Quantitative magnetic resonance imaging and histological hoof wall assessment of 3-year-old Quarter Horses.

BACKGROUND: Few noninvasive methods are available for equine hoof wall evaluation. The highly organised wall structures and composition of proteoglycans and collagens may make this region amenable to quantitative MRI (qMRI) techniques of T1ρ and T2 mapping to identify pathology related to proteoglycan content and collagen organisation respectively. OBJECTIVE: To establish normative T1ρ and T2 values of the equine hoof wall of 3-year-old Quarter Horses with histological comparison. STUDY DESIGN: Cadaveric anatomical study. METHODS: Six cadaveric left thoracic feet from 3-year-old racing Quarter Horses with no reported lameness were evaluated using T1ρ and T2 mapping. Mapping was performed at six regions of interest at the toe of each hoof including proximal and distal regions of the inner epidermis, stratum lamellatum and corium. Histology was evaluated for standard hoof morphology and proteoglycan staining. RESULTS: T2 values of the stratum lamellatum and corium were similar (42.9 [95% CI: 41.6-44.2] ms and 44 [95% CI: 42.7-45.3] ms respectively), but both were significantly different to the inner epidermis (35.8 [95% CI: 34.5-37.1] ms, P<0.001). T1ρ values for the inner epidermis, stratum lamellatum and corium were significantly different (25.1 [95% CI: 23.1-27.1] ms, 44.4 [95% CI: 42.4-46.4] ms and 50.1 [95% CI: 48.1-52.1] ms, respectively, P<0.001). Histology demonstrated normal organised morphology. Proteoglycan staining was only visible in the stratum lamellatum and corium. MAIN LIMITATIONS: Cadaveric study with frozen samples used. CONCLUSIONS: Variation of qMRI metrics through the depth of the equine hoof wall was found. Although the highly ordered environment of collagen may contribute to T2 values, there was lack of evidence to support proteoglycan content as a major contributor of T1ρ values. It is possible T1ρ values had a greater dependence on total water content as the lowest values were seen in the epidermis. Additional research using qMRI is needed to determine mapping values in different disease states.

Poly(I:C) source, molecular weight and endotoxin contamination affect dam and prenatal outcomes, implications for models of maternal immune activation.

The viral mimetic polyinosinic:polycytidylic acid (poly(I:C)) is increasingly used to induce maternal immune activation (mIA) to model neurodevelopmental disorders (NDDs). Robust and reproducible phenotypes across studies are essential for the generation of models that will enhance our understanding of NDDs and enable the development of improved therapeutic strategies. However, differences in mIA-induced phenotypes using poly(I:C) have been widely observed, and this has prompted the reporting of useful and much needed methodological guidelines. Here, we perform a detailed investigation of molecular weight and endotoxin variations in poly(I:C) procured from two of the most commonly used suppliers, Sigma and InvivoGen. We demonstrate that endotoxin contamination and molecular weight differences in poly(I:C) composition lead to considerable variability in maternal IL-6 response in rats treated on gestational day (GD)15 and impact on fetal outcomes. Specifically, both endotoxin contamination and molecular weight predicted reductions in litter size on GD21. Further, molecular weight predicted a reduction in placental weight at GD21. While fetal body weight at GD21 was not affected by poly(I:C) treatment, male fetal brain weight was significantly reduced by poly(I:C), dependent on supplier. Our data are in agreement with recent reports of the importance of poly(I:C) molecular weight, and extend this work to demonstrate a key role of endotoxin on relevant phenotypic outcomes. We recommend that the source and batch numbers of poly(I:C) used should always be stated and that molecular weight variability and endotoxin contamination should be minimised for more robust mIA modelling.

Does collagenase injection disrupt or digest the Dupuytren's cord: a magnetic resonance imaging study.

UNLABELLED: Collagenase clostridium histolyticum has been extensively studied as a treatment modality for Dupuytren's contracture. Its mechanism of action has been documented. It is unknown whether injected collagenase weakens the Dupuytren's cord sufficiently to cause failure during manipulation or if there is digestion and reduction in cord volume. We examined five patients with isolated contractures of the ring or middle metacarpalphalangeal (MP) joint using magnetic resonance imaging (MRI) prior to injection with collagenase and again 1 month following injection. All patients had full correction after manipulation which was maintained at follow-up. The Dupuytren's cord was evaluated with respect to volume, signal intensity, inflammatory changes and continuity. Additionally, signal intensity changes of the flexor tendons and neurovascular structures were recorded. MRI demonstrated cord discontinuity, significant reduction of cord volume and a significant increase in cord signal intensity after treatment with collagenase. There was a slight increase in flexor tendon signal intensity that was not significant. These findings suggest that there may be local chemical dissolution of the cord. Future studies may establish whether or not this will have prognostic implications in terms of correction and recurrence following collagenase injection. LEVEL OF EVIDENCE: IV.

Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.

REASONS FOR PERFORMING STUDY: Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants. OBJECTIVES: To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences. STUDY DESIGN: Nonrandomised in vitro experiment. METHODS: MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively. RESULTS: Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE. CONCLUSION: MAVRIC and WBW FSE are feasible additions to minimise artefact around implants.

OARSI Clinical Trials Recommendations: Hip imaging in clinical trials in osteoarthritis.

Imaging of hip in osteoarthritis (OA) has seen considerable progress in the past decade, with the introduction of new techniques that may be more sensitive to structural disease changes. The purpose of this expert opinion, consensus driven recommendation is to provide detail on how to apply hip imaging in disease modifying clinical trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, artifacts associated with various MRI sequences); quality assurance/control procedures; measurement methods; measurement performance (reliability, responsiveness, and validity); recommendations for trials; and research recommendations.

Correlation of meniscal T2* with multiphoton microscopy, and change of articular cartilage T2 in an ovine model of meniscal repair.

OBJECTIVE: To correlate meniscal T2* relaxation times using ultra-short echo time (UTE) magnetic resonance imaging (MRI) with quantitative microscopic methods, and to determine the effect of meniscal repair on post-operative cartilage T2 values. DESIGN: A medial meniscal tear was created and repaired in the anterior horn of one limb of 28 crossbred mature ewes. MR scans for morphological evaluation, meniscal T2* values, and cartilage T2 values were acquired at 0, 4 and 8 months post-operatively for the Tear and Non-Op limb. Samples of menisci from both limbs were analyzed using multiphoton microscopy (MPM) analysis and biomechanical testing. RESULTS: Significantly prolonged meniscal T2* values were found in repaired limbs than in control limbs, P < 0.0001. No regional differences of T2* were detected for either the repaired or control limbs in the anterior horn. Repaired limbs had prolonged cartilage T2 values, primarily anteriorly, and tended to have lower biomechanical force to failure at 8 months than Non-Op limbs. MPM autofluorescence and second harmonic generation data correlated with T2* values at 8 months (ρ = -0.48, P = 0.06). CONCLUSIONS: T2* mapping is sensitive to detecting temporal and zonal differences of meniscal structure and composition. Meniscal MPM and cartilage T2 values indicate changes in tissue integrity in the presence of meniscal repair.

MRI evaluation of rotational alignment and synovitis in patients with pain after total knee replacement.

Component malalignment can be associated with pain following total knee replacement (TKR). Using MRI, we reviewed 50 patients with painful TKRs and compared them with a group of 16 asymptomatic controls to determine the feasibility of using MRI in evaluating the rotational alignment of the components. Using the additional soft-tissue detail provided by this modality, we also evaluated the extent of synovitis within these two groups. Angular measurements were based on the femoral transepicondylar axis and tibial tubercle. Between two observers, there was very high interobserver agreement in the measurements of all values. Patients with painful TKRs demonstrated statistically significant relative internal rotation of the femoral component (p = 0.030). There was relative internal rotation of the tibial to femoral component and combined excessive internal rotation of the components in symptomatic knees, although these results were significant only with one of the observers (p = 0.031). There was a statistically significant association between the presence and severity of synovitis and painful TKR (p < 0.001). MRI is an effective modality in evaluating component rotational alignment.

Imaging near metal with a MAVRIC-SEMAC hybrid.

The recently developed multi-acquisition with variable resonance image combination (MAVRIC) and slice-encoding metal artifact correction (SEMAC) techniques can significantly reduce image artifacts commonly encountered near embedded metal hardware. These artifact reductions are enabled by applying alternative spectral and spatial-encoding schemes to conventional spin-echo imaging techniques. Here, the MAVRIC and SEMAC concepts are connected and discussed. The development of a hybrid technique that utilizes strengths of both methods is then introduced. The presented technique is shown capable of producing minimal artifact, high-resolution images near total joint replacements in a clinical setting.

Local cytokine profiles in knee osteoarthritis: elevated synovial fluid interleukin-15 differentiates early from end-stage disease.

