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Prognostic value of SPECT myocardial perfusion entropy in high-risk type 2 diabetic patients : The EVADIAB study

Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the assessment of myocardial ischemia provides valuable prognostic value. However, the risk stratification of patients with type 2 diabetes mellitus (T2D) remains suboptimal. Recent studies have highlighted the role of coronary microvascular disease in the occurrence of coronary symptoms in this population. We hypothesized that enhanced signal analysis from SPECT myocardial perfusion images may allow insights into the status of the coronary microvasculature. More specifically, we hypothesized that myocardial perfusion entropy (MPE) as a surrogate marker of microvascular disease quantified from SPECT myocardial perfusion images may provide an incremental prognostic value in T2D patients independently from the routinely performed assessment of myocardial ischemia. T2D patients with very high cardiovascular risk were studied (n = 166, 65 ± 12 years). Ischemia was assessed by SPECT myocardial perfusion imaging (MPI). In addition, SPECT MPI was used for the quantification of rest and stress MPE using an original algorithm providing a global value of MPE from reconstructed rest and stress SPECT images. The primary end point was major adverse cardiac events (MACEs) defined as cardiac death, Q-wave myocardial infarction (MI) and myocardial revascularization > 3 months after SPECT. Forty-six patients underwent MACEs over a median follow-up of 4.6 years. Significant differences in stress MPE were observed between patients with and without MACEs (4.19 ± 0.46 vs. 3.93 ± 0.39; P ≤ 0.01). By Kaplan-Meier analysis, the risk of MACEs was significantly higher in patients with higher stress MPE (log-rank P ≤ 0.01). Stress MPE was significantly associated with the risk of MACEs (hazard ratio: 2.80, P ≤ 0.01) after adjustment for clinical and imaging risk factors as identified from preliminary, univariate analysis and including age, hypertension and ischemia. The risk of overfitting was controlled by internal validation procedures such as LASSO, stepwise and random forests selections on time-to-MACEs Cox models. A competing risk event (“other deaths”) slightly overestimated Cox estimates. However, the impact of informative censorship was assessed by Fine-Gray subdistribution hazard estimates and proved to be marginal. The incremental prognostic value of MPE over clinical risk factors was quantified using nested models showing improved AIC, reclassification (global continuous Net Reclassification Improvement [NRI]: 70.1, global Integrated Discrimination Improvement [IDI]: 6.6%), discrimination (change in c-statistic: 0.69 vs. 0.74), and time-dependent AUC (0.71 vs. 0.77 at 4 years of follow-up). Stress MPE provided independent and incremental prognostic information for the prediction of MACEs in diabetic patients.

Prognostic value of myocardial perfusion entropy in patients with normal thallium-201 myocardial perfusion with a CZT camera : PROMHETE study

Objectives We assessed the prognostic value of myocardial perfusion heterogeneity (entropy) in patients with normal myocardial perfusion as estimated from a dual isotope high-speed protocol (Thallium-201 stress and technetium- 99m-sestamibi rest) performed on a semiconductor camera. Background The prognostic value of normal myocardial perfusion scintigraphic imaging has been widely established for over twenty years but the clinical value of perfusion heterogeneity quantification beyond perfusion imaging as routinely performed is unknown. Methods From May 2011 to September 2012, 1159 patients with a normal scan or a non-significant perfusion abnormality (SSS 45%) were retrospectively identified. This study reports an interim analysis of 443 patients. A dual isotope high-speed protocol was performed on a semiconductor camera following exercise testing (37%) or pharmacological stress (63%). Myocardial perfusion images were then used to quantify myocardial perfusion heterogeneity as estimated by stress and rest image entropy. The primary endpoint was the occurrence of a cardiovascular event (cardiovascular death, non-fatal myocardial infarction, coronary angiography with or without revascularization, and stroke). Results The primary endpoint occurred in 73 patients during follow-up (3.3 ± 0.4 years). In a multivariate analysis, age (HR 1.04 [1.01; 1.06] P 4.06) underwent more events than those with a lower entropy ( Conclusions Myocardial perfusion heterogeneity (entropy) determined from thallium-201 stress perfusion images acquired on a semiconductor camera represent an independent prognostic factor of cardiovascular events with additive value over the classical interpretation of images from patients with normal myocardial perfusion scintigraphy. Myocardial perfusion heterogeneity (entropy) might represent a surrogate of coronary microvascular dysfunction.

