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1.
Jan Vontobel Riccardo Liga Mathias Possner Olivier F. Clerc Fran Mikulicic Patrick Veit-Haibach Edwin E. G. W. ter Voert Tobias A. Fuchs Julia Stehli Aju P. Pazhenkottil Dominik C. Benz Christoph Gräni Oliver Gaemperli Bernhard Herzog Ronny R. Buechel Philipp A. Kaufmann 《European journal of nuclear medicine and molecular imaging》2015,42(10):1574-1580
2.
Duo Zhang Bang-Hung Yang Nien Yun Wu Greta Seng Peng Mok 《Annals of nuclear medicine》2017,31(2):172-180
Objective
Cine average CT (CACT) and interpolated average CT (IACT) have been proposed to improve attenuation correction (AC) for PET/CT in oncologic and cardiac studies. This study aims to evaluate their effectiveness on myocardial perfusion SPECT/CT using computer simulation and physical phantom experiments.Methods
We first simulated normal male with 99mTc-sestamibi distribution using digital XCAT phantom with respiratory motion amplitudes of 2, 3, and 4 cm. Average activity and attenuation maps represented static SPECT and CACT, while the attenuation maps of end-inspiration and end-expiration represented two helical CTs (HCTs), respectively. Sixty noise-free and noisy projections were simulated over 180° using an analytical parallel-hole projector. We then filled 673 MBq 99mTc into an anthropomorphic torso phantom with normal heart or heart with a defect which placed on a programmable respiratory platform to model various respiratory amplitudes. Sixty projections were acquired over 180° using a clinical SPECT/CT scanner. The CACT, standard HCT, and 2 HCTs at extreme phases were acquired. Interpolated CT phases were generated between them using affine plus b-spline registration, and IACT was obtained by averaging the interpolated phases and the 2 original extreme phases for both simulation and phantom experiments. Projections were reconstructed with AC using CACT, IACT, and HCTs, respectively. Polar and 17-segment plots were analyzed by relative difference (RD) of the uptake. Two regions-of-interest (ROI) were drawn on the defect and background area to obtain the intensity ratio (IR).Results
No substantial difference was observed on the polar plots generated from different AC methods, while the quantitative RD measurements showed that SPECTCACT were most similar to the original phantom, followed by SPECTIACT, with RDmax <8 and <10% in the simulation study. The RD of SPECTHCTs deviated from the original phantom and SPECTCACT in various segments, with RDmax of 19.76 and 16.68% in the simulation and phantom experiment, respectively. The IR of SPECTHCTs fluctuated more from the truth for higher motion amplitude.Conclusions
Both CACT-AC and IACT-AC reduced respiratory artifacts and improved quantitation in myocardial perfusion SPECT as compared to HCT-AC. The use of IACT further reduced the radiation dose.3.
Nina Burkhard Bernhard A. Herzog Lars Husmann Aju P. Pazhenkottil Irene A. Burger Ronny R. Buechel Ines Valenta Christophe A. Wyss Philipp A. Kaufmann 《European journal of nuclear medicine and molecular imaging》2010,37(3):517-521
Purpose
The aim of this study was to evaluate whether ECG-triggered coronary calcium scoring (CCS) scans can be used for attenuation correction (AC) to quantify myocardial blood flow (MBF) and coronary flow reserve (CFR) assessed by PET/CT with 13N-ammonia. 相似文献4.
Adam M Alessio Steve Kohlmyer Kelley Branch Grace Chen James Caldwell Paul Kinahan 《Journal of nuclear medicine》2007,48(5):794-801
In dual-modality PET/CT systems, the CT scan provides the attenuation map for PET attenuation correction. The current clinical practice of obtaining a single helical CT scan provides only a snapshot of the respiratory cycle, whereas PET occurs over multiple respiratory cycles. Misalignment of the attenuation map and emission image because of respiratory motion causes errors in the attenuation correction factors and artifacts in the attenuation-corrected PET image. To rectify this problem, we evaluated the use of cine CT, which acquires multiple low-dose CT images during a respiratory cycle. We evaluated the average and the intensity-maximum image of cine CT for cardiac PET attenuation correction. METHODS: Cine CT data and cardiac PET data were acquired from a cardiac phantom and from multiple patient studies. The conventional helical CT, cine CT, and PET data of an axially translating phantom were evaluated with and without respiratory motion. For the patient studies, we acquired 2 cine CT studies for each PET acquisition in a rest-stress (13)N-ammonia protocol. Three readers visually evaluated the alignment of 74 attenuation image sets versus the corresponding emission image and determined whether the alignment provided acceptable or unacceptable attenuation-corrected PET images. RESULTS: In the phantom study, the attenuation correction from helical CT caused a major artifactual defect in the lateral wall on the PET image. The attenuation correction from the average and from the intensity-maximum cine CT images reduced the defect by 20% and 60%, respectively. In the patient studies, 77% of the cases using the average of the cine CT images had acceptable alignment and 88% of the cases using the intensity maximum of the cine CT images had acceptable alignment. CONCLUSION: Cine CT offers an alternative to helical CT for compensating for respiratory motion in the attenuation correction of cardiac PET studies. Phantom studies suggest that the average and the intensity maximum of the cine CT images can reduce potential respiration-induced misalignment errors in attenuation correction. Patient studies reveal that cine CT provides acceptable alignment in most cases and suggest that the intensity-maximum cine image offers a more robust alternative to the average cine image. 相似文献
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6.
