Tatsuya Nishii

Clinical Structural Anatomy of the Inferior Pyramidal Space Reconstructed Within the Cardiac Contour Using Multidetector‐Row Computed Tomography

Although many studies have described the detailed anatomy of the inferior pyramidal space, it may not be easy for cardiologists who have few chances to study cadaveric hearts to understand the correct morphology of the structure. The inferior pyramidal space is the part of extracardiac fibro‐adipose tissue wedging between the 4 cardiac chambers from the diaphragmatic surface of the heart. Many cardiologists have interests in pericardial adipose tissue, but the inferior pyramidal space seems to have been neglected. A number of important structures, including the coronary sinus, atrioventricular node, atrioventricular nodal artery, membranous septum, muscular atrioventricular sandwich (previously called the “muscular atrioventricular septum”), atrial septum, ventricular septum, aortic valvar complex, mitral valvar attachment, and tricuspid valvar attachment are associated with the inferior pyramidal space. We previously revealed its 3‐dimensional live anatomy using multidetector‐row computed tomography. Moreover, the 3‐dimensional understanding of the anatomy in association with the cardiac contour is important from the viewpoints of clinical cardiac electrophysiology. The purpose of this article is to demonstrate extended findings regarding the clinical structural anatomy of the inferior pyramidal space, which was reconstructed in combination with the cardiac contour using multidetector‐row computed tomography, and discuss the clinical implications of the findings.

Optimal angulations for obtaining an en face view of each coronary aortic sinus and the interventricular septum: Correlative anatomy around the left ventricular outflow tract

An optimal image intensifier angulation used for obtaining an en face view of a target structure is important in electrophysiologic procedures performed around each coronary aortic sinus (CAS). However, few studies have revealed the fluoroscopic anatomy of the target area. This study investigated the optimal angulation for each CAS and the interventricular septum (IVS). The study included 102 consecutive patients who underwent computed tomography coronary angiography. The optimal angle for each CAS was determined by rotating the volume‐rendered image around the vertical axis. The angle formed between the anteroposterior axis and IVS was measured using the horizontal section. The frontal direction was defined as zero, positive, or negative if the en face view of the target CAS was obtained in the frontal view, left anterior oblique (LAO) direction, or right anterior oblique (RAO) direction, respectively. The optimal angles for the left, right, and non‐CASs were 120.3 ± 10.5°, 4.8 ± 16.3°, and −110.0 ± 13.8°, respectively. The IVS angle was 42.6 ± 8.5°. Accordingly, the optimal image intensifier angulations for the left, right, and non‐CASs and the IVS were estimated to be RAO 60°, LAO 5°, LAO 70°, and RAO 50°, respectively. The IVS angle was the most common independent predictor of the optimal angle for each CAS. Differences in the optimal angulations for each CAS and the IVS are demonstrated. The biplane angulation needs to be tailored according to the individual patients and target structures for electrophysiologic procedures. Clin. Anat. 28:494–505, 2015.

Association between the rotation and three-dimensional tortuosity of the proximal ascending aorta

Age‐related morphological changes of the aorta, including dilatation and elongation, have been reported. However, rotation has not been fully investigated. We focused on the rotation of the ascending aorta and investigated its relationship with tortuosity. One hundred and two consecutive patients who underwent computed tomography coronary angiography were studied. The angle at which the en face view of the volume‐rendered image of the right coronary aortic sinus (RCS) was obtained without foreshortening was defined as the rotation index. It was defined as zero if the RCS was squarely visible in the frontal view, positive if it rotated clockwise toward the left anterior oblique (LAO) direction, and negative if it rotated counter‐clockwise toward the right anterior oblique (RAO) direction. The tortuosity was evaluated by measuring the biplane tilt angles formed between the ascending aorta and the horizontal line. The mean rotation index, posterior tilt angle viewed from the RAO direction (αRAO), and anterior tilt angle viewed from the LAO direction (αLAO) were 4.8 ± 16.3, 60.7 ± 7.0°, and 63.6 ± 9.0°, respectively. Although no correlation was observed between the rotation index and the αLAO (β = −0.0761, P = 0.1651), there was a significant negative correlation between the rotation index and αRAO (β = −0.1810, P < 0.0001). In multivariate regression analysis, the rotation index was an independent predictor of the αRAO (β = −0.1274, P = 0.0008). Clockwise rotation of the proximal ascending aorta exacerbates the tortuosity by tilting the aorta toward the posterior direction. Clin. Anat. 27:1200–1211, 2014.

