Spencer Caton Behr MD, Presenter: Research Grant, General Electric Company

Thomas A. Hope MD, Abstract Co-Author: Speaker, Guerbet SA Research Grant, General Electric Company

Lorenzo Nardo MD, Abstract Co-Author: Nothing to Disclose

Vahid Ravanfar, Abstract Co-Author: Research Grant, General Electric Company

Emily Verdin, Abstract Co-Author: Research Grant, General Electric Company

Dragana Savic, Abstract Co-Author: Nothing to Disclose

Randall A. Hawkins MD, PhD, Abstract Co-Author: Nothing to Disclose

Youngho Seo PhD, Abstract Co-Author: Research Consultant, sanofi-aventis Group

Solid-state photomultiplier (SSPM), coupled with fast scintillators, can operate in the strong magnetic field and still maintain time-of-flight (TOF) PET capability. The highly-sensitive large filed-of-view (25-cm axial) SSPM-based TOF-PET integrated with 3T-MRI (TOF-PET/MRI) offers the possibility of rapid, diagnostic quality PET studies potentially as fast as 1 minute per bed compared to 3 minutes for the current clinical PET systems. This shortened PET scan time can allow for both rapid full-body PET studies as well as for dedicated, organ-specific MR and PET protocols in less than 60 minutes.

8 consecutive TOF-PET scans at 4 minutes per bed were acquired on the TOF-PET/MRI system in listmode, 120 to 180 minutes after intravenous administration of 370 MBq FDG. Listmode PET data were replayed and reconstructed for 1- and 2-minute intervals in addition to the prospective 4-minute per bed reconstruction with TOF and 4 minutes without TOF. Reconstructed MIP images were compared to the PET from the PET/CT for qualitative assessment. Qualitative assessment by three radiologists; one with over 20 years of experience, second with over 8 years of experience and another was a resident with 3 years of experience. Scoring was 1 to 5, 1 for non-diagnostic, 3 equal to PET from PET/CT and 5 superior quality/new lesions detected.

Qualitative scores were similar between radiologists: 4 minute without TOF was $ and 1,2, and 4 minute with TOF was 3.3, 3.4 and 4.1, respectively.

Even with the significant loss of FDG signal from the 2-hour delayed acquisition, the new TOF-PET/MRI system has high enough sensitivity and resolution to allow for full body diagnostic PET at 1 to 2 minutes per bed station. However clinical PET scans are routinely performed at 60 minutes after injection, which will further improve the signal to noise. Therefore, these findings support the hypothesis that this TOF-PET/MRI can perform diagnostic PET studies as short as 1 minute per bed and allow ample time for focused MRI and PET protocols. In addition, this ultrafast whole-body PET capability may be helpful for patients who have difficulty laying flat such as pediatric or patients with back pain.

The shortened scan time due to SSPM and TOF PET technology can allow for both rapid full-body PET studies as well as for dedicated, organ-specific MR and PET protocols in less than 60 minutes.

Behr, S, Hope, T, Nardo, L, Ravanfar, V, Verdin, E, Savic, D, Hawkins, R, Seo, Y, Ultrafast PET Acquisition Using Solid-state Photomultiplier-based PET Camera under a Strong Magnetic Field.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008856.html