Smekens Céline, Beirinckx Quinten, Bosmans Frederik, Vanhevel Floris, Snoeckx Annemiek, Sijbers Jan, Jeurissen Ben, Janssens Thomas, Van Dyck Pieter
From the imec-Vision Lab, Department of Physics, University of Antwerp, Antwerp, Belgium (C.S., Q.B., J.S., B.J.); Siemens Healthcare NV/SA, Groot-Bijgaarden, Belgium (C.S., T.J.); Department of Radiology, Antwerp University Hospital, Antwerp, Belgium (F.B., F.V., A.S., P.V.D.); and MIRA, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium (A.S., P.V.D.).
Invest Radiol. 2025 Mar 1;60(3):220-233. doi: 10.1097/RLI.0000000000001118. Epub 2024 Aug 28.
The aim of this study was to evaluate the use of a multicontrast deep learning (DL)-reconstructed 4-fold accelerated 2-dimensional (2D) turbo spin echo (TSE) protocol and the feasibility of 3-dimensional (3D) superresolution reconstruction (SRR) of DL-enhanced 6-fold accelerated 2D Dixon TSE magnetic resonance imaging (MRI) for comprehensive knee joint assessment, by comparing image quality and diagnostic performance with a conventional 2-fold accelerated 2D TSE knee MRI protocol.
This prospective, ethics-approved study included 19 symptomatic adult subjects who underwent knee MRI on a clinical 3 T scanner. Every subject was scanned with 3 DL-enhanced acquisition protocols in a single session: a clinical standard 2-fold in-plane parallel imaging (PI) accelerated 2D TSE-based protocol (5 sequences, 11 minutes 23 seconds) that served as a reference, a DL-reconstructed 4-fold accelerated 2D TSE protocol combining 2-fold PI and 2-fold simultaneous multislice acceleration (5 sequences, 6 minutes 24 seconds), and a 3D SRR protocol based on DL-enhanced 6-fold accelerated (ie, 3-fold PI and 2-fold simultaneous multislice) 2D Dixon TSE MRI (6 anisotropic 2D Dixon TSE acquisitions rotated around the phase-encoding axis, 6 minutes 24 seconds). This resulted in a total of 228 knee MRI scans comprising 21,204 images. Three readers evaluated all pseudonymized and randomized images in terms of image quality using a 5-point Likert scale. Two of the readers (musculoskeletal radiologists) additionally evaluated anatomical visibility and diagnostic confidence to assess normal and pathological knee structures with a 5-point Likert scale. They recorded the presence and location of internal knee derangements, including cartilage defects, meniscal tears, tears of ligaments, tendons and muscles, and bone injuries. The statistical analysis included nonparametric Friedman tests, and interreader and intrareader agreement assessment using the weighted Fleiss-Cohen kappa (κ) statistic. P values of less than 0.05 were considered statistically significant.
The evaluated DL-enhanced 4-fold accelerated 2D TSE protocol provided very similar image quality and anatomical visibility to the standard 2D TSE protocol, whereas the 3D SRR Dixon TSE protocol scored less in terms of overall image quality due to reduced edge sharpness and the presence of artifacts ( P < 0.001). Subjective signal-to-noise ratio, contrast resolution, fluid brightness, and fat suppression were good to excellent for all protocols. For 1 reader, the Dixon method of the 3D SRR protocol provided significantly better fat suppression than the spectral fat saturation applied in the standard 2D TSE protocol ( P < 0.05). The visualization of knee structures with 3D SRR Dixon TSE was very similar to the standard protocol, except for cartilage, tendons, and bone, which were affected by the presence of reconstruction and aliasing artifacts ( P < 0.001). The diagnostic confidence of both readers was high for all protocols and all knee structures, except for cartilage and tendons. The standard 2D TSE protocol showed a significantly higher diagnostic confidence for assessing tendons than 3D SRR Dixon TSE MRI ( P < 0.01). The interreader and intrareader agreement for the assessment of internal knee derangements using any of the 3 protocols was substantial to almost perfect (κ = 0.67-1.00). For cartilage, the interreader agreement was substantial for DL-enhanced accelerated 2D TSE (κ = 0.79) and almost perfect for standard 2D TSE (κ = 0.98) and 3D SRR Dixon TSE (κ = 0.87). For menisci, the interreader agreement was substantial for 3D SRR Dixon TSE (κ = 0.70-0.80) and substantial to almost perfect for standard 2D TSE (κ = 0.80-0.99) and DL-enhanced 2D TSE (κ = 0.87-1.00). Moreover, the total acquisition time was reduced by 44% when using the DL-enhanced accelerated 2D TSE or 3D SRR Dixon TSE protocol instead of the conventional 2D TSE protocol.
