Serial changes in regional right ventricular free wall and left ventricular septal wall lengths during the first 4 to 5 years after index anterior wall myocardial infarction.

OBJECTIVES: This study investigated serial changes in regional right ventricular free wall and interventricular septal wall lengths during the first 4 to 5 years after an index anterior wall myocardial infarction. BACKGROUND: We previously demonstrated that remodeling after anterior wall myocardial infarction was a biventricular process; however, regional changes in biventricular topology were not investigated. METHODS: Serial electron beam computed tomographic scanning was performed in 19 patients at five times (hospital discharge and at 6 weeks, 6 months, 1 year and 4 to 5 years) after an index anterior wall myocardial infarction, and global and regional right ventricular free wall and interventricular septal wall lengths were quantified. RESULTS: At a mean (+/- SD) of 1,642 +/- 171 days (4 to 5 years) after infarction, global end-diastolic and end-systolic right ventricular free wall and interventricular septal wall lengths increased in parallel by 13% to 23% as global left and right ventricular volumes increased 22% to 29% from hospital discharge to 4 to 5 years after infarction. When global right ventricular free wall was compared with interventricular septal wall lengths, percent increases at end-diastole and end-systole were not statistically different at any time during the study period. Distinct regional changes in both right ventricular free wall and interventricular septal wall lengths after infarction were most dramatic during the first 6 weeks and primarily confined to the most apical levels. However, further and significant increases in both were observed by 4 to 5 years after infarction. CONCLUSIONS: Changes in both right ventricular free wall and interventricular septal wall lengths were apparent during the 4 to 5 years after the index anterior wall infarction, and the combination of both contributed to global increases in right and left ventricular chamber volumes. Regional changes in both right ventricular free wall and interventricular septal wall lengths were almost exclusively confined to their respective apices and progressed generally in parallel; however, the cause-and-effect relation remains speculative at the present time.

Serial changes in left and right ventricular systolic and diastolic dynamics during the first year after an index left ventricular Q wave myocardial infarction.

OBJECTIVES: This study quantified serially biventricular emptying and filling after infarction and related these to changes in volume, muscle mass, wall stress and contractility. BACKGROUND: There are limited data on serial changes in ventricular dynamics after infarction. METHODS: Forty patients had serial electron beam computed tomographic examinations during the first year after index Q wave infarction (21 anterior, 19 inferior), and global biventricular volumes, peak rates of emptying and filling and left ventricular muscle masses were quantified. Mean mid-left ventricular end-systolic wall stresses, rate-corrected velocities of circumferential shortening and two indexes of left ventricular contractility--the end-systolic wall stress/volume ratio and the end-systolic wall stress/rate-corrected velocity of circumferential shortening relation--were estimated in each instance. RESULTS: Patients with anterior infarction had an increase in biventricular chamber volume of 15% to 35% by 1 year. Global biventricular peak rates of emptying and filling were decreased by 20% to 30% from hospital discharge to 6 weeks but thereafter remained unchanged. Despite a significant increase in mean wall stresses, the end-systolic wall stress/volume ratio remained unchanged during the year. The rate-corrected velocities of circumferential shortening declined serially after anterior infarction but did so in proportion to the increase in mean wall stresses, consistent with no net change in left ventricular contractility. Patients with inferior infarction showed a trend toward similar changes, but the magnitudes did not reach significance. CONCLUSIONS: Left (and right) ventricular global peak rates of emptying and filling during the first year after infarction can be altered in the absence of additional ischemic injury but are more consistent with responses to changes in left ventricular afterload than changes in intrinsic ventricular performance or contractility. Serial changes in left ventricular afterload after infarction are largely due to progressive chamber enlargement and limited development of compensatory hypertrophy during the first year. Intrinsic global left ventricular contractile performance was not altered by postinfarction cardiac remodeling in the patients examined.

Nonparallel changes in global left ventricular chamber volume and muscle mass during the first year after transmural myocardial infarction in humans.

