Abstract #1614
Comparison of mono-exponential, bi-exponential and stretched-exponential models derived parameters in detecting renal cell carcinomas
Wenhui Wang 1 , Degang Ding 2 , Dapeng Shi 3 , Yan Bai 3 , xiaoyue ma 4 , and Meiyun Wang 3
1
Radiology, Henan Provincial Peoples
Hospital, Zhengzhou, Henan, China,
2
Urology,
Henan Provincial Peoples Hospital, Zhengzhou, Henan,
China,
3
Henan
Provincial Peoples Hospital, Zhengzhou, Henan, China,
4
Radiology,
Zhengzhou University Peoples Hospital & Henan
Provincial Peoples Hospital, Zhengzhou, Henan, China
To evaluate the diagnostic accuracy of mono-exponential,
bi-exponential and stretched-exponential models
diffusion weighted imaging (DWI) in patients with renal
cell carcinoma (RCC). 24 patients with RCC underwent DWI
with fifteen b factors (0, 10,30, 50, 70, 100,150,200,
300,400,600, 800,1000,1500,2000 sec/mm2) on a 3.0T MR
scanner. The isotropic apparent diffusion coefficient
(ADC); the true diffusion coefficient (ADCslow),
pseudo-diffusion coefficient (ADCfast), and fraction of
perfusion (f) ; the water diffusion heterogeneity index
() and distributed diffusion coefficient (DDC) derived
from the mono-exponential, bi-exponential and
stretched-exponential models were calculated in the
solid area of tumors and in the corresponding regions of
contralateral normal renal parenchyma. Univariate
receiver operating characteristic (ROC) analysis was
implemented and areas under the curve (AUC) were
compared among all parameters using MedCalc (MedCalc
Sofware, Mariakerke, Belgium) to determine the largest
Yoden index and corresponding sensitivities and
specificities in the diagnosis of RCC. The mean ADC,
ADCslow and value was significantly lower in RCC than
in normal renal parenchyma (P < 0.001). ADCfast value
was significantly higher in RCC than in normal renal
parenchyma (P < 0.001). In the ROC analysis, the AUC for
was 0.977 and significantly larger than other
parameters with a sensitivity of 100% and a specificity
of 75.0%. There was a strong correlation between ADC and
ADCslow ( r=0.908, P0.001). DWI is a noninvasive MR
technique that is sensitive to water molecular diffusion
in biological tissue. However, ADC value calculated by a
mono-exponential model alone may not be able to
accurately reflect water molecular diffusion in vivo
because of the influence of the microcirculation of
blood in capillaries [1]. Some recent studies have
suggested that bi-exponential and stretched-exponential
DWI models might provide more accurate information about
the water diffusion[2-3] by separating water molecular
diffusion from microcirculation and describing the
heterogeneity of intravoxel diffusion rates and the
distributed diffusion effect. Comparing with parameters
derived from mono-exponential and bi-exponential models,
the derived from stretched-exponential model may
provide the most accurate information in the diagnosis
of RCC.
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