List four indications for dynamic renal imaging using nuclear medicine.

1. Suspected renal obstruction (furosemide renogram)
2. Suspected renal artery stenosis with resultant hypertension (captopril renogram)
3. Suspected complications from renal transplantation (e.g., acute tubular necrosis, cyclosporine toxicity, rejection)
4. Suspected urine leak in the setting of enal transplantation or ureteral surgery