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Purpose: We used a whole-brain, isotropic-voxel acquisition technique to improve the geometric distortion in diffusion-weighted (DWI) and diffusion tensor imaging (DTI) in coronal directions, which is remarkable at high magnetic fields. Materials and Methods: We performed magnetic resonance imaging of 17 healthy volunteers using a 3T scanner and obtained coronal DWI/DTI as well as coronal images that were reformatted from isotropic volume data acquired by 1.6-mm-thick axial DWI/DTI. We visually evaluated the degree of image distortion and quantitated the findings by co-registration analysis. Results: In-plane geometric distortions in coronal DWI/DTI, particularly at the frontal base and medial temporal lobe, were dramatically diminished when the isotropic-voxel acquisition technique was used. Quantitative measurement revealed a reduction in areas of misregistration, but not their absence, in reformatted coronal images, mainly because of distortion in the anteroposterior direction in the source images. Conclusion: The isotropic-voxel DWI/DTI technique enabled acquisition of coronal images that represented anatomical details accurately with permissible spatial distortion while maintaining spatial resolution, even at 3T.

Background and Purpose— Cerebrovascular reactivity (CVR) to acetazolamide is a key parameter in determining the severity of hemodynamic impairment in patients with major cerebral artery occlusive disease. Perfusion-weighted MRI (PW MRI) can measure the cerebral blood volume (CBV) as an indicator of hemodynamic impairment. CBV measured by PW MRI was compared with CVR measured by positron emission tomography (PET). Methods— Twelve normal subjects and 17 patients with major cerebral artery occlusive disease underwent PW MRI and PET. The images were coregistered with 3-dimensional spoiled gradient-recalled acquisition images. Quantitative PW MRI-CBV maps were generated using the indicator dilution method with arterial input function. One large cortical region of interest for each unilateral middle cerebral artery territory was determined on each image. PET-CVR was calculated by measuring cerebral blood flow before and after acetazolamide challenge. Results— A significant negative correlation was observed between PW MRI-CBV and PET-CVR ( r =−0.713; P Conclusions— The PW MRI-CBV method can simply and accurately identify patients with hemodynamic impairment without exposure to ionizing radiation.

Purpose: To investigate age-related changes in the locus ceruleus (LC) in healthy subjects using neuromelanin magnetic resonance (MR) imaging at 3 Tesla. Methods: We examined 64 healthy volunteers (aged 23 to 80 years) using neuromelanin-sensitive T1-weighted images and measured the contrast of areas of high signal intensity corresponding to the LC. Results: A pair of punctate areas of high signal intensity that represented neuromelanin within the noradrenergic neurons of the LC was easily recognized in all subjects. The contrast ratio of the LC to the adjacent pontine tegmentum increased to the age of 40 to 59 years and gradually and significantly decreased in elderly subjects. This correlates well with pathologically proven age-related changes in neuromelanin content within the LC. Conclusion: Age-related variance should be considered when determining the existence of abnormalities in the LC.

The temperature change of the fractional dissociation of imidazole (alpha-imidazole) in resting human lower leg muscles was measured noninvasively using (1)H-nuclear magnetic resonance spectroscopy at 3.0 and 1.5 T on five normal male volunteers aged 30.6 +/- 10.4 yr (mean +/- SD). Using (1)H-nuclear magnetic resonance spectroscopy, water, carnosine, and creatine in the muscles could be simultaneously analyzed. Carnosine contains imidazole protons. The chemical shifts of water and carnosine imidazole protons relative to creatine could be used for estimating temperatures and alpha-imidazole, respectively. Using the chemical shift, the values of temperature in gastrocnemius (Gast) and soleus muscles at ambient temperature (21-25 degrees C) were estimated to be 35.5 +/- 0.5 and 37.4 +/- 0.6 degrees C (means +/- SE), respectively (significantly different; P0.01). The estimated values of alpha-imidazole in these muscles were 0.620 +/- 0.007 and 0.630 +/- 0.013 (means +/- SE), respectively (not significant). Alternation of the surface temperature of the lower leg from 40 to 10 degrees C significantly changed the temperature in Gast (P0.0001) from 38.1 +/- 0.5 to 28.0 +/- 1.2 degrees C, and the alpha-imidazole in Gast decreased from 0.631 +/- 0.003 to 0.580 +/- 0.011 (P0.05). However, the values of alpha-imidazole and the temperature in soleus muscles were not significantly affected by this maneuver. These results indicate that the alpha-imidazole in Gast changed significantly with alternation in muscle temperature (r = 0.877, P0.00001), and its change was estimated to be 0.0058/ degrees C.

A large amount of chromosomal DNA is degraded during programmed cell death and definitive erythropoiesis. DNase II is an enzyme that digests the chromosomal DNA of apoptotic cells and nuclei expelled from erythroid precursor cells after macrophages have engulfed them. Here we show that DNase II-/-IFN-IR-/- mice and mice with an induced deletion of the DNase II gene develop a chronic polyarthritis resembling human rheumatoid arthritis. A set of cytokine genes was strongly activated in the affected joints of these mice, and their serum contained high levels of anti-cyclic citrullinated peptide antibody, rheumatoid factor and matrix metalloproteinase-3. Early in the pathogenesis, expression of the gene encoding tumour necrosis factor (TNF)-alpha was upregulated in the bone marrow, and administration of anti-TNF-alpha antibody prevented the development of arthritis. These results indicate that if macrophages cannot degrade mammalian DNA from erythroid precursors and apoptotic cells, they produce TNF-alpha, which activates synovial cells to produce various cytokines, leading to the development of chronic polyarthritis.

Purpose: To investigate the difference in enhancement effects and relaxivities of the gadolinium chelate at 1.5 and 3 Tesla (T) and to elucidate the contribution of the high magnetic field to contrast enhancement in spin-echo (SE) and gradient-echo (GRE) images. Methods: Phantoms containing water with or without gadopentetate dimeglumine (Gd-DTPA) at different concentrations were scanned using 1.5T and 3T MRI scanners of the same manufacturer and under the same temperature conditions and scanning parameters. Relaxivities of gadolinium, R1 and R2, were estimated from serial T1 and T2 values of the phantoms using linear regression. Contrast enhancement ratios in SE and GRE T1-weighted images were compared at 1.5 and 3T. Results: The R1 and R2 of Gd-DTPA at 1.5 and 3T were 4.79 and 5.14, and 4.50 and 5.09, respectively. Although the relaxivities at 3T were slightly lower than those at 1.5T, the contrast enhancement ratio improved in both SE and GRE images as a result of T1 prolongation of the water at 3T. Conclusion: The decrease in relaxivities of the Gd-DTPA at 3T appears to be so small that T1 prolongation of the water improves contrast enhancement, suggesting a potential clinical advantage in administration of Gd-DTPA at high field strength.