RIDER Phone Call, June 6, 2008

Geoff McLennan, Chuck Meyer, Sam Armato, Binsheng Zhao, Tony Reeves,
Mike McNitt-Gray, Grace Kim, Daniel Barboriak, Luc Bidaut, Nick Petrick,
Lisa Kinnard, Marios Gavrielides, Chuck Fenimore, Paul Kinahan, Ed
Jackson, Larry Clarke, Barbara Croft, Reinhard Beichel at U Iowa

There is a discussion document that Chuck Meyer sent out this AM.

Mike put together list of datasets and how they might be used, and how
they might be used to measure the effect size vs the noise. We need to
focus on the variance issues.

Mike:

File is **Summary of RIDER Data and Research Questions**

Wrote this to see what was available and what we wanted to tackle.

1.  test- retest

2.  accuracy and bias, other parameters

3.  patient change studies

Different modalities and rich dataset.

Taxonomy to organize it; ran it by Grace Kim, a statistician.

Larry -- NCI is concentrating on repeat measurements, to find variance
and bias of repeat measurements, for September report.

Mike -- good to be focused on what to do first.

Larry -- it is there as a public resource. By September develop repeat
measurement criteria. The e-mail from SAIC with contract says Sept 13
deadline, with Sept 25 drop dead date for a progress report. Would hope
that the data used in the report could be sent to NCI and resident on
NCIA.

Geoff -- so focus is on A mostly.

Chuck -- there are several data sets.

Tony -- working on several data sets, but not sure whether they would be
part of the effort. Are doing repeat studies. Have 28 scans that have
repeat scans, and some patients with airway disease with 2 month
interval studies.

Chuck -- most of us are hung up on IRB approvals.

Tony -- think it is not a problem.

Chuck -- so there are 5 lines and

Paul -- the RIDER data was in Group B? There are 3 data sets,
coffee-break on 3 vendors' instruments of the phantom which is moved and
re-scanned, same phantom scanned at about a dozen different sites, and
third is serial studies of patients, deidentified.

Mike -- his form is in terms of the question being asked.

Geoff -- so at least one study in B, coffee-break, gives reproducibility
and bias for 3 different vendors' instruments.

Paul -- each scanner has a different set of biases. It is not as
controlled as he would like because it would be even better to do repeat
studies at each site.

Mike -- the FDA study also has their phantom scanned on different CT
scanners.

Binsheng -- so that also means 2 different kinds of studies in the ..
and FDA study could be moved to phantom study under repeatability.

Tony -- all the accuracy and bias category are repeatability studies.

Mike -- did the FDA move the phantom between data sets?\\

Lisa -- yes, because the scanners were shared with other users, and the
phantom had to be moved.

Paul -- did 3 expts, not moving phantom, moving it by 1 mm intervals,
and walking around with it between imaging sessions. Did notice that
there was a measurable increase in the variance as more movement was
performed.

Larry -- this is all fine in that measurements do not need to all be
taken in this time period, but that the experiments should be proposed.

Mike -- the discussion was helpful, because we need to know what the
significant sources of variance are.

Mike -- question for Ed Jackson -- will there be a status for MR phantom
to have some repeatability?

Ed Jackson -- IRAT DCE-MRI phantom is out being scanned at various sites
right now. Do expect there will be some data on test-retest on that
phantom.

Grace Kim -- there is more than question here, as this relates to
patient studies. There are 2 parts to repeatability.

Mike -- keep group A as the patient studies. In all studies under B
there will be between site data.

Geoff -- are repeatabity, reproducibility and variance all the same?

Chuck -- we want to see patient's change and be able to compare it to
the variance that represents the noise.

Paul -- is this all broken down by the acquisition chain steps? For NM
studies, statistics are a big issue. A useful part 2 would be a
breakdown by the steps in the imaging chain.

Chuck -- we need to tie to an analysis of variance.

Mike -- we did not do this, because this is a breakdown by imaging
modality. The datasets that we have will limit what kind of analysis we
can carry out.

Paul -- could maybe have a block diagram of the steps. Calibration of
DCE MRI is a big issue. In the nuclear case, stochastic variation is a
big issue.

Mike -- FDA studies were done at different dose levels.

Chuck -- when we do the coffee-break expt with a patient, we will have
all the components.

Paul -- there are examples of these patient experiments in the
literature.

Geoff -- is it worth developing a script of variance and showing how
these are examples.

Mike -- good idea. QIB meeting a couple of weeks ago would suggest this.
He wrote down "machine" and "analysis".

Daniel -- looking at spreadsheet: you get a repeatability out of a
phantom study. If you see larger effects in a patient study, then it may
be real. The segmentation may not be the same from one study to the
next. You may need to do repeatability before treatment and after
treatment, because they may not be the same. Lesions may be more or less
homogeneous after treatment.

Chuck -- and for DCE one issue is deciding what the input function is.

Daniel -- and it is 2 different questions whether 2 different scanners
are used or whether the patient is moved around in between studies.

Larry -- we want to share the data, but there is no expectation of
re-analysis of data. Share the analysis.

Geoff --different modalities, different lesions, different imaging
circumstances.

How would we develop a variance lexicon? Would it be useful?

Chuck -- not so interested in the lexicon, but in the coffee-break exam
which represents the whole null-hypothesis.

Paul -- maybe break the exam down into the parts of the chain. Then we
look at the variance of the different aspects.

Chuck -- we are gamblers, looking for a large effect size and reduced
noise.

Mike -- would like a taxonomy or something. We need to ID different
sources of variance so we can say what we are addressing and what we are
not.

Chuck -- subgroups are the way to address this.

Chuck F -- FDA is constructive in their approach to the CT and the
phantom; they have varied a number of things which they think might be
important. At the end of the day, we may have identified some holes and
be able to point the way to new data we need.

Geoff -- revise document.

Paul -- each person working with a specific modality could send an
analysis of the major effects for his/her modality. You need to know
what is going on with any modality. This could be 1 page. He is thinking
of a 1-page flow chart. Send it to Chuck and Mike and then it can be
incorporated.

"The truth is out there -- variance of MRI!!!"

Mike -- 1 more step. Going through Daniel's slides, looking for sources
of variance and what kind of analysis might be recommended. Send
holistic approach -- patient, machine, image analysis.

Chuck -- documents included an Excel spread sheet, and a couple of
articles about reducing multicenter differences, primarily for DCE MRI

Larry -- it would be helpful to circulate other documents you know about
that cover this topic.

Next call in a couple of weeks.