Acetabular coverage differs between standing and supine positions: model-based assessment of low-dose biplanar radiographs and comparison with CT.

OBJECTIVES: To evaluate the feasibility of 2D and 3D acetabular coverage assessments based on low-dose biplanar radiographs (BPR) in comparison with CT, and to demonstrate the influence of weight-bearing position (WBP) on anterior and posterior acetabular coverages. METHODS: Fifty patients (21 females, 29 males) underwent standing BPR and supine CT of the pelvis. Using dedicated software, BPR-based calculations of anterior and posterior 2D coverages and anterior, posterior, and global 3D coverages were performed in standardized anterior pelvic plane (APP) and WBP. CT-based anterior and posterior 2D coverages and global 3D coverage was calculated in APP and compared with BPR-based data. Statistics included intraclass correlation coefficients (ICC) and Bland-Altman plots. RESULTS: Mean anterior 2D coverage was 21.2% (standard deviation, ± 7.4%) for BPR and 23.8% (± 8.4%) for CT (p = 0.226). Mean posterior 2D coverage was 54.2% (± 9.8%) for BPR and 61.7% (± 9.7%) for CT (p = 0.001). Mean global 3D coverage was 46.5% (± 3.0%) for BPR and 45.6% (± 3.6%) for CT (p = 0.215). The inter-method reliability between CT and BPR and inter-reader reliability for BPR-based measurements were very good for all measurement (all ICC > 0.8). Based on BPR, mean anterior and posterior 3D coverages were 20.5% and 26.0% in WBP and APP, while 25 patients increased anterior and 24 patients increased posterior 3D coverage from APP to WBP with a relative change of coverage of up to 11.9% and 10.0%, respectively. CONCLUSIONS: 2D and 3D acetabular coverages can be calculated with very good reliability based on BPR. The impact of standing position on acetabular coverage can be quantified with BPR on an individual basis. KEY POINTS: • 2D and 3D acetabular coverages can be calculated with very good reliability based on biplanar radiographs in comparison with CT. • The impact of standing position on anterior and posterior acetabular coverages can be quantified with BPR on an individual basis.

Can quantitative sensory tests predict failed back surgery?: A prospective cohort study.

BACKGROUND: Failed back surgery syndrome (FBSS) is a pain condition refractory to therapy, and is characterised by persistent low back pain after spinal surgery. FBSS is associated with severe disability, low quality of life and high unemployment. We are currently unable to identify patients who are at risk of developing FBSS. Patients with chronic low back pain may display signs of central hypersensitivity as assessed by quantitative sensory tests (QST). This can contribute to the risk of developing persistent pain after surgery. OBJECTIVE: We tested the hypothesis that central hypersensitivity as assessed by QST predicts FBSS. DESIGN: Prospective cohort study. SETTING: Three tertiary care centres. PATIENTS: 141 patients scheduled for up to three segment spinal surgery for chronic low back pain (defined as at least 3 on a numerical rating scale on most days during the week and with a minimum duration of 3 months) due to degenerative changes. OUTCOMES: We defined FBSS as persistent pain, persistent disability or a composite outcome defined as either persistent pain or disability. The primary outcome was persistent pain 12 months after surgery. We applied 14 QST using electrical, pressure and temperature stimulation to predict FBSS and assessed the association of QST with FBSS in multivariable analyses adjusted for sociodemographic, psychological and clinical and surgery-related characteristics. RESULTS: None of the investigated 14 QST predicted FBSS, with 95% confidence intervals of crude and adjusted associations of all QST including one as a measure of no association. Results remained robust in all sensitivity and secondary analyses. CONCLUSION: The study indicates that assessment of altered central pain processing using current QST is unlikely to identify patients at risk of FBSS and is therefore unlikely to inform clinical decisions.

Postpartum Bone Marrow Edema at the Sacroiliac Joints May Mimic Sacroiliitis of Axial Spondyloarthritis on MRI.

