Fifty-eighth annual meeting of the american association of physicists in medicine
SU-F-R-29: The Influence of Four Dimensional Diffusion-Weighted MRI (4D-DWI) On Feature Analysis of Time-Resolved Apparent Diffusion Coefficient (ADC) Measurement: Initial Evaluation
Diffusion-weighted imaging (DWI) has been shown to have superior tumor-to-tissue contrast for cancer detection compared to other MRI sequences and CT. This study aims at developing and evaluating the effects of the four dimensional DWI (4D-DWI) technique on the feature analysis of time-resolved Apparent Diffusion Coefficient (ADC) measurement.
Image acquisition was performed by repeatedly imaging a volume of interest using a multi-slice single-shot 2D-DWI sequence in the axial planes. Each 2D-DWI image was acquired sequentially in the x, y, and z-diffusion-directions (b=500s/mm2). Respiratory motion was simultaneously recorded using bellows. Retrospective sorting was conducted to reconstruct 4D-DWI. As a comparison, free breathing DWI (FB-DWI) was also reconstructed using the same dataset. Subsequently, ADC maps were measured for 4D-DWI and FB-DWI data. The technique was implemented on a digital human phantom (XCAT). It was programmed to simulate regular motion. Motion trajectories of tumor were extracted from 4D-DWI and compared with average input breathing curve. The mean amplitude difference(D) was calculated. To quantitatively analyze the effect of 4D-DWI on time-resolved ADC maps, feature analysis was conducted on tumor region for the time-resolved ADC maps and the free breathing ADC maps. 3D XCAT images were served as the reference. The following features were calculated: mean tumor ADC value, entropy, energy, kurtosis, skewness, homogeneity, sphericity, tumor surface area and tumor contrast.
4D-DWI of XCAT digital phantom demonstrated the respiratory motion clearly. The values of D were 1.9mm, 1.7mm and 2.0mm, respectively. The feature analysis shows that the texture of tumor demonstrated on time-resolved ADC maps was significantly closer to the reference than the free breathing ADC maps.
The influence of 4D-DWI technique on feature analysis of time-resolved ADC measurement was initially evaluated on a digital human phantom. Comparing to free breathing DWI, 4D-DWI can lead to more accurate measurement of ADC.