Gated Blood Pool Research Articles

Evaluating the accuracy of planar gated blood pool processing software using simulated patient studies

Planar gated blood pool (GBP-P) radionuclide imaging is a valuable non-invasive technique for assessing left ventricular ejection fraction (LVEF). Serial cardiac imaging can be performed to monitor the potential decline in LVEF among patients undergoing cardiotoxic chemotherapy. Consequently, accurate LVEF determination becomes paramount. While commercial software programs have enhanced the LVEF values' reproducibility, concerns remain regarding their accuracy. This study aimed to generate a database of GBP-P studies with known LVEF values using Monte Carlo simulations and to assess LVEF values' accuracy using four commercial software programs.We utilised anthropomorphic 4D-XCAT models to generate 64 clinically realistic GBP-P studies with Monte Carlo simulations. Four commercial software programs (Alfanuclear, Siemens, General Electric Xeleris, and Mediso Tera-Tomo) were used to process these simulated studies. The accuracy and reproducibility of the LVEF values determined with these software programs and the intra- and inter-observer reproducibility of the LVEF values were assessed.Our study revealed a strong correlation between LVEF values calculated by the software programs and the true LVEF values derived from the 4D-XCAT models. However, all the software programs slightly underestimated LVEF at lower LVEF values. Intra- and inter-observer reliability for LVEF measurements was excellent.Accurate LVEF assessment is crucial for determining the patient's cardiac function before initiating and during chemotherapy treatment. The observed underestimation, particularly at lower LVEF values, emphasises the need for the accurate and reproducible determination of these values to avoid excluding suitable candidates for chemotherapy. The software programs' excellent intra- and inter-observer reliability highlights their potential to reduce subjectivity when using the semi-automatic processing option.This study confirms the accuracy and reliability of these commercial software programs in determining LVEF values from simulated GBP-P studies. Future research should investigate strategies to mitigate the underestimation biases and extend findings to diverse patient populations.Gated blood pool studies, left ventricular ejection fraction, Monte Carlo simulations, 4D-XCAT models.

Sixteen-Frame Gated Myocardial Perfusion SPECT as a Surrogate for Equilibrium Radionuclide Angiography in Measurement of Systolic and Diastolic Indices: A Cross-Sectional Study

Abstract Introduction Equilibrium radionuclide angiography (ERNA) has long been assumed as the preferred method to assess cardiac volumes as well as left ventricular systolic and diastolic indices. ERNA was used to diagnose subtle changes in cardiac function during chemotherapy or early stages of heart failure. Gated myocardial perfusion SPECT (GMPS) was introduced as a more feasible and versatile alternative to ERNA, but the precision of GMPS to assess systolic and diastolic indices has not yet been fully reviewed. Method We studied the left ventricular systolic and diastolic functional indices measured by a 16-frame GMPS and compared the results with those of ERNA in 25 patients. All the images were analyzed visually, semi-quantitatively, and quantitatively using quantitative gated SPECT (QGS), quantitative blood pool SPECT (QBS), and planar gated blood pool (PGBP) software. The left ventricular functional indices calculated using QGS compared with those obtained using QBS and PGBP Result Our study found a significant correlation between the left ventricular ejection fraction (LVEF) calculated using the PGBP, QGS, and QBS methods. There was a significant correlation between the LV peak ejection rate (LVPER) calculated by the PGBP and QGS analyses, and there was no significant difference in the LVPER calculated with the QGS and QBS methods. This study also revealed a significant correlation between the LV peak filling rate (LVPFR) calculated by QBS and QGS, with no significant difference between them. We also found a significant correlation between LV end systolic volume (LVESV) calculated using QGS and QBS and between LV end diastolic volume (LVEDV) calculated using QGS and QBS software. This study also revealed a significant correlation between the LV mean filling rate over the first third of diastole (LVMFR/3) calculated using the QGS and QBS software. Conclusion Considering the significant correlation between LVEF, LVPER, LVPFR, LVESV, LVMFR/3, and LVEDV calculated using the QGS and QBS methods in our study, the 16-frame GMPS could be regarded as an acceptable substitute for ERNA in the investigation of systolic and diastolic indices.

