Sample Size Calculation for Clinical Trials Using Magnetic Resonance Imaging for the Quantitative Assessment of Carotid Atherosclerosis

Saam, Tobias; Kerwin, William S.; Chu, Baocheng; Cai, Jianming; Kampschulte, Annette; Hatsukami, Thomas S.; Zhao, Xue Qiao; Polissar, Nayak L.; Neradilek, Blažej; Yarnykh, Vasily L.; Flemming, Kelly D.; Huston, John; Insull, William; Morrisett, Joel D.; Rand, Scott D.; DeMarco, Kevin J.; Yuan, Chun

doi:10.1080/10976640500287703

Cited by 110 publications

(106 citation statements)

References 25 publications

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“…A number of studies have shown that MRI can accurately quantify vessel wall dimensions of atherosclerotic arteries in vivo (4), with measurement errors ranging from 4-6% for the lumen and wall, and 3.3% for total vessel area measurement (5,6). Thus, MRI provides a promising tool to study plaque progression and the remodeling process of atherosclerosis in humans in a non-invasive fashion.…”

Section: Introductionmentioning

confidence: 99%

Predictors of carotid atherosclerotic plaque progression as measured by noninvasive magnetic resonance imaging

et al. 2007

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The purpose of this in vivo MRI study was to quantify changes in atherosclerotic plaque morphology prospectively and to identify factors that may alter the rate of progression in plaque burden. Sixtyeight asymptomatic subjects with ≥50% stenosis, underwent serial carotid MRI examinations over an 18 month period. Clinical risk factors for atherosclerosis, and medications were documented prospectively. The wall and total vessel areas, matched across time-points, were measured from cross-sectional images. The normalized wall index (NWI = wall area / total vessel area), as a marker of disease severity, was documented at baseline and at 18 months. Multiple regression analysis was used to correlate risk factors and morphological features of the plaque with the rate of progression/ regression.On average, the wall area increased by 2.2%/year (P=0.001). Multiple regression analysis demonstrated that statin therapy (P=0.01) and a normalized wall index >0.64 (P=0.001) were associated with a significantly reduced rate of progression in mean wall area. All other documented risk factors were not significantly associated with changes in wall area. Findings from this study suggest that increased normalized wall index and the use of statin therapy are associated with reduced Address for Correspondence: Thomas S. Hatsukami, MD VA Puget Sound Health Care System Surgery and Perioperative Care (112)

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Section: Introductionmentioning

confidence: 99%

Predictors of carotid atherosclerotic plaque progression as measured by noninvasive magnetic resonance imaging

et al. 2007

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“…This suggests that the carotid wall volume might be a more reliable parameter of atherosclerosis burden when comparing across MR techniques. However, in a follow-up study using the 2D technique only, Mani et al found better reproducibility for W/OW than for wall volume, and W/OW has other advantages in clinical studies, such as the ability to meaningfully compare scans with differing numbers of slices (27).…”

Section: Discussionmentioning

confidence: 99%

“…From these models, lumen volume, wall volume, and total vessel volume were derived for the imaged volume (40 mm of longitudinal coverage). The total wall volume was also expressed as a percentage of the total vessel volume (wall/outer wall or W/OW ratio), as previously described (27).…”

Section: Image Analysismentioning

confidence: 99%

Comparison of 2D and multislab 3D magnetic resonance techniques for measuring carotid wall volumes

