Superior metal artifact reduction of tin-filtered low-dose CT in imaging of lumbar spinal instrumentation compared to conventional computed tomography.

OBJECTIVE: To compare the image quality of low-dose CT (LD-CT) with tin filtration of the lumbar spine after metal implants to standard clinical CT, and to evaluate the potential for metal artifact and dose reduction. MATERIALS AND METHODS: CT protocols were optimized in a cadaver torso. Seventy-four prospectively included patients with metallic lumbar implants were scanned with both standard CT (120 kV) and tin-filtered LD-CT (Sn140kV). CT dose parameters and qualitative measures (1 = worst,4 = best) were compared. Quantitative measures included noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and the width and attenuation of the most prominent hypodense metal artifact. Standard CT and LD-CT were assessed for imaging findings. RESULTS: Tin-filtered LD-CT was performed with 60% dose saving compared to standard CT (median effective dose 3.22 mSv (quartile 1-3: 2.73-3.49 mSv) versus 8.02 mSv (6.42-9.27 mSv; p < .001). Image quality of CT and tin-filtered low-dose CT was good with excellent depiction of anatomy, while image noise was lower for CT and artifacts were weaker for tin-filtered LD-CT. Quantitative measures also revealed increased noise for tin-filtered low-dose CT (41.5HU), lower SNR (2) and CNR (0.6) compared to CT (32HU,3.55,1.03, respectively) (all p < .001). However, tin-filtered LD-CT performed superior regarding the width and attenuation of hypodense metal artifacts (2.9 mm and -767.5HU for LD-CT vs. 4.1 mm and -937HU for CT; all p < .001). No difference between methods was observed in detection of imaging findings. CONCLUSION: Tin-filtered LD-CT with 60% dose saving performs comparable to standard CT in detection of pathology and surgery related complications after lumbar spinal instrumentation, and shows superior metal artifact reduction.

Value of MR arthrography for evaluation of children and adolescents with clinically suspected intraarticular cause of hip pain.

PURPOSE: To evaluate the distribution of intra- and extraarticular MRI findings in children and adolescents with clinically suspected intraarticular cause of hip pain in order to assess the need for additional intraarticular contrast administration. MATERIAL AND METHODS: Database was searched over a period of 34 months retrospectively for consecutive hip MR arthrography in young patients (8-17 years) with suspected intraarticular cause of hip or groin pain. Exclusion criteria were prior hip surgery, follow-up examination due to known intraarticular pathology, incomplete examination, qualitatively non-diagnostic examinations, and missing informed consent. Reports of fellowship-trained MSK radiologists were searched for intraarticular versus extraarticular findings explaining hip or groin pain. RESULTS: Seventy patients (68% female; median age: 14.5 years; range:10.8-16.9 years) were analyzed. No reason for pain was found in 30 (42.9%) hips, extraarticular reasons in 20 (28.6%) cases, intraarticular in 14 (20.0%), and both (intra- and extraarticular) in 6 (8.6%) hips. Most common extraarticular reasons were apophysitis (14.3%), other bony stress reactions (12.9%), intramuscular edema (7%), tendinitis (5.7%), and trochanteric bursitis (4.3%). Labral pathology was the most common intraarticular finding (overall:34.3%; partial tear:15.7%, complete tear:15.7%), most frequent at the anterosuperior position (81.8%). Cartilage defects (1.4%), intraarticular neoplasia (1.4%), and tear of the femoral head ligament (2.8%) were rarely found. Synovitis and loose bodies were not observed. Cam-(37.1%) and pincer-configurations (47.1%) were common while hip dysplasia was rare (5.7%). CONCLUSION: MRI in children and adolescents with hip pain should be done primarily without intraarticular contrast administration since most cases show an extraarticular pain reason or no diagnosis detectable with MRI.

Can pre-operative intraarticular injection predict pain relief after total hip arthroplasty?

