Deep-Learning-Based Whole-Lung and Lung-Lesion Quantification Despite Inconsistent Ground Truth: Application to Computerized Tomography in SARS-CoV-2 Nonhuman Primate Models

RATIONALE AND OBJECTIVES

Animal modeling of infectious diseases such as coronavirus disease 2019 (COVID-19) is important for exploration of natural history, understanding of pathogenesis, and evaluation of countermeasures. Preclinical studies enable rigorous control of experimental conditions as well as pre-exposure baseline and longitudinal measurements, including medical imaging, that are often unavailable in the clinical research setting. Computerized tomography (CT) imaging provides important diagnostic, prognostic, and disease characterization to clinicians and clinical researchers. In that context, automated deep-learning systems for the analysis of CT imaging have been broadly proposed, but their practical utility has been limited. Manual outlining of the ground truth (i.e., lung-lesions) requires accurate distinctions between abnormal and normal tissues that often have vague boundaries and is subject to reader heterogeneity in interpretation. Indeed, this subjectivity is demonstrated as wide inconsistency in manual outlines among experts and from the same expert. The application of deep-learning data-science tools has been less well-evaluated in the preclinical setting, including in nonhuman primate (NHP) models of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection/COVID-19, in which the translation of human-derived deep-learning tools is challenging. The automated segmentation of the whole lung and lung lesions provides a potentially standardized and automated method to detect and quantify disease.

MATERIALS AND METHODS

We used deep-learning-based quantification of the whole lung and lung lesions on CT scans of NHPs exposed to SARS-CoV-2. We proposed a novel multi-model ensemble technique to address the inconsistency in the ground truths for deep-learning-based automated segmentation of the whole lung and lung lesions. Multiple models were obtained by training the convolutional neural network (CNN) on different subsets of the training data instead of having a single model using the entire training dataset. Moreover, we employed a feature pyramid network (FPN), a CNN that provides predictions at different resolution levels, enabling the network to predict objects with wide size variations.

RESULTS

We achieved an average of 99.4 and 60.2% Dice coefficients for whole-lung and lung-lesion segmentation, respectively. The proposed multi-model FPN outperformed well-accepted methods U-Net (50.5%), V-Net (54.5%), and Inception (53.4%) for the challenging lesion-segmentation task. We show the application of segmentation outputs for longitudinal quantification of lung disease in SARS-CoV-2-exposed and mock-exposed NHPs.

CONCLUSION

Deep-learning methods should be optimally characterized for and targeted specifically to preclinical research needs in terms of impact, automation, and dynamic quantification independently from purely clinical applications.

Magnetic Resonance Imaging for Monitoring of Hepatic Disease Induced by Ebola Virus: a Nonhuman Primate Proof-of-Concept Study

Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD). However, the role of hepatic involvement in EVD progression is understudied. Medical imaging in established animal models of EVD (e.g., nonhuman primates [NHPs]) can be a strong complement to traditional assays to better investigate this pathophysiological process in vivo and noninvasively. In this proof-of-concept study, we used longitudinal multiparametric magnetic resonance imaging (MRI) to characterize liver morphology and function in nine rhesus monkeys after exposure to Ebola virus (EBOV). Starting 5 days postexposure, MRI assessments of liver appearance, morphology, and size were consistently compatible with the presence of hepatic edema, inflammation, and congestion, leading to significant hepatomegaly at necropsy. MRI performed after injection of a hepatobiliary contrast agent demonstrated decreased liver signal on the day of euthanasia, suggesting progressive hepatocellular dysfunction and hepatic secretory impairment associated with EBOV infection. Importantly, MRI-assessed deterioration of biliary function was acute and progressed faster than changes in serum bilirubin concentrations. These findings suggest that longitudinal quantitative in vivo imaging may be a useful addition to standard biological assays to gain additional knowledge about organ pathophysiology in animal models of EVD. IMPORTANCE Severe liver impairment is a well-known hallmark of Ebola virus disease (EVD), but the contribution of hepatic pathophysiology to EVD progression is not fully understood. Noninvasive medical imaging of liver structure and function in well-established animal models of disease may shed light on this important aspect of EVD. In this proof-of-concept study, we used longitudinal magnetic resonance imaging (MRI) to characterize liver abnormalities and dysfunction in rhesus monkeys exposed to Ebola virus. The results indicate that in vivo MRI may be used as a noninvasive readout of organ pathophysiology in EVD and may be used in future animal studies to further characterize organ-specific damage of this condition, in addition to standard biological assays.

Computed Tomography Imaging for Monitoring of Marburg Virus Disease: a Nonhuman Primate Proof-Of-Concept Study

Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. The pathogenesis of MVD remains poorly understood, partially due to the low number of cases that can be studied, the absence of state-of-the-art medical equipment in areas where cases are reported, and limitations on the number of animals that can be safely used in experimental studies under maximum containment animal biosafety level 4 conditions. Medical imaging modalities, such as whole-body computed tomography (CT), may help to describe disease progression in vivo, potentially replacing ethically contentious and logistically challenging serial euthanasia studies. Towards this vision, we performed a pilot study, during which we acquired whole-body CT images of 6 rhesus monkeys before and 7 to 9 days after intramuscular MARV exposure. We identified imaging abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to clinical, virological, and gross pathological hallmarks of MVD in this animal model. Quantitative image analysis indicated hepatomegaly with a significant reduction in organ density (indicating fatty infiltration of the liver), splenomegaly, and edema that corresponded with gross pathological and histopathological findings. Our results indicated that CT imaging could be used to verify and quantify typical MVD pathogenesis versus altered, diminished, or absent disease severity or progression in the presence of candidate medical countermeasures, thus possibly reducing the number of animals needed and eliminating serial euthanasia. IMPORTANCE Marburg virus (MARV) is a highly virulent zoonotic filovirid that causes Marburg virus disease (MVD) in humans. Much is unknown about disease progression and, thus, prevention and treatment options are limited. Medical imaging modalities, such as whole-body computed tomography (CT), have the potential to improve understanding of MVD pathogenesis. Our study used CT to identify abnormalities in the liver, spleen, and axillary lymph nodes that corresponded to known clinical signs of MVD in this animal model. Our results indicated that CT imaging and analyses could be used to elucidate pathogenesis and possibly assess the efficacy of candidate treatments.

Longitudinal analyses using 18F-Fluorodeoxyglucose positron emission tomography with computed tomography as a measure of COVID-19 severity in the aged, young, and humanized ACE2 SARS-CoV-2 hamster models

This study compared disease progression of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in three different models of golden hamsters: aged (≈60 weeks old) wild-type (WT), young (6 weeks old) WT, and adult (14-22 weeks old) hamsters expressing the human-angiotensin-converting enzyme 2 (hACE2) receptor. After intranasal (IN) exposure to the SARS-CoV-2 Washington isolate (WA01/2020), 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography with computed tomography (18F-FDG PET/CT) was used to monitor disease progression in near real time and animals were euthanized at pre-determined time points to directly compare imaging findings with other disease parameters associated with coronavirus disease 2019 (COVID-19). Consistent with histopathology, 18F-FDG-PET/CT demonstrated that aged WT hamsters exposed to 105 plaque forming units (PFU) developed more severe and protracted pneumonia than young WT hamsters exposed to the same (or lower) dose or hACE2 hamsters exposed to a uniformly lethal dose of virus. Specifically, aged WT hamsters presented with a severe interstitial pneumonia through 8 d post-exposure (PE), while pulmonary regeneration was observed in young WT hamsters at that time. hACE2 hamsters exposed to 100 or 10 PFU virus presented with a minimal to mild hemorrhagic pneumonia but succumbed to SARS-CoV-2-related meningoencephalitis by 6 d PE, suggesting that this model might allow assessment of SARS-CoV-2 infection on the central nervous system (CNS). Our group is the first to use (18F-FDG) PET/CT to differentiate respiratory disease severity ranging from mild to severe in three COVID-19 hamster models. The non-invasive, serial measure of disease progression provided by PET/CT makes it a valuable tool for animal model characterization.

Toward the determination of sensitive and reliable whole-lung computed tomography features for robust standard radiomics and delta-radiomics analysis in a nonhuman primate model of coronavirus disease 2019

Purpose

We propose a method to identify sensitive and reliable whole-lung radiomic features from computed tomography (CT) images in a nonhuman primate model of coronavirus disease 2019 (COVID-19). Criteria used for feature selection in this method may improve the performance and robustness of predictive models.

Approach

Fourteen crab-eating macaques were assigned to two experimental groups and exposed to either severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or a mock inoculum. High-resolution CT scans were acquired before exposure and on several post-exposure days. Lung volumes were segmented using a deep-learning methodology, and radiomic features were extracted from the original image. The reliability of each feature was assessed by the intraclass correlation coefficient (ICC) using the mock-exposed group data. The sensitivity of each feature was assessed using the virus-exposed group data by defining a factor R that estimates the excess of variation above the maximum normal variation computed in the mock-exposed group. R and ICC were used to rank features and identify non-sensitive and unstable features.

Results

Out of 111 radiomic features, 43% had excellent reliability ( ICC > 0.90 ), and 55% had either good ( ICC > 0.75 ) or moderate ( ICC > 0.50 ) reliability. Nineteen features were not sensitive to the radiological manifestations of SARS-CoV-2 exposure. The sensitivity of features showed patterns that suggested a correlation with the radiological manifestations.

Conclusions

Features were quantified and ranked based on their sensitivity and reliability. Features to be excluded to create more robust models were identified. Applicability to similar viral pneumonia studies is also possible.

Characteristic and quantifiable COVID-19-like abnormalities in CT- and PET/CT-imaged lungs of SARS-CoV-2-infected crab-eating macaques (Macaca fascicularis)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing an exponentially increasing number of coronavirus disease 19 (COVID-19) cases globally. Prioritization of medical countermeasures for evaluation in randomized clinical trials is critically hindered by the lack of COVID-19 animal models that enable accurate, quantifiable, and reproducible measurement of COVID-19 pulmonary disease free from observer bias. We first used serial computed tomography (CT) to demonstrate that bilateral intrabronchial instillation of SARS-CoV-2 into crab-eating macaques (Macaca fascicularis) results in mild-to-moderate lung abnormalities qualitatively characteristic of subclinical or mild-to-moderate COVID-19 (e.g., ground-glass opacities with or without reticulation, paving, or alveolar consolidation, peri-bronchial thickening, linear opacities) at typical locations (peripheral>central, posterior and dependent, bilateral, multi-lobar). We then used positron emission tomography (PET) analysis to demonstrate increased FDG uptake in the CT-defined lung abnormalities and regional lymph nodes. PET/CT imaging findings appeared in all macaques as early as 2 days post-exposure, variably progressed, and subsequently resolved by 6-12 days post-exposure. Finally, we applied operator-independent, semi-automatic quantification of the volume and radiodensity of CT abnormalities as a possible primary endpoint for immediate and objective efficacy testing of candidate medical countermeasures.

Cranial Vena Cava Syndrome in Guinea Pigs with Chronic Jugular Vein Catheters

Guinea pigs are a premier small animal model for infectious disease research, and chronic indwelling venous access ports may be used to facilitate various procedures. Here we report catheter-related lesions in 5 uninfected Dunkin-Hartley guinea pigs with chronic jugular vein catheters used for imaging studies. Three guinea pigs were found dead with no premonitory signs. At necropsy, there was severe bilateral pulmonary atelectasis due to 20 to 29 mL of pleural effusion resulting from catheter-related thrombosis and cranial vena cava syndrome. In addition, one of these 3 guinea pigs had a polymicrobial catheter infection with abscessation. A 4th clinically normal guinea pig was euthanized at the end of the study, having spontaneously lost its catheter 7 mo prior, and had 17 mL of pleural effusion. The 5th guinea pig was euthanized following pooling of contrast material around the distal catheter in the cranial vena cava on CT. By histology, affected animals had recent and remote thrombosis or fibrosis (or both) of the cranial vena cava and right atrial wall, with osseous and cartilaginous metaplasia. Cranial vena cava syndrome should be considered as a differential for dyspnea or death in chronically catheterized laboratory animals.

Acute transient tachypnea following gadoxetate administration in a rhesus macaque during contrast-enhanced magnetic resonance imaging

During an infectious disease modeling study, a rhesus macaque (Macaca mulatta), experienced acute transient tachypnea including transient severe motion during the 70-second phases of serial contrast-enhanced magnetic resonance imaging of the abdomen. This same animal experienced transient severe motion during all but 2 of the 8 scans of the year-long study. This animal was the only animal in the study (1 of 12) to have this reaction to gadoxetate; the animal also vomited after the contrast injection once on day 146 of the study. On day 86, a different contrast agent (gadobutrol) was used, and the reaction did not occur. No treatment was required for any conditions relating to the reaction due to the self-limited nature. This type of reaction has not yet been reported in veterinary subjects before and is likely to be idiosyncratic after first exposure. However, this reaction should not be life threatening, and other contrast agents can be used if acute transient tachypnea does occur.

Working Together to Address Women's Health in Research and Drug Development: Summary of the 2017 Women's Health Congress Preconference Symposium

Historically, women have been underrepresented in clinical research, requiring physicians to extrapolate medical recommendations for women from clinical research done in cohorts consisting predominantly of male participants. While government-funded clinical research has achieved gender parity in phase-3 clinical trials across many biomedical disciplines, improvements are still needed in several facets of women's health research, such as the inclusion of women in early-phase clinical trials, the inclusion of pregnant women and women with physical and intellectual disabilities, the consideration of sex as a biological variable in preclinical research, and the analysis and reporting of sex and gender differences across the full biomedical research continuum. The National Institutes of Health (NIH) Office of Research on Women's Health and the Office of Women's Health of the U.S. Food and Drug Administration (FDA) cosponsored a preconference symposium at the 25th Annual Women's Health Congress, held in Arlington, VA in April, 2017, to highlight gains made and remaining needs regarding the representation of women in clinical research, to introduce innovative procedures and technologies, and to outline revised policy for future studies. Six speakers presented information on a range of subjects related to the representation of women in clinical research and federal initiatives to advance precision medicine. Topics included the following: the return on investment from the NIH-funded Women's Health Initiative; progress in including women in clinical trials for FDA-approved drugs and products; the importance of clinical trials in pregnant women; FDA initiatives to report drug safety during pregnancy; the NIH-funded All of Us Research Program; and efforts to enhance FDA transparency and communications, including the introduction of Drug Trials Snapshots. This article summarizes the major points of the presentations and the discussions that followed.

Relation between the Framingham Risk Score, coronary calcium, and incident coronary heart disease among low-risk men

The Prospective Army Coronary Calcium Project is evaluating the predictive value of coronary artery calcium (CAC) in unselected, healthy, lower-risk, 40- to 50-year-old men. Although this study has found that coronary calcium is predictive of future coronary heart disease (CHD), criteria are needed to narrow the screening population to those in whom CAC measurement is most efficient (vs unselected screening of low-risk men). In 1,634 unselected volunteer men (mean age 42 years, mean 10-year CHD Framingham risk score [FRS] 4.6%, CAC prevalence 22.4%), we evaluated the independent relation between CAC and incident CHD over 5.6 years including hard events (hospitalized unstable angina, myocardial infarction, and CHD death) and coronary revascularization. The cohort was analyzed in tertiles of FRS for the relation between CAC and CHD outcomes. FRS tertile cutpoints were 0% to 3% (n = 547), >3% to 5% (n = 547), and >5% (n = 540) 10-year CHD risk. Over a mean follow-up of 5.6 +/- 1.5 years (range 1.0 to 8.3), there were 22 total CHD events, including 14 hard events and 8 revascularizations. Most events occurred in the highest FRS tertile (n = 14) versus the middle (n = 6) and lowest (n = 2) risk tertiles (p = 0.005). CAC and CHD events increased across FRS tertiles. Only in the highest FRS tertile was there a significant relation between CAC and CHD outcomes (hazard ratio 9.3). In conclusion, CAC screening could be of benefit in refining risk assessment of low-risk men, but only when the FRS exceeds approximately 5%.

