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Functional imaging using positron emission tomography (PET) plays an important role in the diagnosis, staging, image-guided treatment planning and monitoring of malignant diseases. PET imaging complements conventional anatomical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). The strength of CT scanning lies in its high spatial resolution, allowing for anatomical characterization of disease. PET imaging, however, moves beyond anatomy and characterizes tissue based on functions such as metabolic rate. Combined PET/CT scanners were introduced commercially in 2001 and a number of technological advancements have since occurred. Radiolabelled tracers such as 18F-fluorodeoxyglucose (FDG) and 18F-fluorothymidine (FLT) allow visualization of various metabolic processes within cancer cells. Many studies in human oncology evaluating the utility of PET/CT have demonstrated clinical benefits. Few veterinary studies have been performed, but initial studies show promise for improved detection of malignancy, more thorough staging of canine cancer and determination of early response and disease recrudescence. [ABSTRACT FROM AUTHOR]

Radiologists interpreting imaging studies of the central nervous system are well acquainted with the findings of various common neuroradiological disorders. This self-assessment module is intended to test the knowledge base of radiologists working in the emergency room setting. [ABSTRACT FROM AUTHOR]

Objective: Diffusion-weighted magnetic resonance imaging (DWI) detects acute ischemic infarcts with high lesion conspicuity. Determination of infarct age is difficult on DWI alone because infarct signal intensity (SIinfarct) on DWI is influenced by T2 properties ("T2 shine-through"). Maps of the apparent diffusion coefficient (ADC) reflect pure diffusion characteristics without T2 effects but have low lesion conspicuity. Thus, in clinical practice, combined use of DWI and ADC maps is required. Exponential DWI (eDWI) is an innovative means of MRI-diffusion data analysis that merges the advantages of DWI and ADC maps. The authors hypothesized that SIinfarct on eDWI would correlate with infarct age. The authors studied 114 consecutive patients who had 120 ischemic strokes with clearly determined onset times and who underwent echo-planar DWI. The eDWI were generated by dividing the signal intensity on DWI by that on the corresponding T2 image on a pixel-by-pixel basis. SIinfarct on eDWI was measured in the lesion core and expressed as a percentage of contralateral control tissue. On eDWI, relative SIinfarct changed significantly with infarct age (P < .0001). When patients were sorted in infarct-age groups, no significant differences were found within the first 120 hours. However, for patients studied within 5 days, the mean relative SIinfarct was significantly higher compared with patients studied > or = 8 days after stroke (P < .05). For all infarcts up to 5 days old, the eDWI signal intensity was higher than control tissue (hyperintense appearance). All infarcts > 10 days old had an eDWI signal intensity lower than control tissue (hypointense appearance). The authors concluded that the use of eDWI, as a single set of images, reliably differentiates acute infarcts (< or = 5 days old) from infarcts > 10 days old. This feature would be expected to be helpful when the distinction between acute and nonacute infarction cannot be determined on clinical grounds. [ABSTRACT FROM AUTHOR]

Transverse myelopathy is an uncommon complication of systemic lupus erythematosus (SLE). Three patients with SLE are reported who developed transverse myelopathy, including the neuropathological findings in one patient on whom necropsy was performed. Paraparesis was present in all three cases, but definite sensory changes were present in only one patient. In two patients, the CSF findings were remarkable for elevated protein and depressed glucose concentrations. Microscopic examination of the brain demonstrated small, scattered foci of recent necrosis consistent with microinfarctions. Striking abnormalities were found in the spinal cord at all levels, including multiple foci of vacuolar spongy degeneration in the peripheral white matter, as well as ballooning of myelin sheaths, swollen axons, myelin pallor, and loss of glial nuclei. The pathological findings in previously reported cases of SLE-related transverse myelopathy are reviewed, and the possible pathogenesis of the findings in our case are discussed. [ABSTRACT FROM AUTHOR]