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Purpose: To develop methods for evaluating 3D patellofemoral and tibiofemoral alignment in vertical open-bore magnetic resonance (MR) scanners, with participants upright and fully weight-bearing; and to evaluate the repeatability of these methods in individuals with patellofemoral osteoarthritis (OA) and in asymptomatic knees.Materials and Methods: Our methods extend previously validated, reliable methods for evaluating alignment into an upright MR environment. In 10 participants with early patellofemoral OA and 10 with asymptomatic knees, we acquired sagittal T1 -weighted turbo spin echo images in a 3T scanner to create accurate participant-specific 3D anatomical surface models. In a vertical open-bore 0.5T MR scanner, we obtained lower-resolution sagittal gradient echo images to capture bony position and orientation data. Participants were scanned in a position of squatting with the knees flexed 30°, three separate times to evaluate repeatability. Bone segmentation was performed manually, surface models were registered to data from the 0.5T scanner, and 3D patellofemoral and tibiofemoral alignment was calculated in all six degrees of freedom (three rotations and three translations).Results: Intraclass correlation coefficients (ICCs) were ≥0.94, with the exception of patellar spin (0.79). Standard errors of measure (SEM) were <2° rotation and <0.9 mm translation. Repeatability remained adequate when stratified by group, with the exception of patellar spin (ICC 0.57 for asymptomatic knees vs. 0.91 for OA knees).Conclusion: We demonstrate methods for evaluating 3D alignment in upright fully weight-bearing participant positions in a vertical open-bore MR scanner. With the exception of patellar spin, repeatability was good to excellent.Level Of Evidence: 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:841-847. [ABSTRACT FROM AUTHOR]

Patellofemoral (PF) osteoarthritis (OA) is a prevalent and clinically important knee OA subgroup. Malalignment may be an important risk factor for PF OA. However, little is known about alignment in PF OA, particularly in an upright, weightbearing environment. Using a vertically‐oriented open‐bore MR scanner, we evaluated 3D knee alignment in 15 PF OA cases and 15 individually matched asymptomatic controls. We imaged one knee per participant while they stood two‐legged at four flexion angles (0°, 15°, 30°, 45°), and also while they stood one‐legged at 30° knee flexion. We calculated 3D patellofemoral and tibiofemoral alignment. Using mixed effects models, four of the five patellofemoral measures differed by group. For key measures, PF OA patellae were 6.6° [95%CI 5.0, 8.2] more laterally tilted, 2.4 mm [1.3, 3.5] more laterally translated, and at least 3.7 mm [0.2, 7.2] more proximally translated compared to controls (more with knees flexed). Alignment did not differ between two‐legged stance and one‐legged stance in either group. Statement of Clinical Significance: Our study demonstrated significant and clinically relevant differences in alignment between PF OA cases and controls in upright standing and squatting positions. Our findings were similar to those in previous studies of PF OA using traditional MR scanners in supine positions, supporting the clinical usefulness of existing methods aimed at identifying individuals who may benefit from interventions designed to correct malalignment. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. 9999:1–9, 2019. [ABSTRACT FROM AUTHOR]

Purpose: To visualize healthy and abnormal articular cartilage, we investigated the potential of using the 3D multi-echo gradient echo (GRE) signal's magnitude and frequency and maps of T2* relaxation.Materials and Methods: After optimizing imaging parameters in five healthy volunteers, 3D multi-echo GRE magnetic resonance (MR) images were acquired at 3T in four patients with chondral damage prior to their arthroscopic surgery. Average magnitude and frequency information was extracted from the GRE images, and T2* maps were generated. Cartilage abnormalities were confirmed after arthroscopy and were graded using the Outerbridge classification scheme. Regions of interest were identified on average magnitude GRE images and compared to arthroscopy.Results: All four patients presented with regions of Outerbridge Grade I and II cartilage damage on arthroscopy. One patient had Grade III changes. Grade I, II, and III changes were detectable on average magnitude and T2* maps, while Grade II and higher changes were also observable on MR frequency maps. For average magnitude images of healthy volunteers, the signal-to-noise ratio of the magnitude image averaged over three echoes was 4.26 ± 0.32, 12.26 ± 1.09, 14.31 ± 1.93, and 13.36 ± 1.13 in bone, femoral, tibial, and patellar cartilage, respectively.Conclusion: This proof-of-principle study demonstrates the feasibility of using different imaging contrasts from the 3D multi-echo GRE scan to visualize abnormalities of the articular cartilage. © 2016 International Society for Magnetic Resonance in Medicine Level of Evidence: 1 J. MAGN. RESON. IMAGING 2017;45:1502-1513. [ABSTRACT FROM AUTHOR]

MR-based methods provide low risk, noninvasive assessment of joint kinematics; however, these methods often use static positions or require many identical cycles of movement. The study objective was to compare the 3D kinematic results approximated from a series of sequential static poses of the knee with the 3D kinematic results obtained from continuous dynamic movement of the knee. To accomplish this objective, we compared kinematic data from a validated static MR method to a fast static MR method, and compared kinematic data from both static methods to a newly developed dynamic MR method. Ten normal volunteers were imaged using the three kinematic methods (dynamic, static standard, and static fast). Results showed that the two sets of static results were in agreement, indicating that the sequences (standard and fast) may be used interchangeably. Dynamic kinematic results were significantly different from both static results in eight of 11 kinematic parameters: patellar flexion, patellar tilt, patellar proximal translation, patellar lateral translation, patellar anterior translation, tibial abduction, tibial internal rotation, and tibial anterior translation. Three-dimensional MR kinematics measured from dynamic knee motion are often different from those measured in a static knee at several positions, indicating that dynamic-based kinematics provides information that is not obtainable from static scans. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]