Bumwoo Park

Publications (3)11.12 Total impact

• Source

  Available from: Namkug Kim

  Article: Reproducibility of measurement of apparent diffusion coefficients of malignant hepatic tumors: Effect of DWI techniques and calculation methods.

  So Yeon Kim, Seung Soo Lee, Bumwoo Park, Namkug Kim, Jeong Kon Kim, Seong Ho Park, Jae Ho Byun, Ki Jun Song, Ja-Heung Koo, Eun Kyung Choi, Moon-Gyu Lee
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  ABSTRACT: To evaluate the effect of diffusion-weighted imaging (DWI) methods, apparent diffusion coefficient (ADC) calculation methods, and selection of b-values on the ADCs and the measurement reproducibility of malignant hepatic tumors. Nineteen patients with pathologically confirmed malignant hepatic tumors underwent breath-hold DWI (b-values = 0, 50, 500 s/mm(2) ) and respiratory-triggered DWI (0, 50, 300, 500, 1000 s/mm(2) ) twice on a 1.5 T magnetic resonance imaging (MRI) scanner. ADCs were calculated using a two b-value and/or a multiple b-value method. The reproducibility of the ADC measurements was evaluated from the intraclass correlation coefficients (ICCs) and the 95% Bland-Altman limit-of-agreement (LOA). The ADCs were different according to the DWI methods (P = 0.040-0.282), ADC calculation methods (P = 0.003-0.825), and the choice of b-values (P < 0.001). The ADC tended to be more reproducible with use of breath-hold DWI (ICC: 0.898-0.933; LOA, 18.8%-24.0%) than respiratory-triggered DWI (ICC: 0.684-0.928; LOA, 15.0%-31.9%) (P = 0.008-0.122). For respiratory-triggered DWI, the multiple b-value method using five b-values had better reproducibility than the two b-value method for measurement of ADC (P = 0.009-0.221). The DWI method, ADC calculation method, and selection of b-values potentially influence the ADCs and the reproducibility of malignant hepatic tumors. ADCs calculated from breath-hold DWI are more reproducible than from respiratory-triggered DWI. A multiple b-value method may improve the reproducibility of respiratory-triggered DWI. J. Magn. Reson. Imaging 2012;36:1131-1138. © 2012 Wiley Periodicals, Inc.
  Journal of Magnetic Resonance Imaging 07/2012; 36(5):1131-8. · 2.70 Impact Factor
• Article: Malignant hepatic tumors: short-term reproducibility of apparent diffusion coefficients with breath-hold and respiratory-triggered diffusion-weighted MR imaging.

  So Yeon Kim, Seung Soo Lee, Jae Ho Byun, Seong Ho Park, Jeong Kon Kim, Bumwoo Park, Namkug Kim, Moon-Gyu Lee
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  ABSTRACT: To prospectively evaluate the reproducibility of apparent diffusion coefficient (ADC) measurement in malignant hepatic tumors and to examine the influence of imaging methods, lesion location, and lesion size on the reproducibility of ADC measurement. The institutional review board approved the study protocol, and informed consent was obtained. Forty-nine patients underwent both breath-hold and respiratory-triggered diffusion-weighted (DW) magnetic resonance imaging on a 1.5-T system twice. Two independent readers measured the ADC of the largest malignant hepatic tumor for each patient on each image sets. Mean ADCs were compared between repeated acquisitions and imaging techniques by using the paired t test. Reproducibility of the ADC measurement and interobsever agreement were determined by using 95% Bland-Altman limits of agreement and intraclass correlation coefficients (ICCs). The effects of the imaging technique, lesion location, and lesion size on the reproducibility of the ADC measurements were assessed by comparing ICCs by using the z test. There were no significant differences in the mean ADC between repeated acquisitions for breath-hold ([1.266-1.275] x 10(-3) mm(2)/sec vs [1.285-1.290] x 10(-3) mm(2)/sec; P = .572-.634) or respiratory-triggered ([1.487-1.502] x 10(-3) mm(2)/sec vs [1.421-1.441] x 10(-3) mm(2)/sec; P = .073-.091) DW MR imaging. The mean ADCs measured by using the respiratory-triggered method ([1.421-1.502] x 10(-3) mm(2)/sec) were significantly higher than those measured by using the breath-hold method ([1.266-1.290] x 10(-3) mm(2)/sec) (P < or = .001). The 95% limits of agreement between ADCs measured on repeated DW images were 28.7%-31.3% of the mean, and those between ADCs measured by two readers were 14.6%-22.5% of the mean. ADC measurement of malignant hepatic tumors tended to be more reproducible for right-lobe than for left-lobe lesions and for larger rather than smaller lesions. Changes in ADCs of less than approximately 30% fall into the range of measurement error. Imaging technique significantly affected ADCs of malignant hepatic tumors. Lesion location and size are potentially influential on the reproducibility of ADC measurement.
  Radiology 06/2010; 255(3):815-23. · 5.73 Impact Factor
• Article: Quantitative analysis of diffusion-weighted magnetic resonance imaging of the pancreas: usefulness in characterizing solid pancreatic masses.

  Seung Soo Lee, Jae Ho Byun, Beom Jin Park, Seong Ho Park, Namkug Kim, Bumwoo Park, Jeong Kon Kim, Moon-Gyu Lee
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  ABSTRACT: To evaluate whether measurement of apparent diffusion coefficient (ADC) and pure diffusion coefficient (D) can help to characterize solid pancreatic masses. Diffusion-weighted MR imaging was performed in both a patient group (n = 71; pancreatic cancer [n = 47], mass-forming pancreatitis [n = 13], solid pseudopapillary neoplasm [n = 6], and neuroendocrine tumor [n = 5]) and a normal control group (n = 11) by applying three b-factors of 0, 500, and 1000 sec/mm(2). ADC(500), ADC(1000), D (ADC using b = 500 and 1000 sec/mm(2)), and perfusion fraction (f, 1- exp [-500 sec/mm(2) x (ADC(500) - D)]) of normal pancreas, pancreatic cancer, and mass-forming pancreatitis were compared using the Kruskal-Wallis test. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance and optimal cutoff value of these parameters in differentiating pancreatic cancer from mass-forming pancreatitis. Normal pancreas had significantly higher mean ADC(500), ADC(1000), and f than either pancreatic cancer (P < 0.001, < 0.001, and 0.004, respectively) or mass-forming pancreatitis (P < 0.001, < 0.001, and 0.002, respectively). ADC(500), ADC(1000), and D of mass-forming pancreatitis were significantly lower than those of pancreatic cancer (P = 0.002, 0.004, and 0.014, respectively). Sensitivities and specificities in the diagnosis of pancreatic cancer were 72.3% and 76.9% for ADC(500), 87.2% and 69.2% for ADC(1000), 87.2% and 61.5% for D, and 42.6% and 92.3% for f, respectively. Measurement of ADC and D may be helpful in differentiating pancreatic cancers from mass-forming pancreatitis.
  Journal of Magnetic Resonance Imaging 11/2008; 28(4):928-36. · 2.70 Impact Factor