An in vitro experimental study and clinical applications of MR angiography with low-dose contrast agent of lower limb arteries at 3.0 T / 中华放射学杂志

ABSTRACT

Objective To evaluate the feasibility and diagnostic accuracy of CE-MRA with low dose contrast agent by comparison with DSA in diabetic patients with peripheral arterial diseases. Methods ( 1 )Study in vitro test tubes containing Gd-DTPA of different concentrations were scanned, and the relationship between signal intensities and concentrations of GD-DTPA was analyzed. DSA and CE-MRA with selected concentrations of Gd-DTPA were performed on stenotic vascular models to estimate the proper low dose of GD-DTPA for clinical applications. (2) Clinical applications 78 diabetic patients with peripheral arterial diseases were scanned from the abdomen and pelvis station to the calf-foot station in a 3 T MR system with standard bolus chase 3D CE-MRA sequence after injection of 13 ml GD-DTPA . The image quality,diagnostic rate of stenosis of arteries in calf and degree of venous contamination were evaluated with Fisher's exact test. DSA images of 220 vascular segments in 22 patients ( 10 segments per patient) were acquired as the gold standard and compared with CE-MRA by using Kappa test. Results The MR signal intensities were proportional to the concentrations of contrast agent in present study, and all stenotic segments of vascular model were displayed by CE-MRA with GD-DTPA at lower concentration of 1.5 mmol/L. As for MRA images of 78 diabetic patients with low dose Gd-DTPA, about 97.4% (76/78) showed diagnostic image quality for pelvic and thigh stations. But the MRA images of lower extremities were interfered by the venous contamination significantly (P ＜ 0.01 ). Compared with DSA for 22 patients, the diagnostic sensitivity, specificity and agreement coefficient (Kappa value) of MRA were 96. 0% ( 168/175), 73.3%(33/45), and 0.72 (P＜0.01), respectively. Conclusion Using 3.0 T MR scanner, high quality CE-MRA of lower limb arteries can be obtained for clinical applications with contrast agent dose as low as 13 ml,which has comparable diagnostic sensitivity and specificity with DSA. But the limitation of venous contamination in MRA image should be resolved in further studies.