Diagnosis of Urinary Tract Obstruction: Techniques …nucleus.iaea.org/HHW/NuclearMedicine/PaediatricsandNeph...Diagnosis of Urinary Tract Obstruction: Techniques and Limitations Isabel

Diagnosis of Urinary Tract Obstruction: Techniques and Limitations

Isabel Roca, MDHU VALL HEBRONBarcelona, Spain

123I-OIH99mTc-EC

99mTc-MAG3

123I-OIH

99mTc-DMSA99mTc-GH

99mTc-DTPA • Renography (RNG) F0:• definitely established

• RNG: +++ Parameters • excretory • post-gravitatory

Accepted Indications• RNG F0

• Prenatal hydronephrosis• DMSA

• Acute pyelonephritis• Scars

• CYSTOSCINTIGRAPHY• RNG TX• RNG + CAPTOPRIL

Diurectic radionuclide renography easily detects whether a partial or total obstruction is present

The diuretic renogram in the clinical management of neonatal hydronephrosis

NO OBSTRUCTION

• preserved bilateral renal function• moderate dilation of urinary tract

• asymmetric renal function• urinary tract dilation

OBSTRUCTIVE PROFILE

When the pediatrician orders a diuretic renogram, what does he/she wants to know?

SURGERY?? yes / no

Can we answer the question? NOCan we help decide? YES

HOW?

When the pediatrician orders a diuretic renogram, what does he/she wants to know?

SURGERY yes or no??

Providing information about:- renal function- excretory pattern

HOWCan we help the pediatrician evaluate

a patient with hydronephrosis?

OBSTRUCTIONObstacle to urine drainage which, left without treatment, may affect renal function

(Koff, Peters)

PROCEDURE:- Technique- Patient preparation

INTERPRETATION:- Images- Curves- Quantitative parameters

OBSTRUCTIVE PROFILE ???

INTERPRETATION OF DIURETIC RENOGRAM

IN CHILDREN

There are as many protocols as NM services !A comprehensive, complete software package is lacking

Oral hydrationFor a baby, best possible hydration is lactation

F-15 F0 F+15 F+20 ??Probably all options are valid and clinically useful

"Well tempered renography”

Diuretic renogram

Europe

USA

• difficulties: centers with different protocols, controversies in interpretation

Published GUIDELINES:Gordon I, Colarinha P, Fettich J et al.Guidelines for standard and diuretic renography in children.Eur J Nucl Med 2001; 28 : BP21–BP30O'Reilly P, Aurell M, Britton K, Kletter K, Rosenthal L, Testa T.Consensus on diuresis renography for investigating the dilated upper urinary tract. Radionuclides in Nephrourology Group. Consensus Committee on Diuresis Renography.J Nucl Med 1996; 37 : 1872–6BJU 2003; 91:239–243Conway JJ, Maizels M.The ‘well tempered’ diuretic renogram: a standard method to examine the asymptomatic neonate with hydronephrosis or hydroureteronephrosis. A report from combined meetings of The Society for Fetal Urology and members of The Pediatric Nuclear Medicine Council – The Society of Nuclear Medicine.J Nucl Med 1992; 33 : 2047–51

EANM

SNM

ISCORN

- recommends a physiologic procedure- evaluation of drainage takes into account renal function, and contemplates urinary excretion including gravity and micturation

- recommends a more invasive technique- evaluation of drainage does not account for influence of gravity, renal function, pelvis size.

Gordon I, Colarinha P, Fettich J et al.Guidelines for standard and diuretic renography in children.Eur J Nucl Med 2001; 28 : BP21–BP30

Conway JJ, Maizels M.The ‘well tempered’ diuretic renogram: a standard method to examine the asymptomatic neonate with hydronephrosis or hydroureteronephrosis. A report from combined meetings of The Society for Fetal Urology and members of The Pediatric Nuclear Medicine Council – The Society of Nuclear Medicine.J Nucl Med 1992; 33 : 2047–51

Guidelines for standard and diuretic renography in children

Paediatric Committee of European Association of Nuclear Medicine

Eur J Nucl Med 2001; 28:BP21-BP30

MAG-3 diuresis renography has been shown to be useful even in children

aged 1 month or less and this technique should be available to them


Age of the child

� Routine use of bladder catheter is not indicated.� Most children will void spontaneously, especially as a diuretic has been given.

� Recommend the acquisition of a post-micturition image obtained after gravity assisted drainage.


