Tıp Fakültesi / Faculty of Medicine

Permanent URI for this collectionhttps://hdl.handle.net/11727/1403

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Author: search.filters.author.Koc, ZaferSubject: search.filters.subject.b-value

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    Diffusion-Weighted MRI and Optimal b-value For Characterization of Liver Lesions
    (2014) Kaya, Bilal; Koc, Zafer; https://orcid.org/0000-0002-8917-3375; https://orcid.org/0000-0003-0987-1980; 23982322; AAK-9366-2020; S-8384-2016
    Background: Diffusion-weighted imaging (DWI) is commonly used to distinguish between benign and malignant liver lesions. However, different b-values are recommended. Purpose: To determine the most suitable b-value in DWI for differentiation of benign and malignant liver lesions. Material and Methods: A total of 124 lesions in 89 consecutive patients (43 men, 46 women; age, mean +/- standard deviation, 58 +/- 14 years) with a pathological or radiological diagnosis of malignant or benign focal liver lesions after magnetic resonance imaging (MRI) were included in this study. Routine abdominal MRI and DWI were performed using seven b-values (0, 50, 200, 400, 600, 800, 1000 s/mm(2)). Lesions were analyzed for benignity/malignity using apparent diffusion coefficient (ADC) values with 10 b-value combinations and by measuring the lesion/normal parenchyma ADC ratio. Results: Mean ADC values were significantly different between malignant and benign lesions for all b-value combinations (P = 0.000). The best b-value combination was 0 and 800 (Az = 0.935). Using lower b-values such as 0 and 50 together with higher b-values >= 600 s/mm(2) was beneficial (Az = 0.928 and 0.927). Mean ADC values were approximately 13% (1-15%) higher in total when b = 0 and b = 50 s/mm(2) were included in multiple b-value combinations. Conclusion: In DWI, we recommend the use of b-values of 0 and 800 s/mm(2) as two b-values, or b = 0, 50, 600, 800, and 1000 s/mm(2) as multiple b-values for distinguishing between benign and malignant liver lesions. Mean ADC value is 13% higher in total by additional use of b = 0 and b = 50 s/mm(2) in multiple b-value combinations.
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    Utility of Diffusion-Weighted MRI to Detect Changes in Liver Diffusion in Benign and Malignant Distal Bile Duct Obstruction: The Influence of Choice of b-Values
    (2016) Karan, Belgin; Erbay, Gurcan; Koc, Zafer; Pourbagher, Aysin; Yildirim, Sedat; Agildere, Ahmet Muhtesem; 0000-0003-0987-1980; 0000-0002-5735-4315; 0000-0002-1706-8680; 0000-0003-4223-7017; 27592163; S-8384-2016; AAF-4610-2019; AAK-5370-2021; AAB-5802-2020
    Purpose: The study sought to evaluate the potential of diffusion-weighted magnetic resonance imaging to detect changes in liver diffusion in benign and malignant distal bile duct obstruction and to investigate the effect of the choice of b-values on apparent diffusion coefficient (ADC). Methods: Diffusion-weighted imaging was acquired with b-values of 200, 600, 800, and 1000 s/mm(2). ADC values were obtained in 4 segments of the liver. The mean ADC values of 16 patients with malignant distal bile duct obstruction, 14 patients with benign distal bile duct obstruction, and a control group of 16 healthy patients were compared. Results: Mean ADC values for 4 liver segments were lower in the malignant obstruction group than in the benign obstruction and control groups using b = 200 s/mm(2) (P < .05). Mean ADC values of the left lobe medial and lateral segments were lower in the malignant obstruction group than in the benign obstructive and control groups using b = 600 s/mm2 (P < .05). Mean ADC values of the right lobe posterior segment were lower in the malignant and benign obstruction groups than in the control group using b = 1000 s/mm(2) (P < .05). Using b = 800 s/mm(2), ADC values of all 4 liver segments in each group were not significantly different (P > .05). There were no correlations between the ADC values of liver segments and liver function tests. Conclusion: Measurement of ADC shows good potential for detecting changes in liver diffusion in patients with distal bile duct obstruction. Calculated ADC values were affected by the choice of b-values.