OBJECTIVE: Much of what is known about the inflammatory response in the synovial membrane (SM) of patients with osteoarthritis (OA) comes from studies of synovial tissues from end-stage disease. In this study, we sought to better characterize the inflammatory infiltrate in symptomatic patients with early signs of knee OA, and to determine how inflammatory cell populations relate to the pattern of cytokine and degradative enzyme production. METHODS: Study populations comprised patients with degenerative meniscal tears and early cartilage thinning undergoing arthroscopic procedures (early OA) and patients undergoing total knee replacement for end-stage OA. Quantitative real-time polymerase chain reaction (PCR) was used to measure expression of SM cytokines and enzymes implicated in the pathogenesis of inflammatory arthritis and OA, as well as cell lineage-specific markers. We quantified synovial fluid (SF) cytokines and enzymes by enzyme-linked immunosorbent assay (ELISA) and SM cell populations by immunohistochemistry. RESULTS: We found increased levels of SF interleukin-15 (IL-15) protein in the early knee OA patients when compared to end-stage OA. Both SF IL-15 protein and numbers of CD8 cells within SM correlated with matrix metalloproteinase-1 (MMP-1) and three levels. TNF-alpha, IL-6 and IL-21 were also detectable in the SF of the majority of patients, and IL-15 levels were associated with IL-6 levels. CONCLUSION: IL-15 is elevated in early knee OA, suggesting activation of an innate immune response in the SM. The association of IL-15 expression with CD8 transcripts and MMPs implicates this cytokine in OA pathogenesis and as a candidate therapeutic target.

Augmentation of tendon healing in an intraarticular bone tunnel with use of a bone growth factor.

We hypothesized that an exogenous bone growth factor could augment healing of a tendon graft in a bone tunnel in a rabbit anterior cruciate ligament-reconstruction model. Seventy rabbits underwent bilateral anterior cruciate ligament reconstructions with a semitendinosus tendon graft. One limb received a collagen sponge carrier vehicle containing a mixture of bone-derived proteins while the contralateral limb was treated with either no sponge or a sponge without bone-derived proteins. The reconstruction was evaluated at 2, 4, or 8 weeks with histologic, biomechanical, and magnetic resonance imaging analysis. Histologic analysis demonstrated that specimens treated with bone-derived proteins had a more consistent, dense interface tissue and closer apposition of new bone to the graft, with occasional formation of a fibrocartilaginous interface, when compared with control specimens. The treated specimens had significantly higher load-to-failure rates than did control specimens. Treatment with bone-derived proteins resulted in an average increase in tensile strength of 65%. The treated specimens were stronger than control specimens at each time point, but the difference was greatest at 8 weeks. On the basis of signal characteristics and new bone formation, magnetic resonance imaging was useful for predicting which limb was treated, the site of failure, and the limbs with higher load-to-failure values. This study demonstrates the potential for augmenting tendon healing in an intraarticular bone tunnel using an osteoinductive growth factor.

The relationship of the femoral origin of the anterior cruciate ligament and the distal femoral physeal plate in the skeletally immature knee. An anatomic study.

We defined the anatomic relationship of the anterior cruciate ligament femoral origin to the distal femoral physis in the skeletally immature knee with use of 12 fresh-frozen human fetal specimens (ages, 20 to 36 weeks). Each specimen underwent magnetic resonance imaging, was dissected free of soft tissue, sectioned in the sagittal plane, and stained. The spatial relationship of 1) the epiphyseal side of the physeal proliferative zone to the nearest point of bony attachment of the anterior cruciate ligament and 2) the origin of the anterior cruciate ligament to the over-the-top position were measured. The same measurements were made in 13 skeletally immature knees (ages, 5 to 15 years). We found that the femoral origin of the fetal anterior cruciate ligament developed as a confluence of ligament fibers with periosteum at 20 weeks, vascular invasion into the epiphysis at 24 weeks, and establishment of a secure epiphyseal attachment by 36 weeks. In the fetus, the distance from the anterior cruciate ligament femoral origin to the epiphysis was 2.66+/-0.18 mm (range, 2.34 to 2.94). There was no significant change in this distance in adolescent specimens (2.92+/-0.68 mm; range, 2.24 to 3.62). The over-the-top position was at the level of the distal femoral physis.

Magnetic resonance imaging of the wrist.

