Automated intertumoral susceptibility signal extraction combined with quantitative enhanced T₂*-weighted angiography sequence parameters: a promising approach for evaluating HIF-1α expression in endometrial cancer

Introduction

Endometrial cancer (EC), a malignant neoplasm originating from the uterine endometrium, represents the second most frequent gynecologic malignancy in China and ranks as the most common female reproductive tract cancer in developed nations (1-3). The incidence of EC has been steadily increasing. Clinical prognosis is significantly associated with multiple clinicopathological factors, including age at diagnosis, tumor stage, histological grade, and pathological subtype. Notably, elderly patients presenting with advanced-stage disease and poorly differentiated tumors typically demonstrate worse clinical outcomes (4,5). The cornerstone of EC remains surgical intervention, complemented by adjuvant therapies including radiotherapy, chemotherapy, and hormonal treatment (6). Therapeutic decision-making should incorporate comprehensive consideration of patient age, histopathological characteristics, molecular profiling, and International Federation of Gynecology and Obstetrics (FIGO) staging. For early-stage (I–II) EC without high-risk features, total hysterectomy with bilateral salpingo-oophorectomy represents the standard approach. Cases exhibiting high-risk factors such as extrauterine extension or lymph node metastasis (LNM) typically necessitate multimodal therapy combining radical surgery with adjuvant chemoradiation. Advanced-stage (III–IV) disease with documented extrauterine invasion generally requires radiotherapy as a critical component of treatment, though therapeutic responses may demonstrate significant interpatient variability (6). The tumor’s hypoxic microenvironment, linked to hypoxia-inducible factor-1α (HIF-1α), is a key factor influencing the effectiveness of radiotherapy (7,8).

HIF-1α, a critical transcription factor, plays a pivotal role in modulating gene expression in response to hypoxic conditions (9). Research (10-12) has demonstrated a direct correlation between the oxygenation levels of tumors and the expression of HIF-1α. To be specific, HIF-1α is rapidly degraded under normoxic circumstances, while in hypoxic settings, this degradation process is suppressed, causing it to accumulate in the nucleus. The accumulation of HIF-1α in the nucleus can serve as a significant indicator of tumor hypoxia, invasiveness, and resistance to radiation therapy (13). Meanwhile, HIF-1α plays a role in tumorigenesis, metastasis, and epithelial-mesenchymal transformation (EMT) through the regulation of glucose uptake, energy metabolism, angiogenesis, erythropoiesis, cell proliferation and apoptosis, as well as cell-cell and cell-matrix interactions to modulate cellular functions under hypoxic conditions (9,14). Conversely, the upregulation of HIF-1α significantly influences molecular signaling pathways both downstream and upstream (15), ultimately modulating the expression of hypoxia-related genes, which contributes to compromised arterial blood supply, diminished vascular density, impaired vascular tissue transport, alterations in red blood cell flow, functional shunting, and an imbalance between oxygen supply and demand. In EC, high HIF-1α expression correlates with advanced FIGO stage (≥ III), lymphovascular invasion, and reduced 5-year survival (16). It also promotes metastasis via vascular endothelial growth factor (VEGF) upregulation—a key mechanism for targeted therapy. Furthermore, elevated HIF-1α expression serves as a biomarker for tumors demonstrating resistance to conventional chemoradiation while exhibiting susceptibility to targeted therapeutic approaches: (I) anti-angiogenic agents—preclinical studies reveal synergistic activity of bevacizumab specifically in HIF-1α-overexpressing subsets; (II) immunotherapy—through HIF-1α-mediated upregulation of programmed death-ligand 1 (PD-L1) expression, suggesting enhanced responsiveness to immune checkpoint inhibitors in these tumor populations.

