Rest Of Image Research Articles

Patterns and trends of population radiation exposure and projected the risk of exposure-induced death from gamma camera examinations in Yazd Province

IntroductionThe use of nuclear medicine examinations as imaging modalities has recently increased. This study aimed to assess the radiation dose delivered to patients from common diagnostic nuclear medicine examinations and estimate the risk of exposure-induced death (REID). In addition, the frequency of nuclear medicine procedures were evaluated from 2015-2018. Materials and MethodsThe data were collected from adult patients who had undergone cardiac, skeletal, renal, lacrimal, and thyroid imaging. For each patient, the effective dose was calculated using dose conversion factors, and REID was estimated using PCXMC. The frequency of examinations between 2015 and 2018 was obtained from the hospital information system (HIS). ResultsThe highest estimated effective dose was attributed to the scans of myocardial stress (8.09 ± 1.28 mSv), myocardial rest (5.59 ± 1.27 mSv), and thyroid imaging (3.93 ± 0.55 mSv). In addition, cardiac stress examination had the highest REID values for solid cancers (212.5 ± 67.5) and bone scans had the highest REID values for leukemia (11.5 ± 2.5). A large increase in the number of myocardial perfusion scans was a significant contributor to an increase in collective effective dose from 23.37 man-Sv in 2015 to 49.47 man-Sv in 2018, a compound annual growth rate (CAGR) of 26%. ConclusionAlthough the annual frequency and per capita effective dose of nuclear medicine procedures in Yazd Province increased continuously, they were comparably lower than those reported for other countries. Despite this, the cancer risks of nuclear medicine scans at the individual level are negligible (around 0.01% excess fatal cancer risk), yet the increasing tendency for these examinations could be of concern.

Aberrantly higher functional connectivity in the salience network is associated with transient global amnesia

Triple intrinsic brain networks including the salience network (SN), default mode network (DMN), and central executive network (CEN), are known to be important in human cognition. Therefore, investigating those intrinsic brain networks in transient global amnesia (TGA) may offer novel insight useful for the pathophysiology of TGA. Fifty TGA patients underwent the resting state functional magnetic resonance imaging (rsfMRI) within 24 h, at 72 h, and 3 months after TGA onset. Twenty-five age, gender matched controls also underwent rsfMRI. Within 24 h of TGA onset, TGA patients showed greater functional connectivity in the SN and lower functional connectivity in the DMN, while relatively preserved functional connectivity was observed in the CEN. Interestingly, TGA patients continued to show decreased connectivity in the DMN, while no alterations were shown in the SN 72 h after illness onset. Three months after TGA onset, alterations of functional connectivity in the SN or the DMN were normalized. Our findings suggest that TGA is associated with transient greater functional connectivity in the SN and lower connectivity in the DMN.

Hippocampal Connectivity with Retrosplenial Cortex is Linked to Neocortical Tau Accumulation and Memory Function.

The mechanisms underlying accumulation of Alzheimer's disease (AD)-related tau pathology outside of the medial temporal lobe (MTL) in older adults are unknown but crucial to understanding cognitive decline. A growing body of evidence from human and animal studies strongly implicates neural connectivity in the propagation of tau in humans, but the pathways of neocortical tau spread and its consequences for cognitive function are not well understood. Using resting state functional magnetic resonance imaging (fMRI) and tau PET imaging from a sample of 97 male and female cognitively normal older adults, we examined MTL structures involved in medial parietal tau accumulation and associations with memory function. Functional connectivity between hippocampus (HC) and retrosplenial cortex (RsC), a key region of the medial parietal lobe, was associated with tau in medial parietal lobe. By contrast, connectivity between entorhinal cortex (EC) and RsC did not correlate with medial parietal lobe tau. Further, greater hippocampal-retrosplenial (HC-RsC) connectivity was associated with a stronger correlation between MTL and medial parietal lobe tau. Finally, an interaction between connectivity strength and medial parietal tau was associated with episodic memory performance, particularly in the visuospatial domain. This pattern of tau accumulation thus appears to reflect pathways of neural connectivity, and propagation of tau from EC to medial parietal lobe via the HC may represent a critical process in the evolution of cognitive dysfunction in aging and AD.SIGNIFICANCE STATEMENT The accumulation of tau pathology in the neocortex is a fundamental process underlying Alzheimer's disease (AD). Here, we use functional connectivity in cognitively normal older adults to track the accumulation of tau in the medial parietal lobe, a key region for memory processing that is affected early in the progression of AD. We show that the strength of connectivity between the hippocampus (HC) and retrosplenial cortex (RsC) is related to medial parietal tau burden, and that these tau and connectivity measures interact to associate with episodic memory performance. These findings establish the HC as the origin of medial parietal tau and implicate tau pathology in this region as a crucial marker of the beginnings of AD.