OBJECTIVES: This study was designed to serially assess time-dependent changes in both chamber volume and myocardial muscle mass after infarction in humans. BACKGROUND: Dilation of the left ventricular chamber has been previously described after transmural myocardial infarction. METHODS: Global left ventricular chamber volumes and muscle mass were quantified by using cine computed tomographic scanning in 18 patients at hospital discharge and 6 weeks, 6 months and 1 year after an initial transmural myocardial infarction (12 anterior and 6 inferior). No patient had heart failure during the initial hospital stay or on any subsequent follow-up visit. RESULTS: The patients with anterior myocardial infarction (estimated infarct extent 27 +/- 2% of left ventricle) demonstrated a progressive increase in left ventricular end-diastolic volume from 148 +/- 9 ml (mean +/- SEM) at hospital discharge to 180 +/- 9 ml at 1 year after infarction (p < 0.001). However, global left ventricular muscle mass decreased significantly during the 1st 6 weeks after infarction but returned by 1 year to nearly the value determined at hospital discharge (177 +/- 13 vs. 165 +/- 10 g, p = NS). The changes in global muscle mass did not parallel the steady and progressive increases in chamber end-diastolic volume. The end-diastolic chamber volume to muscle mass ratio, an index of global left ventricular wall tension, increased steadily after hospital discharge but remained level by 1 year after infarction. The time course of changes in global end-systolic chamber volume was roughly proportional to the concomitant changes in end-diastolic volume. During this same time period, left ventricular stroke volume remained constant or improved from that determined at baseline. Global left ventricular end-diastolic and end-systolic volumes remained relatively static during the 1st year in the patient subgroup with inferior wall myocardial infarction (estimated infarct extent 10 +/- 1% of left ventricle), but global muscle (myocardial) mass initially decreased and then increased in a pattern similar, although of smaller magnitude, to that observed in patients with anterior wall myocardial infarction. CONCLUSIONS: Overall, left ventricular end-diastolic and end-systolic chamber volumes increase progressively from hospital discharge to 1 year after an initial transmural myocardial infarction in patients with a moderately large anterior wall infarction but remain stable in patients with a small inferior wall infarction. Concurrently, total left ventricular muscle mass decreases significantly during the initial 6 weeks after infarction (presumed largely secondary to changes in the necrotic segments) but then returns to the hospital discharge baseline values by 1 year. These data are consistent with the late development of, at most, limited ventricular hypertrophy in the noninfarcted myocardium that occurs well after the early and progressive left ventricular chamber dilation observed in patients with a moderate to large myocardial infarction. These data, in particular as applied to patients with anterior infarction, suggest that ventricular wall tension is significantly elevated at least during the 1st year after an initial transmural myocardial infarction. These observations may explain the potential utility of agents aimed at reducing afterload or ventricular wall tension during the early convalescent phase after myocardial infarction.

An algorithm for noninvasive identification of angiographic three-vessel and/or left main coronary artery disease in symptomatic patients on the basis of cardiac risk and electron-beam computed tomographic calcium scores.

OBJECTIVES: We sought to model an algorithm for noninvasive identification of angiographically obstructive three-vessel and/or left main disease based on conventional cardiac risk assessment and site and extent of coronary calcium determined by electron-beam computed tomography (EBCT). BACKGROUND: Such an algorithm would greatly facilitate clinical triage in symptomatic patients with no previous diagnosis of coronary artery disease (CAD). METHODS: We examined 291 patients with suspected, but not previously diagnosed, CAD who underwent coronary angiography for clinical indications. Cardiac risk factors were determined as defined by the National Cholesterol Education Program. An EBCT scan was performed in all patients, and a coronary calcium score (Agatston method) was computed. Total per-patient calcium scores and separate scores for the major coronary arteries were generated. These scores were also analyzed for localization of coronary calcium in the more distal versus proximal tomographic sections. These parameters and the risk factors were considered for the model described in the following section. RESULTS: Sixty-eight patients (23%) had angiographic three-vessel and/or left main CAD. Multiple logistic regression analysis determined male sex, presence of diabetes and left anterior descending (LAD) and circumflex (LCx) coronary calcium scores, independent from more distal calcium localization, as independent predictors for identification of three-vessel and/or left main CAD. Based on this four variable model, a simple noninvasive index (NI) was constructed as the following: loge(LAD score) + log(e)(LCx score) + 2[if diabetic] + 3[if male]. Receiver operating characteristic curve analysis for this NI yielded an area under the curve of 0.88+/-0.03 (p < 0.0001) for separating patients with, versus without, angiographic three-vessel and/or left main CAD. Various NI cutpoints demonstrated sensitivities from 87-97% and specificities from 46-74%. The NI values >14 increased the probability of angiographic three-vessel and/or left main CAD from 23% (pretest) to 65-100% (posttest), and NI values <10 increased the probability of no three-vessel and/or left main CAD from 77% (pretest) to 95-100% (posttest). CONCLUSIONS: On the basis of a simple algorithm ("noninvasive index"), EBCT calcium scanning in conjunction with risk factor analysis can rule in or rule out angiographically severe disease, i.e., three-vessel and/or left main CAD, in symptomatic patients.

Measurement of abdominal and visceral fat with computed tomography and dual-energy x-ray absorptiometry.

These studies were undertaken to compare dual-energy x-ray absorptiometry (DXA) and computed tomography (CT) measurements of abdominal fat and to determine whether anthropometry could be combined with DXA to predict intraabdominal (visceral) fat mass in humans. Twenty-one volunteers underwent abdominal CT scans, DXA, and anthropometry. DXA- and CT-measured total abdominal fat were similar (8448 +/- 5005 and 8066 +/- 5354 mL, respectively; NS) and were highly correlated (r = 0.985, P < 0.001). The combination of anthropometry and DXA was a suboptimal predictor of CT-measured intraabdominal fat (r = 0.61, P < 0.05); however, the combination of a single CT slice (to assess the ratio of intraabdominal to total abdominal adipose tissue) and DXA-measured abdominal fat was an excellent predictor of CT-measured intraabdominal fat (r = 0.98, P < 0.001). We conclude that a single-slice CT scan (or other imaging technique) with or without DXA is required for accurate predictions of intraabdominal fat.

Intracerebral hemorrhage and phenylpropanolamine use.

Two patients developed intracerebral hemorrhage within hours from first-time ingestion of phenylpropanolamine-containing medications. One patient had marked hypertension, presented with three intracerebral hematomas, and developed a fourth hemorrhage 10 days later. Angiogram in one patient revealed "beading" of intracranial arteries, an abnormality also detected in a third patient who developed severe headache, vomiting, and acute hypertension following a single dose of phenylpropanolamine. These cases and others reported in the literature strongly suggest an association between phenylpropanolamine ingestion and hemorrhagic stroke. Direct questioning of use of this medication in cases of unexplained intracranial hemorrhage in previously healthy young individuals may reveal an unsuspected high frequency of this association.

High-level expression of recombinant Fc chimeric proteins in suspension cultures of stably transfected J558L cells.

Recombinant Fc chimeric proteins are useful tools for studying protein function, including the analysis of molecular interactions by techniques such as expression cloning. Here we describe a method we have used to express the IgLON family proteins, CEPU1 and OBCAM, as recombinant Fc chimeric proteins in stably transfected mouse J558L myeloma cells. The use of this cell line provided the opportunity to maximize protein production, as it secretes antibodies in large quantities and can be grown to high density in small volumes of culture medium. Isolation of recombinant OBCAMFc from the adherent COS7 cell line suggested a minimum level of expression of 0.07 mg OBCAMFc/100 mL culture medium, while the J558L cell line expressed OBCAMFc at approximately 11.4 mg/100 mL culture medium. Purification of IgLON-Fc expressed by J558L cells was simpler than purification from COS7 cells because of the lower volume of culture medium generated. Furthermore, contamination of J558L expressed IgLONFc with bovine IgG from the culture medium was negligible. The method presented, which utilizes a commercially available small-scale bioreactor, provides the nonspecialist protein expression laboratory with the means to produce recombinant proteins quickly and easily in milligram quantities.

Quantitative dynamics of left ventricular emptying and filling as a function of heart size and stroke volume in pure aortic regurgitation and in normal subjects.

Quantitative understanding of the dynamics of left ventricular (LV) emptying and filling as the left ventricle dilates but maintains ejection fraction is limited. Cine computed tomography was used to quantify peak LV emptying and filling characteristics in 30 patients with normal ejection fraction but variable end-diastolic and stroke volumes. Group I consisted of 15 normal male patients and group II of 15 male patients with chronic, well-compensated, isolated aortic regurgitation. For each patient global LV volumes, absolute peak emptying and peak early diastolic filling rates and the timing of these maximal slopes were quantified. Mean arterial pressure and heart rate were within the normal range and ejection fraction and ages similar between groups I and II. Between-group analyses showed significantly increased end-diastolic and stroke volumes in group II compared with group I but nearly identical end-systolic volumes. Likewise, absolute peak emptying and filling rates were significantly greater in group II than in group I patients. The ratio of peak emptying rate to peak filling rate remained constant between groups. Timing of peak emptying and filling were similar in both groups. Absolute LV peak emptying and filling rates were found to vary linearly with end-diastolic and stroke volumes in all subjects examined. However, referencing peak emptying or peak filling rates to end-diastolic or total stroke volumes eliminated intergroup differences. Thus, in the presence of preserved ejection fraction and normal arterial pressure, the dynamic rates of LV emptying and early diastolic filling increase in direct proportion to absolute end-diastolic and stroke volumes, but the ratio of peak emptying to peak filling rate remains constant.