Relationship between left ventricular mechanical dyssynchrony with cardiac resynchronization therapy response in chronic heart failure patients with left bundle branch block

Aim. To investigate the relationship between left ventricular (LV) mechanical dyssynchrony with cardiac resynchronization therapy (CRT) response in chronic heart failure (CHF) pts with left bundle branch block.Methods. Forty-nine pts (male - 34 [69.4%], average age 58.3±11.4 years) with sinus rhythm, permanent left bundle branch block with QRS duration ≥150 ms and New York Heart Association (NYHA) II-III functional class of CHF were included in the study. In addition to full examination, myocardial perfusion scintigraphy (MPS) and gated blood pool single-photon emission computed tomography (gBPS) were performed before and 6 months after CRT devices with cardioverter-defibrillator function implantation. Pts were considered as responders to CRT if they fulfilled after 6-month follow-up the following combined criteria: NYHA FC improvement ≥1 class + LV end systolic volume decrease >15% or NYHA FC improvement ≥1 class + LV ejection fraction improvement >5%.Results. The 1st and 2nd groups included 35 (71.4%) and 14 (28.6%) pts with and without response to CRT respectively. Groups were comparable in terms of pre-CRT implantation clinical and instrumental parameters, except for MPS and gBPS parameters. The multivariate logistic regression had shown that only ∆interventricular dyssynchrony (adjusted odds ratio [OR] 1,0349; 95% confidence interval [CI] 1.0075-1,0631; р=0.01) and phase standard deviation of the anterior LV wall (OR 1.0669; 95% CI 1.0118-1.1251; p=0.01) were independently related with CRT response. An increase in the prognostic coefficient, calculated using the ∆interventricular dyssynchrony and phase standard deviation of the anterior LV wall, more than 0.67 was a predictor of CRT response (area under the curve 0.918; sensitivity 85.71; specificity 85.71; p <0.001).Conclusion. The mechanical dyssynchrony assessed by MPS and gBPS is associated with CRT response. According to our predictive model, an increase in prognostic coefficient more than 0.67 is a predictor of CRT response.

Determinants of impaired coupling of right ventricle to hemodynamic load in advanced HFrEF

Abstract Background The mechanisms and consequnces of impaired right ventricular (RV) dysfunction and impaired RV-pulmonary artery (PA) coupling in advanced heart failure (HF) poorely understood. Purpose To compare RV-PA coupling parameters in patients with advanced HFrEF, PAH and in controls to ellucidate determinants and prognostic impact of RV-PA uncoupling in HFrEF. Methods 260 pacients with advanced HF (NYHA 3.0±0.5, 40% CAD, LVEF: 23±10%, 87% males, BMI: 28±4.5 kg/m2, BNP: 1238±982 pg/ml), 39 controls and 21 PAH patients underwent lab tests, ecocardiography, right heart catheterisation and equilibrium gated blood pool SPECT to precisely measure cardiac volumes. RV End-systolic elastance (Ees) and Effective arterial elastance (Ea) were calculated by single beat method. Patients were longitudinally followed for occurrence of adverse outcome (urgent Tx, LVAD or death without Tx/LVAD). Results PAH patients had higher PA pressures and more dilated RV than HFrEF and controls. Despite of that, RV-PA coupling, reflected by Ees/Ea ratio, was more profoundly reduced in HFrEF than in PAH (Figure). While RV contractility (Ees) was augmented by increased afterload in PAH, such augmentation was absent in HFrEF. At follow-up (median 258; 53–763 days), 69% of HFrEF subjects experienced adverse event (17% death, 24% urgent HTx, 28% LVAD). In HFrEF, RV-PA coupling was strongly predictive od adverse outcome, more than RV EF%, RV EDV or RV Ees. The strongest predictors of reduced RV Ees/Ea ratio in HFrEF were in descending order: RV EF, RV EDV, PA systolic/systemic systolic pressure ratio (PAs/SBP), PAWP, heart rate, PA compliance, RA mean pressure, PA mean pressure, BNP level, SBP, PAs, Tri Reg grade, Non-CAD etiology of HF, Mi Reg grade, PVR, RV dyssynchrony, absence of ACEi/ARB/S-V (GLM model, all p<0.001). RV Ees/Ea ratio correlated with PAs/SBP ratio, that reflects systolic ventricular interdependence. Invasive PAs/SBP predicted outcome and closely correlated with non-invasive estimation of PAs/SBP. Conclusion Despite having less PH and smaller RV, RV coupling is more impaired in HFrEF than in PAH due to absence of RV contractility enhancement. Higher RV volume, heart rate, tricuspid regurgitation, lower PA compliance, higher PAWP and systolic ventricular interdependence (PAs/SBP) are main determinants of RV PA decoupling in HFrEF. Elevated PA systolic pressure but low systemic BP (high PAs/SBP ratio) is associated with poor RV-PA coupling and prognosis. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): AZV NU20-02-00052, AZV NU21-02-00402

