Article
Elastography during brain tumor surgery: First results
Elastographie bei der Operation von Hirntumoren : erste Ergebnisse
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Authors
Published: | April 23, 2004 |
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Outline
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Objective
Elastography is a new method in tumor diagnostics especially in prostata or mamma carcinoma. After experimental work with swine brains we transferred this real time imaging technique to the human brain during open neurosurgery according to the requirements of the ethic commission of the Ruhr-University Bochum.
Methods
We used a conventional ultrasound system (Siemens Sonoline Omnia) with additional hard and software components for elastography. Using a new approach the conventional static tissue compression was replaced by low frequency vibration operating in quasi static compression mode. The strain imaging system uses the fast phase root algorithm for strain estimation with ca. 40 Hz. Strain images are frame-to-frame filtered by an adaptive temporal filter which enables the use of an up to 50 % smaller compression of the tissue achieving the same image quality as with the conventional frame-to-frame filters. Ultrasound rf-data was aquired using the above described system and a 6.5 MHz endocavity curved array.
Results
The study demonstrated that with a total compression of only 0.3 mm, high quality strain images can be produced. First in vivo images of 12 patients (age 31 - 77 years) with different histologies are presented in compared to conventional ultrasound. In 11 of 12 cases tumor could be detected with elastography. With vibrography three different types of tumor elastograms could be differentiated. Two tumors showed equal elasticity like brain tissue and were therefor of red appearance with a yellow border at the outer margin. 5 other tumors were yellow in the elastogram and and 5 other tumors brown or black in the elastogram and therefor harder than brain tissue.
Conclusions
Elastography and its modification vibrography are new online imaging techniques which can be used in addition to conventional ultrasound in brain tumor surgery. For detection of tumor remnants in the margin of resection caves application method has to be adapted because direct tissue contact is required for vibrography. Further studies are needed to improve image quality. In future investigations fusion with MRI-data for neuronavigation will be achieved.