Utility of In Vivo Magnetic Resonance Imaging Is Predictive of Gestational Diabetes Mellitus During Early Pregnancy

Abstract

Context: Gestational diabetes (GDM) imposes long-term adverse health effects on the mother and fetus. The role of magnetic resonance imaging (MRI) during early gestation in GDM has not been well-studied.

Objective: To investigate the role of quantitative MRI measurements of placental volume and perfusion, with distribution of maternal adiposity, during early gestation in GDM.

Methods: At UCLA outpatient antenatal obstetrics clinics, ∼200 pregnant women recruited in the first trimester were followed temporally through pregnancy until parturition. Two placental MRI scans were prospectively performed at 14 to 16 weeks and 19 to 24 weeks gestational age (GA). Placental volume and blood flow (PBF) were calculated from placental regions of interest; maternal adiposity distribution was assessed by subcutaneous fat area ratio (SFAR) and visceral fat area ratio (VFAR). Statistical comparisons were performed using the two-tailed t test. Predictive logistic regression modeling was evaluated by area under the curve (AUC).

Results: Of a total 186 subjects, 21 subjects (11.3%) developed GDM. VFAR was higher in GDM vs the control group, at both time points (P < 0.001 each). Placental volume was greater in GDM vs the control group at 19 to 24 weeks GA (P = 0.01). Combining VFAR, placental volume and perfusion, improved the AUC to 0.83 at 14 to 16 weeks (positive predictive value [PPV] = 0.77, negative predictive value [NPV] = 0.83), and 0.81 at 19 to 24 weeks GA (PPV = 0.73, NPV = 0.86).

Conclusion: A combination of MRI-based placental volume, perfusion, and visceral adiposity during early pregnancy demonstrates significant changes in GDM and provides a proof of concept for predicting the subsequent development of GDM.

Keywords: gestational diabetes; maternal adiposity; placenta MRI; prediction modeling; visceral and subcutaneous fat.

Figure 1.

A. Study timeline. This figure depicts the study timeline. The middle row (Gestational Age) represents the temporal course of the pregnancy. The top row (MRI Timeline) depicts the 2 MRI time points, at 14-16 weeks and 19-24 weeks. The bottom row (Study Visits) depicts the timeline of recruitment (at 6-8 weeks) and the 4 study visits planned for each subject (at 11-14 weeks, 20-29 weeks, 36 weeks, and at delivery). Recruitment flowchart. Abbreviations: D&C, dilation and curettage; GA, gestational age; GDM, gestational diabetes; MRI, magnetic resonance imaging.

Figure 2.

Placental volume. To determine placental volume, placental regions of interest were traced manually. The two images above are the same; the top image (A) shows an MRI slice in the coronal plane of the placenta and fetus; the bottom image (B) shows the placental region traced in green. This was repeated for all MRI slices in which the placenta was visible, for each the axial, coronal, and sagittal planes, allowing for the determination of placental volume.

Figure 3.

Maternal adiposity analysis. A) a sagittal plane MRI image (top left) of a representative subject showing the corresponding axial plane (top right) at lumbar vertebral level L5 (horizontal green line in the sagittal plane). B) The subcutaneous fat area of image A is highlighted in green. C) The total body area of image A is highlighted in pink. D) The visceral fat area of image A is highlighted in red. E) The total visceral area of image A is highlighted in blue. F) The uterus in image A is highlighted in yellow.

Figure 4.

Placental function analysis. A) Scatter plots showing placental volumes (in cubic centimeters) plotted by gestational age (GA). Control group volumes are represented at the first MRI time point of 14-16 weeks GA (blue dots) and second MRI time point of 19-24 weeks GA (green dots). The gestational diabetes (GDM) group is represented by red triangles, at the first (filled red triangle) and second (open red triangle) MRI time point. B) Mean and standard deviations for values of regions of average placental blood flow (PBF, in mL/100 g/min) in all subjects, overweight/obese subjects, and nonobese subjects. Blue bars represent the control group; red bars represent the GDM group. The graph shows PBF at the first and second MRI time points (MRI 1: 14-16 weeks GA, and MRI 2: 19-24 weeks GA, respectively). The PBF values trended lower in the gestational diabetes (GDM) group for every comparison between the respective control group values. C) Mean and standard deviations for values of regions of high placental blood flow (hPBF, in mL/100 g/min) in all subjects, overweight/obese subjects, and non-obese subjects. Blue bars represent the control group; red bars represent the GDM group. The graph shows hPBF at the first and second MRI time points (MRI 1: 14-16 weeks GA, and MRI 2: 19-24 weeks GA, respectively). The hPBF values trended lower in the gestational diabetes (GDM) group for every comparison between the respective control group values.

Figure 5.

Receiver operating characteristic curves for subcutaneous fat area ratio (SFAR) and visceral fat area ratio (VFAR) analysis at 14-16 weeks gestational age (GA) and at 19-24 weeks GA, for the outcome of gestational diabetes. Areas under the curve (AUC) for SFAR were 0.51 at 14-16 weeks GA (A, top left), and 0.50 at 19-24 weeks GA (B, top right). AUCs for VFAR were 0.82 at 14-16 weeks GA (C, bottom left), and 0.77 at 19-24 weeks GA (D, bottom right).

Figure 6.

MRI images. Comparison of representative MRI images of two different subjects in the axial plane. A patient with gestational diabetes (GDM) is shown in the top image (A), versus a patient who did not develop GDM in the bottom image (B), at similar axial MRI level. Both patients had a pre-pregnancy BMI in the Normal weight, yet visceral adiposity is visibly higher in the GDM patient (A).

Figure 7.

Multiple logistic regression analysis for the outcome of gestational diabetes (GDM) at 14-16 weeks gestational age (GA), and 19-24 weeks GA. Receiver operating characteristic curves of the multiple logistic regression analysis using VFAR, high placental blood flow, and placental blood flow for the outcome of GDM. The top row depicts the analysis at the first MRI time point of 14-16 weeks GA. “All cohort” (A, top left) includes subjects of any BMI. “Obese cohort” (B, top middle) includes overweight and obese subjects. “Non-obese cohort” (C, top right) includes underweight and Normal weight subjects. The area under the curves are A. 0.83, B. 0.84, and C. 0.90, respectively. The bottom row depicts the analysis at the second MRI time point of 19-24 weeks GA. “All cohort” (A, bottom left) includes subjects of any BMI. “Obese cohort” (B, bottom middle) includes overweight and obese subjects. “Non-obese cohort” (C, bottom right) includes underweight and Normal weight subjects. The area under the curves are A. 0.81, B. 0.82, and C. 0.83, respectively.