Correlation with degree of iliac vein compression

In 1957, May and Thurner described the compression of the left common iliac vein (LCIV) by the right common iliac artery (RCIA) at L5 level. The chronic irritation caused by RCIA pulsation could result in a fibrotic venous spur within the LCIV, causing flow changes, and could lead to deep vein thrombosis (DVT) in this limb. The prevalence of this compression is around 22%–32% in cadavers.

This condition is asymptomatic in most cases, but when symptomatic can cause chronic pelvic pain, inferior limb swelling, varicosities, claudication, DVT, chronic ulcers, varicocele, or severe complications such as pulmonary embolism and vein rupture.

May Thurner syndrome (MTS) usually occurs in women between the second and fourth decade of life. Persistent or recurrent swelling of the left lower limb in a young woman, with or without DVT, is highly suggestive of MTS. The diagnosis of MTS should be based on the patient’s clinical history and imaging findings.

A: Time-resolved imaging technique depicting suprapubic, pre-sacral and abdominal wall collateral vessels (red arrows) associated with signs of left external iliac vein thrombosis (blue arrow). B: TRI exam with no signs of collateral vessels.

Venography was traditionally the gold standard for diagnosis and assessment of the location and severity of compression, presence of collateral and flow pattern, but it is invasive and time consuming.

Time-resolved imaging (TRI) is a minimally-invasive MR technique that provides high temporal and contrast resolution, dynamically evaluating the flow pattern of ovarian veins (OV) and pelvic collaterals in a similar way to conventional venography.

Diagnosing MTS and other causes of congestion pelvic syndrome (CPS) on CT and MRI (without TRI) is mainly based on morphology, specifically on the diameter of the LCIV and OV, without information on flow direction and assessment of all collaterals.

TRI can be used to accurately assess the flow direction and anatomy of ovarian and collateral veins, regardless of their calibre, and provide therapeutic planning for endovascular treatment without exposure to ionising radiation.

MTS is only treated when symptomatic, and the correct detection of flow direction of the involved veins is considered crucial for planning the patient’s therapy (stent placement or endovascular occlusion).

MRI-angiography. A: FIESTA sequence at the point of maximal degree of compression in the left common iliac vein (LCIV) graded as 0cm of calibre. B: Post-contrast sequence showing compression in the LCIV, but with a calibre measured as 0.2cm.

Stent placement is considered an option; however, most MTS patients are young, and there are no data on stent integrity beyond ten years, so this option should be used with caution.

The aim of our study was to evaluate the benefit of TRI in patients with clinical suspicion of MTS, correlating the degree of LCIV compression with the presence of collaterals. We also evaluated inter and intra-observer variability regarding the degree of compression using different techniques (FIESTA/LAVA).

TRI demonstrated a clear benefit in assessment of the pelvic vasculature, showing a correlation between the degree of LCIV compression and the formation of collaterals, with a p <0.001. We also observed a statistically significant difference in LCIV measurement between techniques and readers, which reinforces the importance of a combined evaluation using dynamic analysis with TRI, rather than an isolated morphological measurement of the LCIV calibre.

In conclusion, TRI allows dynamic assessment in MTS patients with better evaluation of collaterals, which correlates well with the degree of LCIV compression.

Dr. Dyandra Moreira de Araújo is an Abdominal Radiologist at Hospital do Coração in São Paulo, Brazil.

Research Presentation Session
RPS 1815 MR in vascular imaging

The benefits of time-resolved imaging (TRI) in May Thurner syndrome (MTS): a correlation with the degree of iliac vein compression
D.M.D. Araújo1, M.D.P. Estrela2, M.M. Filisbino1, A. Skaf1, S.D.T.O. Cantoni1, F.H.C. Souza1, L.E.C. Paiva1, H. Leao Filho1; 1São Paulo/BR, 2Barretos/BR

Read the full abstract in the ECR 2020 Book of Abstracts
Araújo DMD, et al. (2020) The benefits of time-resolved imaging (TRI) in May Thurner syndrome (MTS): a correlation with the degree of iliac vein compression. Abstract RPS 1815-4 in: ECR 2020 Book of Abstracts. Insights Imaging 11, 34 (2020). DOI 10.1186/s13244-020-00851-0