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result(s) for
"photon statistics"
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Methods for data analysis of resting energy expenditure measured using indirect calorimetry
by
Gonçalves, Ezequiel M.
,
Borges, Juliano H.
,
Guerra-Júnior, Gil
in
Absorptiometry, Photon - methods
,
Absorptiometry, Photon - statistics & numerical data
,
Adult
2019
•Reduced steady-state methods during 10 min of measurement overestimate the resting energy expenditure (REE).•Interval methods during 10 and 30 min of measurement overestimate the REE.•We recommend 5 min in steady state during 30 min of measurement to estimate the REE.
The aim of this study was to test the accuracy of different methods of resting energy expenditure (REE) data analysis using indirect calorimetry (IC) during traditional (30 min) and abbreviated (10 min) protocols.
Fifteen women and 15 men (21–34 y of age) completed two consecutive 30-min IC measurements. Body composition was measured using dual-energy x-ray absorptiometry. The reference method for REE analysis was 5 min in steady state (SS) during 30 min (first 5 min discarded). REE measurements were randomized to define a reference or testing method. An interval method was defined using 25, 20, and 15 min (with first 5, 10, and 15 min discarded, respectively), during 30 min, and 5 min (first 5 min discarded) during 10-min intervals. The SS method was defined using 5 min in SS (first 5 min discarded) during 30 min, 5, 4, and 3 min in SS during 10-min (first 5 min discarded) intervals.
Interval methods during 30 min and SS and interval methods during 10 min demonstrated large bias with significantly high REEs compared to the reference method (78.8–109.0 kcal/d, all P < 0.001). Testing methods demonstrated large upper limits of agreement between 225.2 and 322.8 kcal/d. No mean differences (P > 0.05), small bias (14.3 kcal/d), and narrow limits of agreement (–125.8 to 154.4 kcal/d) were observed between 5-min SS during 30 min and the reference method.
All interval methods and SS methods during 10 min overestimated REE. We recommend using 5-min SS during 30 min. The measurement may be repeated until all participants achieve SS.
Journal Article
A population-based study of postfracture care in Manitoba, Canada 2000/2001–2014/2015
by
Yang, S
,
Morin, S N
,
Lix, L M
in
Diabetes mellitus
,
Dual energy X-ray absorptiometry
,
Glucocorticoids
2019
SummaryWe previously found that population-based postfracture notification, which informed primary care physicians of their patient’s recent fracture and suggested assessment for osteoporosis, led to an improvement in postfracture care in the context of a randomized controlled trial (ClinicalTrials.gov identifier NCT00594789, fractures from late 2007 to mid-2010). Since June 2010, a province-wide postfracture notification program was implemented. This study was to (1) determine whether this program has resulted in sustained improvement in postfracture care and (2) test factors associated with receiving osteoporosis care.MethodsA retrospective matched cohort study was performed using population-based health administrative data in Manitoba, Canada. We selected individuals aged 50+ years with an incident major osteoporosis fracture (MOF; N = 18,541) in fiscal years 2000/2001 to 2013/2014 and controls without a MOF (N = 92,705) matched (5:1) on age, sex, and residential area. The Cochran-Armitage test tested for a linear trend in osteoporosis care outcomes for cases and controls. Logistic regressions were used to test characteristics associated with the likelihood of receiving osteoporosis care.ResultsThe percentage of individuals receiving DXA testing and/or osteoporosis medication increased in fracture cases (p < 0.001), but decreased in controls (p < 0.001). Odds ratios for osteoporosis care in years following the postfracture notification program were approximately double of those prior to the clinical trial. In addition to prior MOF (OR 9.03, 95% CI 8.60–9.48), factors associated with osteoporosis care included lower income (OR 0.72, 95% CI 0.67–0.78), glucocorticoid use (OR 4.37, 95% CI 3.72–5.14), diabetes diagnosis (OR = 0.74, 95% CI 0.68–0.80), and Charlson Comorbidity Index (indexes 1–2: OR 1.27, 95% CI 1.20–1.34; indexes 3–5: OR 1.26, 95% CI 1.13–1.40).ConclusionsAdopting a population-based postfracture notification program led to sustained improvements in postfracture care.
Journal Article
Diagnostic accuracy of rest/stress ECG-gated Rb-82 myocardial perfusion PET: Comparison with ECG-gated Tc-99m sestamibi SPECT
by
Hertenstein, Ginger K.
,
Case, James A.
,
Bryngelson, Jan R.
in
Accuracy
,
Aged
,
Cardiovascular disease
2006
Although single photon emission computed tomography (SPECT) and positron emission tomography (PET) myocardial perfusion imaging (MPI) have evolved considerably over the last decade, there is no recent comparison of diagnostic performance. This study was designed to assess relative image quality, interpretive confidence, and diagnostic accuracy by use of contemporary technology and protocols.
