Static CT myocardial perfusion imaging: image quality, artifacts including distribution and diagnostic performance compared to 82Rb PET

Background Rubidium-82 positron emission tomography (82Rb PET) MPI is considered a noninvasive reference standard for the assessment of myocardial perfusion in coronary artery disease (CAD) patients. Our main goal was to compare the diagnostic performance of static rest/ vasodilator stress CT myocardial perfusion imaging (CT-MPI) to stress/ rest 82Rb PET-MPI for the identification of myocardial ischemia. Methods Forty-four patients with suspected or diagnosed CAD underwent both static CT-MPI and 82Rb PET-MPI at rest and during pharmacological stress. The extent and severity of perfusion defects on PET-MPI were assessed to obtain summed stress score, summed rest score, and summed difference score. The extent and severity of perfusion defects on CT-MPI was visually assessed using the same grading scale. CT-MPI was compared with PET-MPI as the gold standard on a per-territory and a per-patient basis. Results On a per-patient basis, there was moderate agreement between CT-MPI and PET-MPI with a weighted 0.49 for detection of stress induced perfusion abnormalities. Using PET-MPI as a reference, static CT-MPI had 89% sensitivity (SS), 58% specificity (SP), 71% accuracy (AC), 88% negative predictive value (NPV), and 59% positive predictive value (PPV) to diagnose stress-rest perfusion deficits on a per-patient basis. On a per-territory analysis, CT-MPI had 73% SS, 65% SP, 67% AC, 90.8% NPV, and 34% PPV to diagnose perfusion deficits. Conclusions CT-MPI has high sensitivity and good overall accuracy for the diagnosis of functionally significant CAD using 82Rb PET-MPI as the reference standard. CT-MPI may play an important role in assessing the functional significance of CAD especially in combination with CCTA.

Lung perfusion changes in COVID-19 pneumonia: a dual energy computerized tomography study

Objective: There is limited and contradictory information about pulmonary perfusion changes detected with dual energy computed tomography (DECT) in COVID-19 cases. The purpose of this study was to define lung perfusion changes in COVID-19 cases with DECT, as well as to reveal any possible links between perfusion changes and laboratory findings. Methods: Patients who had a positive RT-PCR for SARS-CoV-2 and a contrast-enhanced chest DECT examination were included in the study. The pattern and severity of perfusion deficits were evaluated, as well as the relationships between perfusion deficit severity and laboratory results and CT severity ratings. The paired t-test, Wilcoxon test, and Student’s t-test were used to examine the changes in variables and perfusion deficits. p < 0.05 was regarded as statistically significant. Results: Study population consisted of 40 patients. Mean age was 60.73 ± 14.73 years. All of the patients had perfusion deficits at DECT images. Mean perfusion deficit severity score of the population was 8.45 ± 4.66 (min.-max, 1–19). In 24 patients (60%), perfusion deficits and parenchymal lesions matched completely. In 15 patients (37.5%), there was partial match. D dimer, CRP levels, CT severity score, and perfusion deficit severity score all had a positive correlation Conclusions: Perfusion deficits are seen not only in opacification areas but also in parenchyma of normal appearance. The CT severity score, CRP, D-dimer, and SpO2 levels of the patients were determined to be related with perfusion deficit severity. Advances in knowledge: Findings of the current study may confirm the presence of micro-thrombosis in COVID-19 pneumonia.

Optimized cervical spinal cord perfusion MRI after traumatic injury in the rat

Despite the potential to guide clinical management of spinal cord injury and disease, noninvasive methods of monitoring perfusion status of the spinal cord clinically remain an unmet need. In this study, we optimized pseudo-continuous arterial spin labeling (pCASL) for the rodent cervical spinal cord and demonstrate its utility in identifying perfusion deficits in an acute contusion injury model. High-resolution perfusion sagittal images with reduced imaging artifacts were obtained with optimized background suppression and imaging readout. Following moderate contusion injury, perfusion was clearly and reliably decreased at the site of injury. Implementation of time-encoded pCASL confirmed injury site perfusion deficits with blood flow measurements corrected for variability in arterial transit times. The noninvasive protocol of pCASL in the spinal cord can be utilized in future applications to examine perfusion changes after therapeutic interventions in the rat and translation to patients may offer critical implications for patient management.

Abstract 15250: The Correlation Between the Amounts of Exosomes and Functional Parameters of Myocardial Perfusion Imaging in the Patients With Coronary Artery Disease

Introduction: Exosomes were found to be involved in the pathophysiological process of coronary artery disease (CAD). The study investigated the relationship of the exosome amounts and imaging markers of myocardial perfusion in patients with CAD. Methods: Peripheral blood was collected from patients who had more than 70% luminal stenosis of coronary arteries on coronary angiography. Plasma exosomes were extracted by chemical precipitation and flow cytometry (CytoFLEX BB10068). Further confirmation of exosome surface markers was performed by Western blot. The myocardial perfusion imaging (MPI) of single photon emission computed tomography performed less than 6 months before coronary angiography were retrospectively reviewed. Perfusion deficits of MPI were scored visually by a nuclear medicine physician. Functional parameters of MPI were generated from gated images by QPS/QGS software (Cedars-Sinai), including ejection fraction (EF), diastolic function, shape index of heart, etc. The amounts of exosomes were correlated with the perfusion deficits and functional parameters of MPI using Spearman’s correlation. Comparison of the exosome amounts between patients with normal or abnormal functional parameters was performed by Mann-Whitney U test. Results: Exosome amounts and MPI images from 40 patients with CAD were analyzed. Exosome amounts have poor correlation with perfusion and functional parameters of MPI (all R value <0.5). However, patients with abnormal post-stress ejection fraction (<50%) had significantly higher amounts of exosome in size of 100nm and 100 to 200nm ( p = 0.046, 0.030, respectively). The mean amounts of exosome in size of 100nm and 100 to 200nm were 67793.8 ± 45498.3 and 19394.1 ± 10995.9 million particle/ml in patients with abnormal EF, compared to 43885.0 ± 24678.4 and 13604.2 ± 8381.3 million particle/ml in patients with normal EF. Conclusions: CAD patients with abnormal systolic function have increasing amounts of exosomes. Exosomes may participate in the dysfunction process of ischemic heart disease. The exact casual relationship and mechanism needs further investigation.

