Outcome of MRI in Patients with Nonconditional Devices with Mismatch between Manufacturer of Leads and Generator

In a series of 35 MRI examinations with non-MRI-conditional devices with a mismatch between the manufacturer of the device generators and leads, there were no adverse events.

Relationship Between Myocardial Perfusion Imaging Abnormalities on Positron Emission Tomography and Anginal Symptoms, Functional Status, and Quality of Life

BACKGROUND

Myocardial perfusion imaging (MPI) identifies abnormalities that occur early in the ischemic cascade leading to angina. Our aim was to study the association between ischemic measures on positron emission tomography MPI and patients' health status; their symptoms, function, and quality of life.

METHODS

Health status was collected using the Seattle Angina Questionnaire (SAQ-7, 0-100, higher=better) and Rose Dyspnea Score (RDS) on 1515 outpatients with known or suspected coronary artery disease presenting for clinically indicated pharmacological ⁸²Rb positron emission tomography MPI from July 2018 to July 2019. Adjusted multivariable ordinal regression models were used to assess the association between MPI findings of ischemia and the SAQ physical limitation, angina frequency, quality of life, summary score, and the RDS.

RESULTS

The mean SAQ and RDS scores of the cohort (mean age 71.7 years, 55% male, 37.6% prior myocardial infarction or revascularization) were 73.8±28.6 (physical limitation), 87.4±21.7 (angina frequency), 79.0±26.1 (quality of life), 81.3±19.0 (summary score), and 2±2 (RDS). No perfusion, flow or function abnormalities were significantly associated with SAQ angina frequency scores. Low left ventricular ejection fraction reserve (≤0%), low global and regional myocardial blood flow reserve (<2) were independently associated with worse SAQ Physical Limitation score, SAQ summary score, and RDS (30% to 57% greater odds; all P≤0.01), but reversible perfusion defects were not.

CONCLUSIONS

Impaired augmentation of left ventricular ejection fraction and myocardial blood flow with stress is associated with significant angina-associated functional limitation, health status, and dyspnea in patients who underwent positron emission tomography MPI, but not the frequency of their angina. Future studies should evaluate whether therapies that improve stress-induced abnormalities in systolic function and myocardial flow may improve patients' health status.

Stress myocardial perfusion imaging in patients presenting with syncope: Comparison of PET vs. SPECT

BACKGROUND

The role of myocardial perfusion imaging (MPI) in patients with suspected coronary artery disease (CAD) presenting with syncope is controversial. We aimed to determine diagnostic yield of MPI for evaluation of syncope in patients without known CAD, as a function of pre-test patient risk and test modality (PET vs SPECT).

METHODS

Between 1/2010 and 12/2016, 1324 consecutive patients presenting with syncope without known CAD underwent MPI with PET (n = 640) or SPECT (n = 684). Rates of abnormal MPI (summed difference score (SDS) > 2 or left ventricular ejection fraction (LVEF) reserve ≤ 0 for PET and SDS > 2 or post-stress LVEF ≤ 45% for SPECT) were determined among patients stratified by pre-test risk. In patients who were referred for coronary angiography, diagnostic yield of obstructive CAD was calculated in the overall cohort as well as in a propensity-matched cohort compared to patients without syncope.

RESULTS

Abnormal MPI was noted in 36.5% (201/551) of patients who had PET compared with 13.0% (87/671) who had SPECT (P < 0.001), which is largely related to higher comorbidity burden and greater pre-test CAD risk in the PET population. Among patients who had an abnormal MPI, 8.5% (47/551) with PET and 0.7% (5/671) with SPECT were found to have obstructive CAD if referred for coronary angiography. Patients at intermediate-high pre-test risk had a higher proportion of abnormal MPIs and obstructive CAD as compared to those at low risk in both the PET and SPECT cohorts. The rate of abnormal testing and diagnostic yield of PET MPI was similar and proportionate to pre-test likelihood among matched patients with and without syncope.

CONCLUSIONS

Among patients referred for PET MPI with syncope at an intermediate-high pre-test CAD risk, 1 in 3 had an abnormal MPI and 1 in 10 had obstructive CAD. The value of MPI was related to pre-test risk as opposed to the presence of syncope, and MPI testing with PET or SPECT in the low-risk population was low value.

Relative Prognostic Significance of Positron Emission Tomography Myocardial Perfusion Imaging Markers in Cardiomyopathy

BACKGROUND

Rubidium-82 positron emission tomography myocardial perfusion imaging provides measurements of perfusion, myocardial blood flow and reserve (MBFR), and changes in left ventricular ejection fraction (LVEF) at rest and peak stress. Although all of these variables are known to provide prognostic information, they have not been well studied in patients with heart failure due to reduced LVEF.

