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Biomedical subjects

P F Sheedy

Publications and source records attributed to P F Sheedy.

At least 37 records · Page 2Linked to original sources
PubMed1999

Progression of coronary artery calcification: a pilot study.

OBJECTIVE: To describe individual changes in the quantity of coronary artery calcification (CAC) measured by electron beam computed tomography (CT) and determine the rate of change in the quantity of CAC during a 3.5-year period. MATERIAL AND METHODS: Eighty-eight consecutive participants (51 men at least 30 years of age and 37 women at least 40 years of age) from a community-based CAC study were invited for a follow-up examination. Established coronary artery disease risk factors were studied at baseline. CAC score was measured by electron beam CT at baseline and follow-up. RESULTS: Of the 88 invited participants, 82 (93%) returned for a follow-up examination. Considerable variation existed among the participants in the extent of CAC score change. On average, CAC score increased over time by an estimated 24% each year (P<0.05). The relative increase in CAC score over time was significantly lower for older than for younger participants but did not vary significantly by sex. CONCLUSION: The ability to recruit follow-up participants in this pilot study and to detect significant change in CAC score over time provides evidence that electron beam CT is useful for studying progression of CAC in a sample and may be a valuable procedure for assessing the effectiveness of clinical interventions designed to retard progression of coronary atherosclerosis.

Adult↗
PubMed1998

Angiographic correlates of "spotty" coronary artery calcium detected by electron-beam computed tomography in patients with normal or near-normal coronary angiograms.

To characterize relations between coronary plaque formation, focal, "spotty" coronary calcified lesions, and luminal narrowing, coronary calcium was examined by electron-beam computed tomography in 49 patients with normal or near-normal angiograms. Based on a coronary segmental analysis and on a patient-by-patient analysis, spotty coronary calcium was associated with slight angiographic changes consistent with early atherosclerotic disease and compensatory arterial remodeling.

Adult↗
PubMed1998

Anatomy of the human biliary system studied by quantitative computer-aided three-dimensional imaging techniques.

The branching geometry of the normal, cholangiographically identifiable human biliary tree was studied with an innovative computer-aided three-dimensional (3D) imaging technique. In addition, a serially sectioned conventional paraffin block from a normal donor liver was used to create and quantitatively study a microscopic 3D image. Finally, a geometric model was developed to estimate the enlargement of biliary surfaces imparted by microvilli. The images created by these techniques could be viewed in stationary modes or rotating around any preselected axis. Approximately 7 (+/-3) intrahepatic duct orders were cholangiographically identified. Computerized measurements of the images from three normal livers suggested that the mean total volume of duct orders 1 to 7 shown in the cholangiograms was 16.6 cm3. The volume of the entire macroscopic duct system was estimated to be between 14 and 24 cm3 (mean, 20.4 cm3), with an internal surface of 336 to 575 cm2 (mean, 398 cm2). A geometric model based on electron micrographs suggested that this surface is magnified approximately 5.5-fold by the presence of microvilli. Volume and surface area (SA) measurements of all ducts in the same orders increased nearly exponentially from the first toward the seventh branching order (i.e., from the hilus toward the periphery of the liver), and probably beyond. The microscopic computerized reconstruction of a septal bile duct with its tributaries also allowed volume measurements; the imaged duct system represented 2.7% of the portal tract volume. The data presented herein may help to better evaluate branching patterns of the biliary tree and, eventually, the quantitative aspects of site-restricted cholangiocyte function and their role in the development of biliary diseases.

Biliary Tract↗
PubMed1998

Intravenous electron-beam computed tomographic coronary angiography for segmental analysis of coronary artery stenoses.

