Clinically, DTT is used for a wide range of applications for diagnostic and therapeutic purposes. DTI remains the main dMRI technique for clinical practice to circumvent the issue of long imaging times associated with DTT. Many clinical applications were broadly performed for the analysis of brain development [125, 215] or change due to aging  and for diagnosing various types of brain disorders [192, 202]. Examples of three applications are shown with images .
Neurosurgical Planning and Intraoperative Navigation
A case involving a well-demarcated tumor without perifocal edema in the left medial temporal area is displayed in Fig. 3.25. In addition to the tumor volume, the corticospinal tract was visualized. The posterior limb of the internal capsule was used for tracking seed areas at the high-intensity area on the T2-weighted (b = 0)
Fig. 3.24 Global tractography examples 
Fig. 3.25 Brain tumor. Left: 3D rendering of the pyramidal tracts, well-demarcated tumor, and brain surface extracted from T2-weighted image data. Right: Coronal section of T2-weighted image with tractography 
Fig. 3.26 Brain tumor of mild invasion: Tractography stereo pair 
image. The precentral sulcus can be recognized by the precentral knob sign, and other signs are employed as the tracking target area. Significant deformation with slight change of diffusion anisotropy in the color-encoding scheme was observed at the tract while the patient shows only mild weakness of the arm. Figure 3.26 shows a case of left superior frontal tumor without significant perifocal edema. The visualized pyramidal tract displays rounded deviation and minimal change of anisotropy.
A 15-h acute infarction in the deep white matter very close to the pyramidal tract is shown in Fig. 3.27. No significant difference in diffusion anisotropy is observed between the sides, and the patient recovered completely.
Fig. 3.27 Acute infarction: Stereo pair of tractography by 3D rendering including infarction volume 
Abnormality of White Matter Anatomy (Agenesis of Corpus Callosum)
A case of complete agenesis of the corpus callosum without commissure fibers is visualized via tractography in Fig. 3.28. When fiber tracking is started from the portion where the commissure fibers are located in normal subjects, thick fibers in the anteroposterior direction can be tracked while the Probst bundle running along the anteroposterior axis was visualized in this case.