[Transient bone marrow edema of the hip]. / Le syndrome d'œdème médullaire de la tête fémorale.

Transient bone marrow edema of the hip is characterized by moderate homogeneous low MR signal intensity with ill-defined margins that involves at least a portion of the femoral head. Spin echo T1-weighted images are helpful to exclude other underlying diseases (tumor, infection, necrosis from systemic origin…), for which marrow edema is secondary or no epiphyseal in location. High-resolution fat-suppressed T2-weighted or proton density images allow evaluation of the articular cartilage, subchondral bone and subchondal marrow: if the articular cartilage is abnormal, the lesion is irreversible (arthrosis or necrosis); if the subchondral bone is focally interrupted and/or if the femoral is no longer spherical, the lesion is irreversible (necrosis); if a focal linear fluid collection is present under the subchondral bone, the lesion is irreversible (necrosis). Finally, subchondral changes may provide useful prognostic information: the absence of any abnormality other than marrow edema typically indicates that complete resolution is likely; the presence of a focal T2-weighted hypointense lesion immediately next to the subchondral bone suggests an irreversible lesion, especially if it is equal to or thicker than 4mm or the joint space. In some instances, prognosis cannot be reliably determined requiring the need for follow-up imaging.

[Plain radiography of the knee: the articular surfaces]. / Relecture des radiographies standard du genou: les surfaces articulaires.

Lateral knee radiographs allow recognition of both medial and lateral femoral and tibial surfaces, groove and anterior borders of the trochlea and lateral facet and ridge of the patella. Analysis of these lines allows detection of focal contour abnormalities, femoral trochlear dysplasia and patellar tilt. Qualitative radiological analysis of the osseous surfaces detects the particular aspect of abraded subchondral bone ("drawn with chalk"), preventing the trap of false joint spaces on non weight-bearing views. Occasionally, very subtle bone abnormalities can be recognized in cases of cartilaginous, subchondral or even meniscal lesions. However, these focal abnormalities are not constant, and their visualization is somewhat anecdotal.

Bone marrow edema of the femoral head.

This article addresses the MR features of the bone marrow edema syndrome (BMES) of the femoral head with emphasis on the prevalence and clinicopathology of the disorder and description of the current concepts on diagnosis and prognosis. BMES can be observed in self resolving conditions such as transient osteoporosis of the hip, spontaneous fracture of the femoral head, or post traumatic lesions. Rapidly destructive coxarthrosis, necrosis of the femoral head as well as certain forms of spontaneous fracture of the femoral head may present a similar MR pattern, though prognosis is definitely less favourable. The challenging role of the radiologist is to recognize BMES at an early stage and to provide adequate prognosis on the lesion outcome.

[Cardiac imaging by means of four-detector row computed tomography and cardiac gating]. / Imagerie cardiaque en tomodensitométrie à quatre canaux d'acquisition et synchronisation cardiaque.

Electrocardiographically-assisted imaging is a recent development in multislice spiral computed tomography. In this article, we summarize the principles of four-detector row CT for cardiac applications. Following is an overview of the potential of this technique to evaluate the heart, the thoracic aorta, and the paracardiac pulmonary parenchyma. Technical considerations for optimal imaging are highlighted.

[Atypical ganglion cysts]. / Les kystes mucoides atypiques.

Intra- or para-articular ganglion cysts are frequent and can develop at some distance from the joints. The authors describe examples of typical and atypical ganglion cysts, namely meniscal cyst, intra-articular cyst, intraosseous cyst, intraneural cyst of tibial nerve, adventitial cyst of popliteal artery, and para-articular cyst of the hip, filled with gas of presumed articular origin. The diagnosis of a ganglion cyst can be difficult when there is no evident articular communication. If demonstration of communication is necessary (in case of uncertain diagnosis or for preoperative assessment), the best procedure is arthrography followed by a CT scan 1-2 hours after the injection.

[Normal bone marrow: dynamic aspects in magnetic resonance imaging]. / La moelle osseuse normale: aspects dynamiques en imagerie par résonance magnétique.

The bone marrow is a complex organ that contains fat and nonfat cells, the proportion of which varies greatly with age and in the different bones of the skeleton. Magnetic resonance imaging provides information on the composition of the medullary cavity of any given bone and on the distribution of red and yellow marrow in the skeleton. The wide spectrum of appearances of the normal bone marrow at MR imaging will be reviewed. The purpose of this paper is to determine the MR appearance of the bone marrow, to illustrate the phenomenon of marrow conversion and to familiarize the readers with the complex parameters that interfere with the MR appearance of normal bone marrow.

Magnetic resonance imaging and differential diagnosis of epiphyseal osteonecrosis.

This article addresses imaging features of epiphyseal osteonecrosis that have been highlighted by the use of magnetic resonance imaging, including better depiction of marrow infarcts, better knowledge of their natural history, and better understanding of the different patterns of epiphyseal osteonecrosis. Imaging features that enable differentiation between irreversible lesions, including epiphyseal osteonecrosis and rapidly progressive osteoarthritis, and spontaneously transient lesions, including transient osteoporosis and epiphyseal fractures, are emphasized.