BACKGROUND: To study if pain relief after injection and arthroplasty correlate. METHODS: A retrospective cohort study included consecutive patients (n = 88; median age 64 (interquartile range (IQR) 22) years, 49 (56%) females) that received fluoroscopic-guided intra-articular hip injection with contrast agent, anaesthetic (diagnostic), and corticosteroid (therapeutic) before implantation of primary total hip arthroplasty. Pain scores were assessed pre-injection, post-injection after 15 min (diagnostic phase) at first clinical follow up (therapeutic phase; median 2 (IQR 2) months), and postoperatively (last follow up (median 15 (IQR 5) months)). Responders had reduction in pain score ≥ 20 (numeric rating scale 0-100) points. The primary outcome was the same (or inverse) response to injection and arthroplasty. RESULTS: The median pain scores were higher pre-injection (68 (IQR 30) points) compared to the diagnostic phase (18 (IQR 40) points; p < 0.001), therapeutic phase (50 (IQR 40) points; p < 0.001), and post-operatively (2 (IQR 15) points; p < 0.001). On the one hand, 69 (78%) cases had the same response in the diagnostic phase and post-operatively (rho = 0.58; p < 0.001; sensitivity 83%); on the other hand 32 (36%) cases had the same response in the therapeutic phase and post-operatively (rho = 0.25; p < 0.001; sensitivity 33%). Furthermore, 57% and 91% of patients had an even better response post-operatively than in the diagnostic and therapeutic phases. CONCLUSIONS: Pre-operative intraarticular injection can predict pain relief after primary total hip arthroplasty. A positive response to hip arthroplasty may be better predicted by the response to local anaesthetic (diagnostic phase) than corticosteroids. Most patients (91%) with osteoarthritis may expect better pain relief after arthroplasty compared to the therapeutic phase after injection.

Muscle atrophy in diabetic patients with Charcot foot: a case-control study.

PURPOSE: To evaluate the distribution and severity of muscle atrophy in diabetic patients with active Charcot foot (CF) compared to diabetic patients without CF. Furthermore, to correlate the muscle atrophy with severity of CF disease. MATERIAL/METHODS: In this retrospective study, MR images of 35 diabetic patients (21 male, median:62.1 years ± 9.9SD) with active CF were compared with an age- and gender-matched control group of diabetic patients without CF. Two readers evaluated fatty muscle infiltration (Goutallier-classification) in the mid- and hindfoot. Furthermore, muscle trophic (cross-sectional muscle area (CSA)), intramuscular edema (none/mild versus moderate/severe), and the severity of CF disease (Balgrist Score) were assessed. RESULTS: Interreader correlation for fatty infiltration was substantial to almost perfect (kappa-values:0.73-1.0). Frequency of fatty muscle infiltration was high in both groups (CF:97.1-100%; control:77.1-91.4%), but severe infiltration was significantly more frequent in CF patients (p-values: < 0.001-0.043). Muscle edema was also frequently seen in both groups, but significantly more often in the CF group (p-values: < 0.001-0.003). CSAs of hindfoot muscles were significantly smaller in the CF group. For the flexor digitorum brevis muscle, a cutoff value of 139 mm2 (sensitivity:62.9%; specificity:82.9%) in the hindfoot was found to differentiate between CF disease and the control group. No correlation was seen between fatty muscle infiltration and the Balgrist Score. CONCLUSION: Muscle atrophy and muscle edema are significantly more severe in diabetic patients with CF disease. Muscle atrophy does not correlate with the severity of active CF disease. A CSA < 139 mm2 of the flexor digitorum brevis muscle in the hindfoot may indicate CF disease.

Dual energy CT arthrography in shoulder instability: successful iodine removal with virtual non-contrast images and accurate 3D reformats of the glenoid for assessment of bone loss.

