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Background The purpose of this study was to develop a software tool and evaluate different T1 map calculation methods in terms of computation time in cardiac magnetic resonance imaging. Methods The modified Look-Locker inversion recovery (MOLLI) sequence was used to acquire multiple inversion time (TI) images for pre- and post-contrast T1 mapping. The T1 map calculation involved pixel-wise curve fitting based on the T1 relaxation model. A variety of methods were evaluated using data from 30 subjects for computational efficiency: MRmap, python Levenberg–Marquardt (LM), python reduced-dimension (RD) non-linear least square, C++ single- and multi-core LM, and C++ single- and multi-core RD. Results Median (interquartile range) computation time was 126 s (98–141) for the publicly available software MRmap, 261 s (249–282) for python LM, 77 s (74–80) for python RD, 3.4 s (3.1–3.6) for C++ multi-core LM, and 1.9 s (1.9–2.0) for C++ multi-core RD. The fastest C++ multi-core RD and the publicly available MRmap showed good agreement of myocardial T1 values, resulting in 95% Bland–Altman limits of agreement of (− 0.83 to 0.58 ms) and (− 6.57 to 7.36 ms) with mean differences of − 0.13 ms and 0.39 ms, for the pre- and post-contrast, respectively. Conclusion The C++ multi-core RD was the fastest method on a regular eight-core personal computer for pre- or post-contrast T1 map calculation. The presented software tool (fT1fit) facilitated rapid T1 map and extracellular volume fraction map calculations.

Computed tomography (CT) and magnetic resonance imaging (MRI) are being increasingly utilized for the evaluation of cardiac valves. Although echocardiography is the first-line imaging modality in the evaluation of aortic stenosis (AS), CT and MRI can be adopted as adjunct imaging modalities for assessing the severity of AS. First, CT has established its role in the evaluation of co-existing coronary artery disease in AS patients, while stress MRI can be employed to exclude myocardial perfusion abnormalities. For the pre- and post-procedural evaluation of transcatheter aortic valve implantation or replacement, CT plays a very important role in determining the size of prosthetic valves and evaluating post-procedural complications. CT also helps assess the prosthetic valve sizes with 3-dimensional printing. Late gadolinium enhancement, T1 mapping, and feature tracking of left ventricular myocardium enable assessment of left ventricular function and myocardial fibrosis in patients with AS. Four-dimensional flow analysis gives new insights on flow patterns, kinetic energy, and wall shear stress in the ascending aorta in AS patients. In summary, CT and MRI are playing increasingly important roles in the evaluation of aortic valve disease.

Purpose: To evaluate the normal range and variation in pre-contrast (preT1) and post-contrast (postT1) myocardial T1 values and extracellular volume fraction (ECV) according to left ventricular (LV) segments and to check for correlations between them and known cardiovascular risk factors.Methods: This study included 233 asymptomatic subjects (210 men and 23 women; aged 54.1±6.0 years) who underwent cardiac magnetic resonance imaging with preT1 and postT1 mapping on a 1.5-T scanner. T1 values and ECVs were compared among LV segments, age groups, and sex, and correlated with renal function. Based on the presence of hypertension (HTN) and diabetes mellitus (DM), the subjects were subdivided into the control (n=121), HTN (n=58), DM (n=25), and HTN and DM (HTN-DM) groups (n=29).Results: T1 values and ECV showed significant differences between the basal septal and lateral segments (p≤0.001) and between the mid-septal and mid-lateral segments (PreT1 p≤0.003, postT1 and ECV pConclusion: Septal segments show higher preT1 and ECV but lower postT1 than lateral segments at the mid-ventricular and basal levels. ECV is significantly affected by cardiovascular risk factors such as HTN, DM, and decreased renal function, even in asymptomatic subjects.

Cardiac magnetic resonance-tissue tracking (CMR-TT)-derived myocardial strain after ST-elevation myocardial infarction (STEMI) is related to adverse cardiac events. We aimed to investigate the feasibility of CMR-TT for the early prediction of adverse left ventricular (LV) remodeling after STEMI. We retrospectively searched our institution’s STEMI registry for patients who underwent reperfusion therapy, post-reperfusion CMR within 1 week after STEMI, and follow-up CMR. CMR-TT analysis was performed using cine imaging of post-reperfusion CMR. Adverse LV remodeling was defined as an increase in end-diastolic LV volume by 20% or more on follow-up CMR (median interval between serial CMR exams, 197 days; interquartile, 174–241 days). A total of 82 patients (age, 59.2 ± 11.1 years; male:female = 73:9) were included and divided into two groups: STEMI without (n = 62) and with (n = 20) adverse LV remodeling. Patients with LV remodeling showed significantly higher peak creatine kinase-MB and troponin I levels and a larger infarct size compared with those without LV remodeling (p = 0.001, p = 0.001, and p = 0.010, respectively). Global circumferential, radial, and longitudinal strain (GLS) also differed significantly between the groups (p = 0.001, p = 0.004, and p

A minute thrombus can pass through a small type of interatrial communication, which can result in a stroke or transient ischemic attack and several associated symptoms. This study sought to investigate a new type of interatrial communication. Thirty-one hearts from embalmed adult cadavers were investigated. Each interatrial channels (IACs) was classified as either an open or obstructed channel according to the connection of each hole on the right and left surfaces of the interatrial septum. Open channels were found in two specimens (6.5%). Both open and obstructed IACs followed tortuous courses through the interatrial septum. On the right surface of the interatrial septum, the hole was usually found adjacent to the left border of the interatrial septum between the opening of the superior vena cava into the right atrium and the superior margin of the fossa ovalis. Conversely, holes on the left surface of the interatrial septum were usually found in the upper and middle parts adjacent to the left border of the interatrial septum. This novel finding is expected to support our understanding of the onset of possible symptoms such as stroke in the absence of classical atrial septal defects.

Esophageal injury is a rare but potentially life-threatening condition. Endoscopic or surgical procedures are the most common causes of esophageal perforation which may lead to mediastinitis. Esophageal emergencies may initially present nonspecific clinical manifestations but characteristic imaging features which are crucial for ensuring an accurate diagnosis. In this chapter, the pathophysiology and characteristic imaging findings of traumatic and non-traumatic esophageal emergencies including esophageal perforation, Boerhaave’s syndrome, esophageal intramural dissection, esophageal hernia, acute phlegmonous esophagitis, and aortoesophageal fistula are discussed.

