Contrast-enhanced endoscopic ultrasound with low mechanical index: A new technique

Aim: Recent advances in technology have supported the development of new endoscopic ultrasound systems making it possible to use low MI contrast-enhanced imaging techniques (wide band harmonic imaging done with endoscopic ultrasound is currently at a preliminary stage). We now report on the first use of contrast-enhanced, low mechanical index, real-time endoscopic ultrasound (CELMI-EUS) in six patients using prototype technology. Materials and Methods: CELMI-EUS was performed using an electronic echo-endoscope HITACHI/Pentax EG-3830UT and adapted dynamic contrast harmonic wide-band pulsed inversion software with low mechanical index (MI = 0.09 - 0.25) before and up to 180 seconds after injection of SonoVue (R) (4.8 mL) in six patients. Results: Adequate visualisation of the arterial and portal venous phases was achieved in all patients. The pancreas and liver were studied thereafter. In contrast to the satisfactory visualisation of these vessels, enhancement of the left liver lobe was sufficient only in 4 patients. In the remaining 2 patients with liver cirrhosis, the enhancement was less pronounced in contrast to the strong enhancement of the hepatic artery and portal vein. Conclusion: Recent advances in technology have supported the development of new echo-endoscopic systems making it possible to use real-time, low mechanical index, contrast-enhanced imaging techniques with endoscopic ultrasound. We have preliminarily shown that arterial, portal venous and parenchymal contrast enhancement is possible.