We hypothesized that individual differences in intelligence (Spearman's g) are supported by multiple brain regions, and in particular that fluid ( gF) and crystallized ( gC) components of intelligence are related to brain function and structure with a distinct profile of association across brain regions. In 225 healthy young adults scanned with structural and functional magnetic resonance imaging sequences, regions of interest (ROIs) were defined on the basis of a correlation between g and either brain structure or brain function. In these ROIs, gC was more strongly related to structure (cortical thickness) than function, whereas gF was more strongly related to function (blood oxygenation level-dependent signal during reasoning) than structure. We further validated this finding by generating a neurometric prediction model of intelligence quotient (IQ) that explained 50% of variance in IQ in an independent sample. The data compel a nuanced view of the neurobiology of intelligence, providing the most persuasive evidence to date for theories emphasizing multiple distributed brain regions differing in function.

This study demonstrates that 3D 7T MRI can definitively visualize anatomical alterations occurring in the SN of PD subjects. Further pathological studies are required to elucidate the nature of these anatomical alterations.

Recent MRI studies have demonstrated that the relative orientation of white matter fibers to the B0 field significantly affects R2∗ measurement. In this work, the origin of this effect was investigated by measuring R2 and R2∗ in multiple orientations and fitting the results to magnetic susceptibility-based models and magic angle-based models. To further explore the source of magnetic susceptibility effect, the contribution of tissue iron to the orientation dependent R2∗ contrast was investigated. Additionally, the effects of temperature on R2∗ and orientation dependent R2∗ contrasts were studied to understand the differences reported between a fixed specimen at room temperature and in vivo at body temperature. The results suggest that the B0 dependent R2∗ variation is better explained by the magnetic susceptibility-based model with susceptibility anisotropy. However, extracting tissue iron did not reduce the orientation dependent R2∗ contrast, suggesting iron is not the origin of the contrast. This leaves susceptibility effects from myelin as the most probable origin of the contrast. Temperature showed large contribution on both R2∗ and orientation dependent R2∗ contrasts, explaining a portion of the contrast difference between the in-vivo and in-vitro conditions.

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13121038/-/DC1.

No abstract

Background and Purpose-We sought to examine the feasibility of observing the lenticulostriate arteries (LSAs) noninvasively by ultrahigh-field MRI with 7.0T. Methods-We used 3-dimensional time-of-flight MR angiography with a radiofrequency coil optimized for 7.0T MRI. We examined the LSAs of 6 healthy subjects and compared 7.0T MR angiography images with 1.5T ones to examine the potentials of ultrahigh-field MRI for angiography. Results-The results show clear details of LSAs and their distribution in the normal healthy subjects with large variations in the shapes, the number of branches and the sites of origin. We also observed substantial differences between the left and right sides within each subject. Although we studied only 6 subjects, we found no age-or gender-related differences in the LSAs. Conclusions-The visualization of microvasculature of the brain, such as LSAs, using 7.0T MR angiography, is possible in in vivo human studies noninvasively. We, therefore, believe that it could play a major role in the study of small vascular abnormalities, such as the early stages of cerebral strokes. (Stroke. 2008;39:1604-1606.)

Abstract-Hypertension, a major risk factor for stroke, is associated with altered arterial anatomy and function; however, the limited resolution of current imaging techniques has restricted the in vivo study of microvascular changes in the brain. In this report, we quantitatively examined the lenticulostriate arteries in hypertensive patients using ultrahigh-field 7T MRI. We compared the number of stems and branches, curvature, and tortuosity of the lenticulostriate arteries by 3D time-of-flight magnetic resonance angiography among 20 hypertensive patients (mean age: 46.6Ϯ9.1 years) and 20 age-matched healthy subjects (mean age: 47.7Ϯ8.1 years). The average numbers of stems and branches in hypertensive patients were significantly less than those of healthy subjects (PϽ0.002). However, this difference was abolished in older volunteers (Ͼ45 years old), whereas the difference between young hypertensive patients (Յ45 years old) and age-matched healthy controls was augmented by 55% for stems and 91% for branches (Pϭ0.001). In comparison, there were no differences in the average curvature and tortuosity of the lenticulostriate arteries and no significant difference when corrected for smoking (Pϭ0.064). In conclusion, our results showed that there was a substantial difference in the lenticulostriate arteries of hypertensive patients compared with healthy individuals when observed in vivo by ultrahighresolution 7T magnetic resonance angiography, and the difference was considerable in young subjects. Key Words: microvessels Ⅲ hypertension Ⅲ magnetic resonance angiography Ⅲ 7T MRI Ⅲ lenticulostriate arteries H ypertension is considered to be one of the most important risk factors for strokes, heart attacks, heart failure, and arterial aneurysms. Hypertension can promote and/or be induced by changes in the small arterial and arteriolar architecture via vascular hypertrophy, endothelial dysregulation, and atherosclerosis. 1 These structural changes disturb the microcirculation, resulting in high vascular resistance and reduced blood flow through the microvessels. 2 Given the relatively high blood flow through the anterior cerebral artery and middle cerebral artery, hypertensive patients have a particularly high incidence of stroke. 3,4 Their perforators, the lenticulostriate arteries (LSAs), play a major role, because lacunar infarcts account for Ͼ20% of all strokes, and 35% to 44% of intracerebral hemorrhages involve the basal ganglia. This is because the blood supplied to these territories comes from end arteries that have little or no collateral circulation. 4,5 Moreover, hypertension is associated with Ͼ70% of all intracerebral hemorrhages and lacunar infarcts, 6,7 as well as white matter changes and silent strokes. Thus, imaging of the LSAs in vivo could offer important insight for understanding the mechanisms of microvascular diseases associated with hypertension.Although current neuroimaging techniques, including magnetic resonance angiography (MRA), computed tomographic angiography, and digital subtraction angiograp...

This study demonstrates that noninvasive magnetic resonance angiography using 7 T magnetic resonance imaging can visualise abnormalities in the cerebral microvasculature of stroke patients, and that the number of lenticulostriate arteries supplying the region of the basal ganglia is less in these patients compared with age-matched controls.