The FAT was reconstructed using four different algorithms for each patient in the study. The fiber tracts were visualized using DSI-studio to demonstrate the anatomical accuracy of the reconstruction results, and the CST fiber bundles were overlaid with the FA image.
Among the patients, 14 were diagnosed with primary tumors, specifically glioblastoma multiforme WHO IV (IDH-mutant or IDH wildtype), and 5 patients had astrocytoma anaplasticum WHO III. Additionally, 19 patients had metastatic tumors, including 10 with lung cancer metastasis, 6 with colorectal cancer, and 3 with melanoma.
Table 1 summarizes the average values of FA and MD. The average values of the number of fibers, tract volume, and length of tracts are provided in the supplementary material.
Significantly higher volumes (p < 0.001; 40806.7 ± 9284.5 vs. 52831.7 ± 2399.0; treated group vs. control group) and numbers of FAT tracts (p < 0.001; 1548.5 ± 397.1 vs. 2231.7 ± 119.5; treated group vs. control group) were observed when the ROI was set at the superior frontal gyrus (SFG) with an endpoint at the inferior frontal gyrus pars opercularis (IFG op), compared to other ROIs (all p < 0.05) in both the control and treated groups. Using ROI-2 at the SMA with an endpoint at the inferior frontal gyrus pars triangularis (IFG tra) resulted in over 90% fewer fibers and a smaller volume of FAT.
The longest FAT, in both the study and control groups, was obtained when selecting ROI 1 (superior frontal gyrus) with an endpoint at the inferior frontal gyrus pars triangularis (9.41; SD ± 3.9 vs 89.7; SD ± 4.0; study group vs. control group).
In the study group, the number of fibers and volume of FAT were lower than in the control group, regardless of the chosen method for FAT plotting. Additionally, a significant statistical difference (p < 0.05) in the number of fibers was identified between patients in the control and study groups, in each of the selected projections. Regarding the volume of the tract, statistical significance was achieved in the SMA-IFG tri projection (p < 0.001; 464.8 ± 92.5 vs. 632.3 ± 89.6; study group vs. control group), SMA-IFG op projection (p < 0.001; 2738.3 ± 1374.7 vs. 5028.3 ± 1238.1; study group vs. control group), and SFG-IFG op projection (p < 0.001; 40806.7 ± 9284.5 vs. 52831.7 ± 2399.0; study group vs. control group). However, in terms of fiber length, the threshold of statistical significance was reached only in the SMA-IFG projection (p = 0.045; 81.8 ± 6.4 vs. 86.5 ± 5.7; study group vs. control group).
The FA value was statistically significantly lower (p < 0.05) in the study group, while the MD value was statistically significantly higher in this group in each method of FAT determination. The exact data of the above parameters have been collected and presented in table no 1 however, no statistically significant differences were found between the results for the FA parameter in people from the glioblastoma and metastasis groups, regardless of the selected projection.. Comparison of FA and MD values depending on ROIs and endpoints in the group of patients with primary tumors and metastases was presented on Table 2.
Table 1
Comparison of FA and MD values in the study and control groups depending on the ROI and endpoints.
| MD study group | MD control group | p value | FA study group | FA control group | p value |
\(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me |
SFG-IFGop | 0,77 | 0,13 | 0,72 | 0,49 | 0,06 | 0,50 | < 0,001 | 0,42 | 0,05 | 0,42 | 0,69 | 0,09 | 0,69 | < 0,001 |
SFG-IFG tra | 0,78 | 0,09 | 0,77 | 0,48 | 0,07 | 0,49 | < 0,001 | 0,42 | 0,04 | 0,42 | 0,74 | 0,06 | 0,74 | < 0,001 |
SMA-IFGop | 0,75 | 0,09 | 0,72 | 0,48 | 0,07 | 0,49 | < 0,001 | 0,44 | 0,05 | 0,46 | 0,76 | 0,07 | 0,78 | < 0,001 |
SMA-IFG tra | 0,77 | 0,06 | 0,79 | 0,47 | 0,08 | 0,49 | < 0,001 | 0,46 | 0,06 | 0,46 | 0,76 | 0,07 | 0,79 | < 0,001 |
Comparison of the examined parameters between patients with glioblastoma and metastasis revealed statistically significant differences for MD (p < 0.001) regardless of the selected projection. The specific values are presented in Table 2. However, no statistically significant differences were found for the remaining parameters in the projections used, except for the SMA-IFG op projection. In this projection, statistically significant differences were also identified in the number of fibers (p = 0.028; 179.6 ± 90.0 vs. 304.6 ± 106.5; glioblastoma vs. metastasis) and tract volume (p = 0.032; 2040.8 ± 1042.0 vs. 3535.4 ± 1323.9; glioblastoma vs. metastasis).
