In situ photoacoustic spectroscopic analysis on photocatalytic decolorization of methylene blue over titanium(IV) oxide particles

Photoabsorption of an aqueous suspension containing methylene blue (MB) dye and titanium(IV) oxide (TiO2) powder was evaluated using photoacoustic spectroscopy (PAS). Simultaneous detection of photoabsorption of MB both in solution and adsorbed on TiO2 was performed using a corrosion-resistant cell with microphone detection. In addition, time-course PAS measurements were employed to observe the photocatalytic decolorization of MB in the aqueous suspension. The time-course data of the MB decolorization process attributed to the oxidation or reduction of MB was obtained at 20 s intervals. Moreover, the MB decolorization rate as a function of the initial pH of the suspension was different from that obtained by conventional evaluation methods. This discrepancy most likely stems from the advantages of PAS analysis, which enables the detection of all MB dye included in the aqueous suspension

How precisely do SPECT images reflect tracer uptake in myocardial infarction? A comparison of thallium-201 and technetium-99m using a myocardial phantom

金沢大学大学院医学系研究科量子医療技術学Objective: We compared the count ratios of 201Tl and 99mTc on SPECT images and the true radioactivity in a myocardial phantom to study how precisely SPECT images reflect tracer uptake in myocardial infarction. Methods: A defect with 20%, 40% or 60% of normal myocardial radioactivity was placed in the anterior or inferior wall of a myocardial phantom to simulate myocardial infarction. Lung radioactivity was kept at 10% or 30% of normal myocardial radioactivity. The count ratio on short-axis SPECT images was calculated using the circumferential profile curve analysis. Results: The count ratios of 201Tl and 99mTc SPECT images with an anterior wall defect was lower than the true radioactivity in the phantom. The count ratio on SPECT images with the inferior wall defect was greater than the true radioactivity for the 20% and 40% defects and lower for the 60% defect. Conclusion: SPECT images overestimated decreased perfusion in the anterior wall. SPECT images underestimated decreased perfusion for 20% and 40% perfusion defects in the inferior wall

Comparison of regional myocardial Technetium-99m-MIBI uptake between ECG-gated and ungated SPECT imaging

金沢大学大学院医学系研究科量子医療技術学Technetium-99m-MlBI uptake was compared between ECG-gated and ungated SPECT images in 10 normal subjects and 10 patients with coronary artery disease to investigate the effects of wall motion on regional myocardial uptake. Methods: Left ventricular ejection fraction (LVEF) and wall motion were evaluated using the first-pass data acquired immediately after injection of 1110 MBq 99mTc-MIBI. A transaxial ungated image was reconstructed with cumulative data during a cardiac cycle. For transaxial gated images, data during a cardiac cycle were divided into eight frames and the first seven frames were used. The lateral/septal ratios for ungated and gated images were obtained using the counts in the ROIs drawn in the lateral and the septal walls. Results: In 10 normal subjects, the lateral/septal ratio for gated increased during end-systole. The mean of the lateral/septal ratio was significantly lower for ungated than for gated (1.025 vs. 1.077, p < 0.05). In patients with septal wall asynergy and a normokinetic lateral wall, the mean of the lateral/septal ratios was significantly lower for ungated than for gated (1.267 vs. 1.325, p < 0.01). Conclusion: Ungated SPECT acquisition may underestimate regional myocardial uptake when myocardial wall motion is good, therefore, ECG-gated data should be acquired for accurate assessment of regional myocardial uptake of 99mTc-MIBI

New functional polar maps for estimating regional cardiac function using ECG-gated technetium-99m-tetrofosmin SPECT

金沢大学大学院医学系研究科量子医療技術学Objective: The purpose of this work was to develop functional parameters to analyze regional cardiac function using ECG-gated 99mTc-tetrofosmin SPECT. Our goal was to develop a methodology that used slice thickness correction, the generation of a time-activity curve and a polar map. Methods: Fourteen normal patients without evidence of coronary artery disease were studied. One hour after intravenous injection of 740-1110 MBq (20-30 mCi) 99mTc-tetrofosmin, ECG-gated SPECT data were acquired by dividing a cardiac cycle into 12 frames. The SPECT data were reconstructed from 11 of 12 frames into 3 views. The reconstruction of these images was repeated after performing slice thickness correction. Excluding the effect of different apex-to-base lengths at any frame during a cardiac cycle, 10 short-axis images with the same slice thickness were obtained. Each short-axis image was divided by 40 radii into 40 segments. The time-activity curve was generated from the total counts included in each segment plus both neighboring segments. Subsequently the curve fitting was performed using the second Fourier function. Results: From fitted curves and their differentials, we calculated end-systolic count, end-diastolic count, percent count increase, uptake, peak contraction rate, peak distention rate and contraction time. Conclusion: The functional polar maps visually demonstrated regional myocardial function. This method is expected to be helpful for assessing regional cardiac function using 99mTc-tetrofosmin

New functional polar maps for estimating regional cardiac function using ECG-gated technetium-99m-tetrofosmin SPECT

金沢大学大学院医学系研究科Objective: The purpose of this work was to develop functional parameters to analyze regional cardiac function using ECG-gated 99mTc-tetrofosmin SPECT. Our goal was to develop a methodology that used slice thickness correction, the generation of a time-activity curve and a polar map. Methods: Fourteen normal patients without evidence of coronary artery disease were studied. One hour after intravenous injection of 740-1110 MBq (20-30 mCi) 99mTc-tetrofosmin, ECG-gated SPECT data were acquired by dividing a cardiac cycle into 12 frames. The SPECT data were reconstructed from 11 of 12 frames into 3 views. The reconstruction of these images was repeated after performing slice thickness correction. Excluding the effect of different apex-to-base lengths at any frame during a cardiac cycle, 10 short-axis images with the same slice thickness were obtained. Each short-axis image was divided by 40 radii into 40 segments. The time-activity curve was generated from the total counts included in each segment plus both neighboring segments. Subsequently the curve fitting was performed using the second Fourier function. Results: From fitted curves and their differentials, we calculated end-systolic count, end-diastolic count, percent count increase, uptake, peak contraction rate, peak distention rate and contraction time. Conclusion: The functional polar maps visually demonstrated regional myocardial function. This method is expected to be helpful for assessing regional cardiac function using 99mTc-tetrofosmin

Creation and characterization of Japanese standards for myocardial perfusion SPECT: database from the Japanese Society of Nuclear Medicine Working Group

金沢大学大学院医学系研究科がん制御

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection