Normalized Subendocardial Myocardial Attenuation on Coronary Computed Tomography Angiography Predicts Postoperative Adverse Cardiovascular Events: Coronary CTA VISION Substudy.

BACKGROUND: Abnormalities in computed tomography myocardial perfusion has been associated with coronary artery disease and major adverse cardiovascular events (MACE). We sought to investigate if subendocardial attenuation using coronary computed tomography angiography predicts MACE 30 days postelective noncardiac surgery. METHODS: Using a 17-segment model, coronary computed tomography angiography images were analyzed for subendocardial and transmural attenuation and the corresponding blood pool. The segment with the lowest subendocardial attenuation and transmural attenuation were normalized to the segment with the highest subendocardial and transmural attenuation, respectively (SUBnormalized, and TRANSnormalized, respectively). We evaluated the independent and incremental value of myocardial attenuation to predict the composite of cardiovascular death or nonfatal myocardial infarction. RESULTS: Of a total of 995 coronary CTA VISION (Coronary Computed Tomographic Angiography and Vascular Events in Noncardiac Surgery Patients Cohort Evaluation Study) patients, 735 had available images and complete data for these analyses. Among these patients, 60 had MACE. Based on Revised Cardiovascular Risk Index, 257, 302, 138, and 38 patients had scores of 0, 1, 2, and ≥3, respectively. On coronary computed tomography angiography, 75 patients had normal coronary arteries, 297 patients had nonobstructive coronary artery disease, 264 patients had obstructive disease, and 99 patients had extensive obstructive coronary artery disease. SUBnormalized was an independent and incremental predictor of events in the model that included Revised Cardiovascular Risk Index and coronary artery disease severity. Compared with patients in the highest tertile of SUBnormalized, patients in the second and first tertiles had an increased hazards ratio for events (2.23 [95% CI, 1.091-4.551] and 2.36 [95% CI, 1.16-4.81], respectively). TRANSnormalized, as a continuous variable, was also found to be a predictor of MACE (P=0.027). CONCLUSIONS: Our study demonstrates that SUBnormalized and TRANSnormalized are independent and incremental predictors of MACE 30 days after elective noncardiac surgery. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01635309.

3D Rapid Prototyping Heart Model Validation for Teaching and Training - A Pilot Project in a Teaching Institution

Abstract Introduction: Rapid prototyping is a process by which three-dimensional (3D) computerized surface models are converted into physical models. In this study, a 3D heart bio model was created using the rapid prototyping method and the accuracy of this heart model was assessed by clinicians. Methods: The two-dimensional images of normal heart from gated computed tomography scan datasets were used to create a 3D model of the heart. The slices were then processed using the software BioModroid and printed with the 3D printer. The evaluation of the model was performed by a questionnaire answered by four cardiothoracic surgeons, 12 cardiologists, five radiologists, and nine surgical registrars. Results: Eighty-six percent of the anatomy structures showed in this model scored 100% accuracy. Structures such as circumflex branch of left coronary artery, great cardiac vein, papillary muscle, and coronary sinus were each rated 77%, 70%, 70%, and 57% accurate. Among 30 clinicians, a total of 93% rated the model accuracy as good and above; 64% of the clinicians evaluated this model as an excellent teaching tool for anatomy class. As a visual aid for surgery or interventional procedures, the model was rated excellent (40%), good (50%), average (23%), and poor (3%); 70% of the clinicians scored the model as above average for training purpose. Overall, this 3D rapid prototyping cardiac model was rated as excellent (33%), good (50%), and average (17%). Conclusion: This 3D rapid prototyping heart model will be a valuable source of anatomical education and cardiac interventional management.

The role of regional myocardial topography post-myocardial infarction on infarct extension.

Infarct extension involves necrosis of healthy myocardium in the border zone (BZ), progressively enlarging the infarct zone (IZ) and recruiting the remote zone (RZ) into the BZ, eventually leading to heart failure. The mechanisms underlying infarct extension remain unclear, but myocyte stretching has been suggested as the most likely cause. Using human patient-specific left-ventricular (LV) numerical simulations established from cardiac magnetic resonance imaging (MRI) of myocardial infarction (MI) patients, the correlation between infarct extension and regional mechanics abnormality was investigated by analysing the fibre stress-strain loops (FSSLs). FSSL abnormality was characterised using the directional regional external work (DREW) index, which measures FSSL area and loop direction. Sensitivity studies were also performed to investigate the effect of infarct stiffness on regional myocardial mechanics and potential for infarct extension. We found that infarct extension was correlated to severely abnormal FSSL in the form of counter-clockwise loop at the RZ close to the infarct, as indicated by negative DREW values. In regions demonstrating negative DREW values, we observed substantial fibre stretching in the isovolumic relaxation (IVR) phase accompanied by a reduced rate of systolic shortening. Such stretching in IVR phase in part of the RZ was due to its inability to withstand the high LV pressure that was still present and possibly caused by regional myocardial stiffness inhomogeneity. Further analysis revealed that the occurrence of severely abnormal FSSL due to IVR fibre stretching near the RZ-BZ boundary was due to a large amount of surrounding infarcted tissue, or an excessively stiff IZ.

3D Rapid Prototyping Heart Model Validation for Teaching and Training - A Pilot Project in a Teaching Institution.

