1,097 research outputs found

    Microtesla MRI of the human brain combined with MEG

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    One of the challenges in functional brain imaging is integration of complementary imaging modalities, such as magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI). MEG, which uses highly sensitive superconducting quantum interference devices (SQUIDs) to directly measure magnetic fields of neuronal currents, cannot be combined with conventional high-field MRI in a single instrument. Indirect matching of MEG and MRI data leads to significant co-registration errors. A recently proposed imaging method - SQUID-based microtesla MRI - can be naturally combined with MEG in the same system to directly provide structural maps for MEG-localized sources. It enables easy and accurate integration of MEG and MRI/fMRI, because microtesla MR images can be precisely matched to structural images provided by high-field MRI and other techniques. Here we report the first images of the human brain by microtesla MRI, together with auditory MEG (functional) data, recorded using the same seven-channel SQUID system during the same imaging session. The images were acquired at 46 microtesla measurement field with pre-polarization at 30 mT. We also estimated transverse relaxation times for different tissues at microtesla fields. Our results demonstrate feasibility and potential of human brain imaging by microtesla MRI. They also show that two new types of imaging equipment - low-cost systems for anatomical MRI of the human brain at microtesla fields, and more advanced instruments for combined functional (MEG) and structural (microtesla MRI) brain imaging - are practical.Comment: 8 pages, 5 figures - accepted by JM

    Identification of osteopontin as a novel marker for early hepatocellular carcinoma

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    The aim of this study was to identify a biomarker that could improve alpha‐fetoprotein (AFP) performance in hepatocellular carcinoma (HCC) surveillance among patients with cirrhosis. We performed proteomic profiling of plasma from patients with cirrhosis or HCC and validated selected candidate HCC biomarkers in two geographically distinct cohorts to include HCC of different etiologies. Mass spectrometry profiling of highly fractionated plasma from 18 cirrhosis and 17 HCC patients identified osteopontin (OPN) as significantly up‐regulated in HCC cases, compared to cirrhosis controls. OPN levels were subsequently measured in 312 plasma samples collected from 131 HCC patients, 76 cirrhosis patients, 52 chronic hepatitis C (CHC) and B (CHB) patients, and 53 healthy controls in two independent cohorts. OPN plasma levels were significantly elevated in HCC patients, compared to cirrhosis, CHC, CHB, or healthy controls, in both cohorts. OPN alone or in combination with AFP had significantly better area under the receiver operating characteristic curve, compared to AFP, in comparing cirrhosis and HCC in both cohorts. OPN overall performance remained higher than AFP in comparing cirrhosis and the following HCC groups: HCV‐related HCC, HBV‐associated HCC, and early HCC. OPN also had a good sensitivity in AFP‐negative HCC. In a pilot prospective study including 22 patients who developed HCC during follow‐up, OPN was already elevated 1 year before diagnosis. Conclusion : OPN was more sensitive than AFP for the diagnosis of HCC in all studied HCC groups. In addition, OPN performance remained intact in samples collected 1 year before diagnosis. (H EPATOLOGY 2012)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90204/1/24703_ftp.pd

    Clinical utility of serum fucosylated hemopexin in Japanese patients with hepatocellular carcinoma

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    Aim: Hepatocellular carcinoma (HCC) is a common clinical problem all over the world. Fucosylated hemopexin (Fuc-Hpx) is a newly reported glycoprotein for the diagnosis of HCC, however, its clinical implications are unclear. The aim of this study was to elucidate the clinical utility of Fuc-Hpx in Japanese patients with HCC. Methods: The sera from 331 HCC patients, 45 with liver cirrhosis (LC), 85 with chronic hepatitis (CH) and 22 healthy people were examined for the expression of Fuc-Hpx; the level was compared with clinical parameters as well as hemopexin (Hpx) expression. The expressions of Fuc-Hpx in 12 HCC tissues and corresponding adjacent non-cancerous liver tissues were also examined. Results: No correlation was observed between Hpx and Fuc-Hpx level. The median Fuc-Hpx levels in healthy people and CH, LC and HCC patients were 3.8, 3.7, 6.1 and 7.6 AU/mL, respectively (CH vs LC, P = 0.002; CH vs HCC, P < 0.001; LC vs HCC, P = 0.02). Multivariate analysis revealed that low albumin, low prothrombin time and the presence of HCC were significantly correlated with high Fuc-Hpx (P = 0.013, =0.001 and <0.001, respectively). Among the HCC patients, albumin was correlated with high Fuc-Hpx; however, none of the tumor factors, such as tumor size, tumor number and tumor stage, was correlated with Fuc-Hpx level. The expression of Fuc-Hpx in cancer tissue was not different from that in non-cancerous tissue. Conclusion: Fuc-Hpx is a valuable biomarker for HCC but it might be a marker for hypercarcinogenic liver rather than a marker for tumor-bearing liver

    Mapping In Vivo Tumor Oxygenation within Viable Tumor by 19F-MRI and Multispectral Analysis

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    AbstractQuantifying oxygenation in viable tumor remains a major obstacle toward a better understanding of the tumor microenvironment and improving treatment strategies. Current techniques are often complicated by tumor heterogeneity. Herein, a novel in vivo approach that combines 19F magnetic resonance imaging (19F-MRI)R1 mapping with diffusionbased multispectral (MS) analysis is introduced. This approach restricts the partial pressure of oxygen (pO2) measurements to viable tumor, the tissue of therapeutic interest. The technique exhibited sufficient sensitivity to detect a breathing gas challenge in a xenograft tumor model, and the hypoxic region measured by MS 19F-MRI was strongly correlated with histologic estimates of hypoxia. This approach was then applied to address the effects of antivascular agents on tumor oxygenation, which is a research question that is still under debate. The technique was used to monitor longitudinal pO2 changes in response to an antibody to vascular endothelial growth factor (B20.4.1.1) and a selective dual phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor (GDC-0980). GDC-0980 reduced viable tumor pO2 during a 3-day treatment period, and a significant reduction was also produced by B20.4.1.1. Overall, this method provides an unprecedented view of viable tumor pO2 and contributes to a greater understanding of the effects of antivascular therapies on the tumor's microenvironment
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