OXIDATIVE DEGRADATION OF 2-CHLOROPHENOL BY PERSULFATE

The degradation of 2-chlorophenol (2-CP) by persulfate was investigated. The kinetics of persulfate oxidation of 2-chlorophenol in aqueous solutions at various pH, oxidant concentration, temperature, Fe2+ and Cu2+ ions content was studied. Maximum of 2-CP degradation occurred at pH 8. The oxidation rate of 2-CP increased with increasing the persulfate molar excess. The degradation process was significantly influenced by temperature – the higher temperature results in a faster degradation of 2-CP. The activation of persulfate by ferrous and copper ions was also studied. Results showed that persulfate is activated more effectively by iron(II) than copper(II) ions. A comparison of different persulfate activation methods revealed that heat-activation was the most effective. Under optimal conditions, in the presence of ferrous ions at 50 °C, complete degradation of 2-chlorophenol was achieved after about 30 minutes

The effect of image translation table on diagnostic efficacy of myocardial perfusion SPECT studies

BACKGROUND: The aim of this study was to determine which of the most popular colour scales used in the Xeleris processing system (GE) should preferably be used during a clinical interpretation of myocardial perfusion images, and to find out whether a colour scale saturation level affects the diagnostic efficacy of the study. MATERIAL AND METHODS: From among 100 patients in whom a myocardial perfusion scintigraphy had been performed, a subgroup of people referred for coronary angiography, with neither prior history nor ECG signs of a myocardial infarction has been selected retrospectively. This group consisted of 41 patients (14 females) in the age group 46 to 76 years. All patients underwent two-day myocardial perfusion SPECT imaging using 99mTc-MIBI as a radiopharmaceutical. Reconstructed slices were interpreted in 3 colour scales: white-red-yellow-green-blue-black with computer-assigned thresholds (French 100%), the same French scale but without a white colour (image maximum set manually to a border value between red and white &#8212; French w.w.), and a white-yellow-violet- pink-blue-black scale (GEcolor), by consensus of two experienced nuclear medicine specialists. A semiquantitative method for evaluation of perfusion images was applied, based on myocardium segmentation. Perfusion in each segment was scored using a five-point system. Study interpretation (normal/ abnormal perfusion) was based on summed stress scores (SSS), being equal/above or below a given threshold value. The choice of optimal SSS threshold value was based on sensitivity and specificity of the study in detection of perfusion defects resulting from critical stenoses of main coronary arteries RESULTS: SSS values differed among colour scales (p < 0.00001). The lowest values were obtained for a French 100% scale (mean value = 5.0, SD = 8.0), the highest for French w.w. (mean values = 8.1, SD = 8.7), and for GE colour scale &#8212; mean value &#8212; 5.6, SD &#8212; 7.9. A French 100% scale gave high sensitivity (88%), as well as specificity (83%), but only when a low SSS threshold value of 2, hardly acceptable for study interpreters, was used. When higher threshold values were applied, they compromised the sensitivity of the study. A French w.w. scale with SSS threshold values lower than 3 provided a slightly higher sensitivity (94%), but with a significant reduction in specificity (to values below 50%). Only a threshold value of 4 provided acceptable, but still low specificity (63%) with preserved high sensitivity (88%). At the same time, the scale GE colour provided indices of diagnostic efficacy with the SSS threshold value of 3 as high as a scale French 100% with threshold value of 2. CONCLUSIONS: A French scale (Xeleris, GE) is not the scale of choice for the interpretation of myocardial perfusion SPECT images. It seems that a GE colour scale is better suited for this purpose. SSS threshold values accepted as diagnostic criteria for the detection of myocardial perfusion abnormalities should be suited separately for every translation table. The choice of optimal value should be verified by results of coronary angiography. Nuclear Med Rev 2010; 13, 2: 64&#8211;6

