1. Materials for medical students
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

2. 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)

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

4. Renal Radiotracers Excretion Mechanisms
GF TS TF Tc-99m DTPA >95%
Tc-99m MAG3 <5% 95%
I-131 OIH 20% 80%
Tc-99m GHA 40%-60% 20%
Tc-99m DMSA some 60%
Semin NM Apr.92

5. Renal Radiopharmaceuticals
Extract. fraction Clearance
Tc-99m DTPA 20% ml/min
Tc-99m MAG % ~ 300 ml/min
I-131 OIH ~100% ml/min

6. Renal Radiopharmaceuticals Dosimetry
DTPA MAG3 GHA DMSA I-131OIH rad/10 mCi rad/5mCi rad/300µCi
Kidney
Bladder
EDE (rem)

7. Choosing Renal Radiotracers
Clin. Question Agent
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

8. Basic Renal Scan Procedure

9. Basic Renal Scintigraphy Patient Preparation
Patient must be well hydrated
Give 5-10 ml/kg water (2-4 cups) min. pre-injection
Can measure U - specific gravity (<1.015)
Void before injection
end of study
Int’l Consens. Comm.
Semin NM ‘99:

10. Basic Renal Scintigraphy Acquisition
Supine position preferred
Do not inject by straight stick
Flow (angiogram) : 2-3 sec / fr x 1 min
Dynamic: sec / frame x min
1-3 min/frame)

11. Basic Renal Scintigraphy Acquisition (cont’d)
Obtain a sec. image over injection 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:

12. International Consensus Committee Recommendations for Basic Renogram
Tracer: MAG3, (DTPA)
Dose: 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:

13. DTPA normal

14. DTPA normal

15. Relative (split) function ROI’s

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/ /44
Borderline 57/ /41
Abnormal > 60/40
Taylor, SeminNM Apr 99

17. Basic Renal Scintigraphy Processing
Time to peak
Best from cortical ROI
Normal < 5 min
Residual Cortical Activity (RCA20 or 30)
Ratio of 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)

18. DTPA flow + scan
GFR = 29 ml/’
Creat = 2.0
L= 33%
R= 67%

19. Renal artery occlusion

20. Rt renal infarct

21. Renogram Phases I. Vascular phase (flow study): Ao-to-Kid ~ 3”
II. Parenchymal phase (kidney-to-bkg): Tpeak < 5’
III. Washout (excretory) phase

22. Renogram curves

23. Evaluation of Hydronephrosis
Diuretic (Lasix) Renal Scan

24. Obstruction
Obstruction to urine outflow leads to obstructive uropathy (hydronephrosis, hydroureter) and may lead to obstructive nephropathy (loss of renal function)

25. 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)

26. 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

27. Diuretic Renal Scan Requirements
Rapidly cleared tracer
Well hydrated patient
Good renal function

28. Diuretic Renal Scan Procedure
Pt. preparation:
prehydration adults - oral or 360ml/m2 iv over 30’ peds ml/kg D %NS
void before injection
bladder catheterization ?

29. Diuretic Renal Scan Procedure (cont’d)
Tracers: Tc-99m MAG 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: sec / frame x min

30. Diuretic Renal Scan Procedure (cont’d)
Void before Lasix
Lasix: 40mg adult, 1mg/kg child iv @ ~10-20 min (when pelvis full) -15min (“F-15” method)
Acquisition for 30 min post Lasix
Assess adequacy of diuresis
Measure voided volume
Adults produce ~ ml urine post-Lasix

31. 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%)

32. pre-Lasix

33. post-Lasix

34. No UPJ obstruction
T1/2
R = 6’
L = 2’

35. Post-Lasix curve

36. Pre-Lasix
10 y/o M

37. Post-Lasix

38. Rt UPJ obstruction
T1/2
R = N/A
F/U - nephrostomy tube placed

39. Lt hydronephrosis
3-wk old baby

40. Lt UPJ obstruction

41. Rt UPJ obstruction
T1/2
R = N/A
F/U - nephrostomy tube placed

42. Lt UPJ obstruction

43. 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

44. 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

45. T1/2 washout
cts
100%
50%
T1/2 min

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)

