Magnetic resonance mapping demonstrates benefits of VEGF-induced myocardial angiogenesis.

Coronary occlusive disease is the leading cause of death in industrial nations and affects one in four adults. Although heart attacks are caused by occlusion of a coronary artery, some patients have occlusions without infarction because they have sufficient collateral vessels providing an alternate pathway for blood supply. Vascular endothelial growth factor (VEGF) is an angiogenic peptide that can stimulate collateral vessel development in the ischaemic myocardium. We used magnetic resonance imaging (MRI) and image processing to identify and quantify non-invasively the benefits related to VEGF infusion on collateral development in the heart. This was accomplished as a placebo-controlled study in the porcine model of chronic ischaemia that most closely mimics the human pathophysiology of progressive coronary occlusion. Image series converted to a space-time map demonstrated that with treatment the ischaemic zone was smaller and the contrast arrival delay was less, which resulted in better ejection fraction and regional wall thickening. These findings demonstrate in a manner applicable to humans, that VEGF improves collateral blood supply, resulting in improved cardiac global and regional function after and in spite of coronary artery occlusion.

Significant exercise-induced hypoxaemia with equivocal desaturation in patients with chronic obstructive pulmonary disease.

BACKGROUND: The wide 95% confidence interval for S(a)O2 measured by pulse oximetry (S(P)O2) and the inherent characteristics of the oxyhaemoglobin dissociation curve can lead to modest but significant decreases in P(a)O2 (deltaP(a)O2 > or = 5 mmHg) that may be under-appreciated. AIM: To avoid missing potentially significant deltaP(a)O2 by using S(P)O2, this study establishes a threshold of deltaS(P)O2 to detect deltaP(a)O2 by examining the correlation between deltaS(P)O2 and deltaP(a)O2. METHODS: We enrolled 29 elderly patients with moderate to severe chronic obstructive pulmonary disease as assessed by lung function testing. Arterial blood gases and S(P)O2 measurements were carried out during maximal exercise testing. The patients were assigned to groups based on P(a)O2 measurements: group 1 had P(a)O2 at peak exercise (P(a)O2peak) > or = 60 mmHg without a deltaP(a)O2; group 2 had P(a)O2peak > or = 60 mmHg with a deltaP(a)O2; group 3 had P(a)O2peak < 60 mmHg without a deltaP(a)O2; and group 4 had P(a)O2peak < 60 mmHg with a deltaP(a)O2. RESULTS: The study population was evenly distributed between groups 1, 2 and 4. However, group 3 did not have any patients enrolled in this study that met group 3 criteria. The sensitivity of pulse oximetry required to detect S(a)O2 below 90% was 19%. DeltaS(P)O2 of 3% may increase the low sensitivity of S(P)O2 and was shown by a 92% positive predictive value for deltaP(a)O2 > or = 5 mmHg. CONCLUSION: This study suggests that important changes in oxygenation may be avoided if using deltaS(P)O2 rather than absolute values of S(P)O2 in patients with chronic obstructive pulmonary disease undergoing exercise testing to detect exercise-induced hypoxaemia.

Importance of imaging method over imaging modality in noninvasive determination of left ventricular volumes and ejection fraction: assessment by two- and three-dimensional echocardiography and magnetic resonance imaging.

