MR Arthrography of the Knee: How, Why, When

SSR white paper: guidelines for utilization and performance of direct MR arthrography

OBJECTIVE

Direct magnetic resonance arthrography (dMRA) is often considered the most accurate imaging modality for the evaluation of intra-articular structures, but utilization and performance vary widely without consensus. The purpose of this white paper is to develop consensus recommendations on behalf of the Society of Skeletal Radiology (SSR) based on published literature and expert opinion.

MATERIALS AND METHODS

The Standards and Guidelines Committee of the SSR identified guidelines for utilization and performance of dMRA as an important topic for study and invited all SSR members with expertise and interest to volunteer for the white paper panel. This panel was tasked with determining an outline, reviewing the relevant literature, preparing a written document summarizing the issues and controversies, and providing recommendations.

RESULTS

Twelve SSR members with expertise in dMRA formed the ad hoc white paper authorship committee. The published literature on dMRA was reviewed and summarized, focusing on clinical indications, technical considerations, safety, imaging protocols, complications, controversies, and gaps in knowledge. Recommendations for the utilization and performance of dMRA in the shoulder, elbow, wrist, hip, knee, and ankle/foot regions were developed in group consensus.

CONCLUSION

Although direct MR arthrography has been previously used for a wide variety of clinical indications, the authorship panel recommends more selective application of this minimally invasive procedure. At present, direct MR arthrography remains an important procedure in the armamentarium of the musculoskeletal radiologist and is especially valuable when conventional MRI is indeterminant or results are discrepant with clinical evaluation.

Magnetic resonance imaging of the knee

Knee pain is frequently seen in patients of all ages, with a wide range of possible aetiologies. Magnetic resonance imaging (MRI) of the knee is a common diagnostic examination performed for detecting and characterising acute and chronic internal derangement injuries of the knee and helps guide patient management. This article reviews the current clinical practice of MRI evaluation and interpretation of meniscal, ligamentous, cartilaginous, and synovial disorders within the knee that are commonly encountered.

AcidoCEST-UTE MRI for the Assessment of Extracellular pH of Joint Tissues at 3 T

OBJECTIVES

The goal of this study was to demonstrate feasibility of measuring extracellular pH in cartilage and meniscus using acidoCEST technique with a 3-dimensional ultrashort echo time readout (acidoCEST-UTE) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Magnetization transfer ratio asymmetry, radiofrequency (RF) power mismatch, and relative saturation transfer were evaluated in liquid phantoms for iopromide, iopamidol, and iohexol over a pH range of 6.2 to 7.8, at various agent concentrations, temperatures, and buffer concentrations. Tissue phantoms containing cartilage and meniscus were evaluated with the same considerations for iopamidol and iohexol. Phantoms were imaged with the acidoCEST-UTE MRI sequence at 3 T. Correlation coefficients and coefficients of variations were calculated. Paired Wilcoxon rank-sum tests were used to evaluate for statistically significant differences.

RESULTS

The RF power mismatch and relative saturation transfer analyses of liquid phantoms showed iopamidol and iohexol to be the most promising agents for this study. Both these agents appeared to be concentration independent and feasible for use with or without buffer and at physiologic temperature over a pH range of 6.2 to 7.8. Ultimately, RF power mismatch fitting of iohexol showed the strongest correlation coefficients between cartilage, meniscus, and fluid. In addition, ratiometric values for iohexol are similar among liquid as well as different tissue types.

CONCLUSIONS

Measuring extracellular pH in cartilage and meniscus using acidoCEST-UTE MRI is feasible.

[MR and CT arthrography in cartilage imaging : Indications and implementation]

BACKGROUND

The imaging of chondral pathologies is an essential part in the work-up of acute and chronic joint diseases. Besides conventional MR imaging, CT and MR arthrography are well-established methods in evaluating articular cartilage. The application of these techniques requires knowledge of indications and safe injection procedures by the performing radiologist.

PURPOSE

Our goal is to describe the techniques of cross-sectional arthrographies of different joints, give an overview of general and joint-specific considerations for practical application as well as provide typical indications for cartilage imaging.

