Atherosclerosis imaging using 3D black blood TSE SPACE vs 2D TSE

Application and interpretation of vessel wall magnetic resonance imaging for intracranial atherosclerosis: a narrative review

Background and Objective

Atherosclerosis is a systemic disease that occurs in the arteries, and it is the most important causative factor of ischemic stroke. Vessel wall magnetic resonance imaging (VWMRI) is one of the best non-invasive methods for displaying the vascular features of intracranial atherosclerosis. The main clinical applications of this technique include the exploration of the pathogenesis of intracranial atherosclerotic lesions, follow-up monitoring, and treatment prognosis judgment. As the demand for intracranial VWMRI increases in clinical practice, radiologists should be aware of the selection of imaging parameters and how they affect image quality, clinical indications, evaluation methods, and limitations in interpreting these images. Therefore, this review focused on describing how to perform and interpret VWMRI of intracranial atherosclerotic lesions.

Methods

We searched the studies on the application of VWMRI in the PubMed database from January 1, 2000 to March 31, 2022, and focused on the analysis of related studies on VWMRI in atherosclerotic lesions, including technical application, expert consensus, imaging characteristics, and the clinical significance of intracranial atherosclerotic lesions.

Key Content and Findings

We reviewed and summarized recent advances in the clinical application of VWMRI in atherosclerotic diseases. Currently accepted principles and expert consensus recommendations for intracranial VWMRI include high spatial resolution, multiplanar two and three-dimensional imaging, multiple tissue-weighted sequences, and blood and cerebrospinal fluid suppression. Understanding the characteristics of VWMRI of normal intracranial arteries is the basis for interpreting VWMRI of atherosclerotic lesions. Evaluating VWMRI imaging features of intracranial atherosclerotic lesions includes plaque morphological and enhancement characteristics. The evaluation of atherosclerotic plaque stability is the highlight of VWMRI.

Conclusions

VWMRI has a wide range of clinical applications and can address important clinical questions and provide critical information for treatment decisions. VWMRI plays a key role in the comprehensive evaluation and prevention of intracranial atherosclerosis. However, intracranial VWMRI is still unable to obtain in vivo plaque pathological specimens for imaging—pathological comparison is the most significant limitation of this technique. Further technical improvements are expected to reduce acquisition time and may ultimately contribute to a better understanding of the underlying pathology of lesions on VWMRI.

Atherosclerosis inflammation and burden in young adult smokers and vapers measured by PET/MR

BACKGROUND AND AIMS

Electronic cigarette (EC) use is popular among youth, touted as a safer alternative to smoking and promoted as a tool to aid in smoking cessation. EC cardiovascular safety however is not well established. The aim of this study was to examine cardiovascular consequences of EC use by evaluating their effect on the entire atherosclerotic cascade in young adults using noninvasive combined positron emission tomography (PET)/magnetic resonance imaging (MR) and comparing EC use with age matched smokers of traditional cigarettes and nonsmoking controls.

METHODS

Carotid PET/MR was applied to look at vascular inflammation (18-fluorodeoxyglucose (FDG)-PET) and plaque burden (multi-contrast MR of vessel wall) from 60 18-30 year-old subjects (20 electronic cigarette users, 20 traditional smokers and 20 nonsmokers).

RESULTS

Groups were reasonably well balanced in terms of age, gender, demographics, cardiovascular risk and most biomarkers. There were no differences in vascular inflammation as measured by 18-FDG-PET target to background ratios (TBR) between EC users, traditional cigarette smokers and nonsmokers. However, measures of carotid plaque burden - wall area, normalized wall index, and wall thickness - measured from MR were significantly higher in both traditional smokers and EC users than in nonsmokers.

CONCLUSIONS

Young adult EC users, smokers and nonsmokers in our study did not exhibit vascular inflammation as defined by 18-F-FDG-PET TBR max, but smokers and EC users had significantly more carotid plaque burden compared to matched nonsmokers. Results could indicate that vaping does not cause an increase in vascular inflammation as measured by FDG-PET.

High-Resolution Vessel Wall Magnetic Resonance Imaging of the Middle Cerebral Artery: Comparison of 3D CUBE T1-Weighted Sequence with and without Fat Suppression

Background

Fat suppression is an important technique in magnetic resonance imaging (MRI). Comprehensive and quantitative assessment of the influence of fat suppression (FS) on T1-weighted imaging of intracranial vessel wall imaging is needed. In this study, we compared the three-dimensional (3D) variable-flip-angle turbo-spin-echo (CUBE) T1-weighted sequence with and without FS to investigate the differences between the 2 sequences in imaging of the middle cerebral artery (MCA) vessel walls.