The Chft+ Sensor: A Novel Method to Measure Perfusion Abnormalities in Sickle Cell Disease

Introduction: Peripheral perfusion limitation is a potential biomarker of the severity and progression of sickle cell disease (SCD). Currently, there exists no direct means of quantifying perfusion deficits in SCD patients. Transcranial doppler ultrasonography offers a surrogate measure of perfusion and is highly operator dependent. Routine clinical screening of perfusion abnormalities with alternative modalities (e.g., positron emission tomography and magnetic resonance imaging) is challenging given high cost, requirement for sedation in young children, and need for trained personnel. The Combined Heat-Flux Temperature Sensor (CHFT+) is a novel noninvasive bio-heat perfusion sensor that measures peripheral perfusion in real time at depths of up to 1 cm by applying a minimal amount of heat to the skin surface. Because perfusion limitation is a hallmark of SCD, an improved understanding of its pathophysiology could potentially empower both patients and their physicians. The aim of this study was to evaluate the ability of the CHFT+ to detect differences in peripheral perfusion between healthy volunteers and patients with SCD. Materials and Methods: The present study is an ongoing, non-randomized pilot study that aims to test the CHFT+ sensor's ability to detect impaired perfusion is pediatric SCD patients. We are actively enrolling pediatric patients (age 3-17) with SCD and healthy volunteers from 2 pediatric clinics to test the sensor. Peripheral perfusion measurements were obtained at 5 locations on the body (e.g., forehead, forearms, palms). All measurements were normalized against forehead perfusion values to account for individual variations. An independent-samples t-test was conducted to compare average rates of perfusion in patients with SCD and in healthy volunteers. The goal enrollment for this study is 52 patients (26 with SCD, 26 healthy controls) to detect a two-fold difference in perfusion with a power of 0.80. Interim Results and Discussion: To date, 31 participants have been enrolled, 10 (32%) of whom were patients with SCD. Overall, average perfusion rates were lower in the SCD group when compared to the healthy group, although these differences were not statistically significant. Representative measurements of perfusion in the right and left forearms, normalized against forehead rates, are shown in Figure 1. Normalized left forearm perfusion in healthy controls vs. SCD patients: avg = 1.77, SD = 0.95 vs. avg = 1.28, SD = 0.52, respectively [t(27) = 1.80, p = 0.08]; see Fig. 1a. Normalized right forearm perfusion in healthy controls vs. SCD patients: avg = 1.80, SD = 1.01 vs. avg = 1.31, SD = 0.60, respectively [t(25) = 1.55, p = 0.13]); see Fig. 1b. Conclusions:At this time, our data suggest that the novel CHFT+ sensor is capable of detecting a modest difference in peripheral perfusion in children with SCD versus healthy controls, but this difference is not statistically significant due to limited enrollment. Additional enrollment will further define the utility of the CHFT+ sensor in this clinical population. Future studies should evaluate the sensor's capability to detect perfusion deficits in the adult SCD population, as well as measure perfusion variations that occur during SCD vaso-occlusive crises. Disclosures Diller: FluxTeq:Other: Partner.

Assessment of tissue permeability by early CT perfusion as a surrogate parameter for early brain injury after subarachnoid hemorrhage

OBJECTIVEThe severity of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (aSAH) correlates with delayed cerebral ischemia (DCI) and outcome. A disruption of the blood-brain barrier is part of EBI pathophysiology. The aim of this study was to assess tissue permeability (PMB) by CT perfusion (CTP) in the acute phase after aSAH and its impact on DCI and outcome.METHODSCTP was performed on day 3 after aSAH. Qualitative and quantitative analyses of all CTP parameters, including PMB, were performed. The areas with increased PMB were documented. The value of an early PMB increase as a predictor of DCI and outcome according to the modified Rankin Scale (mRS) grade 3 to 24 months after aSAH was assessed. Possible associations of increased PMB with the Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) and with early perfusion deficits, as radiographic EBI markers, were evaluated.RESULTSA total of 69 patients were enrolled in the study. An increased PMB on early CTP was detected in 10.1% (7/69) of all patients. A favorable outcome (mRS grade ≤ 2) occurred in 40.6% (28/69) of all patients. DCI was detected in 25% (17/69) of all patients. An increased PMB was a predictor of DCI (logistic regression, p = 0.03) but not of outcome (logistic regression, p = 0.40). The detection of increased PMB predicted DCI with a sensitivity of 25%, a specificity of 94%, a positive predictive value of 57%, and a negative predictive value of 79% (chi-square test p = 0.03). Early perfusion deficits were seen in 68.1% (47/69) of the patients, a finding that correlated with DCI (p = 0.005) but not with the outcome. No correlation was found between the SEBES and increased PMB.CONCLUSIONSChanges in PMB can be detected by early CTP after aSAH, which correlates with DCI. Future studies are needed to evaluate the time course of PMB changes and their interaction with therapeutic measures.