Behavioral and neural correlates of social network size: The unique and common contributions of face recognition and extraversion.

Humans are inherently social creatures and can gain advantages from larger network size. Researches have shown that different cognitive and personality factors may result in individual differences of social network size (SNS). Here, we focused on whether face recognition ability and extraversion were related to SNS and the neural basis underlying the relations. Behaviorally, we adopted the face-inversion task, NEO personality inventory, and computerized SNS test to explore the relationships between face recognition, extraversion, and SNS. Neurally, we used resting state functional magnetic resonance imaging and fractional amplitude of low-frequency fluctuation (fALFF) analysis method to investigate the neural correlates of SNS and then revealed whether face recognition and extraversion were related to SNS relevant brain regions. We found that individuals with better face recognition ability and more extraverted personality had larger size of social network. In addition, we found that SNS was positively associated with the fALFF in the ventromedial prefrontal cortex (vmPFC), right superior temporal sulcus, and precuneus. Interestingly, the fALFF in the vmPFC significantly correlated with face recognition ability. Our study suggests that both face recognition and extraversion may be important correlates of SNS, and the underlying spontaneous neural substrates are partially dissociable.

Relation between myocardial blood flow and cardiac events in diabetic patients with suspected coronary artery disease and normal myocardial perfusion imaging

BackgroundWe assessed the prognostic value of structural abnormalities and coronary vasodilator function in diabetic patients referred to a PET/CT for suspected coronary artery disease (CAD). MethodsWe studied 451 diabetics and 451 nondiabetics without overt CAD and normal myocardial perfusion. Myocardial blood flow (MBF) was computed from the dynamic rest and stress imaging. Myocardial flow reserve (MFR) was defined as ratio of hyperemic to baseline MBF and was considered reduced when < 2. ResultsDuring a mean follow-up of 44 months 33 events occurred. Annualized event rate (AER) was higher in diabetic than nondiabetic patients (1.4% vs 0.3%, P < .001). Diabetic patients with reduced MFR had higher AER compared to those with preserved MFR (3.3% vs 0.4%, P < .001). At Cox analysis, age, BMI and reduced MFR were independent predictors of events in diabetic patients. Patients with diabetes and reduced MFR had lower event-free survival compared to nondiabetic patients and MFR < 2 (P < .001). Event-free survival was similar in patients with diabetes and normal MFR and those without diabetes and reduced MFR. ConclusionsDiabetic patients with reduced MFR had higher AER and lower event-free survival compared to those with preserved MFR and to nondiabetic patients.

Measuring SPECT myocardial blood flow at the University of Ottawa Heart Institute

The introduction of new cardiac SPECT cameras has made it practical to do dynamic SPECT imaging and opened the door to performing myocardial blood flow (MBF) imaging with SPECT. In this paper, we describe in detail our approach to dynamic SPECT MBF imaging using a multi-pinhole cardiac SPECT camera and commercially available kinetic analysis software. We use a 1-day rest/stress protocol with 370 MBq injected at rest and 1,000 MBq at stress with a 1- to 2-hour interval between rest and stress imaging. The tracer is injected mechanically over 30 seconds using a syringe pump. Projection data are acquired in listmode for a duration of 11 minutes and then reframed into a dynamic series. Each image is reconstructed independently using vendor-supplied software. The dynamic images are corrected for residual activity and manually corrected for motion using rigid-body translation. The uptake rate constant, K1, is calculated using a 1-tissue-compartment kinetic model and converted to MBF using a previously determined extraction fraction correction.

