Three-dimensional isotropic T2-weighted fast spin-echo (VISTA) ankle MRI versus two-dimensional fast spin-echo T2-weighted sequences for the evaluation of anterior talofibular ligament injury

3D isotropic MRI of ankle: review of literature with comparison to 2D MRI

The ankle joint has complex anatomy with different tissue structures and is commonly involved in traumatic injuries. Magnetic resonance imaging (MRI) is the primary imaging modality used to assess the soft tissue structures around the ankle joint including the ligaments, tendons, and articular cartilage. Two-dimensional (2D) fast spin echo/turbo spin echo (FSE/TSE) sequences are routinely used for ankle joint imaging. While the 2D sequences provide a good signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) with high spatial resolution, there are some limitations to their use owing to the thick slices, interslice gaps leading to partial volume effects, limited fluid contrast, and the need to acquire separate images in different orthogonal planes. The 3D MR imaging can overcome these limitations and recent advances have led to technical improvements that enable its widespread clinical use in acceptable time periods. The volume imaging renders the advantage of reconstructing into thin continuous slices with isotropic voxels enabling multiplanar reconstructions that helps in visualizing complex anatomy of the structure of interest throughout their course with improved sharpness, definition of anatomic variants, and fluid conspicuity of lesions and injuries. Recent advances have also reduced the acquisition time of the 3D datasets making it more efficient than 2D sequences. This article reviews the recent technical developments in the domain 3D MRI, compares imaging with 3D versus 2D sequences, and demonstrates the use-case scenarios with interesting cases, and benefits of 3D MRI in evaluating various ankle joint components and their lesions.

Multiaxial 3D MRI of the Ankle: Advanced High-Resolution Visualization of Ligaments, Tendons, and Articular Cartilage

MRI is a valuable tool for diagnosing a broad spectrum of acute and chronic ankle disorders, including ligament tears, tendinopathy, and osteochondral lesions. Traditional two-dimensional (2D) MRI provides a high image signal and contrast of anatomic structures for accurately characterizing articular cartilage, bone marrow, synovium, ligaments, tendons, and nerves. However, 2D MRI limitations are thick slices and fixed slice orientations. In clinical practice, 2D MRI is limited to 2 to 3 mm slice thickness, which can cause blurred contours of oblique structures due to volume averaging effects within the image slice. In addition, image plane orientations are fixated and cannot be changed after the scan, resulting in 2D MRI lacking multiplanar and multiaxial reformation abilities for individualized image plane orientations along oblique and curved anatomic structures, such as ankle ligaments and tendons. In contrast, three-dimensional (3D) MRI is a newer, clinically available MRI technique capable of acquiring high-resolution ankle MRI data sets with isotropic voxel size. The inherently high spatial resolution of 3D MRI permits up to five times thinner (0.5 mm) image slices. In addition, 3D MRI can be acquired image voxel with the same edge length in all three space dimensions (isotropism), permitting unrestricted multiplanar and multiaxial image reformation and postprocessing after the MRI scan. Clinical 3D MRI of the ankle with 0.5 to 0.7 mm isotropic voxel size resolves the smallest anatomic ankle structures and abnormalities of ligament and tendon fibers, osteochondral lesions, and nerves. After acquiring the images, operators can align image planes individually along any anatomic structure of interest, such as ligaments and tendons segments. In addition, curved multiplanar image reformations can unfold the entire course of multiaxially curved structures, such as perimalleolar tendons, into one image plane. We recommend adding 3D MRI pulse sequences to traditional 2D MRI protocols to visualize small and curved ankle structures to better advantage. This article provides an overview of the clinical application of 3D MRI of the ankle, compares diagnostic performances of 2D and 3D MRI for diagnosing ankle abnormalities, and illustrates clinical 3D ankle MRI applications.

Ultrasound or MRI in the Evaluation of Anterior Talofibular Ligament (ATFL) Injuries: Systematic Review and Meta-Analysis

OBJECTIVES

Ankle sprains represent the second most common cause of emergency department access for musculoskeletal injury and lateral ankle ligament complex tears account for 850,000 cases annually in the United States with a relapse rate of 70%. Clinical examination is limited due to its subjectivity and the difficulty of identifying a specific involvement of the ligament; therefore, US and MRI are frequently requested. Therefore, the goal of this study is to analyze the available literature on the use of ultrasound (US) and magnetic resonance imaging (MRI) to diagnose injuries to the anterior talofibular ligament (ATFL) with a meta-analytic approach.

METHODS

According to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines, all studies regarding the diagnostic accuracy of ultrasound and magnetic resonance imaging ATFL injuries were searched and assessed. The data were obtained from two independent reviewers with 12 and 3 years of experience in meta-analysis. A QUADAS-2 (Quality Assessment of Studies of Diagnostic Accuracy Studies) checklist was carried out to assess the risk of biases. From the selected studies, the sensitivity, specificity, and accuracy data were extracted.