OBJECTIVE: The objective of our study was to compare MRI findings in the sacroiliac joints of postpartum women (as a model of mechanical changes) and women with known axial spondyloarthritis (as an inflammatory model). SUBJECTS AND METHODS: For this prospective multicenter age-matched, case-control study, sacroiliac joint MRI examinations of 30 healthy women (mean age, 34.0 years) in the early postpartum period (mechanical group) and 30 age-matched women (mean age, 33.8 years) with known axial spondyloarthritis (retrospective inflammatory group) were compared. Blinded to clinical information, readers assessed MR images using the following scoring systems: Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index, Berlin method, Assessment of Spondyloarthritis International Society (ASAS) criteria, and SPARCC MRI structural score. Descriptive statistics as percentages of the different findings (i.e., bone marrow edema [BME], erosion, fatty bone marrow replacement, backfill, ankylosis) and scores between groups and between delivery modes were compared. RESULTS: In the postpartum group, 63.3% (19/30) of women showed BME around the sacroiliac joints compared with 86.7% (26/30) of women in the spondyloarthritis group (based on ASAS criteria). Erosions were uncommon in the postpartum group (10.0% [3/30] postpartum vs 56.7% [17/30] spondyloarthritis). Fatty bone marrow replacement, backfill, and ankylosis were not seen in the postpartum group. In subjects with positive MRI findings for sacroiliitis based on ASAS criteria, the SPARCC MRI index (mean ± SD, 13.6 ± 14.5 vs 13.0 ± 10.7; p = 0.818) and Berlin method (4.5 ± 3.0 and 5.5 ± 3.5, p = 0.378) were not different between the postpartum and spondyloarthritis groups. Scores were not different between birth modalities. CONCLUSION: Pregnancy-induced BME at the sacroiliac joints, as a result of prolonged mechanical stress, was present in 63.3% of women who underwent MRI during the early postpartum period and may mimic sacroiliitis of axial spondyloarthritis.

Subchondral bone microarchitecture analysis in the proximal tibia at 7-T MRI.

Background Bone remodels in response to mechanical loads and osteoporosis results from impaired ability of bone to remodel. Bone microarchitecture analysis provides information on bone quality beyond bone mineral density (BMD). Purpose To compare subchondral bone microarchitecture parameters in the medial and lateral tibia plateau in individuals with and without fragility fractures. Material and Methods Twelve female patients (mean age = 58 ± 15 years; six with and six without previous fragility fractures) were examined with dual-energy X-ray absorptiometry (DXA) and 7-T magnetic resonance imaging (MRI) of the proximal tibia. A transverse high-resolution three-dimensional fast low-angle shot sequence was acquired (0.234 × 0.234 × 1 mm). Digital topological analysis (DTA) was applied to the medial and lateral subchondral bone of the proximal tibia. The following DTA-based bone microarchitecture parameters were assessed: apparent bone volume; trabecular thickness; profile-edge-density (trabecular bone erosion parameter); profile-interior-density (intact trabecular rods parameter); plate-to-rod ratio; and erosion index. We compared femoral neck T-scores and bone microarchitecture parameters between patients with and without fragility fracture. Results There was no statistical significant difference in femoral neck T-scores between individuals with and without fracture (-2.4 ± 0.9 vs. -1.8 ± 0.7, P = 0.282). Apparent bone volume in the medial compartment was lower in patients with previous fragility fracture (0.295 ± 0.022 vs. 0.317 ± 0.009; P = 0.016). Profile-edge-density, a trabecular bone erosion parameter, was higher in patients with previous fragility fracture in the medial (0.008 ± 0.003 vs. 0.005 ± 0.001) and lateral compartment (0.008 ± 0.002 vs. 0.005 ± 0.001); both P = 0.025. Other DTA parameters did not differ between groups. Conclusion 7-T MRI and DTA permit detection of subtle changes in subchondral bone quality when differences in BMD are not evident.

Osseous spurs at the fovea capitis femoris-a frequent finding in asymptomatic volunteers.

OBJECTIVE: To investigate the different morphologic types of the fovea capitis femoris and the spectrum of osseous spurs/osteophytes of the fovea in asymptomatic volunteers and patients with hip osteoarthritis. MATERIAL AND METHODS: Sixty-five patients (mean age 63.6 years) with radiographically confirmed osteoarthritis of the hip and 59 asymptomatic healthy volunteers (mean age 33.9 years) underwent non-contrast MRI of the hip joint. Two radiologists independently evaluated all images. Fovea morphology (standard type, diamond type, flat type, triangular type) as well as the frequency, size and location of spurs/osteophytes of the fovea were assessed. Descriptive and inferential statistics were applied. RESULTS: The most frequent morphologic type of the fovea capitis femoris was the standard type for both asymptomatic volunteers (average 45%) and patients (average 49%). Osseous spurs were detected in 70% of the asymptomatic volunteers, and 97% of the patients had osteophytes. Spur size at all locations was significantly smaller in asymptomatic volunteers (range 1-2 mm) than osteophyte size in patients (range 1-4 mm) (p ≤ 0.035). In volunteers and patients, the spurs/osteophytes were most frequently located at the anterior border of the fovea capitis femoris. CONCLUSION: Smaller osseous spurs (<2 mm) at the border of the fovea capitis femoris are very common in asymptomatic volunteers and do not seem to be pathologic.