Right ventricular dilatation and remodeling the first year after an initial transmural wall left ventricular myocardial infarction.

Left ventricular (LV) remodeling after LV myocardial infarction was described previously. Little is known regarding concomitant adaptation, if any, in right ventricular (RV) volumes after LV infarction. To examine this issue, cine-computed tomography was used to determine serial changes in absolute global LV and RV volumes in 27 patients without clinical heart failure during the first year after an initial Q-wave myocardial infarction (14 anterior and 13 inferior). The patient group with anterior wall LV infarction showed progressive increases in LV and RV volumes from hospital discharge to 1 year (end-diastolic volumes +25 and +13%, respectively; and end-systolic volumes +35 and +15%, respectively). In patients with inferior wall LV infarction, both LV end-diastolic and end-systolic volumes increased significantly during the study period (+13 and +15%, respectively). Despite a trend for RV end-diastolic volume to be increased at 1 year, neither end-diastolic nor end-systolic volume increased significantly after hospital discharge following inferior wall LV infarction. Absolute RV end-diastolic volume was not significantly different between the infarct groups at any time after infarction. In conclusion, global changes occur in both LV and RV volumes during the first year after an initial infarction regardless of infarct location. The magnitude of these changes was greater after anterior than inferior wall LV infarction.

Comparison of two different software systems for electron-beam CT-derived quantification of coronary calcification.

OBJECTIVE: The growing interest in coronary calcium quantification by electron-beam CT (EBCT) has led to the development of various software systems for the analysis of EBCT raw data, but it is unknown whether these software systems yield comparable results. METHODS: Two sets of EBCT scans were obtained in 73 asymptomatic patients less than 15 minutes apart. Both scans of each patient were analyzed using two different software systems, the Mayo Clinic software and the AccuImage Scoring System. The authors compared the calcium quantities yielded by the two different software systems, analyzed the interscan variability, and calculated the interobserver variability. Finally, they investigated the influence of the CT density factor inherent in the widely used Agatston score for the quantification of coronary calcium on reproducibility. RESULTS: The mean score determined by the Mayo Clinic software was 14% greater than that determined by the AccuImage system. The mean difference between the two systems was 14% +/- 25%, and the median difference was 3%. The relative mean and the median difference between the two scans of one patient were 15.3% and 6% determined by the AccuImage system and 17% and 6.5% determined by the Mayo Clinic software. The interobserver reliability calculated by the Mayo Clinic software was better than that of the AccuImage system. There was a trend for better reproducibility using calcium area rather than the Agatson score. CONCLUSIONS: Two different scoring systems do not necessarily yield the same result. Calcium quantities were systematically determined to be greater by one system than the other, and there were significant differences with regard to interobserver reliability. Hence, software should be tested with regard to reproducibility data, and the interpretation of calcium quantities should acknowledge which type of software was used.

Measurement of myocardial infarct size by electron beam computed tomography: a comparison with 99mTc sestamibi.

RATIONALE AND OBJECTIVES: The authors sought to determine, using a variety of regional left ventricular ejection fraction (EF) and wall thickening (WTh) criteria, the applicability to measure left ventricular (LV) infarct size using electron-beam CT (EBCT) in patients as compared with technetium 99m (99mTc) sestamibi scanning as reference standard. METHODS: Twelve patients (age 57 +/- 11 years) underwent 99mTc sestamibi scanning and EBCT at hospital discharge after an acute index anterior myocardial infarction. Left ventricular infarct size was defined using standard 99mTc sestamibi scanning. Regional EF and WTh were analyzed on each EBCT scan with use of a floating epicardial centroid method. In five contiguous LV tomograms, the amount of infarcted myocardium was estimated using the following EF and WTh criteria: EF < or = 35%, 30%, 25%, 20%, and WTh < or = 2 mm, 1 mm, and 0 mm. RESULTS: Infarct size measured with 99mTc sestamibi was 33.3% (+/- 18.3%) (mean +/- SD, range 6%-54%) of the LV. Using an EF < or = 35% or absolute WTh < or = 2 mm as criteria for infarcted myocardium, EBCT yielded 28% (+/- 17%) and 27% (+/- 16%), respectively (P = NS, paired Student's t test, versus 99mTc sestamibi). Although, with use of the other criteria, EBCT tended to underestimate infarct size compared with 99mTc sestamibi, a close correlation across the entire range of infarct size determinations (range, 0.72-0.82) regardless of the underlying criteria suggested an internal consistency of the data. CONCLUSIONS: Quantitative analysis of regional myocardial function by EBCT allows an estimate of anterior infarct size when compared with 99mTc sestamibi. This suggests that in addition to previously established applications after acute myocardial infarction such as examination of cardiac volumes and mass, EBCT also may provide for infarct size determination.

