MR Imaging Knee Synovitis and Synovial Pathology.

Knee synovitis is a common, but nonspecific finding on MR imaging in patients with knee pain, with causes ranging from post-traumatic and osteoarthritis to inflammatory and infectious causes. Synovial thickening, joint effusion, and synovial enhancement are present across the spectrum of etiologies and do not allow differentiation between them in most instances. This article reviews synovial physiology and MR imaging of the normal synovium and synovitis, with discussion of specific pathologies and limited signs that suggest one diagnosis over another. Intravenous contrast is helpful across the spectrum of pathologies to distinguish joint fluid from synovial proliferation.

Deferoxamine as a potential cause of incidentally found T1-hyperintense urine on magnetic resonance imaging.

T1-hyperintense urine can be an incidental finding on MRI with many potential causes, such as prior gadolinium administration or hematuria. This is the case of a 33-year-old female with a history of sickle cell disease complicated by iron overload secondary to chronic transfusions, who has been on multiple different iron chelation regimens. Due to persistent iron overload despite various treatments, the patient was started on a new iron chelation regimen that utilized a protocol involving inpatient admission for high dose IV deferoxamine. While admitted for the administration of this regimen, the patient underwent an MRI due to acute on chronic hip pain; this MRI demonstrated an incidental finding of T1-hyperintense urine. There was no evidence found to suggest that this T1-hyperintense urine was caused by prior gadolinium administration, hematuria, or other typical causes of T1-hyperintensity. This incidental finding was thought to have been caused by the usage of deferoxamine; to our knowledge, there is no previous literature discussing this association. Therefore, the findings of this case report demonstrate that this medication is an important item to keep in mind while evaluating the differential diagnosis of T1-hyperintense urine.

Regional and voxel-wise comparisons of blood flow measurements between dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and arterial spin labeling (ASL) in brain tumors.

The objective of the current study was to evaluate the regional and voxel-wise correlation between dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) measurement of cerebral blood flow (CBF) in patients with brain tumors. Thirty patients with histologically verified brain tumors were evaluated in the current study. DSC-MRI was performed by first using a preload dose of gadolinium contrast, then collecting a dynamic image acquisition during a bolus of contrast, followed by posthoc contrast agent leakage correction. Pseudocontinuous ASL was collected using 30 pairs of tag and control acquisition using a 3-dimensional gradient-echo spin-echo (GRASE) acquisition. All images were registered to a high-resolution anatomical atlas. Average CBF measurements within regions of contrast-enhancement and T2 hyperintensity were evaluated between the two modalities. Additionally, voxel-wise correlation between CBF measurements obtained with DSC and ASL were assessed. Results demonstrated a positive linear correlation between DSC and ASL measurements of CBF when regional average values were compared; however, a statistically significant voxel-wise correlation was only observed in around 30-40% of patients. These results suggest DSC and ASL may provide regionally similar, but spatially different measurements of CBF.