Splenic switch-off in [15O]H2O-positron emission tomography myocardial perfusion imaging using parametric blood flow images.

BACKGROUND: Evaluation of sufficient adenosine response constitutes a significant challenge in myocardial perfusion imaging (MPI). Splenic switch-off in MPI studies denotes a visually (qualitatively) reduced splenic radiotracer signal during adenosine stress and is considered indicative of sufficient cardiac vasodilation. In this study, we examined semi-quantitative and quantitative approaches to splenic switch-off assessment using [15O]H2O-PET with either summed activity images or calculated parametric splenic blood flow images. METHODS: Cohort 1: 90 clinical patients undergoing [15O]H2O MPI in whom adenosine response was considered clinically adequate were identified to characterize the corresponding splenic switch-off. Spleen stress/rest-ratio (SSR-ratio) was calculated as spleen stress signal intensity/spleen rest signal intensity on both summed activity and parametric blood flow images. Cohort 2: Twenty-five patients with repeat MPI due to suspected insufficient adenosine response were identified to observe if splenic switch-off on the initial MPI could predict the outcome of the repeat MPI. Cohort 3: Fifty-four patients who were considered adenosine responders on MPI and who had a coronary angiogram (CAG) follow-up within 3 months after MPI served as a separate validation group. RESULTS: Splenic switch-off was present in most patients with a clinically sufficient adenosine response (Cohort 1), illustrated by both visual (74.4%-86.7%), semi-quantitative (summed activity images) (85.6%), and quantitative (parametric blood flow images) (92.2%) evaluation, which corresponds to the distribution in patients with sufficient adenosine response and follow-up CAG (Cohort 3). In patients suspected of insufficient adenosine response on the initial MPI (Cohort 2), the repeat MPI only yielded different myocardial blood flow (MBF) results if the initial SSR-ratio was >0.90 on splenic parametric blood flow images. CONCLUSION: quantitative splenic switch-off assessment on parametric blood flow images was superior to the semi-quantitative splenic switch-off approach. Patients with a suspected insufficient initial adenosine response and SSR-ratio >0.90 can benefit from a repeat MPI. Thus, the integration of quantitative splenic switch-off using parametric blood flow images in the evaluation of adenosine response may support future clinical decision-making.

Detection and correction of patient motion in dynamic 15O-water PET MPI.

BACKGROUND: Patient motion constitutes a limitation to 15O-water cardiac PET imaging. We examined the ability of image readers to detect and correct patient motion using simulated motion data and clinical patient scans. METHODS: Simulated data consisting of 16 motions applied to 10 motion-free scans were motion corrected using two approaches, pre-analysis and post-analysis for motion identification. Both approaches employed a manual frame-by-frame correction method. In addition, a clinical cohort was analyzed for assessment of prevalence and effect of motion and motion correction. RESULTS: Motion correction was performed on 94% (pre-analysis) and 64% (post-analysis) of the scans. Large motion artifacts were corrected in 91% (pre-analysis) and 74% (post-analysis) of scans. Artifacts in MBF were reduced in 56% (pre-analysis) and 58% (post-analysis) of the scans. The prevalence of motion in the clinical patient cohort (n = 762) was 10%. Motion correction altered exam interpretation in only 10 (1.3%) clinical patient exams. CONCLUSION: Frame-by-frame motion correction after visual inspection is useful in reducing motion artifacts in cardiac 15O-water PET. Reviewing the initial results (parametric images and polar maps) as part of the motion correction process, reduced erroneous corrections in motion-free scans. In a large clinical cohort, the impact of motion correction was limited to few patients.

Demographic and clinical characteristics of patients with low back pain in primary and secondary care settings in Southern Denmark.

