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Purpose@#This study aimed to assess the feasibility of ultrashort echo time (UTE)-T2* mapping in comparison with T2 mapping for quantitative evaluation of meniscal degeneration. @*Materials and Methods@#This study included 208 menisci of 99 patients (59 women and 40 men, median age 52 years old [16–80 years]) who underwent knee MRI with both standard T2 mapping and UTE-T2* mapping sequences. A radiologist reviewed the images and graded meniscal degeneration according to the morphologic criteria on T2-weighted and proton density-weighted sequences. Manually drawn regions of interest were placed along the outline and hyperintensity subregion within the meniscus, and in the same location on midsagittal images of each T2 and UTE-T2* sequence. Meniscal T2 and T2* values (T2m and T2*m) as well as T2 and T2* values of hyperintensity subregions (T2h, T2*h) were calculated. @*Results@#There was a strong correlation between T2m, T2*m, T2h, and T2*h, and morphological grades (correlation coefficient 0.793–0.943, 95% CI). On morphologic analysis, 50, 52, 50, and 56 menisci were graded as 0, 1, 2, and 3, respectively. T2m, T2*m, T2h, and T2*h were found to be significantly different in all the grades and tended to be higher in the more degraded meniscus (p < 0.001 for both). Mean T2m was 10.78 ± 2.91 ms, 15.81 ± 2.99 ms, 20.26 ± 3.19 ms, and 30.80 ± 7.38 ms and mean T2*m was 7.10 ± 1.12 ms, 9.64 ± 1.27 ms, 12.01 ± 1.58 ms, and 18.98 ± 4.67 ms for grades 0, 1, 2, and 3, respectively. Mean T2h was 20.05 ± 3.67 ms, 24.39 ± 4.73 ms, and 38.92 ± 9.49 ms and mean T2*h was 10.94 ± 1.65 ms, 13.67 ± 2.41 ms, and 22.36 ± 5.20 ms for grades 1, 2, and 3, respectively. @*Conclusion@#UTE-T2* mapping was feasible for quantitative evaluation of meniscal degeneration in patients. With a few improvements UTE-T2* mapping is a potential substitute for the standard T2 mapping, with improved efficacy.
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On MRI, abnormal signals of the intervertebral disc, destruction of the upper and lower vertebral body endplate around the disc, and bone marrow edema around the endplate are considered typical findings of infectious spondylitis. These findings can also appear in various non-infectious spinal diseases, such as degenerative changes, acute Schmorl’s node, spondyloarthropathy, synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO), chronic recurrent multifocal osteomyelitis, and calcium pyrophosphate dihydrate crystal deposition disease. The imaging findings of infectious spondylitis that can be differentiated from these non-infectious spinal diseases on MRI are high signal intensity and abscess of the disc space, an abscess in the paraspinal soft tissue, and the loss of the linear low signal intensity on T1-weighted images of the bony endplate. However, these differentiation points do not always apply since there are many similarities in the imaging findings of infectious and non-infectious diseases. Therefore, for an accurate diagnosis, it is important to know the imaging characteristics related to the pathophysiology of not only infectious spondylitis but also non-infectious spinal diseases, which requires differentiation from infection.
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Ultrasonography (US) is a very powerful diagnostic modality for the musculoskeletal system due to the ability to perform real-time dynamic high-resolution examinations with the Doppler technique. In addition to acquiring morphologic data, we can now obtain biomechanical information by quantifying the elasticity of the musculoskeletal structures with US elastography. The earlier diagnosis of degeneration and the ability to perform follow-up evaluations of healing and the effects of treatment are possible. US elastography enables a transition from US-based inspection to US-based palpation in order to diagnose the characteristics of tissue. Shear wave elastography is considered the most suitable type of US elastography for the musculoskeletal system. It is widely used for tendons, ligaments, and muscles. It is important to understand practice guidelines in order to enhance reproducibility. Incorporating viscoelasticity and overcoming inconsistencies among manufacturers are future tasks for improving the capabilities of US elastography.