RENAL SCINTIGRAPHY.pptx

renal scintigraphy

1. RENAL SCINTIGRAPHY Presenter – Dr.Ahammed Sahal B K ( JR I) Moderator – Dr. Ishank (JR II Senior) Date – 22/01/2024

2. CONTENTS: INTRODUCTION GAMMA CAMERA POSITIONING RADIONUCLIDES DYNAMIC RENOGRAPHY STATIC RENOGRAPHY

3. INTRODUCTION Medical imaging of the kidney using radionuclide material and viewed with a Gamma camera. Also called Nuclear Renography or Radioisotope Renography. Done by injecting a radionuclide material into the intravenous system and it’s progress can be traced using a gamma camera. Radionuclides contain radioactive atoms & when they decay , they emit gamma rays that are detected by the gamma camera.

4. GAMMA CAMERA Consists of :- Collimators – Made of lead, helps maintain image quality. Scintillator(Image crystal) – Converts gamma ray photons to visible light. Photomultiplier tube(PMT) – Converts the visible light to electrical signals. Pre-amplifier – Attached to the back of the PMT to amplify the electrical signal, and send to the computer for encoding and image formation.

5. POSITIONING Posterior - Patient will lie supine or can be seated on a stool where the detector is brought as close as possible to the patient’s back. Right Posterior Oblique(RPO) – To view the right kidney better, with the patient lying sideward on his/her right side. Left Posterior Oblique(LPO) – To view the left kidney better, with the patient lying sideward on his/her left side.

6. RADIONUCLIDES Isotope - T wo or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei. Isotopes attempting to reach stability by emitting radiation are called radionuclides/radioisotopes. Divided into 2 groups: Rapidly eliminated by the kidneys Concentrated in the renal parenchyma for a sufficiently long time

7. Rapidly eliminated by the kidneys:- 99mTc-MAG( mercapto -acetyl-triglycine) 99mTc-DTPA(diethylene triamine penta-acetic acid) 99mTc-GHA(glucoheptonate) 99mTc-LLEC(L,L ethylene cystine) 123I-OIH( orthoiodohippurate ) Concentrated in renal parenchyma for a long time:- 99mTc-DMSA( dimercaptosuccinic acid) 99mTc-GHA

8. 99Tc DTPA ECF distribution Tracer of choice for dynamic renal scintigraphy. 2-6% plasma protien binding Extraction fraction 20 % 90% excreted in urine in first 4 hrs Useful in measuring GFR

9. 99Tc - DMSA 75% Plasma protein binding. Slow renal excretion – retained in renal cortex. 40-65% of injected dose concentrated in renal cortex at 6 hours. Gives best morphological images. Assessment of scarring. Differential renal function.

10. 99Tc – MAG3 It is the most commonly used renal radiopharmaceutical. Excreted by active tubular secretion and remaining by glomerular filtration. Preferred in paediatric patients and patients with poor renal function.

11. IMAGING TECHNIQUES:

12. DYNAMIC RENOGRAPHY Indications :- Evaluation of obstruction. Assessment of renal function following drainage procedures of the urinary tract. Demonstration of vesicoureteric reflux. Assessment of renal transplantation. Renal trauma. Diagnosis of Renal artery stenosis. Contraindications :- Pregnancy

13. Patient preparation :- Should be well hydrated before study Patient is asked to empty their bladder before examination In suspected cases of obstruction, Foley’s should be inserted. IV line is established to avoid extravasations of the tracer. Radiopharmaceuticals used :- 99mTc-MAG(Most common). 99mTc-DTPA 99mTc-LLEC 99mTc-GHA Dose - 0.100 mCi /kg 123I-OIH Dose -0.010

14. Imaging:- Examined in supine position with gamma camera placed underneath the examination table. In children, appropriate immobilisation should be attained during imaging. Once appropriately positioned, a rapid IV bolus of the tracer is injected and simultaneously the acquisition is started. 1 frame/2s is recorded for 1 minute, followed by 1 frame/15s for a duration of 20-30 mins.

15. Parenchymal phase: Visualized 60-120 seconds after the initial vascular distribution of the tracer and shows:- Relative and absolute size of the functional renal parenchyma units Total renal function(kidney/background ratio) Relative or split renal function Overall renal morphology and redistribution of functioning parenchyma Position of the renal units.

16. Cortical transit time :- Interval between IV injection of the radiotracer and its first appearance within the renal collecting system Normally, it’s about 3-6 mins. Normal cortical transit time indicates that the renal parenchymal function is not compromised. Poorer the renal function, longer is the cortical transit time. Conditions which prolong the cortical transit time are:- Ureteral obstruction Acute and chronic pyelonephritis Nephrotoxicity Trauma Renal artery stenosis Renal vein thrombosis Acute Tubular necrosis Allograft rejection

17. Drainage phase:- Passage of radiotracer from the pelvicalyceal system through the ureter into the bladder Most of the radiotracer leaves the renal parenchyma after 20 mins

18. DIURETIC RENOGRAPHY Uses 99mTc-MAG combined with IV Furosemide administered 20-30 mins after injection of the radiotracer. Used to distinguish between simple dilation of the collecting system and true obstruction. Rapid washout of the radiotracer from the kidney indicates simple dilation. Persistence of the radiotracer indicates a degree of obstruction.

19. CAPTOPRIL RENOGRAPHY To evaluate for renal artery stenosis and renovascular hypertension. Patient needs to be well hydrated and not eat anything for atleast 4 hours before the exam. ACE inhibitors or Angiotension receptor blockers(ARBs) should be stopped prior to exam. Baseline study is obtained either one hour after oral captopril(1 mg/kg upto 50 mg) or 15 mins after IV enalapril(0.03 mg/kg). Typical findings of a positive study include:- Split renal uptake Increase in cortical transit time Prolongation of time to peak and r etention of tracer in the renal parenchyma.

20. CORTICAL/STATIC RENAL SCINTIGRAPHY Indications include evaluation of renal scarring or calculation of differential renal function. 99mTc-DMSA is used. Imaging occurs 2-4 hours after radiotracer administration. Imaging techniques:- Planar Renal Scinitigraphy Magnified Renal Scintigraphy SPECT(Single Photon Emission Computed Tomography)

21. REFERENCES AIIMS-MAMC-PGI’s Comprehensive Textbook of Diagnostic Radiology. Chapman and Nakielny’s Guide to Radiological Procedures.

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