Ultra-fast whole-body bone tomoscintigraphies achieved with a high-sensitivity 360° CZT camera and a dedicated deep-learning noise reduction algorithm.

This study aimed to determine whether the whole-body bone Single Photon Emission Computed Tomography (SPECT) recording times of around 10 min, routinely provided by a high-sensitivity 360° cadmium and zinc telluride (CZT) camera, can be further reduced by a deep-learning noise reduction (DLNR) algorithm. METHODS: DLNR was applied on whole-body images recorded after the injection of 545 ± 33 MBq of [99mTc]Tc-HDP in 19 patients (14 with bone metastasis) and reconstructed with 100%, 90%, 80%, 70%, 60%, 50%, 40%, and 30% of the original SPECT recording times. RESULTS: Irrespective of recording time, DLNR enhanced the contrast-to-noise ratios and slightly decreased the standardized uptake values of bone lesions. Except in one markedly obese patient, the quality of DLNR processed images remained good-to-excellent down to 60% of the recording time, corresponding to around 6 min SPECT-recording. CONCLUSION: Ultra-fast SPECT recordings of 6 min can be achieved when DLNR is applied on whole-body bone 360° CZT-SPECT.

Assessment of the routine reporting of very low-dose exercise-first myocardial perfusion SPECT from a large-scale real-world cohort and correlation with the subsequent reporting of coronary stenosis at angiography.

PURPOSE: Our study assesses the routine reporting of exercise ischemia using very low-dose exercise-first myocardial perfusion SPECT in a large number of patients and under real-life conditions, by evaluating correlations with the subsequent routine reporting of coronary stenosis by angiography and with factors that predict ischemia. METHODS: Data from 13,126 routine exercise MPI reports, from 11,952 patients (31% women), using very low doses of sestamibi and a high-sensitivity cardiac CZT camera, were extracted to assess the reporting of significant MPI-ischemia (> 1 left ventricular segment), to determine the MPI normalcy rate in a group with < 5% pretest probability of coronary artery disease (CAD) (n = 378), and to assess the ability of MPI to predict a > 50% coronary stenosis in patients with available coronary angiography reports in the 3 months after the MPI (n = 713). RESULTS: The median effective patient dose was 2.51 [IQR: 1.00-4.71] mSv. The normalcy rate was 98%, and the MPI-ischemia rate was independently predicted by a known CAD, the male gender, obesity, and a < 50% LV ejection fraction, ranging from 29.5% with all these risk factors represented to 1.5% when there were no risk factors. A > 50% coronary stenosis was significantly predicted by MPI-ischemia, less significantly for mild (odds ratio [95% confidence interval]: 1.61 [1.26-1.96]) than for moderate-to-severe MPI-ischemia (4.05 [3.53-4.57]) and was also impacted by having a known CAD (2.17 [1.83-2.51]), by a submaximal exercise test (1.48 [1.15-1.81]) and being ≥ 65 years of age (1.43 [1.11-1.76]). CONCLUSION: Ischemia detected using a very low-dose exercise-first MPI protocol in a large-scale clinical cohort and under real-life routine conditions is a highly significant predictor for the subsequent reporting of coronary stenosis, although this prediction is enhanced by other variables. This weakly irradiating approach is amenable to being repeated at shorter time intervals, in target patient groups with a high probability of MPI-ischemia.

Integration of quantitative absolute myocardial blood flow estimates from dynamic CZT-SPECT improves the detection of coronary artery disease.

BACKGROUND: Balanced ischemia with multi-vessel coronary artery disease (CAD) is difficult to diagnose with semiquantitative single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Dynamic cardiac SPECT provides quantitative estimations of stenosis severity and ischemic burden by assessing myocardial flow reserve (MFR) and myocardial blood flow (MBF). The aim of this study was to evaluate the incremental value of dynamic SPECT in multi-vessel coronary artery disease (CAD). METHODS: Patients with suspected CAD who underwent dynamic ECG-gated dipyridamole MPI and coronary angiography within 6 months were retrospectively reviewed. The performance of summed stress, rest and difference scores (SSS, SRS, SDS), post-stress and resting MBF (MBFs, MBFr) and MFR were compared at both patient level and vessel level. RESULTS: In 32 patients with 39 stenotic vessels, 12 had three-vessel disease (38%). Globally increased SSS and impaired MBF values were significantly associated with significant CAD at the patient level, but SDS and MFR were not. Regional increases in SSS and reductions in both MBFs and MBFr were significantly associated with stenotic vessels. The best cutoff value of global MBFs to predict CAD was 3.5 ml·g-1·min-1 (area under the curve, AUC = .84, P = .002). The best cutoff value of regional MBFs to detect significant stenosis was 3.6 ml·g-1·min-1 (AUC = .74, P < .001). However, the best possible cut-off values of MFR were not found. Sex-difference in both global and regional MBFr but MBFs was found, which might result in the non-significance in MFR. CONCLUSIONS: This study validated a clinically available method to quantify MFR using dynamic CZT-SPECT. This method improved the detectability of multi-vessel CAD, and absolute MBFs was superior to MFR and other semiquantitative MPI parameters.

Transthyretin Cardiac Amyloidosis Scintigraphy Using Planar D-SPECT on Dedicated Cardiac CZT Camera.

BACKGROUND: Bone scintigraphy is a main diagnostic tool in suspected ATTR patients. Almost all literature is based on conventional whole body gamma cameras, and there is very sparse data evaluating the use of dedicated cardiac CZT cameras. The aim of this study was to evaluate the utility of bone scintigraphy in suspected transthyretin cardiac amyloidosis (ATTR-CA) patients on a dedicated cardiac CZT camera. METHODS: Seventy-three patients with suspected ATTR-CA underwent planar and SPECT Tc-99 m pyrophosphate scintigraphy using dedicated cardiac CZT camera between May and August 2019. RESULTS: Planar D-SPECT image quality was mostly good. Six patients were identified as ATTR-CA positive. Inter-observer agreement based on both Perugini score and on planar D-SPECT H/CL ratio was excellent. CONCLUSIONS: ATTR-CA scintigraphy using dedicated cardiac CZT camera was feasible, and yielded planar D-SPECT images with excellent inter-observer agreement.

Feasibility of simultaneous 99mTc-tetrofosmin and 123I-BMIPP dual-tracer imaging with cadmium-zinc-telluride detectors in patients undergoing primary coronary intervention for acute myocardial infarction.

BACKGROUND: Simultaneous dual-tracer imaging using isotopes with close photo-peaks may benefit from improved properties of cadmium-zinc-telluride (CZT)-based scanners. METHODS: Thirty patients having undergone primary percutaneous coronary intervention for acute myocardial infarction underwent single-(99mTc-tetrofosmin (TF) or 123I-BMIPP first) followed by simultaneous 99mTc-TF /123I-BMIPP dual-tracer imaging using a Discovery NM/CT 670 CZT. The values for the quantitative gated-SPECT (QGS) and the quantitative perfusion SPECT (QPS) were assessed. RESULTS: The intra-class correlation (ICC) coefficients between the single- and dual-tracer imaging were high in all the QGS and QPS data (Summed motion score: 0.95, summed thickening score: 0.94, ejection fraction: 0.98, SRS for 99mTc-TF: 0.97/ for 123I-BMIPP: 0.95). Wall motion, wall thickening and rest scores per coronary-territory-based regions were also comparable between the single- and dual imaging (ICC coefficient > 0.91). The interrater concordance in the visual analysis for the infarction and perfusion-metabolism mismatch was significant for the global and regional left ventricle (P < 0.001). CONCLUSION: The quantitative/semi-quantitative values for global and regional left-ventricular function, perfusion, and fatty acid metabolism were closely comparable between the dual-tracer imaging and the single-tracer mode. These data suggests the feasibility of the novel CZT-based scanner for the simultaneous 99mTc-TF /123I-BMIPP dual-tracer acquisitions in clinical settings.

