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Figure 1 . (A) Images of a transverse slice through the human head at 7 Tesla, obtained with magnetization preparation to encode B
1 magnitude as [cos( τγ B
1
)] “Turboflash” (center-out k -space sampling,
TR/TE = 4.2 ms/2.5 ms, slice thickness = 5 mm, flip angle = 10º at slice center, matrix size = 128 x 64).
The different images correspond to different τ going from 0 to 2 ms in 0.1-ms steps (left to right). The starting image on the right corresponds to τ of 0, 0.7, and 1.4 ms for the first, second, and third rows, respectively, as shown in the figure. B
1 magnitude was kept constant. (B) The signal (magnitude) oscillation frequency plotted for two regions of interest in the middle and periphery of the brain. Oscillation frequency is equal to γ B
1
, indicating that B with permission from [15].
1 is substantially higher in the center of the brain. Reprined
Figure 2 . (A) SNR gains at 7 Tesla relative to 4 Tesla for 4-port driven TEM volume coil. The SNR gains are given as a ratio of 7 T SNR vs 4 T SNR as numbers in red at one central and four peripheral locations. Reprinted with permission from [15]. (B) SNR ratio of periphery vs. the center of the brain at 7 T with a four-port driven TEM volume coil (same data as in A). (C) SNR ratio of periphery vs. the center of the brain at 7 Tesla with an 8-element array coil. Reprinted with permission from [21].

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Figure 3 . SNR at 7 Tesla of a TEM volume coil (4-port driven) vs. two different coil arrays.
Images are scaled so that gray scale corresponds to SNR.
Figure 4 . Early human head and body images at 4 Tesla. Reprinted with permission from
[198].

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Figure 5 . Receive and transmit patterns generated with an array coil either as the sum of magnitudes (SOM) or a magnitude of complex sum (MOS) to emulate a single-channel
“volume coil” mode: (A) Sum of the eight individual B
1 receive magnitude maps. (B) B receive magnitude map calculated from complex summation in order to simulate a single-
1 channel “volume coil” mode. (C) Ratio of magnitude of the complex sum over the sum of the 8 magnitude receive B
1 fields, showing the loss of receive B
1 field in the periphery when merging complex data from multiple coil elements. Color scales are independently adjusted, in arbitrary units, for A and B maps in order to emphasize spatial profiles. In C, the color scale ranges from 0 to 1. The performed calculations yield equal values in the center of the phantom for the maps shown in A and B . (D) Sum of the eight individual B
1 nitude maps obtained when transmitting one channel at a time. (E) B
1 transmit magtransmit magnitude map obtained when transmitting through 8 channels simultaneously (“volume coil” case).
Note that, unlike for receive B
1 a unique data set. (F) Ratio of the magnitude of “volume coil” transmit B
1 the eight magnitude transmit B comparison, maps in A and B could not be obtained from
1 over the sum of
. Color tables were independently adjusted, in arbitrary units, for A and B maps. In C the color scale ranges from 0 to 0.82. Reprinted with persmission from [24,25].

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Figure 6 . Transmit B
1 field summations for 300 MHz (A,B,C) and 64 MHz (D,E,F) obtained through simulations. (A,D) Sum of the eight transmit magnitude maps obtained when simulating transmission with one channel at a time; (B,E) B
1 transmit magnitude map obtained when simulating transmission through 8 channels simultaneously (“volume coil” case). (C,D) Ratio of, respectively, the map shown in
B over the map shown in A, and the map shown in E over the map shown in D. Color tables were independently adjusted, in arbitrary units, for the A, B, D, and E maps. In C and F the color scales range from 0 to 1. Reprinted with permission from [24,25].
Figure 7 . 4 Tesla head and body images from the University of Minnesota. Head images are obtained with 2D (top) and 3D MDEFT (bottom) [68]. Body images are obtained with a TEM body coil used for transmit and signal reception and EKG gated true FISP. Reprinted with permission from [37].

