In vivo detection of hemorrhage in human atherosclerotic plaques with magnetic resonance imaging

Abstract

Purpose:To investigate the performance of high-resolution T1-weighted (T1w) turbo field echo (TFE) magnetic resonance imaging (MRI) for the identification of the high-risk component intraplaque hemorrhage, which is described in the literature as a troublesome component to detect. Materials and Methods:An MRI scan was performed preoperatively on 11 patients who underwent carotid endarterectomy because of symptomatic carotid disease with a stenosis larger than 70%. A commonly used double inversion recovery (DIR) T1w turbo spin echo (TSE) served as the T1w control for the T1w TFE pulse sequence. The MR images were matched slice by slice with histology, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the MR images were calculated. Additionally, two readers, who were blinded for the histological results, independently assessed the MR slices concerning the presence of intraplaque hemorrhage.Results: More than 80% of the histological proven intraplaque hemorrhage could be detected using the TFE sequence with a high interobserver agreement (Kappa ϭ 0.73). The TFE sequence proved to be superior to the TSE sequence concerning SNR and CNR, but also in the qualitative detection of intraplaque hemorrhage. The false positive TFE results contained fibrous tissue and were all located outside the main plaque area. Conclusion:The present study shows that in vivo highresolution T1w TFE MRI can identify the high-risk component intraplaque hemorrhage with a high detection rate in patients with symptomatic carotid disease. Larger clinical trials are warranted to investigate whether this technique can identify patients at risk for an ischemic attack.

Intraplaque Hemorrhage and the Plaque Surface in Carotid Atherosclerosis: The Plaque At RISK Study (PARISK)

“…We used the 3D-T1W fat suppresssed spoiled gradient echo or the 2D-T1W inversion recovery turbo field echo MR imaging sequence to detect intraplaque hemorrhage. Bitar et al 25 and Cappendijk et al 26 used sequences like ours and found a good sensitivity, specificity, and interobserver agreement for the detection of intraplaque hemorrhage in both sequences. They also found good agreement between MR imagingdepicted intraplaque hemorrhage and histologic sections.…”

“…20 Based on the good sensitivity and specificity of MDCTA for plaque ulcerations and the good agreement between MR imaging-depicted intraplaque hemorrhage and histology, we therefore conclude that it is legitimate to use imaging techniques such as MDCTA and MR imaging to study the relationship between intraplaque hemorrhage and the disruption of the plaque surface. 25,26 Moreover, the use of MDCTA and MR imaging provides the opportunity to investigate the relationship in a specific category of patients-that is, those with a mild-to-moderate carotid artery stenosis, patients who are treated medically and thus have no available histology. The final limitation of our study is that it is cross-sectional.…”

Imaging of the Carotid Artery Vulnerable Plaque

“…MR can age IPH surface (white open arrows) for CT and US respectively. e, f Smooth plaque ulcers (white arrowheads) for CT and US respectively [48][49][50] by distinguishing different patterns on T1-w, T2-w, PD, and TOF images. Authors tried to identify IPH using CT and found a strong correlation between very low HU value and IPH [51,52].…”

Carotid Atherosclerotic Calcification Does Not Result in High Signal Intensity in MR Imaging of Intraplaque Hemorrhage

“…3,24 High signal intensity in carotid plaques did not correlate with the presence of calcium seen in the same segments in the corresponding MicroCT images. This could perhaps be explained by our scanning parameters (TE, 3.3 ms; TR, 11.2 ms; flip angle, 15°), which are much shorter than those that Henkelman and Kucharczyk 22 reported as optimal (TE, 29 ms; TR, 30 ms; flip angle, 5°-10°).…”

“…Also, T1 shortening was found to be dependent on hydroxyapatite concentration, with the signal intensity de-creasing as hydroxyapatite concentration increased beyond 30%-40% of the weight of the tissue (because the proton attenuation/T2 effects dominate the T1 shortening effects). Cappendjik et al 24 compared 3D high-resolution GRE and 3D high-resolution FSE sequences for imaging intraplaque hemorrhage. They found that calcification produced some false-positives (high signal intensity) in a very few cases, however, these were seen in FSE and not GRE sequences.…”