By consensus and without clinical information, 4 experienced nuclear cardiologists interpreted 112 SPECT technetium-99m sestamibi and 112 PET rubidium-82 MPI electrocardiography (ECG)–gated rest/pharmacologic stress studies in patient populations matched by gender, body mass index, and presence and extent of coronary disease. The patients were categorized as having a low likelihood for coronary artery disease (27 in each group) or had coronary angiography within 60 days. SPECT scans were acquired on a Cardio-60 system and PET scans on an ECAT ACCEL scanner. Image quality was excellent for 78% and 79% of rest and stress PET scans, respectively, versus 62% and 62% of respective SPECT scans (both
p < .05). An equal percent of PET and SPECT gated images were rated excellent in quality. Interpretations were definitely normal or abnormal for 96% of PET scans versus 81% of SPECT scans (
p = .001). Diagnostic accuracy was higher for PET for both stenosis severity thresholds of 70% (89% vs 79%,
p = .03) and 50% (87% vs 71%,
p = .003) and was higher in men and women, in obese and nonobese patients, and for correct identification of multivessel coronary artery disease.
In a large population of matched pharmacologic stress patients, myocardial perfusion PET was superior to SPECT in image quality, interpretive certainty, and diagnostic accuracy.
Journal Article
The EXERRT trial: “EXErcise to Regadenoson in Recovery Trial”: A phase 3b, open-label, parallel group, randomized, multicenter study to assess regadenoson administration following an inadequate exercise stress test as compared to regadenoson without exercise for myocardial perfusion imaging using a SPECT protocol
by
Thomas, Gregory S.
,
Feaheny, Kathleen M.
,
Gropler, Robert J.
in
Acute coronary syndromes
,
Cardiology
,
Coronary Artery Disease - diagnostic imaging
2017
This study assessed the non-inferiority and safety of regadenoson administration during recovery from inadequate exercise compared with administration without exercise.
Patients unable to achieve adequate exercise stress were randomized to regadenoson 0.4 mg either during recovery (Ex-Reg) or 1 hour after inadequate exercise (Regadenoson) (MPI1). All patients also underwent non-exercise regadenoson MPI 1-14 days later (MPI2). The number of segments with reversible perfusion defects (RPDs) detected using single photon emission computerized tomography imaging was categorized. The primary analysis evaluated the majority agreement rate between Ex-Reg and Regadenoson groups.
1,147 patients were randomized. The lower bound of the 95% confidence interval of the difference in agreement rates (−6%) was above the −7.5% non-inferiority margin, demonstrating non-inferiority of Ex-Reg to Regadenoson. Adverse events were numerically less with Ex-Reg (MPI1). In the Ex-Reg group, one patient developed an acute coronary syndrome and another had a myocardial infarction following regadenoson after exercise. Upon review, both had electrocardiographic changes consistent with ischemia prior to regadenoson.
Administering regadenoson during recovery from inadequate exercise results in comparable categorization of segments with RPDs and with careful monitoring appears to be well tolerated in patients without signs/symptoms of ischemia during exercise and recovery.
Journal Article
Aminophylline and caffeine for reversal of adverse symptoms associated with regadenoson SPECT MPI
by
Schwartz, Ronald G.
,
Doran, Jesse A.
,
Schneider, Marabel D.
in
Administration, Oral
,
Aged
,
Aminophylline - administration & dosage
2017
Aminophylline shortages led us to compare intravenous (IV) aminophylline with IV and oral (PO) caffeine during routine pharmacologic stress testing with SPECT MPI.
We measured presence, duration, and reversal of adverse symptoms and cardiac events following regadenoson administration in consecutive patients randomized to IV aminophylline (100 mg administered over 30-60 seconds), IV caffeine citrate (60 mg infused over 3-5 minutes), or PO caffeine as coffee or diet cola.
Of 241 patients, 152 (63%) received regadenoson reversal intervention. Complete (CR), predominant (PRE), or partial (PR) reversal was observed in 99%. CR by IV aminophylline (87%), IV caffeine (87%), and PO caffeine (78%) were similar (P = NS). Time to CR (162 ± 12.6 seconds, mean ± SD) was similar in treatment arms. PO caffeine was inferior to IV aminophylline for CR + PRE.
IV aminophylline and IV caffeine provide rapid, safe reversal of regadenoson-induced adverse effects during SPECT MPI. Oral caffeine appeared similarly effective for CR but not for the combined CR + PRE. Our results suggest PO caffeine may be an effective initial strategy for reversal of regadenoson, but IV aminophylline or IV caffeine should be available to optimize symptom reversal as needed.
