Detection of scapholunate interosseous ligament injury using dynamic computed tomography-derived arthrokinematics: A prospective clinical trial.

Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

OrthoFusion: A Super-Resolution Algorithm to Fuse Orthogonal CT Volumes.

OrthoFusion, an intuitive super-resolution algorithm, is presented in this study to enhance the spatial resolution of clinical CT volumes. The efficacy of OrthoFusion is evaluated, relative to high-resolution CT volumes (ground truth), by assessing image volume and derived bone morphological similarity, as well as its performance in specific applications in 2D-3D registration tasks. Results demonstrate that OrthoFusion significantly reduced segmentation time, while improving structural similarity of bone images and relative accuracy of derived bone model geometries. Moreover, it proved beneficial in the context of biplane videoradiography, enhancing the similarity of digitally reconstructed radiographs to radiographic images and improving the accuracy of relative bony kinematics. OrthoFusion's simplicity, ease of implementation, and generalizability make it a valuable tool for researchers and clinicians seeking high spatial resolution from existing clinical CT data. This study opens new avenues for retrospectively utilizing clinical images for research and advanced clinical purposes, while reducing the need for additional scans, mitigating associated costs and radiation exposure.

Assessing carpal kinematics following scapholunate interosseous ligament injury ex vivo using four-dimensional dynamic computed tomography.

BACKGROUND: Scapholunate interosseous ligament injuries are prevalent and often challenging to diagnose radiographically. Four-dimensional CT allows visualization of carpal bones during motion. We present a cadaveric model of sequential ligamentous sectionings ("injuries") to quantify their effects on interosseous proximities at the radioscaphoid joint and scapholunate interval. We hypothesized that injury, wrist position, and their interaction affect carpal arthrokinematics. METHODS: Eight cadaveric wrists were moved through flexion-extension and radioulnar deviation after injuries. Dynamic CT images of each motion were acquired in each injury condition using a second-generation dual-source CT scanner. Carpal osteokinematics were used to calculate arthrokinematic interosseous proximity distributions during motion. Median interosseous proximities were normalized and categorized by wrist position. Linear mixed-effects models and marginal means tests were used to compare distributions of median interosseous proximities. FINDINGS: The effect of wrist position was significant for both flexion-extension and radioulnar deviation at the radioscaphoid joint; the effect of injury was significant for flexion-extension at the scapholunate interval; and the effect of their interaction was significant for radioulnar deviation at the scapholunate interval. Across wrist positions, radioscaphoid median interosseous proximities were less able to distinguish injury conditions versus scapholunate proximities. Median interosseous proximities at the scapholunate interval are majoritively able to detect differences between less (Geissler I-III) versus more (Geissler IV) severe injuries when the wrist is flexed, extended, and ulnarly-deviated. INTERPRETATION: Dynamic CT enhances our understanding of carpal arthrokinematics in a cadaveric model of SLIL injury. Scapholunate median interosseous proximities in flexion, extension, and ulnar deviation best demonstrate ligamentous integrity.

Evaluation of Scapholunate Injury and Repair with Dynamic (4D) CT: A Preliminary Report of Two Cases.

Background In predynamic or dynamic scapholunate (SL) instability, standard diagnostic imaging may not identify SL interosseous ligament (SLIL) injury, leading to delayed detection and intervention. This study describes the use of four-dimensional computed tomography (4DCT) in identifying early SLIL injury and following injured wrists to 1-year postoperatively. Description of Technique 4DCT acquires a series of three-dimensional volume data with high temporal resolution (66 ms). 4DCT-derived arthrokinematic data can be used as biomarkers of ligament integrity. Patients and Methods This study presents the use of 4DCT in a two-participant case series to assess changes in arthrokinematics following unilateral SLIL injury preoperatively and 1-year postoperatively. Patients were treated with volar ligament repair with volar capsulodesis and arthroscopic dorsal capsulodesis. Arthrokinematics were compared between uninjured, preoperative injured, and postoperative injured (repaired) wrists. Results 4DCT detected changes in interosseous distances during flexion-extension and radioulnar deviation. Generally, radioscaphoid joint distances were greatest in the uninjured wrist during flexion-extension and radioulnar deviation, and SL interval distances were smallest in the uninjured wrist during flexion-extension and radioulnar deviation. Conclusion 4DCT provides insight into carpal arthrokinematics during motion. Distances between the radioscaphoid joint and SL interval can be displayed as proximity maps or as simplified descriptive statistics to facilitate comparisons between wrists and time points. These data offer insight into areas of concern for decreased interosseous distance and increased intercarpal diastasis. This method may allow surgeons to assess whether (1) injury can be visualized during motion, (2) surgery repaired the injury, and (3) surgery restored normal carpal motion. Level of Evidence Level IV, Case series.