OBJECTIVE: To evaluate the image quality of dual energy CT (DECT) of the shoulder after arthrography and of virtual non-contrast (VNC) 3D reformats of the glenoid and to compare glenoid measurements on VNC 3D reformats and on 2D CTs. MATERIALS AND METHODS: DECT arthrography (80 kV/140 kV) was performed in 42 shoulders of 41 patients with instability using diluted iodinated contrast media (80 mg/ml). VNC images and VNC 3D reformats of the glenoid were calculated using image postprocessing. Dose parameters, CT values of intraarticular iodine and muscle, image contrast (iodine/muscle), and image quality (5-point scale: 1 = worst, 5 = best) were evaluated. Two independent readers assessed glenoid morphology and performed glenoid measurements on 2D and 3D images. RESULTS: Calculation of VNC images and VNC 3D reformats was successful in 42/42 shoulders (100%). The effective dose was mean 1.95 mSv (± 0.9 mSv). CT values of iodine and muscle were mean 1014.6 HU (± 235.8 HU) and 64.5 HU(± 8.6 HU), respectively, and image contrast was mean 950.2 HU (± 235.5 HU). Quality of cross-sectional images, VNC images, and VNC 3D reformats was rated good (median 4 (4-5), 4 (3-4), 4 (3-5), respectively). Detection of an osseous defect was equal on 2D and 3D images (13/42, P > 0.99) with no difference for measurement of the glenoid diameter with mean 28.3 mm (± 2.8 mm) vs. 28.4 mm (± 2.9 mm) (P = 0.5), width of the glenoid defect with 3.2 mm (± 2.1 mm) vs. 3.1 mm (± 2.3 mm) (P = 0.84), surface area with 638.5 mm2 (± 127 mm2) vs. 640.8 mm2 (± 129.5 mm2) (P = 0.47), and surface area of the defect with 46.6 mm2 (± 44.3 mm2) vs. 47.2 mm2 (± 48.0 mm2) (P = 0.73), respectively. CONCLUSION: DECT shoulder arthrography is feasible and allows successful iodine removal with generation of VNC images and accurate VNC 3D reformats of the glenoid for assessment of bone loss.

Ligaments of the scapho-trapezial-trapezoidal joint: MR anatomy in asymptomatic and symptomatic individuals.

PURPOSE: To evaluate the MRI anatomy of the scapho-trapezial-trapezoidal (STT) ligament complex in asymptomatic and symptomatic individuals. MATERIAL AND METHODS: In this retrospective study, STT ligament complex of 42 (male 69%, median age 37.5 years) asymptomatic (n = 25) and symptomatic (n = 17) (defined as pain described over the STT joint) individuals was examined using a high-resolution 3D proton density-weighted isovoxel sequence (MR arthrogram) with multiplanar reconstructions. Two musculoskeletal radiologists independently assessed visibility, signal intensity (SI), morphology, and thickness of the radiopalmar scapho-trapezial ligament (rpSTL), palmar scapho-capitate capsular ligament (pSCL), palmar STT capsule (pSTTC), and dorsal STT capsule (dSTTC). RESULTS: Interreader agreement ranged from fair to good and intraclass correlations were good. The rpSTL was almost always visible (85.7%/80.1%; reader 1/reader 2). The pSCL and dSTTC were visible in all cases. The pSTTC was visible in only 52.4%/42.9%. Mean thickness of the rpSTL, pSCL, pSTTC, and dSTTC was 1.4 ± 0.5 mm/1.3 ± 0.5 mm, 2.8 ± 0.7 mm/2.7 ± 0.6 mm, 0.5 ± 0.5 mm/0.4 ± 0.4 mm, and 0.5 ± 0.3 mm/0.3 ± 0.3 mm. Both readers rated SI of the rpSTL significantly more often as increased in the symptomatic group (increased SI in asymptomatic group: 20%/15%; symptomatic group: 56%/50%) (p-values < 0.005). For all other ligaments, no significant difference was observed for SI between symptomatic and asymptomatic group (p-values ranging between 0.188 and 0.890). For all other ligaments, no significant differences were observed regarding ligament visibility, morphology, and thickness (p-values ranging between 0.274 and 1.000). CONCLUSION: The anatomy of the STT ligament complex can consistently be visualized on high-resolution 3D MRI. Increased signal intensity of rpSTL is significantly more frequent in patients with radial-sided wrist pain.