Absolute myocardial blood flows derived by dynamic CZT scan vs invasive fractional flow reserve: Correlation and accuracy.

PURPOSE: To define the diagnostic power of absolute myocardial blood flow (MBF) evaluation on dynamic CZT imaging in intermediate risk patients in comparison with invasive coronary angiography (ICA) and fractional flow reserve (FFR). METHODS: Twenty-three stable CAD patients underwent one-day dynamic rest-stress 99mTc-Sestamibi myocardial perfusion imaging by CZT camera. Stress and rest MBF values were calculated semi-automatically using a net retention model by Leppo. Coronary flow reserve (CFR) and flow difference (FD) [MBF stress - MBF rest] were also estimated. A total of 28 vessels were functionally quantified with FFR: 19 (68%) vessels with a stenosis ≥ 70% and 9 (32%) with < 70% stenotic lesions. RESULTS: The mean global MBFs at rest and during stress were 0.36 (IQR 0.33-0.54) mL/min/g and 0.67 (IQR 0.55-0.81) mL/min/g, respectively, with an average CFR of 1.80 (IQR 1.35-2.24). Moderate correlations between stenosis severity and FFR (r = 0.45; P = .01), stress MBF (r = -0.46; P = .01) and FD (r = -0.37; P = .04) were detected. FFR abnormalities were best predicted by absolute stress MBF, CFR and FD with values of ≤ 0.54 mL/min/g (sensitivity 61.5%; specificity 93.3%), ≤ 1.48 (sensitivity 69.2%; specificity 93.3%) and ≤ 0.18 mL/min/g (sensitivity 69.2%; specificity 100%), respectively. CONCLUSIONS: The values of stress MBF, CFR and FD obtained through dynamic CZT acquisitions compare well with invasive FFR. The clinical use of dynamic acquisition of myocardial perfusion imaging by CZT may help cardiologist in the detection of hemodynamically significant CAD.

Low-dose dynamic myocardial perfusion imaging by CZT-SPECT in the identification of obstructive coronary artery disease.

BACKGROUND: We measured myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by a dynamic low-dose CZT-SPECT protocol in patients with suspected or known coronary artery disease (CAD) and investigated the capability of dynamic data in predicting obstructive CAD. A total of 173 patients with suspected or known CAD underwent dynamic CZT-SPECT after the injection of 155 MBq and 370 MBq of 99mTc-sestamibi for rest and stress imaging, respectively. Standard rest and stress imaging were performed at the end of each dynamic scan. A total perfusion defect (TPD) < 5% were considered normal. Obstructive CAD was defined as ≥ 70% stenosis at coronary angiography. RESULTS: Global MPR was lower (p < 0.05) in patients with abnormal compared with those with normal MPI (2.40 ± 0.7 vs. 2.70 ± 0.8). A weak, albeit significant correlation between TPD and MPR (r = - 0.179, p < 0.05) was found. In 91 patients with available angiographic data, hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower (both p < 0.05) in patients with obstructive CAD (n = 21) compared with those without (n = 70). At univariable analysis, TPD, hyperemic MBF, and MPR were significant predictors of obstructive CAD, whereas only MPR was independent predictor at multivariable analysis (p < 0.05). At per vessels analysis, regional hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and regional MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower in the 31 vessels with obstructive CAD compared with 242 vessels without (both p < 0.05). CONCLUSIONS: In patients with suspected or known CAD, MPR assessed by low-dose dynamic CZT-SPECT showed a good correlation with myocardial perfusion imaging findings and it could be useful to predict obstructive CAD.

Feasibility of simultaneous dual isotope acquisition for myocardial perfusion imaging with a cadmium zinc telluride camera.

