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.

Clinical cardiac structural anatomy reconstructed within the cardiac contour using multidetector-row computed tomography: The arrangement and location of the cardiac valves.

It is essential for the interventional cardiologist to have in-depth anatomical information about the three-dimensional arrangement and location of the cardiac valves relative to the various projections of the cardiac contour as revealed fluoroscopically. Multidetector-row computed tomography is useful for providing information about the three-dimensional arrangements of each structure. This article presents cardiac structural images, focusing on the arrangement and location of the cardiac valves, which were reconstructed with the cardiac contour and surrounding structures using multidetector-row computed tomography. We discuss the clinical implications of the findings. We hope these images will serve as a bridge between cardiology, radiology, and anatomy, and will prompt scientists in the field of cardiology to integrate their accumulated insights into three-dimensional clinical images of the living heart.

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.

A Comparison of Quantitative T2 Mapping on Cardiovascular Magnetic Resonance Imaging with Metaiodobenzylguanidine Scintigraphy and Left Ventricular Functional Recovery in Dilated Cardiomyopathy: A Retrospective Pilot Study.

OBJECTIVE: Metaiodobenzylguanidine (MIBG) scintigraphy is used to assess heart failure (HF) severity and to predict cardiac functional recovery. Cardiovascular magnetic resonance (CMR) imaging has recently been used to diagnosis HF. We evaluated CMR T2 mapping and MIBG scintigraphy in dilated cardiomyopathy (DCM) patients. METHODS: Consecutively, 22 DCM patients [aged 56.8 ± 13.4 years; 6 women and 16 men; left ventricular ejection fraction (LVEF), 31.9 ± 10.7%] who underwent T2 mapping and MIBG scintigraphy were retrospectively evaluated. Echocardiography results were recorded at baseline and the 6-month follow-up. Patients with an increased LVEF ≥15% between the 2 measures were considered to be responders. We measured each patient's T2 values and MIBG indices [the heart-to-mediastinum ratio (H/M) in the early phase, H/M in the delayed phase, and the washout rate (WOR)] at baseline. We compared these values between the 12 responders and 10 non-responders. RESULTS: The mean T2 value for all patients was 64.5 ± 6.6 ms. The mean values of early H/M, delayed H/M, and WOR were 2.06 ± 0.25, 1.94 ± 0.35, and 43.5 ± 11.8%, respectively. The T2 values were found to correlate with MIBG indices (p<0.05 for all) and were lower in the responders than non-responders (61.4 vs. 68.1 ms, p=0.013). MIBG indices were not significantly different. CONCLUSION: Our study shows that the T2 values correlated with the MIBG indices and were increased in non-responders. T2 mapping may be useful in assessing the cardiac function and functional recovery in DCM patients.

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.

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.

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.

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 (ß = -0.0761, P = 0.1651), there was a significant negative correlation between the rotation index and αRAO (ß = -0.1810, P < 0.0001). In multivariate regression analysis, the rotation index was an independent predictor of the αRAO (ß = -0.1274, P = 0.0008). Clockwise rotation of the proximal ascending aorta exacerbates the tortuosity by tilting the aorta toward the posterior direction.

Cardiovascular magnetic resonance tagging imaging correlates with myocardial dysfunction and T2 mapping in idiopathic dilated cardiomyopathy.

To evaluate the details of myocardial dysfunction in dilated cardiomyopathy (DCM) patients using tagging images and the correlation of tagging imaging with tissue characteristics. Circumferential strain (Ecc) derived from tagging images was measured in 15 normal (NML) subjects (15 males; mean age 28.5 years) and 12 DCM patients (7 males; mean age 48.9 years). The following parameters were compared: (1) the magnitude of peak Ecc (Ecc*); (2) the coefficient of variation of the time of Ecc* (CVtime*), which indexes dyssynchrony; and (3) descriptive findings of time-Ecc curves. We also evaluated the correlations of Ecc* in DCM patients with ejection fraction (EF), myocardial T2 values, and late gadolinium enhancement (LGE). Mean Ecc*s in DCM patients and NML subjects were -12.7 and -23.5%, respectively (P < 0.0001). Mean CVtime*s were 15.2 and 4.5%, respectively (P = 0.0002). The findings of pre-systolic extension and systolic stretch in the septum were observed in 6 (50%) and 10 (83.3%) DCM patients and in none of the NML participants. Ecc* was correlated with EF (P < 0.0001, R2 = 0.90) and T2 values (P = 0.018, R2 = 0.44) but not with LGE (P = 0.072, R2 = 0.28). Tagging images revealed the reduction of myocardial function as well as dyssynchrony in DCM patients. Myocardial dysfunction occurred coincidently with myocardial inflammation.

