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Isamu Ohashi - One of the best experts on this subject based on the ideXlab platform.

  • relationship between bone marrow cellularity and Apparent Diffusion Coefficient
    Journal of Magnetic Resonance Imaging, 2001
    Co-Authors: Yoshie Nonomura, Mayumi Yasumoto, Ryoichi Yoshimura, Kyoko Haraguchi, Sukeyuki Ito, Takumi Akashi, Isamu Ohashi
    Abstract:

    This study was performed to determine if there is a relationship between Apparent Diffusion Coefficient (ADC) and cellularity of bone marrow of the posterior ilium. Four groups of various marrow cellularity underwent Diffusion-weighted echo-planar imaging: 1) adults with normal hypocellularity (21 patients); 2) adults with normal normocellularity (13 patients); 3) young children with normal hypercellularity (5 patients); and 4) adults with lymphoma-related hypercellularity (3 patients). In all adults, marrow cellularity was confirmed by uni-or bilateral bone marrow biopsies. In children, the iliac marrow was presumed hypercellular because of their ages. A total of 66 ADC values of bone marrow calculated from Diffusion-weighted images with b-values of 30 and 300 seconds/mm(2) was evaluated. Hypercellular marrow (normal and lymphoma-related) showed the highest mean ADC, and hypocellular the lowest ADC. Statistically significant differences were found between three groups of normal marrow: hypocellular, normocellular, and hypercellular. There is a positive correlation between ADC and cellularity of bone marrow. J. Magn. Reson. Imaging 2001;13:757-760.

  • relationship between bone marrow cellularity and Apparent Diffusion Coefficient
    Journal of Magnetic Resonance Imaging, 2001
    Co-Authors: Yoshie Nonomura, Mayumi Yasumoto, Ryoichi Yoshimura, Kyoko Haraguchi, Takumi Akashi, Isamu Ohashi
    Abstract:

    This study was performed to determine if there is a relationship between Apparent Diffusion Coefficient (ADC) and cellularity of bone marrow of the posterior ilium. Four groups of various marrow cellularity underwent Diffusion-weighted echo-planar imaging: 1) adults with normal hypocellularity (21 patients); 2) adults with normal normocellularity (13 patients); 3) young children with normal hypercellularity (5 patients); and 4) adults with lymphoma-related hypercellularity (3 patients). In all adults, marrow cellularity was confirmed by uni-or bilateral bone marrow biopsies. In children, the iliac marrow was presumed hypercellular because of their ages. A total of 66 ADC values of bone marrow calculated from Diffusion-weighted images with b-values of 30 and 300 seconds/mm2 was evaluated. Hypercellular marrow (normal and lymphoma-related) showed the highest mean ADC, and hypocellular the lowest ADC. Statistically significant differences were found between three groups of normal marrow: hypocellular, normocellular, and hypercellular. There is a positive correlation between ADC and cellularity of bone marrow. J. Magn. Reson. Imaging 2001;13:757–760. © 2001 Wiley-Liss, Inc.

  • anisotropic Diffusion in kidney Apparent Diffusion Coefficient measurements for clinical use
    Journal of Magnetic Resonance Imaging, 2000
    Co-Authors: Yutaka Fukuda, Isamu Ohashi, Kaoru Hanafusa, Tsuneaki Nakagawa, Shinichi Ohtani, Yasushi Annaka, Tokio Hayashi, Hitoshi Shibuya
    Abstract:

    The purpose of this study was to evaluate anisotropy of the kidney by measurements of the Apparent Diffusion Coefficient (ADC) using commercially available magnetic resonance (MR) imaging. Fifty-one consecutive patients underwent Diffusion-weighted echoplanar MR imaging of the upper abdomen with five different strengths of motion probing gradients (b = 1.51, 55.3, 36.6, 317, and 932 sec/mm2) applied along the z-axis. Four ADC values for the upper pole and central portion of the kidney were calculated from four different b-value ranges and compared. The ADCs for the kidney calculated in the lower b-value ranges were significantly higher than those in the higher ranges. The ADCs for the upper pole portion were significantly higher than those for the central portion except for one in the highest b-value range. Diffusion in the kidney is anisotropic, probably due to the kidney's radially oriented structures such as renal vessels and tubules. J. Magn. Reson. Imaging 2000;11:156–160. © 2000 Wiley-Liss, Inc.