OBJECTIVES: This study sought to determine the concordance between biplane and volumetric echocardiography and magnetic resonance imaging (MRI) strategies and their impact on the classification of patients according to left ventricular (LV) ejection fraction (EF) (LVEF). BACKGROUND: Transthoracic echocardiography and MRI are noninvasive imaging modalities well suited for serial evaluation of LV volume and LVEF. Despite the accuracy and reproducibility of volumetric methods, quantitative biplane methods are commonly used, as they minimize both scanning and analysis times. METHODS: Thirty-five adult subjects, including 25 patients with dilated cardiomyopathies, were evaluated by biplane and volumetric (cardiac short-axis stack) cine MRI and by biplane and volumetric (three-dimensional) transthoracic echocardiography. Left ventricular volume, LVEF and LV function categories (LVEF > or =55%, >35% to <55% and < or =35%) were then determined. RESULTS: Biplane echocardiography underestimated LV volume with respect to the other three strategies (p < 0.01). There were no significant differences (p > 0.05) between any of the strategies for quantitative LVEF. Volumetric MRI and volumetric echocardiography differed by a single functional category for 2 patients (8%). Six to 11 patients (24% to 44%) differed when comparing biplane and volumetric methods. Ten patients (40%) changed their functional status when biplane MRI and biplane echocardiography were compared; this comparison also revealed the greatest mean absolute difference in estimates of EF for those subjects whose EF functional category had changed. CONCLUSIONS: Volumetric MRI and volumetric echocardiographic measures of LV volume and LVEF agree well and give similar results when used to stratify patients with dilated cardiomyopathy according to systolic function. Agreement is poor between biplane and volumetric methods and worse between biplane methods, which assigned 40% of patients to different categories according to LVEF. The choice of imaging method (volumetric or biplane) has a greater impact on the results than does the choice of imaging modality (echocardiography or MRI) when measuring LV volume and systolic function.

Effect of increased body mass index on accuracy of two-dimensional echocardiography for measurement of left ventricular volume, ejection fraction, and mass.

We used 2- and 3-dimensional echocardiography to determine left ventricular volume, mass, and ejection fraction in overweight (body mass index [BMI] > or = 25 kg/m2), obese (BMI > or = 30 kg/m2), and control (BMI < 25 kg/m2) subjects. Compared with corresponding magnetic resonance imaging measurements, 3-dimensional echocardiography is more accurate than 2-dimensional echocardiography in all patients, but particularly in overweight and obese subjects.

Relation between the number of image planes and the accuracy of three-dimensional echocardiography for measuring left ventricular volumes and ejection fraction.

The relation between accuracy of 3-dimensional echocardiography (3DE) in determining left ventricular end-diastolic volume, end-systolic volume, and ejection fraction (compared with magnetic resonance imaging) and the number of component planes used for 3DE ventricular reconstruction was evaluated in 41 adult subjects with normal (n = 24) and abnormal (n = 17) left ventricles. Accuracy and confidence of 3DE gradually increased with use of additional component planes, so that > or = 10 planes from both parasternal and apical windows provided 3DE reconstructions that accurately predict magnetic resonance imaging-measured left ventricular volumes and ejection fraction with confidence.

A noninvasive assessment of pulmonary perfusion abnormality in patients with primary pulmonary hypertension.

STUDY OBJECTIVES: The ventilatory equivalent for CO(2) (ie, the ratio of minute ventilation [VE] to carbon dioxide output [VCO(2)]) is increased in patients with primary pulmonary hypertension (PPH) consequent to an increase in physiologic dead space and alveolar ventilation. We wished to see whether the VE/V(2) ratio correlated with the abnormality in pulmonary hemodynamics in PPH patients and whether it changed in response to prostacyclin infusion. METHODS: Following right-sided heart catheterization, 10 patients with severe PPH were studied in the coronary-care unit while hemodynamic and gas exchange measurements were measured simultaneously before and after infusion with epoprostenol (Epo), a prostacyclin analog. Studies were performed at baseline and during IV infusion of two to three increasing dosages of Epo in 10 PPH patients (NYHA class III-IV). Four patients had radial artery catheters for simultaneous blood gas measurements. Nine healthy subjects who were matched by sex, height, and weight underwent gas exchange analyses only. RESULTS: The mean (+/- SD) VE/VCO(2) ratio was higher in PPH patients than in control subjects (50.7 +/- 9.7 vs 30.6 +/- 3.8; p < 0.001). Thirteen measurements made in four patients showed that the VE/VCO(2) ratio correlated with the physiologic dead space/tidal volume ratio (r = 0.78; p = 0.002). The VE/VCO(2) ratio measurement at baseline correlated significantly with total pulmonary vascular resistance (TPVR) (r = 0.70; p = 0.02) but not with mean pulmonary artery pressure (mPAP) or cardiac index. During Epo infusion, the VE/VCO(2) ratio decreased with increasing dosage in 6 of 10 patients, with no change or slight increases in the 4 remaining patients. Considering all doses, the VE/VCO(2) ratio decreased significantly in response to the short-term administration of Epo. The decrease tended to parallel the pattern of decrease in TPVR, but the changes in both variables were too small to provide a statistically significant correlation. The mPAP did not change significantly in response to Epo infusion, although TPVR did change at the highest dosage. CONCLUSIONS: In patients with severe PPH, the VE/VCO(2) ratio correlated significantly with TPVR but not with mPAP or cardiac index. The VE/VCO(2) ratio decreased systematically from baseline with the dose of Epo in some but not all patients. The VE/VCO(2) ratio and TPVR decreased significantly in response to Epo when all doses were considered. Further studies are needed to elucidate whether noninvasive gas exchange measurements may be clinically useful in the evaluation of the severity of pulmonary vascular disease and the effectiveness of pulmonary vasodilator therapy.