OBJECTIVES: We sought to identify and localize significant coronary stenoses on a segmental basis by electron-beam computed tomography (EBCT) and intravenous administration of a contrast agent. BACKGROUND: The clinical applicability and limitations of intravenous EBCT coronary angiography have not been defined. METHODS: EBCT was performed within 24 h of selective coronary angiography (SCA) in 28 patients (19 men and 9 women, mean [+/-SD] age 60 +/- 10 years). After examination for coronary calcium, EBCT coronary angiography was performed using overlapping slices (in-plane resolution 0.34 to 0.41 mm) with a nominal slice thickness of 1 mm. Based on quantitative analysis of SCA, lumen diameter narrowing > or = 50% (i.e., significant stenoses) was evaluated in 8 (major) or 12 (including side branches) coronary artery segments, using both two-dimensional (tomographic) and three-dimensional (volume) data sets. RESULTS: Of the 330 segments assessable by SCA, 237 (72%) were visualized by EBCT. The sensitivity (+/-SE) for detection of significant stenoses was 82 +/- 6%; specificity was 88 +/- 2%; positive and negative predictive values were 57 +/- 7% and 96 +/- 2%, respectively; and overall accuracy was 87 +/- 2%. If only eight (major) coronary artery segments were considered, 194 (88%) of 221 segments were visualized, and the overall accuracy was 90 +/- 2%. Seven (18%) of 38 significantly stenotic segments were classified as having < 50% stenoses by EBCT. Six of these segments (86%), but only 9 (29%) of the 31 correctly classified stenotic segments, were severely calcified (area > 20 mm2, p = 0.02). In 23 (12%) of 199 nonstenotic segments falsely classified as having > or = 50% stenosis by EBCT, the lumen diameter was significantly smaller than that of the segments correctly classified as negative (mean [+/-SD] 1.5 +/- 0.8 vs. 2.9 +/- 1.1 mm, p < 0.001). CONCLUSIONS: Intravenous EBCT coronary angiography allows for accurate segmental evaluation of significant disease in the major coronary arteries and may be of value for ruling out significant disease. The main determinant of false negative results is substantial segmental calcification, whereas the main determinant of false positive results is small vessel size.

Adult↗
PubMed1998

Reproducibility of right and left ventricular volume measurements by electron-beam CT in patients with congestive heart failure.

UNLABELLED: The applicability and reproducibility of electron-beam computed tomography (EBCT) was tested to define left and right ventricular volumes in patients with congestive heart failure in a clinical setting. METHODS: Ten patients (mean age 64 +/- 11 years) with dilated hearts and stable congestive heart failure (functional class III-IV) were studied. After determination of the individual circulation time, two serial short axis polytomographic EBCT studies were performed within a mean interval of 14.8 +/- 10 days. Following intravenous contrast administration, biventricular end-diastolic volumes (LVEDV, RVEDV), end-systolic volumes (LVESV, RVESV), and left ventricular muscle mass (LVMM) were determined using previously developed techniques. RESULTS: Adequate contrast opacification in both ventricular cavities was obtained in all patients at baseline and at follow-up. Values were 323.4 +/- 99.3 (mean +/- SD) and 332.6 +/- 105.4 ml for LVEDV, 249.3 +/- 75.6 and 250.5 +/- 79.3 ml for LVESV, 236.8 +/- 56.2 and 251.2 +/- 72.7 ml for RVEDV, 179.8 +/- 76.4 and 188.3 +/- 64.0 ml for RVESV, and 207.7 +/- 70.6 and 204.9 +/- 81.9 g for LVMM (p = NS, respectively, paired t-test). Linear regression analysis correlating biventricular volumes and left ventricular muscle mass measurements in the serial scans yielded r-values in the range of 0.89 to 0.95 and a small SEE. The SE of the mean differences between left and right ventricular ejection fraction measurements was 1 point, respectively. CONCLUSION: EBCT studies of ventricular volumes in patients with dilated hearts and congestive heart failure are highly reproducible and offer the potential for serial assessment of these patients in whom quantitation of ventricular volumes has been shown to be of prognostic value.

Cardiac Volume↗
PubMed1998

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.

Adult↗
PubMed1997

Electron beam computed tomographic coronary calcium score cutpoints and severity of associated angiographic lumen stenosis.

