Differentiation between diamagnetic and paramagnetic cerebral lesions based on magnetic susceptibility mapping

Area of Science:

• Neuroimaging
• Medical Physics
• Radiology

Background:

• Accurate etiological diagnosis of cerebral lesions requires identification of calcifications and hemorrhages.
• Magnetic resonance imaging (MRI) phase data can reflect magnetic susceptibility distributions in biological tissues.

Purpose of the Study:

• To develop a robust method for characterizing intra-cerebral lesions (calcifications and hemorrhages) using clinical gradient-echo MRI phase data at 1.5 Tesla.
• To differentiate between paramagnetic and diamagnetic properties of brain lesions.

Main Methods:

• Inversion of magnetic resonance phase data to susceptibility distribution using lesion geometry from gradient-echo magnitude signal voids.
• Processing and evaluation of clinical MRI exams from three patients (n=70 lesions).
• Validation using computed tomography (CT) and numerical simulations to assess robustness.

Main Results:

• Susceptibility maps demonstrated clear delineation of lesions, vessels, and iron-laden tissues.
• Successful discrimination between paramagnetic and diamagnetic lesions was achieved in all cases.
• Quantitative values for minimum magnetic susceptibility of lesions were obtained, confirmed by CT and simulations.

Conclusions:

• A noninvasive, semiautomatic method for characterizing brain lesions using MRI phase data has been developed.
• The technique shows potential for diagnosing lesions with calcifications or hemorrhages.
• Further studies may confirm its utility in obviating the need for confirmatory CT scans.