Novel typing of iliac vein compression in asymptomatic individuals evaluated by contrast enhanced CT

Abstract

Purpose: Compression of the iliac vein between the iliac artery and lumbosacral vertebra can cause iliac vein compression syndrome (IVCS). The purpose of this study is to assess compression characteristics and establish a new sub-typing in asymptomatic IVCS individuals using contrast-enhanced CT.

Methods: A retrospective analysis of abdomen contrast-enhanced CT images from 195 asymptomatic subjects with iliac vein compressed was investigated. Patients had no history of venous pathology, and images were collected from June 2018 to January 2019. Qualitative and quantitative characteristics of compression were examined including the location, pattern, minor diameter, area, and the percentage compression on an orthogonal section by the post-processing of multiple planar reconstruction and volume rendering.

Results: There were 107 females and 88 males with age range 18-92 years. The most common site of iliac vein compression was localized to the left common iliac vein (LCIV) (178/195, 91.3%). Notably, four compression types (type I-IV) were established according to the compression location, with type II being the most common. The four compression types had differences in the upper limit and fluctuation range of compression. It was found that the average level of iliac vein compression was below 25%. The compression degree of the left common iliac vein in type II was relatively concentrated, and the upper limit of compression was close to 70%.

Conclusion: Asymptomatic iliac vein compression was categorized according to compression location. The proposal of four types might help clinicians to predict which IVCS patients would benefit from interventional therapy.

Keywords: Asymptomatic diseases; Compression type; Iliac vein; Iliac vein compression syndrome; May-Thurner syndrome; Tomography; X-ray computed.

Fig. 1

Measurement on an orthogonal section by multiple planar reconstruction. a The angle (α₁, α₂) between the right (a) or left (b) common iliac vein and inferior vena cava at confluence level of the common iliac vein; b, c the minor diameter (b) and area (c) at the site of the maximum iliac vein (black arrow) compression by the iliac artery (white arrow)

Fig. 2

The compression percentage of LCIV and RCIV by age and gender. a The percentage compression of LCIV and RCIV by age. b, c The frequency distribution of LCIV (b) and RCIV (c) percentage compression in females and males. LCIV left common iliac vein, RCIV right common iliac vein

Fig. 3

A diagram of the four compression types in a volume rendering (a, d, g, j) and contrast-enhanced CT (axial, arterial phase, b, e, f, h, i, k; and sagittal reformation at venous phase, c, l). Type I a–c sole compression of LCIV (a, dotted square), the LCIV (black arrow) compressed by RCIA (white arrow); Type II d–f dual compression of the LCIV (d, dotted square), the LCIV (e–f, black arrow) compressed by RCIA (e, white arrow) and LIIA (f, white arrow) simultaneously; Type III g–i bilateral compression of the LCIV and the RCIV (g, dotted square), which was the LCIV (h, black arrow) compressed by LCIA (h, white arrow) and RCIV (i, black arrow) compressed by the RCIA (i, white arrow); Type IV j–l other compression types (j, dotted square), such as the LEIV (black arrow) compressed by LCIA (white arrow). LCIA left common iliac artery, LCIV left common iliac vein, LEIV left external iliac vein, LIIA left internal iliac artery, RCIA right common iliac artery, RCIV right common iliac vein

Fig. 4

The box-plot of percentage compression above zero percent in four types. LIV left iliac vein, RIV right iliac vein