ACCELERATION: Sequentially-scanning DECT Imaging Using High Temporal Resolution Image Reconstruction And Temporal Extrapolation

TL;DR

The paper tackles temporal mismatch in sequential DECT caused by dynamic iodine contrast, which undermines accurate iodine quantification. It introduces ACCELERATION, a hardware-agnostic pipeline that combines time-resolved short-scan reconstructions at the first tube potential with temporal extrapolation to synthesize temporally consistent dual-energy images for iodine quantification. Reconstruction relies on an implicit neural representation $\mathcal{M}_{\theta}$ trained in two stages: an image-domain loss ${\theta}^{*}=\arg\min_{\theta} \frac{1}{N} \sum_{j=1}^{N} (\mathcal{M}_{\theta}(x_j)-v_j)^2$ and a subsequent sinogram-domain loss ${\theta}^{*}=\arg\min_{\theta} \frac{1}{M} \sum_{i=1}^{M} (\sum_{j=1}^{N} a_{ij} \mathcal{M}_{\theta}(x_j) - s_i)^2$ after forward projection. Temporal extrapolation then performs per-pixel linear least-squares across $T$ reconstructed frames to estimate the CT image at time $T_4$ for the first tube potential, with the second-tube-potential data processed by the same first-step, enabling robust material decomposition into water and iodine bases. Validation on numerical simulations inspired by clinical cerebral DECT demonstrates improved iodine quantification and more accurate material decomposition compared with conventional FBP-based approaches.

Abstract

Dual-energy computed tomography (DECT) has been widely used to obtain quantitative elemental composition of imaged subjects for personalized and precise medical diagnosis. Compared with existing high-end DECT leveraging advanced X-ray source and/or detector technologies, the use of the sequentially-scanning data acquisition scheme to implement DECT may make broader impact on clinical practice because this scheme requires no specialized hardware designs. However, since the concentration of iodinated contrast agent in the imaged subject varies over time, sequentially-scanned data sets acquired at two tube potentials are temporally inconsistent. As existing material decomposition approaches for DECT assume that the data sets acquired at two tube potentials are temporally consistent, the violation of this assumption results in inaccurate quantification accuracy of iodine concentration. In this work, we developed a technique to achieve sequentially-scanning DECT imaging using high temporal resolution image reconstruction and temporal extrapolation, ACCELERATION in short, to address the technical challenge induced by temporal inconsistency of sequentially-scanned data sets and improve iodine quantification accuracy in sequentially-scanning DECT. ACCELERATION has been validated and evaluated using numerical simulation data sets generated from clinical human subject exams. Results demonstrated the improvement of iodine quantification accuracy using ACCELERATION.

Figures (7)

• Figure 1: Temporal inconsistency in the sequentially-scanning DECT data acquisition.
• Figure 2: Reconstruction by solving Eq. (\ref{['eq1']})
• Figure 3: Reconstruction by solving Eq. (\ref{['eq2']})
• Figure 4: Short-scan image reconstruction module
• Figure 5: Global architecture of ACCELERATION. ①, ②, ③$~$represent the first, second and third steps respectively for the data set acquired at the low tube potential.