Three-dimensional Phase-contrast Magnetic Resonance Angiography Research Articles

A new method for displaying the lingual artery using high-resolution three-dimensional phase-contrast magnetic resonance angiography

The aim of this study was to display the lingual artery superimposed on the anatomical image and to confirm its course and relation to the adjacent structures, noninvasively. Nineteen volunteers participated in the magnetic resonance imaging (MRI) study and one was excluded for excessive movement during scanning. A three-dimensional phase-contrast sequence (3D-PC) of magnetic resonance angiography (MRA) was used for vessel images, and a 3D-T1 high-resolution volume examination (THRIVE) was used for anatomical images. Colour-coded vessel images from 3D-PC MRA were superimposed on the 3D volume anatomical images, and the arterial course and relation to the adjacent structures were confirmed with multiplanar reconstructed cross-sectional (MPR) images. 3D-PC MRA images visualized the lingual artery in all 18 subjects and the sublingual artery in 14 subjects. In seven of 18 cases the bilateral sublingual arteries were shown to run side by side but had no contact with the sublingual veins. They ran together with the sublingual veins in four cases. Three cases showed irregular patterns. The bilateral sublingual arteries could not be identified in four cases. 3D-PC MRA images of the lingual artery superimposed on the anatomical images may be clinically useful to confirm its course and relationship to the adjacent structures before surgery, in order to prevent haemorrhage.

Visualization of the ophthalmic artery by phase-contrast magnetic resonance angiography: a pilot study

This study aimed at investigating whether phase-contrast (PC) magnetic resonance (MR) angiography is useful for visualizing the ophthalmic artery (OA). This prospective study enrolled 196 consecutive outpatients who underwent three-dimensional PC MR angiography. The basal image parallel to the anteroposterior dimension of the OA was extracted for analysis from the imaging data. The 99 male and 97 female subjects were aged from 10 years to 80 years (mean 47.9 years). The OAs were supplied only by the external carotid system or in combination with the internal carotid artery (ICA) in 18 subjects (9.2%). The bilateral OAs were symmetrical in 12%, asymmetrical in 87%, and unidentified in 1%. The contour of the proximal segment of the OAs could be classified into straight, curved, and tortuous types. The ICA-OA angle defined by the angle between the approximate line of the proximal OA and the vertical line was also variable. The first bend of the OA corresponded to the anastomosis site with the external carotid system. The proximal medial bend was the origin of the posterior ethmoidal artery, and the distal medial bend was the origin of the anterior ethmoidal artery. According to the results the OA not only possesses three characteristic bends, but also shows prominent individual variability and commonly shows bilateral asymmetry. The contour of the OA may be regulated by the anchor effect at the bend sites. PC MR Angiography is useful for visualizing the main trunk of the OA.

Three-Dimensional Phase-Contrast Magnetic Resonance Angiography: A Useful Clinical Adjunct to Gadolinium-Enhanced Three-Dimensional Renal Magnetic Resonance Angiography?

To assess the value of three-dimensional (3D) phase-contrast (PC) magnetic resonance angiography (MRA) after gadolinium (Gd)-enhanced 3D MRA for renal artery imaging. Twenty-one patients with suspected renal artery hypertension were reviewed. All studies included Gd-enhanced 3D MRA and 3D PC MRA. Blinded interpretation of the images was performed for each technique independently and in combination. Conventional X-ray angiography was used for diagnostic correlation when available. Renal artery stenosis was present in 7 (16.3%) of 43 renal arteries, confirmed by X-ray angiography. MRA images demonstrated 100% sensitivity and 74% specificity for Gd-enhanced 3D MRA and 100% sensitivity and 94% specificity for 3D PC MRA. All vessels were diagnosed correctly when both image sets were viewed. 3D PC MRA can improve the specificity of renal MRA by decreasing the number of false-positive Gd-enhanced 3D MRA interpretations.

Three-Dimensional Phase-Contrast Magnetic Resonance Angiography: A Useful Clinical Adjunct to Gadolinium-Enhanced Three-Dimensional Renal Magnetic Resonance Angiography?