Evaluating Usefulness of Deep Learning Based Left Ventricle Segmentation in Cardiac Gated Blood Pool Scan

Evaluating Usefulness of Deep Learning Based Left Ventricle Segmentation in Cardiac Gated Blood Pool Scan

Low-dose dobutamine stress gated blood pool SPECT assessment of left ventricular contractile reserve in ischemic cardiomyopathy: a feasibility study.

The purpose of the present study was to evaluate the feasibility of gated blood pool single-photon emission computed tomography (GBPS) with low-dose dobutamine (LDD) stress test, performed on a single-photon emission computed tomography (SPECT) camera equipped with cadmium-zinc-telluride (CZT) solid-state detectors, in assessing of left ventricle (LV) contractile reserve in patients with ischemic cardiomyopathy (ICM). A total of 52 patients (age 59 ± 7.2years, 47 men and 5 women) with ICM and a control group of 10 patients without obstructive coronary artery lesion underwent GBPS and transthoracic echocardiography (TTE) at rest and during LDD stress test (5, 10, 15µg/kg/min). The duration of each GBPS step was 5min. Stress-induced changes in LV ejection fraction (ΔLVEF), peak ejection rate, LV volumes, and mechanical dyssynchrony (phase histogram standard deviation, phase histogram bandwidth and entropy) obtained with GBPS were estimated. All GBPS indices except end-diastolic volume showed significant dynamics during stress test in both groups. The majority of parameters in ICM patients showed significant changes at a dobutamine dose of 10µg/kg/min as compared to the rest study. Seventeen percent of ICM patients, but none from the control group, showed a decrease in LVEF during stress, accompanied by a significant increase in entropy. The intra- and inter-observer reproducibility was excellent for both rest and stress studies. There was a moderate correlation (r = 0.5, p = 0.01) between GBPS and TTE, with a mean difference value of - 1.7 (95% confidence interval - 9.8; 6.4; p = 0.06) in ΔLVEF. Low-dose dobutamine stress GBPS performed with high-efficiency CZT-SPECT cameras can be performed for evaluating stress-induced changes in LV contractility and dyssynchrony with lower acquisition time. A dobutamine dose of 10µg/kg/min can potentially suffice to detect stress-induced changes in patients with ICM during GBPS. ClinicalTrials.gov identifier: NCT04508608 (August 7, 2020).

The role of stress-induced dyssynchrony obtained from nuclear modalities in evaluation of high-risk patients after surgical treatment of ischemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: None. Background Mechanical dyssynchrony (MD) is a well-known parameter witch has prognostic value [1]. Stress tests can be used to unmask MD. However, stress-induced changes in left ventricle (LV) MD by data of nuclear imaging modalities are not well-understood, especially its predictive value [2]. Purpose. To assess the role of stress-induced changes of LV MD obtained by nuclear modalities in evaluating high-risk patients after surgical treatment of ischemic cardiomyopathy (ICM). Methods. Sixty-nine patients with ICM were enrolled. Before surgical treatment all patients underwent gated myocardial perfusion imaging (gMPI) (Tc99m-MIBI; 2 days stress-rest protocol, adenosine 140mkg/kg/min) and gated blood pool SPECT (gBPS) (rest – stress, dobutamine doses of 5/10/15 µg/kg/min). After surgical treatment patients were divided into 2 groups: with (n = 21) and without (n = 48) complicated course of early postoperative period (death, intra-aortic balloon pump, extra inotropic support). The following parameters were estimated: summed stress score (SSS), summed rest score (SRS), summed different score (SDS); phase mean, phase standard deviation (PSD) and histogram bandwidth (HBW) (% from cycle for MPI; degrees for gBPS); phase entropy (%, only by gBPS). Stress-induced changes (Δ) were calculated for MPI indices as [stress value-rest value], for gBPS indices as [value on each dobutamine dose-rest value]. For gBPS the maximum changes of MD were calculated as well. Results. Rest gBPS MD correlated with SRS better than rest gMPI (gMPI: PSD r = 0.31, p = 0.005; HBW r = 0.28, p = 0.008; gBPS: PSD r = 0.47, p < 0.001; HBW r = 0.36, p = 0.006; entropy r = 0.39, p = 0.003). Stress gBPS MD correlated better with post stress gMPI MD at the dobutamine dose of 5µg/kg/min. An following increase of the dobutamine dose led to a decrease in the r-value, but it remained significant for all indices (tab.1). Stress-induced MD changes didn’t correlate between gMPI and gBPS. Mann-Whitney test showed significant differences in SDS (p = 0.02) between the groups. Both methods didn’t show any differences at rest study. Stress-induced changes of MD showed differences between groups in only ΔEntropy rest-10µg/kg/min (p = 0.02) and maximum ΔEntropy (p = 0.01) by gBPS, as well as Δphase mean (p = 0.03) by gMPI. Logistic regression analysis showed that only maximum ΔEntropy has prognostic value in prediction of the course of early postoperative period (OR 1.2 95%CI 1.04; 1.37). ROC-analysis showed sensitivity of 80% and specificity of 55% with AUC of 0.7 for cut-off value >0. Conclusion. LVMD obtained from gBPS is associated with SRS better than those obtained from gMPI. Dyssynchrony indices obtained from gMPI with adenosine stress-test have a week to moderate correlation with those obtained from dobutamine gBPS, and correlation decrease with increasing of dobutamine dose. Only maximum ΔEntropy obtained from dobutamine gBPS is associated with the adverse course of early postoperative period in patients with ICM.

The comparison of left ventricular mechanical dyssynchrony obtained by myocardial perfusion scintigraphy and gated blood pool SPECT to predict the result of the cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction The assessment of left ventricular mechanical dyssynchrony (LV MD) is essential in identifying patients who may benefit from cardiac resynchronization therapy (CRT). Both gated myocardial perfusion scintigraphy (MPS) and gated blood pool SPECT (GBPS) are widely used to LV MD assessment [1,2]. Lack of data is available regarding the comparison of left ventricular MD parameters obtained by MPS and GBPS on cadmium-zinc-telluride (CZT) gamma-cameras and their prognostic value. Purpose to compare two scintigraphic methods – MPS and GBPS in LV MD assessment and to assess the capability of these methods to predict CRT response. Methods This study included 30 heart failure patients referred for CRT. Before CRT all patients underwent rest gated MPS and GBPS with LV MD evaluation on CZT cardiac gamma. Based on the phase analysis, the following indexes were estimated: phase standard deviation (SD) and phase histogram bandwidth (HBW). One year after CRT patients were divided to responders and non-responders. The response criteria were defined as LV end systolic volume decreased by ≥ 15% or LV ejection fraction increase by ≥ 5%, based on echocardiography. Results The correlation between gated MPI indexes and GBPS indexes was suboptimal: SD r = 0.39, p < 0.05; HBW r = 0.48, p < 0.05. Based on Mann-Whitney statistics significant differences between LV MD indexes, assessed by both MPS and GBPS were found: SD LV 56.1 (IQR 50.6 – 64) deg. vs 50.6 (37 - 61) deg., p < 0.05 and HBW LV 188.64 (176 - 213) deg. vs 201.68 (180 - 240) deg., p = 0.03, respectively. The Bland-Altman analysis showed poor agreement between gated MPS and GBPS for SD assessment (p = 0.02) with mean difference value 7.02 (96% CI 1.11 to 12.9). However both MPS and GBPS were comparable in terms of HBW estimation (p = 0.18), with mean difference value of -12.5 (96% CI -31.5 to 6.3).MD indexes derived by MPS differed significantly between CRT responders and non-responders: SD 53.56 (47 – 63.4) deg. vs 62.4 (56-71) deg., p < 0.05; HBW 182.1 (166 - 211) deg. vs 204.3 (179 - 225) deg., p < 0.05. MD indexes obtained by GBPS did not show significant difference in CRT responders and non-responders: SD 51.2 (37 – 62) deg. vs 49.4 (40 – 58) deg., p = 0.92 and HBW 203.4 (186 - 237) deg. vs 198.5 (174 - 240) deg., p = 073. Univariate logistic regression analysis showed that SD and HBW assessed by gated MPS were independent predictors of CRT response: SD (OR = 0.91; 95% CI 0.85-0.97; p < 0.05) and HBW (OR = 0.98; 95% CI 0.96-0.99; p =0.03). However MD indexes obtained by GBPS, did not show statistically significance in prediction of CRT response. Conclusion Gated MPS and GBPS are not interchangeable in terms of left ventricular MD assessment. Left ventricular SD and HBW obtained by gated MPI on CZT gamma-camera showed prognostic significance to predict CRT response.