MATERIALS AND METHODS

A selective PubMed literature search concerning "arthrography", "CT arthrography", "MR arthrography", "arthrography cartilage", "arthrography wrist", "arthrography elbow", "arthrography shoulder", "arthrography hip", "arthrography knee", "arthrography ankle", "arthrography complications", "arthrography imaging guidance" "osteochondral lesion", "cartilage imaging" and "cartilage lesion" was performed.

RESULTS AND CONCLUSION

CT and MR arthrography are valuable and safe tools in cartilage imaging. They are useful to verify and specify chondral pathologies, usually after conventional MR imaging, and have an important role in evaluating the stability and therefore in therapeutic decision making of osteochondral lesions. CT arthrography is not only a substitute technique in case of MR contraindications, it can be advantageous in small joints (wrist, elbow, ankle) compared to MR arthrography due to its higher image resolution. Fluoroscopic guided joint puncture is still the most commonly used image guidance method, but the role of ultrasound is steadily increasing. Joint traction in MR arthrography is a promising technique to improve cartilage visualization, though it is not yet used in clinical routine imaging.

Learning curves of two different techniques for the intra-articular injection of the knee joint under fluoroscopic guidance

AIM

The aim of the study was to compare the learning curves of three beginner operators using two different techniques of intra-articular injection of the knee under fluoroscopic guidance with a superolateral approach.

MATERIALS AND METHODS

In total, 177 consecutive patients (72 females (40.7%) and 105 males (59.3%), mean age 42.2 ± 15.0 years) scheduled for a computed tomography (CT) arthrography and without joint effusion on the lateral X-rays were enrolled. They underwent an intra-articular injection of the knee under fluoroscopic guidance with a superolateral approach. Patients were randomly assigned to three different operators, including a junior supervisor and two first-year residents in radiology who never performed an intra-articular injection of the knee before the present study. Procedures in lateral or supine position were randomly assigned to three operators.

RESULTS

There was a higher rate of successful injections with the lateral position (92.1%) than with supine position (80.2%) (odds ratio (OR) 4.52, 95% confidence interval (CI) 1.46-14.0). A significant learning effect was observed for the supine position, while none was observed for the lateral position. Pain and time of fluoroscopy did not differ between the two procedures (p = 0.85 and p = 0.10, respectively). Junior supervisor had a higher rate of successful intra-articular injection compared with the other two operators (p = 0.0072). There was a statistically significant higher rate of extravasation with the supine position (66.3%) than with lateral position (19.7%) (p < 0.0001, OR 0.13, 95% CI 0.06-0.25).

CONCLUSION

The intra-articular injection of the knee under fluoroscopic guidance with the patient in lateral position is an easy technique for operators in training with a low rate of extravasation. Lateral position does not require a supplementary irradiation and does not increase the procedural pain. Personal operator's skill is an independent factor in determining the success of the training.

BAKER'S CYST

Baker's cysts are located in the posteromedial region of the knee between the medial belly of the gastrocnemius muscle and semimembranosus tendon. In adults, these cysts are related to intra-articular lesions, which may consist of meniscal lesions or arthrosis. In children, these cysts are usually found on physical examination or imaging studies, and they generally do not have any clinical relevance. Ultrasound examination is appropriate for identifying and measuring the popliteal cyst. The main treatment approach should focus on the joint lesions, and in most cases there is no need to address the cyst directly. Although almost all knee cysts are benign (Baker's cysts and parameniscal cysts), presence of some signs makes it necessary to suspect malignancy: symptoms disproportionate to the size of the cyst, absence of joint damage (e.g. meniscal tears) that might explain the existence of the cyst, unusual cyst topography, bone erosion, cyst size greater than 5 cm and tissue invasion (joint capsule).

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician.

Matrix-induced autologous chondrocyte implantation of the knee: mid-term and long-term follow-up by MR arthrography

OBJECTIVE

To define magnetic resonance (MR) arthrography imaging findings of matrix-induced autologous chondrocyte implantation (MACI) grafts of the knee in order to describe implant behaviour and to compare findings with validated clinical scores 30 and 60 months after MACI implant.

MATERIALS AND METHODS

Thirteen patients were recruited (10 male, 3 female) with a total number of 15 chondral lesions. Each patient underwent an MACI procedure and MR arthrography 30 and 60 months after surgery. MR arthrography was performed using a dedicated coil with a 1.5-Tesla unit. The status of the chondral implant was evaluated with the modified MOCART scoring scale. The lining of the implant, the integration to the border zone, the surface and structure of the repaired tissue were assessed, and the presence of bone marrow oedema and effusion was evaluated. For clinical assessment, the Cincinnati score was used.

