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Renal Scintigraphy






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Renal Scintigraphy. Materials for medical students. Helena Balon, MD Wm. Beaumont Hospital Royal Oak, Michigan Charles University 3rd School of Medicine Dept Nucl Med, Prague. Renal perfusion and function Obstruction (Lasix renal scan) Renovascular HTN (Captopril renal scan)
Renal Scintigraphy

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Renal scintigraphy l.jpgSlide 1

Renal Scintigraphy

Materials for medical students

Helena Balon, MD

Wm. Beaumont Hospital

Royal Oak, Michigan

Charles University

3rd School of Medicine

Dept Nucl Med, Prague

Indications l.jpgSlide 2

Renal perfusion and function

Obstruction (Lasix renal scan)

Renovascular HTN (Captopril renal scan)

Infection (renal morphology scan)

Pre-surgical quantitation (nephrectomy)

Renal transplant

Congenital anomalies, masses (renal morphology scan)

Indications

Evaluation of:

Renal function l.jpgSlide 3

Renal Function

  • Blood flow- 20% cardiac output to kidneys (1200 ml/min blood, 600 ml/min plasma)

  • Filtration - 20% renal plasma flow filtered by glomeruli (120 ml/min, 170 L/d)

  • Tubular secretion

  • Tubular reabsorption (1% ultrafiltrate - urine)

  • Endocrine functions

Renal radiotracers excretion mechanisms l.jpgSlide 4

Renal RadiotracersExcretion Mechanisms

GF TS TFTc-99m DTPA >95%

Tc-99m MAG3 <5% 95%

I-131 OIH 20% 80%

Tc-99m GHA 40%-60% 20%

Tc-99m DMSAsome 60%

Semin NM Apr.92

Renal radiopharmaceuticals l.jpgSlide 5

Renal Radiopharmaceuticals

Extract. fractionClearance

Tc-99m DTPA 20% 100-120 ml/min

Tc-99m MAG3 40-50% ~ 300 ml/min

I-131 OIH ~100% 500-600 ml/min

Renal radiopharmaceuticals dosimetry l.jpgSlide 6

Renal RadiopharmaceuticalsDosimetry

DTPA MAG3 GHA DMSA I-131OIH rad/10 mCirad/5mCi rad/300µCi

Kidney 0.2 0.15 1.6 3.5 0.01

Bladder 2.85.1 2.7 0.3 0.3

EDE (rem) 0.3 0.4 0.4 0.3 0.03

Choosing renal radiotracers l.jpgSlide 7

Perfusion MAG3, DTPA, GHA

Morphology DMSA, GHA

Obstruction MAG3, DTPA, OIH

Relative function All

GFR quantitation I-125 iothalamate,

Cr-51 EDTA, DTPA

ERPF quantitation MAG3, OIH

Choosing Renal Radiotracers

Clin. Question Agent

Basic renal scan procedure l.jpgSlide 8

Basic Renal ScanProcedure

Basic renal scintigraphy patient preparation l.jpgSlide 9

Basic Renal ScintigraphyPatientPreparation

  • Patient must be well hydrated

    • Give 5-10 ml/kg water (2-4 cups) 30-60 min. pre-injection

    • Can measure U - specific gravity (<1.015)

  • Void before injection

  • Void @ end of study

Int’l Consens. Comm.

Semin NM ‘99:146-159

Basic renal scintigraphy acquisition l.jpgSlide 10

Basic Renal ScintigraphyAcquisition

  • Supine position preferred

  • Do not inject by straight stick

  • Flow (angiogram) : 2-3 sec / fr x 1 min

  • Dynamic: 15-30 sec / frame x 20-30 min

    (display @ 1-3 min/frame)

Basic renal scintigraphy acquisition cont d l.jpgSlide 11

Basic Renal ScintigraphyAcquisition (cont’d)

  • Obtain a 30-60 sec. image over injection site @ end of study

    • if infiltration >0.5% dose do not report clearance

  • Obtain post-void supine image of kidneys @ end of study

Taylor, SeminNM 4/99:102-127

International consensus committee recommendations for basic renogram l.jpgSlide 12

International Consensus Committee Recommendations for Basic Renogram

  • Tracer: MAG3, (DTPA)

    • Dose: 2 - 5 mCi adult, minimum 0.5 mCi peds

  • Pt. position: supine (motion, depth issues)

    • Include bladder, heart

  • Collimator: LEAP

  • Image over injection site

Int’l Consens. Comm.