Three-Dimensional Phase-Contrast Magnetic Resonance Angiography: A Useful Clinical Adjunct to Gadolinium-Enhanced Three-Dimensional Renal Magnetic Resonance Angiography?

Renal artery stenosis: value of screening with three-dimensional phase-contrast MR angiography with a phased-array multicoil.

To evaluate screening with three-dimensional (3D) phase-contrast magnetic resonance (MR) angiography with a phased-array multicoil to detect renal artery stenosis. Fifty consecutive patients suspected of having renovascular disease were prospectively examined with 3D phase-contrast MR imaging with a phased-array multicoil. Findings were correlated with those at intra-arterial digital subtraction angiography (DSA) as the standard of reference for grade of stenosis. MR angiography depicted 101 of 103 renal arteries depicted at intraarterial DSA; the two missed arteries were an accessory artery outside the imaging volume and an artery with a stent. At intraarterial DSA, a stenosis was found in 31 of 101 arteries. On the basis of findings at 3D phase-contrast MR angiography, the presence of any degree of stenosis was correctly depicted in 29 of 31 cases and the absence of stenosis was correctly depicted in 66 of 70 cases (accuracy, 94%; sensitivity, 94%; negative predictive value, 97%). Overall accuracy was 97% for correct depiction of severe renal artery stenosis (> 50%). 3D phase-contrast MR angiography with a phased-array multicoil was an accurate noninvasive screening technique in patients with suspected renal artery stenosis.

Comparison of three-dimensional phase-contrast magnetic resonance angiography with three-dimensional time-of-flight magnetic resonance angiography in cerebral aneurysms

Magnetic resonance angiography (MRA) can be divided into two types: namely, the phase-contrast (PC) method and the time-of-flight (TOF) method. The purpose of this study is to determine which method is better suited to demonstrate cerebral aneurysms. In a total of 27 cerebral aneurysms confirmed by cerebral angiography, both three-dimensional (3-D) PC and 3-D TOF methods were performed, and the corresponding findings were compared with conventional cerebral angiographic findings. Aneurysm visualization was grouped into three categories: “good” when clearly distinguishable, “fair” if distinguishable when reconstructed, and “poor” if completely undistinguishable. All MRAs were independently interpreted by two neurosurgeons in our institute. Sensitivity was 92.6% when MRA was performed with the TOF method, whereas it was 70.4% when performed with the PC method. In conclusion, the TOF method was more useful for demonstrating the aneurysms than the PC method due to its higher spatial resolution and shorter imaging time.

The anatomy of the posterior communicating artery as a risk factor for ischemic cerebral infarction.

After the occlusion of an internal carotid artery the principal source of collateral flow is through the arteries of the circle of Willis, but the size and patency of these arteries are quite variable. Study of the anatomy of the collateral pathways in patients with internal-carotid-artery occlusion with or without infarction in the watershed area of the deep white matter may identify patterns that afford protection from ischemic infarction. Using conventional magnetic resonance imaging and three-dimensional phase-contrast magnetic resonance angiography, we evaluated 29 consecutive patients (32 hemispheres at risk) with angiographically proved occlusion of the internal carotid artery. Four collateral pathways to the occluded vessel were evaluated: the proximal segment of the anterior cerebral artery, the posterior communicating artery, the ophthalmic artery, and leptomeningeal collateral vessels from the posterior cerebral artery. Only features of the ipsilateral posterior communicating artery were related to the risk of watershed infarction. The presence of posterior communicating arteries measuring at least 1 mm in diameter was associated with the absence of watershed infarction (13 hemispheres, no infarcts; P < 0.001). Conversely, there were 4 watershed infarcts in the 6 hemispheres with posterior communicating arteries measuring less than 1 mm in diameter and 10 infarcts in the 13 hemispheres with no detectable flow in the ipsilateral posterior communicating artery. A small (< 1 mm in diameter) or absent ipsilateral posterior communicating artery is a risk factor for ischemic cerebral infarction in patients with internal-carotid-artery occlusion.