Sequential 2D inflow venography: initial clinical observations

MR Venography for the Assessment of Deep Vein Thrombosis in Lower Extremities with Varicose Veins

OBJECTIVE

To assess the performance of magnetic resonance venography (MRV) for pelvis and deep vein thrombosis in the lower extremities before surgical interventions for varicose veins.

MATERIALS AND METHODS

We enrolled 72 patients who underwent MRV and ultrasonography before stripping for varicose veins of lower extremities. All images of the deep venous systems were evaluated by time-of-flight MRV.

RESULTS

Forty-six patients (63.9%) of all were female. Mean age was 65.2 ± 10.2 years (37-81 years). There were forty patients (55.6%) with varicose veins in both legs. Two deep vein thrombosis (2.8%) and three iliac vein thrombosis (4.2%) were diagnosed. All patients without deep vein thrombosis underwent the stripping of saphenous veins, and post-thrombotic change was avoided in all cases.

CONCLUSION

MRV, without contrast medium, is considered clinically useful for the lower extremity venous system.

Dynamic MRA with four-dimensional time-resolved angiography using keyhole at 3 tesla in head and neck vascular lesions

Conventional MRA provides inadequate visualization of the dynamic features of blood flow in vascular lesions of the head and neck. Four-dimensional time-resolved angiography using keyhole (4D-TRAK) is a new technique of performing contrast-enhanced MRA. By combining parallel imaging with sensitivity encoding (SENSE) with the keyhole imaging technique and a high field strength (3 T) magnet, we have been able to obtain detailed hemodynamic information similar to that obtained via catheter angiography with digital subtraction (DSA), but without the risks associated with ionizing radiation exposure, iodizing contrast agents, or catheterization itself.

Dynamic MR venography: An intrinsic benefit of time-resolved MR angiography

PURPOSE

To investigate the possibility of obtaining dynamic contrast-enhanced magnetic resonance venography (DCE-MRV) images of the lower extremities.

MATERIALS AND METHODS

Peripheral contrast-enhanced magnetic resonance angiography (CE-MRA) was performed on 20 patients using a time-resolved sequence that combined undersampled projection reconstruction (PR) in-plane and Cartesian slice encoding through-plane. The contrast dynamics of distal vessels were depicted. An automated segmentation algorithm based on a contrast arrival time (CAT) threshold was used to generate contrast dynamics in the venous system. The signal difference between the vein and artery was measured to evaluate the effectiveness of this technique in isolating the venous contrast dynamics.

RESULTS

The automatically generated image series depicted the contrast dynamics of both the arterial and venous systems, including asymmetric venous enhancement and background tissue enhancement. Quantitative measurement showed a mean venous/arterial signal ratio increase from 1.58 to 4.82 for the peak venous frame after arterial signal suppression.

CONCLUSION

DCE-MRV is a minimally invasive technique for evaluating the venous side of the systemic vascular anatomy. Time-resolved MRA has the potential clinical benefit of enabling both arterial and venous disease to be detected in patients undergoing CE-MRA.

[Usefulness of lower extremity 2D TOF MR venography with respiratory compensation technique, and effect of patient positioning on the visualization of deep veins in the leg]

We evaluated the usefulness of two-dimensional time-of-flight (2D TOF) MR venography (MRV) of the lower extremity using the respiratory compensation (RC) technique. In addition, six variations in patient positioning of the leg and knee were investigated to determine the best method of visualizing the deep popliteal veins and lower leg. All data sets were reviewed and graded for visualization of the deep veins at the pelvis, thigh, and leg portion (4-point scale) by two radiologists and three radiological technologists. The same veins demonstrated with various positions of the patient were also evaluated in the same manner. In conclusion, 2D TOF MRV with RC resulted in increased uniformity of vein signal in the pelvic area. Furthermore, we should position the patient's leg so as not to compress the vein at the posterior portion of the leg, and not to over-extend the knee joint. This enabled the best results to be obtained in MRV of the lower extremity.

Value of a blood pool contrast agent in MR venography of the lower extremities and pelvis: Preliminary results in 12 patients

The purpose of this study was to determine the value of a blood-pool contrast media (NC100150, Nycomed Imaging (now Amersham Health) Oslo, Norway) for evaluation of venous thrombosis of the deep veins of the pelvis and lower extremities. Twelve patients were prospectively evaluated with conventional X-ray venography (XRV) and MR venography (MRV) after injection of NC100150 (2 ml/kg body weight). The source images and 3D maximum intensity projection (MIP) were viewed on an independent workstation. Diagnosis was made in consensus from two radiologists. Diagnostic image quality was achieved in 87 veins with XRV and MRV. As determined by XRV, thrombus was present in 30 out of 87 veins (34.5%). There was agreement concerning absence or presence of thrombi in 83 out of 87 veins (95.4%; kappa = 0.9 +/- 0.05). Compared to XRV, overall sensitivity and specificity of blood-pool MRV were 93.3% and 96.5%, respectively. Two venous thromboses of the popliteal and posterior tibial vein were diagnosed in MRV, but not in XRV. Conversely, two venous thromboses below the knee had been missed by MRV. NC100150 allows prolonged and improved visualization of the peripheral vasculature and may overcome some limitations of gadolinium contrast media. A more complete examination of the proximal venous tree may be possible than with conventional XRV. Arterial and venous enhancement and motion artifacts can limit image interpretation.

Pelvic and lower extremity veins: contrast-enhanced three-dimensional MR venography with a dedicated vascular coil-initial experience

PURPOSE

To assess the performance of three-dimensional (3D) magnetic resonance (MR) venography of the pelvis and lower extremities in patients without acute deep venous thrombosis by using a lower extremity vascular coil and pedal injection of paramagnetic contrast material.

MATERIALS AND METHODS

Conventional and MR venography were performed in 35 legs in 25 patients referred for evaluation of varicosities (n = 8) and postthrombotic changes (n = 7) and assessment of the great saphenous veins prior to bypass surgery (n = 10). Injection of 120 mL of diluted (1:15) gadopentetate dimeglumine into a pedal vein was performed manually at a rate of 1 mL/sec, and 3D gradient-recalled echo data sets of the upper and lower veins were collected. Conventional and MR venographic images were analyzed separately in a blinded fashion.

RESULTS

MR image quality was comparable to that of conventional venograms. Varicose changes of the great and small saphenous veins (sensitivity, 94% [44 of 47]; specificity, 96% [89 of 93]) were assessed as reliably as their status before bypass surgery (sensitivity, 98% [53 of 54]; specificity, 92% [47 of 51]). Postthrombotic changes were diagnosed with a sensitivity of 100% [13 of 13] and a specificity of 98% [88 of 90].

CONCLUSION

Direct 3D MR venography comprehensively displays the lower extremity venous system and permits assessment of postthrombotic and varicose changes and the bypass suitability of the saphenous vein.

Three-dimensional low dose gadolinium-enhanced peripheral MR venography

Our initial experience with low dose contrast-enhanced (LCE) peripheral MR venography (MRV) is presented. Five subjects were studied using three-dimensional (3D) fast imaging with a steady-state precession (FISP) sequence. A dose of 60 ml of gadopentetate dimeglumine diluted 1:20 was used. A tourniquet was applied during lower extremity MR venography. The venous anatomy was well depicted with the 3D LCE technique in all subjects. Compared to the two-dimensional (2D) time-of-flight (TOF) technique, acquisition time of 3D LCE MRV was much shorter, images looked sharper, and more veins could be seen. It is not affected by in-plane saturation and can be performed repeatedly because of the low dose of contrast. This technique holds promise for the detection of venous thrombosis and other disorders.