A comparison of breast lesion imaging capability of a whole-body PET camera and a brain/breast PET camera

PET scanners have been used for the diagnosis, staging, and management of a variety of malignancies, including breast cancer. However, despite the powerful molecular imaging nature of PET, the resolution and sensitivity of current PET cameras practically limit the detection of breast lesions to relatively large lesion (≫7 mm) and high tracer uptakes. Improvements in spatial resolution and sensitivity of PET cameras are essential for early detection of small breast lesions (≪5 mm) which is critical to the early detection and successful treatment of breast cancer. Recently, we have completed the construction of a high-resolution and high-sensitivity PET camera (HOTPET). HOTPET has spatial resolution of better than 3 mm and can operate in the whole-body mode or breast/brain mode. In the whole-body mode HOTPET has transverse field-of-view (FOV) of 60 cm and axial FOV of 13 cm. In the breast/brain mode it has transverse FOV of 39 cm and axial FOV of 21 cm. We have performed a detailed phantom study of the breast lesion detection capability of HOTPET in both modes using a breast phantom with lesion insert. The breast phantom was attached to a torso phantom with lung, liver, spine and cardiac inserts. We scanned 2 small lesions with diameter of 4.95 and 7.86 mm for several lesion activity contrasts. The standard uptake value (SUV) of lesion was in range of 1 to 10. The SUV of the breast, torso and heart were 0.8, 1, and 4, respectively. Visual inspection of the images showed that the small 4.95-mm lesion with SUV of 2.5 or higher was observable in HOTPET breast mode data and with SUV of 5.5 or higher in the whole-body mode data. The 7.86 mm lesion was observable with SUV of 1.75 in breast mode and SUV of 2.5 in whole-body mode.