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Bland-Altman Analysis (bland-altman + analysis)
Selected AbstractsNoninvasive Estimation of Pulmonary Vascular Resistance in Pulmonary HypertensionECHOCARDIOGRAPHY, Issue 5 2009Navin Rajagopalan M.D. Background: Determination of pulmonary vascular resistance (PVR) in patients with suspected or known pulmonary hypertension (PH) requires right heart catheterization. Our purpose was to use Doppler echocardiography to estimate PVR in patients with PH. Methods: Patient population consisted of 52 patients (53 ± 12 years; 35 females) who underwent Doppler echocardiography and right heart catheterization within 24 hours of each other. The ratio of peak tricuspid regurgitation velocity (TRV) and right ventricular outflow time-velocity integral (VTIRVOT) was measured via transthoracic echocardiography and correlated to invasively determined PVR. A linear regression equation was generated to determine PVR by echocardiography based upon the TRV/VTIRVOT ratio. PVR by echocardiography was compared to invasive PVR using Bland-Altman analysis. Results: Significant correlation was demonstrated between TRV/VTIRVOT and PVR by catheterization (r = 0.73; P < 0.001). However, Bland-Altman analysis showed that agreement between PVR determined by echocardiography and invasive PVR was poor (bias = 0; standard deviation = 4.3 Wood units). In a subset of patients with invasive PVR < 8 Wood units (26 patients), correlation between TRV/VTIRVOT and invasive PVR was strong (r = 0.94; P < 0.001). In these patients, agreement between PVR by echocardiography and invasive PVR was satisfactory (bias = 0; standard deviation = 0.5 Wood units). There was no correlation between TRV/VTIRVOT and invasive PVR in patients with PVR > 8 Wood units (n = 26; r = 0.17). Conclusion: While TRV/VTIRVOT correlates significantly with PVR, using it to estimate PVR in a PH patient population cannot be recommended. [source] Transthoracic Tissue Doppler Imaging of the Atria: A Novel Method to Determine the Atrial Fibrillation Cycle LengthJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2006MATTIAS DUYTSCHAEVER M.D., Ph.D. Background: The atrial fibrillation cycle length (AFCL) is a critical parameter for the perpetuation and termination of AF. In the present study, we evaluated a new method to measure the AFCL based on transthoracic tissue Doppler imaging (TDI) of the right atrium (RA) and left atrium (LA). Methods: Twenty patients with AF (6 acute AF, 14 persistent or permanent AF) were studied. A quadripolar catheter was positioned at RA or LA to measure AFCL (AFCLEGM, gold standard). Transthoracic echocardiography (apical 4-chamber view) was used to perform pulsed wave TDI at the free wall of RA or LA. AFCLTDI was defined as the time interval between two consecutive positive to negative crossings of the baseline of the atrial time velocity curves. AFCLEGM and AFCLTDI were measured at baseline and during a 10-minute infusion of flecainide (1.5 mg/kg). Results: Measurement of AFCLTDI was feasible in all but one patient. At baseline, AFCLEGM was 170 ± 22 ms, AFCLTDI 172 ± 22 ms (difference 2 ± 5 ms). AFCLTDI correlated significantly with AFCLEGM (R = 0.91, P < 0.0001). Bland-Altman analysis showed a bias of ,2 ms with a 95% limit of agreement between ,26 ms and +22 ms. During flecainide, the AFCLTDI method yielded an AFCL prolongation from 176 ± 23 ms at baseline to 279 ± 68 ms (P < 0.01) after 10 minutes of infusion (57 ± 26%). Conclusions: (1) Tissue Doppler imaging of the atria during transthoracic echocardiography can be used to reliably determine the AFCL during both acute and persistent or permanent AF. (2) Continuous measurement of AFCL with TDI can be used to monitor the effect of antiarrhythmic drugs on atrial rate during AF. (3) This novel method is attractive because of the ease of acquiring the data and its noninvasive character. [source] Adaptation and evaluation of the Randox full-range CRP assay on the Olympus AU2700®JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2007A.M. Dupuy Abstract The implementation of a high-sensitivity CRP (hs-CRP) assay as a routine laboratory parameter may be necessary. A single CRP method that could yield reliable results for the whole concentration range (0.1,200 mg/L) would be the most practical solution for the laboratory setting. The aim of this study was to assess the Randox full-range CRP assay on the Olympus AU2700® biochemistry analyzer and evaluate its analytical performance on serum and heparin plasma samples. The Randox CRP turbidimetric assay was compared with the existing CRP assay used routinely on