Tarinee Tangcharoen

Visualization of the Cardiac Venous System Using Cardiac Magnetic Resonance

We sought to investigate the value of cardiac magnetic resonance to depict cardiac venous anatomy. For cardiac resynchronization therapy the lead for the left ventricle is usually placed by transvenous approach into a tributary of the coronary sinus (CS). Knowledge of the anatomy and variations of the cardiac venous system may facilitate the positioning of the left ventricle lead. The cardiac magnetic resonance examinations of 23 subjects (16 volunteers and 7 patients) were retrospectively analyzed. All examinations were performed using navigator-gated whole-heart steady-state free precession coronary artery imaging after administration of intravascular contrast agents (gadofosveset in volunteers; Gadomer-17 in patients). The cardiac venous system was visualized in all subjects. The most frequent anatomical variant observed (in 12 subjects [52%]) was a connection of the small cardiac vein to the CS at the crux cordis. In 10 subjects (44%) the small veins entered the right atrium independently from the CS, and the posterior interventricular vein was connected to the CS at the crux cordis. Only one subject had a disconnection between the CS and posterior interventricular vein, which entered into the right atrium independently. The mean distance of the posterior vein of the left ventricle and the left marginal vein to the ostium of the CS was 15.2+/-4.7 mm and 49.7+/-14.1 mm, respectively. In conclusion, the anatomy of the cardiac venous system and its anatomical variability can be described using cardiac magnetic resonance. Its preimplantation visualization may help to facilitate the implant procedure and to reduce fluoroscopy time.

A subject-specific technique for respiratory motion correction in image-guided cardiac catheterisation procedures

We describe a system for respiratory motion correction of MRI-derived roadmaps for use in X-ray guided cardiac catheterisation procedures. The technique uses a subject-specific affine motion model that is quickly constructed from a short pre-procedure MRI scan. We test a dynamic MRI sequence that acquires a small number of high resolution slices, rather than a single low resolution volume. Additionally, we use prior knowledge of the nature of cardiac respiratory motion by constraining the model to use only the dominant modes of motion. During the procedure the motion of the diaphragm is tracked in X-ray fluoroscopy images, allowing the roadmap to be updated using the motion model. X-ray image acquisition is cardiac gated. Validation is performed on four volunteer datasets and three patient datasets. The accuracy of the model in 3D was within 5mm in 97.6% of volunteer validations. For the patients, 2D accuracy was improved from 5 to 13mm before applying the model to 2-4mm afterwards. For the dynamic MRI sequence comparison, the highest errors were found when using the low resolution volume sequence with an unconstrained model.

Detection of coronary artery anomalies in infants and young children with congenital heart disease by using MR imaging.

PURPOSE To evaluate the feasibility and accuracy of magnetic resonance (MR) coronary angiography for the detection of coronary artery anomalies in infants and children by using surgical findings as a reference. MATERIALS AND METHODS The data analysis was approved by the institutional review board. One hundred children with congenital heart disease underwent MR coronary angiography while under general anesthesia (mean age ± standard deviation, 3.9 years ± 3; age range, 0.2-11 years). A navigator-gated, T2-prepared, three-dimensional steady-state free precession whole-heart protocol (isotropic voxel size, 1.0-1.3 mm(3); mean imaging time, 4.6 minutes ± 1.2; mean navigator efficiency, 70%; 3-mm gating window) was used after injection of gadopentetate dimeglumine. The cardiac rest period (end systole or middiastole) and acquisition window were prospectively assessed for each patient. Coronary artery image quality (score of 0 [nondiagnostic] to 4 [excellent]), vessel sharpness, and coronary artery anomalies were assessed by two observers. Surgery was performed in 58 patients, and those findings were used to define accuracy. Variables were assessed between age groups by using either analysis of variance or Kruskal-Wallis tests. RESULTS Diagnostic image quality (score, ≥1 for all coronary artery segments) was obtained in 46 of the 58 patients (79%) who underwent surgery. The origin and course of the coronary artery anatomy depicted with MR imaging was confirmed at surgery in all 46 patients-including the four (9%) with substantial coronary artery anomalies. Diagnostic-quality images were obtained in 84 of the 100 patients. The rate of success improved significantly when patients were older than 4 months (88% for patients >4 months vs 17% for patients ≤4 months, P < .001). CONCLUSION Improved whole-heart MR coronary angiography enables accurate detection of abnormal origin and course of the coronary artery system even in very young patients with congenital heart disease.

