Improved Resolution and Image Quality of Musculoskeletal Magnetic Resonance Imaging using Deep Learning-based Denoising Reconstruction: A Prospective Clinical Study

OBJECTIVE

To prospectively evaluate a deep learning-based denoising reconstruction (DLR) for improved resolution and image quality in musculoskeletal (MSK) magnetic resonance imaging (MRI).

METHODS

Images from 137 contrast-weighted sequences in 40 MSK patients were evaluated. Each sequence was performed twice, first with the routine parameters and reconstructed with a routine reconstruction filter (REF), then with higher resolution and reconstructed with DLR, and with three conventional reconstruction filters (NL2, GA43, GA53). The five reconstructions (REF, DLR, NL2, GA43, and GA53) were de-identified, randomized, and blindly reviewed by three MSK radiologists using eight scoring criteria and a forced ranking. Quantitative SNR, CNR, and structure's full width at half maximum (FWHM) for resolution assessment were measured and compared. To account for repeated measures, Generalized Estimating Equations (GEE) with Bonferroni adjustment was used to compare the reader's scores, SNR, CNR, and FWHM between DLR vs. NL2, GA43, GA53, and REF.

RESULTS

Compared to the routine REF images, the resolution was improved by 47.61% with DLR from 0.39 ± 0.15 mm2 to 0.20 ± 0.06 mm2 (p < 0.001). Per-sequence average scan time was shortened by 7.93% with DLR from 165.58 ± 21.86 s to 152.45 ± 25.65 s (p < 0.001). Based on the average scores, DLR images were rated significantly higher in all image quality criteria and the forced ranking (p < 0.001).

CONCLUSION

This prospective clinical evaluation demonstrated that DLR allows approximately two times finer resolution and improved image quality compared to the standard-of-care images.

Two-year outcomes with a bioinductive collagen implant used in augmentation of arthroscopic repair of full-thickness rotator cuff tears: final results of a prospective multicenter study

BACKGROUND

Full-thickness rotator cuff tears (FTRCTs) represent a common shoulder injury that, if untreated, can progress in size, become increasingly painful, and inhibit function. These lesions are often surgically repaired, with double-row arthroscopic repair often preferred for larger tears. Biological augmentation technologies have been developed to improve rates of postoperative radiographic retear and enhance patient-reported outcomes after surgical FTRCT repair. This study sought to confirm that augmented repair with a bioinductive bovine collagen implant results in favorable retear rates and patient outcomes with follow-up to 2 years.

METHODS

A prospective multicenter cohort study was undertaken to determine the efficacy and safety of augmenting single- or double-row arthroscopic repair of FTRCTs with a bioinductive bovine collagen implant. Of 115 adult patients participating, 66 (57.4%) had medium (1-3-cm) tears and 49 (42.6%) had large (3-5-cm) tears. Magnetic resonance imaging and patient-reported outcomes (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] and Constant-Murley Score [CMS]) were performed and recorded at baseline, 3 months, 1 year, and 2 years.

RESULTS

Mean duration of follow-up was 2.1 years (range, 1.5-2.9 years). Between baseline and 2-year follow-up, mean total thickness of the supraspinatus tendon increased by 12.5% for medium tears and by 17.1% for large tears. Radiographic retear was noted in 7 of 61 available patients (11.5%) with medium tears, and in 14 of 40 patients (35.0%) with large tears. In both groups, these tears primarily occurred before the 3-month follow-up visit (13 of 21 [61.9%]). Radiographic retear with the supplemented double-row (DR) repair technique was 13.2% overall (12 of 91 DR patients; 11.3% for medium tears and 15.8% for large tears). The minimal clinically important difference was achieved by >90% of patients with both medium and large tears for both ASES and CMS. There were 2 serious adverse events classified by the treating surgeon as being possibly related to the device and/or procedure (1 case of swelling/drainage and 1 case of intermittent pain). Nine patients (7.8%; 4 medium tears and 5 large tears) required reoperation of the index rotator cuff surgery.

CONCLUSION

Final 2-year data from this study confirm that using this implant in augmentation of arthroscopic double-row repair of FTRCTs provides favorable rates of radiographic retear and substantial functional recovery. The relative safety of the device is also further supported.

Shoulder Pathology on Magnetic Resonance Imaging in Asymptomatic Elite-Level Rock Climbers

Background:

The prevalence of findings on shoulder magnetic resonance imaging (MRI) is high in asymptomatic athletes of overhead sports.

Purpose/Hypothesis:

The purpose of this study was to determine the prevalence of atypical findings on MRI in shoulders of asymptomatic, elite-level climbers and to evaluate the association of these findings with clinical examination results. It was hypothesized that glenoid labrum, long head of the biceps tendon, and articular cartilage pathology would be present in >50% of asymptomatic athletes.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 50 elite climbers (age range, 20-60 years) without any symptoms of shoulder pain underwent bilateral shoulder examinations in addition to dedicated bilateral shoulder 3-T^† MRI. Physical examinations were performed by orthopaedic sports medicine surgeons, while MRI scans were interpreted by 2 blinded board-certified radiologists to determine the prevalence of abnormalities of the articular cartilage, glenoid labrum, biceps tendon, rotator cuff, and acromioclavicular joint.

Results:

MRI evidence of tendinosis of the rotator cuff, subacromial bursitis, and long head of the biceps tendonitis was exceptionally common, at 80%, 79%, and 73%, respectively. Labral pathology was present in 69% of shoulders, with discrete labral tears identified in 56%. Articular cartilage changes were also common, with humeral pathology present in 57% of shoulders and glenoid pathology in 19% of shoulders. Climbers with labral tears identified in this study had significantly increased forward elevation compared with those without labral tears in both active (P = .026) and passive (P = .022) motion.

Conclusion:

The overall prevalence of intra-articular shoulder pathology detected by MRI in asymptomatic climbers was 80%, with 57% demonstrating varying degrees of glenohumeral articular cartilage damage. This high rate of arthritis differs significantly from prior published reports of other overhead sports athletes.

Cotyloid Fossa Coverage Percentages May Be Associated With Alpha Angle, Labral Tear, and Clinical Outcomes in Patients With Femoroacetabular Impingement

BACKGROUND

Within the hip joint, the anatomy of the acetabulum and cotyloid fossa is well established. There is little literature describing the association between the size of the cotyloid fossa relative to the acetabulum and characteristics of patients with femoroacetabular impingement (FAI).

PURPOSE/HYPOTHESIS

The purpose was to calculate the cotyloid fossa coverage percentage in the acetabulum and determine its association with patient characteristics, radiographic parameters, intra-articular findings, and preoperative patient-reported outcomes in patients with FAI. We hypothesized there is an association between the cotyloid fossa coverage percentage of the acetabulum and characteristics of patients with FAI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients were included who underwent standard clinical 3-T magnetic resonance imaging of the hip and primary arthroscopic FAI correction surgery during 2015 and 2016. Exclusion criteria were age <18 or >40 years, osteoarthritis, labral reconstruction, previous ipsilateral hip surgery, and hip dysplasia. Measurements of the cotyloid fossa and surrounding lunate cartilage were performed to calculate cotyloid fossa width (CFW) and cotyloid fossa height (CFH) coverage percentages. The relationships between coverage percentages and patient characteristics and intraoperative findings were assessed using independent t tests or Pearson correlations.

RESULTS

An overall 146 patients were included. Alpha angle negatively correlated with CFH coverage percentage (r = -0.19; P = .03) and positively correlated with labral tear size (r = 0.28; P < .01). CFH coverage percentage was negatively correlated with labral tear size (r = -0.24; P < .01). Among patients with degenerative tears, CFH was negatively correlated with labral tear size (r = -0.31; P < .01). However, this association was no longer significant after adjusting for sex (partial r = -0.10; P = .39). Cotyloid fossa coverage was not associated with the condition of the cotyloid fossa synovium (synovitis vs no synovitis). CFW coverage percentage was negatively correlated with the 12-Item Short Form Health Survey (SF-12) physical component summary score (r = -0.23; P < .01).

CONCLUSION

The CFW and CFH coverage percentages may be associated with alpha angle, labral tear size, and SF-12 physical component summary score in patients with FAI. We may be able to predict the labral condition based on preoperative measurements of CFH and CFW coverage percentages.

Accuracy of MRI-Based Talar Cartilage Thickness Measurement and Talus Bone and Cartilage Modeling: Comparison with Ground-Truth Laser Scan Measurements

OBJECTIVE

The purpose of this work was to compare measurements of talar cartilage thickness and cartilage and bone surface geometry from clinically feasible magnetic resonance imaging (MRI) against high-accuracy laser scan models. Measurement of talar bone and cartilage geometry from MRI would provide useful information for evaluating cartilage changes, selecting osteochondral graft sources or creating patient-specific joint models.

DESIGN

Three-dimensional (3D) bone and cartilage models of 7 cadaver tali were created using (1) manual segmentation of high-resolution volumetric sequence 3T MR images and (2) laser scans. Talar cartilage thickness was compared between the laser scan- and MRI-based models for the dorsal, medial, and lateral surfaces. The laser scan- and MRI-based cartilage and bone surface models were compared using model-to-model distance.

RESULTS

Average cartilage thickness within the dorsal, medial, and lateral surfaces were 0.89 to 1.05 mm measured with laser scanning, and 1.10 to 1.22 mm measured with MRI. MRI-based thickness was 0.16 to 0.32 mm higher on average in each region. The average absolute surface-to-surface differences between laser scan- and MRI-based bone and cartilage models ranged from 0.16 to 0.22 mm for bone (MRI bone models smaller than laser scan models) and 0.35 to 0.38 mm for cartilage (MRI bone models larger than laser scan models).

CONCLUSIONS

This study demonstrated that cartilage and bone 3D modeling and measurement of average cartilage thickness on the dorsal, medial, and lateral talar surfaces using MRI were feasible and provided similar model geometry and thickness values to ground-truth laser scan-based measurements.

Isolated bioinductive repair of partial-thickness rotator cuff tears using a resorbable bovine collagen implant: two-year radiologic and clinical outcomes from a prospective multicenter study

BACKGROUND

Current surgical treatment options for partial-thickness tears (eg, takedown and repair, in situ repair) are limited by the degenerative nature of the underlying tendon and may require extensive intervention that can alter the anatomic footprint. The complexity of available techniques to address these issues led to the development of a resorbable collagen implant, which can be used to create a bioinductive repair of partial-thickness tears.

METHODS

We prospectively enrolled 33 patients with chronic, degenerative, intermediate-grade (n = 12), or high-grade (n = 21) partial-thickness tears (11 articular, 10 bursal, 4 intrasubstance, and 8 hybrid) of the supraspinatus tendon in a multicenter study. After arthroscopic subacromial decompression without a traditional rotator cuff repair, a bioinductive implant was secured over the bursal surface of the tendon. Clinical outcomes were assessed using American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores (CMS) preoperatively and at 3 months, 1 year, and 2 years postoperatively. Magnetic resonance imaging was performed to assess postoperative tendon healing and thickness at the original tear site.

RESULTS

At 2-year follow-up, mean ASES and CMS scores improved both clinically and statistically at 1 and 2 years, compared with baseline, for intermediate- and high-grade tears. There was magnetic resonance imaging evidence of new tissue fill-in within the original baseline tear in 100% of the intermediate-grade tears and 95% of the high-grade tears. In 90.9% of the intermediate-grade tears and 84.2% of the high-grade tears, this new tissue fill-in represented at least an additional 50% of the volume of the initial lesion. From baseline to 2-year follow-up, the mean tendon thickness increased by 1.2 mm (standard deviation, 1.3; P = .012) and 1.8 mm (standard deviation, 2.2; P = .003) in the intermediate- and high-grade tears, respectively. The analysis of tear grade and location revealed no statistically significant difference in the change in mean tendon thickness at any time point. One patient with a high-grade articular lesion demonstrated progression to a full-thickness tear; however, the patient was noncompliant and the injury occurred while shoveling snow 1 month after surgery. Neither tear location nor treatment of bicep pathology affected the ASES or CMS scores at any follow-up point. No serious adverse events related to the implant were reported.

CONCLUSION

Final results from this 2-year prospective study indicate that the use of this resorbable bovine collagen implant for isolated bioinductive repair of intermediate- and high-grade partial-thickness rotator cuff tears of the supraspinatus is safe and effective, regardless of tear grade and location.

Automated analysis of immediate reliability of T2 and T2* relaxation times of hip joint cartilage from 3 T MR examinations

BACKGROUND

Magnetic resonance (MR) T2 and T2* mapping sequences allow in vivo quantification of biochemical characteristics within joint cartilage of relevance to clinical assessment of conditions such as hip osteoarthritis (OA).

PURPOSE

To evaluate an automated immediate reliability analysis of T2 and T2* mapping from MR examinations of hip joint cartilage using a bone and cartilage segmentation pipeline based around focused shape modelling.

STUDY TYPE

Technical validation.

SUBJECTS

17 asymptomatic volunteers (M: F 7:10, aged 22-47 years, mass 50-90 kg, height 163-189 cm) underwent unilateral hip joint MR examinations. Automated analysis of cartilage T2 and T2* data immediate reliability was evaluated in 9 subjects (M: F 4: 5) for each sequence.

FIELD STRENGTH/SEQUENCE

A 3 T MR system with a body matrix flex-coil was used to acquire images with the following sequences: T2 weighted 3D-trueFast Imaging with Steady-State Precession (water excitation; 10.18 ms repetition time (TR); 4.3 ms echo time (TE); Voxel Size (VS): 0.625 × 0.625 × 0.65 mm; 160 mm field of view (FOV); Flip Angle (FA): 30 degrees; Pixel Bandwidth (PB): 140 Hz/pixel); a multi-echo spin echo (MESE) T2 mapping sequence (TR/TE: 2080/18-90 ms (5 echoes); VS: 4 × 0.78 × 0.78 mm; FOV: 200 mm; FA: 180 degrees; PB: 230 Hz/pixel) and a MESE T2* mapping sequence (TR/TE: 873/3.82-19.1 ms (5 echoes); VS: 3 × 0.625 × 0.625 mm; FOV: 160 mm; FA: 25 degrees; PB: 250 Hz/pixel).

ASSESSMENT

Automated cartilage segmentation and quantitative analysis provided T2 and T2* data from test-retest MR examinations to assess immediate reliability.

STATISTICAL TESTS

Coefficient of variation (CV) and intraclass correlations (ICC_{2, 1}) to analyse automated T2 and T2* mapping reliability focusing on the clinically important superior cartilage regions of the hip joint.

RESULTS

Comparisons between test-retest T2 and (T2*) data revealed mean CV's of 3.385% (1.25%), mean ICC_{2, 1}'s of 0.871 (0.984) and median mean differences of -1.139ms (+0.195ms).

CONCLUSION

The T2 and T2* times from automated analyses of hip cartilage from test-retest MR examinations had high (T2) and excellent (T2*) immediate reliability.

Si racetrack optical modulator based on the III-V/Si hybrid MOS capacitor

We have fabricated a Si racetrack optical modulator based on a III-V/Si hybrid metal-oxide-semiconductor (MOS) capacitor. The III-V/Si hybrid MOS optical phase shifter was integrated to a Si racetrack resonator with a coupling length of 200 µm and a coupling gap of 700 nm. The fabricated Si racetrack resonator demonstrated a small VπL of 0.059 Vcm. For 10-dB optical intensity modulation, the Si racetrack resonator showed a 60% smaller driving voltage than a Mach-Zehnder interferometer modulator with the same phase shifter, leading to a better balance between high energy efficiency and large modulation bandwidth.

Quantitative T2 mapping of the glenohumeral joint cartilage in asymptomatic shoulders and shoulders with increasing severity of rotator cuff pathology

•

Glenohumeral cartilage T2 values were correlated to increasing rotator cuff pathology severity.

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Massive tear versus lesser injury differences were most evident in superior humeral cartilage.

•

Sagittal T2 mapping best captures superior humeral head cartilage change in massive tear patients.

Purpose

To examine the relationship between glenohumeral cartilage T2 mapping values and rotator cuff pathology.

Method

Fifty-nine subjects (age 48.2 ± 13.5 years, 15 asymptomatic volunteers and 10 tendinosis, 13 partial-thickness tear, 8 full-thickness tear, and 13 massive tear patients) underwent glenohumeral cartilage T2 mapping. The humeral head cartilage was segmented in the sagittal and coronal planes. The glenoid cartilage was segmented in the coronal plane. Group means for each region were calculated and compared between the groups.

Results

Massive tear group T2 values were significantly higher than the asymptomatic group values for the humeral head cartilage included in the sagittal (45 ± 7 versus 32 ± 4 ms, p <  .001) and coronal (44 ± 6 versus 38 ± 1 ms, p =  0.01) plane images. Mean T2 was also significantly higher for massive than full-thickness tears (45 ± 7 versus 38 ± 5 ms, p =  0.02), massive than partial-thickness tears (45 ± 7 versus 34 ± 4 ms, p <  0.001), and massive tears than tendinosis (45 ± 7 versus 35 ± 4 ms, p =  0.001) in the sagittal-images humeral head region and significantly higher for massive tears than asymptomatic shoulders (44 ± 6 versus 38 ± 1 ms, p =  0.01) in the coronal-images humeral head region.

Conclusion

Humeral head cartilage T2 values were significantly positively correlated with rotator cuff pathology severity. Massive rotator cuff tear patients demonstrated significantly higher superior humeral head cartilage T2 mapping values relative to subjects with no/lesser degrees of rotator cuff pathology.

Retear rates and clinical outcomes at 1 year after repair of full-thickness rotator cuff tears augmented with a bioinductive collagen implant: a prospective multicenter study

Background

Biologic technologies can potentially augment existing arthroscopic rotator cuff repair to improve retear rates and postoperative outcomes. The purpose of this study was to evaluate healing rates and clinical outcomes of full-thickness rotator cuff repairs augmented with a bioinductive bovine collagen implant.

