Signal-to-noise ratio and parallel imaging performance of commercially available phased array coils in 3.0 T brain magnetic resonance imaging.

The signal-to-noise ratio (SNR) and parallel imaging (PI) performance of two commercial phased-array coils (PACs) were examined in magnetic resonance imaging (MRI) of the brain. All measurements were performed on a 3.0 T MRI instrument. The SNR and PI performance were evaluated with 32-channel and 15-channel PACs. A gradient echo sequence was used for obtaining images of a phantom. SNR and geometry factor (g-factor) maps were calculated from two images with identical parameters. Horizontal and vertical profiles were taken through the SNR maps in the axial plane. The average g-factor was measured in a circular region of interest in the g-factor maps for the axial plane. The SNR map of the 32-channel coil showed a higher SNR than that of the 15-channel coil at the phantom's posterior and lateral surfaces. The SNR profiles for the 32-channel coil also showed a 1.3-fold increase at the phantom's center. The average g-factor of the 32-channel coil was lower than that of the 15-channel coil at the same acceleration factor. These results indicate that the 32-channel coil can provide a higher spatial resolution and/or a faster imaging speed. Horizontal and vertical profiles are useful for evaluation of the performance of commercially available PACs.

Ionising irradiation-induced inhibition of differentiation of C3H10T1/2 cells to the osteoblastic lineage.

PURPOSE: Previous studies using mouse osteoblast derived MC3T3-E1 and mouse myoblast derived C2C12 cells have not completely explained the mechanisms responsible for osteoradionecrosis. Thus, the aim of this study was to advance the in vitro experimental approaches for investigations of osteoradionecrosis. MATERIALS AND METHODS: The pluripotent stem cell line, mouse embryo derived C3H10T1/2, was treated with all-trans-retinoic acid after irradiation (1, 3 and 6 Gy), and cell growth, cell cycle distribution, apoptosis, and alkaline phosphatase (ALP) activity were assessed. RESULTS: We demonstrated that ionising radiation inhibited the growth and decreased ALP activity in C3H10T1/2 cells. The decrease in cell growth was not due to apoptosis but was due to cell cycle delay. The decrease in ALP activity persisted in cells that were induced to an osteoblastic lineage 24 h after irradiation. CONCLUSIONS: Our results suggested that C3H10T1/2 cells are suitable for investigating the effects of ionising irradiation on osteoblast precursor cells.

Physiological changes in human cardiac sympathetic innervation and activity assessed by (123)I-metaiodobenzylguanidine (MIGB) imaging.

BACKGROUND: Physiologic changes in the human sympathetic nervous system (SNS) may be associated with cardiovascular diseases, so the present study assessed the age and gender differences in global cardiac SNS in normal subjects. METHODS AND RESULTS: The 163 subjects (74 men, 89 women; age range 40-89 years) whose coronary arteriogram was normal, and who had no other cardiac or neurohormonal diseases, and no medication affecting the autonomic nervous system were included. All study subjects underwent metaiodobenzylguanidine imaging. Both initial and delayed heart-to-mediastinum (H/M) ratios had a significant gender difference and showed a progressive decrease with aging. In addition, the initial H/M ratio had a significant positive correlation with the delayed H/M ratio (r=0.89, P<0.0001). Females (50-59 years) demonstrated significantly higher delayed H/M ratio than males of the same age. After the age of 60, the delayed H/M ratio in females progressively decreased with aging, similar to males. As for the washout rate, both genders had a significantly progressive increase with aging. In addition, there was a significant decrease in the delayed H/M ratio in 10 females with surgical menopause compared with 15 age-matched females without surgical menopause. CONCLUSION: Cardiac SNS appears to be regulated by various physiological factors.