genitourinary system
TRANSCRIPT
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.