OBJECTIVES: We sought to determine a range of cutpoints for coronary calcium scores measured by electron beam computed tomography (EBCT) in predicting the likely severity of associated angiographic coronary artery stenoses. BACKGROUND: EBCT can quantify coronary calcium and allow the estimation of atherosclerotic plaque burden, but use of the calcium score to define lumen narrowing is controversial. METHODS: A total of 213 patients (mean [+/- SD] age 50 +/- 9 years) underwent coronary angiography and EBCT. Maximal percent diameter stenosis in any artery was paired with total coronary calcium score. Receiver operating characteristic (ROC) curve analysis was done using definitions of "disease" for maximal stenosis from > or = 20% to 100%, and the corresponding score cutpoints were determined for 90% sensitivity, 90% specificity or "optimal" sensitivity and specificity. RESULTS: ROC curve areas ranged from a mean (+/- SE) of 0.91 +/- 0.02 for > or = 20% stenosis to 0.83 +/- 0.03 for 100% stenosis. Optimal calcium score cutpoints consisted of nonoverlapping values ranging from 15 for > or = 20% stenosis to 327 for 100% stenosis, whereas sensitivities and specificities ranged from 78% to 84%, depending on maximal stenosis severity. Calcium score cutpoints for 90% sensitivity and 90% specificity were also nonoverlapping and ranged from 3 and 27, respectively, for > or = 20% stenosis to 154 and 945, respectively, for 100% stenosis; corresponding specificities and sensitivities ranged from 40% to 78%. CONCLUSIONS: These data define the ranges for EBCT coronary calcium score cutpoints that predict the likely severity of associated maximal angiographic stenosis severity to a high sensitivity, high specificity or optimal sensitivity/specificity. These cutpoints potentially can be used in conjunction with clinical variables to predict the severity of lumen narrowing in patients undergoing assessment for coronary artery disease.

Adult↗
PubMed1997

Perfusion pressure dependency of in vivo renal tubular dynamics.

To examine whether changes in renal perfusion pressure (RPP) within the range of autoregulation induce detectable changes in tubular dynamics in an entire nephron population of the intact kidney, we measured, using electron beam computed tomography (EBCT), transit times (TT, s) and intratubular concentration (%) of filterable contrast media in various nephron segments simultaneously with renal regional perfusion. In seven dogs (group A) this was performed at the upper and lower limits of autoregulation (RPP = 130 and 95 mmHg, respectively) while group B (n = 5) served as control. In group A alone, a decrease in RPP led to an increase in TT by 40%, 68%, and 32% in the proximal tubules, ascending limb of Henle's loop, and distal tubules, respectively, in association with an increase in intratubular concentration (+ 50%, 80%, and 42%, respectively). Papillary perfusion decreased, whereas perfusion of the adjacent, outlying inner medulla increased. The decrease in papillary perfusion correlated positively with the concurrent change in sodium excretion (R = 0.81). This study demonstrates that changes in RPP within the autoregulatory range elicit changes of tubular sodium reabsorption mainly in proximal, distal, and ascending tubules, in which most of the nephrons participate. These tubular changes are associated with an alteration of perfusion circumscribed to two areas of the inner renal medulla.

Animals↗
PubMed1996

Potential of quantity of coronary artery calcification to identify new risk factors for asymptomatic atherosclerosis.

The goals of this study of adults asymptomatic for coronary artery disease (CAD) were to examine the relations between established CAD risk factors and quantity of coronary artery calcification (CAC) in three arterial locations using generalized linear mixed models and to estimate the variability in quantity of CAC explained by established CAD risk factors and the variability due to noise or artifact in the measure. The community-based sample included 740 asymptomatic adults (378 women) aged 20-59 years without hypertension or diabetes. Participants were recruited from Rochester, Minnesota, between 1990 and 1994. Quantity of CAC in three arterial locations was detected noninvasively by electron beam computed tomography. Sex, arterial location, age, body size, blood pressure, lipid metabolism, and smoking were significantly (p < 0.05) associated with quantity of CAC. Age was more strongly associated with quantity of CAC in the left than in the right coronary or circumflex arterial locations (p < 0.005). In each sex, risk factors together explained less than 40% of the variability in quantity of CAC. Noise or artifact in the measure accounted for only a small proportion of unexplained variability. Future studies of new risk factors for artery-specific quantity of CAC and its progression could provide additional etiologic insights into the atherosclerotic process.