Left ventricular eccentricity index measured with SPECT myocardial perfusion imaging: An additional parameter of adverse cardiac remodeling

BackgroundSingle-photon emission computed-tomography (SPECT) allows the quantification of LV eccentricity index (EI), a measure of cardiac remodeling. We sought to evaluate the feasibility of EI measurement with SPECT myocardial perfusion imaging and its interactions with relevant LV functional and structural parameters. Methods and resultsFour-hundred and fifty-six patients underwent myocardial perfusion imaging on a Cadmium-Zinc-Telluride (CZT) camera. The summed rest, stress, and difference scores were calculated. From rest images, the LV end-diastolic (EDV) and end-systolic volumes, ejection fraction (EF), and peak filling rate (PFR) were calculated. In every patient, the EI, ranging from 0 (sphere) to 1 (line), was computed using a dedicated software (QGS/QPS; Cedars-Sinai Medical Center). Three-hundred and thirty-eight/456 (74%) patients showed a normal EF (>50%), while 26% had LV systolic dysfunction. The EI was computed from CZT images with excellent reproducibility (interclass correlation coefficient: 0.99, 95% CI 0.98-0.99). More impaired EI values correlated with the presence of a more abnormal LV perfusion (P < .001), function (EF and PFR, P < .001), and structure (EDV, P < .001). On multivariate analysis, higher EDV (P < .001) and depressed EF (P = .014) values were independent predictors of abnormal EI. ConclusionsThe evaluation of LV eccentricity is feasible on gated CZT images. Abnormal EI associates with significant cardiac structural and functional abnormalities.

Resting coronary velocity and myocardial performance in women with impaired coronary flow reserve: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

BackgroundWomen with evidence of ischemia and no obstructive coronary arteries (INOCA) often have coronary microvascular dysfunction (CMD) indicated by impaired coronary flow reserve (CFR) to adenosine. Low CFR is associated with an adverse prognosis, including incident heart failure. Because the CFR calculation relies on the baseline intrinsic coronary vasomotor flow velocity, a major determinate of CFR and the degree of variation in baseline flow alone may be an important contributor to risk of adverse outcomes in women with CMD. A better understanding of baseline blood flow in the setting of low CFR and its association with myocardial performance would be helpful. MethodsWe evaluated 74 women who underwent invasive coronary reactivity testing in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study and had impaired CFR (<2.32). We assessed the relationship between coronary artery baseline average peak velocity (bAPV) at rest and cardiac magnetic resonance imaging measures of left ventricular (LV) structure and function. ResultsWhen stratified as low (<22 cm/s) versus high (≥22 cm/s) bAPV, there were no differences in cardiovascular risk factors, coronary plaque burden, or LV structure. However, low bAPV was associated with higher LV end-diastolic filling pressure (P = 0.04), lower LV ejection fraction (P = 0.001), and differences in late systolic and diastolic strain rates (P = 0.01 to 0.05). ConclusionsIn women with impaired CFR, low resting coronary flow velocity is associated with more adverse myocardial performance, which may contribute to risk for adverse outcomes and particularly heart failure in women with CMD.

Preclinical Validation of a Single-Scan Rest/Stress Imaging Technique for 13N-Ammonia Positron Emission Tomography Cardiac Perfusion Studies.

We previously proposed a technique for quantitative measurement of rest and stress absolute myocardial blood flow (MBF) using a 2-injection single-scan imaging session. Recently, we validated the method in a pig model for the long-lived radiotracer 18F-Flurpiridaz with adenosine as a pharmacological stressor. The aim of the present work is to validate our technique for 13NH3. Nine studies were performed in 6 pigs; 5 studies were done in the native state and 4 after infarction of the left anterior descending artery. Each study consisted of 3 dynamic scans: a 2-injection rest-rest single-scan acquisition (scan A), a 2-injection rest/stress single-scan acquisition (scan B), and a conventional 1-injection stress acquisition (scan C). Variable doses of adenosine combined with dobutamine were administered to induce a wide range of MBF. The 2-injection single-scan measurements were fitted with our nonstationary kinetic model (MGH2). In 4 studies, 13NH3 injections were paired with microsphere injections. MBF estimates obtained with our method were compared with those obtained with the standard method and with microspheres. We used a model-based method to generate separate rest and stress perfusion images. In the absence of stress (scan A), the MBF values estimated by MGH2 were nearly the same for the 2-radiotracer injections (mean difference: 0.067±0.070 mL·min-1·cc-1, limits of agreement: [-0.070 to 0.204] mL·min-1·cc-1), showing good repeatability. Bland-Altman analyses demonstrated very good agreement with the conventional method for both rest (mean difference: -0.034±0.035 mL·min-1·cc-1, limits of agreement: [-0.103 to 0.035] mL·min-1·cc-1) and stress (mean difference: 0.057±0.361 mL·min-1·cc-1, limits of agreement: [-0.651 to 0.765] mL·min-1·cc-1) MBF measurements. Positron emission tomography and microsphere MBF measurements correlated closely. Very good quality perfusion images were obtained. This study provides in vivo validation of our single-scan rest-stress method for 13NH3 measurements. The 13NH3 rest/stress myocardial perfusion imaging procedure can be compressed into a single positron emission tomography scan session lasting less than 15 minutes.