Virtual non-contrast images calculated from dual-energy CT shoulder arthrography improve the detection of intraarticular loose bodies.

OBJECTIVE: This study aims to evaluate the image quality of virtual non-contrast (VNC) images calculated from dual-energy CT shoulder arthrography (DECT-A) and their ability to detect periosteal calcifications and intraarticular loose bodies. MATERIALS AND METHODS: In 129 shoulders of 123 patients, DECT arthrography (80 kV/140 kV) was performed with diluted iodinated contrast material (80 mg/ml). VNC images were calculated with image postprocessing. VNC image quality (1 = worst, 5 = best), dose parameters, and CT numbers (intraarticular iodine, muscle, VNC joint fluid density) were assessed. Image contrast (iodine/muscle) and percentage of iodine removal were calculated. Two independent readers evaluated VNC and DECT-A images for periosteal calcifications and intraarticular loose bodies, and diagnostic confidence (1 = low, 4 = very high) was assessed. RESULTS: VNC images (129/129) were of good quality (median 4 (3-4)), and the mean effective dose of DECT-A scans was 2.21 mSv (± 1.0 mSv). CT numbers of iodine, muscle, and VNC joint fluid density were mean 1017.6 HU (± 251.6 HU), 64.6 HU (± 8.2 HU), and 85.3 HU (± 39.5 HU), respectively. Image contrast was mean 953.1 HU (± 251 HU) on DECT-A and 31.3 HU (± 32.3 HU) on VNC images. Iodine removal on VNC images was 91% on average. No difference was observed in the detection of periosteal calcifications between VNC (n = 25) and DECT-A images (n = 21) (p = 0.29), while the detection of intraarticular loose bodies was superior on VNC images (14 vs. 7; p = 0.02). Diagnostic confidence was higher on VNC images for both periosteal calcifications (median 3 (3-3) vs. 3 (3-3); p = 0.009) and intraarticular loose bodies (median 3 (3-4) vs. 3 (3-3); p < 0.001). CONCLUSION: VNC images from DECT shoulder arthrography are superior to DECT-A images for the detection of intraarticular loose bodies and increase the confidence in detecting periosteal calcifications.

Pulley, Flexor, and Extensor Tendon Injuries of the Hand.

Tendon injuries represent the second most common injury of the hand (after fractures) and are a common scanning indication in radiology. Pulley injuries are very frequent in rock climbers with the A2 pulley the most commonly affected. Tendon and pulley injuries can be reliably evaluated using ultrasound (US) and magnetic resonance imaging (MRI). US can be postulated as a first-line imaging modality, allowing dynamic examination. MRI is essential for cases with ongoing diagnostic doubt post-US and also for preoperative pulley reconstruction assessment.

The "Balgrist Score" for evaluation of Charcot foot: a predictive value for duration of off-loading treatment.

OBJECTIVE: To develop a new magnetic resonance imaging(MRI) scoring system for evaluation of active Charcot foot and to correlate the score with a duration of off-loading treatment ≥ 90 days. METHODS: An outpatient clinic database was searched retrospectively for MRIs of patients with active Charcot foot who completed off-loading treatment. Images were assessed by two radiologists (readers 1 and 2) and an orthopedic surgeon (reader 3). Sanders/Frykberg regions I-V were evaluated for soft tissue edema, bone marrow edema, erosions, subchondral cysts, joint destruction, fractures, and overall regional manifestation using a score according to degree of severity (0-3 points). Intraclass correlations (ICC) for interreader agreement and receiver operating characteristic analysis between MR findings and duration of off-loading-treatment were calculated. RESULTS: Sixty-five feet in 56 patients (34 men) with a mean age of 62.4 years (range: 44.5-85.5) were included. Region III (reader 1/reader 2: 93.6/90.8%) and region II (92.3/90.8%) were most affected. The most common findings in all regions were soft tissue edema and bone marrow edema. Mean time between MRI and cessation of off-loading-treatment was 150 days (range: 21-405). The Balgrist Score was defined in regions II and III using soft tissue edema, bone marrow edema, joint destruction, and fracture. Interreader agreement for Balgrist Score was excellent: readers 1/2: ICC 0.968 (95% CI: 0.948, 0.980); readers 1/2/3: ICC 0.856 (0.742, 0.917). A cutoff of ≥ 9.0 points in Balgrist Score (specificity 72%, sensitivity 66%) indicated a duration of off-loading treatment ≥ 90 days. CONCLUSION: The Balgrist Score is a new MR scoring system for assessment of active Charcot foot with excellent interreader agreement. The Balgrist Score can help to identify patients with off-loading treatment ≥ 90 days.

