When is MRI Useful in When is MRI Useful in Evaluating Renal Masses?Evaluating Renal Masses?Stuart G. Silverman, M.D., FACRStuart G. Silverman, M.D., FACR

Professor of RadiologyProfessor of RadiologyHarvard Medical School Harvard Medical School

Director, Abdominal Imaging and Director, Abdominal Imaging and InterventionIntervention

Brigham and WomenBrigham and Women’’s Hospitals HospitalBoston, MABoston, MA

When is MRI Useful in When is MRI Useful in Evaluating Renal Masses?Evaluating Renal Masses?Stuart G. Silverman, M.D., FACRStuart G. Silverman, M.D., FACR

Consultant, Consultant, GalilGalil Medical Ltd, Medical Ltd, YokneamYokneam, Israel, Israel

Book Royalties, Lippincott, Williams, Book Royalties, Lippincott, Williams, & Wilkins, Philadelphia, PA& Wilkins, Philadelphia, PA

Disclosures:Disclosures:

Renal Mass MRI IndicationsRenal Mass MRI IndicationsAlthough CT is the initial Although CT is the initial

test of choice in test of choice in detecting and detecting and

characterizing renal characterizing renal masses, MRI is valuable masses, MRI is valuable

in selected patients.in selected patients.

Renal Mass MRI IndicationsRenal Mass MRI Indications

•• Iodinated CM allergyIodinated CM allergy•• Renal Insufficiency (Diffusion)Renal Insufficiency (Diffusion)•• PregnancyPregnancy•• Young patients, need for serial Young patients, need for serial f/uf/u

Patient populationsPatient populations……

……CT relatively contraindicatedCT relatively contraindicated

•• HyperdenseHyperdense, enhancing mass, enhancing mass•• Indeterminate cystic massIndeterminate cystic mass•• Pre and post ablationPre and post ablation•• (Staging questions e.g., IVC (Staging questions e.g., IVC

involvement and extent)involvement and extent)

Clinical problemsClinical problems……

Renal Mass MRI IndicationsRenal Mass MRI Indications

……MRI provides added valueMRI provides added value

Renal Mass MR ProtocolRenal Mass MR Protocol•• T1T1--w SPGR or FSEw SPGR or FSE•• T2T2--w FRFSE or SSFSEw FRFSE or SSFSE•• Chemical Shift (In/OOP)Chemical Shift (In/OOP)•• T1T1--w SPGR, Fat w SPGR, Fat

suppressed, pre + post suppressed, pre + post contrast materialcontrast material

•• Subtraction imagesSubtraction images……Enhanced ProtocolEnhanced Protocol

BWH Gadolinium PolicyBWH Gadolinium Policy•• Obtain serum Cr / Obtain serum Cr / eGFReGFR (w/in 3 (w/in 3 wks) in pts with h/o kidney disease, wks) in pts with h/o kidney disease, DM, SLE, MM, on dialysis, or +DM, SLE, MM, on dialysis, or +FHxFHx•• eGFReGFR > 60 > 60 –– any dose any dose GdGd givengiven•• eGFReGFR 3030--60 60 –– max 20 cc max 20 cc GdGd•• eGFReGFR <30, dialysis, or <30, dialysis, or hepatorenalhepatorenalsyndrome syndrome –– ““medical necessitymedical necessity””; ; written informed consent obtainedwritten informed consent obtained

Renal Mass MR ProtocolRenal Mass MR Protocol•• T1T1--w SPGR or FSEw SPGR or FSE•• T2T2--w FRFSE or SSFSEw FRFSE or SSFSE•• Chemical Shift (In/OOP)Chemical Shift (In/OOP)•• GRASSGRASS•• Diffusion (DWI) B = 0, 200, Diffusion (DWI) B = 0, 200, 400, 800, 1000; ADC (3T)400, 800, 1000; ADC (3T)

……Unenhanced ProtocolUnenhanced Protocol

Renal Mass MRIRenal Mass MRI•• Structural analysis Structural analysis

((BosniakBosniak applied to MRI)applied to MRI)•• T1 and T2 T1 and T2 •• Contrast media enhancementContrast media enhancement•• Fat cell detection Fat cell detection

(fat suppression)(fat suppression)•• IntracytoplasmicIntracytoplasmic lipid lipid

detection (chemical shift)detection (chemical shift)•• DiffusionDiffusion

Cystic Renal MassesCystic Renal Masses(after (after BosniakBosniak))