Methods

In this prospective multicenter study, investigators enrolled 115 patients (mean age, 60.4 years) with full-thickness rotator cuff tears. There were 66 (57.4%) medium (1-3 cm) tears and 49 (42.6%) large (3-5 cm) tears. Eligible patients consisted of those ≥21 years of age with chronic shoulder pain lasting longer than 3 months and unresponsive to conservative therapy. Patients underwent single- or double-row repair augmented with a bioinductive bovine collagen implant. At the baseline, 3 months, and 1 year, magnetic resonance imaging was performed and patients were assessed for American Shoulder and Elbow Surgeons (ASES) Shoulder Score and Constant-Murley Score (CMS). The primary failure end point was retear, classified as any new full-thickness defect observed on magnetic resonance imaging.

Results

There were 13 retears (11.3%) at 3 months, with an additional 6 (19 total [16.5%]) found at 1 year. In large tears, double-row repair had a significantly lower rate of retear at 3 months (P = .0004) and 1 year (P = .0001) compared with single-row repair. ASES and CMS scores significantly improved between the baseline and 1 year for medium and large tears. At 1 year, the minimally clinically important difference for ASES and CMS was met by 91.7% (95% CI: 84.9-96.1) and 86.4% (95% CI: 78.2-92.4) of patients, respectively. Patients without retear and those <65 years of age had significantly better CMS scores at 1 year when compared with those with retear and those ≥65 years (P < .05). There was no statistically significant difference in outcomes based on treatment of the biceps tendon. Of 9 reported reoperations in the operative shoulder, only 2 were considered potentially related to the collagen implant.

Conclusion

Interim results from this prospective study indicate a favorable rate of retear relative to the literature and improvement in clinical function at 1 year after adjunctive treatment with the study implant augmenting standard arthroscopic repair techniques.

T2* mapping and subregion analysis of the tibialis posterior tendon using 3 Tesla magnetic resonance imaging

OBJECTIVE

Early detection of tibialis posterior tendon changes and appropriate intervention is necessary to prevent disease progression to flat-foot deformity and foot/ankle dysfunction, and the need for operative treatment. Currently, differentiating between early-stage tibialis posterior tendon deficiency patients who will benefit from conservative vs more aggressive treatment is challenging. The objective of this work was to establish a quantitative MRI T2* mapping method and subregion baseline values in the tibialis posterior tendon in asymptomatic ankles for future clinical application in detecting tendon degeneration.

METHODS

26 asymptomatic volunteers underwent T2* mapping. The tendon was divided axially into seven subregions. Summary statistics for T2* within each subregion were calculated and compared using Tukey post-hoc pairwise comparisons.

RESULTS

Results are reported for 24 subjects. The mean tibialis posterior tendon T2* was 7 ± 1 ms. Subregion values ranged from 6 ± 1 to 9 ± 2 ms with significant between-region differences in T2*. Inter- and intrarater absolute agreement intraclass correlation coefficient (ICC) values were all "excellent" (0.75 < ICC=1.00) except for regions 5 through 7, which had "fair to good" interrater and/or and intrarater ICC values (0.4 < ICC=0.75).

CONCLUSION

A tibialis posterior tendon T2* mapping protocol, subregion division method, and baseline T2* values for clinically relevant regions were established. Significant differences in T2* were observed along the tendon length.

ADVANCES IN KNOWLEDGE

This work demonstrates that regional variation exists and should be considered for future T2*-based research on posterior tibias tendon degeneration and when using T2* mapping to evaluate for potential tibialis posterior tendon degeneration.

Quantitative mapping of acute and chronic PCL pathology with 3 T MRI: a prospectively enrolled patient cohort

Background

The diagnosis of incomplete acute and chronic posterior cruciate ligament (PCL) tears can be challenging with conventional magnetic resonance (MR) imaging, particularly for injuries in which the ligament appears continuous as occurs with chronic PCL tears that have scarred in continuity. Quantitative mapping from MR imaging may provide additional useful diagnostic information in these cases. The purpose of this study was to assess the feasibility of quantifying transverse relaxation time (T2) mapping values at 3 Tesla (T) in a prospectively enrolled patient cohort with chronic PCL tears.

Methods

Twelve subjects with acute or chronic functionally torn PCL, confirmed on clinical exam and posterior knee stress radiographs (with 8 mm or more of increased posterior tibial translation), were enrolled prospectively over a span of 4 years (age: 28–52 years, injury occurred 2 weeks to 15 years prior). Unilateral knee MR images were acquired at 3 T, including a multi-echo spin-echo T2 mapping scan in the sagittal plane. For the six subjects with a continuous PCL on MR imaging the PCL was manually segmented and divided into proximal, mid and distal thirds. Summary statistics for T2 values in each third of the ligament were compiled.

Results

Across the six patient subjects with a continuous ligament, the mean T2 for the entire PCL was 36 ± 9 ms, with the highest T2 values found in the proximal third (proximal: 41 ms, mid 30 ms, distal 37 ms). The T2 values for the entire PCL and for the proximal third subregion were higher than those recently published for asymptomatic volunteers (entire posterior cruciate ligament: 31 ± 5 ms, proximal: 30 ms, mid: 29 ms, distal: 37 ms) with similar methodology.

Conclusion

Mean T2 values were quantified for acute and chronic PCL tears in this prospectively enrolled patient cohort and were higher than those reported for asymptomatic volunteers. This novel approach of using quantitative mapping to highlight injured areas of the posterior cruciate ligament has potential to provide additional diagnostic information in the challenging case of a suspected posterior cruciate ligament tear which appears continuous, including chronic tears that have scarred in continuity and may appear intact on conventional magnetic resonance imaging.

Ultra-power-efficient 2 × 2 Si Mach-Zehnder interferometer optical switch based on III-V/Si hybrid MOS phase shifter

We have demonstrated an ultra-power-efficient 2 × 2 Si Mach-Zehnder interferometer optical switch with III-V/Si hybrid metal-oxide-semiconductor (MOS) phase shifters. The efficient low-loss phase modulation enables low-crosstalk and broadband switching in conjunction with multimode interference couplers consisting of tapered input and output ports. Owing to the negligible gate leakage current in the hybrid MOS capacitor, the power consumption required for switching is 0.18 nW, approximately 10⁷ times smaller than that of a Si thermo-optic phase shifter. We also demonstrated a switching time of less than 20 ns. The III-V/Si hybrid MOS phase shifter is promising for fabricating large-scale Si photonic integrated circuits that require efficient, low-loss, and high-speed optical phase control.

Quantitative mapping of glenohumeral cartilage in asymptomatic subjects using 3 T magnetic resonance imaging

OBJECTIVE

The purpose of this study was to develop quantitative T2 mapping methodology in asymptomatic shoulders for the entire mappable region of the glenohumeral cartilage in the coronal and sagittal planes, to assess the feasibility and limitations of the development of a diagnostic tool for future application in symptomatic patients.

MATERIALS AND METHODS

Twenty-one asymptomatic volunteers underwent sagittal and coronal glenohumeral T2 mapping, as the spherical geometry of the humeral head obviates the need to evaluate the entire glenohumeral cartilage in a single plane. The humeral head cartilage orthogonal to the mapping plane was manually segmented in the sagittal and coronal planes, whereas the glenoid cartilage was segmented in the coronal plane. Cartilage T2 summary statistics were calculated and coverage in each mapping plane was qualitatively assessed.

RESULTS

The mean ± standard deviation of the glenoid cartilage T2 was 38 ± 2 ms. The coronal and sagittal mapping planes captured different regions of the humeral head with some overlap: inferior-medial to superior-lateral versus superior/superior-lateral to anterior-lateral and posterior-lateral respectively. The mean humeral head cartilage T2 in the coronal plane was 41 ± 3 ms, which was significantly different (p < 0.05) from the sagittal plane mean of 34 ± 2 ms.

CONCLUSION

This study measured characteristic glenoid and humeral head cartilage T2 values over the area mappable with two planes. Importantly, this study demonstrated that two-dimensional mapping in a single plane or two combined planes cannot capture the entirety of the semi-spherical humeral head cartilage. This highlights the need for three-dimensional T2 mapping techniques in the shoulder.

Radiologic and clinical evaluation of a bioabsorbable collagen implant to treat partial-thickness tears: a prospective multicenter study

BACKGROUND

Treatment of partial-thickness cuff tears remains controversial. Although conservative therapy may treat symptoms, these defects do not spontaneously heal and conversion to a full-thickness lesion with subsequent repair may alter the tendon footprint. The ability to induce new tissue formation and limit tear progression in intermediate- and high-grade partial-thickness tears without surgical repair may represent a significant advancement in the treatment paradigm for these lesions.

METHODS

We prospectively enrolled 33 patients with chronic, degenerative, intermediate-grade (n = 12) or high-grade (n = 21) partial-thickness tears (11 articular, 10 bursal, 4 intrasubstance, and 8 hybrid) of the supraspinatus tendon in a multicenter study. Following arthroscopic subacromial decompression without repair, a bioinductive implant was attached over the bursal surface of the tendon. Clinical outcomes were assessed using American Shoulder and Elbow Surgeons and Constant-Murley scores preoperatively and at 3 and 12 months postoperatively. Magnetic resonance imaging was performed to assess postoperative tendon healing and thickness at the original tear site.

