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Objectives The purpose of this study was to estimate the myocardial area at risk (MAAR) using coronary computed tomography angiography (CTA) and Voronoi algorithm-based myocardial segmentation in comparison with single-photon emission computed tomography (SPECT). Methods Thirty-four patients with coronary artery disease underwent 128-slice coronary CTA, stress/rest thallium-201 SPECT, and coronary angiography (CAG). CTA-based MAAR was defined as the sum of all CAG stenosis (>50 %) related territories (the ratio of the left ventricular volume). Using automated quantification software (17-segment model, 5-point scale), SPECT-based MAAR was defined as the number of segments with a score above zero as compared to the total 17 segments by summed stress score (SSS), difference (SDS) score map, and comprehensive SPECT interpretation with either SSS or SDS best correlating CAG findings (SSS/SDS). Results were compared using Pearson's correlation coefficient. Results Forty-nine stenoses were observed in 102 major coronary territories. Mean value of CTA-based MAAR was 28.3 ± 14.0 %. SSS-based, SDS-based, and SSS/SDS-based MAAR was 30.1 ± 6.1 %, 20.1 ± 15.8 %, and 26.8 ± 15.7 %, respectively. CTA-based MAAR was significantly related to SPECT-based MAAR ( r  = 0.531 for SSS; r  = 0.494 for SDS; r  = 0.814 for SSS/SDS; P  < 0.05 in each). Conclusions CTA-based Voronoi algorithm myocardial segmentation reliably quantifies SPECT-based MAAR. Key points • Voronoi algorithm allows for three-dimensional myocardial segmentation of coronary CT angiography • Stenosis-related CT myocardial territories correlate to SPECT based area at risk • CT angiography myocardial segmentation may assist in clinical decision-making

Since the introduction of computed tomography (CT) over 30 years ago, the challenge of imaging the beating heart has been a driving force in the innovation of cardiac CT. Imaging the anatomy and physiology of the heart demands temporal, spatial and contrast resolution is arguably greater than for any other organ system in the body. Great progress has been achieved in using CT to evaluate coronary artery stenosis and plaque composition. In addition, techniques to evaluate cardiac function, including myocardial perfusion, regional ventricular wall motion, systolic thickening, ejection fraction, valve function, and congenital cardiac abnormalities are also gaining a foothold in clinical practice as adjuncts to or replacements for invasive coronary angiography, cardiac single photon emission CT (SPECT) imaging, ultrasound and magnetic resonance imaging (MRI). This review summarizes the major accomplishments and future directions in this field, with emphasis on developments over the past 10 years.

Multidetector-row computed tomography (MDCT) applications have expanded to evaluation of myocardial blood flow (MBF) and viability. We quantified regional MBF pre– and post–coronary artery bypass grafting (CABG) using adenosine stress and cardiac 64-MDCT, and investigated whether the results predict MBF and left ventricular (LV) function recovery after CABG. We studied 321 regions in 19 CABG patients who underwent adenosine stress 64-row MDCT perfusion imaging and cine magnetic resonance imaging pre- and post-CABG. Myocardial blood flow was estimated from linear regression equation slopes using Patlak plot analyses and compared with LV function by measuring wall thickening (%WT) using cine magnetic resonance imaging. Overall mean MBFs were 1.39 ± 0.49 and 1.95 ± 0.49 mL/(g min) pre- and post-CABG ( P < .0001). Myocardial blood flow in revascularized areas increased significantly (pre-CABG 1.18 ± 0.45, post-CABG 1.99 ± 0.66 mL/[g min], P < .001), whereas nonischemic areas showed no difference (1.79 ± 0.70 and 1.97 ± 0.46 mL/[g min], P = .14). Revascularized areas with preoperative MBF ≥0.9 mL/(g min) showed significantly greater MBF improvement than those with preoperative MBF <0.9 mL/(g min) ( P = .04). In patients with preoperative LV dysfunction (ejection fraction <40%), %WT in revascularized areas with pre-CABG MBF ≥0.9 mL/(g min) improved significantly after CABG (pre-%WT 40.9 ± 22.9, post-%WT 52.8 ± 20.6, P = .03) versus those with pre-CABG MBF <0.9 mL/(g min) (pre-%WT 53.2 ± 35.5, post-%WT 42.5 ± 17.0, P = .40). Our results demonstrated more significantly increased MBF post-CABG than pre-CABG, particularly in revascularized areas. Regional MBF before CABG may predict MBF and LV function recovery, in the short term, after CABG.

