No specific imaging characteristics

Ultrasound-guided renal biopsy is gold standard

Acute rejection (AR): Nonspecific allograft edema, urothelial thickening

Resistive index (RI) may be elevated, or there may be loss or reversal of arterial diastolic flow

Elevated RI > 0.80 in early postoperative period associated with increased risk of graft failure

Chronic rejection (CR): Cortical atrophy, increased echogenicity, calcification

Color perfusion may be decreased in both AR or CR

Acute tubular necrosis/delayed graft function

Infection

Renal vascular thrombosis

Calcineurin inhibitor toxicity

AR and CR: Diagnosed and staged pathologically

14% in first 3-6 months

Acute cellular rejection most common after postoperative day 4

Symptoms and signs include elevation of creatinine, decreased urine output, fever, graft tenderness and swelling

Interval graft enlargement and tenderness with normal perfusion are suggestive of AR

Poor correlation between RI and rejection

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  Small, hypoperfused, hyperechoic renal transplants are compatible with CR