Aronson Aronson UrolUrol RadRad 19911991

CatCat TermTerm ProbProb % Remark% Remark

II SimpleSimple 00 proven proven

IIII ComplicatedComplicated @0@0 variablevariable

IIFIIF IndeterminateIndeterminate ?? IsraelIsrael

IIIIII IndeterminateIndeterminate 5050 Aronson Aronson

IVIV Solid FeaturesSolid Features >95>95 CurryCurry

Curry AJR 1991Curry AJR 1991

Israel AJR 2003Israel AJR 2003

Israel and Israel and BosniakBosniak Radiology 2005Radiology 2005BosniakBosniak MA Radiology 1991MA Radiology 1991

Cystic Renal Masses Cystic Renal Masses ––BosniakBosniak applied to MRIapplied to MRI

•• Of 69 cystic masses, MR identified more Of 69 cystic masses, MR identified more septa in 8 (12%) masses and thicker walls or septa in 8 (12%) masses and thicker walls or septa in 7 (10%) compared with CT.septa in 7 (10%) compared with CT.

•• In 2 (3%) masses, enhancement was In 2 (3%) masses, enhancement was different.different.

•• MR upgraded 7 masses: II to IIF in 2, IIF to MR upgraded 7 masses: II to IIF in 2, IIF to III in 3, and III to IV in 2.III in 3, and III to IV in 2.

Israel and Israel and BosniakBosniak Radiology 2004Radiology 2004

Cystic Renal Masses Cystic Renal Masses ––BosniakBosniak applied to MRIapplied to MRI

•• MRI may show enhancement not seen at CTMRI may show enhancement not seen at CT

•• MRI may correct MRI may correct pseudoenhancementpseudoenhancement at CTat CT

•• MRI may miss calcificationsMRI may miss calcificationsMRI most helpfulMRI most helpful::Category IIF and III lesionsCategory IIF and III lesionsConfirm minimal (<1 cm) cystic masses as Confirm minimal (<1 cm) cystic masses as simplesimple……

Israel and Israel and BosniakBosniak Radiology 2004Radiology 2004

ROI PrinciplesROI Principles•• Same acquisition Same acquisition

parameters pre + postparameters pre + post•• Search enhanced Search enhanced

images firstimages first•• LesionLesion ROIROI•• Homogeneous Homogeneous

population of tissuespopulation of tissues

Enhancement at MRIEnhancement at MRI

•• Unequivocal Unequivocal >> 20 20 %%•• EquivocalEquivocal 15 15 –– 19 19 %%•• NoneNone < 15 < 15 %%

% = SI Change / Native SI% = SI Change / Native SI

Ho VB Radiology 2002Ho VB Radiology 2002

Renal Cell CarcinomaRenal Cell Carcinoma

Clear cell Clear cell 70%70% 5555--60%60%

Papillary Papillary 1515--20%20% 8080--90%90%

ChromophobeChromophobe 66--11%11% 90%90%

Collecting ductCollecting duct <1%<1% <5%<5%

UnclassifiedUnclassifiedKim AJR 02 178:1499Kim AJR 02 178:1499

SubtypeSubtype Prevalence Prognosis*Prevalence Prognosis*

*5*5--yr survivalyr survival

MRI Features of Renal MassesMRI Features of Renal MassesT1T1 T2T2 CECE DxDxdarkdark brightbright -- Simple CystSimple Cystbright bright brightbright -- High Protein CystHigh Protein Cystbrightbright darkdark -- Hemorrhage/CystHemorrhage/Cystdarkdark brightbright ++ RCC (CC type)RCC (CC type)dark/dark/ darkdark ++ AML, RCC AML, RCC brightbright (papillary) (papillary) brightbright brightbright ++ AML, RCC (CC)AML, RCC (CC)

MRI of Papillary RCC (n=20)MRI of Papillary RCC (n=20)MRI FeatureMRI Feature T1 SET1 SE T1 GET1 GE

0013 (93%)13 (93%)

1 (7%)1 (7%)

0066

IsointenseIsointense9 (53%)9 (53%)8 (47%)8 (47%)

HyperintenseHyperintense 00 00

HeterogenousHeterogenous 00 6 (30%)6 (30%)

00

33

T2T2HypointenseHypointense 14 (70%)14 (70%)

Not performedNot performed 00

83% (10/12) of small (<3cm) tumors 83% (10/12) of small (<3cm) tumors were T2were T2--hypointensehypointense

OlivaOliva et al AJR 2009et al AJR 2009

AML AML –– Keys to DiagnosisKeys to Diagnosis

4% 4% AMLsAMLs contain no contain no definite fat by imagingdefinite fat by imaging

AngiomyolipomaAngiomyolipomawith minimal fatwith minimal fat

AML without Fat by Imaging AML without Fat by Imaging

JinzakiJinzaki et al, Radiology 1997et al, Radiology 1997

•• Retrospective review of 175 resected Retrospective review of 175 resected lesions suspicious for RCC by lesions suspicious for RCC by imaging.imaging.