the Olympus AU2700®. The analytical performance of the Randox CRP with both Olympus CRP reagents (CRP for normal application andhs-CRP) was good. We found that the Randox CRP method in the range of 0.5,160 mg/L was closely correlated to the Olympus CRP and hs-CRP for serum samples. According to a Bland-Altman analysis, the serum and heparinized samples showed an excellent agreement in CRP concentrations throughout the entire range (mean difference = ,0.035 ± 1.806 mg/L) as well as in CRP levels <10 mg/L. Our data indicate that Randox full-range CRP measurements using an immunoturbidimetry assay on Olympus systems perform as well for routine diagnostics as other high-sensitivity applications using serum or heparin plasma. J. Clin. Lab. Anal. 21:34,39, 2007. © 2007 Wiley-Liss, Inc. [source] Multicontrast black-blood MRI of carotid arteries: Comparison between 1.5 and 3 tesla magnetic field strengthsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2006Vasily L. Yarnykh PhD Abstract Purpose To compare black-blood multicontrast carotid imaging at 3T and 1.5T and assess compatibility between morphological measurements of carotid arteries at 1.5T and 3T. Materials and Methods Five healthy subjects and two atherosclerosis patients were scanned in 1.5T and 3T scanners with a similar protocol providing transverse T1 -, T2 -, and proton density (PD)-weighted black-blood images using a fast spin-echo sequence with single- (T1 -weighted) or multislice (PD-/T2 -weighted) double inversion recovery (DIR) preparation. Wall and lumen signal-to-noise ratio (SNR) and wall/lumen contrast-to-noise ratio (CNR) were compared in 44 artery cross-sections by paired t -test. Interscanner variability of the lumen area (LA), wall area (WA), and mean wall thickness (MWT) was assessed using Bland-Altman analysis. Results Wall SNR and lumen/wall CNR significantly increased (P < 0.0001) at 3T with a 1.5-fold gain for T1 -weighted images and a 1.7/1.8-fold gain for PD-/T2 -weighted images. Lumen SNR did not differ for single-slice DIR T1 -weighted images (P = 0.2), but was larger at 3T for multislice DIR PD-/T2 -weighted images (P = 0.01/0.03). The LA, WA, and MWT demonstrated good agreement with no significant bias (P 0.5), a coefficient of variation (CV) of <10%, and intraclass correlation coefficient (ICC) of >0.95. Conclusion This study demonstrated significant improvement in SNR, CNR, and image quality for high- resolution black-blood imaging of carotid arteries at 3T. Morphologic measurements are compatible between 1.5T and 3T. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Comparison between three-dimensional volume-selective turbo spin-echo imaging and two-dimensional ultrasound for assessing carotid artery structure and functionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2005Lindsey A. Crowe PhD Abstract Purpose To compare a volume-selective three-dimensional turbo spin echo (TSE) technique with ultrasound (US) for assessing carotid artery wall structure and function. Materials and Methods A three-dimensional volume-selective TSE technique was used to image the carotid artery in 10 healthy subjects and five hypertensive subjects (each of whom were scanned three times while they received different hypertension treatments). Lumen and wall area were measured on MR images. Two-dimensional US measurements of the intima-media thickness (IMT) and lumen diameter were taken in three orientations through a single cross section. The lumen area change over the cardiac cycle was used to determine distension. For validation, a Bland-Altman analysis was used to compare the vessel wall and lumen areas measured by three-dimensional MRI volumes with those obtained by US scans. Results Agreement between the two methods was found. The mean difference in distension between US and MRI was 1.2% (±5.1%). For the wall area measurements, good agreement was shown, but there was a systematic difference due to the visualization of the adventitia by MRI. Both techniques offer an easy way to objectively measure lumen indices. MRI can provide the complete circumference over the length of a vessel, while US is flexible and relatively inexpensive. The application of US is limited, however, when subjects are poorly echogenic. A difference between hypertensive and healthy subjects was found. Conclusion There was a good agreement between MRI and the clinically established two-dimensional US method. The MRI method has the advantage of providing increased vessel coverage, which permits one to assess localized abnormalities without assuming vessel uniformity. J. Magn. Reson. Imaging 2005;21:282,289. © 2005 