ACE-inhibitor renal scan

Indications:
  • Evaluation of renal hypertension.

Contraindications:
  • Patient has taken an Ace inhibitor prior to exam.
  • Consumption of food prior to exam without a long enough window in between.
  • Patient still on ARB prior to exam.
  • Iodine IV contrast study on same day.
  • Possible Beta blocker interference with reni production.

Questions asked in Patient History:

List the common questions asked when taking a patient history for this specific procedure.
  • Are you pregnant?
  • Are you currently on any diuretics?
  • Are you allergic to any medications?
  • Are you well hydrated/when was the last time you drank anything and how much did you drink?
  • When was your last meal?
  • Any prior surgeries (possibility of having one kidney or a transplant kidney).
  • Have they had any recent trauma or injury?
  • Do you have a history of hypertension/ pulmonary hypertension.


Radiopharmaceutical information:
  • Radionuclide: Tc- 99m
  • Radiopharmaceutical: Captopril/Vasotec
  • Adult dosing: Captopril pill of 50mg/ Vasotec intravenously 0.04mg/kg
  • Pediatric dosing:Captopril- 100 uCi/kg with a minimum dose of 1.0 mCi (single study). Vasotec-15 uCi/kg (with minimum dose of 150 uCi) and 120 uCi/kg (with a minimum dose of 1.2 mCi) if both studies are performed on the same day.
  • Method of administration:Captopril pill whole or crushed in a little water Orally- 1 hour prior to exam / Vasotec- infused intravenously over 3-5 minutes
  • Method of Localization: compartmental, blood flow
  • Physical Half-life: 6hours

Patient Preparation:

What does the patient need to do prior to coming for the procedure?
  • Keep hydrated
  • Stopped Diuretics
  • Liquids only 4 hrs prior to exam
  • Discontinue ACE inhibitors (3 days for short acting and 5-7 days for long acting)
  • Discontinue angiotensin receptor blockers
  • Discontinue calcium channel blockers
  • Post voiding recommended

Side Effects:

Will the patient feel any different during or after the procedure?

Possible renal failure, hypotension, and allergic reaction.

Equipment Used:
Type of Camera: Large field of view
Collimator used: LEHR

Acquisition Setup:

Photopeak(s): 140keV

Window(s): 20%


Dynamic: View(s)
Matrix: 256 x 256
Time/Frame: 1sec/frame
Number of Frames: 60 frame

Statics: View(s)
Matrix: 256 x 256
Total Counts or Duration: Pre-void 500k cts and post-void 500k cts

Procedure:
Describe the procedure from verifying the requisition to completing the scan. Include any patient instructions pre- or post- injection/scan, delays between injection and imaging, and any side effects.

Patient positioning- native kidney- imaged posteriorly, transplant/ pelvic kidney- imaged anteriorly

Captopril:

Make sure the patient is well hydrated along with stopping all diuretics. Give the patient 50mg of crushed Captopril added to water and have the patient take it by mouth.Wait 1 hour post administration to start scan, making sure to monitor the patient's blood pressure every 15 minutes for the hour wait. After 1 hour post administration, image just like a renal scan: image posteriorly, with the Flow- dynamic at 1sec/frame for 60sec and Function at 30sec/frame for 50 frames (25minutes). Also, perform a pre-void for 500k cts as well as a post-void for 500k cts. This study can be done in one day, with the baseline first and then the Captopril; or we can do a two day study, with Captopril the first day and then the baseline the second day. Some of the possible side effects are hypotension in small women, and possibly an allergic reaction.

Vasotec:


Make sure the patient is well hydrated along with stopping all diuretics. Inject the patient with 0.04mg/kl intravenously given over 5 minutes. Wait 15 minutes post administration to start scan. After 15 minutes post administration, image just like a renal scan: image posteriorly, with the Flow- dynamic as 1sec/frame for 60sec and Function- dynamic at 30sec/frame for 50 frames (25minutes). Also, perform a pre-void for 500k cts as well as a post-void for 500k cts.

Normal Uptake and common varients:
Insert an image of a normal scan. Describe the normal uptake, and any normal varients visualized.

Abnormal Uptake and causes:

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A 60 year old patient experienced a sudden onset of hypertension. Post ACE inhibitor, there is uptake and retention of the radiopharmaceutical in the left kidney with normal function by the right. Pre ACE inhibitor administration, both kidneys demonstrated equal retention and then excretion 49% and 51% respectively. Based upon the studies done, it was found that the woman has renal arterial stenosis.

Artifacts:
Insert an image with an artifact, and explain what the artifact is.


References: