Brain diffusion MRI with multiplexed sensitivity encoding for reduced distortion in a pediatric patient population.

BACKGROUND: Diffusion-weighted imaging (DWI) is a valuable tool for routine imaging of the pediatric brain. However, the commonly used single-shot (ss) echo-planar imaging (EPI) DWI sequence is prone to geometric distortions and T2*-blurring. This study aimed to investigate in a pediatric population the benefits of using multiplexed sensitivity-encoding (MUSE) without and with reversed polarity gradients (RPG) instead. METHODS: This retrospective study compared image quality, geometric distortions, and diffusion values between three different approaches for DWI (ssEPI, MUSE, and RPG-MUSE) in 14 patients (median age = 4 (0.6-15) years, 11 males). Distortion levels were quantified and compared in two brain regions, i.e., the brain stem and the temporal lobes, using the Dice Coefficient and the Hausdorff Distance, with T2-weighted images as reference. Expected geometrical distortion was further evaluated by comparing the effective echo spacing between the DWI sequences. Apparent diffusion coefficient (ADC) values were determined in the genu of the corpus callosum and the optic nerves. Two raters graded overall image quality and image distortions on a Likert scale. RESULTS: Distortion levels assessed with Dice coefficient and Hausdorff distance were significantly lower for MUSE (p < 0.05) and RPG-MUSE (p < 0.01) compared to ssEPI. No significant difference in ADC values was observed between methods. The RPG-MUSE method was graded by one rater as significantly higher in overall image quality than ssEPI (p < 0.05) and by both raters as significantly lower in levels of image distortions than both MUSE (p < 0.05) and ssEPI (p < 0.05). These results were in agreement with the reduced effective echo spacing was that was attained with MUSE and RPG-MUSE. CONCLUSION: For imaging of the pediatric brain, MUSE and even more so RPG-MUSE offers both improved geometric fidelity and image quality compared to ssEPI.

Novel imaging findings in pyruvate dehydrogenase complex (PDHc) deficiency-Results from a nationwide population-based study.

The vast clinical and radiological spectrum of pyruvate dehydrogenase complex (PDHc) deficiency continues to pose challenges both in diagnostics and disease monitoring. Prompt diagnosis is important to enable early initiation of ketogenic diet. The patients were recruited from an ongoing population-based study in Sweden. All patients with a genetically confirmed diagnosis who had been investigated with an MRI of the brain were included. Repeated investigations were assessed to study the evolution of the MRI changes. Sixty-two MRI investigations had been performed in 34 patients (23 females). The genetic cause was mutations in PDHA1 in 29, PDHX and DLAT in 2 each, and PDHB in 1. The lesions were prenatal developmental in 16, prenatal clastic in 18, and postnatal clastic in 15 individuals. Leigh-like lesions with predominant involvement of globus pallidus were present in 12, while leukoencephalopathy was present in 6 and stroke-like lesions in 3 individuals. A combination of prenatal developmental and clastic lesions was present in 15 individuals. In addition, one male with PDHA1 also had postnatal clastic lesions. The most common lesions found in our study were agenesis or hypoplasia of corpus callosum, ventriculomegaly, or Leigh-like lesions. Furthermore, we describe a broad spectrum of other MRI changes that include leukoencephalopathy and stroke-like lesions. We argue that a novel important clue, suggesting the possibility of PDHc deficiency on MRI scans, is the simultaneous presence of multiple lesions on MRI that have occurred during different phases of brain development.

UBE2A deficiency syndrome: a report of two unrelated cases with large Xq24 deletions encompassing UBE2A gene.

Intragenic mutations of the UBE2A gene, as well as larger deletions of Xq24 encompassing UBE2A have in recent years been associated with a syndromic form of X-linked intellectual disability called UBE2A deficiency syndrome or X-linked intellectual disability type Nascimento (OMIM#300860). Common clinical features in these patients include moderate to severe intellectual disability (ID), heart defects, dysmorphic features such as high forehead, synophrys, prominent supraorbital ridges, almond-shaped and deep-set eyes, wide mouth, myxedematous appearance, hirsutism, onychodystrophy, and genital anomalies. This study investigates clinical and molecular data of two unrelated, affected males with chromosome Xq24 deletions encompassing UBE2A. Both have been followed from birth until two years of age. A review of the previously published patients with deletions encompassing UBE2A is provided. Besides the common features, the two boys show anomalies not previously described, such as retinal coloboma, esophageal atresia with esophageal fistula, long fingers, camptodactyly, clinodactyly, and long broad toes. Analyses of the phenotype-genotype correlations suggest considerable prevalence of heart defects in the group of patients with larger deletions of Xq24 in comparison to the patients having intragenic UBE2A mutations. However, further studies are needed in order to establish statistically reliable phenotype-genotype correlations of this syndrome.

A retrospective analysis of the clinical impact of 939 chest radiographs using the medical records.

Objective. Between one-third and half of all radiology examinations worldwide are probably chest studies. The aim of the current study was to retrospectively evaluate the clinical influence of chest radiography. Methods. In a tertiary referral hospital, 939 consecutive daytime chest radiography examinations were evaluated. The outcome was classified as normal, incidental, or pathologic. The referring physician's reaction to radiologic outcome was classified as highly expected, moderately expected, or unexpected. The influence on the patients' treatment was divided into four groups from major to no influence. Results. In all, 71.6% of the studies had a highly expected outcome. Moderately expected or unexpected outcomes were noted in 36.6% of 500 pathologic examinations. Unexpected outcome was noted in 11.6% of all studies. The radiologic outcome influenced treatment in 65.4% of patients where pathology was demonstrated. Patients with normal or incidental findings had treatment influenced in 1/3 of the cases. Unexpected findings influenced treatment more than moderately expected findings. When radiological findings were highly expected, treatment was influenced in less than half of the cases. Surprisingly few chest radiology examinations were commented upon in the medical records.