One View Per City for Buildings Segmentation in Remote-Sensing Images via Fully Convolutional Networks: A Proof-of-Concept Study.

The segmentation of buildings in remote-sensing (RS) images plays an important role in monitoring landscape changes. Quantification of these changes can be used to balance economic and environmental benefits and most importantly, to support the sustainable urban development. Deep learning has been upgrading the techniques for RS image analysis. However, it requires a large-scale data set for hyper-parameter optimization. To address this issue, the concept of “one view per city” is proposed and it explores the use of one RS image for parameter settings with the purpose of handling the rest images of the same city by the trained model. The proposal of this concept comes from the observation that buildings of a same city in single-source RS images demonstrate similar intensity distributions. To verify the feasibility, a proof-of-concept study is conducted and five fully convolutional networks are evaluated on five cities in the Inria Aerial Image Labeling database. Experimental results suggest that the concept can be explored to decrease the number of images for model training and it enables us to achieve competitive performance in buildings segmentation with decreased time consumption. Based on model optimization and universal image representation, it is full of potential to improve the segmentation performance, to enhance the generalization capacity, and to extend the application of the concept in RS image analysis.

Low-dose dynamic myocardial perfusion imaging by CZT-SPECT in the identification of obstructive coronary artery disease.

We measured myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by a dynamic low-dose CZT-SPECT protocol in patients with suspected or known coronary artery disease (CAD) and investigated the capability of dynamic data in predicting obstructive CAD. A total of 173 patients with suspected or known CAD underwent dynamic CZT-SPECT after the injection of 155MBq and 370MBq of 99mTc-sestamibi for rest and stress imaging, respectively. Standard rest and stress imaging were performed at the end of each dynamic scan. A total perfusion defect (TPD) < 5% were considered normal. Obstructive CAD was defined as ≥ 70% stenosis at coronary angiography. Global MPR was lower (p < 0.05) in patients with abnormal compared with those with normal MPI (2.40 ± 0.7 vs. 2.70 ± 0.8). A weak, albeit significant correlation between TPD and MPR (r = - 0.179, p < 0.05) was found. In 91 patients with available angiographic data, hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1ml/min/g) and MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower (both p < 0.05) in patients with obstructive CAD (n = 21) compared with those without (n = 70). At univariable analysis, TPD, hyperemic MBF, and MPR were significant predictors of obstructive CAD, whereas only MPR was independent predictor at multivariable analysis (p < 0.05). At per vessels analysis, regional hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1ml/min/g) and regional MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower in the 31 vessels with obstructive CAD compared with 242 vessels without (both p < 0.05). In patients with suspected or known CAD, MPR assessed by low-dose dynamic CZT-SPECT showed a good correlation with myocardial perfusion imaging findings and it could be useful to predict obstructive CAD.

Amplitude of low-frequency fluctuations of resting-state functional MRI in colorectal cancer patients with depression

Objective: To investigate the alterations of the cerebral resting-state spontaneous neural activity in colorectal cancer patients with depressive symptoms. Methods: Thirty-three colorectal cancer patients (patient group) with depression and 43 healthy subjects (control group) underwent the resting state functional magnetic resonance imaging (rs-fMRI). The amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) were calculated. Two independent samples t test were used to compare the ALFF and fALFF values between two groups by DPABI software, and then correlation analysis was performed between ALFF and fALFF with statistical significance and Patient Health Questionnaire (PHQ-9) scores and Generalized Anxiety Disorder (GAD-7) scores. Results: Compared with the control group, the patient group showed significantly lower ALFF and fALFF values in the bilateral precuneus, calcarine gyrus, lingual gyrus, left cuneus, superior, middle, inferior occipital gyrus and right fusiform gyrus (t=-5.730, P<0.05; t=-4.872, P<0.05). There were no significant correlations between the ALFF and fALFF values in these regions and PHQ-9 or GAD-7 scores (P>0.05). Conclusion: Spontaneous decrease of neural activity in occipital and parietal lobes exists in colorectal cancer patients with depression at resting-sate, which may be a potential neurobiological marker.

