MR permeability mapping in vivo: characteristics of various tissues and usefulness as predictive index for treatment

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We have developed a frequency-selective fat saturated dual-echo 2DFLASH sequence to obtain T1weighted and T2* weighted gradient-echo images at one TR. The equipment used was Magnetome Vision (Siemens, 1.5T), and the parameters used were as follows; TR/TE1 ＆ TE2/FA=〜27/2.3 ＆ 20 /45 degrees, matrix 256x64, NEX=1. Single slice dynamic study was performed after intravenous bolus injection of Gd-DTPA (0.1mmol/kg) at a rate of 2cc/sec via superficial venous system of the upper extremities. Scanning was performed for approximately 2 minutes and the patients were asked to breathe shallowly and consistently during the examination.We focused on pelvic disease processes because they had little respiratory motion artifacts and pathologic evidence was relatively easily obtained in our instiute. We developed software to calculate pure T1 (R1) and pure T2* (R2*) images utilizing.the TE1 ＆ TE2 images. We also developed a software to facilitate to create precontrast T1-value mapping which is mandatory … More to calculate R1 ＆ R2* images. Sequential changes of R1 and R2* images were analyzed after Gd intravenous injection. These two were considered to represent summation effect of vascularity and permeability and vascularity alone, respectively, and combination of these two images may contribute to novel understanding of disease processes. However, because adequate theoretical model was not available to calculate and evaluate these two indices quantitatively, we carried out qualitative evaluation this time.We examined several intrapelvic diseases including 24 uterine myomas, 5 cervical carcinomas, 4 endometrial carcinomas, 4 ovarian carcinomas, and so on. Patterns of dynamic curves of R1 and R2* images were subclassified into 6 categories (I: plateau, II: peak, III: peak ＆ plateau, IV: gradual increase, V: flat, VI: unclassified). Normal uterine body, vagino-urethral complex, myomas showed categories I and V on Rl and R2* images, respectively. Normal bone marrow showed category I both on R1 and R2* images. Adenomyosis of the uterus, some of the cervical cancers showed categories II or III on R2* images.Meticulous analysis of R1 and R2* images may reveal neovascularity and permeability change in various disease processes. Further investigation is needed to clarify the usefulness of R1 and R2* images in larger population and also to develop soft ware which enables quantitative analysis of these two indices. Less