HU000123Q0013 P00001 QandA.pdf

HU000123Q0013 P00001 Q&A

1. With respect to the available FOV, the use of Rabbits for PET/SPECT imaging is extremely rare. Is the ability to image rabbit a firm system requirement or would it be viewed as an advantage only assuming rodent and ferret models can be imaged in the system?

We require the ability to scan animals larger than a rat or ferret because of a concept called translational science. We are trying to accommodate the animal spectrum we have at USU.

2. The requirements state that the “coincidence” PET and CT modalities must be integrated under the same hood/instrument. Regarding the requirement that ideally the SPECT would be on a separate gantry for simultaneous scanning, does this mean you would accept a bid for 2 separate instruments from one vendor, one for PET/CT and the other for SPECT/CT?

The term “coincidence” PET means that it is true PET. Some vendors refer to their high energy SPECT in their dual energy system as the PET part and it is not. We would ideally like it to have a system where the PET/CT are together in one unit with a separate SPECT scanner with it. The animal cradles need to be interchangeable between these units. That just allows us to have a better workflow as we could run PET/CT and SPECT at the same time. Both units need to be able to scan rabbits. We do not need a separate SPECT/CT equipment.

3. Would you anticipate significant performance decrease in terms of PET sensitivity when going from a 80 mm to 110mm trans axial FOV for rodent models, perhaps as much 33%, requiring significantly higher doses and longer scan times for all mice and rat studies, and which are the most dominant specimen for all preclinical PET and SPECT studies?

The PET detectors with thick LSO crystals can not only enhance the sensitivity of the PET imaging but also gives us better quantification at low level activity. The overall resolution of the large transaxial FOV will not be compromised. On contrary, having a large FOV will enable us to image multiple small animals, up to 4 mice or 2 rats (increasing throughput), better utilization of the expensive radiotracers (instead of having to image one animal at a time, while the radiotracers decay) and also image larger animals like NHP and ferrets.

4. Would a 150mm axial field of view be more effective for whole body rat studies versus a 100mm axial FOV which would require multiple bed positions/scans to image a whole rat body increasing scan times significantly?

The CT imaging technology has been refined over the years. The CT images can be acquired very quickly now and at a very low dose of only 1mSv exposure for a whole mouse. Though the axial FOV may be larger for one of the CT scanners, the overall resolution is only 52um compared to the other where the overall resolution is 30 um. It is better to get precision imaging than large axial FOV.

5. Would bed compatibility between the PET/CT system and the Biospec 7T MRI at USUHS be considered useful to open up PET/MR applications?

Bed compatibility with MRI is not necessary as we have digital fusion technology for our images already without this feature.