Dataset Information

Experimental validation of absolute SPECT/CT quantification for response monitoring in patients with coronary artery disease.

ABSTRACT:

Background

Quantitative SPECT enables absolute quantification of uptake in perfusion defects. The aim of this experimental study is to assess quantitative accuracy and precision of a novel iterative reconstruction technique (Evolution; GE Healthcare) for the potential application of response monitoring using ^99mTc-tetrofosmin SPECT/CT in patients with coronary artery disease (CAD).

Methods

Acquisitions of an anthropomorphic torso phantom with cardiac insert containing defects (with varying sizes), filled with ^99mTc-pertechnetate, were performed on a SPECT/CT (Discovery 670 Pro, GE Healthcare). Subsequently, volumes of interest of the defects were manually drawn on CT to assess the recovery coefficient (RC). Bull's eye plots were composed to evaluate the uptake per segment. Finally, ^99mTc-tetrofosmin SPECT/CT scans of 10 CAD patients were used to illustrate clinical application.

Results

The phantom study indicated that Evolution showed convergence after 7 iterations and 10 subsets. The average repeatability deviation of all configurations was 2.91% and 3.15% (%SD mean) for filtered (Butterworth) and unfiltered data, respectively. The accuracy after post-filtering was lower compared to the unfiltered data with a mean (SD) RC of 0.63 (0.05) and 0.70 (0.07), respectively (p < 0.05). More artificial defects were found on Bull's eye plots created with the unfiltered data compared to filtered data. Eight out of ten patients showed significant changes in uptake before and after treatment (p < 0.05).

Conclusion

Quantification of ^99mTc-tetrofosmin SPECT/CT seems feasible for CAD patients when 7 iterations (10 subsets), Butterworth post-filtering (cut off frequency 0.52 in cycles/cm, order of 5) and manual CT-delineation are applied. However, future prospective patient studies are required for clinical application.

SUBMITTER: van de Burgt A

PROVIDER: S-EPMC8208344 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Accurate and reproducible SPECT quantification of myocardial molecular processes remains a challenge because of the complication of heterogeneous background and extracardiac activity adjacent to the heart, which causes errors in the estimation of myocardial focal tracer uptake. Our aim in this study was to introduce a heuristic method for the correction of extracardiac activity into SPECT quantification and validate the modified quantification method for accuracy and reproducibility using a canine model.Dual-isotope-targeted (99m)Tc and (201)Tl perfusion SPECT images were acquired using a hybrid SPECT/CT camera in 6 dogs at 2 wk after myocardial infarction. Images were reconstructed with and without CT-based attenuation correction, and the reconstructed SPECT images were filtered and quantified simultaneously with incorporation of extracardiac radioactivity correction, gaussian fitting, and total-count sampling. Absolute myocardial focal tracer uptake was quantified from SPECT images using 3 different normal limits (maximum entropy [ME], mean-squared-error minimization [MSEM], and global minimum [GM]). SPECT-quantified percentage injected dose (%ID) was calculated and compared with the well-counted radioactivity measured from the postmortem myocardial tissue. SPECT quantitative processing was performed by 2 different individuals with extensive experience in cardiac image processing, to assess reproducibility of the quantitative analysis.Correlations between SPECT-quantified and well-counted %IDs using 3 different normal limits were excellent (ME: r = 0.82, y = 0.932 x - 0.0102; MSEM: r = 0.73, y = 1.1413 x - 0.0052; and GM: r = 0.7, y = 1.2147 x - 0.0002). SPECT quantification using ME normal limits resulted in an underestimation of %ID, as compared with well-counted %ID. Myocardial focal tracer uptake quantified from SPECT images without CT-based attenuation correction was significantly lower than that with the attenuation correction. The %IDs quantified from attenuation-corrected SPECT images using MSEM and GM normal limits were not significantly different from well-counted %IDs. Reproducibility of the SPECT quantitative analysis was excellent (ME: r = 0.98, y = 0.9221 x + 0.0001; MSEM: r = 0.97, y = 0.9357 x + 0.0004; and GM: r = 0.96, y = 0.9026 x + 0.001).Our SPECT/CT quantification algorithm for the assessment of regional radioactivity may allow for accurate and reproducible serial noninvasive evaluation of molecularly targeted tracers in the myocardium.