Optimal magnetic resonance (MR) imaging of the wrist requires a high field strength magnet and a dedicated wrist coil to achieve high-resolution images. Using current MR sequences, detailed images of articular cartilage and the supporting ligaments and tendons can be obtained. Evaluation of the triangular fibrocartilage as well as the extrinsic and intrinsic ligaments of the wrist is possible with thin-slice three-dimensional volumetric gradient recalled sequences. Fast inversion recovery sequences, used to achieve fat suppression in peripheral joints such as the wrist, allow for detection of acute osseous trauma, which is often radiographically occult. Cartilage-sensitive imaging allows for evaluation of conditions in the skeletally immature patient, such as chronic physeal loading in the adolescent gymnast, as well as detection of the sequelae of altered biomechanics in the adult, as in the ulnolunate impaction syndrome. Moreover, contrast-enhanced magnetic resonance angiography permits a relatively noninvasive evaluation of peripheral vascular disease, obviating the need for an intraarticular injection.

Pigmented villonodular synovitis of the hip: 2- to 23-year followup study.

Pigmented villonodular synovitis affecting the hip is rare. Seven new patients are presented and 117 cases from the literature are reviewed. Among the new patients, two refused treatment; in one patient, severe bone loss was observed after a radiographic followup of 21 years; the second patient showed no radiographic changes 2 years after diagnosis. One patient underwent a synovectomy and had a recurrence 9 years later, requiring a total hip replacement. The remaining four patients underwent synovectomy and primary total hip replacement with no recurrences detected after an average followup of 13 years (range, 2-23 years). Among 117 cases published, 62 patients (53%) did not have enough information for analysis. A metaanalysis using the remaining 55 patients was done. In nine patients (16%; nine of 55) the diagnosis was made with a preoperative biopsy. Treatment consisted of synovectomy in 26 patients (47%; 26 of 55), arthroplasty in 24 (43%; 24 of 55), arthrodesis in two (4%; two of 55), and hindquarter amputation in a patient misdiagnosed as having synovial sarcoma (2%; one of 55). Two patients (4%; two of 55) were not treated. Ten patients had a recurrence (19%; 10 of 53); nine in the synovectomy group (35 %; nine of 26) and one in the joint replacement group (4%; one of 24). Synovectomy is recommended for patients with preserved articular cartilage and total hip replacement is recommended for patients with secondary osteoarthritis. Removal of all macroscopic tumors including careful curetting of the osteolytic lesions should be done as they may constitute a source of recurrence.

Imaging of the multiple-ligament-injured knee.

Imaging of the multiple-ligament-injured knee requires a comprehensive assessment of ligaments, cartilage, bone, peripheral nerves, and vascular anatomy. It is imperative that the radiologist be a crucial part of the trauma team, to provide prompt diagnostic assistance without unnecessary delays in patient management. MR angiography remains a promising modality to detect vascular injury and provides arteriographic assessment with little risk to the patient in a more expeditious fashion than conventional contrast angiography.

Imaging of posttraumatic and soft tissue dysfunction of the elbow.

The inherent obliquity of the elbow produces a challenge to the radiologist. In the treatment of elbow trauma, comprehensive evaluation includes detection of bone, cartilage, ligament, and tendon injury. In most cases, plain radiographs remain the initial imaging mainstay for evaluation of the elbow, followed by properly performed magnetic resonance imaging with thin (1.5-2 mm) sections and appropriate pulse sequencing to provide differential contrast between subchondral bone, cartilage, and joint fluid. Vigilant attention to imaging technique obviates the need for additional intraarticular contrast agent, which converts the magnetic resonance imaging to an invasive procedure and, in many cases, increases the cost. The advent of magnetic resonance angiography has provided an important noninvasive diagnostic means to detect associated vascular injury. In addition, computed tomography imaging, particularly with concomitant three-dimensional reformations, provides comprehensive fracture assessment. Postprocessing capabilities include rotation of three-dimensional models and subtraction programs that may be useful in disclosing subtle fracture components. Finally, ultrasound increasingly is being accepted as an important imaging modality by which to detect tendinous and soft tissue injury and has the distinct advantage of being able to impart dynamic load to muscle tendon units.

Prosthetic radial head components and proximal radial morphology: a mismatch.

