Diagnostic performance of CMR, SPECT, and PET imaging for the detection of cardiac amyloidosis: a meta-analysis

Background Noninvasive myocardial imaging modalities, such as cardiac magnetic resonance (CMR), single photon emission computed tomography (SPECT), and Positron emission tomography (PET), are well-established and extensively used to detect cardiac amyloid (CA). The purpose of this study is to directly compare CMR, SPECT, and PET scans in the diagnosis of CA, and to provide evidence for further scientific research and clinical decision-making. Methods PubMed, Embase, and Cochrane Library were searched. Studies used CMR, SPECT and/or PET for the diagnosis of CA were included. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR), diagnostic odds ratio (DOR), their respective 95% confidence intervals (CIs) and the area under the summary receiver operating characteristic (SROC) curve (AUC) were calculated. Quality assessment of included studies was conducted. Results A total of 31 articles were identified for inclusion in this meta-analysis. The pooled sensitivities of CMR, SPECT and PET were 0.84, 0.98 and 0.78, respectively. Their respective overall specificities were 0.87, 0.92 and 0.95. Subgroup analysis demonstrated that 99mTc-HMDP manifested the highest sensitivity (0.99). 99mTc-PYP had the highest specificity (0.95). The AUC values of 99mTc-DPD, 99mTc-PYP, 99mTc-HMDP were 0.89, 0.99, and 0.99, respectively. PET scan with 11C-PIB demonstrated a pooled sensitivity of 0.91 and specificity of 0.97 with an AUC value of 0.98. Conclusion Our meta-analysis reveals that SEPCT scans present better diagnostic performance for the identification of CA as compared with other two modalities.

Added prognostic value of plaque burden to computed tomography angiography anatomic assessment and myocardial perfusion imaging in patients with diabetes Mellitus

Introduction Cardiac computed tomographic angiography (CCTA)-derived measures of coronary artery disease (CAD) burden such as segment involvement score (SIS), which quantifies the number of segments with plaque, have been shown to independently predict incident cardiovascular events. Purpose We aimed to compare the added prognostic value of plaque burden to CCTA anatomic assessment and single photon emission computed tomography (SPECT) physiologic assessment in patients with diabetes undergoing both tests. Methods Consecutive patients with diabetes who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected coronary artery disease at a tertiary care center were retrospectively identified from medical records. Stenosis severity and segment involvement score (SIS) were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed from date of imaging for major adverse cardiovascular events (MACE; inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.) Results A total of 778 patients were included (mean age 60.6±14.4 years, 55% males). Obstructive stenosis (left main ≥50%, all other coronary segments ≥70%) and ischemia were found in 15% and 16% of patients respectively. After a median follow-up of 31 months, 87 (11%) patients experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes in models including obstructive stenosis and ischemia (HR 1.17, 95% CI 1.10 - 1.24, p<0.001; 1.16, 95% CI 1.10 - 1.23, p<0.001). The addition of SIS also significantly improved discrimination (Harrel's C 0.75, p=0.006; 0.76, p=0.006 in models with CCTA obstructive stenosis and SPECT ischemia respectively). Results were consistent using subgroups of summed scores by composition of plaque (calcified vs non-calcified) and alternate definitions of obstructive stenosis. Conclusion Our results suggest that in high-risk patients with diabetes and suspected coronary disease, SIS has incremental prognostic value over ischemia by SPECT or stenosis by CCTA in predicting incident cardiovascular outcomes. FUNDunding Acknowledgement Type of funding sources: None.

