genitourinary system

GENITOURINARY SYSTEM

MOHAN MAKHIJA, M.D.

RADIONUCLIDE GU EVALUATION

• QUANTITATIVE EVALUATION OF RENAL PERFUSION AND FUNCTION

• RENAL ANATOMY -ULTRASOUND AND CT.

• RENAL IMAGING CONFINED TO FUNCTIONAL ANALYSIS

INDICATIONS

• SENSTIVITY TO CONTRAST MATERIAL

• ASSESSMENT OF RENAL FLOW

• DIFFERENTIAL FUNCTIONAL ASSESSMENT

• URETERAL OR PELVIC OBSTRUCTION

• VESICOURETERAL REFLUX

• RENOVASCULAR HYPERTENSION

EXCRETORY FUNCTION

• TWO PRIMARY MECHANISIMS

• A) PASSIVE FILTRATION THROUGH

THE GLOMERUS

• B) ACTIVE SECRETION BY THE

TUBULES

Renal AnatomyRenal Anatomy

Thrall and Ziessman Nuclear Medicine THE REQUISITES

DTPA

• DTPA -CLEARED BY GLOMERULAR FILTRATION -MEASURE GFR

• NORMAL GFR IS 125 ML/MIN

Renal Anatomy and FunctionRenal Anatomy and Function

Thrall and Ziessman Nuclear Medicine THE REQUISITES

MAG 3

• MAG 3 NEARLY IDENTICAL TO HIPPURAN

• IN PRACTICE, 99m Tc-DTPA

• 99m Tc-MAG 3 ARE ROUTINELY USED.

Mechanisms of Uptake for Renal Scintigraphic AgentsMechanisms of Uptake for Renal Scintigraphic Agents

UPTAKE MECHANISM IMAGING AGENT

Glomerular filtration (100%) Tc99m DTPA

Tubular (100%) Tc99m MAG3

Tubular (80%) and glomerular (20%) I-131 and I-123 OIH

Cortical binding (50%) Tc99m DMSA

Glomerular filtration (80%) Tc99m GHA

and cortical binding (20%)

Thrall and Ziessman Nuclear Medicine THE REQUISITES

GFR WITH DTPA

• Tc DTPA USED FOR EVALUATING GFR

• SERIAL IMAGES – SIMILAR TO IVP.

• ACCURATE ESTIMATE OF GFR.

• 90% OF DTPA –FILTERED BY 4 HOURS

• NORMAL DOSE 10-20 mCi I.V.

RENAL CORTICAL AGENTS

• DMSA AND GLUCOHEPTONATE

• DMSA EXCELLENT CORTICAL AGENT

• 40% OF DOSE IN CORTEX AT 6 HOURS.

• ONLY 10% OF TRACER IN URINE.

• BINDS TO SULFHYDRYL GROUPS IN PROXIMALTUBULES

ANATOMIC (CORTICAL) IMAGING

• USUALLY PERFORMED FOR:

• SPACE OCCUPYING LESIONS

• PSEUDOTUMORS - COLUMNS OF BERTIN.

• EDEMA OR SCARRING – ACUTE CHRONIC PYELONEPHRITIS

• DMSA OR GH USING PINHOLE/SPECT

RADIONUCLIDE RENAL EVALUATION

• VISUAL ASSESSMENT OF PERFUSION AND FUNCTION

• RENOGRAPHY (TIME ACTIVITY CURVES REPRESENTATIVE OF FUNCTION)

• QUANTIFICATION OF RENAL FUNCTION (GFR AND ERPF)

• ANATOMIC IMAGING (RENAL CORTEX)

RENAL FUNCTION IMAGING

• DYNAMIC OR SEQUENTIAL STATIC, 3-5 MINUTE DTPA OR MAG3 IMAGES OVER 20-30 MINUTES.

• MAXIMAL PARENCHYMAL ACTIVITY SEEN AT 3-5 MINUTES.

• ACTIVITY IN COLLECTING SYSTEM AND BLADDER BY 4-8 MINUTES.

RENOGRAPHY

• RENOGRAM IS SIMPLY A TIMEACTIVITY CURVE - GRAPHIC OF UPTAKE AND EXCRETION BY THE KIDNEYS.

• CLASSIC RENOGRAM CURVE IS OBTAINED BY USING Tc-MAG3 (TUBULAR SECRETION AGENT)

NORMAL RENOGRAM CURVE

• THREE PHASES:

• FIRST PHASE : VASCULAR TRANSIT FOR 30-60 SECONDS. REPRESENTS THE INITIAL ARRIVAL OF THE RADIOPHARMACEUTICAL IN EACH KIDNEY.