Stairways to the brain: Transcutaneous spinal direct current stimulation (tsDCS) modulates a cerebellar-cortical network enhancing verb recovery

It has long been assumed that the language function is hierarchically organized into specific cortical areas. Here, for the first time, we present direct evidence that the spinal cord takes part in language processing. In a randomized-double blind design, sixteen aphasics underwent a language treatment combined with transcutaneous spinal direct current stimulation (tsDCS). During the treatment, each subject received tsDCS (20 min, 2 mA) over the thoracic vertebrae (IX-X vertebrae) in two different conditions: (1) anodal, and (2) sham while performing a verb naming task. Each experimental condition was run in five consecutive daily sessions over two weeks. Before and after each condition, all patients underwent a resting state functional magnetic resonance imaging (rs-fMRI). After anodal tsDCS, significant functional connectivity changes were found in a cerebellar-cortical network recruiting regions such as the left cerebellum, the right parietal and premotor cortex known to be also involved in action-related verb processing. Indeed, this increase of connectivity significantly correlated with the greatest amount of improvement found in verb naming. In line with our experimental data, we also found a greater improvement after anodal tsDCS also on untreated items of the language test but only on tasks which required the use of verbs, such as verb naming and picture description. No significant changes were found in noun naming. Thus, this evidence emphasizes, for the first time, that the neural response due to tsDCS combined with language treatment changes during the course of recovery by enhancing activity into cortical regions which influence verb processing.

Cardiac Magnetic Resonance Imaging used for Evaluation of Adipose-Derived Stromal Cell Therapy in Patients with Chronic Ischemic Heart Disease

Adipose-derived stromal cell (ASC) therapy is currently investigated as a new treatment option for patients with ischemic heart disease (IHD). The aim of this study was to evaluate the effect of ASC therapy in patients with chronic IHD measuring myocardial perfusion and cardiac function using cardiac magnetic resonance imaging (CMRI). Patients were included in MyStromalCell trial, a phase II, randomized, double-blinded, placebo-controlled study investigated the effect of ASCs in patients with chronic IHD with preserved left ventricular ejection fraction (LVEF). In total, 41 of 60 patients underwent cine, late enhancement, rest and stress imaging with CMRI. There was a non-significant difference between stress and rest values in maximal signal intensity, a measure of myocardial perfusion, from baseline to follow-up comparing placebo with ASC group (–52.52 ± 88.61 and 3.05 ± 63.17, p = 0.061, respectively). LVEF, myocardial mass, stroke volume, left ventricle end-diastolic volume and end-systolic volume changed non-significantly (–0.5 ± 4.7%, –3.5 ± 13.1 g, –0.7 ± 8.6 mL, 1.9 ± 25.1 mL and 2.6 ± 16.5 mL, respectively) in the placebo group and in the ASC group (0.7 ± 8.6%, 0.9 ± 10.8 g, –0.3 ± 26.1 mL, –3.0 ± 31.5 mL and –2.7 ± 20.4 mL, respectively) from baseline to 6 months follow-up. The amount of scar tissue was unchanged in the placebo group by 0.0 ± 1.6 g, p = 1.0 and in the ASC group with –0.3 ± 2.3 g, p = 0.540. There was no difference between the groups. There was a non-significant trend toward increased myocardial perfusion but no significant changes in functional parameters or amount of scar tissue in patients treated with ASCs compared with patients allocated into the placebo group.

AEROBIC TRAINING, THE DEFAULT MODE NETWORK, AND COGNITION IN OLDER ADULTS WITH MILD VASCULAR COGNITIVE IMPAIRMENT

Aerobic training has been shown to be effective at improving cognitive and brain outcomes in older adults with mild subcortical ischemic vascular cognitive impairment (SIVCI). However, uncertainty remains regarding the underlying neurobiological mechanisms by which exercise elicits these improvements in cognition. Increased aberrant functional connectivity of the default mode network has been highlighted as a factor contributing to cognitive decline in older adults with cognitive impairment. Greater connectivity of the DMN at rest is associated with poorer performance on attention-demanding tasks, indicative of a lack of ability to deactivate the network on task. Our previous work on a randomized controlled trial of participants with mild SIVCI, demonstrated that 6-months of thrice weekly aerobic training led to improved global cognitive function, as measured by Alzheimer’s disease Assessment Scale-Cognitive subscale (ADAS-Cog), compared with a health education program. Thus, we conducted secondary analyses to investigate whether these changes in global cognitive function were associated with changes in resting state DMN connectivity. A subsample of 21 participants underwent a resting state functional magnetic resonance imaging (fMRI) scan before and after trial completion. Change in resting state DMN connectivity was found to significantly predict change in ADAS-Cog score (β = -.442, p=.038) after controlling for age, intervention group, and baseline functional capacity (R2=.467, F(4,16)= 3.507, p=.031). These findings suggest that functional connectivity of the DMN may underlie changes in global cognitive function. Furthermore, aerobic exercise is a promising intervention by which to elicit these changes in older adults with mild SIVCI.

