Dynamic SPECT Research Articles

The evaluation of combined fractional flow reserve and dynamic SPECT in chronic total occlusion

BackgroundChronic total occlusion (CTO) is the most challenging subset in percutaneous coronary intervention (PCI), but the optimal selection of patients and indication for such procedures remain a subject of debate. We sought to investigate the role of physiological function in treatment decisions of CTO PCI by measuring fractional flow reserve (FFR) and Dynamic SPECT imaging in this study. MethodsAll the FFR of CTO vessel were measured before and immediately after CTO revascularization, and Dynamic SPECT imaging were detected before PCI in patients with an identified CTO. ResultsA total of 53 patients with single-vessel CTO lesions were included in this cohort study. The mean FFR value was 0.34 ± 0.09 at baseline. Immediately after successful CTO PCI, the FFR value significantly increased to 0.79 ± 0.11. The regional coronary flow reserve (CFR) of CTO vessels was 1.62 ± 0.64, which was significantly and positively correlated with the baseline FFR value (r = 0.607, p = 0.005). The area under the ROC curve of the baseline FFR for the detection of ischemia was 0.923 (p < 0.001). The diagnostic performance in terms of sensitivity and specificity was 83.3 % and 85.7 % for baseline FFR with a ROC-optimized cutoff value of 0.35. ConclusionsA significant correlation was found between the CFR derived from dynamic SPECT and baseline FFR. An FFR of <0.35 before CTO PCI can be taken as the cutoff for the presence of inducible ischemia, which was a useful index for therapy options.

3D dynamic diuretic renal scintigraphy using a hybrid whole body CZT SPECT/CT camera protocol in the evaluation of acute ureteric obstruction caused by ureteric stone

PurposeTo investigate the performance of dynamic 3D diuretic renal scintigraphy using a hybrid whole body CZT SPECT/CT for the evaluation of acute ureteric obstruction in patients with urinary stone disease.Methods20 patients who presented to the Emergency Department with acute renal colic due to urinary stone disease confirmed by means of CT were prospectively included. Three observers evaluated and graded hydronephrosis, hydroureter, perirenal stranding, and thickening of the renal fascia from the CT as well as the renal scintigraphy curves from the dynamic SPECT study. The normalized residual activity from dynamic SPECT was analysed at 16 min in all patients and at 20 min in suspected obstruction.ResultsRenal scintigraphy curves showed a sensitivity of 100%, specificity of 93%, PPV 83% and a NPV 100% for obstruction, while normalized residual activity showed a sensitivity of 100%, specificity of 73%, PPV 56% and a NPV 100%. All patients presented at least 2 secondary signs of obstruction on the CT, showing a PPV of only 25% for obstruction.ConclusionDynamic 3D diuretic renal scintigraphy CZT SPECT/CT provides valuable functional and anatomical information from one single examination. The combination of pathological renogram curves and high normalized residual activity values provide the most valuable imaging information to determine the presence of acute ureteric obstruction. The secondary signs of obstruction observed on CT are not specific and should not be used to confirm or discard obstruction in patients with urinary stone disease.Trial registration: ISRCTN15338358. Registration date 03/01/2024. Retrospectively registered. https://www.isrctn.com/ISRCTN15338358?q=miguel%20ochoa%20figueroa&filters=&sort=&offset=1&totalResults=2&page=1&pageSize=10

Validation of advanced hybrid SPECT/CT system using dynamic anthropomorphic cardiac phantom