RESULTS

Nine studies were included. The results of the meta-analysis demonstrate a greater sensitivity for ultrasound [96.88 (95% CI: 94-99) (fixed effects); 97 (95% CI: 94-99) (random effects)] compared to MRI [88.50 (95% CI: 85-91) (fixed effects); 86.98 (95% CI: 77-94) (random effects)], p < 0.05. The result of this meta-analysis shows that the less expensive diagnostic technique is also the most sensitive for the diagnosis of ATFL tears. Ultrasound articles resulted to have non-heterogeneity [(p = 0.2816; I° = 21.4607%)].

CONCLUSION

This meta-analysis demonstrates that US appears to be a highly sensitive diagnostic technique for diagnosing tears of the ATFL. Compared to MRI, the sensitivity of US result was higher.

Advanced Imaging in the Chronic Lateral Ankle Instability: An Algorithmic Approach

Imaging examinations are a fundamental part of assessing chronic lateral ankle instability (CLAI). Plain radiographs are used in the initial examination, whereas stress radiographs can be requested to actively search for instability. Ultrasonography (US) and Magnetic Resonance Imaging (MRI) allow direct visualization of ligamentous structures, with the advantage of dynamic evaluation for US, and assessment of associated lesions and intra-articular abnormalities for MRI, which plays an essential role in surgical planning. This article reviews imaging methods to diagnose and follow up on CLAI, along with illustrative cases and an algorithmic approach.

Prospective intraindividual comparison of a standard 2D TSE MRI protocol for ankle imaging and a deep learning-based 2D TSE MRI protocol with a scan time reduction of 48

PURPOSE

Magnetic resonance imaging (MRI) scan time remains a limited and valuable resource. This study evaluates the diagnostic performance of a deep learning (DL)-based accelerated TSE study protocol compared to a standard TSE study protocol in ankle MRI.

MATERIAL AND METHODS

Between October 2020 and July 2021 forty-seven patients were enrolled in this study for an intraindividual comparison of a standard TSE study protocol and a DL TSE study protocol either on a 1.5 T or a 3 T scanner. Two radiologists evaluated the examinations regarding structural pathologies and image quality categories (5-point-Likert-scale; 1 = "non diagnostic", 5 = "excellent").

RESULTS

Both readers showed almost perfect/perfect agreement of DL TSE with standard TSE in all analyzed structural pathologies (0.81-1.00) with a median "good" or "excellent" rating (4-5/5) in all image quality categories in both 1.5 T and 3 T MRI. The reduction of total acquisition time of DL TSE compared to standard TSE was 49% in 1.5 T and 48% in 3 T MRI to a total acquisition time of 5 min 41 s and 5 min 46 s.

CONCLUSION

In ankle MRI the new DL-based accelerated TSE study protocol delivers high agreement with standard TSE and high image quality, while reducing the acquisition time by 48%.

The Influence of Suture-Tape Augmentation on Biological Healing of the Anterior Talofibular Ligament in Chronic Ankle Instability: A Quantitative Analysis Using MRI

While the effectiveness of suture-tape augmentation for chronic ankle instability has been supported biomechanically and clinically, little information is available regarding biological changes of the lateral ligaments postoperatively. This study aims to quantitatively evaluate ligament regeneration with MRI after suture-tape augmentation. Forty-six patients underwent MRI scan at follow-up of a minimum of 1 year after lateral ligaments augmentation using suture-tape. The signal-to-noise ratio (SNR) and width of anterior talofibular ligament (ATFL) were measured on preoperative and postoperative MRI by 3 researchers. The degree of biological healing of ATFL was analyzed based on the change of SNR and comparison with normal contralateral ankle. Clinical outcomes were evaluated with the Foot and Ankle Outcome Score, Foot and Ankle Ability Measure. Mean Foot and Ankle Outcome Score and Foot and Ankle Ability Measure scores improved significantly from 63.1 to 92.7, and 59.6 to 91.5 points at final follow-up, respectively (p < .001). Mean SNR and width of ATFL were changed insignificantly from 8.24 to 7.96, and 1.88 mm to 2.05 mm at final follow-up, respectively (p = .391, .509). As compared to contralateral side, there were significant differences in both mean SNR and width of the ATFL, respectively (p < .001, p = .0012). Spearman's correlation analysis revealed no significant association between clinical outcomes and degree of biological healing of ATFL based on MRI. Despite significant improvement in patient-reported clinical outcomes, the influence on ligament regeneration of suture-tape augmentation for chronic ankle instability was insignificant. In addition, there was no significant correlation between clinical outcomes and degree of biological healing of the ATFL.

Morphologic evaluation of injured and contralateral uninjured ankles in patients with unilateral chronic ankle instability

OBJECTIVE

To compare the morphological anatomy and abnormalities of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) in unilateral chronic ankle instability (CAI).

METHODS

22 patients (men: women, 13:9; mean age, 28.95 ± 8.127 years) with unilateral CAI and 18 healthy volunteers (men: women, 9:9, mean age, 28.33 ± 3.678 years) were recruited. MRI scans were divided into Group 1 (22 injured ankles), Group 2 (22 contralateral uninjured ankles), and Group 3 (36 healthy volunteer ankles). The morphologic variables, MRI signal intensity (SI) values were evaluated.