Project description:Absolute quantification of radiotracer distribution using SPECT/CT imaging is of great importance for dosimetry aimed at personalized radionuclide precision treatment. However, its accuracy depends on many factors. Using phantom measurements, this multi-vendor and multi-center study evaluates the quantitative accuracy and inter-system variability of various SPECT/CT systems as well as the effect of patient size, processing software and reconstruction algorithms on recovery coefficients (RC). METHODS:Five SPECT/CT systems were included: Discovery™ NM/CT 670 Pro (GE Healthcare), Precedence™ 6 (Philips Healthcare), Symbia Intevo™, and Symbia™ T16 (twice) (Siemens Healthineers). Three phantoms were used based on the NEMA IEC body phantom without lung insert simulating body mass indexes (BMI) of 25, 28, and 47 kg/m2. Six spheres (0.5-26.5 mL) and background were filled with 0.1 and 0.01 MBq/mL 99mTc-pertechnetate, respectively. Volumes of interest (VOI) of spheres were obtained by a region growing technique using a 50% threshold of the maximum voxel value corrected for background activity. RC, defined as imaged activity concentration divided by actual activity concentration, were determined for maximum (RCmax) and mean voxel value (RCmean) in the VOI for each sphere diameter. Inter-system variability was expressed as median absolute deviation (MAD) of RC. Acquisition settings were standardized. Images were reconstructed using vendor-specific 3D iterative reconstruction algorithms with institute-specific settings used in clinical practice and processed using a standardized, in-house developed processing tool based on the SimpleITK framework. Additionally, all data were reconstructed with a vendor-neutral reconstruction algorithm (Hybrid Recon™; Hermes Medical Solutions). RESULTS:RC decreased with decreasing sphere diameter for each system. Inter-system variability (MAD) was 16 and 17% for RCmean and RCmax, respectively. Standardized reconstruction decreased this variability to 4 and 5%. High BMI hampers quantification of small lesions (< 10 ml). CONCLUSION:Absolute SPECT quantification in a multi-center and multi-vendor setting is feasible, especially when reconstruction protocols are standardized, paving the way for a standard for absolute quantitative SPECT.

Project description:BackgroundQuantitative SPECT imaging in targeted radionuclide therapy with lutetium-177 holds great potential for individualized treatment based on dose assessment. The establishment of dose-effect relations requires a standardized method for SPECT quantification. The purpose of this multi-center study is to evaluate quantitative accuracy and inter-system variations of different SPECT/CT systems with corresponding commercially available quantitative reconstruction algorithms. This is an important step towards a vendor-independent standard for quantitative lutetium-177 SPECT.MethodsFour state-of-the-art SPECT/CT systems were included: Discovery™ NM/CT 670Pro (GE Healthcare), Symbia Intevo™, and two Symbia™ T16 (Siemens Healthineers). Quantitative accuracy and inter-system variations were evaluated by repeatedly scanning a cylindrical phantom with 6 spherical inserts (0.5 - 113 ml). A sphere-to-background activity concentration ratio of 10:1 was used. Acquisition settings were standardized: medium energy collimator, body contour trajectory, photon energy window of 208 keV (± 10%), adjacent 20% lower scatter window, 2 × 64 projections, 128 × 128 matrix size, and 40 s projection time. Reconstructions were performed using GE Evolution with Q.Metrix™, Siemens xSPECT Quant™, Siemens Broad Quantification™ or Siemens Flash3D™ algorithms using vendor recommended settings. In addition, projection data were reconstructed using Hermes SUV SPECT™ with standardized reconstruction settings to obtain a vendor-neutral quantitative reconstruction for all systems. Volumes of interest (VOI) for the spheres were obtained by applying a 50% threshold of the sphere maximum voxel value corrected for background activity. For each sphere, the mean and maximum recovery coefficient (RCmean and RCmax) of three repeated measurements was calculated, defined as the imaged activity concentration divided by the actual activity concentration. Inter-system variations were defined as the range of RC over all systems.ResultsRC decreased with decreasing sphere volume. Inter-system variations with vendor-specific reconstructions were between 0.06 and 0.41 for RCmean depending on sphere size (maximum 118% quantification difference), and improved to 0.02-0.19 with vendor-neutral reconstructions (maximum 38% quantification difference).ConclusionThis study shows that eliminating sources of possible variation drastically reduces inter-system variation in quantification. This means that absolute SPECT quantification for 177Lu is feasible in a multi-center and multi-vendor setting; however, close agreement between vendors and sites is key for multi-center dosimetry and quantitative biomarker studies.

Project description:BackgroundThe digital cadmium-zinc-telluride (CZT)-based SPECT system has many advantages, including better spatial and energy resolution. However, the impacts of different acquisition and reconstruction parameters on CZT SPECT quantification might still need to be validated. This study aimed to evaluate the impacts of acquisition parameters (the main energy window and acquisition time per frame) and reconstruction parameters (the number of iterations, subsets in iterative reconstruction, post-filter, and image correction methods) on the technetium quantification of CZT SPECT/CT.MethodsA phantom (PET NEMA/IEC image quality, USA) was filled with four target-to-background (T/B) ratios (32:1, 16:1, 8:1, and 4:1) of technetium. Mean uptake values (the calculated mean concentrations for spheres) were measured to evaluate the recovery coefficient (RC) changes under different acquisition and reconstruction parameters. The corresponding standard deviations of mean uptake values were also measured to evaluate the quantification error. Image quality was evaluated using the National Electrical Manufacturers Association (NEMA) NU 2-2012 standard.ResultsFor all T/B ratios, significant correlations were found between iterations and RCs (r = 0.62-0.96 for 1-35 iterations, r = 0.94-0.99 for 35-90 iterations) as well as between the full width at half maximum (FWHM) of the Gaussian filter and RCs (r = - 0.86 to - 1.00, all P values < 0.05). The regression coefficients of 1-35 iterations were higher than those of 35-90 iterations (0.51-1.60 vs. 0.02-0.19). RCs calculated with AC (attenuation correction) + SC (scatter correction) + RR (resolution recovery correction) combination were more accurate (53.82-106.70%) than those calculated with other combinations (all P values < 0.05). No significant statistical differences (all P values > 0.05) were found between the 15% and 20% energy windows except for the 32:1 T/B ratio (P value = 0.023) or between the 10 s/frame and 120 s/frame acquisition times except for the 4:1 T/B ratio (P value = 0.015) in terms of RCs.ConclusionsCZT-SPECT/CT of technetium resulted in good quantification accuracy. The favourable acquisition parameters might be a 15% energy window and 40 s/frame of acquisition time. The favourable reconstruction parameters might be 35 iterations, 20 subsets, the AC + SC + RR correction combination, and no filter.