Assessment of Patellar Vascularity after Patellar Cartilage Restoration via Lateral Parapatellar Approach: Analysis Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

OBJECTIVE: Patellofemoral cartilage restoration procedures, including osteochondral allograft, particulated juvenile cartilage, and matrix-induced autologous chondrocyte implantation, have been shown to be effective treatments for patellofemoral cartilage lesions. However, concerns exist regarding disruption of the patellar vascular supply and secondary stabilizers of the patellofemoral joint during medial parapatellar approaches, especially when combined with a lateral release. A lateral parapatellar approach affords the possibility of avoiding disruption of the medial blood supply to the patella, while also allowing laterally-based soft tissue stabilization procedures. The purpose of this study was to investigate in vivo changes in patellar vascularity following patellofemoral cartilage restoration procedures performed via a lateral parapatellar approach via use of dynamic contrast-enhanced magnetic resonance (MR) imaging. DESIGN: This study is a prospective case series of 5 adult patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach with pre-operative and post-operative dynamic contrast-enhanced MR imaging to assess changes in patellar vascularity. Secondary outcomes included knee range of motion, need for revision surgery, and complications. RESULTS: There was no significant post-operative difference in patellar vascularity in patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach, as evaluated by qualitative MR imaging. CONCLUSION: Our results suggest that a lateral parapatellar approach for cartilage restoration procedures may preserve patellar vascularity, while also allowing for lateral release to be performed through the same incision.

The Dorsal Ligament Complex: A Cadaveric, Histology, and Imaging Study.

PURPOSE: The distinction between the dorsal intercarpal (DIC) and dorsal scaphotriquetral (DST) ligaments is imprecise and unclear in the literature. The purpose of our cadaveric study was to define the origins, insertions, and anatomic relationships of the dorsal wrist ligaments and relate these anatomic findings to magnetic resonance imaging (MRI) scans and histology. METHODS: The study included 17 unmatched fresh-frozen cadaveric specimens (7 male and 10 female), with a mean age of 67.1 years (range, 48-86 years). Wrists with arthritis or carpal malalignment were excluded. Ligaments were dissected and insertion sites were recorded in the radioulnar (width) and proximodistal (length) dimensions, centered at the midpoints of the insertion. Three cadaveric specimens underwent a histologic analysis to demonstrate ligament composition and insertion sites. Three additional cadavers underwent MRI, from which 3-dimensional models were built to model ligament topography. RESULTS: The conjoined triquetral insertion of the DIC, DST, and dorsal radiocarpal (DRC) measured 88.5 ± 6.4 mm2. In each specimen, there were 2 distinct deep and superficial components of intercarpal fibers. The deep component inserted on the lunate with an area of 59.0 ± 5.0 mm2. The deep and superficial components diverged as they coursed radially. The superficial component proceeded to the scaphoid ridge, trapezium, and trapezoid, whereas the deep component inserted on the proximal row. The deep fibers blended distally from their lunate insertion with the DST, forming a robust, 2.9 ± 0.8-mm wide extension over the dorsal capitate. The DRC inserted on the lunate, proximal to the DIC and DST insertions, with an area of 23.9 ± 5.4 mm2. CONCLUSIONS: The dorsal ligament complex forms a firm link across the proximal carpal row and the DST provides extension of the proximal row over the capitate. CLINICAL RELEVANCE: This information can guide surgeons while performing a dorsal approach to the wrist and repairing traumatic ligament disruption.

Optimizing Web-Based Viewer of 4D CT Scans for Clinical Assessment of Injured Wrists.

