Pitfalls and Artefacts using Contrast Enhanced Ultrasound

Zusammenfassung

Der Ultraschall stellt heute die Methode der ersten Wahl zur Diagnostik und Charakterisierung von fokalen und diffusen Organpathologien dar. Bekannt ist, dass für einen richtigen Einsatz des B-Mode- und Farbdoppler-Ultraschalls eine profunde Kenntnis der technischen Grundlagen erforderlich ist. Die junge Technik des kontrastverstärkten Ultraschalls besitzt heute zunehmende Bedeutung bei der Diagnostik von Pathologien der Leber, des Pankreas und der Nieren. Dies ist zurückzuführen auf: (a) wachsende Erkenntnisse des Kontrastverhaltens, welche sich durch eine enorme Zahl an Studien, insbesondere im Bereich der Leber zeigen, (b) nahezu keine Nebenwirkung des eingesetzten Kontrastmittels (1:10 000 im Vergleich zu 1 – 12:100 bei jodhaltigen Kontrastmitteln) und insbesondere die fehlende Kontraindikation bei Niereninsuffizienz und Hyperthyreose, (c) ein im Vergleich zu Röntgenkontrastmitteln vertretbarer Preis des Ultraschallkontrastmittels (abhängig von den lokalen Gegebenheiten vor Ort [Indikation, Art des Kontrastmittel, Erstattungsfähigkeit]). Umso wichtiger sind bei Einführung neuer Techniken profunde Kenntnisse in den physikalischen Grundlagen und Kenntnisse in Bezug auf mögliche Artefaktbildungen, die zu Missinterpretationen führen können. Leider sind entsprechende Veröffentlichungen zu diesem Thema selten. In diesem Artikel werden sowohl die Grundlagen erläutert als auch Fehlermöglichkeiten anhand von Beispielen erklärt. Insbesondere wird eingegangen auf Fehlermöglichkeiten betreffend: (i) den mechanischen Index (Zerstörung der Kontrastmittelbläschen), (ii) der Möglichkeit einer Kontrastgebung in nicht vaskularisierten Arealen, (iii) einer zu hohen Kontrastmitteldosis, (iv) der Bildaufbaurate und örtlichen Auflösung, (v) der Untersuchung schallkopffern gelegener Areale, (vi) der Fokuslage bei der Detektion und Charakterisierung von Läsionen, (vii) Vorteile und Nachteile von der Nutzung einer erneuten Anflutung nach Kontrastmittelzerstörung, (viii) der Verlässlichkeit von Doppler-Analysen nach Kontrastmittelgabe.

Abstract

Ultrasound is the method of choice in the detection and characterization of diffuse and focal organic diseases. For B-mode and colour (power) Doppler ultrasound, besides manual skills, (hands-on) a technical knowledge about ultrasound images is of the upmost importance for the investigator. Contrast enhanced ultrasound (CEUS) has become an important diagnostic tool for hepatic, renal, pancreatic indications and several others due to: (a) an increasing rate of studies resulting in sufficient evidence especially in hepatic indications, (b) a rate of adverse events close to zero (1:10.000 in comparison to iodinated contrast agents from 1 – 12:100) enabling the application of CEUS in patients with severe renal insufficiency or thyroid gland autonomy, and (c) a reasonable price (depends on the country and influence of the health-care system [reimbursement]) and the dosage used. Mini-doses from 0.1 to 0.4 mL are used depending on the contrast agent and applied indication. Therefore a well founded knowledge concerning the technical aspects of CEUS is important for the investigator to avoid misinterpretation especially when artefacts specific for CEUS occur. Special literature is rare. In the presented article we present pitfalls concerning CEUS. The following aspects are considered and illustrated by images: (i) acoustic power (mechanical index) and other aspects resulting in micro bubble destruction, (ii) the possibility of false positive contrast signals in non-vascularized areas, (iii) attenuation caused by too high contrast agent dose, (iv) influence of the frame rate on the spatial resolution, (v) dealing with deep located lesions, (vi) differences in focus positioning in detection and characterization studies, (vii) advantages and disadvantages of replenishment studies, (viii) reliability of contrast enhanced spectral Doppler measurements.

