Renal and perirenal space involvement in acute pancreatitis:: spiral CT findings

Background: This study was conducted to estimate the prevalence and morphologic computed tomographic (CT) features of renal and perirenal space abnormalities in acute pancreatitis in correlation with the severity of pancreatitis. Methods: One hundred fifty-nine contrast-enhanced CT scans of 100 consecutive patients with acute pancreatitis were retrospectively and independently reviewed by three observers. All CT images were obtained using contrast-enhanced helical CT (collimation width = 5 mm, table increment = 7 mm/s, reconstruction interval = 5 mm, scan delay time = 30-50 s). Additional maximized images (field of view = 260 mm) of the perirenal space were available for review. All CT scans were scored with the CT Severity Score Index: pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the severity scope and the presence of renal and perirenal involvement was calculated. Correlation between the prevalence of complications and the degree of pancreatitis was estimated. Results: CT scans were graded as mild (n = 59), moderate (n = 82), and severe (n = 18). Abnormalities detected included perirenal stranding (n = 37 patients, 26 bilateral), perirenal fluid collections (n = 10 patients, one bilateral), ureteral encasement (n = 2 patients), renal vein thrombosis (n = 1 patient), and renal parenchymal abnormalities (n = 1 patient). The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of abnormalities was 75.5-79.2% and 59.8-100%, respectively, Except for stranding of the perirenal fat, no statistically significant differences between the presence of abnormalities and the severity of pancreatitis (moderate or severe) was observed with Fisher's exact test. Also, no preferential left-sided localization of complications was observed. Conclusions: The incidence of renal and perirenal complications from acute pancreatitis is higher than previously estimated (7%). We found no significant correlation between the prevalence of major complications and the severity of pancreatitis. These findings are important because these complications may have an impact on therapeutic strategy and can affect prognosis.