Assessment of aortic diameter in Marfan patients: intraindividual comparison of 3D-Dixon and 2D-SSFP magnetic resonance imaging

Assessment of the thoracic aorta after aortic root replacement and/or ascending aortic surgery using 3D relaxation-enhanced angiography without contrast and triggering

Objective

Relaxation-Enhanced Angiography without Contrast and Triggering (REACT) is a novel 3D isotropic flow-independent non-contrast-enhanced MRA (non-CE-MRA) and has shown promising results in imaging of the thoracic aorta, primarily in patients without prior aortic surgery. The purpose of this study was to evaluate the performance of REACT after surgery of the aortic root and/or ascending aorta by performing an intraindividual comparison to CE-MRA.

Material and methods

This retrospective single center study included 58 MRI studies of 34 patients [mean age at first examination 45.64 ± 11.13 years, 31 (53.44%) female] after ascending aortic surgery. MRI was performed at 1.5T using REACT (ECG- and respiratory-triggering, Compressed SENSE factor 9, acquired spatial resolution 1.69 × 1.70 × 1.70 mm3) and untriggered 3D CE-MRA. Independently, two radiologists measured maximum and minimum vessel diameters (inner-edge) and evaluated image quality and motion artifacts on 5-point scales (5 = excellent) for the following levels: mid-graft, distal anastomosis, ascending aorta, aortic arch, and descending aorta. Additionally, readers evaluated MRAs for the presence of aortic dissection (AD) and graded the quality of depiction as well as their diagnostic confidence using 5-point scales (5 = excellent).

Results

Vessel diameters were comparable between CE-MRA and REACT (total acquisition time: 05:42 ± 00:38 min) with good to excellent intersequence agreement (ICC = 0.86-0.96). At the distal anastomosis (minimum/maximum, p < .001/p = .002) and at the ascending aorta (minimum/maximum, p = .002/p = .06), CE-MRA yielded slightly larger diameters. Image quality for all levels combined was higher in REACT [median (IQR); 3.6 (3.2-3.93) vs. 3.9 (3.6-4.13), p = .002], with statistically significant differences at mid-graft [3.0 (2.5-3.63) vs. 4.0 (4.0-4.0), p < .001] and ascending aorta [3.25 (3.0-4.0) vs. 4.0 (3.5-4.0), p < .001]. Motion artifacts were more present in CE-MRA at all levels (p < .001). Using CE-MRA as the standard of reference, readers detected all 25 cases of residual AD [Stanford type A: 21 (84.0%); Stanford type B: 4 (16.0%)] in REACT with equal quality of depiction [4.0 (3.0-4.5) vs. 4.0 (3.0-4.0), p = .41] and diagnostic confidence [4.0 (3.0-4.0) vs. 4.0 (3.0-4.0), p = .81) in both sequences.

Conclusions

This study indicates the feasibility of REACT for assessment of the thoracic aorta after ascending aortic surgery and expands its clinical use for gadolinium-free MRA to these patients.

Advances in Cardiovascular Multimodality Imaging in Patients with Marfan Syndrome

Marfan syndrome (MFS) is a genetic disorder affecting connective tissue, often leading to cardiovascular complications such as aortic aneurysms and mitral valve prolapse. Cardiovascular multimodality imaging plays a crucial role in the diagnosis, monitoring, and management of MFS patients. This review explores the advancements in echocardiography, cardiovascular magnetic resonance (CMR), cardiac computed tomography (CCT), and nuclear medicine techniques in MFS. Echocardiography remains the first-line tool, essential for assessing aortic root, mitral valve abnormalities, and cardiac function. CMR provides detailed anatomical and functional assessments without radiation exposure, making it ideal for long-term follow-up. CT offers high-resolution imaging of the aorta, crucial for surgical planning, despite its ionizing radiation. Emerging nuclear medicine techniques, though less common, show promise in evaluating myocardial involvement and inflammatory conditions. This review underscores the importance of a comprehensive imaging approach to improve outcomes and guide interventions in MFS patients. It also introduces novel aspects of multimodality approaches, emphasizing their impact on early detection and management of cardiovascular complications in MFS.

