Electromagnetically tracked ultrasound for small animal imaging

Charles F. Caskey, Mario Hlawitschka, Shengping Qin, Katherine W. Ferrara

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The fusion of computed tomography (CT) and ultrasound (US) imaging hasrecently been examined for guiding interventional procedures such as biopsy,local drug delivery and radiofrequency ablation. During combined CT/USprocedures, US facilitates real time visualization of blood flow and tissuestructure, while CT provides a three-dimensional view of an extended region andis capable of differentiating tissue types based on Hounsfield units (HU). Ourlaboratory is working to extend this fusion to include therapeutic USco-registered with CT. Here, we demonstrate the ability to differentiate fat,protein-rich regions, and bone with CT by comparing segmented CT images tohistology. Then we present methods for semi-automated registration betweentracked US and CT with the objective of imaging and guiding acoustic therapy insmall animals. A calibration phantom and fiducial markers were used to generateaccurate transformation between the real-time US and pre-acquired CT imagestack. The mean error in transducer calibration was 0.70.5mm with a maximumerror of 1.75mm. Target registration error (TRE) of 1.98/1.12mm was observedbetween US and CT images of a dual-modality phantom. The combined CT/US systemprovides CT-based guidance with enough accuracy to plan and guide US-inducedhyperthermia.

Original languageEnglish (US)
Title of host publicationProceedings - IEEE Ultrasonics Symposium
Number of pages4
StatePublished - 2010
Event2010 IEEE International Ultrasonics Symposium, IUS 2010 - San Diego, CA, United States
Duration: Oct 11 2010Oct 14 2010


Other2010 IEEE International Ultrasonics Symposium, IUS 2010
Country/TerritoryUnited States
CitySan Diego, CA


  • 3D ultrasound
  • image-guided therapy
  • mild hyperthermia
  • tracked ultrasound

ASJC Scopus subject areas

  • Acoustics and Ultrasonics


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