Assessment of left ventricular ejection fraction with cardiofocal collimators: Comparison between IQ-SPECT, planar equilibrium radionuclide angiography, and cardiac magnetic resonance

BackgroundIQ-SPECT has been shown to significantly reduce acquisition time and administered dose while preserving image quality in myocardial perfusion imaging. Whether IQ-SPECT provides accurate left ventricular ejection fractions (LVEF) with gated blood pool SPECT (GBPS) remains unknown. MethodsSixty patients underwent IQ-SPECT GBPS and planar imaging. Among those patients, 11 underwent both cMRI and GBPS. GBPS LVEF, LVEDV, and LVESV were calculated using 2 validated software; QBS (Cedars-Sinai Medical Center, Los Angeles, USA) and MHI (Montreal Heart Institute, Montreal, Canada). LVEF, LVEDV, and LVESV obtained with the different modalities were compared. ResultsAverage planar LVEF was 48 ± 11% (mean ± SD), average LVEDV was 177 ± 59 mL (range 63 to 342 mL), and average LVESV was 96 ± 46 mL (range 16 to 234 mL). GBPS LVEF and their correlation coefficient with planar LVEF were 40 ± 12% (r = 0.70) and 44 ± 12% (r = 0.83) with QBS and MHI, respectively. Correlation coefficient between cMRI and planar LVEF was 0.65 and were 0.69 and 0.52 between cMRI and GBPS using QBS and MHI, respectively. ConclusionsLVEF calculated with GBPS using IQ-SPECT correlates with planar measurements. Correlation is best using the MHI method and variation is independent of LVEDV.

Noninvasive Assessment of Right Ventricular Function in Patients with Pulmonary Arterial Hypertension and Left Ventricular Assist Device.

Right ventricular (RV) failure in patients with pulmonary arterial hypertension (PAH) and left ventricular assist device (LVAD) is associated with increased hospitalizations, worsening functional class, and poor survival. Accurate RV function assessment is essential in diagnosing RV failure, guiding therapies, and determining prognosis. Noninvasive imaging techniques provide fast and reliable quantification of RV morphology and function. We review echocardiography, nuclear medicine, and cardiac magnetic resonance imaging (MRI) uses for RV function assessment in patients with PAH and LVAD. We identify current knowledge gaps in utilizing noninvasive tests to assess RV function. Echocardiography is most widely used to quantify RV function in patients with PAH and LVAD, followed by cardiac MRI for RV morphology and function measurement in PAH patients. The first-pass radionuclide angiography with radiolabeled RBC is the gold standard for calculating RV function. Gated blood pool SPECT can be an alternative as it separates the cardiac chambers well and provides accurate assessment of the RV function with high reproducibility, which is particularly useful for monitoring treatment. More research is needed to compare and validate these modalities in evaluating RV function.

RV function improvement following nitric oxide inhalation demonstrated by gated blood pool SPECT in a patient with primary pulmonary hypertension

RV function improvement following nitric oxide inhalation demonstrated by gated blood pool SPECT in a patient with primary pulmonary hypertension

Bone marrow hyperplasia detected by gated blood pool imaging

Technetium-99m RBC gated blood pool ventriculography study or multigated acquisition (MUGA) is a commonly employed imaging study to determine the left ventricle ejection fraction and regional wall motion. However, tracer distribution at abnormal sites requires further evaluation. We present the case of a young thalassemia patient with significant tracer uptake in the rib cage as observed in the planar images of MUGA study helping in the demonstration of scintigraphic evidence of bone marrow hyperplasia.