Frequency of inflammatory-like MR imaging findings in asymptomatic fingers of healthy volunteers.

OBJECTIVE: To describe the frequency of inflammatory-like findings on MR imaging in asymptomatic volunteers and compare them with patients with known rheumatoid arthritis and psoriatic arthritis. MATERIALS AND METHODS: MR images of fingers in 42 asymptomatic volunteers and 33 patients with rheumatoid/psoriatic arthritis were analyzed. The Outcome Measures in Rheumatology Clinical Trials (OMERACT) Rheumatoid/Psoriatic Arthritis MRI Scoring System (RAMRIS/PsAMRIS) and tenosynovitis scoring system were used to assess: bone marrow edema (BME), erosions, tendon sheath fluid/tenosynovitis, joint effusion, and soft-tissue edema. Findings and scores were compared between volunteers and patients. Inter-reader agreement was calculated (intraclass correlation coefficients, ICC). RESULTS: In volunteers, tendon sheath fluid was very common in at least one location (42/42 volunteers for reader 1, 34/42 volunteers for reader 2). BME, erosions, joint effusion, and soft-tissue edema were absent (except one BME in the 3rd proximal phalanx for reader 1). Tendon sheath fluid scores in volunteers and tenosynovitis scores in patients were high (reader 1, 7.17 and 5.39; reader 2, 2.31 and 5.45). Overall, inter-reader agreement was substantial (ICC = 0.696-0.844), except for tendon sheath fluid (ICC = 0.258). CONCLUSION: Fluid in the finger flexor tendon sheaths may be a normal finding and without gadolinium administration should not be interpreted as tenosynovitis. Bone marrow edema, erosions, joint effusion, and soft-tissue edema in the fingers most likely reflect pathology if present.

Treatment for Symptomatic SLAP Tears in Middle-Aged Patients Comparing Repair, Biceps Tenodesis, and Nonoperative Approaches: A Cost-Effectiveness Analysis.

PURPOSE: To evaluate the cost-effectiveness of nonoperative management, primary SLAP repair, and primary biceps tenodesis for the treatment of symptomatic isolated type II SLAP tear. METHODS: A microsimulation Markov model was constructed to compare 3 strategies for middle-aged patients with symptomatic type II SLAP tears: SLAP repair, biceps tenodesis, or nonoperative management. A failed 6-month trial of nonoperative treatment was assumed. The principal outcome measure was the incremental cost-effectiveness ratio in 2017 U.S. dollars using a societal perspective over a 10-year time horizon. Treatment effectiveness was expressed in quality-adjusted life-years (QALY). Model results were compared with estimates from the published literature and were subjected to sensitivity analyses to evaluate robustness. RESULTS: Primary biceps tenodesis compared with SLAP repair conferred an increased effectiveness of 0.06 QALY with cost savings of $1,766. Compared with nonoperative treatment, both biceps tenodesis and SLAP repair were cost-effective (incremental cost-effectiveness ratio values of $3,344/QALY gained and $4,289/QALY gained, respectively). Sensitivity analysis showed that biceps tenodesis was the preferred strategy in most simulations (52%); however, for SLAP repair to become cost-effective over biceps tenodesis, its probability of failure would have to be lower than 2.7% or the cost of biceps tenodesis would have to be higher than $14,644. CONCLUSIONS: When compared with primary SLAP repair and nonoperative treatment, primary biceps tenodesis is the most cost-effective treatment strategy for type II SLAP tears in middle-aged patients. Primary biceps tenodesis offers increased effectiveness when compared with both primary SLAP repair and nonoperative treatment and lower costs than primary SLAP repair. LEVEL OF EVIDENCE: Level III, economic decision analysis.

Cost-effectiveness of Virtual Bone Strength Testing in Osteoporosis Screening Programs for Postmenopausal Women in the United States.