OBJECTIVE: To describe and compare the demographic and clinical characteristics of patients with acute or chronic low back pain across all health care settings treating this condition.Design and setting: Concurrent prospective survey registration of all consecutive consultations regarding low back pain at general practitioners, chiropractors, physiotherapists, and the secondary care spine centre in Southern Denmark. SUBJECTS: Patients ≥16 years of age with low back pain. MAIN OUTCOME MEASURE: Demographic characteristics, symptoms, and clinical findings were registered and descriptively analysed. Pearson's chi-square tested differences between the populations in the four settings. Multiple logistic regression assessed the odds of consulting specific settings, and t-test assessed differences between patients attending for a first and later consultation. RESULTS: Thirty-six general practitioners, 44 chiropractors, 74 physiotherapists, and 35 secondary care Spine Centre personnel provided information on 5645 consultations, including 1462 first-visit consultations. The patients differed significantly across the settings. Patients at the Spine Centre had the most severe symptoms and signs and were most often on sick leave. Compared to the other populations, the chiropractor population was younger, whereas the physiotherapist population was older, more often females, and had prolonged symptoms. In general practice, first-time consultations were with milder cases while patients who attended for a second or later consultation had the worst symptoms, findings, and risk of sick leave compared to the other primary care settings. CONCLUSION: The demographic and clinical characteristics of patients with low back pain differ considerably across the health care settings treating them.KEY POINTSThe study describes the symptoms and clinical findings of patients with low back pain consulting the Danish health care system in all its settings.Patients with chiropractors were youngest, while those with physiotherapists were the oldest and most frequently female.First consultations in general practice were generally with the least symptomatic patients while those returning for a subsequent consultation had more severe disease including more sick leave compared to patients in the other primary care settings.Our findings call for caution when generalizing between health care settings for patients with low back pain.

Providing information at the initial consultation to patients with low back pain across general practice, chiropractic and physiotherapy - a cross-sectorial study of Danish primary care.

OBJECTIVE: Clinical guidelines for managing low back pain (LBP) emphasise patient information, patient education and physical activity as key components. Little is known about who actually receives information. This study investigates to what extent information at the first consultation with general practitioner (GP), chiropractor (DC) and physiotherapist (PT) in Danish primary care is provided to patients with LBP. DESIGN AND SETTING: This cross-sectorial study was conducted as a prospective survey registration of LBP consultations at the three primary health care professions in Denmark. INTERVENTION: Clinicians ticked off a paper survey chart during or after consultations with patients who visited the clinic for LBP (Approval number: ID # 11.220). SUBJECTS: 33 GPs, 43 DCs and 61 PTs registered first-time consultations. MAIN OUTCOME MEASURES: The primary outcome was provision of information, overall and across care settings. RESULTS: The overall proportion of patients provided with information was 72%, but this varied among professions (GP, 44%; DC, 76%; and PT, 74%). Provision of information increased to 78% if patients had increased emotional distress or back-related leg pain below the knee. The strongest association with provision of information was having two or three signs of elevated distress (OR 2.58 and 5.05, respectively, p= 0.00) or physical disability (OR 2.55, p= 0.00). CONCLUSION: In more than a quarter of first-time consultations, patient information was not provided. Large variation in providing information was found across the settings. The proportion provided with information increased for sub-populations having elevated distress or back-related leg pain below the knee.Key Points Clinical guidelines recommend patient information, patient education and physical activity for managing low back pain (LBP) • Information is not provided in more than a quarter of first-time consultations in Danish primary care settings that manage these patients. • Information increased for the sub-populations having elevated distress and back-related leg pain below the knee. • The conducted primary care surveys monitored clinical activity and illustrated variations in provision of information.

Moderators of treatment effect of non-steroidal anti-inflammatory drugs for patients with (sub) acute low back pain: Protocol for a systematic review with individual participant data meta-analysis.

