Although you can’t possibly know by looking at the single images, for what it is worth, the above cases are; A = metastasis, B = abscess, C = radiation necrosis, D = GBM, E = demyelination, F = contusion.
Radiopaedia Blog : Radiology signs
This case demonstrates the typical circumferential calcification and lucent center of myositis ossificans. The imaging diagosis is not always as clear-cut as it is in this case, and further imaging may be needed. It is important to avoid biopsy of these lesions, especially in the early prolifferative phases, as histologically myositis ossificans can appear similar to osteosarcoma, and lead to inappropriate management. A clinical history of trauma, even minor trauma, can be very helpful.
Spinnaker sign - a neonatal chest radiograph sign of pneumomediastinum. It refers to the thymus being outlined by air with each lobe displaced laterally like spinnaker sails. This appearance may also be termed the thymic wing sign. Bonus radiology signs also demonstrated in this case include left-sided deep sulcus sign of pneumothorax and continuous diaphragm sign of pneumomediastinum.
- Lamellated, layered or onion skin
- Codman triangle
- Spiculated, sunburst or hair on end
Although periosteal reactions may be seen in young and adult populations, the relatively loose attachment and active physiology of the periosteum in children leads to an earlier and more robust reaction to underlying pathology, and is a more sensitive indicator of disease. Lack of a periosteal reaction in adults, who have a tightly adhered and relatively inactive periosteum, is not unusual, even with highly aggressive underlying pathologies. (see the example of adult primary osteosarcoma at the bottom of this post)
Primary osteosarcoma in an adult male. Note the absence of a periosteal reaction.