Table 2
Comparison of FA and MD values depending on ROIs and endpoints in the group of patients with primary tumors and metastases.
| MD GBM group | MD metastasis group | p value | FA GBM group | FA metastasis group | p value |
\(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me | \(\overline{x}\) | SD | Me |
SFG-IFGop | 0,66 | 0,04 | 0,67 | 0,89 | 0,05 | 0,89 | < 0,001 | 0,42 | 0,06 | 0,41 | 0,42 | 0,03 | 0,42 | 0,985 |
SFG-IFG tra | 0,70 | 0,03 | 0,70 | 0,86 | 0,05 | 0,84 | < 0,001 | 0,42 | 0,04 | 0,43 | 0,42 | 0,03 | 0,41 | 0.874 |
SMA-IFGop | 0,68 | 0,04 | 0,69 | 0,84 | 0,04 | 0,82 | < 0,001 | 0,44 | 0,06 | 0,43 | 0,45 | 0,03 | 0,46 | 0.862 |
SMA-IFG tra | 0,72 | 0,04 | 0,71 | 0,82 | 0,03 | 0,82 | < 0,001 | 0,46 | 0,08 | 0,45 | 0,46 | 0,03 | 0,46 | 0.875 |
Based on the analysis of the results obtained in the group of cancer patients, statistically significant differences (p < 0.05) were observed between the results recorded in the SFG-IFG op and SMA-IFG op ROIs for the parameters related to the number of fibers (p < 0.001; 1548.5 ± 397.1 vs. 237.9 ± 114.3; SFG vs. SMA) and tract volume (p < 0.001; 40806.7 ± 9284.5 vs. 2738.3 ± 1374.7; SFG vs. SMA). However, the parameters MD, FA, and fiber length did not reach the level of statistical significance. A strong positive correlation was identified for MD using Pearson's rank correlation test (0.9 < R < 1.0), and it reached statistical significance (p < 0.001).
In the same group, when analyzing data obtained in the SFG-IFG tra vs. SMA-IFG tra ROIs, statistical significance (p < 0.05) was observed for the number of fibers (p < 0.001; 470.1 ± 106.8 vs. 24.8 ± 11.0; SFG vs. SMA) and tract volume (p = 0.001; 6288.5 ± 3790.3 vs. 464.8 ± 92.5; SFG vs. SMA), as well as for fiber length (p = 0.008; 91.41 ± 3.92 vs. 87.18 ± 6.544; SFG vs. SMA) and FA (p = 0.037; 0.42 ± 0.004 vs. 0.46 ± 0.006; SFG vs. SMA). However, MD and fiber length analysis results in the above ROIs did not reach statistical significance. Additionally, two statistically significant (p < 0.05) positive correlations were identified for fiber length (p = 0.022) and MD (p < 0.001).
In the control group, comparisons were also made between the results obtained in the SFG-IFG op and SMA-IFG op ROIs. Differences exceeding the threshold of statistical significance (p < 0.05) were noted for the number of fibers (p < 0.001; 2231.7 ± 119.5 vs. 446.1 ± 59.2; SFG vs. SMA) and tract volume (p = 0.001; 52831.7 ± 2399.0 vs. 5028.3 ± 1238.1; SFG vs. SMA). However, when analyzing data obtained in the SFG-IFG tri and SMA-IFG tri projections, statistically significant differences (p < 0.05) were observed for the number of fibers (p < 0.001; 804.6 ± 143.1 vs. 40.9 ± 7.0; SFG vs. SMA), tract volume (p < 0.001; 8510.2 ± 1040.9 vs. 632.3 ± 89.6; SFG vs. SMA), and fiber length (p = 0.004; 89.69 ± 3.97 vs. 86.64 ± 6.08; SFG vs. SMA). No statistically significant differences were found for the remaining parameters.