Dynamic Single-Photon Emission Computed Tomography Data Analysis: Capabilities for Determining Functional Significance of Coronary Artery Atherosclerosis

The aim of the study was to develop the method for collecting and processing scintigraphic data to determine myocardial flow reserve by using gamma-camera with a new type detector based on Cadmium Zinc Telluride (CZT). Sixteen coronary artery disease patients and nine healthy volunteers received cardiac dynamic single-photon emission computed tomography with technetium 99m methoxyisobutylisonitrile ({99m}Tc-MIBI) at rest and during pharmacologic stress test. Data processing involved a formation of regions of interest from the left ventricular (LV) cavity and myocardial walls to build activity-time curves. Myocardial flow reserve index was determined as a quotient of two ratios of mean myocardial counts to area under a curve peak from LV cavity during stress test and at rest. Mean values of myocardial flow reserve index were 1.86 (1.59; 2.2) in group of healthy volunteers and 1.39 (1.12; 1.69) in patients with multivessel coronary artery disease. When the value of this index was less than 1.77, the method allowed for identification of multivessel disease with sensitivity and specificity of 81.8% and 66.7%, respectively. Standard myocardial perfusion scintigraphy in combination with the method of myocardial flow reserve index determination allows for increasing diagnostic significance of the scintigraphic approach for assessment of coronary microcirculation lesions in multivessel coronary artery disease

Lung scintigraphy in differential diagnosis of peripheral lung cancer and community-acquired pneumonia

Ventilation/perfusion lung scintigraphy was performed in 39 patients with verified diagnosis of community-acquired pneumonia (CAP) and in 14 patients with peripheral lung cancer. Ventilation/perfusion ratio, apical-basal gradients of ventilation (U/L(V)) and lung perfusion (U/L(P)), and alveolar capillary permeability of radionuclide aerosol were determined based on scintigraphy data. The study demonstrated that main signs of CAP were increases in ventilation/perfusion ratio, perfusion and ventilation gradient on a side of the diseased lung, and two-side increase in alveolar capillary permeability rate for radionuclide aerosol. Unlike this, scintigraphic signs of peripheral lung cancer comprise an increase in ventilation/perfusion ratio over 1.0 on a side of the diseased lung with its simultaneous decrease on a contralateral side, normal values of perfusion and ventilation gradients of both lungs, and delayed alveolar capillary clearance in the diseased lung compared with the intact lung

Возможности использования сцинтиграфических методов в дифференциальной диагностике острой тромбоэмболии легочной артерии и хронической постэмболической легочной гипертензии

Purpose. The purpose of the study was to evaluate the capabilities of lung scintigraphy and gated equilibrium radionuclide blood-pool SPECT in the differential diagnostics of acute pulmonary embolism and chronic postembolic pulmonary hypertension. Material and methods. The study included 78 patients, which have been divided into two groups: 62 (79.5%) patients had a verified diagnosis of acute pulmonary embolism and 16 (20.5%) patients - chronic postembolic pulmonary hypertension. Patients underwent a full range of clinical and diagnostic examinations, including ventilation/perfusion scintigraphy and gated equilibrium radionuclide blood-pool SPECT; 12 patients underwent multidetector computed tomographic (MDCT) angiography of the pulmonary arteries. Results. According to ventilation/perfusion lung scintigraphy data, perfusion defects were found in the upper and middle parts of the lungs in patients with acute pulmonary embolism. In these patients, perfusion defects were characterized by clear demarcation and by triangular or wedge-like shape. Localizations of the thrombosed vessels did not correspond to the areas with ventilation abnormalities. The ratio of transverse dimensions of right to left ventricular blood pools (RV/LV) in axial slices did not exceed 1.0. In patients diagnosed with chronic postembolic pulmonary hypertension, the areas of abnormal circulation were diffuse; the boundaries between the diseased areas and the intact pulmonary tissue were not clearly demarcated. In these patients, the RV/LV ratio in axial slices exceeded 1.0. Scintigraphic identification of pulmonary disorders was verified by MDCT pulmonary angiography. Conclusion. The use of scintigraphic methods aimed at assessment of the functional states of the heart and the lungs contributed to the accuracy of complicated differential diagnosis of acute pulmonary embolism and chronic postembolic pulmonary hypertension. Diagnostic information acquired with scintigraphic methods allowed for timely administration of adequate therapy.Цель исследования: оценить возможности использования пульмоносцинтиграфии и равновесной радионуклидной вентрикулографии (РРВГ) в комплексной дифференциальной диагностике острой тромбоэмболии легочной артерии (ТЭЛА) и хронической постэмболической легочной гипертензии. Материал и методы. Обследованы 78 больных, которые были разделены на 2 группы: с верифицированным диагнозом острой ТЭЛА - 62 (79,5%) больных и с хронической постэмболической легочной гипертензией-16 (20,5%) больных. Пациенты прошли полный комплекс клинико-диагностических исследований, включающий в себя вентиляционно-перфузионную пульмоносцинтиграфию и РРВГ сердца, мультиспиральная компьютерная томоангиопульмонография проведена 12 больным. Результаты. По данным вентиляционной и перфузионной сцинтиграфии у пациентов с острой ТЭЛА в верхних и средних отделах легких были обнаружены дефекты перфузии, которые характеризовались четкостью контуров, имели треугольную или клиновидную форму, соответствовали бассейну тромбированного сосуда и по локализации не совпадали с областями вентиляционных нарушений. Соотношение поперечных размеров радиоактивного пула крови правого желудочка сердца к левому (ПЖ/ЛЖ) на аксиальных томографических срезах не превышало 1,0. У лиц с хронической постэмболической легочной гипертензией картина нарушений кровоснабжения имела диффузно-неравномерный характер, границы между пораженными отделами и интактной тканью легких были нечеткими. Показатель соотношения поперечных размеров радиоактивного пула крови ПЖ/ЛЖ превышал 1,0. Выявленные сцинтиграфические легочные нарушения были верифицированы результатами рентгеноконтрастной ангиопульмонографии. Выводы. Использование сцинтиграфических методов оценки функционального состояния легких и сердца способствует повышению точности комплексной дифференциальной диагностики ТЭЛА и хронической постэмболической легочной гипертензии, что позволяет своевременно назначить адекватную терапию