Semin NM ‘99:146-159

Dtpa normal l.jpgSlide 13

DTPA normal

Dtpa normal14 l.jpgSlide 14

DTPA normal

Relative split function roi s l.jpgSlide 15

Relative (split) functionROI’s

Relative uptake l.jpgSlide 16

Relative uptake

  • Contribution of each kidney to the total fct

    net cts in Lt ROI

    % Lt kid = --------------------------------------- x 100%

    net cts Lt + net cts Rt ROI

    • Normal 50/50 - 56/44

    • Borderline 57/43 - 59/41

    • Abnormal > 60/40

Taylor, SeminNM Apr 99

Basic renal scintigraphy processing l.jpgSlide 17

Basic Renal ScintigraphyProcessing

  • Time to peak

    • Best from cortical ROI

    • Normal < 5 min

  • Residual Cortical Activity (RCA20 or 30)

    • Ratio of cts @ 20 or 30 min / peak cts

    • Use cortical ROI

    • Normal RCA20 for MAG3 < 0.3

  • Residual Urine Volume

    • (post-void cts x void. vol)  (pre-void cts - post void cts)

Slide18 l.jpgSlide 18

DTPA flow + scan

GFR = 29 ml/’

Creat = 2.0

L= 33%

R= 67%

Renal artery occlusion l.jpgSlide 19

Renal artery occlusion

Rt renal infarct l.jpgSlide 20

Rt renal infarct

Renogram phases l.jpgSlide 21

Renogram Phases

  • I. Vascular phase (flow study): Ao-to-Kid ~ 3”

  • II. Parenchymal phase (kidney-to-bkg): Tpeak < 5’

  • III. Washout (excretory) phase

Renogram curves l.jpgSlide 22

Renogram curves

Evaluation of hydronephrosis l.jpgSlide 23

Evaluation of Hydronephrosis

Diuretic (Lasix) Renal Scan

Obstruction l.jpgSlide 24

Obstruction

Obstruction to urine outflow leads to obstructive uropathy(hydronephrosis, hydroureter) andmay lead to obstructive nephropathy(loss of renal function)

Diuretic renal scan principle l.jpgSlide 25

Diuretic Renal ScanPrinciple

  • 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

  • Can quantitate rate of washout (T1/2)

Diuretic renal scan indications l.jpgSlide 26

Diuretic Renal ScanIndications

  • Evaluate functional significance of hydronephrosis

  • Determine need for surgery

    • obstructive hydronephrosis - surgical Rx

    • non-obstructive hydronephrosis - medical Rx

  • Monitor effect of therapy

Diuretic renal scan requirements l.jpgSlide 27

Diuretic Renal ScanRequirements

  • Rapidly cleared tracer

  • Well hydrated patient

  • Good renal function

Diuretic renal scan procedure l.jpgSlide 28

Diuretic Renal ScanProcedure

  • Pt. preparation:

    • prehydration adults - oral or 360ml/m2 iv over 30’ peds - 10-15 ml/kg D5 0.3-0.45%NS

    • void before injection

    • bladder catheterization ?

Diuretic renal scan procedure cont d l.jpgSlide 29

Diuretic Renal ScanProcedure (cont’d)

  • Tracers: Tc-99m MAG3 5-10 mCi (preferred over DTPA)

  • Acquisition: supine until pelvis full (can switch to sitting post- Lasix)

  • Flow (angiogram) : 2-3 sec / fr x 1 min

  • Dynamic: 15-30 sec / frame x 20-30 min

Diuretic renal scan procedure cont d30 l.jpgSlide 30

Diuretic Renal ScanProcedure (cont’d)

  • Void before Lasix

  • Lasix: 40mg adult, 1mg/kg child iv @ ~10-20 min (when pelvis full)or @ -15min (“F-15” method)

  • Acquisition for 30 min post Lasix

  • Assess adequacy of diuresis

    • Measure voided volume

    • Adults produce ~200-300 ml urine post-Lasix

Diuretic renal scan procedure cont d31 l.jpgSlide 31

Diuretic Renal ScanProcedure (cont’d)

  • Don’t give Lasix if

    • Collecting system still filling

    • Collecting system not full by 60 min

    • Collecting system drains spontaneously

    • Poor ipsilateral fct (< 20%)

