Browsing by Author "Akpek, Sergin"

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    Conspicuity of Peripheral Zone Prostate Cancer on Computed Diffusion-Weighted Imaging: Comparison of cDWI(1500), cDWI(2000), and cDWI(3000)
    (HINDAWI LTD, 2014-01-01) Vural, Metin; Ertas, Gokhan; Onay, Aslihan; Acar, Omer; Esen, Tarik; Saglican, Yesim; Zengingonul, Hale Pinar; Akpek, Sergin
    Introduction and Objective. Disadvantages associated with direct high b-value measurements may be avoided with use of computed diffusion-weighted imaging (cDWI). The purpose of this study is to assess the diagnostic performance of cDWI image sets calculated for high b-values of 1500, 2000, and 3000 s/mm(2). Materials and Methods. Twenty-eight patients who underwent multiparametric MRI of the prostate and radical prostatectomy consecutively were enrolled in this retrospective study. Using a software developed at our institute, cDWI 1500, cDWI 2000, and cDWI 3000 image sets were generated by fitting a monoexponential model. Index lesions on cDWI image sets were scored by two radiologists in consensus considering lesion conspicuity, suppression of background prostate tissue, distortion, image set preferability, and contrast ratio measurements were performed. Results. Lesion detection rates are the same for computed b-values of 2000 and 3000 s/ mm 2 and are better than b-values of 1500 s/ mm(2). Best lesion conspicuity and best background prostate tissue suppression are provided by cDWI(3000) image set. cDWI(2000) image set provides the best zonal anatomical delineation and less distortion and was chosen as the most preferred image set. Average contrast ratio measured on these image sets shows almost a linear relation with the b-values. Conclusion. cDWI 2000 image set with similar conspicuity and the same lesion detection rate, but better zonal anatomical delineation, and less distortion, was chosen as the preferable image set.
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    Evaluation of Peripheral Zone Prostate Cancer Aggressiveness Using the Ratio of Diffusion Tensor Imaging Measures
    (WILEY-HINDAWI, 2017-01-01) Onay, Aslihan; Ertas, Gokhan; Vural, Metin; Acar, Omer; Saglican, Yesim; Coskun, Bilgen; Akpek, Sergin
    Purpose. To evaluate the aggressiveness of peripheral zone prostate cancer by correlating the Gleason score (GS) with the ratio of the diffusion tensor imaging (DTI) measures. Materials and Methods. Forty-two peripheral zone prostate tumors were imaged using DTI. Regions of interest focusing on the center of tumor foci and noncancerous tissue were used to extract statistical measures of mean diffusivity (MD) and fractional anisotroy (FA). Measure ratio was calculated by dividing tumor measure by noncancerous tissue measure. Results. Strong correlations are observable between GS and MD measures while weak correlations are present between GS and FA measures. Minimum tumor MD (MDmin) and the ratio of minimum MD (rMD(min)) show the same highest correlation with GS (both rho = -0.73). Between GS <= 7 (3 + 4) and GS >= 7 (4 + 3), differences are significant for all MD measures but for some FA measures. MD measures perform better than FA measures in discriminating GS >= 7 (4 + 3). Conclusion. Ratios of MD measures can be used in evaluation of peripheral zone prostate cancer aggressiveness