47. T1/2 Normal < 10 min Obstructed > 20 min
Indeterminate min
Best to obtain own normals for each institution, depending on protocol used

48. Diuretic Renal Scan Interpretation
Interpret whole study, not T1/2 alone
Visual (dynamic images)
Washout curve shape (concave vs. convex)
T1/2

49. 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

50. Effect of catheterization (1)
full bladder, no catheter

51. Effect of catheterization (2)
with catheter in bladder

52. Effect of catheterization (3)
without catheter
with catheter

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 1987:10-14 Upsdell, Br JUrol 1992:

54. Evaluation of Renovascular Hypertension
Captopril Renal Scan (ACEI Renography)

55. Renovascular Disease Renal artery stenosis (RAS) Ischemic nephropathy
Renovascular hypertension (RVH)
RAS  RVH

56. Renovascular Hypertension
Caused by renal hypoperfusion
Atherosclerosis
Fibromuscular dysplasia
Mediated by renin - AT - aldosterone system
Potentially curable by renal revascularization

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%)

58. Renin-Angiotensin System
Angiotensinogen
RAS
Renin
Angiotensin I
Captopril
ACE
Angiotensin II
Aldosterone Vasoconstriction
HTN

59. Effect of RAS on GFR

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

61. ACEI Renography

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 min pre- and during test
ACEI
Captopril 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

63. 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 min.

64. 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

66. ACEI Renography Grading renogram curves

67. 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:

68. 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.

69. Captopril Renal Scan MAG 3

70. Captopril Renal Scan MAG3

71. Captopril Renal Scan MAG 3

73. Captopril Renal Scan MAG 3

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

78. Evaluation of Renal Infection
Renal Morphology Scan (Renal Cortical Scintigraphy)

79. UTI VUR PN may lead to scarring >>> ESRD, HTN
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

80. Renal Cortical Scintigraphy Indications
Determine involvement of upper tract (kidney) in acute UTI (acute pyelonephritis)
Detect cortical scarring (chronic pyelonephr.)
Follow-up post Rx

81. 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

82. 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

83. Renal Cortical Scintigraphy “Cold Defect “
Acute or chronic PN
Hydronephrosis
Cyst
Tumors
Trauma (contusion, laceration, rupture, hematoma)
Infarct

84. DMSA parallel hole collimator

85. Normal DMSA
pinhole
LPO RPO

86. DMSA

87. Acute pyelonephritis DMSA
post L
post R
LEAP
LPO pinhole
RPO

88. Renal Cortical Scintigraphy Congenital Anomalies
Agenesis
Ectopy
Fusion (horseshoe, crossed fused ectopia)
Polycystic kidney
Multicystic dysplastic kidney
Pseudomasses (fetal lobulation, hypertrophic column of Bertin)

89. DMSA horseshoe kidney
parallel pinhole

90. DMSA Lt Agenesis
parallel

91. GHA Crossed ectopia
74% %

93. Radionuclide Cystogram

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.

95. Methods Direct Indirect Tc-99m DTPA or Tc-99m MAG3 Tc-99m S.C. or TcO4
i.v.
no catheter
info on kidneys
need pt cooperation
need good renal fct
Tc-99m S.C. or TcO4
via Foley
can do at any age
VUR during filling
catheterization
Advant.
Disadv.

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

97. RN Cystogram vs. VCUG Advantages Disadvantages
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

98. Normal cystogram
filling voiding post-void

99. VUR - filling phase A

100. VUR - voiding phase & post-voidB

101. Post void residual volume
voided vol x post-void cts pre-void cts - post void cts
RV =

102. Reflux nephropathy
16%
84%