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
Evaluation of:
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)
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
GF TS TF
Tc-99m DTPA >95%
Tc-99m MAG3 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
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
DTPA normal
Relative (split) function
ROI’s
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
Time to peak
Best from cortical ROI
Normal >> will not wash out
If dilated, non-obstructed >>> will wash out
Can quantitate rate of washout (T1/2)
Diuretic Renal Scan
Indications
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
Rapidly cleared tracer
Well hydrated patient
Good renal function
Diuretic Renal Scan
Procedure
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)
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’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’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 min
Indeterminate 10 - 20 min
Best to obtain own normals for each
institution, depending on protocol used
Diuretic Renal Scan
Interpretation
Interpret whole study, not T1/2 alone
Visual (dynamic images)
Washout curve shape (concave vs. convex)
T1/2
Diuretic Renal Scan
Pitfalls
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)
full bladder,
no catheter
Effect of catheterization (2)
with catheter
in bladder
Effect of catheterization (3)
without catheter with catheter
“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 1987:10-14
Upsdell, Br JUrol 1992:126-132
Evaluation of
Renovascular
Hypertension
Captopril Renal Scan
(ACEI Renography)
Renovascular Disease
Renal artery stenosis (RAS)
Ischemic nephropathy
Renovascular hypertension (RVH)
RAS RVH
Renovascular
Hypertension
Caused by renal hypoperfusion
Atherosclerosis
Fibromuscular dysplasia
Mediated by renin - AT - aldosterone system
Potentially curable by renal revascularization
Renovascular
Hypertension
Prevalence
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
RAS
Angiotensinogen
Renin
Angiotensin I Captopril
ACE
Angiotensin II
Aldosterone Vasoconstriction
HTN
Effect of RAS on GFR
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
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
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
Relative renal uptake (bkg corrected)
Time to peak (Tp) - from cortical ROI
normal 90%)
Marked C-induced change
Low probability RVH (>> do MRA, Duplex US, angio
Evaluation of Renal
Infection
Renal Morphology Scan
(Renal Cortical
Scintigraphy)
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
Determine involvement of upper tract
(kidney) in acute UTI (acute pyelonephritis)
Detect cortical scarring (chronic pyelonephr.)
Follow-up post Rx
Renal Cortical Scintigraphy
Procedure
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
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 “
Acute or chronic PN
Hydronephrosis
Cyst
Tumors
Trauma (contusion, laceration, rupture,
hematoma)
Infarct
DMSA
parallel hole collimator
Normal DMSA
pinhole
LPO RPO
DMSA
Acute pyelonephritis
DMSA
post L post R
LEAP
LPO pinhole RPO
Renal Cortical Scintigraphy
Congenital Anomalies
Agenesis
Ectopy
Fusion (horseshoe, crossed fused ectopia)
Polycystic kidney
Multicystic dysplastic kidney
Pseudomasses (fetal lobulation, hypertrophic
column of Bertin)
DMSA
horseshoe kidney
parallel pinhole
DMSA
Lt Agenesis
parallel
GHA
Crossed ectopia
74%
26%
Radionuclide
Cystogram
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
Direct Indirect
Tc-99m S.C. or Tc-99m DTPA or
TcO4 Tc-99m MAG3
i.v.
via Foley
Advant.
no catheter
info on kidneys
can do at any age
VUR during filling
Disadv. need pt
cooperation
catheterization need good renal
fct
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
Advantages Disadvantages
Lower radiation Cannot detect distal
dose ureteral reflux
(5 vs 300 mrad to No anatomic detail
ovary) Grading difficult
Smaller amount of
reflux detectable
Quantitation of
post-void residual
volume
Normal cystogram
filling voiding post-void
VUR - filling phase
A
VUR - voiding phase &
post-void
B
Post void residual
volume
voided vol x post-void cts
RV =
pre-void cts - post void cts
Reflux nephropathy
16% 84%