1, heart rate control below 70 beats per minute, you can take heart rate lowering drugs such as Betaxolol or Atenolol. 2.Patients with diabetes who are taking glucose-lowering drugs such as metformin need to stop taking the drug for 48 hours before doing the test, and then continue to stop taking the drug for 48 hours after doing the test before they can continue taking it. 3, patients with hyperthyroidism and patients allergic to iodine preparations are not suitable for such tests. 4. Patients can eat and drink normally before the test.