Journal Article
Clinical validation of SPECT attenuation correction using x-ray computed tomography–derived attenuation maps: Multicenter clinical trial with angiographic correlation
by
Wackers, Frans J. Th
,
Peretz, Aharon
,
Liu, Yi-Hwa
in
Angiography - statistics & numerical data
,
attenuation correction
,
Cardiovascular disease
2005
Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon emission computed tomography (SPECT) myocardial perfusion images. In phantoms, normal subjects, and patients suspected of having coronary artery disease (CAD), we evaluated a new hybrid attenuation correction (AC) system that combines x-ray computed tomography (CT) with conventional stress SPECT imaging.
The effect of CT-based AC was evaluated in phantoms by assessing homogeneity of normal cardiac inserts. AC improved homogeneity of normal cardiac phantoms from 11% ± 2% to 5% ± 1% (
P < .001). Attenuation-corrected normal patient files were created from 37 normal subjects with a low likelihood (<3%) of CAD. The diagnostic performance of AC for detection of CAD was evaluated in 118 patients who had stress technetium 99m sestamibi or tetrofosmin stress SPECT imaging and coronary angiography. SPECT images with and without AC were interpreted by 4 blinded readers with different interpretative attitudes. Overall, AC improved the diagnostic performance of all readers, particularly the normalcy rate. The degree of improvement depended on interpretative attitude. Readers prone to high sensitivity or with less experience had the greatest gain in the normalcy rate, whereas a reader prone to higher specificity had improvements in sensitivity and specificity but not the normalcy rate. Importantly, improvement of one diagnostic variable was not associated with worsening of other variables.
CT-based AC of SPECT images consistently improved overall diagnostic performance of readers with different interpretive attitudes and experience. CT-based AC is well suited for routine use in clinical practice.
Journal Article
The safety and tolerability of regadenoson in patients with end-stage renal disease: The first prospective evaluation
by
Alqaid, Ammar
,
Morales Demori, Raysa
,
Doukky, Rami
in
Adenosine A2 Receptor Agonists - adverse effects
,
Cardiology
,
chronic kidney disease (CKD)
2013
There has not been any prospective evaluation of the safety and tolerability of regadenoson (REG)-stress in patients with end-stage renal disease (ESRD).
From the pooled database of two identically designed randomized, double-blinded, placebo-controlled clinical trials, ASSUAGE and ASSUAGE-CKD (IV-aminophylline vs placebo following REG-stress), we extracted the placebo-treated subjects to form 2 study groups: ESRD (dialysis or GFR < 15 mL/minute/1.73 m2) and control (GFR ≥ 30). The incidence of REG adverse effects and the hemodynamic and ECG responses to REG-stress were compared.
We identified 146 ESRD subjects and 97 controls. There was no significant difference in the incidence of the composite of any REG adverse effect [ESRD 108 (74%) vs control 73 (75%), P = .82]. ESRD patients seem to have excess incidences of diarrhea [42 (29%) vs 14 (14%), P = .009] and fewer events of dizziness [28 (19%) vs 43 (44%), P < .001]. There were no serious adverse events in either group. There was no significant difference in the incidence of ST-segment deviation, tachyarrhythmias, atrioventricular block, or hypotension.
This is the first prospective study to confirm the safety and tolerability of REG in patients with ESRD.
Journal Article
Prognostic validation of a 17-segment score derived from a 20-segment score for myocardial perfusion SPECT interpretation
2004
Recently, a 17-segment model of the left ventricle has been recommended as an optimally weighted approach for interpreting myocardial perfusion single photon emission computed tomography (SPECT). Methods to convert databases from previous 20- to new 17-segment data and criteria for abnormality for the 17-segment scores are needed.
Initially, for derivation of the conversion algorithm, 65 patients were studied (algorithm population) (pilot group, n = 28; validation group, n = 37). Three conversion algorithms were derived: algorithm 1, which used mid, distal, and apical scores; algorithm 2, which used distal and apical scores alone; and algorithm 3, which used maximal scores of the distal septal, lateral, and apical segments in the 20-segment model for 3 corresponding segments of the 17-segment model. The prognosis population comprised 16,020 consecutive patients (mean age, 65 ± 12 years; 41% women) who had exercise or vasodilator stress technetium 99m sestamibi myocardial perfusion SPECT and were followed up for 2.1 ± 0.8 years. In this population, 17-segment scores were derived from 20-segment scores by use of algorithm 2, which demonstrated the best agreement with expert 17-segment reading in the algorithm population. The prognostic value of the 20- and 17-segment scores was compared by converting the respective summed scores into percent myocardium abnormal. Conversion algorithm 2 was found to be highly concordant with expert visual analysis by the 17-segment model (
r = 0.982; κ = 0.866) in the algorithm population. In the prognosis population, 456 cardiac deaths occurred during follow-up. When the conversion algorithm was applied, extent and severity of perfusion defects were nearly identical by 20- and derived 17-segment scores. The receiver operating characteristic curve areas by 20- and 17-segment perfusion scores were identical for predicting cardiac death (both 0.77 ± 0.02,
P = not significant). The optimal prognostic cutoff value for either 20- or derived 17-segment models was confirmed to be 5% myocardium abnormal, corresponding to a summed stress score greater than 3. Of note, the 17-segment model demonstrated a trend toward fewer mildly abnormal scans and more normal and severely abnormal scans.
