Complex left cerebellar hemisphere mass in a 10-year old sho | Figure 1

CincyKidsRad

Cincinnati Children's Radiology

Complex left cerebellar hemisphere mass in a 10-year old shows marked diffusion restriction on the apparent diffusion coefficient (ADC) image (blue arrow) and hyperintensity on the diffusion image (red). Although juvenile pilocytic astrocytomas are common complex hemispheric lesions in pediatrics, the marked diffusion restriction makes a high grade lesion such as a medulloblastoma much more likely. Diffusion-weighted imaging is a key imaging sequence to help determine grade of pediatric brain tumors, as many may show little to no enhancement or adjacent edema, as here. #NeuroWednesday

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Axial T2 (image 1), T1 postcontrast (image 2), and diffusion weighted image (image 3) show a small dermoid (arrow) adjacent to the lateral wall of the right orbit. The lesion is bright on the T2-weighted image, has mild peripheral enhancement and restricted diffusion. Dermoids are well demarcated masses with fatty content. They typically have a thin rim of peripheral enhancement and restricted diffusion. Dermoids typically present as a painless mass in the region of the orbit, floor the mouth, anterior neck, or nasoglabellar region. #NeuroWednesday


An ADC (apparent diffusion coefficient) image shows very hypointense signal centrally/marked diffusion restriction (arrow). Although a glioblastoma may have some similar imaging features, the T2 hypointense peripheral rim seen on the first image and central diffusion restriction make abscess the primary concern. An abscess typically also has a thinner enhancing rim. An abscess may occur from hematogenous dissemination, but it is important to look for an adjacent infection, such as from complicated mastoiditis or sinusitis, although an identifiable source is not always found. #FridayQuizDay


Sagittal T1 and T2 weighted (image 1) and diffusion weighted (image 2) MR images of the spine shows a spinal epidermoid (arrow) at the L4 level. Spinal epidermoids are uncommon but account for approximately 10% of intraspinal tumors in children. They can be associated with segmentation anomalies. They're characterized on imaging with similar signal characteristics to fluid. The intense restricted diffusion is a key feature of the lesion.


Axial diffusion-weighted (image 1) and apparent diffusion coefficient (ADC) map (image 2) show the lesion (arrow) of the left middle cranial fossa restricts diffusion. This is a common location for an arachnoid cyst. However, an arachnoid cyst should follow cerebral spinal fluid on all imaging sequences including diffusion-weighted imaging. Intracranial epidermoid cysts can mimic an arachnoid cyst. They are differentiated from arachnoid cysts by their restricted diffusion. The ADC map helps to confirm that there is true restricted diffusion and not just T2 shine through. #FridayQuizDay #Quiz #FridayQuiz