Material/Methods

A 3D CUBE T1-weighted sequence with and without FS by 3.0T MRI was used to obtain intracranial vessel wall images of 105 MCA stenosis patients. The image signal intensity, signal-to-noise ratio, and contrast-to-noise ratio were calculated and compared. Two observers evaluated the image quality of the 2 sequences twice, and interobserver and intraobserver consistency were determined. Differences between the 2 sequences in the area of lumen and plaque were compared.

Results

The signal intensity, signal-to-noise ratio, and contrast-to-noise ratio of the 3D CUBE T1-weighted sequence without FS were higher, whereas the noise level was lower. In terms of subjective scores, the 3D CUBE T1-weighted sequence without FS performed better. No significant difference was observed in the measurement of the vascular lumen area between the 2 sequences, although there were statistically significant differences in the measurement of plaque area (i.e., the measurement obtained with 3D CUBE T1-weighted sequence without FS was larger).

Conclusions

3D CUBE T1-weighted sequence without FS performed better for MCA vessel walls imaging than 3D CUBE T1-weighted sequence with FS.

Imaging plaque inflammation in asymptomatic cocaine addicted individuals with simultaneous positron emission tomography/magnetic resonance imaging

BACKGROUND

Chronic cocaine use is associated with stroke, coronary artery disease and myocardial infarction, resulting in severe impairments or sudden mortality. In the absence of clear cardiovascular symptoms, individuals with cocaine use disorder (iCUD) seeking addiction treatment receive mostly psychotherapy and psychiatric pharmacotherapy, with no attention to vascular disease (i.e., atherosclerosis). Little is known about the pre-clinical signs of cardiovascular risk in iCUD and early signs of vascular disease are undetected in this underserved population.

AIM

To assess inflammation, plaque burden and plaque composition in iCUD aiming to detect markers of atherosclerosis and vascular disease.

METHODS

The bilateral carotid arteries were imaged with positron emission tomography/magnetic resonance imaging (PET/MRI) in iCUD asymptomatic for cardiovascular disease, healthy controls, and individuals with cardiovascular risk. PET with 18F-fluorodeoxyglucose (¹⁸F-FDG) evaluated vascular inflammation and 3-D dark-blood MRI assessed plaque burden including wall area and thickness. Drug use and severity of addiction were assessed with standardized instruments.

RESULTS

The majority of iCUD and controls had carotid FDG-PET signal greater than 1.6 but lower than 3, indicating the presence of mild to moderate inflammation. However, the MRI measure of wall structure was thicker in iCUD as compared to the controls and cardiovascular risk group, indicating greater carotid plaque burden. iCUD had larger wall area as compared to the healthy controls but not as compared to the cardiovascular risk group, indicating structural wall similarities between the non-control study groups. In iCUD, wall area correlated with greater cocaine withdrawal and craving.

CONCLUSION

These preliminary results show markers of carotid artery disease burden in cardiovascular disease-asymptomatic iCUD. Broader trials are warranted to develop protocols for early detection of cardiovascular risk and preventive intervention in iCUD.

Feasibility of High-Resolution 3-Dimensional Sampling Perfection with Application-Optimized Contrast Using Different Flip Angle Evolution Imaging for the Preoperative Detection of Parasinus Meningioma: A Pilot Study Compared with Contrast-Enhanced Magnetic Resonance Venography

OBJECTIVES

To prospectively evaluate the diagnostic value of 3.0 Tesla magnetic resonance 3-dimensional sampling perfection with application-optimized contrast using different flip angle evolution (3D-SPACE) in the detection of sinus wall invasion and sinus patency in parasinus meningiomas.

METHODS

In this study, 28 patients with suspected meningiomas adjacent to the venous sinus underwent conventional magnetic resonance imaging, contrast-enhanced magnetic resonance venography, and 3D-SPACE scans. We collected patient charts and surgical reports for demographic details, histologic analysis, and neurologic performance preoperatively and postoperatively. Images obtained by each technique were assessed independently by 2 neurosurgeons for characteristics of sinus infiltration, wall invasion, lumen patency, and collateral veins.