METHODS

Between 2010 and 2016, 1255 consecutive unique patients with LVEF≤40% were included in this study who underwent rubidium-82 positron emission tomography myocardial perfusion imaging and did not have subsequent revascularization within 90 days. Perfusion assessment was scored semiquantitatively, and LVEF reserve (stress-rest LVEF) and global MBFR (stress/rest MBF) were quantified using automated software. Cox proportional hazards models adjusted for 14 clinical and 7 test characteristics were used to define the independent prognostic significance of MBFR on all-cause mortality.

RESULTS

Of 1255 patients followed for a mean of 3.2 years, 454 (36.2%) died. After adjusting for clinical variables, the magnitude of fixed and reversible perfusion defects was prognostic of death (P=0.02 and 0.01, respectively), while the rest LVEF was not (P=0.18). The addition of LVEF reserve did not add any incremental value, while the addition of MBFR revealed incremental prognostic value (hazard ratio per 0.1 unit decrease in MBFR=1.08 [95% CI, 1.05-1.11], P<0.001) with fixed and reversible defects becoming nonsignificant (P=0.07 and 0.29, respectively). There was no interaction between MBFR and cause of cardiomyopathy (ischemic versus nonischemic).

CONCLUSIONS

In patients with a known cardiomyopathy who did not require early revascularization, reduced MBFR as obtained by positron emission tomography myocardial perfusion imaging is associated with all-cause mortality while other positron emission tomography myocardial perfusion imaging measures were not.

Correlation of Hepatic Steatosis Among Cohabitants Using Hounsfield Unit From Coronary Computed Tomography

Background

Individuals living in the same household are exposed to common risk factors. We hypothesized that living with someone who has fatty liver disease increases the risk of having the same disease.

Methods

This was a retrospective study that included pairs of men and women who shared the same residential addresses, underwent screening non-contrast computed tomography for coronary calcium scoring and had Hounsfield Unit density for liver and spleen in the field of view available for measurement. The primary goal was to determine the association between hepatic steatosis and living in the same household. Secondary end-points compared to body mass index, triglyceride levels, type 2 diabetes mellitus (T2DM) and hypertension.

Results

Out of 1,362 cohabitant pairs, there were 202 couples with either the male or female having hepatic steatosis and 10 cohabitant pairs with both the male and female having hepatic steatosis. In 1,150 cohabitant pairs out of 1,362, neither man nor woman had hepatic steatosis. Pearson correlation coefficient (r) for hepatic steatosis between cohabitant pairs was 0.122 (p-value: < 0.001), suggesting that no correlation was found. Elevated triglyceride levels were prevalent among cohabitant pairs with hepatic steatosis, when compared to pairs without hepatic steatosis (p-value < 0.05). Female gender and having a diagnosis of hepatic steatosis also showed a strong association with higher body mass index, T2DM and hypertension (p-value < 0.05).

Conclusion

Despite the assumption of exposure to similar environmental factors, our results did not show any correlation of hepatic steatosis among the cohabitants.

Acute Heart Failure From Coronary Cameral Fistula

A 40-year-old African American woman presented with dyspnea, orthopnea, weight gain, and ankle edema. She was admitted for acute decompensated heart failure. Coronary angiography revealed coronary cameral fistula. We used multiple imaging modalities to confirm the fistula’s pathway. Her left ventricular systolic function improved after repair of coronary cameral fistula. (Level of Difficulty: Beginner.)

Evolution of Diagnostic and Treatment Patterns of Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) may impart substantial morbidity and mortality, and novel imaging modalities are now available to aid in early diagnosis of this clinically silent disease. A better understanding of the clinical experience with CS is important. Twenty-eight patients were diagnosed with the aid of multimodality imaging techniques and were treated by a multidisciplinary team. Demographics, symptomatology, imaging, and therapeutic interventions were compiled from our referral center. In patients with CS, nuclear and MR techniques were often the first studies performed. Echocardiographic findings differed widely. Immunosuppressive therapy and cardiac devices were frequently used. Importantly, isolated CS was not an infrequent finding.

Safety and Clinical Impact of MRI in Patients with Non-MRI-conditional Cardiac Devices

Purpose

To explore the safety and clinical utility of MRI in participants with non-MRI-conditional cardiac implantable electronic devices, by establishing the Patient Registry of Magnetic Resonance Imaging in Non-Approved DEvices (PROMeNADe).