(132) - Analysis of Right Ventricular (RV) Regional and Global Systolic Function by Gated Blood Pool SPECT (GBPS) in Patients Undergoing Left Ventricular Assist Device (LVAD) Implantation

Pre-LVAD assessment of RV function is critical for surgical planning, but is confounded by asymmetric RV geometry. GBPS is count based (no geometric assumptions), provides global and regional RV function, and needs minimal operator input.

The utility of routine pre-chemotherapy screening with cardiac gated blood pool scan for patients at low risk of anthracycline toxicity

Background Anthracycline-based chemotherapy is used in many malignancies. Current recommendations by several groups suggest cardiac monitoring prior to and during anthracycline therapy. We aim to review the usefulness of baseline cardiac screening for left ventricular ejection fraction to assess if it had any impact on chemotherapy decisions in patients to be treated with anthracycline-based regimens or any beneficial effect upon outcomes. Methods We conducted a retrospective three-year audit of cancer patients who underwent GBPS prior to anthracycline (doxorubicin) chemotherapy. Subjects were identified via records from the Department of Nuclear Medicine. Pharmacy dispensing records identified those who received doxorubicin. Patient demographics, cancer type, cardiac risk factors, GBPS ejection fraction (EF), and cumulative anthracycline dose were collected. Results From 1 August 2009 to 31 July 2012, 179 patients underwent GBPS pre-doxorubicin chemotherapy. The mean age was 59 years (range 21-89 years), with 51% being males. Only two patients (1.1%) had an abnormal EF < 50%, while 33 patients (18%) had an EF 51-59% and 144 patients (80%) had EF ≥ 60%. The two patients with reduced baseline EF still received anthracycline-based chemotherapy. All 135 patients without any known cardiovascular risk factors had normal EFs. The total number of patients who received anthracycline chemotherapy during the same period was 207. Thus 28 patients (13%) commenced anthracycline without a prior GBPS. Conclusion Only 1.1% of the screened patients had EF < 50%. These two patients still received doxorubicin chemotherapy despite a compromised EF, as their treating clinicians believed that the benefits of chemotherapy outweighed the risk of potential cardiac toxicity. Our audit questions the practice of routine cardiac evaluation pre-anthracycline screening with GBPS. We propose that routine screening only be requested if cardiac risk factors are present.

Phase analysis of gated blood pool SPECT for multiple stress testing assessments of ventricular mechanical dyssynchrony in a tachycardia-induced dilated cardiomyopathy canine model

BackgroundStress-induced dyssynchrony has been shown to be independently correlated with clinical outcomes in patients with dilated cardiomyopathy (DCM) and narrow QRS complexes. However, the extent to which stress levels affect inter- and intraventricular dyssynchrony parameters remains unknown. MethodsTen large dogs were submitted to tachycardia-induced DCM by pacing the right ventricular apex for 3–4 weeks to reach a target ejection fraction (EF) of 35% or less. Stress was then induced in DCM dogs by administering intravenous dobutamine up to a maximum of 20 μg·kg−1·min−1. Hemodynamic and ventricular dyssynchrony data were analyzed by left ventricular (LV) pressure measurements and gated blood pool SPECT (GBPS) imaging. In order to assess mechanical dyssynchrony in DCM subjects and compare it with that of 8 normal counterparts, we extracted the following data: count-based indices of LV contraction homogeneity index (CHI), entropy and phase standard deviation, and interventricular dyssynchrony index. ResultsA significant LV intraventricular dyssynchrony (CHI: 96.4 ± 1.3% in control vs 78.6% ± 10.9% in DCM subjects) resulted in an intense LV dysfunction in DCM subjects (EF: 49.5% ± 8.4% in control vs 22.6% ± 6.0% in DCM), compared to control subjects. However, interventricular dyssynchrony did not vary significantly between the two groups. Under stress, DCM subjects showed a significant improvement in ventricular functional parameters at each level (EF: 22.6% ± 6.0% at rest vs 48.1% ± 5.8% at maximum stress). All intraventricular dyssynchrony indices showed a significant increase in magnitude of synchrony from baseline to stress levels of greater than or equal to 5 μg·kg−1·min−1 dobutamine. There were individual differences in the magnitude and pattern of change in interventricular dyssynchrony during the various levels of stress. ConclusionsBased on GBPS analyses, different levels of functional stress, even in close intervals, can have a significant impact on hemodynamic and intraventricular dyssynchrony parameters in a DCM model with narrow QRS complex.

