Magnetic resonance imaging of the hip

Standard magnetic resonance imaging (MRI) as well as MR arthrography (MRA) have been important diagnostic tools to assess for a spectrum of clinical presentations related to the hip. MRA has allowed the radiologist to closely examine intracapsular structures such as the acetabular labrum. In this article, we provide a general review of soft tissue and osseous anatomy of hips, especially focusing on the MR appearances of the acetabular labrum and the osseous morphology of the greater trochanter and ischial tuberosity with their muscle and tendon attachments. In addition, current topics in recent literature will be discussed such as femoroacetabular impingement (FAI) and rotator cuff tears of the hip.     

髋关节撞击综合征影像表现的初步探讨

目的 探讨髋关节撞击综合征(FAI)的影像表现.方法 回顾性分析经手术证实的9例FAI患者的影像资料,9例患者均行髋关节正侧位X线检查及患髋MR检查,其中1例还接受了患髋关节MR关节造影检查,探讨其影像特征性改变.结果 9例患者X线表现均出现股骨头颈交界处骨性突起或髋臼过度覆盖.MR检查显示9例患者均出现不同程度的髋臼盂唇损伤,均出现在前上盂唇,ⅠA期损伤2例,ⅠB期损伤3例,ⅡA期损伤2例,ⅡB期损伤2例;1例患髋关节MR造影检查显示髋臼前上盂唇内线样裂隙,可见对比剂进入裂隙.2例的股骨头负重区软骨下骨内出现硬化囊变区,手术证实相应部位出现直径2 cm大小的软骨剥脱.结论 MRI可以显示FAI患者髋臼盂唇及关节软骨损伤,有助于早期诊断FAI.     

Conventional 3-T MRI and 1.5-T MR Arthrography of Femoroacetabular Impingement

OBJECTIVE: This article provides a review of femoroacetabular impingement (FAI) and the role MRI is attempting to fulfill in this complex and sometimes controversial condition. A perspective on the current status and on the advantages of 1.5-T MR arthrography is presented, and its usefulness in this setting is compared with the potential of nonarthrographic 3-T MRI. CONCLUSION: With its increasing availability, 3-T MRI has the potential to provide routine, less invasive assessment of the hip for FAI.     

Ferucarbotran (Resovist): a new clinically approved RES-specific contrast agent for contrast-enhanced MRI of the liver: properties,clinical development,and applications

Ferucarbotran (Resovist) is the second clinically approved superparamagnetic iron oxide developed for contrast-enhanced MRI of the liver. The purpose of this review is to provide an overview on the properties, clinical development, and application of ferucarbotran. Safety data obtained during clinical phases I–III revealed a total of 162 adverse events within 1053 patients, of which 75 were classified as possibly, probably, or definitely drug related. The majority of events occurred within the first 3 h (73 of 75) and was of mild intensity. The agent significantly improves the detection of hypovascular focal liver lesions with a comparable sensitivity in lesion detection to CTAP but without a relevant loss in specificity. Furthermore, ferucarbotran leads to a significant improvement of the sensitivity for lesion classification and characterization of the most frequent liver lesions. Contrast-enhanced MRA is not feasible and the angiographic effect is not sufficient to allow for postprocessing of data into maximum intensity projections. Intraindividual studies at low-field (0.2 T) and high-field (1.5 T) showed similar rates for lesion detection. The time window for contrast-enhanced MRI of the liver is at least 1 day up to 4 days. The compound can be regarded as safe and well tolerated. Even bolus injections caused no cardiovascular side effects, lumbar back pain, or clinically relevant laboratory changes. The examination time can be kept short with T1- and T2-weighted pre-contrast sequences, dynamic MRI over 10 min, and finally accumulation phase T2-weighted MRI. Patients who may benefit in particular are surgical candidates for resection, transplantation, or interventional therapies, and patients with liver cirrhosis and/or suspected hepatocellular carcinoma to either exclude malignancy or to define the extent of disease, the location of lesions, and the type of newly detected lesions. Electronic Publication     

In vivo precision of quantitative shoulder cartilage measurements, and changes after spinal cord injury.

