Fig. 2

Visualization and measurement of the SPG. Axial (a) and sagittal (b) FIESTA MRI, axial (c) and sagittal (d) T2-weighted MRI depicting the sphenopalatine ganglion (SPG) (the red arrow is positioned in the center of the SPG, blue arrow is positioned at the pterygopalatine fossa [PPF]). The SPG has a crescent shape and intermediate signal intensity. The image surrounded by the orange rectangle is the ‘zoomed-in’ image. The light blue polygon depicts the border of the PPF. The oval red line is the border of the SPG. The dark blue line depicts the adjacent structure of PPF. FL cerebral frontal lobe, McS masticator space, MN maxillary nerve, MS maxillary sinus, MT middle nasal turbinate, NC nasal cavity, O orbit, PC palatine canal, PN palatine nerve, PPF pterygopalatine fossa, PP pterygoid process, SPB sphenoid bone, TL temporal lobe, VC vidian canal, VN vidian nerve