RESULTS

At 1-year follow-up, clinical scores improved significantly (P <.0001) and the mean tendon thickness increased by 2.0 mm (P <.0001). Magnetic resonance imaging evidence of complete healing was found in 8 patients and a considerable reduction in defect size was shown in 23, whereas 1 lesion remained stable. In 1 noncompliant patient with a high-grade articular lesion, progression to a full-thickness tear occurred while shoveling snow 1 month after surgery. No serious adverse events related to the implant were reported.

CONCLUSIONS

Arthroscopic implantation of a bioinductive collagen scaffold is a safe and effective treatment for intermediate- to high-grade partial-thickness rotator cuff tears of the supraspinatus tendon.

Predictors of outcomes after arthroscopic transosseous equivalent rotator cuff repair in 155 cases: a propensity score weighted analysis of knotted and knotless self-reinforcing repair techniques at a minimum of 2 years

PURPOSE

To evaluate the outcomes of two commonly used transosseous-equivalent (TOE) arthroscopic rotator cuff repair (RCR) techniques for full-thickness supraspinatus tendon tears (FTST) using a robust multi-predictor model.

METHODS

155 shoulders in 151 patients (109 men, 42 women; mean age 59 ± 10 years) who underwent arthroscopic RCR of FTST, using either a knotted suture bridging (KSB) or a knotless tape bridging (KTB) TOE technique were included. ASES and SF-12 PCS scores assessed at a minimum of 2 years postoperatively were modeled using propensity score weighting in a multiple linear regression model. Patients able to return to the study center underwent a follow-up MRI for evaluation of rotator cuff integrity.

RESULTS

The outcome data were available for 137 shoulders (88%; n = 35/41 KSB; n = 102/114 KTB). Seven patients (5.1%) that underwent revision rotator cuff surgery were considered failures. The median postoperative ASES score of the remaining 130 shoulders was 98 at a mean follow-up of 2.9 years (range 2.0-5.4 years). A higher preoperative baseline outcome score and a longer follow-up had a positive effect, whereas a previous RCR and workers' compensation claims (WCC) had a negative effect on final ASES or SF 12 PCS scores. The repair technique, age, gender and the number of anchors used for the RCR had no significant influence. Fifty-two patients returned for a follow-up MRI at a mean of 4.4 years postoperatively. Patients with a KSB RCR were significantly more likely to have an MRI-diagnosed full-thickness rotator cuff re-tear (p < 0.05).

CONCLUSIONS

Excellent outcomes can be achieved at a minimum of 2 years following arthroscopic KSB or KTB TOE RCR of FTST. The preoperative baseline outcome score, a prior RCR, WCC and the length of follow-up significantly influenced the outcome scores. The repair technique did not affect the final functional outcomes, but patients with KTB TOE RCR were less likely to have a full-thickness rotator cuff re-tear.

LEVEL OF EVIDENCE

Level III, Retrospective Comparative Study.

Ovo-vegetarian diet is associated with lower systemic blood pressure in Taiwanese women

OBJECTIVE

This study was designed to investigate blood pressure (BP) profiles among Taiwanese women with different dietary patterns.

STUDY DESIGN

Cross-sectional study.

METHODS

A total of 269 non-hypertensive Taiwanese women, 40 years of age or older, were surveyed using structured questionnaires, and measurements of BP and physiological parameters were made. To assess differences among vegans, ovo-vegetarians, and meat eaters in terms of BP, demographic, and health behavior data, the chi-squared and Fisher's exact tests were employed for categorical variables, and analysis of variance and independent t-tests were performed for continuous variables. Multiple regression analysis was used to examine the relationship between BP and dietary patterns while controlling for potential confounding factors.

RESULTS

A significant difference was found among the three test groups in terms of age, education, employment, stress, and waist-hip ratio. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) significantly differed among the three groups. After controlling for age, body weight, waist circumference, and hip circumference, the three groups were observed to be a significant risk factor of the SBP and DBP. The SBP and DBP of the ovo-vegetarian group were significantly lower than those of the meat-eater group. No significant differences were found between the vegan and meat-eater groups in terms of SBP and DBP.

CONCLUSION

Dietary pattern is a likely risk factor for SBP and DBP outcomes in Taiwanese women. In particular, the SBP and DBP of ovo-vegetarians are the lowest among the values observed for all dietary patterns. This finding suggests that an ovo-vegetarian diet is beneficial for long-term BP control and prevention of hypertension in females.

T2* Mapping of Peroneal Tendons Using Clinically Relevant Subregions in an Asymptomatic Population

BACKGROUND

Peroneal tendon evaluation is particularly demanding using current magnetic resonance imaging (MRI) techniques because of their curving path around the lateral malleolus. Quantifiable, objective data on the health of the peroneal tendons could be useful for improving diagnosis of tendon pathology and tracking post-treatment responses. The purpose of this study was to establish a method and normative T2-star (T2*) values for the peroneal tendons in a screened asymptomatic cohort using clinically reproducible subregions, providing a baseline for comparison with peroneal tendon pathology.

METHODS

Unilateral ankle scans were acquired for 26 asymptomatic volunteers with a 3-Tesla MRI system using a T2* mapping sequence in the axial and sagittal planes. The peroneus brevis and peroneus longus tendons were manually segmented and subregions were isolated in the proximity of the lateral malleolus. Summary statistics for T2* values were calculated.

RESULTS

The peroneus brevis tendon exhibited a mean T2* value of 12 ms and the peroneus longus tendon was 11 ms. Subregions distal to the lateral malleolus had significantly higher T2* values ( P < .05) than the subregions proximal in both tendons, in both the axial and sagittal planes.

CONCLUSION

Peroneal tendon regions distal to the inferior tip of the lateral malleolus had significantly higher T2* values than those regions proximal, which could be related to anatomical differences along the tendon.

CLINICAL RELEVANCE

This study provides a quantitative method and normative baseline T2* mapping values for comparison with symptomatic clinically compromised peroneal tendon patients.

Predictive Value of 3-T Magnetic Resonance Imaging in Diagnosing Grade 3 and 4 Chondral Lesions in the Hip

PURPOSE

To assess the diagnostic capability and predictive value of 3-T magnetic resonance imaging (MRI) in detecting grade 3 and 4 cartilage lesions in the hip.

METHODS

From August 2010 to April 2015, patients who underwent 3-T MRI and hip arthroscopy were included in the study. Data were prospectively collected and retrospectively reviewed. A radiologist prospectively documented MRI findings, and the surgeon documented cartilage damage at arthroscopy using the Outerbridge grading system. Arthroscopy was considered the diagnostic gold standard. This study was approved by the institutional review board.

RESULTS

The study group comprised 606 patients, with 354 men (58%) and 252 women (42%). The mean patient age was 34 years (range, 18 to 71 years). For femoral head defects, the sensitivity was 61% (95% confidence interval [CI], 53% to 68%), specificity was 58% (95% CI, 55% to 62%), positive predictive value was 29% (95% CI, 25% to 33%), and negative predictive value was 84% (95% CI, 81% to 87%). For chondral defects of the acetabulum, the sensitivity was 80% (95% CI, 75% to 84%), specificity was 41% (95% CI, 38% to 44%), positive predictive value was 42% (95% CI, 39% to 45%), and negative predictive value was 79% (95% CI, 74% to 84%).

CONCLUSIONS

The results of this study showed that 3-T MRI had sensitivity, as well as specificity, for identifying chondral defects that is similar to what has been previously reported. MRI showed increased sensitivity when identifying acetabular defects compared with femoral head defects. With a low positive predictive value, MRI may be most useful in ruling out cartilage lesions.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Prospective In Vivo Comparison of Damaged and Healthy-Appearing Articular Cartilage Specimens in Patients With Femoroacetabular Impingement: Comparison of T2 Mapping, Histologic Endpoints, and Arthroscopic Grading

PURPOSE

To describe T2 mapping values in arthroscopically determined International Cartilage Repair Society (ICRS) grades in damaged and healthy-appearing articular cartilage waste specimens from arthroscopic femoroacetabular impingement (FAI) treatment. Furthermore, we sought to compare ICRS grades of the specimens with biochemical, immunohistochemistry and histologic endpoints and assess correlations with T2 mapping.

METHODS

Twenty-four patients were prospectively enrolled, consecutively, between December 2011 and August 2012. Patients were included if they were aged 18 years or older and met criteria that followed the clinical indications for arthroscopy to treat FAI. Patients with prior hip trauma including fracture or dislocation or who have undergone prior hip surgery were excluded. All patients received a preoperative sagittal T2 mapping scan of the hip joint. Cartilage was graded intraoperatively using the ICRS grading system, and graded specimens were collected as cartilage waste for histologic, biochemical, and immunohistochemistry analysis.

RESULTS

Forty-four cartilage specimens (22 healthy-appearing, 22 damaged) were analyzed. Median T2 values were significantly higher among damaged specimens (55.7 ± 14.9 ms) than healthy-appearing specimens (49.3 ± 12.3 ms; P = .043), which was most exaggerated among mild (grade 1 or 2) defects where the damaged specimens (58.1 ± 16.4 ms) were significantly higher than their paired healthy-appearing specimens (48.7 ± 15.4 ms; P = .026). Severely damaged specimens (grade 3 or 4) had significantly lower cumulative H&E than their paired healthy-appearing counterparts (P = .02) but was not statistically significant among damaged specimens with mild (grade 1 or 2) defects (P = .198). Among healthy-appearing specimens, median T2 and the percentage of collagen fibers oriented parallel were significantly correlated (rho = 0.425, P = .048).