Sixty-four-slice CT angiography to determine the three dimensional relationships of vascular and soft tissue wounds in lower extremity war time injuries

This article analyzes the use and benefits of the 64-slice CT scanner in determining the 3D relationships of vascular and soft tissue wounds in lower extremity war time injuries. A brief overview of CT scanning is given as well as the techniques used to produce the images needed for diagnosis. The series follows two similar cases of war time injury patients at the Walter Reed Army Medical Center. The first case is a 30-year-old active duty male, who presented with multiple trauma from a motor vehicle accident because of an improvised explosive device (IED) blast, sustaining substantial lower extremity injuries. The second case is a 34-year-old active duty male, who presented with multiple trauma blast injuries. Both cases were of interest because the vasculature was found to be very close to the surface of the wound, which put the arteries at risk for rupture and for iatrogenic injury during repeated debridements.

Does prolonged warfarin exposure potentiate coronary calcification in humans? Results of the warfarin and coronary calcification study

Warfarin has been shown to accelerate vascular calcification in experimental animals, and possibly humans, through inhibition of the vitamin K-dependent protein matrix gla protein, a potent inhibitor of tissue calcification. We performed a cross-sectional analysis of the extent of coronary artery calcification (CAC) in patients without coronary heart disease, currently taking or referred for warfarin therapy. The primary end point was severity of CAC measured by electron beam computed tomography attributed to duration of warfarin use, after adjustment for cardiovascular risk factors. Seventy patients (46 men, mean age 68 +/- 13 years) were enrolled from three groups of warfarin use duration: (1) <6 months (n = 31, mean duration 1 +/- 1 months), (2) 6-24 months (n = 11), and (3) >24 months (n = 28, mean 67 +/- 40 months). Overall, the mean total CAC score (Agatston) was 293 +/- 560: group 1 (175 +/- 285), group 2 (289 +/- 382), and group 3 (426 +/- 789). In univariate analysis, there was a nonsignificant trend to increased CAC with increasing warfarin exposure (P = 0.18). Bivariate analysis revealed no correlation between warfarin duration and CAC score (r = 0.075, P = 0.537). Linear regression for the independent variable coronary calcium score controlling for warfarin treatment duration and intensity (duration of warfarin use months x mean INR), Framingham risk score, and creatinine clearance showed that only the Framingham risk score was associated with CAC (P = 0.001). Among patients without known coronary heart disease, duration of warfarin exposure was not associated with extent of coronary calcification.

The relationship between subclinical atherosclerosis and electrocardiographic abnormalities as biomarkers of cardiovascular risk

Electrocardiographic findings indicating myocardial disease, such as left ventricular hypertrophy or ST-T wave abnormalities, or the presence of coronary artery calcium, indicating atherosclerotic coronary artery disease, are both biomarkers of future cardiovascular (CV) risk. Although the risk factors for myocardial and coronary artery disease are similar, their concomitant expression has implications for CV disease screening and prevention programmes. The relationship between the resting 12-lead ECG and subclinical atherosclerosis measured as coronary artery calcium (CAC) with electron beam tomography was examined in 937 healthy participants (aged 40-50 years) enrolled in a CV risk screening study. Electrocardiograms and CAC were interpreted in blinded fashion, using standard criteria. An abnormal ECG was coded in 268 (28.6%) participants, most commonly left ventricular hypertrophy (3.1%), delayed precordial R wave transition (5.7%), T-wave abnormalities (10.0%) and intraventricular conduction delay (10.4%). Although abnormal ECG findings were associated with CV risk variables, the prevalence of any CAC was similar in subjects with any ECG finding (43 of 268, 16.0%) compared with those with normal ECGs (125 of 669, 18.7%, p =NS). In a logistic model controlling for CV risk factors including systolic blood pressure, low-density lipoprotein cholesterol (LDL-C), body mass index (BMI), glycosylated haemoglobin, race, age and gender, significant associations with CAC were found for LDL-C, race and BMI. There was no significant relationship between CAC and ECG abnormalities (odds ratio 0.80, 95% confidence interval 0.54-1.20). In conclusion, electrocardiographic abnormalities and subclinical calcified atherosclerosis were not significantly associated with each other in this middle-aged screening population. This suggests these two biomarkers may be complementary towards broader detection of latent CV risk.

Progression of calcified coronary atherosclerosis: Relationship to coronary risk factors and carotid intima-media thickness

BACKGROUND

The determinants of coronary artery calcium (CAC) progression are not well understood. Prior studies have shown a limited relationship between CAC progression and traditional coronary risk factors. We hypothesized that the extent of non-calcified atherosclerosis detected using carotid intima-media thickness (CIMT) would predict progression of calcified atherosclerosis.

METHODS

One hundred and eighty healthy male participants (mean age 47.9) with CAC from the Prospective Army Coronary Calcium (PACC) project volunteered to undergo a second EBCT scan, risk factor assessment, lab testing, and CIMT assessment 4.2+/-1.3 years after their original scan. All results were independently examined, blinded to baseline data. A change in CAC score >or=15% per year was defined as clinically significant progression.

RESULTS

CAC progression occurred in 60.2%. Compared to participants without progression, those with progression had higher triglycerides, LDL and total cholesterol and Framingham risk scores, but similar blood pressure, HDL cholesterol, blood glucose, C-reactive protein, fibrinogen, and body mass index. CIMT was significantly higher among those with versus without CAC progression (0.660 mm versus 0.603 mm; P=0.001). Each quintile of increasing CIMT was independently associated with a 35% increase in the odds of CAC progression (P=0.01), after controlling for the Framingham risk score and C-reactive protein.

CONCLUSION

Among middle-aged men with coronary calcium, increasing extent of non-calcified atherosclerosis is strongly associated with coronary artery calcium progression over 4 years.

Subclinical Calcified Atherosclerosis in Men and Its Association With Family History of Premature Coronary Heart Disease in First‐ and Second‐Degree Relatives

The authors examined the associations between coronary artery calcification and a family history of premature coronary heart disease in either first-degree (immediate family) or second-degree (grandparents, aunts, uncles) relatives in 1619 asymptomatic healthy men ages 40-50 years. The prevalence of any coronary artery calcification was 19.3% in participants (n=1102) with no family history, 26.6% in those with a first-degree family history (n=203; 12.5%), 26.5% in those with a second-degree family history (n=215, 13.3%), and 30.3% with both (n=99, 6.1%, p=0.003). After controlling for the Framingham risk score, body mass index, and ethnicity, all categories of family history were significant predictors of coronary artery calcification. The odds ratios for coronary artery calcification associated with a first- (1.49; p=0.026) and second-degree (1.41; p=0.049) family history of coronary heart disease were similar. Clinical coronary risk assessments should broadly include an assessment of premature coronary heart disease in both first- and second-degree relatives.

