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CT CT UrographyUrographyStuart G. Silverman, M.D.Stuart G. Silverman, M.D.
Professor of RadiologyProfessor of RadiologyHarvard Medical SchoolHarvard Medical School
Director, Abdominal Imaging Director, Abdominal Imaging and Interventionand Intervention
Brigham and WomenBrigham and Women’’s s HospitalHospital
Boston, MABoston, MAUreter
CT CT UrographyUrographyStuart G. Silverman, M.D.Stuart G. Silverman, M.D.
Disclosure of financial Disclosure of financial relationship with relevant relationship with relevant commercial interestcommercial interestSiemens Medical SolutionsSiemens Medical SolutionsMalverneMalverne , PA , PA –– Consultant Consultant
Ureter
OutlineOutline•• CT CT urographyurography techniquetechnique•• UreterUreter variantsvariants•• UreterUreter: benign : benign vsvs malignantmalignant•• Dual energy applied to Dual energy applied to ureterureter•• SummarySummary
BWH CTU ProtocolsBWH CTU Protocols
•• Three phase Three phase –– UP (abdomen and pelvis), NP UP (abdomen and pelvis), NP (kidneys only), EP (abdomen and pelvis), (kidneys only), EP (abdomen and pelvis), supplemented with 10 mg supplemented with 10 mg furosemidefurosemide IVIV
Patients > 40 years oldPatients > 40 years old
•• Split bolus, two phase Split bolus, two phase –– abdomen and abdomen and pelvis, supplemented with 250 cc saline IVpelvis, supplemented with 250 cc saline IV
Patients Patients << 40 years old40 years old
10 mg 10 mg IV Furosemide 22--33”” CM (100cc)
UnenhancedUnenhanced NephrographicNephrographic ExcretoryExcretoryRangeRange Abd/PelAbd/Pel KidneysKidneys Abd/PelAbd/PelDelay Delay ---- 100 s 100 s 10 10 -- 15 min15 minCollimation Collimation 1.2 mm 1.2 mm 1.2 mm 1.2 mm 0.6 mm0.6 mmAxial Recon/Axial Recon/IncrIncr 3/3 3/1.5 3/3 3/1.5 3/33/3Post Processing Post Processing ---- ---- CorCor / Sag / MIP / CPR / VR/ Sag / MIP / CPR / VR
Iodinated contrast material (300 Iodinated contrast material (300 mgImgI/ml); 0.5 s rotation time/ml); 0.5 s rotation timeAEC w/ quality reference 200 AEC w/ quality reference 200 mAsmAs, 120 , 120 kVpkVp
BWH CT Urography Protocol64 64 –– ChannelChannel MDCT with 3 phasesMDCT with 3 phases
Silverman et al Radiology 2006Silverman et al Radiology 2006
10 mg 10 mg IV Furosemide 22--33”” CM (80cc)
UnenhancedUnenhanced NephrographicNephrographic ExcretoryExcretoryRangeRange Abd/PelAbd/Pel KidneysKidneys Abd/PelAbd/PelDelay Delay ---- 100 s 100 s 10 10 -- 15 min15 minCollimation Collimation 1.2 mm 1.2 mm 1.2 mm 1.2 mm 0.6 mm0.6 mmAxial Recon/Axial Recon/IncrIncr 3/3 3/1.5 3/3 3/1.5 3/33/3Post Processing Post Processing ---- ---- CorCor / Sag / MIP / CPR / VR/ Sag / MIP / CPR / VR
Iodinated contrast material (Iodinated contrast material (370370 mgImgI/ml); 0.5 s rotation time/ml); 0.5 s rotation timeAEC w/ quality reference 200 AEC w/ quality reference 200 mAsmAs, 120 , 120 kVpkVp
BWH CT Urography Protocol64 64 –– ChannelChannel MDCT with 3 phasesMDCT with 3 phases
Silverman et al Radiology 2006Silverman et al Radiology 2006
•• FurosemideFurosemide allergyallergy•• Sulfa allergySulfa allergy•• SBP < 90 SBP < 90 torrtorr
IV IV FurosemideFurosemide WithheldWithheld
IV Saline is suitable alternativeIV Saline is suitable alternative
CM (80cc) IV Saline(250 IV Saline(250 ccsccs))
UnenhancedUnenhanced NephrographicNephrographic ExcretoryExcretoryRangeRange Abd/PelAbd/Pel KidneysKidneys Abd/PelAbd/PelDelay Delay ---- 100 s 100 s 10 10 -- 15 min15 minCollimation Collimation 1.2 mm 1.2 mm 1.2 mm 1.2 mm 0.6 mm0.6 mmAxial Recon/Axial Recon/IncrIncr 3/3 3/1.5 3/3 3/1.5 3/33/3Post Processing Post Processing ---- ---- CorCor / Sag / MIP / CPR / VR/ Sag / MIP / CPR / VR
Iodinated contrast material (370 Iodinated contrast material (370 mgImgI/ml); 0.5 s rotation time/ml); 0.5 s rotation timeAEC w/ quality reference 200 AEC w/ quality reference 200 mAsmAs, 120 , 120 kVpkVp
BWH CT Urography Protocol64 64 –– ChannelChannel MDCT with 3 phasesMDCT with 3 phases
McTavishMcTavish et al Radiology 2002et al Radiology 2002
BWH CTU Protocol for pts < 40 y.o.BWH CTU Protocol for pts < 40 y.o.
