Improved accuracy and precision of fat-suppressed isotropic 3D T2 mapping MRI of the knee with dictionary fitting and patch-based denoising

• Published in: European radiology experimental Vol. 7; no. 1; p. 25
• Main Authors: Kuhn, Simon, Bustin, Aurélien, Lamri-Senouci, Aicha, Rumac, Simone, Ledoux, Jean-Baptiste, Colotti, Roberto, Bastiaansen, Jessica A. M., Yerly, Jérôme, Favre, Julien, Omoumi, Patrick, van Heeswijk, Ruud B.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 22.05.2023; Springer Nature B.V; SpringerOpen
• Subjects: Accuracy; Cartilage; Diagnostic Radiology; Dictionaries; Healthy Volunteers; Humans; Imaging; Imaging, Three-Dimensional - methods; Internal Medicine; Interventional Radiology; Knee; Knee joint; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Medicine; Medicine & Public Health; Neuroradiology; Original; Original Article; Phantoms, Imaging; Radiology; Ultrasound; Cartilage; Knee joint; Magnetic resonance imaging; Phantoms (imaging)
• DOI: 10.1186/s41747-023-00339-8
• ISSN: 2509-9280

Purpose To develop an isotropic three-dimensional (3D) T2 mapping technique for the quantitative assessment of the composition of knee cartilage with high accuracy and precision. Methods A T2-prepared water-selective isotropic 3D gradient-echo pulse sequence was used to generate four images at 3 T. These were used for three T2 map reconstructions: standard images with an analytical T2 fit (AnT2Fit); standard images with a dictionary-based T2 fit (DictT2Fit); and patch-based-denoised images with a dictionary-based T2 fit (DenDictT2Fit). The accuracy of the three techniques was first optimized in a phantom study against spin-echo imaging, after which knee cartilage T2 values and coefficients of variation (CoV) were assessed in ten subjects in order to establish accuracy and precision in vivo . Data given as mean ± standard deviation. Results After optimization in the phantom, whole-knee cartilage T2 values of the healthy volunteers were 26.6 ± 1.6 ms (AnT2Fit), 42.8 ± 1.8 ms (DictT2Fit, p  < 0.001 versus AnT2Fit), and 40.4 ± 1.7 ms (DenDictT2Fit, p  = 0.009 versus DictT2Fit). The whole-knee T2 CoV reduced from 51.5% ± 5.6% to 30.5 ± 2.4 and finally to 13.1 ± 1.3%, respectively ( p  < 0.001 between all). The DictT2Fit improved the data reconstruction time: 48.7 ± 11.3 min (AnT2Fit) versus 7.3 ± 0.7 min (DictT2Fit, p  < 0.001). Very small focal lesions were observed in maps generated with DenDictT2Fit. Conclusions Improved accuracy and precision for isotropic 3D T2 mapping of knee cartilage were demonstrated by using patch-based image denoising and dictionary-based reconstruction. Key points • Dictionary T2 fitting improves the accuracy of three-dimensional (3D) knee T2 mapping. • Patch-based denoising results in high precision in 3D knee T2 mapping. • Isotropic 3D knee T2 mapping enables the visualization of small anatomical details.