2012 Proceedings - International Tissue Elasticity Conference

010 MONITORING SURGICAL RESECTION OF TUMORS WITH ULTRASOUND STRAIN IMAGING.
TS Pheiffer 1 , BC Byram 3 , MI Miga 1,2 .
1 Vanderbilt University, Nashville, TN, USA; 2 Vanderbilt University Medical Center, Nashville, TN,
USA; 3 Duke University, Durham, NC, USA.
Background: Resection of tumors is often performed by the surgeon using tactile sensory information to
distinguish between normal and abnormal tissue. Ultrasound strain imaging has potential to supplement
conventional guidance methods with quantitative information about tissue stiffness at depth. It has been
suggested that strain imaging may be capable of distinguishing tumor from normal tissue during surgery
[1–3]. With respect to diagnostic lesion inspection, localization with strain imaging of a potential surgical
target is well understood. In this work, we assess the efficacy of this modality to monitor resection.
Aims: The aim of this work is to demonstrate the feasibility of using ultrasound strain imaging to monitor
a tumor remnant during surgical resection.
Methods: A phantom was constructed of tissue–mimicking polyvinyl alcohol gel with graphite scatterers
and a fabric sphere to serve as the target lesion. The tumor was incrementally resected in three stages,
with larger amounts excised at each stage until complete removal was accomplished. Strain imaging was
performed of the tumor remnant at each stage of resection, and the tumor cavity was irrigated with water
to eliminate air pockets introduced by the resection process. An Acuson Antares ultrasound machine
(Siemens, Munich, Germany) was used with a VFX13–5 probe at a frequency of 11.4MHz. Strain images
were generated using the eSie Touch Elasticity Imaging software on the ultrasound machine. All imaging
was conducted freehand with the probe in approximately the same location lateral to the resection site.
Figure 1: Effects of tumor resection on strain imaging in a cryogel phantom. (a), (c), (e) and (g) show increasing
amounts of tumor resection, from no resection to total resection. (b), (d), (f) and (h) show the
corresponding strain images of the tumor remnant.
Results: The strain images show the tumor mass with clear contrast against the bulk phantom material
prior to resection. After resection of approximately one third of the tumor volume, the lesion still appears
in the strain images with a corresponding reduction in image slice cross– sectional area. After resection of
another third of the tumor, the tumor mass still clearly appears in the strain images but with a more
noticeable decrease in cross–sectional area. Following the complete resection of the entire tumor mass,
strain imaging no longer showed a region of low strain in the resection cavity.
Conclusions: The phantom study performed shows the feasibility of using ultrasound strain imaging as a
tool for monitoring surgical resection of lesions. It was shown that the excision of tumor mass and the
creation of a resection cavity did not obstruct the creation of strain images. In addition, the lesion area in
the images decreased in correlation with decreasing remnant tumor volume. Ultrasound strain imaging
shows promise as a surgical localization method and awaits further studies within the clinical environment.
Acknowledgements: This work is funded by the National Institutes of Health: grant R01 NS049251 of the National
Institute for Neurological Disorders and Stroke.
References:
[1] Chakraborty, A., J.C. Bamber, and N.L. Dorward: Preliminary Investigation into the Use of Ultrasound
Elastography during Brain Tumour Resection. Ultrasound, 20(1), pp. 33–40, 2012.
[2] Scholz, M., et al.: Current Status of Intraoperative Real–Time Vibrography in Neurosurgery. Ultraschall Med,
28(5), pp. 493–7, 2007.
[3] Selbekk, T., et al.: Tissue Motion and Strain in the Human Brain Assessed by Intraoperative Ultrasound in
Glioma Patients. Ultrasound in Medicine and Biology, 36(1), pp. 2–10, 2010.
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