2. Introduction
● Aimed to measure renal function with
radiopharmaceuticals.
● Functional and anatomic information
● Range variesfrom
● urine countingand crude probe detectors
● measurements of plasma clearance, dynamic functional
imaging
● Single-photon emission computed tomography
(SPECT) cortical imaging.
3. Indications
● Blood flow abnormalities
● Function quantification and Differential function
● Glomerular filtration rate, effective renal plasma flow
● Mass vs. column of Bertin
● Obstruction: Uteropelvic junction, ureteral
● Pyelonephritis
● Renal failure: Acute and chronic
● Renovascular hypertension/renal artery stenosis
● Renal vein thrombosis
● Surgical complications
● Transplant rejection and anastomosis assessment
● Trauma
● V
esicoureteral reflux
● V
olume quantification: Bladder residual volume
4. Physiology
● Normally, the kidneys receive 20% of cardiac output,
with renal plasma flow (RPF) averaging 600 mL/min
● Clearance (mL/min) = Urine concentration (mg/mL) × Urine flow
(mL/min) / Plasma concentration (mg/mL)
● Plasma clearance occurs by glomerular filtration and
tubular secretion
5. Clearence
● First passextraction is
usually< 100%, the term
effectiverenal plasmaflow
(ERPF) is used to describe
the measurement
● ~20%ofRPF (120
mL/min) is filtered through
the semipermeable
membrane ofthe
glomerulus
● Tubular secretion accounts
for 80%ofrenal plasma
clearance
6. NUCLEAR SCINTIGRAPHY
TECHNIQUES
● 2D Scintigraphy - use of internal radionuclides to create
two-dimensionalimages.
● 3D SPECT - tomographic technique using gamma camera
data from many projections and reconstructed in different
planes
● HYBRID SCAN - SPECT/CT and PET/CT
7. Renal Radiopharmaceuticals
● Are Classified bytheir uptake and clearance
mechanisms as
● agentsfor glomerular filtration
● Tubular secretion
● Cortical binding.
8. Agents Used to Quantify
● For GFR
● C-14 or H-3 inulin
● I-125 diatrizoate
● I-125 iothalamate
● Co-57 vitamin B12
● Cr-51 EDTA
● In-111 or Yb-169 DTPA
● Tc-99mDTPA
● For ERPF
● H-3 or C-14
paraaminohippurate
(PAH)
● I-125 or I-131
iodopyracet
● I-123, or I-
131orthoiodohippurate
(hippuran)
● Tc-99m
mercaptoacetyltriglycine
(MAG3)
9. Radionuclides for Imaging
●Desirable characteristics
Minimum particulate emission
Primary photon energy between 50-500 keV
Physical T1/2 > time reqd to prepare material
Effective T1/2 longer than examination time
Low toxicity
Stabilityor near stabilityof the product
11. Tc-99m
Mercaptoacetyltriglycine
● Tc-99mMAG3 iscommonlyused
● Asit is protein bound hence(97%) not filtered and
Cleared bytubular secretion shows significant
anatomic details
● Alternative path of excretion is via the hepatobiliary
route.
● The normal time to peakactivityis3 to 5 minutes, with a
time to halfpeak(T½) of 6 to 10 minutes.
● Clearance is bi-exponential, and in patients with normal
renal function, 90% of the dose is cleared in 3 hours.
12. Diethylene triamine
pentaacetic Acid
● Used to examine flow and renal function
● Calculate GFR
● DTPAis aheavy metal chelator used for treatment
ofpoisoning
● Children:1.9 MBq/kg, minimum dose of 1 mCi (37
MBq)
● Adults:5-10 mCi (185-370 MBq)
● 5- 10% plasma protein binding, so it tends to
underestimate the GFR
13. DTPA Kinetics
● After intravenous injection, normal peak cortical uptake occurs
by3 to 4 minutes.(90%filtered in 4hrs.)
● By5 minutes, the collectingsystem is seen
● By10-15 minutes the bladder is typicallyvisualized by
● The T½ peak, or the time it takes for half of the maximal
cortical activity to clear, is normally 15 to 20 minutes for Tc-
99m DTPA.
● Its completely filtered at the glomerulus with no tubular
secretion or reabsorption.
● Asonly 20% of renal function is the result of glomerular
filtration, the 1stpassextraction of aglomerular filtration agent
islessthan that ofagents cleared bytubular secretion
14. Tc-99m Dimercaptosuccinic
Acid
● Cortical imaging with DMSAis m/c to detect renal
scarring or acute pyelonephritis &provide accurate
differential renal function.
● The rapid transit of others (DTPA, MAG3) does not
allow high resolution imagingofthe cortex.
● But the stable cortical uptake of DMSAproduces high
qualityimages usingpinhole imaging SPECT.
● Delayed imaging results in high target-to-background
ratiosand good resolution.
15. DMSA Kinetics
● Upto 40% to 50% of the injected Tc-99m DMSA
dose localizesin the cortex
● Common localisation is in the proximal tubules.
