MRI における下顎骨骨髄の加齢的変化
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概要
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The purpose of this study is to clarify age-related changes of the mandibular bone marrow using MR imaging. This study involved 95 cases (males : 51, females : 44) of MR imaging randomly selected with no hematopoietic or bone disease in the mandible. The youngest subject was a 6-month-old boy and the oldest subject was an 80-year-old male. The cases were categorized as 30 mandibular symphysis regions, 66 mandibular premolar regions, 70 mandibular molar regions, and 63 mandibular ramus center regions. The T1-weighted MR images of bone marrow used in this study were obtained utilizing the spin echo technique. The scanning parameters were TR 500 msec, TE 15 msec, 8 mm section thickness and 10 mm section intervals for adults, 5 mm section thickness and 6 mm section intervals for children. Bone marrow images were sectioned into the sagittal section of the mandibular symphysis, coronal section of the mandibular premolar and molar regions, and horizontal section of the center of the mandibular ramus. MR signal intensity of the bone marrow on T1-weighted MR images were classified into three grades : (a) low, (b) high, and (c) mixed (high and low). The results obtained were as follows : 1. The varied signal intensities of the 30 T1-weighted MR images of the bone marrow in the mandibular symphysis : (a) 16 (53%) showed a low signal intensity. Of these 16, 5 were in the 61-70 age group and 4 were in the 0-10 age group. (b) 11 (37%) showed a high signal intensity. The high signal intensity was observed in other groups except for those in the 11-20 and 21-30 age groups. (c) 3 (10%) showed a mixed signal intensity. These 3 were the lowest among the three grades of signal intensity. 2. The varied signal intensities of 66 T1-weighted MR images of bone marrow in the mandibular premolar region : (a) 16 (24%) showed a low signal intensity. Of the 16 subjects, 8 in the 61-70 age group had the highest number of low signal intensity of all groups. (b) 23 (35%) showed a high signal intensity. Of these 23, 6 in the 41-50 age group and 6 in the 61-70 age group were of the highest number in high signal intensity. (c) 27 (41%) showed a mixed signal intensity. These 27 cases were the most numerous among the three grades of signal intensity. Of the 27, 7 in the group of 61-70 age range, 6 in the 51-60 age range, and 6 in the 71-80 age range were the highest number. 3. The varied signal intensities of 70 T1-weighted MR images of bone marrow in the mandibular molar regions : (a) 16 (23%) showed a low signal intensity. Of the 16, 8 in the 61-70 age group were the most numerous. (b) 23 (33%) showed a high signal intensity. Of the 23, 7 in the group of 61-70 age range and 6 in 41-50 age range were most numerous. (c) 31 (44%) showed a mixed signal intensity. These 31 cases were the most numerous among the three grades of signal intensity. Of these 31, 8 in the 71-80 age group, 7 in the 51-60 age group, and 7 in the 61-70 age group were the most numerous. 4. The varied signal intensities of 63 T1-weighted MR images of the bone marrow in the center region of the mandibular ramus : (a) 11 (17%) showed a low signal intensity. Of the 11, 4 in the 51-60 age group and 4 in 61-70 age group were most numerous. (b) 45 (70%) showed a high signal intensity. These 45 cases of high signal intensity were the most numerous among the three grades of signal intensity. Of these 45, 13 in the 61-70 age group were the most numerous. (c) 7 (11%) showed a mixed signal intensity. These 7 cases of a mixed signal intensity were fewest among the three grades of signal intensity. Mixed signal intensity was seen in all of the age groups except for those in the 11-20 and 31-40 age groups.
- 九州歯科学会の論文
- 1999-08-25