Comparison of exercise cardiac output by the Fick principle using oxygen and carbon dioxide.

BACKGROUND AND STUDY OBJECTIVE: Theoretically, cardiac output (CO) calculated by the Fick principle should be the same using O(2) (CO[O2]) or CO2 (CO[CO2]) as the test gas. However, agreement depends on the accuracy of gas exchange and blood gas measurements and the validity of the equations to convert measured variables into blood gas contents. Considering the widespread use of indirect estimates of pulmonary artery blood PCO2 and CO2 content to measure Fick principle CO during exercise, we wished to determine whether CO[O2] and CO[CO2] were equal during exercise and whether CO[CO2] could be accurately and precisely determined using direct measures of pulmonary artery blood. PREPARATION AND METHODS: Five healthy young nonsmoking volunteer men performed incremental exercise from rest to peak exercise on two separate occasions with intervening rest. Catheters were placed in brachial and pulmonary arteries to allow repeated blood sampling every minute during concurrent breath-by-breath gas exchange measurements from rest to peak exercise. CO[O2] was compared with CO[CO2] at multiple levels of exercise. Using standard equations, arterial and mixed venous O2 contents were calculated from hemoglobin concentration (Hb), oxyhemoglobin saturation (SO2), and PO2, whereas CO2 contents were calculated from PCO2, pH, Hb, and SO2. Blood gas analyzers were used for measurement of pH, PCO2, and PO2, and a co-oximeter was used for measurement of Hb and SO2. Initial calculations suggested that exercise CO[CO2] was 14% higher than CO[O2] and helped disclose small systematic measurement errors in PCO(2) for values > 45 mm Hg detected by proficiency testing surveys and documented with blood tonometry in the blood gas analyzer. RESULTS: After correcting PCO2 for the small systematic measurement error found, the measures and equations used to calculate arterial and mixed venous O2 and CO2 contents were adequate to provide mean CO values that are reasonably similar. However CO[CO2] values were more than twice as variable as CO[O2]. CONCLUSIONS: The increased variability of Fick principle CO[CO2] compared with CO[O2] is attributable to the much lower extraction ratio for CO2 and the greater complexity in calculation of blood CO2 than O2 contents. These results raise concerns about the accuracy and precision of estimating CO and stroke volume using CO2 as a test gas, even with direct measurement of blood CO2 contents in normal subjects.

Aerobically generated CO(2) stored during early exercise.