Antioxidant Vitamin Intake and Subclinical Coronary Atherosclerosis

Numerous studies have evaluated the association between antioxidants and coronary atherosclerosis but have been limited by its study among individuals with advanced atherosclerosis. The authors studied 865 consecutive patients, 39-45 years of age, without known coronary artery disease and presenting for a periodic physical examination. Antioxidant intake was assessed with the Block Dietary Questionnaire, and coronary atherosclerosis was identified by measuring coronary artery calcification using electron beam computed tomography. The mean age was 42 (+/-2), 83% were male, and the prevalence of coronary artery calcification was 20%. Vitamin supplements were used by 56% of the participants, and the mean (+/-SD) daily intake (dietary plus supplemental) of vitamins A, C, and E were 1683 mg (+/-1245), 371 mg (+/-375), and 97 mg (+/-165), respectively. There was no significant correlation between coronary artery calcification score and individual vitamin or total antioxidant vitamin intake, even after adjusting for traditional cardiac risk factors. The highest quartile of vitamin E was positively associated with calcification (odds ratio=1.77; 95% confidence interval, 1.02-3.06). Antioxidant vitamin intake is not significantly related to coronary artery calcification, implying that there is no effect on the development of early coronary atherosclerosis. High doses of vitamin E may confer an increased risk of calcified atherosclerosis.

Conventional, Emerging, Heredity, Lifestyle, and Psychosocial Coronary Risk Factors: Relationships to Subclinical Atherosclerosis

The authors examined the relationship between calcified coronary atherosclerosis and an array of cardiovascular risk factors in sequential logistic models to determine the extent to which these markers overlap in their identification of patients at risk for developing coronary heart disease. The prevalence of coronary artery calcium using electron beam computed tomography was 19.4% in this cross-sectional study of a prospective, consecutive, screening cohort of 1999 healthy United States Army personnel (aged 39-50 years). The proportion of the total variance of coronary artery calcium explained by sequential logistic models incorporating conventional, emerging, hereditary, lifestyle, and psychosocial cardiovascular risk variables increased progressively from 9.7% to 14.5%. The best-fit logistic model for the prediction of coronary artery calcium identified age, male gender, Framingham risk score, total cholesterol, high-density lipoprotein cholesterol, triglycerides, smoking, a family history of coronary heart disease, white race, physical inactivity, and lower depression scores as significant independent correlates of coronary artery calcium. These data indicate that the explanatory power of models for atherosclerosis can be significantly improved with the use of emerging, heredity, lifestyle, and psychosocial factors. The large residual variance, however, supports the potential of atherosclerosis imaging to incrementally and independently identify coronary heart disease risk.

Vitamin K1 intake and coronary calcification

OBJECTIVES

The activity of matrix Gla-protein (MGP), a potent inhibitor of vascular calcification, is dependent on carboxylation using vitamin K as a co-factor. In animals, low intake of total vitamin K has been shown to accelerate vascular calcification via the MGP mechanism. This has led to the hypothesis that low levels of dietary vitamin K intake may be a risk factor for accelerated vascular calcification in humans due to decreased MGP activity. Additionally, some authors have suggested that current recommended daily intake values for vitamin K might be insufficient to fully inhibit vascular calcification via the MGP mechanism. The aim of this study was to examine the relationship between dietary vitamin K1 (the most prevalent dietary form of vitamin K) intake and premature coronary artery calcification (CAC) in an asymptomatic screening population.

METHODS

We conducted a prospective study of 807 consecutive active-duty US Army personnel, 39-45 years of age, without known coronary heart disease. Vitamin K1 intake was measured with the Block Dietary Questionnaire and CAC was identified using electron-beam computed tomography (EBCT).

RESULTS

We found no significant correlation between CAC score and vitamin K1 intake (r = 0.132, P = 0.106). Multivariate analysis with adjustment for cardiac risk factors showed no association between dietary vitamin K1 intake and CAC.

CONCLUSIONS

Dietary vitamin K1 (phylloquinone) intake appears to be unrelated to premature coronary calcification in a screening population. Further investigation into the relationship of vascular calcification and other forms of vitamin K1 (menaquinones) is indicated.

Alcohol intake is not associated with subclinical coronary atherosclerosis

BACKGROUND

The inverse relation between alcohol intake and clinical coronary artery disease (CAD) is well established, although the mechanisms remain speculative. We studied the relation between alcohol intake and subclinical CAD to assess the possible role of alcohol in atherogenesis.

METHODS

We conducted a prospective study of 731 consecutive, consenting, active-duty US Army personnel (39 to 45 years of age) without known CAD who were undergoing a routine physical examination. Each participant was surveyed with the validated Block dietary questionnaire, which included detailed information on alcohol intake as wine, beer, or liquor. Subclinical CAD was determined by means of electron beam computed tomography to quantify coronary artery calcification (CAC).

RESULTS

The mean age was 42 (+/-2); 83% were male, 71% were white, and 82% were college graduates. The prevalence of CAC was 18.6% (mean CAC score = 12 +/- 69). Twenty-two percent drank alcohol daily, with an average of 2.4 drinks per day. Systolic blood pressure was correlated with number of drinks per day (r = 0.10, P = .025). Among drinkers, HDL was weakly correlated with daily alcohol consumption (r = 0.10, P = .025). There was no relation between the CAC score and the alcohol intake as measured by drinks per day (OR, 1.02; 95% CI, 0.64 to 1.63; 1.13, 0.59 to 2.15; 1.26, 0.69 to 2.59, for less than 1, 1 to 2, and more than 2 drinks per day, respectively). Stratified analyses based on type of alcohol and multivariate analyses indicated no independent relation between any type or quantity of alcohol intake and the presence or extent of coronary calcification.

CONCLUSIONS

Alcohol intake does not appear to be inversely related to subclinical CAC, implying that previous observations of a protective effect of alcohol on clinical CAD may involve factors related to plaque stability rather than atherogenesis.

Impact of electron beam tomography, with or without case management, on motivation, behavioral change, and cardiovascular risk profile: a randomized controlled trial

CONTEXT

Although the use of electron beam tomography (EBT) as a motivational tool to change behavior is practiced, its efficacy has not been studied.

OBJECTIVE

To assess the effects of incorporating EBT as a motivational factor into a cardiovascular screening program in the context of either intensive case management (ICM) or usual care by assessing its impact over 1 year on a composite measure of projected risk.

DESIGN

Randomized controlled trial with a 2 x 2 factorial design and 1 year of follow-up.

SETTING AND PARTICIPANTS

A consecutive sample of 450 asymptomatic active-duty US Army personnel aged 39 to 45 years stationed within the Washington, DC, area and scheduled to undergo a periodic Army-mandated physical examination were enrolled between January 1999 and March 2001 (mean age, 42 years; 79% male; 66 [15%] had coronary calcification; mean [SD] predicted 10-year coronary risk, 5.85% [3.85%]).

INTERVENTIONS

Patients were randomly assigned to 1 of 4 intervention arms: EBT results provided in the setting of either ICM (n = 111) or usual care (n = 119) or EBT results withheld in the setting of either ICM (n = 124) or usual care (n = 96).

MAIN OUTCOME MEASURE

The primary outcome measure was change in a composite measure of risk, the 10-year Framingham Risk Score (FRS).

RESULTS

Comparing the groups who received EBT results with those who did not, the mean absolute risk change in 10-year FRS was +0.30 vs +0.36 (P =.81). Comparing the groups who received ICM with those who received usual care, the mean absolute risk change in 10-year FRS was -0.06 vs +0.74 (P =.003). Improvement or stabilization of cardiovascular risk was noted in 157 patients (40.2%). In multivariable analyses predicting change in FRS, after controlling for knowledge of coronary calcification, motivation for change, and multiple psychological variables, only the number of risk factors (odds ratio, 1.42; 95% confidence interval, 1.16-1.75 for each additional risk factor) and receipt of ICM (odds ratio, 1.62; 95% confidence interval, 1.04-2.52) were associated with improved or stabilized projected risk.

CONCLUSIONS

Using coronary calcification screening to motivate patients to make evidence-based changes in risk factors was not associated with improvement in modifiable cardiovascular risk at 1 year. Case management was superior to usual care in the management of risk factors.