Increased right ventricular uptake on (99m Tc)-sestamibi SPECT myocardial perfusion imaging as a marker of elevated pulmonary artery systolic pressure measured by Doppler echocardiography

Abstract Funding Acknowledgements Type of funding sources: None. Background Though prior work has been done, the significance of the not uncommon finding of increased right ventricular (RV) tracer uptake in patients undergoing (99m Tc)-sestamibi SPECT myocardial perfusion imaging remains poorly defined and this finding not been systemically integrated into the interpretation of the study, despite likely carrying both diagnostic and prognostic relevance for the patient. Purpose To examine if the presence of increased RV tracer uptake in patients undergoing myocardial perfusion imaging with same-day protocol (99m Tc)-sestamibi SPECT is associated with a higher pulmonary artery systolic pressure (PASP) measured non-invasively with transthoracic Doppler echocardiography Methods Patients who underwent myocardial perfusion imaging with same-day protocol (99m Tc)-sestamibi SPECT at a single academic health system between 2017-2020 were retrospectively enrolled. Those patients who had a transthoracic echocardiogram performed within 60 days of the nuclear study with sufficient Doppler data to estimate pulmonary artery systolic pressure(PASP) using the tricuspid regurgitation peak velocity method were included. A right atrial pressure of either 3 mmHg, 8 mmHg, or 15 mmHg was used in the calculation of PASP in keeping with the 2015 American Society of Echocardiography guidelines. The rest images for each nuclear study were reviewed and analyzed for the presence of RV tracer uptake. RV uptake was graded as either 0 or "no RV uptake", 1+ or "partial RV uptake", or 2+ or "complete RV uptake". The nuclear studies were grouped accordingly and the mean PASP for each group was computed. The mean PASP was also computed for a combined group of patients who demonstrated either 1+ or 2+ RV uptake. Statistical analysis using a t-test was performed to compare the mean PASP of each patient group. Results 193 patients were included in the analysis. Of those, 123(63%) demonstrated "no RV uptake", 58(31%) demonstrated 1+ or "partial RV uptake", and 12(6%) demonstrated 2+ or "complete RV uptake". 70 patients(36%) had either 1+ or 2 + RV uptake. The mean PASP was 27.2 ± 7 mmHg for the "no RV uptake" group, 28.3 ± 9 mmHg for the 1+ RV uptake group and 41. 6 ± 14 mmHg for the 2+ RV uptake group. When combined, patients demonstrating 1+ or 2+ RV uptake had a mean PASP of 30.6 ± 11 mmHg. There was no statistical difference in the mean PASP of the "no RV uptake" group and the 1+ or "partial RV uptake group" (p = 0.434). The difference in mean PASP between the "no RV uptake" group and the combined 1+ or 2+ RV uptake group was statistically significant(p = 0.028). Conclusion In a small single health system sample, patients undergoing (99m Tc)-sestamibi SPECT myocardial perfusion imaging who have either partial or complete RV uptake on rest images have an increased pulmonary artery systolic pressure compared to patients who do not exhibit this finding.

Entropy-based myocardial blood flow measurements using PET: a way to improve reproducibility

Abstract Funding Acknowledgements Type of funding sources: None. Background and purpose Myocardial blood flow (MBF) measurements using PET are increasingly used to guide the management of patients with (suspected) coronary artery disease (CAD). Day-to-day variability of these measurements is poor with a 21% standard deviation or 40% 95%-confidence interval [Reference: JACC Cardiovasc Imaging, 2017;10(5):565]. This limits clinical applicability in diagnosis, risk stratification and follow-up as these all depend on comparison of flow values with fixed cut-off values. We expect that reproducibility can be improved by combining flow measurements with the variation of flow values within the myocardium. As entropy is a measure of variability of the associated distribution, we compared the reproducibility of an entropy-based flow parameter with that of conventional myocardial flow reserve (MFR) measurements. Methods We performed a study using intra-individual comparison in 24 patients who underwent rest and regadenoson-induced stress myocardial perfusion imaging using Rubidium-82 on two different PET systems (PET1: Discovery 690, GE Healthcare, and PET2: Vereos, Philips Healthcare) within 3 weeks. MBF for both rest and stress was calculated using Lortie’s one-tissue compartment model (Corridor4DM, INVIA). MFR (ratio of MBF stress/rest) was determined for the myocardial as a whole (MFRglobal), for the three vascular territories: LAD, LCX and RCA (MFRregional) and for the 17 segments. Next, we calculated Shannon’s entropy to measure the variation of the 17 MFR segmental values. We multiplied Shannon’s entropy by the mean of the MFR segmental values resulting in an entropy-based MFR (MFRentropy). For each patient MFRglobal, MFRregional and MRFentropy were compared between both PET systems. For each of the three parameters the test-retest precision was calculated as the SD of the relative difference between measurements. Results The mean difference in MFR measurements between both cameras did not differ from zero (p &amp;gt; 0.05). Mean values for PET1 were MFRglobal = 2.4, MFRregional = 2.4 (LAD), 2.4 (LCX) and 2.5 (RCA), and MFRentropy = 2.4. For PET2 we found MFRglobal = 2.5, MFRregional = 2.5 (LAD), 2.4 (LCX) and 2.6 (RCA), and MFRentropy = 2.5. Test-retest precision was lower for MFRentropy with 11% compared to that of MFRglobal (21%), MFRregional LAD (22%), MFRregional LCX (23%) and MFRregional RCA (24%) (p &amp;lt; 0.01). Conclusion The reproducibility of myocardial flow reserve measurements using Rubidium-82 PET improved by a factor of 2 when an entropy-based flow parameter instead of global or regional MFR parameters is used. This entropy-based flow-parameter may be used to better discriminate ischemia from non-ischemia and may therefore improve CAD management.