Previous studies have shown that a metabolic alkalosis develops in the muscle during early exercise. This has been linked to phosphocreatine hydrolysis. Over a similar time frame, the femoral vein blood pH and plasma K(+) and HCO(-)(3) concentrations increase without an increase in PCO(2). Thus CO(2) from aerobic metabolism is converted to HCO(-)(3) rather than being eliminated by the lungs. The purpose of this study was to quantify the increase in early CO(2) stores and the component due to the exercise-induced metabolic alkalosis (E-I Alk). To avoid masking the increase in CO(2) stores by CO(2) released as HCO(-)(3) buffers lactic acid, the transient increase in CO(2) stores was measured only for work rates (WRs) below the lactic acidosis threshold (LAT). The increase in CO(2) stores was evident at the airway starting at approximately 15 s; the increase reached a peak at approximately 60 s and was complete by approximately 3 min of exercise. The increase in CO(2) stores was greater, but the kinetics were unaffected at the higher WR. Three components of the change in aerobically generated CO(2) stores were considered relevant: the carbamate component of the Haldane effect, the increase in CO(2) stores due to increase in tissue PCO(2), and the E-I Alk. The Haldane effect was calculated to be approximately 5%. Physically dissolved CO(2) in the tissues was approximately 30% of the store increase. The remaining E-I Alk CO(2) stores averaged 61 and 68% for 60 and 80% LAT WRs, respectively. The kinetics of O(2) uptake correlated with the time course of the increase in CO(2) stores; the size of the O(2) deficit correlated with the size of the E-I Alk component of the CO(2) stores. We conclude that a major component of the aerobically generated increase in CO(2) stores is the new HCO(-)(3) generated as phosphocreatine is converted to creatine.

Combined bronchoalveolar lavage and polymerase chain reaction in the diagnosis of pulmonary tuberculosis in smear-negative patients.

SETTING: The polymerase chain reaction (PCR) may be sensitive and specific for the diagnosis of tuberculosis, but most reports are of studies conducted in well-controlled laboratories. A study to evaluate the clinical value of bronchoalveolar lavage (BAL) combined with PCR was necessary. OBJECTIVE: One hundred and thirty one patients were recruited into the study from March 1994 to February 1997. DESIGN: Patients with a positive acid-fast stain on sputum smear were recruited into group A as positive controls, patients with lung cancer and a negative acid-fast stain on sputum smear were put into group B as negative controls, and patients who had clinical symptoms of pulmonary TB without sputum or with negative smear results were the investigating group. PCR was performed on the sputum samples from group A and B patients and on the BAL fluid from those in group C. RESULTS: The sensitivity of PCR was 96% in group A, and the specificity was 100% in group B. The sensitivity of PCR in the BAL fluid from the group C patients was 36% and the specificity was 96%; the positive predictive value was 94% and the negative predictive value was 45%. CONCLUSION: BAL plus PCR is useful in the rapid diagnosis of pulmonary TB in non-productive or smear-negative patients.

Three-dimensional echocardiography improves accuracy and compensates for sonographer inexperience in assessment of left ventricular ejection fraction.

This study was performed to determine whether 3-dimensional echocardiography (3DE) with a magnetic tracking system for image plane localization, which unlike standard 2-dimensional echocardiography (2DE), does not require acquisition of specific image planes or "standard views" for quantitative measurement of left ventricular volume and ejection fraction (EF), could compensate for sonographer inexperience. Eight adults underwent magnetic resonance imaging (MRI) scanning; they also had 2DE and 3DE performed by 2 experienced and 3 novice sonographers. Data were analyzed by a single expert reader blinded to patient and sonographer identity. Linear regression of MRI EF (reference standard) against echocardiographic EF yielded the following results, where RD indicates the residual difference between measured MRI values and those predicted using echocardiographic results: expert 3DE: r = 0.97, RD = 2.4%, and r = 0.96, RD = 2.8%; novice 3DE: r = 0. 83, RD = 5.1%, to r = 0.95, RD = 4.8%; expert 2DE: r = 0.85, RD = 4. 8%, and r = 0.86, RD = 4.9%; and novice 2DE: r = 0.34, RD = 11.7%, to r = 0.69, RD = 6.6%. Comparison of error variances indicated that novices who used 3DE equaled the performance of experts who used 2DE, although experts were always more accurate than novices when both used the same echocardiographic method (3DE vs 3DE, 2DE vs 2DE). In a comparison of methods, 3DE was always superior to 2DE, regardless of sonographer experience. Three-dimensional echocardiography allows even novice sonographers to obtain diagnostic-quality data sets, which they were unable to accomplish with 2DE. These results suggest that scanning with 3DE, combined with remote expert interpretation, may be useful in providing echocardiographic services in regions where they are presently unavailable.

