关节软骨MR成像进展

随着软骨序列的开发和应用，MRI对关节软骨的评价越来越重要。本文就关节软骨的MRI表现、关节软骨的MRI序列和扫描技术、关节软骨损伤以及修复术后MRI评价等方面进行了综述。     

Magnetic resonance of the knee menisci and cartilage

This contribution is designed to present magnetic resonance (MR) of the menisci and cartilage to the orthopedic surgeon in a practical manner. The investigators describe those MR sequences and techniques that optimally show injury, as well as the expected morphology of the menisci. Criteria for diagnosis of meniscal tears are outlined. Common “equivocal” meniscal tear appearances are shown and strategies for resolving such equivocal cases are suggested. The difficult problem of diagnosing a meniscal remnant tear or reinjury of a repaired meniscus is covered. Finally, MR imaging of chondromalacia and osteochondral injuries is discussed.     

Magnetic resonance imaging ofthe hand and wrist — clinical significance and impact

The clinical experience with magnetic resonance imaging (MRI) in the evaluation of the hand and wrist has beenrapidly expanding over the past few years. The use of dedicated surface coils has improved the ability of MRI to assess the soft tissue and osseous structures in this region. The evaluation of the patient with chronic hand and wrist pain can be a diagnostic dilemma. The anatomic complexity of the hand and wrist makes the pathological possibilities innumerable, ranging from tenosynovitis to osteonecrosis. MRI is invaluable in the detection of avascular necrosis of the carpus, and allows staging, determination of prognosis, and assessment of treatment. Carpal instability can be evaluated by this noninvasive modality, which provides information regarding ligament integrity as well as an assessment of'the articular surface. More recent application in the upper extremity has allowed the determination of flexor tendon integrity, and MR angiography can be used in the evaluation of vascular disorders of the hand. MRI has made a significant impact in our assessment and treatment of these various disorders of the hand and wrist. As the techniques are further refined, we can expect continued improvement in our diagnostic capabilities.     

Magnetic resonance imaging of thehand and wrist

The application of magnetic resonance imaging (MRI) to the hand and wrist has lagged behind its use in larger joints. Recent advances in hardware and software technology have allowed faster imaging with excellent anatomic resolution. After routine radiography, MRI is the imaging procedure of choice for evaluation of chronic wrist pain. The most common indications for MRI within the hand and wrist include scapholunate-lunate ligament tears, triangular fibrocartilage complex (TFCC) tears, avascular necrosis, and soft tissue masses. MRI may occasionally help evaluate tendon abnormalities, atypical or postoperative recurrent carpal tunnel syndrome, and complications of inflammatory arthritides. Future applications of MRI will likely include improved anatomic imaging of smaller structures such as the lunatotriquetral ligament and the extrinsic ligaments, as well as MR angiography (MRA).     

Magnetic resonance imaging of themusculoskeletal system

The accuracy of magnetic resonance imaging (MRI) in evaluating disorders of the musculoskeletal system is wellestablished. MRI is especially valuable in evaluating pathology of the major joints and soft tissues of the body. Importantly, MRI is a noninvasive technology. As with any new technology in medicine, time is required to establish the place of the technology in the armamentarium of clinicians. This is the unsettled situation MRI finds itself in today.     

Magnetic resonance imaging of articular cartilage: ex vivo study on normal cartilage correlated with magnetic resonance microscopy

The aims of this study were (a) to compare the MR appearance of normal articular cartilage in ex vivo MR imaging (MRI) and MR microscopy (MRM) images of disarticulated human femoral heads, (b) to evaluate by MRM the topographic variations in articular cartilage of disarticulated human femoral heads, and subsequently, (c) to compare MRM images with histology. Ten disarticulated femoral heads were examined. Magnetic resonance images were obtained using spin-echo (SE) and gradient-echo (GE) sequences. Microimages were acquired on cartilage–bone cylindrical plugs excised from four regions (superior, inferior, anterior, posterior) of one femoral head, using a modified SE sequence. Both MRI and MRM images were obtained before and after a 90 ° rotation of the specimen, around the axis perpendicular to the examined cartilage surface. Finally, MRM images were correlated with histology. A trilaminar appearance of articular cartilage was observed with MRI and with a greater detail with MRM. A good correlation between MRI and MRM features was demonstrated. Both MRI and MRM showed a loss of the trilaminar cartilage appearance after specimen rotation, with greater evidence on MRM images. Cartilage excised from the four regions of the femoral head showed a different thickness, being thickest in the samples excised from the superior site. The MRM technique confirms the trilaminar MRI appearance of human articular cartilage, showing good correlation with histology. The loss of the trilaminar appearance of articular cartilage induced by specimen rotation suggests that this feature is partially related to the collagen-fiber orientation within the different layers. The MRM technique also shows topographic variations in thickness of human articular cartilage. Received 28 July 1997; Revision received 31 December 1997; Accepted 6 January 1998     