Split dose Split dose 370 370 mgImgI/ml/ml CM (40cc) (80 cc)UnenhancedUnenhanced NPNP + + EPEP
RangeRange Abd/PelAbd/Pel Abd/PelAbd/PelDelay Delay ---- 6 min6 min 100 sec100 secCollimation 2.5 mm Collimation 2.5 mm 2.5 mm2.5 mmAxial Recon/Axial Recon/IncrIncr 3/3 3/3 3/33/3Post Processing Post Processing ---- CorCor / Sag / MIP / CPR / VR/ Sag / MIP / CPR / VR
Modified from Chow and Modified from Chow and SommerSommer AJR 2001AJR 2001ChaiChai et al et al AustralasAustralas RadiolRadiol 20012001
SalineSaline
Obtaining NP and EP during one scan Obtaining NP and EP during one scan reduces radiation dosereduces radiation dose
Indications: Indications: FullFull CT CT UrogramUrogram•• HematuriaHematuria•• Suspected Suspected urothelialurothelial cancer cancer
(e.g., positive urine cytology)(e.g., positive urine cytology)•• FollowFollow--up up urothelialurothelial cancercancer•• HydronephrosisHydronephrosis ?etiology?etiology•• Others?Others?
Urinary Tract CT ProtocolsUrinary Tract CT Protocols•• Flank pain Flank pain -- > UP (> UP (““Stone protocolStone protocol””))•• Renal mass Renal mass -- > UP, NP, Excretory (Kidney)> UP, NP, Excretory (Kidney)•• Congenital anomalies Congenital anomalies -- > Excretory> Excretory•• Partial Partial nephrectomynephrectomy -- > AP, VP, Excretory> AP, VP, Excretory•• PostPost--operative Comp operative Comp -- > Excretory> Excretory•• Trauma Trauma --> NP, Excretory> NP, ExcretoryUP = unenhanced phase; NP = UP = unenhanced phase; NP = nephrographicnephrographic phasephaseAP = arterial phase; VP = venous phase AP = arterial phase; VP = venous phase
Ureteral Mass-like findings•• LumenalLumenal –– stone, clot, stone, clot, mycetomamycetoma, ,
sloughed papilla, mucussloughed papilla, mucus
•• Mucosal Mucosal –– tumor, stricturetumor, stricture
•• Mural Mural –– ureteritisureteritis cysticacystica, met, , met, leiomyomaleiomyoma
•• Extramural Extramural –– RPF, LN, massRPF, LN, mass
More Ureteral Ca Look-Alikes•• EndometriosisEndometriosis
•• LeukoplakiaLeukoplakia
•• CholesteatomaCholesteatoma
•• MalacoplakiaMalacoplakia
•• TuberculosisTuberculosis
Is CTU Good in detecting UT TCC?Is CTU Good in detecting UT TCC?•• UT TCC is uncommonUT TCC is uncommon•• UT TCC occur in up to 6.5% of pts UT TCC occur in up to 6.5% of pts
w/ known or prior bladder ca.w/ known or prior bladder ca.•• Upper tract needs to be evaluated Upper tract needs to be evaluated
at the time bladder cancer is at the time bladder cancer is diagnosed and periodically in diagnosed and periodically in surveillance.surveillance.
