Avascular necrosis


The clue for this case is the identification of the right iliac fossa renal transplant.

Avascular osteonecrosis (AVN) is a serious osseous complication after renal transplantation. Bone scintigraphy and MRI are both useful in the detection of early osteonecrosis after renal transplantation. 

Bone scintigraphy is quite sensitive (~85%) and is the second option after MRI. It is a choice when multiple sites of involvement must be assessed in patients with risk factors. The findings are different accordingly to the time of the scan:

  • early disease: often represented by a cold area likely representing the vascular interruption
  • late disease: may show a "doughnut sign": a cold spot with surrounding high uptake ring (surrounding hyperemia and adjacent synovitis)