IOP Injection, A Novel Superparamagnetic Iron Oxide Particle MRI Contrast Agent for the Detection of Hepatocellular Carcinoma: A Phase II Clinical Trial

Abstract

Background: MRI is crucial in diagnosing hepatocellular carcinoma (HCC). Superparamagnetic iron oxide particles (SPIO) are liver-specific contrast agents which enhance lesions in T₂ -weighted images. Iron oxide nano-particle m-PEG-silane (IOP) Injection, a newly developed SPIO, showed promising imaging effects and good safety profile in preclinical studies and in phase I clinical trial.

Purpose: To evaluate the safety and clinical validity of IOP Injection as MRI contrast agent in diagnosing HCC.

Study type: Prospective.

Subjects: A total of 52 subjects (61.6 ± 11.05 years, 45 males/7 females) with suspected HCC.

Field strength/sequence: 1.5 T, T₁ -weighted in/opposed phase, T₂ *-weighted gradient echo, T₂ -weighted fast spin echo, true fast imaging with steady-state free precession.

Assessment: Adverse effects and clinical monitoring were recorded throughout the 5-day study. Two independent readers (M.G.H. with 30 years of experience, S.P.K. with 26 years of experience) made the diagnosis. The diagnostic performance of IOP-enhanced MRI was evaluated with sensitivity and positive predictive value by comparing to the pathology reports from subsequent hepatic resection. The number of lesions with various sizes and degrees of differentiation detected by IOP-enhanced MRI was assessed. The relative change in signal intensities over time was indirectly measured from acquired images.

Statistical tests: Sensitivity and positive predictive value were used to evaluate the diagnostic performance of IOP-enhanced MRI. Prevalence-adjusted and bias-adjusted 𝜅 coefficient was used to assess the interreader variability.

Results: No serious adverse event related to IOP Injection was found. IOP Injection enhanced the lesion-to-liver contrast ratio in T₂ *-weighted images by 50.1% ± 4.8%. IOP-enhanced MRI detected HCC with 100% sensitivity by subject and 96% sensitivity by lesion. IOP Injection visualized subtle vascular invasion as filling defect within vessels in true fast imaging with steady-state free precession (TrueFISP) images.

Data conclusion: IOP Injection was safe and efficacious as MRI contrast agent in diagnosing HCC in a limited group of subjects.

Evidence level: 2.

Technical efficacy: Stage 2.

Keywords: hepatocellular carcinoma; liver specific contrast agent; magnetic resonance imaging; superparamagnetic iron oxide particles.