10. Applications of DMSAApplications of DMSA
scintigraphyscintigraphy
1.Renal ectopia and anomalies1.Renal ectopia and anomalies
2.Renal masses and pseudomasses2.Renal masses and pseudomasses
3.Infection and scarring3.Infection and scarring
29. • 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)
30. • Tracers: Tc-99m MAG3 5-10 mCi
• Acquisition: supine until pelvis full
(can switch to sitting post- Lasix)
• Flow (angiogram) : 2-3 sec / frame x 1 min
• Dynamic: 15-30 sec / frame x 20-30 min
40. • Off ACEI & ATII receptor blockers x 3-7 days
• Off diuretics x 5-7days
• No solid food x 4 hours
• 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
Patient PreparationPatient Preparation
41. • 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)
• Acquisition: flow & dynamic x 20-30 min.
44. Grade I Mild delay in Tmax (6-11 min using 99m Tc-
DTPA) with a falling excretion phase
Grade 2 More prolonged delay in T max (greater than
11 min) but still with an excretion phase
Grade 3 with marked reduction in function of the
affected kidney
45.
46.
47.
48. • Evaluation of children with recurrent UTI
• 30-50% have VUR
• Follow up after initial VCUG
• Assess effect of therapy / surgery
• Screening of siblings of reflux patients.
49. • Tc-99m
• 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 patient
cooperation
• need good renal
function
AdvantageAdvantage
Disadv.Disadv.
Direct Indirect
50. • 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
Advantages Disadvantages
The intact nephron concept
Independent functioning unit If any part of the nephron is diseased the function of the whole nephron in affected.
Exception is ATN( acute tubular necrosis)
For imaging renal anatomy- DMSA Dimercaptosuccinic acid
For renal perfusion and excretion MAG3 Mercaptoacetylglycylglycylglyine preferred over DTPA (diethylentriamine penta acetic acid) solely excreted by glomerular filretion or by tubular secretion( orthoiodohippurate I 131)
Early disease detection by stressing the function 1.Diuretic and ACE
GFR with DTPA and serial blood samples obtained after injection of tracer
Pseudomasses (fetal lobulation, hypertrophic column of Bertin)
To locate the functioning renal tissue
Differentiate renal cortex from the soft tissue masses in and adjacent to kidneys, to find scars or non functioning areas of renal parenchyma and to establish the functional contribution of an abnormal kidney.
Mutlicystic dysplasic kidney is suspected DMSA is used to confirm total absence of function and differentiate in from other forms of unilateral cystic disease of infancy.
Horseshoe kidney. 99 Tc-DMSA showing bridging renal tissue between the lower poles of both kidneys.
Common location for ectopic kidney is midline of the pelvis often shows parenchymal distortion or dysplasia
Post infective scarring 99mTc-DMSA study showing normal left kidney; scarred right upper pole (arrows).
Renal masses and pseudomasses
Column of bertin confirmed by their concentration of DMSA.
Residual function on one side for conservative surgical procedure( partial nephrectomy)
Bilateral Wilms' tumours. 99 mTc-DMSA study showing extensive replacement of the left kidney; smaller tumour at the hilum of the right kidney.
Tumors, cysts or abscesses shows no uptake of tracer and appears as photon deficient areas in renal images.
Differentiation of AcPN vs. ChPN unreliable
Acute PN produces diminished function in the affected areas often a small subsegmental wedge of the renal cortex.
In more severe cases focal scarring may ensue and local functional deficit becomes permanent.
Scarring is recognized as indentation or discontinuity in the cortical images.
For scarring DMSA should be delayed for at least 3 months after the infective episode
Tc-99m DMSA renal scintigraphy(posterior view):
A. Normal scintigraphy finding.
B. 34 year old woman with acute pyelonephritis who complained of pain and tenderness on right costovertebral angle area. Tc-99m DMSA renal scintigraphy showed focal defect(arrow) on right kidney upper portion.
However, renal ultrasongraphy and IVP study were normal.
Acute pyelonephritisDMSA
For excretion studies 100MBq or up to 200MBq if perfusion imaging is also being performed.
MAG3 Mercaptoacetylglycylglycylglyine preferred over DTPA (diethylentriamine penta acetic acid)
Normal Tc-MAG3 dynamic renal study: (A) Part of the first-pass acquisition showing perfusion of aorta and both kidneys;
(B) selected images from the excretion series with symmetrical uptake and clearance from both kidneys; LK = left kidney; RK = right kidney; Ao = aorta.
(C) renogram curves from the perfusion sequence in the first 30 s (left) and the excretion curves up to 30 min (right).
Standard display of QuantEM 2.0 review screen shows demographic data, dose injected, dose counted on camera, percentage of dose infiltrated, MAG3 (mercaptoacetyltriglycine) clearance, and expected MAG3 clearance, followed by percentage of uptake, Tmax (time to maximum counts), T½ (time to half-peak counts), and 20 min/max ratio (ratio of renal counts at 19-20 minutes to maximum counts) for whole-kidney region of interest (ROI). Voided volume and postvoid residual volume are also displayed. Urine flow rate was not measured. Upper central panel shows 2-second images as initial bolus reaches kidney. Upper right panel shows injection site; just beneath is a frame for viewing dynamic cine images, and pre- and post voiding bladder images. Central panel shows 12 2-minute images followed by postvoid image of kidneys with patient lying on camera in same position as initial images. Lower left panel shows whole-kidney ROIs and whole-kidney renogram curves; lower right panel shows cortical ROIs and cortical renogram curves
DTPA normal
DTPA normal
Relative (split) functionROI’s
Percentage of both kidneys after background has been subtracted
T1/2time required for 50% tracer to leave the dilated unit i.e. time required for activity to fall to 50% of peak
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)
Rapidly cleared tracer, Well hydrated patient, Good renal function
Evaluate functional significance of hydronephrosis
Determine need for surgery
obstructive hydronephrosis - surgical Rx
non-obstructive hydronephrosis - medical Rx
Monitor effect of therapy
(preferred over DTPA)
Don’t give Lasix if
Collecting system still filling
Collecting system not full by 60 min
Collecting system drains spontaneously
Poor ipsilateral fct (< 20%)
Dilated but unobstructed renal pelvis. 99mTc images at 5, 10 and 15 min show rapid uptake and clearance from the left kidney; slower clearance from the right kidney. Renogram curves (bottom right) show normal left side and delayed peak on the right with rapid washout following furosemide (frusemide) injection. LK = left kidney; RK = right kidney; B = bladder.
Low-grade obstruction. 99 nTc-MAG3 diuretic study images at 1, 5 and 20 min show normal uptake and clearance on the right; normal uptake on the left but incomplete clearance. Renogram curves (bottom
right) show normal right side and normal uptake on the left but after an initial fall the excretion curve rises again (Homsy's sign). LK = left kidney; RK = right kidney; B = bladder.
2 day test: post-Capto scan, only if abnormal >> baseline
Right renal artery stenosis.
99m -Tc-MAG3 dynamic study shows reduced blood flow to the smaller right kidney on the perfusion series
(A), delayed excretion on the 15 min image (B), and the renogram curve (C) shows reduced uptake, delayed T max and slower clearance from the right
With MAG3, Tmax occurs earlier than the DTPA time quoted above.
bladder capacity = (age+2) x 30
Acute tubular necrosis. 99mTc-MAG3 study shows perfusion of both kidneys is reduced (A) and excretion images at 1 min (B) and 20 min (C) show persistent retention of the tracer in the kidney with no excretion. Renogram curves (D) show immediate uptake but no clearance. LK = left kidney; RK = right kidney.
Acute oliguria after renal transplantation. Anterior perfusion phase images from 99 mTc-DTPA study show that blood flow to the trans-planted kidney in the right iliac fossa is well maintained. Diagnosis: acute tubular necrosis.
Radionuclide cystography showing reflux.
Selected images from the dynamic sequence obtained during micturition (left) show tracer appearing in the right kidney and ureter as the bladder empties (arrows). Time-activity curves over left and right ureters (right) show no reflux on the left and mild but prolonged episodic reflux on the right.
DMSA Left Agenesis
The lower poles of both kidneys are joined by a bridge of renal tissue which lies anterior to the aorta and vena cava, ureters take a more anterior course may be degree of obstruction where the ureters cross the bridging renal tissue
DMSA- assess the renal function and anatomical abnormality
Unilateral PUJ obstruction. 99 mTc-MAG3 images at 1 min(A), 5 min (B) and 15 min (C), showing typical left hydronephrosis with normal clearance from the right kidney.
Renogram curves (bottom right) show normal clearance on the right and an obstructed left side. LK = left kidney; RK = right kidney; B = bladder.
Isotopic renogram (obtained with technetium mercaptoacetyltriglycine [MAG3]) after captopril shows a markedly depressed renal function in the right kidney. Bottom right, Analogous images show negligible activity in the right kidney. Note that this pattern is more typical for DTPA than MAG3 (as DTPA depends on the glomerular filtration rate for uptake which is decreased after captopril in renovascular hypertension [RVHT]). In severe cases of RVHT, MAG3 uptake can be decreased, as in this case. However, typically, uptake is preserved with decreased cortical excretion.
