MR appearance of cartilage defects of the knee: preliminary results of a spiral CT arthrography-guided analysis

Morphological assessment of cartilage and osteoarthritis in clinical practice and research: Intermediate-weighted fat-suppressed sequences and beyond

Magnetic resonance imaging (MRI) is widely regarded as the primary modality for the morphological assessment of cartilage and all other joint tissues involved in osteoarthritis. 2D fast spin echo fat-suppressed intermediate-weighted (FSE FS IW) sequences with a TE between 30 and 40ms have stood the test of time and are considered the cornerstone of MRI protocols for clinical practice and trials. These sequences offer a good balance between sensitivity and specificity and provide appropriate contrast and signal within the cartilage as well as between cartilage, articular fluid, and subchondral bone. Additionally, FS IW sequences enable the evaluation of menisci, ligaments, synovitis/effusion, and bone marrow edema-like signal changes. This review article provides a rationale for the use of FSE FS IW sequences in the morphological assessment of cartilage and osteoarthritis, along with a brief overview of other clinically available sequences for this indication. Additionally, the article highlights ongoing research efforts aimed at improving FSE FS IW sequences through 3D acquisitions with enhanced resolution, shortened examination times, and exploring the potential benefits of different magnetic field strengths. While most of the literature on cartilage imaging focuses on the knee, the concepts presented here are applicable to all joints. KEY POINTS: 1. MRI is currently considered the modality of reference for a "whole-joint" morphological assessment of osteoarthritis. 2. Fat-suppressed intermediate-weighted sequences remain the keystone of MRI protocols for the assessment of cartilage morphology, as well as other structures involved in osteoarthritis. 3. Trends for further development in the field of cartilage and joint imaging include 3D FSE imaging, faster acquisition including AI-based acceleration, and synthetic imaging providing multi-contrast sequences.

Synthesis of vibroarthrographic signals in knee osteoarthritis diagnosis training

Background

Vibroarthrographic (VAG) signals are used as useful indicators of knee osteoarthritis (OA) status. The objective was to build a template database of knee crepitus sounds. Internships can practice in the template database to shorten the time of training for diagnosis of OA.

Methods

A knee sound signal was obtained using an innovative stethoscope device with a goniometer. Each knee sound signal was recorded with a Kellgren–Lawrence (KL) grade. The sound signal was segmented according to the goniometer data. The signal was Fourier transformed on the correlated frequency segment. An inverse Fourier transform was performed to obtain the time-domain signal. Haar wavelet transform was then done. The median and mean of the wavelet coefficients were chosen to inverse transform the synthesized signal in each KL category. The quality of the synthesized signal was assessed by a clinician.

Results

The sample signals were evaluated using different algorithms (median and mean). The accuracy rate of the median coefficient algorithm (93 %) was better than the mean coefficient algorithm (88 %) for cross-validation by a clinician using synthesis of VAG.

Conclusions

The artificial signal we synthesized has the potential to build a learning system for medical students, internships and para-medical personnel for the diagnosis of OA. Therefore, our method provides a feasible way to evaluate crepitus sounds that may assist in the diagnosis of knee OA.

MRI EVALUATION OF KNEE CARTILAGE

Through the ability of magnetic resonance imaging (MRI) to characterize soft tissue noninvasively, it has become an excellent method for evaluating cartilage. The development of new and faster methods allowed increased resolution and contrast in evaluating chondral structure, with greater diagnostic accuracy. In addition, physiological techniques for cartilage assessment that can detect early changes before the appearance of cracks and erosion have been developed. In this updating article, the various techniques for chondral assessment using knee MRI will be discussed and demonstrated.

Diagnostic performance of flat-panel CT arthrography for cartilage defect detection in the ankle joint: comparison with MDCT arthrography with gross anatomy as the reference standard

OBJECTIVE

The purpose of this study is to compare the diagnostic performance and radiation exposure of flat-panel CT arthrography for cartilage defect detection in the ankle joint to standard MDCT arthrography, using gross anatomy and thermoluminescent dosimetry as reference standards.

MATERIALS AND METHODS

Ten cadaveric ankle specimens were obtained from individuals who had willed their bodies to science. Five milliliters of a mixture of diluted ioxaglate and saline were injected. Specimens were examined consecutively with the use of flat-panel CT and MDCT. Radiation doses of flat-panel CT and MDCT were recorded using thermoluminescent dosimeters. Flat-panel CT and MDCT arthrography examinations were blinded and randomly evaluated by two musculoskeletal radiologists in consensus. In each ankle specimen, eight cartilage areas were assessed separately: medial talar surface, medial talar trochlea, lateral talar trochlea, lateral talar surface, tibial malleolus, medial tibial pla-fond, lateral tibial plafond, and fibular malleolus. Findings at flat-panel CT and MDCT arthrography were compared with macroscopic assessments in 80 cartilage areas.