Application of stress-only myocardial perfusion imaging

BACKGROUND: Single-photon emission computed tomography myocardial perfusion study is usually a sequence of stress and rest part. In case of a normal stress study rest part can be given up. The objective of this study was to examine factors affecting concordance of results of stress-only (SO) and stress-rest (SR) studies. MATERIAL AND METHODS: SO and SR studies without and with attenuation correction (AC) of 212 selected patients (without cardiomyopathy, history of myocardial infarction or coronary artery bypass grafting) were analyzed visually. Influence of percutaneous coronary intervention (PCI) in the past, type of stress (physical/pharmacological) and application of AC (in form of combined method of non-corrected and corrected images — CM), patient body mass index (BMI) and gender on concordance rates of SO and SR studies were examined. RESULTS: Neither a history of PCI, nor a type of stress affected concordance rate. AC (in form of CM) improved concordance rate significantly, from 60% to 68% (p = 0.018). Patient BMI affected concordance rates — 72% in non-obese and 59% in obese patients (p = 0.05). In the whole group, risk of overlooking patients with abnormal perfusion in SO study was small (&lt; 2%), but it grew significantly with patient BMI. Rest study was necessary in about 20% of non-obese and in about 50% of obese patients. CONCLUSION: MPS can be limited to stress part in appropriately selected, especially non-obese, patients provided that AC is applied, due to a low risk of overlooking patients with abnormal perfusion. In case of obese patients, careful analysis of exercise images for their normality is particularly important

Comparison of shortened gated myocardial perfusion imaging processed with „Myovation Evolution” with full time study

Background: The work compares results of shortened gated myocardial perfusion imaging (MPI), processed with „Myovation Evolution” software, with a study performed in a standard way.Material and methods: A retrospective study was conducted in a group of 95 patients (56 males and 39 females, age 62±9 years, BMI 28±4) with known or suspected CAD, without clinical history or any signs of a previous myocardial infarction. All patients underwent coronary angiography (CA) within 3 months of MPI. CA was used as a reference for diagnostic performance of MPI. Patients underwent a stress/rest 2-day MPI. Both studies were performed twice, with normal (25s) and shortened (13s) time per projection. Studies were processed using Myovation protocol (OSEM with 2 iterations and 10 subsets) for full time (FT) studies and a Myovation Evolution protocol dedicated to half time (HT) studies (OSEM with 12 iterations, 10 subsets). Reconstructed images, with and without attenuation correction (AC), were evaluated by 2 experienced nuclear medicine specialists (a consensus), with regard to image quality and perfusion, evaluated using a visual semi-quantitative method, applying a standard division of myocardium into 17 segments. Perfusion was assessed in every segment using a standard 5 grade scale. Summed stress scores were calculated for every patient and threshold values for detection of CAD were selected based on ROC analysis with CA treated as a reference method. After at least 2 months FT images were interpreted again by the same specialists.Results: Quality of images obtained from shortened and normal studies was equally good. All correlation coefficients between segmental scorings of FT and HT studies were high and statistically significant. Correlation coefficients between corresponding segments in FTAC and HTAC (i.e. with AC) studies were systematically higher than without AC. Agreement between FT and HT study results was equal to 81% for FT and HT studies and to 86% for FTAC and HTAC studies (p=0.40). Repeatability of FTAC study assessments was equal to 94%. 95-per cent confidence intervals calculated for agreement between FTAC and HTAC studies and repeatability of FTAC study overlapped considerably. Correlation coefficients for EDV, ESV and EF values between FT and HT were high: 0.93, 0.96 and 0.88, respectively. Conclusion: Myovation Evolution protocol used for reconstruction of myocardial perfusion studies with reduced number of counts requires AC. Disagreements observed during visual assessment of normal and reduced count studies are statistically not significantly larger than between dual assessment of a full count study.BACKGROUND: The work compares the results of shortened gated myocardial perfusion imaging (MPI), processed with „Myovation Evolution” software, with a study performed in a standard way. MATERIAL AND METHODS: A retrospective study was conducted in a group of 95 patients (56 males and 39 females, age 62 ± 9 years, BMI 28 ± 4) with known or suspected CAD, without clinical history or any signs of a previous myocardial infarction. All patients underwent coronary angiography (CA) within 3 months of MPI. CA was used as a reference for diagnostic performance of MPI. Patients underwent a stress/rest 2-day MPI. Both studies were performed twice, with normal (25s) and shortened (13s) time per projection. Studies were processed using Myovation protocol (OSEM with 2 iterations and 10 subsets) for full time (FT) studies and a Myovation Evolution protocol dedicated to half time (HT) studies (OSEM with 12 iterations, 10 subsets). Reconstructed images, with and without attenuation correction (AC), were evaluated by 2 experienced nuclear medicine specialists (a consensus), with regard to image quality and perfusion, evaluated using a visual semi-quantitative method, applying a standard division of myocardium into 17 segments. Perfusion was assessed in every segment using a standard 5 grade scale. Summed stress scores were calculated for every patient and threshold values for detection of CAD were selected based on ROC analysis with CA treated as a reference method. After 2 months FT images were interpreted again by the same specialists. RESULTS: The quality of images obtained from shortened and normal studies was equally good. All correlation coefficients between segmental scorings of FT and HT studies were high and statistically significant. Correlation coefficients between corresponding segments in FTAC and HTAC (i.e. with AC) studies were systematically higher than without AC. The agreement between FT and HT study results was equal to 81% for FT and HT studies and to 86% for FTAC and HTAC studies (p = 0.40). The repeatability of FTAC study assessments was equal to 94%. 95-percent confidence intervals calculated for agreement between FTAC and HTAC studies and the repeatability of FTAC study overlapped considerably. Correlation coefficients for EDV, ESV and EF values between FT and HT were high: 0.93, 0.96 and 0.88, respectively. CONCLUSION: Myovation Evolution protocol used for reconstruction of myocardial perfusion studies with reduced number of counts requires AC. The agreement between the results of visual assessment of normal and reduced count studies is high and not worse than the agreement between repeat assessment of a full time study