Use of a new myocardial centroid for measurement of regional myocardial dysfunction by electron beam computed tomography: comparison with technetium-99m sestamibi infarct size quantification.

RATIONALE AND OBJECTIVES: The study compared the performance of conventional endocardial and epicardial centroid algorithms with the new "myocardial" centroid algorithm in patients with anterior myocardial infarction. "Floating" endocardial or epicardial centroid algorithms, commonly used in tomographic imaging methods to assess regional motion, may misrepresent left ventricular regional myocardial function in the presence of markedly asymmetric left ventricular contraction. METHODS: A new centroid algorithm based on regional myocardial mass distribution was tested in 29 patients with a first anterior myocardial infarction and was compared with conventional centroid algorithms. Direct comparisons in 60 equal sectors at one midventricular level per patient were performed between electron beam computed tomography and technetium-99m sestamibi single-photon emission computed tomography. The thresholds of regional myocardial function used to define infarction were varied for regional ejection fraction from 20% to 40% and for regional wall thickening from 0 to 4 mm. Regression and Bland-Altman analysis were used to compare infarct size by regional myocardial function with infarct size by sestamibi single-photon emission computed tomography. RESULTS: The new myocardial centroid showed the least shift toward infarcted myocardium from diastole to systole and had the highest amplitudes of the measurement curves for regional ejection fraction and regional wall thickening. The optimal regional myocardial function thresholds for each centroid algorithm for regional ejection fraction were endocardial, 30% (R = 0.62; mean difference to sestamibi, -0.5% +/- 22.1% tomographic infarct size points); epicardial, 30% (R = 0.79; mean difference, 2.2% +/- 13.1% tomographic infarct size points); and new myocardial, 25% (R = 0.88; mean difference, -0.6% +/- 9.5% tomographic infarct size points). The optimal thresholds for regional wall thickening were endocardial, 1 mm (R = 0.70; mean difference, -2.2% +/- 14.3% tomographic infarct size points); epicardial, 1 mm (R = 0.78; mean difference, -4.6% +/- 12.7% tomographic infarct size points); and new myocardial, 2 mm (R = 0.71; mean difference, 2.1% +/- 14.1% tomographic infarct size points). The best agreement (R = 0.88) between electron beam computed tomography infarct size and sestamibi single-photon emission computed tomography infarct size was achieved with regional ejection fraction and the new myocardial centroid algorithm. CONCLUSIONS: In asymmetrically contracting left ventricles, the new myocardial centroid algorithm is superior to conventional methods for tomographic analysis of regional myocardial function.

A method for automatic edge detection and volume computation of the left ventricle from ultrafast computed tomographic images.

RATIONALE AND OBJECTIVES: Detection of endocardial and epicardial borders of the left ventricle (LV) using various imaging modalities is time-consuming and prone to interpretive error. An automatic border detection algorithm is presented that is used with ultrafast computed tomographic images of the heart to compute cavity volumes. METHODS: The basal-level slice is identified, and the algorithm automatically detects the endocardial and epicardial borders of images from the basal to the apical levels. From these, the ventricular areas and chamber volumes are computed. The algorithm uses the Fuzzy Hough Transform, region-growing schemes, and optimal border-detection techniques. The cross-sectional areas and the chamber volumes computed with this technique were compared with those from manually traced images using canine hearts in vitro (n = 8) and studies in clinical patients (n = 27). RESULTS: Though the correlation was good (r = .88), the algorithm overestimated the LV epicardial area by 4.8 +/- 6.4 cm2, though this error was not statistically different from zero (P > .05). There was no difference in endocardial areas (r = .95, P > .05). The algorithm tended to underestimate the end-diastolic volume (r = .94) and the end-systolic volume (r = .94), although these errors were not statistically different from zero (P > .05). The algorithm tended to underestimate the ejection fraction (r = .80), although this error was not statistically different from zero (P > .05). CONCLUSIONS: Automatic detection of myocardial borders provides the clinician with a useful tool for calculating chamber volumes and ejection fractions. The algorithm, with the corrections suggested, provides an accurate estimation of areas and volumes. This algorithm may be useful for contour border identification with ultrasound, positron-emission tomography, magnetic resonance imaging, and other imaging modalities in the heart, as well as other structures.