Adult↗
PubMed1996

The relationship between renal cortical volume and predisposition to hypertension.

It has been proposed that a reduction in the number of nephrons is a renal abnormality that plays an important role in the pathogenesis of essential hypertension. The objective of this study was to determine whether renal cortical volume, used as a measure of the number of nephrons, is lower in normotensive subjects with a familial predisposition to develop essential hypertension than in subjects who lack this predisposition. For this purpose, we measured renal cortical volume using electron beam computed tomography in 26 white offspring to two hypertensive parents (OHT; 14 women, 12 men) and 27 white offspring of two normotensive parents (ONT; 13 women, 14 men) who were stabilized on a high sodium diet for 3 days (200 mmol/day). In women, mean age was significantly greater in OHT than ONT (46.1 +/- 4.9 [standard deviation] v 41.8 +/- 5.1 years, respectively, P = .04)In men, means for age and weight were greater in OHT than ONT (age: 47.1 +/- 7.7 v 37.9 +/- 8.1 years, P < .01; weight: 90.2 +/- 10.7 v 81.1 +/- 9.4 kg, P = .03.) In women, mean total cortical volume did not differ significantly between OHT and ONT (156 +/- 33.3 v 166 +/- 30.9 cc, P = .80). After adjustment for interindividual differences in age, mean total cortical volume remained not significantly different in OHT than ONT (160 +/- 29.0 v 162 +/- 32.4 cc, P = .83). In men, mean total cortical volume was significantly greater in OHT than ONT (210 +/- 33.6 v 180 +/- 20.0 cc, P = .01). After adjustment for interindividual differences in age, mean total cortical volume remained significantly greater in OHT than ONT (207 +/- 33.2 v 182 +/- 19.8 cc, P = .02). After adjustment for interindividual differences in body weight, mean total cortical volume did not differ significantly between OHT and ONT (201 +/- 21.7 v 187 +/- 20. cc, P = .09). The results of this study do not support the hypothesis that a decrease in renal cortical volume, as a result of a decrease in number of nephrons, is a characteristic of white women or men with a familial predisposition to develop essential hypertension.

Adult↗
PubMed1996

Fast CT for pulmonary embolus.

Recent technical advances in CT have led to the ability to scan a volume in a shorter period with optimal contrast opacification of blood vessels, including the pulmonary arteries. Initially, there were isolated instances of an accidental detection of a filling defect because of pulmonary embolus in the pulmonary arteries. Gradually, directed examinations were introduced to diagnose or exclude pulmonary embolus. These examinations were successful. Radiologists and clinicians now are turning to fast CT for this purpose for a variety of reasons, including the proven accuracy and reliability of the method and the relative deficiencies of traditional noninvasive methods. Accurate interpretation of CT scans for possible pulmonary embolus depends on the ability to conduct a high-quality examination and to recognize the spectrum of findings for both acute and chronic emboli. This article reviews the history of fast CT pulmonary angiography, and it presents both technical and diagnostic information germaine to the performance of this technique.

Acute Disease↗
PubMed1996

Computed tomography-derived intrarenal blood flow in renovascular and essential hypertension.

The effect of renal artery stenosis on intrarenal perfusion and volume in renovascular hypertensive patients is unclear. Alterations in these attributes may ultimately be involved in deterioration of renal function. We measured whole kidney, cortical, and medullary perfusion and volume with electron beam computed tomography (EBCT) in 33 hypertensive patients, with well-preserved renal function, scheduled for renal angiography. EBCT-derived whole kidney perfusion was lower in patients with atherosclerotic renal artery stenosis (RAS; N = 20) than in fibromuscular dysplasia (FMD; N = 10) or essential hypertension (N = 28; P < 0.05), as was cortical perfusion (2.44 +/- 0.16 vs. 3.26 +/- 0.17 and 3.07 +/- 0.09 ml/min/cc tissue, respectively, P < 0.005), but medullary perfusion was similar. Whole kidney, cortical, and medullary perfusion correlated inversely with degree of stenosis in FMD, but not in atherosclerotic RAS. Renal volumes were similar. These results demonstrate that, in contrast to patients with FMD, in patients with atherosclerotic RAS the decrease in cortical perfusion is not directly related to the degree of stenosis in the main renal artery. Factors other than the stenosis itself may play a role in the pathophysiology of atherosclerotic RAS and associated renal failure.