3D hindfoot alignment measurements based on low-dose biplanar radiographs: a clinical feasibility study.

OBJECTIVE: To test a 3D-hindfoot alignment (HA) measurement technique based on low-dose biplanar radiographs (BPRs) in a clinical setting and compare the results with 2D-HA measurements on long axial view radiographs (LARs). MATERIALS AND METHODS: This prospective study was approved by the local institutional review board. HA measurements on 3D-BPR and 2D-LAR of 50 patients (29 female; mean age 47 ± 16.6 years) were compared (positive values = valgus; negative values = varus). Two independent musculoskeletal radiologists (readers 1 and 2) performed 3D-HA measurements on BPR using a custom-made MATLAB code and measured HA on LAR during two separate readout sessions. Descriptive statistics and intraclass correlation coefficients (ICC) were calculated, and Bland-Altman plots were used for intermethod comparison. RESULTS: Using BPRs, HA was 0.8° ± 9.°1 (range, -20.2 to 20.0) for reader 1, and 0.7° ± 9.5° (range, -21.2 to 18.3) for reader 2. HA on LARs was -2.0 ° ± 7.0° (range, -27.0° to 11.1°) for reader 1 and - 1.7° ± 7.0° (range, -24.1° to 14.3°) for reader 2. Interreader agreement for measurements was excellent, both for BPRs (ICC = 0.992; 95% CI:0.986-0.995) and LAR measurements (ICC = 0.962; 95% CI:0.932-0.978). Mean difference between the two methods was -2.43° (range, -29.4° to 25.6°) for reader 1 and -2.6° (range,-28.7° to 30.2°) for reader 2. On Bland-Altman plots, three measurements of reader 1 and six measurements of reader 2 were outside of the ±1.96 SD interval. CONCLUSION: Hindfoot alignment measurements on 3D-BPR have an excellent interreader agreement in a clinical setting. Large measurement errors can occur in individual patients using 2D-LAR alone. Therefore, we suggest using 3D-BPR measurements in daily routine for the assessment of HA, which are independent of rotational foot malpositioning.

MRI Predictors of Posterolateral Corner Instability: A Decision Tree Analysis of Patients with Acute Anterior Cruciate Ligament Tear.

Purpose To determine the diagnostic performance of MRI for helping to predict posterolateral knee instability in patients with acute anterior cruciate ligament (ACL) tear. Materials and Methods This retrospective cohort study was performed in a consecutive series of 162 patients (mean age, 32.8 years ± 10.0 [standard deviation]; 95 men [mean age, 31.0 years ± 9.6] and 67 women [mean age, 35.4 years ± 10.0]) who underwent ACL reconstruction with (n = 19) or without (n = 143) concomitant posterolateral corner (PLC) reconstruction between June 2014 and February 2017. MR images were evaluated by two radiologists. Diagnostic performance of imaging findings was calculated. Clinical evidence of posterolateral instability requiring PLC reconstruction served as reference standard. The most significant predictors of posterolateral instability were determined with decision tree analysis. Results In patients with and without PLC reconstruction, respectively, the lateral collateral ligament was completely torn in 10 of 19 (52.6%) and seven of 143 (4.9%) patients; the posterior cruciate ligament in two of 19 (10.5%) and five of 143 (3.5%) patients; the popliteus tendon in three of 19 (15.8%) and none of 143 (0%) patients; and the biceps femoris tendon in four of 19 (21.1%) and none of 143 (0%) patients (data for reader 1). The smaller structures of the PLC were not constantly viewable. Complete tear or avulsion of the lateral collateral ligament was more frequent in patients who needed PLC reconstruction (P < .001), and decision tree analysis revealed that this finding was the most statistically significant predictor of posterolateral instability. Instability was correctly predicted in 147 of 162 patients (90.7%) by reader 1 and 151 of 162 patients (93.2%) by reader 2. Conclusion Complete tear or avulsion of the lateral collateral ligament was the most significant predictor at MRI of posterolateral instability. Assessment of the smaller posterolateral corner structures did not improve diagnostic performance. © RSNA, 2018 Online supplemental material is available for this article.