ObjectiveMyocardial blood flow (MBF) assessment can provide incremental diagnostic and prognostic information and thus the validation of dynamic SPECT is of high importance. We recently developed a novel cardiac phantom for dynamic SPECT validation and compared its performance against the GE Discovery NM 530c. We now report its use for validation of a new hybrid SPECT/CT System featuring advanced cadmium zinc telluride (CZT) technology in a ring array detector design (StarGuide™, GE HealthCare).MethodsOur recently developed cardiac phantom with injected technetium-99m radiotracer was used to create physiological time activity curves (TACs) for the left ventricular (LV) cavity and the myocardium. The TACs allow the calculation of uptake rate (K1) and MBF. The StarGuide system was used to acquire and process the TACs, and these were compared to the TACs produced by the phantom and its mathematical model. Fifteen (15) experiments with different doses representing various MBF values were conducted, and a standard statistic tool was applied for significance.ResultsThe TACs produced by the StarGuide system had a significant correlation (p < 0.001) with the reference TACs generated by the phantom both for the LV (r = 0.94) and for the myocardium (r = 0.89). The calculated MBF difference between the system and the phantom was 0.14 ± 0.16 ml/min/g and the average relative absolute difference was 13.2 ± 8.1%. A coefficient of variance of ≤ 11% was observed for all MBF subranges. The regional uptake rate values were similar to the global one with a maximum difference of 5%.ConclusionsOur newly developed dynamic cardiac phantom was used for validation of the dynamic hybrid SPECT/CT CZT-based system (StarGuide™, GE). The accuracy and precision of the system for assessing MBF values were high. The new StarGuide system can reliably perform dynamic SPECT acquisitions over a wide range of myocardial perfusion flow rates.

Higher processing repeatability of myocardial flow reserve calculated using net retention model compared to one compartment model in SPECT studies

Dynamic assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR) provides additional information that can improve diagnostic accuracy of radionuclide myocardial perfusion imaging in some clinical situations. This study assessed processing repeatability of these parameters calculated using two models—net retention (RET) and one compartment (1CM) in dynamic SPECT studies, using the latest version of Corridor 4DM software (v2024). Data of 107 patients were analyzed retrospectively (57 of whom were assessed in our previous study using 4DM v2015). Dynamic SPECT studies were carried out using a routine two-day rest-dipyridamole protocol. Data was processed in 4DM v2024 twice by one operator and once by another operator. Automatic heart image positioning during post-processing in 4DM v2024 was significantly improved compared to v2015, reducing the number of studies requiring extensive manual corrections from 41 to 12%. This significantly improved interobserver processing repeatability of MFR values in RCA territory compared to our previous study using v2015—from r = 0.67 to 0.85 (p = 0.0034). Interobserver processing repeatability of MBF and MFR in all 107 patients was significantly better in RET model compared to 1CM model. In conclusion, RET model is more reliable for calculating MBF and MFR values based on dynamic SPECT studies.

Evaluating dyNamic myocardial blood flow qUantitation as a Cost-effective care modeL for diabEtic patients with coronary artery diSease (NUCLEuS): A randomized controlled trial – Rationale and Design

BackgroundRecent advancements in quantifying myocardial blood flow (MBF) and coronary flow reserve using dynamic SPECT MPI have demonstrated comparable hemodynamic correlations with invasive angiography and PET. Implementation into routine practice, however, imposes attendant demands on resources. Diabetes mellitus is a rising pandemic associated with accelerated atherosclerosis, yet there is potential for under-detection of significant ischemia. ObjectivesWe postulate that quantifying myocardial blood flow (MBF) by dynamic SPECT reduces post-test resource utilization and improve economic efficiency over conventional SPECT. MethodsNUCLEuS is an ongoing prospective open-label randomized clinical trial that will enroll 300 diabetic patients without known coronary artery disease (CAD) referred clinically for SPECT MPI from March 2022 to March 2025. The aim is to determine the incremental prognostic value and post-test resource utilization of dynamic MBF over conventional SPECT in diabetic patients with suspected CAD. The primary endpoint is diagnostic failure, defined as unnecessary coronary angiography (absence of ≥50% stenosis in ≥1 coronary artery) or additional anatomical testing (e.g., coronary computed tomography angiography) within 90 days. Secondary endpoints are referrals for angiography or revascularization, escalation of anti-anginal medications, and quality-of-life scores at 12 months. Long-term endpoints are major adverse cardiovascular events (cardiac mortality, myocardial infarction, unstable angina, revascularization) within 36 months. The incremental cost-effectiveness ratio will be estimated based on cost and clinical effectiveness. ConclusionsNUCLEuS will be an imaging-directed clinical trial that will compare differences in outcomes and resource utilization of dynamic MBF over conventional SPECT MPI in the routine clinical management of CAD in diabetes mellitus.

