PMC

Obscured bone marrow edema-like signal on postcontrast STIR images. Precontrast STIR images of four different patients (A to D) with bone marrow edema-like signal at the Lisfranc joint (left) show signal suppression on postcontrast STIR images (right). A 1.5-T MRI of an 84-year-old male patient shows bone marrow edema-like signal at the base of the second metatarsal bone on precontrast STIR (left, white arrow). The signal intensity of bone marrow edema-like signal is reduced even below the adjacent normal appearing bone on the corresponding postcontrast STIR image (right, white arrow). B 1.5-T MRI of a 94-year-old male patient with bone marrow edema-like signal on both sides of the Lisfranc joint of the first ray (left, white arrow) on precontrast STIR with complete suppression of the signal on postcontrast STIR (right). C 3-T MRI of a 69-year-old female patient shows bone marrow edema-like signal with cystic changes at the Lisfranc joint of the second ray on precontrast STIR (left, white arrow) with nearly complete signal suppression on postcontrast STIR (right). Note the persisting high signal of the cystic changes on the postcontrast STIR image (white arrow). D 1.5-T MRI of a 37-year-old female patient with bone marrow edema-like signal at the base of the second metatarsal bone on precontrast STIR (left, white arrow) with complete signal suppression on the postcontrast STIR image (right)

Scanning electron micrographs of (a) MIP-coated stir bar with the magnifications of 200x; (b) MIP-coated stir bar with the magnifications of 5000x; (c) NIP-coated stir bar with the magnifications of 200x; (d) NIP-coated stir bar with the magnifications of 5000x.

Typical microstructures of friction stir processed material: (a) base metal, (b) boundary of base metal and stir zone on advancing side, (c) stir zone, (d) boundary of base metal and stir zone on retreating side [].

Different types of progression at 1 year in single muscles (baseline on the left‐hand side and follow‐up on the right of each panel). (A) Patient 41: worsening on T1w sequences with persistence of STIR hyperintensity in vastus lateralis (arrow) and medialis (asterisk); in the same patient, the STIR+ sartorius (arrowhead) becomes atrophic and STIR‐ at follow‐up; (B) Patient 35: a new hyperintense lesion in STIR sequences accompanied by volume loss is evident in the tibialis anterior (arrowhead); (C) Patient 65: normalization of STIR signal without apparent changes on T1w images in the semitendinosus (arrow); (D) Patient 63: right soleus (asterisk, STIR+ at baseline), left soleus (triangle), and right gastrocnemius medialis (arrowhead, STIR+ at follow‐up scan) becoming almost completely replaced by fat tissue after 1 year; appearance of a new STIR+ muscle (gastrocnemius lateralis, arrow) with normal signal in T1w sequences. STIR, short‐tau inversion recovery.