Feasibility and accuracy of gated blood pool SPECT equilibrium radionuclide ventriculography for the assessment of left and right ventricular volumes and function in patients with left ventricular assist devices

BackgroundLeft ventricular assist devices (LVADs) require serial assessment of right and left ventricular (RV & LV) volumes and function. Because the RV is not assisted, its function is a critical determinant of the hemodynamic and contributes significantly to postoperative morbidity and mortality. We evaluated the feasibility and the accuracy of tomographic-equilibrium radionuclide ventriculography (t-ERV) for the assessment of patients with LVADs. MethodsTwenty-four patients with LVAD underwent t-ERV. Because of the limited acoustic window, transthoracic echocardiography (TTE) was only feasible in 19 patients. Functional evaluation including six-minute walk test (6MWT) and peak oxygen consumption (POC) was performed in 18 patients. Nine patients underwent a cardiac multidetector computed tomography (MDCT). Eight patients underwent a second evaluation by ERV 4.3 ± 1.4 months later. ResultsReliability between t-ERV and MDCT for LV end-diastolic volume, LV end-systolic volume, LV ejection fraction, RV end-diastolic volume, RV end-systolic volume, and RV ejection fraction (RVEF) was 0.900 (P = .001), 0.911 (P = .001), 0.765 (P = .021), 0.728 (P = .042), 0.875 (P = .004), and 0.781 (P = .023), respectively. There was no correlation between t-ERV and RV systolic parameters assessed by TTE. RVEF was correlated with POC (R = 0.521; P = .027). A cut-off value of 40% for RVEF measured by t-ERV could discriminate patients with poor functional status (P = .048 for NYHA stage; P = .016 for 6MWT and P = .007 for POC). Conclusiont-ERV is a simple, reproducible, and an accurate technique for the assessment of RV function in patients with LVADs and warrants consideration in the evaluation and monitoring of symptomatic patients.

Apical takotsubo syndrome in a patient with metastatic breast carcinoma on novel immunotherapy

A 56 year-old woman was to the current institution from a rural centre with sudden-onset central chest pain following a severe episode of abdominal cramping with diarrhoea associated with dysentery. Intermittent episodes of abdominal discomfort had developed after starting on clinical trial therapy for progressive breast carcinoma which was currently managed with steroid suppositories. Her past history was significant for metastatic herceptin-receptor positive breast carcinoma treated with a left mastectomy and axillary clearance and adjuvant anthracycline-based chemotherapy and trastuzumab. Following disease progression with lung metastases, she was enrolled in a clinical trial receiving 3 weekly pembrolizumab and trastuzumab with remission. She had serial gated blood pool scans with a baseline left ventricular ejection fraction (LVEF) of 66%, 5-months post treatment LVEF of 62% and 8-month LVEF of 67% (performed only a week prior to presentation). Apart from distant ex-tobacco smoking, she had no other cardiac risk factors.

Radiation reduction and faster acquisition times with SPECT gated blood pool scans using a high-efficiency cardiac SPECT camera

BackgroundPlanar gated blood pool scans are an established method for the evaluation of left ventricular ejection fraction (LVEF) but the camera technology used for these studies has not significantly changed in decades. The purpose of this study was to determine the diagnostic accuracy of new high-efficiency SPECT gated blood pool scans compared to traditional scans and determine if they can be performed with lower radiation doses or faster acquisition times. MethodsPatients undergoing a planar gated blood pool scan on a Na-I SPECT camera who consented to participate were subsequently imaged for 5 minutes in “List Mode” using a high-efficiency SPECT camera. LVEF was calculated for both the planar study and at 1, 2, 3, 4, and 5 minutes of acquisition on the high-efficiency camera. Counts acquired in the field of view, counts in the cardiac blood pool and LVEF were compared. ResultsA total of 46 patients were analyzed (48% male, mean age 55 years, and BMI 27.6 kg/m2) who received an average Tc-99m dose of 20.3 mCi (5.3 mSv), 17 (37%) with abnormal LVEF’s. The Na-I camera averaged 24,514 counts/min/mCi in the field of view and 8662 counts/min/mCi in the cardiac blood pool while the high-efficiency camera averaged 65,219 counts/min/mCi and 41,427 counts/min/mCi, respectively. Compared to the planar calculation of LVEF, 1-minute SPECT LVEF was on average 8.6 ± 10.7 higher, 2 minutes 3.5 ± 7.6 higher, 3 minutes 2.9 ± 8.5 higher, 4 minutes 2.5 ± 7.0 higher, and 5 minutes 1.1 ± 6.2 higher. Good correlation was seen between the SPECT LVEF’s and the planar LVEF’s across all acquisition times with correlation coefficients of 0.74-0.93. ConclusionsHigh-efficiency SPECT technology can reduce radiation exposure to patients during gated blood pool imaging or decrease acquisition time while maintaining diagnostic accuracy. Based on the improved count sensitivity with high-efficiency SPECT, a 50% reduction in injected activity may be achievable while maintaining short imaging times of 5 minutes, with further reduction possible at longer imaging times.

