共查询到20条相似文献,搜索用时 31 毫秒
1.
David Izquierdo-Garcia Stephen J. Sawiak Karin Knesaurek Jagat Narula Valentin Fuster Joseph Machac Zahi A. Fayad 《European journal of nuclear medicine and molecular imaging》2014,41(8):1574-1584
Purpose
The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard.Methods
Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician.Results
Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group ?0.2 ± 33.6 %, R 2?=?0.98, p?<?0.001; beta group 10.31 ± 69.86 %, R 2?=?0.97, p?<?0.001).Conclusion
In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method. 相似文献2.
Automatic, three-segment, MR-based attenuation correction for whole-body PET/MR data 总被引:3,自引:0,他引:3
Schulz V Torres-Espallardo I Renisch S Hu Z Ojha N Börnert P Perkuhn M Niendorf T Schäfer WM Brockmann H Krohn T Buhl A Günther RW Mottaghy FM Krombach GA 《European journal of nuclear medicine and molecular imaging》2011,38(1):138-152
Purpose
The combination of positron emission tomography (PET) and magnetic resonance (MR) tomography in a single device is anticipated to be the next step following PET/CT for future molecular imaging application. Compared to CT, the main advantages of MR are versatile soft tissue contrast and its capability to acquire functional information without ionizing radiation. However, MR is not capable of measuring a physical quantity that would allow a direct derivation of the attenuation values for high-energy photons.Methods
To overcome this problem, we propose a fully automated approach that uses a dedicated T1-weighted MR sequence in combination with a customized image processing technique to derive attenuation maps for whole-body PET. The algorithm automatically identifies the outer contour of the body and the lungs using region-growing techniques in combination with an intensity analysis for automatic threshold estimation. No user interaction is required to generate the attenuation map.Results
The accuracy of the proposed MR-based attenuation correction (AC) approach was evaluated in a clinical study using whole-body PET/CT and MR images of the same patients (n?=?15). The segmentation of the body and lung contour (L-R directions) was evaluated via a four-point scale in comparison to the original MR image (mean values >3.8). PET images were reconstructed using elastically registered MR-based and CT-based (segmented and non-segmented) attenuation maps. The MR-based AC showed similar behaviour as CT-based AC and similar accuracy as offered by segmented CT-based AC. Standardized uptake value (SUV) comparisons with reference to CT-based AC using predefined attenuation coefficients showed the largest difference for bone lesions (mean value ± standard variation of SUVmax: ?3.0%?±?3.9% for MR; ?6.5%?±?4.1% for segmented CT). A blind comparison of PET images corrected with segmented MR-based, CT-based and segmented CT-based AC afforded identical lesion detectability, but slight differences in image quality were found.Conclusion
Our MR?\based attenuation correction method offers similar correction accuracy as offered by segmented CT. According to the specialists involved in the blind study, these differences do not affect the diagnostic value of the PET images. 相似文献3.
Abdoli M de Jong JR Pruim J Dierckx RA Zaidi H 《European journal of nuclear medicine and molecular imaging》2011,38(12):2257-2268
Purpose
Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over- or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron emission tomography (PET) images. Since this degrades the diagnostic quality of the images, metal artefact reduction (MAR) prior to attenuation correction is required. 相似文献4.
Ghafarian P Aghamiri SM Ay MR Rahmim A Schindler TH Ratib O Zaidi H 《European journal of nuclear medicine and molecular imaging》2011,38(2):252-262
Purpose
Cardiac PET/CT imaging is often performed in patients with pacemakers and implantable cardioverter defibrillator (ICD) leads. However, metallic implants usually produce artefacts on CT images which might propagate to CT-based attenuation-corrected (CTAC) PET images. The impact of metal artefact reduction (MAR) for CTAC of cardiac PET/CT images in the presence of pacemaker, ICD and ECG leads was investigated using both qualitative and quantitative analysis in phantom and clinical studies. 相似文献5.