Purpose To investigate whether assessment of bone strength with quantitative computed tomography (CT) in combination with dual-energy x-ray absorptiometry (DXA) is cost-effective as a screening tool for osteoporosis in postmenopausal women. Materials and Methods A state-transition microsimulation model of osteoporosis for postmenopausal women aged 55 years or older was developed with a lifetime horizon and U.S. societal perspective. All model inputs were derived from published literature. Three strategies were compared: no screening, DXA with T score-dependent rescreening intervals, and a combination of DXA and quantitative CT with different intervals (3, 5, and 10 years) at different screening initiation ages (55-65 years). Oral bisphosphonate therapy was started if DXA hip T scores were less than or equal to -2.5, 10-year risk for hip fracture was greater than 3% (World Health Organization Fracture Risk Assessment Tool score, or FRAX), 10-year risk for major osteoporotic fracture was greater than 20% (FRAX), quantitative CT femur bone strength was less than 3000 N, or occurrence of first fracture (eg, hip, vertebral body, wrist). Outcome measures were incremental cost-effectiveness ratios (ICERs) in 2015 U.S. dollars per quality-adjusted life year (QALY) gained and number of fragility fractures. Probabilistic sensitivity analysis was also performed. Results The most cost-effective strategy was combined DXA and quantitative CT screening starting at age 55 with quantitative CT screening every 5 years (ICER, $2000 per QALY). With this strategy, 12.8% of postmenopausal women sustained hip fractures in their remaining life (no screening, 18.7%; DXA screening, 15.8%). The corresponding percentages of vertebral fractures for DXA and quantitative CT with a 5-year interval, was 7.5%; no screening, 11.1%; DXA screening, 9%; for wrist fractures, 14%, 17.8%, and 16.4%, respectively; for other fractures, 22.6%, 30.8%, and 27.3%, respectively. In probabilistic sensitivity analysis, DXA and quantitative CT at age 55 years with quantitative CT screening every 5 years was the best strategy in more than 90% of all 1000 simulations (for thresholds of $50 000 per QALY and $100 000 per QALY). Conclusion Combined assessment of bone strength and bone mineral density is a cost-effective strategy for osteoporosis screening in postmenopausal women and has the potential to prevent a substantial number of fragility fractures. © RSNA, 2017 Online supplemental material is available for this article.

Advances in MRI around metal.

The prevalence of orthopedic metal implants is continuously rising in the aging society. Particularly the number of joint replacements is increasing. Although satisfying long-term results are encountered, patients may suffer from complaints or complications during follow-up, and often undergo magnetic resonance imaging (MRI). Yet metal implants cause severe artifacts on MRI, resulting in signal-loss, signal-pileup, geometric distortion, and failure of fat suppression. In order to allow for adequate treatment decisions, metal artifact reduction sequences (MARS) are essential for proper radiological evaluation of postoperative findings in these patients. During recent years, developments of musculoskeletal imaging have addressed this particular technical challenge of postoperative MRI around metal. Besides implant material composition, configuration and location, selection of appropriate MRI hardware, sequences, and parameters influence artifact genesis and reduction. Application of dedicated metal artifact reduction techniques including high bandwidth optimization, view angle tilting (VAT), and the multispectral imaging techniques multiacquisition variable-resonance image combination (MAVRIC) and slice-encoding for metal artifact correction (SEMAC) may significantly reduce metal-induced artifacts, although at the expense of signal-to-noise ratio and/or acquisition time. Adding advanced image acquisition techniques such as parallel imaging, partial Fourier transformation, and advanced reconstruction techniques such as compressed sensing further improves MARS imaging in a clinically feasible scan time. This review focuses on current clinically applicable MARS techniques. Understanding of the main principles and techniques including their limitations allows a considerate application of these techniques in clinical practice. Essential orthopedic metal implants and postoperative MR findings around metal are presented and highlighted with clinical examples. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:972-991.

MR imaging of soft tissue alterations after total hip arthroplasty: comparison of classic surgical approaches.

