What type of Magnetic Resonance Imaging (MRI) is recommended for a pancreas mass?

MRI for Pancreatic Mass Evaluation

For evaluating a pancreatic mass, MRI abdomen without and with IV contrast with MRCP (Magnetic Resonance Cholangiopancreatography) is the recommended imaging modality due to its superior soft-tissue contrast and ability to demonstrate ductal communication. 1

Primary Imaging Recommendation

• MRI abdomen without and with IV contrast with MRCP is the preferred imaging modality for pancreatic masses, with superior sensitivity (96.8%) and specificity (90.8%) compared to CT (80.6% and 86.4% respectively) for distinguishing different types of pancreatic lesions 1, 2
• The reported sensitivity of thin-slice 3-D MRCP acquisitions for demonstrating communication of a cyst with the pancreatic duct is as high as 100%, which is crucial for diagnosing certain types of pancreatic masses like IPMNs 1, 2
• MRI provides superior assessment of internal architecture including mural nodules and internal septations, which are key features for determining malignant potential 2

MRI Protocol Components

• T1-weighted gradient recalled-echo (GRE) sequences with and without fat saturation 3
• T2-weighted single-shot turbo spin-echo (TSE) sequences 3
• Coronal/oblique MRCP pulse sequences 3
• Dynamic gadolinium-enhanced T1w fatsat 3D GRE images to delineate vessel infiltration and assess cystic masses 3
• Diffusion-weighted imaging (DWI) to help differentiate malignant from benign lesions 4

When to Consider CT as an Alternative

• When MRI is contraindicated or unavailable 1
• When identification of calcifications is important for diagnosis 2
• When CT is performed, a dual-phase contrast-enhanced pancreatic protocol CT (including late arterial and portal venous phases with multiplanar reformations) is recommended 1
• CT provides excellent spatial resolution but has inferior soft-tissue contrast compared to MRI 1, 3

Role of Endoscopic Ultrasound (EUS)

• EUS is recommended as an adjunct to cross-sectional imaging, not as the primary diagnostic tool 1, 2
• EUS is particularly valuable when tissue sampling is required 1
• EUS may provide useful staging information, particularly through assessment of vascular invasion 1
• EUS can help evaluate periampullary masses and better characterize cystic pancreatic lesions 1

Important Features to Assess on Imaging

• Size and location of the mass 1
• Presence of mural nodules or solid components suggesting malignancy 2
• Vascular involvement (arterial and venous) 1
• Communication between cystic lesions and the pancreatic duct 1, 2
• Presence of metastatic disease (liver, lymph nodes, peritoneum, lung) 1

Common Pitfalls and Considerations

• Isoattenuating pancreatic tumors (5-17% of cases) may be missed on CT but are better visualized on MRI 1
• MRI is superior to CT for detecting small liver metastases, potentially reducing unnecessary laparotomies 1
• The accuracy of both MRI and CT remains relatively low for identifying the specific type of pancreatic cystic neoplasm 2
• For follow-up imaging of known pancreatic lesions, non-contrast MRI may be sufficient in some cases 1

Special Considerations

• For patients who will undergo surgery with radical intent, imaging should be performed within 4 weeks before starting therapy 1
• Standardized reporting templates are recommended as they significantly reduce the number of missing morphological and vascular features compared with free-text reports 1
• PET/CT is not routinely recommended for the initial diagnosis of pancreatic masses 1