MRI findings in two bone complications of sickle cell disease (acute pain episode and osteomyelitis)

MRI images in an acute pain episode and a case of osteomyelitis.
(A) A patient with an acute pain episode. An MRI post-contrast T1 image reveals multiple foci of marrow infarction in the right femur with a subperiosteal fluid collection (arrows) and adjacent extraosseous soft tissue inflammation (increased signal intensity in the right medial thigh muscles relative to the left).
(B) A different patient with osteomyelitis. An MRI post-contrast T1 image reveals areas of hypo-enhancement in the left femoral diaphysis relative to the right (dashed arrows), elevation and hyper-enhancement of the periosteum (arrowhead), a subperiosteal fluid collection and knee effusion (indicated by the measurements), and surrounding myositis (increased signal intensity in the muscles of the left thigh relative to the right).
Refer to the UpToDate topic on bone complications of SCD for details of the clinical presentations.