Hadi Malek

Tehran University of Medical Sciences, Teheran, Tehrān, Iran

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Publications (8)6.46 Total impact

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    ABSTRACT: Recently, the phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has become feasible via several software packages for the evaluation of left ventricular mechanical dyssynchrony. We compared two quantitative software packages, quantitative gated SPECT (QGS) and Emory cardiac toolbox (ECTb), with tissue Doppler imaging (TDI) as the conventional method for the evaluation of left ventricular mechanical dyssynchrony.
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology. 07/2014;
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    ABSTRACT: The effectiveness of metoclopramide in reducing gastrointestinal-induced artifacts in myocardial perfusion imaging (MPI) is a subject of debate. We examined the significance of this pharmacological intervention in the quality of images obtained from MPI studies. A total of 211 suspected or known cases with coronary artery disease routinely referred to our nuclear medicine department for MPI were randomly assigned to group A and group B. Group A (N=125) comprised patients who received 10 mg of metoclopramide orally after the injection of the radiotracer [technetium-99m-labeled methoxyisobutyl isonitril (99mTc-MIBI)] 1 h before image acquisition, and group B (N=86) comprised patients who did not receive any pharmacological intervention and were considered the control group. All the scans in each group were assessed in the rest phase of a routine 2-day protocol. The single-photon emission computerized tomography (SPECT) images were visually evaluated in terms of extracardiac activities and their effects on image quality by three nuclear medicine physicians, who were blinded to the details of the protocol. Of the 125 patients who had received metoclopramide, 16 (13%) had nonacceptable, 72 (57.6%) had acceptable (interpretable), and 37 (29.6%) had good image quality. The image quality in group B was nonacceptable in 10 (11.23%), acceptable in 48 (50.23%), and good in 28 (33.56%) patients. The overall interobserver agreement was good (κ: 0.6-0.9, P<0.05) among the three readers. There was no statistically significant difference in terms of MPI-SPECT image quality between patients who received metoclopramide and those in the control group. Metoclopramide, therefore, did not exert a remarkable effect on the quality of our MPI scans.
    Nuclear Medicine Communications 07/2012; 33(10):1053-7. · 1.38 Impact Factor
  • Journal of Nuclear Cardiology 03/2012; 19(3):618-20. · 2.85 Impact Factor
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    ABSTRACT: Gated myocardial perfusion single-photon emission computed tomography (GSPECT) has been established as an accurate and reproducible diagnostic and prognostic technique for the assessment of myocardial perfusion and function. Respiratory motion is among the major factors that may affect the quality of myocardial perfusion imaging (MPI) and consequently the accuracy of the examination. In this study, we have proposed a new approach for the tracking of respiratory motion and the correction of unwanted respiratory motion by the use of respiratory-cardiac gated-SPECT (RC-GSPECT). In addition, we have evaluated the use of RC-GSPECT for quantitative and visual assessment of myocardial perfusion and function. Twenty-six patients with known or suspected coronary artery disease (CAD)-underwent two-day stress and rest (99m)Tc-Tetrofosmin myocardial scintigraphy using both conventional GSPECT and RC-GSPECT methods. The respiratory signals were induced by use of a CT real-time position management (RPM) respiratory gating interface. A PIO-D144 card, which is transistor-transistor logic (TTL) compatible, was used as the input interface for simultaneous detection of both ECG and respiration signals. A total of 26 patients with known or suspected CAD were examined in this study. Stress and rest myocardial respiratory motion in the vertical direction was 8.8-16.6 mm (mean, 12.4 +/- 2.9 mm) and 7.8-11.8 mm (mean, 9.5 +/- 1.6 mm), respectively. The percentages of tracer intensity in the inferior, inferoseptal and septal walls as well as the inferior to lateral (I/L) uptake ratio was significantly higher with the use of RC-GSPECT as compared to the use of GSPECT (p < 0.01). In a left ventricular ejection fraction (LVEF) correlation analysis between the use of rest GSPECT and RC-GSPECT with echocardiography, better correlation was noted between RC-GSPECT and echocardiography as compared with the use of GSPECT (y = 0.9654x + 1.6514; r = 0.93, p < 0.001 versus y = 0.8046x + 5.1704; r = 0.89, p < 0.001). Nineteen (19/26) patients (73.1%) showed abnormal myocardial perfusion scans with reversible regional myocardial defects; of the 19 patients, 14 (14/26) patients underwent coronary angiography. Respiratory induced motion can be successfully corrected simultaneously with the use of ECG-gated SPECT in MPI studies using this proposed technique. Moreover, the use of ECG-gated SPECT improved image quality, especially in the inferior and septal regions that are mostly affected by diaphragmatic attenuation. However, the effect of respiratory correction depends mainly on the patient respiratory pattern and may be clinically relevant in certain cases.
    Korean Journal of Radiology 01/2008; 9(6):490-7. · 1.56 Impact Factor