Wrist injuries pose a unique challenge for patients and providers. Due to the complexity of the wrist, it is difficult to determine if a wrist injury is primarily a bone fracture or soft tissue damage. The scapholunate interosseous ligament (SLIL) is an important ligament in the function of the wrist, and it is also one of the most common soft tissue injuries in the wrist. Wrist arthroscopy is the gold standard for assessing injuries of the scapholunate joint; however, it is an invasive procedure. Recent advances in dynamic imaging with 4D Computed Tomography scans allow for the assessment of SLIL injuries non-invasively. Unfortunately, 4DCT scan data can be difficult to disseminate to clinical practitioners due to the large amount of data generated and the complexity in visualizing the data. A web-based application has been developed to interactively assess 4DCT scans of patients with suspected SLIL injury. Due to the magnitude of data and the diversity of hardware platforms used to visualize the data, the images are preprocessed with a rendering engine and presented in a pseudo-3D visualization paradigm where the user can interactively explore the 3D data without transmitting the entire dataset to the local computer. The technology has been used to assess 27 patients.

Differences in the magnetic resonance imaging parameter T2* may be identified during the course of canine patellar tendon healing: a pilot study.

BACKGROUND: Previous studies have utilized ultrashort echo (UTE) magnetic resonance imaging (MRI), and derived T2* maps, to evaluate structures with highly ordered collagen structures such as tendon. T2* maps may provide a noninvasive means to assess tendon damage and healing. This pilot study evaluated the longitudinal relationship of an induced mechanical strain on the patellar tendon with corresponding UTE T2* metrics, histologic and biomechanical evaluation at two post-operative time points. METHODS: A total of 27 patellar tendons in male Beagles were surgically subjected to stretching by a small diameter (SmD) or a large diameter (LgD) diameter rod to induce damage due to strain, and evaluated at 4- and 8-week intervals using quantitative MRI (qMRI), biomechanical testing, and histology. A separate set of 16 limbs were used as controls. RESULTS: The tendons experienced a 67% and 17% prolongation of short T2* values as compared to controls at 4 and 8 weeks post-operatively, respectively. Histologic analysis displayed a trend of increased collagen disruption at 4 weeks followed by presence of greater organization at 8 weeks. Biomechanical evaluation found a reduction of tendon modulus and failure strain at both time points, and an increase in cross-sectional area at 4 weeks as compared to controls. CONCLUSIONS: These findings display tendon healing in response to an imposed strain and present the utility of qMRI to evaluate longitudinal differences of patellar tendon T2* values in a model of induced subclinical tendon damage. The qMRI technique of UTE provides a means to non-invasively evaluate the healing process of a mechanically damaged tendon.

Evaluation of Osseous Morphology of the Hip Using Zero Echo Time Magnetic Resonance Imaging.

BACKGROUND: Femoroacetabular impingement syndrome (FAIS) is a common disorder of the hip resulting in groin pain and ultimately osteoarthritis. Radiologic assessment of FAI morphologies, which may present with overlapping radiologic features of hip dysplasia, often requires the use of computed tomography (CT) for evaluation of osseous abnormality, owing to the difficulty of direct visualization of cortical and subchondral bone with conventional magnetic resonance imaging (MRI). The use of a zero echo time (ZTE) MRI pulse sequence may obviate the need for CT by rendering bone directly from MRI. PURPOSE/HYPOTHESIS: The purpose was to explore the application of ZTE MRI to the assessment of osseous FAI and dysplasia morphologies of the hip. It was hypothesized that angular measurements from ZTE images would show significant agreement with measurements obtained from CT images. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Thirty-eight hips from 23 patients were imaged with ZTE MRI and CT. Clinically relevant angular measurements of hip morphology were made in both modalities and compared to assess agreement. Measurements included coronal and sagittal center-edge angles, femoral neck-shaft angle, acetabular version (at 1-, 2-, and 3-o'clock positions), Tönnis angle, alpha angle, and modified-beta angle. Interrater agreement was assessed for a subset of 10 hips by 2 raters. Intermodal agreement was assessed on the complete cohort and a single rater. RESULTS: Interrater agreement was demonstrated in both CT and ZTE, with intraclass correlation coefficient values ranging from 0.636 to 0.990 for ZTE and 0.747 to 0.983 for CT, indicating "good" to "excellent" agreement. Intermodal agreement was also shown to be significant, with intraclass correlation coefficients ranging from 0.618 to 0.904. CONCLUSION: Significant agreement of angular measurements for hip morphology exists between ZTE MRI and CT imaging. ZTE MRI may be an effective method to quantitatively evaluate osseous hip morphology.