A Cochrane review found that non-steroidal anti-inflammatory drugs (NSAIDs) are slightly more effective than placebo on acute and subacute low back pain (LBP) outcomes (pain intensity, disability, and global improvement). Our objectives are: (1) to assess the overall treatment effect of NSAIDs in adults with acute and subacute LBP; (2) to identify the moderation of baseline patients' characteristics on treatment effect. We will conduct a systematic search of RCTs on effectiveness of NSAIDs compared with placebo in adults with non-chronic LBP in Medline ALL, Embase, Cochrane Central Register of Controlled Trials*. We will screen the records after January 2020, and include eligible RCTs before January 2020 screened by the Cochrane review mentioned above. Our primary outcomes are pain intensity, disability, and health-related quality of life, secondary outcomes are adverse events. Our IPD dataset will consist of the information on each eligible trial characteristics and included variables according to a predefined coding scheme. We will assess risk-of-bias of included RCTs with the Cochrane Risk Of Bias (RoB)-2 assessment tool. We will perform power calculations with closed-form solutions and prioritize a one-stage approach for IPD-MA. For reporting the results, we will adhere to the PRISMA-IPD statement.

Guiding early revascularization using [15O]H2O positron emission tomography myocardial perfusion imaging: impact of atrial fibrillation.

AIMS: Myocardial perfusion imaging (MPI) using [15O]H2O positron emission tomography (PET) is used to guide the selection of patients with angina for invasive angiography and possible revascularization. Our study evaluated (i) whether atrial fibrillation (AF) reduces global hyperaemic myocardial blood flow (MBF) and (ii) whether [15O]H2O PET MPI effectively guides revascularization procedures for patients with ongoing AF. METHODS AND RESULTS: We prospectively recruited 346 patients with angina and persistent or paroxysmal AF referred for baseline/hyperaemic [15O]H2O PET MPI. The primary outcome was revascularization within 3 months of MPI. In the analyses, patients were divided into four groups based on whether they had ongoing AF or sinus rhythm (SR) and whether they had previously documented coronary artery disease (CAD) or not. Thus, four groups were compared: SR-noCAD, AF-noCAD, SR-CAD, and AF-CAD. Hyperaemic MBF was affected by both ongoing AF and prior CAD [MBF (mL/min/g): 2.82 (SR-noCAD) vs. 2.12 (AF-noCAD) vs. 2.22 (SR-CAD) vs. 1.80 (AF-CAD), two-way analysis of variance P < 0.0001]. In multiple linear regression, ongoing AF was independently associated with reduced hyperaemic MBF. Every 0.1 mL/min/g decrease in hyperaemic MBF was associated with a 23% increase in odds of early revascularization. Receiver operating characteristic (ROC) analysis of vessel-specific hyperaemic MBF to predict early revascularization yielded the following areas under the ROC curve: SR-noCAD: 0.95 (P < 0.0001); AF-noCAD: 0.79 (P < 0.0001); SR-CAD: 0.78 (P < 0.0001); and AF-CAD: 0.88 (P < 0.0001). CONCLUSION: Ongoing AF is associated with 19-25% reduced global hyperaemic MBF as measured by [15O]H2O MPI PET. Regardless, vessel-specific hyperaemic MBF still predicts early revascularization in patients with AF.

Exploring usual care for patients with low back pain in primary care: a cross-sectional study of general practitioners, physiotherapists and chiropractors.

OBJECTIVES: To explore the elements and composition of care provided by general practitioners (GPs), physiotherapists (PTs) and chiropractors (DCs) to patients with low back pain (LBP). DESIGN: Observational study. SETTING: Primary care setting, Denmark. PARTICIPANTS: Primary care clinicians (GPs, PTs and DCs) in the Region of Southern Denmark were invited to register consecutive adult patient visits with LBP as the primary complaint. PRIMARY OUTCOME MEASURES: Clinicians reported care elements provided to patients with LBP. Elements varied due to professional differences (eg, prescriptive rights). Data were descriptively analysed, on group and individual levels, for frequency and combination of care elements, and practice patterns were explored with latent class analysis. RESULTS: The clinicians (33 GPs, 67 PTs and 43 DCs with a median experience of 15 years and 59% were females) registered 3500 patient visits. On average, the visits involved patients aged 51 years, and 51% were with females. The frequencies of common care elements across professions were information (42%-56% of visits between professions) and advice (56%-81%), while other common elements for GPs were pain medication (40%) and referrals to PTs (36%), for PTs, use of exercises (81%) and for DCs, use of manual therapy (96%). Substantial variation was observed within professions and distinct practice patterns, with different focuses of attention to information and advice versus exercise and manual therapy, were identified for PTs and DCs. CONCLUSIONS: These data indicate substantial variation in the care elements provided by GPs, PTs and DCs to LBP patients. The compositions of care and practice patterns identified challenge the understanding of usual care as a uniform concept and professions as homogeneous groups. Strategic use of particular care elements in different parts of treatment courses is indicated. Longitudinal data and qualitative enquiry are needed to assess if or how care is tailored to individual patients.