YousemYousem DM. et al. Synchronous and DM. et al. Synchronous and metachronousmetachronoustransitional cell carcinoma of the urinary tract. transitional cell carcinoma of the urinary tract. RadiologyRadiology1988;167:6131988;167:613--618.618.
0
10
20
30
40
50
True Positive False Positive
4343 3939
82 (3%) positive CT 82 (3%) positive CT urogramsurograms (n=2602)(n=2602)
PPV: 43/82 = 52%PPV: 43/82 = 52% SadowSadow et al AJR (in press)et al AJR (in press)
Is CTU Good in Detecting UT TCC?Is CTU Good in Detecting UT TCC?
Is CTU Good in Detecting UT TCC?Is CTU Good in Detecting UT TCC?
0
10
20
30
40
Large Mass(>5 mm)
Small Mass(</=5 mm)
UrothelialThickening
CTU + True +
36
29
17
0
29
14
PPV = 81%PPV = 81%
PPV = 0%PPV = 0%
PPV = 48%PPV = 48%
SadowSadow et al AJR (in press)et al AJR (in press)
Is CTU Good in Detecting UT TCC?Is CTU Good in Detecting UT TCC?•• The PPV (52%) of CTU for detection of The PPV (52%) of CTU for detection of
upper tract malignancies is moderate, upper tract malignancies is moderate, as benign findings mimic canceras benign findings mimic cancer
•• Large (> 5 mm) masses are likely to be Large (> 5 mm) masses are likely to be cancerscancers
•• Small (Small (<< 5 mm) masses are unlikely to 5 mm) masses are unlikely to be cancersbe cancers
•• Urothelial thickening is just as likely to Urothelial thickening is just as likely to be benign as malignantbe benign as malignant
SadowSadow et al AJR (in press)et al AJR (in press)
Imaging Algorithm for Imaging Algorithm for HematuriaHematuriaMDCTUMDCTU
Renal cystRenal cyst Renal massRenal mass NormalNormal Urothelial Urothelial abnabn
Retro Retro PyelogramPyelogramMRIMRI
Note.Note.-- Retrograde Retrograde pyelographypyelographymay still be needed when CTU may still be needed when CTU is positiveis positive……
ThickeningThickening
Single Energy CTSingle Energy CT
waterfat
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
CT-
valu
e (H
U)
10
20
30
40
50
60
70
80
0
spong.bone
lungs
compactbone
kidney
pancreas
blood
liver
Materials differentiated Materials differentiated based on attenuationsbased on attenuationsCourtesy Courtesy ChristianneChristianne LeideckerLeidecker SMSSMS
One xOne x--ray tube, one ray tube, one acquisitionacquisition……
Dual Energy CTDual Energy CT
•• Two xTwo x--ray tubes ray tubes ––kVpkVp same or differentsame or different
•• Tube A = 140 Tube A = 140 kVpkVp, , FOV= 50 cmFOV= 50 cm
•• Tube B = 80 Tube B = 80 kVpkVp, , FOV 26 cm (33 cm)FOV 26 cm (33 cm)
Dual source methodDual source method……50 cm50 cm
26 cm26 cm
Tube Tube BB
Tube Tube AA
Dual Energy CTDual Energy CTN
umbe
r of p
hoto
ns x
101
7N
umbe
r of p
hoto
ns x
10
Num
ber o
f pho
tons
x 1
01717
Photon Energy (keV)Photon Energy (Photon Energy (keVkeV))
22
33
44
55
00 5050 100100 150150
11Tube Tube BB
Tube Tube AA
Mean Energy!Mean Energy!56 56 keVkeV 76 76 keVkeV
140140 kVpkVp
XX--ray beams are
ray beams are polypolychromatic!
chromatic!
Peak Energy!Peak Energy!
8080 kVpkVp
Mean Energy!Mean Energy!
80 Kvp, mean 56 keV80 Kvp, mean 56 keV140 kVp, mean 76 keV140 kVp, mean 76 keV
Dual Energy CTDual Energy CT
•• XX--ray attenuation is ray attenuation is determined by two determined by two independent independent absorption process, absorption process, comptoncompton scatter and scatter and photoelectric effectphotoelectric effect
Basic conceptsBasic concepts……
Compton effect is constantCompton effect is constantPhotoelecticPhotoelectic effects greater at effects greater at lower lower kVpkVp, and soar at k edge, and soar at k edge
Dual Energy CTDual Energy CT
•• Total attenuation decreases Total attenuation decreases with increasing energywith increasing energy
•• Attenuation depends on Attenuation depends on energy (energy (keVkeV) and material ) and material densitydensity
•• XX--ray absorption depends on ray absorption depends on the inner electron shells. the inner electron shells.
