Antimicrobial distribution from local delivery depends on dose : a pilot study with MRI

Area of Science:

• Biomedical Engineering
• Materials Science
• Radiology

Background:

• Previous studies quantified tissue distribution of gadolinium-labeled diethylenetriamine pentaacetic acid (Gd-DTPA) over 5 hours in rabbits using 7-T MRI.
• The impact of Gd-DTPA load in bone cement on local tissue distribution duration after surgery remained unknown.

Purpose of the Study:

• To determine if the Gd-DTPA load in bone cement influences local tissue distribution over a 1-month period.
• To assess the relationship between gadolinium concentration in bone cement and its sustained release in local tissues.

Main Methods:

• A rabbit model with a 1-cm3 soft tissue dead space in the quadriceps was used.
• The dead space was filled with bone cement containing varying gadolinium loads.
• Tissue volumes with Gd-DTPA concentrations >14 μg/mL were measured using 7-T MRI at 7, 14, and 33 days.

Main Results:

• Higher gadolinium loads resulted in significantly larger volumes of tissue with high Gd-DTPA concentration on Day 7 (p=0.02).
• For the 10-g gadolinium load, the distribution volume decreased over time (2121 mm3 on Day 7 to 1241 mm3 on Day 14).

Conclusions:

• The volume of distribution and duration of Gd-DTPA in local tissues increased with higher loads in the bone cement.
• Sustained high antimicrobial concentrations in local tissues are achievable with increased antimicrobial loads in delivery systems.