Delineation of optic radiation and stria of Gennari on high-resolution phase difference enhanced imaging.

RATIONALE AND OBJECTIVES: Phase difference enhanced (PADRE) imaging technique can selectively enhanced the phase difference between the target and surrounding tissue. Our purpose is to assess the delineations of the optic radiation and primary visual cortex (stria of Gennari) using PADRE. MATERIALS AND METHODS: The subjects were 6 healthy volunteers. Axial and coronal high-spatial resolution PADRE images were acquired covering the entire optic radiation using a 3T magnetic resonance system. Two radiologists evaluated the PADRE and susceptibility-weighted imaging (SWI)-like images for the delineation of four layers at the optic radiation (tapetum, internal sagittal stratum, external sagittal stratum, and adjacent white matter) on the basis of the anatomic appearances of the cadaveric specimens stained with Bodian's method and Kluver-Barrera method. The radiologists also assessed the delineations of the stria of Gennari on PADRE and SWI-like images. RESULTS: In all 6 healthy subjects, the PADRE images clearly identified the four layers at the optic radiation, as well as the stria of Gennari, which were difficult to appreciate in SWI-like images. The anatomic appearances of the optic radiation on PADRE images were more similar to those seen in the specimens stained with Kluver-Barrera method than with Bodian's method. CONCLUSION: The PADRE technique can delineate the four layers at the optic radiation and the stria of Gennari; the differences in myelin densities can also be enhanced. The PADRE technique may have the potential to reinforce the clinical utility of MRI in the diagnosis of diseases that affect the optic radiation and primary visual cortex.

A novel tract imaging technique of the brainstem using phase difference enhanced imaging: normal anatomy and initial experience in multiple system atrophy.

OBJECTIVES: To develop a new tract imaging technique for visualising small fibre tracts of the brainstem and for detecting the abnormalities in multiple system atrophy of the cerebellar type (MSA-C) using a phase difference enhanced (PADRE) imaging technique, in which the phase difference between the target and surrounding tissue is selectively enhanced. METHODS: Two neuroradiologists compared the high-spatial-resolution PADRE imaging, which was acquired from six healthy volunteers, three patients with MSA-C, and 7 patients with other types of neurodegenerative diseases involving the brainstem or cerebellum. RESULTS: Various fine fibre tracts in the brainstem, the superior and inferior cerebellar peduncles, medial lemniscus, spinothalamic tract, medial longitudinal fasciculus, central tegmental tract, corticospinal tract and transverse pontine fibres, were identified on PADRE imaging. PADRE imaging from MSA-C demonstrated the disappearance of transverse pontine fibres and significant atrophy of the inferior cerebellar peduncles, while the superior cerebellar peduncles were intact. PADRE imaging also demonstrated that the transverse pontine fibres and inferior cerebellar peduncle were not involved in the other neurodegenerative diseases. CONCLUSION: PADRE imaging can offer a new form of tract imaging of the brainstem and may have the potential to reinforce the clinical utility of MRI in differentiating MSA from other conditions.

Superficial siderosis associated with a chronic subdural hematoma: T2-weighted MR imaging at 3T.

RATIONALE AND OBJECTIVES: The purposes of this study were to assess the association between superficial siderosis (SS) and subdural hematoma (SDH) and to evaluate the magnetic resonance imaging (MR) characteristics of SS in patients with the presence or histories of SDH compared to those with histories of aneurysmal subarachnoid hemorrhage (SAH). MATERIALS AND METHODS: A radiology database for a 4-year period contained data on patients with diagnoses of SDH. From these patients, 47 patients were further selected who underwent brain MR examinations using a 3-T MR system (the SDH group). Using T2-weighted images, two neuroradiologists evaluated the presence or absence and the characteristics of SS findings by comparing the patients with histories of aneurysmal subarachnoid hemorrhage (the SAH group; n = 36). The SS findings were classified into three types: apical (SS at the top of the surface of the gyrus of the cerebral hemisphere), gyral (SS surrounding the gyrus), and mixed. RESULTS: SS findings were seen in 13 patients (27.7%) in the SDH group (SS-SDH) and 13 patients (36.1%) in the SAH group (SS-SAH); all 13 cases of SS-SDH were the apical type, whereas the 13 cases of SS-SAH were either the gyral (n = 9 [69.2%]) or mixed (n = 4 [30.8%]) type. SS-SDH was seen only in the cerebral hemisphere ipsilateral to the side of the SDH (12 of 13 [92.3%]). All 13 cases of SS-SDH were accompanied by thinning of gray-matter intensity in the cerebral cortex, which was more frequently seen than in SS-SAH (P < .01). CONCLUSION: SDH occasionally causes the SS-like MR findings, and the pathogenesis of SS-SDH may be also different from that of SS-SAH.