Schlüsselwörter

Sonografie - Artefakte - Bildinterpretation - Fallgruben

Key words

ultrasonography - artefacts - image interpretation - pitfalls

References

• 1 Greis C. Ultrasound contrast agents as markers of vascularity and microcirculation.  Clin Hemorheol Microcirc. 2009;  43 1-9
• 2 Singh J, Daftary A. Iodinated contrast media and their adverse reactions.  J Nucl Med Technol. 2008;  36 69-74
• 3 Correas J M, Burns P N, Lai X et al. Infusion versus bolus of an ultrasound contrast agent: in vivo dose-response measurements of BR 1.  Invest Radiol. 2000;  35 72-79
• 4 Lampaskis M, Averkiou M. Investigation of the relationship of nonlinear backscattered ultrasound intensity with microbubble concentration at low MI.  Ultrasound Med Biol. 2010;  36 306-312
• 5 Wei K, Le E, Bin J P et al. Quantification of renal blood flow with contrast-enhanced ultrasound.  J Am Coll Cardiol. 2001;  37 1135-1140
• 6 Bernatik T, Seitz K, Blank W et al. Unclear focal liver lesions in contrast-enhanced ultrasonography – lessons to be learned from the DEGUM multicenter study for the characterization of liver tumors.  Ultraschall in Med. 2010;  epub DOI 10.1055/s-0029-1245649
• 7 Seitz K, Bernatik T, Strobel D et al. Contrast-enhanced ultrasound (CEUS) for the characterization of focal liver lesions in clinical practice (DEGUM multicenter trial): CEUS vs. MRI – a prospective comparison in 269 patients.  Ultraschall in Med. 2010;  31 492-499
• 8 Seitz K, Strobel D, Bernatik T et al. Contrast-enhanced ultrasound (CEUS) for the characterization of focal liver lesions – prospective comparison in clinical practice: CEUS vs. CT (DEGUM multicenter trial). Parts of this manuscript were presented at the Ultrasound Dreilandertreffen 2008, Davos.  Ultraschall in Med. 2009;  30 383-389
• 9 Strobel D, Seitz K, Blank W et al. Tumor-specific vascularization pattern of liver metastasis, hepatocellular carcinoma, hemangioma and focal nodular hyperplasia in the differential diagnosis of 1,349 liver lesions in contrast-enhanced ultrasound (CEUS).  Ultraschall in Med. 2009;  30 376-382
• 10 Strobel D, Seitz K, Blank W et al. Contrast-enhanced ultrasound for the characterization of focal liver lesions – diagnostic accuracy in clinical practice (DEGUM multicenter trial).  Ultraschall in Med. 2008;  29 499-505
• 11 Wei K, Skyba D M, Firschke C et al. Interactions between microbubbles and ultrasound: in vitro and in vivo observations.  J Am Coll Cardiol. 1997;  29 1081-1088
• 12 Choudhry S, Gorman B, Charboneau J W et al. Comparison of tissue harmonic imaging with conventional US in abdominal disease.  Radiographics. 2000;  2 1127-1135
• 13 Blomley M, Albrecht T, Cosgrove D et al. Stimulated acoustic emission in liver parenchyma with Levovist.  Lancet. 1998;  351 568
• 14 Claudon M, Cosgrove D, Albrecht T et al. Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS) – update 2008.  Ultraschall in Med. 2008;  29 28-44
• 15 Dietrich C F, Ignee A, Frey H. Contrast-enhanced endoscopic ultrasound with low mechanical index: a new technique.  Z Gastroenterol. 2005;  43 1219-1223
• 16 Dietrich C F. Contrast-enhanced low mechanical index endoscopic ultrasound (CELMI-EUS).  Endoscopy. 2009;  41 (Suppl 2) E43-E44
• 17 Ressner M, Jansson T, Cedefamn J et al. Contrast biases the autocorrelation phase shift estimation in Doppler tissue imaging.  Ultrasound Med Biol. 2009;  35 447-457
• 18 Rognin N G, Frinking P, Costa M et al. In-vivo perfusion quantification by contrast ultrasound: Validation of the use of linearized video data vs. raw RF data, Proceedings of the Ultrasonics Symposium.  IUS. 2008;  IEEE 1690-1693