Implications of transient ischaemic dilatation and impaired left ventricular ejection fraction reserve in patients with normal stress myocardial perfusion imaging and elevated coronary artery calcium

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Stress only (SO) instead of stress/rest single photon emission computed tomography myocardial perfusion imaging (MPI) is encouraged if perfusion and left ventricular ejection fraction (LVEF) are normal on SO images. Concurrent coronary artery calcium (CAC) scoring has also been recommended to assess atherosclerotic burden in ‘normal’ MPIs. However, the safety of SO MPI in high CAC cases is unclear as additional rest imaging may show transient ischaemic dilation (TID) and/or impaired LVEF reserve (iLVEFr) which are markers of severe coronary artery disease (CAD) and indicate ‘balanced ischaemia’. Purpose We aim to assess the incidence and outcomes of TID and iLVEFr in stress/rest MPIs with normal SO images and elevated CAC. Methods Retrospective analysis of all normal stress/rest MPIs performed between 1 March 2016 to 31 January 2017 with concurrently measured CAC &amp;gt;300. A SO protocol was not in place then. Prone post stress images were routinely done. Known CAD cases were excluded. A reader reviewed only the post stress supine/prone images and excluded cases ineligible for SO MPI (non-homogenous perfusion, LVEF ≤50%, abnormal wall motion). The remaining cases were assessed for TID (software derived TID ratio &amp;gt;1.20) and iLVEFr (stress LVEF – rest LVEF ≤-5%). Coronary angiography (CAG) and major adverse cardiac events (MACE, defined as cardiac death, non fatal myocardial infarction, revascularisation) within 24 months post MPI were traced using electronic medical records. Results There were 230 cases included (mean age 71, 56.5% male) of which 43 (18.7%) had TID and/or iLVEFr (9 TID, 22 iLVEFr, 12 both). There were no significant differences in baseline characteristics, CAC and aspirin/statin use between cases with or without TID and/or iLVEFr (Table 1). More patients in the TID and/or iLVEFr group underwent elective CAG [10 (23.3%) vs 10 (5.3%), p = 0.001] although CAG diagnosis of severe CAD (left main, 3-vessel or 2-vessel disease with proximal left anterior descending involvement) was not different [4/6 (40.0%) vs 5/10 (50.0%), p = 1.000). MACE was significantly higher in the TID and/or iLVEFr group [10 (23.3%) vs 16 (8.6%), p = 0.013], driven by higher elective revascularisation [8 (18.6%) vs 8 (4.3%), p = 0.003] with no significant differences in cardiac death or non fatal myocardial infarction (Table 2). Conclusion TID and/or iLVEFr is seen in &amp;lt;20% of cases eligible for SO MPI with high CAC, suggesting that routine rest scan in these cases exposes the majority to unnecessary radiation. Identification of TID and/or iLVEFr is associated with higher 24 month MACE, driven by higher elective revascularisation from more CAG referral. Approximately half of cases in each group had revascularisation for non severe CAD not typically associated with TID and/or impaired LVEFr. Overall cardiac death and non fatal myocardial infarction rates were low and not significantly different between groups with or without TID and/or iLVEFr.

Decreased Functional Connectivity of Vermis-Ventral Prefrontal Cortex in Bipolar Disorder.