Reduced-time myocardial perfusion study processed with “Myovation Evolution” — assessment of diagnostic efficacy

BACKGROUND: While assessing images using standard segmental method, we felt that some defects were either underscored or missed. So this work is intended to compare results of low count myocardial perfusion studies (MPS) processed with „Myovation Evolution”, applying complete evaluation of all available slices, with full count studies and assess impact of reduction of counts on diagnostic efficacy of the study. MATERIAL AND METHODS: A retrospective study was conducted in a group of 95 patients (56 males, age 62 ± 9 years, BMI 28 ± 4) with known or suspected CAD, without clinical history or any signs of a previous myocardial infarction. All patients underwent coronary angiography (CA) within 3 months of MPS. CA was used as a reference method for diagnostic performance of MPS. Patients underwent a stress/rest 2-day MPS. Both studies were performed twice, with normal (25 s) and shortened (13 s) time/projection. Studies were processed using Myovation protocol (OSEM, 2 iterations, 10 subsets) for full time (FT) studies and a Myovation Evolution protocol for half time (HT) studies (OSEM, 12 iterations, 10 subsets, Resolution Recovery). Reconstructed images, with and without attenuation correction (AC), were evaluated by 2 experienced nuclear medicine specialists (a consensus) visually, taking into account all available slices, in a 5-grade scale (normal, probably normal, equivocal, probably abnormal and abnormal). Study results were additionally dichotomized as normal or abnormal. Perfusion defects were assigned to coronary arteries. RESULTS: An exact agreement between FT and HT study assessment, without AC, amounted to 66%, with AC it grew to 79%, p = 0.05. In studies without AC 10 perfusion defects were found only in HT studies in RCA area in male patients. A higher percentage of studies with perfusion defects in RCA area visible only in HT studies was found among discordant (7/25, 28%) than concordant results (3/70, 4%), p = 0.003. AC reduced this difference. HT study provided lower accuracy in detection of CAD than FT study (58% vs. 68%, p = 0.034). AC reduced this difference considerably. Dichotomized assessment agreed in 81% of studies without AC and in 87% with AC. CONCLUSIONS: Myovation Evolution protocol requires application of AC otherwise perfusion defects in RCA area in male patients are falsely detected. Shortened studies reconstructed with „Myovation Evolution” package without AC reveal a tendency toward reduction of accuracy of the study in detection of CAD. AC makes up for this reduction

Application of normalized values of kidney clearance function in the diagnosis of bilateral obstructive nephropathy — a preliminary report

BACKGROUND: Dynamic renal scintigraphy provides effective diagnosis of obstructive uropathy and nephropathy. However, in case of a bilateral outflow impairment, relative differential renal function (DRF), which is a primary quantitative criterion for diagnosis of unilateral obstructive nephropathy (when its value is below 45%, according to EANM guidelines from 2011), becomes unreliable. In case of bilateral nephropathy with similar severity, this parameter may even be within the normal range (45–55%) for both kidneys. The aim of this study was therefore to assess diagnostic usefulness of the original, normalized, absolute parameter proportional to the value of renal clearance function (K) in the evaluation of obstructive nephropathy in a group of patients with bilateral uropathy. MATERIAL AND METHODS: 16 healthy volunteers (32 kidneys) without history of kidney diseases were examined to determine normative value of K index. Then, 8 patients (16 kidneys) with bilateral obstructive uropathy found in standard dynamic renal scintigraphy performed using 111 MBq of 99mTc-EC (cumulative renographic curve that continued rising or dropped by less than 50% after i.v. administration of Furosemide) were examined. For each of the subjects 60 sequential 20s images were obtained, which were then assessed using an original method of post-processing scintigraphic data. It included normalization of renographic curves to the area under the heart curve. Subsequently, these normalized values from the uptake phase (between 2nd and 3rd minute) were inserted into the linear regression equation, from which K index was obtained. RESULTS: In healthy volunteers the average value of K index was 0.23 ± 0.05. The value of 0.13 (mean –2 SD) was taken as the lower limit of the norm. Values below that limit suggest obstructive nephropathy. In patients with bilateral obstructive uropathy, 5 kidneys met the conventional criteria of nephropathy (DRF &lt; 45%), while 11 kidneys had DRF within normal range. K index was below the norm in 9 kidneys (including 4 kidneys with low and 5 with normal DRF), while its value was normal in 7, including one kidney with reduced DRF (37%). K index changed the diagnosis in 6 kidneys out of 16 (38%). CONCLUSIONS: Preliminary results indicate usefulness of K index in diagnosis of obstructive nephropathy in patients with bilateral obstructive uropathy. For further evaluation of clinical value of this method, it is planned to examine a larger group of patients with varying degrees of renal parenchymal function impairments