Non-contrast free-breathing 2D CINE compressed SENSE T1-TFE cardiovascular MRI at 3T in sedated young children for assessment of congenital heart disease

Cardiac MRI is a crucial tool for assessing congenital heart disease (CHD). However, its application remains challenging in young children when performed at 3T. The aim of this retrospective single center study was to compare a non-contrast free-breathing 2D CINE T1-weighted TFE-sequence with compressed sensing (FB 2D CINE CS T1-TFE) with 3D imaging for diagnostic accuracy of CHD, image quality, and vessel diameter measurements in sedated young children. FB 2D CINE CS T1-TFE was compared with a 3D non-contrast whole-heart sequence (3D WH) and 3D contrast-enhanced MR angiography (3D CE-MRA) at 3T in 37 CHD patients (20♂, 1.5±1.4 years). Two radiologists independently assessed image quality, type of CHD, and diagnostic confidence. Diameters and measures of contrast and sharpness of the aorta and pulmonary vessels were determined. A non-parametric multi-factorial approach was used to estimate diagnostic accuracy for the diagnosis of CHD. Linear mixed models were calculated to compare contrast and vessel sharpness. Krippendorff's alpha was determined to quantify vessel diameter agreement. FB 2D CINE CS T1-TFE was rated superior regarding image quality, diagnostic confidence, and diagnostic sensitivity for both intra- and extracardiac pathologies compared to 3D WH and 3D CE-MRA (all p<0.05). FB 2D CINE CS T1-TFE showed superior contrast and vessel sharpness (p<0.001) resulting in the highest proportion of measurable vessels (740/740; 100%), compared to 3D WH (530/620; 85.5%) and 3D CE-MRA (540/560; 96.4%). Regarding vessel diameter measurements, FB 2D CINE CS T1-TFE revealed the closest inter-reader agreement (Krippendorff's alpha: 0.94-0.96; 3D WH: 0.78-0.94; 3D CE-MRA: 0.76-0.93). FB 2D CINE CS T1-TFE demonstrates robustness at 3T and delivers high-quality diagnostic results to assess CHD in sedated young children. Its ability to function without contrast injection and respiratory compensation enhances ease of use and could encourage widespread adoption in clinical practice.

Highly accelerated, Dixon-based non-contrast MR angiography versus high-pitch CT angiography

OBJECTIVES

To compare a novel, non-contrast, flow-independent, 3D isotropic magnetic resonance angiography (MRA) sequence that combines respiration compensation, electrocardiogram (ECG)-triggering, undersampling, and Dixon water-fat separation with an ECG-triggered aortic high-pitch computed tomography angiography (CTA) of the aorta.

MATERIALS AND METHODS

Twenty-five patients with recent CTA were scheduled for non-contrast MRA on a 3 T MRI. Aortic diameters and cross-sectional areas were measured on MRA and CTA using semiautomatic measurement tools at 11 aortic levels. Image quality was assessed independently by two radiologists on predefined aortic levels, including myocardium, proximal aortic branches, pulmonary veins and arteries, and the inferior (IVC) and superior vena cava (SVC). Image quality was assessed on a 5-point Likert scale.

RESULTS

All datasets showed diagnostic image quality. Visual grading was similar for MRA and CTA regarding overall image quality (0.71), systemic arterial image quality (p = 0.07-0.91) and pulmonary artery image quality (p = 0.05). Both readers favored MRA for SVC and IVC, while CTA was preferred for pulmonary veins (all p < 0.05). No significant difference was observed in aortic diameters or cross-sectional areas between native MRA and contrast-enhanced CTA (p = 0.08-0.94).

CONCLUSION

The proposed non-contrast MRA enables robust imaging of the aorta, its proximal branches and the pulmonary arteries and great veins with image quality and aortic diameters and cross-sectional areas comparable to that of CTA. Moreover, this technique represents a suitable free-breathing alternative, without the use of contrast agents or ionizing radiation. Therefore, it is especially suitable for patients requiring repetitive imaging.

