Tumor Imaging

Kevin P Banks, MD Department Radiology San Antonio Military Health System & Health Education Consortium Assistant Professor of Radiology & Nuclear Medicine Uniformed Services University of Health Sciences

RENAL SCINTIGRAPHY

I HAVE NO DISCLOSURES.

Learning Objectives

ú Review common types of renal scintigraphic exams and their clinical applications Review components of dynamic renography exam

interpretation & normal versus abnormal values Discuss pitfalls in diuretic renography that can

cause false positive results Review use & interpretation of renal anatomic

scintigraphy Discuss radionuclide cystography technique and

diagnosis of vesicoureteral reflux

GU OBSTRUCTION

IMAGING

Indication for Diuretic Renal Scintigraphy

§ Differentiate obstructive vs Non-obstuctive hydronephrosis

Obstructive Hydronephrosis

§Congenital stenosis §Stricture §Lithiasis §Tumor

Non-Obstructive Hydronephrosis Congenital dilation Vesicoureteral reflux (VUR) Urinary tract infection (UTI) Non-compliant bladder Prior obstruction

Principles of Diuretic Renography

ÄPhysiologic Conditions: Urine (radiotracer) pools in dilated collecting system either due to reservoir effect or obstruction of outflow

ÄFurosemide (Lasix): Induces increased urine flow ú Dilated non-obstructed system à diuresis

produces rapid washout of activity ú Obstructed system à fixed narrowing prevents

significant increased flow and thus prolongs retention of tracer

Protocol/Procedure

q 10 mCi of Tc-99m MAG3 (peds: 100-150 uCi/kg, min 1.0 mCi) [1]

q 40 mg IV Lasix (peds: 1 mg/kg)

q Supine imaging with camera posterior

q Image for 20-30 min following injections of radiotracer & diuretic

q Post-void image

[1] Gelfand MJ, Parisi MT, and Treves ST. Pediatric Radiopharmaceutical Administered Doses: 2010 North American Consensus Guidelines. JNM 2010;52(2):318-322

SNM Procedure Guidelines [2]

3 different approaches for time of injection of diuretic furosemide (F) in relation to injection of radiopharmaceutical (Tc-99m MAG3 ):

å 20 min after radiopharmaceutical (F+20) ù or later when dilated system is filled

ç 15 min before the injection of radiopharmaceutical (F-15)

é Simultaneous injection of Tc-99m MAG3 & diuretic (F+0) [3,4]

Protocol/Procedure

[2] Shulkin BL, Mandell GA, Cooper JA. Procedure guideline for diuretic renography in children 3.0. JNMT 2008;36(3):162-168 [3] 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. [4] Turkolmez S, Atasever T, Turkolmez K, Gogus O. Comparison of three different diuretic renal scintigraphy protocols in patients with dilated upper urinary tracts. Clin Nucl Med 2004:29(3):154-160.

SFU

Interpretation

§ Flow = prompt & symmetric

§ Differential Function = 45-55% each § Time to peak activity = 3-5 minutes

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

§ Half-time excretion = < 10 minutes is NORMAL

40 yo F with Hx of Kidney Stones and R Hydronephorsis

F+O Protocol (Lasix administered at time of radiotracer)

FLOW PHASE

NORMAL RENAL FLOW • RENAL FLOW IS PROMPT à1-3 SEC AFTER AORTA • RENAL FLOW IS SYMMETRIC

• GOOD TIGHT BOLUS


FLOW PHASE

AORTA FIRST VISIBLE

RENAL FLOW APPEARS W/IN 2 sec


NORMAL RENAL FUNCTION • PEAK PARENCHYMAL ACTIVITY <3-5 MIN • TIME TO PEAK AND INTENSITY ARE SYMMETRIC

• <=30% RETENTION 20 MIN AFTER PEAK NORMAL RENAL EXCRETION • 50% COLLECTING SYSTEM ACTIVITY GONE BY 10 MIN AFTER COLLECTING SYSTEM PEAK

FUNCTION & EXCRETION

PHASES

F+O Protocol (Lasix administered at time of radiotracer) F

UNCTION & EXCRETION

PHASES

COLLECTING SYSTEM ACTIVITY APPEARS

RENOGRAM

5 MIN 10 MIN 15 MIN 20 MIN

COUNTS

VASCULAR PHASE ~ 30-60 s

FUNCTIONAL PHASE ~ 1-5 m

EXCRETION PHASE

RENOGRAM

T ½ EXCRETION < 10 m DIFFERENTIAL

FUNCTION 2-3 m 45–55 %

T Peak < 3-5 m

25 MIN

T Peak-to-20min < = 30 %

RENOGRAM

RENOGRAM

RENOGRAM

RENOGRAM

1 Month Later...

F+20 Protocol Lasix administered after initial imaging

50 yo M s/p Pyeloplasty (No Prior Imaging)