RESULTS

The blood flow signal inside the lumen and collateral veins were depressed and presented as black, contrasting well with the sinus wall on 3D-SPACE imaging. When the curved-planar reconstruction images were combined, it was intuitive and accurate to detect the extent of sinus wall invasion by meningioma and also to detect lumen patency. An intratumoral "false lumen" was shown to maintain the blood flow inside the sinus at a totally invaded lesion. Moreover, collateral veins enveloped in a meningioma with their confluence points of the venous sinus were easily observed on 3D-SPACE images.

CONCLUSION

With an integrative presentation of parasinus meningioma, wall invasion, lumen patency, and collateral veins, high-resolution 3D-SPACE imaging provides a reliable technique to accurately assess venous sinus invasion preoperatively.

Vascular disease in cocaine addiction

Cocaine, a powerful vasoconstrictor, induces immune responses including cytokine elevations. Chronic cocaine use is associated with functional brain impairments potentially mediated by vascular pathology. Although the Crack-Cocaine epidemic has declined, its vascular consequences are increasingly becoming evident among individuals with cocaine use disorder of that period, now aging. Paradoxically, during the period when prevention efforts could make a difference, this population receives psychosocial treatment at best. We review major postmortem and in vitro studies documenting cocaine-induced vascular toxicity. PubMed and Academic Search Complete were used with relevant terms. Findings consist of the major mechanisms of cocaine-induced vasoconstriction, endothelial dysfunction, and accelerated atherosclerosis, emphasizing acute, chronic, and secondary effects of cocaine. The etiology underlying cocaine's acute and chronic vascular effects is multifactorial, spanning hypertension, impaired homeostasis and platelet function, thrombosis, thromboembolism, and alterations in blood flow. Early detection of vascular disease in cocaine addiction by multimodality imaging is discussed. Treatment may be similar to indications in patients with traditional risk-factors, with few exceptions such as enhanced supportive care and use of benzodiazepines and phentolamine for sedation, and avoiding β-blockers. Given the vascular toxicity cocaine induces, further compounded by smoking and alcohol comorbidity, and interacting with aging of the crack generation, there is a public health imperative to identify pre-symptomatic markers of vascular impairments in cocaine addiction and employ preventive treatment to reduce silent disease progression.

Imaging of the high-risk carotid plaque: magnetic resonance imaging

The emergence of the concept of high-risk atherosclerotic plaque has led to considerable interest in noninvasive imaging techniques to identify high-risk features before clinical sequelae. For plaques in the carotid arteries, magnetic resonance imaging has undergone considerable histologic validation to link imaging features to indicators of plaque instability, including plaque burden, intraplaque hemorrhage, fibrous cap disruption, lipid rich necrotic core, and calcification. Recently introduced imaging technologies, especially those focused on three-dimensional imaging sequences, are now poised for integration into the clinical workup of patients with suspected carotid atherosclerosis. The purpose of this article is to review the carotid plaque magnetic resonance imaging techniques that are most ready for integration into the clinic.

Feasibility of imaging superficial palmar arch using micro-ultrasound, 7T and 3T magnetic resonance imaging

AIM

To demonstrate feasibility of vessel wall imaging of the superficial palmar arch using high frequency micro-ultrasound, 7T and 3T magnetic resonance imaging (MRI).

METHODS

Four subjects (ages 22-50 years) were scanned on a micro-ultrasound system with a 45-MHz transducer (Vevo 2100, VisualSonics). Subjects’ hands were then imaged on a 3T clinical MR scanner (Siemens Biograph MMR) using an 8-channel special purpose phased array carotid coil. Lastly, subjects’ hands were imaged on a 7T clinical MR scanner (Siemens Magnetom 7T Whole Body Scanner) using a custom built 8-channel transmit receive carotid coil. All three imaging modalities were subjectively analyzed for image quality and visualization of the vessel wall.

RESULTS

Results of this very preliminary study indicated that vessel wall imaging of the superficial palmar arch was feasible with a whole body 7T and 3T MRI in comparison with micro-ultrasound. Subjective analysis of image quality (1-5 scale, 1: poorest, 5: best) from B mode, ultrasound, 3T SPACE MRI and 7T SPACE MRI indicated that the image quality obtained at 7T was superior to both 3T MRI and micro-ultrasound. The 3D SPACE sequence at both 7T and 3T MRI with isotropic voxels allowed for multi-planar reformatting of images and allowed for less operator dependent results as compared to high frequency micro-ultrasound imaging. Although quantitative analysis revealed that there was no significant difference between the three methods, the 7T Tesla trended to have better visibility of the vessel and its wall.