Keenan

Grasso

Locca

et al. 2008

Magnetic Resonance Imaging

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Purpose: To compare a multislab three-dimensional volume-selective fast spin-echo (FSE) magnetic resonance (MR) sequence with a routine two-dimensional FSE sequence for quantification of carotid wall volume. Materials and Methods:One hundred normal subjects (50 men, mean age 44.6 years) underwent carotid vessel wall MR using 2D and 3D techniques. Carotid artery total vessel volume, lumen volume, wall volume, and wall/outer wall (W/OW) ratio were measured over 20 contiguous slices. Two-(2D) and three-dimensional (3D) results were compared. Results:The mean difference between 2D and 3D datasets (as a percentage of the mean absolute value) was 1.7% for vessel volume, 4.9% for lumen volume, 4.7% for wall volume, and 5.8% for W/OW ratio. There was good correlation between 2D and 3D models for total vessel volume (R 2 ϭ 0.93, P Ͻ 0.001), lumen area (R 2 ϭ 0.92, P Ͻ 0.001), and wall volume (R 2 ϭ 0.77, P Ͻ 0.001). The correlation for the W/OW ratio was weaker (R 2 ϭ 0.30; P Ͻ 0.001). The signalto-noise ratio (SNR) for the 3D technique was 2.1-fold greater than for the 2D technique (P Ͻ 0.001). When using the 3D sequence, scan time was reduced by 63%. Conclusion:Multislab volume selective 3D FSE carotid arterial wall imaging performs similarly to a conventional 2D technique, but with over twice the SNR and substantially reduced scan time. CARDIOVASCULAR MAGNETIC RESONANCE (MR) is a good technique for assessing atherosclerosis in the carotid artery, with much development over the last 15 years in plaque characterization and assessment of the structure and function of the arterial wall (1-6). Quantitative carotid wall imaging typically requires a stack of two-dimensional (2D) images, which can be contoured and analyzed. Acquisition protocols vary, but scan times of the order of 1 hour are common so as to cover an adequate length of the carotid artery with contiguous slices. Long scan times limit the applicability of the technique. As scan times increase, patient comfort and acceptability decrease, and patient movement increases, leading to image degradation from movement artifact (7). Long scan times also limit the feasibility of using carotid MR in large clinical studies. To reduce the scan time, a localized three-dimensional (3D) fast spinecho (FSE) sequence for carotid artery imaging has been developed and validated (8 -13).In conventional 3D imaging, rather than a single slice, a slab of tissue is excited by the radiofrequency (RF) pulse. Spatial encoding is performed in 3D by using additional phase encoding in the direction perpendicular to the selected slab, along with an additional dimension of Fourier transformation for image reconstruction (14). The 3D images have an inherently higher signal-to-noise ratio (SNR), so fewer cardiac cycles are needed than with 2D to produce similar image quality at the same voxel size (8,15). In theory, the SNR advantage of 3D over 2D is ͌N, where N is the number of 3D phase-encode steps in the partition direction. Using perpendicular 90°and 180°selection gradients, the 3D slab can ...

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“…In this study, the PWV was used to measure the plaque burden because it can fully exploit the 3D data acquisition inherent in carotid MR imaging and is the most reproducible parameter to evaluate plaque burden among all the morphologic measurements by MR imaging. 23,24 Similarly, a previous study has shown that carotid plaque burden as measured by sonographic intima-media thickness is associated with recurrence of cardiovascular events including stroke. 25 Additionally, we found that there was no significant difference in the prevalence of carotid lumen stenosis of Ͼ50% between the 2 patient groups, indicating that the degree of arterial stenosis alone is a relatively poor predictor of recurrent neurologic events.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Carotid Atherosclerotic Plaque Characteristics by High-Resolution Black-Blood MR Imaging between Patients with First-Time and Recurrent Acute Ischemic Stroke

Liu

Zhao

Cao

et al. 2012

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: It has been shown that patients with a first ischemic stroke are at high risk of developing recurrent stroke due to carotid atherosclerotic plaque rupture. However, no one has defined the difference in plaques between initial and recurrent stroke. This study sought to investigate the characteristics of carotid plaque between patients with first-time and recurrent acute ischemic stroke by using MR imaging.

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Sample Size Calculation for Clinical Trials Using Magnetic Resonance Imaging for the Quantitative Assessment of Carotid Atherosclerosis

Abstract: In vivo MRI is capable of quantifying plaque volume and plaque composition, such as %lipid-rich/necrotic core and %calcification, in the clinical setting of a multi-center trial with low inter-scan variability. This study provides the basis for sample size calculation of future MRI trials.

Cited by 110 publications

References 25 publications

Predictors of carotid atherosclerotic plaque progression as measured by noninvasive magnetic resonance imaging

Predictors of carotid atherosclerotic plaque progression as measured by noninvasive magnetic resonance imaging

Comparison of 2D and multislab 3D magnetic resonance techniques for measuring carotid wall volumes

Comparison of Carotid Atherosclerotic Plaque Characteristics by High-Resolution Black-Blood MR Imaging between Patients with First-Time and Recurrent Acute Ischemic Stroke

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