A morphometric study of the proximal radius was performed with magnetic resonance imaging scans to measure the anatomic dimensions of the radial head and neck. These dimensions were then compared with the manufacturer's size specifications of commercially available titanium prosthetic radial head components to determine whether these designs adequately match the morphologic characteristics of the proximal radius. A cadaveric correlation was performed to validate the accuracy and reliability of measurements obtained from the magnetic resonance scans. The narrow intramedullary dimensions of the radial neck negated fitting of even the smallest available metallic prosthetic component stem in 18 (39%) of 46 scans reviewed (confidence interval 26% to 53%). Of the 31 male patients who underwent scanning, 4 (13%) would not be able to be fitted with a prosthetic component according to the manufacturer's technique guide (confidence interval 0% to 29%). Of the 15 female patients who underwent scanning, 14 (93%) would not able to be fitted with a prosthetic stem (confidence interval 70% to 99%). In those patients in whom the radial neck could accommodate a prosthetic stem (n = 26), there was ineffective restoration of proximal radial head length in all cases (100%, confidence interval 87% to 100%). The average shortening was 4 mm of proximal radial length (range 1 to 7 mm). Our findings reveal that the commercially available metallic radial head design may overestimate the dimensions of the radial neck. Inadequate sizing of radial head prostheses may lead to an inadvertent change in proximal radial length, with potentially adverse effects on elbow, forearm, and wrist mechanics. Newer designs taking into account these anatomic dimensions may lead to an improvement in function after reconstruction.

Injuries of the pectoralis major muscle: evaluation with MR imaging.

PURPOSE: To demonstrate that magnetic resonance (MR) imaging allows evaluation of injuries of the pectoralis major muscle. MATERIALS AND METHODS: Fifteen men underwent MR imaging after injury of the pectoralis major muscle. Most of the patients (nine of 15) were injured while lifting weights, notably bench-pressing. The injuries were evaluated for abnormal morphology and signal intensity, specifically the site of injury, degree of tearing, and amount of tendon retraction. RESULTS: Six injuries occurred at the musculotendinous junction, and five were treated conservatively; eight of the nine cases of distal tendon avulsion were treated with primary surgical repair. The MR imaging findings were confirmed in the nine cases treated surgically. Complete tears (three of 15) were less common than partial tears (12 of 15). The sternal and clavicular heads were torn in 10 patients, only the clavicular head was torn in two patients, and only the sternal head was torn in three patients. Acute tears (10 of 15) demonstrated hemorrhage and edema, whereas chronic tears (five of 15) demonstrated fibrosis and scarring. There was a variable amount of tendon retraction. CONCLUSION: MR imaging allows accurate evaluation of injuries of the pectoralis major muscle and enables identification of patients who would benefit from surgical repair.

Noncontrast magnetic resonance imaging of superior labral lesions. 102 cases confirmed at arthroscopic surgery.

Previous studies report that noncontrast magnetic resonance imaging is limited in the evaluation of the superior glenoid labrum. From our magnetic resonance imaging database of 2552 patients, we prospectively identified 104 patients with superior labral lesions who subsequently went on to arthroscopic surgery. Magnetic resonance images were assessed to identify fraying, flap tears, bucket-handle tears, or displaced flap of fibrocartilage. The biceps tendon was also evaluated. Patients were categorized according to Snyder's classification, and the findings on the magnetic resonance images were correlated with surgical findings. One hundred of the 104 tears suspected on the images were confirmed at surgery. There were four false-positives and two false-negatives, the former reflecting one normal labrum, two meniscoid-type labra, and one sublabral foramen. With arthroscopic surgery as the standard, magnetic resonance imaging had a sensitivity of 98.0% (100 of 102), a specificity of 89.5% (34 of 38), and an accuracy of 95.7% (134 of 140) for detection of superior labral lesions. We concluded that high-resolution noncontrast magnetic resonance imaging can accurately diagnose superior labral lesions and aid in surgical management.

Magnetic resonance evaluation of the labral capsular ligamentous complex: a pictorial review.

Magnetic resonance imaging of the shoulder is a common imaging test, and in the course of routine evaluation it can provide accurate information regarding the labral capsular ligamentous complex (LCLC). Common patterns of labral injury include fraying, flap tears and labral distraction, which can be readily identified on both coronal and axial planes by paying attention to signal and morphological characteristics. Capsular and ligamentous pathology may be subtle, but is recognizable using a high-resolution technique that has differential contrast between native intra-articular fluid and the adjacent labrum and capsular restraints. Common patterns of capsular injury include a thickened, hyperintense capsule, sometimes with disruption and retraction. The inferior glenohumeral ligament is the primary stabilizer of the shoulder joint, and although failure of this structure is uncommon, the injury is easily identified. Shoulder instability is a common presentation, the diagnosis of which is dependent upon recognizing various injury patterns including Bankart lesions, reverse Bankart lesions, anterior labroligamentous periosteal sleeve avulsion (ALPSA) and failure of the inferior glenohumeral ligament.