CONCLUSIONS

This study outlines the potential for T2 mapping to identify early cartilage degeneration in patients undergoing arthroscopy to treat FAI. Findings in ICRS grade 1 and 2 degeneration corresponded to an increase in T2 values. Further biochemical evaluation revealed a significant difference between healthy-appearing cartilage and late degeneration in cumulative H&E as well as significantly lower percentage of collagen fibers oriented parallel and a higher percentage of collagen fibers oriented randomly when considering all grades of cartilage damage.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Magnetic resonance imaging characterization of individual ankle syndesmosis structures in asymptomatic and surgically treated cohorts

PURPOSE

Historically, syndesmosis injuries have been underdiagnosed. The purpose of this study was to characterize the 3.0-T MRI presentations of the distal tibiofibular syndesmosis and its individual structures in both asymptomatic and injured cohorts.

METHODS

Ten age-matched asymptomatic volunteers were imaged to characterize the asymptomatic syndesmotic anatomy. A series of 21 consecutive patients with a pre-operative 3.0-T ankle MRI and subsequent arthroscopic evaluation for suspected syndesmotic injury were reviewed and analysed. Prospectively collected pre-operative MRI findings were correlated with arthroscopy to assess diagnostic accuracy [sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)].

RESULTS

Pathology diagnosed on pre-operative MRI correlated strongly with arthroscopic findings. Syndesmotic ligament disruption was prospectively diagnosed on MRI with excellent sensitivity, specificity, PPV, NPV, and accuracy: anterior inferior tibiofibular ligament (87.5, 100, 100, 71.4, 90.5 %); posterior inferior tibiofibular ligament (N/A, 95.2, 0.0, 100, 95.2 %); and interosseous tibiofibular ligament (66.7, 86.7, 66.7, 86.7, 81.0 %).

CONCLUSIONS

Pre-operative 3.0-T MRI demonstrated excellent accuracy in the diagnosis of syndesmotic ligament tears and allowed for the visualization of relevant individual syndesmosis structures. Using a standard clinical ankle MRI protocol at 3.0-T, associated ligament injuries could be readily identified. Clinical implementation of optimal high-field MRI sequences in a standard clinical ankle MRI exam can aid in the diagnosis of syndesmotic injuries, augment pre-operative planning, and facilitate anatomic repair by providing additional details regarding the integrity of individual syndesmotic structures not discernible through physical examination and radiographic assessments.

LEVEL OF EVIDENCE

II.

Quantitative MRI characterization of arthroscopically verified supraspinatus pathology: comparison of tendon tears, tendinosis and asymptomatic supraspinatus tendons with T2 mapping

PURPOSE

Quantitative MRI T2 mapping is a non-invasive imaging technique sensitive to biochemical changes, but no studies have evaluated T2 mapping in pathologic rotator cuff tendons. It was sought to evaluate the efficacy of T2 mapping in detecting differences in the supraspinatus tendon (SST) among patients with tendinosis, partial tears and minimally retracted full-thickness tears, relative to asymptomatic volunteers.

METHODS

The pathologic cohort consisted of two arthroscopically verified groups: tendinosis and a tear group of partial tears or minimally retracted full-thickness tears, and was compared to an asymptomatic cohort with no prior history of shoulder pathology. The SST was manually segmented from the footprint to the medial humeral head in the coronal and sagittal planes and divided into six clinically relevant subregions. Mean T2 values and inter- and intra-rater reliability were assessed.

RESULTS

In the anterolateral subregion, the tear group exhibited significantly higher mean T2 values (43.9 ± 12.7 ms) than the tendinosis (34.9 ± 3.9 ms; p = 0.006) and asymptomatic (33.6 ± 5.3 ms; p = 0.015) groups. In the posterolateral subregion, the tear group had higher mean T2 values (45.2 ± 13.7) than the asymptomatic group (34.7 ± 6.7; p = 0.012). Inter- and intra-rater reliability was mostly excellent (ICC > 0.75).

CONCLUSION

T2 mapping is an accurate non-invasive method to identify quantitatively early rotator cuff pathology. The lateral region in the coronal plane in particular may differentiate partial and small minimally retracted full-thickness tears from tendinosis and asymptomatic tendons. Understanding and being able to measure quantitatively the process of tendon degeneration and subsequent tearing may help clinicians to better predict at-risk groups and to stratify treatment options.

LEVEL OF EVIDENCE

III.

Quantifiable Imaging Biomarkers for Evaluation of the Posterior Cruciate Ligament Using 3-T Magnetic Resonance Imaging: A Feasibility Study

Background:

Quantitative magnetic resonance imaging (MRI) techniques, such as T2 and T2 star (T2*) mapping, have been used to evaluate ligamentous tissue in vitro and to identify significant changes in structural integrity of a healing ligament. These studies lay the foundation for a clinical study that uses quantitative mapping to evaluate ligaments in vivo, particularly the posterior cruciate ligament (PCL). To establish quantitative mapping as a clinical tool for identifying and evaluating chronic or acute PCL injuries, T2 and T2* values first must be determined for an asymptomatic population.

Purpose:

To quantify T2 and T2* mapping properties, including texture variables (entropy, variance, contrast, homogeneity), of the PCL in an asymptomatic population. It was hypothesized that biomarker values would be consistent throughout the ligament, as measured across 3 clinically relevant subregions (proximal, middle, and distal thirds) in the asymptomatic cohort.

Study Design:

Cross-sectional study; Level of evidence, 4.

Methods:

Unilateral knee MRI scans were acquired for 25 asymptomatic subjects with a 3.0-T MRI system using T2 and T2* mapping sequences in the sagittal plane. The PCL was manually segmented and divided into thirds (proximal, middle, and distal). Summary statistics for T2 and T2* values were calculated. Intra- and interrater reliability was assessed across 3 raters to 2 time points.

Results:

The asymptomatic PCL cohort had mean T2 values of 36.7, 29.2, and 29.6 ms in the distal, middle, and proximal regions, respectively. The distal PCL exhibited significantly higher mean, variance, and contrast and lower homogeneity of T2 values than the middle and proximal subregions (P < .05). T2* results exhibited substantial positive skew and were therefore presented as median and quartile (Q) values. Median T2* values were 7.3 ms (Q1-Q3, 6.8-8.9 ms), 7.3 ms (Q1-Q3, 7.0-8.5 ms), and 7.3 ms (Q1-Q3, 6.4-8.2 ms) in the distal, middle, and proximal subregions, respectively.

Conclusion:

This is the first study to identify T2 and T2* mapping values, and their texture variables, for the asymptomatic PCL. The distal third of the PCL had significantly greater T2 values than the proximal or middle thirds.

Clinical Relevance:

T2 and T2* values of the asymptomatic PCL can provide a baseline for comparison with acute and chronic PCL injuries in future studies.

Association between scapula bony morphology and snapping scapula syndrome

HYPOTHESIS AND BACKGROUND

Scapular incongruity has been described as a contributing factor to the development of snapping scapula syndrome (SSS). The purpose of this retrospective case-control study was to determine the association between scapula bony morphology on magnetic resonance imaging (MRI) and the diagnosis of SSS.

METHODS

Bony morphologies of the scapula were evaluated on MRI scans of 26 patients with SSS and 19 patients with non-SSS pathologies. The medial scapula corpus angle (MSCA) was measured on axial MRI sequences. Scapulae were categorized as straight, S shaped, or concave. Two independent observers performed the measurements. Interobserver and intraobserver agreements of MSCA measurements were determined with intraclass correlation coefficients.

RESULTS

Axial scapula bony morphology identified 28 scapulae of the straight type, 14 S-shaped scapulae, and 5 concave scapulae. All 5 concave scapulae had confirmed SSS. Measurement of the MSCA showed excellent interobserver agreement of 0.80 (95% confidence interval [CI], 0.67 to 0.89) and intraobserver agreement of 0.70 (95% CI, 0.52 to 0.82). There were significant differences in the mean MSCAs between shoulders with SSS (14.4° ± 19.3°) and non-SSS shoulders (-3.3° ± 15.3°, P = .001). The odds ratio was 8.4 (95% CI, 2.2 to 31.8) for positive MSCA and SSS. The scapulothoracic distance was significantly decreased in the SSS group (14.9 ± 5.8 mm) compared with the non-SSS patients (24.0 ± 6.7 mm, P < .001).

DISCUSSION AND CONCLUSION

Anterior angulation of the medial scapula in the axial plane was associated with SSS. Patients with a concave-shaped scapula and a positive MSCA have a 12-fold increased risk of SSS. The MSCA may prove helpful in determining the location and amount of scapular resection needed for patients with SSS.