Clinical myocardial perfusion PET/CT. 总被引:5,自引:0,他引:5
Marcelo F Di Carli Sharmila Dorbala Jolene Meserve Georges El Fakhri Arkadiusz Sitek Stephen C Moore 《Journal of nuclear medicine》2007,48(5):783-793
The field of nuclear cardiology is witnessing growing interest in the use of cardiac PET for the evaluation of patients with coronary artery disease (CAD). The available evidence suggests that myocardial perfusion PET provides an accurate means for diagnosing obstructive CAD, which appears superior to SPECT especially in the obese and in those undergoing pharmacologic stress. The ability to record changes in left ventricular function from rest to peak stress and to quantify myocardial perfusion (in mL/min/g of tissue) provides an added advantage over SPECT for evaluating multivessel CAD. There is growing and consistent evidence that gated myocardial perfusion PET also provides clinically useful risk stratification. Although the introduction of hybrid PET/CT technology offers the exciting possibility of assessing the extent of anatomic CAD (CT coronary angiography) and its functional consequences (ischemic burden) in the same setting, there are technical challenges in the implementation of CT-based transmission imaging for attenuation correction. Nonetheless, this integrated platform for assessing anatomy and biology offers a great potential for translating advances in molecularly targeted imaging into humans. 相似文献
7.
Russell A H Cook Greg Carnes Ting-Yim Lee R Glenn Wells 《Journal of nuclear medicine》2007,48(5):811-818
Heart disease is a leading cause of death in North America. With the increased availability of PET/CT scanners, CT is now commonly used as a transmission source for attenuation correction. Because of the differences in scan duration between PET and CT, respiration-induced motion can create inconsistencies between the PET and CT data and lead to incorrect attenuation correction and, thus, artifacts in the final reconstructed PET images. This study compared respiration-averaged CT and 4-dimensional (4D) CT for attenuation correction of cardiac PET in an in vivo canine model as a means of removing these inconsistencies. METHODS: Five dogs underwent respiration-gated cardiac (18)F-FDG PET and 4D CT. The PET data were reconstructed with 3 methods of attenuation correction that differed only in the CT data used: The first method was single-phase CT at either end-expiration, end-inspiration, or the middle of a breathing cycle; the second was respiration-averaged CT, which is CT temporally averaged over the entire respiratory cycle; and the third was phase-matched CT, in which each PET phase is corrected with the matched phase from 4D CT. After reconstruction, the gated PET images were summed to produce an ungated image. Polar plots of the PET heart images were generated, and percentage differences were calculated with respect to the phase-matched correction for each dog. The difference maps were then averaged over the 5 dogs. RESULTS: For single-phase CT correction at end-expiration, end-inspiration, and mid cycle, the maximum percentage differences were 11% +/- 4%, 7% +/- 3%, and 5% +/- 2%, respectively. Conversely, the maximum difference for attenuation correction with respiration-averaged CT data was only 1.6% +/- 0.7%. CONCLUSION: Respiration-averaged CT correction produced a maximum percentage difference 7 times smaller than that obtained with end-expiration single-phase correction. This finding indicates that using respiration-averaged CT may accurately correct for attenuation on respiration-ungated cardiac PET. 相似文献
8.
Impact of metallic dental implants on CT-based attenuation correction in a combined PET/CT scanner 总被引:9,自引:2,他引:7
Our objective was to study the effect of metal-induced artifacts on the accuracy of the CT-based anatomic map as a prerequisite
for attenuation correction of the positron emission tomography (PET) emission data. Twenty-seven oncology patients with dental
metalwork were enrolled in the present study. Data acquisition was performed on a PET/CT in-line system (Discovery LS, GE
Medical Systems, Milwaukee, Wis.). Attenuation correction of emission data was done twice, using an 80-mA CT scan (PETCT80) and a 68Ge transmission scan (PET68Ge). Average count in kBq/cc was measured in regions with and without artifacts and compared for PETCT80 and PET68Ge. Data analysis of region of interests (ROIs) revealed that the ratio (ROIs PETCT80/ROIs PET68Ge) and the difference (ROIs PETCT80 minus ROIs PET68Ge) had a higher mean of values in regions with artifacts than in regions without artifacts (1.2±0.17 vs 1.06±0.06 and 0.68±0.67
vs 0.15±0.17 kBq/cc, respectively). For most of the studied artifactual ROIs, the PETCT80 values were higher than those of the PET68Ge. Attenuation correction of PET emission data using an artifactual CT map yields false values in regions nearby artifacts
caused by dental metalwork. This may falsely estimate PET quantitative studies and may disturb the visual interpretation of
PET scan.
