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Value of CACS compared with ETT and myocardial perfusion imaging for predicting long-term cardiac outcome in asymptomatic and symptomatic patients at low risk for coronary disease: clinical implications in a multimodality imaging world.
Chang, SM, Nabi, F, Xu, J, Pratt, CM, Mahmarian, AC, Frias, ME, Mahmarian, JJ
JACC. Cardiovascular imaging. 2015;(2):134-44
Abstract
OBJECTIVES This prospective, observational study in 988 asymptomatic or symptomatic low-risk patients without prior coronary artery disease was conducted to define the relative value of coronary artery calcium score (CACS), exercise treadmill testing (ETT), and stress myocardial perfusion single-photon emission computed tomography (SPECT) variables in predicting long-term risk stratification. BACKGROUND CACS, ETT, and stress myocardial perfusion SPECT results predict patients' outcome. There are currently no data comparing their relative value in long-term risk stratification. METHODS Patients were stratified by Framingham risk score (FRS), with a median follow-up of 6.9 years. Cardiac events were defined as a composite of cardiac death, nonfatal myocardial infarction, and the need for coronary revascularization. Most patients (87%) were considered appropriate candidates for functional testing as defined by current appropriate use criteria. RESULTS The long-term cardiac event rate was 11.2% (1.6% per year). Multivariate risk predictors in all patients and in the appropriate use cohort were abnormal SPECT (hazard ratio [HR]: 1.83 and 1.99), ETT ischemia (HR: 1.70 and 1.76), decreasing exercise capacity (HR: 1.11 and 1.17), decreasing Duke treadmill score (HR: 1.07 for both), and CACS severity (HR: 1.29 for both), respectively. Throughout the 10-year follow-up, CACS improved risk prediction, with event rates ranging from 0.6% per year (CACS ≤10) to 3.7% per year (CACS >400) (p < 0.0001). CACS also improved risk prediction in all patients, in the appropriate use cohort and among those with low-risk ETT and SPECT results (all, p < 0.001). Area under the receiver-operating characteristic curve was increased when CACS variables (from 0.63 to 0.70; p = 0.01) but not ETT variables (from 0.63 to 0.65) were added to FRS. Moreover, net reclassification improvement was significantly increased when CACS was added to FRS + functional variables in all patients and in the appropriate use cohort (both, p < 0.0001). CONCLUSIONS CACS significantly improved long-term risk stratification beyond FRS, ETT, and SPECT results across the spectrum of clinical risk and importantly even among those who are currently considered appropriate candidates for functional testing or have low-risk functional test results. Our findings support CACS as a first-line test over ETT or SPECT for accurately assessing long-term risk in such patients.
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Glucagon-like peptide-1 receptor imaging for the localisation of insulinomas: a prospective multicentre imaging study.
Christ, E, Wild, D, Ederer, S, Béhé, M, Nicolas, G, Caplin, ME, Brändle, M, Clerici, T, Fischli, S, Stettler, C, et al
The lancet. Diabetes & endocrinology. 2013;(2):115-22
Abstract
BACKGROUND Small benign insulinomas are hard to localise, leading to difficulties in planning of surgical interventions. We aimed to prospectively assess the insulinoma detection rate of single-photon emission CT in combination with CT (SPECT/CT) with a glucagon-like peptide-1 receptor avid radiotracer, and compare detection rates with conventional CT/MRI techniques. METHODS In our prospective imaging study, we enrolled adults aged 25-81 years at centres in Germany, Switzerland, and the UK. Eligible patients had proven clinical and biochemical endogenous hyperinsulinaemic hypoglycaemia and no evidence for metastatic disease on conventional imaging. CT/MRI imaging was done at referring centres according to standard protocols. At three tertiary nuclear medicine centres, we used whole body planar images and SPECT/CT of the abdomen up to 168 h after injection of (111)In-[Lys40(Ahx-DTPA-(111)In)NH2]-exendin-4 ((111)In-DTPA-exendin-4) to identify insulinomas. Consenting patients underwent surgery and imaging findings were confirmed histologically. FINDINGS Between Oct 1, 2008, and Dec 31, 2011, we recruited 30 patients. All patients underwent (111)In-DTPA-exendin-4 imaging, 25 patients underwent surgery (with histological analysis), and 27 patients were assessed with CT/MRI. (111)In-DTPA-exendin-4 SPECT/CT correctly detected 19 insulinomas and four additional positive lesions (two islet-cell hyperplasia and two uncharacterised lesions) resulting in a positive predictive value of 83% (95% CI 62-94). One true negative (islet-cell hyperplasia) and one false negative (malignant insulinoma) result was identified in separate patients by (111)In-DTPA-exendin-4 SPECT/CT. Seven patients (23%) were referred to surgery on the basis of (111)In-DTPA-exendin-4 imaging alone. For 23 assessable patients, (111)In-DTPA-exendin-4 SPECT/CT had a higher sensitivity (95% [95% CI 74-100]) than did CT/MRI (47% [27-68]; p=0.011). INTERPRETATION (111)In-DTPA-exendin-4 SPECT/CT could provide a good second-line imaging strategy for patients with negative results on initial imaging with CT/MRI. FUNDING Oncosuisse, the Swiss National Science Foundation, and UK Department of Health.
