Mind Your Heart: Exploring Feasibility, Acceptability, and Preliminary Effects of Phone-Delivered Mindfulness Training on Medication Adherence in Outpatients With Chronic Heart Failure.

BACKGROUND: Mindfulness training (MT) may promote medication adherence in outpatients with heart failure. OBJECTIVE: The aims of this study were to determine the feasibility and acceptability of MT (primary outcomes) and explore effects on medication adherence, functional capacity, cognitive function, depression, and mindfulness skills (secondary outcomes). METHODS: In this pre/post-design study, participants received a 30-minute phone-delivered MT session weekly for 8 weeks. RESULTS: We enrolled 33 outpatients (32% women; 69.7 White; mean age, 60.3 years). Retention was 100%, and session attendance was 91%. Overall, participants (97%) rated MT as enjoyable. Objectively assessed ( P < .05) adherence decreased post intervention, whereas improvements were noted in functional capacity ( P = .05), mindfulness ( P < .05), and cognitive function (reaching significance for Flanker scores). CONCLUSIONS: Phone-delivered MT was feasible and acceptable. Whereas no improvements were noted in medication adherence and depression, cognitive function, functional capacity, and mindfulness levels increased post intervention, suggesting MT may have beneficial effects in outpatients with heart failure.

Lung cancer screening provider recommendation and completion in black and White patients with a smoking history in two healthcare systems: a survey study.

BACKGROUND: Annual lung cancer screening (LCS) with low dose CT reduces lung cancer mortality. LCS is underutilized. Black people who smoke tobacco have high risk of lung cancer but are less likely to be screened than are White people. This study reports provider recommendation and patient completion of LCS and colorectal cancer screening (CRCS) among patients by race to assess for utilization of LCS. METHODS: 3000 patients (oversampled for Black patients) across two healthcare systems (in Rhode Island and Minnesota) who had a chart documented age of 55 to 80 and a smoking history were invited to participate in a survey about cancer screening. Logistic regression analysis compared the rates of recommended and received cancer screenings. RESULTS: 1177 participants responded (42% response rate; 45% White, 39% Black). 24% of respondents were eligible for LCS based on USPSTF2013 criteria. One-third of patients eligible for LCS reported that a doctor had recommended screening, compared to 90% of patients reporting a doctor recommended CRCS. Of those recommended screening, 88% reported completing LCS vs. 83% who reported completion of a sigmoidoscopy/colonoscopy. Black patients were equally likely to receive LCS recommendations but less likely to complete LCS when referred compared to White patients. There was no difference in completion of CRCS between Black and White patients. CONCLUSIONS: Primary care providers rarely recommend lung cancer screening to patients with a smoking history. Systemic changes are needed to improve provider referral for LCS and to facilitate eligible Black people to complete LCS.

Mind Your Heart-II: Protocol for a behavioral randomized controlled trial of mindfulness training to promote self-care in patients with comorbid heart failure and cognitive impairment.

BACKGROUND: Heart failure (HF) self-care is a robust predictor of prognosis in HF patients. Cognitive impairment is a common comorbidity in HF patients and constitutes a major challenge to HF self-care. Mindfulness training (MT) has been shown to improve cognitive function and interoception, two components essential to promoting effective HF self-care. OBJECTIVES: The aims of the Mind Your Heart-II (MYH-II) study are to investigate the effects of MT on HF self-care via changes in cognitive function and interoception in patients with comorbid HF and cognitive impairment, and to study the process by which MT can improve cognitive function via vagal control. We hypothesize that MT will improve cognitive function, interoception, and vagal control, resulting in enhanced HF self-care, compared to control participants. METHODS: MYH-II is a mechanistic parallel phase II behavioral randomized controlled trial. We will enroll 176 English or Spanish-speaking patients with comorbid chronic HF and mild cognitive impairment. Participants will be randomized to either: (1) 8-week phone-delivered MT + Enhanced Usual Care (EUC), or (2) EUC alone. Participants will complete baseline, end-of-treatment (3 months), and follow-up (9 months) assessments. The primary outcome is cognitive function (NIH Toolbox Fluid Cognition Composite Score). Additional key outcomes include: interoception (heartbeat tracking task, Multidimensional Assessment of Interoceptive Awareness), HF self-care (Self-Care of Heart Failure Index v7.2), and vagal control (high-frequency heart rate variability). IMPLICATIONS: If study hypotheses are confirmed, phone-based MT may be a key tool for improving HF self-care, and possibly clinical outcomes, in HF patients with comorbid cognitive impairment.