Electronic Publication 相似文献
9.
PET/CT attenuation correction: breathing lessons. 总被引:1,自引:0,他引:1
Stephen L Bacharach 《Journal of nuclear medicine》2007,48(5):677-679
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Ryo Nakazato MD PhD Damini Dey PhD Erick Alexánderson MD Aloha Meave MD Moisés Jiménez MD Edgar Romero MD Rodrigo Jácome MD Marco Pe?a MD Daniel S. Berman MD Piotr J. Slomka PhD 《Journal of nuclear cardiology》2012,19(3):482-491
Background
Hybrid PET/CT allows for acquisition of cardiac PET and coronary CT angiography (CCTA) in one session. However, PET and CCTA are acquired with differing breathing protocols and require software registration. We aimed to validate automatic correction for breathing misalignment between PET and CCTA acquired on hybrid scanner.Methods
Single-session hybrid PET/CT studies of rest/stress 13N-ammonia PET and CCTA in 32 consecutive patients were considered. Automated registration of PET left ventricular (LV) surfaces with CCTA volumes was evaluated by comparing with expert manual alignment by two observers.Results
The average initial misalignments between the position of LV on PET and CCTA were 27.2?±?11.8, 13.3?±?11.5, and 14.3?±?9.1?mm in x, y, and z axes on rest, and 26.3?±?10.2, 11.1?±?9.5, and 11.7?±?7.1?mm in x, y, and z axes on stress, respectively. The automated PET-CCTA co-registration had 95% agreement as judged visually. Compared with expert manual alignment, the translation errors of the algorithm were 5.3?±?2.8?mm (rest) and 6.0?±?3.5?mm (stress). 3D visualization of combined coronary vessel anatomy and hypoperfusion from PET could be made without further manual adjustments.Conclusion
Software co-registration of CCTA and PET myocardial perfusion imaging on hybrid PET/CT scanners is necessary, but can be performed automatically, facilitating integrated 3D display on PET/CT. 相似文献12.
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14.
Mark T. Madsen Peter T. Kirchner Maleah Grover-McKay Regai Aktay James S. Seabold Karim Rezai Greg Kelly 《Journal of nuclear cardiology》1997,4(6):477-486
Background Nonuniform attenuation in the thorax can generate artifacts in single-photon emission computed tomographic myocardial perfusion
studies that mimic coronary artery disease. In this article we present both phantom and simulation data, as well as clinical
data, in support of an emission-based method that provides reliable correction for attenuation effects without the need for
a transmission measurement.
Methods and Results The attenuation map is derived from the measured distribution of 99mTc-labeled macroaggregated albumin in the lungs and a radioactive binder wrapped about the thorax. This information is acquired
as part of a dual-isotope acquisition during the rest 201TI study. Segmentation is used to define the interiors of lung and body compartments, which are assigned a single attenuation
coefficient for each of the two tissue types. The appropriateness of this approach was investigated by examining the measured
attenuation coefficients in a group of 80 individuals (40 male, 40 female) from positron emission tomographic transmission
studies. The correction technique was evaluated with computer simulations, a physical phantom, and clinical data acquired
from 20 patients. Analysis of the positron emission tomographic data found a small SD in the mean attenuation coefficients
for the body (<5%) and lungs (<15%). The application of emission-based attenuation-correction technique produced a substantial
reduction in the magnitude of the attenuation artifact in images obtained from both the phantom and the simulation studies.
The emission-based attenuation-correction technique was easily applied to myocardial perfusion studies, where it had a significant
effect, resulting in changes in interpretation for nine of 20 patients.
Conclusions The results of this study provide strong support for the concept that an attenuation map can be generated with fixed attenuation
values in place of those that are directly measured. Thus the emission-based attenuation-correction technique can be considered
an inexpensive alternative to transmission-based correction methods. Because the emission-based correction technique does
not require any additional hardware, it has the major advantage of being applicable to all single-photon emission computed
tomographic systems. 相似文献
15.