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Figure 8
T
1
. Dependence of GM and WM 1 H
2
O T
1 values on B0. The solid squares represent data obtained from a ~0.05 mL ROI selected from the putamen, an internal gray matter structure. The solid circles represent T
1 data obtained from a 0.2-mL ROI selected from frontal white matter. Reprinted with permission from [67].
Figure 9 . High-resolution imaging at 7 Tesla using a 16-channel array coil. (A) Gradient recalled echo (FLASH) image with some inherent T
2
* (512 x 512); (B)
Turboflash (4-segment acquisition) image 0.25 x 0.25 x 4 mm
3
T
1
-weighted IR-
(~1K x 1K), 3.2 min Acq.
Time, TI = 1.45 s.

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Figure 10 . Imaging Alzheimer’s plaques in genetically modified mice using MR at 9.4 Tesla. Image resolution is 60 x 60 x 120 μ m 3 . TE = 53 ms, and imaging time was 1 hour 7 minutes. The figure shows a three-way correlation in a 26-month AD mouse. Panels A, C, and E are full FOV and panels B, D, and F illustrate a magnified sub-sampled area centered on the hippocampus of the parent image to its left. The numbered arrows point to identical spatial coordinate positions in the common space of the three spatially registered volumes (in vivo, ex vivo, histological) using a linked cursor system. Spatially matched in-vivo (A,B), ex-vivo (C,D), and histological sections (E,F) conclusively demonstrate that the dark areas seen in vivo do indeed represent plaques. (E) Scale bar = 500 ìm. (F) Scale bar = 200 μ m. Plaque sharpness in vivo approaches but is clearly inferior to that obtained on ex-vivo MRI.
Figure 11 . 7 Tesla, 1 x 1 x 3 mm 3 fMRI functional images in two sagittal planes in the human visual cortex obtained with T
2
* BOLD contrast, showing positive and negative signal intensity changes (A). Acquisition parameters were
4-segment gradient recalled echo EPI, TR = 150 ms per segment, TE = 20 ms. Reproducibility of images is illustrated in (B) for two consecutive runs in the same subject; the pixels that are deemed to have shown a statistically significant increase are color-coded as darker red for positive BOLD signals and darker blue for the negative BOLD signals. (C) The cross-correlation of all pixels with the activation template for the two runs against each other.
Adapted with permission from [83].

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Figure 12 . Experimental evaluation of blood contribution to 7 T Hahn spin echo functional images. Figure shows normalized HSE BOLD percent changes as a function of b value for short and long echo times at 4 and 7 T in a region of interest (ROI) defined in the b = 1 map. Percent changes were normalized to the BOLD change at b = 1 s/mm 2 for each subject and averaged for each field. Closed rectangles and circles indicate HSE data with TE of 65 ms at 4 T ( n = 7) and with TE of 55 ms at 7 T ( n = 4), respectively. Open rectangles and circles indicate HSE data with TE of 32 ms at 4 and 7 T, respectively, for two subjects at each field (six repeated measurements were made for each subject). Error bars are standard errors of the means. For long TE, the attenuation was not statistically different between 4 and 7 T ( p > 0.05). Reprinted with permission from [70].
Figure 13 . Simulation of the intravascular BOLD signal change, Δ S blood
/( Δ S blood
+ Δ S tissue
), as a function of echo time for a Hahn spin echo at 1.5, 3, 4, 7, and 9.4 T. We assumed a venous blood volume of 0.05, no stimulus-evoked blood volume change, and an increase in venous oxygenation level from 0.6 to 0.65 during stimulation. The T
2 values of blood water at different field strengths and as a function of echo time were calculated from experimental data (see
[70] for details). Reprinted with permission from [70].