Pre lasix l.jpgSlide 32

pre-Lasix

Post lasix l.jpgSlide 33

post-Lasix

No upj obstruction l.jpgSlide 34

No UPJ obstruction

T1/2

R = 6’

L = 2’

Post lasix curve l.jpgSlide 35

Post-Lasix curve

Pre lasix36 l.jpgSlide 36

Pre-Lasix

10 y/o M

Post lasix37 l.jpgSlide 37

Post-Lasix

Rt upj obstruction l.jpgSlide 38

Rt UPJ obstruction

T1/2

R = N/A

F/U - nephrostomy tube placed

Slide39 l.jpgSlide 39

Lt hydronephrosis

3-wk old baby

3164897

Slide40 l.jpgSlide 40

Lt UPJ obstruction

3164897

Rt upj obstruction41 l.jpgSlide 41

Rt UPJ obstruction

T1/2

R = N/A

F/U - nephrostomy tube placed

Slide42 l.jpgSlide 42

Lt UPJ obstruction

3164897

Diuretic renal scan processing l.jpgSlide 43

Diuretic Renal ScanProcessing

  • ROI placement

    • around whole kidney or

    • around dilated renal collecting system

  • T/A curve

  • T1/2

    • from Lasix injection vs. from diuretic response

    • linear vs. exponential fit of washout curve

Diuretic renal scan washout diuretic response l.jpgSlide 44

Diuretic Renal ScanWashout(diuretic response)

T1/2time required for 50% tracer to leave the dilated unit i.e. time required for activity to fall

to 50% of peak

T 1 2 washout l.jpgSlide 45

T1/2 washout

cts

100%

50%

T1/2 min

T 1 2 value l.jpgSlide 46

T1/2 value

  • Variables influencing T1/2 value:

    • Tracer

    • State of hydration

    • Volume of dilated pelvis

    • Bladder catheterization

    • Dose of Lasix

    • Renal function (response to Lasix)

    • ROI (kidney vs. pelvis)

    • T1/2 calculation (from inj. vs. response, curve fit)

T 1 2 l.jpgSlide 47

T1/2

  • Normal < 10 min

  • Obstructed > 20 min

  • Indeterminate 10 - 20 min

  • Best to obtain own normals for each institution, depending on protocol used

Diuretic renal scan interpretation l.jpgSlide 48

Diuretic Renal ScanInterpretation

  • Interpret whole study, not T1/2 alone

  • Visual (dynamic images)

  • Washout curve shape (concave vs. convex)

  • T1/2

Diuretic renal scan pitfalls l.jpgSlide 49

Diuretic Renal ScanPitfalls

  • False positive for obstruction

    • Distended bladder

    • Gross hydronephrosis

      T(transit time) = V (volume) F (flow)

    • Poorly functioning / immature kidney

    • Dehydration

  • False negative

    • Low grade obstruction

    • Poorly functioning / immature kidney

Effect of catheterization 1 l.jpgSlide 50

Effect of catheterization (1)

full bladder,no catheter

Effect of catheterization 2 l.jpgSlide 51

Effect of catheterization (2)

with catheter in bladder

Effect of catheterization 3 l.jpgSlide 52

Effect of catheterization (3)

without catheter

with catheter

F minus 15 diuretic renogram l.jpgSlide 53

“F minus 15” Diuretic Renogram

  • Furosemide (Lasix) injected 15 min before radiopharmaceutical

  • Rationale: kidney in maximal diuresis,under maximal stress

  • Some equivocals will become clearly positive, some clearly negative

English, Br JUrol 1987:10-14Upsdell, Br JUrol 1992:126-132

Evaluation of renovascular hypertension l.jpgSlide 54

Evaluation of Renovascular Hypertension

Captopril Renal Scan (ACEI Renography)

Renovascular disease l.jpgSlide 55

Renovascular Disease

  • Renal artery stenosis (RAS)

  • Ischemic nephropathy

  • Renovascular hypertension (RVH)