Nandita M Desouza - One of the best experts on this subject based on the ideXlab platform.

  • Apparent Diffusion Coefficient from magnetic resonance imaging as a biomarker in oncology drug development
    European Journal of Cancer, 2012
    Co-Authors: Ralph Sinkus, Nandita M Desouza, Bernard E Van Beers, Valerie Vilgrain, John C Waterton
    Abstract:

    Magnetic resonance imaging (MRI) can be made sensitive to Diffusion of water molecules in biological tissues: this phenomenon can be quantitated to provide a biomarker, the Apparent Diffusion Coefficient (ADC). Over the past decade, evidence has accumulated from numerous clinical and animal studies that ADC is abnormal in tumours; that elevated ADC reflects an elevated non-cellular fraction; and that acute increases in ADC following therapy can indicate that tumour cells have been killed. However there remain substantial challenges in ensuring robust and valid ADC measurements, particularly in multicentre studies in common sites of metastasis such as lung and liver. Moreover, there is uncertainty about how best to select the timing of observation post-therapy to avoid false-negatives, and how to minimise the confounding factors which could decouple drug-induced ADC increase from drug-induced cell kill. In this review we summarise the physical basis of the biomarker, the evidence that it reflects non-viable fraction, particularly in extracranial tumours, and suggest a roadmap for validation and qualification.

  • Diffusion weighted imaging of the normal breast reproducibility of Apparent Diffusion Coefficient measurements and variation with menstrual cycle and menopausal status
    European Radiology, 2012
    Co-Authors: Elizabeth Oflynn, Veronica A Morgan, Sharon L Giles, Nandita M Desouza
    Abstract:

    Objectives To establish the reproducibility of Apparent Diffusion Coefficient (ADC) measurements in normal fibroglandular breast tissue and to assess variation in ADC values with phase of the menstrual cycle and menopausal status.

  • mri in the detection of prostate cancer combined Apparent Diffusion Coefficient metabolite ratio and vascular parameters
    American Journal of Roentgenology, 2009
    Co-Authors: Sophie F Riches, Veronica A Morgan, Geoffrey S Payne, Samir Sandhu, Cyril Fisher, Michael Germuska, D J Collins, Alan Thompson, Nandita M Desouza
    Abstract:

    OBJECTIVE. The purpose of this study was to compare Apparent Diffusion Coefficients, metabolic ratios, and vascularity values within histologically defined prostate tumors with those in nontumor tissue to determine which functional parameter or combination of parameters is best for differentiating tumor from nontumor tissue.SUBJECTS AND METHODS. Twenty patients due for prostatectomy underwent endorectal MRI at 1.5 T. Transverse T2-weighted, Diffusion-weighted, 2D chemical shift, and dynamic contrast-enhanced images were acquired. After prostatectomy, the gland was sectioned transversely. Fresh slices and stained whole-mount sections with histologically defined tumor outlines were photographed. The tumor outlines were mapped onto images, and the Apparent Diffusion Coefficient (ADC), choline-to-citrate (Cho/cit) ratio, and vascularity of the histologically defined tumor, normal peripheral zone, and central gland were quantitatively measured. Area under the receiver operating characteristics (ROC) curve (Az)...

Hans Rolf Jager - One of the best experts on this subject based on the ideXlab platform.

Daniel J Tozer - One of the best experts on this subject based on the ideXlab platform.

  • low grade gliomas six month tumor growth predicts patient outcome better than admission tumor volume relative cerebral blood volume and Apparent Diffusion Coefficient
    Radiology, 2009
    Co-Authors: Gisele Brasil Caseiras, Daniel J Tozer, Paul S Tofts, Jeremy Rees, O Ciccarelli, Daniel R Altmann, C Benton, T A Yousry, Adam D Waldman, Hans Rolf Jager
    Abstract:

    Tumor growth within 6 months was better than baseline volumes, relative cerebral blood volume, or Apparent Diffusion Coefficient in predicting time to malignant transformation in untreated low-grade gliomas and was independent of other parameters, including histologic findings.