● Imagingis done after a2- to 3-hour delay to allow
time for slow background clearance
● DMSAInhibition in PTsdiseases:- RTA, Fanconi`s
▪ Maximum activity at 3-6 hrs
▪ Images taken at 2 – 4 hrs
● Poor target to background :- Poor renal functions
16.
17.
18. Imaging techniques
● Dynamic functional studies are generally performed
● Perfusion sequence of renal blood flow
●
●
By3 sec aorta is fully visualized.
By5-6 sec, both kidneys are seen.
Maximal kidney activity is reached in 30-60 sec.
● Function seqence Consists of 2 parts.
● Renal blood flow is assessed in the first passof the bolus to
the kidney.
● Over the next 25 to 30 minutes, uptake and clearance assess
function.
23. Renogram Curvers
● The renogramrepresentsasummation ofuptake and
excretion.
● Three phasesare normallyseen:-
● Blood flow
● Cortical uptake
● Clearance phases
24. ● The functional changes are seen by
● Time to peakactivity
● Uptake slope
● Rate of clearance
● Percent clearance at 20 minutes
25. Differential Functions
● calculation is particularly useful because estimated
GFRand serum creatinine may not identifyU/L
lesions
● Normally, the relative contribution for each kidney
liesbetween 45%to 55%
● Acalculation of GFRor ERPFcan be done asa
separate study to quantifyactual function.
● GFR~ 1/3 rd of ERPF
26. Interpretation
● Flow Phase :- seen immediatelyafter flow appears
in the adjacent artery
● first few 2-sec flow frames.
● Asses quality of the injection bolus
● Ifthe slope of the arterial TACis not steep or if
activity visibly persists in the heart and lungs,
the injection may have been given improperly
● asymmetry suggests abnormal perfusion to the
particular side
27. Interpretation
● Cortical Function Phase
● Normallykidneysaccumulate agent in the
parenchymal tissues in the first 1 to 3 minutes
● Cortex appear homogeneous.
● calycesand renal pelvis usually seen in this initial
phase
● “flip-flop” pattern poorly functioning side initially
has lower uptake, but the cortical activityon
later imagesis higher sue to stasis
● delayed cortical washout isanonspecific finding
28. Interpretation
● Clearance Phase
● calyces and pelvis usually begin filling by 3 minutes.
● next 10 to 15 minutes, activityin the kidneyandcollecting
system decreases
● Drainsinto bladder
● Lackof clearance or overlap of PCSstructures on the cortex
suggests HN
● indirect determination of reflux can be done when ureteral
activity persists after the kidneyshave cleared
● Prevoid and postvoid bladder images evaluate emptying
and PVRs
29.
30. Diuretic renography
● In adilated system, prolonged retention of agent is seen
because of areservoir effect.
● Furosemide inj. allows accurate identification of patients
affected by obstruction.
● It’s aloop diuretic that inhibits Na+ &Cl- reabsorption,
markedly increases urine flow and washout in normal
patients.
● Normally the Radiotracer washout is accelerated &In
Obstruction narrow lumen prevents augmented washout
● Lasix isgiven slowlyover 1 to 2 minutes onset of
action within 30 to 60 seconds, maximal effect is seen at
15 minutes : Protocols :- F+20, F+0, F-15
31.
32. Interpretations
● In avery distended systems, delayed washout maybe
seen regardless of whether obstruction is present.
● An“indeterminate” clearance pattern is seen with
little change on the imagesor TAC
● Diuretic response may also be diminished in patients
with azotemia in such cases an increased furosemide
dose or early diuretic infusion (F-15) maybe used.
● If the GFRon the affected side is less than 15
mL/min, diuretic renography is unreliable.
34. OReilly` s Curves
● Response curves to Furosemide
● Curve Patterns
● Type I Normal Non-obstructed
● Type II Progressive TracerAccumulation-
Obstruction
● Type IIIa Rapid respose to Frusemide after initial
accmulation
● Type IIIb Poor response to Frusemide (equivocal)
● Type IV delayed compensation(delayed double
peaks) (Homsy`ssign)
35.
36. Diuretic Renal Scan
Washout
(diuretic response)
T1/2
time required for 50% tracer to leave
the dilated unit
i.e. time required for activityto fall
to 50%of peak
37. ● Clearance half time or washout half time (T½)
quantifications ofthe collecting system
● Another method for T ½ estimation is to fit acurve
to the steepest portion of the washout TAC.
● Normal
● Obstructed
● Indeterminate
< 10 min
> 20 min
10 - 20 min
38.
39. ACEinhibition renography
● Captopril
● Indicated in patients at moderate to highrisk for RVH.
● severe hypertension/resistant to Rx
● abrupt or recent onset
● onset under the age of30 yrs. or over 55 years
● Abdominal or flank bruits
● Worsening Renal parameters afterACEinhibitor Rx
● sensitive, non-invasive functional method or diagnosing
RVH.
● It blocks the conversion ofA
TItoATII causingfall in
GFRin Pts ofRVH whorely on compensatory
mechanism to maintain.