Preoperative risk stratification using electron beam computed tomography in elective vascular surgery: relationship to clinical risk prediction and postoperative complications

We studied the utility of electron beam computed tomography as a screening test for the cardiovascular risk of elective vascular surgery. In 45 patients undergoing principally carotid and aortic surgical procedures, coronary artery calcification was prevalent and severe, and related to the clinically predicted cardiovascular risk of the procedure. However, only the clinically predicted surgical risk, and not coronary artery calcification, was related to the incidence of perioperative cardiovascular complications.

Electron beam computed tomography screening of the coronary arteries: experience with 3,263 patients at Walter Reed Army Medical Center

The U.S. Department of Defense desires to reduce the impact of coronary atherosclerosis on its active duty, retired, and dependent populations. Electron beam computed tomography (EBCT) is currently the best way to noninvasively image the coronary arteries directly. Between August 1997 and February 1999, a total of 3,263 patients were scanned by EBCT in the Radiology Department at Walter Reed Army Medical Center. Scans were performed on 2,415 men (74%) and 848 women (26%). The most common age group was 50 to 54 years (25%). Coronary calcification was found in approximately half of the patients (46%), and the magnitude of the score was strongly associated with age and male gender. Average scores increased exponentially with age, doubling every 7 years. In men, average scores ranged from 17 units in those aged 35 to 39 years to 842 in those older than 70 years old. In women, average scores ranged from 1 in those 35 to 39 years to 162 in those older than 70 years. Significant numbers of patients fell into the high-risk categories, with 8% of men in their 40s, 20% of men in their 50s, 33% of men in their 60s, and 49% of men in their 70s with high scores. Scores of more than 400 units were seen in 368 patients (8%) overall. There is a large amount of coronary calcium present in military personnel and their dependents, in patterns that are consistent with previous studies. Many patients had very high scores that are consistent with advanced coronary artery disease. EBCT should play a central role in the identification of occult calcific atherosclerosis of the coronary arteries in military, retired, and dependent patients.

C-reactive protein is not associated with the presence or extent of calcified subclinical atherosclerosis

BACKGROUND

Both high-sensitivity C-reactive protein (hsCRP) and electron beam computed tomography (EBCT) coronary artery calcification (CAC) are valid markers of cardiovascular risk. It is unknown whether hsCRP is a marker of atherosclerotic burden or whether it reflects a process (eg, inflammatory fibrous cap degradation) leading to acute coronary events.

METHODS

A nested case-control study was performed of 188 men enrolled in the Prospective Army Coronary Calcium study. The serum hsCRP levels (latex agglutination assay) were evaluated in subjects with CAC (CAC score >0, n = 94) and compared with age- and smoking status-matched control subjects (CAC score 0, n = 94).

RESULTS

Levels of hsCRP in the highest quartile were related to the following coronary risk factors: smoking status, low-density lipoprotein cholesterol, body mass index, glycosylated hemoglobin, fibrinogen, and homocysteine. The mean hsCRP level was similar in cases (+CAC, 0.20 +/- 0.22 mg/dL) and controls (-CAC, 0.19 +/- 0.21 mg/dL; P =.81) and was unrelated to the log-transformed CAC score (r < 0.01, P =.91). Multivariable analysis controlling for standard risk factors, aspirin, and statin therapy found only that low-density lipoprotein cholesterol was related to CAC.

CONCLUSIONS

Despite associations with standard and emerging cardiovascular risk factors, hsCRP is unrelated to the presence and extent of calcified subclinical atherosclerosis. This implies that CAC (a disease marker) and hsCRP (a process marker) may be complementary for the prediction of cardiovascular risk.

Lack of correlation between psychological factors and subclinical coronary artery disease

BACKGROUND

The relation between psychological variables and clinically evident coronary artery disease has been studied extensively, although the potential mechanisms of such a relation remain speculative. We studied the relation between multiple psychological variables and subclinical coronary artery disease to assess the possible role of such variables in atherogenesis.

METHODS

We conducted a prospective study of 630 consecutive consenting, active-duty U.S. Army personnel, 39 to 45 years of age, without known coronary artery disease. Each participant was assessed for depression, anxiety, somatization, hostility, and stress. Subclinical coronary artery disease was identified by electron-beam computed tomography.

RESULTS

The mean (+/-SD) age of the subjects was 42+/-2 years; 82 percent were male, and 72 percent were white. The prevalence of coronary-artery calcification was 17.6 percent (mean calcification score, 10+/-49). The prevalence of prior or current psychiatric disorders was 12.7 percent. There was no correlation between the coronary-calcification score and the scores measuring depression (r= -0.07, P=0.08), anxiety (r=-0.07, P=0.10), hostility (r=-0.07, P=0.10), or stress (r=-0.002, P=0.96). Somatization (the number and severity of durable physical symptoms) was inversely correlated with calcification scores (r=-0.12, P=0.003), even after we controlled for age and sex. In multivariate logistic-regression models, a somatization score greater than 4 (out of a possible 26) was independently associated with the absence of any coronary-artery calcification (odds ratio, 0.49; 95 percent confidence interval, 0.25 to 0.96).

CONCLUSIONS

Our data suggest that depression, anxiety, hostility, and stress are not related to coronary-artery calcification and that somatization is associated with the absence of calcification.

Multidisciplinary airway stent team: a comprehensive approach and protocol for tracheobronchial stent treatment

Tracheobronchial stents are being used with increasing frequency to treat major airway obstruction from both malignant and benign processes. Traditionally, stents have been placed via rigid bronchoscopy, flexible bronchoscopy, or fluoroscopy by members of various individual disciplines. We describe a novel multidisciplinary airway stent team (MAST) protocol for tracheobronchial stent placement and endoscopic management of major airway obstruction. A patient with symptoms of airway obstruction is generally first evaluated with a computed tomography scan and a videotaped flexible bronchoscopy. These studies are reviewed by the team otolaryngologist, pulmonologist, and interventional radiologist. A treatment plan, including the type and location of stents and the need for adjuvant therapies, is formulated. Stent placement is performed in the operating room under general anesthesia. Rigid bronchoscopy, with flexible bronchoscopy and fluoroscopy as needed, allows precise stent placement and the best use of various therapeutic methods. The MAST protocol combines the skills, knowledge, and unique therapeutic options of specialists from otolaryngology, pulmonology, and interventional radiology. This approach allows optimal stent placement and the use of other endobronchial therapies, including laser ablation, balloon dilation, photodynamic therapy, cryotherapy, and brachytherapy. A protocol with representative case reports is presented, along with a review and comparison of several of our most commonly used stents. Otolaryngologists who practice bronchoesophagoscopy, by virtue of their operative skill and knowledge of airway management, are well equipped to become leaders of MASTs and are encouraged to initiate MASTs at their institutions.

Rationale and design of the Prospective Army Coronary Calcium (PACC) Study: utility of electron beam computed tomography as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty United States Army Personnel

BACKGROUND

Screening for coronary artery calcium with electron beam computed tomography (EBCT) has potential diagnostic and prognostic implications. Most prior research on this technology has been done on selected, high-risk populations. The goal of the Prospective Army Coronary Calcium (PACC) study is to determine the utility of EBCT for the detection of coronary calcium as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty personnel undergoing the United States Army's Cardiovascular Screening Program.

METHODS AND RESULTS

Three study designs will be used to address the objectives of this investigation: (1) a cross-sectional study of 2000 unselected, consecutive participants to determine the prevalence and extent of coronary calcification in the 40- to 45-year-old Army population, (2) a randomized, controlled trial with a 2 x 2 factorial design involving 1000 participants to assess the impact of EBCT information on several dimensions of patient behavior, with and without intensive risk factor case management, and (3) a prospective cohort study of 2000 participants followed for at least 5 years to establish the relation between coronary calcification and cardiovascular events in an unselected, "low-risk" (by conventional standards) Army population.