Traumatic thoracic skeletal injury is fairly common in an emergency setting. However, such injuries may be missed on chest imaging since the interpreting radiologists may not be familiar with thoracic skeletal injuries, or may pay more attention to other vital organs. An accurate diagnosis of skeletal injury is essential because the presence of a skeletal injury is associated with patient’s symptoms and can provide diagnostic clues for more severe associated injuries. In this chapter, we provided a comprehensive review of thoracic skeletal injuries involving rib, clavicle, sternum, sternoclavicular dislocation, scapula, and spine. The imaging findings of each skeletal injury and associated complications were reviewed.

Since contrast extravasation is a relatively uncommon imaging finding on chest CT, the imaging findings of contrast extravasation on chest CT may be unfamiliar to novice readers or be overlooked in daily practice. However, recognizing contrast extravasation on chest CT is of paramount importance in guiding appropriate patient treatment and preventing persistent bleeding. Contrast extravasation on chest CT can be observed in various settings: secondary to pulmonary tuberculosis (Rasmussen aneurysm), following trauma, as a complication of surgery, as a complication of interventional procedures such as thoracentesis, as a result of a tumor or pneumonia, etc. In the chapter, the authors present several representative cases involving contrast extravasation on chest CT.

Even though many patients complaining of fever in emergency department (ED) have infection as an underlying disease, fever in some other patients is caused by non-infectious causes. Non-infectious conditions eliciting fever and related pulmonary abnormalities and becoming the cause of ED visit can be identified in two different conditions besides infection and they are connective tissue disease (CTD) and malignant condition such as leukemia and related condition capillary leak syndrome and lymphoma. Other conditions that cause pulmonary emergency without infection include drug-related pneumonitis (DRP), radiation pneumonitis, cardiogenic or renal and neurogenic pulmonary edema (PE), diffuse alveolar hemorrhage (DAH), adult respiratory distress syndrome (ARDS) and acute interstitial pneumonia (AIP), fat embolism, acute eosinophilic pneumonia (AEP), organizing pneumonia (OP) and acute fibrinous organizing pneumonia (AFOP). Diffuse alveolar damage pattern with diffuse or wide patchy areas of parenchymal opacity is the key feature and is seen in most diseases. Pattern approach is most important in differential diagnosis.

Mediastinitis refers to the inflammatory or infectious conditions of the mediastinum and can be classified into acute and chronic forms. Acute mediastinitis is usually associated with esophageal rupture, or cardiothoracic surgeries. Chronic form of mediastinitis is referred to as fibrosing mediastinitis. There are two types of fibrosing mediastinitis: focal and diffuse. The focal type usually manifests as a localized, calcified mass in the paratracheal, subcarinal or pulmonary hilar area. The diffuse type manifests as a diffusely infiltrating, often noncalcified mass that affects multiple mediastinal compartments. Pyogenic spondylitis and tuberculous spondylitis are common causes of spinal infection. It is difficult to differentiate tuberculous spondylitis and pyogenic spondylitis clinically and radiologically. In this chapter, the pathophysiology and characteristic imaging findings of acute mediastinitis, fibrosing mediastinitis, descending necrotizing mediastinitis, and infectious spondylitis are discussed.

Traumatic airway injury is a relatively uncommon but potentially life-threatening condition. In patients with suspected airway injuries, imaging plays a key role in demonstrating the injury, its complications, and any associated injuries. In these patients, chest radiography and CT are essential to establishing a treatment plan. In this chapter, the mechanisms and imaging findings of traumatic airway injuries including tracheobronchial injuries, pneumomediastinum, and pulmonary interstitial emphysema are discussed.

In the thorax, foreign bodies may be encountered in the airways, esophagus, and other body parts. Imaging diagnosis is often difficult when there is no corresponding clinical information, since many aspirated or ingested foreign bodies are radiolucent (e.g., food boluses). Even radio-opaque foreign bodies might be sometimes overlooked since radiologists or clinicians may regard them as radiopaque materials present outside the body or medical devices. Leaving a foreign body behind in the thorax may cause complications such as infection, migration, thrombosis, or sepsis. To ensure accurate diagnosis and treatment of foreign bodies, radiologists should be familiar with the imaging findings of commonly encountered foreign bodies, secondary signs such as post-obstructive changes and associated complications.

Pneumonia, which is the leading cause of death owing to infectious disease, is a common condition seen in the emergency department (ED). In the ED, accurate diagnosis of pneumonia and grading of pneumonia severity is important because clinicians must determine whether to manage pneumonia on an outpatient basis, in a hospital ward, or in the intensive care unit. Imaging studies should always be interpreted with full awareness of the clinical features of the disease. Knowledge of a patient’s exposure status (community-acquired pneumonia [CAP] or healthcare-associated pneumonia [HCAP]) and immune status are important for differential diagnosis and determination of the most likely causative organisms. Conditions that simulate pneumonia and need differential diagnosis in the ED include hydrostatic pulmonary edema (PE), diffuse alveolar hemorrhage (DAH), radiation pneumonitis, drug-related pneumonitis (DRP), pulmonary lymphangitic carcinomatosis (PLC), acute eosinophilic pneumonia (AEP), extensive organizing pneumonia (OP), acute fibrinous and organizing pneumonia (AFOP) and acute interstitial pneumonia (AIP), and pulmonary tuberculosis manifesting as acute respiratory distress syndrome or cystic lung diseases. Please refer to chapter 11 (non-infectious pulmonary emergency).

Computed tomography (CT) is the first-line imaging modality for evaluation of acute aortic diseases and magnetic resonance imaging (MRI) can be used without exposure to radiation or contrast injection in selected cases of acute aortic diseases. Electrocardiography (ECG)-gated CT scanning is recommended to avoid pulsating artifacts in the ascending aorta. CT findings can be used to predict prognoses of patients with uncomplicated acute type B classic dissection or intramural hematoma. Imaging findings of an infected aortic pseudoaneurysm, traumatic pseudoaneurysm, rupturing aortic aneurysm, aortoesophageal fistula, aortobronchial fistula, noninfectious aortitis, and periaortic sclerotic disease are also discussed in this review.

