Table 4.

Placental R₂* measurements in normal subjects using free-breathing radial MRI at 3 T. Mean R₂* (± standard deviation), R₂* range, coefficient of variation (CV), and mean (± standard deviation) change in R₂* over gestational age (GA) (ΔR₂*) are reported for 14-18 weeks and 19-23 weeks GA. Analysis was performed for all subjects (N = 30), and again for the subjects separated into anterior (N = 15) versus posterior (N = 15) placenta implantation positions.

	GA (Weeks)	R2* (s−1)	R2* Range (s−1)
All Subjects (N = 30)	14-18	12.94 ± 2.66	7.91 – 20.29
	19-23	13.19 ± 1.87	9.64 – 16.88
Anterior (N = 15)	14-18	12.93 ± 2.06	8.91 – 17.34
	19-23	13.64 ± 1.67	10.80 – 16.88
Posterior (N = 15)	14-18	12.94 ± 3.22	7.91 – 20.29
	19-23	12.73 ± 2.01	9.64 – 16.16

	GA (Weeks)	CV (Arbitrary Units)	ΔR2* (s−1/Week)
All Subjects (N = 30)	14-18	0.632 ± 0.121◆	0.102 ± 0.728
	19-23	0.577 ± 0.128◆
Anterior (N = 15)	14-18	0.587 ± 0.108◆	0.191 ± 0.723
	19-23	0.488 ± 0.076◆#
Posterior (N = 15)	14-18	0.677 ± 0.120	0.013 ± 0.747
	19-23	0.666 ± 0.106#

^◆Statistically significant differences with P < 0.05 between 14-18 weeks and 19-23 weeks GA.

^#Statistically significant differences with P < 0.001 between anterior and posterior placentas.