Comparison of T2 Values in the Lateral and Medial Portions of the Weight-Bearing Cartilage of the Hip for Patients With Symptomatic Femoroacetabular Impingement and Asymptomatic Volunteers

PURPOSE

To develop a simplified method to define a clinically relevant subregion in the course of arthroscopic treatment of femoroacetabular impingement (FAI) using T2 mapping in patients and asymptomatic volunteers. Additionally, we sought to compare the lateral and medial subregion values in asymptomatic volunteers and in patients presenting with FAI. Finally, we wanted to investigate possible associations between patients' T2 mapping values and demographic variables-i.e., alpha angle, age, sex, and body mass index (BMI).

METHODS

Twenty-five asymptomatic volunteers and 23 consecutive symptomatic patients with FAI (cam or mixed type) were prospectively enrolled and evaluated with a sagittal T2 mapping sequence. The weight-bearing region of the acetabular and femoral cartilage was manually segmented and divided into medial and lateral subregions. Median T2 values were determined, and patient characteristics were assessed as potential predictors of T2 values.

RESULTS

T2 values in the lateral portion of the acetabulum were lower than in the medial portion for both asymptomatic volunteers (43 v 53 ms; P < .001) and patients with FAI (42 v 49 ms; P = .016). The medial acetabulum (MA) of asymptomatic volunteers had higher T2 values than those of the FAI group (53 v 49 ms; P = .040). The lateral-minus-medial difference was significantly larger among asymptomatic volunteers than in patients with FAI (P = .047). Patients with FAI had higher alpha angles than those of the asymptomatic volunteers, but no other associations with patient characteristics were observed.

CONCLUSIONS

This study's findings suggest that there are differences in cartilage T2 mapping values between medial and lateral weight-bearing aspects of the hip and may expand the application and usefulness of biochemical magnetic resonance imaging (MRI) techniques, specifically T2 mapping, in the diagnosis of hip cartilage damage with the evaluation of clinically relevant subregions. When comparing asymptomatic volunteers and patients with FAI presenting with cam or mixed type deformity, we observed a significant contrast between the T2 mapping values of the lateral and medial portions of the weight-bearing zone of the acetabular cartilage, whereas such contrast was not observed when zone 3 was analyzed as a whole.

LEVEL OF EVIDENCE

Level III, development of diagnostic criteria on the basis of consecutive patients with a universally applied reference gold standard.

Diagnostic accuracy of 3.0 Tesla magnetic resonance imaging for the detection of articular cartilage lesions of the talus

BACKGROUND

Talar chondral defects can be a source of persistent ankle pain and disability. If untreated, there is an increased risk of osteoarthritis. The purpose of our study was to determine diagnostic accuracy of 3T MRI in detecting Outerbridge grades 3 and 4 articular cartilage lesions of the talus in a clinical setting, utilizing a standardized clinical MRI protocol.

METHODS

Patients who had a 3T ankle MRI and subsequent ankle surgery, by a single surgeon, were included in this study. MRI exams were performed 180 days or less before surgery. Seventy-nine ankles in 78 patients (mean age of 42.3 years) were included in this study. Mean body mass index was 26.3. A standard clinical MRI exam was performed on a 3T MRI scanner. Mean days from MRI to surgery was 39 days. All MRI exams were read and findings recorded by a musculoskeletal radiologist. Arthroscopic examination was performed by a single orthopaedic surgeon. Detailed arthroscopic findings and demographic data were collected prospectively and stored in a data registry. Of the 78 patients, 31 (39.2%) reported previous ankle surgery. Pain was the primary reason for seeking medical attention as reported by 95% of patients, followed by instability in 44% and loss of function with 42%.

RESULTS

Prevalence of Outerbridge grade 3 and 4 talar articular cartilage defects identified at arthroscopy was 17.7%. The 3T MRI demonstrated a sensitivity of 0.714, specificity of 0.738, positive predictive value of 0.370, and negative predictive value of 0.923.

CONCLUSION

Sensitivity and specificity levels were acceptable for detection of grades 3 and 4 articular cartilage defects of the talar dome using 3T MRI. The high negative predictive value may be beneficial in preoperative planning. While these values are acceptable, a high index of suspicion should be maintained in the appropriate clinical setting.

Patient-centered outcomes after hip arthroscopy for femoroacetabular impingement and labral tears are not different in patients with normal, high, or low femoral version

PURPOSE

The purpose of this study was to determine whether outcomes after hip arthroscopy were different based on femoral version.

METHODS

The inclusion criteria were diagnosis of femoroacetabular impingement (FAI) based on clinical examination and/or imaging findings and preoperative measurement of femoral version by magnetic resonance imaging. For this study, the definition of FAI was a positive impingement sign, a positive flexion-abduction-external rotation examination finding, or radiographic signs of impingement. A query of a prospective data registry identified 180 patients who matched the inclusion and exclusion criteria. Group 1 had version of less than 5° (n = 48), group 2 had version of 5° to 15° (n = 84), and group 3 had version greater than 15° (n = 48). The mean age of the patients was 35 years (range, 18 to 61 years).

RESULTS

On radiographic examination, the mean alpha angle for all patients' injured hips was 63° (range, 42° to 88°). The mean center-edge angle was 30° (range, 20° to 43°), and mean femoral version was 9.9° (range, -16° to 29°). There was no significant difference in age, alpha angle, or center-edge angle among the 3 version groups. A significant difference in psoas release procedures (psoas impingement) was seen with increasing femoral version. The mean follow-up period was 30 months (range, 18 to 47 months). Patient-reported functional outcomes were not statistically different among the groups.

CONCLUSIONS

Patient-reported functional outcomes after hip arthroscopy for labral tears and FAI were not different based on femoral version in this population. Although some differences were observed regarding intraoperative findings, these also did not result in differences in patient outcomes reported at a mean follow-up of 2 years.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Systematic technique-dependent differences in CT versus MRI measurement of the tibial tubercle-trochlear groove distance

BACKGROUND

The tibial tubercle-trochlear groove (TTTG) distance is used to quantify the degree of lateralization of the patellar tendon insertion on the tibial tubercle relative to the deepest part of the trochlear groove. Disagreement exists as to whether the TTTG distance measured on computed tomography (CT) and magnetic resonance imaging (MRI) can be considered equivalent.

PURPOSE

To compare TTTG distance as measured on axial CT and MRI and to investigate the potential effect of patient positioning between modalities.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Patients who received both CT and MRI of the same knee for any indication from August 2010 to April 2014 were included in this study. The TTTG distances were measured twice by 2 raters in a randomized order, with at least 30 days between ratings to minimize recall bias. Inter- and intrarater reliability of CT and MRI measurements and intermethod reliability were assessed with intraclass correlation coefficients (ICCs). Bland-Altman plots were also created to assess agreement. Differences in patient positioning were investigated to determine its effect on the TTTG distance.

RESULTS

Fifty-nine patients (age, 32.8 ± 12.9 years) were included. Interrater ICCs were excellent for both CT and MRI measurements. Intrarater ICCs were excellent for both raters. Absolute agreement ICCs for intermethod reliability were fair to good, but consistency type agreement was excellent. A systematic bias of lower MRI distances (bias = -2.8 mm) compared with CT was observed. The investigation of CT versus MRI imaging techniques demonstrated that the standard MRI examination places the knee in approximately 4.6° of relative varus alignment compared with CT.

CONCLUSION

A systematic bias toward lower TTTG distances on MRI compared with CT was found. This finding is likely dependent on imaging technique, including patient positioning. Patient knees were positioned in varus on the MRI compared with the CT examination, with resulting lower TTTG distances on MRI compared with CT. The TTTG distances on CT and MRI vary with imaging technique, which may be attributable to patient positioning and result in differences among imaging centers.

Diagnostic accuracy of 3.0 T magnetic resonance imaging for the detection of meniscus posterior root pathology

PURPOSE

The purpose of this study was to determine the diagnostic accuracy of 3 T MRI, including sensitivity, specificity, negative and positive predictive values, for detection of posterior medial and lateral meniscus root tears and avulsions.

METHODS

All patients who had a 3 T MRI of the knee, followed by arthroscopic surgery, were included in this study. Arthroscopy was considered the gold standard. Meniscus root tears diagnosed at arthroscopy and on MRI were defined as a complete meniscus root detachment within 9 mm of the root. All surgical data were collected prospectively and stored in a data registry. MRI exams were reported prospectively by a musculoskeletal radiologist and reviewed retrospectively.

RESULTS

There were 287 consecutive patients (156 males, 131 females; mean age 41.7 years) in this study. Prevalence of meniscus posterior root tears identified at arthroscopy was 9.1, 5.9% for medial and 3.5% for lateral root tears (one patient had both). Sensitivity was 0.770 (95% CI 0.570, 0.901), specificity was 0.729 (95% CI 0.708, 0.741), positive predictive value was 0.220 (95% CI 0.163, 0.257) and negative predictive value was 0.970 (95% CI 0.943, 0.987). For medial root tears, sensitivity was 0.824 (95% CI 0.569, 0.953), specificity was 0.800 (95% CI 0.784, 0.808), positive predictive value was 0.206 (95% CI 0.142, 0.238) and negative predictive value was 0.986 (95% CI 0.967, 0.996). For lateral meniscus posterior root tears, sensitivity was 0.600 (95% CI 0.281, 0.860), specificity was 0.903 (95% CI 0.891, 0.912), positive predictive value was 0.181 (95% CI 0.085, 0.261) and negative predictive value was 0.984 (95% CI 0.972, 0.994).