CONCLUSION

Imaging of smaller arteries at the 7T is feasible for evaluating atherosclerosis burden and may be of clinical relevance in multiple diseases.

Reference Values for Cardiac and Aortic Magnetic Resonance Imaging in Healthy, Young Caucasian Adults

Background

Reference values for morphological and functional parameters of the cardiovascular system in early life are relevant since they may help to identify young adults who fall outside the physiological range of arterial and cardiac ageing. This study provides age and sex specific reference values for aortic wall characteristics, cardiac function parameters and aortic pulse wave velocity (PWV) in a population-based sample of healthy, young adults using magnetic resonance (MR) imaging.

Materials and Methods

In 131 randomly selected healthy, young adults aged between 25 and 35 years (mean age 31.8 years, 63 men) of the general-population based Atherosclerosis-Monitoring-and-Biomarker-measurements-In-The-YOuNg (AMBITYON) study, descending thoracic aortic dimensions and wall thickness, thoracic aortic PWV and cardiac function parameters were measured using a 3.0T MR-system. Age and sex specific reference values were generated using dedicated software. Differences in reference values between two age groups (25–30 and 30–35 years) and both sexes were tested.

Results

Aortic diameters and areas were higher in the older age group (all p<0.007). Moreover, aortic dimensions, left ventricular mass, left and right ventricular volumes and cardiac output were lower in women than in men (all p<0.001). For mean and maximum aortic wall thickness, left and right ejection fraction and aortic PWV we did not observe a significant age or sex effect.

Conclusion

This study provides age and sex specific reference values for cardiovascular MR parameters in healthy, young Caucasian adults. These may aid in MR guided pre-clinical identification of young adults who fall outside the physiological range of arterial and cardiac ageing.

The association between carotid intraplaque hemorrhage and outcomes of carotid stenting: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

The purpose of this systematic review and meta-analysis was to determine whether carotid stenting patients with intraplaque hemorrhage (IPH) identified on preoperative MRI were more likely to suffer perioperative ischemic complications compared with patients without IPH.

METHODS

We conducted a comprehensive literature search of studies published between January 1, 2005 and December 31, 2015 reporting perioperative outcomes of carotid stenting among patients with and without IPH on hemorrhage sensitive carotid MRI sequences. Clinical outcomes included perioperative (≤30 days post-stenting) minor stroke, major stroke, death, and a composite outcome combining stroke, death, and myocardial infarction (MI). We also compared the rate of silent ischemia on diffusion weighted imaging (DWI) between groups. Statistical analysis was performed using a random effects meta-analysis.

RESULTS

9 studies with 491 unique patients (198 in the IPH group and 293 in the non-IPH group) were included. The rate of the composite outcome of any stroke, death, or MI within 30 days was 8.1% (13/160) in the IPH group and 2.1% (5/239) in the non-IPH group (OR=4.45, 95% CI 1.61 to 12.30, p<0.01). There were no significant differences between groups in the rates of minor stroke, major stroke, or death when considered individually. The rate of postoperative infarct on DWI was 49.7% (75/161) for the IPH group and 33.6% (81/241) for the non-IPH group (OR=2.01, 95% CI 1.31 to 3.09, p<0.01).

CONCLUSIONS

Our systematic review and meta-analysis demonstrated that patients with IPH on pre-carotid stenting MRI had higher rates of silent ischemia as well as of a composite outcome of perioperative stroke, death, and MI compared with those without IPH.

3D black blood VISTA vessel wall cardiovascular magnetic resonance of the thoracic aorta wall in young, healthy adults: reproducibility and implications for efficacy trial sample sizes: a cross-sectional study

BACKGROUND

Pre-clinical detection of atherosclerosis enables personalized preventive strategies in asymptomatic individuals. Cardiovascular magnetic resonance (CMR) has evolved as an attractive imaging modality for studying atherosclerosis in vivo. Yet, the majority of aortic CMR studies and proposed sequences to date have been performed at 1.5 tesla using 2D BB techniques and a slice thickness of 4-5 mm. Here, we evaluate for the first time the reproducibility of an isotropic, T1-weighted, three-dimensional, black-blood, CMR VISTA sequence (3D-T1-BB-VISTA) for quantification of aortic wall characteristics in healthy, young adults.

METHODS

In 20 healthy, young adults (10 males, mean age 31.3 years) of the AMBITYON cohort study the descending thoracic aorta was imaged with a 3.0 T MR system using the 3D-T1-BB-VISTA sequence. The inter-scan, inter-rater and intra-rater reproducibility of aortic lumen, total vessel and wall area and mean and maximum wall thickness was evaluated using Bland-Altman analyses and Intraclass Correlation Coefficients (ICC). Based on these findings, sample sizes for detecting differences in aortic wall characteristics between groups were calculated.