Predicting the response to cardiac resynchronization therapy using 99mTc-tetrofosmin myocardial scintigraphy in patients with drug-refractory heart failure: additional value of the washout of 99mTc-tetrofosmin.

OBJECTIVE: A lack of response to cardiac resynchronization therapy (CRT) has been reported in 20-40% of heart failure patients with left ventricular (LV) dyssynchrony who underwent treatment based on the established guidelines. The study aimed to investigate the relationship between (99m)Tc-tetrofosmin ((99m)Tc-TF) myocardial scintigraphy and the response to CRT. PATIENTS AND METHODS: Twenty-one patients with drug-refractory heart failure who underwent CRT were evaluated. All patients underwent (99m)Tc-TF myocardial scintigraphy before and after CRT. Single-photon emission computed tomography images of (99m)Tc-TF were acquired at 30 min and 3 h after injection and were used to determine the total defect score (TDS) and washout score (WOS). The change in the LV volume and ejection fraction (ΔLVEF) and relative reduction in left ventricular end-systolic volume (%ΔLVESV) were calculated as an index of LV functional recovery after CRT. Response to CRT was considered to have occurred when ΔLVEF was greater than 15% or when ΔLVEF was greater than 5% and %ΔLVESV was greater than 15%. RESULTS: Significant differences were observed between the patients who responded to CRT (the responder group, 13 patients) and the nonresponder group (eight patients) for both early and delayed TDS and WOS (P<0.05). Moreover, there was a good correlation between early TDS before CRT and both ΔLVEF and %ΔLVESV (P<0.01) and an excellent correlation between WOS before CRT and both ΔLVEF and %ΔLVESV (P<0.01). CONCLUSION: Evaluating the washout of (99m)Tc-TF in addition to myocardial perfusion before CRT using (99m)Tc-TF myocardial scintigraphy might be useful in drug-refractory heart failure patients.

Relationship of decreased accumulation of (99m)Tc-tetrofosmin on myocardial single-photon emission computed tomography images between QRS duration in dilated cardiomyopathy patient with left bundle branch block.

PURPOSE: This study aimed to clarify the relationship between severity of conduction delay in the left ventricle and myocardial uptake of (99m)Tc-tetrofosmin (TF) in dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB). METHODS AND RESULTS: Thirty-two DCM patients with LBBB underwent electrocardiography and (99m)Tc-TF myocardial single-photon emission computed tomography (SPECT). SPECT images were acquired at 30 min (early images) and 3 h (late images) after injection. We calculated the total defect score (TDS) using a 20-segment model with a 5-point scoring system. The TDS in early and late images was defined as the summed early score (SES) and summed late score (SLS), respectively. On early images, 29 of 32 patients (91%) had decreased tracer uptake in the septum. All patients showed a decreased tracer uptake in the septum on late images. A significant correlation was observed between TDS (both SES and SLS) and QRS duration, with SLS showing an excellent correlation (SES: r = 0.554, P < 0.001; SLS: r = 0.779, P < 0.0001). CONCLUSIONS: These findings suggest that in DCM patients with LBBB, hypoperfusion and myocardial damage in the septum might occur in accordance with an increase in the QRS duration.

Cardiovascular magnetic resonance T2 mapping can detect myocardial edema in idiopathic dilated cardiomyopathy.

Myocardial edema and inflammation play an important role in dilated cardiomyopathy (DCM). This pathologic condition can be identified noninvasively using cardiovascular magnetic resonance imaging (CMR). The purpose of this study was to determine the effectiveness of T2 values obtained with T2 mapping in the detection of edema in DCM patients, compared with that of conventional T2-weighted imaging (T2WI). CMR was used for 15 normal controls (NML) and 26 DCM patients. The DCM patients were classified as having either mild dysfunction with a left ventricular ejection fraction (EF) >35% or severe dysfunction with an EF ≤35%. Myocardial edema was assessed by both T2 mapping and T2WI. The differences between the T2 values determined from T2 mapping and the T2 ratios that were calculated from the T2WI were compared among the NML, mild DCM, and severe DCM patients. The T2 values for the NML, mild DCM, and severe DCM patients were 51.2 ± 1.6, 61.2 ± 0.37, and 67.4 ± 6.8, respectively (P < 0.05 for each pair), and the corresponding T2 ratios were 1.88 ± 0.09, 2.12 ± 0.37, and 2.04 ± 0.34, respectively (P > 0.05). T2 mapping clearly showed that the myocardial water content was larger in DCM patients than in NML controls and that the myocardial water content increased as the disease progressed. Thus, T2 mapping is a useful technique for the diagnosis and quantitation of diffuse myocardial edema.