Suspected early or mild chronic pancreatitis: Enhancement patterns on gadolinium chelate dynamic MRI

Abstract

Purpose: To assess whether measuring the pattern of pancreatic enhancement on gadolinium chelate dynamic magnetic resonance imaging (MRI) is helpful for diagnosis of suspected early or mild chronic pancreatitis. Materials and Methods:In this retrospective study, 24 patients with suspected early or mild chronic pancreatitis, classified by imaging criteria of equivocal chronic pancreatitis (ultrasound, computed tomography [CT] or ERCP) grading, had dynamic MRI that included unenhanced, arterial dominant, early venous, and late venous phases of contrast enhancement. Twenty patients without pancreatic diseases also had the dynamic sequence as a control group. The signal intensity was measured at the pancreatic head, body, and tail on all phases, and for each, the signal intensity ratio (SIR, the signal intensity in postcontrast divided by that in precontrast) was calculated. Two radiologists independently reviewed the images of the patients with suspected early or mild chronic pancreatitis for pancreatic morphologic abnormalities without knowing the results of signal intensity measurements.Results: On unenhanced images, there was no significant difference of signal intensity between control and pancreatitis groups (P Ͻ 0.05). In the pancreatitis group, but not in the control group, the unenhanced signal intensity of the pancreatic head and body were significantly higher than that of the tail (P Ͻ 0.05). In the control group, the greatest enhancement (highest SIR) after injection was in the arterial phase (1.89 Ϯ 0.31), significantly higher than that in the early venous phase (1.68 Ϯ 0.17, P Ͻ 0.01) and in the late venous phase (1.61 Ϯ 0.15, P Ͻ 0.001). The pancreatitis group, however, had an arterial phase SIR (1.65 Ϯ 0.23) that was significantly lower than its early venous phase SIR (1.75 Ϯ 0.22, P Ͻ 0.05) and lower than the arterial phase SIR of the control group (P Ͻ 0.01). The presence of an SIR less than 1.73 in the arterial phase and/or a delayed peak enhancement after contrast agent administration had a sensitivity and specificity of diagnosing early or mild chronic pancreatitis of 92% and 75%, respectively. This sensitivity was significantly higher than the sensitivity of 50% for diagnosis based on morphologic abnormalities (P Ͻ 0.05). Conclusion:Measuring pancreatic signal intensity on gadolinium chelate dynamic MRI is helpful for diagnosing early or mild chronic pancreatitis, especially before apparent pancreatic morphologic or signal intensity changes are present.

DCE‐MRI in experimental chronic pancreatitis

“…The TTP on DCE MRI increased gradually with the severity of CP (r ¼ 0.54). Our results confirmed previous clinical research (7,8,15), which indicates a possible connection between decreased pancreatic microvascular perfusion and the severity of CP.…”

“…Our results indicate that there was a significant difference of pancreatic microvascular blood flow in advanced CP from normal pancreas or minimal CP but no significant difference between normal pancreas and minimal CP. This confirmed further previous clinical research (7,8).…”

“…The grade of lesion vascularity of CP on the contrast-enhanced harmonic gray scale sonographic images correlated with the pathologic grade of inflammation and inversely correlated with the grade of fibrosis associated with autoimmune pancreatitis (27). Both experimental and clinical studies showed that pancreatic perfusion in advanced CP were decreased and could be a diagnostic clue for advanced CP (7,8,(11)(12)(13)(14)(15)27). In our study, we also found that the SS and TTP of the pancreatic SI-T curve on the DCE MRI were significantly different between the advanced CP and the normal pancreas or minimal CP.…”

“…Dynamic contrast-enhanced (DCE) MRI of the pancreas has also been used to detect CP in humans (7,8). However, it is accepted that the earliest changes in CP are minimal histological changes and normal imaging (9).…”

“…Both animal (11)(12)(13)(14) and clinical studies (7,8,15) have shown decreased pancreatic tissue perfusion in the condition of CP. DCE MRI may have the potential as a diagnostic tool for CP.…”