Myocardial perfusion imaging by 15O-H2O positron emission tomography predicts clinical revascularization procedures in symptomatic patients with previous coronary artery bypass graft.

Aims: We wanted to assess if 15O-H2O myocardial perfusion imaging (MPI) in a clinical setting can predict referral to coronary artery catheterization [coronary angiography (CAG)], execution of percutaneous coronary intervention (PCI), and post-PCI angina relief for patients with angina and previous coronary artery bypass graft (CABG). Methods and results: We analysed 172 symptomatic CABG patients referred for 15O-H2O positron emission tomography (PET) MPI at Aarhus University Hospital Department of Nuclear Medicine & PET Centre, of which five did not complete the scan. In total, 145 (87%) enrolled patients had an abnormal MPI. Of these, 86/145 (59%) underwent CAG within 3 months; however, no PET parameters predicted referral to CAG. During the CAG, 25/86 (29%) patients were revascularized by PCI. Relative flow reserve (RFR) (0.49 vs. 0.54 P = 0.03), vessel-specific myocardial blood flow (MBF) (1.53 vs. 1.88 mL/g/min, P < 0.01), and vessel-specific myocardial flow reserve (MFR) (1.73 vs. 2.13, P < 0.01) were significantly lower in patients revascularized by PCI. Receiver operating characteristic analysis of the vessel-specific parameters yielded optimal cutoffs of 1.36 mL/g/min (MBF) and 1.28 (MFR) to predict PCI. Angina relief was experienced by 18/24 (75%) of the patients who underwent PCI. Myocardial blood flow was an excellent predictor of angina relief on both a global [area under the curve (AUC) = 0.85, P < 0.01] and vessel-specific (AUC = 0.90, P < 0.01) level with optimal cutoff levels of 1.99 mL/g/min and 1.85 mL/g/min, respectively. Conclusion: For CABG patients, RFR, vessel-specific MBF, and vessel-specific MFR measured by 15O-H2O PET MPI predict whether subsequent CAG will result in PCI. Additionally, global and vessel-specific MBF values predict post-PCI angina relief.

Database coverage and their use in systematic reviews regarding spinal manipulative therapy: an exploratory study.

BACKGROUND: Systematic reviews (SRs) of randomized controlled trials (RCTs) are considered one of the most reliable study types. Through a systematic and thorough literature search, researchers aim to collect all research relevant to their purpose. The selection of databases can be challenging and depend on the topic of interest. The Cochrane Handbook suggests searching at least the following three databases: Cochrane Library, MEDLINE, and EMBASE. However, this is not always sufficient for reviews on the musculoskeletal field in general. This study aimed to examine the frequency and choice of databases used by researchers in SRs of spinal manipulative therapy (SMT). Secondly, to analyze the RCTs included in the SRs to determine the optimal combination of databases needed to conduct efficient literature searches for SRs of SMT. METHODS: SRs investigating the effect of SMT on any patient-reported outcome measure were identified through searches in PubMed and Epistemonikos (all entries till date of search February 25, 2022). For each SR, databases searched and included RCTs were collected. RCTs were searched individually in nine databases (Cochrane Library, MEDLINE/PubMed, EMBASE, Google Scholar, CINAHL, Web of Science, Index to Chiropractic Literature, PEDro, and AMED). Coverage rates were calculated using the number of retrieved RCTs by the database or combinations of databases divided by the total number of RCTs. RESULTS: Eighty-five SRs published met the inclusion criteria, and 442 unique RCTs were retrieved. The most frequently searched database was MEDLINE/PubMed. Cochrane Library had the highest overall coverage rate and contained the third most unique RCTs. While a 100% retrieval was not possible, as 18 RCTs could not be retrieved in any of the nine databases, the combination of Cochrane Library, Google Scholar, and PEDro retrieved all possible RCTs with a combined coverage rate of 95.9%. CONCLUSIONS: For SRs on SMT, we recommend using the combination suggested by the Cochrane Handbook of Cochrane Library, MEDLINE/PubMed, Embase, and in addition, PEDro and Index to Chiropractic Literature. Google Scholar might be used additionally as a tool for searching gray literature and quality assurance.