Wiley-Liss, Inc. [source] Validation of 2 Techniques for Electrocardiographic Recording in Dogs and CatsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2006Luca Ferasin Background: Standard electrocardiographic (ECG) recording in the dog and cat is commonly performed in right lateral recumbency, by connecting the ECG leads to the skin of the patient via metallic alligator clips. The jaws of the alligator clips are usually filed or flattened to reduce their uncomfortable pressure on the patient's skin. However, filed and flattened alligator clips can occasionally lose their grip to the skin, causing lead detachment during standard ECG recording. Hypothesis: The aim of the study was to validate two novel ECG recording techniques ("gel" and "pads"). Animals: Six-lead standard ECG recording was obtained from 42 dogs and 40 cats using the standard technique, as well as the two novel methods. Methods: Measurements were taken of the amplitude and duration of P waves and QRS complexes, duration of PQ and QT intervals, and mean electrical axis (MEA). In each recording, five representative complexes were measured, and the results were averaged for each parameter. Results: A good quality ECG recording was obtained with all the three different techniques, although a degree of wandering trace was observed in one third of cats with the "pads" technique. Bland-Altman analysis showed good agreement between the ECG values recorded with the two novel techniques and those recorded with the standard traditional technique. Furthermore, the observed differences were not clinically relevant, except for the R wave amplitude recorded with the "pads" method in cats (-0.35 to 0.37 mV). Conclusions and Clinical Importance: In conclusion, this study supports the reliability and clinical validity of the "gel" and "pads" techniques for ECG recording both in the dog and the cat, with some limitations for the "pads" technique in cats. [source] Reliability of a new ultrasonic cardiac output monitor in recipients of living donor liver transplantation,,§¶LIVER TRANSPLANTATION, Issue 7 2008Bai-Chuan Su The ultrasonic cardiac output monitor (USCOM) is a new Doppler device for noninvasive hemodynamic monitoring. The aim of this prospective nonrandomized study was to test the feasibility, perioperative reliability, and clinical applicability of using USCOM as an alternative to pulmonary artery catheterization in recipients of living donor liver transplantation. Thirteen patients scheduled to receive living donor liver transplants were initially recruited. Three were subsequently excluded prior to the commencement of surgery because of technical difficulties in obtaining diagnostic-quality images with USCOM. Ten patients proceeded to be studied. Cardiac output measurements by thermodilution and USCOM were compared at 30-minute intervals throughout the procedure and at 10 specific procedural reference points during the surgery when hemodynamic changes were most likely to be observed. The data were analyzed with Lin's concordance coefficient and Bland-Altman analysis. Two hundred ninety paired cardiac output values were obtained from the 10 patients. The concordance between both methods was excellent in 8 patients and satisfactory in 2. Bland-Altman analysis of all data produced a mean bias of , 0.02 L/minute for USCOM, and the 95% limits of agreement were ,1.06 to +1.10 L/minute. Further analysis of the 10 reference time points showed minimal bias and high levels of agreement between the methods. We conclude that USCOM provides an accurate and noninvasive method for cardiac output measurement during liver transplantation. It may therefore represent an alternative to pulmonary artery catheter placement with consequent reduction in patient's risk and morbidity associated with catheterization. Liver Transpl 14:1029,1037, 2008. © 2008 AASLD. [source] Comparison of the USCOM ultrasound cardiac output monitor with pulmonary artery catheter thermodilution in patients undergoing liver transplantation,LIVER TRANSPLANTATION, Issue 7 2008Lai-Sze Grace Wong The aim of the study was to compare the standard technique of cardiac output determination by pulmonary artery catheter thermodilution (PAC-TD) with a noninvasive ultrasound Doppler monitor (USCOM Pty., Ltd., Coffs Harbour, Australia) in surgery for liver transplantation. We wished to determine if the degree of accuracy would allow the ultrasound cardiac output monitor (USCOM) to be used as an alternative monitor in a clinical setting in which wide fluctuations in cardiac output could be expected. This was a prospective method comparison study, with 71 paired