR(>1.7 ), neurological outcome was poor despite complete recanalization. CONCLUSION: Although superselective intra-arterial fibrinolysis for acute cerebral stroke is a good therapeutic method for recanalization, the clinical outcome can be disappointing. We therefore suggest that in cases of acute cerebral ischemic infaret, SIR-as seen on DWI-might be useful for predicting the benefits of recanalization. In such cases, further investigation of the use of DWI prior to fibrinolysis is therefore needed.
Diffusion Magnetic Resonance Imaging ; Diffusion* ; Fibrinolysis* ; Humans ; Magnetic Resonance Imaging ; Stroke

PURPOSE: To determine the impact of pseudoglandular formation on apparent diffusion coefficient (ADC) values of hepatocellular carcinoma (HCC) in diffusion-weighted imaging (DWI), and to validate the results using histopathological grades. MATERIALS AND METHODS: We assessed 182 HCCs surgically resected from 169 consecutive patients. Each type of tumor pseudoglandular formation was categorized into “non-,” “mixed-,” or “pure-,” based on official histopathology reports. The ADC for each tumor was independently measured, using the largest region of interest on the ADC map. Data were assessed using the analysis of variance test, with Bonferroni correction for post hoc analysis to stratify the relationship of ADCs with pseudoglandular formation, followed by subgroup analysis according to the histopathological tumor grades. RESULTS: The mean ADC was significantly higher in pure pseudoglandular lesions (n = 5, 1.29 ± 0.08 × 10−3 mm2/s) than in non-pseudoglandular lesions (n = 132, 1.08 ± 0.17 × 10−3 mm2/s; P = 0.003) or mixed-pseudoglandular lesions (n = 45, 1.16 ± 0.24 × 10−3 mm2/s; P = 0.034). The ADC values and pseudoglandular formation were significantly correlated in moderately differentiated HCCs (n = 103; r = 0.307, P = 0.007), while well- (n = 19) and poorly-differentiated HCCs (n = 60) did not show significant correlation (r = 0.105 and 0.068, respectively; P = 0.600 and 0.685, respectively). CONCLUSION: The degree of pseudoglandular formation could be one of the determinants of ADC in DWI of HCCs-especially moderately differentiated HCCs-while its influence does not appear to be significant in well- or poorly differentiated HCCs.
Carcinoma, Hepatocellular ; Diffusion Magnetic Resonance Imaging ; Diffusion ; Humans ; Liver Diseases ; Liver Neoplasms ; Magnetic Resonance Imaging

The accurate diagnosis and staging of hepatic fibrosis is crucial for treatment and prognosis of liver disease. The current gold standard is liver biopsy, but it cannot be used in population-based screening, and has well known drawbacks if used for monitoring of disease progression or treatment results. Functional MR, as a non-invasive method, is increasingly used in hepatic fibrosis and became the current hot spot. Most recently available functional MR imaging techniques including diffusion weighted imaging, perfusion weighted imaging and MR spectroscopy can detect cirrhosis or fibrosis reasonably accurately. However, to date only MR elastography has been able to stage fibrosis or diagnose mild disease. MR diffusion weighted appears next most promising.
Diffusion Magnetic Resonance Imaging ; Humans ; Liver Cirrhosis ; classification ; diagnosis ; Magnetic Resonance Imaging ; methods ; Magnetic Resonance Spectroscopy

OBJECTIVE: To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. MATERIALS AND METHODS: A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. RESULTS: The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p < 0.05). The sensitivity of the diagnostic performance was higher with an additional DWI in both 1.5T and 3T, but the sensitivities were similar with the addition of b values of 400 and 1000. The specificities of the diagnostic performances did not show significant differences (p value > 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. CONCLUSION: The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T.
Diffusion ; Echo-Planar Imaging ; Edema* ; Magnetic Resonance Imaging* ; Spine