RESULTS

For the detection of cartilage lesions, flat-panel CT showed a sensitivity of 80%, specificity of 98%, and accuracy of 94%, and MDCT arthrography showed a sensitivity of 55%, specificity of 98%, and accuracy of 88%. Flat-panel CT and MDCT arthrography showed almost perfect (κ = 0.83) and substantial (κ = 0.65) agreement, respectively, with anatomic examination. Radiation dose was significantly lower for flat-panel CT (mean, 2.1 mGy; range, 1.1-3.0 mGy) than for MDCT (mean, 47.2 mGy; range, 39.3-53.8 mGy) (p < 0.01).

CONCLUSION

Flat-panel CT arthrography is accurate for detecting cartilage defects in the ankle joint and is an alternative to MDCT arthrography that may have better diagnostic performance and may permit the use of a lower radiation dose.

Diagnostic performance of CT-arthrography and 1.5T MR-arthrography for the assessment of glenohumeral joint cartilage: a comparative study with arthroscopic correlation

PURPOSE

To compare the diagnostic performance of multi-detector CT arthrography (CTA) and 1.5-T MR arthrography (MRA) in detecting hyaline cartilage lesions of the shoulder, with arthroscopic correlation.

PATIENTS AND METHODS

CTA and MRA prospectively obtained in 56 consecutive patients following the same arthrographic procedure were independently evaluated for glenohumeral cartilage lesions (modified Outerbridge grade ≥2 and grade 4) by two musculoskeletal radiologists. The cartilage surface was divided in 18 anatomical areas. Arthroscopy was taken as the reference standard. Diagnostic performance of CTA and MRA was compared using ROC analysis. Interobserver and intraobserver agreement was determined by κ statistics.

RESULTS

Sensitivity and specificity of CTA varied from 46.4 to 82.4 % and from 89.0 to 95.9 % respectively; sensitivity and specificity of MRA varied from 31.9 to 66.2 % and from 91.1 to 97.5 % respectively. Diagnostic performance of CTA was statistically significantly better than MRA for both readers (all p ≤ 0.04). Interobserver agreement for the evaluation of cartilage lesions was substantial with CTA (κ = 0.63) and moderate with MRA (κ = 0.54). Intraobserver agreement was almost perfect with both CTA (κ = 0.94-0.95) and MRA (κ = 0.83-0.87).

CONCLUSION

The diagnostic performance of CTA and MRA for the detection of glenohumeral cartilage lesions is moderate, although statistically significantly better with CTA.

KEY POINTS

• CTA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. • MRA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. • CTA is more accurate than MRA for detecting cartilage substance loss.

MR arthrography of the shoulder: optimizing pulse sequence protocols for the evaluation of cartilage and labrum

OBJECTIVES

To compare axial T1weighted fat-saturated (T1w fs) and T1w non-fs sequences, and coronal T1w-fs and T2w-fs sequences, for evaluation of cartilage and labrum using CT arthrography (CTA) as the reference.

METHODS

Patients had MR arthrography (MRA) and CTA of the shoulder on the same day. Cartilage was assessed for superficial and full thickness focal and diffuse damage. Labral lesions were graded for Bankart variants and SLAP lesions. CTA images were read for the same features. The diagnostic performance of MRA including area under the curve (AUC) was evaluated against CTA.

RESULTS

When comparing axial sequences, the diagnostic performance for cartilage lesion detection on T1w non-fs was 61.9% (sensitivity) 93.6% (specificity) and 89.5% (accuracy) with AUC 0.782, while that for T1w fs was 61.9%, 94.0%, 89.8% and 0.783. For labral assessment, it was 89.1%, 93.0%, 91.4% and 0.919 for T1w non-fs, and 89.9%, 94.0%, 92.6% and 0.922 for T1w fs. Comparing coronal sequences, diagnostic performance for cartilage was 42.5%, 97.5%, 89.8% and 0.702 for T1w fs, and 38.4%, 98.7%, 90.2%, and 0.686 for T2w fs. For the labrum it was 85.1%, 87.5%, 86.2%, and 0.868 for T1w fs, and 75.7%, 97.5%, 80.8% and 0.816 for T2w fs.