Bladder catheterization

RENOGRAM F0

post.mict.post-gravity

Encourage oral fluid intake for adequate hydration rather than intravenous fluid administration


Hydration of the child

� F+20, F-15, F0: No evidence of any one of these timings being better than the others.

� If venous access is difficult, a single injection is recommended (F0).

Guidelines for standard and diuretic renography in childrenTime of diuretic administration

� Renal function

� Drainage assessment


Parameters used

Preparation

Offer water / orange juice.

No bladder catheterization, only if:

Previous hydrationNeonates: start acquisition just afterroutine lactation.

Pelvic ectopic kidney.Vesico-uretheral reflux present +++

Gravity effect

Previous micturation whenever possible.

Vertical position just before post-micturing image.

IV fluids only if necessary.

DiureticVariable timing.

IMMOBILIZATIONsand bags, Velcro strips

HYDRATION

POST-MICTURING IMAGEGRAVITYDIURETIC

• F+15 F+20 F+30Inject diuretic when maximum activity is detected in dilated

structures just above the stenosis.

0 min 10 min 20 min 30 min 40 min

Advantages:1. Interactive renogram2. Optimal functional information

MAG3 Diuretic

FUROSEMIDE: 0.5-1 mg/kg

FUROSEMIDE: 0.5-1 mg/kg• F-15 or F0

0 min 5 min 10 min 15 min 20 min

MAG3

diurético

Advantages:1. No need to maintain IV line2. Shorter camera time

Catheter only necessary if:

• VUR +++++

• Ectopic kidney

Post-micturing image

Bladder catheter: • Post-micturing image AVOIDS the use of catheter.


IN CHILDREN




COMPARISON:� IMAGES� CURVES

INTERPRETATION- Images- Curves- Quantitative parameters

Renogram classificationDEGREE OF UPTAKE: % DRF Ransley et al (1990) classified patients according

to % of differential renal function (DFR):

EXCRETION PATTERNO’ Reilly et al (1979) classified patients according to diuretic response: Response I : Normal initial renography with no change after diuretic. Response II : Obstructive initial renography with no change after diuretic. Response IIIa: Obstructive initial renography with rapid clearance

after diuretic. Response IIIb: Obstructive initial renography with mild/partial clearance after

diuretic.

Poor uptake :< 20% Moderate uptake : 20-39%Good uptake : > 40%

Diur

Parenchymalimpairment

Drainage impairment

RENOGRAM3 phases

Phase 1:• Initial seconds• Fast ↑ activity• Injection

= renal perfusion

Phase 2:• 2–3 min post injection• Tracer accumulates in

kidney• no excretion

= renal uptake

Phase 3:• Tracer starts clearing

= renal drainage


= renal perfusion



= renal uptake


= renal drainage

RENOGRAM3 phases


= renal perfusion



= renal uptake


= renal drainage

RENOGRAM3 phases

• increment of renal activity ≈ differential renal function DRF• curve upslope• integral counts under the curve

• DRF should be calculated for the initial 2 minutes.Late calculation of DRF:• normal kidney: underestimation of relative function because part of the tracer is already leaving the kidney.• Hydronefrosis: overestimation of relative function because of delay in clearance.

PITFALL



= renal uptake

• not representative of DRF.• does not indicate start of excretion.

Tmax

PITFALL

Tmax = curve peak • equilibrium between uptake and excretion.



= renal uptake

Options for Phase 3 are: • decreasing activity:

• preserved drainage• flat curve: equilibrium

• amount cleared tracer = amount excreted tracer• increasing activity: ectasia and urinary tract dilatation

• without obstruction• with obstruction


= renal drainage

Diuretic enhancement:Furosemide: increases glomerular filtration.• wash-out if no obstruction present• retention if partial obstruction exists


= renal drainage

INTERPRETATION- Images- Curves- Quantitative parameters

YES

NO

NORMALFUNCTION DECREASED

FOCAL LESIONSDRF

RENAL EXCRETION• after diuretic• after micturation• after gravity

DRAINAGEEXCRETION

Interpretation of diuretic renogram in children:problems and pitfalls

ESKILD-JENSEN, GORDON, PIEPSZ, FRØKIÆRBJU 2004; 94,887–892

DRF is independent of• degree of hydronephrosis• hydration status• bladder emptiness• gravity• diuretic administration

DRF – Differential Renal Function

1. LOW signal / background (BKG)• Renal insufficiency.• DTPA instead of MAG3 in young children.

2. Inappropriate BKG ROI• DFR influenced by extra-renal interstitial

activity included in BKG ROI.• Consensus regarding BKG subtraction ROI:

peri-renal area.• Problem: severe dilatation and very young

patients (renal contour similar to body contour). In this case, draw BKG ROI below kidney.

