Molecular Imaging of Breast Cancer Using Breast PET/CT

Institution: University of California, Davis
Investigator(s): Ramsey Badawi, Ph.D. -
Award Cycle: 2005 (Cycle 11) Grant #: 11IB-0114 Award: $99,907
Award Type: IDEA
Research Priorities
Detection, Prognosis and Treatment>Imaging, Biomarkers, and Molecular Pathology: improving detection and diagnosis

Initial Award Abstract (2005)
We propose to combine an existing positron emission tomography (PET) detector system, built previously, with a dedicated breast computed tomography (CT) system built with prior California CBCRP, as well as NIH resources. By combining the functional (physiological) image information derived from PET with the excellent anatomical detail provided by breast CT, we anticipate that a more quantitative assessment of breast cancer aggressiveness can be made, and that the fused PET/CT image data sets will provide physicians with better information to optimize the therapeutic treatment of breast cancer on a patient-by-patient basis.

The current project involves the engineering (electrical, mechanical, and computational) development of a combined PET/CT system capable of imaging only the breast, and this sets the stage for addressing the clinical utility after the breast PET/CT scanner is ready. Thus, we plan to build a working PET/CT system dedicated for breast imaging, using existing hardware. Four specific aims will be utilized to reach this objective: (1) upgrade the PET electronics, and develop PET reconstruction algorithms specific to the geometry of the newly proposed system, (2) physically and electronically integrate the PET hardware with the existing breast CT scanner gantry, (3) develop calibration techniques for the co-alignment of PET and CT breast images, and finally (4) measure the sensitivity and quantitative accuracy of the breast PET/CT. To accomplish our aims, we will upgrade the electronics on the PET system to improve sensitivity and mathematical algorithms will be written to robustly reconstruct the images acquired with the PET hardware. The PET detector system will be physically mounted onto the existing breast CT gantry. A system of breast-equivalent phantoms which simulate the anatomical and physiological characteristics of breast cancer will be built and used to optimize the image acquisition of the hybrid PET/CT breast scanner. At the end of this developmental project, we anticipate having a working breast PET/CT system, capable of imaging patient volunteers.

Final Report (2007)
The overall objective of this grant was to combine an existing breast PET system (built with Komen funding) with an existing breast CT scanner (built with CBCRP funding), to produce a well integrated PET/CT system dedicated to breast imaging. This objective has been met. A combined system has been fabricated and characterized, and human trials with it are about to start.

Specifically, we achieved success in the following project aims: (a) Upgrade PET electronics and develop PET reconstruction algorithms. We have replaced the original data acquisition system with a 16-channel system that is capable if simultaneously recording prompt, random and single event rates. This involved substantial re-programming of our data acquisition software and the interfacing of several new electronics modules with our data acquisition computer. We have also developed Filtered Back-Projection, Maximum-Likelihood and Maximum A Postiori algorithms for tomographic reconstruction (i.e., imaging by sections or sectioning).

(b) Physically and electronically integrate PET hardware with existing breast CT scanner. We have built a computer-controlled PET gantry that can rotate, vertically translate, and move the PET detectors closer to or further form the breast. This device is physically integrated into our breast CT prototype. Retractable shields have been built to protect the PET detectors during x-ray CT scanning.

(c) Develop calibration techniques for co-alignment of PET and CT breast images. We have built a phantom which models the breast and contains “markers” that can be filled with iodinated (radioactive) contrast agent and PET tracer. Using this device we have computed the accuracy of the overlay of the PET to the CT data - accuracy of less than 0.5 mm was obtained.

(d) Evaluate sensitivity and quantitative accuracy of breast PET/CT scanner. We have measured the noise equivalent count (NEC) rate capabilities of the combined scanner. Using a centrally placed cylinder of internal diameter 4.5 cm and height 14.5 cm, uniformly filled with activity, a peak NEC of 26,000 cps was obtained with a total activity of 0.5 mCi. For an anthropomorphic activity distribution, the NEC is in the 2-3000 cps range. Assessments of the quantitative accuracy of the device are still ongoing.

We have now obtained funding from the American Cancer Association to make a “first-in-human” trial of 10 patients with suspected breast cancer using this device. We have also obtained additional funding from the Komen Foundation to perform a further upgrade of the system electronics and test the device in a neoadjuvant therapy response trial; funding from the NIH for a second prototype device is pending.

Characteristics of the PET Component of a Dedicated Breast PET/CT Scanner Prototype
Periodical:Nuclear Science Symposium Record
Index Medicus:
Authors: Y. Wu, K. Yang, L. Fu, V.-H. Tran, J. Qi, J. M. Boone, S. R. Cherry, R. D. Badawi
Yr: 2006 Vol: 4 Nbr: Abs: Pg:2335-2339

Design simulation of a rotating dula-headed PET/CT scanner for breast imaging
Periodical:Nuclear Science Symposium Record
Index Medicus:
Authors: Lamare F, et al and Badawi RD
Yr: 2005 Vol: 3 Nbr: Abs: Pg:1524-1529