Et spektrum av elastografimodaliteter

Transkript

1 Et spektrum av elastografimodaliteter Roald Flesland Havre overlege, PhD Medisinsk Avdeling, gastroseksjonen Nasjonalt Senter for Ultralyd i Gastroenterologi, Haukeland Universitetssykehus, Bergen Elastoworshop Ullevål Sykehus OUS,

2 Oversikt Kroniske leversykdommer Diagnostikk, oppfølgingsverktøy Elastografi Strain elastografi Transient elastografi Point Shear wave (pswe) og Acoustic Radiation Force Imaging (ARFI) 2D-Shear wave elastografi (SSI + GE 2D- SWE)

3 Forløpsindikatorer hvor alvorlig er min leversykdom? MELD score Child-Pugh klasse Kliniske scoringsverktøy: Fib-4, Fibrotest m. fl. Billeddiagnostikk (CT, MR, UL) Elastografi: Kvantitativt mål på levervevets hardhet som uttrykk for fibrosegrad. Noninvasiv, repeterbar, ufarlig

4 Billeddiagnostikk CT: økt tetthet i levervev, regenerasjonsknuter, buklet overflate, fett i lever eller liten skrumpet lever UL: økt attenuasjon ved fettlever. Varierende ekkogenisitet, regenerasjonsknuter, buklet overflate. Økt hastighet i v. Porta. Foruten fett i lever er dette tegn på sene funn forenlig med levercirrhose

5 Bilde av cirrhose (CT og UL)

6 GE E9 E-score + 2D SWE Hitachi Ascendus RTE + SWE Aixplorer, SSI Philips XU22, Elast PQ

7 Elastografi en metode for å visualisere og måle leverstivhet Ulike metoder Strain: måler deformasjon i vevet etter en kompresjon Shear wave: disse bølgene oppstår perpendikulært på en akustisk impuls som deponeres i vevet. Hastigheten på skjærebølgen måles og kvadratet av denne hastigheten er proposjonal med elastisk modulus, E.

8 Soft tissue elasticity imaging- Theory in short: push it and track the deformation or the shear wave! Oct , Rostock. Brækhus vs Lauren (Photo by Boris Streubel/Bongarts/Getty Images)

9 Elastography images the Elastic modulus (E=Youngs modulus) of soft tissues Stress (KPa) Linear elasticity (gelatin) Δ strain Δ stress Biological tissue Strain (%) E= Δ Stress / Δ Strain

10 Elasticity, E (Youngs modulus) Strain elastography (qualitative): E = Δs/Δe s = stress e = strain (Δ deformation) Stress, s (KPa) Shear wave speed: Approximation of tissue elastic modulus, E: (quantitative) Strain, e (%) E = 3ρ(c) 2 ρ = density (1000kg/m 3 ) c = Shear wave speed

11 Available methods for liver elastography Transient Elastography Acoustic Raditation Force Imaging (ARFI) Point shear wave elastography (pswe) Quasi static elastography (Strain imaging) 2D Shear wave imaging Fibroscanner Echosens Siemens Phillips Toshiba Several producers Supersonic imaging Aixplorer GE 2D SWE Method: US probe with a thumper creates a physical push-pulse into the liver and US is used to track this shear wave Method: Acoustic pulse is deposited at user selected position, deformation and shear waves are recorded Method: Strain imaging By external or internal tissue movement Deposition of a parallel acoustic cones covering a larger area with shear wave tracking Quantitative shear wave speed, no image Qualitative map in ARFI. + Quantitative pswe Qualitative: SR, Visual scores, Hepatic strain index, strain %, strain pattern analysis Quantitative and qualitative

12 Strain Calculation Algorithm (By Hitachi Medical corp.) Axial compression Hard Small strain Soft Large strain Compression L soft deltal hard soft Spatial derivation Before After Displacement Strain (%) (Elasticity) RFH MEDVIZ 2013

13 Elastography of focal liver lesions Havre/Hermanns Intraoperative scanning of isoechoic liver metastasis fom colon cancer

14 Metaanalyse: Real-Time elastography for the staging of Hepatic fibrosis Literature search of English full papers April 2000 to April 2014 were used. 23 identified as relevant, 10 excluded,13 used The combined AUROC of the liver fibrosis index (LFI) for the evaluation of significant fibrosis (F 2), advanced fibrosis (F 3), and cirrhosis (F = 4) were 0.79, 0.94, and 0.85, respectively. Using the intercostal muscle as reference tissue gave poorer results. Huisuo Hong et al. Performance of Real-Time Elastography for the Staging of Hepatic Fibrosis: A Meta-Analysis. PLoS One. 2014; 9(12): e Published online 2014 Dec 26.