A technique for using CT images in attenuation correction and quantification in SPECT 总被引:4,自引:0,他引:4
J S Fleming 《Nuclear medicine communications》1989,10(2):83-97
A technique is described for using computed tomography (CT) images for attenuation correction and quantification in SPECT. The CT images are aligned with the corresponding SPECT slices and the Hounsfield units are converted to linear attenuation coefficient values for the SPECT radionuclide. The attenuation coefficient map thus produced is used to provide the attenuation correction required in the SPECT reconstruction. The technique has been evaluated in both a non-anatomical and an anatomical phantom giving a mean accuracy in quantifying activity of various features in the phantoms of 2.6% (range 0.3%-4.0%). The value of performing scatter correction prior to attenuation correction in obtaining accurate quantification is demonstrated. The practicalities of applying the technique in patient studies are discussed. 相似文献
16.
J. D. van Dijk M. Mouden J. P. Ottervanger J. A. van Dalen S. Knollema C. H. Slump P. L. Jager 《Journal of nuclear cardiology》2017,24(2):395-401
Background
Attenuation correction (AC) improves the diagnostic outcome of stress-only myocardial perfusion imaging (MPI) using conventional SPECT. Our aim was to determine the value of AC using a cadmium zinc telluride-based (CZT)-SPECT camera.Methods and results
We retrospectively included 107 consecutive patients who underwent stress-optional rest MPI CZT-SPECT/CT. Next, we created three types of images for each patient; (1) only displaying reconstructed data without the CT-based AC (NC), (2) only displaying AC, and (3) with both NC and AC (NC + AC). Next, two experienced physicians visually interpreted these 321 randomized images as normal, equivocal, or abnormal. Image outcome was compared with all hard events over a mean follow-up time of 47.7 ± 9.8 months. The percentage of images interpreted as normal increased from 45% using the NC images to 72% using AC and to 67% using NC + AC images (P < .001). Hard event hazard ratios for images interpreted as normal were not different between using NC and AC (1.01, P = .99), or NC and NC + AC images (0.97, P = .97).Conclusions
AC lowers the need for additional rest imaging in stress-first MPI using CZT-SPECT, while long-term patient outcome remained identical. Use of AC reduces the need for additional rest imaging, decreasing the mean effective dose by up to 1.2 mSv.17.
Jeffrey M. C. Lau R. Laforest H. Sotoudeh X. Nie S. Sharma J. McConathy E. Novak A. Priatna R. J. Gropler P. K. Woodard 《Journal of nuclear cardiology》2017,24(3):839-846
Background
Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC.Methods and Results
Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body 18F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R 2 = 0.97).Conclusions
Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.18.
Purpose
Recent studies have shown an excellent correlation between PET/MR and PET/CT hybrid imaging in detecting lesions. However, a systematic underestimation of PET quantification in PET/MR has been observed. This is attributable to two methodological challenges of MR-based attenuation correction (AC): (1) lack of bone information, and (2) truncation of the MR-based AC maps (μmaps) along the patient arms. The aim of this study was to evaluate the impact of improved AC featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR.Methods
The MR-based Dixon method provides four-compartment μmaps (background air, lungs, fat, soft tissue) which served as a reference for PET/MR AC in this study. A model-based bone atlas provided bone tissue as a fifth compartment, while the HUGE method provided truncation correction. The study population comprised 51 patients with oncological diseases, all of whom underwent a whole-body PET/MR examination. Each whole-body PET dataset was reconstructed four times using standard four-compartment μmaps, five-compartment μmaps, four-compartment μmaps + HUGE, and five-compartment μmaps + HUGE. The SUVmax for each lesion was measured to assess the impact of each μmap on PET quantification.Results
All four μmaps in each patient provided robust results for reconstruction of the AC PET data. Overall, SUVmax was quantified in 99 tumours and lesions. Compared to the reference four-compartment μmap, the mean SUVmax of all 99 lesions increased by 1.4 ± 2.5% when bone was added, by 2.1 ± 3.5% when HUGE was added, and by 4.4 ± 5.7% when bone + HUGE was added. Larger quantification bias of up to 35% was found for single lesions when bone and truncation correction were added to the μmaps, depending on their individual location in the body.Conclusion
The novel AC method, featuring a bone model and truncation correction, improved PET quantification in whole-body PET/MR imaging. Short reconstruction times, straightforward reconstruction workflow, and robust AC quality justify further routine clinical application of this method.19.
Ishii K Hanaoka K Okada M Kumano S Komeya Y Tsuchiya N Hosono M Murakami T 《Annals of nuclear medicine》2012,26(3):241-247
Purpose
The aim of this study was to elucidate the regional differences between brain perfusion single photon emission computed tomography (SPECT) images reconstructed with a uniform attenuation correction using Chang’s method (AC-Chang) and a non-uniform attenuation correction with CT using SPECT/CT (AC-CT). 相似文献20.
R. Glenn Wells PhD FCCPM Karen Soueidan MSc Rachel Timmins MSc Terrence D. Ruddy MD FRCPC FACC FASNC 《Journal of nuclear cardiology》2013,20(5):785-796