3. Technical errors• Injection problems.• Poor labelling (MAG3: liver, stomach).• Patient motion.• Wrong timing initiation of acquisition.

PITFALLSWRONG

ESTIMATIONOF RENAL FUNCTION

DFR

Renal curves corrected by extra-renal BKG activity

DRF calculation2 widely accepted algorithms:

• integral method = DRF-int•Rutland-Patlak method = DRF-RP

Recommendation• use both methods• if similar results, quality control is OK +++


F-15 / F0DRF calculation – integral methodIf diuretic is given before (15 min) or simultaneously:

• there is increased renal transit time• risk of underestimation of DRF

SolutionCompare:

• Tmax (renogram peak) • with interval used to calculate DRF (usually 1-2’)

If Tmax <2 min, change to lower interval (30-90”)


Normal range: 45–55%• It is a relative measure of renal function.• DRF may reflect changes due to contralateral kidney:

� contralateral kidney damage � compensatory function of contralateral kidney

Estimation of absolute renal function – GFR• Gamma-camera method:

� unaccurate� great variations, especially in young children� no consensus

• Plasma sampling method:� 99mTc-DTPA or 51Cr-EDTA � more accurate


Supra-normal function > 55%• Technical error?• Hiperperfusion / hiperfiltration of “obstructed” kidney?• Relative to increased renal size?

(DRF-integral detects greater values in larger kidneys)• More frequent in younger children• 11 % with DRF-integral method• 8 % with DRF-RP method• only 5 % if FRD-integral and FRD-RP are coincident

• To obtain a robust measure of DRF in youngsters:� quality control (motion, injection, etc.)� correct BKG subtraction (ROI)

Robustness of estimation of differential renal function in infants and children with unilateral prenatal diagnosis of a hydronephrotic kidney on dynamic renography. How real is the supranormal kidney?

Gordon, I. EJNM, in pressContradictory Supranormal Function in Hydronephrotic

Kidneys: Fact or Artifact on Pediatric MAG-3 Renal Scans?Clin Nucl Med 2005; 30:91-96

PREDICTION OF RENAL FUNCTION DETERIORATION

Partial obstruction:• affects nephrogenesis• may cause hyperfiltration

Experimental HydronephrosisObstructed kidney increases glomerular filtration

(GF) between weeks 4 and 12 post- partial renal obstruction

Frokiaer, J

If mentioned mistakes are avoided, DRF is: • A robust method to measure relative renal function.• Accurate: < 5 % inter-observer variability. • A decrease >5-10 % means deterioration.

PITFALLS• ROIs: similar renal and body contours.• Time interval for DRF calculation.

� 30-90 sec F0� 1– 3 min F+15

• MAG3 and dosis: adequate signal-BKG ratio.


Based on residual activity• ROE = renal output efficiency• PEE = pelvic excretion efficiency • NORA20=normalized residual activity

METHODS FOR QUANTIFICATION OF

EXCRETION

• F-15• F0

� after diuretic� after micturition

Based on the curve response post-furosemide• % drainage 5-10 min• T1/2 post-diuretic • F15

• F20

Validation of renal output efficiency as an objective quantitative parameter in the evaluation of upper urinary tract obstruction.

Chaiwatanarat, Padhy, Bomanji, Nimmon, Sonmezoglu, Britton. J Nucl Med. 1993, 34: 845-8

NORA: A simple and reliable parameter for estimating renal output with or without furosemide challenge Piepsz, Tondeur, Ham. Nucl Med Commun 2000; 21: 317–23

Assessment of drainage in PUJ dilatation: Pelvic Excretion efficiency as an index of renal function Anderson, Rangarjan, Gordon. Nucl Med. Commun 1997, 18: 823-826

• after diuretic• after micturation• after gravity

MicturationEqual or more important than diuretic administration

Pitfall:Renogram commenced with full bladder can simulate BILATERAL FUNCTIONALOBSTRUCTIVE PATTERN