Recent advances in MRI have enabled the quantitative assessment of articular cartilage morphology in human joints. In this study, we tested the hypothesis that the precision of quantitative shoulder cartilage measurements is sufficient to detect changes between and within patients, and that shoulder cartilage thickness in paraplegic patients increases due to increased loading. We imaged the shoulders of seven healthy volunteers four times using a coronal 3D, fat-suppressed, gradient-echo sequence. The humeral head cartilage in seven paraplegic patients was evaluated soon after injury and 1 year post injury. A precision of 4.5% (root mean square (RMS) average coefficient of variation (CV) %) was found for shoulder cartilage thickness measurements in the humeral head. Whereas a significant decrease of cartilage thickness (-11%, P < 0.05) was observed in the knee, there was no significant change in articular cartilage thickness in the shoulder (-1.1%). Our data show, for the first time, that articular cartilage of the humeral head can be quantified with acceptable precision in vivo. It was demonstrated that, in contrast to the knee, the articular cartilage morphology of the humeral head changes very little (i.e., there is no significant increase or decrease in thickness) after spinal cord injury (SCI).     

股骨髋臼撞击症的影像学评估

股骨髋臼撞击症（FAI）是引起青年人髋关节运动障碍及髋部疼痛的主要原因之一,与股骨、髋臼解剖形态学异常密切相关,髋关节运动时异常撞击进而导致软骨损伤。X线摄影、CT定量测量及MRI等观察软骨的影像方法可进一步明确FAI的分型,有助于临床诊断治疗。就FAI的影像学典型表现及其定量测量方法予以综述。     

Steady state evaluation of aortic dissections: A feasibility study

PURPOSE: One the main reasons for the limited use of MRI in the evaluation of aortic dissection in emergency conditions is its long execution time. The authors report their experience regarding a new MRI sequence that reduces execution time and avoids the use of contrast medium. MATERIALS AND METHODS: Eighteen haemodynamically stable patients with suspected (16 cases, 3 with confirmed diagnosis of aneurysm) or known aortic dissection (2 cases) underwent in emergency conditions 1.5T MRI with Steady-State sequence (Fast Imaging Employing Steady-State Acquisition: GRE 2D; TR 3.5, TE 1.6; Flip Angle 45, bandwidth 125, matrix 224x224, NEX 1, acquisition time per slice 7 s, thickness 6-8 mm, FOV 38; 2D-GE breath-hold sequence requiring cardiac triggering). The results obtained were compared in terms of diagnostic accuracy and execution time with those of classical MRI examination (black blood T1, FSE T2 and 3D MR-angiography) or multislice CT. RESULTS: The diagnostic accuracy of MRI, both with Steady-State sequence and the 'classical' technique, and multislice CT in the diagnosis of dissection or aneurysm is equal (100%), whereas execution time is 6, 25 and 6 minutes, respectively. Multislice CT proved to be more accurate than Steady-State MRI in evaluating the renal parenchyma and the extension of the dissection to the renal arteries. CONCLUSIONS: The Steady-State MRI sequence provides a diagnosis of aortic dissection or aneurysmal dilatation in a short time and may represent a valuable alternative to CT in emergency settings, especially in patients with reported contraindications to iodinated contrast media.     

Masthead,Volume 37, Issue 5

Cartilage is one of the most essential tissues for healthy joint function and is compromised in degenerative and traumatic joint diseases. There have been tremendous advances during the past decade using quantitative MRI techniques as a noninvasive tool for evaluating cartilage, with a focus on assessing cartilage degeneration during osteoarthritis (OA). In this review, after a brief overview of cartilage composition and degeneration, we discuss techniques that grade and quantify morphologic changes as well as the techniques that quantify changes in the extracellular matrix. The basic principles, in vivo applications, advantages, and challenges for each technique are discussed. Recent studies using the OA Initiative (OAI) data are also summarized. Quantitative MRI provides noninvasive measures of cartilage degeneration at the earliest stages of joint degeneration, which is essential for efforts toward prevention and early intervention in OA. J. Magn. Reson. Imaging 2013;38:991–1008. © 2013 Wiley Periodicals, Inc.     