New heterocyclic precursors for thermal generation of reactive, electron-rich 1,2-diaza-1,3-butadienes.

[reaction--see text] [corrected] The preparation and thermolysis of new stable heterocyclic precursors of 1,2-diaza-1,3-butadienes is described. The resulting reactive diazadienes are trapped in situ with N-phenylmaleimide [corrected]. The effect of precursor structure on the temperature at which the diazadienes are generated is discussed.

A novel route to 2,3-pyrazol-1(5H)-ones via palladium-catalyzed carbonylation of 1,2-diaza-1,3-butadienes.

[reaction--see text] A novel Pd(0)-catalyzed carbonylation of both isolable 1,2-diaza-1,3-butadienes and those generated in situ by extrusion of SO(2) and CO(2) from heterocyclic precursors is described. The reaction proceeds at room temperature to 110 degrees C under 1-2 atm of CO to afford 2,3-pyrazol-1(5H)-ones in good to excellent yields. The effect of catalyst structure and stability on the carbonylation reaction is evaluated.

Measuring leg muscle and fat mass in humans: comparison of CT and dual-energy X-ray absorptiometry.

Dual-energy X-ray absorptiometry (DEXA) is reported to be inferior to computed tomography (CT) to measure changes in appendicular soft tissue composition. We compared CT- and DEXA-measured thigh muscle and fat mass to evaluate the random and systematic discrepancies between these two methods. Thigh skeletal muscle area (single-slice CT) was suboptimally (r(2) = 0.74, P < 0.0001) related to DEXA-measured thigh fat-free mass (FFM). In contrast, thigh muscle and adipose tissue volumes (multislice CT) were highly related to DEXA-measured thigh FFM and fat (both r(2) = 0.96, P < 0.0001). DEXA-measured leg fat was significantly less than multislice-CT-measured leg adipose tissue volume, whereas multislice-CT-measured leg muscle mass was less (P < 0.0001) than DEXA-measured leg FFM. The systematic discrepancies between the two approaches were consistent with the 10-15% nonfat components of adipose tissue. In conclusion, CT and DEXA measures of appendicular soft tissue are highly related. Systematic differences between DEXA and CT likely relate to the underlying principles of the techniques.

Pituitary desensitization to gonadotropin-releasing hormone increases abdominal adiposity in hyperandrogenic anovulatory women.

OBJECTIVE: To determine whether hyperandrogenism in anovulatory women affects body fat distribution. DESIGN: Prospective nonrandomized study. SETTING: An academic research environment. PATIENT(S): Ten hyperandrogenic anovulatory patients and 10 healthy women matched by body mass index. INTERVENTION(S): Regional body fat analysis was performed before and after 3 months of GnRH analogue (GnRH-a) therapy. MAIN OUTCOME MEASURE(S): Body fat distribution was measured by waist-to-hip circumference ratio, single-slice computed tomography imaging (L2-3 interspace), and total body dual-energy x-ray absorptiometry. RESULT(S): Weight, body mass index, waist-to-hip circumference ratio, total body and leg fat mass, and subcutaneous adipose area were unaffected by the presence of hyperandrogenism or the use of GnRH-a therapy. Basal abdominal fat mass, abdomen-to-leg fat mass ratio, visceral adipose area, and total visceral adipose volume were comparable in both study groups. The abdominal fat mass increased in both groups during GnRH-a therapy, whereas the abdomen-to-leg fat mass ratio rose significantly only in the hyperandrogenic patients. During GnRH-a therapy, the hyperandrogenic patients demonstrated a significant increase in visceral adipose area compared with the healthy women so that total visceral adipose volume increased significantly in the former but not the latter. CONCLUSION(S): Three months of GnRH-a administration preferentially increased abdominal fat, as measured by single-slice computed tomography imaging and total body dual-energy x-ray absorptiometry, in hyperandrogenic anovulatory women.