Skills to Enhance Positivity in adolescents at risk for suicide: Protocol for a randomized controlled trial.

BACKGROUND: Suicide and suicidal behavior during adolescence have been steadily increasing over the past two decades. The preponderance of interventions focuses on crisis intervention, underlying psychiatric disorders, regulating negative affect, and reducing cognitive distortions. However, low positive affectivity may be a mechanism that contributes to adolescent suicidal ideation and behaviors independent of other risk factors. Skills to Enhance Positivity (STEP) is an acceptance-based intervention, designed to increase attention to, and awareness of, positive affect and positive experiences. Results from a pilot RCT demonstrated engagement of the target (positive affect) and a decrease in clinical outcomes (suicidal events; i.e., either a suicide attempt or an emergency intervention for an acute suicidal crisis), providing support to test the clinical effectiveness of STEP in a larger clinical trial with clinical staff implementing the intervention. OBJECTIVE: To test the effectiveness of STEP, compared to Enhanced Treatment as Usual (ETAU), in reducing suicidal events and ideation in adolescents admitted to inpatient psychiatric care due to suicide risk. We hypothesize that those randomized to STEP, compared to ETAU, will have lower rates of suicide events, active suicidal ideation (SI), and depressed mood over the 6-month follow-up period. We hypothesize that those randomized to STEP, compared to ETAU, will demonstrate greater improvement in the hypothesized mechanisms of attention to positive affect stimuli and gratitude and satisfaction with life. METHODS: Participants will be randomized to either STEP or ETAU. STEP consists of four in-person sessions focused on psychoeducation regarding positive and negative affect, mindfulness meditation, gratitude, and savoring. Mood monitoring prompts and skill reminders will be sent via text messaging daily for the first month post-discharge and every other day for the following two months. The ETAU condition will receive text-delivered reminders to use a safety plan provided at discharge from the hospital and healthy habits messages, matched in frequency to the STEP group. This trial was registered on 6 August 2021 (ClinicalTrials.gov NCT04994873). RESULTS: The STEP protocol was approved by the National Institute of Mental Health (NIMH) Data and Safety Monitoring Board on March 4, 2022. The RCT is currently in progress. DISCUSSION: The STEP protocol is an innovative, adjunctive treatment that has the potential to have positive effects on adolescent suicidal ideation and attempts beyond that found for standard treatment alone.

Integrated smoking cessation and mood management following acute coronary syndrome: Protocol for the post-acute cardiac event smoking (PACES) trial.

BACKGROUND: Approximately 400,000 people who smoke cigarettes survive Acute Coronary Syndrome (ACS; unstable angina, ST and non-ST elevation myocardial infarction) each year in the US. Continued smoking following ACS is an independent predictor of mortality. Depressed mood post-ACS is also predictive of mortality, and smokers with depressed mood are less likely to abstain from smoking following an ACS. A single, integrated treatment targeting depressed mood and smoking could be effective in reducing post-ACS mortality. METHOD/DESIGN: The overall aim of the current study is to conduct a fully powered efficacy trial enrolling 324 smokers with ACS and randomizing them to 12 weeks of an integrated smoking cessation and mood management treatment [Behavioral Activation Treatment for Cardiac Smokers (BAT-CS)] or control (smoking cessation and general health education). Both groups will be offered 8 weeks of the nicotine patch if medically cleared. Counseling in both arms will be provided by tobacco treatment specialists. Follow-up assessments will be conducted at end-of-treatment (12-weeks) and 6, 9, and 12 months after hospital discharge. We will track major adverse cardiac events and all-cause mortality for 36 months post-discharge. Primary outcomes are depressed mood and biochemically validated 7-day point prevalence abstinence from smoking over 12 months. DISCUSSION: Results of this study will inform smoking cessation treatments post-ACS and provide unique data on the impact of depressed mood on success of post-ACS health behavior change attempts. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03413423. Registered 29 January 2018. https://beta. CLINICALTRIALS: gov/study/NCT03413423 .