OBJECTIVES: To compare soft-tissue changes after total hip arthroplasty with posterior, direct-lateral, anterolateral, or anterior surgical approaches. METHODS: MRI of 120 patients after primary total hip arthroplasty (30 per approach) were included. Each MRI was assessed by two readers regarding identification of surgical access, fatty muscle atrophy (Goutallier classification), tendon quality (0 = normal, 1 = tendinopathy, 2 = partial tear, 3 = avulsion), and fluid collections. Readers were blinded to the surgical approach. RESULTS: Surgical access was correctly identified in all cases. The direct lateral approach showed highest Goutallier grades and tendon damage for gluteus minimus muscle (2.07-2.67 and 2.00-2.77; p = 0.017 and p = 0.001 for readers 1 and 2, respectively) and tendon (2.30/1.67; p < 0.0005 for reader 1/2), and the lateral portion of the gluteus medius tendon (2.77/2.20; p < 0.0005 for reader 1/2). The posterior approach showed highest Goutallier grades and tendon damage for external rotator muscles (1.97-2.67 and 1.57-2.40; p < 0.0005-0.006 for reader 1/2) and tendons (1.41-2.45 and 1.93-2.76; p < 0.0005 for reader 1/2). The anterolateral and anterior approach showed less soft tissue damage. Fluid collections showed no differences between the approaches. CONCLUSIONS: MRI is well suited to identify surgical approaches after THA. The anterior and anterolateral approach showed less soft tissue damage compared to the posterior and direct lateral approach. KEY POINTS: • Identification of the surgical approach is well possible with MR imaging. • Anterolateral/anterior approaches show less soft-tissue damage compared to lateral/posterior approaches. • Posterior approaches show marked damage to external rotator tendons and muscles. • After direct lateral approaches the gluteus minimus tendon/muscle show severe damage.

The Legend of the Luschka Tubercle and Its Association With Snapping Scapulae: Osseous Morphology of Snapping Scapulae on CT Images.

OBJECTIVE: The purpose of this article is to determine the osseous morphology of snapping scapulae on CT images. MATERIALS AND METHODS: Retrospectively, 2D and 3D CT images of the scapulae of 35 patients with snapping scapula were compared with 35 age-matched control group subjects. Two observers analyzed the following parameters: presence of the Luschka tubercle; abnormalities of the bones and periscapular soft tissues; shape, thickness, and length of the superior angle of the scapula; craniocaudal length of the scapula; minimum distance between the scapula and rib cage; depth of the subscapular fossa; and the superomedial angle. RESULTS: In patients with snapping scapulae, observer 1 did not find any Luschka tubercles, whereas observer 2 detected one; in the control group both observers found two Luschka tubercles (p > 0.49). One scapular osteochondroma was found in the group with snapping scapulae. No further abnormalities of the rib cage or periscapular soft tissues were found in that group. The superior angle of the scapula was significantly thicker in the snapping scapula group compared with the control group (4.8 ± 1.3 mm vs 4.0 ± 1.0 mm, p < 0.012). The subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects (25.7 ± 5.2 mm vs 21.8 ± 5.0 mm, p < 0.005). The remaining parameters did not differ significantly between the groups. CONCLUSION: The Luschka tubercle was rarely observed and not associated with a snapping scapula. However, the superior angle of the scapula was significantly thicker and the subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects.

Frequency of Arthritis-Like MRI Findings in the Forefeet of Healthy Volunteers Versus Patients With Symptomatic Rheumatoid Arthritis or Psoriatic Arthritis.

OBJECTIVE: The objective of the present study is to evaluate arthritis-like findings on MRI studies of the forefeet of healthy volunteers versus patients with symptomatic rheumatoid arthritis (RA) or psoriatic arthritis (PsA). MATERIALS AND METHODS: Two observers analyzed MR images of the forefeet of 31 healthy volunteers, 30 patients with symptomatic RA, and 30 patients with symptomatic PsA, to identify MRI patterns of RA or PsA (e.g., bone marrow edema [BME], erosions, tenosynovitis, joint effusion, periarticular soft-tissue edema, or bony proliferations) on the basis of the Outcome Measures in Rheumatoid Arthritis Clinical Trial RA MRI scoring system and the PsA MRI scoring system. The Mann-Whitney test with Bonferroni correction was used for statistical analysis. RESULTS: Reader 1 found BME in 14 healthy volunteers (45%), whereas reader 2 found BME in 10 volunteers (32%). Tenosynovitis was observed by reader 1 in three healthy volunteers (10%). Joint effusion was found by reader 1 in seven healthy volunteers (23%) and by reader 2 in three volunteers (10%); the mean intensity grades for these findings were low (range, 1-1.33). Erosions, soft-tissue edema, and bony proliferations were not found in the forefeet of healthy volunteers. Reader 1 and reader 2 observed all arthritis-like features on the MR images of patients with RA. The percentages of patients with RA who had such MRI features, as identified by reader 1 and reader 2, respectively, were as follows: BME, 83% and 80%; erosions, 40% and 40%; tenosynovitis, 33% and 17%; effusion, 87% and 53%; soft-tissue edema, 20% and 27%; and bony proliferations, 3% and 3%. The percentages of patients with PsA who were found to have arthritis-like findings on MR images, as determined by reader 1 and reader 2, respectively, were as follows: BME, 70% and 67%; erosions, 20% and 20%; tenosynovitis, 57% and 50%; effusion, 70% and 37%; and soft-tissue edema, 60% and 53%. Bony proliferations were observed by reader 2 only in 7% of patients with PsA. The mean minimum intensity grade was 1 (for tenosynovitis in patients with RA, as observed by reader 2), whereas the maximum intensity grade was 2.53 (for erosions in patients with RA, as observed by reader 1). Tenosynovitis and soft-tissue edema were observed more frequently in patients with PsA than in patients with RA (p = 0.001-0.059). CONCLUSION: On the forefoot of healthy volunteers, mild BME is a common finding, and tenosynovitis and joint effusion are occasional findings. The frequency and intensity of arthritis-like findings on MRI are similar in patients with RA and PsA, with the exception of tenosynovitis and soft-tissue edema, which are more frequently observed in patients with PsA than in patients with RA.