RESULTS

For each studied parameter, the inter-scan, inter-rater and intra-rater reproducibility was excellent as indicated by narrow limits of agreement and high ICCs (ranging from 0.76 to 0.99). Sample sizes required to detect a 5% difference in aortic wall characteristics between two groups were 203, 126, 136, 68 and 153 per group for lumen area, total vessel area and vessel wall area and for mean and maximum vessel wall thickness, respectively.

CONCLUSION

The 3D-T1-BB-VISTA sequence provides excellent reproducibility for quantification of aortic wall characteristics and can detect small differences between groups with reasonable sample sizes. Hence, it may be a valuable tool for assessment of the subtle vascular wall changes of early atherosclerosis in asymptomatic populations.

Assessment of Liliequist membrane by 3D-SPACE technique at 3 T

INTRODUCTION

Liliequist membrane (LM) is the most important anatomic structure for the success of endoscopic third ventriculostomy (ETV). Identification of this membrane is difficult with conventional MRI techniques. The purpose of this retrospective study is to determine the impact of three-dimensional sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) sequence with variant flip-angle mode (VFAM) in the assessment of LM at 3-T MRI devices.

METHODS

3D-SPACE with VFAM images were obtained in 445 patients. LM visibility and integrity were scored as 0 (good), 1 (moderate), and 2 (poor) on these images for each parts (sellar, diencephalic, and mesencephalic) and overall of the membrane.

RESULTS

According to the LM overall integrity scores, 11 % (48 cases) of the patients had perforated membrane. According to subsegmental integrity scores, sellar part was completely intact in 63 % of patients, diencephalic segment was completely intact in 60 % of the patients, and mesencephalic segment was completely intact in 95 % of the patients. Visibility scores of the third ventricle inferior wall were significantly higher in the patients with intact LM (p = 0.001). There was not any statistically significant relationship between LM pattern and overall integrity (p = 0.352). LM attachment sites could be detected easier in the patients who had better visibility of third ventricle inferior wall or intact LM (p < 0.001 for both).

CONCLUSION

3D-SPACE technique is a useful alternative for the evaluation of morphology, integrity, individual variations, topographic relationships, and visibility of LM since it has some advantages including lower SAR values, fewer artifacts, and high-resolution images.

Isotropic 3D black blood MRI of abdominal aortic aneurysm wall and intraluminal thrombus

INTRODUCTION

The aortic wall and intraluminal thrombus (ILT) have been increasingly studied as potential markers of progressive disease with abdominal aortic aneurysms (AAAs). Our goal was to develop a high resolution, 3D black blood MR technique for AAA wall and ILT imaging within a clinically acceptable scan time.

METHODS

Twenty two patients with AAAs (maximal diameter 4.3±1.0cm), along with five healthy volunteers, were imaged at 3T with a 3D T1-weighted fast-spin-echo sequence using variable flip angle trains (SPACE) with a preparation pulse (DANTE) for suppressing blood signal. Volunteers and ten patients were also scanned with SPACE alone for comparison purposes. The signal to noise ratio (SNR) and the aortic wall/ILT to lumen contrast to noise ratio (CNR) were measured. Qualitative image scores (1-4 scale) assessing the inner lumen and outer wall boundaries of AAA were performed by two blinded reviewers. In patients with ILT, the ratio of ILT signal intensity (ILTSI) over psoas muscle SI (MuscleSI) was calculated, and the signal heterogeneity of ILT was quantified as standard deviation (SD) over the mean.

RESULTS

All subjects were imaged successfully with an average scan time of 7.8±0.7minutes. The DANTE preparation pulse for blood suppression substantially reduced flow artifacts in SPACE with lower lumen SNR (8.8 vs. 21.4, p<0.001) and improved the wall/ILT to lumen CNR (9.9 vs. 6.3, p<0.001) in patients. Qualitative assessment showed improved visualization of lumen boundaries (73% higher scores on average, p=0.01) and comparable visualization of outer wall boundary (p>0.05). ILT was present in ten patients, with relatively high signal and a wide SD (average ILTSI/MuscleSI 1.42±0.48 (range 0.75-2.11)) and with SD/mean of 27.7%±6.6% (range 19.6%-39.4%).