Accuracy and Reproducibility of Myocardial Blood Flow Quantification by Single Photon Emission Computed Tomography Imaging in Patients With Known or Suspected Coronary Artery Disease.

BACKGROUND: Single photon emission computed tomography (SPECT) has limited ability to identify multivessel and microvascular coronary artery disease. Gamma cameras with cadmium zinc telluride detectors allow the quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR). However, evidence of its accuracy is limited, and of its reproducibility is lacking. We aimed to validate 99mTc-sestamibi SPECT MBF and MFR using standard and spline-fitted reconstruction algorithms compared with 13N-ammonia positron emission tomography in a cohort of patients with known or suspected coronary artery disease and to evaluate the reproducibility of this technique. METHODS: Accuracy was assessed in 34 participants who underwent dynamic 99mTc-sestamibi SPECT and 13N-ammonia positron emission tomography and reproducibility in 14 participants who underwent 2 99mTc-sestamibi SPECT studies, all within 2 weeks. A rest/pharmacological stress single-day SPECT protocol was performed. SPECT images were reconstructed using a standard ordered subset expectation maximization (OSEM) algorithm with (N=21) and without (N=30) application of spline fitting. SPECT MBF was quantified using a net retention kinetic model' and MFR was derived as the stress/rest MBF ratio. RESULTS: SPECT global MBF with splines showed good correlation with 13N-ammonia positron emission tomography (r=0.81, P<0.001) and MFR estimates (r=0.74, P<0.001). Correlations were substantially weaker for standard reconstruction without splines (r=0.61, P<0.001 and r=0.34, P=0.07, for MBF and MFR, respectively). Reproducibility of global MBF estimates with splines in paired SPECT scans was good (r=0.77, P<0.001), while ordered subset expectation maximization without splines led to decreased MBF (r=0.68, P<0.001) and MFR correlations (r=0.33, P=0.3). There were no significant differences in MBF or MFR between the 2 reproducibility scans independently of the reconstruction algorithm (P>0.05 for all). CONCLUSIONS: MBF and MFR quantification using 99mTc-sestamibi cadmium zinc telluride SPECT with spatiotemporal spline fitting improved the correlation with 13N-ammonia positron emission tomography flow estimates and test/retest reproducibility. The use of splines may represent an important step toward the standardization of SPECT flow estimation.

Exploring Effects of Aerobic Exercise and Mindfulness Training on Cognitive Function in Older Adults at Risk of Dementia: A Feasibility, Proof-of-Concept Study.

OBJECTIVES: This study sought to explore feasibility, acceptability, and preliminary effects of aerobic training (AT), mindfulness training (MT), or both (MT + AT) on cognitive function in older individuals at risk of dementia. METHOD: Participants were randomized to AT, MT, both, or usual care (UC). Z-scores of attention, verbal fluency, and episodic memory for non-demented adults (ZAVEN) were computed at baseline, end of treatment (EOT), and 6 months since baseline. RESULTS: Of the 36 enrolled participants (12 M, 24 F, mean age = 70.1 years), 97% were retained in the study at 6 months. At EOT, MT had higher ZAVEN scores than UC (b = .43, P =.03) and AT (b = .26, P = .10), while no differences were seen with MT + AT. A similar pattern was observed at a 6 month follow-up (all P values = .10). DISCUSSION: MT may improve cognitive function in older individuals at risk of dementia. These preliminary findings need to be confirmed in a fully powered RCT.

Effect of Case Management With Goal-Setting on Diet Scores and Weight Loss in Cardiac Rehabilitation Patients.

PURPOSE: The impact of cognitive-behavioral strategies and clinical factors on diet change during cardiac rehabilitation (CR) is not well studied. The purpose of this study was to examine the effects of collaborative goal-setting and clinical predictors on diet scores and weight loss in a case management model of CR. METHODS: We retrospectively examined the effects of clinical factors and goal-setting facilitated by case managers on diet scores and weight loss in 629 consecutive patients with atherosclerotic cardiovascular disease enrolled in our CR program between 2014 and 2016. The Rate Your Plate (RYP) diet score was used to measure diet quality at baseline and discharge. Logistic regression modeling was used to identify predictors of diet score change in a subsample with goal-setting data (n = 615). Analysis of variance was conducted in the subset with complete weight data (n = 584) to compare weight loss between those who improved their RYP scores versus those who did not. RESULTS: Participants were 27.9% female, with a mean age of 63.4 ± 11.5 y. The average body mass index at baseline was 30.3 ± 6.8, and 51.7% reported diet change and/or weight loss as a goal. After an average of 33 CR sessions, 27.3% improved their RYP scores by at least 1 risk category (mean score, 54.0 ± 9.0 vs 58.2 ± 7.3, P < .001) and the average weight loss was 1.5 ± 2.9 kg (P < .001). After logistic regression modeling, dietary goal-setting was significantly associated with improvement in diet scores and with greater weight loss (2.2 ± 3.1 kg vs 0.84 ± 2.6 kg, P < .001). CONCLUSIONS: A case management model that incorporates dietary goal-setting is associated with improved measures of diet quality and weight loss during CR.

