Precipitation of gadolinium and ethanol during nerve block

MR imaging-guided percutaneous sclerotherapy of peripheral venous malformations with a clinical 1.5-T unit: a pilot study

PURPOSE

To evaluate the feasibility of magnetic resonance (MR) imaging-guided percutaneous sclerotherapy of venous malformations (VMs) by using a clinical 1.5-T MR unit and the safety and therapeutic outcome of the performed procedures.

MATERIALS AND METHODS

This is a prospective pilot study with ethical approval and written informed patient consent. Ten MR imaging-guided percutaneous sclerotherapy treatments were performed in 10 patients (one male and nine female patients; age range, 16-47 years; mean age, 30.3 years) with a VM in the foot and/or ankle (n = 5), calf (n = 2), thigh and/or knee (n = 2), and elbow (n = 1). MR imaging was used for needle insertion guidance and real-time monitoring of the injection process by using three-dimensional fast spoiled gradient-echo MR sequences (repetition time msec/echo time msec = 3.7-5.2/1.1-1.6, flip angle = 35 degrees) and meglumine gadoterate/ethanol solutions as the sclerosing agent. The technical success (ie, absence of technical problems, number of needle position corrections) was systematically evaluated along with safety aspects (ie, absence of complications) and the therapeutic outcome (eg, VM volume decrease, relief of symptoms) during a 1-year follow-up period.

RESULTS

MR imaging-guided sclerotherapy was technically successful in all patients. A mean of 2.5 +/- 1.85 (range, 1-6) needle position corrections were needed for correct needle placement. The distribution of the sclerosing agent (mean amount, 10.5 mL; range, 0.8-33.0 mL) was clearly visible with real-time MR monitoring. One patient developed a compartment syndrome, which was managed with surgery. No other complications were observed. VM volumes significantly decreased by 53% (range, 24%-86%; P = .02) 12 weeks after therapy. Nine of the 10 patients (90%) noted an improvement of symptoms.

CONCLUSIONS

In this limited preliminary series, 1.5-T MR imaging-guided percutaneous sclerotherapy for the treatment of VMs was feasible with a high degree of technical success, was relatively safe, and had a good therapeutic outcome after 1 year.

Contrast Material–enhanced Visualization of the Ablation Medium for Magnetic Resonance– monitored Ethanol Injection Therapy: Imaging and Safety Aspects

PURPOSE

This study was performed to test whether the dissociation rate of free Gd3+ ions from gadoterate meglumine is significantly increased when the contrast agent is dissolved in ethanol and whether the magnetic resonance (MR) signal of gadolinium/ethanol solutions is enhanced to a degree that promises reliable detection during MR imaging-guided intralesional administration, such as for the treatment of low-flow venous malformations.

MATERIALS AND METHODS

The apparent gadoterate meglumine-induced enhancement of the longitudinal proton relaxation rate of sterile ethanol/water solutions, stored at a temperature of 24 degrees C +/- 5 degrees C in the dark, was monitored for 2 weeks. The content of dissociated Gd3+ ions was determined after 6 and 8.5 months of storage. The signal difference between contrast agent/ethanol solutions and muscle tissue was assessed with imaging at 0.5 T and 1.5 T.

RESULTS

Commercialized gadoterate meglumine diluted with 94% ethanol was not shown to have released toxic Gd3+ during storage times that exceed its physiologic circulation and excretion times after intravenous injection by a factor of more than 100. A maximum dissociation rate of 0.05% per month was estimated from the detection limit of the analysis. The apparent molar relaxivity of the contrast agent in the mixtures varied by less than 0.1 L/mmol per second with no temporal trend. Gradient-echo ethanol/muscle contrast increased with Gd concentrations to maximums of 15 mmol/L (at 0.5 T) and 25 mmol/L (at 1.5 T).

CONCLUSIONS

Neither limited solubility nor release of Gd3+ ions could be identified as a general safety hazard associated with the application of gadoterate meglumine/ethanol solutions at Gd concentrations of 0.5-25 mmol/L, and such ablation mixtures could be efficiently and reliably visualized.