Longitudinal quantitative analysis of the tuber-to-brain proportion in patients with tuberous sclerosis.

OBJECT: In patients with tuberous sclerosis complex (TSC), the tuber-to-brain proportion (TBP) is a marker of seizure severity and cognitive function. However, few studies have quantified the TBP. Furthermore, authors of these studies have measured the TBP at only a single time point, despite the fact that tuber cells were found to express proliferation markers, suggesting that they may be dynamic lesions. Authors of the present study used a semi-automated tuber segmentation program to determine whether the TBP changes over time. METHODS: Axial FLAIR MR images were retrospectively identified for patients with TSC who had undergone imaging at the authors' institution between February 1998 and June 2009. Using FireVoxel software, the TBP was measured for each patient at a minimum interval of 2 years. RESULTS: Twelve patients meeting the study inclusion criteria were identified. The mean TBP was 1.88% (range 0.38%-3.70%). Eight patients demonstrated minimal changes and 3 patients demonstrated small increases in TBP. The remaining patient exhibited a decrease of 1.00%, which correlated with a visible decrease in the size of 2 cerebellar lesions. CONCLUSIONS: Semi-automated brain segmentation is a valuable tool in the longitudinal study of tubers. A subset of patients with TSC, particularly those with cerebellar lesions, may exhibit changes in the TBP over time.

Prenatal MR findings of the middle interhemispheric variant of holoprosencephaly.

We report a case of the middle interhemispheric variant of holoprosencephaly (MIH) with noncleavage of the posterior portion of the frontal lobes and the parietal regions in a fetus at 22 weeks' gestation. To our knowledge, this is the first case of the rare MIH variant to be diagnosed in utero by use of ultrafast MR imaging and one of the few such reports to document gross and microscopic pathologic findings. Neuroimaging results correlated with those of gross and microscopic pathologic specimens obtained from the stillborn child. We conclude that ultrafast MR imaging can accurately distinguish holoprosencephaly subtypes in utero, which may affect counseling of parents.

In vivo pyruvate detected by MR spectroscopy in neonatal pyruvate dehydrogenase deficiency.

We present a unique finding of an elevated level of pyruvate at 2.37 ppm revealed by in vivo MR spectroscopy of a female neonate. Low fibroblast pyruvate dehydrogenase (PDH) complex activity subsequently confirmed a diagnosis of PDH deficiency. Abnormalities of brain development consistent with PDH deficiency were also evident on fetal and postnatal MR images. To our knowledge, this is the first report of pyruvate being shown in vivo in a child and the first report of MR spectroscopy aiding in the diagnosis of inborn error in pyruvate metabolism before confirmation by conventional enzymatic testing. This finding has potential implications for earlier diagnosis in patients with defects in mitochondrial metabolism.