RESULTS

The ATFL proximal, intermediate, and distal sites and the CFL proximal and distal sites in Group 3 were narrower than those in Group 1 (P ＜0.05). Both ATFL and CFL in Group 1 were thicker than those in Group 3 (P ＜0.01). The proximal and intermediate sites of the ATFL and the proximal site of the CFL in Group 3 were narrower than those in Group 2 (P ＜0.01). The intermediate site of the ATFL and the proximal and distal sites of the CFL in Group 2 were thicker than those in Group 3 (P ＜0.01). The mean SI values of the ATFL in Group 1 were higher than those in Groups 2 and 3 (P ＜0.01). The ATFL and CFL SI values were higher in Group 2 than those in Group 3 (P ＜0.05).

CONCLUSION

Both the injured and contralateral uninjured ankles had wider ATFL and CFL, more thickness, and higher SI values compared with those of healthy volunteer ankles.

ADVANCES IN KNOWLEDGE

High-resolution three-dimensional MRI provides a potential tool assisting clinical decision on the treatment and rehabilitation therapy of patients with unilateral CAI.

Straight Form of Calcaneofibular Ligament as a Three-Dimensional Magnetic Resonance Imaging Sign in Diagnosis of Calcaneofibular Ligament and Anterior Talofibular Ligament Inferior Fascicle Injury

The present study was performed to investigate the morphological characteristics of the calcaneofibular ligament (CFL) and evaluate its relationship to the anterior talofibular ligament (ATFL) in patients with lateral ankle ligament injury using 3-dimensional magnetic resonance imaging (3D-MRI). This retrospective study involved 35 patients with lateral ankle ligament injury and 24 patients without a history of ankle trauma and a bone abnormality as controls. Reconstructed 3D-MRI was used to classify the form of the CFL as curved, wavy, or straight. The presence/absence of continuity between the fibula and CFL was evaluated in the 35 patients with injury, who were divided into 2 groups (continuity and discontinuity groups). The number of fascicles in the ATFL and the continuity between the distal end of the fibula and the proximal end of the ATFL were then evaluated. Among the patients with injury, 54.3% had the curve type of CFL, 34.3% had the wave type, and 11.4% had the straight type. In the control group, 62.5% had the curve type, 37.5% had the wave type, and none had the straight type. Continuity between the fibula and CFL was seen in 88.6%, and discontinuity was seen in 11.4%. Additionally, 85.7% had double fascicles in the ATFL. Inferior fascicle discontinuity between the ATFL and fibula was found in 13.3% with a double-fascicle ATFL; in all of these patients, the form of the CFL was straight and exhibited inferior fascicle discontinuity. The straight form of CFL could be a 3D-MRI sign in the diagnosis of CFL and ATFL inferior fascicle injury.

3D MRI of the Ankle: A Concise State-of-the-Art Review

Magnetic resonance imaging (MRI) is a powerful imaging modality for visualizing a wide range of ankle disorders that affect ligaments, tendons, and articular cartilage. Standard two-dimensional (2D) fast spin-echo (FSE) and turbo spin-echo (TSE) pulse sequences offer high signal-to-noise and contrast-to-noise ratios, but slice thickness limitations create partial volume effects. Modern three-dimensional (3D) FSE/TSE pulse sequences with isotropic voxel dimensions can achieve higher spatial resolution and similar contrast resolutions in ≤ 5 minutes of acquisition time. Advanced acceleration schemes have reduced the blurring effects of 3D FSE/TSE pulse sequences by affording shorter echo train lengths. The ability for thin-slice partitions and multiplanar reformation capabilities eliminate relevant partial volume effects and render modern 3D FSE/TSE pulse sequences excellently suited for MRI visualization of several oblique and curved structures around the ankle. Clinical efficiency gains can be achieved by replacing two or three 2D FSE/TSE sequences within an ankle protocol with a single isotropic 3D FSE/TSE pulse sequence. In this article, we review technical pulse sequence properties for 3D MRI of the ankle, discuss practical considerations for clinical implementation and achieving the highest image quality, compare diagnostic performance metrics of 2D and 3D MRI for major ankle structures, and illustrate a broad spectrum of ankle abnormalities.

Evaluation of the anterior inferior tibiofibular and anterior talofibular ligaments using 2D oblique coronal imaging and 3D isotropic resolution T2-weighted fast spin-echo sequences at 3.0 T: Is there additional diagnostic value?

INTRODUCTION

To compare diagnostic performance of additional two-dimensional (2D) oblique coronal view and three-dimensional (3D) T2-weighted fast spin-echo(FSE) images for diagnosing injury of the anterior inferior tibiofibular (AiTFL) and anterior talofibular ligaments (ATFL).

METHODS

This study included 48 patients with ankle sprain who had undergone MRI using standard protocol and two additional sequences with 2D oblique coronal and 3D isotropic images, followed by arthroscopic surgery. Ligament injuries was subdivided by intact tendon, partial or complete tear. Retrospectively, two musculoskeletal radiologists respectively reviewed three image sets of MR including 2D axial image only (set 1), 2D axial and oblique coronal images (set 2), and 2D axial with 3D-isotropic images (set 3). Using arthroscopic findings as reference standard, diagnostic performances of both methods were analysed by the area under the curve (AUC).

