Author: Anzi Zhao 👨🔬
Affiliation: Northwestern Medicine 🌍
Purpose: This study investigates the utility of Dual-Energy Computed Tomography (DECT) material decomposition in resolving Magnetic Resonance Imaging (MRI) safety concerns for patients with unidentified foreign objects. The goal is to demonstrate the broader application of DECT in determining foreign object composition, ensuring safe MRI access when alternative imaging fail to meet clinical needs.
Methods: A 68-year-old female with history of intracranial aneurysm clip (IAC) presented for pre-operative MRI. IAC surgical records were unobtainable. Prior imaging indicated the IAC resembled a across-action design, available in ferromagnetic and non-ferromagnetic versions when implanted. DECT brain imaging was acquired (Siemens SOMATOM Drive) on the patient and a phantom model (Sun Nuclear Multi-Energy CT Phantom) under matched acquisition conditions. DECT data were reconstructed at three composition settings (0, 0.5, 1.0) using a quantitative kernel (Q32) with extended Hounsfield Units. Regions of interest (ROIs) were sampled from the patient’s IAC and subcutaneous scalp fat. Phantom data ROIs were collected from inserts representing adipose tissue (ρwe=0.93), 99% aluminum (ρwe=2.36), titanium (ρwe=3.79), and 316 stainless-steel (ρwe=6.58). Linear regression was used to compare the DECT phantom data with the patient data.
Results: Regression analysis demonstrated a strong correlation between the patient’s IAC data and the titanium insert (R²=0.975, p<0.05). Similarly, the adipose insert significantly predicted fatty subcutaneous scalp data (R²=0.884, p<0.05). In contrast, neither the 316 stainless steel nor the 99% aluminum inserts significantly predicted IAC data (R²=-9.7301 and -11.9112, respectively).
Conclusion: DECT material decomposition is a promising tool for differentiating materials with distinct electron density profiles, addressing critical challenges in MRI safety clearance. The findings suggest that the patient’s IAC is composed of MRI Conditional titanium rather than MRI Unsafe 316 stainless steel. This methodology has the potential for broader application in assessing various foreign objects, improving patient outcomes by facilitating accurate and timely MRI safety evaluations.