Magnetic resonance and computed tomography imaging in multiple myeloma.

This article reviews current knowledge on the various lesion patterns that can be observed at magnetic resonance (MR) imaging and on computed tomography images in patients with plasma cell neoplasms. It reviews limitations in specificity of imaging features and emphasizes difficulties in the recognition of the benign or malignant origin of vertebral fractures in these patients. The prognostic significance of MR imaging findings with respect to the natural history of the disease or to survival after treatment is discussed.

Magnetic resonance appearance of uncomplicated Paget's disease of bone.

Paget's disease is a disorder of the bone mesenchyma of the skeleton and is a unique condition in which active bone changes can occur without concomitant significant marrow alteration. When present, marrow changes involve predominantly the paratrabecular and endosteal areas, where bone metabolism is increased. At magnetic resonance (MR) imaging, marrow alterations can become prominent and hence confusing in bones with high trabecular content including vertebrae and pelvis. This article addresses the MR appearance of uncomplicated Paget's disease, including normal pagetic bone, predominantly lytic or sclerotic pagetic bone, and unusual partial involvement of the vertebral body. We will emphasize the added diagnostic value of the combination of imaging techniques that depict either osseous changes including radiographs, computed tomography, and bone scintigraphy, or marrow changes, including MR imaging, to contribute to a noninvasive presumptive diagnosis of Paget's disease in atypical presentations.

[Hip imaging: what is the best modality?]. / Imagerie de la hanche: quel examen choisir?

Conventional radiography plays a key-role in the assessment of symptomatic hips. A well-performed radiographic examination (comparative A-P views with straight or ascending X-Ray beam, off-lateral view of Lequesne) enables to recognise most bone (fractures, transient osteoporosis, epiphyseal osteonecrosis) and articular lesions (osteoarthritis). In some situations (incoherent radio-clinical findings, need of a confident diagnosis), joint aspiration or additional imaging procedures are needed. Serial radiographs are obtained when no specific treatment can be immediately offered. Bone scintigraphy is obtained to confidently exclude bone or articular disorders or in case of suspected disseminated bone disease. The majority of bone, articular and abarticular lesions can be diagnosed by using MRI. It should be obtained when results are likely to influence the final outcome of the disease.

Lesions of the menisci of the knee: value of MR imaging criteria for recognition of unstable lesions.

OBJECTIVE: This study aimed to determine the value of four MR imaging criteria for evaluating unstable meniscal lesions. MATERIALS AND METHODS: Criteria for unstable meniscal lesions were the presence of a displaced meniscal fragment, visibility on more than three 3-mm-thick coronal and two 4-mm-thick sagittal images, having more than one orientation plane or more than one pattern (contour irregularity, peripheral separation, tear), and having intrameniscal high signal intensity on T2-weighted spin-echo images. Sensitivity, specificity, and positive and negative predictive values for recognition of instability among all meniscal lesions were determined for the presence of each individual criterion and for the presence of at least one criterion in 50 consecutive patients (mean age, 46 years) who underwent MR imaging and subsequent arthroscopy. RESULTS: Sensitivities and specificities of these four criteria ranged between 18% and 54% and between 94% and 100%, respectively. Positive and negative predictive values ranged between 92% and 100% and between 39% and 52%, respectively. The presence of at least one criterion enabled recognition of unstable lesions with a sensitivity and specificity of 82% and with positive and negative predictive values of 90% and 70%, respectively. CONCLUSION: The four MR imaging criteria have high specificities and positive predictive values and low sensitivities and negative predictive values when evaluating unstable meniscal lesions.

Bone marrow transplantation in patients with multiple myeloma: prognostic significance of MR imaging.

OBJECTIVE: This study in myeloma patients treated with myeloablative therapy and bone marrow transplantation assessed the prognostic value of MR imaging before and after treatment of the bone marrow and the prognostic value of an index reflecting changes on MR images obtained before and after treatment. SUBJECTS AND METHODS: MR images (T1-weighted images before and after injection of gadolinium and T2(*)-weighted images) of the spine and pelvis were obtained 1 month before and 1 month after marrow transplantation in 25 consecutive patients with stage III myeloma. Pre- and posttreatment MR imaging patterns of marrow involvement (normal, focal, diffuse), number of focal lesions, and a "marrow evolution index" (0-8 on the basis of comparison of the lesions [number, size, contrast enhancement] and of the surrounding marrow background on pre- and posttreatment MR images) were determined. Hematologic and MR imaging parameters were correlated with the quality of response to treatment (complete versus partial remission) and with relapse-free and overall survival. RESULTS: Response quality did not differ among categories of patients determined on the basis of MR images. Individual MR imaging parameters did not correlate with response duration and survival. Patients with a low marrow evolution index had significantly longer relapse-free (p < 10(-3)) and overall survival (p = 0.005) than patients with a high index. CONCLUSION: Individual MR imaging parameters before and after treatment had no prognostic significance in our series of myeloma patients treated with marrow transplantation. Comparison of MR images before and after treatment using a marrow evolution index may help predict response duration and survival.