Quantitative Magnetic Resonance Imaging and Histological Comparison of Normal Canine Menisci.

OBJECTIVE: The purpose of this observational study was to establish normative data for the canine menisci using magnetic resonance imaging (MRI). METHODS: Ten fresh stifles from five normal male Beagles were obtained from animals with no known lameness. Conventional MRI and ultrashort echo time (UTE) imaging were performed and T2* values calculated. Five stifles were assessed histologically. RESULTS: The caudal horn of the medial meniscus had significantly prolonged T2* values (4.6 ± 1.27 ms; p = 0.002) as compared with the cranial horn of the medial meniscus (3.25 ± 0.86 ms), and the cranial (3.06 ± 0.54 ms) and caudal (3.64 ± 0.72 ms) horns of the lateral meniscus. Histology demonstrated normal tibial, femoral, interior and peripheral meniscal margins, and normal cellularity. The medial meniscus was noted to be obliquely oriented to the scan plane compared with the relatively perpendicular orientation of the lateral meniscus as compared with the bore of the magnet in a limb-extended orientation. CLINICAL SIGNIFICANCE: Variability of MRI UTE T2* is seen in the normal canine meniscus, with prolongation of the caudal horn, medial meniscus. Prolongation may be due to magic angle effects, as the medial meniscus of the Beagle is not perpendicular to the axis of the main magnetic field. Canine meniscal injury is a common sequela to cruciate tear, and detecting meniscal damage is important for directing patient care. The non-invasive quantitative MRI technique of UTE imaging can be used for the evaluation of collagen orientation, while acknowledging inherent regions of prolongation.

Technical Developments: Zero Echo Time Imaging of the Shoulder: Enhanced Osseous Detail by Using MR Imaging.

Purpose To determine the intermodality agreement of morphologic grading and clinically relevant quantitative measurements between computed tomography (CT) and zero echo time (ZTE) magnetic resonance (MR) imaging of the shoulder. The primary objective was to demonstrate the clinical applicability of ZTE in osseous shoulder imaging. Materials and Methods Thirty-four patients undergoing standard-of-care (SOC) MR imaging with concomitant CT were enrolled in this institutional review board-approved study. ZTE images were acquired after SOC MR imaging. Glenoid morphology (version, vault depth, erosion), injury or disease (osteoarthritis, Bankart and Hill-Sachs lesions, subchondral cysts), and evidence of prior surgery were graded or measured. κ Values, intraclass correlation coefficients (ICCs), and Bland-Altman limits of agreement were used to establish agreement. Qualitative comparison of osseous findings was performed between ZTE and SOC MR imaging. Results Binary classification and nominal/ordinal grades showed substantial or better agreement between raters and modalities (κ or ICC > 0.6). Continuous measurements exhibited strong correlation between raters and modalities, although not universally. Bankart ICCs were not significant, owing to low prevalence. ZTE exhibited greater conspicuity of enthesopathic cysts and marrow edema. In 21 of 34 cases, ZTE imaging of osseous features exceeded SOC MR imaging. Conclusion ZTE MR imaging provides "CT-like" contrast for bone. The results of this study demonstrate strong intermodality agreement between measurements and grades from CT and ZTE images in a cohort of patients undergoing imaging with both modalities. A majority of ZTE image sets provided superior visualization of osseous features when compared with SOC MR image sets. This superiority coupled with strong quantitative agreement with CT suggests that ZTE may be used clinically in lieu of CT in some cases. © RSNA, 2017 Online supplemental material is available for this article.

Diagnostic Accuracy of Zero-Echo Time MRI for the Evaluation of Cervical Neural Foraminal Stenosis.

