Imaging for Pancreatitis and Pancreatic Cysts

Acute Pancreatitis

The American College of Radiology recommends that initial imaging is NOT routinely recommended in the first week unless there is clinical deterioration or uncertainty in diagnosis, and when imaging is needed, contrast-enhanced CT with pancreas protocol is the modality of choice 1, 2
Early CT (first 4 days) is generally NOT indicated because the full extent of necrosis takes at least 4 days to develop, and early scanning may underestimate disease severity 1, 2, 3
CT is indicated when clinical impression suggests severe disease with organ failure, APACHE II score >8, Glasgow score ≥3, or CRP >150 mg/L at 24-48 hours 1, 2, 3
The CT severity index for staging should be used when imaging is performed, with a mortality correlation of 0-3 (3%), 4-6 (6%), 7-10 (17%) 1, 2, 3

The American College of Radiology recommends MRI abdomen without and with IV contrast with MRCP as the preferred initial imaging modality for incidentally detected pancreatic cysts, with no routine laboratory testing required 5
MRI with MRCP achieves 96.8% sensitivity and 90.8% specificity for distinguishing IPMN from other cystic lesions, compared to CT's 80.6% sensitivity and 86.4% specificity 6, 7
Cysts ≤2.5 cm: MRI with MRCP is usually appropriate, while cysts >2.5 cm without high-risk features: MRI with MRCP is usually appropriate, and cysts >2.5 cm with high-risk stigmata or worrisome features: both endoscopic ultrasound (EUS) and MRI with MRCP are usually appropriate as complementary procedures 5
The American College of Radiology does not recommend routine laboratory tests, including serum tumor markers, for initial characterization of small, asymptomatic pancreatic cysts 6
EUS-FNA is complementary to MRCP, not a replacement, and should be considered for cysts ≥3 cm even without other concerning features, and provides tissue diagnosis when MRCP shows worrisome features or high-risk stigmata 7
Follow-up imaging should be performed with either CT or MRI, with modality concordance between baseline and follow-up facilitating comparison, and the risk of malignant transformation is approximately 0.24% per year 5, 7