RESULTS

Arthroscopy confirmed 13 AiTFL and 41 ATFL injuries. For AiTFL, when set 1 and set 3 were compared, AUC value was significantly higher for set 3 (P < 0.05). However, there was no significant difference between AUC values for set 2 and set 3 sequences by either reader for either type of tear (P > 0.05). For ATFL, both readers found there was no significant difference in AUC values between set 1 and set 3 and between set 2 and set 3.

CONCLUSION

Additional oblique coronal sequence demonstrated better diagnostic performance for AiTFL injury than conventional and isotropic imaging did. This sequence showed as much diagnostic accuracy as isotropic sequence for evaluation of ATFL injury.

The role of the anterior talofibular ligament area as a morphological parameter of the chronic ankle sprain

BACKGROUND

Repetitive microtrauma can result in a hypertrophied ATFL. Previous studies have found that the anterior talofibular ligament thickness (ATFLT) is correlated with lateral ankle sprains, ligament injuries and chronic stroke in patients, and thickened anterior talofibular ligament (ATFL) has been considered to be a major morphologic parameter of hypertrophied ATFL. However, hypertrophy is different from thickness. Thus, we devised the anterior talofibular ligament area (ATFLA) as a new morphological parameter to evaluate the hypertrophy of the whole ATFL.

METHODS

ATFL samples were collected from 53 patients with sprain group and from 50 control subjects who underwent magnetic resonance imaging (MRI) of the ankle and revealed no evidence of lateral ankle injury. Axial T1-weighted MRI images were collected at the ankle level from all subjects. We measured the ATFLA and ATFLT at the anterior margin of the fibular malleolus to the talus bone on the MRI using a picture archiving and communications system. The ATFLA was measured as the whole cross-sectional ligament area of the ATFL that was most hypertrophied in the axial MR images. The ATFLT was measured as the thickest point between the lateral malleolus and the talus of the ankle.

RESULTS

The average ATFLA was 25.0 ± 6.0 mm² in the control group and 47.1 ± 10.4 mm² in the sprain group. The average ATFLT was 2.3 ± 0.6 mm in the control group and 3.8 ± 0.6 mm in the hypertrophied group. Patients in sprain group had significantly greater ATFLA (p < 0.001) and ATFLT (p < 0.001) than the control subjects. A Receiver Operator Characteristics curve analysis showed that the best cut-off point of the ATFLA was 34.8 mm², with 94.3% sensitivity, 94.0% specificity, and an AUC of 0.97 (95% CI, 0.94-1.00). The optimal cut-off point of the ATFLT was 3.1 mm, with 86.8% sensitivity, 86.0% specificity, and AUC of 0.95 (95% CI, 0.92-0.99).

CONCLUSION

ATFLA is a new morphological parameter for evaluating chronic ankle sprain, and may even be more sensitive than ATFLT.

3D MRI evaluation of morphological characteristics of lateral ankle ligaments in injured patients and uninjured controls

BACKGROUND

With ultrasonography or 2D magnetic resonance imaging (MRI) of the lateral ankle ligament, it is particularly difficult to show the entire calcaneofibular ligament (CFL). The purpose of this study was to evaluate the morphological characteristics of the lateral ankle ligaments in injured patients and uninjured controls using 3D MRI.

METHODS

A total of 64 ankles of 59 healthy volunteers and lateral ligament injury patients (mean age of 32.4 years) were examined. The 64 ankles included a healthy group of 11 ankles, an acute injury group of 12 ankles that underwent MRI a month after injury, and a chronic injury group of 41 ankles that underwent MRI more than 3 months after injury. Using a 3.0-T MRI system, imaging was done with fast imaging employing steady-state acquisition cycled phases. Oblique sagittal images that most clearly depicted the entire anterior talofibular ligament (ATFL) and CFL were prepared manually and evaluated using a workstation.

RESULTS

In the healthy group, both the ATFL and CFL were clearly and entirely visualized. The mean width in the central portion was 4.0 ± 1.0 mm in the ATFL and 4.8 ± 0.6 mm in the CFL. 3D MRI in the acute injury group showed findings of diffuse swelling with hyperintensity in the ATFL of all patients. The CFL in 7 of 12 ankles showed findings of diffuse swelling with hyperintensity. In the chronic injury group, morphological abnormalities of the ATFL were seen in 19 of 41 ankles. The ligament signal disappeared in 2 ankles, thinned in 4 ankles, and showed swelling in 13 ankles. Morphological abnormalities of the CFL were seen in 17 of 41 ankles. The ligament signal disappeared in 1 ankle, thinned in 2 ankles, and showed swelling in 14 ankles.

CONCLUSION

3D MRI may be a useful modality to visualize both the ATFL and the CFL.