Design and development of the DE-SPECT system: a clinical SPECT system for broadband multi-isotope imaging of peripheral vascular disease

Objective. Peripheral Vascular Disease (PVD) affects more than 230 million people worldwide and is one of the leading causes of disability among people over age 60. Nowadays, PVD remains largely underdiagnosed and undertreated, and requires the development of tailored diagnostic approaches. We present the full design of the Dynamic Extremity SPECT (DE-SPECT) system, the first organ-dedicated SPECT system for lower extremity imaging, based on 1 cm thick Cadmium Zinc Telluride (CZT) spectrometers and a dynamic dual field-of-view (FOV) synthetic compound-eye (SCE) collimator. Approach. The proposed DE-SPECT detection system consists of 48 1 cm thick 3D-position-sensitive CZT spectrometers arranged in a partial ring of 59 cm in diameter in a checkerboard pattern. The detection system is coupled with a compact dynamic SCE collimator that allows the user to select between two different FOVs at any time during an imaging study: a wide-FOV (28 cm diameter) configuration for dual-leg or scout imaging or a high-resolution and high-sensitivity (HR-HS) FOV (16 cm diameter) for single-leg or focused imaging. Main results. The preliminary experimental data show that the CZT spectrometer achieves a 3D intrinsic spatial resolution of <0.75 mm FWHM and an excellent energy resolution over a broad energy range (2.6 keV FWHM at 218, 3.3 keV at 440 keV). From simulations, the wide-FOV configuration offers a 0.034% averaged sensitivity at 140 keV and <8 mm spatial resolution, whereas the HR-HS configuration presents a peak central sensitivity of 0.07% at 140 keV and a ∼5 mm spatial resolution. The dynamic SCE collimator enables the capability to perform joint reconstructions that would ensure an overall improvement in imaging performance. Significance. The DE-SPECT system is a stationary and high-performance SPECT system that offers an excellent spectroscopic performance with a unique computer-controlled dual-FOV imaging capability, and a relatively high sensitivity for multi-tracer and multi-functional SPECT imaging of the extremities.

99m Tc-DTPA dynamic SPECT/CT renogram in adults: feasibility and diagnostic benefit.

The objective of this study is to investigate the feasibility and potential advantages of 99m Tc-DTPA dynamic single photon emission computed tomography/computed tomography (SPECT/CT) renogram in adults. Fifty-five patients aged 19-80 years (mean 56.3) were enrolled. The imaging protocol included: day 1: 99m Tc-DTPA planar renogram, followed by planar 99m Tc-DMSA scan. Day 3: attenuation-corrected dynamic 99m Tc-DTPA SPECT renogram [DSPECT(AC)] and Cr-51 ethylenediamine tetraacetic acid (EDTA) glomerular filtration rate (GFR) calculation. DSPECT(AC) included an initial CT scan followed by 12 consecutive SPECT sessions acquired via continuous-mode acquisition for a total of 24 min. Fast SPECT sequences (1-2 s/projection, 60 projections, every 6°) were obtained for the first 8 min, followed by slower acquisitions (3-4 s/projection) during the rest of the study. Renal activity was measured in the total kidney volume by regions of interest drawn on consecutive transaxial slices of the third SPECT, which were then copied on the whole 12-SPECT series. Corresponding time-activity curves were created. DSPECT(AC) parameters were compared with those of planar renogram. The reference method for split renal function was 99m Tc-DMSA (geometrical mean of anterior and posterior projection counts) and for GFR the Cr-51 EDTA 2-blood sample clearance method. DSPECT(AC) images were of good quality. There was good correlation between renogram parameters (time to peak activity and NORA20) comparing the two techniques ( r = 0.959 and 0.933, respectively). In 21 cases with >30% absolute difference between the two kidneys, spilt renal function calculation by DSPECT(AC) correlated perfectly ( r = 0.968) with the reference method, whereas planar renogram was less accurate ( r = 0.843). Anatomic information provided by nonenhanced CT offered an integrated structural-functional view valuable for final diagnosis. DSPECT(AC) early kidney uptake as a fraction of injected dose correlated better with reference GFR ( r = 0.789) than the Gates' method ( r = 0.642). 99m Tc-DTPA dynamic SPECT/CT renogram is feasible with conventional SPECT/CT systems. It allows accurate split renal function measurement, offers additional anatomical information and can be used for closer approximation of GFR compared with Gates' method.