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Absolute quantification of left ventricular global and regional function at nuclear MPI using ultrafast CZT SPECT: initial validation versus cardiac MR.
Cochet, H, Bullier, E, Gerbaud, E, Durieux, M, Godbert, Y, Lederlin, M, Coste, P, Barat, JL, Laurent, F, Montaudon, M
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2013;(4):556-63
Abstract
UNLABELLED We sought to evaluate the accuracy of myocardial perfusion imaging (MPI) using cadmium-zinc-telluride (CZT) SPECT cameras for the measurement of left ventricular (LV) global and regional function, and the performance of absolute wall motion (WM) and wall thickness (WT) measurements for the detection of myocardial scarring, using cardiac MR as a reference. METHODS Sixty patients with known or suspected coronary artery disease underwent MPI using a CZT SPECT camera, as well as cine and delayed enhanced cardiac MR. Gated MPI data were processed using quantitative gated SPECT software. LV global function was assessed by measuring LV end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). Regional function was assessed by quantifying segmental WM and WT according to the 17-segment model. Myocardial scarring was quantified on each segment using delayed enhanced cardiac MR. Agreement between SPECT and cardiac MR was assessed using Pearson correlation and Bland-Altman analyses. The influence of measurement magnitude on the agreement was analyzed using Spearman correlation coefficients between the mean and SD of measurements. The performance of WM and WT for the detection of segments with more than 25% scar transmurality was assessed using receiver-operating-characteristic analysis. RESULTS Correlation between methods was excellent for EF (R = 0.81, P < 0.0001) and ESV (R = 0.88, P < 0.0001) and was good for EDV (R = 0.71, P < 0.0001). Agreement was good for EF (bias, -2.7%; limits of agreement, -15.5 to +10.1) but was lower for EDV (bias, -29.7 mL; limits of agreement, -68.3 to +8.9) and ESV (bias, -9.9 mL; limits of agreement, -30.7 to +10.9). Correlation between methods was fair for WM (R = 0.49, P < 0.0001) and WT (R = 0.48, P < 0.0001). SPECT underestimated WT (bias, -41%; limits of agreement, -108 to +26), with an error depending on thickening magnitude (ρ = 0.70, P < 0.0001). The agreement in WM measurement was higher (bias, -1.4 mm; limits of agreement, -6.9 to +4) and independent of motion magnitude (ρ = 0.006, P = 0.86). WM and WT were equally able to identify scarred segments (area under the receiver-operating-characteristic curve, 0.74 ± 0.03 and 0.74 ± 0.03, respectively). CONCLUSION MPI using CZT SPECT cameras and quantitative gated SPECT analysis accurately quantifies EF but still underestimates LV volumes. WM shows a higher agreement with cardiac MR than does WT, with errors in WT measurement increasing at greater thicknesses. Absolute quantification of segmental WM and WT can equally be used to identify myocardial scarring.
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Diagnostic imaging of higher brain dysfunction in patients with adult moyamoya disease using statistical imaging analysis for [123I]iomazenil single photon emission computed tomography.