40. Protocols
● Stop allACEinhibitors 2-3 daysfor captopril &5-
7 days for longer acting such asenalapril and lisinopril
● Also Stop angiotensin receptor blockers and calcium
channel blockers(cause false+ve )
● 2-Day/1-day protocol
● ACEinhibitors cause adrop in GFR decreases
urine flow that can be visualized during the functional
portion of the study as adiminished function
41. ● In DTPAthe degree ofchange from baseline is
significant
● Greater the change, the higher the probabilitythat
RASis causingsignificant RVH.
● A10% decrease in relative function or adecrease in
absolute function GFRgreater than 10%is
considered “high probability”/positive
● Achange of5% to 9% is intermediate/boderline
● AdelayedMAG3washoutandthe primary finding
will be cortical retention (cortical staining)
42. Transplant
● Renal allograft evaluation isperformed usingthe dynamic
scintigraphy protocol with Tc-99m MAG3
● Camera is placed anterior, centred over the allograft in the
lower pelvis.
● Someportion of the bladder is included, the entire bladder is
included on pre-void and post-void images.
● Ifconcern for RASexists ACEinhibitor protocol isused.
● The diuretic renography protocol is employed in
hydronephrosis or obstruction.
● Delayed images over the course of 1 to 2 hours used to clarify
the cause of fluid collections and assesspossible urine leaks.
● Acute Rejection v/sV
asomotor Nephropathy
43. GFR
● Accurate quantification of GFRand ERPFwith
nonradioactive inulin and PAH isdone
● continuous infusion required to achieve asteadystate
and multiple blood and urine samples.
● AgentsLike Tc-99m DTPAand I-131 OIH or Tc-
99m MAG3) used for estimation
● camera-based techniquesare employed
44. GFREstimation
● Asmall known dose of DTPAiscounted at aset distance from
the camera face to determine the count rate before injecting it
into the patient.
● The actual administered dose is then corrected for the post
injection residual in the syringe &serves asastandard.
● Overestimation of GFRmay occur if excess dose is counted.
● The imagesare acquired for 6 minutes.
● Counts in background are subtracted andAttenuation of the
photonscaused byvaryingrenal depth iscorrected using
formulabased on patient weight and height.
● The fraction of the standard taken up by the kidneys in the 1-
to 2.5-minute or 2- to 3-minute frames can be correlated with
GFR
45. Cortical Imaging
● Tc-99m DMSAoffers superior cortical resolution due
to itssignificant cortical binding.
● Commonly, DMSAis used to evaluate suspected
pyelonephritis or to possibly detect renal scarring in a
patient with reflux.
● Occasionally, cortical scintigraphy is used to
differentiate aprominent column of Bertin seen on
ultrasound from atrue mass
● For acute pyelonephritis DMSAis considered the
gold standard.
47. Method
● Here dynamic imaging is not performed
● Background clearance is slow and the kidney clears
only asmall percentage of the radiotracer.
● Delayed cortical planar or SPECTimaging is acquired
● Planar imaging usually requires at least both posterior
and posterior oblique views.
● Apinhole collimator or converging collimator
provides magnification and improved resolution.
● SPECThas excellent image detail(better resolution)
48. Imaging
● normal DMSA homogeneousdistribution
throughout the renal cortex
● Upper polesappear lessintense splenic
impression, fetal lobulation, and attenuation from
liver and spleen.
● The central collecting system and medullary regions
are photon deficient because DMSAtubular binding
occurs in the cortex.
49. Interpretations
● DMSAscanwill showradiotracer uptake in acolumnof
Bertin but not in amasscaused by tumour
● Areas of cortical tubular dysfunction from infection or
scarpresent ascortical defects(focal, ill definedor
multifocal)
● Tumour will present asadefect because cortical scanning
is not specific(correlate with USG)
● Diffuse loss of activity seen in diffuse inflammatory
process
● Scars have alocalized, sharp margins
● Acute scars improve in function ( upto44%) over 6
months f/u scans else are termed chronic scars
50. CYSTOGRAPHY
● MAG3 or Tc-99m sulphur colloid or DTPAare
employed agents
● asked to not void until the bladder is maximally
distended {(age + 2) × 30 = vol. in ml }
● First aPre V
oidingimage is obtained
● SecondlydynamicVoiding images are acquired
● FinallyaPost void film is obtained
●
51. Reflux
● Reflux grades have been described for radiographic
contrast studies
● In this system, criteria include
● The level the reflux reaches
● The dilation of the renal pelvis
● The ureteral dilation and tortuosity.
● But the anatomical resolution is much lower with
scintigraphic methods and calyceal morphologyis not
well defined.
52.
53.
54. EC:- Ethylene Dicysteine
● Metabolite of the L,L-ECD(ethylene cystine dimer)
with cortical uptake
● Secretion in proximal convoluted tubules
● Plasma protein bindingis 50%
● Exact excretion mechanismisnot known
● Clearance is 69-85%of OIH
56. Refrences
● Oxford text book of clinical nephrology-3rd ed.
● EssentialsofNuclear Medicine Imaging – Mettler
● Brenner and Rector’sThe kidney– 9thed.
