Preparation and MR Imaging Study of a Recombinant Surface Antibody Superparamagnetic Iron Oxide Nanoparticle–EPC1 Molecular Probe for Hepatic Alveolar Echinococcosis

PURPOSE: To establish a new hepatic alveolar echinococcosis (HAE) model, construct an EPC1 antibody-conjugated superparamagnetic iron oxide nanoparticle (SPION) molecular probe and evaluate the probe's efficacy in the targeted MRI of HAE. METHODS: Thirty C57 female mice (9-10 weeks; 17-22g) were used to establish an HAE model via hepatic portal vein infection. Twenty successfully HAE-modeled mice were randomly divided into a control group, which was given a simple SPION tracer, and an experimental group, which was given a complex SPION-EPC1 tracer. In addition, a blocking group (n = 5), in which mice received an excess dose of free EPC1 antibody prior to injection of the SPION-EPC1 tracer, was included to assess EPC1-dependent targeting, and a gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) group (n = 5), which received 0.1 mmol/kg of Gd-DTPA, was included to provide a reference clinical contrast agent. MRI was performed using an animal MRI scanner, and T1- and T2-weighted imaging sequences were utilized to assess lesion characteristics before and after tracer injection at 1 and 4h time points. Subsequently, T2 signal intensity, the lesion SNR, and the lesion-to-liver contrast-to-noise ratio were measured by 2 blinded physicians (>5 years experience) using ImageJ software. Comparisons were made between plain and post-injection scans at 1 and 4h. Independent sample t-tests and non-parametric tests were applied to compare signal intensities and SNR values. RESULTS: The SPION-EPC1 probe significantly decreased T2 signal intensity and lesion SNR in the experimental group at both 1 (T2 intensity: -24.3%; SNR: -35.2%) and 4h (T2 intensity: -23.5%; SNR: -43.1%) compared with plain scans. By contrast, the control group showed only transient decreases, with no significant differences at 4h. In the EPC1-blocking group, the T2-signal decrease at 4h was markedly attenuated compared with that of the SPION-EPC1 group and comparable to that of the SPION group, supporting EPC1-dependent targeting. CONCLUSION: The SPION-EPC1 molecular probe demonstrated improved sensitivity and long-lasting effects in the MRI detection of HAE lesions, offering a promising tool for early diagnosis and the potential advancement of clinical practice in HAE imaging.