MRI-guided attenuation correction in whole-body PET/MR: assessment of the effect of bone attenuation
A. Akbarzadeh M. R. Ay A. Ahmadian N. Riahi Alam H. Zaidi 《Annals of nuclear medicine》2013,27(2):152-162
Objective
Hybrid PET/MRI presents many advantages in comparison with its counterpart PET/CT in terms of improved soft-tissue contrast, decrease in radiation exposure, and truly simultaneous and multi-parametric imaging capabilities. However, the lack of well-established methodology for MR-based attenuation correction is hampering further development and wider acceptance of this technology. We assess the impact of ignoring bone attenuation and using different tissue classes for generation of the attenuation map on the accuracy of attenuation correction of PET data.Methods
This work was performed using simulation studies based on the XCAT phantom and clinical input data. For the latter, PET and CT images of patients were used as input for the analytic simulation model using realistic activity distributions where CT-based attenuation correction was utilized as reference for comparison. For both phantom and clinical studies, the reference attenuation map was classified into various numbers of tissue classes to produce three (air, soft tissue and lung), four (air, lungs, soft tissue and cortical bones) and five (air, lungs, soft tissue, cortical bones and spongeous bones) class attenuation maps.Results
The phantom studies demonstrated that ignoring bone increases the relative error by up to 6.8 % in the body and up to 31.0 % for bony regions. Likewise, the simulated clinical studies showed that the mean relative error reached 15 % for lesions located in the body and 30.7 % for lesions located in bones, when neglecting bones. These results demonstrate an underestimation of about 30 % of tracer uptake when neglecting bone, which in turn imposes substantial loss of quantitative accuracy for PET images produced by hybrid PET/MRI systems.Conclusion
Considering bones in the attenuation map will considerably improve the accuracy of MR-guided attenuation correction in hybrid PET/MR to enable quantitative PET imaging on hybrid PET/MR technologies. 相似文献6.
Y. Sakaguchi T. Mitsumoto T. Zhang K. Mitsumoto Y. Tachiya N. Ohya M. Sasaki 《Annals of nuclear medicine》2010,24(7):507-514
Objective
The aim of this study was to investigate the utility of gated PET/CT and CT attenuation correction (AC) for the quantitation of radioactivity.Methods
An ellipse phantom containing six spheres, ranging from 10 to 37 mm in diameter, was filled with 36.7 kBq/mL of F-18. The respiratory motion was simulated by a motor-driven plastic platform to move the phantom with a displacement of 2 cm in the craniocaudal direction at a frequency of 15/min. With the phantom at rest, PET/CT data were acquired and used as a standard (nonmotion). With the phantom in motion, PET data were acquired in both the static and gated modes (sPET and gPET, respectively). Helical CT (HCT), slow CT (SCT), average CT (ACT), and four-dimensional CT (4DCT) were acquired and used to correct attenuation. On both PET and CT images, the maximum radioactivity, dimensions, and CT numbers were measured on the central slices.Results
In nonmotion, recovery coefficients whose spheres were 22 mm or smaller gradually decreased. Regarding motion, the PET counts of the spheres in the static acquisition were lower than those acquired in nonmotion with either type of CTAC (sPET–HCT: ?43.8%, sPET–SCT: ?51.4%, sPET–ACT: ?49.5%). Gated acquisition of PET significantly improved the PET counts (gPET–HCT: ?30.1%) (p < 0.05), while additional gated acquisition of CT significantly improved them further (gPET–4DCT: ?15.2%) (p < 0.01). The dimensions of sPET were overestimated, but those of gPET were close to the standard values. The SCT significantly overestimated the dimensions, and the water density area decreased (p < 0.01). The 4DCT images were similar to the HCT images.Conclusions
In respiratory motion, PET acquisition in the static mode underestimated the radioactivity and overestimated the dimensions. Neither SCT nor ACT improved these errors. Although PET acquisition in the gated mode improved the quantification of PET/CT images, the additional gated CT acquisition using 4DCT is required for further improvement. 相似文献7.
