Peak maps of principal metabolites for mouse C69, harboring a glioblastoma.

<p>It was scanned at 7 Tesla by PRESS-MRSI with 136 ms echo-time. MRSI data were acquired with Bruker ParaVision 4.0, and Fourier interpolated to 32×32 voxels, with a final PRESS MRSI data grid of 10×10 voxels. Line broadening adjustments and zero order phase correction were carried out. Then, the data were fed into a home-built module for MRSI post-processing, where the 4.5–0 ppm region of each spectrum was individually normalized to Unit Length (UL2). Each map shows the peak height in absolute values of the studied metabolite in each voxel. The white dotted lines highlight the tumoral mass according to T2-W MR images. The scales reflected in the colors coding are in arbitrary units.</p

Sensitivity and specificity for tumor delimitation using PI≤30% as non-tumor.

<p>Sensitivity and specificity (sensitivity/specificity) calculated with respect to the delineation provided by the T2-W image, and also with respect to the source-based labels maps at LTE and STE, for each mouse. The “gold standard” used here is the Ki67 maps. PI>30% represents tumor, while PI≤30% is now taken to represent non-tumor. The last row contains the mean values for each column.</p

Relationship between the Ki67 maps and the source-based labels maps.

<p>T stands for the accuracy between a PI>30% and the tumor area delineated by the source-based labels maps; while N stands for the accuracy between a PI≤5% and the corresponding non-tumor area. The numbers in parentheses correspond to the number of correctly labeled voxels from the total. The last row contains the mean values for each column.</p

Summary of the results for mice C71, C32, C179, C233, C234, and C278.

<p>T2-W images (first row), Ki67 slides (second row), Ki67 maps with PI≤5% (third row), Ki67 maps with PI>30% (fourth row), source contributions maps (interpolated) of the tumoral source calculated at LTE (fifth row), and STE (seventh row), source-based labels maps calculated at LTE (sixth row) and STE (eighth row). Color columns of rows 3 and 4 as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g005" target="_blank">figure 5</a>. Color columns of rows 5 and 7 as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g008" target="_blank">figure 8</a>. Color columns of rows 6 and 8 similar to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g007" target="_blank">figure 7</a>, adding a new color (magenta) to represent the region below the main tumor source 50% threshold (O, “other”) in mouse C278. Please note that C278 does not contain non-tumoral tissue voxels that fulfill the labeling criteria for source calculation according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone.0047824-Simes4" target="_blank">[32]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone.0047824-Simonetti1" target="_blank">[33]</a>.</p

Ki67 preparation from mouse C179.

<p>The connecting region between the two tumor masses is shown enlarged, displaying three 0.1 mm² areas manually sampled. From top (smaller mass) to bottom (main mass), PI: 40%, 21.5%, 24.5%, and 62.7%. White bar at bottom-left corner shows the scale. The insert at the bottom left corner shows the location of the enlarged image (blue rectangle) with respect to the whole brain.</p

Correlations and errors.

<p>Correlations (top row) and errors (bottom row) between the source signals and the average spectra of the labeled areas (as measured by RMSE). Dark gray bars: tumors; light gray bars: non-tumor tissue.</p

Correlations between the sources and the average spectra for mouse C69 at LTE.

<p>Table cells should be read as the correlations between the sources and the average spectra (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g002" target="_blank">figures 2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g003" target="_blank">3</a>) of the tumor/non-tumor areas. The results of the best performing method, for each initialization condition, are highlighted in bold.</p

Sources obtained for the seven mice at STE.

<p>The calculated sources are shown in black color, the average spectra in red, and all the labeled spectra in gray. The sources in the left column represent the tumor, and the ones in the right column mainly represent non-tumoral tissue. Frequencies in the horizontal axis are measured in ppm.</p

Source contributions maps representing the tumor area of mouse C69.

<p>They codify the <i>C</i> values of Eq.2 scaled between 0 and 100. The maps obtained at LTE (left column) and STE (right column) are superimposed over the T2-W reference image. The red color identifies the tumor, while blue identifies non-tumoral tissue. The yellow dotted lines outline the tumor region, as judged from the T2-W image, similar to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g006" target="_blank">figure 6</a>. Top row: 10×10 grid of voxels. Bottom row: the same map interpolated. Color columns on the right hand side of the maps indicate <i>C</i> scale in percentage.</p

Source-based labels maps generated for mouse C69.

<p>The maps obtained at LTE (left) and STE (right) are superimposed to the T2-W reference image. The red color identifies tumor (T), blue identifies non-tumor (N), and black represents ‘undecided’. The color intensities shown in the scale bar on the right hand side correspond to the magnitude of the correlation values between the spectra of the voxels and their representing source. The yellow dotted lines outline the tumor region, as judged from the T2-W image, similar to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047824#pone-0047824-g006" target="_blank">figure 6</a>.</p