Lower-limb deep venous thrombosis: direct MR imaging of the thrombus

To determine the feasibility of diagnosing deep venous thrombosis (DVT) with direct three-dimensional magnetic resonance (MR) imaging of the thrombus.Eighteen patients with proved DVT at conventional venography were evaluated with a magnetization-prepared three-dimensional blood- and fat-suppressed MR imaging sequence. The presence and extent of thrombosis on the MR images were compared with the findings at conventional venography.At MR imaging, DVT was visualized in 17 of the 18 patients. MR imaging demonstrated greater proximal extent of the thrombosis in four patients, asymptomatic contralateral thrombosis in one, involvement of the deep femoral vein in five, and involvement of the superficial venous system in three.Direct MR imaging of clots appears capable of demonstrating venographically diagnosed DVT. This MR imaging technique is noninvasive, quick, and repeatable and allows a survey of the whole lower-limb venous system. Detection of thrombosis relies on the formation of methemoglobin, which appears to be sufficiently rapid to allow use of this technique in the clinical setting. Changes in the signal from clot over time may allow estimation of the age of the thrombus.