Background With an increasing clinical importance of the treatment of the heart failure (HF) with preserved ejection fraction (HFpEF), it is important to be certain of the diagnosis of HF. We investigated global and regional left ventricular (LV) strains using speckle tracking echocardiography (STE) in patients with HFpEF and compared those parameters with that of patients with hypertension and normal subjects. Methods Peak longitudinal, circumferential and radial strains were assessed globally and regionally for each study groups using STE. Diastolic strain rate was also determined. Results There were 50 patients in HFpEF group, 56 patients in hypertension group and 46 age-matched normal subjects. In patients with HFpEF, global peak longitudinal, circumferential and radial strain and strain rate were reduced compared to both hypertension patients and normal controls (− 15.5 ± 5.3 vs − 17.7 ± 3.1 and − 19.9 ± 2.0; − 9.7 ± 2.2 vs − 19.3 ± 3.1 and − 20.5 ± 3.3; 17.7 ± 8.2 vs 38.4 ± 12.4 and 43.6 ± 11.9, respectively, P Conclusions In the speckle tracking echocardiography, impaired peak global strain and homogeneously reduced regional strain was observed in HFpEF patients compared to the hypertension patients and normal subjects in decreasing order. This can provide early information on the initiation of LV deformation of HFpEF in patients with hypertension or normal subjects.

Objective We aimed to compare the aortic valve area (AVA) calculated using fast high-resolution three-dimensional (3D) magnetic resonance (MR) image acquisition with that of the conventional two-dimensional (2D) cine MR technique. Materials and methods We included 139 consecutive patients (mean age ± standard deviation [SD], 68.5 ± 9.4 years) with aortic valvular stenosis (AS) and 21 asymptomatic controls (52.3 ± 14.2 years). High-resolution T2-prepared 3D steady-state free precession (SSFP) images (2.0 mm slice thickness, 10 contiguous slices) for 3D planimetry (3DP) were acquired with a single breath hold during mid-systole. 2D SSFP cine MR images (6.0 mm slice thickness) for 2D planimetry (2DP) were also obtained at three aortic valve levels. The calculations for the effective AVA based on the MR images were compared with the transthoracic echocardiographic (TTE) measurements using the continuity equation. Results The mean AVA ± SD derived by 3DP, 2DP, and TTE in the AS group were 0.81 ± 0.26 cm², 0.82 ± 0.34 cm², and 0.80 ± 0.26 cm², respectively (p = 0.366). The intra-observer agreement was higher for 3DP than 2DP in one observer: intraclass correlation coefficient (ICC) of 0.95 (95% confidence interval [CI], 0.94-0.97) and 0.87 (95% CI, 0.82-0.91), respectively, for observer 1 and 0.97 (95% CI, 0.96-0.98) and 0.98 (95% CI, 0.97-0.99), respectively, for observer 2. Inter-observer agreement was similar between 3DP and 2DP, with the ICC of 0.92 (95% CI, 0.89-0.94) and 0.91 (95% CI, 0.88-0.93), respectively. 3DP-derived AVA showed a slightly higher agreement with AVA measured by TTE than the 2DP-derived AVA, with the ICC of 0.87 (95% CI, 0.82-0.91) vs. 0.85 (95% CI, 0.79-0.89). Conclusion High-resolution 3D MR image acquisition, with single-breath-hold SSFP sequences, gave AVA measurement with low observer variability that correlated highly with those obtained by TTE.

BACKGROUND Little is known about the causality and pathological mechanism underlying the association between old age and myocardial injury in patients with ST-segment elevation myocardial infarction (STEMI). We evaluated the association between old age and myocardial injury in STEMI patients undergoing primary percutaneous coronary intervention (PCI) using cardiovascular magnetic resonance imaging (CMR). METHODS A total of 279 patients with STEMI who underwent primary PCI and CMR were enrolled. Of these, 52 patients were over the age of 70 years (18.6%, Age ≥70 group) and 227 patients were under the age of 70 years (81.4%, Age

Background: The spectrum of genetic variants and their clinical significance of Hypertrophic cardiomyopathy (HCM) have been poorly studied in Asian patients. The objectives of this study were to assess the spectrum of genetic variants and genotype&ndash, phenotype relationships within a Korean HCM population. Methods: Eighty-nine consecutive unrelated HCM patients were included. All patients underwent genotypic analysis for 23 HCM-associated genes. Clinical parameters including echocardiographic and cardiac magnetic resonance (CMR) parameters were evaluated. A composite of major adverse cardiac and cerebrovascular events was assessed. Results: Genetic variants were detected in 55 of 89 subjects. Pathogenic variants or likely pathogenic variants were identified in 27 of HCM patients in MYBPC3, TNNI3, MYH7, and MYL7. Variants of uncertain significance were identified in 28 patients. There were significant differences in the presence of non-sustained ventricular tachycardia (p = 0.030) and myocardial fibrosis on CMR (p = 0.029) in the detected compared to the not-detected groups. Event-free survival was superior in the not-detected group (p = 0.006). Conclusion: Genetic variants in patients with HCM are relatively common and are associated with adverse clinical events and myocardial fibrosis on CMR. Genotypic analysis may add important information to clinical variables in the assessment of long-term risk for HCM patients.

Objectives This study assessed diffuse myocardial fibrosis (MF) by cardiac magnetic resonance (CMR) imaging and speckle-tracking echocardiography (STE) in patients with severe aortic stenosis (AS) and validated findings by using histologic confirmation of MF. Background MF is a concomitant pathologic finding related to hypertrophic response in severe AS. It would be beneficial to have reliable imaging methods to assess MF. Methods CMR and STE were performed in 71 consecutive patients with severe AS before aortic valve replacement. The extracellular volume (ECV) and native T1 values obtained by CMR and global longitudinal strain (GLS) values by STE were measured. The degree of MF was quantified by using Masson trichrome stain in myocardial biopsy specimens obtained intraoperatively. The study population was divided into 3 groups according to the degree of MF on histology (mild, moderate, and severe MF). Results The severe MF group had a higher incidence of heart failure (HF) and diastolic dysfunction than the mild and moderate MF groups. The ECV (r = 0.465; p Conclusions ECV as assessed by CMR could be an ideal surrogate marker for diffuse MF in patients with severe AS among all 3 models considered.

