54 Chapter 3 Histograms, boxplots, and the Shapiro-Wilk test were used to confirm that cerebral blood flow was approximately normally distributed. Linear mixed models were used to compare the mean cerebral blood flow in the frontal lobe in trigonocephaly patients versus control subjects. We did not include age or sex in this model due to our limited sample size. A chi-square test was performed to assess the effect of sex on the frontal lobe perfusion. To confirm the validity of our data, we normalized cerebral blood flow data of the frontal lobe by occipital lobe data using the ratio of frontal lobe to occipital lobe. We compared this frontal lobe to occipital lobe ratio between patients and control subjects by using a t test. In addition, we assessed the ratio of the spatial coefficient of variation — a measure of global spatial signal distribution — between the frontal lobe and occipital lobe, comparing the ratios between patients and control subjects using a t test. A significance level of 0.05 was considered for all tests. As a supplement, descriptive data on cerebral blood flow of the other brain regions were set out as mean, standard deviation, standard error, and lower and upper confidence interval. RESULTS Patient Characteristics Thirty-six unoperated patients with trigonocephaly with a median age of 0.50 years (interquartile range, 0.30) and 16 control subjects with a median age of 0.83 years (interquartile range, 0.56) were included in this study, as presented in Table 1. During follow-up after the magnetic resonance imaging scans, 18 patients underwent a frontosupraorbital remodeling at a median age of 0.82 years (interquartile range, 0.08). All patients were initially considered for surgical intervention. Eighteen patients were operated on to correct the contour of the forehead, and the remaining patients were not operated on after joint decision making with their parents (n = 18). The follow up median age of the operated trigonocephaly group was 1.63 years (interquartile range, 1.16); the follow-up median age of the trigonocephaly group not operated on was 1.71 years (interquartile range, 0.41). Table 1. Patient Characteristics. Trigonocephaly Controls n MRI 36 16 f : m 11:25 10:06 median age (IQR) 0.5(0.3) 0.83(0.56) n Frontosupraorbital remodellation 18 f : m 07:11 median age (IQR) 0.82(0.08) Follow-up operated trigonocephaly patients median age (IQR) 1.63(1.16) non-operated trigonocephaly patients median age (IQR) 1.71(0.41)
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