Establishment of Normal ADC Values and Morphological Parameters of the Fetal Kidney Using Magnetic Resonance Imaging and Analysis of their Correlation with Gestational Age

Yangmei Pu¹,Shuzhen Ma¹,Qiyan Wang¹,Ran Li¹,Xuejing Zou¹,Yuchen Liu²,Min Kang^1✉

1.Department of Radiology, Sichuan Provincial Maternity and Child Health Care Hospital, Chengdu, Sichuan, China

2.MR Research, GE Healthcare, Beijing, China

Correspondence: Min Kang (1073297610@qq.com)

✉Corresponding author.

Abstract

Background

Fetal renal developmental abnormalities are among the most common congenital malformations and are associated with adverse perinatal outcomes. However, existing fetal magnetic resonance imaging (MRI) studies are limited by small sample sizes and the lack of comprehensive gestational age (GA)–specific reference ranges that integrate both morphological and functional parameters. This study aimed to establish multiparametric MRI reference ranges for normal fetal kidneys and to characterize their relationships with GA.

Methods

In this retrospective single-center observational study, 313 singleton pregnancies (GA 23–39 weeks) with normal postnatal urinary outcomes underwent 1.5T fetal MRI, including T2-weighted and diffusion-weighted imaging sequences. Morphological parameters [anteroposterior, transverse and longitudinal diameters, and mean renal parenchymal thickness (MRPT)] and functional parameters [T2 relative signal intensity (RSI-T2) and apparent diffusion coefficient (ADC)] were measured for both kidneys. Reproducibility was assessed using intraclass correlation coefficients (ICC). Correlations between MRI parameters and GA were analyzed, and linear regression models were constructed for ADC.

Results

All morphological and functional parameters demonstrated good to excellent intra- and inter-observer reproducibility (ICC > 0.75). Renal diameters and MRPT increased significantly with GA (r = 0.72–0.89; all P < 0.0001), reflecting progressive macroscopic growth. In contrast, ADC values decreased moderately with advancing GA (right kidney: r = − 0.47; left kidney: r = − 0.52; both P < 0.0001), consistent with microstructural and functional maturation. The regression equations for ADC (×10⁻³ mm²/s) were: ADC_right = 3.23 − 0.049 × GA and ADC_left = 3.46 − 0.058 × GA.

Conclusions

This study provides GA-stratified reference ranges for key morphological and functional MRI parameters of normal fetal kidneys in the second and third trimesters. These quantitative benchmarks may improve prenatal assessment of fetal renal growth and maturation and support earlier detection and characterization of fetal renal developmental abnormalities.

Trial registration

Not applicable.

Keywords

fetal kidney

magnetic resonance imaging

diffusion-weighted imaging

apparent diffusion coefficient

gestational age

renal development

reference values

prenatal diagnosis

Background

Fetal renal developmental abnormalities represent one of the most common categories of congenital malformations, accounting for approximately 15%–20% of all fetal anomalies. Severe bilateral renal abnormalities in particular are strongly associated with oligohydramnios, pulmonary hypoplasia, and increased perinatal mortality, thereby contributing to adverse pregnancy outcomes and lifelong health implications ^{[1, 2]}. Accurate prenatal evaluation of fetal renal morphology and function is therefore essential for determining the severity and type of abnormality, guiding perinatal management, informing prognosis, and supporting clinical decision-making.

Ultrasound remains the first-line modality for prenatal screening owing to its accessibility, low cost, and non-invasiveness. However, its ability to assess fetal renal function is limited, and its diagnostic value is often compromised by maternal body habitus, fetal position, amniotic fluid volume, and operator-dependent variability ^{[3, 4]}. In contrast, fetal magnetic resonance imaging (MRI) provides superior soft-tissue contrast and multiparametric functional assessment, increasingly demonstrating its complementary value in prenatal diagnosis. Among the available MRI biomarkers, the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) quantitatively reflects the microscopic diffusion characteristics of water molecules within renal tissue, enabling indirect assessment of renal microstructure and functional maturation ^{[5, 6]}. Previous studies have suggested that ADC values change with advancing gestational age and may serve as a quantitative marker of renal development ^{[7, 8, 19]}. For example, Savelli et al. reported a significant decline in fetal renal ADC values with increasing gestational age (ADC = 1.45 − 0.0104 × GA), whereas Manganaro et al. also demonstrated a decreasing trend (ADC = 1.69 − 0.0169 × GA; r = − 0.614). These findings consistently support the potential of ADC values as an imaging biomarker for monitoring fetal renal maturation.