BACKGROUND: We studied the impact of technetium-99m (99mTc) in the thallium-201 (201Tl) energy window (70 keV) to determine if CZT cardiac cameras allow us to perform simultaneous dual-isotope acquisition for myocardial perfusion imaging. METHODS: We included 117 consecutive patients. We injected 0.7 MBq/kg of 201Tl at stress, performed the first scan (image T1), then injected at rest 2 MBq/kg of 99mTc-tetrofosmin and immediately acquired a second scan with reconstruction in the energy window of thallium (image T2). A corrected thallium image was created by the subtraction of 99mTc downscattered photons (image TS). We compared spectra, image quality, and semiquantitative scores on T1, T2, and TS images. RESULTS: Though T2 images were of worse quality, TS images were of equal quality compared to T1 images in most cases. Scores show an underestimation of abnormalities in 20% of patients on T2 images and in 10% on TS images. CONCLUSIONS: Despite the improved energy resolution of CZT cameras, downscatter of technetium in the 201Tl window leads to an underestimation of the pathological territory in 10% to 20% of cases. It does not allow us to use simultaneous dual-isotope acquisition in clinical practice without additional tools for scatter correction.

Head-to-head comparison of the diagnostic performances of Rubidium-PET and SPECT with CZT camera for the detection of myocardial ischemia in a population of women and overweight individuals.

BACKGROUND: The aim of this study was to compare the diagnostic performances for the detection of myocardial ischemia of 82-Rb-PET-MPS and 99m-Tc-SPECT-MPS in overweight individuals and women. METHODS AND RESULTS: Men with BMI ≥ 25 and women referred for MPS were considered for inclusion. All individuals underwent 99m-Tc-SPECT-MPS with CZT cameras and 82-Rb-PET-MPS in 3D-mode. Individuals with at least one positive MPS were referred for coronary angiography (CA) with FFR measurements. A criterion for positivity was a composite endpoint including significant stenosis on CA or, in the absence of CA, the occurrence of acute coronary event during the following year. 313 patients (46% women) with mean BMI of 31.8 ± 6.5 were included. Sensitivity for the detection of myocardial ischemia was higher with 82-Rb-PET-MPS compared with 99m-Tc-SPECT-MPS (85% vs. 57%, P < .05); specificity was equally high with both imaging techniques (93% vs. 94%, P > .05). 82-Rb-PET allowed for a more accurate detection of patients with a high-risk coronary artery disease (HR-CAD) than 99m-Tc-SPECT-MPS (AUC = 0.86 vs. 0.75, respectively; P = .04). CONCLUSIONS: In women and overweight individuals, 82-Rb-PET-MPS provides higher sensitivity for the detection of myocardial ischemia than 99m-Tc-SPECT-MPS thanks to a better image quality and an improved detection of HR-CAD.

Left ventricular ejection fraction determined with the simulation of a very low-dose CZT-SPECT protocol and an additional count-calibration on planar radionuclide angiographic data.

PURPOSE: To determine whether the left ventricular ejection fractions (EFs), measured on a high-sensitivity CZT single photon emission computed tomography (SPECT)-camera with a 70% reduction in recording times and a prevention of EF overestimation through an additional count-calibration, are concordant with reference EF from planar radionuclide angiography (2D-RNA). METHODS: An additional 10-minute CZT-SPECT recording was performed in patients referred to 2D-RNA for cardiomyopathy (n = 23) or chemotherapy monitoring (n = 50) with an in vivo red blood cell labeling with 850 MBq [Formula: see text]. The EF, obtained from CZT-SPECT with 100% (SPECT100) or 30% (SPECT30) projection times and with a SPECT-count calibration on the 2D-RNA counts of corresponding cavity volumes, were compared to EF from 2D-RNA. RESULTS: Strong and equivalent relationships were documented between the EF from 2D-RNA and the calibrated EF from SPECT100 (y = 0.89x + 6.62; R2 = 0.87) and SPECT30 (y = 0.87x + 8.40; R2 = 0.85), and the mean EF from SPECT100 (54% ± 15%) and SPECT30 (53% ± 16%) were close to that from 2D-RNA (55% ± 15%). However, upward shifts in these mean values were documented in the absence of count calibration for both SPECT100 (60% ± 18%) and SPECT30 (60% ± 18%). CONCLUSION: Left ventricular EF may be determined on a high-sensitivity CZT-camera, a 70% reduction in injected activities, and an additional count-calibration for further enhancing the concordance with 2D-RNA values.