The traditional approach to assessing HIF-1α expression primarily involved the use of immunohistochemistry (IHC) on surgically obtained or biopsy-derived pathological tissues (17). However, this method is constrained by sample size limitations, an inability to accurately capture the heterogeneous nature of the entire tumor, and its invasive and time-intensive nature. Furthermore, while genomic analysis technology has been utilized for detecting HIF-1α expression, its widespread implementation in clinical settings is hindered by cost constraints, lengthy detection cycles, and technical intricacies. Various imaging techniques can be utilized to evaluate tumor hypoxia, either directly or indirectly, in a non-invasive manner. Earlier techniques for assessing tumor hypoxia comprised direct approaches, such as employing oxygen sensing probes (18) and utilizing phosphorescence lifetime imaging to ascertain oxygen pressure (PO₂) (19), along with indirect approaches including oxygen-enhanced magnetic resonance imaging (OE-MRI) (20), magnetic susceptibility sequences (21), and positron emission tomography (PET) (22), which are used to deduce tumor hypoxia. Simultaneously, there exist studies that have identified an initial correlation between the quantitative parameters of sequences, including dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) (23,24), diffusion-weighted imaging (DWI), and intravoxel incoherent motion (IVIM) (25), and hypoxia within the tumor. The enhanced T₂*-weighted angiography (ESWAN) sequence, derived from susceptibility-weighted imaging (SWI) and incorporating magnetic susceptibility difference and oxygen level-dependent effect imaging techniques, allows for the acquisition of quantitative parameters such as phase values and R₂* values following post-processing (26,27). These values enable the non-invasive assessment of oxygenation and local metabolic status in hypoxic tumor regions. This approach enables a more comprehensive and quantitative evaluation of tumor hypoxia compared to alternative magnetic susceptibility sequences.

The Intertumoral susceptibility signal (ITSS) is a low-signal area on the phasor map, characterized by continuous dots or thin lines within the tumor, primarily attributed to microhemorrhages and neovascularization (28). This feature serves as a non-invasive and intuitive imaging marker for assessing vascular proliferation within pathological tissues, reflecting the density and size of micro-vessels present in the lesion (29). Presently, the predominant assessments of ITSS primarily rely on semiquantitative methods (30,31), with some studies incorporating quantitative measures (32). Nonetheless, these approaches are constrained by several limitations: (I) susceptibility to the subjective interpretation of the assessor and inadequate reproducibility, resulting in inconsistent measurement outcomes; (II) focus on the head as the study subject, which experiences minimal interference from respiration and motion artifacts, necessitating further investigation into the applicability and reliability of these methods for abdominal organs; (III) failure to address phase diagram artifacts, potentially leading to inaccuracies in the results.

In order to overcome the constraints associated with existing methodologies, the current study utilized the ESWAN sequence for pre-processing phase map artifacts, particularly addressing the challenges posed by respiratory and motion-related artifacts in abdominal organs. Subsequently, the study employed an automated approach to extract the ITSS ratios of patients with EC, based on the ratio of low-signal region pixels within the tumor to the total number of pixels in the tumor. This method is characterized by its simplicity, reproducibility, and reduced subjectivity, rendering it highly suitable for clinical applications. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-514/rc).

Methods

Patients

This retrospective study was approved by the medical ethics committee of the First Affiliated Hospital of Dalian Medical University (Approval No. PJ-KS-KY-2023-265), and individual consent for this retrospective analysis was waived. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. We retrospectively reviewed the clinical and imaging data of 276 patients with suspected uterine pathology who underwent 1.5-T MRI between January 2012 and August 2019 at the First Affiliated Hospital of Dalian Medical University and were later diagnosed with EC. The study’s inclusion criteria consisted of patients with histologically confirmed EC following surgical resection, MRI scans incorporating T₂-weighted imaging (T₂WI), DWI, and ESWAN sequences, high-quality MRI images with clear lesion visualization and absence of artifacts, and ease of tumor boundary identification for region of interest (ROI) delineation. Additionally, included patients had solitary tumors without concurrent uterine tumors or endometrial hyperplasia. Patients were excluded from the study for the following reasons: (I) prior receipt of alternative treatments for EC, such as radiotherapy, chemotherapy, and immunotherapy before undergoing MRI (n=12); (II) incomplete scanning sequence or absence of an ESWAN sequence (n=1); (III) poor quality MRI images displaying lesions inadequately or tumors measuring less than 1 cm with ROI outlines containing less than 3 layers (n=34); (IV) retrospective analysis of wax blocks revealing unclear depiction of lesions within the sections and absence of HIF-1α expression (n=10).

