For the purpose of investigating a difference in muscle fiber composition and bone marrow between the affected and unaffected sides, the relaxation times of Magnetic Resonance Imaging (MRI) were measured in lower thigh muscles of hemiplegic stroke patients. Results obtained were as follows: 1) Of soleus muscle, both TI and T2 values were larger in the affected side than in the unaffected side, which implies that the fast twitch fiber may be contained more in the muscle of the affected side than

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... in the unaf fected side. 2) No significant difference in T1 and T2 values of anterior tibial muscle was observed between the sides, which suggests that relatively active muscle fiber may be decreased in the muscles of both sides. 3) Of upper part of the bone marrow, both T1 and T2 values were larger in the unaffected side compared with the affected side. This suggests that fat bone marrow may be contained more in the affected side than in the unaffected side.