Exploring synergistic effects of aerobic exercise and mindfulness training on cognitive function in older adults: Protocol for a pilot randomized controlled trial.

INTRODUCTION: Despite increasing evidence that aerobic exercise and cognitive training improve cognitive function among patients with cognitive impairment and dementia, few studies have focused on the effect of a combination of these approaches. This study will explore whether combining aerobic training (AT) with mindfulness training (MT), an intervention promoting the moment-to-moment awareness of physical sensations, affective states, and thoughts, improves cognitive function in individuals at risk of dementia. The primary objective is to determine the feasibility and acceptability of the intervention(s). The secondary objective is to obtain estimates of effect sizes on cognitive function and on possible mediators. METHODS AND ANALYSIS: Forty participants with at least 2 risk factors for dementia will be randomized (2 × 2 factorial design) to either AT (3 sessions/week for 12 weeks), MT (1 session/week for 8 weeks), both, or usual care. Assessments of cognitive function (attention, executive function, episodic, and working memory); physical activity (accelerometry), aerobic capacity (6-minute walk test), waist-to-hip ratio, blood pressure, social support (Multidimensional Scale of Perceived Social Support), depression (Hospital Anxiety and Depression Scale), and mindfulness (Five Facets of Mindfulness) will be conducted at baseline, end of treatment, and 6-months postbaseline. Rates of retention, attendance, and program satisfaction will be calculated for each of the 4 groups to determine the feasibility and acceptability of each intervention. ETHICS AND DISSEMINATION: This study has full ethical approval by The Miriam Hospital Institutional Review Board and adheres to the Standard Protocol Items: Recommendations for Interventional Trials reporting recommendations. If results from this exploratory, proof-of-concept study support our hypotheses, we will conduct a large randomized controlled trial (RCT) to determine the efficacy of combined MT and AT in improving cognitive function in individuals at risk of dementia. Results from the study will be disseminated through peer-reviewed journals and conference presentations. REGISTRATION DETAILS:: http://www.clinicalstrials.gov identifier NCT03289546.

Tai Chi Is a Promising Exercise Option for Patients With Coronary Heart Disease Declining Cardiac Rehabilitation.

BACKGROUND: More than 60% of patients decline participation in cardiac rehabilitation after a myocardial infarction. Options to improve physical activity (PA) and other risk factors in these high-risk individuals are limited. We conducted a phase 2 randomized controlled trial to determine feasibility, safety, acceptability, and estimates of effect of tai chi on PA, fitness, weight, and quality of life. METHODS AND RESULTS: Patients with coronary heart disease declining cardiac rehabilitation enrollment were randomized to a "LITE" (2 sessions/week for 12 weeks) or to a "PLUS" (3 sessions/week for 12 weeks, then maintenance classes for 12 additional weeks) condition. PA (accelerometry), weight, and quality of life (Health Survey Short Form) were measured at baseline and 3, 6, and 9 months after baseline; aerobic fitness (stress test) was measured at 3 months. Twenty-nine participants (13 PLUS and 16 LITE) were enrolled. Retention at 9 months was 90% (LITE) and 88% (PLUS). No serious tai chi-related adverse events occurred. Significant mean between group differences in favor of the PLUS group were observed at 3 and 6 months for moderate-to-vigorous PA (100.33 min/week [95% confidence interval, 15.70-184.95 min/week] and 111.62 min/week; [95% confidence interval, 26.17-197.07 min/week], respectively, with a trend toward significance at 9 months), percentage change in weight, and quality of life. No changes in aerobic fitness were observed within and between groups. CONCLUSIONS: In this community sample of patients with coronary heart disease declining enrollment in cardiac rehabilitation, a 6-month tai chi program was safe and improved PA, weight, and quality of life compared with a 3-month intervention. Tai chi could be an effective option to improve PA in this high-risk population. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02165254.