Impact of on-line endocardial border detection on determination of left ventricular volume and ejection fraction by transthoracic 3-dimensional echocardiography.

This study was performed to determine whether use of on-line automated border detection (ABD) could reduce data analysis time for 3-dimensional echocardiography (3DE) while maintaining accuracy of 3DE in measures of left ventricular (LV) volumes and ejection fraction (EF). The study proceeded in 2 phases. In the validation phase, 20 subjects were examined with the use of 3DE and of monoplane 2-dimensional (2D) ABD. Results were compared with the reference standard of magnetic resonance imaging (MRI). In the test phase, 20 subjects underwent two 3DE studies (once with images optimized for visual border definition and once with images optimized for ABD border tracking) and a conventionally used 2D ABD study. For 3DE, volumes and EF were determined with the use of manually traced borders and ABD. Analysis times were recorded with a digital stopwatch. In the validation phase, 3DE and MRI results correlated very well (r = 0.99) without systematic differences. Comparison of 2D ABD with MRI showed good correlation for LV volumes (r >/= 0.90) and EF (r = 0.85) despite significant underestimation. For the test phase, Acoustic Quantification-optimized 3-dimensional datasets underestimated end-diastolic volume and EF relative to visually optimized 3-dimensional datasets regardless of whether borders were hand-traced or ABD was used. However, correlations ranged from r = 0.96 to r = 0.98 for LV volumes and 0.88 to 0.91 for LV EF and were superior to those for 2D ABD. Data analysis times decreased moderately with the use of ABD, but scan times increased; total study times were unchanged. Use of on-line ABD with 3DE reduces data analysis time and is more accurate than conventional monoplane 2D ABD but results in underestimation of LV volumes and EF. Additional automated postprocessing techniques may be required to obtain accurate measures, consistently using 3DE in conjunction with on-line ABD.

The body weight-walking distance product as related to lung function, anaerobic threshold and peak VO2 in COPD patients.

The product of walking distance and body weight (D x W) mimics the work of walking. We hypothesized the superiority of D x W to walking distance (D) alone in any correlation with lung function, anaerobic threshold (AT) and maximal oxygen uptake (VO2max). We further hypothesized that the D x W product for a 6-min walk test (6 MWT) would correlate with the AT and VO2max because all three are markers of exercise ability. Thirty-three male chronic obstructive pulmonary disease (COPD) patients with mean forced expiratory volume in 1 sec (FEV1) of 1.2+/-0.4 l (range 0.58-1.86 l) were enrolled. Six patients were excluded due to inability to achieve a maximal test. Lung function and self-assessed every-day activities using a oxygen-cost diagram were evaluated before entry of the study. A maximal effort ramp-pattern cardiopulmonary exercise test (CPET) and a 6 MWT were conducted in random order. Borg score, heart rate, and O2 saturation with pulse oximetry (SpO2) were measured during both exercise tests. VO2 AT and minute ventilation were also measured during the CPET. Correlations were sought between the distance covered in the 6 MWT, and the D x W product with AT, VO2max and other variables. The average D and D x W were 456 m and 27.5 kg km(-1), respectively. D x W was superior to D alone when correlated with the VO2max and AT determined from the CPET, while modestly correlated with the change (delta) in Borg score and delta SpO2 in the 6 MWT and self-assessed every-day activities. Distance x weight product was correlated with the AT and VO2max. In addition, D x W was better correlated with diffusing capacity for carbon monoxide and vital capacity than D alone. We conclude that D x W mimics the work of walking better than D and is suggested as a parameter for evaluation of patients' fitness if gas exchange measurements are not available.

Patient motion compensation during transthoracic 3-D echocardiography.