Prevalence of vitamin D insufficiency in radiologists: a cross-sectional study.

OBJECTIVE: To compare the prevalence of vitamin D insufficiency between radiologists and a control group of non-radiologists. MATERIALS AND METHODS: This prospective cross-sectional study was conducted at the Swiss Congress of Radiology in May of 2016. Attendees (radiologists and non-radiologists) were asked to give a venous blood sample to measure vitamin D (25-hydroxyvitamin D) blood serum level. Vitamin D insufficiency was defined as < 50 nmol/l (30 ng/ml). We collected information on profession, age, gender, vitamin D supplements, recent sunny vacation, and eating fish. We compared vitamin D between radiologists and non-radiologists. RESULTS: A total of 137 radiologists (mean age, 38 ± 10 years) and 164 non-radiologists (mean age, 40 ± 12 years) participated in the study. Prevalence of vitamin D insufficiency in both groups was similar (58.4% (80/137) vs. 53.7% (88/164); p = 0.240). Forty-three participants were under vitamin D supplementation. In those without supplementation, we found no difference in vitamin D between groups (44.0 ± 16.2 nmol/l (17.6 ± 6.5 ng/ml) vs. 44.4 ± 16.9 nmol/l (17.8 ± 6.8 ng/ml); p = 0.757). Average vitamin D levels for radiologists were slightly lower (-0.98 nmol/l (0.39 ng/ml), 95% confidence interval - 5.96 to 4.00 (- 2.38 to 1.6 ng/ml); p = 0.699), when adjusting for the potential confounders, but not statistically significant. The odds ratio of vitamin D insufficiency for radiologists versus non-radiologists was 1.7 (95% CI = 0.94-3.06; p = 0.078) after adjusting for the other independent variables. CONCLUSIONS: The prevalence of vitamin D insufficiency in radiologists was high (58.4%), but not substantially higher than in non-radiologists.

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.

Total knee arthroplasty in patients with a history of illicit intravenous drug abuse.

PURPOSE: Injection drug users are at high risk for both infection with blood-borne pathogens, namely, human immune deficiency virus (HIV), hepatitis-B, -C virus, various bacterial infections, as well as early primary and secondary joint degeneration. When total knee arthroplasty (TKA) is anticipated the risk of septic complications is a major concern. The purpose of this study was to assess the clinical and radiographic outcome of patients with a history of intravenous drug use after total knee arthroplasty. The primary outcome was revision rate. Secondary outcomes were the Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Society Score (KSS) and radiographic loosening. METHODS: We retrospectively reviewed the records of 1,692 TKA performed or revised in our institution. Data of 18 TKA in 12 patients (11 male, 1 female; average age 42, range 23-62 years) with a history of intravenous opioid abuse were available for final analysis. RESULTS: The mean follow up was 125 (range 25-238) months. Seven patients required revision surgery due to periprosthetic joint infection after 62 months (range 5-159): one two staged revision, three arthrodesis and three amputations. The median prosthesis survival was 101 (95%-CI 48-154) months. CONCLUSION: Total knee arthroplasty in patients with a history of intravenous drug abuse is associated with major complications, including above-the-knee amputation. If permanent abstinence from intravenous drug abuse is doubtful, other therapeutic options including primary arthrodesis should be considered.

