Identification of Ferromagnetic Materials of Medical Devices in Patients by Using Dual Energy CT
Y Lu1*, D Ragan1, M Bhalla1, B Barnes2, T Crawford1, Y Liu1, (1) Medical College of Wisconsin, Milwaukee, WI, (2) Froedtert Hospital, Milwaukee, WI
Presentations
(Saturday, 3/26/2022) [Central Time (GMT-5)]
Purpose: It is imperative for clinicians to identify if medical implants in patients contain ferromagnetic components before patients undergo MRI exams, because ferromagnetic materials in the environment of MRI can potentially introduce detrimental hazards on patients. Conventional single energy CT images (SECT) have ambiguity in differentiating material types. Since CT images from dual energy CT (DECT) can provide more accurate CT number quantification, they have the potential for better material identification. This study aims to develop a technique to differentiate ferromagnetic/non-ferromagnetic material types by using DECT technique.
Methods: One plain steel rod (ferromagnetic) and one stainless steel screw (non-ferromagnetic) were collected as inserts into an anthropomorphic head phantom for experiments performed on a DECT CT scanner (GE Revolution Apex). Both SECT and DECT images were acquired with routine head protocols. Monochromatic images were reconstructed from acquired DECT images. Regions of interest (ROI) were manually selected on CT images for each material with its mean value as the CT number (HU). To compare the difference of CT numbers between the two types of steel, a paired Student’s t-test was performed.
Results: For SECT images, CT number of the ferromagnetic steel rod is 16103.31±1033.84 HU, while for non-ferromagnetic steel it is 16662.46±1884.98 HU. There is no statistically significant difference between these two types of steel (p=0.35). For DECT images, the non-ferromagnetic stainless steel always has a higher CT number than the ferromagnetic steel. At 70 keV, CT number of the non-ferromagnetic stainless steel is 27940.26±1190.41 HU, which is significantly higher than that of the ferromagnetic steel (22438.98±1314.49 HU) (p<0.01).
Conclusion: This preliminary phantom study presents the potential of using DECT in differentiating ferromagnetic and non-ferromagnetic steels. Future studies will be conducted using more representative ferromagnetic/non-ferromagnetic materials and medical devices in phantoms and patients.
ePosters
Keywords
Dual-energy Imaging, CT, X Rays
Taxonomy
IM- CT: Dual Energy and Spectral
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