Diffuse vertebral marrow changes at MRI: Multiple myeloma or normal?

Five MRI patterns of marrow involvement (diffuse, focal, combined diffuse and focal, variegated, and normal) are observed in patients with a marrow proliferative disorder including MM. The wide range of marrow involvement patterns in monoclonal plasma cell proliferative disorders mirrors that of their natural histories that can vary from indolent to rapidly lethal. MRI of the axial bone marrow contributes to stage these disorders, but it should not be obtained for disease detection and characterization because of its limited specificity and sensitivity. At MRI, diffuse benign hematopoietic marrow hyperplasia and marrow heterogeneities in elderly patients mimic the diffuse and variegated patterns observed in MM patients. Careful analysis of fat- and fluid-sensitive MR images and quantitative marrow assessment by using MRI and FDG-PET can contribute in differentiating these changes from those associated with neoplastic marrow infiltration, with some residual overlapping findings.

MRI detection of radiographically occult fractures of the hip and pelvis in the elderly: Comparison of T2-weighted Dixon sequence with T1-weighted and STIR sequences.

PURPOSE: To compare the diagnostic performance of T2-weighted Dixon, T1-weighted and Short-Tau Inversion Recovery (STIR) MR images for the detection of radiographically occult fractures (ROF) of the hip and pelvis in elderly patients after low-energy trauma. MATERIALS AND METHODS: A total of 22 patients older than 50 years with suspected ROF after low-energy trauma was prospectively included. There were 9 men and 13 women, with a mean age of 80.9 years±12.5 (SD) (range: 52-100 years). T2-weighted Dixon, T1-weighted and STIR MR images were analyzed by 3 independent radiologists blinded to the clinical data and the results of other imaging examinations. Readers separately assessed each series of images for the presence of fractures on a per bone analysis. Diagnostic performance of each reader was compared for Dixon and non-Dixon sequences using contingency tables and McNemar test. Interobserver agreement was evaluated according to the Fleiss-Cuzick's kappa statistics. RESULTS: The sensitivity of the Dixon sequence in the detection of ROF ranged from 90.9% (20/22; 95% CI: 70.8-98.9%) to 100% (22/22; 95% CI: 84.6-100%). The sensitivities of the non-Dixon sequences in the detection of ROF ranged from 95.5% (21/22; 95% CI: 77.2-99.9%) to 100% (22/22; 95% CI: 84.6-100%). For each reader, there were no statistical differences between combined Dixon and combined non-Dixon images for the detection of ROF (P=0.12, 0.99 and 0.99). Interobserver agreement with T2-weighted Dixon water-only images was significantly lower than that with the STIR sequence (0.70-0.79 vs. 0.87-0.93). CONCLUSION: T2-weighted Dixon may be a second-rate alternative to T1-weighted and STIR sequences for the detection of ROF of the hip and pelvis in elderly patients.

Magnetic resonance imaging (MRI) of the knee: Identification of difficult-to-diagnose meniscal lesions.

This article characterizes common meniscal pathologies, reviews magnetic resonance imaging (MRI) diagnostic criteria for meniscal tears, and identifies difficult-to-detect tears and fragments and the best MRI sequences and practices for recognizing these lesions. These difficult-to-diagnose meniscal lesions that radiologists should consider include tears, meniscocapsular separation lesions, and displaced meniscal fragments. Meniscus tears are either vertical, which are generally associated with traumatic injury, horizontal, which are associated with degenerative injury, or combinations of both. MRI has a high sensitivity for tears but not for fragments; MRI performance is also better for medial than lateral meniscal lesions. Fragment detection can be improved by recognizing signs secondary to migration, especially signs of epiphyseal irritation and mechanical impingement. Radial and peripheral tears, as well as those close to the posterior horn insertion, have been traditionally difficult to detect, but improvements in arthroscopic knowledge, identification of common lesion patterns, and selection of the proper MRI sequence and plane for each lesion type mean that, when properly used, MRI is an invaluable tool in detecting all types of meniscal tears.

Aneurysmal bone cystic lesions: value of genomic studies.

Aneurysmal bone cystic (ABC) lesions can be primary or secondary (to a trauma or a pre-existing benign or malignant tumour). Specific translocations of the USP6 gene are reported in about 70% of primary but never in secondary ABC lesions. We report two cases of ABC lesions in which imbalanced genomic aberrations were detected at initial presentation and showed complex clonal evolution. These demonstrative observations strengthen the guidelines regarding the diagnostic approach when an ABC is suggested by imaging. Biopsy is mandatory including genomic analysis. When a primary ABC is not clearly proven by the initial biopsy, an extensive curettage should be performed, with pathological examination of all removed tissue in order to exclude a secondary ABC. It also illustrates the added value of genomic analyses in the setting of an ABC lesion: complex clonal aberrations argues for a lesion secondary to a malignant proliferation whereas USP6 rearrangement allows the diagnosis of primary ABC.