Clinical structural anatomy of the inferior pyramidal space reconstructed from the living heart: Three-dimensional visualization using multidetector-row computed tomography

The inferior pyramidal space (IPS) comprises the epicardial visceral adipose tissue wedged between the bottoms of the four cardiac chambers from the postero‐inferior epicardial surface of the heart. Understanding the complex anatomy around the IPS is important for clinical cardiologists. Although leading anatomists and radiologists have clarified the anatomy of the IPS in detail, few studies have demonstrated this anatomy in three dimensions. The aim of this study was to visualize the three‐dimensional anatomy of the IPS reconstructed from the living heart using multidetector‐row computed tomography. We also developed an original paper model of the IPS to enhance understanding of its intricate structure. Clin. Anat. 28:878–887, 2015.

Clinical cardiac structural anatomy reconstructed within the cardiac contour using multidetector‐row computed tomography: Atrial septum and ventricular septum

Cardiologists are increasingly becoming involved in procedures associated with the atrial septum and ventricular septum, such as transseptal puncture and selective site pacing. Moreover, detailed knowledge about the architecture of the atrial septum and ventricular septum is now available from studies by radiologists and anatomists. However, from the viewpoint of clinical cardiologists, many questions about the three‐dimensional cardiac structural anatomy that relate closely to routine invasive procedures remain unresolved. Although modern multidetector‐row computed tomography could provide answers, interventional cardiologists might have not considered the potential of this equipment, as only a few have performed studies with both radiological imaging and cadaveric hearts. Detailed knowledge of the three‐dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of cardiac structural images, including images of the atrial septum and ventricular septum, reconstructed in combination with the cardiac contour using multidetector‐row computed tomography. We also discuss the clinical implications of the findings on the basis of accumulated insights of research pioneers. We hope that the present images will serve as a bridge between the fields of cardiology, radiology, and anatomy, and encourage cardiologists to integrate their accumulated insights into the three‐dimensional clinical images of the living heart. Clin. Anat. 29:342–352, 2016.

Clinical cardiac structural anatomy reconstructed within the cardiac contour using multidetector-row computed tomography: Left ventricular outflow tract.

The left ventricular outflow tract (LVOT) is a common site of idiopathic ventricular arrhythmia. Many electrocardiographic characteristics for predicting the origin of arrhythmia have been reported, and their prediction rates are clinically acceptable. Because these approaches are inductive, based on QRS‐wave morphology during the arrhythmia and endocardial or epicardial pacing, three‐dimensional anatomical accuracy in identifying the exact site of the catheter position is essential. However, fluoroscopic recognition and definition of the anatomy around the LVOT can vary among operators, and three‐dimensional anatomical recognition within the cardiac contour is difficult because of the morphological complexity of the LVOT. Detailed knowledge about the three‐dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of structural images of the LVOT reconstructed in combination with the cardiac contour using multidetector‐row computed tomography. We also discuss the clinical implications of these findings based on the accumulated insights of research pioneers. Clin. Anat. 29:353–363, 2016.

Three-dimensional quantification and visualization of aortic calcification by multidetector-row computed tomography: A simple approach using a volume-rendering method

OBJECTIVE Three-dimensional (3-D) visualization and quantification of vascular calcification (VC) are important to accelerate the multidisciplinary investigation of VC. Agatston scoring is the standard approach for evaluating coronary artery calcification. However, regarding aortic calcification (AC), quantification methods appear to vary among studies. The aim of this study was to introduce a simple technique of simultaneous quantification and 3-D visualization of AC and provide validation data. METHODS The main study comprised of 126 patients who underwent the thoracoabdominal plain computed tomography scan as preoperative general evaluation. AC was quantified using a volume-rendering (VR) method (VR AC volume) by extracting the volume with a density ≥130 HU within the total aorta. The concordance and reproducibility of the VR AC volume were validated in comparison with the conventional slice-by-slice voxel-based AC quantification (volumetric AC score) using the Agatston scoring software. RESULTS Excellent concordance between the VR AC volume and volumetric AC score was confirmed (Spearman correlation coefficient = 0.9997, mean difference = -0.05 ± 0.23 mL, p <0.0001). Excellent intraobserver and interobserver reliabilities were demonstrated using the Bland-Altman analysis as the mean intraobserver difference was 0.00 mL (p = 0.9863) and the mean interobserver difference was -0.01 mL (p = 0.6612). CONCLUSION The VR method was validated to be feasible. This simple approach could overcome the limitation of the current method based on slice-by-slice pixel or voxel summation, which lacks 3-D visual information. Accordingly, this approach would be promising for accelerating the investigation of VC.