CONCLUSIONS

We present a review of the literature on the clinical utility of EBCT, with a focus on the limited research in young, asymptomatic populations. The details of the PACC study (begun in October1998) are presented. The results of the PACC study will determine the clinical utility of EBCT in young, asymptomatic patients.

Evaluation of the aortic root by MRI: insights from patients with homozygous familial hypercholesterolemia

BACKGROUND

In homozygous familial hypercholesterolemia (HFH), the aortic root is prone to develop atherosclerotic plaque at an early age. However, the aortic wall and plaque have not yet been assessed in this condition by MRI. We evaluated the aortic root by use of MRI in 17 HFH patients and 12 normal control subjects in a prospective, blinded, controlled study.

METHODS AND RESULTS

Morphological assessment of the aortic root was done with spin-echo and gradient-echo MRI scanning. Comparisons were made with a number of measures of disease severity, including cholesterol-year score, calcium score on electron-beam CT (EBCT), and size of Achilles tendon xanthomas. Atherosclerotic plaque, visible on fat-suppressed images but never on water-suppressed images, was present in 9 HFH patients (53%). Supravalvular aortic stenosis was present in 7 patients with HFH (41%). Maximum supravalvular aortic wall thickness was significantly greater and OD and lumen cross-sectional area (CSA) were smaller in patients than in control subjects (P=0.006, 0.0005, and 0.06, respectively). Maximum wall thickness was associated with a greater calcium score on electron-beam CT (P=0.02). Although the cumulative exposure of the aortic root to cholesterol (the cholesterol-year score) was significantly correlated with the Achilles tendon CSA and vascular calcification, this score did not correlate with the wall thickness or aortic CSA.

CONCLUSIONS

This study not only demonstrates the utility of MRI for detecting and characterizing aortic root atherosclerotic plaque and supravalvular aortic stenosis in HFH patients but also suggests that the LDL receptor plays a direct or indirect role in aortic mural development and vascular growth.

Aortic hypoplasia in homozygous familial hypercholesterolemia

Diagnosis of hypoplastic aortic root with ultrafast computed tomography provides important clinical information in homozygous familial hypercholesterolemic patients with supravalvular aortic stenosis.

Prospective sonographic evaluation of interleukin-2-induced changes in the gallbladder

PURPOSE

To describe the changes in the gallbladder induced by interleukin-2 (IL-2) therapy and to correlate the findings with the clinical course.

MATERIALS AND METHODS

Twenty-five men with human immunodeficiency virus (HIV) infection were examined prospectively with right upper quadrant ultrasonography (US) before and after receiving IL-2 therapy. Four patients also underwent US after a second course of IL-2. The gallbladder was evaluated for wall thickening, echotexture, and intramural and pericholecystic fluid. Correlation was made between the clinical signs and symptoms, IL-2 dose, CD4 cell count, and the US appearance of the gallbladder.

RESULTS

There was significant correlation between symptoms of right upper quadrant pain during IL-2 therapy and US abnormalities of the gallbladder, including an increase in wall thickening (P = .012) and the development of intramural (P = .015) and pericholecystic (P = .006) fluid. More severe abnormalities were seen with higher IL-2 doses. All symptoms resolved with cessation of IL-2 therapy. In patients who underwent repeat US, the gallbladder reverted to a normal appearance. No correlation was found between the CD4 cell count and the development of symptoms or the US appearance of the gallbladder.

CONCLUSION

IL-2-induced changes resolve rapidly with cessation of therapy, and no surgical intervention is needed. These changes can be avoided or reduced by decreasing the IL-2 dose during subsequent cycles.

Safety and efficacy of strength training in patients with sporadic inclusion body myositis

We studied the effects of a 12-week progressive resistance strength training program in weakened muscles of 5 patients with sporadic inclusion body myositis (IBM). Strength was evaluated with Medical Research Council (MRC) scale ratings and quantitative isometric and dynamic tests. Changes in serum creatine kinase (CK), lymphocyte subpopulations, muscle size (determined by magnetic resonance imaging), and histology in repeated muscle biopsies were examined before and after training. After 12 weeks, the values of repetition maximum improved in the least weakened muscles, 25-120% from baseline. This dynamic effect was not captured by MRC or isometric muscle strength measurements. Serum CK, B cells, T-cell subsets, and NK cells remained unchanged. Repeat muscle biopsies did not reveal changes in the number and degree of degenerating fibers or inflammation. The size of the trained muscles did not change. We conclude that a supervised progressive resistance training program in IBM patients can lead to gains in dynamic strength of the least weak muscles without causing muscle fatigue and muscle injury or serological, histological, and immunological abnormalities. Even though the functional significance of these gains is unclear, this treatment modality is a safe and perhaps overlooked means of rehabilitation of IBM patients.

Crystalluria and urinary tract abnormalities associated with indinavir

BACKGROUND

Indinavir, a protease inhibitor widely used to treat patients with HIV infection, has been associated with nephrolithiasis. Distinctive urinary crystals and a spectrum of urologic disorders were noted in patients receiving indinavir.

OBJECTIVE

To determine the composition of urinary crystals and the frequency of asymptomatic crystalluria and urinary tract symptoms in patients receiving indinavir.

PATIENTS

Patients with HIV infection who were enrolled in studies conducted at the National Institutes of Health.

MEASUREMENTS

Microscopic urinalysis, high-performance liquid chromatography (HPLC) and mass spectrometry of urinary crystals and stones, and clinical evaluation of patients with urologic symptoms.

RESULTS

Of 240 patients receiving indinavir, 142 provided urine specimens for analysis. Twenty-nine (20%) had crystals consisting of plate-like rectangles and fan-shaped or starburst forms. Mass spectrometry and HPLC confirmed that these crystals were composed of indinavir. Of 40 patients who were not receiving indinavir, none had similar crystals (P < 0.001). Nineteen of the 240 patients receiving indinavir (8%) developed urologic symptoms. Of these, 7 (3%) had nephrolithiasis and the other 12 (5%) had previously undescribed syndromes: crystalluria associated with dysuria and crystalluria associated with back or flank pain. Four of the patients with the latter syndrome had radiographic evidence of intrarenal sludging.

CONCLUSIONS

Indinavir forms characteristic crystals in the urine. This crystalluria may be associated with dysuria and urinary frequency, with flank or back pain associated with intrarenal sludging, and with the classic syndrome of renal colic.

Distinctions between CD8+ and CD4+ T-cell regenerative pathways result in prolonged T-cell subset imbalance after intensive chemotherapy

Rapid recovery of CD4+ T cells after intensive chemotherapy is limited by an age-dependent decline in thymopoiesis. Here we sought to determine whether similar limitations exist for CD8+ T-cell regeneration. After intensive chemotherapy, CD8+ T cells had a faster effective doubling time than CD4+ T cells (median, 12.6 v 28.2 days, P < .05). Accordingly, at 3 months posttherapy, mean CD8+ T-cell number had returned to baseline, whereas mean CD4+ T-cell number was only 35% of pretherapy values (P < .05). These differences were primarily due to very rapid expansion of CD8+CD57+ and CD8+CD28- subsets. At 3 months posttherapy, there was no relationship between age and CD8+ T-cell number (R = -.02), whereas CD4+ T-cell number was inversely related to age (R = -.66) and there were no discernible differences in CD8+ recovery among patients with or without thymic enlargement, whereas CD4+ recovery was enhanced in patients with thymic enlargement after chemotherapy (P < .01). Therefore thymic-independent pathways of T-cell regeneration appear to rapidly regenerate substantial numbers of CD8+, but not CD4+ T cells, resulting in prolonged T-cell subset imbalance after T-cell depletion. These inherent distinctions between CD4+ v CD8+ T-cell regeneration may have significant implications for immunotherapeutic strategies undertaken to eradicate minimal residual neoplastic disease after cytoreductive chemotherapy.