CONCLUSIONS

This study demonstrated moderate sensitivity and specificity of 3 T MRI to detect posterior meniscus root tears. The negative predictive value of 3 T MRI to detect posterior meniscus root tears was high; however, the positive predictive value was low. Sensitivity was higher for medial root tears, indicating a higher risk of missing lateral root tears on MRI. Imaging has an important role in identifying meniscus posterior horn root tears; however, some root tears may not be identified until arthroscopy.

LEVEL OF EVIDENCE

Prognostic study (diagnostic), Level II.

Subregional Anatomical Distribution of T2 Values of Articular Cartilage in Asymptomatic Hips

OBJECTIVE

A standardized definition of normative T2 values across the articular surface of the hip must be defined in order to fully understand T2 values for detecting early degeneration. Therefore, in this article, we seek to lay foundational methodology for reproducible quantitative evaluation of hip cartilage damage using T2 mapping to determine the normative T2 values in asymptomatic individuals.

DESIGN

Nineteen prospectively enrolled asymptomatic volunteers (age 18-35 years, males 10, females 9, alpha angle 49.3º ± 7.2º) were evaluated with a sagittal T2 mapping sequence at 3.0 T magnetic resonance imaging. Acetabular and femoral cartilage was manually segmented directly on the second echo of the T2 mapping sequence by 3 raters, twice. Segmentations were divided into 12 subregions modified from the geographic zone method. Median T2 values within each subregion were compiled for further analysis and interrater and intrarater reliability was assessed.

RESULTS

In the femur, the posterior-superior subregion was significantly higher (P ≤ 0.05) than those in the posterior-inferior and anterior-inferior subregions. In the acetabulum, the anterior-inferior subregion was significantly higher (P ≤ 0.001) than in the anterior-superior, middle, and posterior-inferior subregions. T2 values of the posterior-superior subregion were significantly higher (P ≤ 0.05) than the anterior-superior, middle, and posterior-inferior subregions. Interrater agreement was generally fair to good.

Quantitative MRI in the evaluation of articular cartilage health: reproducibility and variability with a focus on T2 mapping

PURPOSE

Early diagnosis of cartilage degeneration and longitudinal tracking of cartilage health including repair following surgical intervention would benefit from the ability to detect and monitor changes of the articular cartilage non-invasively and before gross morphological alterations appear.

METHODS

Quantitative MR imaging has shown promising results with various imaging biomarkers such as T2 mapping, T1 rho and dGEMRIC demonstrating sensitivity in the detection of biochemical alterations within tissues of interest. However, acquiring accurate and clinically valuable quantitative data has proven challenging, and the reproducibility of the quantitative mapping technique and its values are essential. Although T2 mapping has been the focus in this discussion, all quantitative mapping techniques are subject to the same issues including variability in the imaging protocol, unloading and exercise, analysis, scanner and coil, calculation methods, and segmentation and registration concerns.

RESULTS

The causes for variability between time points longitudinally in a patient, among patients, and among centres need to be understood further and the issues addressed.

CONCLUSIONS

The potential clinical applications of quantitative mapping are vast, but, before the clinical community can take full advantage of this tool, it must be automated, standardized, validated, and have proven reproducibility prior to its implementation into the standard clinical care routine.

Preoperative diagnosis of pathologic conditions of the ligamentum teres: is MRI a valuable imaging modality?

PURPOSE

The purpose of this study was to determine the accuracy of 3-Tesla magnetic resonance imaging (MRI) in detecting ligamentum teres (LT) lesions in patients before they undergo hip arthroscopy for the treatment of femoroacetabular impingement.

METHODS

From 2010 to 2011, data were prospectively collected on all patients presenting for treatment of hip pain. All patients underwent MRI followed by arthroscopic surgery. A radiologist prospectively documented MRI findings, and the surgeon recorded the findings at arthroscopy. Radiologic and surgical data included classification of the LT as not torn, hypertrophic, partially torn, or completely torn. All MR images were read by a single radiologist, and all surgery was performed by a single surgeon. Arthroscopy was considered the diagnostic gold standard.

RESULTS

One hundred forty-two patients with a mean patient age of 35 years (range, 19 to 73 years) met the inclusion criteria. Only one complete LT tear was found in the study. The accuracy of MRI for the diagnosis of LT partial tears was 64%. The sensitivity and specificity of MRI for diagnosing partial tears of the LT were 9% and 91%, [corrected] respectively. The positive predictive value and negative predictive value were 31% and 67%, [corrected] respectively. The sensitivity and specificity of MRI for diagnosing hypertrophic LT were 32% and 78%, respectively.

CONCLUSIONS

In this patient population, MRI demonstrated sensitivity and specificity of 34% and 50%, [corrected] respectively, in identifying any pathologic process of the LT. MRI is capable of ruling out [corrected] partial tears of the LT with high sensitivity (91%) and negative [corrected] predictive value (67%).

LEVEL OF EVIDENCE

Level II, development of diagnostic criteria on basis of consecutive patients with universally applied gold standard.

Automatic model-based semantic registration of multimodal MRI knee data

PURPOSE

To propose a robust and automated model-based semantic registration for the multimodal alignment of the knee bone and cartilage from three-dimensional (3D) MR image data.

MATERIALS AND METHODS

The movement of the knee joint can be semantically interpreted as a combination of movements of each bone. A semantic registration of the knee joint was implemented by separately reconstructing the rigid movements of the three bones. The proposed method was validated by registering 3D morphological MR datasets of 25 subjects into the corresponding T2 map datasets, and was compared with rigid and elastic methods using two criteria: the spatial overlap of the manually segmented cartilage and the distance between the same landmarks in the reference and target datasets.

RESULTS

The mean Dice Similarity Coefficient (DSC) of the overlapped cartilage segmentation was increased to 0.68 ± 0.1 (mean ± SD) and the landmark distance was reduced to 1.3 ± 0.3 mm after the proposed registration method. Both metrics were statistically superior to using rigid (DSC: 0.59 ± 0.12; landmark distance: 2.1 ± 0.4 mm) and elastic (DSC: 0.64 ± 0.11; landmark distance: 1.5 ± 0.5 mm) registrations.

CONCLUSION

The proposed method is an efficient and robust approach for the automated registration between morphological knee datasets and T2 MRI relaxation maps.

MRI T2 mapping of the asymptomatic supraspinatus tendon by age and imaging plane using clinically relevant subregions

PURPOSE

Diagnosis of partial rotator cuff tears and tendonopathy using conventional MRI has proven variable. Quantitative T2 mapping may have application for assessing rotator cuff health. In order to evaluate the usefulness of T2 mapping for the rotator cuff, methods must be refined for mapping the supraspinatus tendon, and normative T2 values must first be acquired.

MATERIALS AND METHODS

This study was IRB approved. Thirty asymptomatic volunteers (age: 18-62) were evaluated with sagittal and coronal T2 mapping sequences. Manual segmentation of tendon and muscle as a unit and tendon alone was performed twice by two independent raters. Segmentations were divided into medial, middle and lateral subregions and mean T2 values calculated.

RESULTS

Anatomic comparison of mean T2 values illustrated highest values in the medial region, lowest values in the lateral region, and intermediate values for the middle region upon coronal segmentation (p<0.001). In sagittal segmentations, there were higher values in the medial region and no significant differences between the lateral and middle subregions. No significant differences were found with comparison across age groups. Inter and intra-rater segmentation repeatability was excellent, with coefficients ranging from 0.85 to 0.99.

CONCLUSION

T2 mapping illustrated anatomic variation along the supraspinatus muscle-tendon unit with low standard deviations and excellent repeatability, suggesting that changes in structure due to degeneration or changes associated with healing after repair may be detectable.

Magnetic resonance imaging findings of snowboarding osteochondral injuries to the middle talocalcaneal articulation

This report presents 2 cases of subtle injuries to the subtalar joint, specifically, osteochondral defects of the middle facet of the talus and concomitant involvement of the middle talocalcaneal articulation sustained while snowboarding. The 3T magnetic resonance image revealed fracture of the lateral talar process with osteochondral lesions of the middle talocalcaneal articulation. This injury can lead to severe and chronic disability if undetected and could ultimately end athletic participation prematurely.

Clinically Relevant Subregions of Articular Cartilage of the Hip for Analysis and Reporting Quantitative Magnetic Resonance Imaging: A Technical Note

OBJECTIVE

Before quantitative imaging techniques can become clinically valuable, the method, and more specifically, the regions of locating and reporting these values should be standardized toward reproducibility comparisons across centers and longitudinal follow-up of individual patients. The purpose of this technical note is to describe a rigorous and reproducible method of locating, analyzing, and reporting quantitative MRI values in hip articular cartilage with an approach that is consistent with current orthopedic literature.

DESIGN

To demonstrate this localization and documentation, 3 patients (age, 23 ± 5.1 years; 2 males, 1 female) who presented with symptomatic mixed-type femoroacetabular impingement (α angle, 63.3° ± 2.1°; center edge angle, 39° ± 4.2°) were evaluated with T2-mapping at 3 T MRI prior to hip arthroscopy. Manual segmentation was performed and cartilage of the acetabulum and femur was divided into 12 subregions adapted from the geographic zone method. Bone landmarks in the acetabulum and femur, identifiable both in arthroscopy and MR images, were manually selected and the coordinates exported for division of cartilage.

