Comparison of amniotic fluid volumetry between fetal sonography and MRI - Correlation to MR diffusion parameters of the fetal kidney

Abstract

Objective: Determine whether amniotic fluid volume (AFV) determination by magnetic resonance imaging (MRI) can be compared with ultrasound based amniotic fluid index (AFI) and whether diffusion weighted imaging (DWI) of the fetal kidneys can be used as surrogate marker for the assessment of AFV and fetal kidney function. Methods:In the period from August 2013 to September 2014 prospective evaluation of AFV based on TRUFI MRI in 2 spatial planes (AFVMRI) and ultrasound based AFI. Inclusion criteria for the evaluation were: 1) Full image of the fetus (including AF and placenta) in an MR-study in at least two planes (sagittal and coronal), 2) Layer thickness 8 mm, 3) DWI-images of the fetal kidney in two planes (sagittal and transverse to the fetus). ROI analysis of the ADC values in normal kidneys and in pathological fetal kidneys (CAKUT) as well as the correlation of AFVMRI vs. AFI, renal volume and ADC were performed. Results:The correlation between AFI (13.60 ± 2.46 cm) and AFVMRI (579 ± 353 mL) was 0.69 (p=0.03). There was no significant correlation between AFVMRI and kidney volume, between AFVMRI and ADC700 and ADC800. The B700-ADC values of fetuses with CAKUT (n=14) were considerably higher than the values in fetuses with healthy kidneys. Conclusion:Compared to AFI, AFVMRI showed higher accuracy, but was associated with higher time consumption. Thus it cannot be routinely recommended for the purpose of AFV-determination alone. MRI can be used to establish a relationship between kidney diffusion parameters, renal volume, GA and AFV in fetuses with CAKUT.

AFNet Algorithm for Automatic Amniotic Fluid Segmentation from Fetal MRI

“…Throughout gestation, various dynamic processes, such as fetal breathing and swallowing, regulate amniotic fluid [2]. Disruptions in these dynamic processes can result in low amniotic fluid volume (oligohydramnios) or high amniotic fluid volume (polyhydramnios), which occur in approximately 1-2% of pregnancies due to underlying causes and are associated with poor pregnancy outcomes [1,[3][4][5][6][7][8].…”

“…Quantifying amniotic fluid volume is often challenging using non-invasive fetal imaging techniques, primarily ultrasound (US). The Single Deepest Pocket (SDP) and Amniotic Fluid Index (AFI) are the most commonly employed ultrasound-based techniques [2][3][4][5][6][7]. While SDP and AFI can reasonably estimate amniotic fluid volume (AFV) disorders [8], they lack precision in volumetric measurements.…”

“…Fetal Magnetic Resonance Imaging (MRI) offers high soft tissue contrast compared to ultrasound [5,[11][12][13]] and provides more comprehensive information [14] for diagnosing specific fetal or maternal abnormalities, such as oligohydramnios or polyhydramnios. The use of MRI in pregnancies is considered safe by the Canadian Association of Radiologists, particularly after the first trimester and without gadolinium-based contrast agents [15].…”

AmnioML: Amniotic Fluid Segmentation and Volume Prediction with Uncertainty Quantification

“…While doctors oftentimes estimate AF volume via a visual inspection of ultrasound exams, precise estimation typically requires the use of higher-quality magnetic resonance images (MRI) (Hellinger and Epelman 2010;Kubik-Huch et al 2001;Moschos et al 2017;Prayer, Brugger, and Prayer 2004). After obtaining the images, medical experts segment the areas in each slice of the MRI containing AF (see Figure 1) and, from this segmentation, the AF volume can be estimated.…”