Chronic pancreatitis: Pain and computed tomography/magnetic resonance imaging findings

Table 1 Patterns and classification of pain[10,16,17]

Pattern	Implication
A	Usually, pain-free with episodes of mild to moderate pain
B	Constant mild to moderate pain
C	Usually, pain-free with episodes of severe pain
D	Constant mild to moderate pain plus episodes of severe pain
E	Constant severe pain
Frequency of pain
Intermittent	Pain pattern A or C
Constant	Pain pattern B, D or E
Severity of pain
Mild-moderate	Pain pattern A or B
Severe	Pain pattern C, D or E

Table 2 Cambridge classification diagnostic criteria in chronic pancreatitis[27]

To evaluate chronic pancreatitis from the aspects of pancreatic parenchyma, pancreatic duct morphology, local changes, and so on by CT and US
Normal	Quality study visualising the whole gland without abnormal features
Equivocal	One sign only	Main duct enlarged (< 4 mm)
		Gland enlarged (up to 2 × normal)
		Cavities (< 10 mm)
		Irregular ducts
		Focal acute pancreatitis
		Parenchymal heterogeneity
Mild changes	Two or more signs	Duct wall echoes increased
Moderate changes		Irregular head/body contour
Marked changes	As above, and with one or more of: Large cavities (> 10 mm), gross gland enlargement (> 2 × normal), intraductal filling defects or calculi, duct obstruction, structure or gross irregularity, contiguous organ invasion

CT: Computed tomography; US: Ultrasound.

Table 3 M-Annheim diagnostic criteria of definite chronic pancreatitis[14]

At least one of the following four items should be met
Pancreatic calcifications
Moderate or marked ductal lesions (according to the Cambridge classification)
Marked and persistent exocrine insufficiency defined as pancreatic steatorrhea markedly reduced by enzyme supplementation
Typical histology of an adequate histological specimen

Table 4 The relationship between pain and imaging findings of chronic pancreatitis

Ref.	n	Research type	Imaging techniques	Results
Bornman et al[34], 1980	47	A prospective study	ERCP	The incidence of pancreatic duct obstruction or stricture in patients with painless and painful CP was comparable, indicating that the morphological changes of the pancreatic duct are not related to the occurrence of pain
Jensen et al[35], 1984	101	A comparative study	ERP	There was no correlation between the degree of pain in CP (no pain, light pain, moderate pain, severe pain) and the dilatation of the main pancreatic duct measured by ERP (the diameter of the main pancreatic duct in the pancreatic body exceeding 5 mm was defined as dilatation)
Malfertheiner et al [37], 1987	64	A prospective study	CT/ERP	There was a poor correlation between the severity of pain and abdominal imaging features in CP patients, but it was also found that patients with large pancreatic cysts were most often associated with severe pain (62%), while enlargement of pancreatic gland, small cysts, and duct dilatation were roughly the same as different degrees of pain. Most (89%) patients with calcification still had pain and some of them (39%) showed severe pain
Morgan et al[36], 2003	25	A retrospective study	ERCP	There was a poor correlation between the morphological changes of the main pancreatic duct (whether the duct was dilated or blocked) and pain
Mullady et al[16], 2011	414	A prospective cohort study	CT/ERCP	The duration of disease in CP patients was not related to either the frequency of pain (intermittent vs constant) or the severity of pain (mild, moderate or severe)
Bahuva et al[18], 2013	54	A retrospective study	CT/MRCP/EUS	The presence or absence of visceral pain is not significantly related to the severity of CP structural changes, whether the structural changes are severe, mild, or absent
Frøkjær et al[39], 2013	40	A controlled study	MRCP/DWI	The pancreatic pathological imaging findings of the fibrotic changes as well as atrophy and ductal pathology were not associated with pain
Wilcox et al[17], 2015	518	A retrospective study	CT/MRI/MRCP/EUS/ERCP	CP patients with different pain patterns, temporal nature of pain (no pain, intermittent, constant) or pain severity (no pain, mild-moderate, severe) were very similar in the distribution of imaging findings
Madzak et al[2], 2017	82	A prospective cohort study	s-MRI	There was no correlation between pancreatic parenchyma and ductal changes, pain severity, and pain interference scores

CT: Computed tomography; MRCP: Magnetic resonance cholangiopancreatography; EUS: Endoscopic ultrasound; ERP: Endoscopic retrograde pancreatography; ERCP: Endoscopic retrograde cholangio-pancreatography; DWI: Diffusion-weighted imaging; MRI: Magnetic resonance imaging; s-MRI: Secretin-stimulated magnetic resonance imaging; CP: Chronic pancreatitis.