Hossein Ghadiri Mohammad Bagher Shiran Hamid Soltanian-Zadeh Arman Rahmim Habib Zaidi Mohammad Reza Ay 《Annals of nuclear medicine》2014,28(6):559-570
Objective
Uptake value in quantitative PET imaging is biased due to the presence of CT contrast agents when using CT-based attenuation correction. Our aim was to examine spectral CT imaging to suppress inaccuracy of 511 keV attenuation map in the presence of multiple nanoparticulate contrast agents.Methods
Using a simulation study we examined an image-based K-edge ratio method, in which two images acquired from energy windows located above and below the K-edge energy are divided by one another, to identify the exact location of all contrast agents. Multiple computerized phantom studies were conducted using a variety of NP contrast agents with different concentrations. The performance of the proposed methodology was compared to conventional single-kVp and dual-kVp methods using wide range of contrast agents with varying concentrations.Results
The results demonstrate that both single-kVp and dual-kVp energy mapping approaches produce inaccurate attenuation maps at 511 keV in the presence of multiple simultaneous contrast agents. In contrast, the proposed method is capable of handling multiple simultaneous contrast agents, thus allowing suppression of 511 keV attenuation map inaccuracy.Conclusion
Attenuation map produced by spectral CT clearly outperforms conventional single-kVp and dual-kVp approaches in the generation of accurate attenuation maps in the presence of multiple contrast agents. 相似文献8.
Comparison of integrated whole-body [11C]choline PET/MR with PET/CT in patients with prostate cancer
Michael Souvatzoglou Matthias Eiber Toshiki Takei Sebastian Fürst Tobias Maurer Florian Gaertner Hans Geinitz Alexander Drzezga Sibylle Ziegler Stephan G. Nekolla Ernst J. Rummeny Markus Schwaiger Ambros J. Beer 《European journal of nuclear medicine and molecular imaging》2013,40(10):1486-1499
Purpose
To evaluate the performance of conventional [11C]choline PET/CT in comparison to that of simultaneous whole-body PET/MR.Methods
The study population comprised 32 patients with prostate cancer who underwent a single-injection dual-imaging protocol with PET/CT and subsequent PET/MR. PET/CT scans were performed applying standard clinical protocols (5 min after injection of 793?±?69 MBq [11C]choline, 3 min per bed position, intravenous contrast agent). Subsequently (52?±?15 min after injection) PET/MR was performed (4 min per bed position). PET images were reconstructed iteratively (OSEM 3D), scatter and attenuation correction of emission data and regional allocation of [11C]choline foci were performed using CT data for PET/CT and segmented Dixon MR, T1 and T2 sequences for PET/MR. Image quality of the respective PET scans and PET alignment with the respective morphological imaging modality were compared using a four point scale (0–3). Furthermore, number, location and conspicuity of the detected lesions were evaluated. SUVs for suspicious lesions, lung, liver, spleen, vertebral bone and muscle were compared.Results
Overall 80 lesions were scored visually in 29 of the 32 patients. There was no significant difference between the two PET scans concerning number or conspicuity of the detected lesions (p not significant). PET/MR with T1 and T2 sequences performed better than PET/CT in anatomical allocation of lesions (2.87?±?0.3 vs. 2.72?±?0.5; p?=?0.005). The quality of PET/CT images (2.97?±?0.2) was better than that of the respective PET scan of the PET/MR (2.69?±?0.5; p?=?0.007). Overall the maximum and mean lesional SUVs exhibited high correlations between PET/CT and PET/MR (ρ?=?0.87 and ρ?=?0.86, respectively; both p?<?0.001).Conclusion
Despite a substantially later imaging time-point, the performance of simultaneous PET/MR was comparable to that of PET/CT in detecting lesions with increased [11C]choline uptake in patients with prostate cancer. Anatomical allocation of lesions was better with simultaneous PET/MR than with PET/CT, especially in the bone and pelvis. These promising findings suggest that [11C]choline PET/MR might have a diagnostic benefit compared to PET/CT in patients with prostate cancer, and now needs to be further evaluated in prospective trials. 相似文献9.
