Echo enhanced ultrasound: a new valid initial imaging approach for severe acute pancreatitis

This prospective study aimed to compare the accuracy of echo enhanced ultrasound with spiral computed tomography (CT) in assessing acute pancreatitis and to explore the correlation between ultrasound findings and clinical outcome.

Thirty one patients (24 men and 7 women, median age 39 years, range 19-67 years) with acute pancreatitis were investigated by contrast enhanced CT and echo enhanced ultrasound within 72 hours after admission. Echo enhanced ultrasound (with intravenous injection of 2.4 ml SonoVue, pulse inversion technique, mechanical index 0.1 to 0.2, Siemens Elegra) was performed following conventional ultrasound. Balthazar's grading system was used to measure CT and ultrasound severity indices (CTSI and USSI). Correlations between CTSI and USSI and between USSI and clinical parameters were tested by Spearman's rank correlation coefficient.

A strong correlation was demonstrated between CTSI and USSI (r = 0.807, p<0.01). Ultrasound correlated with the following: the Ranson score (r = 0.401, p<0.05), C-reactive protein levels 48 hours after admission (r = 0.536, p<0.01), duration of hospitalisation (r = 0.422, p<0.05), and clinical outcome regarding morbidity, including local and systemic complications (r = 0.363, p<0.05). Based on CT findings as the gold standard, sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound for detecting severe acute pancreatitis based on imaging criteria (Balthazar score D or E and/or presence of hypoperfusion compatible with necrosis and/or SI>/=3) were, respectively, 82% (95% CI 61 to 93), 89% (95% CI 57 to 98), 95% (95% CI 75 to 99), and 67% (95% CI 39 to 86).

Echo enhanced ultrasound produces excellent results in the staging of acute pancreatitis severity. The procedure is cheaper and has fewer contraindications than CT. Further multicentre studies need to be performed before including the method in the diagnostic algorithm of patients with acute pancreatitis.