NORMAL RENOGRAM CURVE

• SECOND PHASE:

• CORTICAL OR TUBULAR CONCENTRATION PHASE OF INITIAL PARENCHYMAL TRANSIT.

• OCCURS DURING 1-5 MINUTES AND CONTAINS THE PEAK OF THE CURVE.

NORMAL RENOGRAM CURVE

• THIRD PHASE:

• CLEARANCE OR EXCERETION PHASE. REPRESENTS THE DOWN SLOPE OF THE CURVE AND IS PRODUCED BY EXCRETION OF THE TRACER FROM THE KIDNEY AND CLEARANCE FROM THE COLLECTING SYSTEM.

RENOGRAM DATA

• TIME TO PEAK ACTIVITY. NORMAL IS ABOUT 3-5 MINUTES.

• RENAL UPTAKE RATIOS AT 2-3 MINUTES. IDEALLY 50% EACH.

• 40% OR LESS IN ONE KIDNEY SHOULD BE CONSIDERED AS ABNORMAL.

RENOGRAM DATA

• HALF-TIME EXCRETION IS THE TIME FOR HALF OF THE PEAK ACTIVITY TO BE CLEARED FROM THE KIDNEY. NORMAL IS 8-12 MINUTES

RENOGRAM DATA

• 20 MINUTE TO PEAK RATIO.• THIS IS ACTIVITY MEASURED IN EACH

KIDNEY AT 20 MINUTES AND IS EXPRESSED AS A PERCENTAGE OF PEAK CURVE ACTIVITY.

• IN ABSENCE OF PELVIC CALYCEAL RETENTION OR IF ONLY CORTICAL ROI IS USED, A NORMAL 20 MINUTE MAXIMAL CORTICAL RATIO IS <0.3 OR 30%

RENOGRAM DATA

• 20 MINUTE TO PEAK COUNT RATIO

• AS RENAL FUNCTION DETERIORATES, DELAYED TRANSIT - RESULTS IN AN ABNORMAL RENOGRAM CURVE, WHICH CAN BE QUANTITATED BY USING THIS INDEX.

QUANTITATION OF RENAL FUNCTION

• UP TO HALF OF RENAL FUNCTION, INCLUDING GFR, MAY BE LOST BEFORE SERUM CREATININE LEVELS BECOME ABNORMAL

• DIRECT MEASUREMENT OF GFR AND ERPF, PLAYS AN IMPORTANT ROLE IN ASSESSMENT OF RENAL FUNCTION.

RENAL ARTERY STENOSIS

• SIGNIFICANT RENAL ARTERY STENOSIS (60% TO 75%) DECREASES AFFERENT ARTERIOLAR BLOOD PRESSURE

• THIS STIMUALTES RENIN SECRETION BY JUXTAGLOMERULAR APPARATUS

• RENIN ELICITS PRODUCTION OF ANGIOTENSIN I

RENAL ARTERY STENOSIS

• ANGIOTENSIN I IS ACTED ON BY ACE TO YIELD ANGIOTENSIN II

• ANGIOTENSIN II INDUCES VASOCONTRICTION OF THE EFFERENT ARTERIOLES, WHICH RESTORES GFR PRESSURE AND RATE.

ACEACE--I (Captopril) RenographyI (Captopril) Renography

Angiotensin Converting Enzyme –Inhibitor

Renin – angiotensin –aldosterone axis

Thrall and Ziessman Nuclear Medicine THE REQUISITES

RENAL ARTERY STENOSIS

• ACE INHIBITORS - CAPTOPRIL AND ENALAPRILAT, PREVENT THE PRODUCTION OF ANGIOTENSIN II

• PREGLOMERULAR FILTRATION PRESSURES ARE NO LONGER MAINTAINED

• RESULTS IN SIGNIFICANT DECREASE IN GLOMERULAR FILTRATION.

ACEACE--I I RenographyRenography -- RVHRVH

Thrall and Ziessman Nuclear Medicine THE REQUISITES

ACE INHIBITION

• PATIENTS SELECTION - LIMITED TO- MODERATE TO HIGH PROBABILITY OF RENOVASCULAR HYPERTENSION.

