What does calcification on an MRI (Magnetic Resonance Imaging) report mean?

What Does Calcification on MRI Mean?

When an MRI report mentions calcification, it indicates the presence of calcium deposits in tissue, but you should recognize that MRI has significant limitations in detecting and characterizing calcification compared to CT—if characterizing calcification is clinically important, CT should be obtained. 1, 2, 3

Understanding MRI's Limitation with Calcification

Detection Challenges

• MRI is inherently limited in identifying mineralization, which is why CT remains the gold standard for detecting and characterizing calcification 1, 4
• In a systematic study of 20 patients with CT-confirmed calcifications, MRI detected the calcification definitively in only 3 of 20 cases (15%), raised the possibility in 7 cases (35%), and was indeterminate in 10 cases (50%) 3
• CT proved superior to MRI in both detecting and characterizing calcification in all cases studied 3

How Calcification Appears on MRI

• Calcifications typically appear as regions of profoundly reduced signal intensity (signal void) on MRI sequences, similar to cortical bone 3
• T2-weighted sequences are most sensitive for detecting calcification as signal void 3
• The signal characteristics are inconsistent—calcification may show signal void in some pulse sequences but not others, making interpretation unreliable 3
• In some metabolic conditions causing calcium deposition, paradoxically high signal on T1-weighted imaging may occur due to surface effects of diamagnetic calcium particles 5

Clinical Implications by Location

Soft Tissue Masses

• CT is the optimal imaging method to characterize soft-tissue mineralization, allowing distinction between ossification and calcification 1, 4, 6
• CT can identify characteristic patterns of mineralization (such as the zonal pattern in myositis ossificans) that may be invisible or nonspecific on MRI 1, 4
• For flank masses or deep soft tissue masses with calcification, CT should be performed before biopsy to guide diagnosis and management 4, 6

Joint and Inflammatory Conditions

• Calcifications in crystal deposition diseases (calcium pyrophosphate dihydrate disease/pseudogout) can be visualized by radiography, ultrasound, and CT, whereas MRI is less sensitive 1
• Chondrocalcinosis and calcification of tendons or joint capsules are better evaluated with CT or ultrasound than MRI 1

Cardiovascular Calcifications

• MRI can be misleading in cardiovascular imaging because of difficulty detecting clinically important calcifications such as calcified coronary arteries, calcific pericarditis, or calcified myocardial infarctions 2
• These calcifications are readily apparent on CT but may be missed entirely on MRI 2

Lymph Node Metastases

• Calcified metastatic lymph nodes (particularly in rectal cancer) appear as patchy areas of signal loss on high-resolution MRI that are larger than the actual calcification seen on CT 7
• Mixed signal intensity in lymph nodes on MRI may indicate calcification and can be a strong indicator of metastasis 7

When to Obtain CT After MRI Reports Calcification

Mandatory CT Scenarios

• Any soft tissue mass in the flank, paraspinal region, groin, or deep tissues where calcification pattern affects diagnosis 1, 4, 6
• When distinguishing ossification from calcification is clinically important 1, 4
• Before biopsy of any mass where calcification is mentioned, as the pattern may be diagnostic 4, 6
• When evaluating for crystal deposition diseases if MRI was performed first 1

CT Protocol Considerations

• Obtain noncontrast CT images first, as distinguishing subtle calcification from enhancement may be impossible without precontrast images 1, 4, 6
• Consider adding IV contrast after noncontrast imaging to evaluate vascularity and tumor margins 4, 6
• CT's multiplanar capability is ideal for depicting the interface between calcified masses and adjacent bone 1, 4

Critical Pitfalls to Avoid

• Do not assume MRI has adequately characterized calcification—if the clinical question involves the nature, extent, or pattern of calcification, obtain CT 1, 4, 3
• Do not proceed to biopsy based on MRI findings alone when calcification is present in a soft tissue mass—CT characterization should precede biopsy 4, 6
• Do not dismiss the possibility of calcification if MRI shows signal void—this may represent calcification, hemosiderin, air, or flow void, and CT may be needed for clarification 3
• In pediatric patients with flank masses and calcification, the differential includes neuroblastoma, Wilms tumor, and sarcomas—CT is essential for characterization 4