Materials and Methods

From September 2015 to June 2019, 532 participants (211 women) with a mean age of 69 years ± 14 (standard deviation) were enrolled prospectively in the PROMeNADe registry (ClinicalTrials.gov identifier: NCT03081364) and underwent a total of 608 MRI examinations (61 cardiac MRI examinations). All participants had device interrogations performed before and after each MRI. Pacemaker-dependent patients received asynchronous pacing. Patients with an implantable cardioverter defibrillator (ICD) had tachycardia therapies disabled during the MRI. An electrophysiology nurse monitored participants for any hemodynamic or rhythm abnormalities. Referring physicians were surveyed regarding the clinical utility of the MRI. Standard descriptive analyses included summary statistics with percentages and means.

Results

Cardiac devices included pacemakers (46%), ICDs (30%), cardiac resynchronization therapy (CRT) pacemakers (4%), and CRT defibrillators (17%), as well as abandoned leads (2%). Pacemaker-dependent patients comprised 27% of all MRI examinations. There were no patient- or device-related complications. Clinical utility surveys of MRI examinations were completed by 150 physicians. According to the survey responses, these MRI examinations changed the suspected diagnosis 25% of the time and changed suspected prognosis in 26% of participants, with planned medical or surgical treatment being changed 42% of the time.

Conclusion

This registry demonstrates that MRI examinations, including thoracic MRI examinations, can be performed safely in patients who have non-MRI-conditional devices, in pacemaker-dependent patients with ICDs, and in patients with abandoned leads. These MRI examinations can have a substantial impact on patient care, justifying the extensive resources used to perform them.Supplemental material is available for this article.© RSNA, 2020See also the commentary by Peshock in this issue.

Technetium pyrophosphate nuclear scintigraphy for cardiac amyloidosis: Imaging at 1 vs 3 hours and planar vs SPECT/CT

BACKGROUND

Multi-societal consensus recommendations endorse both planar and single photon emission tomographic (SPECT) image acquisitions for the evaluation of cardiac amyloidosis. However, the correlation between planar and SPECT findings and the optimal timing of image acquisitions remain uncertain.

METHODS

This is an analysis of 109 consecutive patients who underwent technetium pyrophosphate nuclear scintigraphy for the evaluation of cardiac amyloidosis. Patients were imaged at 1 and 3 hours after radiotracer injection using both planar and SPECT/CT, and the correlations between imaging protocols were compared.

RESULTS

In the overall cohort (median age 77 years, 75% male), 33 patients had radiotracer localized to the myocardium on SPECT/CT images. There was strong correlation between 1- and 3-hour planar heart-to-contralateral lung ratios (mean difference 0.07, r = 0.94). However, there was discordance between planar image interpretation (based upon semiquantitative score and H/CL ratio) and myocardial localization of radiotracer on SPECT/CT in 17 patients (16%). The pattern of SPECT/CT uptake was identical at 1 and 3 hours in all cases (32 diffuse, 1 focal).

CONCLUSION

These data support the recommendation that SPECT/CT should be obtained in addition to planar images when performing nuclear scintigraphy for the detection of cardiac amyloidosis. A 1-hour planar and SPECT/CT protocol appears optimal.

Extent of Myocardial Ischemia on Positron Emission Tomography and Survival Benefit With Early Revascularization

BACKGROUND

Prior studies with single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) have shown a survival benefit with early revascularization in patients with >10% to 12.5% ischemic myocardium. The relationship among positron emission tomography (PET)-derived extent of ischemia, early revascularization, and survival is unknown.

OBJECTIVES

The purpose of this study was to evaluate the association among percent ischemia on PET MPI, revascularization, and survival.

METHODS

A total of 16,029 unique consecutive patients who were undergoing Rubidium-82 rest-stress PET MPI from 2010 to 2016 were included. Patients with known cardiomyopathy and nondiagnostic perfusion results were excluded. Percent ischemic myocardium was estimated from a 17-segment model. Propensity scoring was used to account for nonrandomized referral to early revascularization (90 days of PET). A Cox model was developed, adjusting for propensity scores for early revascularization and percent ischemia, and an interaction between ischemia and early revascularization was tested.