RESULTS

At 60 months, the abnormality showed worsening in 1 out of 15 cases. Integration showed improvement in 3 out of 15 cases, and worsening in 3 out of 15 cases. Two surfaces of the implant showed further deterioration at 60 months, and 1 afflicted implant fully recovered after the same time interval. Implant contrast enhancement at 30 months was seen in 2 out of 15 cases, 1 of which recovered at 60 months. According to the MOCART score, 4 cases were rated 68.4 out of 75 at 30 months and 65 out of 75 at 60 months. The mean clinical score decreased from 8.6 out of 10 at 30 months to 8.1 out of 10 at 60 months.

CONCLUSION

Magnetic resonance arthrography improved the evaluation of implants and facilitated the characterisation of MACI integration with contiguous tissues. The follow-up showed significant changes in MACI, even at 60 months, allowing for useful long-term MR evaluations.

US-guided interventional joint procedures in patients with rheumatic diseases--when and how we do it?

OBJECTIVE

To describe the main indications and the technical steps to perform ultrasound guided procedures in patients with rheumatic diseases. To access procedures accuracy, safety and effectiveness.

MATERIALS AND METHODS

27 patients with pain related to articular complications of rheumatic diseases and according to previous radiographic or US exam were submitted to several US-guided procedures. 42% of patients (n=11) had rheumatoid arthritis, 11% (n=3) spondyloarthropathies, 18% (n=5) psoriatic arthritis, 15% (n=4) undifferentiated arthritis, 3% (n=1) Sjögren syndrome and 11% (n=3) had gout. Described procedures are synovial biopsies, intra-articular injections of corticosteroids, radiation synovectomy and synovial cysts drainage procedures. When a therapeutical procedure was made, patients were evaluated by 2 rheumatologists. Corticosteroids used were Prednisolone and Triamcinolone. Yttrium-90 was used for synovectomy.

RESULTS

In all cases success was achieved with correct needle placement inside the joint. After injection/aspiration symptoms successfully solved with all patients improving their health status. No complications were recorded during follow-up period.

CONCLUSIONS

US-guidance is very reliable to afford a safety procedure always checking the injection, biopsy or aspiration. Guided-biopsy has high success rates obtaining several samples. Thus is also possible to use more powerful/long acting therapeutic drugs aggressive to extra-articular structures avoiding complications.

Imaging of lower limb cartilage

The cartilage of the lower limb joints is exposed to high levels of mechanical stress and therefore is a frequent site of degenerative and traumatic lesions. Magnetic resonance imaging (MRI) is the modality of choice for the assessment of these cartilage lesions. To date, clinically available sequences have focused on morphological defects and cartilage loss. Efforts have been made in recent years to depict cartilage lesions at an earlier stage, with new quantitative sequences focusing on the biochemical assessment of tissue.After a brief review of the hyaline cartilage structure, we review the current morphological imaging methods and the biochemical MRI techniques to assess the cartilage. We then illustrate the application of these MRI sequences for the most common degenerative and traumatic disorders affecting lower limb cartilage.

CT arthrography, MR arthrography, PET, and scintigraphy in osteoarthritis

CT arthrography and MR arthrography are accurate methods for the study of surface cartilage lesions and cartilage loss. They also provide information on subchondral bone and marrow changes, and ligaments and meniscal lesions that can be associated with osteoarthritis. Nuclear medicine also offers new insights in the assessment of the disease. This article discusses the strengths and limitations of CT arthrography and MR arthrography. It also highlights nuclear medicine methods that may be relevant to the study of osteoarthritis in research and clinical practice.

Knee MR-arthrography in assessment of meniscal and chondral lesions

INTRODUCTION

No study, so far in France, has investigated the diagnosis value of knee MR-arthrography since the recent approval of intra-articular gadolinium use, by this country's healthcare authorities. This study objective is to verify the MR-arthrography superiority on conventional knee MRI, in meniscus and cartilage knee lesions diagnosing accuracy both in regard to sensitivity and specificity.

HYPOTHESIS

MR-arthrography, represents in some pathologic situations, a more accurate source of information than conventional MRI.