Sebastian Lehner MD Christian Sussebach MD Andrei Todica MD Christopher Uebleis MD Stefan Brunner MD Peter Bartenstein MD Serge D. Van Kriekinge PhD Guido Germano PhD Marcus Hacker MD 《Journal of nuclear cardiology》2014,21(3):578-587
Background
To evaluate the influence of SPECT attenuation correction on the quantification of hibernating myocardium derived from perfusion SPECT and 18F-FDG PET.Methods and Results
20 patients underwent rest 99mTc-tetrofosmin perfusion SPECT/CT and 18F-FDG PET/CT. Perfusion images were reconstructed without attenuation correction (NC), with attenuation correction based on the CT from the SPECT/CT (AC_SPECT), and with attenuation correction based on the CT from the PET/CT (AC_PET). Another 56 patients had rest 99mTc-tetrofosmin perfusion SPECT and 18F-FDG PET/CT. Perfusion images were reconstructed as NC and AC_PET. The amounts of hibernating myocardium and scar were quantified with QPS® and corresponding AC and NC normative databases. In both cohorts, perfusion in the inferior wall was higher in the AC scans than without AC. Global and regional values for total perfusion deficit (TPD), hibernation and scar areas did not differ between NC, AC_SPECT, and AC_PET scans. In a retrospective evaluation with 7% cut-off of hibernating myocardium as a condition for revascularization, the therapeutic approach would have been altered in 5 of 56 patients, if the AC_PET approach had been used.Conclusions
AC of SPECT perfusion scans with an attenuation map derived from PET/CT scans is feasible. If AC is unavailable, perfusion scans should be compared to NC normative databases for assessing TPD, hibernation, and mismatch. It should be taken into account that in approximately 10% of the patients, a therapeutic recommendation based on published thresholds for hibernating myocardium would be altered if NC scans were used as compared to AC scans. 相似文献10.
Eku Shimosegawa Kouichi Fujino Hiroki Kato Jun Hatazawa 《Annals of nuclear medicine》2013,27(9):822-833
Rationale and objectives
As spreading integrated SPECT/CT scanners, reconstruction method based on three-dimensional ordered-subset expectation maximization (3D-OSEM) with attenuation correction (AC) using an X-ray CT image (CTAC) is easily available in brain imaging. For quantitative cerebral blood flow (CBF) measurements, however, the accuracy of this method has not been fully evaluated clinically. To validate this new algorithm, we sequentially studied quantitative PET-CBF and SPECT-CBF measurements in the same healthy volunteers and compared CBF values.Methods
Ten healthy subjects underwent quantitative PET-CBF and SPECT-CBF measurements on the same day. PET-CBF data were obtained by the intravenous injection of O-15 water and the quantitative IMP-ARG method followed. Three types of SPECT images were reconstructed: (1) filtered back projection (FBP) with Chang’s AC (FBP + Chang’s AC), (2) 3D-OSEM with Chang’s AC (3D-OSEM + Chang’s AC), and (3) 3D-OSEM with CTAC (3D-OSEM + CTAC). The mean CBF difference, the linearity, and the correlation between the PET-CBF and SPECT-CBF values were compared among the SPECT reconstruction algorithms.Results
The mean SPECT-CBF values of all the algorithms were significantly lower in the pons (P = 0.000–0.007) and higher in the frontal lobe (P = 0.002–0.022). All the SPECT-CBF values were significantly correlated with the PET-CBF values (r = 0.749–0.829, P < 0.001). The SPECT-CBF values obtained using the 3D-OSEM + CTAC method showed the best regression with the PET-CBF values.Conclusion
The present clinical study validated accuracy of CBF image reconstructed by the 3-D OSEM method with CTAC and the integrated SPECT/CT system. 相似文献11.
