Measuring Fractional Anisotropy of the Corpus Callosum Using Diffusion Tensor Imaging: Mid-Sagittal versus Axial Imaging Planes

한글 요약

확산텐서영상(DTI)으로 뇌량의 분할 이방성(FA)을 측정할 때 촬영 단면의 방향이 결과에 영향을 주는지를 살핀 연구입니다. 기존 연구들은 대부분 비교적 두꺼운 축상 단면으로 촬영해 부분 용적 효과 때문에 FA를 과소평가할 가능성이 있었으므로, 건강한 지원자를 3.0T MRI에서 정중 시상면과 축상면 두 방식으로 촬영하여 뇌량의 다섯 구역별 FA 값을 비교했습니다. 그 결과 뇌량의 대부분 구역에서 정중 시상면 촬영의 FA 값이 축상면보다 유의하게 높았고, 특히 감각 영역에 해당하는 구역에서 차이가 컸습니다. 따라서 뇌량의 미세구조를 정확히 측정하고 환자와 건강인을 비교하는 연구에서는 정중 시상면 DTI가 더 바람직할 수 있습니다.

OBJECTIVE: Many diffusion tensor imaging (DTI) studies of the corpus callosum (CC) have been performed with a relatively thick slice thickness in the axial plane, which may result in underestimating the fractional anisotropy (FA) of the CC due to a partial volume effect. We hypothesized that the FA of the CC can be more accurately measured by using mid-sagittal DTI. We compared the FA values of the CC between the axial and mid-sagittal DTI.

MATERIALS AND METHODS: Fourteen healthy volunteers underwent MRI at 3.0 T. DTI was performed in both the mid-sagittal and axial planes. One 5-mm mid-sagittal image and twenty-five 2-mm axial images were obtained for the CC. The five regions of interest (ROIs) that included the prefrontal (I), premotor and supplementary motor (II), motor (III), sensory (IV) and parietal, temporal and occipital regions (V) were drawn along the border of the CC on each sagittal FA map. The FA values obtained from each region were compared between the two sagittal maps.

RESULTS: The FA values of all the regions, except for region V, were significantly increased on the mid-sagittal imaging. The FA values in region IV were significantly underestimated on the mid-sagittal image from the axial imaging, compared with those in the regions I and V (p = 0.037 and p = 0.001, respectively).

CONCLUSION: The FA values of the CC were significantly higher on the mid-sagittal DTI than those on the axial DTI in regions I-IV, and particularly in the region IV. Mid-sagittal DTI may provide more accurate FA values of the CC than can the axial DTI, and mid-sagittal DTI may be more desirable for studies that compare between patients and healthy subjects.