Abstract
Objective
To compare the application value of stepping angiography and traditional segmental angiography in lower limb anterograde venography.
Methods
A retrospective analysis was conducted among 95 patients who underwent lower limb anterograde venography at the Hefei Third People’s Hospital and the First Affiliated Hospital of Anhui University of Chinese Medicine from September 2021 to December 2024. Among them, 50 patients who underwent traditional segmental angiography were assigned to the control group, while 45 patients who underwent stepping angiography were assigned to the observation group. Comparative assessments were performed between the two groups regarding image quality, angiography time, absorbed radiation dose, contrast agent dosage, and incidence of complications.
Results
The image quality in the observation group was better than that in the control group. The average angiography time in the control group was 27.87 ± 4.98 min, while that in the observation group was 10.23 ± 2.88 min (P = 0.013). The average absorbed radiation dose in the control group was 4.65 ± 1.32 Gy, while that in the observation group was 3.53 ± 0.73 Gy (P = 0.008). The average contrast agent dosage in the control group was 69.42 ± 10.42 mL, while that in the observation group was 47.51 ± 8.14 mL (P = 0.011). Two complications occurred in the control group, while three occurred in the observation group (P = 0.339).
Conclusion
For lower limb venous lesions, stepping angiography is superior to traditional segmental angiography in terms of overall image quality and practicality. Stepping angiography is a simpler and quicker process, and only a small dose of radiation is absorbed by both doctors and patients; moreover, it requires a lower dosage of contrast agent. It plays an important objective guiding role in the decision-making of treatment plans for lower limb venous diseases.
Keywords
Introduction
Chronic venous disease (CVD) is one of the most common vascular diseases, mainly occurring in the lower limbs, with an incidence of 20%–50%.1,2 Patients with CVD may experience lower limb swelling, skin changes, and even venous ulcers. 3 Lower limb venography is the gold standard for diagnosing most lower limb venous diseases as it can directly reflect the morphology, lesion or obstruction sites of the lower limb veins, and the condition of valve reflux.4,5 Currently, traditional segmental lower limb anterograde venography, the most commonly used diagnostic technique, often fails to clearly display venous lesions, with low diagnostic accuracy for pelvic venous segmental lesions. 6 In recent years, with continuous advancements in medical digital equipment and expansion of examination techniques, stepping angiography has been widely applied in magnetic resonance.7–9 However, there are only a few reports on the application of stepping angiography in digital subtraction angiography (DSA) lower limb venography. This study aimed to use stepping angiography for DSA lower limb anterograde venography and compare the application value of stepping angiography and traditional segmental angiography in lower limb anterograde venography to better guide the clinical diagnosis and treatment of CVD.
Materials and methods
Patients
Patients who underwent lower limb anterograde venography at the Hefei Third People’s Hospital and the First Affiliated Hospital of Anhui University of Chinese Medicine from September 2021 to December 2024 and met the inclusion criteria were enrolled. The inclusion criteria were as follows: (a) lower limb anterograde venography via the dorsalis pedis vein; (b) lesions in a single limb; and (c) consent to participate in this study. In total, 95 patients undergoing lower limb anterograde venography were included in this study. Among them, 50 patients undergoing traditional segmental angiography were assigned to the control group, and 45 patients undergoing stepping angiography were assigned to the observation group. There was no significant difference in the age; sex; angiography reasons; complications; and clinical, etiology, anatomy, pathophysiology (CEAP) classification between the two groups (P > 0.05). A comparison of the general characteristics of the two groups is shown in Table 1. A flowchart of the study is shown in Figure 1. This study was approved by the hospital’s medical ethics committee (Ethical Approval Number: 2025LLWL014), and all patients provided written informed consent. This study was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2024. We have de-identified all patient details. The reporting of this study conforms to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. 10
Comparison of the general characteristics of patients (mean ± SD, n (%)).
CEAP: clinical, etiology, anatomy, pathophysiology.
Research flowchart.
Equipment
The main equipment used was the DSA system, with models GE Innova3100 and SIEMENS Artis Q ceiling (the use of GE and SIEMENS DSA follows a random principle). The contrast agent was iodixanol (Nanjing Zhengda Tianqing, approval number: H20183201).