Study on optimizing rapid acquisition time of CZT-SPECT myocardial perfusion imaging using different injection doses

Objective To explore the optimal and rapid imaging acquisition time and clinical applicability when using high- and low-dose one day rest/stress myocardial perfusion imaging (MPI) with cadmium-zinc-telluride heart dedicated SPECT (CZT-SPECT). Methods The MPI data with high-dose rest/stress protocol in 51 patients (22 males, 29 females, age: (55.4±8.5) years) between November 2017 and December 2017 and those with low-dose protocol in 50 patients (27 males, 23 females, age: (59.1±12.8) years) between July 2018 and October 2018 were retrospectively analyzed. The MPI was performed with CZT-SPECT. Each patient received 296-370 MBq rest dose of 99Tcm-methoxyisobutylisonitrile (MIBI) for high-dose protocol, 111-222 MBq rest dose of 99Tcm-MIBI for low-dose protocol. Stress dose was 3 times of the corresponding rest dose. Rest and stress scans were acquired 6 min and 4 min for high-dose protocol, while 8 min and 6 min for low-dose protocol in total. All rest or stress imaging data were reconstructed from list-mode raw data to obtain scan durations of 1 min, 2 min, etc, up to the maximum of acquisition time. Image quality at different acquisition times were evaluated, and myocardial perfusion and function parameters were compared. Paired t test, Wilcoxon signed rank test, Pearson correlation and Bland-Altman analyses were used for data analysis. Results The image quality was rated as excellent/good in all patients (100%, 51/51) when acquisition time ≥3 min and ≥2 min respectively for rest and stress imaging with high-dose protocol, the similar results was obtained (100%, 50/50) when acquisition time ≥4 min and ≥3 min respectively for rest and stress imaging with low-dose protocol. The quantitative perfusion parameters(summed rest scores, summed stress scores, total perfusion deficit) and left ventricle ejection fraction (LVEF) at shorter acquisition times (3 min/2 min, 4 min/3 min) were not significantly different from the results at the longer acquisition times (6 min/4 min, 8 min/6 min; t values: from -1.196 to 1.597, z values: from -1.963 to 1.945, all P>0.05). Those parameters at shorter and longer acquisition times showed strong correlations (all r>0.700, all P<0.001), and Bland-Altman analysis revealed good agreement between them. Conclusion The optimal acquisition time is 3 min/2 min for high-dose one-day rest/stress CZT-SPECT MPI, and 4 min/3 min for low-dose protocol, which can significantly shorten the MPI acquisition time, then reliable perfusion parameters and LVEF can be obtained under the premise of ensuring image quality, making it the better clinical applicability. Key words: Coronary disease; Myocardial perfusion imaging; Cadmium; Zinc; Tellurium; Tomography, emission-computed, single-photon; Time management; Technetium Tc 99m sestamibi

Functional Connectivity Patterns and the Role of 5-HTTLPR Polymorphism on Network Architecture in Female Patients With Anorexia Nervosa.

IntroductionRecent neuroimaging studies suggest that anorexia nervosa (AN) symptoms emerge from failures in the relationships between spatially distributed networks that support different cognitive, emotional, and somatosensory functions. The 5-HTTLPR genotype has been shown to modulate all these abilities in AN, as well as the connectivity patterns between brain regions that support their functioning. This study aims at exploring the presence of any difference in functional connectome properties between AN patients and healthy controls (HC) by means of graph theory tools. The effect of 5-HTTLPR genotype on regional and global network characteristics in AN and HC was also explored.MethodsA sample of 74 subjects (38 HC, 36 AN) underwent a resting state functional magnetic resonance imaging and was genotyped for 5-HTTLPR polymorphism. Comparisons of network properties were made between the AN and HC groups and, within each group, between 5-HTTLPR carriers of low-functioning alleles and carriers of the long–long genotype.ResultsPatients with AN displayed lower network clustering than HC (p = 0.04 at Mann–Whitney U test). Based on both degree and betweenness, a different distribution of network hubs emerged in the two groups. In particular, the anterior part of the anterior cingulate cortex was a hub only in the patient group. A correlation emerged between differences in brain volumes between patients and HC and differences in degree values of basal ganglia, nodes in the insula, and those in the parietal cortex. Carriers of the short allele of the 5-HTTLPR polymorphism were characterized by lower small-world properties (p = 0.027) and modularity (p = 0.031) in the patient group, and a trend toward higher modularity (p = 0.033) and small-world values (p = 0.123) in the HC group.DiscussionPatients with AN showed differences in hubs distribution, providing evidence of the presence of a different functional architectural backbone in this group. Since some correlation emerged between different degree values of nodes and differences in volumes, further longitudinal studies are warranted to better understand the role of malnutrition on brain network architecture. The opposite effects of 5-HTTLPR polymorphism on global network characteristics in the two groups suggest an interaction of the short allele and malnutrition in modulating brain network properties.