CONCLUSION

High resolution, 3D black blood MRI of AAAs can be achieved in a clinical accepted scan time with reduction of flow artifacts using the DANTE preparation pulse. Signal characteristics of ILT can be quantified and may be used for improved patient-specific risk stratification.

Utility of a High-Resolution 3D MRI Sequence (3D-SPACE) for Evaluation of Congenital Heart Disease

The purpose of this study was to evaluate the role of a high-resolution 3D dark-blood turbo spin echo sequence with variable flip angles (3D-SPACE) in evaluation of congenital heart disease. SPACE sequence was performed in 20 patients (mean age, 17.6 ± 12.6 years, range 9 months-57 years, M: 13) with either unrepaired (N = 3) or post-repair (n = 17) congenital heart disease. All scans were performed on 1.5 T Aera scanners (Siemens). Two separate observers with expertise in cardiovascular imaging scored the quality of the images for blood suppression and definition of key anatomical structures in a blinded fashion using a 5 grade scoring system. Mean of average overall quality scores for two observers was 4 ± 0.62. All overall quality scores were greater than 3. None of the studies were deemed nondiagnostic. Mean length of the SPACE acquisition time was 12.7 min (4-21 min). There was no significant correlation between image quality and duration of scans. Lack of blood suppression was the limiting factor in image quality with the most common place being ascending aorta in nine patients. However, overall blood suppression score was very good with score of 3.9 ± 0.43. There was very good overall agreement between observers in rating the image quality (85.6 % agreement, kappa 0.5, standard error 0.04, p < 0.0001). The 3D-SPACE dark-blood sequence with near-isotropic spatial resolution coupled with respiratory and cardiac gating can be feasibly performed in all age groups with diagnostic image quality in all cases in this study.

Increasing the Spatial Resolution of 3T Carotid MRI Has No Beneficial Effect for Plaque Component Measurement Reproducibility

Purpose

Different in-plane resolutions have been used for carotid 3T MRI. We compared the reproducibility, as well as the within- and between reader variability of high and routinely used spatial resolution in scans of patients with atherosclerotic carotid artery disease. Since no consensus exists about the optimal segmentation method, we analysed all imaging data using two different segmentation methods.

Materials and Methods

In 31 patient with carotid atherosclerosis a high (0.25 × 0.25 mm²; HR) and routinely used (0.50 × 0.50 mm²; LR) spatial resolution carotid MRI scan were performed within one month. A fully blinded closed and a simultaneously open segmentation were used to quantify the lipid rich necrotic core (LRNC), calcified and loose matrix (LM) plaque area and the fibrous cap (FC) thickness.

Results

No significant differences were observed between scan-rescan reproducibility for HR versus LR measurements, nor did we find any significant difference between the within-reader and between-reader reproducibility. The same applies for differences between the open and closed reads. All intraclass correlation coefficients between scans and rescans for the LRNC, calcified and LM plaque area, as well as the FC thickness measurements with the open segmentation method were excellent (all above 0.75).

Conclusions

Increasing the spatial resolution at the expense of the contrast-to-noise ratio does not improve carotid plaque component scan-rescan reproducibility in patients with atherosclerotic carotid disease, nor does using a different segmentation method.

Fast 3D isotropic imaging of the aortic vessel wall by application of 2D spatially selective excitation and a new way of inversion recovery for black blood imaging

PURPOSE

Aortic vessel wall imaging requires large coverage and a high spatial resolution, which makes it prohibitively time-consuming for clinical use. This work explores the feasibility of imaging the descending aorta in acceptable scan time, using two-dimensional (2D) spatially selective excitation and a new way of inversion recovery for black blood imaging.

METHODS

The excitation pattern and field of view in a 3D gradient echo sequence are reduced in two dimensions, following the aorta's anisotropic geometry. Black blood contrast is obtained by partially inverting the blood's magnetization in the heart at the start of the cardiac cycle. Imaging is delayed until the inverted blood has filled the desired part of the aorta. The flip angle and delay are determined such that the blood signal is nulled upon arrival in the aorta.

RESULTS

Experiments on eight volunteers showed that the descending aortic vessel wall could be imaged over more than 15 cm at a maximal resolution of 1.5 × 1.5 × 1.5 mm(3) in less than 5 min minimal scan time.

CONCLUSION

This feasibility study demonstrates that time-efficient isotropic imaging of the descending aorta is possible by using 2D spatially selective excitation for motion artifact reduction and a new way of inversion recovery for black blood imaging.