• 19 Yu H, Jang H J, Kim T K et al. Pseudoenhancement within the local ablation zone of hepatic tumors due to a nonlinear artifact on contrast-enhanced ultrasound.  Am J Roentgenol. 2010;  194 653-659
• 20 Hudson J M, Karshafian R, Burns P N. Quantification of flow using ultrasound and microbubbles: a disruption replenishment model based on physical principles.  Ultrasound Med Biol. 2009;  35 2007-2020
• 21 Koster J, Schlosser T, Pohl C et al. Blood flow assessment by ultrasound-induced destruction of echocontrast agents using harmonic power Doppler imaging: which parameters determine contrast replenishment curves?.  Echocardiography. 2001;  18 1-8
• 22 Ignee A, Jedrejczyk M, Schuessler G et al. Quantitative contrast enhanced ultrasound of the liver for time intensity curves – reliability and potential sources of errors.  Eur J Radiol. 2010;  73 153-158
• 23 Wilson S R, Burns P N. Microbubble contrast for radiological imaging: 2. Applications.  Ultrasound Q. 2006;  22 15-18
• 24 Burns P N, Wilson S R. Microbubble contrast for radiological imaging: 1. Principles.  Ultrasound Q. 2006;  22 5-13
• 25 Ressner M, Brodin L A, Jansson T et al. Effects of ultrasound contrast agents on Doppler tissue velocity estimation.  J Am Soc Echocardiogr. 2006;  19 154-164
• 26 Dietrich C F, Schuessler G, Trojan J et al. Differentiation of focal nodular hyperplasia and hepatocellular adenoma by contrast-enhanced ultrasound.  Br J Radiol. 2005;  78 704-707
• 27 Dietrich C F, Ignee A, Trojan J et al. Improved characterisation of histologically proven liver tumours by contrast enhanced ultrasonography during the portal venous and specific late phase of SHU 508A.  Gut. 2004;  53 401-405
• 28 Dietrich C F. Comments and illustrations regarding the guidelines and good clinical practice recommendations for contrast-enhanced ultrasound (CEUS) – update 2008.  Ultraschall in Med. 2008;  29 (Suppl 4) S188-S202
• 29 Dietrich C F, Mertens J C, Braden B et al. Contrast-enhanced ultrasound of histologically proven liver hemangiomas.  Hepatology. 2007;  45 1139-1145
• 30 Mork H, Ignee A, Schuessler G et al. Analysis of neuroendocrine tumour metastases in the liver using contrast enhanced ultrasonography.  Scand J Gastroenterol. 2007;  42 652-662
• 31 Schuessler G, Fellbaum C, Fauth F et al. The infammatory pseudotumour – an unusual liver tumour.  Ultraschall in Med. 2006;  27 273-279
• 32 Ignee A, Piscaglia F, Ott M et al. A benign tumour of the liver mimicking malignant liver disease--cholangiocellular adenoma.  Scand J Gastroenterol. 2009;  44 633-636
• 33 Ignee A, Weiper D, Schuessler G et al. Sonographic characterisation of hepatocellular carcinoma at time of diagnosis.  Z Gastroenterol. 2005;  43 289-294
• 34 Piscaglia F, Gianstefani A, Ravaioli M et al. Criteria for diagnosing benign portal vein thrombosis in the assessment of patients with cirrhosis and hepatocellular carcinoma for liver transplantation.  Liver Transpl. 2010;  16 658-667
• 35 Piscaglia F, Leoni S, Cabibbo G et al. Cost analysis of recall strategies for non-invasive diagnosis of small hepatocellular carcinoma.  Dig Liver Dis. 2010;  42 729-734
• 36 Lencioni R, Piscaglia F, Bolondi L. Contrast-enhanced ultrasound in the diagnosis of hepatocellular carcinoma.  J Hepatol. 2008;  48 848-857
• 37 Dietrich C F, Schreiber-Dietrich D, Schuessler G et al. Contrast enhanced ultrasound of the liver – state of the art.  Dtsch Med Wochenschr. 2007;  132 1225-1231
• 38 Trojan J, Hammerstingl R, Engels K et al. Contrast-enhanced ultrasound in the diagnosis of malignant mesenchymal liver tumors.  J Clin Ultrasound. 2010;  38 227-231
• 39 Ignee A, Baum U, Schuessler G et al. Contrast-enhanced ultrasound-guided percutaneous cholangiography and cholangiodrainage (CEUS-PTCD).  Endoscopy. 2009;  41 725-726