Portal phase alone is equivalent to multiphasic phase for CT diagnosis of acute non-traumatic pains in an emergency context.

OBJECTIVES: To evaluate radiological diagnosis concordance between a simplified and a multiphasic computed tomography (MCT) protocol for patients presenting acute non-traumatic abdominal pains (ANTAE).
METHODS: During five consecutive months, all patients admitted in an emergency department for ANTAE were retrospectively included if they underwent MCT, including at least pre-contrast phase, late arterial phase (LAP), and portal venous phase (PVP). Clinical cases of suspected hemorrhagic conditions were secondarily excluded. For the study, two image sets, pre-contrast phase + LAP + PVP ± late phase called S1 and PVP alone called S2, were reviewed independently to give the most appropriate diagnosis with 5-point confidence scale. Diagnosis concordance and radiation dose were compared for each set of protocol by chi-square test. Linear mixed model was used to assess changes of diagnostic confidence and radiation dose.
RESULTS: All in all, 196 patients were included. The kappa coefficient between S1 and S2 was excellent (98.5%, CI95% 95.6-99.7). Three errors due to an inappropriate protocol were observed (1.5%; CI95% = - 0.2 to 3.2%), 2 related to biliary tract obstruction causes and one due to gastric bleeding not suspected on clinical data. S2 was associated with a 61% decrease of the radiation dose (p = 0.01) with a mild decrease of the confidence scale (4.54 ± 0.05 versus 4.74 ± 0.03, p = 0.001).
CONCLUSION: Using PVP-CT alone or MCT is equivalent for the diagnosis of ANTAE if suspected acute hemorrhages are excluded. A simplified CT protocol is associated with a dose decrease of 61%.