•• All 6 All 6 AMLsAMLs were uniformly were uniformly hyperdensehyperdense, enhanced, and were , enhanced, and were hypointensehypointense on T2on T2

•• Of 100 Of 100 RCCsRCCs reviewed: only 2% were reviewed: only 2% were uniformly uniformly hyperdensehyperdense & enhancing& enhancing

AngiomyolipomaAngiomyolipomaThe identification of The identification of fat cellsfat cells in in

a a noncalcifiednoncalcified renal mass, in an renal mass, in an

adult, is virtually diagnostic ofadult, is virtually diagnostic of

a benign renal a benign renal angiomyolipomaangiomyolipoma

Fat cells (FC) vs. Fat cells (FC) vs. IntracytoplasmicIntracytoplasmic Lipid (ICL)Lipid (ICL)

Kidney Kidney FCFC ICLICLRCCRCC N *N * YYAMLAML YY YY

* Except case reports* Except case reports

AML with Minimal FatAML with Minimal Fat•• Biopsy can be used to diagnose Biopsy can be used to diagnose AML, particularly with the aid of AML, particularly with the aid of immunocytochemistryimmunocytochemistry

Granter et al Cancer 1999Granter et al Cancer 1999

AMLAML RCCRCCMART1 MART1 ++ --SMASMA ++ --HMBHMB--45 45 ++ --RCCRCC -- ++

AML AML –– Diagnostic CriteriaDiagnostic Criteria•• CTCT -- ROI < ROI < --10 HU10 HU

•• MRIMRI -- fat suppression fat suppression ((notnot OOPS alone)OOPS alone)

•• BiopsyBiopsy -- fat cells; thick fat cells; thick walled vessels, smooth walled vessels, smooth muscle (SMA and HMB45)muscle (SMA and HMB45)

AML w/ AML w/ imageable

imageable fat cells!fat cells!

AML w/o AML w/o imageable

imageable fat cells!fat cells!

AML with Minimal fatAML with Minimal fat•• AMLsAMLs demonstrating no demonstrating no fat have a characteristic fat have a characteristic appearance (appearance (hyperdensehyperdenseand enhancing) that is not and enhancing) that is not common for RCC.common for RCC.•• Biopsy can be used to Biopsy can be used to biopsy them, and avoid biopsy them, and avoid unnecessary surgeryunnecessary surgery

Renal Mass BiopsyRenal Mass Biopsy

•• Small (Small (<<3 cm), 3 cm), hyperdensehyperdense, , homogeneouslyhomogeneously enhancing renal enhancing renal masses masses

•• Renal masses referred for Renal masses referred for percutaneouspercutaneous ablationablation

•• Indeterminate cystic renal massIndeterminate cystic renal mass((BosniakBosniak Category III)Category III)

Emerging IndicationsEmerging Indications

Silverman et al Radiology 2006Silverman et al Radiology 2006

Short (dark) T2 MassesShort (dark) T2 Masses•• Hemorrhagic cystHemorrhagic cyst

•• RCC (papillary type or RCC (papillary type or clear cell RCC that bled)clear cell RCC that bled)

•• AML (fat poor, rich in AML (fat poor, rich in smooth ms smooth ms –– spindle cells)spindle cells)

•• ((LeiomyomaLeiomyoma of capsule)of capsule)

Diffusion Weighted ImagingDiffusion Weighted Imaging•• Random motion of water Random motion of water molecules (Brownian notion)molecules (Brownian notion)

Free DiffusionFree Diffusion Restricted DiffusionRestricted Diffusion

•• Occurs in intracellular, Occurs in intracellular, extracellular, and intravascular extracellular, and intravascular spacesspaces

Diffusion Weighted ImagingDiffusion Weighted Imaging

•• Cancer Cancer (increased number of cells)(increased number of cells)

•• Ischemia Ischemia ((cytotoxiccytotoxic edema)edema)

•• Inflammation Inflammation (increased viscosity)(increased viscosity)

DDxDDx -- Restricted DiffusionRestricted Diffusion

ADC (Apparent Diffusion Coefficient)ADC (Apparent Diffusion Coefficient)

•• Low ADC valuesLow ADC values•• Low SI on ADC map (contrasts DWI)Low SI on ADC map (contrasts DWI)

Tissues with restricted diffusionTissues with restricted diffusion

•• High ADC valuesHigh ADC values•• High SI on ADC map (contrasts DWI)High SI on ADC map (contrasts DWI)

Tissues with free diffusionTissues with free diffusion

•• High ADC = well diff or necrotic tumorHigh ADC = well diff or necrotic tumor•• Low ADC = may be normal, nodesLow ADC = may be normal, nodes

Pitfalls!Pitfalls!