P591Insights from Exercise Cardiac Magnetic Resonance Imaging (ExMR) With Cardiopulmonary Testing in HIV Patients

Abstract Background Cardiac magnetic resonance imaging in conjunction with exercise (exMR) and cardiopulmonary testing (CPET) to evaluate cardiopulmonary function has the potential of uncovering poorly understood mechanisms of dyspnea in patients that cannot be otherwise discerned with a single imaging modality. Purpose We prospectively evaluated the value of this technique in dyspneic patients with HIV without obvious cardiopulmonary etiologies to comprehensively assess mechanisms of dyspnea. Methods Thirty-six HIV patients with dyspnea without obvious cardiopulmonary causes [normal chest x-ray, normal resting LVEF and resting pulmonary artery (PA) pressures &lt;40 mm Hg on echo] and exercise limitation [Modified Medical Research Council (MMRC) dyspnea scale &gt;2] underwent testing using a novel combined exMR/CPET platform (Figure 1). Resting and exercise magnetic resonance imaging (MRI), including flow velocities across the pulmonary artery together with CPET was evaluated at pre and post peak stress. We analyzed the correlation between CPET and MRI pre and peak exercise variables. Results The mean age was 51 years; 60% were male; and mean absolute CD4 count was 718. Ventilator efficiency at peak exercise (Peak VO2) did not correlate with exMR parameters. Peak VE/VCO2 was negatively associated with peak LV and RV stroke volume (p values 0.002 &amp; 0.005 respectively). There was a positive relationship between peak petCO2and LV cardiac output (p=0.02), peak exercise RV stroke volume (p=0.003), peak exercise LV stroke volume (p=0.02). Absolute CD4 count was positively correlated with post exercise pulmonary artery velocity (p=0.045). We found no correlation between absolute CD8 count and CMR and CPET exercise parameters. Figure 1. MRI-CPET setting Conclusion HIV patients appear to have an impairment of ventilatory efficiency, exemplified by the association of VE/VCO2and PetCO2 with exMR parameters in the context of normal RV/LV contractile reserve and no evidence of Pulmonary arterial hypertension. A combined CPET/exMRI platform may provide new insight into cardiopulmonary function and the factors influencing exercise tolerance in symptomatic HIV patients. Acknowledgement/Funding 7R01HL125060-03

Reorganization of brain networks and its association with general cognitive performance over the adult lifespan

Healthy aging is associated with structural and functional changes in the brain even in individuals who are free of neurodegenerative diseases. Using resting state functional magnetic resonance imaging data from a carefully selected cohort of participants, we examined cross sectional changes in the functional organization of several large-scale brain networks over the adult lifespan and its potential association with general cognitive performance. Converging results from multiple analyses at the voxel, node, and network levels showed widespread reorganization of functional brain networks with increasing age. Specifically, the primary processing (visual and sensorimotor) and visuospatial (dorsal attention) networks showed diminished network integrity, while the so-called core neurocognitive (executive control, salience, and default mode) and basal ganglia networks exhibited relatively preserved between-network connections. The visuospatial and precuneus networks also showed significantly more widespread increased connectivity with other networks. Graph analysis suggested that this reorganization progressed towards a more integrated network topology. General cognitive performance, assessed by Addenbrooke’s Cognitive Examination-Revised total score, was positively correlated with between-network connectivity among the core neurocognitive and basal ganglia networks and the integrity of the primary processing and visuospatial networks. Mediation analyses further indicated that the observed association between aging and relative decline in cognitive performance could be mediated by changes in relevant functional connectivity measures. Overall, these findings provided further evidence supporting widespread age-related brain network reorganization and its potential association with general cognitive performance during healthy aging.