Nakagawara, J, Osato, T, Kamiyama, K, Honjo, K, Sugio, H, Fumoto, K, Murahashi, T, Takada, H, Watanabe, T, Nakamura, H
Neurologia medico-chirurgica. 2012;(5):318-26
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Abstract
[123I]iomazenil (IMZ) is a specific radioligand for the central benzodiazepine (BZ) receptor that may be useful as a marker of cortical neuron loss after cerebral ischemia using single photon emission computed tomography (SPECT). This study used statistical imaging analysis for IMZ-SPECT to investigate the relationship between higher brain dysfunction and cortical neuron loss in the medial frontal lobes, to establish a confirmatory diagnosis of higher brain dysfunction in patients with adult moyamoya disease. IMZ-SPECT was estimated by three-dimensional stereotactic surface projections (3D-SSP). Cortical neuron loss was analyzed using the stereotactic extraction estimation (SEE) method (level 3: gyrus level) for 3D-SSP Z-score maps (Z-score >2). Extent of pixels with significant reduction of BZ receptor density within the target gyri (i.e. bilateral medial frontal gyri [MFGs] and anterior cingulate gyri [ACGs]) was calculated. In 6 patients with higher brain dysfunction, significant cortical neuron loss was observed in the bilateral MFGs in 4 patients, unilateral MFG in 1 patient, and bilateral ACGs in 2 patients. In 12 patients without higher brain dysfunction, no significant cortical neuron loss was observed in the bilateral MFGs or ACGs, and mild loss was observed in the bilateral MFGs in 2 patients, unilateral MFG in 4 patients, and unilateral ACG in 2 patients. Long-standing mild hemodynamic ischemia in the anterior circulation of patients with adult moyamoya disease could lead to incomplete brain infarction within the medial frontal lobes. Statistical imaging analysis using 3D-SSP and SEE methods for IMZ-SPECT could demonstrate significant cortical neuron loss in the bilateral frontal medial cortices involving MFG and/or ACG which correlate with higher brain dysfunction in patients with adult moyamoya disease.
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Nitrate administration increases blood flow in dysfunctional but viable myocardium, leading to improved assessment of myocardial viability: A PET study.
Slart, RH, Agool, A, van Veldhuisen, DJ, Dierckx, RA, Bax, JJ
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2006;(8):1307-11
Abstract
UNLABELLED SPECT with 99mTc-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasodilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. METHODS 13N-Ammonia PET was used to quantitatively assess blood flow, and 18F-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent 13N-ammonia PET at rest and after nitrate administration. RESULTS A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P < 0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. CONCLUSION 13N-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability.
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Baseline/postnitrate tetrofosmin SPECT for myocardial viability assessment in patients with postischemic severe left ventricular dysfunction: new evidence from MRI.
Giorgetti, A, Pingitore, A, Favilli, B, Kusch, A, Lombardi, M, Marzullo, P
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2005;(8):1285-93
Abstract
UNLABELLED The aim of this study was to compare (99m)Tc-tetrofosmin SPECT with contrast-enhanced MRI (ceMRI), a new direct sign of myocardial fibrosis. METHODS We studied 21 patients (age, 60 +/- 11 y; 19 male) with previous myocardial infarction and severe left ventricular dysfunction (ceMRI EF, 29% +/- 6%). All patients underwent resting and postnitrate (intravenous isosorbide dinitrate) (99m)Tc-tetrofosmin gated SPECT as well as ceMRI. Scintigraphic analysis was performed using quantitative perfusion SPECT (QPS), providing the percentage radiotracer uptake and defect severity in a 20-segment model. Hyperenhancement was defined by the increase of ceMRI signal intensity 20 min after intravenous injection of gadolinium-diethylenetriaminepentaacetic acid and its regional extension as the percentage of the total segment area. RESULTS In ceMRI dysfunctional segments, the correlation between the extent of hyperenhancement and both (99m)Tc-tetrofosmin uptake and defect severity was significantly better after nitrate administration rather than at rest (P < 0.0001). Using a ceMRI cutoff below 40%, 102 of 196 (52%) segments were viable, whereas 94 (48%) segments were not viable. According to receiver-operating characteristic curve analysis, diagnostic accuracies were higher for postnitrate (99m)Tc-tetrofosmin uptake as well as perfusion defect severity than using resting data (0.84 vs. 0.71, P < 0.001; 0.89 vs. 0.76, P < 0.001, respectively). CONCLUSION After nitrate administration, (99m)Tc-tetrofosmin uptake and perfusion defect severity were closely related to ceMRI, demonstrating, in vivo, the existence of an inverse correlation between the transmural distribution of fibrosis and tracer delivery to the myocardium.
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Prediction of functional improvement of ischemic myocardium with (123I-BMIPP SPECT and 99mTc-tetrofosmin SPECT imaging: a study of patients with large acute myocardial infarction and receiving revascularization therapy.