A total of 219 patients were ultimately enrolled in the study and stratified into two cohorts based on their levels of HIF-1α expression: 86 individuals in the high expression group and 133 individuals in the low expression group. The demographic and clinicopathological characteristics of the two groups were gathered from the hospital information system (HIS) and included variables such as age, FIGO stage, differentiation grade, menopausal status, pathology type, irregular vaginal bleeding, deep muscle invasion (DMI), lymphatic vascular space invasion (LVSI), LNM, carcinoembryonic antigen (CEA), alpha fetoprotein (AFP), carbohydrate antigen 12-5 (CA12-5), and CA19-9.

MRI protocol

All patients who were enrolled in the study underwent 1.5-T MRI scanning using the GE 1.5-T Signa HDXT MR machine (GE Healthcare, Waukesha, WI USA) within a 2-week timeframe prior to the procedure. Birth control rings were removed one day before the examination, and dietary abstinence was enforced for 4–6 hours prior to reduce gastrointestinal peristaltic artefacts. The bladder was emptied as needed, and patients were instructed on proper breathing techniques to minimize respiratory movement artefacts that could impact image quality. Patients were positioned in the supine position with their foot advanced for the duration of the examination. The study utilized an 8-channel phased array body coil for imaging, with scanning sequences consisting of T₁-weighted imaging (T₁WI), T₂WI, DWI, and ESWAN sequences. Apparent diffusion coefficient (ADC) maps were obtained from DWI post-processing. The specific scanning parameters can be found in Table 1.

HIF-1α assay

Paraffin blocks containing EC tissue were obtained from the pathology department of our hospital following surgical resection. Subsequently, 4-μm sections were prepared by a highly experienced pathology microtome technician specializing in pathological wax sections, and stored in a controlled environment. Immunohistochemical experiments targeting HIF-1α were conducted by postgraduate students in the pathology laboratory using a two-step method for staining visualization. The specific staining procedures utilized in this study encompassed baking, dewaxing, antigen retrieval, blocking endogenous peroxidase, primary and secondary antibody incubation, color development with diaminobenzidine (DAB) working solution, re-staining, and dehydration sealing. Two pathologists, one with 2 years of experience and the other with 4 years of experience, independently assessed the IHC staining results without access to clinical or imaging data. In cases of disagreement between the two pathologists, a consensus was reached through discussion with a third pathologist possessing 10 years of experience. HIF-1α was predominantly localized in the nucleus, and the sections were examined using a high-powered microscope with three randomly selected fields of view for each tissue section. Subsequently, the expression level was comprehensively assessed by considering the percentage of positive cells and the intensity of staining: The total positivity scores ranged from 0 to 4, representing varying percentages of positivity. Staining intensity scores ranged from 0 to 3, indicating different levels of intensity. The high-expression group was characterized by the presence of more than 50% HIF-1α-positive cells with a staining intensity score of 2 or higher, while the low-expression group was defined by criteria that did not meet these thresholds.

Measurement of ITSS ratios

The phase maps were generated through post-processing of ESWAN sequences using Functol software on a GE AW4.6 workstation (GE Healthcare, Waukesha, WI USA). Subsequently, an image de-artifacting program developed in Python was utilized to remove artifacts from the phase maps (as shown in Figure 1). In this study, we employed AnatomySketch (AS), an open-source software framework developed by our collaborators, for medical image analysis. Its core design facilitates essential tasks such as visualization, processing, and segmentation through a suite of intuitive interactive tools. These tools enable rapid annotation (e.g., scribbles, contours, landmarks, and bounding boxes) and subsequent refinement via direct manipulation of three-dimensional surfaces. Critically, AS software is built upon a modular, plugin-based architecture, ensuring functional extensibility.