Despite these promising observations, the existing literature exhibits several limitations. Many studies include small sample sizes, resulting in insufficient statistical power to define robust gestational age–specific reference ranges. Most studies have focused solely on functional parameters such as ADC, without integrating complementary morphological markers (e.g., renal diameters and parenchymal thickness), thereby providing an incomplete representation of renal developmental status. Moreover, inconsistent criteria for defining “normal fetal kidneys” across studies further limit the reliability and clinical applicability of published reference values.

To address these gaps, the present study aims to establish comprehensive multiparametric MRI reference ranges for normal fetal kidneys during the second and third trimesters, incorporating both morphological (renal size and parenchymal thickness) and functional (ADC and T2 relative signal intensity) indicators. By analyzing their correlations with gestational age, this study seeks to provide accurate, reproducible, and clinically meaningful imaging benchmarks for assessing fetal renal maturation, ultimately laying the groundwork for early detection and prognostic evaluation of fetal renal developmental abnormalities.

Methods

Study Design and Participants

This retrospective, observational study was conducted at Sichuan Provincial Maternity and Child Health Care Hospital and was approved by the Medical Ethics Review Committee of Sichuan Provincial Maternity and Child Health Care Hospital (Approval No. 20240419-076).

Written informed consent was obtained from all participants and/or their legal guardians prior to MRI examination. Pregnant women who underwent fetal MRI between June 2018 and June 2023 were screened for eligibility.

Inclusion criteria were: (1) singleton pregnancy; (2) gestational age between 23 and 39 weeks confirmed by first‑trimester ultrasonography; (3) MRI images of sufficient diagnostic quality to allow quantitative analysis; (4) normal fetal renal morphology and signal characteristics confirmed independently by two radiologists with ≥ 10 years of fetal MRI experience; and (5) a normal neonatal urinary system confirmed through 12–18‑month postpartum follow-up. These follow-up findings constituted the reference standard for defining “normal fetal kidneys.”

Exclusion criteria included: (1) maternal systemic diseases (e.g., gestational diabetes, hypertensive disorders of pregnancy, autoimmune or connective tissue disorders); (2) fetal anomalies affecting other organ systems or chromosomal abnormalities confirmed by prenatal or postnatal genetic testing; (3) severe MRI artifacts resulting from fetal motion or technical limitations that precluded reliable measurement; and (4) incomplete clinical data or loss to postpartum follow-up.

MRI Acquisition Protocol

Sequence	Technique	Slice thickness/gap	FOV (mm)	TR (ms)	TE (ms)	Flip angle	Matrix	Plane
T2WI	SS-FSE (Single-shot fast spin echo)	3 / 0	380 × 380	1800	100	/	320 × 256	Coronal, sagittal, axial
T2WI	Fiesta (Fast imaging employing steady-state acquisition)	3 / 0	380 × 380	3.5	1.4	90	224 × 224	Coronal, sagittal, axial
DWI	DWI (Diffusion-weighted imaging, b = 0,600 s/mm²)	4 / 0	380 × 380	4200	70	/	128×128	Coronal, axial
T1WI	FSPGR (Fast spoiled gradient echo)	4 / 1	380 × 380	155	min full	80	228 × 160	Coronal, axial

Image Processing and Quantitative Measurement

Image analysis was performed on an AW 4.7 workstation.

Two radiologists with 8 and 10 years of fetal MRI experience independently reviewed all datasets while blinded to gestational age and clinical information. Prior to the study, both radiologists underwent standardized training on ROI placement to ensure methodological consistency.

Functional parameters included:Apparent diffusion coefficient (ADC): Three circular ROIs (~ 15–20 mm²) were manually placed on ADC maps at the upper pole, renal hilum, and lower pole of each kidney, carefully avoiding renal sinus fat, collecting system, and peripheral susceptibility artifacts. Mean ADC was calculated from the three ROIs.T2 relative signal intensity (RSI‑T2): RSI‑T2 was computed as the ratio of renal parenchymal signal intensity to hepatic parenchymal signal intensity on axial T2WI obtained at comparable anatomical levels(RSI = SI_renal / SI_live).