Pre-lasix

T = 1-20min

Post-lasix

T = 21-40min

PRE-LASIX

POST-LASIX

Interpretation

§ Flow = prompt & symmetric

§ Differential Function = 45-55% each § Time to peak activity = 3-5 minutes

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

§ Half-time excretion = < 10 minutes is NORMAL

Classic Interpretation

§ Half-time excretion = < 10 minutes is NORMAL § Half-time excretion >10 minutes but <20 minutes is INDETERMINATE

§ Half-time excretion > 20 minutes is OBSTRUCTED

15-20%

Interpretation

§ Half-time excretion > 10 minutes is DELAYED § Half-time excretion >10 minutes but <15 ú Unlikely clinically significant difference from patients

with T-1/2 =< 10 minutes

§ Half-time excretion > 15 minutes but < 20 ú Likely unobstructed, but evaluated the same as cases

with T-1/2 > = 20 minutes

Interpretation

§ Half-time excretion > 20 minutes is ABNORMAL Starting point for diagnosing OBSTRUCTION èLook at shape of curve èLook at post void collecting system activity èEvaluate cortical clearance (aka tissue transit time)

Interpretation

§ Look at shape of curve èINCREASING or PLATEAU ✓ OBSTRUCTED

F = 0

Time Activity Curve

24 min

26 yo M with s/p Ureteral Implant

F+O Protocol Lasix administered at time of radiotracer

T = 1-20min

Post Void Image

Interpretation

§ Look at shape of curve èINCREASING or PLATEAU ✓ OBSTRUCTED

F = 0

Time Activity Curve

24 min

Interpretation

§ Look at shape of curve èDECREASES < 50% ✓ QUESTIONABLE

F = 0

Time Activity Curve

20 min

50 % 50 %

Interpretation

§ Half-time excretion > 20 minutes is ABNORMAL Starting point for diagnosing OBSTRUCTION èLook at shape of curve èLook at post void collecting system activity èEvaluate cortical clearance (aka tissue transit time)

Sfiakianakis GN, et al. A Renal Protocol for All Ages and All Indications: MAG3 with Simultaneous Injection of Furosemide: A 17-year Experience. Semin Nuc Med 2009.

50 yo F with Hx of Colorectal Cancer and New R Pelvicaliectasis


T = 1-20min

Post Void Image


T = 1-20min

RIGHT KIDNEY SHOWS NORMAL TISSUE TRANSIT / CORTICAL FUNCTION

DELAYED COLLECTING SYSTEM EMPTYING WITHOUT PARENCHYMAL DYSFUNCTION

46 yo M with Retroperitoneal Fibrosis

T = 2 min T = 5 min T = 20 min


T-1/2 >> 20 min


T-1/2 >> 20 min


T = 2 min T = 5 min

POST VOID

ABNORMAL COLLECTING SYSTEM RETENTION


KIDNEYS SHOW NORMAL TISSUE TRANSIT / CORTICAL FUNCTION


KIDNEYS SHOW NORMAL TISSUE TRANSIT / CORTICAL FUNCTION

DELAYED COLLECTING SYSTEM EMPTYING WITHOUT PARENCHYMAL DYSFUNCTION

6 yo M with R Duplicated CS

POST VOID

R UPPER R LOWER

Diuretic Renography

Pitfalls

ú Poor renal function → Diminished diuretic response

ú Poor hydration → Poor diuretic response

ú Over-compliant renal pelvis → Reservoir effect – very large hydronephrotic volume

ú Difficulty voiding → Backpressure blunts diuretic response

61 yo M with L Hydroureter

Post Void Image

Diuretic Renography § Pitfalls

ú Poor renal function Need to be able to excrete adequate

radiotracer and respond to diuretic GFR should be > 15 mL/min

Considered increased dose of Lasix (80-150mg) for low GFR or patients chronically on Lasix

ú Poor hydration Hold diuretics on day of exam Oral hydration 750-1000cc 30 min prior

51 yo F with Ovarian Cancer and Mild Bilateral Hydronephrosis

T=1 min

T=10 min

T=20 min

Diuretic Renography

§ Pitfalls

ú Noncompliant bladder → Backpressure blunts diuretic response Have patients void before start of study Recommend use of Foley catheter for

patients with difficultly voiding (neurogenic bladder, low-bladder capacity, +/- young children)

Courtesy of Dr. Patrick Colletti Director Nuclear Nuclear Fellowship University of Southern California



