Motion Correction for MR Cystography by an Image Processing Approach

Abstract

Magnetic resonance (MR) cystography or MR-based virtual cystoscopy is a promising new technology to evaluate the entire bladder in a fully non-invasive manner. It requires the anatomical bladder images be acquired at high spatial resolution and with adequate signal-to-noise ratio (SNR). This often leads to a long-time scan (> 5 minutes) and results in image artifacts due to involuntary bladder motion and deformation. In this paper, we investigated an image-processing approach to mitigate the problem of motion and deformation. Instead of a traditional single long-time scan, six repeated short-time scans (each of approximately 1 minute) were acquired for the purpose of shifting bladder motion from intra-scan into inter-scans. Then the inter-scan motions were addressed by registering the short-time scans to a selected reference and finally forming a single average motion-corrected image. To evaluate the presented approach, three types of images were generated: (1) the motion-corrected image by registration and average of the short-time scans; (2) the directly-averaged image of the short-time scans (without motion correction); and (3) the single image of the corresponding long-time scan. Six experts were asked to blindly score these images in terms of two important aspects: (i) the definition of the bladder wall and (ii) the overall expression on the image quality. Statistical analysis on the scores suggested that the best result in both the aspects is achieved by the presented motion-corrected average. Furthermore the superiority of the motion-corrected average over the other two is statistically significant by the measure of a linear mixed-effect model with p-values<0.05. Our findings may facilitate the detection of bladder abnormality in MR cystography by mitigating the motion challenge. The effectiveness of this approach depends on the noise level of acquired short-time scans and the robustness of image registration and future effort on these two aspects is needed.

α-Information-Based Registration of Dynamic Scans for Magnetic Resonance Cystography

“…This observation is consistent with our previous studies reported in [13], [14]. Furthermore, with respect to comparing different methods for dynamic scans registration, the presented α –registration approach outperformed the well–known mutual information approach in terms of RMSE/CC for phantom studies and in terms of SNR of the bladder wall for patient studies.…”

“…Our previous work has shown that retrospective motion correction (RMC) is a promising image processing approach for MR imaging of the moving, expanding, and deforming bladder wall [13], [14]. In this study, we further investigate the effect of selecting an effective image registration method for the RMC in bladder MR images.…”

Recent advances in imaging and understanding interstitial cystitis

“…However, the information in 2D image slices is non-continuous owing to slice gaps. Hence, improvements in bladder wall imaging call for enhancement of contrast and SNR and reduced susceptibility to artifacts 79 during image acquisition and 3D reconstruction.…”

The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System

“…The protection strategy of VSC-HVDC system has been investigated in Refs. [ 21 – 22 ]. Yuan et al [ 23 ] studied the unbalanced three-phase control strategy of VSC-HVDC system.…”