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Early pancreatic tissue necrosis diagnoses by perfusion CT : the study K-Pa

Acute pancreatitis (AP) is associated with high mortality and morbidity rates in case of necrotic forms. Risk assessment should be early performed to stratify patients into higher- and lower-risk of severe form to assist triage. In severe pancreatitis, capillary permeability increases, thereby contributing to capillary leakage which explains organ failures and or tissue necrosis. The aim of this study was therefore to evaluate pancreatic permeability by perfusion CT (pCT).

Methods: From March 2018 to November 2018, patients with suspected AP and who underwent CT at admission were prospectively included. AP cases were classified according to the revised Atlanta classification. A permeability parameter, called k-trans, was measured from pCT in 3 pancreatic areas (normal parenchyma zone, defined by an area of normal CT pattern, pathological zone, defined as an area of parenchymal enlargement and or lack of enhancement and an intermediary zone defined by an area between normal and pathological areas) by to two observers. K-trans values in necrotic and interstitial forms for each zone were compared.

To estimate reproducibility of the measure, inter-observer and intra-observer agreement was evaluated by a Bland and Altman test. Results: 15 patients were enrolled (mean age 45.50 years old, +/-17.70). Four acute pancreatitis were necrotic, and 11 interstitial. Mean k-trans in pathologic zone of necrotic forms was significantly lower (mean=0.08) than in interstitial (mean=0.53), p= 0.0003. In both forms, k-trans values were significantly lower in pathologic zones than in intermediary and normal zones. Intra-observer reproducibility was good. Inter-observer reproducibility was acceptable, one bias was reported, close to zero (-0.052) with limited statistic difference.

Conclusion: K-trans parameter, a well-known marker of tissue permeability, can be estimated by pCT. This parameter seems to be linked to local necrosis and could be used as a discriminant mean to diagnose necrotic from interstitial types of AP in the early phase of disease.

Keywords : acute pancreatitis, perfusion computed tomography, permeability.