RESULTS

Mean T2 values in each zone are presented.

CONCLUSIONS

The current work outlines a standardized system to locate and describe quantitative mapping values that could aid in surgical decision making, planning, and the noninvasive longitudinal follow-up of implemented cartilage preservation and restoration techniques.

Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players

BACKGROUND

It has been reported that relative to other sports participants, ice hockey players suffer from cam-type femoroacetabular impingement (FAI) in higher numbers. α angles have been reported to increase with the likelihood of symptomatic FAI. It is unclear how prevalent increased α angles, commonly associated with cam FAI, are in asymptomatic young ice hockey players.

HYPOTHESIS

There would be a higher prevalence of α angles associated with cam FAI in youth ice hockey players than in a non-hockey-playing (skier) youth control group.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 61 asymptomatic youth ice hockey players (aged 10-18 years) and 27 youth skiers (controls) (aged 10-18 years) underwent a clinical hip examination consisting of the flexion/abduction/external rotation (FABER) distance test, impingement testing, and measurement of hip internal rotation. The hip α angle was measured by magnetic resonance imaging, and labral tears and articular cartilage lesions were documented. Hockey players were grouped according to their USA Hockey classification as peewees (ages 10-12 years), bantams (ages 13-15 years), and midgets (ages 16-19 years).

RESULTS

Overall, ice hockey players had significantly higher α angles than did the control group, and hockey players had a significant correlation between increased age and increased α angles, while the control group did not. In the ice hockey group, 75% had an α angle of ≥55°, while in the skier group, 42% had an α angle of ≥55° (P < .006). Hockey players were 4.5 times more likely to have an α angle commonly associated with cam impingement than skiers. Midget players had the highest risk of increased α angles.

CONCLUSION

Even at young ages, ice hockey players have a greater prevalence of α angles associated with cam FAI than do skier-matched controls. Properties inherent to ice hockey likely enhance the development of a bony overgrowth on the femoral neck, leading to cam FAI.

Relationship between femoral anteversion and findings in hips with femoroacetabular impingement

The purpose of this study was to investigate the relationship between femoral neck version and pre- and intraoperative findings in hips with femoroacetabular impingement (FAI). The authors retrospectively reviewed prospectively collected data on 188 patients (204 hips) who underwent hip arthroscopy for FAI and labral pathology. Femoral version was measured on magnetic resonance imaging by a fellowship-trained musculoskeletal radiologist. The study group comprised 100 men and 88 women with a mean age of 35 years (range, 18 to 62 years). Mean femoral version was 9° (range, -10° to 27°). No relationship was found between femoral version and patient demographics (ie, age, sex, weight, height, and body mass index). A significant correlation was found between version and degrees of external rotation (r=-0.208; P=.027) and internal rotation (r=0.231; P=.002) on physical examination. Patients with femoral version less than 5° had significantly increased external rotation (P=.027). Intraoperative findings demonstrated that femoral version greater than 15° was related to larger labral tears that averaged approximately 38 mm in size, whereas patients with anteversion less than 5° had tear sizes measuring 30 mm and patients with angles between 5° and 15° had tear sizes averaging 34 mm (P=.008). Hips with femoral version greater than 15° were 2.2 times more likely (95% confidence interval, 1.2 to 4.1) to have labral tears that extended beyond the 3 o'clock position, denoting more anterior tears. Hips in which a psoas release was performed had higher version angles (8° vs 11°; P=.023).

Prevalence of abnormal hip findings in asymptomatic participants: a prospective, blinded study

BACKGROUND

The prevalence of abnormal magnetic resonance imaging (MRI) findings in an asymptomatic population has yet to be determined.

PURPOSE

The purpose of this study was to assess a cohort of asymptomatic people to determine the prevalence of hip lesions.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Forty-five volunteers with no history of hip pain, symptoms, injury, or surgery were recruited for enrollment in this institutional review board-approved study. The subjects underwent a unilateral MRI scan with a Siemens 3.0-tesla scanner. The extremity side evaluated by MRI was alternated. All MRI scans were reviewed by 3 fellowship-trained musculoskeletal radiologists. The scans were mixed randomly with 19 scans from symptomatic patients to blind the radiologists to the possibility of patient symptoms. An abnormal finding was considered positive when 2 of 3 radiologists agreed on its presence.

RESULTS

The average age of volunteers was 37.8 years (range, 15-66 y); 60% were men. Labral tears were identified in 69% of hips, chondral defects in 24%, ligamentum teres tears in 2.2%, labral/paralabral cysts in 13%, acetabular bone edema in 11%, fibrocystic changes of the head/neck junction in 22%, rim fractures in 11%, subchondral cysts in 16%, and osseous bumps in 20%. Participants older than 35 years were 13.7 times (95% CI, 2.4-80 times) more likely to have a chondral defect and 16.7 times (95% CI, 1.8-158 times) more likely to have a subchondral cyst compared with participants 35 or younger. No other joint lesions were associated with age. Male subjects were 8.5 times (95% CI, 1.2-56 times) more likely to have an osseous bump than female subjects. No other joint lesions were associated with sex.

CONCLUSION

Magnetic resonance images of asymptomatic participants revealed abnormalities in 73% of hips, with labral tears being identified in 69% of the joints. A strong correlation was seen between participant age and early markers of cartilage degeneration such as cartilage defects and subchondral cysts.

The effect of sequence selection and field strength on detection of osteochondral defects in the metacarpophalangeal joint

Six cadaver forelimbs were imaged in two high-field magnetic resonance (MR) systems and one low-field MR system following the creation of osteochondral defects on the palmar distal aspect of the third metacarpal bone. The following sequences were performed using all three systems: proton density (PD) turbo spin echo, T2* gradient echo (GRE), T2-weighted fast spin echo, and short tau inversion recovery. In addition, 3D T1 GRE sagittal standard and motion insensitive sequences were obtained using the low-field system. PD fat saturated and 3D T1-weighted spoiled GRE images with and without fat suppression were acquired with the high-field systems. Lesions were measured and assigned a confidence score. The images obtained using high-field systems (1.0 and 1.5 T) more accurately represented the osteochondral defects when compared with low-field system (0.27 T) images. The largest difference was observed when evaluating articular cartilage defects, which were not identified on the low-field images. Sequence selection affected the appearance of the lesions. On all systems the turbo and fast spin echo sequences more accurately represented the lesion size and shape when compared with the GRE sequences. The T1 GRE sequence is the only sequence that appears to allow visualization of the articular cartilage on the low-field images, but is limited in providing adequate cartilage visualization. Confidence scores were greater on the high-field systems when compared with the low-field system.

Elucidating the process of co-composting of biosolids and spent activated clay

This study elucidates the co-composting of biosolids and spent activated clay (SAC) using physio-chemical, bioassay, and spectroscopic methods. A pilot-scale pile of blended limed biosolids, SAC, and rice husk was composted for 15weeks. The changes in temperature, pH, Fourier-transform infrared (FT-IR) spectra, C/N, and germination index (GI) of Chinese cabbage (Brassica chinensis) seeds with time support the goal of producing a mature compost with a decline in the SAC acidity of associated with biosolids. Cadmium, Cr, Cu, Ni, and Pb in the initial biosolids were converted from labile fractions into relatively immobile phases upon maturation. Temperature, moisture, pH, C/N, and GI were used to separate the composting process into three phases - initial, thermophilic, and cooling, based on a score plot of principal component analysis (PCA). The values of the parameters of interest reveal that the compost fulfills the requirements of compost maturity in the literature.

Magnetic resonance imaging findings in horses with recent onset navicular syndrome but without radiographic abnormalities

Seventy-two horses with recent onset of navicular syndrome and normal radiographs were assessed. Horses underwent magnetic resonance (MR) imaging of both front feet. All abnormalities were characterized and the most severe abnormality identified, if possible. Abnormal signal intensity in the navicular bone was the most severe abnormality in 24 (33%) horses. Pathologic change in the deep digital flexor tendon was the most severe abnormality in 13 (18%) horses. Pathologic change in the collateral sesamoidean ligament was the most severe abnormality in 11 (15%) horses. Pathologic change in the distal sesamoidean impar ligament was the most severe abnormality in seven (10%) horses. Multiple abnormalities were observed in 13 (18%) horses in which an abnormality that was more severe than the others could not be determined. Abnormalities were not observed in the navicular bone or its supporting soft tissues in four (5%) horses. Fifty-six horses had abnormalities that were most severe in one limb; in 52 (93%) horses, the most severe abnormalities were in the foot of the most lame limb. In 7% (4/56) of horses, the most severe findings were in the opposite limb, and in 16 horses, the findings on both limbs were similar. MR imaging is a useful technique for evaluating horses with navicular syndrome and can differentiate between multiple abnormalities. This provides a more specific diagnosis which affects further treatment of the horse. Pathologic changes in different locations in the foot can cause similar clinical signs that, before MR imaging, were categorized as one syndrome.