Association of cardiac mechanical dyssynchrony indices with data of dynamic single-photon emission computed tomography of the myocardium: the role of the time interval between the stress test and recording

Introduction. According to ECG-synchronized myocardial perfusion imaging (MPI) mechanical dyssynchrony (MD) is a sensitive marker of impaired myocardial perfusion. However, its direct comparison with indicators of myocardial blood flow reserve (MFR) according to single-photon emission computed tomography (SPECT) was not carried out. Traditional MPI protocols imply a long gap between stress test and image acquisition, during which stress-induced changes may pass. It is potentially possible to reduce the time interval down to 5 minutes.Aim: To investigate the relationship between early and delayed MD indices and the data of MFR by means of SPECT.Material and Methods. The study included 20 patients with suspected coronary heart disease, preserved left ventricular ejection fraction (&gt; 55%) and without obstructive coronary artery lesions (&lt; 50%) according to multislice computed coronary angiography. All patients underwent dynamic SPECT (dSPECT) according to a two-day rest/stress protocol. Gated MPI was performed 60 minutes after radiopharmaceutical administration. Myocardial blood flow and reserve, as well as phase histogram standard deviation (PSD, degree) and phase histogram bandwidth (HBW, degree) from 5 minutes after radiopharmaceutical administration were obtained from the dSPECT data by postprocessing. Perfusion data as well as MD indices (PSD, HBW) were obtained from delayed images. Based on dSPECT data, patients were divided into 2 groups: with preserved (MFR ≥ 2.0) and reduced (MFR &lt; 2.0) myocardial blood flow reserve.Results. Correlation analysis showed that MD indices on stress test in early scan had a stronger association with MFR (PSD ρ = –0.68, p &lt; 0.001; HBW ρ = –0.68, p = 0.001) compared to those in delayed scan (PSD ρ = –0.38, p = 0.019; HBW ρ = –0.44, p = 0.005). According to multivariate regression analysis, PSD on stress test at early scan was the only independent predictor of reduced MFR (OR 1.29 (1.1; 1.53)). Stress PSD &gt; 22° obtained at early scanning had a sensitivity of 81% and specificity of 87% (AUC = 0.86, p &lt; 0.001) in predicting of reduced MFR.Conclusion. Left ventricular mechanical dyssynchrony indices obtained by early post-stress gated MPI have a stronger association with myocardial blood flow reserve indices.

Kidney dynamic SPECT acquisition on a CZT swiveling-detector ring camera: an in vivo pilot study

BackgroundLarge field of view CZT SPECT cameras with a ring geometry are available for some years now. Thanks to their good sensitivity and high temporal resolution, general dynamic SPECT imaging may be performed more easily, without resorting to dedicated systems. To evaluate the dynamic SPECT imaging by such cameras, we have performed an in vivo pilot study to analyze the kidney function of a pig and compare the results to standard dynamic planar imaging by a conventional gamma camera.MethodsA 7-week-old (12 kg) female Landrace pig was injected with [99mTc]Tc-MAG3 and a 30 min dynamic SPECT acquisition of the kidneys was performed on a CZT ring camera. A fast SPECT/CT was acquired with the same camera immediately after the dynamic SPECT, without moving the pig, and used for attenuation correction and drawing regions of interest. The next day the same pig underwent a dynamic planar imaging of the kidneys by a conventional 2-head gamma camera. The dynamic SPECT acquisition was reconstructed using a MLEM algorithm with up to 20 iterations, with and without attenuation correction. Time-activity curves of the total counts of each kidney were extracted from 2D and 3D dynamic images. An adapted 2-compartment model was derived to fit the data points and extract physiological parameters. Comparison of these parameters was performed between the different reconstructions and acquisitions.ResultsTime-activity curves were nicely fitted with the 2-compartment model taking into account the anesthesia and bladder filling. Kidney physiological parameters were found in agreement with literature values. Good agreement of these parameters was obtained for the right kidney between dynamic SPECT and planar imaging. Regional analysis of the kidneys can be performed in the case of the dynamic SPECT imaging and provided good agreement with the whole kidney results.ConclusionsDynamic SPECT imaging is feasible with CZT swiveling-detector ring cameras and provides results in agreement with dynamic planar imaging by conventional gamma cameras. Regional analysis of organs uptake and clearance becomes possible. Further studies are required regarding the optimization of acquisition and reconstruction parameters to improve image quality and enable absolute quantification.