Objectives: To investigate changes in functional connectivity between the vermis and cerebral regions in the resting state among subjects with bipolar disorder (BD).Methods: Thirty participants with BD and 28 healthy controls (HC) underwent the resting state functional magnetic resonance imaging (fMRI). Resting-state functional connectivity (rsFC) of the anterior and posterior vermis was examined. For each participant, rsFC maps of the anterior and posterior vermis were computed and compared across the two groups.Results: rsFC between the whole vermis and ventral prefrontal cortex (VPFC) was significantly lower in the BD groups compared to the HC group, and rsFC between the anterior vermis and the middle cingulate cortex was likewise significantly decreased in the BD group.Limitations: 83.3% of the BD participants were taking medication at the time of the study. Our findings may in part be attributed to treatment differences because we did not examine the effects of medication on rsFC. Further, the mixed BD subtypes in our current study may have confounding effects influencing the results.Conclusions: These rsFC differences of vermis-VPFC between groups may contribute to the BD mood regulation.

Distance disintegration characterizes node-level topological dysfunctions in cocaine addiction.

Previous investigations have used global graph theory measures in order to disentangle the complexity of the neural reorganizations occurring in cocaine use disorder (CUD). However, how these global topological alterations map into individual brain network areas remains unknown. In this study, we used resting state functional magnetic resonance imaging (fMRI) data to investigate node-level topological dysfunctions in CUD. The sample was composed of 32 individuals with CUD and 32 healthy controls, matched in age, years of education and intellectual functioning. Graph theory measures of optimal connectivity distance, node strength, nodal efficiency and clustering coefficient were estimated in each participant using voxel-wise functional connectivity connectomes. CUD individuals as compared with healthy controls showed higher optimal connectivity distances in ventral striatum, insula, cerebellum, temporal cortex, lateral orbitofrontal cortex, middle frontal cortex and left hippocampus. Furthermore, clinical measures quantifying severity of dependence were positively related with optimal connectivity distances in the right rolandic operculum and the right lateral orbitofrontal cortex, whereas length of abstinence was negatively associated with optimal connectivity distances in the right temporal pole and the left insula. Our results reveal a topological distancing of cognitive and affective related areas in addiction, suggesting an overall reduction in the communication capacity of these regions.

Routine Stress-Rest Tc-99m MIBI Myocardial Perfusion Scintigraphy Underestimates Ischemia and Viability

Objective: The study included patients with known or suspected coronary artery disease. It aimed to demonstrate the incremental value of the routine nitrate augmentation in stress-rest technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) myocardial perfusion scintigraphy (MPS). Material and Methods: Standard stress and rest MPS was performed, followed by a second rest study with isosorbide dinitrate intervention within 5 days. The redistribution of Tc-99m MIBI was compared between stress and rest images, and interpretation of the study done as normal, scarred, and ischemia ± mixed lesion groups. The rest studies were compared with the rest nitrate studies. Summed rest score (SRS) and summed rest nitrate score (SRNS) were calculated. The summed difference score (SDS) of SRS and SRNS was calculated for each group. Results: A total of 50 patients were included in the study. Based on the routine MPS, patients were divided into the scar (n = 20), ischemia (n = 18), and normal (n = 12) groups. After the administration of nitrate, a significant fall in the blood pressure ( P &lt; .001) and an increase in the heart rate ( P &lt; .001) were noted. SDS was not significant in the normal MPS group (0.17 ± 0.57, P = .19). In comparison, substantial SDS was found in the ischemia ± mixed lesion (4.33 ± 3.43) and scarred (3.5 ± 3.15), respectively (both P &lt; .001). Percentage improvement in the SRS from SRNS was found less than 2% for normal MPS while 18% and 29% for scarred and mixed groups, respectively. Conclusion: Routine MPS (stress followed by rest) underestimate ischemia and viability, which can be significantly reduced by utilizing nitrate augmentation in all patients with abnormal stress MPS. This could lead to a significant change in the extent and severity of ischemia and viability.

Resilience to acute musculoskeletal pain: resting-state functional connectivity of regions associated with gray matter density differences following induction of low-back pain