Osteogenesis imperfecta in childhood: MR imaging of basilar impression

OBJECTIVE: To determine on radiographs the presence of Basilar Impression (BI) in children with Osteogenesis Imperfecta (OI). To confirm this sign and altered geometrical relationships of the craniocervical junction in course of time with magnetic resonance imaging (MRI). METHODS AND PATIENTS: In a cohort study of 130 patients with OI (OI type I: 85; OI type III: 21; OI type IV: 24) lateral radiographs of the skull and cervical spine were made in a standardised way. MRI scans were performed when BI was suspected based upon protrusion of the odontoid above Chamberlain's line. Intracranial abnormalities as well as the basal angle were described. Neurological examination was performed in patients with conclusive BI at MRI-scan. RESULTS AND DISCUSSION: In eight patients BI could be confirmed by MRI-scan. None of the children had or developed in time neurological symptoms or signs. Follow up of BI by MRI scans was done in seven patients (mean: 5 years; range: 2-6 years). No alteration of intracranial findings were seen at subsequent investigation, although in one child Chamberlain's line increased from 8 (first MRI) to 15 mm (last MRI). BI can be diagnosed by radiographs but in the extreme osteoporotic bone and altered anatomy of the craniocervical junction of children with OI MRI is preferable. As intracranial pathology can be demonstrated by MRI, also a relation can be laid to possible neurological symptoms and signs at clinical examination. CONCLUSION: In our cohort study no alteration of the intracranial contents was seen at subsequent MRI scans. Although anatomic deformations exist in BI, no neurological symptoms or signs were present in our study and no operative reconstruction had to be performed. Periodical MRI-scan has not been of influence on the clinical decision making process. At the moment we perform a MRI-scan if BI is suspected at lateral skull radiographs. The MRI images serve as reference findings to anticipate on possible future symptoms and signs of neurological deficit.     

Evaluation of chondral repair using quantitative MRI

Various quantitative magnetic resonance imaging (qMRI) biomarkers, including but not limited to parametric MRI mapping, semiquantitative evaluation, and morphological assessment, have been successfully applied to assess cartilage repair in both animal and human studies. Through the interaction between interstitial water and constituent macromolecules the compositional and structural properties of cartilage can be evaluated. In this review a comprehensive view of a variety of quantitative techniques, particularly those involving parametric mapping, and their relationship to the properties of cartilage repair is presented. Some techniques, such as T2 relaxation time mapping and delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC), are well established, while the full potential of more recently introduced techniques remain to be demonstrated. A combination of several MRI techniques is necessary for a comprehensive characterization of chondral repair. J. Magn. Reson. Imaging 2012; 36:1287–1299. © 2012 Wiley Periodicals, Inc.     

A painful squat test provides limited diagnostic utility in CAM-type femoroacetabular impingement

Purpose

The purpose of this study is to determine the relationship between a symptomatic maximal squat and the presence of radiographic CAM-type femoroacetabular impingement (FAI) on magnetic resonance imaging (MRI) and to determine the sensitivity and specificity of a maximal squat test for the presence of radiographic CAM-type femoral deformity in an adult population.

Methods

In this pilot study, 76 consecutive patients were recruited from an outpatient clinic at McMaster University. All patients presented with pre-arthritic hip pain and were asked to perform a maximal squat. The results of this test were compared to magnetic resonance imaging and magnetic resonance angiographic (MRI and MRA) findings evaluating and characterizing CAM-type FAI deformity.

Results

The sensitivity and specificity of the maximal squat test were 75 % (56.6–88.5 %) and 41 % (27.0–56.8 %), respectively, for CAM-type FAI deformity. The positive and negative likelihood ratios were modest at 1.3 (0.9–1.7) and 0.6 (0.3–1.2), respectively. This means that a 30 % pre-test probability is improved to 36 % following a positive squat test and reduced to 20 % with a negative squat test.

Conclusion

The maximal squat test was found to have marginal incremental diagnostic ability for CAM-type FAI. Its utility in the diagnostic evaluation of FAI remains limited. This survey elucidates areas of research for future studies relevant to the clinical diagnosis of FAI.

Level of evidence

III.     

Magnetic resonance imaging ofarticular cartilage injuries of the knee

Magnetic resonance imaging (MRI) is a widely available, powerful imaging modality in the United States that has rapidly become a mainstay for evaluation of the musculoskeletal system, largely because of its unparalleled depiction of most osseous and soft-tissue pathology. The application of MRI to detect cartilage injuries has evolved to the point where it is possible to noninvasively diagnose cartilage lesions that previously required an invasive examination, eg, arthrography or arthroscopy. However, successful cartilage imaging requires knowledge of the unique technical considerations and limitations of MRI. In this chapter we review current state-of-the-art knee MRI for three groups of chondral disorders: acute osteochondral fractures, osteochondritis dissecans, and degenerative lesions. The role of MRI in osteochondral fractures includes the demonstration of purely chondral intra-articular fragments and the identification of associated injuries, especially previously unrecognized subchondral bruises. MRI may also play a role in surveillance for osteochondral sequelae after injury. For osteochondritis dissecans, MRI can provide evidence supporting the diagnosis of a loose fragment and may aid in the evaluation of cartilage overlying osteochondral defects. Current MRI techniques can show moderate and severe lesions of chondromalacia and chondrosis. Newer techniques show potential for diagnosing these degenerative conditions at earlier stages when the changes are mild. We review these issues and provide examples showing the MRI appearance of common articular injuries.     

Femoroacetabular Impingement: Diagnosis and Management, Including Open Surgical Technique

Early recognition of FAI and timely delivery of care appear to have a considerable impact on the natural history of the femoroacetabular impingement, potentially delaying the onset of end-stage OA in this young group of active patients.³⁵ Successful application of the treatment principles outlined is less likely in patients presenting late who have evidence of extensive articular cartilage injuries. These patients have often been misdiagnosed or subjected to a prolonged period of conservative treatment and successful return to their sports cannot be expected. In the future, screening programs for identifying FAI in adolescents and young adults may become an important step in avoiding development of disabling hip disease.     

Comparative reliability and diagnostic performance of conventional 3T magnetic resonance imaging and 1.5T magnetic resonance arthrography for the evaluation of internal derangement of the hip

Objective

To compare the diagnostic accuracy of conventional 3T MRI against 1.5T MR arthrography (MRA) in patients with clinical femoroacetabular impingement (FAI).

Methods

Sixty-eight consecutive patients with clinical FAI underwent both 1.5T MRA and 3T MRI. Imaging was prospectively analysed by two musculoskeletal radiologists, blinded to patient outcomes and scored for internal derangement including labral and cartilage abnormality. Interobserver variation was assessed by kappa analysis. Thirty-nine patients subsequently underwent hip arthroscopy and surgical results and radiology findings were analysed.

Results

Both readers had higher sensitivities for detecting labral tears with 3T MRI compared to 1.5T MRA (not statistically significant p=0.07). For acetabular cartilage defect both readers had higher statistically significant sensitivities using 3T MRI compared to 1.5T MRA (p=0.02). Both readers had a slightly higher sensitivity for detecting delamination with 1.5T MRA compared to 3T MRI, but these differences were not statistically significant (p=0.66). Interobserver agreement was substantial to perfect agreement for all parameters except the identification of delamination (3T MRI showed moderate agreement and 1.5T MRA substantial agreement).

Conclusion

Conventional 3T MRI may be at least equivalent to 1.5T MRA in detecting acetabular labrum and possibly superior to 1.5T MRA in detecting cartilage defects in patients with suspected FAI.

Key Points

? Conventional 3T MRI is equivalent to 1.5T MRA for diagnosing labral tears. ? Conventional 3T MRI is superior to 1.5T MRA for diagnosing acetabular cartilage defect. ? Conventional 3T MRI is equivalent to 1.5T MRA for diagnosing cartilage delamination. ? Symptom severity score was significantly higher (p<0.05) in group proceeding to surgery.

     

High-resolution magnetic resonance imaging of the knee joint: pathologic correlations

Highly detailed pathologic morphology of 25 knees with suspected structural abnormalities was depicted in thin-section, high-resolution magnetic resonance images (MRI) produced with the aid of a specially designed solenoid surface coil. Scans were obtained on a 0.3-T permanent magnet system with 4-mm-thick slices and 0.75-mm pixel size. The images were correlated with clinical, arthrographic and/or bone scan, and surgical findings. In 10 of 11 cases of clinically suspected meniscal tears, the MRI findings corresponded with those of arthroscopy. In the three cases of clinically suspected injury to the anterior cruciate ligament which underwent surgery, the MRI findings of tears in two cases and a normal ligament in one case were confirmed. MRI was also useful in the evaluation of possible injury to the patellar tendon, in the detection of intraarticular loose bodies, and in the diagnosis of osteonecrosis.     

