Ariyurek Cemre, Lu Lina, Sideris Georgios Antonios, Ferrer Valentina Valencia, Timms Liam, Vasylechko Serge Didenko, Afacan Onur, Kurugol Sila
Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.
Harvard Medical School, Boston, Massachusetts, USA.
NMR Biomed. 2025 Sep;38(9):e70117. doi: 10.1002/nbm.70117.
Diffusion-weighted imaging (DWI) during MR enterography helps identify bowel inflammation in Crohn's disease (CD). However, image quality is compromised by geometric distortions from B field variations and physiological motion, making it challenging for radiologists to correlate findings between DWI and structural images. Traditional correction methods using reversed polarity scans are ineffective due to motion between acquisitions, which limits accurate estimation of intravoxel incoherent motion (IVIM) parameters. We propose a dual-echo echo-planar imaging (EPI) method that retrospectively corrects both geometric distortions and motion in 3T bowel DWI by accounting for field changes during peristalsis and breathing. We added a 5- to 7-min dual-echo EPI DW sequence (eight b-values, six directions) to the clinical MR enterography protocol of 21 patients with suspected CD at 3T MRI. Distortion correction was applied based on dynamically estimated fields from dual-echo DWI, followed by intra-volume registration between odd-even slices and inter-volume registration for motion correction. Two experienced board-certified radiologists evaluated the severity of the disease using simplified magnetic resonance index of activity (MaRIA) scores. Based on their consensus scores, patients were categorized into three groups: no active disease (MaRIA score = 0), active disease (MaRIA score = 1-2), and severe disease (MaRIA score = 3-5). The proposed DWI correction pipeline improved DWI/T-weighted image Dice similarity from 0.73 to 0.89, enabling better correlation of findings between structural and DW-MR images and enhancing DWI's clinical value. Corrected IVIM parameters showed stronger correlations with MaRIA scores (D: ρ = -0.93; f: ρ = -0.94, p < 0.001) compared to uncorrected parameters (D: ρ = -0.68, p = 0.001; f: ρ = -0.35, p = 0.118). Diagnostic sensitivity increased from 0.44 to 0.89, while parameter uncertainty decreased from 35.58% to 19.31% for D and 63.48% to 40.40% for f (p < 0.001). These improvements strengthen quantitative IVIM imaging for CD assessment, potentially reducing reliance on contrast imaging while offering enhanced tissue perfusion and diffusion insights.
磁共振小肠造影期间的扩散加权成像（DWI）有助于识别克罗恩病（CD）中的肠道炎症。然而，图像质量会受到B场变化和生理运动引起的几何失真影响，这使得放射科医生难以将DWI与结构图像的结果进行关联。由于采集之间的运动，使用反向极性扫描的传统校正方法无效，这限制了体素内不相干运动（IVIM）参数的准确估计。我们提出了一种双回波平面回波成像（EPI）方法，通过考虑蠕动和呼吸过程中的场变化，对3T肠道DWI中的几何失真和运动进行回顾性校正。我们在21例疑似3T MRI的CD患者的临床磁共振小肠造影方案中添加了一个5至7分钟的双回波EPI DW序列（八个b值，六个方向）。基于双回波DWI动态估计的场进行失真校正，然后对奇偶切片进行体积内配准，并对运动进行体积间配准。两位经验丰富的获得委员会认证的放射科医生使用简化的磁共振活动指数（MaRIA）评分评估疾病的严重程度。根据他们的共识评分，患者被分为三组：无活动性疾病（MaRIA评分为0）、活动性疾病（MaRIA评分为1 - 2）和严重疾病（MaRIA评分为3 - 5）。所提出的DWI校正流程将DWI/T加权图像的骰子相似度从0.73提高到0.89，使结构图像和DW - MR图像之间的结果具有更好的相关性，并提高了DWI的临床价值。与未校正的参数相比，校正后的IVIM参数与MaRIA评分显示出更强的相关性（D：ρ = -0.93；f：ρ = -0.94，p < 0.001）（D：ρ = -0.68，p = 0.001；f：ρ = -0.35，p = 0.118）。诊断敏感性从0.44提高到0.89，而D参数不确定性从35.58%降至19.31%，f参数不确定性从63.48%降至40.40%（p < 0.001）。这些改进加强了用于CD评估的定量IVIM成像，可能减少对对比成像的依赖，同时提供增强的组织灌注和扩散见解。