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.

Femoral and tibial torsion measurements in children and adolescents: comparison of MRI and 3D models based on low-dose biplanar radiographs.

OBJECTIVE: The aim of our study was to evaluate the reliability and interchangeability of femoral (FT) and tibial torsion (TT) measurements in children using magnetic resonance (MR) imaging compared to measurements on 3D models based on biplanar radiographs (BPR). MATERIALS AND METHODS: FT and TT were measured in 60 children (mean age 10.1 years; range 6.2-16.2 years; 28 female) using axial MR images by two readers. MR measurements were compared to measurements based on BPR-3D models by two separate independent readers. Interreader and intermethod agreements were calculated using descriptive statistics, the intraclass correlation coefficient (ICC), and Bland-Altman analysis. RESULTS: FT/TT was -8.4°-54.1°/0°-45.9° on MR images and -13°-63°/4°-52° for measurements on BPR-3D models. The median of difference between the two methods was -0.18° (range -13.6°-19.1°) for FT and -0.20° (range -18.4°-9.5°) for TT, respectively. Interreader agreement (ICC) of FT/TT measurements was 0.98/0.96 on MR images and 0.98/0.94 on BPR 3D models. Intermethod agreement (ICC) for MR measurements was 0.95 [95% confidence interval (CI), 0.93-0.96] for FT and of 0.86 (CI, 0.24-0.95) for TT. Mean interreader differences at MR were 3.1° (0.0°-8.0°) for FT and 3.2° (0.1°-9.5°) for TT. On Bland-Altman plots all measurements were within the 95% limit of agreement (-10.8°; 11.5° for FT; -14.6°; 4.2°) for TT-except for five measurements of FT and six measurements of TT. CONCLUSION: FT measurements on MR images are comparable to measurements using BPR-3D models. TT measurements differ between the two modalities, but the discrepancy is comparable to measurement variations between CT and BPR.

Quantitative Shear-Wave US Elastography of the Supraspinatus Muscle: Reliability of the Method and Relation to Tendon Integrity and Muscle Quality.

PURPOSE: To evaluate the reliability of ultrasonographic (US) elastography of the supraspinatus (SSP) muscle, define normal shear-wave velocity (SWV) values, and correlate findings with tendon integrity and muscle quality. MATERIALS AND METHODS: The study was approved by the local ethics committee, and written informed consent was obtained from all patients. SSP SWV (in meters per second) was prospectively assessed twice in 22 asymptomatic volunteers (mean age ± standard deviation, 53.8 years ± 15.3; 11 women and 11 men) by two independent examiners by using shear-wave elastography. Forty-four patients (mean age, 51.9 years ± 15.0; 22 women and 22 men) were prospectively included. SWV findings were compared with tendon integrity, tendon retraction (Patte classification), fatty muscle infiltration (Goutallier stages 0-IV), and muscle volume atrophy (tangent sign) on magnetic resonance (MR) images. Descriptive statistics, Spearman correlation, analysis of variance, two-sample t test, and intraclass correlation coefficient (ICC) were used. RESULTS: Test-retest reliability for mean total SWV (MTSWV) was good for examiner 1 (ICC = 0.70; 95% confidence interval [CI]: 0.30, 0.87; P = .003) and excellent for examiner 2 (ICC = 0.80; 95% CI: 0.53, 0.92; P < .001). Interexaminer reliability was excellent (ICC = 0.89; 95% CI: 0.64, 0.96; P < .001). MTSWV in volunteers (3.0 m/sec ± 0.5) was significantly higher than that in patients (2.5 m/sec ± 0.5; P = .001). For tendon integrity, no significant difference in MTSWV was found. For tendon retraction, MTSWV varies significantly between patients with different degrees of retraction (P = .047). No significant differences were found for Goutallier subgroups. MTSWV was significantly lower with a positive tangent sign (P = .015; n = 10). CONCLUSION: Shear-wave elastography is reproducible for assessment of the SSP muscle. Mean normal SSP SWV is 3.0 m/sec ± 0.5. SWV decreases with increasing fat content (Goutallier stage 0-III) and increases in the final stage of fatty infiltration (Goutallier stage IV).