The lumbar vertebral body and diskovertebral junction. Radio MR imaging anatomic correlations.

Radiographs and MR images of spine specimens provide superb tomographic views of changes that involve the mineralized network and the medullary content of vertebral bodies. By illustrating changes in the balance between bone resorption and formation and between fat and nonfat marrow cells, these frozen images of the reality help us to understand normal variants and lesions that develop in osseous and articular diseases of the lumbar spine.

Dual-detector spiral CT arthrography of the knee: accuracy for detection of meniscal abnormalities and unstable meniscal tears.

PURPOSE: To determine the sensitivity and specificity of dual-detector spiral computed tomographic (CT) arthrography of the knee in the detection of meniscal abnormalities and unstable meniscal tears. MATERIALS AND METHODS: The meniscal changes in 50 consecutive patients who underwent dual-detector spiral CT of the knee after intraarticular injection of iodinated contrast material (0.55-mm effective section thickness, 0.75 pitch value, 0.3-mm increment reconstruction, 0.43-mm in-plane resolution, 0.3-mm longitudinal resolution) were determined by two observers and were compared with arthroscopic findings. The sensitivity and specificity of CT arthrography for the detection of meniscal abnormalities and unstable meniscal tears and the kappa statistics for assessing interobserver reproducibility were determined. RESULTS: The sensitivity and specificity for the detection of meniscal abnormalities were 98% and 94%, respectively. The sensitivity and specificity for the detection of unstable meniscal tears were 97% and 90%, respectively. Interobserver agreement was excellent for the detection of meniscal abnormalities (kappa = 0.899) and of unstable meniscal tears (kappa = 0.885). CONCLUSION: Dual-detector spiral CT arthrography of the knee is an accurate and reproducible method for detecting meniscal abnormalities and unstable meniscal tears.

Idiopathic bone marrow edema lesions of the femoral head: predictive value of MR imaging findings.

PURPOSE: To determine the frequency of several subchondral magnetic resonance (MR) imaging features observed in bone marrow edema lesions of the femoral head and to determine their value for differentiation of irreversible from transient lesions. MATERIALS AND METHODS: The authors reviewed MR images of 72 femoral head lesions in 42 men and 25 women (median age, 48 years) with equivocal radiographic findings and bone marrow edema seen at MR imaging (T1- and T2-weighted images in all patients and contrast material-enhanced T1-weighted images in 39 patients). Follow-up MR images showed 57 lesions to be transient and 15 to be irreversible. The presence and size of subtle subchondral features observed on initial MR images were compared for both types of lesion. RESULTS: Lack of any additional subchondral change on T2-weighted or contrast-enhanced T1-weighted images had 100% positive predictive value for transient lesions. For irreversible lesions, presence of a subchondral area of low signal intensity at least 4 mm thick or 12.5 mm long had positive predictive values of 85% and 73%, respectively, on T2-weighted images and 87% and 86%, respectively, on contrast-enhanced T1-weighted images. CONCLUSION: Careful assessment of subchondral changes enables confident differentiation between early irreversible lesions and transient bone marrow edema lesions.

Skeletal survey in advanced multiple myeloma: radiographic versus MR imaging survey.

In an attempt to compare the sensitivity of bone radiographs and bone marrow magnetic resonance (MR) imaging for bone lesion detection in patients with stage III multiple myeloma (MM) and to evaluate the possible consequences of the replacement of the conventional radiographic skeletal survey (RSS) by an MR survey of the spinal and pelvic bone marrow in these patients, we obtained MR studies of the thoracic and lumbar spine, pelvis and proximal femurs in addition to the conventional RSS (including radiographs of the skull, entire spine, pelvis, ribs, humerus and femurs) in 80 consecutive patients with newly diagnosed stage III MM according to the Durie and Salmon staging system (based on blood tests and on the RSS). The performance of MR and radiographic studies to detect bone lesions in given anatomic areas and in given patients were compared. The consequences on MM staging following the substitution of the RSS by the MR survey were assessed. MR imaging was superior to radiographs for lesion detection in the spine (76% v 42% of patients) and pelvis (75% v 46% of patients). The RSS was superior to the limited MR imaging survey for the detection of bone involvement in the patient population (87.5% v 79% of patients). If the RSS had been replaced by the MR imaging survey for patient staging, 7/80 patients would have been categorized as stage I and one as stage II MM on the basis of normal MR findings and biological findings consistent with these stages. Substitution of the RSS by a limited spinal and pelvic marrow MR survey would lead to 'understaging' of 10% of patients with otherwise stage III MM on the basis of blood tests and the conventional RSS.

Retrodural cysts bridging a bilateral lumbar spondylolysis: a report of two symptomatic cases.

We report the MR features in two patients presenting with symptomatic thecal impingement by posterior epidural cysts linking a bilateral lumbar spondylolysis. Large fluid-filled channels bridging the ruptured partes interarticulares were present in spite of the absence of significant arthritic changes within the adjacent facet joints.