Morphological parameters included:Anteroposterior diameter (AD): measured on axial T2WI at the renal hilum level.Transverse diameter (TD) and longitudinal diameter (LD): measured on coronal T2WI slices demonstrating maximal renal extent.Mean renal parenchymal thickness (MRPT): calculated from measurements at the upper, mid, and lower poles.

Each parameter was measured three times per kidney, and mean values were used for statistical analyses. To assess reproducibility, one radiologist repeated measurements on 30 randomly selected studies four weeks later. Intra-and inter-observer intraclass correlation coefficients (ICCs) were computed, with ICC > 0.75 considered indicative of good measurement reliability.Fetal renal T2-weighted images and ADC maps are shown in Fig. 1(a–f).

Fig. 1

Fetal renal at 31 weeks. (a–c) Transverse images: T2-weighted imaging (T2WI, a), diffusion-weighted imaging (DWI, b), and apparent diffusion coefficient (ADC) map (c). (d–f) Coronal images: T2WI (d), DWI (e), and ADC map (f).

Statistical Analysis

Statistical analyses were performed using SPSS version 26.0. Continuous variables were subjected to normality testing using the Shapiro–Wilk test. Normally distributed parameters were summarized using mean ± standard deviation and expressed with 95% reference intervals (x̄ ± 1.96s). For non-normally distributed data, percentile‑based (P2.5–P97.5) reference intervals were applied.Correlation between renal MRI parameters and gestational age was evaluated using Pearson correlation analysis for normally distributed variables and Spearman rank correlation for non-normal variables. Linear regression analyses were performed to model the relationship between ADC and gestational age, with assessment of fit and residual distribution. A two‑tailed P‑value < 0.05 was considered statistically significant.The detailed study design is presented in Fig. 2.

Fig. 2

:The technical flowchart of this study

Results

Characteristics of Study Population and Data Distribution

A total of 313 fetuses with normal postnatal urinary outcomes were included in this study. The distribution of cases across gestational age (GA) groups is summarized in Tables 2 and 3. Maternal age ranged from 20 to 44 years (median: 28.7 years). Shapiro–Wilk testing showed that the morphological parameters—anteroposterior diameter (AD), transverse diameter (TD), longitudinal diameter (LD), and mean renal parenchymal thickness (MRPT)—followed a normal distribution (P > 0.05), whereas the apparent diffusion coefficient (ADC) and T2 relative signal intensity (RSI-T2) values showed non-normal distribution patterns (P < 0.05).

Measurement Reliability

High measurement reproducibility was demonstrated across all renal parameters. For morphological measures (AD, TD, LD, MRPT), both intra- and inter-observer ICCs exceeded 0.90, indicating excellent reliability. For functional measures, the inter-observer ICCs were 0.89 for ADC and 0.85 for RSI-T2, while the intra-observer ICCs were 0.92 and 0.88, respectively.

Establishment of Normal Reference Ranges

Reference ranges stratified by gestational week were generated in accordance with data distribution characteristics.Functional parameters: ADC and RSI-T2 values were expressed using percentile-based reference intervals (P2.5-P97.5) due to non-normal distribution (Table 2).Morphological parameters: AD, TD, LD, and MRPT values were normally distributed and therefore expressed as mean ± 1.96 SD (Table 3).Together, these ranges provide a comprehensive normative dataset for fetal renal morphology and function during the second and third trimesters.

Gestational week	number	Right renal		Left renal
Gestational week	number	ADC (×10⁻³ mm²/s)	RSI-T2	ADC (×10⁻³ mm²/s)	RSI-T2
23	12	2.32–2.40	1.62–1.96	2.26–2.38	1.48–1.94
24	24	1.75–1.99	1.58–1.75	1.75–2.08	1.54–1.72
25	12	1.80–1.88	1.45–1.76	1.76–1.81	1.43–1.69
26	21	1.83–1.98	1.52–1.69	1.91–2.04	1.52–1.73
27	12	1.71–1.93	1.63–1.83	1.76-2.00	1.63–1.84
28	17	1.61–2.07	1.58–1.84	1.60–2.12	1.62–1.93
29	12	1.66–2.17	1.49–1.63	1.73–2.20	1.46–1.63
30	14	1.80–2.02	1.55–1.75	1.60–1.97	1.58–1.87
31	39	1.82–2.13	1.63–1.78	1.75–2.08	1.64–1.85
32	45	1.56–1.80	1.69–1.85	1.51–1.68	1.69–1.89
33	37	1.46–1.70	1.63–1.81	1.46–1.74	1.64–1.86
34	29	1.36–1.60	1.59–1.78	1.31–1.52	1.64–1.86
35	11	1.34–1.62	1.55–1.76	1.25–1.54	1.66–1.91
36	16	1.24–1.42	1.67–1.81	1.19–1.33	1.69–1.92
37	6	1.13–1.73	1.69–2.22	1.09–1.63	1.57–2.33
38	6	1.11–1.45	1.79–2.30	1.06–1.46	1.69–2.22