Philipp Heusch Christian Buchbender Karsten Beiderwellen Felix Nensa Verena Hartung-Knemeyer Thomas C. Lauenstein Andreas Bockisch Michael Forsting Gerald Antoch Till A. Heusner 《European journal of radiology》2013
Purpose
To compare maximum and mean standardized uptake values (SUVmax/mean) of normal organ tissues derived from [18F]-fluoro-desoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) using MR attenuation correction (MRAC) (DIXON-based 4-segment μ-map) with [18F]-FDG positron emission tomography/computed tomography (PET/CT) using CT-based attenuation correction (CTAC).Methods and materials
In 25 oncologic patients (15 men, 10 women; age 57 ± 13 years) after routine whole-body FDG-PET/CT (60 min after injection of 290 ± 40 MBq [18F]-FDG) a whole-body PET/MRI was performed (Magnetom Biograph mMR™, Siemens Healthcare, Erlangen, Germany). Volumes of interest of 1.0 cm3 were drawn in 7 physiological organ sites in MRAC-PET and the corresponding CTAC-PET images manually. Spearman correlation coefficients were calculated to compare MRAC- and CTAC based SUV values; Wilcoxon-Matched-Pairs signed ranks test was performed to test for potential differences.Results
The mean delay between FDG-PET/CT and PET/MRI was 92 ± 18 min. Excellent correlations of SUV values were found for the heart muscle (SUVmax/mean: R = 0.97/0.97); reasonably good correlations were found for the liver (R = 0.65/0.72), bone marrow (R = 0.42/0.41) and the SUVmax of the psoas muscle (R = 0.41). For subcutaneous fat, the correlation coefficient was 0.66 for SUVmean (p < 0.05). Correlations between MRAC and CTAC were non-significant for SUVmean of the psoas muscle, SUVmax of subcutaneous fat, SUVmax and SUVmean of the lungs, SUVmax and SUVmean of the blood-pool. The median SUVmax and SUVmean in MRAC-PET were lower than the respective CTAC values in all organs (p < 0.05) but heart (SUVmax) and the bone marrow (SUVmean).Conclusion
In conclusion, in oncologic patients examined with PET/CT and PET/MRI SUVmax and SUVmean values generally correlate well in normal organ tissues, except the lung, subcutaneous fat and the blood pool. SUVmax and SUVmean derived from PET/MRI can be used reliably in clinical routine. 相似文献12.
Felix P. Kuhn David W. Crook Caecilia E. Mader Philippe Appenzeller G. K. von Schulthess Daniel T. Schmid 《European journal of nuclear medicine and molecular imaging》2013,40(1):44-51
Purpose
PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions.Methods
A total of 100 oncological patients underwent sequential whole-body 18F-FDG PET with CT-based attenuation correction (AC), 40?mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization.Results
From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p?<?0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40?% of lesions, equal to CT in 49?%, and inferior to CT in 11?%.Conclusion
Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust. 相似文献13.
BACKGROUND: The advent of dual-modality positron emission tomography/computed tomography (PET/CT) imaging has revolutionized the practice of clinical oncology by improving lesion localization and facilitating treatment planning for radiation therapy. In addition, the use of CT images for CT-based attenuation correction (CTAC) allows the overall scanning time to be decreased and a noise-free attenuation map (micromap) to be created. The most common procedure requires a piecewise linear calibration curve acquired under standard imaging conditions to convert the patient's CT image from low effective CT energy into an attenuation map at 511 keV. AIM: To evaluate the effect of the tube voltage on the accuracy of CTAC. METHODS: As different tube voltages are employed in current PET/CT scanning protocols, depending on the size of the patient and the region under study, the impact of using a single calibration curve on the accuracy of CTAC for images acquired at different tube voltages was investigated through quantitative analysis of the created micromaps, generated attenuation correction factors and reconstructed neurological PET data using anthropomorphic experimental phantom and clinical studies. RESULTS: For CT images acquired at 80 and 140 kVp, average relative differences of -2.9% and 0.7%, respectively, from the images acquired at 120 kVp were observed for the absolute activity concentrations in five regions of the anthropomorphic striatal phantom when CT images were converted using a single calibration curve derived at 120 kVp. Likewise, average relative differences of 1.9% and -0.6% were observed when CT images were acquired at 120 kVp and CTAC used calibration curves derived at 80 and 140 kVp, respectively. CONCLUSION: The use of a single calibration curve acquired under standard imaging conditions does not affect, to a visible or measurable extent, neurological PET images reconstructed using CTAC when CT images are acquired in different conditions. 相似文献
14.