Assessment of left ventricular volumes and mass with fast 3D cine steady-state free precession k-t space broad-use linear acquisition speed-up technique (k-t BLAST)

To compare left ventricular (LV) volume and mass assessment using two‐dimensional (2D) cine steady‐state free precession (SSFP) and k‐t space broad‐use linear acquisition speed‐up technique (k‐t BLAST) accelerated 3D magnetic resonance imaging (MRI).

Impact of heart rate variability in patients with normal sinus rhythm on image quality in coronary magnetic angiography.

To evaluate the influence of heart rate variability on image quality in patients with suspected coronary artery disease during magnetic resonance coronary angiography (MRCA).

Evaluation of Multiple Coronary Artery Aneurysms in Kawasaki’s Disease by Whole Heart Non-Contrast Enhanced MRI

We describe a patient with history of an acute coronary syndrome. Cardiovascular magnetic resonance (CMR) was used for the assessment of coronary artery status using a high-resolution whole heart coronary artery imaging sequence, cardiac function at rest and detection of myocardial fibrosis using delayed enhancement. In the current case there were multiple giant aneurysms, one with evidence of thrombosis in combination with wall motion abnormalities and late enhancement in the myocardial segments supplied by this coronary artery.

Diagnosis of a "Single" Coronary Artery and Determination of Functional Significance of Concomitant Coronary Artery Disease

Apreviously healthy 71-year-old man with chest pain occurring irregularly during the last 6 months was referred to cardiac magnetic resonance imaging (MRI); a prior exercise ECG was reported to be normal. Whole-heart coronary MR angiography revealed a single, common ostium of the right and left coronary artery arising from the right anterior sinus with anomalous course of the left coronary artery between the aorta and pulmonary artery, which is by definition considered a “single” coronary artery.1 Concomitant obstructive coronary disease of both vessels (Figure 1A …

219 Feasibility of whole-heart steady-state free precession magnetic resonance coronary angiography (MRCA) in infants and children with congenital heart disease

Methods 100 patients (median age 3 years, age range 4 months–11 yrs) with congenital heart disease were imaged with Philips Intera 1.5 T MR scanner under general anesthesia. After injection of contrast (Magnevist 0.2 mmol/kg), a vector cardiogram-triggered, free-breathing, 3D-SSFP whole-heart approach with navigator gating (3 mm) was used with nearly isotropic image resolution (table 1). The acquisition window was adapted to the resting period of the heart. Image quality of the left and right coronary arteries were assessed by two independent observers using a score ranging from 0 (nonvisible) to 4 (excellent quality). The coronary arteries were reformatted using SoapBubble tool2 for vessel length measurements. Echocardiography findings and surgical findings were reference standards for assessment of coronary origins and proximal course.

1105 MR imaging sequences and clinical validation of a technique for respiratory motion correction in XMR-guided cardiac catheterisations

Introduction We have previously developed an augmented reality system that provides an anatomical roadmap derived from MR imaging that is continually aligned to X-ray fluoroscopy images in the XMR hybrid imaging environment [1]. We have used this system to guide cardiac catheterisation for more than 50 clinical cases. This system provides an accuracy of 2 mm, but respiratory motion introduces errors that are typically much greater than this. In this abstract, we describe a novel technique for correcting for respiratory motion using a patient-specific motion model derived from MR imaging. Validation was performed on four volunteer and three patient datasets.