Advisor Client Justin Williams, PhD Department of BiomedicalEngineering University of Wisconsin-Madison Fredrick Kelcz, PhD, MD Department of Radiology University of Wisconsin-Madison

Abstract Core biopsy procedures are currently subject to high specificity due to inaccurate imaging of small tumors around the biopsy needle. Ultrasonic imaging can differentiate between tissue types by the differences in echogenic calcifications. The basics of IVUS probes were used to develop two ultrasonic methods: an integrated ultrasonic probe and a catheter based IVUS probe technique. The chosen design involves the insertion of a catheter based IVUS probe, once the needle is in place. This technique should provide accurate imaging and is extremely practical to implement. However, this techniques will require further experimentation to evaluate its ability to image within the needle in the presence of a strong magnetic field.

Problem Statement The goal of this project is to develop an intravascular ultrasonic probe (IVUS) to provide better imaging without artifact during mammographic and MRI guided biopsy procedures. Usually Biopsy procedures are done with MRI or CT guidance; however, biopsy needles can obstruct imaging of tumors making it difficult to make fine adjustments in needle placement.

Problem Definition Motivation Motivation The accuracy of the overall biopsy procedure is improved and doctors can guarantee patients that the correct lesion was sampled

Background on Guided Core Biopsy Procedure First visit First visit Initial mammographic/MR image Initial mammographic/MR image Positive diagnosis—suspicious lesions Positive diagnosis—suspicious lesions Second visit Second visit Second MR image—insertion of plastic clip Second MR image—insertion of plastic clip Third MR image—check placement Third MR image—check placement Needle Insertion Needle Insertion –Exact location never verified Perform biopsy Perform biopsy Results Results Pathological analysis Pathological analysis

IVUS Probes Use a pizoelectric transducer implanted in catheter 1-2mm in diameter and cm long Use a pizoelectric transducer implanted in catheter 1-2mm in diameter and cm long Provide 2D cross sectional imaging Provide 2D cross sectional imaging A motor rotates the transducer at ~1800rpm A motor rotates the transducer at ~1800rpm Typically single use costing ~$1000 Typically single use costing ~$1000 Operate at 20-40MHz depending on model Operate at 20-40MHz depending on model Imaging depth of 1-2cm depending on frequency Imaging depth of 1-2cm depending on frequency

Design Criteria Spatial resolution approximately mm Spatial resolution approximately mm Depth perception approximately 3-5mm Depth perception approximately 3-5mm Distinguish small tumors and calcifications from normal tissue Distinguish small tumors and calcifications from normal tissue Operate within core biopsy needle with minimal artifact Operate within core biopsy needle with minimal artifact MRI compatible (Class III) MRI compatible (Class III)

Final Design: Catheter Based IVUS Probe 40 MHz “Discovery” IVUS probe 40 MHz “Discovery” IVUS probe Core Biopsy Needle Core Biopsy Needle Manufactured plastic rod insert Manufactured plastic rod insert

Testing Methods Phantoms Phantoms –Water –Ground orange pulp* –Orange slice* –Ultrasonic gel* –Raw turkey breast* *With and without simulated calcifications. To simulate calcifications we used 8 in 1:Sun ripened fruit mineral treat ( % calcium content)

Results

Future Work Testing MRI compatibility Testing MRI compatibility Future phantoms Future phantoms –Simulated tumor (olive in turkey breast) –Real specimen Investigate different probe frequencies Investigate different probe frequencies Investigate probe redesign Investigate probe redesign

Conclusions IVUS imaging shows great potential towards increasing biopsy yields IVUS imaging shows great potential towards increasing biopsy yields System is capable of detecting calcifications System is capable of detecting calcifications Ability to detect actual tumors is unknown Ability to detect actual tumors is unknown Current devices are not MRI compatible Current devices are not MRI compatible

Acknowledgements Our team would like to extend thanks to the following individuals for their assistance on this design project: Dr. Frederick Kelcz Professor Justin Williams Dr. Tomy Varghese Dr. Jim Zagzebski Keith Bourne

References Diagnosis by Biopsy The Breast Center at Southern Illinois University School of Medicine. Date Accessed: February 9, URL: Lengyel J, Greenberg DP, and Popp R. Time-Dependent Three- Dimensional intravascular ultrasound. SIGGRAPH 95 Conference Proceedings, Annual Conference Series, pages ACM SIGGRAPH, Addison Wesley, August 1995 Nissen S Coronary angiography and intravascular ultrasound. Am J Cardiol. 87(4A):15A-20A Trevino, M. (2003, December 12) Calcifications may be presage invasive breast cancer. Diagnostic Imaging Online. Retrieved February 11, 2004 from Yock, P., Johnson, E., and David, D. Intravascular ultrasound:Development and clinical potential. American Journal of CardiacImaging 2(185)