Gestational week	number	Right renal				Left renal
Gestational week	number	LD (cm)	TD (cm)	AD (cm)	MRPT (cm)	LD (cm)	TD (cm)	AD (cm)	MRPT (cm)
23	12	2.01–2.15	1.33–1.44	1.34–1.39	0.53–0.56	2.00-2.09	1.26–1.31	1.27–1.33	0.53–0.58
24	24	2.16–2.37	1.34–1.45	1.35–1.45	0.57–0.60	2.12–2.28	1.35–1.47	1.38–1.48	0.55–0.58
25	12	2.42–2.56	1.422–1.53	1.44–1.53	0.62–0.64	2.31–2.42	1.34–1.39	1.35–1.40	0.56–0.62
26	21	2.69–2.84	1.63–1.72	1.66–1.73	0.62–0.67	2.57–2.74	1.59–1.70	1.59–1.71	0.59–0.62
27	12	2.72–2.84	1.64–1.85	1.58–1.80	0.61–0.72	2.67–2.87	1.68–1.83	1.62–1.81	0.61–0.66
28	17	2.81-3.00	1.73–1.92	1.81–2.01	0.68–0.78	2.77–3.03	1.67–1.90	1.77–2.01	0.61–0.67
29	12	2.70–3.09	1.74–1.89	1.80–1.99	0.69–0.76	2.79–3.14	1.73–1.88	1.85–1.99	0.64–0.77
30	14	3.30–3.39	1.79–1.91	1.76–1.97	0.71–0.76	3.24–3.35	1.85–1.94	1.83–2.02	0.67–0.75
31	39	3.12–3.31	1.81–1.96	1.86–1.99	0.73–0.78	3.08–3.25	1.80–1.93	1.74–1.93	0.75–0.81
32	45	3.29–3.45	1.80–1.94	1.97–2.07	0.71–0.77	3.20–3.37	1.85–1.97	1.93–2.03	0.73–0.78
33	37	3.32–3.52	1.97–2.14	2.02–2.16	0.75–0.81	3.43–3.60	1.91–2.06	1.95–2.08	0.74–0.81
34	29	3.50–3.72	2.11–2.30	2.08–2.24	0.76–0.82	3.45–3.70	2.11–2.25	2.10–2.26	0.78–0.82
35	11	3.44–3.77	2.10–2.29	2.05–2.31	0.78–0.84	3.68–3.98	2.01–2.22	2.07–2.24	0.82–0.97
36	16	3.73–3.88	2.28–2.51	2.19–2.47	0.79–0.84	3.74–3.93	2.16–2.37	2.14–2.44	0.80–0.91
37	6	3.79–4.25	2.14–2.54	2.33–2.50	0.78–0.85	3.82–4.29	2.23–2.71	2.11–2.48	0.74–0.87
38	6	4.04–4.35	2.24–2.66	2.17–2.57	0.82–0.90	4.00-4.26	2.17–2.55	2.19–2.50	0.82–0.95

Correlation Between Renal Parameters and Gestational Age

Spearman correlation analysis demonstrated a moderate negative correlation between ADC and gestational age for both kidneys (right: r = − 0.46, P < 0.0001; left: r = − 0.52, P < 0.0001). RSI-T2 values showed a very weak to weak positive correlation with gestational age (right: r = 0.148; left: r = 0.200; both P < 0.0001). In contrast, Pearson correlation analysis revealed strong positive correlations between all morphological indicators and gestational age (all P < 0.0001):LD: r = 0.88 (right), r = 0.89 (left);TD: r = 0.78 (right), r = 0.80 (left);AD: r = 0.81 (right), r = 0.78 (left);MRPT: r = 0.72 (right), r = 0.74 (left).Scatter plots illustrating these relationships are shown in Fig. 3 and Fig. 4.