Figure 1 Python programming de-artifacting workflow. (A) Input a phase map requiring artifact removal, containing a band artifact characterized by a band of dark pixels juxtaposed with a band of bright pixels; pixels exhibiting these characteristics necessitate elimination. (B) The A-map undergoes median filtering to produce a smoothed B-map. (C) By subtracting the values of matrix A from matrix B, pixels in the resulting matrix that fall below −150 are classified as having insufficient signal, while pixels exceeding 200 are deemed to have excessive signal. A new 3D array, denoted as C-map, is generated by assigning a value of −1 to pixels with insufficient signal, 1 to pixels with excessive signal, and 0 to all other pixels. (D) The process involves extracting the region surrounding the values of 1 and −1 in the C-map, expanding the resulting area by 1 pixel in the cross-section, and generating a D-map. Pixels within this region are designated as pseudo-imaging pixels. (E) The process involves recalculating the pixel values of the artifactual region in the E map by determining the average of the 26 neighboring non-artifactual region pixels for each target pixel, as a replacement for the original artifactual region pixel values. (F) Substituting the pixel values of the corresponding pixels in matrix A with those of matrix E in order to generate the resultant map.

The de-artifacted phase maps were then imported into AS software for the calculation of ITSS ratios. Two physicians, one with 3 years and the other with 8 years of experience in diagnostic uterine MRI imaging, utilized a double-blind method to identify tumor lesions on T₂WI images. They then referenced the DWI and ADC maps to calculate the ITSS ratios of the largest tumor level. The ITSS ratios were delineated on phase maps by outlining ROIs from the edges of the patient’s EC lesion, including the first, last, and two layers above. Subsequently, the AS software automatically computed the ITSS ratios of the level of maximum tumor ITSS content (as shown in Figure 2).

Figure 2 A schematic diagram of the AS software was utilized to calculate the tumor ITSS ratio. By employing the interpolation and labeling tools within the AS software, the ITSS ratio within the ROI was determined. The ITSS ratio is operationally defined as the ratio of pixels exhibiting low signal intensity within the ROI to the total number of pixels present within the ROI. AS, AnatomySketch; ITSS, intertumoral susceptibility signal; ROI, region of interest.

Measurement of quantitative parameters of the ESWAN sequence

The ESWAN imaging post-processing was conducted using the GE AW4.6 workstation with Functol software to generate magnitude, phase, and R₂* maps. T₂WI and DWI sequences were utilized as a reference to identify the largest tumor level on the post-processed ESWAN images by two blinded physicians who calculated the ITSS ratios. Subsequently, the ROIs were delineated on the tumor using a freehand drawing tool to encompass the solid tumor area to the fullest extent possible in tumor maximal level. The ROIs were delineated in order to circumvent regions of necrosis, hemorrhage, cystic degeneration, and to mitigate partial volume effects at the periphery of the tumor. Subsequently, the delineated ROIs are automatically transferred to the functional parameter map, where the mean value of each parameter is documented for subsequent analysis (as shown in Figures 3,4).

Figure 3 A 52-year-old female patient diagnosed with EC and exhibiting low HIF-1α expression. (A) Axial T₂WI image: a slightly high signal mass in the uterine cavity with a full-cavity pattern. (B) Axial DWI image: a mass in the uterine cavity with restricted diffusion and a slightly high signal pattern. (C) ADC map: a low signal pattern in the uterine cavity. (D) The schematic diagram illustrates the ITSS ratio measured within the tumor using AS software. The green area on the diagram signifies the ITSS within the tumor, displaying an ITSS ratio of 0.349. (E-G) Magnitude, phase and R₂* maps of the quantitative parameters of the ESWAN sequence, respectively, where the mean values of the magnitude, phase and R₂* values for this patient are 599.37, −0.043 arc, and 51.513 Hz. (H) Immunohistochemical staining for HIF-1α: less than 50% of HIF-1α-positive cells with a staining intensity of <2 points were defined as low expression. The arrow in the image indicates the location of the tumor lesion. ADC, apparent diffusion coefficient; AS, AnatomySketch; EC, endometrial cancer; DWI, diffusion-weighted imaging; HIF-1α, hypoxia-inducible factor-1α; ITSS, intertumoral susceptibility signal; T₂WI, T₂-weighted imaging.

