Koons Emily K, Gong Hao, Missert Andrew, Chang Shaojie, Winfree Tim, Zhou Zhongxing, McCollough Cynthia H, Leng Shuai
Department of Radiology, Mayo Clinic, Rochester, MN, USA 55905.
Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, USA 55905.
Proc SPIE Int Soc Opt Eng. 2024 Feb;12925. doi: 10.1117/12.3006463. Epub 2024 Apr 1.
Coronary computed tomography angiography (cCTA) is a widely used non-invasive diagnostic exam for patients with coronary artery disease (CAD). However, most clinical CT scanners are limited in spatial resolution from use of energy-integrating detectors (EIDs). Radiological evaluation of CAD is challenging, as coronary arteries are small (3-4 mm diameter) and calcifications within them are highly attenuating, leading to blooming artifacts. As such, this is a task well suited for high spatial resolution. Recently, photon-counting-detector (PCD) CT became commercially available, allowing for ultra-high resolution (UHR) data acquisition. However, PCD-CTs are costly, restricting widespread accessibility. To address this problem, we propose a super resolution convolutional neural network (CNN): ILUMENATE (mproved visualization through rtificial super-resoluion imags), creating a high resolution (HR) image simulating UHR PCD-CT. The network was trained and validated using patches extracted from 8 patients with a modified U-Net architecture. Training input and labels consisted of UHR PCD-CT images reconstructed with a smooth kernel degrading resolution (LR input) and sharp kernel (HR label). The network learned the resolution difference and was tested on 5 unseen LR patients. We evaluated network performance quantitatively and qualitatively through visual inspection, line profiles to assess spatial resolution improvements, ROIs for CT number stability and noise assessment, structural similarity index (SSIM), and percent diameter luminal stenosis. Overall, ILUMENATE improved images quantitatively and qualitatively, creating sharper edges more closely resembling reconstructed HR reference images, maintained stable CT numbers with less than 4% difference, reduced noise by 28%, maintained structural similarity (average SSIM = 0.70), and reduced percent diameter stenosis with respect to input images. ILUMENATE demonstrates potential impact for CAD patient management, improving the quality of LR CT images bringing them closer to UHR PCD-CT images.
冠状动脉计算机断层血管造影(cCTA)是一种广泛应用于冠状动脉疾病(CAD)患者的非侵入性诊断检查。然而,大多数临床CT扫描仪由于使用能量积分探测器(EID),其空间分辨率有限。CAD的放射学评估具有挑战性,因为冠状动脉细小(直径3 - 4毫米),其中的钙化具有很高的衰减性,会导致光晕伪影。因此,这是一项非常适合高空间分辨率的任务。最近,光子计数探测器(PCD)CT已商业化,可实现超高分辨率(UHR)数据采集。然而,PCD - CT成本高昂,限制了其广泛普及。为了解决这个问题,我们提出了一种超分辨率卷积神经网络(CNN):ILUMENATE(通过人工超分辨率成像改善可视化),用于创建模拟UHR PCD - CT的高分辨率(HR)图像。该网络使用从8名患者中提取的补丁,采用改进的U - Net架构进行训练和验证。训练输入和标签分别由使用平滑内核降低分辨率重建的UHR PCD - CT图像(低分辨率输入)和锐化内核(高分辨率标签)组成。该网络学习了分辨率差异,并在5名未见过的低分辨率患者身上进行了测试。我们通过视觉检查、用于评估空间分辨率改善的线轮廓、用于CT值稳定性和噪声评估的感兴趣区域、结构相似性指数(SSIM)以及管腔直径狭窄百分比,对网络性能进行了定量和定性评估。总体而言,ILUMENATE在定量和定性方面都改善了图像,创建了更锐利的边缘,更接近重建的高分辨率参考图像,保持了稳定的CT值,差异小于4%,将噪声降低了28%,保持了结构相似性(平均SSIM = 0.70),并相对于输入图像降低了管腔直径狭窄百分比。ILUMENATE展示了对CAD患者管理的潜在影响,提高了低分辨率CT图像的质量,使其更接近UHR PCD - CT图像。