tumor imaging
TRANSCRIPT
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
F+O Protocol (Lasix administered at time of radiotracer)
FLOW PHASE
AORTA FIRST VISIBLE
RENAL FLOW APPEARS W/IN 2 sec
F+O Protocol (Lasix administered at time of radiotracer)
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
F+O Protocol Lasix administered at time of radiotracer
T = 1-20min
Post Void Image
F+O Protocol Lasix administered at time of radiotracer
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
46 yo M with Retroperitoneal Fibrosis
T-1/2 >> 20 min
46 yo M with Retroperitoneal Fibrosis
T-1/2 >> 20 min
46 yo M with Retroperitoneal Fibrosis
T = 2 min T = 5 min
POST VOID
ABNORMAL COLLECTING SYSTEM RETENTION
46 yo M with Retroperitoneal Fibrosis
KIDNEYS SHOW NORMAL TISSUE TRANSIT / CORTICAL FUNCTION
46 yo M with Retroperitoneal Fibrosis
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
Courtesy of Dr. Patrick Colletti Director Nuclear Nuclear Fellowship University of Southern California
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
Radionuclide Cystography
§ 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
3 yo female with UTI
POST VOID
LEFT MILD VUR
3 yo female with UTI
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
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
Radionuclide Cystography
• 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