Diffusion Weighted ImagingDiffusion Weighted Imaging

UsuallyUsuallyCancerCancer

T2 shineT2 shinethroughthrough

FibrosisFibrosis

DxDx T2WI*T2WI* DWIDWI ADCADC

*variable, *variable, egeg, PRCC, Prostate ca , PRCC, Prostate ca –– T2 T2 hypointensehypointense

DWI DWI –– Renal MassesRenal Masses•• Mean ADC of RCC (1.41) was Mean ADC of RCC (1.41) was significantly lower than benign significantly lower than benign lesions (2.23) (ADCx10lesions (2.23) (ADCx1033/mm/mm22/sec) /sec) •• Mean ADC of Mean ADC of oncocytomasoncocytomas(1.91) was significantly higher (1.91) was significantly higher than solid RCC (1.54). than solid RCC (1.54). ••AML had the lowest ADC AML had the lowest ADC thoughthough……

TaouliTaouli et al Radiology 2009et al Radiology 2009

Diagnostic AlgorithmDiagnostic AlgorithmRenal massRenal mass

Pre Pre -- Contrast CTContrast CT

Contrast CTContrast CT<< 20 H20 H

+ + ΔΔ 20H20H no no ΔΔ

Solid Solid neoplasmneoplasm

Simple cystSimple cyst

no no ΔΔ

20 20 -- 40 H40 H

SonographySonography

+ + ΔΔ 20 H20 H

Solid Solid neoplasmneoplasm

cysticcystic

ProteinaceousProteinaceous cystcyst

solidsolid

Solid neoplasmSolid neoplasm

<<--10 H10 H

AMLAML

>40 H>40 H

Diagnostic AlgorithmDiagnostic AlgorithmContrast CTContrast CT

no no ΔΔ

HyperdenseHyperdense cystcyst

+ + ΔΔ 20H20H MRIMRI

Hyper T2Hyper T2 Hypo T2Hypo T2

RCCRCC BiopsyBiopsy RCC (papillary)RCC (papillary)

AMLAML

+ OOPS+ OOPS

RCC (clear cell)RCC (clear cell)

AMLAML

>40 H>40 H

+ Fat Supp+ Fat Supp AMLAML-- Fat SuppFat Supp

-- OOPSOOPS

Silverman SG et al Silverman SG et al RadioGraphicsRadioGraphics 20072007

Take Home MessagesTake Home Messages•• There are specific indications for There are specific indications for

MRI of renal massesMRI of renal masses•• Apply Apply BosniakBosniak classificationclassification•• Use T1, T2, CE, FS, CSI, as cluesUse T1, T2, CE, FS, CSI, as clues•• Masses with short T2 are fewMasses with short T2 are few•• Look for fat cells (AML)Look for fat cells (AML)•• DonDon’’t use t use OOPsOOPs alone to alone to DxDx AMLAML•• Beware of AML with little or no Beware of AML with little or no

fatfat

Take Home MessagesTake Home Messages•• MRI evaluates MRI evaluates hyperdensehyperdense

masses and can be used to masses and can be used to distinguish AML with minimal distinguish AML with minimal fat from clear cell RCC.fat from clear cell RCC.

•• MRI cannot be used to MRI cannot be used to differentiate AML with minimal differentiate AML with minimal fat from papillary RCC or fat from papillary RCC or CCRCC that bledCCRCC that bled

•• Biopsy can be usefulBiopsy can be useful

Take Home MessagesTake Home Messages•• The use of contrastThe use of contrast--enhanced enhanced MRI in patients with MRI in patients with eGFReGFR <60 is <60 is evolving, as we understand the evolving, as we understand the underlying causes of NSF.underlying causes of NSF.•• As T1, T2, FS, and CSI each As T1, T2, FS, and CSI each contribute diagnostic information, contribute diagnostic information, nonnon--contrast MRI may be useful.contrast MRI may be useful.•• DiffusionDiffusion--weighted MRI may be weighted MRI may be helpful, but needs research.helpful, but needs research.