INTRODUCTION: Rapid prototyping is a process by which three-dimensional (3D) computerized surface models are converted into physical models. In this study, a 3D heart bio model was created using the rapid prototyping method and the accuracy of this heart model was assessed by clinicians. METHODS: The two-dimensional images of normal heart from gated computed tomography scan datasets were used to create a 3D model of the heart. The slices were then processed using the software BioModroid and printed with the 3D printer. The evaluation of the model was performed by a questionnaire answered by four cardiothoracic surgeons, 12 cardiologists, five radiologists, and nine surgical registrars. RESULTS: Eighty-six percent of the anatomy structures showed in this model scored 100% accuracy. Structures such as circumflex branch of left coronary artery, great cardiac vein, papillary muscle, and coronary sinus were each rated 77%, 70%, 70%, and 57% accurate. Among 30 clinicians, a total of 93% rated the model accuracy as good and above; 64% of the clinicians evaluated this model as an excellent teaching tool for anatomy class. As a visual aid for surgery or interventional procedures, the model was rated excellent (40%), good (50%), average (23%), and poor (3%); 70% of the clinicians scored the model as above average for training purpose. Overall, this 3D rapid prototyping cardiac model was rated as excellent (33%), good (50%), and average (17%). CONCLUSION: This 3D rapid prototyping heart model will be a valuable source of anatomical education and cardiac interventional management.

Left ventricular flow propagation velocity measurement: Is it cast in stone?

This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle. We found that the V p measurement was affected by both the inflow jet direction and measurement positions. Both NA and AP methods overestimated V p, especially in dilated left ventricles, while the AV method showed the strongest correlation with the isovolumic relaxation myocardial strain rate (r = 0.53, p < 0.05). Using the AV method, notable difference in mean V p was also observed between healthy volunteers and post-infarct patients at positions of: one-half (81 ± 31 vs. 58 ± 25 cm/s), two-thirds (89 ± 32 vs. 45 ± 15 cm/s) and 4 cm (98 ± 23 vs. 47 ± 13 cm/s) distances. The use of AV method and measurement position at one-half distance was found to be the most suitable method for assessing diastolic dysfunction given varying left ventricular sizes and inflow jet directions.

Regional assessment of LV wall in infarcted heart using tagged MRI and cardiac modelling.

A segmental two-parameter empirical deformable model is proposed for evaluating regional motion abnormality of the left ventricle. Short-axis tagged MRI scans were acquired from 10 healthy subjects and 10 postinfarct patients. Two motion parameters, contraction and rotation, were quantified for each cardiac segment by fitting the proposed model using a non-rigid registration algorithm. The accuracy in motion estimation was compared to a global model approach. Motion parameters extracted from patients were correlated to infarct transmurality assessed with delayed-contrast-enhanced MRI. The proposed segmental model allows markedly improved accuracy in regional motion analysis as compared to the global model for both subject groups (1.22-1.40 mm versus 2.31-2.55 mm error). By end-systole, all healthy segments experienced radial displacement by ~25-35% of the epicardial radius, whereas the 3 short-axis planes rotated differently (basal: 3.3°; mid: -1° and apical: -4.6°) to create a twisting motion. While systolic contraction showed clear correspondence to infarct transmurality, rotation was nonspecific to either infarct location or transmurality but could indicate the presence of functional abnormality. Regional contraction and rotation derived using this model could potentially aid in the assessment of severity of regional dysfunction of infarcted myocardium.

Synchronous unilateral infiltrating ductal and lobular breast carcinoma.

The incidence of synchronous bilateral infiltrating breast cancer has been reported to be 2%. However, synchronous unilateral infiltrating ductal carcinoma and infiltrating lobular carcinoma (ILC) are very rarely reported. We present a woman with palpable ILC who was later found to have synchronous well-circumscribed ductal carcinoma on further imaging. We also discuss the use of diagnostic approaches such as ultrasonography, mammography and histopathology. This case highlights the importance of careful assessment of concurrent lesions in the breast in the presence of an existing carcinoma.

Coronary CT angiography: how should physicians use it wisely and when do physicians request it appropriately?

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease due to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with 64- and more slice CT scanners and in selected patients, coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. Although the tremendous contributions of coronary CT angiography to cardiac imaging are acknowledged, appropriate use of cardiac CT as the first line technique by physicians has not been well established. Optimal selection of cardiac CT is essential to ensure acquisition of valuable diagnostic information and avoid unnecessary invasive procedures. This is of paramount importance since cardiac CT not only involves patient risk assessment, prediction of major cardiac events, but also impacts physician decision-making on patient management. Applications of CT in cardiac imaging include coronary artery calcium scoring for predicting the patient risk of developing major cardiac events, followed by coronary CT angiography which is commonly used to determine the diagnostic and prognostic accuracy in the coronary artery disease. This review presents an overview of the applications of CT in cardiac imaging in terms of coronary calcium scoring and coronary CT angiography. Judicious use of both cardiac CT tools will be discussed with regard to their value in different patient risk groups with the aim of identifying the appropriate criteria for choosing a cardiac CT modality. An effective diagnostic pathway is finally recommended to physicians for appropriate selection of cardiac CT in clinical practice.