Functional Magnetic Resonance Imaging (fMRI) studies are derived from a time series of Echo-Planar images (EPIs). Compared to conventional Magnetic Resonance Images (MRIs), EPIs are of relatively poor quality for discerning anatomic features and are often registered with corresponding MRIs to map brain activity to neuroanatomy. In this paper we demonstrate the utility of a technique to register an EPI-MRI pair by minimizing the discrepancy between its joint intensity probability mass function (PMF) and a previously learned one for a properly registered EPI-MRI pair, using the Kullback-Leibler Distance (KLD). In probing experiments Joint Entropy (JE) and Mutual Information showed significant bias relative to KLD along the axial direction and JE along a rotation axis. A comparison of searches using random starting poses showed KLD to have lower final pose errors than JE. Results of variation on parameters of the KLD based EPI-MRI registration technique are also presented.

Current clinical practice in the premature infant with posthaemorrhagic ventricular dilatation (PHVD) includes drainage of cerebrospinal fluid (CSF). This case study used advanced volumetric three dimensional magnetic resonance imaging to document the impact of CSF removal on the volume of regional brain tissues in a premature infant with PHVD. The removal of a large volume of CSF was associated with an identical reduction in CSF volume, but more dramatically with a significant increase in the regional volumes of cortical grey matter and myelinated white matter. The alterations in cerebral cortical grey matter and myelinated white matter volumes may provide insight into the established association of PHVD with deficits in cognitive and motor functions.

BACKGROUND: One of the diagnostic imaging hallmarks of MS is the uptake of IV administered contrast material in new lesions in the brain, signaling blood-brain barrier breakdown and active inflammation. Many clinical drug trials are designed based on the assumption that lesion enhancement on MRI remains visible on average for 1 month. For practical reasons, few serial MRI studies of patients with MS have been performed at intervals shorter than 4 weeks. METHODS: The authors performed a year-long longitudinal study in 26 patients with relapsing-remitting MS (RRMS), which comprised an initial phase of MRI follow-up at weekly intervals for 8 weeks, followed by imaging every other week for another 16 weeks, and monthly thereafter. They present a quantitative analysis (using a supervised interactive thresholding procedure) of new enhancing lesions appearing during the first 6 weeks in this cohort and evaluated from the time of first detection until enhancement was no longer seen. RESULTS: The average duration of Gd-DTPA enhancement in individual new lesions was 3.07 weeks (median, 2 weeks). Significant correlations were demonstrated between the duration of contrast enhancement or initial growth rates and lesion volumes. Different lesions in the same patient appeared to develop largely independent of each other and demonstrated a large range in the duration of enhancement during the acute phase of their evolution. CONCLUSIONS: The average duration of blood-brain barrier impairment in RRMS is shorter than earlier estimates. Early lesion growth parameters may predict final lesion size. Within-patient heterogeneity of lesion evolution suggests that individual lesions develop independently.

OBJECTIVE: Smaller temporal lobe cortical gray matter volumes, including the left superior temporal gyrus, have been reported in magnetic resonance imaging (MRI) studies of patients with chronic schizophrenia and, more recently, in patients with first-episode schizophrenia. However, it remains unknown whether there are progressive decreases in temporal lobe cortical gray matter volumes in patients with first-episode schizophrenia and whether similarly progressive volume decreases are present in patients with affective psychosis. METHOD: High-spatial-resolution MRI scans at initial hospitalization and 1.5 years later were obtained from 13 patients with first-episode schizophrenia, 15 patients with first-episode affective psychosis (mainly manic), and 14 healthy comparison subjects. MRI volumes were calculated for gray matter of superior temporal gyrus and for the amygdala-hippocampal complex.