Intervention
VFSS was performed using an X-ray flat-panel detector system (FPD, Zexira®, Toshiba, Tokyo, Japan). Swallowing images were digitally recorded at a rate of 30 frames/s from a lateral viewing plane. The VFSS protocol consisted of (1) 3-ml thin liquid (barium sulfate solution or iohexol) provided with a spoon, (2) 5-ml yogurt mixed with each contrast agent provided with a spoon, (3) 5-ml banana mixed with each contrast agent provided with a spoon, and (4) 10-ml thin liquid (barium sulfate solution or iohexol) provided with a cup. Each of the consistencies was given twice to the participants, and the two contrast agents were given alternately for each time (a total of 8 boluses; 4 boluses mixed with barium sulfate and 4 boluses mixed with iohexol) (Fig. VFSS findings were categorized according to the penetration–aspiration scale (PAS)