CONCLUSIONS

Axial T1w fs and T1w non-fs sequences are comparable in their ability to diagnose cartilage and labral lesions. Coronal T1w fs sequence offers slightly higher sensitivity but slightly lower specificity than T2w fs sequence for diagnosis of cartilage and labral lesions.

Imaging of osteochondritis dissecans

Osteochondritis dissecans (OCD) is a localized process that affects the subchondral bone and can progress to the overlying articular cartilage. The cause of this lesion remains elusive. With the vague clinical symptoms and signs of OCD, imaging plays a vital role in making the diagnosis and helping with the prognosis of OCD lesions. This article reviews current imaging modalities for the assessment of OCD including conventional radiography, nuclear medicine, computed tomography (CT), CT arthrography, magnetic resonance (MR) and MR arthrography. The role of imaging in evaluating healing of the OCD and articular congruity after surgical and nonsurgical management is discussed.

An acoustical evaluation of knee sound for non-invasive screening and early detection of articular pathology

Knee sound signals generated by knee movement are sometimes associated with degeneration of the knee joint surface and such sounds may be a useful index for early disease. In this study, we detected the acoustical parameters, such as the fundamental frequency (F0), mean amplitude of the pitches, and jitter and shimmer of knee sounds, and compared them according to the pathological conditions. Six normal subjects (4 males and 2 females, age: 28.3 ± 2.3 years) and 11 patients with knee problems were enrolled. The patients were divided into the 1st patient group (5 males and 1 female, age: 30.2 ± 10.3 years) with ruptured wounds of the meniscus and 2nd patient group (2 males and 3 females, age: 42.1 ± 16.2 years) with osteoarthritis. The mean values of F0, jitter and shimmer of the 2nd patient group were larger than those of the normal group, whereas those of the 1st patient group were smaller (p < 0.05). Also, the F0 and jitter in the standing position were larger than those in the sitting position in both the 1st and 2nd patient groups (p < 0.05). These results showed good potential for the non-invasive diagnosis and early detection of articular pathologies via an auscultation.

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.

[Imaging examinations of the patellofemoral joint]

Lesions in the patellofemoral region can be caused by trauma, chronic overloading, and especially regarding cartilage alterations by normal aging or pathologic processes. Very commonly these lesions lead to early arthrosis. An accurate clinical evaluation in all these patients is recommended. The combination of clinical information and radiological examinations should end up with an exact diagnosis.As part of the radiological evaluation of complaints of the patellofemoral region MR imaging is of special value since this method allows direct visualization of all intra- and extra-articular structures and their alterations, ultimately aiding in planning sufficient therapy. Moreover, is it possible to exclude pathology by MR imaging, which helps to prevent useless treatment and surgical procedures.

An initial qualitative study of dual-energy CT in the knee ligaments

OBJECTIVE

To study the clinical application of dual-energy CT (DECT) in the knee ligaments.

METHODS

Twelve cases (24 knees) were scanned using dual-energy CT for the knee. Two- and three-dimensional images were used for display in all cases by means of multi-planar reformation (MPR) and volume rendering technique (VRT). All images were ranked by two radiologists according to the grade of knee ligament displayed, the definition of edge and attachment points of the knee ligament.

RESULTS

The partial ligaments of 24 knees, such as the patellar ligament, fibular collateral ligament, anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were clearly displayed; the tibial collateral ligament was not satisfactorily displayed. The transversal ligaments, such as lateral patellar retinaculum and medial patellar retinaculum, and the posterior ligament, such as oblique popliteal ligament could not be shown clearly.

CONCLUSION

The dual-energy CT is a new and valuable tool to qualitatively display the main ligaments of the knee.

Cartilage lesions of the glenohumeral joint: diagnostic effectiveness of multidetector spiral CT arthrography and comparison with arthroscopy

This study assessed the diagnostic effectiveness of multidetector spiral CT arthrography (MDCTa) in detecting hyaline cartilage abnormalities of the shoulder joint, with correlation to arthroscopy. Shoulder MDCTa images prospectively obtained in 22 consecutive patients (mean age, 50 years; age range, 23-74 years; 12 female, 10 male) were evaluated for glenohumeral cartilage lesions. Two musculoskeletal radiologists independently analysed the cartilage surfaces of the humeral head and of the glenoid fossa in nine anatomical surface areas. Observations of MDCTa were compared to arthroscopic findings. The sensitivity and specificity of MDCTa for grade 2 (substance loss <50%) or higher and grade 3 (substance loss >or=50%) or higher cartilage lesions, the Spearman correlation coefficient between arthrographic and arthroscopic grading, and K statistics for assessing Intra and Interobserver reproducibility were determined. At MDCTa, sensitivities and specificities ranged between 80% and 94% for the detection of grade 2 or higher cartilage lesions, and between 88% and 98% for the detection of grade 3 or higher cartilage lesions. Spearman correlation coefficients between MDCTa and arthroscopic grading of articular surfaces ranged between 0.532 and 0.651. Interobserver agreement was moderate for grading all articular surfaces (kappa = 0.457), but substantial to almost perfect for detecting lesions with substance loss (kappa, 0.618-0.876). In conclusion, MDCTa is accurate for the study of cartilage surface in the entire shoulder joint. This technique may beneficially impact patient's management by means of selecting the proper treatment approach.