MATERIALS AND METHODS

Over a 27 months period, 25 patients, scheduled to undergo a knee arthroscopy volunteered, after having been fully informed of the possible interest and risk of the MR-arthrography examination, to participate in this study. Twenty-one of them were finally included since in four cases the surgical indication was not confirmed. The group consisted of 15 males and six females with an average age of 35.7 years. All of them consecutively underwent conventional MRI, MR-arthrography finally followed by arthroscopy. The MRI and MR-arthrograms results were compared to the arthroscopy findings using the nonparametric Kappa test.

RESULTS

To diagnose meniscal tears, statistical agreement measure for MRI with arthroscopy was good (K=0.69) but not as good as the MR-arthrography/arthroscopy agreement which, by itself was excellent (K=0.84). As a diagnosis tool, the sensitivity and specificity of MR-arthrography (respectively 100 and 89.6%) were much higher than the corresponding values observed in conventional MRI (92.3 and 82.8%, respectively) which nonetheless remain satisfactory. The meniscal tears characterization seemed to be better interpreted using MR-arthrography. As far as the chondral lesions in this series, they were predominantly located on the patellar surface and in the medial femorotibial compartment. For diagnosing the latter, the MRI/arthroscopy agreement was good (K=0.70) but not as good as the MR-arthrography/arthroscopy agreement (K=0.805) which can be rated excellent. The detection sensitivity thus increased by 10% with gadolinium intra-articular injection. However, assessment accuracy of the lesions depth was mediocre, with frequent errors for the intermediary stages.

DISCUSSION

Intra-articular gadolinium injection improved MRI performances for numerous reasons: filling the joint, reinforcing the synovial fluid signal, and enhancing anatomic structures contrast on the T1-weighted sequences images. In this study, MR-arthrography appeared to be superior to conventional MRI in meniscal and cartilaginous lesions diagnosis, confirming the results previously obtained in other countries. In light of these results and other data from the literature, MR-arthrography can be indicated as an alternative to CT-arthrography in various clinical situations: detection of recurrent tears on operated menisci, search for cartilaginous lesions or foreign bodies in the joint space, and preoperative assessment before chondral repair procedures. However, conventional MRI remains the reference examination for studying cartilage, because the low resolution of MR-arthrography limits its performances in quantitative assessment of lesions depth.

Advanced MR imaging of the cruciate ligaments

The anterior and posterior cruciate ligaments are crucial stabilizers of the knee. These ligaments are named by the location of their tibial attachments. Each ligament is composed of separate functional bundles that differ in size but are equally important in function. MR imaging is accurate and sensitive, making it the imaging technique of choice for evaluating these ligaments. Acute and chronic injuries involving the cruciate ligaments have typical appearances and associated findings. MR imaging interpretation must take into account atypical injuries and imaging pitfalls. Knowledge of normal ligament reconstruction techniques allows differentiation of the normal postoperative appearance from reconstruction failure and complications. Ligament reconstruction techniques, complications, and appearances are reviewed in this article.

Advanced MR Imaging of the Cruciate Ligaments

The anterior and posterior cruciate ligaments are crucial stabilizers of the knee. These ligaments are named by the location of their tibial attachments. Each ligament is composed of separate functional bundles that differ in size but are equally important in function. MR imaging is accurate and sensitive, making it the imaging technique of choice for evaluating these ligaments. Acute and chronic injuries involving the cruciate ligaments have typical appearances and associated findings. MR imaging interpretation must take into account atypical injuries and imaging pitfalls. Knowledge of normal ligament reconstruction techniques allows differentiation of the normal postoperative appearance from reconstruction failure and complications. Ligament reconstruction techniques, complications, and appearances are reviewed in this article.

Magnetic resonance arthrography

For decades, fluoroscopic arthrography was the only method available to image a joint with contrast enhancement. Advances in CT led to the natural development of CT arthrography. Development of MRI and its capability for multiplanar imaging led to direct magnetic resonance arthrography (MRA). This technique has been performed since 1987 and has surpassed CT arthrography in popularity in the United States. Indirect MRA developed subsequently to offer a less invasive alternative. This article presents an overview of direct MRA and addresses joint-specific issues regarding direct MRA. An overview of indirect MRA also is provided.