An algorithm for conversion of 20-segment perfusion scores to 17-segment scores has been developed that is highly concordant with expert visual analysis by the 17-segment model and provides nearly identical prognostic information. This conversion model may provide a mechanism for comparison of studies analyzed by the 17-segment system with previous studies analyzed by the 20-segment approach.
Journal Article
Prevalence and correlates of pulmonary emphysema in smokers and former smokers. A densitometric study of participants in the ITALUNG trial
by
Camiciottoli, Gianna
,
Paci, Eugenio
,
Picozzi, Giulia
in
Absorptiometry, Photon - statistics & numerical data
,
Causality
,
Chest
2009
We assessed with computed tomography (CT) densitometry the prevalence of emphysema in 266 (175 men and 91 women; mean age 64 ± 4 years) smokers and former smokers enrolled in the ITALUNG trial of lung cancer screening with low-dose thin-slice CT. Whole-lung volume and the relative area at −950 Hounsfield units (RA
950
) and mean lung attenuation (MLA) in 1 of every 10 slices (mean, 24 slices per subject) were measured. Lung volume, MLA and RA950 significantly correlated each other and with age. Average RA950 >6.8% qualifying for emphysema was present in 71 (26.6%) of 266 subjects, with a higher prevalence in men than in women (30.3% vs 19.8%; p = 0.003). Only in smokers was a weak (r = 0.18; p = 0.05) correlation between RA950 and packs/year observed. In multiple regression analysis, the variability of RA950 (R2 = 0.24) or MLA (R2 = 0.34) was significantly, but weakly explained by age, lung volume and packs/year. Other factors besides smoking may also have a significant role in the etiopathogenesis of pulmonary emphysema.
Journal Article
Transient ischemic dilation for coronary artery disease in quantitative analysis of same-day sestamibi myocardial perfusion SPECT
by
Arsanjani, Reza
,
Berman, Daniel S.
,
Germano, Guido
in
Cardiology
,
Comorbidity
,
Coronary Artery Disease - diagnostic imaging
2012
Background
Transient ischemic dilation (TID) of the left ventricle in myocardial perfusion SPECT (MPS) has been shown to be a clinically useful marker of severe coronary artery disease (CAD). However, TID has not been evaluated for 99mTc-sestamibi rest/stress protocols (Mibi-Mibi). We aimed to develop normal limits and evaluate diagnostic power of TID ratio for Mibi-Mibi scans.
Methods
TID ratios were automatically derived from static rest/stress MPS (TID) and gated rest/stress MPS from the end-diastolic phase (TID
ed
) in 547 patients who underwent Mibi-Mibi scans [215 patients with correlating coronary angiography and 332 patients with low likelihood (LLk) of CAD]. Scans were classified as severe (≥70% stenosis in proximal left anterior descending (pLAD) artery or left main (LM), or ≥90% in ≥2 vessels), mild to moderate (≥90% stenosis in 1 vessel or ≥70%-90% in ≥1 vessel except pLAD or LM), and normal (<70% stenosis or LLk group). Another classification based on the angiographic Duke prognostic CAD index (DI) was also applied: DI ≥ 50, 30 ≤ DI < 50 and DI < 30 or LLk group.
Results
The upper normal limits were 1.19 for TID and 1.23 for TID
ed
as established in 259 LLk patients. Both ratios increased with disease severity (
P
< .0001). Incidence of abnormal TID increased from 2% in normal patients to >36% in patients with severe CAD. Similarly, when DI was used to classify disease severity, the average ratios showed significant increasing trend with DI increase (
P
< .003); incidence of abnormal TID also increased with increasing DI. The incidence of abnormal TID in the group with high perfusion scores significantly increased compared to the group with low perfusion scores (stress total perfusion deficit, TPD < 3%) (
P
< .0001). The sensitivity for detecting severe CAD improved for TID when added to mild to moderate perfusion abnormality (3% ≤ TPD < 10%): 71% vs 64%,
P
< .05; and trended to improve for TID
ed
/TID
es
: 69% vs 64%,
P
= .08, while the accuracy remained consistent if abnormal TID was considered as a marker in addition to stress TPD. Similar results were obtained when DI was used for the definition of severe CAD (sensitivity: 76% vs 66%,
P
< .05 when TID was combined with stress TPD).
Conclusion
TID ratios obtained from gated or ungated Mibi-Mibi MPS and are useful markers of severe CAD.
Journal Article