SPECT-guided myocardial perfusion and metabolic fatty acid planar imaging to assess the severity of the pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension

Background Patients with chronic thromboembolic pulmonary hypertension (CTEPH) represent right ventricular (RV) enlargement and hypertrophy, which consequently increase the RV myocardial perfusion. Although the main energy source of myocardium is fatty acid, it remains unknown whether myocardial fatty acid metabolism is altered in loaded RV. Herein, we report a novel approach to assess the RV perfusion and fatty acid metabolism, which is called SPECT-guided planar imaging. Purpose To evaluate if SPECT-guided myocardial perfusion and metabolic fatty acid planar imaging reflects the severity of the pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension. Methods The study groups included 30 patients with CTEPH and 20 healthy controls. In these patients with CTEPH, 15 patients underwent pulmonary thromboendarterectomy (PEA). Mean pulmonary artery pressure (mPAP) by right heart catheterization was obtained in all CTEPH patients. 201Thallium (201Tl) and iodine-123-beta-methyl iodophenyl pentadecanoic acid (123I-BMIPP) planar myocardial imaging was performed in all participants. For the patients undergoing PEA, repetitive SPECT-guided 201Tl and 123I-BMIPP planar imaging was performed one year after the procedure. To assess the RV overload, the planar images were performed in left anterior oblique position, optimized to separate the RV from the left ventricular (LV) using SPECT-guided transverse imaging. We measured the total counts of 201Tl and 123I-BMIPP in both the RV and LV. Moreover, we calculated their relative counts of the RV to LV (abbreviated as HR/HL (Tl) and HR/HL (BMIPP), respectively) to determine the indices of myocardial perfusion and fatty acid metabolism, respectively. Results Both HR/HL (Tl) and HR/HL (BMIPP) were elevated in the CTEPH patients compared with control (0.62±0.14 vs. 0.36±0.07, p<0.01 and 0.57±0.14 vs. 0.34±0.06, p<0.01, respectively). In the CTEPH patients, average mPAP was 44.0±9.52 mmHg, which was correlated with HR/HL (Tl) (r=0.675, p<0.001) and HR/HL (BMIPP) (r=0.685, p<0.01). Furthermore, the decrease of average mPAP 1 year after PEA was positively associated with the decrease of HR/HL (Tl) (r=0.646, p<0.01) and HR/HL (BMIPP) (r=0.504, p<0.05) 1 year after PEA. Conclusions In patients with CTEPH, RV myocardial perfusion and fatty acid metabolism was upregulated and moderately correlated with mPAP. SPECT-guided 201Tl and 123I-BMIPP planar imaging is a novel and noninvasive imaging modality to assess the severity of PH. FUNDunding Acknowledgement Type of funding sources: None.

Diagnostic Performance of CMR, SPECT, and PET Imagings for the Detection of Cardiac Amyloidosis: A Meta-Analysis

Background: Noninvasive myocardial imaging modalities, such as cardiac magnetic resonance (CMR), single photon emission computed tomography (SPECT), and Positron emission tomography (PET), are well-established and extensively used to detect cardiac amyloid (CA). The purpose of this study is to directly compare CMR, SPECT, and PET scans in the diagnosis of CA, and to provide evidence for further scientific research and clinical decision-making.Methods: PubMed, Embase, and Cochrane Library were searched. Studies used CMR, SPECT and/or PET for the diagnosis of CA were included. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR), diagnostic odds ratio (DOR), their respective 95% confidence intervals (CIs) and the area under the summary receiver operating characteristic (SROC) curve (AUC) were calculated. Quality assessment of included studies was conducted.Results: A total of 31 articles were identified for inclusion in this meta-analysis. The pooled sensitivities of CMR, SPECT and PET was 0.84, 0.98 and 0.78, respectively. Their respective overall specificities were 0.87, 0.92 and 0.83. Subgroup analysis demonstrated that 99mTc-HMDP manifested the highest sensitivity (0.99). 99mTc-PYP had the highest specificity (0.95). The AUC values of 99mTc-DPD, 99mTc-PYP, 99mTc-HMDP were 0.89, 0.99, and 0.99, respectively. PET scan with 11C-PIB demonstrated a pooled sensitivity of 0.91 and specificity of 0.97 with an AUC value of 0.98.Conclusion: Our meta-analysis reveals that SEPCT scans present better diagnostic performance for the identification of CA as compared with other two modalities.