Bulk patient motion during transthoracic 3-D echocardiography (3DE) produces image plane misregistration and errors in left ventricular (LV) volume and ejection fraction (EF). To correct for patient motion, we used a magnetic locating system to track both the ultrasound transducer and the chest wall of the patient, so images could be registered in a patient-centered coordinate system ("correction"). Fourteen subjects each underwent 3DE, with deliberate patient motion, to measure LV volume and EF. Results were compared to magnetic resonance imaging (MRI). Without correction, 3DE differed significantly from MRI (EF: r = 0.78, SEE = 5.8%). Application of correction increased 3DE accuracy, despite patient motion (EF: r = 0.91, SEE = 3.7%), to a level comparable to that of 3DE in the absence of motion (EF: r = 0.93, SEE = 3.5%). Patient motion during 3DE examination can be corrected using a magnetic spatial location system.

Early chylopneumothorax in a patient with pulmonary lymphangioleiomyomatosis.

A 50-year-old woman was admitted with the complaint of cough and dyspnea on exertion for the previous two months. A radiograph of the chest showed a right-sided hydropneumothorax, which was proven to be a chylous effusion by lipoprotein electrophoresis and was very refractory to tetracycline-pleurodesis. The chylopneumothorax was cured by ligation of the thoracic duct and surgical pleurodesis. After an open lung biopsy, lymphangioleiomyomatosis (LAM) was diagnosed histopathologically with smooth muscle nodules scattered throughout the lungs, obstructing the small airways, venules and lymphatics. An immunohistochemistry study using the avidin biotin complex method with monoclonal antibodies for actin and desmin showed the small nodules to be of muscle origin. During the past two years, the patient has remained stable both in respiratory status and roentgenographically without hormonal manipulation or oophorectomy. We present this case to illustrate the heterogeneous nature of this condition. While our patient's initial presentation was acute and associated with chylothorax, her postoperative course has shown no progression despite withholding of hormonal therapy.

Comparison of estimated and measured maximal oxygen uptake during exercise testing in patients with chronic obstructive pulmonary disease.

BACKGROUND: Maximal oxygen uptake (VO(2max)) and exercise modalities such as walking and standard pulmonary function testing are measurements that have been used by the surgical community as an indication of a patient's current exercise capacity to predict operative outcomes. There are equations available in published reports that allow an estimate of VO(2max) to be made by measuring a combination of the distance walked as well as lung function in patients with chronic obstructive -pulmonary disease (COPD). AIMS: The aim of the present study was to determine if estimates of VO(2max) and measured VO(2max) based on predictive equations are useful in individuals with COPD. METHODS: Twenty-eight male patients (mean age 68 years) with a mean forced expiratory volume in 1 s of 1.3 L were enrolled in the study after determining that they could perform a maximal exercise study. The estimated VO(2max) using equations reported by Chuang et al. and Cahalin et al. was cross-validated with the measured VO(2max) determined during cardiopulmonary exercise testing. RESULTS: The mean estimated VO(2max) using the pre-diction equation did not differ from the mean measured VO(2max) (1.13 vs 1.18 L/min, respectively; P = 0.25). However, the scattered relationship between the measured and the estimated VO(2max) did not support the use of this equation to predict an individual's performance. The prediction equations currently available in published reports significantly underestimate the measured VO(2max) (P < 0.05-10(-12)). CONCLUSIONS: It is recommended that VO(2max) is measured rather than estimated using the prediction equations when a VO(2max) measurement is used for clinical decision-making.

Bilateral diaphragmatic paralysis--a rare cause of acute respiratory failure managed with nasal mask bilevel positive airway pressure (BiPAP) ventilation.