Figure 4 A 70-year-old female patient diagnosed with EC and exhibiting high HIF-1α expression. (A) Axial T₂WI image: a slightly high signal mass in the uterine cavity with a full-cavity pattern. (B) Axial DWI image: a mass in the uterine cavity with restricted diffusion and a slightly high signal pattern. (C) ADC map: a low signal pattern in the uterine cavity. (D) The schematic diagram illustrates the ITSS ratio measured within the tumor using AS software. The green area on the diagram signifies the ITSS within the tumor, displaying an ITSS ratio of 0.217. (E-G) Magnitude, phase and R₂* maps of the quantitative parameters of the ESWAN sequence, respectively, where the mean values of the magnitude, phase and R₂* values for this patient are 948.615, 0.031 arc, and 18.809 Hz. (H) Immunohistochemical staining for HIF-1α: more than 50% of HIF-1α-positive cells with a staining intensity of >2 points were defined as high expression. The arrow in the image indicates the location of the tumor lesion. ADC, apparent diffusion coefficient; AS, AnatomySketch; EC, endometrial cancer; DWI, diffusion-weighted imaging; ESWAN, enhanced T₂*-weighted angiography; HIF-1α, hypoxia-inducible factor-1α; ITSS, intertumoral susceptibility signal; T₂WI, T₂-weighted imaging.

Statistical analysis

Statistical analysis was conducted utilizing SPSS 21.0 software (Chicago, IL, USA), MedCalc 15.2.2 software (Med Calc Software, Ostend, Belgium), and GraphPad Prism 8 software. The intra-class correlation coefficients (ICC) were used to evaluate the consistency between the measurements taken by the two observers. The Shapiro-Wilks test was utilized to examine the normality of the measurements, and either the two independent samples t-test or Mann-Whitney U test was employed to compare quantitative parameters between the two patient groups. The clinicopathological data of the two patient groups were presented as frequencies or percentages, and group comparisons were conducted using the chi-square test or Fisher’s exact test. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the predictive capacity of statistically significant parameters and their combinations in predicting high HIF-1α expression in EC. Binary logistic regression was utilized to ascertain the predictive value of high HIF-1α expression status in EC when combined with independent risk factors. The area under the curve (AUC) was assessed using the DeLong test.

Results

Comparison between the general clinicopathological data of the two groups of patients

There were no statistically significant differences observed in the general clinicopathological characteristics, including age, FIGO stage, differentiation degree, menopausal status, pathological type, irregular vaginal bleeding, DMI, LVSI, LNM, CEA, AFP, CA12-5, and CA19-9, between the two groups of patients (P>0.05) as indicated in Table 2.

Consistency analysis of the measurements between the two observers

The inter-rater reliability of the ITSS ratios, magnitude values, phase values, and R₂* values assessed by the two observers was deemed satisfactory, with all ICC values exceeding 0.75, as evidenced in Table 3.

Comparison of the differences between the parameters in the two groups of patients

The ITSS ratio, phase value, and R₂* value of EC in the high HIF-1α expression group were significantly greater than those in the low expression group with a P value less than 0.05. However, the magnitude value of EC in the high HIF-1α expression group did not show a statistically significant difference compared to the low expression group with a P value greater than 0.05, as illustrated in Table 4 and Figure 5.

Figure 5 Histograms displaying the distribution of parameters within the high HIF-1α expression group and the low HIF-1α expression group. (A-D) Differential comparison of ITSS ratio, magnitude value, phase value and R₂* value between the two groups of cases. ***, P<0.001. HIF-1α, hypoxia-inducible factor-1α; ITSS, intertumoral susceptibility signal; ns, not significant.

Independent predictors of high HIF-1α expression in EC predicted by binary logistic regression analysis

Drawing on integrated clinicopathological data and a range of quantitative parameters with P values less than 0.1 in intergroup comparisons, multiple linear regression analysis was performed to evaluate covariance interference. The variance inflation factor (VIF) of each parameter was found to be less than 10, thus ruling out any covariance interference. Following univariate and multivariate logistic regression analyses, the ITSS ratio, phase value, and R₂* value emerged as independent predictors for assessing the high expression of HIF-1α in EC (as shown in Table 5).