We attempted to assess coronary artery flow using adenosine-stress and dual-energy mode with dual-source CT (DE-CT). Data of 18 patients with suspected coronary arteries disease who had undergone cardiac DE-CT were retrospectively analyzed. The patients were divided into two groups: 10 patients who performed adenosine stress CT, and 8 patients who performed rest CT as controls. We reconstructed an iodine map and composite images at 120 kV (120 kV images) using raw data with scan parameters of 100 and 140 kV. We measured mean attenuation in the coronary artery proximal to the distal portion on both the iodine map and 120 kV images. Coronary enhancement ratio (CER) was calculated by dividing mean attenuation in the coronary artery by attenuation in the aortic root, and was used as an estimate of coronary enhancement. Coronary stenosis was identified as a reduction in diameter of >50% on CT angiogram, and myocardial ischemia was diagnosed by adenosine-stress myocardial perfusion scintigraphy. The iodine map showed that CER was significantly lower for ischemic territories (0.76 ± 0.06) or stenosed coronary arteries (0.77 ± 0.06) than for non-ischemic territories (0.95 ± 0.21, P  = 0.02) or non-stenosed coronary arteries (1.07 ± 0.33, P  < 0.001). The 120 kV images showed no difference in CER between these two groups. Use of CER on the iodine map separated ischemic territories from non-ischemic territories with a sensitivity of 86% and a specificity of 75%. Our quantification is the first non-invasive analytical technique for assessment of coronary artery flow using cardiac CT. CER on the iodine map is a candidate method for demonstration of alteration in coronary artery flow under adenosine stress, which is related to the physiological significance of coronary artery disease.

Along with the increase of detector rows on the z-axis and a faster gantry rotation speed, the spatial and temporal resolutions of the multislice computed tomography (CT) have been improved for noninvasive coronary artery imaging. We investigated the feasibility of the second specification prototype 256-detector row four-dimensional CT for assessing coronary artery and cardiac function. The subjects were five patients with coronary artery disease. Contrast medium (40-60 ml) was intravenously administered at the rate of 3-4 ml/s. The patient's whole heart was scanned for 1.5 s to cover at least one cardiac cycle during breathholding without electrocardiographic gating. Parameters used were 0.5 mm slice thickness, 0.5 s/rotation, 120 Kv, and 350 mA, with a half-scan reconstruction algorithm (temporal resolution 250 ms). Twenty-six transaxial datasets were reconstructed at intervals of 50 ms. The assessability of the coronary arteries in AHA segments 1, 2, 3, 5, 6, 7, 9, and 11 was visually evaluated, resulting in 29 of 32 (90.9%) segments being assessable. Functional assessment was also performed using animated movies without banding artifacts in all cases. The 256-detector row four-dimensional CT can assess the coronary artery and cardiac function using data during 1.5 s without banding artifacts.

Objective Cerebral SPECT images require high spatial and contrast resolution for precise evaluation of the abnormal tracer distribution in the brain. A shorter data acquisition time is preferable so that artifacts due to patient movement are avoided. We tried to shorten data acquisition time applying larger sampling angle and offset acquisition method, in which half degree of the step angle was shifted in the opposite gamma camera of the dual-detector SPECT system. Methods A simulation study was performed with a 3-dimensional mathematical phantom. The phantom studies were performed with a hot-rod phantom and a brain phantom. A clinical study with 99m Tc-ECD SPECT was also performed on a patient who had a cerebral infarction. Reconstruction of images was done for the normal 6° and 12° onset and 12° offset. Data for the 12° offset were acquired by shifting of sampling angles of the opposite detector by half (6°) of the sampling angles of 12°. The MLEM algorithm was used for image reconstruction. Image qualities in the simulation study, the phantom studies, and the clinical study were compared for the 6° and 12° onset, and for the 12° offset by quantitative analysis with use of profile curves. Results Analysis of the profile curves revealed that the image quality of the 12° offset was better than that of the 12° onset and compared to that of the 6° onset in the simulation study, the phantom studies, and the clinical study. Conclusions The present study indicates that wide-angle offset data acquisition improves the image resolution of brain SPECT compared to onset data acquisition with the same sampling time.

