Susceptibility-Weighted Imaging for Differentiating Intracranial Calcification and Hemosiderin: A Comparative Study with CT

Ragitha Ramesh¹, Arunan Subbiah ²*, Senthil Kumar Aiyappan¹

This study demonstrates the efficacy of SWI, particularly the filtered phase image, in accurately differentiating calcification from hemosiderin, offering a safer alternative to CT imaging.

Abstract

Background: Magnetic resonance imaging (MRI) is an essential diagnostic modality for evaluating various tissue types, but distinguishing between substances such as calcification and hemosiderin remains challenging due to their similar appearances on conventional MRI sequences. Susceptibility-weighted imaging (SWI) improves tissue contrast by incorporating phase information, potentially enhancing the accuracy of differentiating these substances. This study aims to assess the effectiveness of SWI, specifically the filtered phase image, in comparison with computed tomography (CT), which is considered the gold standard for calcification detection. Methods: A retrospective analysis was conducted on 35 patients, aged 50-80 years, who presented with confirmed cases of intracranial calcification or hemosiderin deposits. MRI was performed on a 1.5-tesla Siemens Essenza Magnetom using SWI sequences, including both phase and magnitude images. CT scans were obtained using a GE Optima 660 scanner. The study focused on 17 cases of calcification identified by both SWI and CT, and 18 cases of hemosiderin deposits detected by SWI. Statistical analysis was performed using Pearson correlation coefficients to evaluate the relationship between MRI and CT measurements. Results: The study revealed a strong correlation between CT and SWI in detecting calcifications, with a significant agreement in the measurement of calcification size. However, while phase and magnitude images demonstrated a strong correlation with one another, the filtered phase image did not show a significant correlation with hemosiderin size, suggesting limitations in its application for detecting hemosiderin deposits. CT scans confirmed calcification with Hounsfield units exceeding 100, while hemosiderin deposits were more effectively identified through SWI, which provided enhanced contrast without the use of ionizing radiation. Conclusion: SWI, particularly the filtered phase image, is a reliable and sensitive tool for detecting intracranial calcification, offering high accuracy compared to CT. While SWI proves effective in distinguishing calcification, further research is needed to optimize its use for detecting hemosiderin deposits. This study underscores the non-ionizing advantages of SWI over CT, advocating for its potential as a safer and equally effective alternative in clinical imaging.

Keywords: Susceptibility-Weighted Imaging (SWI), Calcification detection, Hemosiderin identification, MRI phase images, Non-ionizing imaging

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