STUDY DESIGN: A cohort study. OBJECTIVE: The aim of this study was to evaluate the clinical utility of Zero-Echo-Time (ZTE) magnetic resonance imaging (MRI) for the assessment of cervical neural foraminal stenosis (CNFS) through the comparison of inter-modality [computed tomography (CT) and ZTE-MRI] CNFS grade severity agreements. SUMMARY OF BACKGROUND DATA: Conventional MRI limited in its ability to provide direct visualization of cortical bone. The highly organized tissue structure of cortical bone results in very short T2 values that preclude acquisition of sufficient signal intensity and positive image contrast. ZTE imaging permits visualization of tissues with very short transverse relaxation times, and is capable of displaying images with CT-like contrast. METHODS: Thirty-four subjects were recruited from a clinical cohort of patients undergoing standard of care MRI and CT imaging for evaluation of CNFS. Standard of care CT imaging studies were obtained on all subjects within 6 months of their ZTE-MRI acquisition (mean time interval: 25.3 ±â€Š54.1 days; median: 0 days). ZTE-MRI and CT imaging studies were evaluated and severity of CNFS was graded on a scale from 0 to 5 (0 = none; 5 = severe). Weighted-kappa statistics were used to assess agreement between ZTE and CT grades of CNFS on both sides (right and left) of each motion segment. Ordinal logistic mixed-effects regression analyses evaluated the effects of inter-modality position differences (flexion-extension curvature) on inter-modality differences in CNFS grade. RESULTS: Substantial agreement (κ = 0.72) was found between ZTE- and CT-based grades of CNFS. Significant inter-modality differences in cervical spine curvature were found for all motion segments, except C2-3 and C3-4 (P < 0.05). However, no significant relationship was found between inter-modality differences in curvature, and inter-modality differences in CNFS grade for any motion segment (P = 0.28). CONCLUSION: Results of the current study suggest that ZTE-MRI is well-suited for the evaluation of CNFS and may have the potential to obviate the need for concurrent CT scans in some cases. LEVEL OF EVIDENCE: 2.

Grasp Performance of a Soft Synergy-Based Prosthetic Hand: A Pilot Study.

Current prosthetic hands are frequently rejected in part due to limited functionality and versatility. We assessed the feasibility of a novel prosthetic hand, the SoftHand Pro (SHP), whose design combines soft robotics and hand postural synergies. Able-bodied subjects ( ) tracked cursor motion by opening and closing the SHP and performed a grasp-lift-hold-release (GLHR) task with a sensorized cylindrical object of variable weight. The SHP control was driven by electromyographic (EMG) signals from two antagonistic muscles. Although the time to perform the GLHR task was longer for the SHP than native hand for the first few trials (10.2 ± 1.4 s and 2.13 ± 0.09 s, respectively), performance was much faster on subsequent trials (~5 s). The SHP steady-state grip force was significantly modulated as a function of object weight ( ). For the native hand, however, peak and steady-state grip forces were modulated to a greater extent (+68% and +91%, respectively). These changes were mediated by the modulation of EMG amplitude and co-contraction. These data suggest that the SHP has a promise for prosthetic applications and point-to-design modifications that could improve the SHP.

The Role of Dynamic (4D) CT in the Detection of Scapholunate Ligament Injury.

Background Scapholunate (SL) interosseus ligament injuries detected at an early stage could allow the surgeon to prevent progression through the spectrum of injury that leads to instability, and eventually osteoarthritis. We contend that early instability following injury can be detected by visualizing the relative motions and distances between the involved carpal bones (scaphoid and lunate) during wrist movement in vivo. The purpose of this study is to demonstrate the utility of dynamic CT (i.e., 4DCT) in diagnosing SL interosseus ligament injuries in two patients with clinical suspicion of SL interosseus ligament injury during flexion-extension (FE), radial-ulnar (RU) deviation, and dart thrower's (DT) motions. Case Description 4DCT images obtained from two individual cases were analyzed to assess the proximity between the scaphoid and lunate during wrist motion using standard image processing techniques. Proximity maps representing the distances between the scaphoid and lunate bones during each phase of wrist motion were determined. These maps provide insight into the severity of diastasis (large separation) and location of diastasis at the SL joint. The patients' proximity maps indicated dorsal diastasis and subtle uniform diastasis. Literature Review Complex musculoskeletal abnormalities, such as wrist joint instabilities, elude diagnosis during 2D fluoroscopy due to the 3D geometry of the anatomy and the inherent 3D nature of the bony kinematics. Even the most recent advances with MR arthrography lack good correlation with wrist arthroscopy. Wrist arthroscopy remains the gold standard for diagnosis to assess for intercarpal laxity. However, arthroscopy is an invasive procedure subjecting patients to the risk of infection, nerve injury, pain, and stiffness. Clinical Relevance 4DCT allows noninvasive characterization of where ligament injuries likely occur; this may allow for a more selective surgical treatment directed at the specific location of the tear.