    RAS  RVH

Renovascular hypertension l.jpgSlide 56

Renovascular Hypertension

  • Caused by renal hypoperfusion

    • Atherosclerosis

    • Fibromuscular dysplasia

  • Mediated by renin - AT - aldosterone system

  • Potentially curable by renal revascularization

Renovascular hypertension57 l.jpgSlide 57

Renovascular Hypertension

  • Prevalence

    • <1% unselected population with HTN

  • Clinical features

    • Abrupt onset HTN in child, adult < 30 or > 50y

    • Severe HTN resistant to medical Rx

    • Unexplained or post-ACEI impairment in ren fct

    • HTN + abdominal bruits

      If these present - moderate risk of RVH (20-30%)

Renin angiotensin system l.jpgSlide 58

Renin-Angiotensin System

RAS

Angiotensinogen

Renin

Angiotensin I

Captopril

ACE

Angiotensin II

Aldosterone Vasoconstriction

HTN

Effect of ras on gfr l.jpgSlide 59

Effect of RAS on GFR

Diagnosis of ras l.jpgSlide 60

Diagnosis of RAS

  • Gold std: angiography

  • Initial non-invasive tests:

    • ACEI renography

    • Duplex sonography

  • Other tests:

    • MRA - insensitive for distal / segmental RAS

    • Captopril test (PRA post-C.) - low sensitivity

    • Renal vein renin levels

Acei renography l.jpgSlide 61

ACEI Renography

Slide62 l.jpgSlide 62

ACEI Renography Patient Preparation

  • Off ACEI & ATII receptor blockers x 3-7 days

  • Off diuretics x 5-7d

  • No solid food x 4 hrs

  • Patient well hydrated

    • 10 ml/kg water 30-60 min pre- and during test

  • ACEI

    • Captopril 25-50 mg po (crushed), 1 hr pre-scan

    • Enalaprilat 40 µg/kg iv (2.5 mg max), 15 min pre-scan

    • Monitor BP q 15 min

Acei renography procedure l.jpgSlide 63

ACEI RenographyProcedure

  • Tracer: Tc-99m MAG3 (or DTPA)

  • Protocol: 1 day vs. 2 day test

    • 1 day test: baseline scan (1-2 mCi) followed by post-Capto scan (8-10 mCi)

    • 2 day test: post-Capto scan, only if abnormal >> baseline

  • Acquisition: flow & dynamic x 20-30 min.

Acei renography processing l.jpgSlide 64

ACEI RenographyProcessing

  • Relative renal uptake (bkg corrected)

  • Time to peak (Tp) - from cortical ROI

    • normal < 5 min

  • RCA20 (20 min/peak ratio) - from cortical ROI

    • normal < 0.3

Slide66 l.jpgSlide 66

ACEI RenographyGrading renogram curves

Acei renography diagnostic criteria l.jpgSlide 67

ACEI RenographyDiagnostic Criteria

  • MAG3:ipsilateral parenchymal retention p.C.

    • change in renogram curve by  1 grade

    • RCA20 increase by  15% (e.g. from 30% to 45%)

    • Tp increase by  2 min or 40% (e.g. from 5 to 7’)

  • DTPA: ipsilateral decreased uptake

    • Decrease in relative uptake  10% (e.g.from 50/50 to 40/60), change of 5-9% - intermediate

    • change in renogram curve by  2 grades

Consens. report JNM ‘96:1876Semin NM 4/99:128-145

Acei renography interpretation l.jpgSlide 68

ACEI RenographyInterpretation

  • High probability RVH (>90%)

    • Marked C-induced change

  • Low probability RVH (<10%)

    • Normal Captopril scan

    • Abnormal baseline, improved p-C.

    • Type I curve - pre- and post-C.

  • Intermediate probability RVH

    • Abnl baseline, no change p-C.

Captopril renal scan mag 3 l.jpgSlide 69

Captopril Renal ScanMAG 3

Slide70 l.jpgSlide 70

Captopril Renal Scan MAG3

Slide71 l.jpgSlide 71

Captopril Renal ScanMAG 3

Slide73 l.jpgSlide 73

Captopril Renal ScanMAG 3

Acei renography77 l.jpgSlide 77

ACEI Renography

  • In normal renal function - sens/spec ~ 90%

  • In poor renal fct / ischemic nephropathy, ACEI renography often indeterminate >>> do MRA, Duplex US, angio

Evaluation of renal infection l.jpgSlide 78

Evaluation of Renal Infection

Renal Morphology Scan (Renal Cortical Scintigraphy)

Slide79 l.jpgSlide 79

UTI

VUR

risk factor for PN,

not all pts w PN have VUR

PN may lead to scarring >>> ESRD, HTN

early Dx and Rx necessary

Clinical & laboratory Dx of renal involvement in UTI unreliable

Renal cortical scintigraphy indications l.jpgSlide 80

Renal Cortical ScintigraphyIndications

Determine involvement of upper tract (kidney) in acute UTI (acute pyelonephritis)

Detect cortical scarring (chronic pyelonephr.)

