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Rationale and Objectives The aims of this study was to evaluate, using 3-T diffusion tensor imaging, changes of fractional anisotropy (FA) in the orbital and intracranial part of the optic nerve (ON), the optic chiasm, the lateral geniculate nucleus, and different parts of the optic radiation (OR) in patients with glaucoma compared to controls and to determine whether FA correlates with disease severity. Materials and Methods Twenty patients with glaucoma and 22 age-matched controls were examined using 3-T diffusion tensor imaging. Regions of interest were positioned on the FA maps, and mean values were calculated for each ON, optic chiasm, lateral geniculate nucleus, and OR. Results were compared to those from controls and correlated with ON atrophy and reduced spatial-temporal contrast sensitivity of the retina. Results Compared to controls, FA in patients with glaucoma was significantly lower in the intracranial part of the ON (0.48 ± 0.15 vs 0.66 ± 0.12, P P r > 0.81). Otherwise, there was no significant difference in FA between patients with glaucoma and controls measured in the orbital part of the ON, optic chiasm, and lateral geniculate nucleus. Conclusions Diffusion tensor imaging at 3 T allows robust FA measurements in the intracranial part of the ON and the OR. FA is significantly reduced in patients with glaucoma compared to controls, with a good correlation with established ophthalmologic examinations.

Rationale and Objectives The aim of this study was to compare tumor signal and contrast media uptake characteristics on contrast-enhanced T1-weighted sequences at 3 Tesla over 30 minutes after double-dose administration of different contrast agents in an animal model of brain glioma. Materials and Methods Nine rats underwent magnetic resonance imaging (MRI) after stereotactic F98 glioma cell implantation before and repetitively for 30 minutes after injection of gadobutrol, gadopentetate, and gadobenate, respectively. Signal-to-noise ratio (SNR) and tumor contrast-to-noise ratio (CNR) were evaluated and MRI-derived tumor volumes were compared to histology. Results Postcontrast tumor SNR and CNR peaked at 4 minutes after contrast application. While contrast-enhancement within the tumor was fading, tumor volume increased by continuous contrast-uptake of peripheral parts between 4 minutes (137 ± 29 mm3, 126 ± 16 mm3, 141 ± 24 mm3) and 20 minutes (182 ± 35 mm3, 164 ± 32 mm3, 191 ± 25 mm3), respectively. At 8 and 12 minutes, 84% and 91% of the tumor volume were definable, respectively. Conclusion Optimal correlation between MRI-derived tumor volume and histology is achieved by imaging up to 20 minutes after contrast application. At 4 minutes (this delay is mostly used in clinical routine), only 75% of the enhancing tumor volume is assessable. A delay of 8 minutes already reveals 84% of the tumor and seems to be a practical clinical compromise.

Rationale and Objectives The objective of this study was to determine how metabolite values (total N-acetyl aspartate [tNAA], glutamate plus glutamine [Glx], total choline [tCho], myoinositol [mI], and total creatine [tCr]) vary across brain regions in healthy subjects. This study was implemented to create an internal reference database for patients with psychiatric disorders and epilepsy. Materials and Methods Using the multivoxel technique with a voxelwise phantom calibration on a 3-T magnetic resonance imaging scanner, metabolite levels of 29 healthy controls (13 men, 16 women; average age, 29 years) were obtained from the hippocampi, basal ganglia, insula cortex, cingulum, and precuneus. Additionally, gray and white matter metabolite values were obtained from the frontal and parietal lobes. Results No significant effect of gender was noticed. The total magnitude of variation was greatest for Glx, followed by tNAA, mI, tCho, and tCr. Glx/tCr, Glx, and tCr were increased in gray matter, while tNAA/tCr, tCho/tCr, respectively tNAA and tCho, were elevated in white matter. These findings indicate (1) anterior-to-posterior increases of tNAA/tCr and Glx/tCr, respectively tNAA and Glx, along the midline in gray matter (cingulum); (2) increased tNAA/tCr, respectively tNAA, in white matter in the fiber tracts of the precentral region; (3) an accentuated anterior-to-posterior increase of tCr in the insula cortex; and (4) an anterior-to-posterior decrease of tCho/tCr and tCho in white matter. Conclusions There are significant metabolic differences within tissue types and within tissue types at different locations; therefore, the spectra and metabolite values presented should provide a useful internal reference for both clinical and research studies.

