Quantification of blood Gd-DTPA levels : implications on dosing dGEMRIC

Abstract

Delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a novel technique that allows early diagnosis of osteoarthritis (OA). Under the current protocol, subjects are injected 0.2mmol of an MRI contrast agent (Gd-DTPA 2, Berlex Imaging, Wayne, NJ) per kilogram of body weight. Because the distribution volume of Gd-DTPA - is affected by body composition, subjects with high Body Mass Index (BMI) may effectively be dosed higher compared to low BMI subjects. In this study, 0.2mmol of Gd-DTPA2- per kilogram of body weight was injected into 17 subjects with varying BMI. Their blood Gd-DTPA - levels were measured at 15, 30, 45, 60, 90, and 120 minutes post-injection. Although there was a wide scatter in Gd-DTPA2- levels both across the subjects and within subjects of similar BMI, results indicated a positive relationship between blood Gd-DTPA2- levels and BMI. It was determined that this effect could lead to over-pronounced OA severity for high BMI subjects. However, further experiments are needed to understand the scatter to better quantify the effect BMI could have on dGEMRIC.