ARFI Elastography of the Spleen is Inferior to Liver Elastography for the Detection of Portal Hypertension

Zusammenfassung

Ziel: Bislang war die transiente Elastografie auf die Leber beschränkt. Acoustic Radiation Force Impulse Imaging (ARFI) ist eine neue Technologie, welche die Elastografie verschiedener Gewebe erlaubt. Wir präsentieren hier erstmals Daten zur Elastografie der Milz und deren Einflussfaktoren, insbesondere die portale Hypertension. Material und Methoden: Die Elastografie von Milz und Leber wurde mittels ARFI bei 30 Patienten mit Lebererkrankungen und portaler Hypertension, 70 Patienten mit Lebererkrankungen ohne portale Hypertension und 25 gesunden Kontrollen durchgeführt. Ergebnisse: Die ARFI-Elastografie der Milz war durchführbar bei 99 % der Patienten und valide bei 78 %. Die mittlere Ausbreitungsgeschwindigkeit innerhalb der Milz lag bei 2,95 ± 0,60 m/s, also viel höher als in normaler Leber (< 1,10 m/s). Die Milzsteifigkeit war höher bei Patienten mit portaler Hypertension (p < 0,008), aber korrelierte nicht mit der Milzgröße. Die Steifigkeit der Milz nahm mit dem Alter und der Lebersteifigkeit zu (beide p < 0,0001), was sich in der Multivarianzanalyse bestätigte (R2 = 0,19, p < 0,01). In der ROC-Analyse war die Milz-Elastografie der Leber-Elastografie bei der Erkennung der portalen Hypertension unterlegen (AUC 0,68 vs. 0,90). Schlussfolgerung: Die neue Methode der ARFI-Elastografie erlaubt eine akkurate Messung der Milzsteifigkeit. Die Steifigkeit der normalen Milz ist deutlich höher als die der Leber und nimmt mit dem Alter zu. Allerdings ist die Milz-Elastografie der Leber-Elastografie in der Detektion von portaler Hypertension unterlegen.

Abstract

Purpose: To date, the use of transient elastography has been limited to the liver. Acoustic radiation force impulse imaging (ARFI) is a new technology offering elastography of different tissues. Here, we present initial spleen elastography data and evaluate its influencing factors, especially portal hypertension. Materials and Methods: Elastography of the spleen and liver using the ARFI method was performed in 30 patients with portal hypertension, 70 patients with chronic liver disease without portal hypertension and 25 healthy controls. Results: ARFI elastography of the spleen was feasible in 99 % of patients and valid in 78 %. The mean propagation velocity inside the spleen was 2.95 ± 0.60 m/sec, thus much higher than in the normal liver (< 1.10 m/sec). Spleen stiffness was higher in the patients with portal hypertension (p < 0.008) but did not correlate to spleen size. Spleen stiffness increased with patient age and liver stiffness (both p < 0.0001) as confirmed by multivariate analysis (R2 = 0.19, p < 0.01). In ROC analysis, spleen elastography was inferior to liver elastography for the detection of portal hypertension (area under the curve 0.68 vs. 0.90). Conclusion: The new ARFI method allows accurate elastography of the spleen. The stiffness of the normal spleen is much higher than that of the normal liver and increases with age. However, spleen elastography is inferior to liver elastography for the detection of portal hypertension.

spleen - ultrasound - hemodynamics/flow dynamics - vascular

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