Follow-up post Rx

Renal cortical scintigraphy procedure l.jpgSlide 81

Renal Cortical ScintigraphyProcedure

Tracers

Tc-99m DMSA

Tc-99m GHA

Acquisition

2-4 hrs post-injection

parallel hole posterior

pinhole post. + post. oblique (or SPECT)

Processing: relative fct

Renal cortical scintigraphy interpretation l.jpgSlide 82

Renal Cortical ScintigraphyInterpretation

Acute PN

single or multiple “cold” defects

renal contour not distorted

diffuse decreased uptake

diffusely enlarged kidney or focal bulging

Chronic PN

volume loss, cortical thinning

defects with sharp edges

Differentiation of AcPN vs. ChPN unreliable

Renal cortical scintigraphy cold defect l.jpgSlide 83

Renal Cortical Scintigraphy“Cold Defect “

Acute or chronic PN

Hydronephrosis

Cyst

Tumors

Trauma (contusion, laceration, rupture, hematoma)

Infarct

Dmsa parallel hole collimator l.jpgSlide 84

DMSA parallel hole collimator

Slide85 l.jpgSlide 85

Normal DMSA

pinhole

LPO RPO

Slide86 l.jpgSlide 86

DMSA

Acute pyelonephritis dmsa l.jpgSlide 87

Acute pyelonephritisDMSA

post L

postR

LEAP

LPO pinhole

RPO

Renal cortical scintigraphy congenital anomalies l.jpgSlide 88

Renal Cortical ScintigraphyCongenital Anomalies

Agenesis

Ectopy

Fusion (horseshoe, crossed fused ectopia)

Polycystic kidney

Multicystic dysplastic kidney

Pseudomasses (fetal lobulation, hypertrophic column of Bertin)

Dmsa horseshoe kidney l.jpgSlide 89

DMSAhorseshoe kidney

parallel pinhole

Dmsa lt agenesis l.jpgSlide 90

DMSALt Agenesis

parallel

Slide91 l.jpgSlide 91

GHACrossed ectopia

74%26%

Radionuclide cystogram l.jpgSlide 93

Radionuclide Cystogram

Indications94 l.jpgSlide 94

Indications

  • Evaluation of children with recurrent UTI

    • 30-50% have VUR

  • F/U after initial VCUG

  • Assess effect of therapy / surgery

  • Screening of siblings of reflux pts.

Methods l.jpgSlide 95

Tc-99m S.C. or TcO4

via Foley

can do at any age

VUR during filling

catheterization

Tc-99m DTPA or Tc-99m MAG3

i.v.

no catheter

info on kidneys

need pt cooperation

need good renal fct

Methods

DirectIndirect

Advant.

Disadv.

Direct cystography l.jpgSlide 96

Direct Cystography

  • 1 mCi S.C. in saline via Foley

  • Fill bladder until reversal of flow

    • (bladder capacity = (age+2) x 30

  • Continuous imaging during filling & voiding

  • Post void image

  • Record

    • volume instilled

    • volume voided

    • pre- and post- void cts

Rn cystogram vs vcug l.jpgSlide 97

Lower radiation dose(5 vs 300 mrad to ovary)

Smaller amount of reflux detectable

Quantitation of post-void residual volume

Cannot detect distal ureteral reflux

No anatomic detail

Grading difficult

RN Cystogram vs. VCUG

AdvantagesDisadvantages

Normal cystogram l.jpgSlide 98

Normal cystogram

filling voiding post-void

Vur filling phase l.jpgSlide 99

VUR - filling phase

A

Vur voiding phase post void l.jpgSlide 100

VUR - voiding phase & post-void

B

Post void residual volume l.jpgSlide 101

Post void residual volume

voided vol x post-void cts pre-void cts - post void cts

RV =

Slide102 l.jpgSlide 102

Reflux nephropathy

16%

84%


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