Resumen Introduccion y objetivos El objetivo del estudio es evaluar el efecto de aliskireno en la rigidez aortica del paciente con sindrome de Marfan (SM). Metodos Se recluto a 28 pacientes con SM (media ± desviacion estandar de edad, 32,6 ± 10,6 anos) entre noviembre de 2009 y octubre de 2014. Todos estaban tratados con atenolol como terapia estandar con bloqueadores beta. Mediante un proceso prospectivo de aleatorizacion, se asigno a los participantes a tratamiento con aliskireno (150-300 mg/dia via oral) o sin tratamiento con aliskireno (controles negativos) en un diseno de etiquetado abierto. Se examinaron al inicio y a las 24 semanas la distensibilidad aortica central y la velocidad de la onda de pulso (PWV) cuantificadas con resonancia magnetica (RM), la PWV periferica, la presion aortica central y el indice de aumento medidos por tonometria y la dilatacion aortica por ecocardiografia. El objetivo primario fue la distensibilidad aortica central por RM. Resultados En el analisis de la diferencia entre el examen basal y a las 24 semanas en el grupo tratado frente a los controles negativos, la distensibilidad aortica central (general; p = 0,26) y la PWV central (0,2 ± 0,9 frente a 0,03 ± 0,7 m/s; p = 0,79) medidas con RM no fueron significativas. La presion sistolica central en la aorta era de 14 mmHg, menor en los pacientes tratados que en los controles (p = 0,09). Se observo una reduccion significativa de la PWV periferica (brazo-tobillo) en el grupo tratado (–1,6 m/s) respecto a los controles (+0,28 m/s; p = 0,005). Conclusiones En los pacientes con SM, la incorporacion de aliskireno a los bloqueadores beta no mejora la rigidez de la aorta central a las 24 semanas de tratamiento.

Introduction and objectives The aim of this study was to evaluate the effect of aliskiren on aortic stiffness in patients with Marfan syndrome (MS). Methods Twenty-eight MS patients (mean age ± standard deviation: 32.6 ± 10.6 years) were recruited from November 2009 to October 2014. All patients were receiving atenolol as standard beta-blocker therapy. A prospective randomization process was performed to assign participants to either aliskiren treatment (150-300 mg orally per day) or no aliskiren treatment (negative control) in an open-label design. Central aortic distensibility and central pulsed wave velocity (PWV) by magnetic resonance imaging (MRI), peripheral PWV, central aortic blood pressure and augmentation index by peripheral tonometry , and aortic dilatation by echocardiography were examined initially and after 24 weeks. The primary endpoint was central aortic distensibility by MRI . Results In analyses of differences between baseline and 24 weeks for the aliskiren treatment group vs the negative control group, central distensibility (overall; P = .26) and central PWV (0.2 ± 0.9 vs 0.03 ± 0.7 [m/s]; P = .79) by MRI were not significantly different. Central systolic aortic blood pressure tended to be lower by 14 mmHg in patients in the aliskiren treatment group than in the control group (P = .09). A significant decrease in peripheral PWV (brachial-ankle PWV) in the aliskiren treatment group (–1.6 m/s) compared with the control group (+0.28 m/s) was noted (P = .005). Conclusions Among patients with MS, the addition of aliskiren to beta-blocker treatment did not significantly improve central aortic stiffness during a 24-week period.

To compare inversion time (TI) parameters, native T1, and extracellular volume (ECV) on cardiac magnetic resonance (CMR) imaging between patients with cardiac amyloidosis (CA) or hypertrophic cardiomyopathy (HCMP). Forty six patients with biopsy-confirmed CA and 30 patients with HCMP who underwent CMR were included. T1 and TI values were measured in the septum and cavity of the left ventricle on T1 mapping and TI scout images. TI values were selected at nulling point for each myocardium and blood pool. Native T1, ECV, and TI interval values were significantly different between the CA (1170.5 ± 86.4 ms, 56.7 ± 12.2, - 11.5 ± 28.4 ms) and HCMP (1059.5 ± 63.4 ms, 28.5 ± 5.8, 66.2 ± 25.4 ms) (all p

Radiology education is a key component in many preclinical anatomy courses. However, the reported effectiveness of radiology education within such anatomy classrooms has varied. This study was conducted to determine if a novel educational method using dynamic images of movies of computed tomography (CT) and magnetic resonance imaging (MRI) was effective in radiology education during a preclinical anatomy course, aided by clay modeling, specific hand gestures (digit anatomy), and reports from dissection findings uploaded to the anatomy course website (digital reports). Feedback surveys using a five-point Likert scale were administered to better clarify students' opinions regarding their understanding of CT and MRI of anatomical structures, as well as to determine if such preclinical radiology education was helpful in their clinical studies. After completion of the anatomy course taught with dynamic images of CT and MRI, most students demonstrated an adequate understanding of basic CT and MR images. Additionally, students in later clinical years generally believed that their study of radiologic images during the preclinical anatomy course was helpful for their clinical studies and clerkship rotations. Moreover, student scores on imaging anatomy examinations demonstrated meaningful improvements in performance after using dynamic images from movies of CT and MRI.

Background Myocardial perfusion reserve index (MPRI) and extracellular volume fraction (ECV) on cardiac magnetic resonance (CMR) are known to quantify coronary microvascular dysfunction and myocardial fibrosis, respectively. Purpose To demonstrate that cardiovascular risk factors such as hypertension, diabetes, hyperlipidemia, and smoking are correlated with MPRI and ECV on CMR in asymptomatic individuals. Material and Methods Between October 2013 and July 2014, 196 individuals underwent CMR. After excluding those with chest pain, arrhythmia, and obstructive coronary artery disease, participants were divided into five groups: those without risk factor (n = 26) and those with one (n = 43), two (n = 35), three (n = 24), or four (n = 6) risk factors. MPRI and ECV were obtained on perfusion CMR and pre- and post-T1 mapping, respectively. Results A total of 134 asymptomatic individuals (109 men, 25 women; mean age = 54.4 ± 7.08 years; body mass index [BMI] = 24.96 ± 2.76 kg/m2; Framingham risk score [FRS] = 7.71 ± 5.21) were included. The Jonckheere-Terpstra test demonstrated trends of increasing BMI, FRS, and left ventricular mass index (all P values Conclusion We demonstrated that an increasing number of cardiovascular risk factors is significantly associated with reduced MPRI, but not with ECV on CMR.

