RENAL SCINTIGRAPHY, ADRENAL SCINTIGRAPHY AND ADRENAL VENOUS.pptx

RENAL SCINTIGRAPHY, ADRENAL SCINTIGRAPHY AND ADRENAL VENOUS.pptx

1. RENAL SCINTIGRAPHY, ADRENAL SCINTIGRAPHY AND ADRENAL VENOUS SAMPLING MODERATOR – DR. RAMAKANTH MDRD PRESENTOR – DR. SWETHA

2. INTRODUCTION The nuclear renal scan, also known as renal scintigraphy, is an imaging method that uses radiopharmaceuticals/radiotracers to evaluate renal anatomy, physiology, and pathology. Injected radiopharmaceuticals enter the renal artery and eventually enter renal glomeruli. Radiotracers primarily filtered by glomeruli are useful to evaluate glomerular filtration rates, which is a way to evaluate renal function. Radiotracer secreted by the tubules is used to assess the estimated renal plasma flow. Renal cortical agents predominantly bind to renal tubules within the kidney cortex and allow renal anatomic evaluation

3. INDICATIONS Reno-vascular hypertension Obstructive uropathy Renal anomalies Renal transplant Renal parenchymal infections particularly pyelonephritis and postinfectious scarring Renal masses Renal trauma Ureteric trauma

4. CHOOSING RADIOTRACERS Perfusion MAG3, DTPA Morphology DMSA Obstruction MAG3, DTPA with diuretics Relative function All GFR quantitation EDTA, DTPA Preparation – WELL HYDRATED NO PREMEDICATION/ DIETARY RESTRICTION IN Diuretic renography – Avoid NSAIDS IN ACEI renography – stop ACEI prior

5. DMSA SCINTIGRPAHY / RENAL MORPHOLOGY SCAN Technetium-99m dimercaptosuccinic acid (Tc-99m DMSA): This agent predominantly binds to renal tubular cells in the renal cortex allowing cortical imaging  it is primarily used for cortical anatomy and assessment of pathologies such as renal ectopia or renal scarring. Disadvantages – Exposing the kidney to radiation for longer time- 6hrs Short Shelf life

6. applicATIONS 1 .Renal anomalies Agenesis Renal ectopia Fusion (horseshoe) 2. Renal masses and pseudomasses 3. Infection and scarring

7. Horseshoe kidney. 99 Tc-DMSA showing bridging renal tissue between the lower poles of both kidneys. Common location for ectopic kidney is midline of the pelvis

8. COLD DEFECT AREA OF NO UPTAKE Acute or chronic pyelonephritis - diffuse decreased uptake diffusely enlarged kidney or focal bulging Hydronephrosis Cyst Tumors Trauma (contusion, laceration, rupture, hematoma) Infarct Abscesses

9. Post infective scarring 99mTc-DMSA study showing normal left kidney; scarred right upper pole (arrows).

10. DYNAMIC RENAL SCAN Tracer: MAG3, (DTPA) MAG3 Mercaptoacetylglycylglyine preferred over DTPA ( diethylentriamine penta acetic acid ) Labeling with technetium- 99m gives a lower radiation dose better imaging and measurement statistics

11. A bolus of radionuclide placed in an antecubital vein typically reaches the renal arteries from the aorta within 1 second.  For renal blood flow evaluation, serial dynamic images are acquired every 1 to 2 seconds for up to a minute. The kidneys are usually seen by 5 to 6 seconds from injection and show maximal activity in normal patients by 30 to 60 seconds. To evaluate renal parenchymal function, a series of images are obtained after 1 minute of the renal perfusion phase. Radiotracer activity usually starts appearing in the collecting system or urinary bladder by 4-8 minutes.

12. RENOGRAM Renal anatomy and function are assessed visually from the acquired images. In addition, a time-activity curve is generated based on the series of images, and renal function is quantified Time activity curves are generated by the system's computer based on the assessment of radionuclide activity over a region of interest (ROI). For renograms, the ROI is placed over each individual kidney. Radiotracer activity beyond the kidneys is subtracted out of the image. Information is graphically displayed to about 20 to 30 minutes after radiotracer injection.

13. 1 . VASCULAR PHASE - The first phase is known as the vascular transit phase which represents radiotracer entering the kidneys. It usually lasts about 30 to 60 seconds.  2. PARENCHYMAL PHASE - The second phase is known as the tubular concentration phase or parenchymal transit phase normally lasts 1 to 5 minutes when radiotracer appears in the tubules. It is represented by a peak in the renogram. 3. EXCRETORY PHASE - The third phase is noted by a downslope in the renogram indicating excretion of the radiotracer from the kidneys and clearance from the collecting system. It usually starts at 4-8 minutes after radiotracer injection

14. LASIX OR DIURETIC RENAL SCAN USED IN THE EVALAUTION OF THE HYDROURETERONEPHROSIS Hydronephrosis - tracer pooling in dilated renal pelvis Lasix induces increased urine flow If obstructed >>> will not wash out If dilated, non-obstructed >>> will wash out Acquisition for 30 min post Lasix

15. CAPTOPRIL RENAL SCAN OR ACEI RENOGRAPHY Renal artery stenosis (RAS) Ischemic nephropathy Renovascular hypertension (RVH) Off ACEI & ATII receptor blockers x 3-7 days Off diuretics x 5-7days No solid food x 4 hours Patient well hydrated ACEI Captopril 25-50 mg po (crushed), 1 hr pre-scan

16. Anatomic stenosis of the renal artery results in renal hypoperfusion and it is compensated for by angiotensin-converting enzyme (ACE) activation. This compensation leads to normal GFR and normal renal scan. When Angiotensin-converting inhibitor (ACEI) is administered, this compensation is eliminated and results in a diminution of glomerular filtration. On scintigraphy, this is noted by decreased renal uptake and excretion.