Project description:AimsTafamidis treatment positively affects left ventricular (LV) structure and function and improves outcomes in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). We aimed to investigate the relationship between treatment response and cardiac amyloid burden identified by serial quantitative 99mTc-DPD SPECT/CT. We furthermore aimed to identify nuclear imaging biomarkers that could be used to quantify and monitor response to tafamidis therapy.Methods and resultsForty wild-type ATTR-CM patients who underwent 99mTc-DPD scintigraphy and SPECT/CT imaging at baseline and after treatment with tafamidis 61 mg once daily [median, 9.0 months (interquartile range 7.0-10.0)] were divided into two cohorts based on the median (-32.3%) of the longitudinal percent change in standardized uptake value (SUV) retention index. ATTR-CM patients with a reduction greater than or equal to the median (n = 20) had a significant decrease in SUV retention index (P < 0.001) at follow-up, which translated into significant benefits in serum N-terminal prohormone of brain natriuretic peptide levels (P = 0.006), left atrial volume index (P = 0.038), as well as LV [LV global longitudinal strain: P = 0.028, LV ejection fraction (EF): P = 0.027, LV cardiac index (CI): P = 0.034] and right ventricular (RV) [RVEF: P = 0.025, RVCI: P = 0.048] functions compared with patients with a decrease less than the median (n = 20).ConclusionTreatment with tafamidis in ATTR-CM patients results in a significant reduction in SUV retention index, associated with significant benefits for LV and RV function and cardiac biomarkers. Serial quantitative 99mTc-DPD SPECT/CT imaging with SUV may be a valid tool to quantify and monitor response to tafamidis treatment in affected patients.Translational perspective99mTc-DPD SPECT/CT imaging with determination of SUV retention index as part of a routine annual examination can provide evidence of treatment response in ATTR-CM patients receiving disease-modifying therapy. Further long-term studies with 99mTc-DPD SPECT/CT imaging may help to evaluate the relationship between tafamidis-induced reduction in SUV retention index and outcome in patients with ATTR-CM and will demonstrate whether highly disease-specific 99mTc-DPD SPECT/CT imaging is more sensitive than routine diagnostic monitoring.

Project description:Purpose To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). Materials and Methods All patients gave written informed consent prior to inclusion in this institutional review board-approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. Results The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P < .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P < .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). Conclusion This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. © RSNA, 2017 Online supplemental material is available for this article.

Project description:BACKGROUND:[123I]epidepride is a high-affinity radiotracer used in single-photon emission computed tomography (SPECT) imaging of the D2/3 receptors. It binds with high affinity to striatal and extrastriatal receptors. Nevertheless, its slow kinetics in the striatum impedes quantification in this region. Thus, an approach that would allow a simultaneous quantification of both striatal and extrastriatal D2/3 receptors would be of interest for preclinical and clinical SPECT neuroimaging. We describe a partial saturation protocol that allows us to produce an in vivo Scatchard plot and thus estimate Bavail and appKd separately in both striatal and extrastriatal regions, through a single dynamic SPECT session. To validate this approach, a multi-injection protocol is used for the full kinetic modeling of [123I]epidepride using a two-tissue compartment, 5-parameter model (2T-5k). METHODS:Eighteen male rats were used. Binding parameters were estimated using the multi-injection protocol. Various simulations were performed to estimate the optimal conditions for the partial saturation protocol, which was applied at the region and voxel level. The results of the partial saturation study were compared to those obtained with the 2T-5k model. To illustrate the interest of the partial saturation approach, we performed a preliminary study of the effect of a chronic, subcutaneous administration of haloperidol (1?mg/kg/day), a D2 receptor antagonist, on the Bavail of [123I]epidepride in the rat striatum. RESULTS:A series of simulations demonstrated that a mass of 3 ug/kg of unlabeled epidepride allows the formation of an in vivo Scatchard plot. The partial saturation study led to robust estimations of Bavail in all brain regions that highly correlated (r = 0.99) with the corresponding values from the multi-injection study. A chronic haloperidol treatment resulted in a 17.9% increase in the Bavail values in the left Caudate Putamen nucleus (CP) (p = 0.07) and a 13.8% increase in the right CP (p = 0.12). CONCLUSION:A partial saturation method allowed the robust quantification of D2/3 receptors in striatal and extrastriatal D2/3 receptors with a single-scan approach. This approach may be applied in the mapping of the D2/3 receptor in translational biological studies and potentially, in clinical SPECT imaging.