Multi-detector-row Spiral CT Manifestations Of Acute Necrotizing Pancreatitis: Relationship Of Glandular Necrosis To Retroperitoneal Spreading And Clinical Disease Severity

Objectives(1) To describe the imaging manifestations of acute necrotizing pancreatitis (ANP) on multi-detector-row spiral CT (MDCT). (2)To investigate the relationships between pancreatic glandular necrosis, retroperitoneal inflammatory spreading and the clinical severity of ANP. (3) To evaluate the evolution of glandular necrosis of ANP in patients with repeated MDCT examinations.Materials and Methods90 patients diagnosed as ANP according to the clinical data, laboratory information and CT imaging findings were prospectively enrolled into this study. They all underwent standardized contrast-enhanced dual-phasic scanning of the whole abdomen using a 16-slice MDCT, the scan delay timesfor arterial and portal venous phases being 3 0-3 5 s and 70s respectively. Two senior abdominal radiologists interpreted all CT imaging data through consensus reading. Scoring of the extent of pancreatic glandular necrosis and Balthazar Grading based on retroperitoneal inflammatory spreading were done at the same time. For 44 patients who met the criteria of Ranson Scoring, both scoring by CT Severity Index (CTSI) and Ranson Criteria were also carried out. In 18 ANP patients who had repeated MDCT examinations, the morphological changes of glandular necrosis were carefully compared in before-and-after CT images. Chi-square test was applied for the statistical analysis of the relationships of glandular necrosis, retroperitoneal spreading, and the clinical severity of ANP.Results1. MDCT manifestations ANP. In 40 out of 90 patients, the glandular necrosis was less than 30%, in 23 the necrosis was between 30-50%, and in 27 the necrosis was more than 50%. Peripancreatic fat swelling and thickening of anterior renal fascia were observed in all cases of ANP; Peripancreatic and retroperitoneal phlegmonous fluid collection occurred in 78 patients (86.7%); 12 had fluid collection in lesser sac (13.3%); Thickening and swelling of posterior gastric wall in 71 (78.9%); Splenic infarction in 4 (4.4%); 35 patients had peritoneal effusion (38.9%) and 87 developed intestinal ileus (96.7%); 82 hadpleural effusion (91.1%).2. 12 patients were classified as Balthazar Grade C, 42 as Grade D and 36 as Grade E. There was a statistically significant positive correlation between the extent of pancreatic glandular necrosis and Balthazar Grades (p<0.05).3. In 44 ANP patients suitable for Ranson Scoring, 12 cases were Mild (27.3%), 23 cases Moderate (52.3%), 9 cases Severe (20.5%). Their CTSI Grading was as follows: Mild cases 0, Moderate cases 25 (56.8%), Severe cases 19 (43.2%). Correlation between the CTSI and the clinical severity of ANP was of statistical significance (p<0.05).4. MDCT depicted clearly the development and evolution of glandular necrosis in 18 ANP patients with repeated MDCT examinations (once in 10 cases, twice or more in 8 cases). Gradual absorption and shrinkage of necrosis was observed in 1 case (1 site); No significant changes in 3 cases (3 sites); Formation of 10 pseudocysts in 7 cases, with enlargement of 4 pseudocysts in 2 cases; Peripancreatic abscesses developed in 6 cases.ConclusionANP can demonstrate a series of imaging manifestations on MDCT, including pancreatic glandular necrosis and retroperitoneal spreading. To some extent, the degree of glandular necrosis and the extent of retroperitoneal spreading is positively correlated, and CTSI grading based on MDCT imaging features is also positively correlated with the clinical severity of ANP as reflected by Ranson Scoring. MDCT is also able to monitor the development and evolution of pancreatic glandular necrosis.