RESULTS

Median follow-up was 3.7 years. Overall, 1,277 (8%) patients underwent early revascularization and 2,493 (15.6%) died (738 cardiac). Nearly 37% of patients (n = 5,902) had ischemia, with 13.5% (n = 2,160) having ≥10%. In propensity-adjusted analyses, there was a significant interaction between ischemia and early revascularization (p < 0.001 for all-cause and cardiac death), such that patients with greater ischemia had improved survival with early revascularization, with a potential ischemia threshold at 5% (upper limit 95% confidence interval at 10%). There was no differential association between ischemia and early revascularization on death based on history of known coronary artery disease (interaction p = 0.72).

CONCLUSIONS

In a contemporary cohort of patients undergoing PET MPI, patients with greater ischemia had a survival benefit from early revascularization. On exploratory analyses, this threshold was lower than that previously reported for SPECT. These findings require future validation in prospective cohorts or trials.

Stabilization of Early Duchenne Cardiomyopathy With Aldosterone Inhibition: Results of the Multicenter AIDMD Trial

Background Duchenne muscular dystrophy incurs nearly universal dilated cardiomyopathy by the third decade of life, preceded by myocardial damage and impaired left ventricular strain by cardiac magnetic resonance. It has been shown that (1) mineralocorticoid receptor antagonist therapy with spironolactone attenuated damage while maintaining function when given early in a mouse model and (2) low-dose eplerenone stabilized left ventricular strain in boys with Duchenne muscular dystrophy and evident myocardial damage but preserved ejection fraction. We hypothesized that moderate-dose spironolactone versus eplerenone would provide similar cardioprotection in this first head-to-head randomized trial of available mineralocorticoid receptor antagonists, the AIDMD (Aldosterone Inhibition in Duchenne Muscular Dystrophy) trial. Methods and Results This was a multicenter, double-blind, randomized, noninferiority trial. Subjects were randomized to eplerenone, 50 mg, or spironolactone, 50 mg, orally once daily for 12 months. The primary outcome was change in left ventricular systolic strain at 12 months. Among 52 enrolled male subjects, aged 14 (interquartile range, 12-18) years, spironolactone was noninferior to eplerenone (∆strain, 0.4 [interquartile range, -0.4 to 0.6] versus 0.2 [interquartile range, -0.2 to 0.7]; P=0.542). Renal and pulmonary function remained stable in both groups, and no subjects experienced serious hyperkalemia. Infrequent adverse events included gynecomastia in one subject in the spironolactone arm and facial rash in one subject in the eplerenone arm. Conclusions In boys with Duchenne muscular dystrophy and preserved left ventricular ejection fraction, spironolactone added to background therapy is noninferior to eplerenone in preserving contractile function. These findings support early mineralocorticoid receptor antagonist therapy as effective and safe in a genetic disease with high cardiomyopathy risk. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02354352.

Treatment of recurrent isolated right atrial metastatic cavitary mass from breast cancer with radiation therapy: A case report and review of literature

The heart is a destination for metastases of various types of primary tumors, with lung, breast, melanoma, and mesothelioma being the most common types. Recurrent isolated cardiac metastasis presenting as a cavitary mass is rare. We present a case of recurrent isolated cavitary metastatic mass to the right atrium in a patient with the history of breast cancer who presented with new-onset atrial fibrillation. The patient successfully received radiation therapy with the resolution of the mass confirmed on repeat echocardiography.

Impact of sex on the heart's metabolic and functional responses to diabetic therapies

Increased myocardial lipid delivery is a determinant of myocardial substrate metabolism and function in animal models of type 2 diabetes (T2DM). Sex also has major effects on myocardial metabolism in the human heart. Our aims were to determine whether 1) sex affects the myocardial metabolic response to lipid lowering in T2DM, 2) altering lipid [fatty acid (FA) or triglyceride] delivery to the heart would lower the elevated myocardial lipid metabolism associated with T2DM, and 3) decreasing lipid delivery improves diastolic dysfunction in T2DM. To this end, we studied 78 T2DM patients (43 women) with positron emission tomography, echocardiography, and whole body tracer studies before and 3 mo after randomization to metformin (MET), metformin + rosiglitazone (ROSI), or metformin + Lovaza (LOV). No treatment main effects were found for myocardial substrate metabolism, partly because men and women often had different responses to a given treatment. In men, MET decreased FA clearance, which was linked to increased plasma FA levels, myocardial FA utilization and oxidation, and lower myocardial glucose utilization. In women, ROSI increased FA clearance, thereby decreasing plasma FA levels and myocardial FA utilization. Although LOV did not change triglyceride levels, it improved diastolic function, particularly in men. Group and sex also interacted in determining myocardial glucose uptake. Thus, in T2DM, different therapeutic regimens impact myocardial metabolism and diastolic function in a sex-specific manner. This suggests that sex should be taken into account when designing a patient's diabetes treatment.

