Genitourinary System Imaging

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Genitourinary System Imaging

Radionuclide Cystography

-any activity in the upper urinary tracts at any of the phases

-No reflux visualized -all or nearly all voided from bladder

-Have patient void before procedure -inject tracer into tubing connected to bladder catheter -fill bladder until drip slows or voids around catheter -Monitor P-scope for signs of reflux (record amount of saline used at the time that reflux is seen) -Take images of full bladder -Record amount used to fill bladder -Deflate folly balloon and take post void images -measure urine (or weigh diaper) -determine residual bladder volume (ml) voided (ml) x Residual Counts/minutes ------------------------------------------ Max counts/min - Residual counts/minutes

Voiding Phase

-120 second immediate post void static image

Full Bladder Phase

-120 second immediate static of posterior and right/left posterior obliques

Filling Phase

-Dynamic at 5 seconds for 1 minute

-Hang 500ml bag of normal saline 25 cm above table -Image dynamic at 5 sec/frame for 60 seconds -Fill bladder to max using formual: (age+2)x30=volume of bladder in ml

Radiopharmaceutical Options

99mTc-Pertehnate 99mTc-DTPA 99mTc-Sulfur Colloid

-Radionuclide cystography is preferred to iodinated contrast cystography -tracer is injected into tubing connected to bladder catheter

0.5-1mCi

-cover imaging table with absorbent paper -Patient should void prior to exam -written consent for catheterization -weigh new/clean diaper -notate amount of saline from start to finish

-Evaluation and detection of vesicoureteral reflux (VUR)

Morphological Renal Scan

aka cortical imaging

Results

Abnormal

-non uniform uptake/cold spots -no uptake in column of Bertin is indicative of tumor

Normal

-Smooth renal contour -uniform uptake of tracer concentration

-ID Patient, verify order, explain procedure -Patient should void before starting -Inject radiopharmaceutical via IV -Image patient in supine position at 2-4 hours

Static Images

-Image Posterior -Post/RAO/LAO/RPO/LPO -500k total counts per image -If pinhole is used 100k counts or 5 mins

- LFOV gamma camera - parallel hole collimator for differential calculation -Pinhole collimator for cortical images

99mTc-GH (Gluceptate)

-Secreted by glomerular filtration and tubular secretion -permits visuatization of renal blood flow and imaging of renal cortex -must be refrigerated -50% renal clearance in 3 hours

Subtopic

10-15 mCi

99mTc-DMSA (Dimercaptosuccinic Acid

-90% is bound to plasma protients which prevents most glomerular filtration -25-50% of the inject dose is in the kidney with an increase over time -DMSA is taken up in the renal cortex (proximal convoluted tubal -highest radiation dose of all renal due to much longer retention

5 mCi

-patient history (abdominal surgery) -advise patient of exam and timing -void just before exam

-pregancy -patient movement

-detects the amount of functioning renal cortical tissue -ex: detect small renal infarctions, scaring, acute pyelonephritis (typically caused by UTI) -differentiate a prominent column of Bertin from a true mass

Renal scintigraphy w/ Ace Inhibitor

Normal / Abnormal Results

-Patient test positive for RAS if two conditions are met: 1. Ace inhibitors study has a decrease of urine flow 2. Renal study without Ace shows improvement compared to other study

-Administer Captopril or enalaprilat per required timing prior to examination -Record blood pressure every 15 mins after ACE administration -Perform routine renal scintigraphy with renography -Obtain post void image -At termination of imaging a final blood pressure reading is taken -Baseline renal scintigraphy needs to be performed before or after Ace scan to compare results

-Dynamic acquisition -1-2 mins/frame for 20-30 mins

Enalaprilat (Vasotec)

-0.04 mg/kg -IV -15 mins before routine renal scintgraphy -Infused over 3-5 mins

Captopril

-25-50 mg -oral -crush pill in water -1 hour before before routine renal scintigraphy

1-10 mCi

-patient history (abdominal surgery) -Only liquids for 4 hours before exam -Patient should hydrate well before exam -void just before exam -halt captopril for 48hrs prior to exam -halt enalaprilat or lisinopril 1 week before

-pregancy

-Diagnosis or exclusion of Renal Vascular Hypertension (RVH) -Differentiation of RVH from Renal Artery Stenosis (RAS)

Diuretic Renal Scan

aka renal scan with lasix

-Patient is supine -one arm can be at patient's side and other is placed on side table for easy flow injection -bolus of rph inject via IV -IV at antecubital preferred -Sternal notch in top one third of image -Begin flow acquisition immediately after injection -IV inject 40mg of furosemide (lasix) when collecting systems are full, typically at 20 minutes post inject of rph -Continue imaging for ~20 minutes -Have patient void and take post void static

-Dynamic acquisition -20-40 minutes of 20 s/frame

-Single or dual head gamma camera -full field of view for adults -LEAP (all purpose) collimator -128x128 flow -Camera position posterior -Camera anterior if previous kidney transplant

Pharmaceutical

-Furosemide (Lasix) -40mg Dose IV inj -Typically at 20 mins post rph inj

-Cleared by glomerular filtration with minimal binding to the renal parencyma -Useful for Glomerular Filtration Rates (GFR) -Useful for blood flow rates to each kindey -Not commonly used for diuretic renography

-recent iodine contrast study -pregancy -dehydrated patients

-to distinguish between obstructive hydronephrotic and non-obstructive collecting system dilation -caused by vesicoureteral reflux, urinary tract infections, congenital malformations, previous obstruction, or a noncompliant bladder -this test evaluates both renal function and urodynamics in in a single test

Functional Renal Imaging

Normal results

-Renogram time activity curve follows the expected projection -Vascular Transit Phase first 30-60 seconds -Tubluar Concentration Phase occurs 1-5 minutes, contains peak curve -Clearance/Excretion Phase represents down slope of curve -Half-Time Excretion is the expected half of the peak activity clearance normally at 8-12 minutes

Procedure

-Patient is supine -one arm can be at patient's side and other is placed on side table for easy flow injection -bolus of rph inject via IV -IV at antecubital preferred -Sternal notch in top one third of image -Begin flow acquisition immediately after injection

Images

Post Void

-posterior static acquisition for 2 minutes

Function

-Dynamic acquisition -19 minutes of 20 s/frame

Flow Renal Perfusion

-Dynamic acquisition -30 frames x 2s/frame -1 minute total time

Technical Details

-Single or dual head gamma camera -full field of view for adults -LEAP (all purpose) collimator -128x128 flow -256x256 function -Camera position posterior -Camera anterior if previous kidney transplant

Radiopharmaceutical

99mTc-DTPA (Pentetate)

-Cleared by glomerular filtration with minimal binding to the renal parencyma -Useful for Glomerular Filtration Rates (GFR) -Useful for blood flow rates to each kindey

99mTc-MAG3 (Mertiatide)

Facts

-Excreted by tubular secretion -high first pass extraction fraction -rapid plasma clearance -Preferred over DTPA (Pentetate) -Used for Effective Renal Plasma Flow (ERPF)

Dose Amount

10-20 mCi

Patient Preparation

-patient history (abdominal surgery) -Patient should hydrate well before exam -void just before exam

Contraindications

-recent iodine contrast study -pregancy

Indications

-Evaluation of a renal transplant -Evaluation of acute renal failure -Measurement of relative renal function