Correlation between two methods of florbetapir PET quantitative analysis.

This study evaluated performance of a commercially available standardized software program for calculation of florbetapir PET standard uptake value ratios (SUVr) in comparison with an established research method. Florbetapir PET images for 183 subjects clinically diagnosed as cognitively normal (CN), mild cognitive impairment (MCI) or probable Alzheimer's disease (AD) (45 AD, 60 MCI, and 78 CN) were evaluated using two software processing algorithms. The research method uses a single florbetapir PET template generated by averaging both amyloid positive and amyloid negative registered brains together. The commercial software simultaneously optimizes the registration between the florbetapir PET images and three templates: amyloid negative, amyloid positive, and an average. Cortical average SUVr values were calculated across six predefined anatomic regions with respect to the whole cerebellum reference region. SUVr values were well correlated between the two methods (r2 = 0.98). The relationship between the methods computed from the regression analysis is: Commercial method SUVr = (0.9757*Research SUVr) + 0.0299. A previously defined cutoff SUVr of 1.1 for distinguishing amyloid positivity by the research method corresponded to 1.1 (95% CI = 1.098, 1.11) for the commercial method. This study suggests that the commercial method is comparable to the published research method of SUVr analysis for florbetapir PET images, thus facilitating the potential use of standardized quantitative approaches to PET amyloid imaging.

Imaging characteristics and safety of florbetapir (¹8F) in Japanese healthy volunteers, patients with mild cognitive impairment and patients with Alzheimer's disease.

OBJECTIVE: The purpose of this study was to evaluate the performance characteristics and safety of florbetapir ((I8)F) positron emission tomography (PET) in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and cognitively normal (CN) control patients from Japan. METHODS: Florbetapir ((I8)F) PET was obtained in 48 subjects (15 AD patients, 15 MCI patients, and 18 CNs) within a multicenter phase 2/3 study. Amyloid burden was assessed visually and classified as positive or negative for pathologic levels of amyloid aggregation, blind to diagnostic classification. Cerebral to cerebellar standardized uptake value ratios (SUVRs) were determined from the florbetapir ((I8)F) PET images. Safety was assessed by monitoring adverse events, vital signs, clinical laboratory assessments, and electrocardiograms. Demographic variables and cognitive scales were summarized by using descriptive statistics for each group. Fisher's exact test and one-way analysis of variance were used to compare amyloid positivity and mean SUVRs, respectively, between diagnostic groups. RESULTS: Florbetapir ((I8)F) PET was rated visually amyloid positive in 80.0% of AD patients, 33.3% of MCI patients, and 16.7% of CNs. Mean SUVRs were highest in the AD group and lowest in the CN group for each brain region (P < 0.01) and globally (P < 0.05). Kappa statistics showed strong inter-reader agreement (Fleiss' kappa = 0.82) and individual reader's agreement with the majority of readers (kappa ranged from 0.79 to 1.0). Seventeen of the 48 subjects (35.4%) were Apolipoprotein E genotype ε4 positive, which included 10 subjects in the AD group and 7 subjects in the MCI group. A total of 6 subjects (5 of whom were in the CN group) had at least 1 treatment-emergent adverse event (TEAE). CONCLUSIONS: These data indicate that amyloid positivity increased with diagnostic category (CN < MCI < AD) and are consistent with expected rates of amyloid positivity among individuals with clinical diagnoses of AD and MCI. In addition, these results were similar to those obtained in United States studies. Florbetapir ((18)F) was safe and well tolerated. The reliability of both qualitative and quantitative assessments of florbetapir ((18)F) in this study population provides support for potential use in clinical settings in Japan.

Amyloid-ß imaging with Pittsburgh compound B and florbetapir: comparing radiotracers and quantification methods.