Lipoprotein lipase correlates positively and hepatic lipase inversely with calcific atherosclerosis in homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (FH) is a rare genetic disorder that leads to premature atherosclerosis due to a defective LDL receptor. There is, however, a large degree of phenotypic heterogeneity at the level of atherosclerosis even in patients with identical mutations of the LDL receptor protein. Lipoprotein lipase (LPL) and hepatic lipase (HL) are crucial enzymes in lipoprotein metabolism, and both have been proposed as having proatherogenic as well as antiatherogenic effects. To evaluate a potential role for these enzymes in the severity of atherosclerosis, we correlated postheparin LPL mass and activity as well as HL activity with the volume of total calcific atherosclerosis (heart and thoracic aorta), coronary artery calcific atherosclerosis, and Achilles tendon width as measured by computed tomography in 15 FH homozygotes. LPL dimer and total mass were positively correlated with all three parameters (r = .65 to .87, P < .01) as was LPL activity (r = .52 to .63, P < .05). HL activity was negatively correlated with total and coronary artery calcified lesion volume (r = -.55 to .57, P < .05). In a multiple regression model of the coronary artery lesion volume, LPL dimer mass and HL activity together accounted for 84% of the variability (r = .92, P < .0001). In a multiple regression model of the total calcified lesion volume, HL activity, total cholesterol, age, and LPL dimer mass together accounted for 85% of the variability (r = .92, P = .0005). These data demonstrate a significant correlation of LPL mass and activity with the extent of calcific atherosclerosis in homozygous FH. It is not clear whether LPL is the cause or consequence of the observed correlation, but if the association between LPL and coronary artery lesions is also present in patients with other genetic dyslipoproteinemias, LPL could constitute a new risk factor for cardiovascular disease.

Strength gains without muscle injury after strength training in patients with postpolio muscular atrophy

We evaluated changes in the dynamic and isometric strength in the newly weakened quadriceps muscles and asymptomatic triceps muscles of 6 patients with postpolio muscular atrophy (PPMA) after 10 weeks of progressive resistance strength training. Alterations in muscle size were determined with magnetic resonance imaging. Serum creatine kinase levels were measured throughout training, and histological signs of muscle injury and changes in muscle fiber size and types were assessed with muscle biopsies before and after training. Exercise training led to an increase in dynamic strength of 41% and 61% for the two knee extensor tests, and 54% and 71% for the two elbow extensor tests. Up to 20% of the improvement was maintained 5 months after cessation of training. Isometric strength, whole muscle cross-sectional areas of quadriceps and triceps muscles, and serum muscle enzymes did not change. No destructive histopathological changes were noted in the repeat muscle biopsies, and no consistent changes in muscle fiber size or fiber type percentages were observed. These results demonstrate that a supervised resistance training program can lead to significant gains in dynamic strength of both symptomatic and asymptomatic muscles of PPMA patients without serological or histological evidence of muscular damage.

Relation of cholesterol-year score to severity of calcific atherosclerosis and tissue deposition in homozygous familial hypercholesterolemia

The high concentrations of low-density lipoprotein cholesterol in plasma lead to accelerated atherosclerosis in patients homozygous for familial hypercholesterolemia (FH). We addressed the hypothesis that lipid deposition in the arterial vasculature and in nonvascular tissues in these patients correlates with both the duration and severity of their hypercholesterolemia. The severity of calcific atherosclerosis was defined by calcification scores and a calcified volume determined by electron beam tomography. The extent of tendinous xanthomatosis was quantitated by computed tomography. A cholesterol-year score was calculated based on the age and the yearly mean serum cholesterol concentration of each patient. Seventeen patients homozygous for FH were followed up. The average total cholesterol concentration in the study group was 780 +/- 231 mg/dl (20.2 mmol/L), and the cholesterol-year scores ranged from 2,172 mg-year/dl (56 mmol-year/L) to 32,260 mg-year/dl (834 mmol-year/L). Achilles tendon width (r=0.86) and cross-sectional area (r=0.81; both p <0.001) were best correlated with the cholesterol-year score. In addition, the coronary (r=0.61; p<0.05), ostial (r=0.45; p<0.05), and total (r= 0.77; p<0.001) calcification atherosclerosis scores all were best correlated with the cholesterol-year score. Calcific atherosclerosis was not observed in these patients until the cholesterol-year score exceeded 10,000 mg-year/dl (260 mmol-year/L). These findings establish a direct association of cholesterol-year with extravascular lipid deposition in tissues of patients with FH. The cholesterol-year score may be useful in defining the risk of atherosclerosis in patients with more common forms of hypercholesterolemia.

Morphing radiologic images: applications on a desktop computer

OBJECTIVE

Morphing is an image processing technology that transforms one image into another by generating a series of intermediate synthetic images. The ability to perform morphing, once restricted to high-end graphics workstations, is now widely available for desktop computers. We investigated the potential use of morphing for displaying radiographic images.

MATERIALS AND METHODS

Morphing was performed with commercially available software (Morph 2.5; Gryphon Software, San Diego, CA) on a Macintosh (Apple Computer, Cupertino, CA) computer. Images from 26 patients with serial radiologic studies were selected, digitized, and morphed. Key points and key surfaces were identified on the images to improve the quality of the morph movie, a process that took approximately 15 min. The images were then morphed into a continuous Quick Time (Apple) movie lasting 5-7 sec. When a sequence contained more than two images, a single movie incorporating all the images was created. The intervals between segments of the movie were made proportional to the actual time elapsed between the images. Images obtained with different techniques (positron emission tomography and MR imaging) were also morphed. Three observers judged the quality of the morph movies as satisfactory, good, or excellent.

RESULTS

Twenty of the 26 movies were judged to be of good or excellent quality. The movie format allowed the rapid display of multiple images in a concise 5- 7-sec time frame. Moreover, the movie allowed the recognition of several simultaneous processes more easily than was possible with static images. Morphing two images of the same anatomic site using different techniques (MR imaging and positron emission tomography) proved to be a simple method of superimposing images.

CONCLUSION

Morphing is a readily available and easily learned technique for displaying serial studies. The movie format is a more interesting, intuitive, and concise summary of events than can be provided by serial static images. Morphing may be useful for displaying large numbers of serial images in a short time for occasions such as clinical conferences or teaching purposes.

Age, thymopoiesis, and CD4+ T-lymphocyte regeneration after intensive chemotherapy

BACKGROUND

Inadequate reconstitution of CD4+ T lymphocytes is an important clinical problem complicating chemotherapy, human immunodeficiency virus infection, and bone marrow transplantation, but relatively little is known about how CD4+ T lymphocytes regenerate. There are two main possibilities: bone marrow-derived progenitors could reconstitute the lymphocyte population using a thymus-dependent pathway, or thymus-independent pathways could predominate. Previous studies have suggested that the CD45RA glycoprotein on CD4+ T lymphocytes is a marker for progeny generated by a thymus-dependent pathway.

METHODS

We studied 15 patients 1 to 24 years of age who had undergone intensive chemotherapy for cancer. The absolute numbers of CD4+ T lymphocytes in peripheral blood and the expression of CD45 isoforms (CD45RA and CD45RO) on these lymphocytes were studied serially during lymphocyte regeneration after the completion of therapy. Radiographic imaging of the thymus was performed concomitantly.

RESULTS

There was an inverse relation between the patients' ages and the CD4+ T-lymphocyte counts six months after therapy was completed (r = -0.92). The CD4+ recovery correlated quantitatively with the appearance of CD45RA+CD4+ T lymphocytes in the blood (r = 0.64). There was a higher proportion of CD45RA+CD4+ T lymphocytes in patients with thymic enlargement after chemotherapy than in patients without such enlargement (two-sided P = 0.015).