First validation of myocardial flow reserve assessed by dynamic 99mTc-sestamibi CZT-SPECT camera: head to head comparison with 15O-water PET and fractional flow reserve in patients with suspected coronary artery disease. The WATERDAY study.

PURPOSE: We assessed the feasibility of myocardial blood flow (MBF) and flow reserve (MFR) estimation using dynamic SPECT with a novel CZT camera in patients with stable CAD, in comparison with 15O-water PET and fractional flow reserve (FFR). METHODS: Thirty patients were prospectively included and underwent FFR measurements in the main coronary arteries (LAD, LCx, RCA). A stenosis ≥50% was considered obstructive and a FFR abnormal if ≤0.8. All patients underwent a dynamic rest/stress 99mTc-sestamibi CZT-SPECT and 15O-water PET for MBF and MFR calculation. Net retention kinetic modeling was applied to SPECT data to estimate global uptake values, and MBF was derived using Leppo correction. Ischemia by PET and CZT-SPECT was considered present if MFR was lower than 2 and 2.1, respectively. RESULTS: CZT-SPECT yielded higher stress and rest MBF compared to PET for global and LAD and LCx territories, but not in RCA territory. MFR was similar in global and each vessel territory for both modalities. The sensitivity, specificity, accuracy, positive and negative predictive value of CZT-SPECT were, respectively, 83.3, 95.8, 93.3, 100 and 85.7% for the detection of ischemia and 58.3, 84.6, 81.1, 36.8 and 93% for the detection of hemodynamically significant stenosis (FFR ≤ 0.8). CONCLUSIONS: Dynamic 99mTc-sestamibi CZT-SPECT was technically feasible and provided similar MFR compared to 15O-water PET and high diagnostic value for detecting impaired MFR and abnormal FFR in patients with stable CAD.

Prognostic value of one millisievert exercise myocardial perfusion imaging in patients without known coronary artery disease.

The aim of this study was to assess the prognostic value of normal ultra-low-dose exercise MPI with a CZT camera. METHODS: 1901 consecutive patients without known CAD referred for exercise MPI with 1.8 MBq/kg (0.05 mCi) of Tc99m sestamibi or tetrofosmin and a CZT camera were included prospectively. Patients with an abnormal scan requiring an additional resting image (230) or a submaximal exercise test (271) were excluded. The 1400 remaining patients were followed for 39 months. The primary end-point was cardiac events (cardiac death, nonfatal myocardial infarction, and revascularization). The secondary end-point was noncardiac death. RESULTS: The mean injected activity was 145 ± 37 MBq (3.9 ± 1 mCi), the mean acquisition duration was 10 ± 0.7 minutes, and the mean effective dose was 0.91 ± 0.13 mSv. 1288 patients (92%) achieved full follow-up. We observed 22 cardiac events and 16 noncardiac deaths. The annualized rates were equivalent to 0.55% for cardiac events and 0.37% for noncardiac mortality. CONCLUSIONS: Normal ultra-low-dose exercise MPI with a CZT camera has a high negative predictive value. The effective dose was less than 1 mSv, and the study thus allays concerns about radiation burden.

Low-dose dual-isotope procedure planed for myocardial perfusion CZT-SPECT and assessed through a head-to-head comparison with a conventional single-isotope protocol.