Going beyond summed stress scores: Correlating global and territorial coronary flow reserve by single photon emission tomography with routine myocardial perfusion imaging

(a) BackgroundTechnological advancement in the recent years has enabled the application of single photon emission tomography (SPECT) to evaluate myocardial blood flow (MBF). This method offers increased sensitivity in the assessment of coronary health, quantifiable through non-invasive imaging beyond the more conventional methods such as with myocardial perfusion imaging (MPI). (b) AimsTo correlate MBF, derived by dynamic SPECT, both global and by coronary territories to the summed stress scores (SSS) on conventional MPI. (c) MethodsImages obtained from dipyridamole-gated SPECT MPI stress and rest studies performed on recruited subjects were examined. We calculated the global and regional coronary flow reserve (CFR) via a standard software package, taken as the ratio of stress MBF to rest MBF, using CFR<2.5 as the cut off. (d) ResultsAmongst the 90 recruited subjects (mean age 67 ± 8 years; of which 76% were males), 49% had MPI within normal limits (summed stress score (SSS) 0–3; Left ventricular ejection fraction (LVEF) > 50%). We observed a progressive reduction in global and regional CFR across the normal SSS category to that of severely abnormal (SSS >13). Reduced global CFR with correspondent lower CFR across the regional arteries were detected in scans within normal limits of MPI scans in subjects who were older (69 ± 7 vs. 62 ± 9 years, p = 0.034). Decreasing CFR was significantly associated with increasing age across the regional arteries. (e) ConclusionIn our study we depict the global and regional MBF values obtained via SPECT MPI in correlation to the respective SSS categories. Our data proposes that dynamic SPECT has a part in refining cardiac risk stratification, particularly in the older adult population, who are at greater risk.

Dynamic multi-pinhole collimated brain SPECT of Parkinson’s disease by [123I]FP-CIT: a feasibility study of fSPECT

We investigated the feasibility of using a dopamine transporter (DaT) tracer ligand ([123I]FP-CIT) along with novel multi-pinhole brain collimators for dynamic brain single photon emission computed tomography (SPECT) in suspected Parkinson's disease patients. Thirteen patients underwent dynamic tracer acquisitions before standard imaging. Uptake values were corrected for partial volume effects. Specific binding ratio (SBRcalc) was calculated, reflecting binding potential relative to non-displaceable binding (BPND) in the cortex. Additional pharmacokinetic parameters (BPND, R1, k2) were estimated using the simplified reference tissue model, revealing differences between Kahraman low-score (LS) and high-score (HS) groups. Results showed increasing striatal tracer uptake until 100 min post-injection, with consistent values afterward. Uptake and SBRcalc ratios matched visual assessment. LS patients had lower putamen than caudate nucleus tracer uptake, decreased BPND values, while R1 and k2 values were comparable to HS patients. In conclusion, dynamic multi-pinhole SPECT using DaT tracer with the extraction of pharmacokinetic parameters is feasible and could help enable early differentiation of reduced and normal DaT values.

The Influence of Kinetic Models and Attenuation Correction on Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography (CZT SPECT)-Derived Myocardial Blood Flow and Reserve: Correlation with Invasive Angiography Data.