ITSS ratio, multiple quantitative parameters and combined model to assess the efficacy of high EC HIF-1α expression

The AUC values for the ITSS ratio, phase value, R₂* value, phase value + R₂* value, and the combined model in evaluating the high HIF-1α expression were 0.705, 0.672, 0.745, 0.765, and 0.828, respectively. DeLong’s test indicated that the diagnostic efficacy of the combined model was superior to that of each individual parameter (as shown in the Table 6 and Figure 6).

Figure 6 ROC curves analyzing the efficacy of ITSS ratio, phase value, R₂* value, phase value + R₂* value (ESWAN) and the combined parameter to assess the high expression of HIF-1α in EC (AUC values of 0.705, 0.672, 0.745, 0.765, and 0.828, respectively). AUC, area under the curve; EC, endometrial cancer; ESWAN, enhanced T₂*-weighted angiography; HIF-1α, hypoxia-inducible factor-1α; ITSS, intertumoral susceptibility signal; ROC, receiver operating characteristic.

Discussion

The primary discovery of this study was the ability of the ITSS ratio and ESWAN sequence quantitative parameters to evaluate the level of HIF-1α expression in EC. Our research revealed that the ITSS ratio, phase value, and R₂* value were notably elevated in groups with high HIF-1α expression compared to those with low expression. Furthermore, after controlling for confounding variables, the ITSS ratio, phase value, and R₂* value emerged as independent risk factors for predicting HIF-1α expression in EC. The combined model demonstrated a high diagnostic efficacy in distinguishing HIF-1α expression in EC, with significant differences compared to single parameter models.

HIF-1α serves as a crucial oxygen-dependent regulator in the context of tumor hypoxia, facilitating the expression of genes associated with hypoxia, including angiogenesis, erythropoiesis, glycolysis, cell adhesion, and cell proliferation and apoptosis in vivo (14). This phenomenon likely mirrors the hypoxic microenvironment characteristic of tumors. Therapeutic agents specifically designed to target patients with elevated expression levels of genes associated with signaling pathways regulated by HIF-1α, such as VEGF, glucose transporter proteins, and anti-apoptotic proteins, are currently accessible. In EC, elevated expression of HIF-1α has been found to be significantly associated with various biological characteristics including clinical stage, differentiation degree, LNM, and DMI (33). Additionally, patients with EC exhibiting high clinical stage, low histological differentiation, LNM, cervical invasion, and distant organ metastasis may require tumor radiotherapy. The efficacy of tumor radiotherapy is influenced by the extent of tumor hypoxia, thus preoperative evaluation of EC HIF-1α expression levels can assist clinicians in devising treatment strategies and assessing outcomes.

HIF-1α has been proven to accumulate in various types of cancers, including rectal cancer, prostate cancer, cervical cancer, kidney cancer, etc. (34-36). Studies have confirmed that in EC, cells overexpressing HIF-1α exhibit poor prognosis and fail to respond effectively to treatment (16,36). Tumor hypoxia and alterations in cancer cell metabolism represent viable targets for selective anticancer therapies, and the inhibition of the activity of the transcription factor HIF-1 falls into this category of therapies (37). HIF-1α holds promise as a desirable target for cancer treatment due to its influence on critical aspects of cancer biology, coupled with its extremely low activity in normal tissues, which minimizes side effects on normal cells (38,39).

ITSS provides a comprehensive depiction of neovascularization and microhemorrhage within the tumor, serving as a noninvasive and intuitive imaging marker for demonstrating vascular proliferation within the tumor. In this research, ITSS ratios were automatically extracted at the level of maximum tumor ITSS content utilizing ESWAN sequences. The study revealed that the ITSS ratios were significantly higher in the high HIF-1α expression compared to the low-expression group. This observation was attributed to the activation of VEGFs by the high expression of HIF-1α (40). Furthermore, tumors with high HIF-1α expression exhibited neovascularization characterized by thin walls, high vascular permeability, and frequent microhemorrhages, contributing to the elevated ITSS rates.