Musculoskeletal pain is an aversive experience that exists within a variety of conditions and can result in significant impairment for individuals. Gaining greater understanding of the factors related to pain vulnerability and resilience to musculoskeletal pain may help target at-risk individuals for early intervention. This analysis builds on our previous work identifying regions where lower gray matter density (GMD) was associated with individuals who report pain following standardized, exercise induced musculoskeletal injury. Here we sought to examine the relationship between baseline resting state functional connectivity (rsFC) in a priori regions and networks, and delayed onset muscle soreness (DOMS) pain intensity following a single session of eccentric exercise. The present study is a secondary analysis from a portion of a larger, blinded, randomized experimental trial. All participants were healthy adults between the ages of 18 and 40 years recruited from the university and surrounding community. The primary outcome measure was functional connectivity assessed by using T2 rest image. Participants completed a baseline functional MRI scan and a high intensity trunk exercise protocol to induce DOMS in the erector spinae. Pain intensity ratings were collected 48-hours later. rsFC from four seed regions and three networks were separately regressed on pain intensity scores. Our results revealed that connectivity between left middle frontal gyrus, the left occipital gyrus and cerebellar network seeds and clusters associated with discriminative, emotional, and cognitive aspects of pain were associated with lower post-DOMS pain. Our results provide key support for the role of structural and functional coherence in regional and network connectivity in adaptive pain response and represent an important step in clarifying neural mechanisms of resilience to clinically relevant pain. Resilience to clinically relevant pain is associated with aspects of regional and network neural coherence. Investigations of pain modulatory capacity that integrate multimodal neuroimaging metrics are called for. R01AT006334, PI Dr. Mark Bishop.

Contributions From Resting State Functional Connectivity and Familial Risk to Early Adolescent-Onset MDD: Results From the Adolescent Brain Cognitive Development Study

Abstract Background Family history of Major Depressive Disorder (MDD) is a robust predictor of MDD onset, especially in early adolescence. We examined the relationships between familial risk for depression and alterations to resting state functional connectivity (rsFC) within the default mode network (wDMN) and between the DMN and the left/right hippocampus (DMN-LHIPP/DMN-RHIPP) to the risk for early adolescent MDD onset. Methods We examined 9403 youth aged nine to eleven from the Adolescent Brain Cognitive Development study. Depressive symptoms were measured with the parent-reported Child Behavior Checklist. Both youth and their parents completed the Kiddie Schedule for Affective Disorders and Schizophrenia, which provided MDD diagnoses. A family history screen was administered to determine familial risk for depression. Youth underwent a resting state functional magnetic resonance imaging scan, providing us with rsFC data. Results Negative wDMN rsFC was associated with child-reported current depression, both child- and parent-reported past depression, and parent-reported current depressive symptoms. No difference was found in wDMN, DMN-LHIPP or DMN-RHIPP rsFC in children with or without familial risk for depression. Familial risk for depression interacted with wDMN rsFC in association with child-reported past MDD diagnosis and parent-reported current depressive symptoms. Limitations Information such as length of depressive episodes and age of onset of depression was not collected. Conclusions Altered wDMN rsFC in youth at familial risk for depression may be associated with increased risk for MDD onset in adolescence, but longitudinal studies are needed to test this hypothesis.

Assessment Relation of Myocardial Detector Counts and Administered Activity of 99mTc-SestaMIBI in MPI: The Effects of Body Weight, BMI, and Gender.

In myocardial perfusion imaging, reducing the number of photons in images of obese patients causes poor image quality. To solve this problem, we need to inject the tracer according to the patients' weight. Therefore, this study aimed to investigate the relationship between myocardial photon counts with patients' weight, BMI, and gender. A total of 129 patients underwent myocardial perfusion imaging in a twoday stress-first protocol, but only rest images were included in this study. Multiplication factor <img src="/images/article-115470.png" /> was used to determine the amount of radiopharmaceutical activity injected into the patients. For evaluating the effect of gender, the photon counts of 22 female patients were also assessed when the breast tissue was pulled upward (Breast Up). The total myocardial detector counts in the raw images were calculated from the summation of 32 projections. A multiple linear regression test was used to simultaneously examine the effects of weight, BMI, and gender on photon counts. There was no significant relationship between photon counts and patients' weight (p=0.129) and BMI (0.406), but gender had significant effects on photon counts, and myocardial detector counts were found to be higher in males (p=0.00). There was a statistically significant difference between the images of Breast Up and Non-Breast Up, and myocardial detector counts were higher in the Breast Up imaging method (p=0.00). Using the bodyweight formula, the image quality was comparable in obese and lean patients, but myocardial detector counts were lower in females, and this formula needs to be adjusted according to the patient's gender.