Examination methods
Traditional segmental angiography is performed as follows. The patient is asked to lie in the supine position on the DSA operating table. A tourniquet is applied above the ankle of the affected limb to prevent the contrast agent from flowing back along the superficial veins. A 22-G intravenous indwelling needle is inserted into the dorsalis pedis vein, and a high-pressure injector is used to inject diluted contrast agent (prepared at a ratio of 1:1 of contrast agent to normal saline). The examination area spans from the ankle joint upward to the position above the opening of the renal vein. A total of five injections of contrast agent are required, and five segments are exposed and collected. Segment 1: from the ankle joint to the knee joint below, injection rate of 1 mL/s, total volume of 5–10 mL, injection delay of 1 s; Segment 2: from the knee joint below to the middle and lower segment of the femur, injection rate of 1 mL/s, total volume of 10–15 mL, injection delay of 1 s; Segment 3: from the middle and lower segment of the femur to the lesser trochanter, injection rate of 1 mL/s, total volume of 10–15 mL, exposure delay of 2 s; Segment 4: from the lesser trochanter to the junction of the bilateral iliac veins (release the tourniquet), injection rate of 2 mL/s, total volume of 20–25 mL, exposure delay of 3.5 s; and Segment 5: from the junction of the bilateral iliac veins to the position above the opening of the renal vein (release the tourniquet), injection rate of 2 mL/s, total volume of 25–30 mL, exposure delay of 5 s. The frame rate for all segments is set at 1 frame per second, and the pressure limit is set at 150 psi. For cases in which the contrast agent remains in the vein for a relatively long time after being emptied, an interval of 10 s to 4 min is required between each two segments of the exposure period. Alternatively, after injecting normal saline to accelerate the emptying of the contrast agent, the process should be observed through fluoroscopy until the contrast agent is emptied; subsequently, exposure and acquisition should be performed in the next segment to prevent the appearance of artifacts in the next segment of the angiography images.
Stepping angiography is performed as follows: The patient is asked to lie in the supine position on the DSA operating table. A tourniquet is applied above the ankle of the affected limb to prevent the contrast agent from flowing back along the superficial veins. A 22-G intravenous indwelling needle is inserted into the dorsalis pedis vein, and a high-pressure injector is used to inject diluted contrast agent (prepared at a ratio of 1:1 of contrast agent to normal saline). The examination area spans from the ankle joint upward to the position above the opening of the renal vein. The contrast agent is injected at one time, and the machine automatically completes the collection in an ascending order from bottom to top. Before exposure and collection, the X-ray left–right center line is aligned with the skin edge on the inner side of the knee joint, and the C-arm is moved under fluoroscopy to observe the segment from the ankle joint to the position above the opening of the renal vein. It is confirmed whether the lower extremity veins to the inferior vena cava are all within the projection field of view, the position is appropriate, and there is no omission of the interest area. Then, the C-arm gantry is returned to the ankle joint as the starting position, and the foot-to-head stepping DSA program is selected. The C-arm gantry is moved to the preset exposure position, and the high-pressure injector is connected and set to be linked to the DSA exposure. The injection rate of the contrast agent is 2 mL/s (for puncture vessels that are relatively thin, have a relatively thin wall, and are more brittle, a rate of 1 mL/s can be used). The injection delay is 0.5 s, and the total volume is 40–60 mL. The pressure limit is 200 psi. The exposure hand brake is pressed. The C-arm gantry will automatically and continuously segmentally expose and acquire the mask film from the starting position according to the preset position. After the mask film acquisition is completed, the angiography machine will start collecting DSA images from the starting position (ankle joint) while displaying the blood flow status on the monitor. It will control the step-by-step movement to the next acquisition segment through the C-arm gantry movement control button; the continuous dynamic venous blood flow images will be observed, and the timing of the C-arm gantry movement will be controlled properly to synchronize it with the return flow speed of the contrast agent. When the contrast agent is clearly displayed in the deep veins or the surrounding collateral veins, the C-arm gantry movement control button is pressed again to move to the next segment of blood vessels for exposure acquisition. The acquisition can be stopped when the inferior vena cava or the surrounding collateral veins are displayed. The acquisition images can be merged together on the workstation.
Observation targets
Two senior attending physicians at the Interventional Department and one DSA technician above the level of associate chief were responsible for recording all angiography procedures and conducting blind film reading and analysis of the images. They performed the following evaluations: 1. The angiography image quality in both groups, in terms of whether the veins in each segment were filled and full, the degree of image display and satisfaction, and the clarity rate of iliac vein and inferior vena cava (or collateral vessel display), were compared and evaluated. When the physicians and the technician agreed that the angiography images met the diagnostic requirements, it was considered that the images were clear; 2. The average angiography time (from the time of successful venous puncture), average absorbed radiation dose, average contrast agent dosage, and incidence of complications (such as contrast agent allergy and extravasation) among the patients were compared between the two groups.
Statistical methods
Statistical Package for Social Sciences (SPSS) 25.0 statistical analysis software was employed for data analysis. Measurement data that conformed to a normal distribution were expressed as mean ± standard deviation values and analyzed using t-tests. Counting data were expressed as frequency and percentage values and analyzed using the chi-square (χ2) test. The test statistics and their corresponding P-values were obtained from these analyses. A P-value <0.05 was considered to indicate a statistically significant difference between the two groups.
Results
The quality of lower limb venography images was compared between the two groups. The number of artifacts caused by unemptied contrast agent was lower in the observation group than in the control group. The observation group performed better than the control group in terms of visualization of the iliac vein and inferior vena cava and their surrounding collateral branches (Table 2). The average angiography time, average absorbed radiation dose, and average contrast agent dosage were lower in the observation group than in the control group. Two complications occurred in the control group, while three complications occurred in the observation group (Table 3). A comparison of lower limb venography images between the two groups is presented in Figure 2.
Comparison of the quality of lower limb venography images (n (%)).
Comparison of relevant Indicators for lower limb venography (mean ± SD, n (%)).
Comparison of lower limb venography images between the two groups. (a) Traditional segmental angiography from the ankle joint to the knee joint below. (b) Traditional segmental angiography from the knee joint below to the middle and lower segments of the femur. (c) Traditional segmental angiography from the middle and lower segments of the femur to the lesser trochanter. The red arrow indicates the artifact formed due to the contrast agent not being emptied. (d) Traditional segmental angiography from the lesser trochanter to the junction of the bilateral iliac veins. The red arrow indicates that the iliac vein is not clearly displayed and the density resolution is relatively low and (e) In stepping angiography, no artifacts are caused by unexcreted contrast agent. The iliac vein and inferior vena cava are clearly displayed with high-density resolution.
Discussion
In clinical practice, the most common indications for lower limb venography are acute and chronic lower limb swelling as well as varicose veins of the lower limb. In case of acute and chronic lower limb swelling, the purpose of the examination is to determine whether there is deep vein thrombosis, uncover the location of the thrombus, determine whether there is compression of the iliac vein, determine whether the thrombus has accumulated in the inferior vena cava, and observe the establishment of collateral branches. In case of varicose veins of the lower limb, it is necessary to determine the patency of the deep veins and the function of the valves—a preoperative examination for surgical or interventional treatment.4,11 These requirements indicate that DSA can provide clear and accurate images of the entire lower limb deep veins, inferior vena cava and their collateral branches, and the dynamic process of blood flow.
There is an inherent limitation of the projection field of the flat-panel detector in traditional segmental angiography. Therefore, to complete the examination of the entire lower limb veins, it is necessary to inject contrast agent five times and expose and obtain photographs in five segments, leading to repeated passage of the contrast agent through the distal blood vessels, resulting in an excessive contrast agent dosage. Meanwhile, in traditional segmental angiography, 25–40 mL of contrast agent is injected from the ankle joint to the lesser trochanter of the femur. To achieve better display effects for the iliac vein and inferior vena cava segments, 20–25 and 25–30 mL of contrast agent need to be injected, respectively. Within a short period, the total contrast agent dosage reaches 70–95 mL. To prevent the occurrence of contrast agent-induced nephropathy and unnecessary damage, especially for older patients and individuals with renal insufficiency, the total contrast agent dosage must be limited. 12 However, reducing the contrast agent dosage for the iliac vein and inferior vena cava segments during angiography leads to insufficient filling of some iliac veins and inferior vena cava, resulting in pale images and low-density resolution. 13 After each segmental angiography examination is completed, before proceeding to the next segmental angiography, it is often necessary to wait for a mean duration of 45 s, with the shortest duration being 10 s and the longest being up to 4 min. Occasionally, it is also necessary to push in normal saline to accelerate the emptying of the contrast agent and prevent the contrast agent from remaining in the blood vessels or at the valve from the previous angiography, causing artifacts in the next angiography and making diagnosis difficult. This also increases the examination duration for the patient and the risk of infection. Different patients have different blood flow speeds. In particular, for those with thrombosis or stenosis and occlusion in the main trunk, the contrast agent often cannot flow upward or flows upward slowly. 14 The X-ray delay time is difficult to be accurately controlled. The tube is often in an ineffective exposure state. It is necessary to wait until the collateral branches are slowly filled before capturing valuable images, increasing the load on the tube; moreover, the radiation dose received by the patient is significantly increased.
Stepping angiography, also known as the Bolus Chase technique (remote-controlled contrast agent tracking angiography technique), is a dynamic DSA technique. It is mainly used to observe the morphological structure and pathological conditions of large blood vessels and is applicable for vascular examinations of the limbs.7,15 There are several advantages of stepping angiography for lower limb venography. First, for completing the examination of all lower limb veins, the contrast agent is injected only once and is continuously exposed, enabling real-time observation of the vascular conditions within a large area of the human body. The total injection volume should be sufficient to clearly display the inferior vena cava (40–60 mL). The contrast agent flows through each segment position (from the calf vein to the iliac vein) in a descending order. The C-arm gantry also moves synchronously from the bottom to top at the blood flow speed. The equipment is used to perform continuous stepwise photography. The contrast agent required for imaging from the calf vein to the iliac vein reaches the inferior vena cava via the distal end. The total amount of contrast agent needed for a single inferior vena cava angiography is sufficient to clearly display the veins in the lower limbs, with collateral vessels filling up faster. At the same time, using a relatively large, one-time dose of 40–60 mL of contrast agent can help display the iliac vein and inferior vena cava clearly, with fuller filling, clear collateral vessels, sharp edges, and high-density resolution; it also enables observation of the opening of the renal vein. This provides preliminary evidence for the feasibility of inferior vena cava filter implantation. 16 The contrast agent utilization rate is high. The total dosage of contrast agent used for venography of the entire lower limb is relatively small. Specifically, in case of older patients and individuals with renal insufficiency, it prevents damage to the body and reduces the examination cost for the patients. 17 In this study, the average contrast agent dosage used for lower limb venography in the observation group decreased by approximately 31.6% compared with that in the control group. Moreover, the display rates of the iliac vein and inferior vena cava increased by 26.9% and 62.2%, respectively. For five patients in the observation group, the iliac vein display was poor. Among them, three were confirmed to have extensive fresh blood clots in the iliac vein after transcatheter angiography, with less collateral vessel compensation and blood flow obstruction to the heart. In two cases, the condition was caused by severe varicose veins of the great saphenous vein in the lower limbs, where the contrast agent was largely retained in the dilated vascular bed through the communicating veins, resulting in insufficient contrast agent reaching the iliac vein. Eight patients showed poor display of the inferior vena cava. Among them, five patients showed poor display due to the poor display of the iliac vein, two patients showed poor display due to the thin walls and greater brittleness of the puncture vein in the dorsal foot, which led to vessel rupture during the injection of the contrast agent and premature termination of the injection. In one case, the display was poor due to the lack of regular stability adjustment of the equipment, where the C-arm gantry vibrated greatly