PURPOSE OF THE REPORT: This study aimed at assessing an original low-dose dual-isotope procedure in which the abnormal stress Tc-99m Sestamibi SPECT is followed by rest Tl-201 SPECT, along with a head-to-head comparison with a single-isotope procedure. METHODS AND RESULTS: One hundred two patients, referred for a low-dose stress-SPECT with Sestamibi (123 ± 20 MBq) on a CZT camera and for whom a rest Sestamibi SPECT was warranted, had an additional Tl-201 rest-SPECT (52 ± 5 MBq) between stress and rest Sestamibi SPECT recordings. Tl-201 images were processed for spill-over and scatter corrections, and uptake differences with stress Sestamibi SPECT were analyzed: (1) for rest acquisitions from Tl-201 (dual-isotope procedure) and from Sestamibi (single-isotope procedure) and (2) in segments for which a diagnosis of ischemia, infarct, or normal perfusion was achieved. Mean effective dose was 8.3 mSv for dual-isotope but would decrease to 5.7 mSv for an expected rate of 37% of patients for whom rest-SPECT is not warranted. After a further background correction of Tl-201 images, the rest-stress difference in myocardial uptake was equivalent between dual- and single-procedures for identifying ischemic segments (respective areas-under-curves: 0.83 ± 0.03 and 0.81 ± 0.03). CONCLUSION: This original dual-isotope procedure provides acceptable radiation doses and consistent results, as compared with conventional single-isotope.

Routine evaluation of left ventricular function using CZT-SPECT, with low injected activities and limited recording times.

PURPOSE: Gamma-cameras, with Cadmium-Zinc-Telluride (CZT) detectors, allow to perform myocardial perfusion imaging (MPI) with limited injected activities and recorded times. This study aimed at determining whether the routine assessment of left ventricular (LV) function with such limited counts protocols compares well with reference values from cardiac MRI. METHODS: The study included patients who have undergone cardiac MRI and an MPI routinely planned on a CZT camera with a low-dose protocol (120 MBq of Sestamibi for stress and 360 MBq at rest for 75 kg body weight), while targeting the recording of only 500 myocardial kcounts in order to limit the recording times (<10 minutes for stress, <4 minutes for rest). SPECT images were reconstructed with a method maintaining rather high spatial (8 mm) and temporal (16 frames/cycle) resolutions. RESULTS: Seventy-six patients were included, and mean effective dose was 3.5 ± 1.7 mSv for the total MPI protocol. Correlations between CZT-SPECT and MRI were good to excellent for ejection fraction (r 2 = 0.77), end-diastolic (r 2 = 0.88) and end-systolic (r 2 = 0.93) volumes, and the analysis of segmental contractility correlated well between the two techniques (kappa score = 0.72 ± 0.02). CONCLUSION: LV function, assessed on a CZT camera with low injected activities and limited recording times, correlates well with the reference assessment from cardiac MRI.

The value of local normal limits in quantitative Thallium-201 CZT MPI SPECT.

BACKGROUND: Considering the distinctive characteristics of CZT detectors, automatic quantification of ischemia using normal limits included with software package may deliver suboptimal results for CAD detection. The present study aims to evaluate the benefits of creating normal limits specific to a local population and laboratory protocol. METHODS AND RESULTS: Two groups were selected from patients who had undergone a CZT MPI. Normal limits were generated with the QPS application based on the population with low likelihood of CAD. Using the vendor-supplied and the population-specific normal limits i-TPD and vessel-specific SDS results obtained for patients who had subsequently undergone coronary angiography were compared with coronary angiography data. A weak correlation was observed for low i-TPD (stress TPD minus rest TPD) and SDS values. Both databases gave similar values for the area under the ROC curve concerning i-TPD (0.75 to 0.74) and SDS results (0.72 to 0.75 for the LAD, 0.62 to 0.64 for the LCx, and 0.63 to 0.67 for the RCA). Sensitivity (60%), specificity (78%), and predictive positive (84%) and negative (52%) values were also similar with a diagnostic and prognostic threshold value. CONCLUSION: The use of a population-specific created database did not influence the diagnostic value of thallium-201 MPI QPS results using a CZT camera.

Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM).

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Comparison of the diagnostic accuracies of very low stress-dose with standard-dose myocardial perfusion imaging: Automated quantification of one-day, stress-first SPECT using a CZT camera.

BACKGROUND: Previous studies have demonstrated accurate diagnosis of reduced dose myocardial perfusion imaging (MPI) using Cadmium-Zinc-Telluride (CZT) technology. We compared the diagnostic performances of very low stress-dose (<2 mSv) with standard-dose stress-first, quantitative MPI using a CZT camera. METHODS: Patients without known coronary artery- disease who underwent a stress-first Tc-99 m sestamibi CZT-MPI and invasive coronary angiography (ICA), and low-risk patients without ICA were included. A stress-rest standard-dose (10/30 mCi) MPI and a low-dose (5/15 mCi) MPI were compared. Normal limits for quantification were developed from 40 (20 males) low-risk patients, and total perfusion deficit (TPD) was derived. RESULTS: 208 patients who underwent MPI and ICA, and 76 low-risk patients were included. Of these, 128 had a standard-dose MPI and 156 had a low-dose MPI. Stress-doses in low-dose and standard-dose groups were 5.9 ± 1.2 vs 10.2 ± 0.5 mCi (1.7 ± 0.3 vs 3.0 ± 0.1 mSv), respectively, P < 0.001, and stress-rest effective radiation was 6.9 ± 1.1 vs 11.7 ± 0.4 mSv, respectively, P < 0.001. Sensitivity, specificity, and accuracy values in the low-dose and standard-dose groups were 86.1%, 76.6%, and 81.4%; and 90.6%, 78.1%, and 84.4%, respectively, P = ns. Using TPD prone, specificity values were 84.9% and 80.3%, respectively, P = ns. CONCLUSION: One-day stress-first MPI with 50% radiation reduction and a very low stress-dose (<2 mSv) using CZT technology and quantitative supine and prone analysis provided a high diagnostic value, similar to standard-dose MPI.

A preliminary feasibility study of simultaneous dual-isotope imaging with a solid-state dedicated cardiac camera for evaluating myocardial perfusion and fatty acid metabolism.

Simultaneous dual-isotope SPECT imaging with 201Tl and (123)I-ß-methyl-p-iodophenylpentadecanoic acid (BMIPP) is used to study the perfusion-metabolism mismatch. It predicts post-ischemic functional recovery by detecting stunned myocardium. On the other hand, (99m)Tc-MIBI is another radioisotope widely used in myocardial perfusion imaging because of its better image quality and lower radiation exposure than 201Tl. However, since the photopeak energies of (99m)Tc and (123)I are very similar, crosstalk hampers the simultaneous use of these two radioisotopes. To overcome this problem, we conducted simultaneous dual-isotope imaging study using the D-SPECT scanner (Spectrum-Dynamics, Israel) which has a novel detector design and excellent energy resolution. We first conducted a basic experiment using cardiac phantom to simulate the condition of normal perfusion and impaired fatty acid metabolism. Subsequently, we prospectively recruited 30 consecutive patients who underwent successful percutaneous coronary intervention for acute myocardial infarction, and performed (99m)Tc-MIBI/(123)I-BMIPP dual-isotope imaging within 5 days after reperfusion. Images were interpreted by two experienced cardiovascular radiologists to identify the infarcted and stunned areas based on the coronary artery territories. As a result, cardiac phantom experiment revealed no significant crosstalk between (99m)Tc and (123)I. In the subsequent clinical study, (99m)Tc-MIBI/(123)I-BMIPP dual-isotope imaging in all participant yielded excellent image quality and detected infarcted and stunned areas correctly when compared with coronary angiographic findings. Furthermore, we were able to reduce radiation exposure to significantly approximately one-eighth. In conclusion, we successfully demonstrated the practical application of simultaneous assessment of myocardial perfusion and fatty acid metabolism by (99m)Tc-MIBI and (123)I-BMIPP using a D-SPECT cardiac scanner. Compared with conventional (201)TlCl/(123)I-BMIPP dual-isotope imaging, the use of (99m)Tc-MIBI instead of (201)TlCl improves image quality as well as lowers radiation exposure.