Current Imaging Strategies in Patients with Abdominal Aortic Aneurysms

BACKGROUND

An abdominal aortic aneurysm (AAA) is defined as a localized dilatation of the abdominal aorta of ≥ 3 cm. With a prevalence of 4-8 %, AAA is one of the most common vascular diseases in Western society. Radiological imaging is an elementary component in the diagnosis, monitoring, and treatment planning of AAA patients.

METHOD

This is a narrative review article on preoperative imaging strategies of AAA, incorporating expert opinions based on the current literature and standard-of-care practices from our own center. Examples are provided to illustrate clinical cases from our institution.

RESULTS AND CONCLUSION

Radiological imaging plays a pivotal role in the initial diagnosis and monitoring of patients with AAA. Ultrasound is the mainstay imaging modality for AAA screening and surveillance. Contrast-enhanced CT angiography is currently considered the gold standard for preoperative imaging and image-based treatment planning in AAA repair. New non-contrast MR angiography techniques are robustly applicable and allow precise determination of aortic diameters, which is of critical importance, particularly with regard to current diameter-based surgical treatment guidelines. 3D imaging with multiplanar reformation and automatic centerline positioning enables more accurate assessment of the maximum aortic diameter. Modern imaging techniques such as 4D flow MRI have the potential to further improve individualized risk stratification in patients with AAA.

KEY POINTS

· Ultrasound is the mainstay imaging modality for AAA screening and monitoring. · Contrast-enhanced CT angiography is the gold standard for preoperative imaging in AAA repair. · Non-contrast MR angiography allows for accurate monitoring of aortic diameters in AAA patients. · Measurement of aortic diameters is more accurate with 3D-CT/MRI compared to ultrasound. · Research seeks new quantitative imaging biomarkers for AAA risk stratification, e. g., using 4D flow MRI.

Thoracic aorta diameters in Marfan patients: Intraindividual comparison of 3D modified relaxation-enhanced angiography without contrast and triggering (REACT) with transthoracic echocardiography

OBJECTIVE

To compare the measurement of aortic diameters using a novel flow-independent MR-Angiography (3D modified Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT)) and transthoracic echocardiography (TTE) in Marfan syndrome (MFS) patients.

MATERIAL AND METHODS

This retrospective, single-center analysis included 46 examinations of 32 MFS patients (mean age 37.5 ± 11.3 years, 17 women, no prior aortic surgery) who received TTE and 3D modified REACT (ECG- and respiratory-triggering, Compressed SENSE factor 9 for acceleration of image acquisition) of the thoracic aorta. Aortic diameters (sinus of Valsalva (SV), sinotubular junction (STJ), and ascending aorta (AoA)) were independently measured by two cardiologists in TTE (leading-edge) and two radiologists in modified REACT (inner-edge, using multiplanar reconstruction). Intraclass correlation coefficient, Bland-Altman analyses, and Pearson's correlation (r) were used to assess agreement between observers and methods.

RESULTS

Interobserver correlation at the SV, STJ, and AoA were excellent for both, TTE (ICC = 0.95-0.98) and modified REACT (ICC = 0.99-1.00). There was no significant difference between TTE and modified REACT for diameters measured at the SV (39.24 ± 3.24 mm vs. 39.63 ± 3.76 mm; p = 0.26; r = 0.78) and the STJ (35.16 ± 4.47 mm vs. 35.37 ± 4.74 mm; p = 0.552; r = 0.87). AoA diameters determined by TTE were larger than in modified REACT (34.29 ± 5.31 mm vs. 30.65 ± 5.64 mm; p < 0.01; r = 0.74). The mean scan time of modified REACT was 05:06 min ± 02:47 min, depending on the patient's breathing frequency and heart rate.

CONCLUSIONS

Both TTE and modified REACT showed a strong correlation for all aortic levels; however, at the AoA, diameters were larger using TTE, mostly due to the limited field of view of the latter with measurements being closer to the aortic valve. Given the excellent interobserver correlation and the strong agreement with TTE, modified REACT represents an attractive method to depict the thoracic aorta in MFS patients.