15 Transient elastography Fibro Scan, for liver tissue stiffness measurement 3.5 MHz probe with 50 Hz thumper placed intercostally over right liver lobe Emits a vibration pulse (Shear wave) tracked by US into the liver tissue Gives up elasticity in kpa No US image relatively easy to use Shear elasticity probe for soft tissues with 1-D transient elastography.sandrin L, Tanter M, Gennisson JL, Catheline S, Fink MIEEE Trans Ultrason Ferroelectr Freq Control Apr;49(4):

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17 Transient elastography (TE) results according to A the fibrosis score (Metavir) B the necroinflammatory activity (195 patients who underwent both TE and liver biopsy) A B Fraquelli, M. et al. Gut 2007;56: Nasjonalt Copyright 2007 Senter BMJ Publishing for Gastroenterologisk Group Ltd. Ultrasonografi

18 Transient elastography (TE) for staging of fibrosis in people with alcoholic liver disease. Retrospective meta analysis, 14 studies, 834patients provided numerical data for analysis (August 2014). Only half of the studies were monoaetiology studies. TE may be used as a diagnostic method to exclude cirrhosis or severe fibrosis when the test is negative. Cut-off values of around 12.5 kpa for cirrhosis may be used in clinical practice, but not validated prospectively Pavlov CS et al. Systematic review with meta-analysis: diagnostic accuracy of transient elastography for staging of fibrosis in people with alcoholic liver disease. Aliment Pharmacol Ther Mar;43(5):

19 Real-time ARFI imaging measurement in liver of 41-year-old man with fibrosis stage F3. Friedrich-Rust M et al. Radiology 2009;252: by Radiological Society of North America

20 Philips Elast PQ Samsung RS80A Elastography Hitachi SWE

21 ARFI elastografi på 68 friske frivillige hva påvirker måleresultatet? Male patients had significantly higher median SWVs (p = ) than female patients. Patients with body mass indexes >22 had significantly lower median SWVs (p = ) than those with body mass indexes 22. The reference ranges for median and mean SWV were and m/s, respectively. Gender and body mass index, but not age, were the significant factors associated with ARFI SWV values. Liao LY et al. Ultrasound Med Biol Mar;41(3): Epub 2015 Jan 28. Acoustic radiation force impulse elastography of the liver in healthy patients: test location, reference range and influence of gender and body mass index.

22 Sammenlikning av leverstivhet målt med to point-shear wave metoder: ARFI og ElastPQ (176 pasienter) Aim: differentiate between subjects with or without chronic liver disease ARFI: LS cut-off value >1.4 m/second: 83.1%accuracy (AUROC=0.822) ElastPQ: LS cut off value >1.23 m/second, with 83.7% accuracy (AUROC=0.851). Both available pswe techniques have very good feasibility for the non-invasive liver fibrosis assessment and a good performance for predicting the presence of liver pathology. LS values obtained by Elast PQ technique are significantly lower than those obtained by ARFI elastography. Sporea I et al. Med Ultrason Dec;16(4): Comparative study between two point Shear Wave Elastographic techniques: Acoustic Radiation Force Impulse (ARFI) elastography and ElastPQ.

23 2D Shear wave imaging Flere akustiske pulser deponeres i et område og skjære-bølgene følges med UL bølger med svært høy frame rate Man oppnår både et sann tids elastogram med fargekoder og kan måle vevshardhet i kpa i ethvert punkt med signal innenfor ROI Supersonic Imaging (SSI) General Electrics 2D SWE

24 GE 2D- SWE Fantom med inklusjon med økt vevshardhet ca 80 kpa.

25 2D Shear wave elasto fra GE Lager en fargekodet elastogram der rødt representerer hardt og blått mykt. Fargekartet viser hvor homogen elastisiteten er, og om det er signalbortfall i kar etc. En rund ROI plasseres innenfor boksen for å måle elastisitet kvantitativt

26 Kombinasjonsløsning Fibroscan og 2D-SWE på en og samme scanner

27 Supersonic imaging (SSI) Plane wave technology Frame rate >5.000/s Shear waves are created as acoustic cones by several, rapidly consecutive acoustic impulses deployed at increasing depths Supersonic shear imaging: a new technique for soft tissue elasticity mapping.bercoff J, Tanter M, Fink M. IEEE Trans Ultrason Ferroelectr Freq Control Apr;51(4):

