This case-control study included 16 patients with acute pancreatitis referred from the emergency department of a university hospital, and 16 patients in a control group who were in the radiodiagnosis department for MRI examination. The cases were age- and sex-matched.
Inclusion criteria
Exclusion criteria
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Patients known to have contraindications for MRI, e.g., an implanted magnetic device, pacemakers, or claustrophobia.
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Patients in a bad general condition needing life support.
Procedure
At the MRI unit, both groups were subject to: the following
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A full history-taking and clinical examination.
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An MRI examination, carried out at the MRI unit at the university hospital.
Patient preparation
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Prior to MRI examination, informed consent was obtained from the patient or the patient’s parents or caregivers.
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No previous preparations were required.
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Detailed explanation of the imaging procedure was provided.
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The patient was positioned supine on the MRI table.
Method of MRI examination
The MRI study was performed using a 1.5T machine (Achieva, Philips medical system, Eindhoven, Netherlands). A standard body coil was used for both conventional imaging and diffusion-weighted imaging.
Examination protocol
Morphological sequences were performed in multiple projections, including the following:
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1.
Axial, sagittal, and coronal T2-weighted turbo spin echo (T2 W TSE) images.
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2.
Axial and sagittal (STIR) images.
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3.
Axial T1-weighted turbo spin echo (T1W TSE) images.
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4.
Axial DWI using a multi-slice single-shot echo-planar imaging (EPI) sequence with different b values.
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5.
ADC maps in grayscale were automatically produced, with the applied mono-exponential decay model including all b values (0, 200, and 800).
Duration of the examination
The MRI took about 15–20 min.
Image analysis
In the control group, mean ADC values from each sector (head, body, and tail) with a minimum area of 80 mm2 were calculated for each patient directly from the ADC map data on the workstation. In the acute pancreatitis group, the ADC from a single (region of interest) ROI with the highest signal intensity in the head, body, or tail with a minimum area of 90 mm2 was measured. Areas with pancreatic fluid, pancreatic duct, pseudocysts, cystic lesions, and artifacts were excluded from the region of interest.
The images were analyzed by a senior radiologist who has 4 years of body MRI experience and who was not blinded to clinical data.
The diagnosis was confirmed by the clinical picture and the laboratory tests.
Statistical analysis
Data were coded using IBM SPSS (version 23). The quantitative data were expressed as mean, SD, and ranges when their distribution found parametric. The qualitative data were expressed as numbers and percentages.
The comparison between the quantitative data and parametric distribution of the two groups was done using the independent t test; the comparison between groups regarding qualitative data was done by using the chi-square test; and the comparison between more than two groups was done using one-way ANOVA.
Spearman’s rank correlation coefficient was used to assess the correlation between two quantitative parameters in the same group.
A receiver operating characteristic (ROC) curve was used in the quantitative form to determine sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the cut-off point of mean ADC. The confidence interval was set to 95% and the margin of error accepted was set to 5%. The significance of p values was established as follows:
p value > 0.05: non-significant (NS)
p value < 0.05: significant (S)
p value < 0.01: highly significant (HS)