Performance et reproductibilité de TOMPOOL pour l’estimation des fractions d’éjection, volumes et débits bi-ventriculaires

BackgroundTo evaluate the diagnostic accuracy of TOMPOOL (gated blood pool SPECT). Comparison with a reference-algorithm: BP-SPECT. Comparison with MRI and right heart catheter measurement. Estimation of the inter-observer reproducibility. Methods and resultsNinety-nine consecutive patients underwent GBPS and two physicians performed the measurement using TOMPOOL and BP-SPECT. Results were compared to the recommended reference-standard: cardiac magnetic resonance imaging [CMR] (EDV, ESV, EF, n=35), catheter measurements from thermodilution [TD] (CO, n=21). ResultsResults are always referred using the following order: correlation with BP-SPECT (n=99), correlation with reference-standard (MRI or right heart catheter measurement), inter-observer correlation. RVEF: r=0.67; r=0.70; r=0.81. RVEDV: r=0.74; r=0.49; r=0.77. RVESV: r=0.76; r=0.64; r=0.81. RCO: r=0.68; 0.63; 0.78. LVEF: r=0.88; r=0.79; r=0.94. LVEDV: r=0.82; r=0.80; r=0.90. LVESV: r=0.89; r=0.90; 0.95. ConclusionTOMPOOL allows a quantitative and qualitative analysis of the volume and systolic function of the left ventricle. However, a prior CMR-based calibration is preferable (thresholds must be adjusted). A qualitative analysis of the right ventricle is more reliable (poorer correlation and reproducibility).

Gated blood pool SPECT: The estimation of right ventricular volume and function is algorithm dependent in a clinical setting

BackgroundGated blood pool SPECT (GBPS) requires further validation for the assessment of the right ventricle (RV). This study evaluated three algorithms: BP-SPECT, QBS, and TOMPOOL (results are referred using this order). We compared (1) their “quantitative-accuracy”: estimation of RV ejection fraction (EF), end-diastolic volume (EDV), and cardiac output (CO); (2) their “qualitative-accuracy”: threshold values allowing diagnosing an impairment of the RV function; (3) their reproducibility: inter-observer relative variability (IOV). Methods and ResultsForty-eight consecutive patients underwent GBPS. Recommended reference standards were used: cardiac magnetic resonance imaging (CMR) (EDV, EF, n = 48), catheter measurements from thermodilution (TD) (CO, n = 25). (1) “Quantitative-accuracy”: r = 0.42, 0.30, 0.42 for RVEF (CMR); r = 0.69, 0.77, 0.53 for RVEDV (CMR); 0.32, 0.36, 0.52 for RCO (TD). (2) “Qualitative-accuracy”: optimal thresholds were 54.7%, 38.5%, 45.2% (AUC: 0.83, 0.80, 0.79) for RVEF; 229, 180, 94 mL (AUC: 0.83, 0.81, 0.81) for RVEDV; 4.1, 4.4, 2.6 L·minute−1 (AUC: 0.73, 0.77, 0.80) for RCO. (3) Reproducibility: IOV was 5% ± 6%, 8% ± 12%, 17% ± 18% for RVEF; 6% ± 8%, 4% ± 4%, 21% ± 18% for RVEDV; 8% ± 8%, 11% ± 15%, 24% ± 20% for RCO. ConclusionDiagnostic accuracies are similar. A CMR-based calibration is required for a quantitative-analysis (cautious interpretation) or an accurate qualitative analysis (thresholds must be adjusted). Automatic procedures (BP-SPECT, QBS) offer the best compromise accuracy/reproducibility.