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Figure 14 . Stimulus-invoked percent signal change at 7 Tesla in the human visual cortex. (A) Histograms of percent changes of repeated (different days) HSE (in blue) and GE (in red) BOLD studies from the same subject, in the same anatomical location in. (B) Percent signal change vs. basal image signal intensity (normalized). Data were extracted from functional images obtained with 0.5 x 0.5 x 3 mm 3 spatial resolution at 7 Tesla, an example of which is shown in (C). Reprinted with permission from [98].
Figure 15.
Noise characteristics of functional imaging data at 7 Tesla: (A) Plots depicting the variance of thermal noise ( σ 2
Therm
Parameter σ 2
) and image-to-image fluctuations in the brain signals due to physiological processes ( σ
Phys
2
Phys
).
was calculated as the difference of the variance of temporal fluctuations of brain signals in the fMRI time series minus the variance of thermal noise. The data are for a single subject. In (B) the ratio of standard deviations ( σ 2
Phys
/ σ 2
Therm
) for all subjects for both GE (blue) and HSE (red). In (A), the data represent the average of all pixels in the brain of a single subject. In (B) the data represent the average over all subjects and all pixels. The error bars in (B) reflect the SD of the differences among the different subjects. In these plots, image signal intensities were normalized for the different resolutions so that effectively noise is decreasing as opposed to both signal and noise increasing as voxel size is increased. Reprinted with permission from [98].

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Figure 16 . (A) Ultimate parallel imaging performance in terms of the geometry factor, calculated for a spherical object with a diameter of 20 cm, assuming average in-vivo brain permittivity and conductivity. The dashed line indicates the transition from favorable to prohibitive geometry factors, with the threshold set arbitrarily at g = 1.2. According to this analysis, high field is expected to facilitate enhanced parallel imaging performance. (B)
Geometry factor as obtained experimentally for the center of the sphere, plotted vs. the reduction factor R and B
0
. Note the close correspondence between this plot and the theoretical prediction of the ultimate geometry factor (A). These results show that high field facilitates higher reduction factors, leading to higher parallel imaging performance.
Reprinted with permission from [20].
Figure 17.
Direct detection of natural abundance 17 O in the human visual cortex at 7 Tesla.
(A) 17 O chemical shift imaging of natural abundance H
2
17 O in the coronal orientation acquired from the human visual cortex. (B) A representative 17 O spectrum from one central voxel as shown in (A). 8.5 sec of image acquisition time and 6.6 ml voxel size.

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Figure 18.
Simulated
1
H spectrum of glutamate and glutamine at four different field strengths assuming that the linewidths increase linearly with the magnetic field magnitude. Adapted with permission from [179].
Figure 19 . 1 H NMR spectrum of the human brain at 7 T acquired over the occipital lobe, largely over gray matter, using STEAM (TE = 6 ms, TR = 5 s, VOI = 8 ml) for single shot
( N =1) and for 64 averages. Adapted with permission from [179].

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Figure 20 . Direct measurement of neuronal ATP synthesis rate in the normal human brain at 7 Tesla. 31 P spectra were acquired with (A) and without (B) complete saturation of the γ -
ATP resonance ( t sat
= 6.62 s); the arrows indicate the position of saturation in the two spectra. The difference of the two spectra (A–B) illustrates that there is transfer of saturation to phosphocreatine (PCr) as a result of the creatine kinase reaction and to inorganic phosphate (Pi) due to ATP synthesis. The latter is taught to represent neuronal oxidative ATP synthesis rate. Reprinted with permission from [183].

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Figure 21 . In-vivo
13
C spectra from a 400-
μ l volume in the rat brain, acquired using the modified DEPT sequence. (a) Natural abundance spectrum acquired for 3.5 hours (5120 scans, TR 2.5 s); (b) spectrum recorded for 1.8 hour (2560 scans, TR 2.5 s) during an infusion of 70%-enriched [1,6-
13
C
2
]glucose. Acquisition was started 1.8 hour after the beginning of glucose infusion; (c) expansion of (b) showing the detection of doubly labeled isotopomers of glutamate, glutamine and aspartate. Note the triplet of glutamate (Glu–C3T) at 27.9 ppm, corresponding to glutamate labeled simultaneously at the C2, C3 and C4 positions. Processing consisted of zero-filling, filtering (5-Hz Lorentzian line broadening for (a) and 2-Hz Lorentzian-to-Gaussian resolution enhancement for (b) and (c)), and fast
Fourier transform. No baseline correction was applied. Reprinted with permission from
[199].