The R₂* value obtained from the ESWAN sequence demonstrates a direct correlation with the concentration of paramagnetic substances, specifically deoxyhemoglobin, within tissues (41). This relationship serves as a sensitive indicator for assessing the local oxygen content within tumors. In this investigation, it was observed that the R₂* values of patients with EC in the high-expression group were significantly elevated compared to those in the low-expression group. This finding may be attributed to the presence of increased neovascularization and thinner vascular walls in tumors of the high HIF-1α expression group, leading to a propensity for hemorrhagic stasis, heightened oxygen consumption, and an accumulation of paramagnetic substances, such as deoxyhemoglobin and ferric hemoflavin (42). Furthermore, elevated levels of HIF-1α indicate more severe local hypoxia within the tumor, decreased blood oxygen content, and an accumulation in local paramagnetic substances such as deoxyhemoglobin and ferric hemoflavin. These factors may contribute to the higher R₂* values observed in patients with high expression of HIF-1α in EC. Furthermore, the phase values analyzed in this investigation revealed a diminished efficacy of EC HIF-1α high expression. This reduction was linked to the heightened expression of HIF-1α causing an accumulation of paramagnetic material within the tumor, resulting in a negative phase shift and subsequently lowering the phase values within the high expression group of HIF-1α.

In addition, ROC curve analysis indicated that the AUC value, sensitivity, and specificity of R₂* values surpassed those of ITSS ratios, likely attributed to the influence of both tumor cell proliferation and neovascularization on tissue oxygenation levels reflected by R₂* values. Despite this distinction, the diagnostic performances of the two methods did not exhibit significant disparities. Additionally, ITSS ratios offer the advantage of automated quantification, simplifying implementation and minimizing subjective bias compared to R₂* values.

This study conducted a multifactorial analysis to identify independent risk factors for predicting high expression of HIF-1α in EC, following the exclusion of confounding factors (such as pathologic type and LVSI). The analysis revealed that the ITSS ratio, phase value, and R₂* value were significant predictors. Furthermore, the combined model based on these independent risk factors demonstrated the highest efficacy in evaluating high expression of EC HIF-1α. These findings suggest that ITSS ratio and ESWAN sequence quantitative parameters provide valuable insights into the role of HIF-1α in the hypoxic tumor microenvironment. The ITSS ratio offers an indirect means of evaluating the expression level of HIF-1α expression in EC through its reflection of microhemorrhages and neovascularization in tumors. In contrast, the quantitative parameters derived from the ESWAN sequence can assess HIF-1α expression by detecting the localized accumulation of paramagnetic substances, such as deoxyhemoglobin, in tumors resulting from changes in oxygenation status. Integrating these two perspectives allows for a more comprehensive, efficient, and specific assessment of tumor hypoxia.

Limitation

This study exhibits several limitations. Firstly, the sample size is small, necessitating an increase for future research. Secondly, our research results are only applicable to 1.5-T systems. In future studies, we will conduct verification on 3-T and above systems, which will help expand its scope of application. Thirdly, the quantitative parameter measurements focused on the largest lesion level while excluding hemorrhage, necrosis, and cystic degeneration, potentially overlooking heterogeneity information within the entire tumor domain. In addition, our study subjects represent typical cases in clinical practice for EC. In future studies, multicenter validation will help improve the generalizability of the study results. Finally, the automatic extraction of ITSS failed to distinguish between tumor neovascularization and microhemorrhage, warranting further investigation.

Conclusions

In conclusion, the automated extraction of ITSS, combined with the quantitative parameters of the ESWAN sequence holds significant potential to enhance the accuracy of evaluating high levels of HIF-1α expression in EC. This novel approach offers a non-invasive and quantitative method for assessing EC HIF-1α expression in clinical settings, with promising prospects for future clinical applications.

Acknowledgments

We wish to thank the associate editor and the reviewers for their useful feedback that helped us improve this paper.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-514/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-514/dss

Funding: This study was supported by the Dalian Medical Science Research Program Project (No. 2023DF038).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-514/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This retrospective study was approved by the medical ethics committee of the First Affiliated Hospital of Dalian Medical University (Approval No. PJ-KS-KY-2023-265), and individual consent for this retrospective analysis was waived. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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