Perelman School of Medicine at the University of Pennsylvania

Physics and Instrumentation Group

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PennPET Explorer

(PI: Joel S. Karp)

PennPET Explorer Website

The PennPET Explorer is a whole-body imager that can image the major body organs simultaneously with higher sensitivity than that of commercial devices. The device is scalable in axial length and was initially tested in prototype form with 3 rings and axial field-of-view (AFOV) of 64 cm. (see figure). The technology of the PennPET Explorer is based on the Philips silicon photomultiplier, and the system achieves a time-of-flight (TOF) resolution of 250 ps and a spatial resolution of 4.0 mm (FWHM). (Karp et. al. 2019) We completed a series of pilot human imaging studies with each study designed to test specific capabilities of the device. ( ) We demonstrated the ability to scan for shorter duration or, alternatively with less activity, without a compromise in image quality. In clinical patients, the PennPET Explorer better delineates extent of FDG-avid disease. Delayed images, up to 10 half-lives with FDG, reveal biological insight and support the ability to track biologic processes over time. Dynamic imaging studies capture relatively noise-free input functions for kinetic modeling applications. Additional studies with experiemental research radiotracers illustrate the benefits from the combination of large axial coverage and high sensitivity. The PennPET Explorer was expanded to 5 rings (112 cm AFOV) and installed in the Stemmler Building with an in-line CT scanner, where it has been fully operational since summer, 2020.

An example of a human study imaged with FDG while the scanner was configured with 3 rings (64 cm AFOV) is shown below. The first scan, acquired at 1.5 hr post-injection. illustrates the excellent image quality – low noise with high structural detail - achieved in a short scan with a single-bed position. The second scan, acquired at 19 hr post-injection illustrates that the very high sensitivity of the PennPET Explorer enables measurement of both fast and slow kinetics and that valuable information can be extracted from the radiotracer distribution after more than 10 half-lives.

1.5 hour post-injection
19 hour post-injection

Also shown is a dynamic FDG study to illustrate the ability to capture fast kinetics. The movie shows the dynamic sequence of FDG uptake over an hour after the bolus injection and plots the time-activity curves of the major organs.



Selected Publications

  1. Pantel AR, Viswanath V, Daube-Witherspoon ME, Dubroff JG, Muehllehner G, Parma MJ, Pryma DA, Schubert EK, Mankoff DA, Karp JS. PennPET Explorer: Human imaging on a whole-body imager.  J Nucl Med (in press).
  2. Karp JS, Viswanath V, Geagan MJ, Muehllehner G, Pantel AR, Parma MJ, Perkins AE, Schmall JP, Werner ME, Daube-Witherspoon ME. PennPET Explorer: Design and preliminary performance of a whole-body imager. J Nucl Med September 2019. [Link]
  3. Viswanath V, Daube-Witherspoon ME, Schmall JP, Surti S, Werner ME, Muehllehner G, Geagan MJ, Perkins AE, Karp JS. Development of PET for total-body imaging. Acta Phys Polonica, vol. 48, pp. 1555-1566, 2017. [Link]
  4. Simon CR, Jones T, Karp JS, Qi J, Moses WM, Badawi RD. Total-body PET: maximizing sensitivity to create new opportunities for clinical research and patient care. Journal of Nuclear Medicine 59.1 (2018): 3-12.