Metastatic disease, myeloma, and lymphoma are the most common malignant spinal tumors. Hemangioma is the most common benign tumor of the spine. Other primary osseous lesions of the spine are more unusual but may exhibit characteristic imaging features that can help the radiologist develop a differential diagnosis. Radiologic evaluation of a patient who presents with osseous vertebral lesions often includes radiography, computed tomography (CT), and magnetic resonance (MR) imaging. Because of the complex anatomy of the vertebrae, CT is more useful than conventional radiography for evaluating lesion location and analyzing bone destruction and condensation. The diagnosis of spinal tumors is based on patient age, topographic features of the tumor, and lesion pattern as seen at CT and MR imaging. A systematic approach is useful for recognizing tumors of the spine with characteristic features such as bone island, osteoid osteoma, osteochondroma, chondrosarcoma, vertebral angioma, and aneurysmal bone cyst. In the remaining cases, the differential diagnosis may include other primary spinal tumors, vertebral metastases and major nontumoral lesions simulating a vertebral tumor, Paget disease, spondylitis, echinococcal infection, and aseptic osteitis. In many cases, vertebral biopsy is warranted to guide treatment.

Background and Purpose-The goal of this study was to characterize cortical reorganization after stroke and its relation with the site of the stroke-induced lesion and degree of motor recovery using functional MRI (fMRI). Methods-Fourteen stroke patients with an affected upper limb were studied longitudinally. Three fMRI sessions were performed over a period of 1 to 6 months after stroke. Upper limb recovery, Wallerian degeneration of the pyramidal tract, and responses to transcranial magnetic stimulation were assessed. Results-Two main patterns of cortical reorganization were found. Pattern 1 was focusing, in which, after initial recruitment of additional ipsilateral and contralateral areas, activation gradually developed toward a pattern of activation restricted to the contralateral sensorimotor cortex in 9 patients. Five patients were found to have pattern 2, persistent recruitment, in which there was an initial and sustained recruitment of ipsilateral activity. Occurrence of recruitment or focusing seemed to depend mainly on whether the primary motor cortex (M1) was lesioned; persistent recruitment was observed in 3 of 4 patients with M1 injury, and focusing was seen in 8 of 10 patients with spared M1. These patterns had no relation to the degree of recovery; in particular, focusing did not imply recovery. However, there was a clear relation between the degree of recovery and the degree of Wallerian degeneration. Conclusions-These results suggest that ipsilateral recruitment after stroke corresponds to a compensatory corticocortical process related to the lesion of the contralateral M1 and that the process of compensatory recruitment will persist if M1 is lesioned; otherwise, it will be transient.

Individual behavioural data are necessary to discuss the mechanisms of functional improvement following stroke with respect to recovery and/or compensation.

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With arthroplasty being increasingly used to relieve joint pain, imaging of patients with metal implants can represent a significant part of the clinical work load in the radiologist's daily practice. Computed tomography (CT) plays an important role in the postoperative evaluation of patients who are suspected of having metal prosthesis-related problems such as aseptic loosening, bone resorption or osteolysis, infection, dislocation, metal hardware failure, or periprosthetic bone fracture. Despite advances in detector technology and computer software, artifacts from metal implants can seriously degrade the quality of CT images, sometimes to the point of making them diagnostically unusable. Several factors may help reduce the number and severity of artifacts at multidetector CT, including decreasing the detector collimation and pitch, increasing the kilovolt peak and tube charge, and using appropriate reconstruction algorithms and section thickness. More recently, dual-energy CT has been proposed as a means of reducing beam-hardening artifacts. The use of dual-energy CT scanners allows the synthesis of virtual monochromatic spectral (VMS) images. Monochromatic images depict how the imaged object would look if the x-ray source produced x-ray photons at only a single energy level. For this reason, VMS imaging is expected to provide improved image quality by reducing beam-hardening artifacts.

Objective. To investigate the degree of agreement between local rheumatologists/radiologists and central trained readers (external standard) on the presence/ absence of sacroiliitis on radiographs of the sacroiliac (SI) joints.Methods. Patients with inflammatory back pain (duration >3 months but <3 years) suggestive of axial spondyloarthritis (SpA) were included in the Devenir des Spondylarthropathies Indifferérenciées Récentes (DESIR) cohort. Baseline radiographs of the SI joints were interpreted by 2 central readers (modified New York criteria); cases of disagreement were adjudicated by a third reader, yielding a positive or a negative result (central reading). The same radiographs were also interpreted by local radiologists/rheumatologists and were rated as "normal," "doubtful sacroiliitis," "obvious sacroiliitis," or "SI joint fusion" (local reading); positive findings were defined as "at least unilateral obvious sacroiliitis," "bilateral obvious sacroiliitis," or "at least unilateral fusion." Agreement and misclassifications between central readers and between central reading versus local reading were calculated (kappa values).Results. Interreader agreement between the central readers was moderate ( ‫؍‬ 0.54); 108 of 688 radiographs (15.7%) were adjudicated. According to local reading ("at least unilateral obvious sacroiliitis"), 183 of the 688 patients (26.6%) had sacroiliitis, whereas according to central reading, 145 of 688 patients (21.1%) had sacroiliitis. Agreement between local reading and central reading was also moderate ( ‫؍‬ 0.55); 76 of 183 patients (41.5%) with "at least unilateral obvious sacroiliitis" (positive by local reading) and 32 of 109 patients (29.4%) with "bilateral obvious sacroiliitis" or "at least unilateral fusion" (positive by local reading) were rated as "negative" by central reading, and 38 of 505 patients (7.5%) and 68 of 579 patients (11.7%), respectively, without sacroiliitis (negative by local reading) were interpreted as "positive" by central reading.

Heel MRI and PDUS frequently show inflammatory lesions in SpA, particularly in painful heels. However, they were also often abnormal in controls. These results suggest that heel MRI and PDUS cannot be used for the diagnosis of SpA. However, PDUS and MRI may be useful for the depiction and assessment of enthesis inflammatory lesions in patients with SpA with heel pain.

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