Lower Signal Intensity of the Anterior Talofibular Ligament is Associated with a Higher Rate of Return to Sport After ATFL Repair for Chronic Lateral Ankle Instability

BACKGROUND

The treatment strategy for anterior talofibular ligament (ATFL) injury is usually determined by the ATFL remnant condition during surgery. Preoperative magnetic resonance imaging (MRI)-based signal intensity of the ATFL remnant, represented by the signal/noise ratio (SNR) value, can reveal the ATFL remnant condition. Thus far, there is a lack of evidence regarding the relationship between the ATFL remnant condition and functional outcomes.

PURPOSE/HYPOTHESIS

The purpose was to quantitatively evaluate whether the MRI-based ATFL ligament SNR value is related to functional outcomes after ATFL repair for ankles with chronic lateral ankle instability. The hypothesis was that a lower preoperative SNR is related to a better clinical outcome, particularly a higher rate of return to sport.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

First, a preliminary study was performed to measure the ATFL SNR in preoperative MRI, the results of which suggested that a preoperative SNR >10.4 was indicative of a poor ATFL condition. Then, a cohort study was retrospectively performed with consecutive patients who underwent open repair of ATFL injuries between January 2009 and August 2014. Accordingly, the patients were divided into 2 groups: high SNR (HSNR; ≥10.4) and low SNR (LSNR; <10.4). Functional outcomes based on the American Orthopaedic Foot and Ankle Society (AOFAS) score, Karlsson Ankle Functional Score (KAFS), and Tegner Activity Scale were then compared between the HSNR group and the LSNR group.

RESULTS

Ultimately, 70 patients were available for the final follow-up: 37 in the HSNR group and 33 in the LSNR group. No significant difference was detected between the HSNR group and the LSNR group in terms of the AOFAS score, KAFS, or Tegner Activity Scale (P > .05 for all) preoperatively. At the final follow-up, the mean ± SD AOFAS score in the LSNR group (92 ± 6) was higher than that in the HSNR group (87 ± 12), although no significant difference was detected postoperatively (P = .16). The mean KAFS in the LSNR group (94 ± 7) was significantly higher than that in the HSNR group (88 ± 11) postoperatively (P = .03). At follow-up, the mean Tegner score in the LSNR group (6; range, 3-7) was significantly higher than that in the HSNR group (5; range, 1-8) postoperatively (P = .03). Patients in the LSNR group had a significantly higher percentage of sports participation than those in the HSNR group (91% vs 65%, P = .02) postoperatively.

CONCLUSION

A lower signal intensity in the ATFL ligament based on preoperative MRI is associated with a better clinical outcome, particularly a higher rate of return to sport.

Reliability and validity of different ankle MRI scanning planes for the anterior talofibular ligament injury diagnosis: a cadaveric study

Background

The objective of the current study is to compare reliability, accuracy, sensitivity, and specificity in magnetic resonance imaging (MRI) evaluation of anterior talofibular ligament (ATFL) among the routine axial scanning plane, oblique axial-coronal scanning plane, and oblique axial-sagittal scanning plane.

Methods

Twenty cadaveric feet were studied. ATFL was exposed before scanning. Routine axial, oblique axial-coronal, and oblique axial-sagittal MRI scanning of 20 ATFL-intact cadaveric feet were acquired utilizing a 1.5-T MRI unit. The scans were repeated on the 20 cadaveric feet after the ATFL was artificially injured. In total, 120 sets of MR images were obtained and were randomly numbered. Three independent observers who were blinded to the experiment evaluated the images. Interobserver agreement, sensitivity, specificity, and accuracy were calculated and compared between different scanning planes utilizing the McNemar test.

Results

The interobserver agreement was fair to good (kappa, 0.55 to 0.65) in the routine axial plane, fair to good (kappa, 0.557 to 0.75) in the oblique axial-sagittal plane, and excellent (kappa, 0.85 to 0.95) in the oblique axial-coronal plane. The accuracy was significantly higher when utilizing oblique axial-coronal MRI scanning than routine axial MRI scanning (reader 1: p = .018; reader 2: p = .005).

Conclusions

The diagnostic accuracy of oblique axial-coronal plane MRI was higher than the routine axial plane concerning ATFL injury, and the interobserver agreement was excellent. The oblique axial-coronal plane could be added to the MRI scanning protocol during clinical practices to improve the diagnostic accuracy of ATFL injury.

Evaluation of diagnostic value and T2-weighted three-dimensional isotropic turbo spin-echo (3D-SPACE) image quality in comparison with T2-weighted two-dimensional turbo spin-echo (2D-TSE) sequences in lumbar spine MR imaging

Purpose

to evaluate diagnostic value and image quality of T2-weighted Three-dimensional isotropic turbo spin-echo (SPACE) in comparison with T2-weighted two-dimensional turbo spin-echo (TSE) sequences for comprehensive evaluation of lumbar spine pathologies.

Materials and methods

Thirty-five participants with lumbar discopathy were examined on a 1.5-T MRI system with both 2D TSE and 3D SPACE sequences. Obtained images were analyzed with synedra view personal (V 17.0.0.2) software in terms of calculating image quality factors such as signal to noise ratio (SNR) and contrast to noise ratio (CNR) for selected regions of interest. In addition, images were referred to radiologists to report their pathologic indexes. The visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen's kappa (k) and Wilcoxon signed rank test was used for the statistical analysis.

