Statistics - Love or Hate?

There is no clinical medical imaging paper without statistics. Research can't live without it, but most researchers wish they could. Big Picture is a Welcome Trust magazine, which is directed to teachers and students. Therefore, the magazine has really simple and clear examples. The new issue is about statistics. There is lots of information relevant for medical imaging researchers: 1) the story about the advertisement of a CT scan that was forbidden to broadcast, 2) types of medical studies from the statistic point of view (see picture below) and 3) general concepts about research. See more information here.

The new issue pdf can be read here. The previous issue was about medical neuroimaging, which can be read here.

Procrastination to find the most cited paper in the field of MRI

I have posted recently about the most cited (important?) papers in Medical Imaging in the last ten/five/two years here. Today I look for the most cited papers in the field of MRI. Interesting to note that these 3 papers were published in Neuroimage.

Most cited paper in Radiology, Nuclear Science and Medical Imaging Field about MRI:

- of the last 10 years with 1346 citations:
Ashburner, J., & Friston, K. (2005). Unified segmentation NeuroImage, 26 (3), 839-851 DOI: 10.1016/j.neuroimage.2005.02.018 

This paper is the basis for the SPM framework, one of the most important in the field of MRI. Thus, it is understandable that this paper has a lot of citations, because most researchers who use this framework (and there are a lot, myself included) use this paper in their citations.

- of the last 5 years with 250 citations:
Klein, A., Andersson, J., Ardekani, B., Ashburner, J., Avants, B., Chiang, M., Christensen, G., Collins, D., Gee, J., Hellier, P., Song, J., Jenkinson, M., Lepage, C., Rueckert, D., Thompson, P., Vercauteren, T., Woods, R., Mann, J., & Parsey, R. (2009). Evaluation of 14 nonlinear deformation algorithms applied to human brain MRI registration NeuroImage, 46 (3), 786-802 DOI: 10.1016/j.neuroimage.2008.12.037

I have to say that I am quite surprised by finding this paper on top. Brain MRI registration is nowadays considered almost a solved problem and I don't think there are many people looking into this anymore. However, it is always nice to put in your own paper: "I used this registration, because this paper says it is the best".

- of the last 2 years with 106 citations:
Smith, S., Miller, K., Salimi-Khorshidi, G., Webster, M., Beckmann, C., Nichols, T., Ramsey, J., & Woolrich, M. (2011). Network modelling methods for FMRI NeuroImage, 54 (2), 875-891 DOI: 10.1016/j.neuroimage.2010.08.063

I have talked about brain networks some times in this blog and this paper shows me that this topic has been hot in the last two years. This papers discusses different methods to obtain networks with fMRI data: "Many different methods are being used in the literature, but almost none has been carefully validated or compared for use on FMRI timeseries data."

Procrastination to find the most cited papers in Medical Imaging

Few day ago, I was wondering what were the most cited (important?) papers in Medical Imaging in the last ten/five/two years. The problem was that I didn't know exactly how to find this information. I googled a bit around and I found a way and tried it out. I found also some extra information about the subject:

Published Papers in Radiology, Nuclear Science and Medical Imaging Field:

Citations in Radiology, Nuclear Science and Medical Imaging Field:

It is interesting to note that it is increasing steadily every year. 

Most cited paper in Radiology, Nuclear Science and Medical Imaging Field:

- of the last 10 years
Jan, S., Santin, G., Strul, D., Staelens, S., Assié, K., Autret, D., Avner, S., Barbier, R., Bardiès, M., Bloomfield, P., Brasse, D., Breton, V., Bruyndonckx, P., Buvat, I., Chatziioannou, A., Choi, Y., Chung, Y., Comtat, C., Donnarieix, D., Ferrer, L., Glick, S., Groiselle, C., Guez, D., Honore, P., Kerhoas-Cavata, S., Kirov, A., Kohli, V., Koole, M., Krieguer, M., Laan, D., Lamare, F., Largeron, G., Lartizien, C., Lazaro, D., Maas, M., Maigne, L., Mayet, F., Melot, F., Merheb, C., Pennacchio, E., Perez, J., Pietrzyk, U., Rannou, F., Rey, M., Schaart, D., Schmidtlein, C., Simon, L., Song, T., Vieira, J., Visvikis, D., Walle, R., Wieërs, E., & Morel, C. (2004). GATE: a simulation toolkit for PET and SPECT Physics in Medicine and Biology, 49 (19), 4543-4561 DOI: 10.1088/0031-9155/49/19/007
- of the last 5 years
Klein, S., Staring, M., Murphy, K., Viergever, M., & Pluim, J. (2010). elastix: A Toolbox for Intensity-Based Medical Image Registration IEEE Transactions on Medical Imaging, 29 (1), 196-205 DOI: 10.1109/TMI.2009.2035616

- of the last 2 years
Hricak, H., Brenner, D., Adelstein, S., Frush, D., Hall, E., Howell, R., McCollough, C., Mettler, F., Pearce, M., Suleiman, O., Thrall, J., & Wagner, L. (2010). Managing Radiation Use in Medical Imaging: A Multifaceted Challenge Radiology, 258 (3), 889-905 DOI: 10.1148/radiol.10101157
How to find this information?
Go to Web of Knowledge and follow these tutorial:
http://www.umuc.edu/library/libhow/woshighlycited_tutorial.cfm

The Dead Salmon fMRI experiment

Have you ever heard about the dead salmon fMRI experiment? Me neither, until recently. The study may seem like a waste of money and expertise, but this study has actually open the eyes of the community about one important aspect of fMRI studies: multiple comparisons.

Image from here.

The basic experiment was just to put a dead salmon inside the MRI scanner, perform an fMRI study and analyze results. Since in an fMRI experiment, you have a lot of voxels being compared, there are some voxels that will eventually show up as activated. In the dead salmon fMRI experiment, voxels in the brain and spine showed up as being activated (see image above). Some could say that even if the salmon is dead, there is activity in its brain, but the most likely (scientific) explanation is that those results just happened by chance. To avoid this problems, you should use a multiple comparison correction, which takes into account this problem. After this correction, of course, the dead salmon showed no activated voxels. Although scientifically based, this study stands out for being so funny. It actually won an IgNobel prize in 2012. The original poster is too good to be true:

Image from here.

Original poster: http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf
And posts by the author in his blog: http://prefrontal.org/blog/2009/06/atlantic-salmon-index/

Other Links:
http://www.wired.com/wiredscience/2009/09/fmrisalmon/
http://blogs.scientificamerican.com/scicurious-brain/2012/09/25/ignobel-prize-in-neuroscience-the-dead-salmon-study/
http://boingboing.net/2012/10/02/what-a-dead-fish-can-teach-you.html