UNLABELLED: (11)C-Pittsburgh compound B ((11)C-PiB) and (18)F-florbetapir amyloid-ß (Aß) PET radioligands have had a substantial impact on Alzheimer disease research. Although there is evidence that both radioligands bind to fibrillar Aß in the brain, direct comparisons in the same individuals have not been reported. Here, we evaluated PiB and florbetapir in a retrospective convenience sample of cognitively normal older controls, patients with mild cognitive impairment, and patients with Alzheimer disease from the Alzheimer's Disease Neuroimaging Initiative (ADNI). METHODS: From the ADNI database, 32 participants were identified who had undergone at least 1 PiB study and subsequently underwent a florbetapir study approximately 1.5 y after the last PiB study. Cortical PiB and florbetapir retention was quantified using several different methods to determine the effect of preprocessing factors (such as smoothing and reference region selection) and image processing pipelines. RESULTS: There was a strong association between PiB and florbetapir cortical retention ratios (Spearman ρ = 0.86-0.95), and these were slightly lower than cortical retention ratios for consecutive PiB scans (Spearman ρ = 0.96-0.98) made approximately 1.1 y apart. Cortical retention ratios for Aß-positive subjects tended to be higher for PiB than for florbetapir images, yielding slopes for linear regression of florbetapir against PiB of 0.59-0.64. Associations between consecutive PiB scans and between PiB and florbetapir scans remained strong, regardless of processing methods such as smoothing, spatial normalization to a PET template, and use of reference regions. The PiB-florbetapir association was used to interconvert cutoffs for Aß positivity and negativity between the 2 radioligands, and these cutoffs were highly consistent in their assignment of Aß status. CONCLUSION: PiB and florbetapir retention ratios were strongly associated in the same individuals, and this relationship was consistent across several data analysis methods, despite scan-rescan intervals of more than a year. Cutoff thresholds for determining positive or negative Aß status can be reliably transformed from PiB to florbetapir units or vice versa using a population scanned with both radioligands.

Quantification of Myocardial Perfusion Reserve Using Dynamic SPECT Imaging in Humans: A Feasibility Study.

UNLABELLED: Myocardial perfusion imaging (MPI) is well established in the diagnosis and workup of patients with known or suspected coronary artery disease (CAD); however, it can underestimate the extent of obstructive CAD. Quantification of myocardial perfusion reserve with PET can assist in the diagnosis of multivessel CAD. We evaluated the feasibility of dynamic tomographic SPECT imaging and quantification of a retention index to describe global and regional myocardial perfusion reserve using a dedicated solid-state cardiac camera. METHODS: Ninety-five consecutive patients (64 men and 31 women; median age, 67 y) underwent dynamic SPECT imaging with (99m)Tc-sestamibi at rest and at peak vasodilator stress, followed by standard gated MPI. The dynamic images were reconstructed into 60-70 frames, 3-6 s/frame, using ordered-subsets expectation maximization with 4 iterations and 32 subsets. Factor analysis was used to estimate blood-pool time-activity curves, used as input functions in a 2-compartment kinetic model. K1 values ((99m)Tc-sestamibi uptake) were calculated for the stress and rest images, and K2 values ((99m)Tc-sestamibi washout) were set to zero. Myocardial perfusion reserve (MPR) index was calculated as the ratio of the stress and rest K1 values. Standard MPI was evaluated semiquantitatively, and total perfusion deficit (TPD) of at least 5% was defined as abnormal. RESULTS: Global MPR index was higher in patients with normal MPI (n = 51) than in patients with abnormal MPI (1.61 [interquartile range (IQR), 1.33-2.03] vs. 1.27 [IQR, 1.12-1.61], P = 0.0002). By multivariable regression analysis, global MPR index was associated with global stress TPD, age, and smoking. Regional MPR index was associated with the same variables and with regional stress TPD. Sixteen patients undergoing invasive coronary angiography had 20 vessels with stenosis of at least 50%. The MPR index was 1.11 (IQR, 1.01-1.21) versus 1.30 (IQR, 1.12-1.67) in territories supplied by obstructed and nonobstructed arteries, respectively (P = 0.02). MPR index showed a stepwise reduction with increasing extent of obstructive CAD (P = 0.02). CONCLUSION: Dynamic tomographic imaging and quantification of a retention index describing global and regional perfusion reserve are feasible using a solid-state camera. Preliminary results show that the MPR index is lower in patients with perfusion defects and in regions supplied by obstructed coronary arteries. Further studies are needed to establish the clinical role of this technique as an aid to semiquantitative analysis of MPI.