17. GRADING Grade I Mild delay in Tmax (6-11 min using 99m Tc-DTPA) with a falling excretion phase Grade 2 More prolonged delay in T max (greater than 11 min) but still with an excretion phase Grade 3 with marked reduction in function of the affected kidney

18. (A), delayed excretion on the 15 min image (B), and the renogram curve (C) shows reduced uptake, delayed T max and slower clearance from the right

19. Adrenal scintigraphy Functioning adrenal cortex tissue can be visualised by ‘trapping’ a radiolabelled cholesterol precursor. Since the tracer is taken up by the normal cortisol-producing adrenal tissue, this investigation must be performed under dexamethasone suppression when aldosterone or androgen-producing lesions are suspected.

20. Indications 1. Hyperaldosteronism 2. Cushings syndrome 3. Adrenal tumours Radiotracer used – IODINE 131 labelled with 6- IODOMETHYLNORCHOLESTEROL

21. PREPARATION 1. Block unintentional radioactive iodine uptake in the thyroid with sodium or potassium iodide Stop all interacting drugs, such as oral contraceptives, dexamethasone, diuretics, propranolol, ketoconazole, cholestyramine and corticosteroids at least 48 h prior to the investigation If dexamethasone suppression required prescribe 4 mg/day starting one week prior to the administration of the radiopharmaceutical

22. INTERPRETATION . Symmetrical distribution of activity: • Normal pattern. • In Cushing’s syndrome or hyperaldosteronism, one sees symmetrically increased uptake as a result of bilateral hyperplasia and ectopic production of adrenocorticotropic hormone. Unilateral uptake: • Adrenal cortex adenoma • Post adrenalectomy. • Aldosterone or androgen-producing carcinoma. • Adrenal infarction. • Gallbladder visualisation.

23. Asymmetrical distribution of activity: • Normal pattern: the right adrenal gland can be somewhat larger than the left Macronodular hyperplasia (hyperaldosteronism). • Small aldosteronoma . • An aldosterone or androgen-producing carcinoma. • Micronodular hyperplasia (hyperaldosteronism) • Residue after unilateral adrenalectomy.

24. Bilateral absence of uptake: • Adrenal cortex carcinoma • Hormonal therapy. • Hyperlipidaemia, hypercholesterolaemia. • Poor labelling.

25. ADRENAL SCINTIGRAPHY WITH DEXAMETHASONE SUPRESSION Bilateral absence of uptake: • Normal. Unilateral uptake: • Aldosteronoma • Adrenal cortex adenoma (hyperandrogenism) Symmetrical distribution of activity: Normal from the 5th day onwards. Macro- or micronodular hyperplasia (hyperaldosteronism). Secondary aldosteronism, e.g. due to stenosis of the renal artery. Medication (oral contraceptives, diuretics). Dexamethasone administration stopped too early.

26. Adrenal venous sampling Adrenal vein sampling (AVS)  is a procedure where blood is collected from the adrenal veins via a catheter to confirm autonomous hormone production (usually aldosterone), if it is unilateral or bilateral, and to guide further treatment If unilateral, the adrenal gland can be removed; thus curing secondary hypertension in 50 to 80% of the cases that are caused by aldosterone-producing adenoma while the remaining cases show improvement in hypertension treatment . If bilateral, the hypertension is better controlled medically with aldosterone antagonists.

27. Indication Adrenal vein sampling is commonly performed in the workup of primary aldosteronism (PA), specifically to diagnose bilateral or unilateral production of excessive aldosterone

28. NORMAL ANATOMY

29. ANATOMICAL VARIANTS

30. Preprocedural accessment Identify a fat-poor adrenal adenoma that can mimic an aldosterone-secreting adenoma Identify adrenal cortical adenocarcinoma (rare cause of PA) Assess the (middle) adrenal veins and identify venous variants relevant to the catheter approach e.g. a right adrenal vein originating from or close to an accessory hepatic vein the right adrenal vein arises directly from the posterior wall of the IVC at T12 level the left adrenal vein in most cases unites with the inferior phrenic vein, forming a common trunk which drains into the left renal vein

31. Technique Review of prior imaging cross-sectional Obtain venous access via common femoral vein (usually right) puncture with guiding catheter / microcatheter set-up Placement of selective catheter or sheath in the IVC or common femoral vein Sequential cannulation of the adrenal veins - confirming position with contrast Venous sampling from each adrenal vein and peripheral source (e.g. femoral vein) It may be difficult to aspirate blood from the adrenal vein, likely due to suction causing vessel wall collapse at the catheter tip. Strategies to overcome this include use of a catheter with a single side-hole close to the tip intermittent gentle suction suction using a partially air-filled syringe in order to reduce suction pressure Label all tubes (attention to right vs left)

32. COMPLICATIONS Unrecognised failure to select the adrenal vein. This is most common on the right, where an accessory hepatic vein can mimic the right adrenal vein The right adrenal gland has a variable appearance on venography In addition, contrast injection into an adrenal vein often produces discomfort, whereas contrast injection into an accessory hepatic vein will not  Adrenal vein rupture due to contrast injection reported incidence is 4-10% in rare causes this can lead to adrenal hemorrhage, manifested clinically by severe pain which can persist for 2-3 days, and potentially causing permanent destruction of the gland  1 other complications include groin hematoma, vasovagal response, intraprocedural back pain, infarction, adrenal vein thrombosis and perforation, hypertensive crisis, and adrenal insufficiency

33. THANK YOU