Re-evaluation of iliac compression syndrome using magnetic resonance imaging in patients with acute deep venous thromboses

BACKGROUND: The majority of proximal deep venous thromboses (DVTs) are thought to have propagated as a contiguous column from the calf veins. However, several authors have proposed that ileofemoral DVT commonly originates in the left common iliac vein (LCIV) at a site of compression by the overlying right common iliac artery (RCIA/LCIV compression). This mechanism could explain both the left-sided predominance of ileofemoral DVT and the finding that ileofemoral DVT frequently occurs either in the absence of calf vein thrombosis (isolated ileofemoral DVT) or is not contiguous with calf vein thrombosis (noncontiguous ileofemoral DVT). This mechanism remains unconfirmed. OBJECTIVES: The purpose of this study was to detect RCIA/LCIV compression using multimodal magnetic resonance imaging in thrombosed and patent iliac veins, to determine whether RCIA/LCIV compression occurs more frequently in cases of left ileofemoral DVT than other types of DVT, and to determine if RCIA/LCIV compression is specifically associated with left isolated and noncontiguous ileofemoral DVT. PATIENTS AND METHODS: This prospective study conducted at the 1355-bed University Hospital included 18 patients with ileofemoral DVT, 23 with femoropopliteal DVT, 15 with isolated calf DVT recruited consecutively, and 28 control patients in whom DVT had been excluded. Interventions included magnetic resonance direct thrombus imaging (MRDTI), venous enhanced peak arterial magnetic resonance venography (VESPA) and magnetic resonance arteriography (MRA) within 48 hours of routine conventional venography (CV). RCIA/LCIV compression of patent LCIVs was assessed using VESPA and MRA; RCIA/LCIV compression of thrombosed LCIVs was assessed using MRDTI and MRA. The extent of calf and popliteal thrombosis was detected using CV; the extent of femoral and iliac thrombosis was detected using VESPA and MRDTI. RESULTS: RCIA/LCIV compression was more commonly detected in cases of left ileofemoral DVT (9/16 cases) than in cases of left femoropopliteal DVT (1/11 cases; P = .018), right femoropopliteal DVT (2/12 cases; P = .054), left isolated calf DVT (1/9 cases; P = .037), right isolated calf DVT (0/6 cases; P = .046) and control patients (4/28 cases; P = .006). RCIA/LCIV compression was more commonly detected in cases of left isolated ileofemoral DVT (6/6 cases; P = .005), and cases of left noncontiguous ileofemoral DVT (2/2 cases; P = .067) than in cases in which thrombosis was contiguous from the calf to the iliac veins (1/8 cases). CONCLUSION: RCIA/LCIV compression was strongly associated with left ileofemoral DVT and was specifically associated with cases that involve independent ileofemoral thrombosis.