Seki, H, Toyama, T, Higuchi, K, Kasama, S, Ueda, T, Seki, R, Hatori, T, Endo, K, Kurabayashi, M
Circulation journal : official journal of the Japanese Circulation Society. 2005;(3):311-9
Abstract
BACKGROUND (18)F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) is assumed to be the most useful method of evaluating the viability of the myocardium, but its use is limited by the need for a cyclotron. In the present study, the ability of a combination of (99m)Tc-tetrofosmin (TF) and (123)I-beta-methyliodophenyl pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT), a combination of (18)F-FDG PET and (123)I-BMIPP SPECT, and a combination of (18)F-FDG PET and (99m)Tc-TF SPECT were compared to predict functional improvement of ischemic myocardium after a large acute myocardial infarction (AMI). METHODS AND RESULTS Ten patients with large AMI were studied by (99m)Tc-TF SPECT, (123)I-BMIPP SPECT and (18)F-FDG PET within 3 weeks. Six months later, (99m)Tc-TF imaging was performed. All patients underwent successful revascularization, and had no restenosis. Regional tracer uptake was scored using a 4-point scale in 20 segments of the SPECT and PET images. When the defect score of (123)I-BMIPP SPECT exceeded the defect score of (99m)Tc-TF SPECT or (18)F-FDG PET by 1 point or more, and when the defect score of (99m)Tc-TF SPECT exceeded the defect score of (18)F-FDG PET by 1 point or more, the segment was considered to show mismatching. When the defect score was the same in 2 tracers, the segment was considered to show matching. (99m)Tc-TF imaging at 3 weeks and 6 months used quantitative gated SPECT (QGS) to score wall motion using a 6-point scale (-1= dyskinesis, 0= akinesis, 1= severe hypokinesis, 2= moderate hypokinesis, 3= mild hypokinesis, and 4= normokinesis). The sensitivity of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 61%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 94%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 76%. The specificity of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 83%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 40%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 49%. The accuracy of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 70%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 71%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 63%. CONCLUSION The combination of (123)I-BMIPP and (99m)Tc-TF imaging is a practical modality for predicting the functional improvement of ischemic myocardium after a large AMI.
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Tomographic imaging in the diagnosis of pulmonary embolism: a comparison between V/Q lung scintigraphy in SPECT technique and multislice spiral CT.
Reinartz, P, Wildberger, JE, Schaefer, W, Nowak, B, Mahnken, AH, Buell, U
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2004;(9):1501-8
Abstract
UNLABELLED Although ventilation/perfusion (V/Q) lung scintigraphy is a well-accepted and frequently performed procedure in the diagnosis of pulmonary embolism, there is growing controversy about its relevance, particularly due to the increasing competition between scintigraphy and CT. Even though comparative studies between both modalities have already been performed, their results were highly inconsistent. Remarkably, in most of those studies, conventional planar perfusion scans were compared with tomographic images acquired using state-of-the-art CT scanners-a study design that cannot give impartial results. Hence, the aim of our study was a balanced comparison between V/Q lung scintigraphy and CT angiography using advanced imaging techniques for both modalities. METHODS A total of 83 patients with suspected pulmonary embolism were examined using V/Q lung scintigraphy in SPECT technique as well as 4-slice spiral CT. Ventilation scans were done using an ultrafine aerosol. Additionally, planar images in 8 views were extracted from the V/Q SPECT datasets. Two experienced referees assessed each of the 3 modalities. The final diagnosis was made at a consensus meeting while taking into account all of the imaging modalities, laboratory tests, clinical data, and evaluation of a follow-up period. RESULTS In the course of the consensus conference, pulmonary embolism was diagnosed in 37 of the 83 patients (44.6%). Compared with planar scintigraphy, SPECT raised the number of detectable defects at the segmental level by 12.8% (+11 defects; P = 0.401) and at the subsegmental level by 82.6% (+57 defects; P < 0.01). The sensitivity/specificity/accuracy of planar V/Q scintigraphy and V/Q SPECT was 0.76/0.85/0.81 and 0.97/0.91/0.94, respectively, compared with 0.86/0.98/0.93 for multislice CT. CONCLUSION SPECT and ultrafine aerosols are technical advancements that can substantially improve lung scintigraphy. Using advanced imaging techniques, V/Q scintigraphy and multislice spiral CT both yield an excellent and, in all aspects, comparable diagnostic accuracy, with CT leading in specificity while SPECT shows a superior sensitivity. Even though planar lung scintigraphy yields satisfactory results for a nontomographic modality, it does not compare with tomographic imaging.
