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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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Slide 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

Slide 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:

Slide 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

Slide 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

Slide 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

Slide 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

Slide 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

Slide 8

Basic Renal ScanProcedure

Slide 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

Slide 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)

Slide 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

Slide 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

Slide 13

DTPA normal

Slide 14

DTPA normal

Slide 15

Relative (split) functionROI’s

Slide 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

Slide 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)

Slide 18

DTPA flow + scan

GFR = 29 ml/’

Creat = 2.0

L= 33%

R= 67%

Slide 19

Renal artery occlusion

Slide 20

Rt renal infarct

Slide 21

Renogram Phases

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

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

  • III. Washout (excretory) phase

Slide 22

Renogram curves

Slide 23

Evaluation of Hydronephrosis

Diuretic (Lasix) Renal Scan

Slide 24

Obstruction

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

Slide 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)

Slide 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

Slide 27

Diuretic Renal ScanRequirements

  • Rapidly cleared tracer

  • Well hydrated patient

  • Good renal function

Slide 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 ?

Slide 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

Slide 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

Slide 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%)

Slide 32

pre-Lasix

Slide 33

post-Lasix

Slide 34

No UPJ obstruction

T1/2

R = 6’

L = 2’

Slide 35

Post-Lasix curve

Slide 36

Pre-Lasix

10 y/o M

Slide 37

Post-Lasix

Slide 38

Rt UPJ obstruction

T1/2

R = N/A

F/U - nephrostomy tube placed

Slide 39

Lt hydronephrosis

3-wk old baby

3164897

Slide 40

Lt UPJ obstruction

3164897

Slide 41

Rt UPJ obstruction

T1/2

R = N/A

F/U - nephrostomy tube placed

Slide 42

Lt UPJ obstruction

3164897

Slide 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

Slide 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

Slide 45

T1/2 washout

cts

100%

50%

T1/2 min

Slide 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)

Slide 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

Slide 48

Diuretic Renal ScanInterpretation

  • Interpret whole study, not T1/2 alone

  • Visual (dynamic images)

  • Washout curve shape (concave vs. convex)

  • T1/2

Slide 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

Slide 50

Effect of catheterization (1)

full bladder,no catheter

Slide 51

Effect of catheterization (2)

with catheter in bladder

Slide 52

Effect of catheterization (3)

without catheter

with catheter

Slide 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

Slide 54

Evaluation of Renovascular Hypertension

Captopril Renal Scan (ACEI Renography)

Slide 55

Renovascular Disease

  • Renal artery stenosis (RAS)

  • Ischemic nephropathy

  • Renovascular hypertension (RVH)

    RAS  RVH

Slide 56

Renovascular Hypertension

  • Caused by renal hypoperfusion

    • Atherosclerosis

    • Fibromuscular dysplasia

  • Mediated by renin - AT - aldosterone system

  • Potentially curable by renal revascularization

Slide 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%)

Slide 58

Renin-Angiotensin System

RAS

Angiotensinogen

Renin

Angiotensin I

Captopril

ACE

Angiotensin II

Aldosterone Vasoconstriction

HTN

Slide 59

Effect of RAS on GFR

Slide 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

Slide 61

ACEI Renography

Slide 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

Slide 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.

Slide 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

Slide 66

ACEI RenographyGrading renogram curves

Slide 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

Slide 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.

Slide 69

Captopril Renal ScanMAG 3

Slide 70

Captopril Renal Scan MAG3

Slide 71

Captopril Renal ScanMAG 3

Slide 73

Captopril Renal ScanMAG 3

Slide 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

Slide 78

Evaluation of Renal Infection

Renal Morphology Scan (Renal Cortical Scintigraphy)

Slide 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

Slide 80

Renal Cortical ScintigraphyIndications

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

Detect cortical scarring (chronic pyelonephr.)

Follow-up post Rx

Slide 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

Slide 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

Slide 83

Renal Cortical Scintigraphy“Cold Defect “

Acute or chronic PN

Hydronephrosis

Cyst

Tumors

Trauma (contusion, laceration, rupture, hematoma)

Infarct

Slide 84

DMSA parallel hole collimator

Slide 85

Normal DMSA

pinhole

LPO RPO

Slide 86

DMSA

Slide 87

Acute pyelonephritisDMSA

post L

postR

LEAP

LPO pinhole

RPO

Slide 88

Renal Cortical ScintigraphyCongenital Anomalies

Agenesis

Ectopy

Fusion (horseshoe, crossed fused ectopia)

Polycystic kidney

Multicystic dysplastic kidney

Pseudomasses (fetal lobulation, hypertrophic column of Bertin)

Slide 89

DMSAhorseshoe kidney

parallel pinhole

Slide 90

DMSALt Agenesis

parallel

Slide 91

GHACrossed ectopia

74%26%

Slide 93

Radionuclide Cystogram

Slide 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.

Slide 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.

Slide 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

Slide 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

Slide 98

Normal cystogram

filling voiding post-void

Slide 99

VUR - filling phase

A

Slide 100

VUR - voiding phase & post-void

B

Slide 101

Post void residual volume

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

RV =

Slide 102

Reflux nephropathy

16%

84%


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