Automatic detection of myocardial contours in cine-computed tomographic images.

Quantitative evaluation of cardiac function from cardiac images requires the identification of the myocardial walls. This generally requires the clinician to view the image and interactively trace the contours. This method is susceptible to great variability that depends on the experience and knowledge of the particular operator tracing the contours. The particular imaging modality that is used may also add tracing difficulties. Cine-computed tomography (cine-CT) is an imaging modality capable of providing high quality cross-sectional images of the heart. CT images, however, are cluttered, i.e., objects that are not of interest, such as the chest wall, liver, stomach, are also visible in the image. To decrease this variability, investigators have developed computer-assisted or near-automatic techniques for tracing these contours. All of these techniques, however, require some operator intervention to confidently identify myocardial borders. The authors present a new algorithm that automatically finds the heart within the chest, and then proceeds to outline (detect) the myocardial contours. Information at each tomographic slice is used to estimate the contours at the next tomographic slice, thus allowing the algorithm to work in near-apical cross-sectional images where the myocardial borders are often difficult to identify. The algorithm does not require operator input and can be used in a batch mode to process large quantities of data. An evaluation and correction phase is included to allow an operator to view the results and selectively correct portions of contours. The authors tested the algorithm by automatically identifying the myocardial borders of 27 cardiac images obtained from three human subjects and quantitatively comparing these automatically determined borders with those traced by an experienced cardiologist.

Regional left ventricular wall thickness and systolic function during the first year after index anterior wall myocardial infarction: serial effects of ventricular remodeling.

There is controversy regarding changes in regional left ventricular systolic function and thickness during remodeling after infarction. To address this, electron beam computed tomography was done in 22 patients with an index anterior wall infarction at discharge, 6 weeks, 6 months and 1 year, and global ventricular chamber volumes and mass quantified. A mid-ventricular short-axis scan from each study was divided into 4, 90 degrees sectors (anterior, septal, lateral and posterior walls). Regional wall thickness, ejection fraction, and absolute and percent wall thickening were determined and compared with 10 normal adults. Global infarct size was estimated at 24.2%+/- 3.4% of the ventricle. In these subjects, the ventricular chamber enlarged steadily during the year, while global ventricular mass initially decreased during the first 6 weeks, but then increased by 1 year. Regional ejection fraction changed little during the year, apart from the lateral wall, which was less than normal. Absolute wall thickening was reduced in the anterior (infarct) and septal walls throughout the year, but was normal and unchanged in the posterior and lateral walls. Regional percent wall thickening was not different from normal individuals. The anterior wall was thinned at discharge and tended to thin further during the year. The lateral wall was thinner than normal 6 weeks after infarction, but remained unchanged thereafter. The posterior wall tended to thin for the first 6 months, but the values at any time were not above normal. There was little change in septal wall thickness throughout the year. It is concluded that, after a moderate size, uncomplicated index anterior infarction, regional systolic function remains generally unaffected by remodeling. However, regional walls tend to thin and/or remain at normal thickness. These data confirm differential regional patterns after anterior infarction for systolic function, muscle atrophy and/or minimal hypertrophy which accompany serial changes in global ventricular chamber volumes and mass.

Effect of mannitol on the traumatized spinal cord. Microangiography, blood flow patterns, and electrophysiology.

The effects of mannitol on the spinal cord blood flow patterns in experimental traumatic paraplegia were correlated with microangiographic and electrophysiologic studies. At 1 hour following a therapeutic dose of mannitol (3 g/kg), an improved fluorescent intramedullary vascular pattern was detected among the mannitol-treated animals relative to those that were not treated. Within 4 hours, perfusion of many areas of the lateral white matter of the spinal cord often approximated normal in the mannitol-treated group. This pattern of perfusion was in striking contrast to that seen in the spinal cord of untreated animals, which displayed an almost total lack of fluorescing vessels at this later time. These findings correlated with an increased vascular caliber as revealed by microangiography and were postulated to be the result of a decrease in vasospasm and an expanded intramedullary blood volume following the administration of mannitol. Although mannitol therapy did not reverse the loss of the cortical evoked response observed during the 4-hour interval studied, the observation of improved blood flow patterns in the white matter is encouraging and warrants further study.