Modeling Left Ventricle Perfusion in Healthy and Stenotic Conditions

A theoretical fluid mechanical model is proposed for the investigation of myocardial perfusion in healthy and stenotic conditions. The model hinges on Terzaghi’s consolidation theory and reformulates the related unsteady flow equation for the simulation of the swelling–drainage alternation characterizing the diastolic–systolic phases. When compared with the outcome of experimental in vivo observations in terms of left ventricle transmural perfusion ratio (T.P.R.), the analytical solution provided by the present study for the time-dependent blood pressure and flow rate across the ventricle wall proves to consistently reproduce the basic mechanisms of both healthy and ischemic perfusion. Therefore, it could constitute a useful interpretative support to improve the comprehension of the basic hemodynamic mechanisms leading to the most common cardiac diseases. Additionally, it could represent the mathematical basis for the application of inverse methods aimed at estimating the characteristic parameters of ischemic perfusion (i.e., location and severity of coronary stenoses) via downstream ventricular measurements, possibly inspiring their assessment via non-invasive myocardial imaging techniques.

Added Prognostic Value of Plaque Burden to Computed Tomography Angiography and Myocardial Perfusion Imaging

Purpose: Cardiac computed tomographic angiography (CCTA) - derived measures of coronary artery disease (CAD) burden such as segment involvement score (SIS), which quantifies the number of segments with plaque, have been shown to independently predict incident cardiovascular events. We aimed to compare the added prognostic value of plaque burden to CCTA anatomic assessment and single photon emission computed tomography (SPECT) physiologic assessment in a high-risk cohort undergoing both tests.Methods: Consecutive patients who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected CAD at a tertiary care cardiology practice were included. Stenosis severity and SIS were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.)Results: A total of 956 patients were included. Mean age was 61.1 ± 14.2 years, 54% were men, 89% had hypertension, 81% had diabetes, 84% had dyslipidemia and 56% had recorded chest pain. Obstructive stenosis (left main ≥ 50%, all other coronary segments ≥ 70%) and ischemia were observed in similar number of patients (14%). After a median follow-up of 31 months, 102 patients (11%, 29.2 events per 1000 person-year) experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes and improved risk discrimination in models with CCTA obstructive stenosis (HR 1.15 95% CI 1.09 - 1.21 p= <0.001; Harrel’s C 0.74, p=0.008) and SPECT ischemia (HR 1.14 95% CI 1.08 - 1.20, p<0.001; Harrel’s C 0.76, p=0.019). Results were consistent using subgroups by plaque composition (calcified vs non-calcified) and lower thresholds of CCTA stenosis. Conclusion: Our results suggest that in high-risk patients with suspected CAD, plaque burden adds incremental prognostic value over established measures in predicting incident cardiovascular outcomes.

The prognostic value of 123I-mIBG SPECT cardiac imaging in heart failure patients: a systematic review

This systematic review aimed to evaluate the prognostic value of Iodine123 Metaiodobenzylguanidine (123I-mIBG) SPECT myocardial imaging in patients with heart failure (HF) and to assess whether semi-quantitative SPECT scores can be useful for accurate risk stratification concerning arrhythmic event (AE) and sudden cardiac death (SCD) in this cohort. A systematic literature search of studies published until November 2020 regarding the application of 123I-mIBG SPECT in HF patients was performed, in Pubmed, Scopus, Medline, Central (Cochrane Library) and Web Of Science databases, including the words “MIBG”, “metaiodobenzylguanidine”, “heart”, “spect”, and “tomographic”. The included studies had to correlate 123I-mIBG SPECT scores with endpoints such as overall survival and prevention of AE and SCD in HF patients. According to the sixteen studies included, the analysis showed that 123I-mIBG SPECT scores, such as summed defect score (SDS), regional wash-out (rWO), and regional myocardial tracer uptake, could have a reliable prognostic value in patients with HF. An increased SDS or rWO, as well as a reduced 123I-mIBG myocardial uptake, have proven to be effective in predicting AE- and SCD-specific risk in HF patients. Despite achieved results being promising, a more reproducible standardized method for semi-quantitative analysis and further studies with larger cohort are needed for 123I-mIBG SPECT myocardial imaging to be as reliable and, thus, accepted as the conventional 123I-mIBG planar myocardial imaging.