(1) Background: The objective of this study was to determine the optimal post-processing model for dynamic cadmium-zinc-telluride single-photon emission computed tomography (CZT-SPECT). (2) Methods: A total of 235 patients who underwent diagnostic invasive coronary angiography within three months of the SPECT and those who had coronary computed tomography angiography (CCTA) before SPECT (within 3 months) were enrolled in this study. Each SPECT study was processed to obtain global and regional stress myocardial blood flow (sMBF), rest-MBF (rMBF), myocardial flow reserve (MFR) and flow difference (FD) estimates obtained with 1-tissue-compartment (1TCM) and net retention (NR) modes, both with and without attenuation correction. (3) Results: The use of AC led to significantly higher sMBF, rMBF and DF values obtained by 1TCM compared those values derived by 1TCM with NAC; the lowest values of stress MBF and rest MBF were obtained by 1TCM_NAC. The resting flow, MFR and DF were significantly (p < 0.005) higher in the AC model than in NAC. All quantitative variables were significantly (p < 0.05) higher in NR_NAC than in the 1TC_NAC model. Finally, sMBF, rMBF and FD showed significantly (p < 0.05) higher values by using 1TMC_AC compared to NR_AC. (4) Conclusions: We suggested that 1-compartment and net retention models correctly reflect coronary microcirculation and can be used for clinical practice for evaluating quantitative myocardial perfusion by dynamic SPECT. Attenuation correction is an important step in post-processing dynamic SPECT data, which increases the consistency and diagnostic accuracy of models.

Feasibility of myocardial blood flow quantification to detect flow-limited coronary artery disease with a one-day rest/stress continuous rapid imaging protocol on cardiac-dedicated cadmium zinc telluride single photon emission computed tomography

BackgroundIt is clinically needed to explore a more efficient imaging protocol for single photon emission computed tomography (SPECT) myocardial blood flow (MBF) quantitation derived from cadmium zinc telluride (CZT) SPECT camera for the routine clinical utilization. MethodsOne hundred and twenty patients with matched clinical characteristics and angiographic findings who completed one-day rest/stress SPECT imaging with either the intermittently sequential imaging (ISI) protocol (two dynamic and two electrocardiography (ECG)-gated scans) or the continuous rapid imaging (CRI) protocol (two dynamic/ECG-gated scans) were included. MBF quantitation adopted residual activity correction (RAC) to correct for rest residual activity (RRA) in the stress dynamic SPECT scan for the detection of flow-limited coronary artery disease. ResultsThe CRI protocol reduced about 6.2 times shorter than the ISI protocol (25.5 min vs 157.6 min), but slightly higher than the RRA (26.7% ± 3.6% vs 22.3% ± 4.9%). With RAC, both protocols demonstrated close stress MBF (2.18 ± 1.13 vs 2.05 ± 1.10, P > 0.05) and myocardial flow reserve (MFR) (2.42 ± 1.05 vs 2.48 ± 1.11, P > 0.05) to deliver comparable diagnostic performance (sensitivity = 82.1%–92.3%, specificity = 81.2%–91.2%). Myocardial perfusion and left ventricular function overall showed no significant difference (all P > 0.26). ConclusionOne-day rest/stress SPECT with the CRI protocol and rest RAC is feasible to warrant the diagnostic performance of MBF quantitation with a shortened examination time and enhanced patient comfort. Further evaluation on the impact of extracardiac activity to regional MBF and perfusion pattern is required. Additional evaluation is needed in a patient population that is typical of those referred for SPECT MPI, including those with known or suspected coronary microvascular disease.

Quantitative Coronary Computed Tomography Angiography And Dynamic Czt Spect Derived Myocardial Blood Flow In Patients With Non-obstructive Coronary Artery Disease

Quantitative Coronary Computed Tomography Angiography And Dynamic Czt Spect Derived Myocardial Blood Flow In Patients With Non-obstructive Coronary Artery Disease

Resolution recovery on list mode MLEM reconstruction for dynamic cardiac SPECT system

