Magnetom 1.5 tesla

All images were obtained with a MAGNETOM 1.5-tesla (Avanto) or 3-tesla (Trio) MR imaging unit (Siemens Healthcare, Erlangen, Germany). The imaging conditions of each device, including TR, TE FOV, and matrix, were almost the same. These MRIs were used for measurement in this study, and axial slice level was photographed consecutively with an MRI reference line consisting of the orbitomeatal line that runs through the external canthus and the center of the external auditory meatus with a slice thickness of 4 -5 mm. The wound, area of the skin and occipital muscle of the affected side was determined using the digital imaging and communications in medicine (DICOM) viewer. Region of interests (ROIs) were designed around the skin and occipital muscles bilaterally and calculated with DICOM viewer software EV Insite® (version. 3.1.1.196; PSP corporation). The ROIs were designed as the area at the level of the occipital condyles in MRI T2-WI axial images, limited anteriorly by an imaging line connecting the central points of both mastoid tips (Fig. 3). Each area was measured three times by two independent raters (T.O. and T.G.) and the mean was adopted. The atrophic ratio of the wound ((contralateral areaipsilateral area)/(contralateral area) × 100 (%)) was calculated for 1, 2, and > 3 years after surgery and compared between methods.