28 Aixplorer Supersonic shear wave Imaging (SSI) Fibroadenoma <30KPa Ductal carcinoma Cyst, no elastography signal Source: Supersonic imagine

29 Accuracy of real time shear wave elastography for assessing liver fibrosis in chronic hepatitis C: A pilot study ROC curves: Comparison between Transient Elastography (fibroscan) and Supersonic shear wave imaging (SSI) in seperating fibrosis grade (Metavir 0-4). N=121 A: F0-F1 vs >F2 B: F0-F2 vs >F3 C: F0-F3 vs F4 Ferraioli G. et al. Accuracy of real-time shear wave elastography for assessing liver fibrosis in chronic hepatitis C: A pilot study Hepatology.Volume 56, Issue 6, pages , 31 AUG 2012

30 Meta anlysis of biopsy proven liver fibrosis with 2D SWE (SSI) 2D-SWE and liver biopsy was available in 1134 patients from 13 sites + transient elastography (TE) in 665 patients. Chronic hepatitis C (HCV, n = 379),hepatitis B (HBV, n = 400) or nonalcoholic fatty liver disease (NAFLD, n = 156). Significant fibrosis (F2): AUROCs of 2D-SWE in patients with HCV, HBV and NAFLD were 86.3%, 90.6% and 85.5% Cirrhosis: 92.9%, 95.5% and 91.7% for diagnosing cirrhosis, respectively. AUROC of 2D-SWE was (95% CI) larger than AUROC of TE for diagnosing significant fibrosis (p = 0.001) and for diagnosing cirrhosis (p = 0.022) in all patients. This difference was strongest in HBV patients. Herrmann E et al: Assessment of biopsy-proven liver fibrosis by 2D-shear wave elastography: An individual patient data based meta-analysis. Hepatology Mar 31. doi: /hep

31 Sammenlikning av påvisning av signifikant fibrose i lever med transient elastografi (XL probe) med SSI i hø og ve leverlapp hos 124 overvektige pasienter Probe/målested Signifikant fibrose (3-4) AUROC FibroScan XL SSI høyre leverlapp SSI venstre levelapp Cirrhose (stad 4) AUROC SSI and the TE-XL probe each accurately quantify liver fibrosis compared to histology in overweight or obese patients with chronic liver disease, including those with HCV infection (102) SSI data obtained from the right lobe and the TE-XL probe can be used to evaluate fibrosis with similar accuracy. Yoneda M et al. Supersonic Shear Imaging and Transient Elastography With the XL Probe Accurately Detect Fibrosis in Overweight or Obese Patients With Chronic Liver Disease. Clin Gastroenterol Hepatol Mar [Epub ahead of print]

32 Elastografibilder av leveren er påvirket av flere faktorer: Trykkkraft med proben og respirasjonsfase Aktiv inflammasjon og hjertesvikt Fibrose Elastogram

33 Uløste problemstillinger som påvirker lever elastografi Faste? Respirasjonsfase? Høyre leverlapp: større, mindre bevegelse, økt reproduserbarhet? Høyre hjertesvikt (leverstuvning) ALAT nivå (inflammasjon) Elastografi av milten kan muligens gi et mål på graden av figrose/cirrose. Speiler portal hypertensjon?

34 Flere faktorer påvirker leverstivhetsmåling inflammasjon er en av dem Inflammation has a significant influence on liver stiffness measurement values in patients with chronic hepatitis B with mild fibrosis, but not in those with significant fibrosis. Zeng X et al. Influence of Hepatic Inflammation on FibroScan Findings in Diagnosing Fibrosis in Patients with Chronic Hepatitis B. Ultrasound Med Biol Feb 24. [Epub ahead of print]

35 Oppsummerig: UL elastografimetoder Strain Elastography (Quasi static elastography) Fused: Qualitative strain map + B-mode US image, Liver Fibrosis Index Transient elastography (Fibroscan) Shear wave based Liver elasticity measurement No imaging Acoustic Radiation Force Impulse (ARFI) imaging Deformation image (strain) + shear wave speed in small ROI Point-Shear-Wave elastography Shear-wave speed in small ROI, no deformation image 2D Shear wave elastography (2D SWE) Qualitative + quantitative shear wave based image + B mode Supersonic shear wave imaging (SSI) + GE 2D-SWE