Results

In this study, the 3D SPACE T2-weighted sequence showed significant higher SNR and CNR as well as visibility in all of the regions of interest except vertebrae and intervertebral discs (p-value < 0.05). Inter-observer agreement for visibility of regions of interest was substantial and perfect (k > 0.6). Also, inter-observer and inter-method agreements for pathologic indexes were substantial and perfect for all of the pathologic indexes (k > 0.6). Inter-observer agreement for 3D SPACE sequence was higher (k = 0.793) in comparison with 2D-TSE sequence (k = 0.603). 3D SPACE sequence and its multi-planar reconstructions (MPR) scan time were less (192 s) than 2D TSE in the sagittal, axial and coronal planes (209 s).

Conclusion

3D SPACE sequence for lumbar spine MRI proved to have higher SNR, CNR, and visibility for all regions of lumbar spine except vertebrae and disc. Inter-observer and inter-method agreements for pathologic indexes between 3D SPACE and 2D TSE sequences were substantial and 3D SPACE had a higher inter-observer agreement and less scan time. Therefore, T2 weighted 3D SPACE sequence, and its MPR might be an excellent alternative for 2D TSE in sagittal, axial, and coronal planes, especially for patients with abnormal curvature of the lumbar spine.

Agreement between arthroscopic and imaging study findings in chronic anterior talo-fibular ligament injuries

BACKGROUND

Imaging studies done to evaluate chronic ankle instability (CAI) often fail to accurately detail injuries to the anterior talo-fibular ligament (ATFL) and may, therefore, also fail to provide guidance for selecting the most appropriate surgical procedure. Arthroscopy is now an indispensable tool for accurately diagnosing ATFL injuries. This study looked at agreement between arthroscopy and imaging study assessments of ATFL injuries. The primary objective was to adapt an arthroscopic classification of chronic ATFL lesions to the pre-operative imaging study findings in order to estimate the performance of computed tomography (CT)-arthrography, ultrasonography, and magnetic resonance imaging (MRI) in diagnosing ATFL lesions, using arthroscopy as the reference standard.

HYPOTHESIS

Agreement between arthroscopic and imaging findings of chronic ATFL injuries can be assessed by using a shared classification developed from the arthroscopic evaluation, used as the reference standard.

MATERIAL AND METHODS

A prospective multicentre study was conducted in 286 patients with arthroscopically-treated CAI. In each patient, the arthroscopic assessment of the ATFL was compared to the pre-operative findings by CT-arthrography, ultrasonography, and MRI. A classification of ATFL lesions based on the arthroscopic assessment was used to analyse the imaging studies. Using this classification, two independent observers compared the findings and evaluated the agreement between arthroscopy and imaging studies.

RESULTS

Of the 286 patients, 157 had complete information on the arthroscopic assessment and on pre-operative imaging studies and were included in the analysis. Imaging studies were CT-arthrography in 49 patients, ultrasonography in 63 patients, and MRI in 45 patients; both ultrasonography and MRI were performed in 3 patients. Agreement with arthroscopy was 82% and 88.5% for CT-arthrography, 66.7% and 76.2% for ultrasonography, 70.5% and 79.5% for MRI, and 73.4% and 81.2% for all imaging studies pooled.

DISCUSSION

Arthroscopy plays a crucial role in the definitive assessment of ligament lesions in patients with CAI, as it supplies far more accurate information than any of the current imaging studies and, in addition, provides a dynamic evaluation of the ligaments and assesses mechanical strength. In the study population, a simple arthroscopic evaluation consistently visualised ATFL lesions, thereby either correcting or confirming the pre-operative imaging study findings. Importantly, the arthroscopic assessment provided more accurate information on the lesions and quality of the ATFL compared to the imaging studies. Arthroscopy has improved our knowledge of chronic ATFL lesions and allowed the development of a simple but accurate four-grade classification of direct relevance to choosing the optimal therapeutic procedure. This classification must be disseminated among radiologists to improve the diagnostic performance of pre-operative imaging studies, assist surgeons in selecting the most appropriate ankle-stabilising procedure, and improve patient information. Further studies are needed to confirm the promising results reported here and the usefulness of this common arthroscopy and imaging-study classification for chronic ATFL lesions.

LEVEL OF EVIDENCE

II.

Imaging diagnosis for chronic lateral ankle ligament injury: a systemic review with meta-analysis

Background

Various imaging techniques have been utilized for the diagnosis of chronic lateral ankle ligament injury. This systemic review will explore the effectiveness of different imaging techniques in diagnosing chronic lateral ankle ligament injury.

Methods

Relative studies were retrieved after searching 3 databases (MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trails). Eligible studies were summarized. Data were extracted to calculate pooled sensitivity and specificity of magnetic resonance imaging (MRI), ultrasonography (US), stress radiography, and arthrography.