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    ABSTRACT: Myocardial SPET has emerged as an important noninvasive diagnostic and prognostic method for assessment of patients with suspected CAD. Respiratory motion is a potential cause of motion artefact and reduced image quality in ECG-gated SPET (GSPET). In this investigation, we studied the effects of respiratory motion on GSPET concerning regional myocardial perfusion and function by simulation study. The NCAT phantom allowed simulation of respiratory motion with different amplitude for diaphragm (0 to 7 cm with increment of 1 cm) and anterior-posterior extension (from 0 to 1.7 cm). SimSET was used to generate simulated projection data. Emission data were generated over one respiratory cycle, divided into 80 phases. Data were reconstructed using the ordered subsets exceptional maximization (OSEM) method without attenuation and scatter correction. Quantitative analysis of regional myocardial perfusion and function were performed by Emory cardiac toolbox software.
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    ABSTRACT: Introduction-Left ventricular ejection fraction (LVEF) is an important clinical index in diagnosis and treatment of myocardial diseases. There are three major methods for measurement of LVEF: echocardiography, angiography and ECG-gated SPECT. The first method is economical, safe and rapid. The second one is more accurate, however invasive and the third one lies somewhere in between. Multi-gated SPECT usually suffers from low reproducibility compared to other methods. This is due to variation in processing factors, mainly reconstruction methods and filtration. Up to now, there is no standard method of processing of cardiac SPECT. Methods-In this study, we attempted to find the optimum processing protocol in which the results are consistent with the angiographic results. Forty patients (referred to our department for myocardial perfusion SPECT) who had angiography within 2 weeks of the test were included in the study. All the patients had a positive history of myocardial infarction. All imaging performed with a single head GE gamma camera SPECT system model DSX using 99m Tc-MIBI. Two commonly used reconstruction methods i.e., filtered back projection and ordered subset expectation maximization with different parameters were used and the results compared with that of echocardiography and angiography. Results-In filtered back projection technique, maximum correlation between ECG-Gated SPECT and angiography (r = 0.775) was observed when using Metz filter with psf FWHM=5 and order=5. In OSEM reconstruction technique, the maximum correlation (r = 0.706) between ECG-Gated SPECT and angiography was found using iteration of 2 and subset of 12. Discussion-Angiography is usually assumed the standard method for calculation of LVEF. However, techniques such as ECG-gated SPECT can be equally accurate if the method of processing is selected optimally. We optimized the method of processing in our department in correlation with the results of angiography (Iranian Heart Journal 2007; 8 (3): 6-15).
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    ABSTRACT: Background-To assess the value of 24-hour redistribution imaging after 201 Tl reinjection for the detection of myocardial viability, we compared the results of 201 Tl reinjection imaging with those obtained 24 hours after reinjection. Methods-In total, 35 patients aged 57±8 years (mean ± SD) who showed one or more persistent perfusion defects on stress reinjection images after myocardial infarction were assessed for myocardial viability. After pharmacological stress and 4-hour reinjection imaging, 25 patients who showed non-viable segments at reinjection image underwent 24-hour redistribution imaging. The stress, reinjection, and 24-hour redistribution images were analyzed quantitatively. Criteria for viability definition were:1) segments which showed at least 50% uptake of peak activity of normal regions at stress phase and 2) segments with less than 50% uptake at stress image which showed at least 20% redistribution at the later phases. Results-Of the 102 abnormal myocardial regions on the stress images, 19 segments at reinjection images and another 17 segments at 24-hour redistribution images demonstrated redistribution. On the other hand, 24-hour imaging showed viability in 17 out of 83 segments (20.4%), which were considered non-viable regions at reinjection image, occurring in 8 out of 25 patients. Conclusion: In stress reinjection protocol by 201 Tl, 24-hour redistribution imaging is proposed to be performed in patients who show significant non-viable myocardial tissue at 4-hour reinjection imaging for a better recognition of viable myocardium (Iranian Heart Journal 2009; 10 (1):16-20).
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    ABSTRACT: Different techniques have been introduced for full automatic processing of myocardial perfusion imaging with single-photon emission tomography. We tried to evaluate the accuracy of one of these commercial automatic processing methods. The study was performed in 300 patients during 18 months. Two post-stress acquisitions in supine and prone positions and one acquisition at rest , were performed for every patient. All images were processed both automatically and interactively and the results were compared to each other. The automatic method matched the interactive method in 95.22% for left ventricle isolation, in 99.54% for excluding extra-cardiac activity and in 98.22% for reorientation of a single projected data. The automatic method was also successful in complete processing of 81.33% sets of stress (supine)-rest and 79.77% sets of stress (prone)-rest images as compared to the interactive method. In conclusion, the fully automated processing method matches the interactive method in complete processing of myocardial perfusion imaging with single-photon emission tomography more than 79.77% and is of equal accuracy to the interactive method in supine and prone-positioned acquisitions.
    Hellenic journal of nuclear medicine 12(1):10-2. · 0.68 Impact Factor