•• DECT is sensitive to atomic DECT is sensitive to atomic number and densitynumber and density
Basic conceptsBasic concepts……
Dual Energy CTDual Energy CTA
ttenu
atio
n (c
m2 /g
)A
ttenu
atio
n (c
mA
ttenu
atio
n (c
m22 /g
)/g
)
Photon Energy (keV)Photon Energy (Photon Energy (keVkeV))
0.10.1
11
1010
100100
10001000
00 5050 100100 150150 200200
IodineIodineCalciumCalciumWaterWaterFatFat
56 56 keVkeV 76 76 keVkeV
Large increaseLarge increase
Small increaseSmall increase
Dual Energy CTDual Energy CT
•• DECT can be used to determine DECT can be used to determine concentration of three known concentration of three known materialsmaterials
•• DECT cannot be used to determine DECT cannot be used to determine the chemical composition of an the chemical composition of an unknown materialunknown material
Basic conceptsBasic concepts……
Dual Energy CT Dual Energy CT -- StonesStones
HU @ 140 kVHU @ 140 kVHU @ 140 kV
HU
@ 8
0 kV
HU
@ 8
0 kV
HU
@ 8
0 kV
000
000-90--9090
-100--100100
+60+60+60
+65+65+65
+200+200+200
+100+100+100
FatFat
IodineIodineIodine
Soft TissueSoft TissueSoft Tissue
Stone Composition Stone Composition –– Why?Why?•• Uric acid stones managed with urine Uric acid stones managed with urine
alkalinizationalkalinization; prevented with ; prevented with allopurinolallopurinol•• Calcium stones managed with SWL, PCNL, Calcium stones managed with SWL, PCNL,
or or ureteroscopyureteroscopy; prevented with ; prevented with thiazidesthiazides•• Calcium monohydrate (high HU and Calcium monohydrate (high HU and
homogeneous), homogeneous), brushitebrushite, and , and cystinecystine(particularly >15 mm) stones are resistant to (particularly >15 mm) stones are resistant to ESWLESWL
Kim et al Kim et al UrolUrol Res 2007Res 2007Perks et al Urology 2008Perks et al Urology 2008
CT Attenuations CT Attenuations –– Why not?Why not?•• Overlapping attenuation rangesOverlapping attenuation ranges•• Stones are typically mixedStones are typically mixed•• HU measurements are variable HU measurements are variable and dependent on CT technique and dependent on CT technique (including dose, collimation, (including dose, collimation, section thickness)section thickness)
KambadakoneKambadakone et al et al RadioGraphicsRadioGraphics 2010 2010
Dual Energy CT Dual Energy CT -- StonesStones•• Attenuation depends on density, atomic Attenuation depends on density, atomic
number, and the energy of the Xnumber, and the energy of the X--ray beam.ray beam.•• The higher the atomic number, the higher the The higher the atomic number, the higher the
attenuationattenuation•• Calcium oxalate (CaCCalcium oxalate (CaC22OO44), calcium phosphate ), calcium phosphate
(Ca(Ca33(PO(PO44))22), and ), and cystinecystine (C(C66HH1212NN22OO44SS22) contain ) contain elements with high atomic numbers (Ca = 20, S elements with high atomic numbers (Ca = 20, S = 16, P = 15) or = 16, P = 15) or ‘‘heavyheavy’’ chemical elements.chemical elements.