Evaluation of Transient Ischemic Dilation (TID) Ratio in Gated SPECT Myocardial Perfusion Imaging (MPI) with Pharmacological Stress Agents

Objectives: Transient ischemic dilation (TID) refers to an apparent increase in the size of the left ventricular cavity on stress myocardial perfusion imaging compared to rest imaging. This study was performed to correlate the value of TID ratio in gated SPECT MPI in Coronary Artery Disease (CAD).&#x0D; Patients &amp; Methods: Seventy-four suspected or known CAD patients underwent MPI performed with Tc-99m sestamibi. Single day stress - rest protocol with pharmacological stress was followed, according to established practicing protocol of NINMAS. A statistical analysis was carried out by using the Statistical Package for Social Sciences version 20.0 for Windows (SPSS Inc., Chicago, Illinois, USA). Student t-test was used for continuous variables. Chi-square test used to compare categorical data. P values &lt;0.05 was considered as statistically significant.&#x0D; Results: Among 74 patients, 63(85.1%) were male and 11(14.9%) were female. The mean age found to be 53.8±10.5 years. Majority (90.5%) patients had hypertension, 45(60.8%) had diabetic mellitus and 39(52.7%) had dyslipidemia in blood lipid profile, 44(59.5%) were past smoker. The mean ejection fraction was 44.6±14.6 percent. The mean abnormal TID ratio was 1.25 ± 0.35 in patients having abnormal MPI findings and 1.03±0.21 in having normal MPI findings. The difference was statistically significant (p&lt;0.05) between two groups. It was also observed that in three cases having normal MPI had high TID ratio.Among the patients with TID ratio &gt;1.19, 24(64.9%) patients were in MVD group and 13(92.9%) were in SVD group. Whereas among the patients with TID ratio&lt;1.19, 13(35.1%) were in MVD group and 1(7.1%) were in SVD group. The difference was statistically significant (P&lt;0.05) between two groups. The mean TID ratio was 1.08±0.21 in single vessel disease and 1.24±0.26 in multiple vessel disease. The difference was also statistically significant (p&lt;0.05) between two groups.&#x0D; Conclusion: This study suggests that the TID ratios could provide incremental diagnostic information to standard myocardial perfusion analysis for the identification of severe and extensive disease in patients with suspected or known CAD.&#x0D; Bangladesh J. Nuclear Med. 21(2): 77-80, July 2018

Relationship between epicardial adipose tissue and coronary vascular function in patients with suspected coronary artery disease and normal myocardial perfusion imaging.

We evaluated the relationship between epicardial adipose tissue (EAT) and coronary vascular function assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) in patients with suspected coronary artery disease (CAD). The study population included 270 patients with suspected CAD and normal myocardial perfusion at stress-rest 82Rb PET/CT. Coronary artery calcium (CAC) score and EAT volume were measured. Absolute myocardial blood flow (MBF) was computed in mL/min/ from the dynamic rest and stress imaging. Myocardial perfusion reserve (MPR) was defined as the ratio of hyperaemic to baseline MBF and it was considered reduced when <2. MPR was normal in 177 (65%) patients and reduced in 93 (35%). Patients with impaired MPR were older (P < 0.001) and had higher CAC score values (P = 0.033), EAT thickness (P = 0.009), and EAT volume (P < 0.001). At univariable logistic regression analysis, age, heart rate reserve (HRR), CAC score, EAT thickness, and EAT volume resulted significant predictors of reduced MPR, but only age (P = 0.002), HRR (P = 0.021), and EAT volume (P = 0.043) were independently associated with reduced MPR, at multivariable analysis. In patients with CAC score 0 (n = 114), a significant relation between EAT volume and MPR (P = 0.014) was observed, while the relationship was not significant (P = 0.21) in patients with CAC score >0 (n = 156). In patients with suspected CAD and normal myocardial perfusion, EAT volume predicts hyperaemic MBF and reduced MPR, confirming that visceral pericardium fat may influence coronary vascular function. Thus, EAT evaluation has a potential role in the early identification of coronary vascular dysfunction.

Non-invasive CT-derived fractional flow reserve and static rest and stress CT myocardial perfusion imaging for detection of haemodynamically significant coronary stenosis

Computed tomography derived fractional flow reserve (FFRCT) and computed tomography stress myocardial perfusion imaging (CTP) are techniques to assess haemodynamic significance of coronary stenosis. To compare the diagnostic performance of FFRCT and static rest/stress CTP in detecting fractional flow reserve (FFR) defined haemodynamically-significant stenosis (FFR ≤ 0.8). Fifty-one patients (96 vessels) with suspected coronary artery disease from a single institution planned for elective invasive-angiography prospectively underwent research indicated 320-detector-CT-coronary-angiography (CTA) and adenosine-stress CTP and invasive FFR. Analyses were performed in separate core-laboratories for FFRCT and CTP blinded to FFR results. Myocardial perfusion was assessed visually and semi-quantitatively by transmural perfusion ratio (TPR). Invasive FFR ≤ 0.8 was present in 33% of vessels and 49% of patients. FFRCT, visual CTP and TPR analysis was feasible in 96%, 92% and 92% of patients respectively. Overall per-vessel sensitivity, specificity and diagnostic accuracy for FFRCT were 81%, 85%, 84%, for visual CTP were 50%, 89%, 75% and for TPR were 69%, 48%, 56% respectively. Receiver-operating-characteristics curve analysis demonstrated larger per vessel area-under-curve (AUC) for FFRCT (0.89) compared with visual CTP (0.70; p < 0.001), TPR (0.58; p < 0.001) and CTA (0.70; p = 0.0007); AUC for CTA + FFRCT (0.91) was higher than CTA + visual CTP (0.77, p = 0.008) and CTA + TPR (0.74, p < 0.001). Per-patient AUC for FFRCT (0.90) was higher than visual CTP (0.69; p = 0.0016), TPR (0.56; p < 0.0001) and CTA (0.68; p = 0.001). Based on this selected cohort of patients FFRCT is superior to visually and semi-quantitatively assessed static rest/stress CTP in detecting haemodynamically-significant coronary stenosis as determined on invasive FFR.