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

Dynamic Single-Photon Emission Computed Tomography Data Analysis: Capabilities for Determining Functional Significance of Coronary Artery Atherosclerosis

The aim of the study was to develop the method for collecting and processing scintigraphic data to determine myocardial flow reserve by using gamma-camera with a new type detector based on Cadmium Zinc Telluride (CZT). Sixteen coronary artery disease patients and nine healthy volunteers received cardiac dynamic single-photon emission computed tomography with technetium 99m methoxyisobutylisonitrile (99mTc-MIBI) at rest and during pharmacologic stress test. Data processing involved a formation of regions of interest from the left ventricular (LV) cavity and myocardial walls to build activity-time curves. Myocardial flow reserve index was determined as a quotient of two ratios of mean myocardial counts to area under a curve peak from LV cavity during stress test and at rest. Mean values of myocardial flow reserve index were 1.86 (1.59; 2.2) in group of healthy volunteers and 1.39 (1.12; 1.69) in patients with multivessel coronary artery disease. When the value of this index was less than 1.77, the method allowed for identification of multivessel disease with sensitivity and specificity of 81.8% and 66.7%, respectively. Standard myocardial perfusion scintigraphy in combination with the method of myocardial flow reserve index determination allows for increasing diagnostic significance of the scintigraphic approach for assessment of coronary microcirculation lesions in multivessel coronary artery disease

The Influence of Kinetic Models and Attenuation Correction on Cadmium&ndash;Zinc&ndash;Telluride Single-Photon Emission Computed Tomography (CZT SPECT)-Derived Myocardial Blood Flow and Reserve: Correlation with Invasive Angiography Data

(1) Background: The objective of this study was to determine the optimal post-processing model for dynamic cadmium&ndash;zinc&ndash;telluride single-photon emission computed tomography (CZT-SPECT). (2) Methods: A total of 235 patients who underwent diagnostic invasive coronary angiography within three months of the SPECT and those who had coronary computed tomography angiography (CCTA) before SPECT (within 3 months) were enrolled in this study. Each SPECT study was processed to obtain global and regional stress myocardial blood flow (sMBF), rest-MBF (rMBF), myocardial flow reserve (MFR) and flow difference (FD) estimates obtained with 1-tissue-compartment (1TCM) and net retention (NR) modes, both with and without attenuation correction. (3) Results: The use of AC led to significantly higher sMBF, rMBF and DF values obtained by 1TCM compared those values derived by 1TCM with NAC; the lowest values of stress MBF and rest MBF were obtained by 1TCM_NAC. The resting flow, MFR and DF were significantly (p &lt; 0.005) higher in the AC model than in NAC. All quantitative variables were significantly (p &lt; 0.05) higher in NR_NAC than in the 1TC_NAC model. Finally, sMBF, rMBF and FD showed significantly (p &lt; 0.05) higher values by using 1TMC_AC compared to NR_AC. (4) Conclusions: We suggested that 1-compartment and net retention models correctly reflect coronary microcirculation and can be used for clinical practice for evaluating quantitative myocardial perfusion by dynamic SPECT. Attenuation correction is an important step in post-processing dynamic SPECT data, which increases the consistency and diagnostic accuracy of models