Comparison of whole-body STIR-MRI and <Superscript>99m</Superscript>Tc-methylene-diphosphonate scintigraphy in children with suspected multifocal bone lesions

The study was performed to compare whole-body short time inversion recovery (STIR) MR imaging and ^99mTc-methylene diphosphonate planar scintigraphy in the examination of children with suspected multifocal skeletal malignant lesions. Sixteen patients with known or suspected malignant skeletal disease underwent both whole-body STIR MR imaging and bone scintigraphy. The lesions were described and numbered according to scintigraphic evaluation criteria. Thus, 16 regions were analyzed in each patient for the comparison between the two modalities. Histology was proven in the primary malignant regions. Follow-up MRIs were registered. Scintigraphy and MRI follow-up were evaluated as gold standard. A total of 139 different lesions was observed by both modalities. Baseline whole-body MRI revealed 119 bone lesions in 256 possible sites (46.5%); scintigraphy revealed only 58 lesions (22.6%). Congruence was observed in only four patients (25%). According to the location of the lesion, correlation was observed in 39/139 lesions (28%). In all, 57.5% of the lesions were detected only by MRI and 14.5% of the lesions were detected only by scintigraphy. Whole-body MRI was more sensitive (P<0.001). Of all lesions numbered which could be separated in the initial MRI, whole-body MRI detected 178 lesions in the patients. The results suggest that whole-body MRI using a STIR sequence is an effective radiation free method for examination of children with suspected multifocal bone lesions. MRI showed more lesions than conventional ^99mTc-methylene diphosphonate scintigraphy. Therefore, whole-body MRI may be feasible as a screening modality for metastatic and skip lesions in osteosarcoma, PNET, Ewing sarcoma and Langerhans cell histiocytosis in children.     

Reversed laminar appearance of articular cartilage by T1‐weighting in 3D fat‐suppressed spoiled gradient recalled echo (SPGR) imaging

Purpose:

To investigate the reversed intensity pattern in the laminar appearance of articular cartilage by 3D fat‐suppressed spoiled gradient recalled echo (FS‐SPGR) imaging in magnetic resonance imaging (MRI).

Materials and Methods:

The 3D SPGR experiments were carried out on canine articular cartilage with an echo time (TE) of 2.12 msec, a repetition time (TR) of 60 msec, and various flip angles (5° to 80°). In addition, T1, T2, and T2* in cartilage were imaged and used to explain the laminar appearance in SPGR imaging.

Results:

The profiles of T2 and T2* in cartilage were similar in shape. However, the T2 values from the multigradient‐echo imaging sequence were about 1/3 of those from single spin‐echo sequences at a pixel resolution of 26 μm. While the laminar appearance of cartilage in spin‐echo imaging is caused mostly by T2‐weighting, the laminar appearance of cartilage in fast imaging (ie, short TR) at the magic angle can have a reversed intensity pattern, which is caused mostly by T1‐weighting.

Conclusion:

The laminar appearance of articular cartilage can have opposite intensity patterns in the deep part of the tissue, depending on whether the image is T1‐weighted or T2‐weighted. The underlying molecular structure and experimental protocols should both be considered when one examines cartilage images in MRI. J. Magn. Reson. Imaging 2010;32:733–737. © 2010 Wiley‐Liss, Inc.     

Computer-assisted imaging of the fetus with magnetic resonance imaging

The purpose of this paper is to review the use of magnetic resonance imaging (MRI) of the fetus and to propose future techniques and applications. Institutional review board approved MR images of the fetus were acquired in 66 patients with sonographically suspected fetal abnormalities. Axial, coronal, and sagittal short TR, short TE images were obtained. In addition, 12 studies were performed with rapid scans requiring 700–1200 ms using either GRASS or Spoiled GRASS techniques. Sequential studies demonstrating fetal motion were also performed. Three studies with 3D IR prepped GRASS were performed. These allowed for orthogonal and non-orthogonal reformatted views and 3D display. Normal fetal structures were shown with MRI, including brain, heart, liver, stomach, intestines, and bladder. Gross fetal anomalies could generally be demonstrated with MRI. MRI may give additional information to that of sonography in fetal anomalies, particularly those involving the central nervous system, and in the detection of fat, blood, and meconium. MRI of the fetus can demonstrate normal and abnormal structures. Newer techniques with faster imaging will allow for greater possibility of computer assisted manipulation of data.