Automatic localization of anatomical landmarks in myocardial perfusion magnetic resonance (MR) data is considered to be a preliminary step toward fully automatic quantification of regional upslope or blood flow in the myocardium. The goal of this work is to develop an automatic method based on supervised learning and detect anatomical landmarks with high accuracy from myocardial perfusion MR data. Dynamic contrast enhanced myocardial MR perfusion data were acquired using a standard perfusion sequence. To effectively extract characteristic features for left ventricle (LV) center point and anterior right ventricle (RV) insertion point, we performed feature extraction of the two landmarks independently from an LV enhancement frame and an RV enhancement frame. Feature extraction of pixel intensity, Sobel gradient, and Haar-like features was performed. Cross-validation from training data was used to build a random forests classifier. We used 38 subjects’ data as training datasets and 21 subjects’ data as test datasets. The proposed method provided high accuracy in localization of the LV center point and anterior RV insertion point. The mean (±SD) localization errors of the proposed method were 3.38 (±2.36) mm for the LV center point and 4.23 (±1.97) mm for the anterior RV insertion point. The proposed method shows the potential to automatically localize anatomical landmarks for the segmental analysis of myocardial perfusion in MRI.

The purpose of this study was to determine the prognostic value of myocardial perfusion CT for major adverse cardiac events (MACE).Data from six centers in Asia, Europe, and North America on 144 patients with known or suspected coronary artery disease who had undergone coronary CT angiography (CCTA) and dynamic myocardial perfusion CT with a dual-source CT system were analyzed. CCTA studies were acquired at rest. Dynamic myocardial perfusion CT was performed under vasodilator stress. CCTA data were evaluated for the presence of coronary artery stenosis (≥ 50% luminal narrowing) on a per-vessel basis. Myocardial perfusion CT data were qualitatively evaluated for perfusion defects in each vessel territory. Patient follow-up was performed 6, 12, and 18 months after imaging. The prognostic value of CT findings was assessed with Kaplan-Meier statistics and the multivariate Cox proportional hazards regression model.According to the CCTA findings, 62 of 144 patients (43.1%) had at least one 50% or greater stenosis. According to the myocardial perfusion CT findings, 51 patients (35.4%) had one or more perfusion defects. Patients with at least one perfusion defect at myocardial perfusion CT were at increased risk of MACE (hazard ratio, 2.50; 95% CI, 1.34-4.65; p = 0.0040). This association remained significant after adjustment for age, sex, and clinical risk factors (hazard ratio, 2.41; 95% CI, 1.28-4.51; p = 0.0064) and after further adjustment for CCTA findings (hazard ratio, 2.03; 95% CI, 1.04-3.97; p = 0.0390). The number of territories with perfusion defects was strongly predictive of MACE with adjusted hazard ratios of 1.41, 3.44, and 4.76 for one, two, and three affected territories.In assessment for future MACE, myocardial perfusion CT has incremental predictive value over clinical risk factors and detection of coronary artery stenosis with CCTA.

BackgroundTo investigate the feasibility of a low tube voltage (80 kVp) protocol with low concentration contrast media (CM) (iodixanol 320 mgl/ml) as compared with a high tube voltage (100 kVp) protocol with high concentration CM (iomeprol 400 mgl/ml) in coronary CT angiography (CCTA) for patients with body mass index less than 30.Materials and methodsA total of 93 patients were randomly assigned into three groups and underwent CCTA as follows: Group A) 100 kVp, 100-350 mAs, 400 mgl/ml CM at 4ml/s, and reconstructed with filtered back projection; Group B and C) 80 kVp, 100-450 mAs, 320 mgl/ml CM at 4 ml/s and 5 ml/s, respectively and reconstructed with iterative reconstruction. Objective and subjective image quality (IQ) was analyzed.ResultsThe image noise, intravascular attenuation, signal-to-noise ratio and contrast-to-noise ratio of major coronary arteries did not differ significantly among three groups. Subjective IQ analyses on vascular attenuation and image noise did not differ significantly, either (all of p > 0.05). Qualitative IQ of Group B and C was non-inferior to that of Group A. Substantial reduction of radiation exposure was achieved in group B (2.60 ± 0.48 mSv) and C (2.72 ± 0.54 mSv), compared with group A (3.58 ± 0.67 mSv) (p < 0.05).ConclusionCCTA at 80 kVp with 320 mgl/ml CM and iterative reconstruction is feasible, achieving radiation dose reduction, while preserving IQ.

Background Administration of gadolinium-contrast can cause problems in cardiac amyloidosis (CA) patients with impaired renal function. Purpose To compare patterns of cardiovascular magnetic resonance tissue tracking (CMR-TT) for CA and hypertrophic cardiomyopathy (HCM) and to assess the feasibility of CMR-TT to distinguish between these diseases without administration of gadolinium-contrast. Material and Methods Included were 54 patients with biopsy-proven CA, 40 patients with HCM, and 30 healthy people. We calculated strain ratio of apex to base (SRAB) in the left ventricle (LV) using radial (R), circumferential (C), and longitudinal (L) strain from CMR-TT. The LV ejection fraction (LVEF) and the ratio of septal to posterior wall at basal level were also calculated. Late gadolinium enhancement (LGE) image analysis was performed for differential diagnosis. Area under the receiver operating characteristic curve (AUC) comparisons were used. Results All SRAB values were significantly different between CA and HCM (all P < 0.001). AUC values for parameters were 0.806 for LVEF, 0.815 for ratio of wall thickness, 0.944 for the LGE pattern, 0.898 for SRABR, 0.880 for SRABC, and 0.805 for SRABL. AUCs for the LGE pattern were significantly higher than for LVEF, ratio of wall thickness and SRABL (all P < 0.008). No significant differences were seen between AUCs for the LGE pattern, SRABR, and SRABC (all P > 0.109). Conclusion SRABR and SRABC were reliable parameters for distinguishing between CA and HCM.