The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the Massachusetts General Hospital, featuring a static cardio focus asymmetrical geometry enabling simultaneous high-resolution and high-sensitivity imaging. Among 14 design iterations of the DC-SPECT with varying number of detector heads, system sensitivity and resolution, the current version under development features 10 mm FWHM geometrical resolution (without resolution recovery) and 0.07% sensitivity at the center of the FOV, this is 1.5× resolution gain and 7× sensitivity gain compared to a conventional dual head gamma camera (0.01% sensitivity and 15-mm resolution). This work presents improvement in imaging resolution by implementing a spatially variant point spread function (SV-PSF) with list mode MLEM reconstruction. A resolution recovery method by PSF deconvolution is validated on list mode MLEM reconstruction for the DC-SPECT. A spatial invariant PSF is included as an additional test to show the influence of the PSF modelling accuracy on reconstructed image quality. We compare the MLEM reconstruction with and without PSF deconvolution; an analytic model is used for the calculation of system response, and the results are compared to the reconstruction with system modelling using Monte Carlo (MC) based methods. Results show that with PSF modelling applied, the quality of the reconstructed image is improved, and the DC-SPECT system can achieve a 4.5 mm central spatial resolution with average 795 counts/Mbq. Both the SV-PSF and the spatial-invariant PSF improve the image quality, and the reconstruction with SV-PSF generates line profiles closer to the ground truth. The results show substantial improvement over the GE Discovery 570c performance (7 mm spatial resolution with an average 460 counts/MBq, 5.8 mm resolution at the FOV center). The impact of PSF deconvolution is significant, improvement of the reconstructed image quality is evident in comparison to MC simulated system matrix with the same sampling size in the simulation.

A Comparison of Dynamic SPECT Coronary Flow Reserve with TIMI Frame Count in the Treatment of Non-Obstructive Epicardial Coronary Patients.

Microvascular dysfunction in patients with non-obstructive epicardial coronary may aggravate patient's symptoms or lead to various clinical events. To investigate the correlation between dynamic single photon emission computed tomography (D-SPECT) derived coronary flow reserve (CFR) and TIMI frame count (TFC) in patients with non-obstructive epicardial coronary patients. Patients with suspected or known stable CAD who were recommended to undergo invasive coronary angiography were prospectively enrolled in this study. Those who had non-obstructive coronary received TIMI frame count (TFC) and D-SPECT. A cut-off value of >40 was defined as slow flow referred to TFC. A total of 47 patients diagnosed with non-obstructive coronary were enrolled. The mean age of patients was 66.09 ± 8.36 years, and 46.8% were male. Dynamic SPECT derived coronary flow reserve (CFR) was significantly correlated with TIMI frame count in 3 epicardial coronary (LAD: r=-0.506, P = 0.0003; LCX: r= -0.532, P = 0.0001; RCA: r= -0.657, P < 0.0001). The sensitivity and specificity of CFR in identifying abnormal TIMI frame count < 40 was 100.0% and 57.6% in LAD, 62.5% and 87.0% in LCX, 83.9% and 75.0% in RCA, respectively. The optimal CFR cut-off values were 2.02, 2.47, and 1.96 among the three vessels. In patients with non-obstructive coronary, CFR derived from D-SPECT was strongly correlated with TFC. This study demonstrates that that CFR may be an alternative non-invasive method for identifying slow flow in non-obstructive coronary.

Quantitative assessment of myocardial blood flow by dynamic single photon emission computed tomography: relationship with ECG changes and biochemical markers of damage in patients with acute myocardial infarction

Aim: To study the relationship of microcirculatory changes in coronary bed and electrocardiographic and laboratory signs of damage to myocardium in patients with acute myocardial infarction (AMI).Methods. The observational study included patients with newly emerged AMI. Depending on the ECG changes, the patients were divided into two groups: 1) with ST segment elevation (n = 75) (STEMI) and 2) without ST segment elevation (n = 44) (NSTEMI). All patients underwent electrocardiography, analysis of biochemical markers of myocardial damage, dynamic single photon emission computed tomography (SPECT) and myocardial perfusion imaging.Results. The study included 119 patients (age 62.5 ± 10.4 years, 63% men). STEMI patients had heavier perfusion defects at rest, 5.00 (3.00;9.00) and 0.00 (0.00;1.00), and after pharmacological stress test, 7.00 (5.00;13.00) and 2.50 (0.00;5.00), also they had more reduced stress myocardial blood flow (MBF), 1.09 (0.83;1.59) and 1.67 (1.36;2.46) ml/min/g, flow difference (FD), 0.36 (0.01;0.72) and 1.14 (0.63;1.72) ml/min/g, and myocardial flow reserve (MFR), 1.78 (1.11;2.19) and 2.57 (2.13;3.31), according to compared to NSTEMI patients. Correlation analysis revealed significant relationships between stress MBF and CPK after 24 hours and 4 days: r = –0.34 and r = = –0.31, troponin I upon admission and after 24 hours – r = –0.4 and r = –0.3; MFR and FD and troponin I upon admission – r = –0.41 and r = –0.41.Conclusion. Quantitative parameters of myocardial perfusion determined by early dynamic myocardial SPECT are associated with electrocardiographic changes and biochemical markers of myocardial damage and allow an adequate assessment of the severity of the disease in patients with AMI.

