Article
Intraoperative contrast-enhanced ultrasound angiography (tUSA) in cerebrovascular surgery – first results
Intraoperative kontrastverstärkte Ultraschallangiographie (tUSA) in der zerebrovaskulären Chirurgie – erste Ergebnisse
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Published: | May 30, 2008 |
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Objective: Intraoperative imaging can improve the safety of clip placement during aneurysm surgery. A potentially effective method is ultrasound angiography (tUSA). New developments allow a visualisation of intracranial vessels and the aneurysm in an angiography-like display with high spatial resolution. The aim of our intraoperative study was the use of contrast enhanced ultrasonography for the first time as a practical technology to visualize cerebral vessel anatomy and flow during and after aneurysm surgery.
Methods: In a prospective study, patients scheduled for aneurysm surgery and with elective cerebral x-ray-angiography were asked to participate. Sonoline Elegra sonography system (Siemens Erlangen, Germany) was used for the intraoperative study. The device was equipped with 2, 5-MHZ phased-array transducer. Transdural ultrasound angiography (tUSA) was acquired with a low acoustic power of 1-3% and a frequency of 1,1 MHZ. tUSA was obtained twice transdural after craniotomy and after clip placement. We used SonoVue (Bracco International) for contrast enhancement. The application was done as a bolus injection of 2, 4 ml (108 µg sulphur hexafluoride) intravenously.
Results: Altogether 10 patients with an aneurysm of the anterior circle of Willis were included in the study (4males/6 females). The age ranged from 30-65 years with a mean age of 47 years. Ultrasound angiography was successfully used twice in all patients during the operation.
We registered no adverse event. Image quality was acceptable or good in all cases for B-Mode and contrast application. After injection and a time delay of 10-18 seconds, the contrast overamplification called “blooming” was recorded. Around 20-30 seconds later the effect was overcome and in all cases we could visualize the aneurysm less than 2 millimetres, the adjacent vessel as well as the aneurysm occlusion after clip placement without artefacts. In all cases the intraoperative findings correlated very well with postoperative x-ray-angiography or MR angiography.
Conclusions: Transdural contrast enhanced ultrasound angiography is adequate for real time visualisation of local and general vessels as well as for intraoperative visualisation of aneurysms less than 2 mm. The quality of the images is comparable to x-ray-angiography with high anatomic resolution. The technique is quick, simple and robust without expensive equipment. Further investigation includes quantitative measurement, perfusion analysis of the aneurysm and the perforating arteries.