[BIC-announce] message from Dr. Jean-Paul Soucy - To PET users at the BIC

[Jennifer Chew, Ms.]

"To all investigators using PET at the BIC:
 
As of July 1st, 2008, the new HRRT scanner is slated to become
operational for research protocols.  As most of you already know, that
scanner offers significantly better spatial resolution than the ECAT HR+
currently being used (approximately 2.2 mm vs approximately 4-5 mm FWHM
at the centre of the field, as a rough comparison).  To some, this might
suggest that everybody should start using the new scanner for protocols
being initiated after that date. However, there are important issues
that should be well understood by all:
 
1) The HRRT scanner is a "high-maintenance" machine: regular (most
likely, 3 to 4/year) calibrations/normalisations are required, which
each last close to 3 weeks, meaning that significant downtime is
unavoidable for any protocol running on that system.
2) We know that the scanner shows significant shifts in many of its
parameters, and is likely to do so for a relatively long period of time
(possibly up to 24 months after its first "power-on").  It is currently
very difficult to quantify the magnitude of those shifts over time, but
they could very well result in difficult-to-interpret data, especially
in studies where subjects are evaluated at different time points.
3) We have no clear long term track record of its overall reliability,
except that we have had to repair some components a number of times
already, and have observed "surprising" software issues.  This reflects
the general experience of all centres using this scanner. Therefore,
again, some downtime might result from breakdowns that could occur with
a higher than expected frequency.
 
What this means is that if you see a very clear benefit in operating at
a significantly higher resolution, doing research with the HRRT is a
reasonable option.  However, if the ECAT HR+ provides you with usable
results, it offers a degree of reliability which might not be found, at
least initially, on the HRRT.
 
Protocols that will be submitted to the PET Working Committee must from
now on specify which system will be used (the appropriate forms will be
modified shortly to reflect that new requirement).  The Committee will
specifically evaluate which of the two seems most appropriate for any
given project and will make recommendations to investigators on that
topic.
 
Thank you in advance for your collaboration in bringing the new scanner
on line.
 
Jean-Paul Soucy, MD, MSc
PET Unit Coordinator
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