measurements obtained in 12 patients undergoing liver transplantation in a university teaching hospital. Bland-Altman analysis of the 2 techniques showed a bias of 0.39 L/minute, with the USCOM cardiac output lower compared with that of PAC-TD. The bias was small and did not vary with the magnitude of the cardiac output. The 95% limits of agreement were ,1.47 and 2.25 L/minute. There was good repeatability for USCOM measurements, with a repeatability coefficient of 0.43 for USCOM versus 0.77 for PAC-TD. We conclude that USCOM is acceptable for the clinical determination of noninvasive cardiac output, particularly in situations in which tracking changes over time is more important than knowing the precise value. However, the utility of USCOM is limited by its inability to measure pulmonary artery pressure. Liver Transpl 14:1038,1043, 2008. © 2008 AASLD. [source] Validation of limited sampling strategy for the estimation of mycophenolic acid exposure in Chinese adult liver transplant recipientsLIVER TRANSPLANTATION, Issue 12 2007Chen Hao Mycophenolate mofetil (MMF) is indicated as immunosuppressive therapy in liver transplantation. The abbreviated models for the estimation of mycophenolic acid (MPA) area under the concentration-time curve (AUC) have been established by limited sampling strategies (LSSs) in adult liver transplant recipients. In the current study, the performance of the abbreviated models to predict MPA exposure was validated in an independent group of patients. A total of 30 MPA pharmacokinetic profiles from 30 liver transplant recipients receiving MMF in combination with tacrolimus were used to compare 8 models' performance with a full 10 time-point MPA-AUC. Linear regression analysis and Bland-Altman analysis were used to compare the estimated MPA-AUC0-12h from each model against the measured MPA-AUC0-12h. A wide range of agreement was shown when estimated MPA-AUC0-12h was compared with measured MPA-AUC0-12h, and the range of coefficient of determination (r2) was from 0.479 to 0.936. The model based on MPA pharmacokinetic parameters C1h, C2h, C6h, and C8h had the best ability to predict measured MPA-AUC0-12h, with the best coefficient of determination (r2 = 0.936), the excellent prediction bias (2.18%), the best prediction precision (5.11%), and the best prediction variation (2SD = ±7.88 mg · h/L). However, the model based on MPA pharmacokinetic sampling time points C1h, C2h, and C4h was more suitable when concerned with clinical convenience, which had shorter sampling interval, an excellent coefficient of determination (r2 = 0.795), an excellent prediction bias (3.48%), an acceptable prediction precision (14.37%), and a good prediction variation (2SD = ±13.23 mg · h/L). Measured MPA-AUC0-12h could be best predicted by using MPA pharmacokinetic parameters C1h, C2h, C6h, and C8h. The model based on MPA pharmacokinetic parameters C1h, C2h, and C4h was more feasible in clinical application. Liver Transpl 13:1684,1693, 2007. © 2007 AASLD. [source] A Computer-Based Method for Determination of the Cell-Free Layer Width in MicrocirculationMICROCIRCULATION, Issue 3 2006SANGHO KIM ABSTRACT Objectives: The cell-free layer between the erythrocyte column and the vessel wall is an important determinant of hydrodynamic resistance in microcirculatory vessels. The authors report a method for continuous measurement of the width of this layer. Methods: The light intensity of a linear array of pixels perpendicular to the vessel axis is continuously determined from a video image of a microcirculatory vessel. A threshold level based on Otsu's method is used to establish the interface between the cell-free layer and the erythrocyte column. To test the method, video images at 750,4500 frames/s were obtained from venules and arterioles in rat spinotrapezius muscle at normal and reduced arterial pressures before and after induction of erythrocyte aggregation with Dextran 500. The current measurements were compared to manual measurements of the same images. Results: Values obtained by the manual and the new methods were in agreement within the 95% confidence limit by the Bland-Altman analysis and within 90,95% range by the correlation coefficient (R2). The more frequent measurements reveal substantial, rapid variations in cell-free layer width and changes in mean values with alteration of arterial pressure and red cell aggregability. Conclusions: A new, computer-based technique has been developed that provides measurements of rapid, time-dependent variations in the width of the cell-free layer in the microcirculation. [source] Body composition in older orthopaedic