Avascular necrosis

Case contributed by Melbourne Uni Radiology Masters

Presentation

Pain in hips and knees.

Patient Data

Age: 50 years
Gender: Female

Tc 99m MDP bone scan

Nuclear medicine

NM Isotope Bone Scan.

Focal and discreet areas of increased isotope activity are noted in both femoral heads and in the region of the tibial plateau on  both sides

The renal transplant is visualized in the right iliac fossa and the bladder contains isotope.

In a renal transplant patient the findings are in keeping with avascular necrosis

Case Discussion

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)

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