Results

Fifteen studies met our inclusion and exclusion criteria. A total of 695 participants were included. The pooled sensitivities in diagnosing chronic ATFL injury were 0.83 [0.78, 0.87] for MRI, 0.99 [0.96, 1.00] for US, and 0.81 [0.68, 0.90] for stress radiography. The pooled specificities in diagnosing chronic ATFL injury were 0.79 [0.69, 0.87] for MRI, 0.91 [0.82, 0.97] for US, and 0.92 [0.79, 0.98] for stress radiography. The pooled sensitivities in diagnosing chronic CFL injury were 0.56 [0.46, 0.66] for MRI, 0.94 [0.85, 0.98] for US, and 0.90 [0.73, 0.98] for arthrography. The pooled specificities in diagnosing chronic CFL injury were 0.88 [0.82, 0.93] for MRI, 0.91 [0.80, 0.97] for US, and 0.90 [0.77, 0.97] for arthrography.

Conclusion

This systematic review with meta-analysis investigated the accuracy of imaging for the diagnosis of chronic lateral ankle ligament injury. Ultrasound manifested high diagnostic accuracy in diagnosing chronic lateral ankle ligament injury. Clinicians should be aware of the limitations of MRI in detecting chronic CFL injuries.

Comparison of two-dimensional fast spin echo T2 weighted sequences and three-dimensional volume isotropic T2 weighted fast spin echo (VISTA) MRI in the evaluation of triangular fibrocartilage of the wrist

OBJECTIVE

To compare image quality of three-dimensional volume isotropic T₂ weighted fast spin echo (3D VISTA) and two-dimensional (2D) T₂ weighted images (T2WI) for evaluation of triangular fibrocartilage (TFC) and to investigate whether 3D VISTA can replace 2D T₂ WI in evaluating TFC injury.

METHODS

This retrospective study included 69 patients who received wrist MRIs using both 2D T₂ WI and 3D VISTA techniques for assessment of wrist pathology, including TFC injury. Two radiologists measured the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) of the two sequences. The anatomical identification score and diagnostic performance were independently assessed by two interpreters. The diagnostic abilities of 3D VISTA and 2D T₂ WI were analysed by sensitivity, specificity and accuracy for diagnosing TFC injury using surgically or clinically confirmed diagnostic reference standards.

RESULTS

17 cases (25%) were classified as having TFC injury. 2 cases (12%) were diagnosed surgically, and 15 cases (88%) were diagnosed by physical examination. 52 cases (75%) were diagnosed as having intact TFC. 8 of these cases (15%) were surgically confirmed, while the others were diagnosed by physical examination and clinical findings. The 3D VISTA images had significantly higher SNR and CNR values for the TFC than 2D T₂ WI images. The scores of 3D VISTA's total length, full width and sharpness were similar to those of 2D T₂ WI. We were unable to find a significant difference between 3D VISTA and 2D T₂ WI in the ability to diagnose TFC injury.

CONCLUSION

3D VISTA image quality is similar to that of 2D T₂ WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment. Advances in knowledge: 3D VISTA image quality is similar to that of 2D T₂ WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment.

Quantitative magnetic resonance imaging (MRI) analysis of anterior talofibular ligament in lateral chronic ankle instability ankles pre- and postoperatively

BACKGROUND

The aim of this study was to quantitatively evaluate and characterize the dimension and signal intensity of anterior talofibular ligament (ATFL) using 3.0 T MRI in the mechanical ankle instability group pre- and postoperatively.

METHODS

A total of 97 participants were recruited retrospectively in this study, including 56 with mechanical chronic ankle instability (CAI group) and 41 without ankle instability (Control group). All the subjects accepted MRI preoperatively. Among the 56 CAI patients, 25 patients, who accepted modified Broström repair of ATFL, underwent a MRI scan at follow-up. The ATFL dimension (length and width) and signal/noise ratio (SNR) were measured based on MRI images. The results of the MRI studies were then compared between groups.

RESULTS

The CAI group had a significantly higher ATFL length (p = 0.03) or ATFL width (p < 0.001) compared with the control group. The mean SNR value of the CAI group was significantly higher than that of the control group (p = 0.006). Furthermore, the mean SNR value of the ATFL after repair surgery (8.4 ± 2.4) was significantly lower than that of the ATFL before surgery (11.2 ± 3.4) (p < 0.001). However, no significant change of ATFL length or ATFL width were observed after repair surgery.

CONCLUSIONS

CAI ankles had a higher ATFL length or width as well as higher signal intensity compared with stable ankles. After repair surgery, the mean SNR value of the ATFL decreased, indicating the relaxed ATFL becomes tight postoperatively.

New Techniques in MR Imaging of the Ankle and Foot

Foot and ankle disorders are common in everyday clinical practice. MR imaging is frequently required for diagnosis given the variety and complexity of foot and ankle anatomy. Although conventional MR imaging plays a significant role in diagnosis, contemporary management increasingly relies on advanced imaging for monitoring therapeutic response. There is an expanding need for identification of biomarkers for musculoskeletal tissues. Advanced imaging techniques capable of imaging these tissue substrates will be increasingly used in routine clinical practice. Radiologists should therefore become familiar with these innovative MR techniques. Many such techniques are already widely used in other organ systems.