Objective
The CT portion of PET/CT provides attenuation correction of the PET emission scan. This study was performed to evaluate how much the CT tube current can be lowered while still providing attenuation maps on PET images.Methods
Two body phantoms (outside diameters of 300 and 500?mm) were used to investigate, and PET/CT acquisitions were performed with an Aquiduo PCA-7000B (Toshiba Medical Systems, Otawara, Japan). The CT scan was performed with the following parameters (120?kVp; 0.5-s rotation; 10, 20, 40, 80, 160, 200, 320, 460?mA). After the CT scan, PET images for 18F-FDG (5.3?kBq/mL) were obtained for 4?min/bed position. The linear attenuation coefficients for 18F-FDG in 300- and 500-mm phantoms, pixel values and SD of CT images, radioactivity concentration values and hot- and cold-sphere contrast on PET images in the 500-mm phantom were evaluated.Results
In the 300-mm phantom, all eight tube currents gave average linear attenuation coefficients of approximately 0.095?cm?1. In contrast, the average linear attenuation coefficients of the 500-mm phantom at 10, 20, and 40?mA were significantly decreased (0.081, 0.087, and 0.092?cm?1, respectively; p?0.05) as compared to 0.096?cm?1 of the other tube currents. Further, CT pixel values decreased 10 and 20?mA. Thus, the background radioactivity concentration values at 10 and 20?mA were substantially underestimated to be 57 and 80%, respectively (p?0.05); the hot-sphere contrast values at 10 and 20?mA were 0.26 and 0.29; the cold-sphere contrast values at 10, 20, and 40?mA were ?0.33, ?0.16, and 0.08.Conclusions
Although the linear attenuation coefficients in the 300-mm phantom remained the same with varying CT tube currents, the 500-mm phantom yielded significant differences in the range 10?C40?mA. Therefore, the CT tube currents for attenuation correction should be adjusted over 40?mA in obese patients. 相似文献15.
Kamilla Smolarz Bernd Joachim Krause Frank Philipp Graner Franziska Martina Wagner Hans-Jürgen Wester Tina Sell Claudia Bacher-Stier Lüder Fels Ludger Dinkelborg Markus Schwaiger 《European journal of nuclear medicine and molecular imaging》2013,40(12):1861-1868
Purpose
Novel tracers for the diagnosis of malignant disease with PET and PET/CT are being developed as the most commonly used 18F deoxyglucose (FDG) tracer shows certain limitations. Employing radioactively labelled glutamate derivatives for specific imaging of the truncated citrate cycle potentially allows more specific tumour imaging. Radiation dosimetry of the novel tracer BAY 85-8050, a glutamate derivative, was calculated and the effective dose (ED) was compared with that of FDG.Methods
Five healthy volunteers were included in the study. Attenuation-corrected whole-body PET/CT scans were performed from 0 to 90 min, at 120 and at 240 min after injection of 305.0?±?17.6 MBq of BAY 85-8050. Organs with moderate to high uptake at any of the imaging time points were used as source organs. Total activity in each organ at each time point was measured. Time–activity curves (TAC) were determined for the whole body and all source organs. The resulting TACs were fitted to exponential equations and accumulated activities were determined. OLINDA/EXM software was used to calculate individual organ doses and the whole-body ED from the acquired data.Results
Uptake of the tracer was highest in the kidneys due to renal excretion of the tracer, followed by the pancreas, heart wall and osteogenic cells. The mean organ doses were: kidneys 38.4?±?11.2 μSv/MBq, pancreas 23.2?±?3.8 μSv/MBq, heart wall 17.4?±?4.1 μSv/MBq, and osteogenic cells 13.6?±?3.5 μSv/MBq. The calculated ED was 8.9?±?1.5 μSv/MBq.Conclusion
Based on the distribution and dose estimates, the calculated radiation dose of BAY 85-8050 is 2.67?±?0.45 mSv at a patient dose of 300 MBq, which compares favourably with the radiation dose of FDG (5.7 mSv). 相似文献16.