rehabilitation inpatients: Are field methods valid?NUTRITION & DIETETICS, Issue 3 2010Alison YAXLEY Abstract Aim:, The assessment of body composition is an important aspect of the determination of nutritional health. This cross-sectional measurement study aimed to assess the relative validity of a range of field techniques for the measurement of body composition in a sample of older orthopaedic inpatients participating in rehabilitation. Methods:, Assessment of percent fat-free mass of 31 adults, aged 65 years and over, was conducted under fasting conditions by two types of bioelectrical impedance analysis (multi-frequency and single frequency,using manufacturer's pre-programmed prediction equation) and compared with percent fat-free mass estimated by dual energy X-ray absorptiometry, a reference technique. Data from multi-frequency bioelectrical impedance analysis were also used to calculate percent fat-free mass from the prediction equation of Dey et al. for comparison. Skeletal muscle mass was derived from assessment of corrected arm muscle area and compared with skeletal muscle mass from dual energy X-ray absorptiometry analysis. Bland-Altman analysis was performed to determine the level of agreement between each field technique and dual energy X-ray absorptiometry. Results:, Mean bias and limits of agreement between single frequency bioelectrical impedance analysis and dual energy X-ray absorptiometry were ,5.7% (,24.0, 12.6), between multi-frequency bioelectrical impedance analysis (manufacturer's pre-programmed prediction equation) and dual energy X-ray absorptiometry were 1.4% (,13.4, 16.1), between multi-frequency bioelectrical impedance analysis (Dey et al. prediction equation) and dual energy X-ray absorptiometry were ,5.0% (,16.6, 6.6) and between skeletal muscle mass as derived from assessment of corrected arm muscle area and skeletal muscle mass from dual energy X-ray absorptiometry analysis ,0.97 kg (,8.37, 6.43). Conclusion:, None of the methods assessed are clinically acceptable for assessment of body composition in older orthopaedic rehabilitation patients; however, estimation of skeletal muscle mass, as derived from corrected arm muscle area, is likely to be of more use in the clinical setting as there is no requirement for patients to be fasted. [source] Point-of-care reversal treatment in phenprocoumon-related intracerebral hemorrhageANNALS OF NEUROLOGY, Issue 6 2010Timolaos Rizos MD Objective Rapid reversal of the anticoagulatory effect of vitamin K antagonists represents the primary emergency treatment for oral anticoagulant-related intracerebral hemorrhage (OAC-ICH). Predicting the amount of prothrombin complex concentrate (PCC) needed to reverse OAC in individual patients is difficult, and repeated international normalized ratio (INR) measurements in central laboratories (CLs) are time-consuming. Accuracy and effectiveness of point-of-care INR coagulometers (POCs) for INR reversal in OAC-ICH have not been evaluated. Methods In phase 1, the agreement of emergency POC and CL INR measurements was determined. In phase 2, stepwise OAC reversal was performed with PCC using a predetermined dosing schedule. Concordance of POC and CL INR measurements during reversal and time gain due to POC were determined. Results In phase 1 (n = 165), Bland-Altman analysis showed close agreement between POCs and CLs (mean INR deviation 0.04). In phase 2 (n = 26), POCs caused a median initial net time gain of 24 minutes for the start of treatment with PCC. Median time for POC-documented complete OAC reversal was 28 minutes, compared with 120 minutes for CLs. Bland-Altman analysis between POCs and CLs revealed a mean INR deviation of 0.13 during stepwise PCC administration. POCs tended to slightly overestimate the INR, especially at higher INR levels. Remarkably, POC-guided reversal led to a median reduction of 30.5% of PCC dose compared with the a priori dose calculation. Hematomas enlarged in 20% of patients. Interpretation POC INR monitoring is a fast, effective, and economic means of PCC dose-titration in OAC-ICH. Larger studies examining the clinical efficacy of this procedure are warranted. ANN NEUROL 2010;67:788,793 [source] 2352: The influence of central corneal thickness and corneal biomechanics in glaucomaACTA OPHTHALMOLOGICA, Issue 2010FC LAM Purpose To look at the impact that central corneal thickness and corneal biomechanics can have on intraocular pressure (IOP) measurements and their effect on visual fields. Methods Written and informed consent from patients and guidance from the local research ethics committee was obtained. Ocular diagnoses and ocular