Activity Level and Function 2 Years After Anterior Talofibular Ligament Repair: A Comparison Between Arthroscopic Repair and Open Repair Procedures

BACKGROUND

The open modified Broström anatomic repair technique is widely accepted as the reference standard for lateral ankle stabilization. Despite recent increases in publications regarding arthroscopic repair of the anterior talofibular ligament (ATFL) for treatment of chronic ankle instability, research is lacking that compares the functional outcomes between arthroscopic repair and open repair procedures for chronic ankle instability.

PURPOSE

To compare function and activity level after arthroscopic repair versus open repair of the ATFL in patients with lateral ankle instability.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients who underwent arthroscopic or open surgical Broström repair of the ATFL between January 2012 and August 2014 were invited to participate in this study. All of the patients had consented for arthroscopic repair if feasible. In cases in which arthroscopic repair was impossible, the open modified Broström procedure was performed after arthroscopy. Patients accepted a systematic rehabilitation program postoperatively. American Orthopaedic Foot and Ankle Society (AOFAS) score, Karlsson Ankle Functional Score (KAFS), and Tegner activity score were used to evaluate ankle function preoperatively and at a minimum follow-up of 2 years. Magnetic resonance imaging (MRI) was performed to evaluate the signal to noise ratio (SNR) of the repaired ATFL.

RESULTS

A total of 60 patients were included in this study. They were assigned to 1 of 2 groups according to their surgical procedure: 23 patients underwent arthroscopic repair (arthroscopic group) and 37 patients underwent open repair (open group). No patient in either group had ankle instability at follow-up postoperatively. After surgery, the AOFAS score ( P < .001), KAFS ( P < .001), and Tegner activity score ( P < .001) increased significantly in both groups. However, no significant difference was found in AOFAS score (93.3 ± 8.9 vs 92.4 ± 8.6; P = .7), KAFS (90.3 ± 12.5 vs 89.4 ± 10.6; P = .75), and Tegner score (5 ± 2 vs 5 ± 2; P = .61) between the arthroscopic group and the open group, respectively. As well, no significant difference was found in the mean SNR value of ATFL between the arthroscopic group and the open group (9.1 ± 2.7 vs 8.8 ± 2.3; P = .39, respectively).

CONCLUSION

When compared with open lateral ankle repair, arthroscopic repair of lateral ankle ligament when feasible produced similarly favorable outcomes. Arthroscopic ATFL repair, as a minimally invasive technique, provided favorable outcomes.

Advanced MRI Techniques for the Ankle

OBJECTIVE

The purposes of this article are to present a state-of-the-art routine protocol for MRI of the ankle, to provide problem-solving tools based on specific clinical indications, and to introduce principles for the implementation of ultrashort echo time MRI of the ankle, including morphologic and quantitative assessment.

CONCLUSION

Ankle injury is common among both athletes and the general population, and MRI is the established noninvasive means of evaluation. The design of an ankle protocol depends on various factors. Higher magnetic field improves signal-to-noise ratio but increases metal artifact. Specialized imaging planes are useful but prolong acquisition times. MR neurography is useful, but metal reduction techniques are needed whenever a metal prosthesis is present. An ultrashort echo time sequence is a valuable tool for both structural and quantitative evaluation.

Comparison of oblique coronal images in knee of three-dimensional isotropic T2-weighted turbo spin echo MRI versus two-dimensional fast spin echo T2-weighted sequences for evaluation of posterior cruciate ligament injury

OBJECTIVE

To compare image quality between three-dimensional volume isotropic turbo spin echo acquisition (3D VISTA) with the posterior cruciate ligament (PCL) view and two-dimensional (2D) fast spin echo (FSE) for evaluation of PCL injury.

METHODS

This retrospective study included 60 patients with clinical suspicion of PCL injury who underwent both 2D FSE and 3D VISTA of the knee between January 2015 and December 2015. The diagnostic performance of each oblique coronal view and the combined images was evaluated for sensitivity, specificity and accuracy for diagnosing a PCL tear. The arthroscopically confirmed diagnoses were used as the reference standard. Data were analyzed using the McNemar test.

RESULTS

The mean contrast-to-noise ratio was significantly higher for 3D VISTA than for 2D FSE. The two imaging modalities did not differ significantly in anatomical identification ability, with the exception of margin sharpness, which was inferior for 3D VISTA with Reader 2 (p = 0.038). When we classified the diagnoses of PCL injury as normal or abnormal, there were no significant differences in sensitivity, specificity or accuracy between the PCL view of 3D VISTA and 2D FSE images (p > 0.05).

CONCLUSION

3D VISTA had a superior contrast-to-noise ratio than 2D FSE and similar image quality in the evaluation of the PCL. The PCL view of 3D VISTA has the same diagnostic ability as 2D FSE in the diagnosis of PCL injury and can thus replace 2D FSE. Advances in knowledge: The oblique coronal view 3D VISTA MRI has similar diagnostic ability to 2D FSE in the diagnosis of PCL injury, and therefore 3D VISTA image can replace 2D FSE.