Background Hypertrophic cardiomyopathy (HCM) is thought to be associated with microvascular dysfunction. Adenosine stress-perfusion cardiovascular magnetic resonance imaging (CMR) is a sensitive method for assessing microvascular perfusion abnormalities. We evaluated the prevalence and clinical characteristics of HCM patients with adenosine-induced perfusion defects on CMR. Methods Among 189 consecutive patients with HCM who underwent adenosine-stress perfusion CMR, 115 patients who had clinical, echocardiography, 24-h Holter monitoring and treadmill exercise test data were analyzed. We calculated myocardial perfusion ratio index from the intensity-over-time curve to quantify perfusion defects. The presence and extent of the stress-induced perfusion defect were compared with clinical characteristics, presence and extent of late gadolinium enhancement (LGE), left ventricular (LV) mass index and volume, presence of non-sustained ventricular tachycardia (NSVT) and results of treadmill exercise test. Results The mean age of enrolled patients was 51.8 ± 11.3 years. Most patients were asymptomatic except 25 subjects presented with New York Heart Association Class II dyspnea and 16 patients with atypical non-exertional chest discomfort. LGE was present in 103 (89.6%) subjects. Adenosine stress-induced perfusion defects were present in 48 (42%) subjects. None of the perfusion defects corresponded with a single or multiple coronary artery territories, showing a multiple patchy pattern in 24 (50.0%), a concentric subendocardial pattern in 20 subjects (41.7%), and as a single blot-like defect in the remaining 4 (8.3%). A perfusion defect was associated with NSVT, LV apical aneurysm, higher LV mass index, and higher LGE volume on univariate analysis. Multivariate analysis revealed female gender (P = 0.008), presence of apical aneurysm and NSVT (P = 0.036 and 0.047, respectively), and LV mass index (P = 0.022) to be independently associated with adenosine stress-induced perfusion defects. Conclusions In patients with HCM, adenosine-stress perfusion defects on CMR are present in more than 40% of subjects. This perfusion defect is associated with NSVT, higher LV mass index, and apical aneurysms. The prognostic value of this finding needs further elucidation.

OBJECTIVE The clinical course of an individual patient with heart failure is unpredictable with left ventricle ejection fraction (LVEF) only. We aimed to evaluate the prognostic value of cardiac magnetic resonance (CMR)-derived myocardial fibrosis extent and to determine the cutoff value for event-free survival in patients with non-ischemic cardiomyopathy (NICM) who had severely reduced LVEF. MATERIALS AND METHODS Our prospective cohort study included 78 NICM patients with significantly reduced LV systolic function (LVEF < 35%). CMR images were analyzed for the presence and extent of late gadolinium enhancement (LGE). The primary outcome was major adverse cardiac events (MACEs), defined as a composite of cardiac death, heart transplantation, implantable cardioverter-defibrillator discharge for major arrhythmia, and hospitalization for congestive heart failure within 5 years after enrollment. RESULTS A total of 80.8% (n = 63) of enrolled patients had LGE, with the median LVEF of 25.4% (19.8-32.4%). The extent of myocardial scarring was significantly higher in patients who experienced MACE than in those without any cardiac events (22.0 [5.5-46.1] %LV vs. 6.7 [0-17.1] %LV, respectively, p = 0.008). During follow-up, 51.4% of patients with LGE ≥ 12.0 %LV experienced MACE, along with 20.9% of those with LGE ≤ 12.0 %LV (log-rank p = 0.001). According to multivariate analysis, LGE extent more than 12.0 %LV was independently associated with MACE (adjusted hazard ratio, 6.71; 95% confidence interval, 2.54-17.74; p < 0.001). CONCLUSION In NICM patients with significantly reduced LV systolic function, the extent of LGE is a strong predictor for long-term adverse cardiac outcomes. Event-free survival was well discriminated with an LGE cutoff value of 12.0 %LV in these patients.

Objective True neurogenic thoracic outlet syndrome (TN-TOS) is an extremely rare neuromuscular disease. We report clinical, electrodiagnostic and radiologic features of patients with TN-TOS. Methods Retrospective chart review of patients satisfying criteria was done. Nerve conduction study (NCS) and needle electromyography (EMG) of upper extremity were reviewed. Brachial plexus MRI and computed tomography angiography (CTA) were also reviewed. Results Thirteen TN-TOS patients were identified. The most common neurologic signs were hypesthesia in the medial forearm or ulnar digits and weakness of the abductor pollicis brevis (APB) muscle. In NCS, medial antebrachial cutaneous (MABC) sensory nerve action potential amplitude was decreased in all tested patients. The APB muscle was most commonly involved in EMG. Among radiologic criteria, focal stenosis of subclavian artery in CTA was the most common finding. Conclusion We confirmed that TN-TOS is T1 predominant lower roots/trunk brachial plexopathy with clinical and electrodiagnostic features. Radiologic studies may be used to detect structural abnormalities. Significance As MABC NCS showed abnormal results in all tested patients, it should be added to electrodiagnostic study as screening method. If present, structural abnormalities might be confirmed with radiologic studies.

The purpose of our study was to investigate the impact of temporal uniformity and adjustment by the contrast opacification enhancement in the aorta on the performance of transluminal attenuation gradient (TAG) for obstructive coronary artery disease. A total of 274 coronary arteries from 94 patients who underwent both multi- and single-beat scan using 128-slice scanner at the same time were enrolled. TAG and corrected coronary opacification (CCO) of both scan technique were compared against obstructive coronary arteries defined by diameter stenosis ≥50%. In per-vessel analysis, both TAG and CCO were slight but significantly different between multi- and single-beat scan in overall (−13.3 vs. −14.3 HU/10 mm; 0.31 vs. 0.38; p

The aims of this study were to identify the distribution of coronary artery calcium score (CACS) by age group and cardiovascular (CV) risk factors and to evaluate the association between CV risk factors and CACS classification in asymptomatic adults. The study included 31,545 asymptomatic Koreans, over 20 years of age with no previous history of malignancy, proven coronary artery disease, or stroke, who underwent CACS computed tomography at the Health Promotion Center, Samsung Medical Center, between January 2005 and June 2013. Mean (±SD) age was 53.8 (±8.5) years overall, 56.1 (±8.3) in men, and 53.3 (±8.5) in women. They were classified into five groups based on their resting CACS: none (CAC = 0), minimal (0 CAC ≤ 10), mild (10 CAC ≤ 100), moderate (100 CAC ≤ 400), and extensive (400 CAC). Older age groups exhibited higher CACS values. The proportion of CACS classification in our study was 55.5 % with no CACS, 9.5 % with minimal CACS, 19.8 % with mild CACS, 10.8 % with moderate CACS, and 4.3 % with extensive CACS. Adjusted odds ratios (ORs) were calculated for CV risk factors to determine their association with CACS. When analyzed according to sex, in males, the adjusted OR for CACS increased with the presence of hypertension (HT), diabetes mellitus (DM), obesity, chronic kidney disease, and smoking status. While, in females, the adjusted OR for CACS increased with the presence of HT, DM, and obesity. CV risk factors appear to be significantly associated with CACS in the Korean population.