during the stepping movement, resulting in equipment-induced motion artifacts. Second, stepping angiography is performed by obtaining the mask film of the interest areas of each segment before the contrast agent is injected into the blood vessels. The mask film of each segment remains unaffected by the unemptied and retained contrast agent; therefore, there is no need to wait for the contrast agent to be emptied between two consecutive angiographies. Moreover, there is no need to push in normal saline to promote the emptying of the contrast agent, which reduces the examination duration and prevents artifacts caused by the residual contrast agent in the proximal blood vessels when the distal vessels are being imaged. In this study, the average angiography time for lower limb venography in the observation group was 63.3% less than that in the control group, and no artifacts caused by the residual contrast agent were observed. Third, the radiation dose is determined by the cumulative exposure times, unit dose, and exposure duration. 18 Stepping angiography proceeds sequentially from the ankle to the inferior vena cava. The flat-panel detector collects images in the order of blood flow, obtaining continuous images at one time. In traditional segmental angiography, each segment must undergo the process of waiting for the contrast agent to reach partial filling and then complete filling. Moreover, the X-ray delay cannot be determined with complete accuracy. In the same segment, the number of unit exposures significantly increases, and phenomena such as ineffective exposure collection may occur. Compared with traditional segmental angiography, stepping angiography reduces the waiting time for the contrast agent to reach the area of interest and the delay steps, prevents unnecessary exposures, reduces the number of exposures per unit time, and lowers the radiation dose received by the patient and the load on the X-ray tube. 19 In this study, the average absorbed radiation dose of the observation group decreased by 24.1% compared with that of the control group.
A comparison of the two angiography methods revealed the following. First, stepping angiography is characterized by higher equipment requirement, necessity of a real-time stepping function module, and a relatively higher equipment cost. Second, in case of angiography machines that do not regularly perform equipment stability debugging, during the stepping operation of the C-arm gantry, the gantry often shows obvious vibration, causing equipment-induced motion artifacts. However, the gantry of the segmental DSA does not need continuous movement, and exposure subtraction can be performed after waiting for the gantry to stabilize, which will not cause equipment-induced motion artifacts. Therefore, in case of unstable equipment gantry, traditional segmental angiography is preferred. Third, for some patients with severe foot swelling, the punctured veins have small lumens, thin walls, and high fragility. To prevent vascular rupture or the formation of large hematomas after rupture, the injection rate and total volume of contrast agent should be reduced. Therefore, stepping angiography is not advisable, and traditional segmental angiography should be performed. Finally, for some patients with forced lower limb positions, such as fractures or severe skeletal deformities, the path from the calf vein to the inferior vena cava may not be completely within the projection field during stepping angiography. Therefore, stepping angiography cannot be used, and traditional segmental angiography should be performed. The projection position should be adjusted in segments for angiography acquisition. This study has certain limitations. First, the sample size of this study is relatively small, which may lead to certain limitations and bias. Second, there was no significant difference in the incidence of complications between the two groups. In total, five patients developed complications; in all cases, the complication was contrast agent extravasation at the injection site during the injection of the contrast agent. Although the patients’ conditions improved after symptomatic treatment and no serious complications occurred, further research in clinical practice is required to understand how to prevent such complications.
Conclusion
In case of lower limb anterograde venography, stepping angiography offers obvious advantages over traditional segmental angiography in terms of display of the iliac vein and inferior vena cava, angiography time, absorbed radiation dose, and contrast agent dosage. Moreover, the overall image is intuitive and may be used as the preferred acquisition method for lower limb anterograde venography. In critical cases, segmental angiography may be performed as a supplementary procedure.
Footnotes
Acknowledgements
The authors are grateful to all the research participants and the staff that were involved in the study.
Author contributions
Conceived and designed the experiments: Hongzhi Sun and Lei Qi. Performed the experiments: Lei Qi, Huagang Li, and Maoneng Hu. Analyzed the data: Peng Ji, Guoliang Wang, and Hongzhi Sun. Wrote the paper: Hongzhi Sun and Lei Qi.
Data availability statement
The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.
Declaration of conflicting interests
The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethics approval
This study was approval by the medical ethics committee of the Third People’s Hospital of Hefei (approval number: 2025LLWL014).
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article. This work was supported by the 2023 Scientific Research Project at the Third People’s Hospital of Hefei (SYKY202301). The funder had no role in the study design, data collection, data interpretation, writing of the report, decision to publish, or preparation of the manuscript.
