Imaging With a Purpose:

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Imaging With a Purpose:

Imaging With a Purpose:

Answering the Clinical Questions in

Adult and Pediatric Renal Scintigraphy

Dr. Shane B. Anderson

Nuclear Medicine Service

Brooke Army Medical Center

San Antonio, TX


Learning Objectives

1. Diuretic renography

2. ACE inhibitor renography

3. Pediatric renography

Renal cortical scintigraphy

Radionuclide cystography

4. Transplant renography

5. Quantitative evaluation


Radiopharmaceuticals

99mTc DTPA

• 5-10% bound to plasma proteins

• 20% extraction (with each pass)

• 90% filtered by 4 hours

• Inexpensive

• Brief nephrogram phase

• 10-20mCi


Radiopharmaceuticals

I-131 OIH replaced by 99mTc-MAG3

• 95% proximal tubules


Functional Renal Imaging

Renography

• Vascular transit phase

• Initial arrival of RP, lasts 30-60 seconds

• Cortical or tubular concentration phase

• Peak of curve, minutes 1-5

• Parenchymal transit

• Closely correlates with ERPF

• Clearance or excretion phase

• Downslope of curve, excretion of RP


Renogram

80000

frame

70000

60000

50000

Excretion

nts per

Cou

40000

30000

20000

Concentration

T1/2

10000

Vascular

0

0 5 10 15 20 25

Time in minutes


Functional Renal Imaging

• Time to peak activity = 3-5 minutes

• Differential Function ideally = 50% each

• Hlfi

Half-time excretion = 8-12 minutes

• 20-minute-to-peak count ratio = < 0.3 (30%)

Mettler et al. Essentials of Nuclear

Medicine Imaging. 5th Edition.


Dynamic images


NORMAL STUDY


CONTRAST

INDUCED

NEPHROPATHY


CONTRAST

INDUCED

NEPHROPATHY


CONTRAST INDUCED NEPHROPATHY


Diuretic Renography

Underlying Pi Principle:

i A fixed anatomic obstruction would not be expected to be

overcome by diuresis


Diuretic Renography

• Nonobstructive hydronephrosis

• Reflux, chronic infection, congenital

• These may fill, but not open UPJ

• Given Lasix, the functional obstruction “opens”


Diuretic Renography

• Collecting system usually full by 15 minutes

• Best to give diuretic when renogram is near peak

• Lasix

• Adults 40mg

• Children 1mg/kg

• Response in 2-3 minutes

• Maximal diuresis at 15 minutes

• Calculate T1/2 from time of injection


Diuretic Renography

Post Lasix Half-time Excretion

• = < 10 minutes is NORMAL

• =>20 minutes is OBSTRUCTED

• > 10 but < 20 is INDETERMINATE

N • 11-1515 min is favored by most as non-obstructed obstructed vs low-

grade obstruction of no clinical significance


Dynamic images


PRE-LASIX


POST-LASIX


F+20 vs F0 Methods

• Furosemide at 20 minutes

• Traditional method

• Evaluates for obstruction and diuresis response

• Furosemide at time 0

• Injected at same time as radiopharmaceutical

• Study found similar outcome regardless of timing

• Sfakianakis et al recommend F0 method

Sfakianakis GN et al: A renal protocol for all indications: MAG3 with simultaneous injection of furosemide (MAG3-F0): a

fifteen year experience. J Nucl Med. 2007:48(suppl 2): 125P.


S/P ureteral implant


Dynamic images


Diuretic Renography

Post Lasix Half-time Excretion

• = < 10 minutes is NORMAL

• =>20 minutes is OBSTRUCTED

• > 10 but < 20 is INDETERMINATE

N • 11-1515 min is favored by most as non-obstructed obstructed vs low-

grade obstruction of no clinical significance


Dynamic images


ACE Inhibitor Renography

• Renovascular hypertension

• 1-4% of all cases of hypertension

• Most common cause is atherosclerosis (elderly ♂)

• 2 nd most common is fibromuscular dysplasia (♀


ACE Inhibitor Renography

• Selection criteria

Not to be used for screening

• > 60 or < 20

• Severe or accelerated HTN

• HTN that was previously well controlled

• Other evidence of vascular disease

• Unexplained renal dysfunction in setting of HTN

• Abdominal bruit


ACE Inhibitor Renography

• DTPA

• Principle finding is ↓ uptake and excretion

• Usually unilateral

• MAG3

• Adequate uptake and excretion

• ↓ washout from collecting tubules

• This results in increased cortical retention


ACE Inhibitor Renography

• Criteria to indicate abnormal MAG3 study

• 2-3 minute differential < 40%

• Asymmetric retained cortical activity at 20 minutes

• >20% difference from contralateral kidney

• Increase from baseline of 0.15

• Normal is 0.3

• Delayed time to peak in affected kidney y( (>2 min)


ACE Inhibitor Renography

• Sensitivity and specificity > 90%

• Best with RAS of 60-90%

• Use caution with:

• Renal insufficiency

• Bilateral RAS

• Solitary or stenotic kidney

• Transplant kidney’s


Anatomic Imaging

• DMSA (or glucoheptonate)

• Space occupying lesion

• Functioning pseudotumors (columns of Bertin)

• Edema

• Scar


Renal Masses

• DMSA or glucoheptonate

• Neoplasms

• Abcess

• Cysts

• Hematoma

• Infarct

• Psuedotumors

• Fetal lobulation, dromedary humps, columns of Bertin


Radionuclide Cystography

• More sensitive than contrast cystography

• Detects as low as 1mL of reflux

• Much hl less radiation i

exposure

• 0.5-1 mCi Pertechnetate, DTPA, or sulfur colloid


Radionuclide Cystography

• Minimal

• Confined to ureter

• Moderate

• Pelvicalyceal system

• Severe

• Into the pelvicalyceal system with dilated intrarenal

collecting system or dilated tortuous ureter


Renal Transplant Evaluation

Differentiate rejection from ATN

• Rejection

• Poor rp perfusion and dp poor rt tubular excretion

• ATN

• Usually within first week

• Preserved perfusion

• Can look like cyclosporin toxicity


Quantitation

• Plasma sample-based clearance

• Plasma and urine samples

• 45 min after injection, MAG3 → ERPF

• 1-2 hrs after injection, DTPA → GFR

• Camera-based clearance

• Not as accurate, but highly reproduceable

• Mathematical calculations


Sources

• Boubaker A, Prior JO, Meuwly JY, Bischof

Delaloye A. Radionuclide investigations of the

urinary tract in the era of multimodality imaging.

JNM 2006;47:1819-1836. 1836.

• Mettler et al. Essentials of Nuclear Medicine

Imaging. 5th Edition.

• Thrall JH and Ziessman HA. Nuclear Medicine:

i

The Requisites. 3rd Edition.

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