Comparison of X-ray fluoroscopy and interventional magnetic resonance imaging for the assessment of coronary artery stenoses in swine - PubMed (original) (raw)

Comparative Study

Comparison of X-ray fluoroscopy and interventional magnetic resonance imaging for the assessment of coronary artery stenoses in swine

Jordin D Green et al. Magn Reson Med. 2005 Nov.

Abstract

The accuracy of a two-step interventional MRI protocol to quantify coronary artery disease was compared to the clinical gold standard, X-ray angiography. Studies were conducted in nine swine with a surgically induced stenosis in the proximal left circumflex coronary artery. The two-step protocol consisted of catheter-directed magnetic resonance angiography (MRA), which was first used to localize the stenosis, followed by MRI cross-sectional images to quantify the degree of stenosis without the use of contrast agent. Line signal intensity profiles were drawn across the vessel diameter at the stenosis site and proximal to the stenosis for each data set to measure percentage stenosis for each animal. Catheter-directed MRA successfully detected eight of nine stenoses. Cross-sectional MRI accurately quantified each stenosis, with strong agreement to the measurements made using X-ray fluoroscopy (intraclass correlation coefficient = 0.955; P < 0.05). This study demonstrates that in the future interventional MRI may be an alternative to X-ray angiography for the detection and quantification of coronary artery disease.

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Figures

Figure 1

SSFP with a saturation pulse-four inversion pulse magnetization preparation. After detection of the R-wave, a 90° saturation pulse is applied, followed by saturation time TS. This is followed by a train of 180° inversion pulses, separated by delay times TI1, TI2, TI3, and TI4. Linear flip angle (LFA) preparation pulses are applied at the end of TI4. Note that TS, TI1-TI4 are not necessarily equal.

Figure 2

Catheter-directed coronary angiography of a swine with a surgically created stenosis in the proximal LCX (arrow) near the aorta (Ao). a) X-ray fluoroscopy. b) Subtracted MIP of 3D catheter-directed MRA. c) Ex vivo digital photo of the heart of the same animal after the experiment, with the LCX and ameroid constrictor exposed. Also included are higher spatial resolution MRI cross-sections (dashed arrows) d) proximal to the stenosed segment and e) at the stenosed segment, obtained without the administration of contrast agent. In this example, the percent stenosis was measured to be 75% using X-ray angiography, 42% using catheter-directed MRA, and 65% using the MRI cross-sections.

Figure 3

Percent stenosis measured using MRA (▪) and X-ray fluoroscopy (•) for the 8 swine where catheter-directed MRA was successful. The absolute difference between X-ray angiography and MRA measurements ranged from a maximum of 34% to a minimum of 3%, with a mean absolute difference of 19%. Under MRA, all eight animals had an estimated stenosis greater than 30% and were further investigated using MRI cross-sections.

Figure 4

a) MIP of a 3D catheter-directed MRA data set showing the LAD and LCX. MRA was used to plan cross-sectional MRI in arterial segments proximal to (solid line) and at (dashed line) the stenosis. b) X-ray angiography of the same animal in a similar orientation as a). c) MRI cross-section of the proximal segment, corresponding to the solid line in a). d) MRI cross-section of the diseased segment, corresponding to the dashed line in a). In this example, the stenosis was measured to be 65% using X-ray angiography, 30% using catheter-directed MRA, and 62% using MRI cross-sections.

Figure 5

Correlation between the percent stenosis measured using cross-sectional MRI vs. percent stenosis measured using X-ray angiography. Solid line represents the line of identity. ICC was measured to be 0.955 (p < 0.05).

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Comparison of X-ray fluoroscopy and interventional magnetic resonance imaging for the assessment of coronary artery stenoses in swine - PubMed (original) (raw)