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

Background: This study was conducted to estimate the prevalence and morphol ogic computed tomographic (CT) features of renal and perirenal space abnorm alities in acute pancreatitis in correlation with the severity of pancreati tis. Methods: One hundred fifty-nine contrast-enhanced CT scans of 100 consecuti ve patients with acute pancreatitis were retrospectively and independently reviewed by three observers. All CT images were obtained using contrast-enh anced helical CT (collimation width = 5 mm, table increment = 7 mm/s, recon struction 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: pancreat itis 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 pre sence of renal and perirenal involvement was calculated. Correlation betwee n the prevalence of complications and the degree of pancreatitis was estima ted. Results: CT scans were graded as mild (n = 59), moderate (n = 82), and seve re (n = 18). Abnormalities detected included perirenal stranding (n = 37 pa tients, 26 bilateral), perirenal fluid collections (n = 10 patients, one bi lateral), ureteral encasement (n = 2 patients), renal vein thrombosis (n = 1 patient), and renal parenchymal abnormalities (n = 1 patient). The intero bserver agreement range for scoring the degree of pancreatitis and the over all presence of abnormalities was 75.5-79.2% and 59.8-100%, respectively, E xcept for stranding of the perirenal fat, no statistically significant diff erences between the presence of abnormalities and the severity of pancreati tis (moderate or severe) was observed with Fisher's exact test. Also, no pr eferential 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 signific ant correlation between the prevalence of major complications and the sever ity of pancreatitis. These findings are important because these complicatio ns may have an impact on therapeutic strategy and can affect prognosis.