MR Arthrography of the Knee: How, Why, When

MR arthrography combines the techniques of arthrography with MR imaging to benefit from the added imaging information afforded by intra-articular distention. This article reviews technical considerations for MR arthrography, potential complications, indications, pitfalls in imaging diagnosis, and commonly encountered pathology. It is an elegant study that can offer precise diagnostic information in the appropriate clinical setting.

Quantitative cartilage volume measurement using MRI: comparison of different evaluation techniques

This study was aimed to investigate the accuracy and time saving of MRI Argus application in the assessment of cartilage volume in osteoarthritic knees. Twelve knees of patients suffering from osteoarthritis were scanned with a 1.5 T MRI using a 3D gradient echo sequence with selective water excitation. Cartilage volume of the tibial and patellar compartment was determined with a validated multiprocessing computer system (Octane Duo, Silicon Graphics, Mountain View, Calif., USA). The calculated cartilage volumes were compared to the results acquired by the Argus (Siemens Inc., Erlangen, Germany) application software using the MRI data sets. Compared to the multiprocessing computer system a time saving of at least 30 min for cartilage volume determination was achieved. The mean differences of Argus versus the multiprocessing computer system were 4.26+/-0.84 and 7.80+/-0.87% for the medial and lateral tibial plateau and 5.94+/-0.59% for the patella (no statistical significant difference; P>0.05). The applied Argus software can be used for fast and accurate determination of cartilage volume in the knee joint.

Comparison of multislice CT arthrography and MR arthrography for the detection of articular cartilage lesions of the elbow

The objective of this study was to compare the value of multislice CT arthrography and MR arthrography in the assessment of cartilage lesions of the elbow joint. Twenty-six cadaveric elbow specimens were examined with the use of CT arthrography and MR arthrography prior to joint exploration and macroscopic inspection of articular cartilage. Findings at CT and MR arthrography were compared with macroscopic assessments in 104 cartilage areas. At macroscopic inspection, 45 cartilage lesions (six grade 2 lesions, 25 grade 3 lesions, 14 grade 4 lesions) and 59 areas of normal articular cartilage were observed. With macroscopic assessment as the gold standard CT and MR arthrography showed an overall sensitivity/specificity of 80/93% and 78/95% for the detection of cartilage lesions, respectively. Only two of six grade 2 lesions were detected by CT and MR arthrography. For the diagnosis of grade 3 and 4 lesions, the sensitivity/specificity was 87/94% with CT arthrography, and 85/95% with MR arthrography. In an experimental setting multislice CT arthrography and MR arthrography showed a similar performance in the detection of cartilage lesions. Both methods indicated limited value in the diagnosis of grade 2 articular cartilage lesions.

Early changes in experimental osteoarthritis using the Pond-Nuki dog model: technical procedure and initial results of in vivo MR imaging

The purpose of this study was to prove the feasibility of combining in vivo MR imaging with the Pond-Nuki animal model for the evaluation of osteoarthritis. In an experimental study, 24 beagle dogs underwent transection of the anterior cruciate ligament of the left leg (modified Pond-Nuki model). The dogs were randomly assigned into four groups and examined by MRI after 6, 12, 24 and 48 weeks. MR imaging of both knees was performed under general anesthesia with the contralateral joint serving as control. In group 1 (6 weeks postoperatively), the first sign detected on MRI was subchondral bone marrow edema in the posteromedial tibia. After 12 weeks, erosion of the posteromedial tibial cartilage could be observed, followed by meniscus degeneration and osteophytosis after 24 and 48 weeks. The contralateral knee joint showed transient joint effusion, but no significant signs of internal derangement (P<0.001). By combining in vivo MR imaging with the Pond-Nuki model, it is possible to detect early signs of osteoarthritis. The first sign was posteromedial subchondral bone marrow edema in the tibia followed by progressive cartilage degeneration and joint derangement. The in vivo model therefore seems to be suitable for longitudinal studies or monitoring the therapeutic effects of osteoarthritis.