Phenylketonuria: A Scoring System for Brain Magnetic Resonance Imaging.

Objective: The purpose of our study was to devise a new brain Magnetic Resonance Imaging (MRI) scoring system based on the Loes and modified Loes scores in phenylketonuria (PKU) patients.

Materials and methods: The brain MRI scans of patients with late diagnosed PKU were evalu- ated retrospectively. Patients' age at diagnosis, age at which diet started, age at MRI, and, blood phenylalanine (Phe) levels at the time point closest to the MRI were recorded.

Results: Eleven patients aged from 3 to 28 years were included in the study. The median MRI involvement score was 17 (interquartile range = 3). The most involved white matter areas were the parietooccipital areas. There was a significant (P = .046) correlation between the blood Phe level at the timepoint closest to the imaging and the MRI involvement score.

Conclusion: Our study provides insights into the MRI findings and scoring system in PKU patients. We have developed a scoring system based on the widely used Loes and modified Loes scoring systems that can be implemented in clinical practice. Also, our study contributes to the long-forgotten and largely abandoned area-imaging findings in late diagnosed and untreated PKU patients and set the stage for the future research in this field.