Contrast medium enhanced susceptibility imaging signal mechanism; should we use contrast medium?

Abstract

Background Intracranial lesions exhibit clear contrast enhancement in T1-weighted imaging, but the mechanism whereby contrast-enhanced susceptibility-weighted imaging (CE-SWI) generates signals remains unclear. Contrast enhancement patterns cannot be reliably predicted. Purpose To explore the mechanism of CE-SWI contrast enhancement. Material and Methods Fifty-five patients were retrospectively enrolled. All of the imaging employed a clinical 3T magnetic resonance imaging (MRI) system fitted with a 32-channel head coil. Minimum-intensity projection reformatted images were evaluated. Intracranial lesions and brain parenchymal intensities were explored using SWI and CE-SWI. signal intensity rates were calculated by dividing the lesional intensity by the white matter intensity, after which the SWI and CE-SWI signal intensity rate were compared. Two observers independently performed intralesional susceptibility signal analysis. Results After contrast medium administration, malignant and extra-axial tumors exhibited obvious contrast enhancement on CE-SWI (P<0.001 and P=0.013, respectively). The signal intensity of white matter was significantly reduced. The signal intensity rates rose significantly in the benign, malignant, and extra-axial groups (P<0.001). Between-radiologist agreement in terms of intralesional susceptibility signal assessment was strong (kappa=0.8, P<0.001). Conclusion Contrast media can either reduce or increase SWI signal intensities. The dual contrast feature of CE-SWI can be useful when exploring intracranial disorders.