From the Guidelines
Contrast-enhanced CT scan is the preferred imaging modality for diagnosing and assessing acute pancreatitis, and it should be performed 48-72 hours after symptom onset to accurately evaluate pancreatic necrosis and complications. According to the 2019 WSES guidelines for the management of severe acute pancreatitis 1, the extension of the (peri)pancreatic necrosis may be detected with a contrast-enhanced CT (CECT) after 72 h from the onset of AP.
Key Points for Imaging in Acute Pancreatitis
- Initial imaging is not necessary for mild cases with typical clinical presentation, elevated lipase/amylase, and rapid improvement with conservative management 1.
- CT imaging is indicated when the diagnosis is uncertain, in severe cases, or when complications are suspected 1.
- MRI can be used as an alternative when CT is contraindicated, offering better soft tissue contrast and detection of biliary stones without radiation exposure 1.
- Ultrasound has limited utility for visualizing the pancreas due to overlying bowel gas but is useful for evaluating biliary causes of pancreatitis, and almost all the AP guidelines worldwide recommend performing US on admission or in the first 48 h 1.
CT Severity Index
The CT severity index, established by Balthazar et al. 1, grades pancreatitis based on the degree of inflammation, presence of fluid collections, and extent of necrosis, with a higher score associated with increased morbidity and mortality.
- The CT severity index is calculated by adding the grade score (0–4) and necrosis score (0–6) 1.
- A higher CT severity index score is associated with increased morbidity and mortality, with scores of 7–10 having a morbidity of 92% and mortality of 17% 1.
Follow-up Imaging
Follow-up imaging is recommended when clinical deterioration occurs or to monitor known complications, typically 7-10 days after onset for patients with severe disease to assess for necrosis development 1. CECT is the imaging modality of choice for diagnosis, staging, and detection of complications of acute pancreatitis, and has major roles in the evaluation of patients with known or suspected AP: (i) diagnosis, (ii) staging of the severity, and (iii) detection of complications, particularly the identification and quantification of (peri)pancreatic necrosis 1.
From the Research
Imaging Modalities for Acute Pancreatitis
- Computed Tomography (CT) is the primary initial imaging modality for characterizing acute pancreatitis 2
- Contrast-enhanced CT (CECT) is useful for monitoring disease progression and assessing intraabdominal complications in patients with severe acute pancreatitis 3
- Ultrasound is the first-line imaging modality for confirming the diagnosis of acute pancreatitis and ruling out other causes of acute abdomen, but it has limitations in the acute clinical setting 4
- Magnetic Resonance Imaging (MRI) has earned an important role in the diagnosis of acute pancreatitis, especially for patients with iodine allergies, characterizing collections, and assessing an abnormal or disconnected pancreatic duct 4, 5
Classification and Complications of Acute Pancreatitis
- The Atlanta classification of acute pancreatitis divides patients into mild and severe groups based on clinical and biochemical criteria 4
- The revised Atlanta classification system emphasizes the importance of extrapancreatic fat necrosis and walled-off necrosis in acute pancreatitis 6
- Imaging is recommended to confirm the clinical diagnosis, investigate the etiology, and grade the extent and severity of acute pancreatitis 4
- Common complications of acute pancreatitis include pancreatic necrosis, abscesses, and pseudocysts, which can be assessed using CT, MRI, or ultrasound 2, 5
Role of Imaging in Acute Pancreatitis
- Imaging plays a crucial role in the diagnosis, evaluation, and management of acute pancreatitis 5
- A practical image-rich guide can facilitate radiologists in writing a correct report and reinforce their role as a key member of a multidisciplinary team in treating patients with acute pancreatitis 5
- Recent advances in imaging acquisition and analytic techniques have improved the evaluation of acute pancreatitis, including the use of multiparametric magnetic resonance imaging (mpMRI) 6