Fig. 3

Scatterplots with fitted regression lines showing the relationships between gestational age and renal morphological parameters. Panels (a–c) show the anteroposterior, transverse, and longitudinal diameters of the right kidney, and panels (d–f) show the corresponding parameters of the left kidney.

Fig. 4

Scatterplots with fitted regression lines showing the relationships between gestational age and functional MRI parameters of the fetal kidneys. Panels (a–c) show mean renal parenchymal thickness (MRPT), T2 relative signal intensity (RSI-T2), and apparent diffusion coefficient (ADC) of the right kidney, and panels (d–f) show the corresponding parameters of the left kidney.

Regression Analysis

Given the negative correlation between ADC and gestational age as well as the positive correlation between MRPT and gestational age, linear regression models were constructed to characterize ADC and MRPT developmental trajectories.

Right kidney:ADC (×10⁻³ mm²/s) = 3.23 − 0.049 × GA (weeks)(R² = 0.218, P < 0.0001)

Right kidney:MRPT(cm) = 0.026× GA (weeks)-0.037(R² = 0.518, P < 0.0001)

Left kidney:ADC (×10⁻³ mm²/s) = 3.46 − 0.058 × GA (weeks)(R² = 0.273, P < 0.0001)

Left kidney:MRPT(cm) = 0.025× GA (weeks)-0.027(R² = 0.548, P < 0.0001)

These models quantify the progressive decreases in ADC values and thickening of MRPT with advancing gestational age, establish predictive equations for clinical use.

Discussion

In this study, we established comprehensive multiparametric MRI reference ranges for normal fetal kidneys during the second and third trimesters, integrating both morphological and functional indicators. Our findings demonstrate that renal morphological parameters—including LD, TD, AD, and MRPT—show strong positive correlations with gestational age, whereas ADC values exhibit a moderate but significant decline with advancing gestation. Together, these results not only reflect the coordinated growth and maturation of fetal renal structures but also highlight the complementary value of combining morphologic and diffusion-based functional markers in evaluating fetal renal development.

Physiological Interpretation of Increasing Renal Parenchymal Thickness with Gestation

Our results show a steady increase in MRPT from 23 to 38 weeks of gestation, with a strong correlation with GA (r > 0.72). This pattern is in line with the established trajectory of renal development. After approximately 20 weeks, nephrogenesis gradually transitions from formation of new nephrons to hypertrophic growth of existing glomeruli and tubules ^{[9, 12]}. Although nephron number becomes largely fixed by 34–36 weeks, tubular length, branching complexity, interstitial tissue volume, and vascular development continue to increase ^[16]. These microstructural processes manifest as macroscopic thickening of the renal parenchyma, supporting MRPT as a reliable morphological indicator of renal maturation.

Clinically, deviations from the gestational-age-specific MRPT reference range may serve as early warning signs of renal pathology. Reduced parenchymal thickness may indicate renal hypoplasia or congenital parenchymal disease, whereas compensatory hypertrophy secondary to obstructive uropathy or hereditary nephropathies may present as increased MRPT^{[10, 13]}. Thus, MRPT provides a readily interpretable morphological marker with high clinical relevance in prenatal diagnostics .

Mechanisms Underlying the Decline in ADC Values With Advancing Gestation

A notable finding of this study is the progressive decrease in renal ADC values with increasing gestational age, consistent with previous observations^{[7, 8, 19]}. This trend can be attributed to several physiological mechanisms:①Increasing cellular density and structural complexity:As nephrons proliferate and tubular structures elongate and thicken, the extracellular diffusion space becomes progressively restricted. This microstructural “densification” reduces the free movement of water molecules, directly contributing to lower ADC values^{[8, 15]}.②Maturation of tubular transport function:During late gestation, the renal tubular epithelium undergoes functional maturation, leading to increasing reabsorption of water and solutes and the establishment of the corticomedullary osmotic gradient. Consequently, water molecules are increasingly compartmentalized within tubular and interstitial spaces, further restricting diffusivity^[17].③Changes in renal perfusion contribution:Although absolute renal blood flow increases with gestation, its proportion of fetal cardiac output remains comparatively low (2%–4%), substantially less than in neonates and adults. Thus, perfusion-related pseudodiffusion contributes minimally to the overall ADC signal during fetal life, reinforcing the dominant effect of structural restriction^[18].