  • Apparent Diffusion Coefficient histograms may predict low grade glioma subtype
    NMR in Biomedicine, 2007
    Co-Authors: Daniel J Tozer, Rolf H Jager, Nasuda Danchaivijitr, Christopher E Benton, Paul S Tofts, Jeremy Rees, A D Waldman
    Abstract:

    The subtypes of glioma are known to have different prognosis and response to treatment. The purpose of this work was to investigate whether Apparent Diffusion Coefficient (ADC) histograms of untreated low-grade astrocytomas and oligodendrogliomas exhibit different characteristics due to their biological differences, and whether a diagnosis of tumour subtype can be made at presentation using the histogram alone, which, if possible, would have an impact on clinical practise. Fifteen patients with astrocytoma (AC) [11 male (mean age +/- standard deviation) 40 +/- 11 years], nine with oligodendroglioma (OD) (four male, 45 +/- 13 years) and three with oligoastrocytoma (OA) (two male, 60 +/- 11 years) were recruited and Diffusion-weighted images (b = 0 and 1000 s mm(-2)) were acquired every 6 months to date or until malignant transformation. Whole tumour ADC histograms were calculated, a multiple discriminant analysis was performed and quantitative morphological parameters extracted, the AC and OD subtypes were then compared using Student's unpaired t-test. Classification of the histograms was also performed. ODs had significantly lower group ADC values than ACs and up to 83% of the subjects could be correctly classified into the OD and AC groups by reference to the histogram. The group differences were most significant for the multiple discriminant analysis (p = 1 x 10(-5)) and at the 10th centile point [AC = 1170 +/- 170, OD = (1030 +/- 80) x 10(-6) mm(2) s(-1)] (p = 0.01). ODs have a lower ADC than ACs with differences throughout the histogram. Both tumour types show similar intra-tumour heterogeneity, as seen from the equal group peak heights, but ACs shows more intra-group heterogeneity. ADC histogram analysis may aid non-invasive sub-classification of low-grade glioma histological subtypes.

A D Waldman - One of the best experts on this subject based on the ideXlab platform.

  • Apparent Diffusion Coefficient histograms may predict low grade glioma subtype
    NMR in Biomedicine, 2007
    Co-Authors: Daniel J Tozer, Rolf H Jager, Nasuda Danchaivijitr, Christopher E Benton, Paul S Tofts, Jeremy Rees, A D Waldman
    Abstract:

    The subtypes of glioma are known to have different prognosis and response to treatment. The purpose of this work was to investigate whether Apparent Diffusion Coefficient (ADC) histograms of untreated low-grade astrocytomas and oligodendrogliomas exhibit different characteristics due to their biological differences, and whether a diagnosis of tumour subtype can be made at presentation using the histogram alone, which, if possible, would have an impact on clinical practise. Fifteen patients with astrocytoma (AC) [11 male (mean age +/- standard deviation) 40 +/- 11 years], nine with oligodendroglioma (OD) (four male, 45 +/- 13 years) and three with oligoastrocytoma (OA) (two male, 60 +/- 11 years) were recruited and Diffusion-weighted images (b = 0 and 1000 s mm(-2)) were acquired every 6 months to date or until malignant transformation. Whole tumour ADC histograms were calculated, a multiple discriminant analysis was performed and quantitative morphological parameters extracted, the AC and OD subtypes were then compared using Student's unpaired t-test. Classification of the histograms was also performed. ODs had significantly lower group ADC values than ACs and up to 83% of the subjects could be correctly classified into the OD and AC groups by reference to the histogram. The group differences were most significant for the multiple discriminant analysis (p = 1 x 10(-5)) and at the 10th centile point [AC = 1170 +/- 170, OD = (1030 +/- 80) x 10(-6) mm(2) s(-1)] (p = 0.01). ODs have a lower ADC than ACs with differences throughout the histogram. Both tumour types show similar intra-tumour heterogeneity, as seen from the equal group peak heights, but ACs shows more intra-group heterogeneity. ADC histogram analysis may aid non-invasive sub-classification of low-grade glioma histological subtypes.