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
Tc-99m DTPA
Tc-99m MAG3
I-131 OIH
Tc-99m GHA
Tc-99m DMSA
TS
>95%
<5%
95%
20%
80%
40%-60%
some
TF
20%
60%
Semin NM Apr.92
Renal
Radiopharmaceuticals
Extract. fraction
Tc-99m DTPA
Tc-99m MAG3
I-131 OIH
20%
40-50%
~100%
Clearance
100-120 ml/min
~ 300 ml/min
500-600 ml/min
Renal Radiopharmaceuticals
Dosimetry
DTPA
MAG3
GHA
rad/10 mCi
Kidney
Bladder
EDE (rem)
0.2
2.8
0.3
0.15
5.1
0.4
1.6
2.7
0.4
DMSA
rad/5mCi
3.5
0.3
0.3
I-131OIH
rad/300µCi
0.01
0.3
0.03
Choosing Renal
Radiotracers
Clin. Question
Perfusion
Morphology
Obstruction
Relative function
GFR quantitation
ERPF quantitation
Agent
MAG3, DTPA, GHA
DMSA, GHA
MAG3, DTPA, OIH
All
I-125 iothalamate,
Cr-51 EDTA, DTPA
MAG3, OIH
Basic Renal Scan
Procedure
Basic Renal Scintigraphy
Patient Preparation
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
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)
Obtain a 30-60 sec. image over injection site
@ end of study
if infiltration >0.5% dose
clearance
do not report
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
% Lt kid =
net cts in Lt ROI
--------------------------------------- x 100%
net cts Lt + net cts Rt ROI
Normal
Borderline
Abnormal
50/50 - 56/44
57/43 - 59/41
> 60/40
Taylor, SeminNM Apr 99
Basic Renal Scintigraphy
Processing
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)
DTPA flow + scan
GFR = 29 ml/’
Creat = 2.0
L= 33%
R= 67%
Renal artery occlusion
Rt renal infarct
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
Evaluation of
Hydronephrosis
Diuretic (Lasix) Renal Scan
Obstruction
Obstruction to urine outflow leads to
obstructive uropathy
(hydronephrosis, hydroureter)
and
may lead to obstructive nephropathy
(loss of renal function)
Diuretic Renal Scan
Principle
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
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%)
pre-Lasix
post-Lasix
No UPJ obstruction
T1/2
R = 6’
L = 2’
Post-Lasix curve
Pre-Lasix
10 y/o M
Post-Lasix
Rt UPJ obstruction
T1/2
R = N/A
F/U - nephrostomy tube placed
Lt hydronephrosis
3-wk old baby
3164897
Lt UPJ obstruction
3164897
Rt UPJ obstruction
T1/2
R = N/A
F/U - nephrostomy tube placed
Lt UPJ obstruction
3164897
Diuretic Renal Scan
Processing
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)
T1/2
time required for 50% tracer to leave
the dilated unit
i.e. time required for activity to fall
to 50% of peak
T1/2 washout
cts
100%
50%
T1/2
min
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)
T1/2
Normal
Obstructed
Indeterminate
< 10 min
> 20 min
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
<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
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 < 5 min
RCA20 (20 min/peak ratio) - from cortical ROI
normal < 0.3
ACEI Renography
Grading renogram curves
ACEI Renography
Diagnostic 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 ‘96:1876
Semin NM 4/99:128-145
ACEI Renography
Interpretation
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
Captopril Renal Scan MAG3
Captopril Renal Scan
MAG 3
Captopril Renal Scan
MAG 3
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
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
Tc-99m S.C. or
TcO4
Advant.via Foley
can do at any age
Disadv.VUR during filling
catheterization
Indirect
Tc-99m DTPA or
Tc-99m MAG3
i.v.
no catheter
info on kidneys
need pt
cooperation
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
Lower radiation
dose
(5 vs 300 mrad to
ovary)
Smaller amount of
reflux detectable
Quantitation of
post-void residual
volume
Disadvantages
Cannot detect distal
ureteral reflux
No anatomic detail
Grading difficult
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%