In vivo carotid plaque MRI using quantitative T2* measurements with ultrasmall superparamagnetic iron oxide particles: a dose–response study to statin therapy

NMR in Biomedicine - Tập 24 Số 1 - Trang 89-95 - 2011
Andrew J. Patterson1, Tjun Yip Tang1, Martin J. Graves1, Karin H. Müller2, Jonathan H. Gillard1
1Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
2Multi‐Imaging Centre, Department of Physiology, University of Cambridge, Cambridge, UK

Tóm tắt

AbstractThis study investigates T2* quantification in carotid plaques before and after the administration of ultrasmall superparamagnetic iron oxide particles (USPIOs) in a cohort of patients receiving statin therapy. Phantom studies were performed using gels with varying concentrations of USPIOs. In the phantom study, 12 gels were prepared with a range of freely distributed concentrations of USPIO nanoparticles (0–0.05 mg/mL). Relative signal intensity measurements were obtained from a T2*‐weighted sequence as well as quantitative T2* (qT2*) measurements. In the patient study, 40 patients with >40% carotid stenosis were randomised to low‐ and high‐dose statin therapy (10 and 80 mg of atorvastatin). Pre‐ and post‐ (36 h) USPIO‐enhanced MRI were performed at baseline, and at 6 and 12 weeks. A linear mixed‐effects model was applied to account for the inherent correlation of multiple‐plaque measurements from the same patient and to assess dose–response differences to statin therapy. In the phantom study, the T2*‐weighted sequence demonstrated an initial increase (T1 effect), followed by a decrease (T2* effect), in relative signal intensity with increasing concentrations of USPIO. The qT2* values decreased exponentially with increasing concentrations of USPIO. In the patient study, there was a highly significant difference in post‐USPIO T2* measurements in plaques between the low‐ and high‐dose statin groups. This was observed for both the difference in qT2* measurements (post‐USPIO minus pre‐USPIO) (p < 0.001) and for qT2* post‐USPIO only (p < 0.001). The post‐USPIO qT2* values were as follows: baseline: low dose, 13.6 ± 5.5 ms; high dose, 12.9 ± 6.2 ms; 6 weeks: low dose, 13.3 ± 6.7 ms; high dose, 14.3 ± 7.7 ms; 12 weeks: low dose, 14.0 ± 7.6 ms; high dose, 18.3 ± 11.2 ms. It can be concluded that qT2* measurements provide an alternative method of quantifying USPIO uptake. These results also demonstrate that changes in USPIO uptake can be measured using post‐USPIO imaging only. Copyright © 2010 John Wiley & Sons, Ltd.

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NMR in Biomedicine

Tập 24 Số 1

89-95

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