Kono Kinuko, Okano Yoshiyuki, Nakayama Keiko, Hase Yutaka, Minamikawa Sosuke, Ozawa Nozomi, Yokote Hiroyuki, Inoue Yuichi
Department of Radiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, abeno-ku, Osaka 545-8585, Japan.
Radiology. 2005 Aug;236(2):630-6. doi: 10.1148/radiol.2362040611.
To prospectively determine the relationship between serum phenylalanine levels and apparent diffusion coefficient (ADC) values in the cerebral white matter of patients with phenylketonuria (PKU).
Institutional review board approval was obtained, and participants provided informed consent. Magnetic resonance (MR) imaging, which included T1- and T2-weighted, fluid-attenuated inversion-recovery (FLAIR), and diffusion-weighted examinations, was performed in 21 patients with PKU (nine male and 12 female patients; age range, 3-44 years; mean age, 19.4 years). ADC values in deep cerebral white matter were calculated for each patient. Serum phenylalanine levels were obtained in all patients within 12 days after MR imaging. Serum phenylalanine levels were measured in 16 patients 1 year before MR imaging. ADC values in cerebral white matter and serum phenylalanine levels were compared. A total of 21 control subjects (12 male and nine female patients; age range, 3-33 years; mean age, 20.6 years) underwent MR imaging. ADC values in cerebral white matter were compared with serum phenylalanine levels by using the Pearson correlation.
Abnormal high signal intensity in white matter on T2-weighted and FLAIR MR images was noted in patients with PKU who had serum phenylalanine levels of more than 8.5 mg/dL (514.2 micromol/L). Diffusion in posterior deep cerebral white matter tended to be restricted in patients when increased serum phenylalanine levels were measured after MR imaging (r = -0.62). There was a correlation between ADC values in posterior cerebral white matter and serum phenylalanine levels measured 1 year before MR imaging (r = -0.77). ADCs of control subjects were significantly higher than ADCs of patients with PKU (P < .005).
Posterior deep white matter in patients with PKU and a serum phenylalanine level of more than 8.5 mg/dL showed high signal intensity in white matter on T2-weighted and FLAIR MR images and revealed decreased ADC. We suggest that to avoid brain-restricted diffusion due to hyperphenylalanemia, patients with PKU should maintain serum phenylalanine levels of less than 8.5 mg/dL (514.2 micromol/L).
前瞻性地确定苯丙酮尿症（PKU）患者血清苯丙氨酸水平与脑白质表观扩散系数（ADC）值之间的关系。
获得机构审查委员会批准，参与者提供知情同意书。对21例PKU患者（9例男性和12例女性患者；年龄范围3 - 44岁；平均年龄19.4岁）进行了磁共振（MR）成像，包括T1加权、T2加权、液体衰减反转恢复（FLAIR）和扩散加权检查。计算每位患者大脑深部白质的ADC值。在MR成像后12天内获取所有患者的血清苯丙氨酸水平。在16例患者中测量了MR成像前1年的血清苯丙氨酸水平。比较脑白质ADC值与血清苯丙氨酸水平。共有21名对照受试者（12例男性和9例女性患者；年龄范围3 - 33岁；平均年龄20.6岁）接受了MR成像。采用Pearson相关性分析比较脑白质ADC值与血清苯丙氨酸水平。
血清苯丙氨酸水平超过8.5 mg/dL（514.2 μmol/L）的PKU患者在T2加权和FLAIR MR图像上白质出现异常高信号强度。在MR成像后测量到血清苯丙氨酸水平升高时，患者大脑后部深部白质的扩散趋于受限（r = -0.62）。大脑后部白质ADC值与MR成像前1年测量的血清苯丙氨酸水平之间存在相关性（r = -0.77）。对照受试者的ADC值显著高于PKU患者（P <.005）。
血清苯丙氨酸水平超过8.5 mg/dL的PKU患者大脑后部深部白质在T2加权和FLAIR MR图像上白质显示高信号强度且ADC降低。我们建议，为避免高苯丙氨酸血症导致脑扩散受限，PKU患者应将血清苯丙氨酸水平维持在低于8.5 mg/dL（514.2 μmol/L）。