A practical method for measuring planar spatial resolution with scatter on a CZT gamma camera.

PURPOSE: This study proposes a practical method for evaluating 2D spatial resolution with scatter on a CZT planar detector gamma camera, which is simpler and faster than the NEMA method. It is used to characterize the influence of distance on spatial resolution FWHM on a CZT camera equipped with a WEHR collimator. METHODS: The practical method uses linear sources tilted with respect to the detector axes. The spatial resolution full width at half maximum (FWHM) with four tilt angles was compared to the FWHM evaluated using the NEMA NU1-2018 method. Spatial resolution FWHM was also assessed with tilted sources acquired at distances of 0 to 20 cm using a single angle, with and without the post-processing image enhancement proposed by the manufacturer. RESULTS: Estimated spatial resolution FWHM with tilted sources was close to the spatial resolution FWHM estimated at 7.63 mm by the NEMA method, with deviations ranging from - 5.62 to 4.59% at 10 cm depending on the angle considered. The study of spatial resolution FWHM dependence on distance indicates that, for distances less than 3 cm, the FWHM no longer decreases with distance. The manufacturer's post-processing reduces the FWHM by an average of 15%. CONCLUSION: The practical method is quicker to implement and gives comparable results to the NEMA reference method for spatial resolution FWHM. Evaluation of spatial resolution with linear sources at short distances from the collimator is limited by the collimator effect and signal digitization. The tilted source method can be used to measure spatial resolution quickly and easily under clinical conditions for CZT planar cameras.

Improving multi-pinhole CZT myocardial perfusion imaging specificity without changing sensibility by using adapted filter parameters.

BACKGROUND: Meta-analysis show the diagnostic performance of cardiac dedicated multi-pinhole cadmium-zinc-telluride myocardial perfusion imaging (MPI) with a sensibility around 0.9 and a specificity around 0.7. The aim of the present study is to explore a simple method to generate less artefact on MPI using single photon emission computed tomography (SPECT) and to enhance specificity without changing sensibility. RESULTS: From October 2018 to March 2019, 200 patients who underwent SPECT with [99mTc]Tc-tetrofosmin were prospectively recruited: 100 patients with ischemia or necrosis diagnosis (first arm), and 100 patients with myocardial reversible SPECT artefact (second arm). Each SPECT was explored using two image process based on a Butterworth prefilter and post-filter: the original image processing (reconstruction A) with a cut-off frequency equals to 37% of the Nyquist frequency and order equals to 7, and a second image processing (reconstruction B) with a cut-off frequency equals to 25% of the Nyquist frequency and order equals to 5. For each patient, sum stress or rest score with and without septum (SSRS and SSRSws) were calculated with the two reconstructions. No significant statistical difference between SSRSa and SSRSb was identified for the first arm (P = 0.54) and the relative difference ∆r was - 0.5 ± 11.1% (95% CI - 2.7 to 1.7). We found a significant statistical difference between SSRSa and SSRSb for the second arm (p < 0.0001) and the relative difference ∆r was 69.7 ± 16.2% (95% CI 66.6-72.9). CONCLUSION: In conclusion, using a Butterworth prefilter and post-filter cut-off frequency equal to 25% of the Nyquist frequency before iterative reconstruction generates less artefact and improves myocardial SPECT specificity without affecting sensibility compared with the original reconstruction.