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
Background
New reconstruction algorithms allow reduction in acquisition times or the amount of injected radioactivity. We examined the impact of different corrections on low-count clinical SPECT myocardial perfusion images (MPI) and compared to 82Rb PET/CT. We compared no corrections (NC) to attenuation correction (AC) with and without scatter correction by either a dual-energy-window (AC-DEW) or model-based (AC-ESSE) approach. All reconstructions included resolution recovery.Methods
56 Patients were imaged using a standard rest/stress Tc-99m-tetrofosmin MPI SPECT/CT protocol with an additional half-time acquisition. A 82Rb-rest/stress PET/CT MPI was acquired within 4 weeks. Reconstruction methods were compared using summed rest/stress/difference scores from an objective algorithm (SRS/SSS/SDS).Results
The SRS and SSS for NC were significantly (P < .01) higher than for AC, but well correlated (r ≥ 0.87). The correlation in SRS/SSS among AC, AC-DEW, and AC-ESSE was excellent (r ≥ 0.98). AC-ESSE and AC-DEW had higher SRS (P ≤ .05) than AC, but the SDS values were not significantly different. Concordance with PET normal/abnormal classification was 76% for NC and ≥85% for the AC methods.Conclusion
AC significantly improves the accuracy of low-count myocardial perfusion SPECT half-time imaging for the detection of disease compared to NC. Compared to PET, there was no significant difference among AC, AC-DEW, and AC-ESSE. 相似文献17.
目的 探讨不同浓度泛影葡胺及不同CT扫描条件对PET/CT图像质量和标准摄取值的影响.材料与方法 分别将2%、5%、10%、15%、30%的泛影葡胺溶液置入一圆桶模型中进行PET/CT显像,同时采用CT及37Cs两种衰减方法进行校正.比较不同管电压(90kV、120kV、140kV) CT扫描条件下各浓度泛影葡胺充盈区CT衰减校正(CTAC)和137Cs衰减校正(CsAC)的标准摄取值差异及图像差异.结果 不同管电压CT扫描条件下的CT衰减校正的标准摄取值均随泛影葡胺浓度增加而增加(r=0.977、0.979、0.985,P<0.01),而137Cs衰减校正的标准摄取值则与泛影葡胺浓度无明显相关性(r=0.386,P> 0.05);在本底区、清水充盈区及浓度为2%的泛影葡胺充盈区,各CT衰减校正和137Cs衰减校正的标准摄取值间差异无统计学意义(F=1.222、0.912、0.721,P>0.05);在浓度为5%、10%、15%、30%的泛影葡胺充盈区,CT衰减校正的标准摄取值明显高于137Cs衰减校正值(F=82.571、348.211、569.630、992.746,P<0.01),管电压越高CT衰减校正的标准摄取值越小.在浓度为15%、30%的泛影葡胺充盈区,不同管电压CT扫描条件下的图像均出现18F-FDG高摄取伪影,以140kV下的图像“热区”范围及强度最小,而相同区域的137Cs衰减校正及无衰减校正图像均表现为圆形“冷区”.结论 高浓度(≥5%)的泛影葡胺可使PET图像出现高摄取伪影或标准摄取值的高估,增加CT扫描管电压值可以减轻图像伪影并减小标准摄取值的误差. 相似文献
18.