Gravity Important for drainage of

whole urinary tract

POST-MICTURATION

NO change in renal retentionPOST-GRAVITY

LESS renal retention

MORE renal retention

PITFALLS Causes affecting RENAL EXCRETION results:• Full bladder• Inappropriate hydration• No post-gravity imaging• Immature renal function (newborns) or renal insufficiency• Large volume of excretory structures (renal pelvis)• Increased compliance of excretory structures

LOW EXCRETION

RENAL PELVIS VOLUME DURING DIURESIS IN CHILDREN WITH HYDRONEPHROSIS: IMPLICATIONS FOR DIAGNOSING OBSTRUCTION WITH DIURETIC RENOGRAPHY

Koff. J Urol 2005 174, 303–307,


EXCRETION


Furosemidevolume

pressure

• LARGE CAVITIESSevere dilated structures

• INCREASED COMPLIANCEStructures with great capacity to dilate

F

Pelvic volume: 1

Pelvic volume: 4

F

T 1/2 after diuretic:• not useful as obstructive parameter• renal pelvis dilates after diuretic • tracer dilutes in renal pelvis• Koff:

� found increased T1/2 post-diuretic in 40% of patients � but there was no obstruction� more frequent in <2 years old � more frequent in children with large volume of renal pelvis

Impaired drainage on diuretic renography using half-time or pelvic excretion efficiency is not a sign of obstruction in children with a prenatal diagnosis of unilateral renal pelvic dilatation

Amarante, Anderson, GordonJ Urol, 169, 1828–1831, 2003

Renal pelvis volume during diuresis in children with hydronephrosisimplications for diagnosing obstruction with diuretic renography

Koff, Binkovitz, Voley, JayanthiJ urol, 174, 303–307, july 2005

Drainage can be best quantified using tools to measure RESIDUAL ACTIVIDAD:• ROE : renal output efficiency• PEE : pelvic excretion efficiency• NORA : normalized residual activity


EXCRETION


Drainage can be best quantified using tools to measure RESIDUAL ACTIVIDAD:• ROE : renal output efficiency• PEE : pelvic excretion efficiency• NORA : normalized residual activity

Especially if diuretic administration time: • F-15• F0

These parameters take into account RENAL FUNCTION


EXCRETION


Catheter only necessary if:

• VUR +++++

• Ectopic kidney

Post-micturing image

Low renal function in neonatal period

Increased parenchymal transit timeLower diuretic effectLow amplitude of the renogram

renography can be done from birthadvisable > 4 weeksMAG3: non toxic for kidney

very low dosimetry





IN CHILDREN

• Drainage can vary with physiologic conditions• Drainage spontaneously improves with time• Surgery improves drainage• Good drainage = good prognosis• Impaired drainage = possible obstruction

Congenital unilateral hydronephrosis: a review of the impact of diuretic renography on clinical treatment

ESKILD-JENSEN, GORDON, PIEPSZ, FRØKIÆRJ Urol 173, 1471–1476, 2005

Indications for SURGERY• Progressive hydronephrosis• Absent or poor diuretic response• Deterioration of renal function• Infection

• Renal function� DRF: normal, ↑ ↓� Cortical optimized image

- diffuse decreased uptake- focal cortical lesions

• Renal size: normal , ↑ ↓• Curves• Transit time• Dynamic images: urunary tract

� dilated� non dilated

• Drainage: diuretic, micturation, gravity� OER� PEE� NORA� PMI

INTE

RPRE

TATI

ON

CRIT

ERIA

Drainage ↑ or =

↑ Pelvic pressure↓ Bladder pressure

• Drainage� diuretic� gravity� bladder emptying

• Quantification� OER� PEE� NORA� PMI

• Renal function� DRF-auc� DRF-decon� cortical image

«"O

BSTR

UCTI

VE P

ATTE

RN»

low / decreased

low / decreased

Frequently, diuretic renography is performed without considering:

• previous hydration• renal function• renal pelvis size• gravity• bladder emptying

PITFALLS

Technical errors should also be considered:

• radiopharmaceutical labelling• injection technique• patient motion• diuretic injection• urine contamination• ROI delineation

Conclusion:IF DIURETIC RENOGRAPHY IS WELL STANDARDIZEDAND POTENTIAL PITFALLS CONSIDERED, IT IS A VALUABLE AND REPRODUCIBLE METHOD TO OBTAIN INFORMATION ON DRF AND RENAL DRAINAGE

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