Delayed-Onset Muscle Soreness: Temporal Assessment With Quantitative MRI and Shear-Wave Ultrasound Elastography.

OBJECTIVE: The objective of our study was to assess delayed-onset muscle soreness (DOMS) over time using quantitative MRI and shear-wave ultrasound (US) elastography. SUBJECTS AND METHODS: Five male (mean age ± SD, 39.6 ± 4.6 years) and five female (30.6 ± 13.5 years) volunteers underwent 1.5-T MRI before and after (15 minutes, 1 day, 3 days, 7 days) performing unilateral eccentric resistance exercise of the elbow flexor muscles. The MRI examinations included fluid-sensitive, DWI, and diffusion-tensor imaging sequences of the distal upper arm. Muscle edema, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were assessed. US of the brachialis muscle was performed before and after (15 minutes, 12 hours, 1 day, 2 days, 3 days, 7 days) exercise to measure mean shear-wave velocity (SWV). Pain and muscle tightness were assessed. RESULTS: For men, muscle edema was moderate and peaked 3 days after exercise; for women, muscle edema was mild and peaked 1-3 days after exercise. ADC was highest 3 days after exercise in men (mean, 1809.22 × 10-6 mm2/s; before exercise, 1529.88 × 10-6 mm2/s) and women (1741.90 × 10-6 mm2/s; before exercise, 1475.80 × 10-6 mm2/s). FA dropped from 361.00 in men and 389.00 in women before exercise to a minimum of 252.12 and 321.28, respectively, 3 days after exercise. Mean SWV increased after exercise in men (before exercise, 3.00 ± 0.30 m/s; peak [15 minutes after exercise], 4.04 ± 0.90 m/s) and women (before, 2.82 ± 0.40 m/s; peak [1 day after exercise], 3.23 ± 0.40 m/s) and subsequently returned to normal. In men, the ADC values of the brachialis muscle positively correlated with mean SWV (r = 0.92, p = 0.028). FA negatively correlated with pain in men (r = -0.993, p = 0.001) Muscle edema outlasted clinical symptoms in most volunteers. CONCLUSION: FA inversely correlates with pain and may be a useful imaging parameter for assessment of DOMS. Shear-wave US elastography shows a temporary increase of muscle stiffness after DOMS-inducing exercise but does not correlate with quantitative MRI parameters or clinical symptoms.

Measurement of acetabular version based on biplanar radiographs with 3D reconstructions in comparison to CT as reference standard in cadavers.

To quantify acetabular version using 3 D reconstructions based on biplanar radiographs (BPR) with CT as reference standard. No institutional review board approval was needed. Nine dry-bone pelvises underwent BPR in five different positions (rotation/tilt). The 3 D models of each pelvis were reconstructed by two radiologists on the basis of anatomical landmarks using semi-automated software. Automated software was used to assess the 3 D models and to calculate acetabular versions perpendicular to the anterior pelvic plane on all levels in the craniocaudal direction in 1 mm steps. Transverse CT images perpendicular to the anterior pelvic plain were reconstructed through the acetabulum in 1 mm steps. Both readers measured acetabular version on each image. Inter-reader agreement was calculated. Measurements based on BPR and CT were compared. Inter-reader agreement was almost perfect for BPR-based acetabular version measurements (ICC (intraclass correlation coefficient) = 0.920, P < 0.0005) and CT (ICC = 0.990, P < 0.0005). Correlation of acetabular versions between the five BPR-positions was substantial/almost perfect (ICC = 0.722-0.887 and 0.749-0.872 for readers 1 and 2, respectively; most P < 0.0005). The acetabular version measurements between the ap-positioning from BPR and CT showed moderate agreement (mean CCC (concordance correlation coefficient) = 0.733 for reader 1, CCC = 0.755 for reader 2). Acetabular version on multiple levels can be measured using BPR and dedicated post-processing software and is relatively independent of pelvic rotation and tilt. Clin. Anat. 30:591-598, 2017. © 2017 Wiley Periodicals, Inc.