•• Uric acid (CUric acid (C55HH44NN44OO33) and ) and struvitestruvite (MgNH(MgNH44POPO44--6H6H22O) are composed of elements with low O) are composed of elements with low atomic numbers, or atomic numbers, or ‘‘lightlight’’ chemical elements chemical elements (H,C,N,O)(H,C,N,O) Thomas et al Thomas et al EurEur RadRad 20092009
PrimakPrimak et al et al AcadAcad RadRad 20072007
Dual Energy CT Dual Energy CT -- StonesStones•• As a consequence, uric acid (UA) stones have higher As a consequence, uric acid (UA) stones have higher
attenuations at higher attenuations at higher kVpkVp than at lower than at lower kVpkVp, whereas , whereas nonnon--UA stones have a higher attenuation at lower UA stones have a higher attenuation at lower kVpkVpthan at higher than at higher kVpkVp
•• Most nonMost non--UA stones contain calciumUA stones contain calcium•• A threeA three--material decomposition first assumes that all material decomposition first assumes that all
voxelsvoxels contain a mixture of water (urine), calcium, and contain a mixture of water (urine), calcium, and UA.UA.
•• If the If the voxelvoxel exhibits DE behavior similar to calcium, it exhibits DE behavior similar to calcium, it is assigned a blue color, UA red, and is assigned a blue color, UA red, and voxelsvoxels that show that show a linear density at both tube potentials remain graya linear density at both tube potentials remain gray((GraserGraser Invest Invest RadRad 2007)2007)
Thomas et al Thomas et al EurEur RadRad 20092009PrimakPrimak et al et al AcadAcad RadRad 20072007
Dual Energy CT Dual Energy CT -- StonesStones•• Commercially available software uses a threeCommercially available software uses a three--
material decomposition algorithm (material decomposition algorithm (SyngoSyngo DE DE Viewer, SMS).Viewer, SMS).
•• Stone is considered a mixture of a hypothetical Stone is considered a mixture of a hypothetical ““purepure”” stone with no pores (such a stone would stone with no pores (such a stone would have high attenuation) and the material that fills have high attenuation) and the material that fills the pores, urine.the pores, urine.
•• On a plot of attenuations @ 80 On a plot of attenuations @ 80 kVpkVp vsvs 140 140 kVpkVp, , a real stone has to lie somewhere, depending on a real stone has to lie somewhere, depending on its porosity, between urine and a pure stone.its porosity, between urine and a pure stone.
PrimakPrimak et al et al AcadAcad RadRad 20072007
Dual Energy CT Dual Energy CT -- StonesStones
PrimakPrimak et al et al AcadAcad RadRad 20072007
HU
@ 8
0 kV
HU
@ 8
0 kV
HU
@ 8
0 kV
HU @ 140 kVHU @ 140 kVHU @ 140 kV
““UrineUrine””
““PurePure”” stonestone
All stones of a particular typeAll stones of a particular typewill be represented along this line,will be represented along this line,depending on the porositydepending on the porosity……
Calcium stones have more attenuation at lower Calcium stones have more attenuation at lower kVpkVp, hence, henceDE ratio (HU @80 DE ratio (HU @80 kVpkVp / HU @ 140 / HU @ 140 kVpkVp) will be higher) will be higher
Calcium stones along this lineCalcium stones along this line
Hence the slope can be Hence the slope can be correlated w/ stone compositioncorrelated w/ stone composition
Dual Energy CT Dual Energy CT -- StonesStones
PrimakPrimak et al et al AcadAcad RadRad 20072007HU @ 140 kVHU @ 140 kVHU @ 140 kV
““UrineUrine””
““PurePure”” uric acid stoneuric acid stone
Stones Stones belowbelow angle bisector areangle bisector arecharacterized as UA stones, characterized as UA stones, aboveaboveas nonas non--UA or calcium stonesUA or calcium stones
““PurePure”” calcium stonecalcium stoneSi
ngle
ave
rage
slo
pe re
pres
ents
Sing
le a
vera
ge s
lope
repr
esen
ts
diffe
rent
cal
cium
diffe
rent
cal
cium
--con
tain
ing
ston
es
cont
aini
ng s
tone
s
HU
@ 8
0 kV
HU
@ 8
0 kV
HU
@ 8
0 kV
•• MDCT MDCT urographyurography supplemented with IV supplemented with IV furosemidefurosemide can be used to evaluate the can be used to evaluate the ureterureter
•• Thin (3 mm) sections and Thin (3 mm) sections and multiplanarmultiplanarreformations, particular CPR, are reformations, particular CPR, are helpful when evaluating the helpful when evaluating the ureterureter
•• Beware of benign entities that mimic Beware of benign entities that mimic cancer.cancer.
•• DECT can be used to differentiate DECT can be used to differentiate urateuratestones from nonstones from non--urateurate stones.stones.
SummarySummary
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