Magnetic resonance imaging of the elbow

With the current popularity of racket and throwing sports, the number of individuals seeking medical care for elbow pain and dysfunction has increased. Elbow dysfunction may be related to acute or chronic injury to the soft tissue or osseous components of the elbow. With magnetic resonance imaging (MRI), it is now possible to accurately determine the nature and extent of the pathological changes in ligaments, tendons, muscles, and osseous structures of the elbow joint. This information facilitates the choice of the appropriate therapeutic regimen.     

Evaluation of chondral injuriesby magnetic resonance imaging: Repair assessments

Magnetic resonance (MR) is a versatile imaging modality that can be tailored to address many of the clinical andresearch questions encountered in musculoskeletal diseases. Developments in MR techniques for cartilage imaging have paralleled the advances in clinical approaches to cartilage injury assessment and repair. This article reviews the current state-of-the-art clinical MR imaging methods designed for noninvasive evaluation of cartilage. Basic technical considerations are discussed, including selection of an imaging site for patient referral, interpretation of MR images, and the limitations of each acquisition technique. Clinical examples are used to illustrate the appearance of chondral lesions. Finally, the unique issues arising from cartilage assessment after surgical repair are examined.     

T1rho MR imaging of the human wrist in vivo

RATIONALE AND OBJECTIVES: The purpose of this study was (a) to demonstrate the feasibility of computing T1rho maps of, and T1rho dispersion in, human wrist cartilage at MR imaging in vivo and (b) to compare T1rho and T2 weighting in terms of magnitude of relaxation times and signal intensity contrast. MATERIALS AND METHODS: T2 and T1rho magnetic resonance images of wrist joints in healthy volunteers (n = 5) were obtained with a spin-echo sequence and a fast spin-echo sequence pre-encoded with a spin-lock pulse cluster. A 1.5-T clinical imager was used (Signa; GE Medical Systems, Milwaukee, Wis) with a 9.5-cm-diameter transmit-receive quadrature birdcage coil tuned to 63.75 MHz. RESULTS: T1rho relaxation times at a spin-lock frequency of 500 Hz vary from 40.5 msec +/- 0.85 to 56.6 msec +/- 4.83, and T2 relaxation times vary from 28.1 msec +/- 1.88 to 34.5 msec +/- 2.63 (mean +/- standard error of the mean, n = 5, P < .016) in various regions of the wrist. T1rho dispersion was observed in the range of spin-lock frequencies studied. T1rho-weighted images not only have higher signal-to-noise ratios but also show better fluid and fat signal suppression than T2-weighted images. CONCLUSION: It was possible to perform T2- and T1rho-weighted MR imaging of human wrist cartilage in vivo with standard clinical imagers. The higher signal-to-noise ratio and improved contrast between cartilage and surrounding fat achieved with T1rho imaging may provide better definition of lesions and accurate quantitation of small changes in cartilage degeneration.     

定量磁共振对膝关节软骨的应用研究进展

膝关节软骨在维持关节正常运动中起着缓冲、减震及润滑的关键作用。软骨定量磁共振成像是一种比较新的磁共振成像技术,能够对软骨内的细微组织成分进行量化评估,是评价膝关节软骨及其病变的一种有效的影像学检查方法。本文对膝关节软骨的正常组织结构和定量磁共振在膝关节软骨的量化评估及临床应用予以综述。     

Effect of gender on in vivo cartilage magnetic resonance imaging T2 mapping

PURPOSE: To determine if gender is a significant variable for in vivo magnetic resonance imaging (MRI) T2-mapping of knee articular cartilage in young asymptomatic volunteers. MATERIALS AND METHODS: Cartilage MRI T2 mapping was performed in a young healthy population consisting of seven male and 10 female volunteers, 22 to 29 years of age. High-resolution in vivo T2 maps were obtained of patellar, tibial, and weight-bearing femoral articular cartilage. Spatial dependency of cartilage T2 between groups was evaluated through a comparison of cartilage T2 as a function of normalized distance from bone. RESULTS: Bulk cartilage T2 values were similar at all three anatomic sites, and between male and female volunteers. All volunteers demonstrated similar spatial variation in cartilage MRI T2 values, with a minimum located in the radial zone and increasing T2 values toward the articular surface. There was no difference in spatial dependency of cartilage T2 between males and females. CONCLUSION: In young, healthy volunteers, the magnitude and spatial dependency of cartilage T2 does not differ with gender.     