• INITIAL PRESENTATION OF HYPERTENSION IN PATIENTS OLDER THAN 60 YEARS OR YOUNGER THAN 20YEARS

ACE INHIBITION

• SEVERE OR ACCELERATED HTN RESISTANT TO MEDICATION THERAPY

• HTN PREVIOUSLY WELL CONTROLLED BUT NOW DIFFICULT TO MANAGE

• HTN IN PATIENTS WITH OTHER EVIDENCE OF VASCULAR DISEASE

• UNEXPLAINED HTN IN PATIENTS WITH ABDOMINAL BRUITS

ACE INHIBITORS

• DISCONTINUE CAPTOPRIL – 48 HOURS• ENALAPRILAT FOR 1 WEEK• MAINTAIN - IF DEEMED NECESSARY

AND INADVISABLE TO DISCONTINUE• REFRAIN FROM ACEI MEDICATION ON

THE DAY OF THE STUDY• ANTIHYPERTENSIVE DRUGS OF NON-

ACE INHIBITOR CLASSES - OK

PROTOCOL

• SHOULD BE FASTING – ABSORPTION

• 25 TO 50 MG OF ORAL CAPTOPRIL

• BLOOD PRESSURE EVERY 15 MIN/HR

• ALTERNATIVE – IV ENALAPRILAT (VASOTEC) 0.04 MG/KG – MAX 2.5 MG OVER 3 TO 5 MIN

SCINTIGRAPHY

• ONE HOUR AFTER CAPTOPRIL OR

15 MIN AFTER ENALAPRILAT INFUSION

10 mCi 99M Tc-MAG3 OR 99M Tc-DTPA

SOME PROTOCOLS USE IV 40-60 mg OF IV FUROSEMIDE.

AT TERMINATION - FINAL BOOD PRESSURE SHOULD BE OBTAINED

PRECAUTIONS

• IN PATIENTS WITH UNILATERAL STENOSIS AND RENAL INSUFF.

• BILATERAL RAS

• SOLITARY KIDNEY OR TRANSPLANT

• CAPTOPRIL OR ENALPRILAT SHOULD BE USED ADVISEDLY FOR DIAGNOSIS

• MAINTAIN IV ACESS THROUGHOUT THE STUDY

? ONE DAY ? TWO DAY

• DIAGNOSIS OF RAS DEPENDS ON INDUCTION OR WORSENING OF RENAL DYSFUNCTION AFTER ACEI

• A BASELINE STUDY IS EXTREMELY USEFUL – ASSESSING EFFECT OF MEDICATION ON RENAL FUNCTION

ONE STAGE PROTOCOL

• ONE STAGE PROTOCOL – PATIENTS WITHOUT EVIDENCE OF PRE-EXISTING RENAL DYSFUNCTION

• CAPTOPRIL CHALLENGE STUDY PERFORMED FIRST.

• IF NORMAL, A DIAGNOSIS OF RVH IS UNLIKELY (10%). NO BASELINE

DIAGNOSTIC CRITERIA

• HALLMARK OF RVH IS A POST-CAP RENOGRAM - ABNORMAL OR MORE ABNORMAL THAN A BASELINE RENOGRAM WITHOUT CAPTOPRIL

• USING 99M Tc 99m DTPA THE PRINCIPAL FINDING IS DROP IN GFR

SINGLE DAY – TWO STAGE

• BASELINE NONCAPTOPRIL STUDY WITH LOW DOSE 1-2 mCi OF Tc-MAG3

• 40 mg OF FUROSEMIDE AFTER FIRST STUDY-GOOD WASHOUT OF ACTIVITY

• REPEAT STUDY USING CAPTOPRIL SEVERAL HOURS LATER

QUANTITATIVE PARAMETERS

• % OF UPTAKE AT 2-3 MINUTES BY ONE KIDNEY < 40% OF TOTAL

• RETAINED CORTICAL ACTIVITY AT 20 MIN DIFFERING BY >20% OR INCREASE FROM THE BASELINE STUDY OF 0.15 (NORMAL <0.3)

• DELAY IN TTP ACTIVITY OF MORE THAN 2 MIN FROM BASELINE STUDY.

BILATERAL RAS

• BILATERAL ABNORMALITIES OR WORSENING FROM BASELINE.

• DETECTION IS MORE DIFFICULT

• BIL RAS OFTEN BEHAVES IN ASYMMETRIC WAY TO ACEI, THEREFORE DISTINGUISHABLE FROM

CHRONIC PARENCHYMAL RENAL DIS.

S AND S

• SENSTIVITY AND SPECIFICITY OF ACEI RENOGRAPHY SURPASS 90%.

