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Results: 7

1.
FIGURE 1

FIGURE 1. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

PET protocol used to quantify MRO2 in BAT at rest and during cold stress. After quantitative assessment of oxidative metabolism, patient underwent 18F-FDG PET/CT to correlate MRO2 with 18F-FDG–derived SUV measures. Indirect calorimetry was performed at rest and during exposure to cold stress.

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
2.
FIGURE 4

FIGURE 4. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

Absolute blood flow during rest and cold stress in BAT and WAT in high-BAT and low-BAT groups. (A) Blood flow in activated BAT (high-BAT) is about 50% higher than in nonactivated BAT (low-BAT). Increase in blood flow was significantly higher in high-BAT group than in low-BAT group, although both increases were significant between rest and cold stress. (B) Blood flow in WAT was significantly higher in high-BAT group at both rest and cold stress than in low-BAT group. However, no significant differences were observed between rest and cold stress in either group.

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
3.
FIGURE 2

FIGURE 2. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

Representative images showing BAT 18F-FDG uptake in subjects belonging to high-BAT and low-BAT groups. Presence of cold-activated BAT was derived on basis of combined conditions of HU range (–250 to –50) and SUV >. 2. ROIs were defined at location of shoulder muscle (broken line) and WAT (not shown). (A) Nine of 25 subjects showed spatially extensive cold-activated BAT (high-BAT group, mass > 10 g). (B). The remaining 16 subjects showed either no cold-activated BAT or only small depots (low-BAT group, mass < 10 g).

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
4.
FIGURE 6

FIGURE 6. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

(A) Relationship between blood flow in BAT (both at rest and during stress) and BAT DEE (●), as well as estimates of upper limit for BAT DEE (○), calculated using almost complete oxygen extraction (OEF = 0.95) and generous estimate of activated BAT mass (SUV threshold of 1.5). Maximal contribution of activated BAT to DEE is in range of 15–25 kcal/d. We determined significant correlation (P = 0.03), indicating that tissue perfusion is an important determinant of DEE in activated BAT. (B) Correlation between maximal SUV in BAT and DEE in those subjects who had SUV > 2.0 (indicative of activated BAT). We found significant correlation between glucose uptake and DEE (P = 0.02).

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
5.
FIGURE 3

FIGURE 3. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

Distribution of amount of BAT mass, maximal SUV, and lean body mass in high-BAT group (●, n = 9, 8 women and 1 man) and in low-BAT group (○, n = 16, 7 women and 9 men). Error bars represent SD of measurements. (A) Amount of BAT mass was highly variable, displaying bimodal distribution. Accordingly, subjects were stratified into high-BAT and low-BAT groups. (B) Maximal SUV in BAT was significantly higher in high-BAT group than in low-BAT group (P < 0.01). (C) Because of higher male-to-female ratio in low-BAT group, lean body mass showed tendency toward higher values in low-BAT group.

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
6.
FIGURE 5

FIGURE 5. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

MRO2 in BAT, muscle, and WAT observed in high-BAT and low-BAT groups. Error bars represent SEM. (A) In high-BAT group, MRO2 in BAT at rest was about twice as high as that in low-BAT group. After cold exposure, MRO2 increased by about 50% in high-BAT group but remained at same level in low-BAT group. In contrast, MRO2 in WAT was higher in low-BAT group both at rest and at cold exposure. Finally, MRO2 in muscle was similar for both groups at rest and after cold exposure. (B) Highly significant correlation (P = 0.01) was observed between MRO2 in BAT (●), WAT (○), and muscle (×) tissue, indicating that tissue perfusion is main determinant of oxidative metabolism in all 3 types of tissue.

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.
7.
FIGURE 7

FIGURE 7. From: 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat.

NIRS-derived measures (R1 and R2) in BAT and WAT. (A) Comparison between R1 and R2 in high-BAT (gray bars) and low-BAT (hatched bars) groups. Consistent with higher BAT oxygen depletion in high-BAT group, R1 ratio in this group tended to be significantly lower than in low-BAT group (P = 0.08). R2 ratios were similar in both groups, indicating that oxygen demand in abdominal subcutaneous WAT is comparable in the 2 groups. (B) Relationship between BAT MRO2 and R1 in both high-BAT (●) and low-BAT (○) groups. Significant correlation between R1 and MRO2 was observed in high-BAT group, indicating higher oxygen depletion in venous blood (reflected in low R1 values) at high MRO2 in BAT. In contrast, no significant relationship between R1 and MRO2 was found in low-BAT group.

Otto Muzik, et al. J Nucl Med. ;54(4):10.2967/jnumed.112.111336.

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