Figure 1.

Infant rat growth (A) and anesthesia management during MRI (B,C). (A) illustrates the average weight of infant rats (N = 13; g ± SD) from postnatal day (PD) 0, considered the day of birth, through PD17 for both female (N = 6) and male (N = 7) rats. No significant differences between sexes were observed at any of the time points. (B) illustrates average levels of administered inhalational anesthetic, Isoflurane/O₂ at 1 L/min via nose cone (% ± SD; N = 13), at different time points during the scanning. Following uniform induction with 3% Isoflurane/O₂ at 1 L/min, anesthetic level was decreased to maintain a consistent respiratory rate in a narrow range between 45 and 50 breaths/min (C). Analysis included the values at the start of the first (anatomical RARE) scan, as well as the start of the second (functional EPI) scan. Average value of Isoflurane level during the length of the functional scan (based on the two 5 min interval measurements/animal) and its average corresponding respiratory rate are shown in the far-right columns (B,C). Respiratory rate was used as an indirect measure of steady and uniform anesthetic depth during functional scan. No differences in respiratory rate (breath/min ± SD) were noted between different time points analyzed [C; induction, T2 start, EPI start, average EPI/10 min; F_{(3, 47)} = 1.11, p = 0.35]. One-way ANOVA with Tukey HSD test.