medications were recorded. IOPs were recorded using Goldmann applanation tonometry (GAT)followed by dynamic contour tonometry with the Pascal tonometer. Central corneal thickness(CCT) was measured using ultrasound. Visual fields were recorded using Humphries perimetry. Bland-Altman plots were used to compare the 2 methods. Results 92 eyes of 46 patients were included. Median CCT 556µm(range:427µm-634µm). Despite a good correlation of the IOP measurements usin the two different techniques(r=0.7; p< 0.01), there was a significant difference in limits of agreement(LOA) of DCT to GAT on the Bland-Altman analysis. The LOA was 8.6mmHg to -4.8mmHg with a mean bias of 1.9mmHg. This persisted even after correction for CCT. Ocular hypertensives had a wider LOA than glaucoma patients. Conclusion DCT IOP measurements can be significantly different from GAT IOPs even after taking into account central corneal thickness. Compared to CCT, corneal hysteresis appears to have a greater impact on IOP measurements. This could have important prognostic implications. [source] Can the Broselow Tape Be Used to Estimate Weight and Endotracheal Tube Size in Korean Children?ACADEMIC EMERGENCY MEDICINE, Issue 5 2007Hye Young Jang MD BackgroundThe Broselow pediatric emergency tape (BT) was developed to provide a length-based estimate of body weight and equipment size during resuscitation. ObjectivesTo conduct a validation study on the use of the BT in Korean children. MethodsAnesthesia records from children were retrospectively reviewed. The measured weights of the subjects were compared with the BT weight estimates by using Bland-Altman analysis. The accuracy of the BT and age-based formula in predicting the endotracheal tube (ETT) size were also compared. The authors drew a receiver operating characteristics (ROC) curve to evaluate the cutoff height that would be acceptable for the application of BT without error in Korean children. ResultsA total of 665 children (mean [± SD] age, 5.1 [± 3.3] years, 61.8% male) were enrolled. The average measured weight of the Korean children was 1.54 kg heavier than the BT estimates (95% CI = 1.24 to 1.85 kg). The BT estimates showed better agreement with the actually used ETT sizes than did the age-based formula estimates (86.9% vs. 34.9%, p < 0.001). The cutoff height of the ROC curve was 127.15 cm. When the BT was used in children who were shorter than the cutoff height, 98.8% of the enrolled children's estimated weights were within the limits of agreement. ConclusionsThe BT can be used in Korean children as a helpful adjunct during resuscitation to estimate the weight and ETT size. [source] Could the coefficient of variation (COV) of the corneal endothelium be overestimated when a centre-dot method is used?CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 1 2008Michael J Doughty PhD Background:, Little has been published on the reliability of estimates of the coefficient of variation (COV) in cell area for human corneal endothelia. The present study compares two methods. Methods:, A non-contact specular micrograph (Topcon SP-2000P) was obtained from the central region of the corneal endothelium of 20 healthy myopic white European subjects, aged from 32 to 53 years, half of whom were successful long-term soft contact lens wearers. The captured image file was either assessed using a machine-based algorithm, in which 25 cells in the middle of the image were marked and their areas reported (designated as ,centre-dot' method) or by a manual method, by which all the cells in the image were outlined on very high magnification prints of the endothelia and the cell areas measured by a manual digitiser in stream mode. The average cell area was used to calculate the endothelial cell density (ECD), while the COV was calculated from the standard deviation (SD) of the cell area measures. Results:, Identical mean cell area values were found (392 µm2) with the two methods, a marginally higher ECD estimate (2,594 versus 2,569) with the centre-dot method (p = NS) but a much higher COV with the centre-dot method (43.8 versus 29.0 per cent). This highly statistically significant difference in COV (p < 0.001) was seen in both contact lens wearers and non-contact lens wearers. A Bland-Altman analysis reveals a bias in the centre-dot method, especially for the COV estimates, that appears to be linked to erroneous definition of a single large cell domain on any individual image. Conclusions:, A centre-dot method can be reliably used to generate useful data on cell area and ECD but it should be used cautiously for estimates of polymegethism (COV). [source] | ||||||||||