Contributions from resting state functional connectivity and familial risk to early adolescent-onset MDD: Results from the Adolescent Brain Cognitive Development study

BackgroundFamily history of Major Depressive Disorder (MDD) is a robust predictor of MDD onset, especially in early adolescence. We examined the relationships between familial risk for depression and alterations to resting state functional connectivity (rsFC) within the default mode network (wDMN) and between the DMN and the left/right hippocampus (DMN-LHIPP/DMN-RHIPP) to the risk for early adolescent MDD onset. MethodsWe examined 9403 youth aged nine to eleven from the Adolescent Brain Cognitive Development study. Depressive symptoms were measured with the parent-reported Child Behavior Checklist. Both youth and their parents completed the Kiddie Schedule for Affective Disorders and Schizophrenia, which provided MDD diagnoses. A family history screen was administered to determine familial risk for depression. Youth underwent a resting state functional magnetic resonance imaging scan, providing us with rsFC data. ResultsNegative wDMN rsFC was associated with child-reported current depression, both child- and parent-reported past depression, and parent-reported current depressive symptoms. No difference was found in wDMN, DMN-LHIPP or DMN-RHIPP rsFC in children with or without familial risk for depression. Familial risk for depression interacted with wDMN rsFC in association with child-reported past MDD diagnosis and parent-reported current depressive symptoms. LimitationsInformation such as length of depressive episodes and age of onset of depression was not collected. ConclusionsAltered wDMN rsFC in youth at familial risk for depression may be associated with increased risk for MDD onset in adolescence, but longitudinal studies are needed to test this hypothesis.

Molecular Mechanisms of Adenosine Stress T1 Mapping.

Adenosine stress T1 mapping is an emerging magnetic resonance imaging method to investigate coronary vascular function and myocardial ischemia without application of a contrast agent. Using gene-modified mice and 2 vasodilators, we elucidated and compared the mechanisms of adenosine myocardial perfusion imaging and adenosine T1 mapping. Wild-type (WT), A2AAR-/- (adenosine A2A receptor knockout), A2BAR-/- (adenosine A2B receptor knockout), A3AR-/- (adenosine A3 receptor knockout), and eNOS-/- (endothelial nitric oxide synthase knockout) mice underwent rest and stress perfusion magnetic resonance imaging (n=8) and T1 mapping (n=10) using either adenosine, regadenoson (a selective A2AAR agonist), or saline. Myocardial blood flow and T1 were computed from perfusion imaging and T1 mapping, respectively, at rest and stress to assess myocardial perfusion reserve and T1 reactivity (ΔT1). Changes in heart rate for each stress agent were also calculated. Two-way ANOVA was used to detect differences in each parameter between the different groups of mice. Myocardial perfusion reserve was significantly reduced only in A2AAR-/- compared to WT mice using adenosine (1.06±0.16 versus 2.03±0.52, P<0.05) and regadenoson (0.98±026 versus 2.13±0.75, P<0.05). In contrast, adenosine ΔT1 was reduced compared with WT mice (3.88±1.58) in both A2AAR-/- (1.63±1.32, P<0.05) and A2BAR-/- (1.55±1.35, P<0.05). Furthermore, adenosine ΔT1 was halved in eNOS-/- (1.76±1.46, P<0.05) versus WT mice. Regadenoson ΔT1 was approximately half of adenosine ΔT1 in WT mice (1.97±1.50, P<0.05), and additionally, it was significantly reduced in eNOS-/- mice (-0.22±1.46, P<0.05). Lastly, changes in heart rate was 2× greater using regadenoson versus adenosine in all groups except A2AAR-/-, where heart rate remained constant. The major findings are that (1) although adenosine myocardial perfusion reserve is mediated through the A2A receptor, adenosine ΔT1 is mediated through the A2A and A2B receptors, (2) adenosine myocardial perfusion reserve is endothelial independent while adenosine ΔT1 is partially endothelial dependent, and (3) ΔT1 mediated through the A2A receptor is endothelial dependent while ΔT1 mediated through the A2B receptor is endothelial independent.

A clinical decision support system for predicting cirrhosis stages via high frequency ultrasound images