Eosinophilic fasciitis: typical abnormalities, variants and differential diagnosis of fasciae abnormalities using MR imaging.

Eosinophilic fasciitis is a rare condition. It is generally limited to the distal parts of the arms and legs. MRI is the ideal imaging modality for diagnosing and monitoring this condition. MRI findings typically evidence only fascial involvement but on a less regular basis signal abnormalities may be observed in neighboring muscle tissue and hypodermic fat. Differential diagnosis of eosinophilic fasciitis by MRI requires the exclusion of several other superficial and deep soft tissue disorders.

Diffusion-weighted MR imaging in musculoskeletal diseases: current concepts.

MR imaging is currently regarded as a pivotal technique for the assessment of a variety of musculoskeletal conditions. Diffusion-weighted MR imaging (DWI) is a relatively recent sequence that provides information on the degree of cellularity of lesions. Apparent diffusion coefficient (ADC) value provides information on the movement of water molecules outside the cells. The literature contains many studies that have evaluated the role of DWI in musculoskeletal diseases. However, to date they yielded conflicting results on the use and the diagnostic capabilities of DWI in the area of musculoskeletal diseases. However, many of them have showed that DWI is a useful technique for the evaluation of the extent of the disease in a subset of musculoskeletal cancers. In terms of tissue characterization, DWI may be an adjunct to the more conventional MR imaging techniques but should be interpreted along with the signal of the lesion as observed on conventional sequences, especially in musculoskeletal cancers. Regarding the monitoring of response to therapy in cancer or inflammatory disease, the use of ADC value may represent a more reliable additional tool but must be compared to the initial ADC value of the lesions along with the knowledge of the actual therapy.

Unusual case of tetraparesis in a patient with systemic lupus erythematosus.

We describe the case of a 67-year-old Asian female patient suffering from severe systemic lupus erythematosus (SLE), including biopsy-proven glomerulonephritis, since the age of 40 who was admitted for tetraparesis. Neurological examination confirmed proximal muscular weakness, hypoesthesia and diminished tendon reflexes. The patient suffered from extremely severe Jaccoud's arthropathy. Magnetic resonance imaging (MRI) demonstrated severe narrowing of the upper spinal canal due to a soft tissue mass surrounding the odontoid process, assumed to be a synovial pannus, causing myelopathy. The patient was treated with three intravenous pulses of methylprednisolone with prompt and full clinical recovery. Follow-up MRI confirmed considerable regression of the pannus. Inflammatory transverse myelopathy is the most common explanation for para/tetraparesis in SLE. However, in this case, the symptoms were caused by atlantoaxial synovitis, which is more typical for rheumatoid arthritis.

Imaging ACL reconstructions and their complications.

Examination of ligament reconstructions, particularly of the anterior cruciate ligament (ACL), are common situations in everyday knee imaging practice. Knowledge of normal appearances, the expected changes over time and the potential complications of these plasties are essential. MRI is the imaging method of choice. This article illustrates the main complications specific to this procedure: suboptimal positioning of the femoral or tibial tunnels, impingement between the graft and bony contours, rupture (partial or complete) of the plasty due to friction or injury, arthrofibrosis and particularly the "Cyclops" syndrome, fragmentation or migration of the fixation materials and a granulomatous reaction to biomaterials.

Vertebral sarcoidosis: long-term follow-up with MRI.

Vertebral involvement in sarcoidosis is rare and its clinical and imaging features are non-specific. Indeed, because the lesions are hard to differentiate from metastatic disease based on imaging alone, a histological confirmation is advised. Fatty replacement is a well-known finding indicating stabilization and healing in both benign and malignant conditions. It can be used as an indicator of a favorable disease course and response to treatment. We report the case of a 43-year-old woman with multifocal vertebral sarcoidosis lesions and long-term follow-up showing progressive and gradual fatty involution on magnetic resonance imaging (MRI) during 4 years of steroid treatment with a final favorable outcome.

MRI for response assessment in metastatic bone disease.

BACKGROUND: Beyond lesion detection and characterisation, and disease staging, the quantification of the tumour load and assessment of response to treatment are daily expectations in oncology. METHODS: Bone lesions have been considered "non-measurable" for years as opposed to lesions involving soft tissues and "solid" organs like the lungs or liver, for which response evaluation criteria are used in every day practice. This is due to the lack of sensitivity, specificity and measurement capabilities of imaging techniques available for bone assessment, i.e. skeletal scintigraphy (SS), radiographs and computed tomography (CT). RESULTS: This paper reviews the possibilities and limitations of these techniques and highlights the possibilities of positron emission tomography (PET), but mainly concentrates on magnetic resonance imaging (MRI). CONCLUSION: Practical morphological and quantitative approaches are proposed to evaluate the treatment response of bone marrow lesions using "anatomical" MRI. Recent developments of MRI, i.e. dynamic contrast-enhanced (DCE) imaging and diffusion-weighted imaging (DWI), are also covered. KEY POINTS: • MRI offers improved evaluation of skeletal metastases and their response to treatment. • This new indication for MRI has wide potential impact on radiological practice. • MRI helps meet the expectations of the oncological community. • We emphasise the practical aspects, with didactic cases and illustrations.