Adult↗
PubMed1996

Reproducibility of human kidney perfusion and volume determinations with electron beam computed tomography.

RATIONALE AND OBJECTIVES: Alterations in whole kidney, cortical, and medullary perfusion and volume play a pivotal role in various physiologic and pathophysiologic processes. Electron-beam computed tomography (EBCT) provides accurate measurements of these traits in animals, but their reproducibility in humans has not been established. METHODS: Perfusion, volume, and flow measurements were obtained by EBCT in eight healthy human volunteers under controlled conditions on two consecutive days. RESULTS: Mean values for whole kidney, cortical, and medullary perfusion and volume obtained with EBCT were similar in scan 1 and scan 2 (P > 0.1), and correlated highly. Coefficients of variation for the repeated measurements usually were less than 10%. Values obtained for renal regional perfusion and volume agreed with previously reported values. CONCLUSIONS: Electron-beam computed tomography estimates of single whole kidney, cortical, and medullary perfusions and volumes are highly reproducible in normal humans, and may be useful to advance understanding of renal involvement in human disease.

Adult↗
PubMed1996

Effects of changes in central venous pressure on upper airway size in patients with obstructive sleep apnea.

Intraluminal airway pressure and pharyngeal muscle activity are widely recognized as major determinants of the size and collapsibility of the upper airway. In addition, changes in the volume or pressure of tissue surrounding the pharyngeal airway may significantly influence its size. The present study used fast computed tomography (CT) to determine the effects of changes in central venous pressure (CVP) on upper airway size. Ten awake male patients with obstructive sleep apnea (OSA) were studied. Scans were performed at functional residual capacity (FRC) and at the end of a tidal inspiration (VTei) under three conditions of CVP: (1) at baseline (CVP nl) with patients lying supine; (2) at decreased CVP (CVP-) by inflating blood pressure cuffs to 40 mm Hg on both legs; and (3) at increased CVP (CVP+) by elevating both legs to 33 degrees. At FRC, changes in CVP had no significant effect on either mean or minimum cross-sectional area (CSA) of the upper airway. In contrast, an analysis of variance (ANOVA) indicated that alterations in CVP were associated with changes in mean CSA (p = 0.03) and to a lesser extent in minimum CSA (p = 0.07) at VTei. With the legs elevated (CVP+), neither mean nor minimum CSA showed any significant change with tidal breathing. However, after leg-cuff inflation (CVP-), highly significant increases in both mean (163 +/- 22 to 218 +/- 19 mm2, p = 0.001) and minimum (48 +/- 8 to 85 +/- 12 mm2, p = 0.02) CSA were detected. Changes in mean and minimum CSA with tidal breathing at baseline (CVP nl) were intermediate. These results indicate that changes in CVP significantly alter the response of the upper airway to tidal breathing. They further suggest that increases in upper airway size with tidal breathing may be related to reduction in venous blood volume in pharyngeal and neck tissues as the generation of negative intrathoracic pressure during inspiration increases venous return to the chest.

Adult↗
PubMed1996

Electron beam computed tomography and coronary artery disease: scanning for coronary artery calcification.

