Key Imaging Features and CT Criteria
The etiology of chronic pancreatitis (CP) is assessed using the TIGAR-O clinical system. Basic imaging changes boil down to pathology of the parenchyma and ductal system.
Ultrasound (B-mode) reveals heterogeneity of the parenchyma and dilation of the main pancreatic duct (MPD) exceeding 2.5 mm. To make a highly specific diagnosis by CT, it is necessary to identify at least 3 out of 4 signs:
- Parenchymal calcifications.
- Intraductal calculi (may cause bile duct dilation).
- Parenchymal atrophy.
- Cystic lesions.
Gland size varies widely: from diffuse enlargement to marked atrophy (especially of the tail).
Differential Diagnosis with Cancer
In approximately 20% of patients, the disease presents as a focal pseudotumor. On CT and MRI, focal CP has low density and shows poor contrast enhancement, making it visually indistinguishable from adenocarcinoma.
The key differential criterion is the duct-penetrating sign (duct penetrating sign). In focal inflammation, the main duct passes straight through the mass without complete cutoff. In marked fibrosing cancer, the duct is completely obstructed.
For detailed and precise diagnosis, the following are used:
- Secretin-enhanced MRCP: secretin dilates the duct within the inflammatory mass (in cancer, the stenotic segment does not respond).
- Gadolinium-enhanced MRI with DWI: for targeted assessment of areas with sharp changes in duct caliber.
- CEUS (Contrast-Enhanced Ultrasound): homogeneous contrast enhancement helps rule out a tumor.
Malignant growth (T4) is clearly indicated by infiltration of major vessels (celiac trunk, mesenteric arteries), which is uncharacteristic of isolated pancreatitis.
Specific Forms of Pancreatitis
Paraduodenal pancreatitis (groove pancreatitis) affects the area between the duodenum and the pancreatic head. Solid (type 1) and cystic (type 2) variants are distinguished.
- Imaging (CT/MRI) shows a lamellar hypodense mass with poor contrast enhancement.
- MRCP reveals pathognomonic cystic changes within the structure of this mass.
- Clinical Pitfall: the solid type is frequently misdiagnosed as cancer prior to surgery.
Autoimmune pancreatitis (AIP) occurs in patients without cholelithiasis and a history of alcohol abuse, and is often accompanied by elevated serum IgG4 levels. The most common form on imaging is the diffuse form (about 70% of cases), characterized by diffuse glandular enlargement and uniform narrowing of the pancreatic duct.
Comparison of imaging modalities
According to meta-analyses, all cross-sectional imaging modalities have comparable high accuracy in initial diagnosis.
- CT and MRI: non-invasive, preferred for detecting lesions, calcifications, and atrophy.
- MRCP and ERCP: provide detailed visualization of ducts, strictures, and protein plugs. However, ERCP is invasive and fails to visualize the entire duct in cases of severe strictures.
- EUS (Endoscopic Ultrasound): indispensable for evaluating early structural changes and performing targeted biopsy, especially when CT or MRI yields inconclusive results.
Briefly: answers to topical questions
What specific early structural changes of the parenchyma and ducts are detected on endoscopic ultrasound (EUS) according to the Rosemont criteria?
Endoscopic ultrasound according to the Rosemont criteria reveals 6 parenchymal and 5 ductal features.
Parenchymal changes:
- Hyperechoic foci with shadowing — major criterion A.
- Honeycombing lobularity — major criterion B.
- Lobularity without honeycombing — minor criterion.
- Hyperechoic foci without shadowing — minor criterion.
- Hyperechoic strands — minor criterion.
- Cysts — minor criterion.
Ductal changes:
- Presence of calculi — major criterion A.
- MPD dilation — minor criterion.
- Side branch dilation — minor criterion.
- MPD irregularity — minor criterion.
- Hyperechoic duct walls — minor criterion.
What stages is chronic pancreatitis divided into according to the Cambridge classification of imaging?
The Cambridge classification divides chronic pancreatitis into five stages of severity.
| Grade | Changes |
|---|---|
| Normal | Normal gland size and shape, homogeneous parenchyma |
| Equivocal | Single feature: duct dilation 2–4 mm, slight enlargement, heterogeneity |
| Mild | Two or more features from the equivocal stage |
| Moderately severe | Small cavities, duct irregularity, increased wall echogenicity, irregular contours |
| Severe | Large cavities, marked enlargement, filling defects, obstruction, involvement of adjacent organs |
What extrapancreatic complications of chronic pancreatitis, besides vascular ones, are visualized on abdominal CT?
On abdominal CT, in addition to vascular complications, the following extrapancreatic or contiguous changes may be visualized in chronic pancreatitis:
- Peripancreatic cysts — listed among reliable CT signs of chronic pancreatitis.
- Peripancreatic fascia thickening — also classified as a reliable CT sign.
- Involvement of adjacent organs — included in the severe grade criteria of the Cambridge CT/ultrasound classification.
- Secondary common bile duct dilatation — may occur with intraductal pancreatic calculi.
For the CT diagnosis of chronic pancreatitis, remember the "3 out of 4" rule: parenchymal calcifications, ductal calcifications, atrophy, cysts.
Class and exam questions
Which MRI sign most accurately differentiates focal pancreatitis from carcinoma?
"Penetrating duct" sign. In pancreatitis, the main duct passes through the mass, whereas in carcinoma, it abruptly terminates due to complete obstruction.
What are the characteristic imaging features of autoimmune pancreatitis?
Characterized by diffuse (less commonly focal) enlargement of the gland combined with narrowing of the pancreatic duct, without the formation of typical calcifications.
What vascular complications are characteristic of long-standing CP?
Most common are thromboses of the splenic, mesenteric, or portal veins with the development of collaterals, as well as arterial pseudoaneurysms.
What else to study on this topic
- TIGAR-O classification in the assessment of CP etiology
- The role of EUS with biopsy in differential diagnosis
- Subtypes of paraduodenal pancreatitis (1A, 1B, 2A, 2B)
- Contrast-enhanced ultrasound (CEUS) to rule out tumors
- Secretin-enhanced MRCP technique
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete guide on "Imaging Diagnosis of Chronic Pancreatitis" and 2,199 other pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the section "Diagnostic Radiology of the Abdominal Organs"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.