Sex and type 2 diabetes: obesity-independent effects on left ventricular substrate metabolism and relaxation in humans

Patients with type 2 diabetes (T2DM), particularly women, are at risk for heart failure. Myocardial substrate metabolism derangements contribute to cardiac dysfunction in diabetic animal models. The purpose of this study was to determine the effects of diabetes and sex on myocardial metabolism and diastolic function in humans, separate from those of obesity. Thirty-six diabetic subjects (22 women) and 36 nondiabetic, BMI-matched subjects (21 women) underwent positron emission tomography (myocardial metabolism) and echocardiography (structure, function). Myocardial blood flow and oxygen consumption (MVO(2)) were higher in women than men (P = 0.003 and <0.0001, respectively). Plasma fatty acid (FA) levels were higher in diabetics (vs. obese, P < 0.003) and sex and diabetes status interacted in its prediction (P = 0.03). Myocardial FA utilization, oxidation, and esterification were higher and percent FA oxidation lower in diabetics (vs. obese, P = 0.0004, P = 0.007, P = 0.002, P = 0.02). FA utilization and esterification were higher and percent FA oxidation lower in women (vs. men, P = 0.03, P = 0.01, P = 0.03). Diabetes and sex did not affect myocardial glucose utilization, but myocardial glucose uptake/plasma insulin was lower in the diabetics (P = 0.04). Left ventricular relaxation was lower in diabetics (P < 0.0001) and in men (P = 0.001), and diabetes and sex interacted in its prediction (P = 0.03). Sex, T2DM, or their interaction affect myocardial blood flow, MVO(2), FA metabolism, and relaxation separate from obesity's effects. Sexually dimorphic myocardial metabolic and relaxation responses to diabetes may play a role in the known cardiovascular differences between men and women with diabetes.

Potentiation of abnormalities in myocardial metabolism with the development of diabetes in women with obesity and insulin resistance

BACKGROUND

Because studies in animal models of type-2 diabetes mellitus (DM) show that excessive myocardial fatty acid (FA) metabolism (at the expense of glucose metabolism) cause cardiac dysfunction, we hypothesized that women with DM would have more FA and less glucose myocardial metabolism than normal or even obese (OB) women.

RESEARCH DESIGN AND METHODS

Women who were lean volunteers (NV) (N = 14; age 35 ± 17 years, body mass index 23 ± 1 kg/m(2)), OB (N = 28;31 ± 6 years, BMI 39 ± 7 kg/m2), and DM (n = 22; 54 ± 11 years, BMI 38 ± 5 kg/m2) were studied. Cardiac positron emission tomography was performed for the determination of myocardial blood flow, oxygen consumption, FA and glucose metabolism. Cardiac work was measured by echocardiography and efficiency by the ratio of work to myocardial oxygen consumption.

RESULTS

Fractional glucose uptake was comparable between NV and OB but lower in DM (P < .05 versus NV). Myocardial FA utilization and oxidation were both higher in DM compared with NV and OB (P < .0001). Myocardial FA utilization and oxidation had positive correlations with HOMA (R = 0.35, P = .005 and R = 0.40, P = .001, respectively) whereas fractional glucose uptake exhibited an inverse correlation (R = -.31, P = .01). Cardiac work and efficiency were similar among the three groups.

CONCLUSIONS

In women, the presence of OB and DM compared with OB alone is associated with a greater reliance on myocardial FA metabolism at the expense of glucose metabolism. These perturbations in myocardial metabolism are not associated in a decline left ventricular efficiency or function suggesting that the metabolic perturbations may precede an eventual decline left ventricular function as is seen in animal models of DM.

Contraindications and side effects of commonly used medications in coronary CT angiography

For certain clinical applications, coronary CT angiography (CCTA) has become a useful tool for the noninvasive evaluation of coronary artery atherosclerosis. To optimize image quality in CCTA, medications are often given prior to scanning to slow the heart rate or distend the arteries. These medications have side effects and are contraindicated in certain patient populations. Metoprolol is the ß-blocker of choice in CCTA, and it has been shown to be effective in achieving the goal heart rate of less than 65 beats per minute for CCTA and in minimizing variability of heart rate. It is contraindicated in patients with hypotension or high degree AV block, and it must be used with caution in patients with asthma or obstructive pulmonary disease, patients with decompensated heart failure, and those with vasospastic or vasoocclusive disease. Diltiazem, the calcium channel blocker of choice in CCTA, is a reasonable alternative for heart control, particularly in patients with asthma or bronchospastic disease, and patients with orthotopic heart transplants that have been sympathetically denervated. Sublingual nitroglycerin is especially useful in order to dilate distal arteries to improve stenosis visibility. However, it is contraindicated in patients on erectile dysfunction medications and those with severe anemia. It must be used cautiously in patients with aortic stenosis or other preload-dependant cardiac pathologies.