• FALSE +VE STUDIES ARE UNCOMMON

• ABNORMALITIES WITH ACEI BEST SEEN IN RAS OF 60%-90%

• LACK OF SIGNIFICANT RENIN-ANGIOTENSIN COMPENSATION <60%

OBSTRUCTIVE UROPATHY

• ROUTINE RENOGRAPHY MAY NOT DIFFERENTIATE OBSTRUCTION FROM HYDRONEPHROSIS OF A NONOBSTRUCTIVE NATURE.

• DIURETIC RENOGRAPHY DISTINGUISH DILATATION FROM OBSTUCTION.

Diuretic Renography in ChildrenDiuretic Renography in Children

Indications:

UPJ, UVJ obstruction

Hydronephrosis

Post-surgical evaluation

Distention collecting system and back pain

SNM: Procedure Guideline

Diuretic Renography in ChildrenDiuretic Renography in Children

Interpretation criteria – T ½ washout

F+20T ½ <10 min absence of obstructionT ½ 10-20 min equivocalT ½ 10-15 min probably normalT ½ >20 min obstructed

F-15T ½<20 min non-obstructed

SNM: Procedure Guideline

PRE LASSIX

POST LASIX

Renal TransplantsRenal Transplants

FlowFunctionObstructionLeak

Tc99m MAG3 preferred over Tc99m DTPA

Renal TransplantRenal Transplant

Post operative

ATN: flow good

function decreased

Nuclear Nuclear CystogramCystogram -- Reflux GradeReflux Grade

Thrall and Ziessman Nuclear Medicine THE REQUISITES

HIPPURAN

• EVALUATION - TUBULAR SECRETION - WITH HIPPURAN

• 80% -TUBULAR SECRETION. (ABOUT 20%) THROUGH GFR.

RADIOPHARMACEUTICALS

• TUBULAR SECRETION – HIPPURAN – MAG 3

• GLOMERULAR FILTRATION – DTPA

• RENAL TUBULES - CORTICAL IMAGING DMSA AND GLUCOHEPTONATE

RENAL PERFUSION IMAGING

• 10-20 mCi DTPA OR MAG3 I.V.

• SERIAL IMAGES 1-5 SECONDS

• ACTIVITY IN KIDNEYS ABOUT 1 SCOND AFTER THE ABDOMINAL AORTA.

• TIME ACTIVITY CURVES REFLECT RENAL PERFUSION- FIRST MINUTE

TUBULAR SECRETION AGENTS

• IODINE-131 ORTHOIODOHIPPURATE - 99m Tc-MAG3 USED CLINICALLY

• 95% CLEARED BY PROXIMAL TUBULES• EXTRACTION 40% TO 50% (MORE

THAN TWICE OF DTPA)• CLEARANCE MAG3 - FOR ERPF• DOSE 10-20 mCi I.V.

RENAL CORTICAL AGENTS

• DOSE OF DMSA 1-5 mCi I.V.

• HIGH RADIATION DOSE TO THE KIDNEYS (LONG EFFECTIVE T ½)

• DELAYED IMAGES AT 1-3 HOURS.

• DMSA HAS SHORT SHELF-LIFE.

RENAL CORTICAL AGENTS

• GH IS CLEARED GFR AND RT

• EARLY IMAGES RENAL PERFUSION, COLLECTING SYSTEMS AND URETERS

• RENAL CORTEX -WELL VISUALIZED 2-4 HOURS AFTER INJ.

• 10-15% IN RENAL TUBULES -40% IN URINE AT 1 HOUR

• DOSE 10-20 mCi I.V.

QUANTITATION OF RENAL FUNCTION

• THE CLASSIC MEASURES OF RENAL FUNCTION - ABILITY OF THE KIDNEYS TO CLEAR CERTAIN SUBSTANCES FROM THE PLASMA.

• CLEARANCE OF INULIN, WHICH IS ENTIRELY FILTERED, DEFINES GFR.

• CLEARANCE OF PARA AMINOHIPPURATE WHICH IS BOTH FILTERED AND SECRETED BY THE TUBULES, DEFINES RPF

QUANTITATION OF RENAL FUNCTION

• RADIOPHARMCEUTICAL FOR THESE CLEARANCES ARE 99mTc-DTPA FOR INULIN CLEARANCE AND GFR.

• 99mTc-MAG3 - PRIMARILY SECRETED BY THE TUBULES, FOR PAH CLEARANCE AND ERPF.