The presented DL-enhanced 4-fold accelerated 2D TSE protocol provides image quality and diagnostic performance similar to the standard 2D protocol. Moreover, the 3D SRR of DL-enhanced 6-fold accelerated 2D Dixon TSE MRI is feasible for multicontrast 3D knee MRI as its diagnostic performance is comparable to standard 2-fold accelerated 2D knee MRI. However, reconstruction and aliasing artifacts need to be further addressed to guarantee a more reliable visualization and assessment of cartilage, tendons, and bone. Both the 2D and 3D SRR DL-enhanced protocols enable a 44% faster examination compared with conventional 2-fold accelerated routine 2D TSE knee MRI and thus open new paths for more efficient clinical 2D and 3D knee MRI.
本研究旨在通过将多对比度深度学习（DL）重建的4倍加速二维（2D）快速自旋回波（TSE）协议以及DL增强的6倍加速二维狄克逊TSE磁共振成像（MRI）的三维（3D）超分辨率重建（SRR）的可行性与传统的2倍加速二维TSE膝关节MRI协议进行图像质量和诊断性能比较，以用于膝关节综合评估。
这项前瞻性、经伦理批准的研究纳入了19名有症状的成年受试者，他们在临床3T扫描仪上接受了膝关节MRI检查。每位受试者在一次检查中使用3种DL增强采集协议进行扫描：一种临床标准的2倍平面并行成像（PI）加速基于2D TSE的协议（5个序列，11分23秒）作为参考，一种结合2倍PI和2倍同时多层加速的DL重建4倍加速2D TSE协议（5个序列，6分24秒），以及一种基于DL增强6倍加速（即3倍PI和2倍同时多层）二维狄克逊TSE MRI的3D SRR协议（6个各向异性二维狄克逊TSE采集围绕相位编码轴旋转，6分24秒）。这总共产生了228次膝关节MRI扫描，包括21204幅图像。三位阅片者使用5分李克特量表对所有匿名和随机化的图像进行图像质量评估。其中两位阅片者（肌肉骨骼放射科医生）还使用5分李克特量表评估解剖结构的可视性和诊断信心，以评估正常和病理性膝关节结构。他们记录了膝关节内部紊乱的存在和位置，包括软骨缺损、半月板撕裂、韧带、肌腱和肌肉撕裂以及骨损伤。统计分析包括非参数弗里德曼检验，以及使用加权弗莱iss - 科恩kappa（κ）统计量进行阅片者间和阅片者内一致性评估。P值小于0.05被认为具有统计学意义。
评估的DL增强4倍加速2D TSE协议提供了与标准2D TSE协议非常相似的图像质量和解剖结构可视性，而3D SRR狄克逊TSE协议由于边缘清晰度降低和伪影的存在，在整体图像质量方面得分较低（P < 0.001）。所有协议的主观信噪比、对比分辨率、液体亮度和脂肪抑制均为良好至优秀。对于一位阅片者，3D SRR协议的狄克逊方法提供的脂肪抑制明显优于标准2D TSE协议中应用的频谱脂肪饱和（P < 0.05）。3D SRR狄克逊TSE对膝关节结构的可视化与标准协议非常相似，除了软骨、肌腱和骨骼，它们受到重建和混叠伪影的影响（P < 0.001）。两位阅片者对所有协议和所有膝关节结构的诊断信心都很高，除了软骨和肌腱。标准2D TSE协议在评估肌腱方面的诊断信心明显高于3D SRR狄克逊TSE MRI（P < 0.01）。使用这3种协议中的任何一种评估膝关节内部紊乱时，阅片者间和阅片者内的一致性为实质性至几乎完美（κ = 0.67 - 1.00）。对于软骨，DL增强加速2D TSE的阅片者间一致性为实质性（κ = 0.79），标准2D TSE（κ = 0.98）和3D SRR狄克逊TSE（κ = 0.87）为几乎完美。对于半月板，3D SRR狄克逊TSE的阅片者间一致性为实质性（κ = 0.70 - 0.80），标准2D TSE（κ = 0.80 - 0.99）和DL增强2D TSE（κ = 0.87 - 1.00）为实质性至几乎完美。此外，与传统2D TSE协议相比，使用DL增强加速2D TSE或3D SRR狄克逊TSE协议时，总采集时间减少了44%。
所呈现的DL增强4倍加速2D TSE协议提供了与标准2D协议相似的图像质量和诊断性能。此外，DL增强6倍加速二维狄克逊TSE MRI的3D SRR对于多对比度3D膝关节MRI是可行的，因为其诊断性能与标准2倍加速二维膝关节MRI相当。然而，需要进一步解决重建和混叠伪影问题，以确保对软骨、肌腱和骨骼进行更可靠的可视化和评估。与传统的2倍加速常规二维TSE膝关节MRI相比，二维和3D SRR DL增强协议都能使检查速度加快44%，从而为更高效的临床二维和3D膝关节MRI开辟了新途径。