LEFT VUR

GU INFECTION AND REFLUX

AAP and AAFP

“Bottom-up” approach

only 61% adherence

Lim R. Vesicoureteral Reflux and Urinary Tract Infection: Evolving Practices and Current Controversies in Pediatric Imaging. AJR 2009;192:1197-1208

European Society of Pediatric Radiology

“Top-down” approach

DMSA emphasis

Lim R. Vesicoureteral Reflux and Urinary Tract Infection: Evolving Practices and Current Controversies in Pediatric Imaging. AJR 2009;192:1197-1208

Anatomic Imaging

DMSA (or glucoheptonate) ú Edema/Inflammation ú Scar ú Space occupying lesions ú Functioning pseudotumors (columns of

Bertin) ú Horseshoe kidney

MUCH MORE SENSITIVE THAN US FOR PYELONEPHRITIS AND SCARRING

Protocol/Procedure

q 50 uCi/kg of Tc-99m DMSA (min 300 uCi) [5]

q Supine imaging with camera posterior

q Images acquired 2-hr after injection

q Planar parallel posterior and posterior oblique high-resolution images

q SPECT and pin-hole more sensitive, but role not definitively defined

[5] Mandell GA, et. Procedure guideline for renal cortical scintigraphy in children 3.0 in SNM Procedure Guideline Manual

Acute Pyelonephritis

Three common patterns:

ú Focal cortical defects

ú Multifocal cortical defects

ú Diffusely decreased activity

INDISTINGUISHABLE FROM SCARRING

4 yo F with UTI

POSTERIOR STATICS

CORONAL SPECT

FOCAL CORTICAL DEFECT

4 yo F with VUR and UTI

POSTERIOR STATICS CORONAL SPECT

MULTIFOCAL CORTICAL DEFECTS

8 yo F with VUR and recurrent UTIs

DIFFUSE DECREASED ACTIVITY

8 yo F with VUR and recurrent UTIs

8 yo F with horseshoe kidney, recurrent UTIs, and HTN

NO ACTIVITY BETWEEN KIDNEYS à FIBROUS ISTHMUS

Vesicoureteral Reflux Imaging

RADIONUCLIDE CYSTOGRAPHY (RNC) §More sensitive than contrast cystography ú Detects as low as 1mL of reflux

§Much less gonadal radiation exposure ú 0.5-1 mCi pertechnetate, DTPA, or sulfur colloid ú 1/10th fluoroscopy

BUT… §No international standard for grading §Poor anatomic detail

Radionuclide Cystography

RNC versus VCUG?

§ VCUG as the initial test ú Severity of VUR ú Anatomic abnormalities

§ RNC for follow up ú Document resolution ú After surgery ú Screening siblings


§ Minimal ú Reflux confined to ureter

§ Moderate ú Pelvicalyceal system

§ Severe ú Into the pelvicalyceal system with dilated

intrarenal collecting system and/or dilated tortuous ureter

3 yo female with UTI

POST VOID

START

VOIDING STARTS


POST VOID

LEFT MILD VUR


LEFT MODERATE VUR

**PATIENT MOTION DURING EXAM**

VUR APPEARS AS PATIENT BEGINS TO VOID - - POINT OF MAX INTRAVESICULAR PRESSURE

2 yo female with h/o UTI & dysfunctional voiding

START

VOIDING STARTS

2 yo female with h/o UTI & dysfunctional voiding

BILATERAL MODERATE VUR

4 yo female with h/o VUR

RIGHT SEVERE

VUR

4 yo female with h/o VUR

NEGATIVE VCUG

[email protected]

REVIEW

Diuretic Renography

• Differentiates dilated (patulous) non-obstructed system from true obstruction • F-15 vs F+0 vs F+20 generally equivalent • T1/2 excretion <=10 min normal >20 min abnormal • FP include: à poor renal function à severely dilated collecting system à dehydration à back-pressure effect in setting of difficulty voiding

REVIEW

Cortical Scintigraphy

• More sensitive than US for pyelonephritis • Solitary or multiple defects versus diffuse decreased activity • Cannot reliably differentiate acute pyelonephritis versus scar by imaging features • Pin-hole and SPECT more sensitive than planar, but significance of findings not seen on planar is questionable

REVIEW


• More sensitive than VCUG • Less gonadal radiation than VCUG • Poor anatomic detail • No standardize international grading

• Mild = reflux to ureter • Moderate = reflux to renal pelvis • Severe = reflux to pelvis with pelvic/ureteral tortuosity

• Likely ideal for follow-up/post-intervention & screening siblings

THANK YOU

[email protected]

Documents

Tumor Imaging