Ischemic heart failure mortality is not predicted by cardiac insulin resistance but by diabetes per se and coronary flow reserve: A retrospective dynamic cardiac 18F-FDG PET study.

BACKGROUND & AIMS: The connection between peripheral insulin resistance (IR) and coronary artery disease is well-established. Both are major risk factors for the development of ischemic cardiomyopathy potentially leading to heart failure (HF). Whether cardiac IR also impacts overall survival and morbidity is still debated. We therefore aimed to test if cardiac IR predicts mortality and major cardiovascular events (MACE) in patients with HF scheduled for cardiac viability testing before revascularization. METHODS: This retrospective study included 131 patients with a clinical diagnosis of ischemic HF (114 (87%) male, 33 (25%) with diabetes) referred to a viability Rubidium-82 (perfusion) and dynamic 18F-Fluorodeoxyglucose (metabolism) positron emission tomography combined with computed tomography prior to a potential revascularization procedure. Cardiac IR was assessed by myocardial glucose uptake (MGU) in a remote (non-scarred) area of the left ventricle during a hyperinsulinemic-euglycemic clamp (1mIE/kg/min). RESULTS: MGU correlated with skeletal muscle glucose uptake (p < 0.001) and whole-body glucose uptake (M-value) (p < 0.001), whereas no association was observed for individuals with diabetes. MGU did not predict the risk of death or MACE. However, both overt diabetes and reduced coronary flow reserve predicted overall survival. CONCLUSION: Even though diabetes and related small-vessel disease is associated with increased mortality, cardiac IR per se does not predict cardiovascular morbidity and mortality.

Myocardial Viability Testing by Positron Emission Tomography: Basic Concepts, Mini-Review of the Literature and Experience From a Tertiary PET Center.

Ischemic heart disease ranges in severity from slightly reduced myocardial perfusion with preserved contractile function to chronic occlusion of coronary arteries with myocardial cells replaced by acontractile scar tissue-ischemic heart failure (iHF). Progression towards scar tissue is thought to involve a period in which the myocardial cells are acontractile but still viable despite severely reduced perfusion. This state of reduced myocardial function that can be reversed by revascularization is termed "hibernation." The concept of hibernating myocardium in iHF has prompted an increasing amount of requests for preoperative patient workup, but while the concept of viability is widely agreed upon, no consensus on clinical testing of hibernation has been established. Therefore, a variety of imaging methods have been used to assess hibernation including morphology based (MRI and ultrasound), perfusion based (MRI, SPECT, or PET) and/or methods to assess myocardial metabolism (PET). Regrettably, the heterogeneous body of literature on the subject has resulted in few robust prospective clinical trials designed to assess the impact of preoperative viability testing prior to revascularization. However, the PARR-2 trial and sub-studies has indicated that >5% hibernating myocardium favors revascularization over optimized medical therapy. In this paper, we review the basic concepts and current evidence for using PET to assess myocardial hibernation and discuss the various methodologies used to process the perfusion/metabolism PET images. Finally, we present our experience in conducting PET viability testing in a tertiary referral center.