Hip Imaging in Athletes: Sports Imaging Series.

Hip or groin pain in athletes is common and clinical presentation is often nonspecific. Imaging is a very important diagnostic step in the work-up of athletes with hip pain. This review article provides an overview on hip biomechanics and discusses strategies for hip imaging modalities such as radiography, ultrasonography, computed tomography, and magnetic resonance (MR) imaging (MR arthrography and traction MR arthrography). The authors explain current concepts of femoroacetabular impingement and the problem of high prevalence of cam- and pincer-type morphology in asymptomatic persons. With the main focus on MR imaging, the authors present abnormalities of the hip joint and the surrounding soft tissues that can occur in athletes: intraarticular and extraarticular hip impingement syndromes, labral and cartilage disease, microinstability of the hip, myotendinous injuries, and athletic pubalgia. (©) RSNA, 2016.

Quantification of early fatty infiltration of the rotator cuff muscles: comparison of multi-echo Dixon with single-voxel MR spectroscopy.

OBJECTIVES: To evaluate quantification of early fatty infiltration in supraspinatus muscles with magnetic resonance (MR) imaging using a T2*-corrected multi-echo 3D-gradient-echo Dixon-based sequence (multi-echo Dixon) and compare it to proton-MR-spectroscopy. METHODS: Sixty subjects (mean age 46 years, 41 men) with good supraspinatus muscle quality on 1.5 T MR imaging were included. Fat percentage (FP) in the supraspinatus muscle was quantified using a multi-echo Dixon compared to single-voxel MR spectroscopy as reference standard. In 18 subjects the multi-echo Dixon was repeated to assess test-retest reliability. Measurements based on multi-echo Dixon were performed by two independent readers by placing regions-of-interest (ROIs) in the supraspinatus muscle corresponding to the MR-spectroscopy voxel. Intraclass and concordance correlation coefficients (ICC/CCC) were used for statistical analysis. RESULTS: Test-retest reliability was substantial for reader 1 (ICC = 0.757) and almost perfect for reader 2 (ICC = 0.873). Inter-reader reliability for multi-echo Dixon was almost perfect (ICC = 0.893, P < .0005). Mean FP in all 60 subjects with multi-echo Dixon was 3.5 ± 1.6 for reader 1, 3.7 ± 1.8 for reader 2, and 2.8 ± 1.4 with MR spectroscopy. Correlation between multi-echo Dixon and MR spectroscopy was moderate (CCC = 0.641). CONCLUSION: The multi-echo Dixon sequence is a reliable method and comparable to MR-spectroscopy for quantification of low levels of fatty infiltration in the supraspinatus muscle. KEY POINTS: • Multi-echo Dixon for low fat quantification in muscles is reliable. • Multi-echo Dixon low fat quantification is comparable to single-voxel MR spectroscopy • Multi-echo Dixon detects substantial differences in fatty infiltration within Goutallier 0-1.

Subchondroplasty: What the Radiologist Needs to Know.

OBJECTIVE: Subchondroplasty is a novel minimally invasive procedure that is used to treat painful bone marrow lesions in patients with knee osteoarthritis or insufficiency fractures. The objective of this article is to describe the surgical technique and the pre- and postoperative imaging findings of a small case series acquired at a single center. CONCLUSION: The radiologist should be familiar with the anticipated postoperative imaging appearances after subchondroplasty and the potential complications.

Enthesitis of lumbar spinal ligaments in clinically suspected spondyloarthritis: value of gadolinium-enhanced MR images in comparison to STIR.

