引言/背景

• 定义：又称May - Thurner病变/解剖或Cockett综合征，多因左髂总静脉受右髂总动脉和脊柱压迫所致
• 发病率：相关压迫性静脉狭窄影响达70%成年患者，25%患者狭窄超50%
• 解剖位置：常见于近端髂总静脉，其次为中外侧髂静脉，罕见于远侧髂外静脉；右侧病变多在远侧髂外静脉，也见于下腔静脉左侧或主动脉分叉较高的患者
• 症状：常无症状，有症状时称May - Thurner综合征，可致下肢水肿、深静脉血栓形成或慢性静脉功能不全；女性有盆腔静脉疾病、慢性盆腔疼痛，男性罕见精索静脉曲张
• 诊断：需详细病史和体格检查排除其他病因，有症状者需影像学评估确诊

特殊影像学考虑

• 关键：识别盆腔血管内的压迫，结合血流动力学信息及血管壁和管腔特征评估
• 注意事项：仰卧位成像可能高估压迫性病变程度和血流动力学意义，脱水也会高估其血流动力学或临床意义
• 成像方式
  • 超声（US）：包括双功超声、血管内超声等，双功超声可在直立或卧位成像，利于压迫性病变特征分析；常规US无创、无电离辐射，彩色双功US可实时表征血流动力学；血管内超声可辅助病变形态、长度等特征分析及支架尺寸和放置
  • CT：横断面成像，空间分辨率好、成像快，无对比剂时静脉结构评估受限；CT静脉造影（CTV）对NIVL评估有价值，但有对比剂肾毒性风险；CT血管造影（CTA）对NIVL评估作用有限
  • MRI：软组织特征优于CT，肾毒性相对低，但成像时间长、有幽闭恐惧症风险、空间分辨率低且对植入设备有限制；磁共振静脉造影（MRV）是评估静脉血管的最佳MRI方式，有肾源性系统性纤维化风险，新的MRI技术可无对比剂评估静脉
  • 导管静脉造影：曾是NIVL评估的参考标准，现被血管内超声取代，仍是血管特征、血流动力学和侧支血管可视化的重要成像方式，但为侵入性操作，一般不推荐作为一线成像评估

初始成像定义

• 开始医疗护理时的成像，多种程序可被视为通常合适的初始成像评估
  • 等效替代程序：仅需一种程序提供临床信息以有效管理患者护理
  • 互补程序：多种程序同时进行，每种程序提供独特临床信息以有效管理患者护理

不同情况的程序讨论

成人单侧下肢水肿，疑似非血栓性髂静脉病变，静脉病因，初始成像

• 超声双功多普勒下肢检查：可评估下肢浅、深静脉系统，确定肿胀病因；可在多种体位成像，排除假阴性；对轻度病变敏感性低于CTV，但能提供血流动力学数据；可评估反流，辅助诊断浅静脉反流疾病；与体积描记法结合可评估静脉血流动力学；可评估干预后长期临床效果
• 腹部和盆腔静脉造影（MRV），静脉注射对比剂：可作为一线成像研究，检测NIVL敏感性高，可排除近端静脉流出道梗阻，但确诊能力有限；时间分辨对比增强MRV可显示静脉血流方向和潜在反流模式
• 腹部和盆腔静脉造影（MRV），无和有静脉注射对比剂：同有静脉注射对比剂的MRV
• 腹部和盆腔静脉造影（MRV），无静脉注射对比剂：虽比有对比剂的MRV受限，但特殊序列可辅助NIVL检测和量化，如黑血静脉成像、多模态MRI协议等
• 腹部和盆腔静脉造影（CTV），双侧下肢造影，静脉注射对比剂：是强大的筛查方法，可确定静脉梗阻，辅助手术规划；与IVUS比较，敏感性和特异性较高；与DSA结合可提高预测准确性；评估双侧髂静脉可提高诊断能力
• 腹部和盆腔静脉造影（CTV），静脉注射对比剂：同双侧下肢造影的CTV
• 腹部和盆腔磁共振成像（MRI），静脉注射对比剂：无相关文献支持用于NIVL初始成像评估，标准序列对静脉结构评估不佳，但可识别其他病因
• 腹部和盆腔磁共振成像（MRI），无和有静脉注射对比剂：与有静脉注射对比剂的MRI类似，无对比剂的MRI对血管评估更差

成人无症状，已知左髂总静脉狭窄，在超声、CT或MRI发现非血栓性髂静脉病变，下一步成像研究

• 多种成像程序通常不合适，包括超声双功多普勒下肢检查、血管内超声、腹部X线摄影、导管静脉造影、磁共振血管造影（MRA）、MRI、MRV、CT、CTA、CTV等

成人盆腔疼痛，疑似非血栓性髂静脉病变，静脉病因，初始成像

• 经腹盆腔超声：通常合适
• 腹部和盆腔静脉造影（MRV），静脉注射对比剂：通常合适
• 腹部和盆腔静脉造影（MRV），无和有静脉注射对比剂：通常合适
• 腹部和盆腔静脉造影（MRV），无静脉注射对比剂：通常合适
• 腹部和盆腔静脉造影（CTV），双侧下肢造影，静脉注射对比剂：通常合适
• 腹部和盆腔静脉造影（CTV），静脉注射对比剂：通常合适
• 超声双功多普勒下肢检查：可能合适
• 腹部和盆腔磁共振成像（MRI），静脉注射对比剂：可能合适
• 腹部和盆腔磁共振成像（MRI），无和有静脉注射对比剂：可能合适
• 腹部和盆腔CT，静脉注射对比剂：可能合适
• 腹部和盆腔CT，无和有静脉注射对比剂：可能合适
• 其他程序通常不合适，如血管内超声、下肢超声、腹部X线摄影、导管静脉造影、MRA、无静脉注射对比剂的MRI和CT、CTA等

初始成像（补充）

CT Abdomen and Pelvis

• With IV Contrast: Standard portal venous phase may highlight NIVL, but CTV better for venous evaluation. Can identify alternative compression sources. Computational fluid dynamic evaluation can quantify flow disturbances
• Without and With IV Contrast: Similar details as with IV contrast. Without IV contrast is inferior for vasculature evaluation but can add diagnostic value in some cases
• Without IV Contrast: Limited evaluation of vasculature, no relevant literature for initial evaluation

US

• Intravascular Iliac Veins: No relevant literature for initial evaluation. Invasive, not a first - line study. Reference standard for evaluation after diagnosis, better for lesion localization and characterization than venography
• Lower Extremity: Can show postthrombotic changes. Diagnostic accuracy varies, not optimal for NIVL diagnosis due to lack of duplex
• Lower Extremity With IV Contrast: Limited data for evaluating chronic iliac vein obstruction, not an ideal initial study

Radiography

• Abdomen: No relevant literature for initial evaluation, venous compression not evident

Catheter Venography

• Pelvis and Lower Extremity: No relevant literature for initial evaluation. Invasive, less reasonable with non - invasive options. Poor sensitivity compared to IVUS, may over - identify non - significant variants
• 3 - D Rotational Venography: Higher detection rate of pelvic collateral veins, contralateral iliac vein filling, and external iliac vein indentation. Provides richer diagnostic information, reduces procedure time and contrast usage

MRI

• Abdomen and Pelvis
  • With IV Contrast: No relevant literature for initial evaluation, suboptimal for venous structure evaluation
  • Without and With IV Contrast: Similar details as with IV contrast, inferior for vasculature evaluation
  • Without IV Contrast: No relevant literature for initial evaluation, suboptimal for venous structure evaluation
• MRV
  • Abdomen and Pelvis With IV Contrast: A reasonable screening method for venous obstruction
  • Abdomen and Pelvis Without and With IV Contrast: A reasonable screening method for venous obstruction
  • Abdomen and Pelvis Without IV Contrast: A reasonable screening method for venous obstruction, specialized sequences can aid in detection

CTA

• Abdomen and Pelvis With Bilateral Lower Extremity Runoff With IV Contrast: Designed for arterial anatomy, limited evaluation of venous structures, no relevant literature for initial evaluation
• Abdomen and Pelvis With IV Contrast: Designed for arterial anatomy, limited evaluation of venous structures, no relevant literature for initial evaluation

CTV

• Abdomen and Pelvis With Bilateral Lower Extremity Runoff With IV Contrast: An effective screening tool for venous obstruction
• Abdomen and Pelvis With IV Contrast: A powerful screening method for venous obstruction, can evaluate alternative pathology

无症状成人已知左髂总静脉狭窄（补充）

US

• Duplex Doppler Lower Extremity: No relevant literature for further evaluation
• Intravascular Iliac Veins: No relevant literature for further evaluation
• Lower Extremity: No relevant literature for further evaluation
• Lower Extremity With IV Contrast: No relevant literature for further evaluation

Radiography

• Abdomen: No relevant literature for follow - up evaluation

Catheter Venography

• Pelvis and Lower Extremity: No relevant literature for subsequent imaging, invasive, poor sensitivity compared to IVUS, may over - identify non - significant variants

MRI

• Abdomen and Pelvis
  • With IV Contrast: No relevant literature for further evaluation
  • Without and With IV Contrast: No relevant literature for further evaluation
  • Without IV Contrast: No relevant literature for further evaluation
• MRV
  • Abdomen and Pelvis With IV Contrast: A reasonable screening method, no additional imaging needed if asymptomatic
  • Abdomen and Pelvis Without and With IV Contrast: A reasonable screening method, no additional imaging needed if asymptomatic
  • Abdomen and Pelvis Without IV Contrast: A reasonable screening method, no additional imaging needed if asymptomatic

CT

• Abdomen and Pelvis
  • With IV Contrast: No relevant literature for further workup
  • Without IV Contrast: No relevant literature for further workup
  • Without and With IV Contrast: No relevant literature for further workup
• CTA
  • Abdomen and Pelvis With Bilateral Lower Extremity Runoff With IV Contrast: No relevant literature for further workup
  • Abdomen and Pelvis With IV Contrast: No relevant literature for further workup
• CTV
  • Abdomen and Pelvis With Bilateral Lower Extremity Runoff With IV Contrast: An effective screening tool, no additional imaging needed if asymptomatic
  • Abdomen and Pelvis With IV Contrast: An effective screening tool, no additional imaging needed if asymptomatic

成人盆腔疼痛疑似NIVL（静脉病因）（补充）

US

• Pelvis Transabdominal: A useful initial imaging study for NIVL evaluation and exclusion of alternative pathology. Limited by patient factors, can be mitigated. Moderate diagnostic value for clinically significant lesions
• Duplex Doppler Lower Extremity: Can evaluate venous structures in leg. Useful for determining underlying source of suspected venous etiology. Less sensitive than CTV, especially for mild lesions. Can be supplemented with APG, MVOV

MRV

• Abdomen and Pelvis With IV Contrast: A first - line imaging study for NIVL evaluation, can rule out proximal venous outflow obstruction
• Abdomen and Pelvis Without and With IV Contrast: Can demonstrate dynamic flow evaluation
• Abdomen and Pelvis Without IV Contrast: A first - line imaging study, specialized sequences can aid in detection

CTV

• Abdomen and Pelvis With Bilateral Lower Extremity Runoff With IV Contrast: A powerful screening method for venous obstruction, can aid in procedural planning
• Abdomen and Pelvis With IV Contrast: A powerful screening method for venous obstruction, can evaluate alternative pathology

MRI

• Abdomen and Pelvis With IV Contrast: No relevant literature for initial evaluation, suboptimal for venous structure evaluation
• Abdomen and Pelvis Without and With IV Contrast: Similar details as with IV contrast, inferior for vasculature evaluation

影像学检查（补充）

超声检查

• 下肢静脉超声造影（CEUS）
  • 支持其用于慢性髂静脉梗阻评估的数据少
  • 与常规超声和血管内超声（IVUS）对比研究显示，诊断髂外静脉和髂总静脉准确性分别为71.3%和53.2%
  • 增强与未增强超声类内相关系数0.9，两种成像方式一致性好
  • 受技术因素限制，非理想初始成像检查

放射学检查

• 腹部X线
  • 无相关文献支持用于NIVL初始成像评估
  • 无法显示静脉受压情况

导管静脉造影

• 骨盆及下肢导管静脉造影
  • 无相关文献支持用于NIVL初始成像评估
  • 非侵入性技术使该侵入性检查合理性降低
  • 历史上用于术中确诊
  • 与IVUS对比，检测静脉狭窄>70%敏感性45%，阴性预测值49%
  • 煎饼征与侧支血管同时出现，识别左髂总静脉病变敏感性97%
  • 30例健康无症状受试者研究显示，80%有两个或更多NIVL静脉造影征象，15%髂静脉狭窄无侧支血管，仅1例无梗阻症状
  • 可能导致根据静脉造影过度治疗
  • 3 - D旋转静脉造影检测盆腔侧支静脉、对侧髂静脉充盈、髂外静脉压迹率更高，诊断信息丰富，减少操作时间和造影剂用量

磁共振血管造影（MRA）

• 腹部、骨盆及双侧下肢静脉MRA（静脉注射造影剂）
  • 无相关文献支持用于NIVL初始成像评估
  • 主要显示动脉解剖，静脉结构评估受限

磁共振成像（MRI）

• 腹部及骨盆非增强MRI
  • 无相关文献支持用于NIVL初始成像评估
  • 无评估静脉结构的最佳序列，总体评估欠佳
  • 可识别其他病因

CT检查

• 腹部及骨盆非增强CT
  • 无相关文献支持用于NIVL初始成像评估
  • 无静脉造影剂限制血管评估
• 腹部、骨盆及双侧下肢静脉CT血管造影（静脉注射造影剂）
  • 无相关文献支持用于NIVL初始成像评估
  • 主要显示动脉解剖，静脉结构评估受限
• 腹部及骨盆CT血管造影（静脉注射造影剂）
  • 无相关文献支持用于NIVL初始成像评估
  • 主要显示动脉解剖，静脉结构评估受限

推荐总结

• 变异1和3
  • 下肢双功能超声、腹部及骨盆CT静脉造影（双侧下肢静脉成像，静脉注射造影剂）、腹部及骨盆MR静脉造影（有或无静脉注射造影剂）通常适用于疑似静脉病因的单侧下肢水肿和/或盆腔疼痛初始评估
  • 除超声外，可评估非血栓性髂静脉病变及其他病因
  • 双功能超声评估症状静脉起源
• 变异2
  • 无症状患者无需进一步成像或评估

辐射相关信息

• 辐射暴露潜在不良健康影响是选择成像检查重要因素
• 不同诊断检查辐射暴露范围广，各成像检查有相对辐射水平（RRL）指示
• RRL基于有效剂量，用于估计成像检查相关人群总辐射风险
• 儿科患者因器官敏感性和预期寿命长，辐射暴露风险高，儿科检查RRL剂量估计范围低于成人