Dynamic perfusion SPECT for functional evaluation in symptomatic patients with myocardial bridging

BackgroundThe aim of this study was to investigate the feasibility and diagnostic value of myocardial flow reserve (MFR) assessed by rest/stress myocardial perfusion imaging with dynamic single-photon emission computed tomography (SPECT) in the functional evaluation of myocardial bridge (MB). MethodsFrom May 2017 to July 2021, patients with angiographically confirmed isolated MB on the left anterior descending artery (LAD) who underwent dynamic SPECT myocardial perfusion imaging were retrospectively included. The assessment of semiquantitative indices of myocardial perfusion (summed stress scores, SSS) and quantitative parameters (MFR) was performed. ResultsA total of 49 patients were enrolled. The mean age of the subjects was 61.0 ± 9.0 years. All of the patients were symptomatic, and 16 cases (32.7%) presented with typical angina. SPECT-derived MFR showed a borderline significantly negative correlation with SSS (r = 0.261, P = .070). There was a trend of higher prevalence of impaired myocardial perfusion defined as MFR < 2 than as SSS ≥ 4 (42.9% vs 26.5%; P = .090). ConclusionOur data support that SPECT MFR may be a useful parameter for the functional assessment of MB. In patients with MB, the use of dynamic SPECT could be a potential method for hemodynamic assessment.

Dynamic CZT-SPECT: Characterizing the Lower Values of Myocardial Blood Flow and Reserve.

CZT-SPECT myocardial perfusion enables quantification of myocardial blood flow (MBF). Normal values and thresholds have been accurately defined in PET but remain unclear in SPECT. The aim of this study was to report normal MBF and myocardial flow reserve values in very low-risk patients referred for coronary artery disease screening with dynamic SPECT, in comparison with patients experiencing coronary artery disease. Eighty-four patients (31 male) were analyzed. The mean 10 years risk of fatal cardiovascular events score was 2.7% ± 1.4%. The mean global stress MBF and myocardial flow reserve were 1.6 ± 0.6 mL/min/g and 2.7 ± 0.7.

Dose-consistent dynamic SPECT

BackgroundCoronary flow reserve (CFR) values measured by dynamic SPECT systems are typically consistent with other modalities (e.g., PET). However, large discrepancies are often observed for individual patients. Positioning of the region-of-interest (ROI), representing the arterial input function (AIF) could explain some of these discrepancies. We explored the possibility of positioning the ROI in a manner that evaluates its consistency with patient-based injected radiotracer doses. MethodsDose-consistent dynamic SPECT methodology was introduced, and its application was demonstrated in a twenty-patient clinical study. The effect of various ROI positions was investigated and comparison to myocardial perfusion imaging was performed. ResultsMean AIF ratios were consistent with the injected dose ratios for all examined ROI positions. Good agreement (> 80%) between total perfusion deficit and CFR was found in the detection of obstructive CAD patients for all ROIs considered. However, for individual patients, significant dependence on ROI position was observed (altering CFR by typically 30%). The proposed methodology’s uncertainty was evaluated (~ 7%) and found to be smaller than the variability due to choice of ROI position. ConclusionDose-consistent dynamic SPECT may contribute to evaluating uncertainty of CFR measurements and may potentially decrease uncertainty by allowing improved ROI positioning for individual patients.