Comparison of Acoustic Radiation Force Impulse (ARFI) Elastography Measurements with the 4C1 Transducer to the 6C1HD Transducer: A Phantom and Patient Study

Abstract

Purpose: The aim of this study was to evaluate whether acoustic radiation force impulse (ARFI) elastography done with the 4C1 probe yields comparable results to the recently introduced 6C1HD probe.

Materials and Methods: Measurements with the 4C1 and 6C1HD probes (Acuson S2000) were performed and compared in four different inclusions of an elasticity phantom model (QA049 CIRS) as well as in the liver of healthy individuals and patients with liver cirrhosis.

Results: Measurements with the 6C1HD probe were slightly higher in all phantom inclusions (8, 14, 45, 80kPA) with a mean of 1.48 m/s (95 %-CI; 1.47 – 1.49), 2.18 m/s (95 %-CI; 2.17 – 2.19), 3.61 m/s (95 %-CI; 3.57 – 3.64) and 4.34 m/s (95 %-CI; 4.29 – 4.39) compared to the 4C1 transducer with 1.46 m/s (95 %-CI; 1.45 – 1.47), 2.15 m/s (95 %-CI; 2.14 – 2.16), 3.39 m/s (95 %-CI; 3.37 – 3.41) and 3.98 m/s (95 %-CI; 3.75 – 4.21), respectively (p = 0.04, p < 0.01, p < 0.01, p < 0.01). Cirrhotic patients (n = 40) had a higher mean shear wave speed with 3.00 m/s (95 %-CI; 2.80 – 3.21) with the 6C1HD transducer compared to 2.81 m/s (95 %-CI; 2.64 – 2.99) with the 4C1 transducer (p = 0.03). Healthy individuals (n = 20) had a mean shear wave speed of 1.12 m/s (95 %-CI; 1.06 – 1.17) with the 6C1HD probe and 1.12 m/s (95 %-CI; 1.05 – 1.19) with the 4C1 probe (p = 0.96).

Conclusion: ARFI values assessed with a 6C1HD transducer are slightly higher than measurements with a 4C1 transducer in an ARFI phantom and in patients with liver cirrhosis. As the difference is small, current cut-off values keep their usefulness but should be interpreted with caution if measurements are close to the cut-off.

Zusammenfassung

Ziel: Ziel dieser Studie war es zu überprüfen, ob die acoustic radiation force impulse (ARFI)-Elastografie mit dem 4C1-Schallkopf vergleichbare Werte zu dem seit kurzem erhältlichen 6C1HD-Schallkopf liefert.

Material und Methoden: Messungen mit dem 4C1- und dem 6C1HD-Schallkopf (Acuson S2000) wurden an vier verschiedenen Inklusionen eines Elastometriephantoms (QA049 CIRS), an der Leber von gesunden Probanden und von Patienten mit Leberzirrhose durchgeführt und die Messwerte miteinander verglichen.

Ergebnisse: Messungen mit dem 6C1HD-Schallkopf an den vier Inklusionen des Phantoms (8–, 14–, 45, 80kPa) lieferten etwas höhere Werte mit durchschnittlich jeweils 1,48 m/s (95 %-CI;1,47 – 1,49), 2,18 m/s (95 %-CI; 2,17 – 2,19), 3,61 m/s (95 %-CI; 3,57 – 3,64) und 4,34 m/s (95 %-CI; 4,29 – 4,39) verglichen mit dem 4C1 – Schallkopf mit Werten von jeweils 1,46 m/s (95 %-CI; 1,45 – 1,47), 2,15 m/s (95 %-CI; 2,14 – 2,16), 3,39 m/s (95 %-CI; 3,37 – 3,41) und 3,98 m/s (95 %-CI; 3,75 – 4,21) mit folgenden korrespondierenden p-Werten: p = 0,04; p < 0,01;p < 0,01; p < 0,01. Die Scherwellengeschwindigkeit zirrhotischer Patienten (n = 40) zeigte sich mit dem 6C1HD-Schallkopf durchschnittlich höher mit 3,00 m/s (95 %-Cl, 2,80 – 3,21) verglichen mit dem 4C1-Schallkopf mit 2,81 m/s (95 %-Cl, 2,64 – 2,99; p = 0,03). Gesunde Probanden (n = 20) hatten eine durchschnittliche Scherwellengeschwindigkeit von 1,12 m/s (95 %-Cl, 1,06 – 1,17) mit dem 6C1HD-Schallkopf und 1,12 m/s (95 %-Cl, 1,05 – 1,19) mit dem 4C1-Schallkopf (p = 0,96).

Schlussfolgerung: ARFI-Messungen am Phantom und bei Patienten mit Leberzirrhose ergaben mit dem 6C1HD-Schallkopf etwas höhere Werte als Messungen mit dem 4C1-Schallkopf. Da die Werte nur gering differieren, behalten die aktuellen Cut-off-Werte ihre Gültigkeit, sollten jedoch bei Messwerten nahe am Cut off mit Vorsicht interpretiert werden.

Key words

ARFI - liver elastography - transducers - probes

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