A 68 yr old woman presented with acute respiratory failure. She was suspected of having a phrenic-diaphragmatic impairment, without evidence of an intrinsic lung disease or generalized neuromuscular disorder, after 3 weeks of prolonged mechanical ventilation. A series of studies, including fluoroscopy, phrenic nerve stimulation test and diaphragmatic electromyography, was performed before the diagnosis of bilateral diaphragmatic paralysis (BDP) was confirmed. The patient was successfully weaned from the conventional mechanical ventilator, and was placed on nasal mask bi-level positive airway pressure (BiPAP) ventilation. A high degree of clinical suspicion of bilateral diaphragmatic paralysis should always be raised in patients suffering respiratory failure without definite predisposing factors. Weaning with noninvasive nasal mask ventilation should be tried first instead of direct tracheostomy.

Adaptive correction of imaging plane position in segmented k-space cine cardiac MRI.

Variability among breath-holds frequently produces registration errors, a situation that may contribute to reproducibility error in anatomic indices. A navigator-echo-based method for real-time prospective correction of imaging slice level was applied to breath-hold cine cardiac imaging of 13 subjects. Repeat acquisitions with correction in the cardiac short-axis orientation showed significantly improved reproducibility in fractional area change and endocardial centroid location as compared with conventional noncorrected methods.

Elastance of the pleural space: a predictor for the outcome of pleurodesis in patients with malignant pleural effusion.

BACKGROUND: In patients who have malignant pleural effusion, it is difficult to diagnose trapped lung before thoracoscopy, thoracostomy, and drainage of the effusion. Predicting the outcome of pleurodesis in patients who have malignant pleural effusion without trapped lung is also difficult. OBJECTIVE: To investigate the factors that may be useful in diagnosing trapped lung and predicting the outcome of pleurodesis. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: 65 patients with symptomatic malignant pleural effusion. INTERVENTION: A chest tube was inserted for drainage of the effusion, and pleurodesis was done using bleomycin as the sclerosant. MEASUREMENTS: The pH and glucose levels of the effusion and the elastance of the pleural space (defined as the decline in pleural fluid pressure in cm H2O after removal of 500 mL of effusion) were measured. The outcome of pleurodesis was evaluated 1 month after the chest tube was removed. RESULTS: Patients with an elastance of 19 cm H2O or more had a higher incidence of trapped lung (11 of 14 patients) than did those with an elastance less than 19 cm H2O (3 of 51 patients) (P < 0.001). None of the 14 patients with an elastance of 19 cm H2O or more and none of the 14 patients with a trapped lung had successful pleurodesis. Forty-two of 43 patients with an elastance less than 19 cm H2O who did not have a trapped lung had successful pleurodesis. Elastance seemed to be the best predictor for trapped lung and outcome of pleurodesis, although outcome was also correlated with pH and glucose levels of the effusion. Low-dose bleomycin (30 mg) is as effective as the usual dose of bleomycin (60 mg) for pleurodesis. CONCLUSION: In patients with symptomatic malignant pleural effusion, measurement of the elastance of the pleural space is a simple and effective method for the diagnosis of trapped lung and prediction of the outcome of chemical pleurodesis with bleomycin.

Prospective navigator correction of image position for coronary MR angiography.

PURPOSE: To determine the potential benefit of prospective navigator correction of image position for coronary magnetic resonance (MR) angiography. MATERIALS AND METHODS: Two-dimensional MR angiograms were obtained with free breathing in 12 adult subjects. Navigator gating was used with and without prospective correction and with gating windows set at 3, 5, and 7 mm. MR angiograms were compared with those obtained with conventional, end-expiratory breath holding. RESULTS: Navigator gating with correction resulted in image quality equivalent to that obtained with breath holding, even with the 7-mm gating window. In contrast, navigator gating without correction allowed only maintenance of image quality similar to that obtained with breath holding for the 3- and 5-mm windows and resulted in decreased image quality with the 7-mm window (P < .05). Use of navigator gating with correction and the 7-mm window resulted in a 28% decrease in imaging time compared with breath holding and a 33% decrease compared with the 3-mm gating window (P < .05 for both comparisons). CONCLUSION: Prospective, adaptive navigator correction of image position for free-breathing coronary MR angiography is a promising, novel approach to compensate for respiratory motion.