The aims of this study was to evaluate, using 3-T diffusion tensor imaging, changes of fractional anisotropy (FA) in the orbital and intracranial part of the optic nerve (ON), the optic chiasm, the lateral geniculate nucleus, and different parts of the optic radiation (OR) in patients with glaucoma compared to controls and to determine whether FA correlates with disease severity.Twenty patients with glaucoma and 22 age-matched controls were examined using 3-T diffusion tensor imaging. Regions of interest were positioned on the FA maps, and mean values were calculated for each ON, optic chiasm, lateral geniculate nucleus, and OR. Results were compared to those from controls and correlated with ON atrophy and reduced spatial-temporal contrast sensitivity of the retina.Compared to controls, FA in patients with glaucoma was significantly lower in the intracranial part of the ON (0.48 ± 0.15 vs 0.66 ± 0.12, P.05) and in the OR (0.40 ± 0.16 to 0.48 ± 0.17 vs 0.53 ± 0.20 to 0.64 ± 0.11, P.05). A high correlation between reduced FA in the intracranial ON and OR and ON atrophy and spatial-temporal contrast sensitivity of the retina was observed (r0.81). Otherwise, there was no significant difference in FA between patients with glaucoma and controls measured in the orbital part of the ON, optic chiasm, and lateral geniculate nucleus.Diffusion tensor imaging at 3 T allows robust FA measurements in the intracranial part of the ON and the OR. FA is significantly reduced in patients with glaucoma compared to controls, with a good correlation with established ophthalmologic examinations.

Rationale and Objectives Diffusion tensor imaging (DTI) can depict rarefaction of the optical fibres. Hence, we applied DTI to assess pathological changes of the optic radiation in glaucoma patients. Materials and Methods Fifty glaucoma patients and 50 healthy age-matched controls were examined by a 3T high-field magnetic resonance scanner. Fiber tracts were volume rendered using a semiquantitative approach to assess rarefaction and results were correlated with the extent of optic nerve atrophy and reduced spatial-temporal contrast sensitivity of the retina using established ophthalmological examinations. Results Twenty-two glaucoma patients (44%) showed significant rarefaction of the optic radiation: the volume was reduced to 67 ± 16% compared with controls. Hereby, the glaucomatous optic nerve atrophy stage correlated with the presence of DTI-derived rarefied optic radiation (Kendall tau-b 0.272, P = .016). Aside, cerebral microangiopathy affecting the optic radiation was significantly higher among glaucoma patients compared to controls (10 patients compared with 2 patients, P Conclusion In patients with glaucomatous optic nerve atrophy, there is anterograde and—most likely because of microangiopathic lesions within the optic radiation—retrograde transneuronal rarefaction of the optic radiation that can be assessed in vivo using DTI with good correlation to established ophthalmological examinations.

The aim of this study was to compare tumor signal and contrast media uptake characteristics on contrast-enhanced T1-weighted sequences at 3 Tesla over 30 minutes after double-dose administration of different contrast agents in an animal model of brain glioma.Nine rats underwent magnetic resonance imaging (MRI) after stereotactic F98 glioma cell implantation before and repetitively for 30 minutes after injection of gadobutrol, gadopentetate, and gadobenate, respectively. Signal-to-noise ratio (SNR) and tumor contrast-to-noise ratio (CNR) were evaluated and MRI-derived tumor volumes were compared to histology.Postcontrast tumor SNR and CNR peaked at 4 minutes after contrast application. While contrast-enhancement within the tumor was fading, tumor volume increased by continuous contrast-uptake of peripheral parts between 4 minutes (137 + or - 29 mm(3), 126 + or - 16 mm(3), 141 + or - 24 mm(3)) and 20 minutes (182 + or - 35 mm(3), 164 + or - 32 mm(3), 191 + or - 25 mm(3)), respectively. At 8 and 12 minutes, 84% and 91% of the tumor volume were definable, respectively.Optimal correlation between MRI-derived tumor volume and histology is achieved by imaging up to 20 minutes after contrast application. At 4 minutes (this delay is mostly used in clinical routine), only 75% of the enhancing tumor volume is assessable. A delay of 8 minutes already reveals 84% of the tumor and seems to be a practical clinical compromise.