Cartilaginous tumours and calcified lesions of the hand: a pictorial review.

Cartilaginous tumours of the extremities are commonly seen in radiographs. Enchondroma is the most frequently encountered tumour. Since the vast majority of enchondromas are asymptomatic, they are typically discovered as incidental findings or along with a pathologic fracture. The authors propose a pictorial review to illustrate the imaging features of cartilaginous bone lesions of the hand and their specificities, and discuss the main differential diagnoses.

[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.

[Comparison of lumbar spinal canal measurements on MRI and CT]. / Comparaison des mesures du canal lombaire en IRM et TDM.

PURPOSE: To compare AP diameter measurements of spinal canal and thecal sac on MRI and CT. MATERIALS AND METHODS: The AP diameter of the spinal canal at L4 and thecal sac at L4-5 were measured on both MRI and CT performed on patients at less than one month interval. Measurements were obtained from axial CT images of the abdomen on CT and sagittal T1W (n = 98) and T2W (n = 78) MR images of the spine. The examinations were reviewed at more than 24 hours interval. Radiologists were blinded. Inter-observer agreement evaluation was performed prior to this study. Measurements were compared using a t test for paired variables. RESULTS: For the spinal canal, mean measurements were 0.4 +/- 1.5mm inferior on CT compared to MRI. For the thecal sac, mean measurements were 0.1 +/- 1.4mm inferior on CT compared to MRI. CONCLUSION: Measurements on CT and MRI for lumbar spinal canal and thecal sac are fairly comparable, with mean measurement differences inferior to the degree of precision of the measurement technique itself.

Fracture-associated and idiopathic subchondral vertebral lesions: a magnetic resonance study in autopsy specimens with histologic correlation.

OBJECTIVE: The aim of this study was to describe and compare the magnetic resonance (MR) and histological appearance of subchondral vertebral lesions that are idiopathic or that develop with vertebral fractures. MATERIALS AND METHODS: T1- and T2-weighted spin-echo images and radiographs were obtained in 81 cadaveric spine specimens. All subchondral vertebral lesions that were considered to be idiopathic or associated with vertebral end plate fractures were selected. Lesions due to growth disturbance were excluded. Radiographs and MR images were analyzed in consensus by two radiologists, and sampled specimens were analyzed by a pathologist. RESULTS: Eleven idiopathic and ten fracture-associated vertebral lesions were available. On T1-weighted images, all lesion signal intensity was low and homogeneous. On T2-weighted images, all idiopathic lesions showed a heterogeneous signal with a central low or intermediate signal component and a peripheral high or intermediate component. All but one fracture-related lesions showed a homogeneous intermediate to high signal intensity. Histological analysis of idiopathic lesions showed a central acellular fibrous connective tissue in all cases surrounded by loose connective tissue in nine cases. Herniated disk material and cartilage metaplasia were found in one lesion only. Fracture-associated lesions contained herniated disk material, necrotic tissue, and loose connective tissue with a peripheral component of loose fibrovascular connective tissue in four cases only. CONCLUSION: MR and histological appearance of idiopathic and fracture-associated subchondral vertebral lesions differ, suggesting that they might have a different origin.

[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.

[Principles of analysis for sacroiliac joints imaging]. / Principes d'interpretation de l'imagerie des articulations sacro-iliaques.

Interpretation of sacroiliac joints imaging is uneasy. Simultaneous erosions, hyperostosis, and ankylosis together make the diagnosis of inflammatory lesions. Articular abnormalities may also be induced by mechanical stress or ligament ossifications. Distribution of the lesions can help to establish a precise diagnosis. Inflammatory lesions may be located in any part of the articulation, including the posterior and inferior part. Mechanical lesions as in osteitis condensans ilii are commonly located in the anterior middle part of the joint. Ligament ossification in case of idiopathic skeletal hyperostosis is located at the margins of joint. The basic for the interpretation of sacroiliac joints is to look at high quality plain radiographs. When diagnosis is uncertain, complementary methods must be considered. CT is useful for analysis of subacute or chronic lesions and MRI is to be preferred for acute lesions, in young patients and when searching for signs of inflammatory activity in an already known chronic disease.