[Show abstract][Hide abstract] ABSTRACT: The use of ionizing radiation has led to advances in medical diagnosis and treatment.
The purpose of this study was to determine the risk of radiation cataractogenesis in the interventionists and staff performing various procedures in different interventional laboratories.
This cohort study included 81 interventional cardiology staff. According to the working site, they were classified into 5 groups. The control group comprised 14 professional nurses who did not work in the interventional sites. Participants were assigned for lens assessment by two independent trained ophthalmologists blinded to the study.
The electrophysiology laboratory staff received higher doses of ionizing radiation (17.2 ± 11.9 mSv; P < 0.001). There was a significant positive correlation between the years of working experience and effective dose in the lens (P < 0.001). In general, our findings showed that the incidence of lens opacity was 79% (95% CI, 69.9-88.1) in participants with exposure (the case group) and our findings showed that the incidence of lenses opacity was 7.1% (95% CI:2.3-22.6) with the relative risk (RR) of 11.06 (P < 0.001).
We believe that the risk of radiation-induced cataract in cardiology interventionists and staff depends on their work site. As the radiation dose increases, the prevalence of posterior eye changes increases.
[Show abstract][Hide abstract] ABSTRACT: Respiratory-related cardiac motion could have considerable effects on myocardial perfusion imaging, leading to misinterpretation of the images. In this study, we examined the influence of respiratory correction on ECG-gated myocardial perfusion SPECT (RC-GSPECT) concerning regional myocardial perfusion and function.
Using the NCAT phantom, a typical torso phantom was generated. SimSET, a Monte Carlo simulator, was used to image the photon emerging from the phantom. Twenty-six patients underwent a 2-day stress-rest ECG-gated myocardial perfusion SPECT (GSPECT) imaging. A separate study was also performed by simultaneous respiratory and cardiac triggering with the real-time position management (RPM) for respiratory correction (RC).
In simulation study, count density in the inferior and inferoseptal walls increased in the lower bin of the respiratory cycle. On the other hand, there was a higher correlation between RC-GSPECT and echocardiography for left ventricular ejection fraction (LVEF) (r = 0.95, P < .01 vs r = 0.88, P < .01 for GSPECT).
We proposed a new approach for respiratory and cardiac-gated SPECT to eliminate respiratory motion artifacts. RC-GSPECT is a feasible method in MPI studies and may play an important role to improve the quality of MPI images, particularly in the inferior wall.
Journal of Nuclear Cardiology 12/2014; DOI:10.1007/s12350-014-0031-1 · 2.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
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.
Methods and Results
Thirty-one patients with severe heart failure (ejection fraction ≤35%) and regular heart rhythm, who referred for gated-SPECT MPI, were enrolled. TDI was performed within 3 days after MPI. Dyssynchrony parameters derived from gated-SPECT MPI were analyzed by QGS and ECTb and were compared with the Yu index and septal-lateral wall delay measured by TDI. QGS and ECTb showed a good correlation for assessment of phase histogram bandwidth (PHB) and phase standard deviation (PSD) (r = 0.664 and r = 0.731, P < .001, respectively). However, the mean value of PHB and PSD by ECTb was significantly higher than that of QGS. No significant correlation was found between ECTb and QGS and the Yu index. Nevertheless, PHB, PSD, and entropy derived from QGS revealed a significant (r = 0.424, r = 0.478, r = 0.543, respectively; P < .02) correlation with septal-lateral wall delay.
Despite a good correlation between QGS and ECTb software packages, different normal cut-off values of PSD and PHB should be defined for each software package. There was only a modest correlation between phase analysis of gated-SPECT MPI and TDI data, especially in the population of heart failure patients with both narrow and wide QRS complex.
[Show abstract][Hide abstract] 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. DOI:10.1097/MNM.0b013e3283570feb · 1.37 Impact Factor
[Show abstract][Hide abstract] 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.
Korean Journal of Radiology 12/2008; 9(6):490-7. DOI:10.3348/kjr.2008.9.6.490 · 1.81 Impact Factor
[Show abstract][Hide abstract] 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).
[Show abstract][Hide abstract] 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. · 0.93 Impact Factor
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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).