Tomohiro Ishikita Noboru Oriuchi Tetsuya Higuchi Go Miyashita Yukiko Arisaka Bishnuhari Paudyal Pramila Paudyal Hirofumi Hanaoka Mitsuyuki Miyakubo Yoshiki Nakasone Akihide Negishi Satoshi Yokoo Keigo Endo 《Annals of nuclear medicine》2010,24(2):77-82
Objective
Clinical application of FDG-PET in head and neck cancer includes identification of metastases, unknown primary head and neck malignancy, or second primary carcinoma, and also recurrent tumor after treatment. In this study, the additional value of PET/CT fusion images over PET images alone was evaluated in patients with initial staging and follow up of head and neck malignancy.Methods
Forty patients with suspected primary head and neck malignancy and 129 patients with suspected relapse after treatment of head and neck malignancy were included. FDG-PET/CT study was performed after the intravenous administration of FDG (5 MBq/kg). Target of evaluation was set at primary tumor, cervical lymph node, and whole body. PET images and PET with CT fusion images were compared. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Results of PET and PET/CT were compared with postoperative histopathological examination, and case by case comparison of PET and PET/CT results for each region was performed. The additional value of CT images over PET only images was assessed. Statistical differences in sensitivity and specificity were evaluated.Results
In the comparative evaluation of 507 targets by PET alone and PET/CT, 401 targets showed agreement of the results. Of the 106 discordant targets, 103 showed a positive result on PET alone and negative result on PET/CT. These results showed a significant difference (p < 0.01). Sensitivity of PET/CT was slightly higher than that of PET without statistical significance, while specificity of PET/CT was significantly higher than that of PET alone (Initial staging: 90.5% vs. 62.2%, p < 0.01; Follow up: 97.2% vs. 74.4%, p < 0.01). In Fisher’s direct probability test, a significant difference was noted in the sensitivity (Initial staging: 91.3% vs. 87.0%, p < 0.01; Follow up: 93.9% vs. 91.4%, p < 0.01).Conclusions
Combined PET/CT showed improved diagnostic performance than PET alone by decreasing the number of false positive findings in patients with initial staging and follow up of head and neck malignancy. 相似文献19.
R. Glenn Wells Karen Soueidan Karen Vanderwerf Terrence D. Ruddy 《Journal of nuclear cardiology》2012,19(4):719-726
Background
For SPECT, CT-based attenuation correction is preferred. Many different models of CT are available with SPECT/CT systems. Our study compares clinical cardiac SPECT images that were attenuation corrected using slow-rotation CT and high-speed CT transmission scans.Methods
We evaluated 59 rest/stress perfusion studies from patients who had undergone both a SPECT/CT with a slow-rotation CT and a perfusion study on a PET/CT camera equipped with a high-speed CT scanner. Each SPECT study was reconstructed with transmission maps from both CT scans and the relative perfusion was assessed using semi-automated software. The summed stress/rest/and difference scores (SSS/SRS/SDS) were compared as well as the test classification.Results
The intraclass correlation coefficients for the SSS, SRS, and SDS were 0.97, 0.96, and 0.80 respectively. There were no significant differences in the mean SSS, SRS, or SDS with the use of either CT for attenuation corrections. Classifying SSS?>?3 as abnormal, there was 97% concordance (???=?0.88). Classifying SDS?>?1 as abnormal, there was 95% concordance (???=?0.54). A McNemar??s test showed no significant differences.Conclusions
There were no significant differences between using a high-speed CT and using a slow-rotation CT for attenuation correction of SPECT myocardial perfusion images. 相似文献20.
Koen Van Laere Rawaha U. Ahmad Hendra Hudyana Sofie Celen Kristof Dubois Mark E. Schmidt Guy Bormans Michel Koole 《European journal of nuclear medicine and molecular imaging》2013,40(2):254-261