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Noninvasive measurement of gastric accommodation by means of pertechnetate SPECT: limiting radiation dose without losing image quality.
Bennink, RJ, van den Elzen, BD, Kuiken, SD, Boeckxstaens, GE
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2004;(1):147-52
Abstract
UNLABELLED The gastric accommodation response to a meal is impaired in conditions such as functional dyspepsia. At present, a barostat study is the gold standard to assess fundic relaxation in response to a meal. However, this method is invasive and possibly induces artifacts as a result of positive intraluminal balloon pressure. A noninvasive scintigraphic test has been developed to measure gastric accommodation in humans. The aim of this study was to refine this method, increasing the imaging time span and limiting the radiation dose applied without losing image quality, so that repeated measurements within 1 subject are possible without increasing radiation risk. METHODS Thirteen healthy volunteers without gastrointestinal symptoms were recruited from a student population. Each volunteer had previously undergone a barostat study. After an overnight fast, volunteers were scanned twice on separate days after intravenous injection of 200 MBq (99m)Tc-pertechnetate. On 1 occasion, volunteers were pretreated with a proton pump inhibitor. Thirty minutes after injection, sequential, 7-min SPECT scans (72 views, 10 s/view, 128 matrix) were acquired on a dual-head gamma-camera system before and up to 2 h after ingestion of a test meal. After reconstruction (filtered backprojection, ramp-Butterworth filter; order, 10; cutoff, 0.45 Nyquist), fundus volume was calculated semiautomatically by means of a threshold voxel volume tool. RESULTS Limiting injection dose from 370-740 MBq to 200 MBq (99m)Tc-pertechnetate resulted in good-quality images, with high target-to-background ratio up to 150 min after injection. This represents a significant dose reduction, from 4.6-9.3 to 2.5 mSv. There was no significant difference between SPECT fundic volumes or accommodation response with or without proton pump inhibitor pretreatment. Volume kinetics were similar to those with barostat studies, but gastric volumes were inferior. CONCLUSION Refining the methodology yields an improved noninvasive test for the assessment of gastric accommodation without unnecessarily increasing radiation burden. This technique enables repeated and serial measurement of gastric accommodation to a test meal, a process that is potentially useful for characterization and follow-up of dyspeptic patients with and without drug intervention.
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Myocardial scintigraphy using a fatty acid analogue detects coronary artery disease in hemodialysis patients.
Nishimura, M, Hashimoto, T, Kobayashi, H, Fukuda, T, Okino, K, Yamamoto, N, Fujita, H, Inoue Tsunehiko Nishimura, N, Ono, T
Kidney international. 2004;(2):811-9
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Abstract
BACKGROUND Coronary artery disease contributes significantly to mortality in end-stage renal disease (ESRD) patients. Single-photon emission computed tomography (SPECT) using an iodinated fatty acid analogue, iodine-123-methyl iodophenylpentadecanoic acid (123I-BMIPP), can assess fatty acid metabolism in the myocardium. We investigated the ability of 123I-BMIPP SPECT to detect coronary artery disease in hemodialysis patients compared with 201thallium chloride (201Tl) SPECT. METHODS We prospectively studied 130 ESRD patients undergoing hemodialysis for a mean of 88.6 months (male/female, 77/53; mean age, 63.8 years). Dual SPECT using 123I-BMIPP and 201Tl was performed, followed by coronary angiography. SPECT findings were graded in 17 segments on a five-point scale (0, normal uptake; 4, none) and assessed as a summed score. RESULTS By coronary angiography, 71.5% of patients (93/130) had significant coronary stenosis (> or =75%), and five patients showed coronary spasm without coronary stenosis. When a BMIPP summed score of 6 or more was defined as abnormal, sensitivity, specificity, and accuracy for detecting coronary artery disease by BMIPP SPECT were 98.0%, 65.6%, and 90.0%, respectively; in contrast, these parameters for detecting coronary artery disease by Tl SPECT were 84.7%, 46.9%, and 75.0%, respectively, when a Tl summed score of 1 or more was defined as abnormal. In receiver operating characteristic analysis, the area under the curve was 0.895 in BMIPP and 0.727 in Tl SPECT, respectively. CONCLUSION Resting BMIPP SPECT is superior to Tl SPECT for detecting coronary lesions, and provides safe screening for coronary artery disease among maintenance hemodialysis patients.