Transdiagnostic modulation of brain networks by electroconvulsive therapy in schizophrenia and major depression

Major depressive disorder (MDD) and schizophrenia (SCZ) share neurobiological and clinical commonalities. Altered functional connectivity of large-scale brain networks has been associated with both disorders. Electroconvulsive therapy (ECT) has proven to be an effective treatment in severe forms of MDD and SCZ. However, the role of ECT on the modulation of the dynamics of brain networks is still unknown. In this study, we used resting state functional magnetic resonance imaging (rs-fMRI) to investigate functional connectivity in 16 pharmacoresistant patients with SCZ or MDD and a matched group of normal controls. Patients were scanned before and after right-sided unilateral ECT. Group spatial independent component analysis was carried out with a multiple analysis of covariance (MANCOVA) approach to estimate the effects of ECT treatment on intrinsic components (INs). Functional network connectivity (FNC) was calculated between pairs of INs. Patients had reduced connectivity within a striato-thalamic network in the thalamus as well as increased low frequency oscillations in a striatal network. ECT reduced low frequency oscillations (LFOs) on a striatal network along with increasing functional connectivity in the medial prefrontal cortex within the DMN. Following ECT treatment, the FNC of the executive network was reduced with the DMN and increased with the salience network, respectively.Our findings suggest transnosological effects of ECT on the connectivity of large-scale networks as well as at the level of their interplay. Furthermore, they support a transnosological approach for the investigation not only of the neural correlates of the disease but also of the brain mechanism of treatment of mental disorders.

Quantitative low-dose rest and stress CT myocardial perfusion imaging with a whole-heart coverage scanner improves functional assessment of coronary artery disease

ObjectiveWe evaluated the diagnostic accuracy of myocardial blood flow (MBF) and perfusion reserve (MPR) measured from low-dose dynamic contrast-enhanced (DCE) imaging with a whole-heart coverage CT scanner for detecting functionally significant coronary artery disease (CAD). MethodsTwenty one patients with suspected or known CAD had rest and dipyridamole stress MBF measurements with CT and SPECT myocardial perfusion imaging (MPI), and lumen narrowing assessment with coronary angiography (catheter and/or CT based) within 6 weeks. SPECT MBF measurements and coronary angiography were used together as reference to determine the functional significance of coronary artery stenosis. In each CT MPI study, DCE images of the whole heart were acquired with breath-hold using a low-dose acquisition protocol to generate MBF maps. Binomial logistic regression analysis was used to determine the diagnostic accuracy of CT-measured MBF and MPR (ratio of stress to rest MBF) for assessing functionally significant coronary stenosis. ResultsMean stress MBF and MPR in ischemic segments were lower than those in non-ischemic segments (1.37 ± 0.34 vs. 2.14 ± 0.64 ml/min/g; 1.56 ± 0.41 vs. 2.53 ± 0.70; p < 0.05 for all). The receiver operating characteristic curve analysis revealed that MPR (AUC 0.916, 95%CI: 0.885–0.947) had a superior power than stress MBF (AUC 0.869, 95%CI: 0.830–0.909) for differentiating non-ischemic and ischemic myocardial segments (p = 0.045). On a per-vessel and per-segment analysis, concomitant use of MPR and stress MBF thresholds further improved the diagnostic accuracy compared to MPR or stress MBF alone for detecting obstructive coronary lesions (per-vessel: 93.4% vs. 83.6% and 88.5%, respectively; per-segment: 90.0% vs. 83.7% and 83.1%, respectively). The estimated effective dose of a rest and stress CT MPI study was 3.04 and 3.19 mSv respectively. ConclusionQuantitative rest and stress myocardial perfusion measurement with a large-coverage CT scanner improves the diagnostic accuracy for detecting functionally significant coronary stenosis.