To compare the success rates of percutaneous coronary interventions (PCIs) for chronic total occlusion (CTO) lesions according to the different signal intensity (SI) patterns seen at coronary magnetic resonance (MR) angiography.Institutional review board approval was obtained, and all patients gave written informed consent. This study included 95 CTO lesions in 93 consecutive patients who underwent steady-state free-precession coronary MR angiography with a 1.5-T imager before PCI. The SI and length of CTO lesions were evaluated at coronary MR angiography, and the lesions were classified into two groups according to the continuity of the areas of high SI in the CTO lesions. Invasive angiographic findings including lesion length and collateral grades were analyzed. A multivariable logistic regression analysis was performed to identify variables associated with successful PCI.Seventy-eight (82%) of 95 CTO lesions were treated successfully with PCI. On coronary MR angiograms, areas of continuous high SI were found in 42 lesions (44%), and 40 (95%) of them were treated successfully with PCI. Thirty-eight (72%) of 53 lesions with low SI or interrupted high SI throughout the CTO segments were successfully treated with PCI. The presence of areas of continuous high SI in the CTO segments was the only independent predictor of PCI success (odds ratio, 8.20; 95% confidence interval: 1.08, 62.15; P = .042).Continuous areas of high SI in CTO lesions on coronary MR angiograms are predictive of better success rates with PCI than are discontinuous or absent areas of high SI.

BackgroundRecently there have been several clinical MR perfusion studies in patients with hypertrophic cardiomyopathy (HCM) who may suffer from myocardial ischemia due to coronary microvascular dysfunction. In these studies, data analysis relied on a manual procedure of tracing epicardial and endocardial borders. The goal of this work is to develop and validate a robust semi-automated analysis method for myocardial perfusion quantification in clinical HCM data. MethodDynamic multi-slice stress perfusion MRI data were acquired from 18 HCM patients. The proposed semi-automated method required user input of two landmark selections: LV center point and RV insertion point. Automated segmentations of the endocardial and epicardial borders were performed in three short-axis slices using distance regularized level set evolution on RV, LV, and myocardial enhancement frames. ResultsThe proposed automated epicardial border detection method resulted in average radial distance errors of 7.5%, 9.5%, and 11.6% in basal, mid, and apical slices, respectively, when compared to manual tracing of the borders as a reference. In linear regression analysis, the highest correlation of myocardial upslope measurements was observed between the manual method and the proposed method in the anterolateral section (r=0.964), and the lowest correlation was observed in the inferoseptal section (r=0.866). ConclusionThe proposed semi-automated method for myocardial MR perfusion quantification is feasible in HCM patients who typically show (1) irregular myocardial shape and (2) low image contrast between the myocardium and its surrounding regions due to coronary microvascular disease. Semi-automated quantification of multi-slice cardiac MR perfusion is proposed.LV center and RV insertion points are manually chosen, and remaining steps are automated.Myocardium is automatically segmented using distance regularized level set evolution.Accuracy of myocardial upslope quantification is evaluated on clinical HCM data.

Rationale and Objectives To evaluate the diagnostic accuracy of semiautomated global quantification of left ventricular myocardial perfusion derived from stress dynamic computed tomography myocardial perfusion imaging (CTMPI) for detection of territorial perfusion deficits (PD). Materials and Methods Dynamic CTMPI datasets of 71 patients were analyzed using semiautomated volume-based software to calculate global myocardial blood flow (MBF), myocardial blood volume, and volume transfer constant. Optimal cutoff values to assess the diagnostic accuracy of these parameters for detection of one- to three-vessel territories with PD in comparison to visual analysis were calculated. Results Nonsignificant differences ( P = 0.694) were found for average global MBF in patients without PD and single-territorial PD. Significant differences were found for mean global MBF in patients with PD in two ( P P Conclusions Semiautomated global quantification of left ventricular MBF during stress dynamic CTMPI shows high diagnostic accuracy for detection of ≥2 vessel territories with PD, facilitating identification of patients with multi-territorial myocardial PD.

Atrial fibrillation (AF) is a leading cause of stroke, but not all cases of stroke in patients with AF are due to AF.The purpose of this study was to determine whether morphometric or volumetric parameters of left atrial appendage (LAA) would be related to the development of cardioembolism in subjects with AF.A total of 433 consecutive patients with acute ischemic stroke underwent multidetector cardiac computed tomography (MDCT). Of these patients, 88 with AF were divided into cardioembolic stroke (CES; n = 57) and non-CES (n = 31) groups, and 95 age- and sex-matched patients with non-CES without AF served as controls. Clinical factors, echocardiographic findings, and MDCT parameters were evaluated.Brain infarct volume, LAA orifice diameter, and LAA volume were larger in patients with CES with AF than in those with non-CES with AF (P.05 in all cases), but no difference was observed between patients with non-CES with AF and those with non-CES without AF. MDCT and echocardiographic parameters of left atrial (LA) dysfunction were different depending on the presence of AF but not between patients with CES with AF vs non-CES with AF. After adjusting for covariates, LAA orifice diameter (odds ratio 1.19, 95% confidence interval 1.06-1.33, P = .004) and LAA volume (odds ratio 12.20, 95% confidence interval 2.58-57.79, P = .002) were independently associated with CES with AF, as was infarct volume.In patients with AF, LAA orifice diameter and LAA volume, but not left atrial dysfunction, were determinants of CES and were useful for stratifying noncardioembolic risk in patients with AF.