The association between wedging of the aorta and cardiac structural anatomy as revealed using multidetector-row computed tomography

The aortic root is wedged within the cardiac base. The precise extent of aortic wedging, however, and its influence on the surrounding cardiac structures, has not been systematically investigated. We analysed 100 consecutive patients, who underwent coronary arterial computed tomographic angiography. We assessed the extent of aortic wedging by measuring the vertical distance between the non‐adjacent aortic sinus and the inferior epicardium. A shorter distance indicates deeper aortic wedging. We assessed the tilt angle and diameter of the ascending aorta, the relative heights of the left atrial roof and the oval fossa, the shape of the proximal right coronary artery, the angle of the aorta relative to the left ventricular axis, and the lung volume. The mean extent of wedging was 42.7 ± 9.8 mm. Multivariate analysis revealed that ageing, male gender, increased body mass index, patients without cardiomyopathy, the extent of tilting and dilation of the ascending aorta, and lung volume were all independent predictors for deeper aortic wedging (R2 = 0.7400, P < 0.0001). The extent of wedging was additionally correlated with a relatively high left atrial roof (R2 = 0.1394, P < 0.0001) and oval fossa (R2 = 0.1713, P < 0.0001), the shepherds crook shape of the proximal right coronary artery (R2 = 0.2376, P < 0.0001), and the narrowness of the angulation of the root relative to the left ventricular axis (R2 = 0.2544, P < 0.0001). In conclusion, ageing, male gender, obesity, background cardiac disease, aortic tilting and dilation, and lung volume are all correlated with the extent of wedging of the aortic root within the cardiac base.

The differences between bisecting and off‐center cuts of the aortic root: The three‐dimensional anatomy of the aortic root reconstructed from the living heart

It is axiomatic that the diameter of the virtual basal ring of the aortic root, which is elliptical rather than circular, will differ when assessed using between bisecting as opposed to off‐center cuts. Such differences, however, which pertain directly to echocardiographic assessments of the so‐called valvar annulus, have yet to be systematically explored.

Diversity and Determinants of the Three-dimensional Anatomical Axis of the Heart as Revealed Using Multidetector-row Computed Tomography

The location of the heart within the thorax varies significantly between individuals. The resultant diversity of the anatomical cardiac long axis, however, and its determinants, have yet to be systematically investigated. We enrolled 100 consecutive patients undergoing coronary arterial computed tomographic angiography, decomposing the vector of the anatomical cardiac long axis by projecting it to horizontal, frontal, and sagittal planes. The projected vectors on each plane were then converted into three rotation angles using coordinate transformation. We then measured the extent of aortic wedging, using the vertical distance between the inferior margins of the non‐adjacent aortic sinus and the epicardium. We took the aortic root rotation angle to be zero when an “en face” view of the right coronary aortic sinus was obtained in the frontal view, defining leftward rotation to be positive. The mean horizontal, frontal, and sagittal rotation angles were 48.7° ± 9.5°, 52.3° ± 12.0°, and 34.0° ± 11.2°, respectively. The mean extent of aortic wedging, and the aortic root rotation angle, were 42.7 ± 9.8 mm, and 5.3° ± 16.4°. Horizontal rotation of the anatomical axis was associated with leftward and ventral rotation, and vice versa. Multivariate analysis showed aortic root rotation to be associated with horizontal cardiac rotation, while aortic wedging is associated with frontal and sagittal cardiac rotation. We have quantified the marked individual variation observed in the anatomical axis of the living heart, identifying the different mechanisms involved in producing the marked three‐dimensional diversity of the living heart. Anat Rec, 300:1083–1092, 2017.