CONCLUSIONS

Thymus-dependent regeneration of CD4+ T lymphocytes occurs primarily in children, whereas even young adults have deficiencies in this pathway. Our results suggest that rapid T-cell regeneration requires residual thymic function in patients receiving high-dose chemotherapy.

Coronary artery calcification: assessment with electron beam CT and histomorphometric correlation

PURPOSE

To assess the reliability of electron beam computed tomography (CT) in the detection of calcific deposits in coronary arteries.

MATERIALS AND METHODS

The authors quantitatively evaluated a total of 4,298 segments of coronary arteries with electron beam CT and histomorphometry.

RESULTS

Regression analysis of the electron beam CT calcium score versus histomorphometric calcium area produced an r2 value of .92 (r = .96; P < .0001). Ninety-three percent (78 of 84) of all coronary arteries with stenosis of 76%-100% contained calcific deposits, and 20% (17 of 83) of all coronary arteries with stenosis of 0%-50% contained calcific deposits.

CONCLUSION

The amount of calcific deposits detected with electron beam CT correlates highly with histomorphometric measurements. Also, the amount of calcific deposits correlates well with the degree of coronary artery stenosis. Electron beam CT, therefore, is a promising noninvasive technique that can help depict the presence and extent of atherosclerotic plaques.

Coronary artery disease: prediction with in vitro electron beam CT

PURPOSE

To investigate the potential to predict coronary artery disease with electron beam computed tomography (CT).

MATERIALS AND METHODS

Fifty heart specimens were examined with electron beam CT and histomorphometric techniques to measure calcific deposits as a percentage of blockage.

RESULTS

In group A specimens (from cadavers of patients with symptomatic coronary artery disease), calcific deposits were identified at electron beam CT in 41% (584 of 1,426) of all segments of coronary arteries; in group B specimens (with asymptomatic coronary artery disease), in 24% (369 of 1,535) of all segments; and in the normal control specimens, in 4% (47 of 1,337) of all segments; segments (group A vs control specimens, P < .0001; group B vs control specimens, P = .02). On the basis of logistic regression analysis, coronary artery disease would be predicted if the average electron beam CT calcium score exceeds 0.32. The sensitivity and specificity of electron beam CT in the detection of calcific deposits per coronary artery was 94% and 76%, respectively.

CONCLUSION

The electron beam CT calcium score appears to be an effective predictor of coronary artery disease.

Detection and quantitation of calcific atherosclerosis by ultrafast computed tomography in children and young adults with homozygous familial hypercholesterolemia

Ultrafast computed tomography (CT) is a new method for detecting calcific lesions in the coronary arteries. The ability of CT to detect and quantify coronary artery atherosclerosis in children and young adults at risk for malignant atherogenesis was evaluated. A total of 11 consecutive familial hypercholesterolemic (FH) homozygotes (3 to 37 years old) participated. Untreated total cholesterol concentrations were 488 to 1277 mg/dL (12.7 to 33.2 mmol/L). Angiography detected significant lesions in 7 of 11 patients. CT detected calcific atherosclerosis in all 9 of the patients older than 12 years of age, including all those with angina. CT was more sensitive in detecting aortic root and coronary ostial lesions, where atherosclerosis first appears in homozygous FH. The volume of calcification (in cubic millimeters) correlated with the severity and duration of the hypercholesterolemia (r = .62, P < .05) as well as with the presence of angina (P < .05). All patients with angina (7 of 7) had > 150 mm3 of calcified volume, whereas only 1 of 4 asymptomatic patients had a volume score > 150 mm3. We conclude that (1) coronary and aortic calcium phosphate deposits are common in young FH homozygotes; (2) these deposits are associated with the presence of angiographic stenoses, as has been seen in adults with coronary atherosclerosis; and (3) aortic calcific deposits are more common than calcific coronary lesions.

Symptomatic interleukin-2-induced cholecystopathy in patients with HIV infection

OBJECTIVE

This study reports the clinical and radiologic findings in seven patients infected with HIV who had 10 consecutive episodes of symptomatic cholecystopathy induced by infusion of interleukin-2.

SUBJECTS AND METHODS

Ten episodes of right upper quadrant pain associated with gallbladder wall thickening were seen in seven of 29 HIV-infected patients who received IV interleukin-2. Patients received 6-18 million IU/day of continuous interleukin-2 infusion for 5 days. Patients with right upper quadrant pain underwent sonographic examinations, which were interpreted prospectively. Medical records and previous sonographic studies were reviewed retrospectively. Follow-up was obtained through outpatient visits and sonography.

RESULTS

Right upper quadrant pain during these 10 episodes of cholecystopathy usually developed 4-5 days after starting infusion of interleukin-2. Sonography during that time showed gallbladder wall thickening (mean thickness, 12.4 mm; range, 5-18 mm) and a wide variety of sonographic appearances. Tenderness during sonography was focal in six episodes, diffuse in one, and absent in three. Sludge was identified in one episode; calculi were not seen. Findings on radionuclide biliary scans were normal in three cases. Symptoms abated rapidly in every case after infusion of interleukin-2 was reduced or stopped. No surgery was necessary. When treatment was repeated, three patients had recurrent episodes, with clinical courses and sonographic aberrations showing little variance from the initial episodes. Follow-up sonography in three episodes showed a maximal thickness of the gallbladder wall of 4 mm. No patient had a history or laboratory evidence of intrinsic biliary disease.

CONCLUSION

Symptomatic thickening of the gallbladder wall during infusion of interleukin-2 can exactly mimic other forms of acalculous cholecystitis, except that when associated with interleukin-2 the thickening is rapidly reversible and surgery is not required. Radionuclide scans can be useful in clinical decision making. The process appears to be benign, and cessation of interleukin-2 therapy, along with close clinical observation, appears to be the appropriate treatment.

Successful surgical management of neutropenic enterocolitis in two patients with severe aplastic anemia. Case reports and review of the literature

We describe two patients with severe aplastic anemia in whom neutropenic enterocolitis developed while they were undergoing treatment at the National Institutes of Health. Both patients had progressive symptoms while receiving optimal medical management and both underwent and survived surgical intervention despite continued prolonged neutropenia in the perioperative period. This experience contrasts with six cases reported in the literature and suggests that surgery can be employed even in patients with profound neutropenia. Thus, in patients who remain persistently septic or who develop clinical deterioration despite medical management or who have other indications for surgical intervention, neutropenia should not be a contraindication to the appropriate or necessary procedure.

Thyrotropin-secreting pituitary carcinoma

Pituitary tumors rarely metastasize outside the central nervous system. Of the more than 100 reported TSH-secreting adenomas, we now describe the first carcinoma. A 40-yr-old woman had transsphenoidal surgery for a large TSH-secreting pituitary adenoma in 1984. She had increased thyroid hormone levels with a TSH that varied from 16-31 microU/mL, and an unusually high alpha-subunit that ranged from 125-150 ng/mL. Because of residual tumor, she had a left craniotomy in 1985 followed by radiation. Despite these therapies, she had a residual tumor that remained stable until January 1989 when her tumor nearly doubled in size. She received radiation therapy and octreotide with marked diminution of the tumor and clinical improvement. In August 1989, she presented with leg weakness, and magnetic resonance imaging revealed a large sacral mass. A biopsy confirmed that the sacral mass was a metastasis from the pituitary tumor. Due to additional metastases in the lung, she received 5-fluorouracil, cytoxan, and adriamycin, with marked decrease in her lesions. Further substantiation of the metastatic pituitary tumor was made when the patient returned in December 1989 with a pleural effusion containing pituitary tumor cells. Of all the reported cases of TSH-secreting adenomas, this case had the highest alpha-subunit portending future metastases. Furthermore, the apparent response to octreotide and response to chemotherapy are encouraging and suggest that new therapies should be explored. Finally, since TSH-secreting adenomas tend to be more invasive than other pituitary tumors, this case underscores the need for early diagnosis and aggressive treatment of these tumors.