OBJECTIVE: To review the association of coronary artery calcification with coronary atherosclerosis and its potential clinical application as detected on electron beam computed tomography (EBCT). DESIGN: A literature review of coronary artery calcification, coronary artery disease, and EBCT is presented, and clinical applications of EBCT are discussed. RESULTS: Recent studies have confirmed that arterial calcification is an active process intimately associated with atherosclerotic plaque evolution. Clinical investigations with use of EBCT have shown that a scan "negative" for coronary calcification is common in patients with normal or near-normal findings on coronary angiography, whereas patients with severe obstructive disease most commonly have "positive" scans--greater amounts of coronary artery calcium are associated with more severe luminal disease. Coronary artery calcium as evaluated on EBCT follows patterns that reflect the development of coronary atheromatous disease as a function of age and gender. Although histologic studies have confirmed that not all atherosclerotic segments have detectable calcification, the area of coronary artery calcification quantified on EBCT has a direct, positive relationship with the histopathologic coronary plaque area. CONCLUSION: The long-held notion of "degenerative" calcification of the coronary arteries with aging is incorrect. Although the incidence of coronary artery calcification increases with patient age, this relationship simply parallels the increased incidence of coronary atherosclerosis with advancing age. Data suggest that EBCT is a highly sensitive and specific test for coronary atherosclerosis and provide a basis for clinical applications when EBCT is viewed as a noninvasive method to estimate human coronary atherosclerotic involvement and "plaque burden."

Adult↗
PubMed1995

Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area. A histopathologic correlative study.

BACKGROUND: Coronary calcium identified by electron-beam computed tomography (EBCT) correlates poorly with luminal atherosclerotic narrowing, but calcium, an intimate part of coronary plaque, may be more directly related to atheromatous plaque area. METHODS AND RESULTS: Thirty-eight coronary arteries from 13 autopsy hearts were dissected, straightened, and scanned with EBCT in 3-mm contiguous increments. Coronary calcium area was defined as one or more pixels with a density > 130 Hounsfield units (0.18 mm2/pixel). Each artery was divided into corresponding 3-mm segments, representative histological sections were stained, and atherosclerotic plaque area per segment (mm2) was quantified. Coronary artery calcium and coronary artery plaque areas were correlated for the hearts as a whole, for individual coronary arteries, and for individual coronary artery segments. The sums of histological plaque areas versus the sums of calcium areas were highly correlated for each heart and for each coronary artery. However, coronary plaque area was on the order of five times greater than calcium area. Furthermore, minimal diffuse segmental coronary plaque could be present despite the absence of coronary calcium detectable by EBCT. CONCLUSIONS: This histopathologic study confirms an intimate relation between whole heart, coronary artery, and segmental coronary atherosclerotic plaque area and EBCT coronary calcium area but suggests that there is a threshold value for plaque area below which coronary calcium is either absent or not detectable by this methodology.

Adult↗
PubMed1995

Quantification of coronary artery calcium by electron beam computed tomography for determination of severity of angiographic coronary artery disease in younger patients.

OBJECTIVES: This study attempted to 1) evaluate five quantitative measures of coronary artery calcium and determine which best agreed with coronary artery disease severity at angiography; and 2) determine optimal quantity cutpoints to distinguish among no, mild and significant disease. BACKGROUND: Coronary artery calcium identified noninvasively by electron beam computed tomography is a sensitive marker for atherosclerosis. Quantitative assessments of calcium could distinguish among patients with no, mild and significant disease in clinical, screening and research settings. METHODS: One hundred sixty patients, 23 to 59 years old, underwent coronary angiography and electron beam computed tomography. Coronary artery calcium was defined as dense (> 130 Hounsfield units) foci > or = 2 mm2 on the tomogram. Regression and receiver operating characteristic analyses were used to evaluate five quantitative measures of calcium as predictors of the largest stenosis in the coronary arteries and to identify optimal cutpoints for distinguishing among disease categories. No disease was defined as no stenosis, mild disease as 10% to 49% diameter stenosis in one or more major branches and significant disease as > or = 50% diameter stenosis in one or more major branches. RESULTS: All measures evaluated performed well. With calcific area as the quantitative measure, the best cutpoint for discriminating between patients with and without disease was the presence of calcium: sensitivity 81%, specificity 86% and overall accuracy 83%. The best cutpoint for discriminating between patients with and without significant disease was 18 mm2: sensitivity 86%, specificity 81% and accuracy 83%. CONCLUSIONS: Because the ranges of calcium quantity overlapped across disease categories, no cutpoints would distinguish among categories with absolute certainty. However, selected cutpoints could rule out disease in most healthy subjects and identify most patients with significant disease.

Adult↗