Technical report: Magnetic resonance direct thrombus imaging at 3 T field strength in patients with lower limb deep vein thrombosis: a feasibility study.
OBJECTIVE
To investigate the feasibility of imaging lower limb deep vein thrombosis using magnetic resonance imaging (MRI) at 3.0 T magnetic field strength with an optimized a T1 magnetization prepared rapid gradient echo technique (MP-RAGE) in patients with normal volunteers as controls.


METHODS
Patients with deep vein thrombosis (n = 4), thrombophlebitis (n = 2) and healthy volunteers (n = 9) were studied. MRI of the distal thigh and upper calf was performed at 3.0 T with MP-RAGE using two pre-pulses to suppress blood and fat (flip angle 15 degrees, echo time 5 ms, and repetition time 10 ms). A qualitative analysis was performed for detection of thrombi and image quality. Contrast-to-noise ratios were determined in thrombosed and patent veins.


RESULTS
Thrombi were clearly visible as high-signal intensity structures with good suppression of the anatomical background. A blinded reader accurately diagnosed 15 out of 16 cases. The contrast-to-noise ratio measurements showed a positive contrast of thrombus over background muscle 16.9 (SD 4.3, 95% CI: 12.5-21.3) and a negative contrast of the lumen to muscle in patent veins of normal volunteers -7.8 (SD 4.3, 95% CI: -11.1 to -4.5), with p = 0.0015.


CONCLUSIONS
Thrombi generate high signal intensity at 3.0 T allowing for their direct visualization if flowing blood, stationary blood and fat are sufficiently suppressed. This preliminary data supports the development of these techniques for other vascular applications.
Schmitz
S A
SA
Imaging Sciences Department, Imperial College, Hammersmith Hospital, London, UK.
O'Regan
D P
DP
Gibson
D
D
Cunningham
C
C
Fitzpatrick
J
J
Allsop
J
J
Larkman
D J
DJ
Hajnal
J V
JV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004574:Electromagnetic Fields; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D035002:Lower Extremity; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020246:Venous Thrombosis / Q000175:diagnosis*