Reconstructed 4-chamber views compared with axial imaging for assessment of right ventricular enlargement on CT pulmonary angiograms

PURPOSE

To test the hypothesis that right enlargement assessed from right ventricular/left ventricular (RV/LV) dimension ratios of computed tomographic (CT) angiograms are equivalent irrespective of whether measured on axial views or reconstructed 4-chamber views.

METHODS

RV/LV dimension ratios were calculated from measurements on axial views, manually reconstructed 4-chamber views and computer generated reconstructed 4-chamber views of CT angiograms in 152 patients with PE.

RESULTS

Paired readings of the axial view and manually reconstructed 4-chamber view showed agreement with RV/LV > or =1 or RV/LV <1 in 114 of 127 (89.8%). Paired readings also showed agreement in 119 of 127 (93.7%) with axial views and computer generated reconstructed 4-chamber views. The McNemar test showed no statistically significant difference between assessments of RV enlargement (RV/LV > or = 1) with any method.

CONCLUSION

Right ventricular enlargement can be determined from axial views on CT angiograms, which are readily and immediately available, without obtaining 4-chamber reconstructed views.

Assessing cardiac CT--advantages & current limitations. Part II: Clinical utility

The media's frenzy towards the imaging capabilities of 64-slice cardiac computed tomography (CCT) is not without cause. CCT allows non-invasive visualization of the coronary arteries, coronary artery bypass grafts, and the presence of atherosclerosis. CCT is not limited to the assessment of coronary vasculature, but can yield information about other causes of chest pain such as aortic dissection, or pericardial disease. Other applications for the high resolution scanner include anatomical assessment of congenital heart disease, post myocardial infarction complications, pulmonary embolism and aortic and peripheral arterial atherosclerosis and aneurysm evaluation. Finally, non-contrast CCT allows for quantification of coronary calcification which provides important prognostic information. As CT technology evolves, it is paramount for clinicians to understand when it is clinically appropriate to use CT coronary angiography (CTCA).

Assessing cardiac CT: advantages & current limitations. Part I: technical advancements & considerations

The media's frenzy towards the imaging capabilities of 64-slice cardiac computed tomography (CCT) is not without cause. ECG-gating and improved resolution allow non-invasive visualization of the coronary arteries, coronary artery bypass grafts, and the presence of atherosclerosis. However, clinicians should understand CCT image acquisition process and the current CCT limitations. Those limitations include poor image quality with the morbidly obese, coronary artery motion on images of those with irregular and/or fast heart rates, potential intravenous contrast related complications, and high radiation exposure. As CT technology evolves, with faster acquisition and higher resolution, it is paramount for clinicians to understand the applications and limitations of this imaging method.

Approach to the athlete with thoracic aortic disease

Sports medicine specialists have a unique opportunity to identify individuals who may be at risk for thoracic aortic disease. These patients may have physical features such as tall stature and long limbs (which typify Marfan syndrome), but also lend themselves to participation in competitive athletics. These individuals are at increased risk of sudden death from aortic dissection. Avoiding or delaying aortic complications involves recognition and screening, medications, and prophylactic surgery when the aorta reaches a size threshold. A key feature in management is recognition of the aortic disease and avoiding those sports or exercises that place excess strain or stress on the aorta. Care involves multiple disciplines including primary care physicians, cardiologists, geneticists, ophthalmologists, and orthopedic and cardiac surgeons; however, the sports medicine specialist is often instrumental in guiding the athlete toward proper diagnosis and safe activities in an effort to avoid catastrophic complications.

Structure and growth of tumors: the effect of Cartesian, cylindrical, and spherical geometries

We present results of numerical simulations of a mathematical model simulating mass transfer in the development of a tumor, resulting in its encapsulation and lobulation. A modified generation term that reflects the population pressure on growth leads to nodular tumor growth. Simulations have been carried out in one dimensional Cartesian, cylindrical, and spherical geometries. Important differences between the three cases have been found. Simulation results in spherical geometry suggest the lobes near the center of the tumor to be larger than those near the capsule wall.