Assessment of two-dimensional (2D) and three-dimensional (3D) lower limb measurements in adults: Comparison of micro-dose and low-dose biplanar radiographs.

OBJECTIVE: To evaluate reliability of 2D and 3D lower limb measurements in adults using micro-dose compared to low-dose biplanar radiographs(BPR). MATERIALS AND METHODS: One hundred patients (mean 54.9 years) were examined twice using micro-dose and low-dose BPR. Length and mechanical axis of lower limbs were measured on the antero-posterior(ap) micro-dose and low-dose images by two independent readers. Femoral and tibial torsions of 50 patients were measured by two independent readers using reconstructed 3D-models based on the micro-dose and low-dose BPR. Intermethod and interreader agreements were calculated using descriptive statistics, intraclass-correlation-coefficient(ICC), and Bland-Altman analysis. RESULTS: Mean interreader-differences on micro-dose were 0.3 cm(range 0-1.0)/ 0.7°(0-2.9) for limb length/axis and 0.4 cm (0-1.0)/0.8°(0-3.3) on low-dose BPR. Mean intermethod-difference was 0.04 cm ± 0.2/0.04° ± 0.6 for limb length/axis. Interreader-ICC for limb length/axis was 0.999/0.991 on micro-dose and 0.999/0.987 on low-dose BPR. Interreader-ICC for micro-dose was 0.879/0.826 for femoral/ tibial torsion, for low-dose BPR was 0.924/0.909. Mean interreader-differences on micro-dose/low-dose BPR were 3°(0-13°)/2°(0°-12°) for femoral and 4°(0-18°)/3°(0°-10°) for tibial torsion. Mean intermethod-difference was -0.1° ± 5.0/-0.4° ± 2.9 for femoral/tibial torsion. Mean dose-area-product was significantly lower (9.9 times;p < 0.001) for micro-dose BPR. CONCLUSION: 2D-and 3D-measurements of lower limbs based on micro-dose BPR are reliable and provide a 10-times lower radiation dose. KEY POINTS: • Lower limb length and mechanical axis can be reliably measured with micro-dose. • Femoral and tibial torsion can be reliably assessed with micro-dose. • Micro-dose allows a huge reduction of radiation exposure.

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.

Comparison of shear wave velocity measurements assessed with two different ultrasound systems in an ex-vivo tendon strain phantom.

OBJECTIVE: The purpose of this study is to compare the reliability of SW velocity measurements of two different ultrasound systems and their correlation with the tangent traction modulus in a non-static tendon strain model. MATERIALS AND METHODS: A bovine tendon was fixed in a custom-made stretching device. Force was applied increasing from 0 up to 18 Newton. During each strain state the tangent traction modulus was determined by the stretcher device, and SW velocity (m/s) measurements using a Siemens S3000 and a Supersonic Aixplorer US machine were done for shear modulus (kPa) calculation. RESULTS: A strong significant positive correlation was found between SW velocity assessed by the two ultrasound systems and the tangent traction modulus (r = 0.827-0.954, p < 0.001), yet all SW velocity-based calculations underestimated the reference tissue tangent modulus. Mean difference of SW velocities with the S3000 was 0.44 ± 0.3 m/s (p = 0.002) and with the Aixplorer 0.25 ± 0.3 m/s (p = 0.034). Mean difference of SW velocity between the two US-systems was 0.37 ± 0.3 m/s (p = 0.012). CONCLUSION: In conclusion, SW velocities are highly dependent on mechanical forces in the tendon tissue, but for controlled mechanical loads appear to yield reproducible and comparable measurements using different US systems.