The aim of this study was to compare the radiation dose and image quality of two CT protocols using a wide-detector computed tomography (WDCT) scanner with single contrast injection for simultaneous evaluation of the aorta and coronary artery. We retrospectively included 104 consecutive patients who underwent coronary and aorta CT angiography. CT Protocols were divided as follows: protocol I, variable helical pitch scan (VHP, n = 31); protocol II, volume scan for coronary artery following helical scan for aorta (VFH, n = 73). Vascular attenuation, noise, signal-to-noise (SNR), and contrast-to-noise ratios (CNR) were compared. Image parameters were measured at coronary artery, thoracic aorta, abdominal aorta, and iliofemoral arteries. Subjective image quality was assessed by two observers. The patient characteristics between groups were similar (P ≥ 0.384). There were no significant differences in any of the quantitative image parameters between the two groups except for the thoracic aorta. Vascular attenuation (469.2 ± 133.6 vs. 605.9 ± 140.2 HU), CNR (24.8 ± 11.4 vs. 37.3 ± 18.5), and SNR (28.4 ± 12.0 vs. 40.6 ± 19.5 ml) were higher in the VHP protocol (P

Side branch (SB) occlusion is one of the major technical hurdles in the percutaneous coronary intervention (PCI) of bifurcation lesions. Our aim was to investigate whether preprocedural coronary computed tomography angiography (CCTA) could predict intraprocedural SB occlusion.A total of 260 bifurcation lesions were enrolled from 246 patients who underwent CCTA before elective bifurcation PCI. Quantitative plaque analysis was performed in the main vessel (MV) and SB. Intraprocedural SB occlusion occurred in 42 lesions (16%). These lesions were characterised by SB plaque, calcified plaque in the MV, low attenuation plaque in the main proximal segment or SB, and a ratio of MV to SB ostium area4.3, which constituted a point-based CT bifurcation score. The CT bifurcation score was cross-validated, outperforming any angiographic Medina classification or RESOLVE score (c-statistics=0.749 versus 0.631 to 0.551; p0.05 for all). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CT bifurcation score ≥1 were 90%, 42%, 23%, 96%, and 50%, respectively.Comprehensive CCTA assessment was able to predict intraprocedural SB occlusion better than the current angiographic classification or scoring system. The CT bifurcation score may thus be a helpful guide for selecting the optimal bifurcation PCI strategy.

Transluminal attenuation gradient (TAG) using 256-slice or 320-slice CT scanners (TAG320) showed a sensitivity of 58–77%, specificity of 44–87%, positive predictive value of 50–83%, negative predictive value of 27–88%, and an area under the curve (AUC) of 0.72–0.78, with invasive fractional flow reserve (FFR) used as the reference standard. The combination of coronary CT angiography (CCTA) and TAG resulted in an AUC between 0.64 and 0.87. In studies using a 64-slice CT scanner, cutoff values of TAG ranged from −1.8 HU/cm to −15.1 HU/cm, while studies using 256- or 320-slice CT scanners used thresholds between −7.5 HU/cm and −15.4 HU/cm. The addition of TAG to CCTA may improve the diagnostic performance of CCTA for evaluating calcified lesions. The AUC for contrast density difference (CDD) was not significantly higher compared to TAG and visual stenosis assessment. TAG-corrected coronary opacification (CCO) was lower in vessels with a hemodynamically significant lesion; however, TAG-CCO was not significant when subgroup analysis was performed for vessels with ≥50% stenosis on CCTA. The CT-integrated approach resulted in a marked increase in sensitivity and a mild decrease in specificity compared with both CCTA + CT perfusion (CTP) and CCTA + TAG320. CT-FFR provides better diagnostic performance for the detection of lesion-specific ischemia compared to stenosis detection on CCTA and TAG. A significant correlation was found between TAG and transluminal diameter gradient (TDG).

Background It has been reported that left ventricular (LV) myocardial strain and late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) imaging have prognostic value in patients with heart failure (HF). However, previous studies included patients with various systolic functions. This study aimed to investigate the prognostic value of LV myocardial strain and LGE on CMR imaging in patients with idiopathic dilated cardiomyopathy (DCM) with reduced ejection fraction (EF

Background To investigate the association between unrecognized myocardial infarction (UMI) assessed with cardiac magnetic resonance (CMR) and coronary artery calcium (CAC) and cardiovascular risk prediction scores in asymptomatic Asian subjects. Materials and methods Total 872 asymptomatic subjects without prior cardiovascular event (male:female, 817:55; age, 53.88 ± 5.91) who underwent both CMR and CAC scoring CT were included. UMI were accessed and framingham risk score (FRS) and ASCVD (atherosclerotic cardiovascular disease) risk score by ACC/AHA were calculated. Results Late gadolinium enhancement indicating UMI was noted in 23 of 872 subjects (2.64%), but only three of them showed ECG abnormality (13.04%). Subjects with UMI showed higher CAC scores, FRS, and ASCVD scores than those without UMI (p < .001, p = .011 and p = .024, respectively). The prevalence of UMI differed significantly according to the CAC scores as follows: 1% in CAC = 0 (4/403), 1% in 1 ≤ CAC

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is associated with hemodynamic changes in the pulmonary vasculature. However, cardiac effects are not fully understood and vary by phenotype of chronic lower respiratory disease. PURPOSE: To use four-dimensional (4D) flow MRI for comprehensive assessment of the right-sided cardiovascular system, assess its interrater and intraobserver reproducibility, and examine associations with venous return to the right heart in individuals with chronic COPD and emphysema. MATERIALS AND METHODS: The Multi-Ethnic Study of Atherosclerosis COPD substudy prospectively recruited participants who smoked and who had COPD and nested control participants from population-based samples. Electrocardiography and respiratory gated 4D flow 1.5-T MRI was performed at three sites with full volumetric coverage of the thoracic vessels in 2014–2017 with postbronchodilator spirometry and inspiratory chest CT to quantify percent emphysema. Net flow, peak velocity, retrograde flow, and retrograde fraction were measured on 14 analysis planes. Interrater reproducibility was assessed by two independent observers, and the principle of conservation of mass was employed to evaluate the internal consistency of flow measures. Partial correlation coefficients were adjusted for age, sex, race/ethnicity, height, weight, and smoking status. RESULTS: Among 70 participants (29 participants with COPD [mean age, 73.5 years ± 8.1 {standard deviation}; 20 men] and 41 control participants [mean age, 71.0 years ± 6.1; 22 men]), the interrater reproducibility of the 4D flow MRI measures was good to excellent (intraclass correlation coefficient range, 0.73–0.98), as was the internal consistency. There were no statistically significant differences in venous flow parameters according to COPD severity (P > .05). Greater percent emphysema at CT was associated with greater regurgitant flow in the superior and inferior caval veins and tricuspid valve (adjusted r = 0.28–0.55; all P < .01), particularly in the superior vena cava. CONCLUSION: Four-dimensional flow MRI had good-to-excellent observer variability and flow consistency. Percent emphysema at CT was associated with statistically significant differences in retrograde flow, greatest in the superior vena cava. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Choe in this issue.

Background: Although a common symptom in patients with severe aortic stenosis (AS) without obstructive coronary artery disease (CAD), little is known about the pathogenesis of exertional an...