Comparative evaluation of the geometrical accuracy of intravascular magnetic resonance imaging: a phantom study

Radio-opaque ethylcellulose-ethanol is a safe and efficient sclerosing agent for venous malformations

OBJECTIVE

To evaluate the efficacy and safety of gelified ethanol, a newly developed sclerosing agent for slow-flow vascular malformations.

METHODS

Seventy-nine sclerotherapy procedures were performed on 44 patients with 37 venous malformations, 2 glomuvenous malformations, 2 lymphatic malformations, 2 lymphatico-venous malformations, and 1 Klippel-Trenaunay syndrome. The median injected volume was 1.00 mL/site of injection. Effects of sclerotherapy on pain, functional and cosmetic disturbance were statistically evaluated with a final result score. Local and systemic complications were recorded.

RESULTS

The mean Visual Analogue Scores were 5.20  ±  2.81 before and 1.52  ±  1.25 after treatment (p < 0.001). Functional and aesthetic improvement was achieved in 31/35 patients (89%) and in 33/41 (80%), respectively. Minor local side effects included necrosis with or without issue of ethylcellulose, palpable residue, and hematoma. No systemic side-effects occurred.

CONCLUSION

Per mL used, radio-opaque gelified ethanol is at least as effective as absolute ethanol. No systemic complication was observed, as only a low dose of ethanol was injected. Indications for sclerotherapy can be widened to areas with higher risk for local side effects (hands and periocular region), as ethanol is trapped in the lesion. Careful injection procedure is though necessary, because only a limited amount of ethylcellulose can be used per puncture. Key Points • Development of a new sclerosing agent for venous malformations. • Interesting novel way to deliver alcohol to slow-flow vascular malformations. • Alcohol-based with less local and systemic side-effects.

Improved in-stent lumen visualization using intravascular MRI and a balanced steady-state free-precession sequence

RATIONALE AND OBJECTIVES

To investigate the ability of an intravascular magnetic resonance (MR) loopless antenna to reduce the radiofrequency shielding of a vascular stent during signal reception as a way to improve the visualization of the in-stent lumen.

METHODS AND MATERIALS

Using a balanced steady-state free-precession (bSSFP) sequence and a dedicated vascular phantom, the signal-to-noise ratio (SNR) inside the lumen of a stent is evaluated as a function of the nominal flip angle and compared with the results obtained for a reference vessel without a stent. All experiments are performed using successively an intravascular loopless antenna and surface arrays coils. Using an optimized protocol, in vitro in-stent restenosis visualization and quantification experiments are performed to evaluate the validity of an approach using an intravascular antenna and cross-sectional images to depict a vascular lesion inside a stent.

RESULTS

The use of a loopless antenna effectively eliminates the radiofrequency shielding effect of the stent during signal reception. Furthermore, using a bSSFP sequence with a carefully chosen nominal flip angle, an equally good blood SNR can be obtained inside and outside the stent. Results of in vitro in-stent restenosis quantification measurements using the proposed method illustrate the benefits arising from the use of the intravascular antenna.

CONCLUSION

In the perspective of MR-guided vascular interventions, the presented results illustrate that the use of an intravascular antenna can significantly facilitate imaging inside a vascular stent. Potential applications include the monitoring of stent deployment as well as visualization and quantification of in-stent restenosis during an intervention.