The stronger negative correlation observed in the left kidney compared with the right may reflect subtle anatomical or physiological differences, though further investigation is warranted to clarify this asymmetry.

Integrated Diagnostic Value of Morphological and Functional MRI Parameters

The combined analysis of structural and functional MRI parameters provides a more comprehensive assessment of fetal renal development. Morphological parameters, which increase linearly with gestational age, reflect macroscopic organ growth. In contrast, the decrease in ADC values captures microstructural maturation and functional development. The distinct but complementary patterns of change in these parameters underscore a morphology–function dissociation that may enhance diagnostic precision.For example:Early renal hypoplasia may present as reduced MRPT with abnormally elevated ADC, indicating impaired parenchymal development and increased diffusivity.Early obstructive nephropathy may initially exhibit decreased ADC values, reflecting cytotoxic edema or early microstructural alterations, before morphological enlargement becomes apparent.Thus, integrating MRPT and ADC values may enable earlier and more accurate identification of subtle renal abnormalities compared with using either metric alone.

Study Limitations

Several limitations should be acknowledged. First, although the total cohort size was relatively large, certain late-gestation strata (≥ 37 weeks) contained fewer cases, which may slightly limit the robustness of reference ranges for these gestational ages. Second, the study was conducted at a single tertiary center, introducing potential selection bias and limiting generalizability to broader populations. Third, although measurement reproducibility was high, ADC values remain inherently sensitive to factors such as ROI placement, fetal motion, and sequence-specific technical parameters. Despite standardized protocols and repeatability assessments, residual variability is unavoidable. Future multicenter and prospective studies are needed to validate these findings across different MRI platforms and populations.

Conclusions

This study established exploratory gestational age–specific reference ranges for key morphological and functional MRI parameters of normal fetal kidneys. Renal size and parenchymal thickness increase steadily with gestation, reflecting macroscopic organ growth and providing robust quantitative markers for assessing structural development, whereas ADC values decline as a result of microstructural and functional maturation. Together, these markers offer a robust quantitative framework for evaluating fetal renal development. Their combined application may substantially enhance the prenatal detection, characterization, and prognostic assessment of fetal renal anomalies. Future multicenter studies are required to further validate these reference intervals and further explore their diagnostic utility in fetal renal disorders.

List of abbreviations

ADC

apparent diffusion coefficient

DWI

diffusion-weighted imaging

gestational age

ICC

intraclass correlation coefficient

MRI

magnetic resonance imaging

MRPT

mean renal parenchymal thickness

ROI

region of interest

RSI-T2

T2 relative signal intensity

T2WI

T2-weighted imaging

Declarations

Ethics approval and consent to participate

This retrospective observational study was conducted at Sichuan Provincial Maternity and Child Health Care Hospital and was approved by the Medical Ethics Review Committee of Sichuan Provincial Maternity and Child Health Care Hospital (Approval No.

20240419-076).All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments.

Written informed consent to participate was obtained from all pregnant women prior to fetal MRI examination.

Consent for publication

Written informed consent for publication of anonymized clinical data and imaging was obtained from all participants and/or their legal guardians.

The publication of anonymized data derived from this study was approved by the Medical Ethics Review Committee of Sichuan Provincial Maternity and Child Health Care Hospital (Approval No. 20240419-076).

Data Availability

The datasets that support the findings of this study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

The authors received no specific funding for this work.

Author Contribution

YMP and MK conceived and designed the study and supervised the overall project. YMP, QYW, RL, and XJZ performed case selection, image review, data collection, and image and statistical analysis. SZM, as the radiologic technologist, conducted and coordinated the fetal MRI examinations and ensured image quality. YCL, as a research scientist from GE Healthcare, provided technical support for MRI sequence optimization and quantitative parameter implementation. YMP drafted the manuscript. All authors critically revised the manuscript for important intellectual content, approved the final version, and agreed to be accountable for all aspects of the work.

Acknowledgement

The authors would like to express their sincere gratitude to all patients and their families for their willingness to participate in this study and for their cooperation throughout the research period.

The authors also thank the leadership and colleagues of the Department of Radiology, Sichuan Provincial Maternity and Child Health Care Hospital, for their continuous support.

The approval and oversight provided by the Medical Ethics Committee of Sichuan Provincial Maternity and Child Health Care Hospital are gratefully acknowledged.

Authors’information

Not applicable.

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Yes