Magnetic resonance imaging findings in diffuse lymphangiomatosis: neuroradiological manifestations

We report magnetic resonance (MR) findings in a patient with histologically proven lymphangiomatosis with a history of chylothorax, diffuse lung infiltrates, spinal involvement, cystic lesions of the mediastinum, and mesentery thickening. The patient also had diffuse infiltration of the right brachial plexus, with similar imaging findings as the spinal lesions. Although osseous and extraosseous involvement may be seen frequently with lymphangiomatosis, involvement of the brachial plexus has not been previously reported.     

Magnetic resonance imaging and permanent cosmetics (tattoos): survey of complications and adverse events

PURPOSE: To use a survey to determine the incidence of complications and adverse events in individuals with permanent cosmetics (e.g., tattooed eyeliner, eyebrows, lips, cheeks, etc.) who underwent magnetic resonance (MR) imaging. MATERIALS and METHODS: A questionnaire was distributed to clients of cosmetic tattoo technicians. This survey asked study subjects for demographic data, information about their tattoos, and for their experiences during MR imaging procedures. RESULTS: Data obtained from 1032 surveys were tabulated. One hundred thirty-five (13.1%) study subjects underwent MR imaging after having permanent cosmetics applied. Of these, only two individuals (1.5%) experienced problems associated with MR imaging. One subject reported a sensation of "slight tingling" and the other subject reported a sensation of "burning"; both sensations were transient in nature. CONCLUSION: Based on these findings and information in the peer-reviewed literature, it appears that MR imaging may be performed in patients with permanent cosmetics without any serious soft tissue reactions or adverse events. Therefore, the presence of permanent cosmetics should not prevent a patient from undergoing MR imaging.     

Magnetic resonance imaging of cartilage and cartilage repair

Magnetic resonance (MR) imaging of articular cartilage has assumed increased importance because of the prevalence of cartilage injury and degeneration, as well as the development of new surgical and pharmacological techniques to treat damaged cartilage. This article will review relevant aspects of the structure and biochemistry of cartilage that are important for understanding MR imaging of cartilage, describe optimal MR pulse sequences for its evaluation, and review the role of experimental quantitative MR techniques. These MR aspects are applied to clinical scenarios, including traumatic chondral injury, osteoarthritis, inflammatory arthritis, and cartilage repair procedures.     

Magnetic resonance imaging of the liver: New imaging strategies for evaluating focal liver lesions

The early detection of focal liver lesions, particularly those which are malignant, is of utmost importance. The resection of liver metastases of some malignancies (including colorectal cancer) has been shown to improve the survival of patients. Exact knowledge of the number, size, and regional distribution of liver metastases is essential to determine their resectability. Almost all focal liver lesions larger than 10 mm are demonstrated with current imaging techniques but the detection of smaller focal liver lesions is still relatively poor. One of the advantages of magnetic resonance imaging (MRI) of the liver is better soft tissue contrast (compared to other radiologic modalities), which allows better detection and characterization of the focal liver lesions in question. Developments in MRI hardware and software and the availability of novel MRI contrast agents have further improved the diagnostic yield of MRI in lesion detection and characterization. Although the primary modalities for liver imaging are ultrasound and computed tomography, recent studies have suggested that MRI is the most sensitive method for detecting small liver metastatic lesions, and MRI is now considered the pre-operative standard method for diagnosis. Two recent developments in MRI sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and keyhole-based dynamic contrast-enhanced (DCE) MRI (4D THRIVE). DWI allows improved detection (b = 10 s/mm(2)) of small (< 10 mm) focal liver lesions in particular, and is useful as a road map sequence. Also, using higher b-values, the calculation of the apparent diffusion coefficient value, true diffusion coefficient, D, and the perfusion fraction, f, has been used for the characterization of focal liver lesions. DCE 4D THRIVE enables MRI of the liver with high temporal and spatial resolution and full liver coverage. 4D THRIVE improves evaluation of focal liver lesions, providing multiple arterial and venous phases, and allows the calculation of perfusion parameters using pharmacokinetic models. 4D THRIVE has potential benefits in terms of detection, characterization and staging of focal liver lesions and in monitoring therapy.     

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.