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\begin{enumerate}
\item Roche et al 2014 - was about partial volume estimation using a bayesian MAP formulation that extends the mixel model. Our segmentation results do not account for partial voluming effects. In the text we
have added:
"Another factor not accounted for in our segmentation results was the effects of partial voluming, which adds uncertainty to tissue volume estimates. In (Roche 2014), researchers developed a method to more accurately estimate partial volume effects using only T1-weighed images from the ADNI dataset, which resulted in higher classification accuracy between Alzheimer’s disease (AD) patients and mild cognitively impaired (MCI) patients from normal controls (NL)."
\item Wolz et al 2014:
The LEAP algorithm
was run on hippocampal volumes,
and compared between 1.5T and
3T 3T. They found small bias (1.17\% mean signed difference) between field strengths on ADNI data. Jovicich 2009 - they found that test-retest reproducibility does not change much cross platforms and field strengths. In the discussion section
I've we have added:
"Even though we did not standardize the protocols and scanners within this study, the consortium is unbalanced in that there are 16 3T
scanners scanners, 11 of which
11 are Siemens. Of the Siemens 3T scanners, there is little variability in TR,
TE TE, and TI, however, there is more variance in the use of parallel imaging, the number of channels in the head coil (12, 20 or 32), and the field of view.
We Similar to the findings of (Jovicich 2009), we could not detect differences in scan-rescan reliability between field
strengths, similar to the findings of (Jovicich 2009). strengths. Wolz and colleagues
also could not detect differences in scan-rescan reliabilities of the hippocampus volumes estimated by the LEAP algorithm, but they detected a small bias between field
strengths, where strengths. They found that the hippocampus volumes
in measured from the 3T ADNI scanners were 1.17 \% larger than
those measured from the 1.5T (Wolz 2014). A two-sample T-test with unequal variances was run between the scaling factors of the 1.5T versus 3T
scanners, and we scanners. This test could not detect differences in any ROI except for the left- and right- amydgala. We found that the scaling factors were lower
for the 1.5T scanners than
for the 3T scanners
(.9 (0.9 versus 1.02),
meaning suggesting that the amygdala volume estimates from the 1.5T were larger than those of the 3T.
However, It should be noted that this interpretation is limited due to the small sample size of 1.5T scanners in this consortium."
\item Wyman et al. 2013:
I'm We are not sure if this is the correct paper
you are the reviewer is referring to, but this paper emphasized the use of ADNI's standardized data sets, which they say add (1) Greater rigor in reporting (2) The ability to compare various techniques side-by-side 3) The ability to evaluate robustness of a given technique and 4) The ability to replicate methods. In order to enable other researchers to compare our methods, evaluate robustness and replicate our study, we
will provide, have provided, in the supplemental materials, the raw data on MRI volumes produced from Freesurfer, along with the python and R code to calculate scaling factors, leave-one-out calibration, and between-/within- site ICC.
\item Whitwell et al. 2012: Found different rates of hippocampal atrophy in the ADNI cohort than the Mayo Clinic Study of Aging cohort, even though there were no differences in hippocampal volumes between the matched cohorts. This
is was attributed to
the sampling of different populations rather than differences in
hippocampal volumes due to differences in acquisition parameters. In the text
I we have added:
"The other limitation of this study is that we assumed that subjects across all sites will come from the same population, and that stratification occurs solely from systematic errors within each site. In reality, sites may recruit from different
populations, populations and the true disease effect will vary even more.
\textbf{For For example, in a comparison study between the matched ADNI cohort and a matched Mayo Clinic Study of Aging cohort, researchers found different rates of hippocampal atrophy even though no differences in hippocampal
volumes volume was detected (Whitwell 2012). This could be attributed to sampling from two different
populations.} populations. This added site-level variability requires a larger site-level sample size, for an example of modeling this, see (Han 2011). "
\end{enumerate}