Many visceral organs contain two important structures: capsule and parenchyma. As a non-invasive examination method, ultrasound is widely used. In this study, we develop a computational framework that consists of capsule localization and parenchyma assessment for disease diagnosis.Clinical decision support system helps providing standard, objective and timely diagnosis. However, although current cirrhosis diagnosis methods are mainly based on the images produced from medical imaging technique and experienced clinicians subjective analysis, many imaging techniques are invasive, and experienced clinicians are in short supply, especially in underdeveloped regions. The proposed system employs an incremental classification model for grading parenchyma patch stages in predicting cirrhosis stages from high frequency ultrasound images. The incremental classification model is based on auto-extracted membrane structures along with patch-ensemble model, using a severe-first strategy. The framework firstly applies multi-scale capsule extraction automatically. The lesions of the capsule and parenchyma show increasing changes in the first three stages. In the final stage, due to the liver ascites, partial lesions restore to normal. To handle the inconsecutive change, the proposed patch-ensemble model applies two layers. We firstly recognize images belong to the severe stage via capsule-specific CIFAR in the first layer. Parenchyma-aimed Resnet is then applied to classify rest images into rest stages. In each layer a data split and aggregation scheme is proposed to evaluate the cirrhosis stage for liver images.The experimental results demonstrate that the proposed method achieves high precision and effectiveness and can be effectively applied to the auxiliary diagnosis of cirrhosis. Some integral parts of the system are also available for visceral organs with similar structure.

Can deep learning identify normal coronary flow reserve from rubidium myocardial PET perfusion?

Abstract Funding Acknowledgements Type of funding sources: None. Background Impaired vasodilator function is an early manifestation of coronary artery disease (CAD) and may precede angiographic stenosis. Rest and stress myocardial blood flow (MBF) are calculated from dynamic imaging during rest/stress Rubidium (Rb) myocardial PET perfusion. Coronary flow reserve (CFR) equals stress divided by rest MBF. CFR is an independent predictor of cardiac mortality in patients with known or suspected CAD. We evaluated the prediction of CFR from analysis of stress/rest PET images by deep learning (DL) as compared with standard calculation of CFR using supervised learning applied methodology using within a commercial DL training platform. Methods 1036 patients (625 male, 411 female, mean age: 64.3 years old) were studied. Patients underwent Stress/rest Rb PET perfusion, and CFR calculated using MBF software by an expert user. Abnormal CFR was defined as &amp;lt;2.0. The left ventricle myocardium was segmented using standard software. DL was trained using polar distribution of normalized PET uptake at stress and rest, processed stress and rest images were cropped, the stress images were then subtracted from the rest images. DL was trained using 935 subtracted images and tested using the remaining 101 images. DL was trained with supervision to classify images. The image shows examples of subtracted abnormal cases (1a &amp; 1b). Results Using our supervised training methodology, the commercial MBF software platform reported 465 cases as abnormal, with 48 of these were included in the DL test set. The DL platform produced abnormal output classifiers for all the whole test set. DL accurately detected over 70% of abnormal cases. The commercial MBF software reported 571 cases as normal; with 50 of these contributing to the DL test set. DL was accurate in 48.0% of normal cases. Statistical results are shown in the table. Conclusion We have shown the proof of concept that DL algorithms trained with supervision can detect abnormal CFR. Our work shows that further work is needed to develop supervised learning methodology in order to improve accuracy for clinical use. Statistical Results Statistic Value Sensitivity 63.16% Specificity 56.67% + Predictive Value 48.00% - Predictive Value 70.83% Accuracy 59.18% Abstract Figure.

Optimal 99mTc activity ratio in the single-day stress-rest myocardial perfusion imaging protocol: A multi-SPECT phantom study

BackgroundThis investigation used image data generated by an anthropomorphic phantom to determine the minimal 99mTc rest-stress activity concentration ratio (R) able to minimize the ghosting effect in the single-day stress-first myocardial perfusion imaging, using different positions of the perfusion defect (PD), scanners and reconstruction protocols. MethodsA cardiac phantom with a simulated PD was imaged under different R using different gamma cameras and reconstruction algorithms. The residual activity from precedent stress administration was simulated by modeling effective half-times in each compartment of the phantom and assuming a delay of 3 hours between the stress and rest studies. The net contrast (NC) of the PD in the rest study was assessed for different R, PD positions and scanner/software combinations. The optimal R will be the one that minimize the NC in the rest images ResultsThe activity concentration ratio R, the position of the PD and the scanner/software combinations were all main effects with a statistically significant impact on the NC, in decreasing order of relevance. The NC diminished significantly only for R values up to 2. No further improvement was observed for NC for R values above 2 and up to 3. NC was significantly higher in anteroseptal than in posterolateral positions of the PD and higher for solid-state cameras. ConclusionsA rest-stress activity concentration ratio R of 2 in single-day stress-first myocardial perfusion imaging is enough to achieve the maximum net contrast in the PD. This ratio should be used to optimize patient’s radiation exposure.