Abstract Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors offer clinical benefits by reducing low-density lipoprotein cholesterol levels and have emerged as valuable therapeutic agents for the management of cardiovascular diseases. Although their effectiveness in treating coronary artery plaques and abdominal aortic aneurysms has been reported, data on their effects on coronary artery aneurysms are limited. Herein, we report the case of a 43-year-old man with familial hyperlipidemia who presented with angina pectoris caused by a giant right coronary artery aneurysm accompanied by extensive plaques and severe stenosis. The patient underwent coronary artery bypass grafting at 6 anastomotic sites, and a PCSK9 inhibitor was initiated postoperatively. Five years after surgery, imaging demonstrated a gradual reduction in the size of the coronary artery aneurysm, and 8 years later, the size was further reduced. This case report illustrates the rare clinical course of a coronary artery aneurysms. The major causes of coronary artery aneurysms are Kawasaki disease in children and atherosclerotic disease in adults.

We report a surgical case of dextrocardia complicated with annuloaortic ectasia (AAE) and mitral regurgitation, which induced congestive heart failure. Preoperative electrocardiography-gated multidetector-row computed tomography (MDCT) showed the following complex cardiovascular abnormalities without motion artifacts: dextrocardia, situs inversus, polysplenia, AAE, absence of the inferior vena cava, azygos vein continuation, drainage of the hepatic vein into the right atrium, and bilateral superior venae cavae. On the basis of the MDCT data, we established a cardiopulmonary bypass; and a modified Bentall procedure (Piehler method) and mitral valve replacement were performed without complications.

A 48-year-old man presented with severe chest pain that had started 2 h before and ST elevation on the electrocardiogram. Cardiac computed tomography (CT) was performed using a 64-slice multidetector scanner (MDCT) to assess coronary artery stenosis at 3 h after the onset. Coronary CT angiography showed no significant stenosis at the coronary arteries, but CT myocardial images at systole demonstrated predominantly subendocardial hypoenhancement in the anterior wall. Cardiac CT that combined coronary angiography and myocardial imaging demonstrated myocardial hypoenhancement in a case of acute coronary syndrome with normal coronary arteries, which may be related to microvascular dysfunction caused by vasospastic angina or microvascular angina.

Attenuation correction with an X-ray CT image is a new method to correct attenuation on SPECT imaging, but the effect of the registration errors between CT and SPECT images is unclear. In this study, we investigated the effects of the registration errors on myocardial SPECT, analyzing data from a phantom and a human volunteer. Registerion (fusion) of the X-ray CT and SPECT images was done with standard packaged software in three dimensional fashion, by using linked transaxial, coronal and sagittal images. In the phantom study, an X-ray CT image was shifted 1 to 3 pixels on the x, y and z axes, and rotated 6 degrees clockwise. Attenuation correction maps generated from each misaligned X-ray CT image were used to reconstruct misaligned SPECT images of the phantom filled with 201Tl. In a human volunteer, X-ray CT was acquired in different conditions (during inspiration vs. expiration). CT values were transferred to an attenuation constant by using straight lines; an attenuation constant of 0/cm in the air (CT value = -1,000 HU) and that of 0.150/cm in water (CT value = 0 HU). For comparison, attenuation correction with transmission CT (TCT) data and an external gamma-ray source (99mTc) was also applied to reconstruct SPECT images. Simulated breast attenuation with a breast attachment, and inferior wall attenuation were properly corrected by means of the attenuation correction map generated from X-ray CT. As pixel shift increased, deviation of the SPECT images increased in misaligned images in the phantom study. In the human study, SPECT images were affected by the scan conditions of the X-ray CT. Attenuation correction of myocardial SPECT with an X-ray CT image is a simple and potentially beneficial method for clinical use, but accurate registration of the X-ray CT to SPECT image is essential for satisfactory attenuation correction.