Effect of CT misalignment on attenuation — corrected myocardial perfusion SPECT

BACKGROUND: Use of CT based attenuation correction (AC) for myocardial perfusion SPECT (MPS) is growing fast due to a rapid development of hybrid SPECT/CT systems. SPECT and CT studies are performed in a sequential way extending total study acquisition and making a patient movement more likely. The present work aims at answering the question how large misalignment between SPECT and CT studies should be considered significant and how often those misregistrations are observed. MATERIAL AND METHODS: A retrospective study applying AC was performed in 107 patients who had coronary angiography (CA) performed within 3 months. Patients underwent a stress/rest Tc-99m MIBI 2 day SPECT/CT myocardial perfusion study. In case of SPECT and CT misalignment CT slices were shifted manually; shifts along 3 axes were recorded and after realignment a repeat reconstruction was performed. Euclidean distance of misalignment was also calculated. Images were analyzed by two experienced nuclear medicine specialists (consensus) applying visual semiquantitative method. Perfusion of three arteries was scored using a 5 grade scale. CA results were used as a reference for MPS findings. RESULTS: In 47 patients (44%) CT realignment was necessary. CT was shifted mostly along x and y axes, and less often along z axis. Euclidean distance S exceeded 2 pixels in 3 stress and 2 rest studies. Only in 7 patients changes of scores assigned to coronary vessels were noted as a result of CT realignment. These changes concerned 9 vessel areas. In 7 out of 9 cases changes were noted toward a better agreement with results of CA. Only in one patient, with stress S &gt; 3 pixels and negative result of CA, CT realignment changed vessel area score significantly, from probably abnormal to normal. CONCLUSIONS: Only misalignments large enough, exceeding 2–3 pixels, have negative impact on attenuation corrected images. Such misalignments are rare, in our material were observed in 3 stress and 2 rest studies (3% and 2% of all studies, respectively). Only in one patient (below 1% of all studied patients) CT misalignment caused a significant study misinterpretation. Although alignment of SPECT and CT studies should be checked in every patient, small misalignments do not affect study interpretation

Electropolymerized Aniline-Based Stainless Steel Fiber Coatings Modified by Multi-Walled Carbon Nanotubes for Electroanalysis of 4-Chlorophenol

In this paper, a stainless steel fiber coated electropolymerized aniline, without and with carbon nanotubes (SS/PANI and SS/PANI/CNT), along with CNTs modified carbon paste electrodes (CPEs), were prepared. The electrodes were characterized by differential pulse voltammetry (DPV) and applied for the detection of 4-chlorophenol (4-CP). For all the electrodes, the oxidative peak current showed a linear dependence on the 4-CP concentration in the range of 0.05&ndash;0.5 mmol/L with R2 &ge; 0.991. SS/PANI/CNT electrodes showed greater sensitivity for the detection of the 4-CP than the SS/PANI and CPEs. For all of the aniline-based stainless steel electrodes, both the LOD and LOQ decreased with the increase in the number of electropolymerization cycles. The lowest LOD (0.38 &micro;mol/L) and LOQ (1.26 &micro;mol/L) were observed for the SS/PANI/CNT electrode modified in aniline solution during 30 cycles. The methods were successfully applied to the analysis of 4-CP in real samples (tap water and river water). The results demonstrated the good agreement of the added and found concentrations of the 4-CP. The recovery and precision were from 95.12% to 102.24% and from 1.53% to 6.79%, respectively. The proposed electrodes exhibited acceptable reproducibility, admirable stability, and adequate repeatability and showed potential for the analysis of 4-CP in water