PMC5386153_01
Magnetic resonance imaging (MRI) showed no distinct abnormalities on a T1-weighted image (A), but showed an irregular image with a mix of low and high signals at L5 vertebra or lower on a T2-weighted image (B).
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F1
Magnetic resonance imaging (MRI) showed no distinct abnormalities on a T1-weighted image, but showed an irregular image with a mix of low and high signals at L5 vertebra or lower on a T2-weighted image (Fig. 1A, B).
Plain computed tomography (CT) at L5/S1 level (A) and reconstructive CT images at the L5-S2 level (B) showed an ossified lesion within the dura mater.
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F2
Plain and reconstructive computed tomography (CT) images showed an ossified lesion within the dura mater at the L5-S2 levels (Fig. 2A, B).
A bone chip 4.5 x 0.5 x 0.5 cm in size was found in a bundled state of the nerves of the cauda equina, which was removed en bloc.
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F3
When the nerves of the cauda equina were individually separated with care, a bone chip 4.5 x 0.5 x 0.5 cm in size was found in its center, which was removed en bloc (Fig. 3).
Histological observation of the harvested bone chips showed a normal osseous structure.
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F4
Histological observation of the harvested bone chips showed a normal osseous structure (Fig. 4). 
Computed tomography reconstruction images obtained 2 years after surgery showed no ossified lesions.
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F5
CT reconstruction images obtained 2 years after surgery showed no ossified lesions (Fig. 5).