OBJECTIVE: To compare detection of spinal ligament enthesitis between gadolinium-enhanced fat-saturated T1-weighted gadolinium-enhanced fat-saturated T1-weighted (T1+Gd) and STIR sequences in patients with suspected spondyloarthritis. MATERIALS AND METHODS: Sixty-eight patients (37 males, 42 ± 14 years) with a sacroiliac-joint (SIJ) and lumbar spine MRI for suspected spondyloarthritis were prospectively included. Sagittal T1+Gd and STIR images of the lumbar spine were assessed by two readers for enthesitis of interspinous/supraspinous ligaments, and for capsulitis of facet-joints between T12-S1. Patients' MRI were grouped according to ASAS (Assessment of SpondyloArthritis international Society) criteria in positive (group A) or negative (group B) SIJs. Enthesitis/capsulitis were compared between groups. Interreader agreement was assessed. RESULTS: Enthesitis/capsulitis per patient was statistically significantly more frequent with T1+Gd compared to STIR (p ≤ 0.007), except for interspinous ligaments for reader 1 (p = 0.455). Interspinous enthesitis, supraspinous enthesitis, and capsulitis were present with T1+Gd(STIR) in 64.7 %(72.1 %), 60.3 %(17.7 %), and 61.8 %(29.4 %) for reader 1, and 51.5 %(41.2 %), 45.6 %(7.4 %), and 91.2 %(45.5 %) for reader 2. There were 76.5 %(52/68) patients in group A and 23.5 %(16/68) in group B. Total number of enthesitis/capsulitis on T1+Gd was statistically significantly higher in group A than B (4.96 vs. 2.94, p = 0.026; 8.12 vs. 5.25, p = 0.041 for reader 1 and 2, respectively). Interreader agreement showed mixed results for interspinous/supraspinous/capsulitis but was higher on T1+Gd (ICC = 0.838/0.783/0.367; p ≤ 0.001) compared to STIR (ICC = 0.652/0.298/0.224; p ≤ 0.032). CONCLUSION: In patients with suspected spondyloarthritis, enthesitis/capsulitis in the lumbar spine are common findings and more frequently/reliably detected with T1+Gd than STIR. In patients with positive SIJ-MRI, the total number of enthesitis/capsulitis in T1+Gd was higher compared to patients with negative SIJ-MRI.

Outcomes after fluoroscopy-guided iliopsoas bursa injection for suspected iliopsoas tendinopathy.

OBJECTIVES: To report patient outcomes up to 1 month after fluoroscopy-guided iliopsoas bursa injection for suspected iliopsoas tendinopathy. METHODS: Thirty-nine consecutive patients (mean age 45 years; range 15-77) who underwent fluoroscopy-guided therapeutic iliopsoas bursa injection using an anterolateral approach and who returned an outcomes questionnaire were prospectively included. The Patients' Global Impression of Change (PGIC) scale was recorded 1 day, 1 week, and 1 month after the injection (primary outcome measure). Patients' subjective pain level data were collected prior to the injection (baseline) using a numeric rating scale (NRS; 0 = no pain; 10 = maximum pain). NRS scores were completed 15 min, 1 day, 1 week, and 1 month post-injection and compared to baseline. RESULTS: Forty-nine per cent of patients reported clinically relevant 'improvement' (PGIC) 1 month post-injection. Mean NRS score prior to injection was 5.9 ± 2.1. Mean NRS scores after 15 min (3.6 ± 2.7), 1 day (4.4 ± 2.7), 1 week (3.4 ± 1.9), and 1 month (3.5 ± 2.5) were statistically significantly lower (p ≤ 0.001) compared to baseline. Reduction of NRS ≥50 % after 15 min was achieved in 49 % (56 % of those unimproved at 1 month). CONCLUSIONS: Fluoroscopy-guided iliopsoas bursa injection leads to a relevant 'improvement' at 1 month or significant pain reduction after 15 min in most patients.

Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision.

OBJECTIVES: To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). METHODS: Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. RESULTS: SEMAC reduced mean artefact size for STIR (11.8 cm(2) vs. 37.7 cm(2)) and PD (16.8 cm(2) vs. 18.9 cm(2)), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. CONCLUSIONS: STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. KEY POINTS: • Slice-encoding for metal artefact correction (SEMAC) MRI reduces metal-induced artefact size. • STIR SEMAC detects more bone marrow oedema in painful unicompartmental knee arthroplasty. • STIR SEMAC can help the orthopaedic surgeon with decision making. • PD SEMAC suffers from blurring of images, potentially masking relevant meniscal lesions. • PD SEMAC does not improve cartilage lesion detection in the non-operated compartments.