Search

The ordered subset expectation maximization with a point spread function (OSEM-PSF) was developed to improve the spatial resolution of reconstructed positron emission tomography (PET) images and has been reported to improve the contrast of hot spots in PET studies for oncology. However, in neuroreceptor imaging, the regional radioactivity concentration changes dynamically during the scan, and the effects of the PSF may differ among various radioligands or quantification methods. In this study, we investigated the effects of the PSF on quantification in PET studies with [11C]FLB 457 of dopamine D2 receptors, using both phantom and human data acquired by the Siemens Biograph 16 imaging platform. In the phantom studies, we evaluated the hot contrast recovery coefficient (HCRC) for variously sized hot spheres and the linearity between the measured and true radioactivities in OSEM-PSF images. Next, in the human studies with [11C]FLB 457, radioactivity concentrations and binding potentials for the cerebral cortex and thalamus were compared between images reconstructed with and without PSF. In the phantom studies, the OSEM-PSF images showed a better HCRC compared to images without PSF, and they showed a good linear correlation with true radioactivity. In the human studies, the radioactivity concentration increased especially in small regions with high accumulation of [11C]FLB 457 when the PSF was included. However, little difference in the binding potentials was observed for the target regions between both types of reconstructed images. In conclusion, PSF-based reconstruction reduced the spill-over phenomena in small hot regions; however, it caused no increase in the binding potentials in the [11C]FLB 457 studies.

Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (mu-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (mu-values). In this study, we proposed an MRI-based mu-value estimation method with a non-rotational radiation source to construct a suitable mu-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the mu-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The mu-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the mu-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4+/1.4%, 17.4+/-9.1% and 6.6+/-4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain mu-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain.

第５４回千葉核医学研究会

Several MRI-based attenuation correction methods have been reported for PET/MRI. The accuracy of the attenuation map (mu-map) from an MRI image depends on correctness of the segmentation of tissue and the attenuation coefficients to be assigned (mu-values). However, an MRI image does not reflect the attenuation of radiation and inaccurate assignment of mu-values affects the quantitative assessment of functional images of PET. Although installation of a transmission scan function on the PET/MRI can provide an accurate mu-map, it restricts the design of the scanner, increases the manufacturing cost and takes additional scanning time. In this study, we proposed an MRI-based mu-value estimation method with a non-rotational radiation source to construct the proper mu-map for PET/MRI. The proposed method uses the accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position radiation source which usually rotates around the subject to obtain the mu-map with the tomographic procedure. According to the Lambert-Beer law, attenuated intensity is described as the function of partial path length and mu-values of every tissue. The partial path length could be estimated by the simulation of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The mu-values of every tissue could be estimated by inverting the function. The simulation results, based upon measurement data, showed the averaged errors between mu-values of the conventional transmission scan and our proposed method were 2.3%, 18.6% and -11.1% for brain, bone and soft tissue other than brain, respectively. Although there were over- and under-estimations for bone and soft tissue, respectively, the present method is able to estimate the brain mu-value accurately and that strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain., IEEE NSS/MIC/RTSD 2013

Adoption of metabolic imaging with F-18-FDG in staging and follow up of cancers needs tumor metabolism parameters like standardized uptake value (SUV). SUVmax,the value of the single voxel with the maximum intensity, avoids inter-observer differences, but a major drawback of SUVmax is its susceptibility to noise in the data. SUVpeak defined as the largest possible mean value of a 1 cm3 spherical VOI positioned within a tumor removes inter-observer variation and reduces the susceptibility to noise. In this study we compared SUVpeak against SUVmax of glucose metabolic activity of pancreas cancer, and assessed how much the SUVpeak was likely to differ from SUVmax using Bland-Altman plot. Method: A total of 53 patients (35 males, 18 females; mean age, 67+-8 y) with pancreas cancer underwent F-18-FDG PET/CT scan in pre-and post-carbon ion radiotherapy. All patients were followed more than 1 year after treatment. The following parameters were measured: maximum standardized uptake value (SUVmax) and peak SUVs (SUVpeak6, SUVpeak10, SUVpeak15). SUVpeak6, SUVpeak10 and SUVpeak15 are measured using spherical VOI with radius 6 mm, 10 mm and 15 mm, respectively, where the volume of spherical VOI of SUVpeak6 is almost 1 cm3. The overall survival was estimated using the Kaplan-Meier method with SUVs as prognostic variables. Bland-Altman plots were used to evaluate difference between SUVmax and SUVpeak in pre-and post-treatment scan. Results: Cutoff values for each SUV were defined by ROC analysis, and the probability of survival was significantly lower with increasing FDG uptake measured by all the kinds of SUVs in both pre-and post-treatment. Significant correlations were observed between SUVmax and SUVpeak6, SUVpeak10 or SUVpeak15 in both pre-and post-treatment. However, proportional bias was observed between SUVmax and SUVpeak6, SUVpeak10 or SUVpeak15 in both pre-and post-treatment as revealed by the Bland-Altman plot analysis. The Bland-Altman analysis illustrated that the 95% limits of agreement is smaller between SUVmax and SUVpeak6 (range: pre 0.25, post 0.16) than between SUVmax and SUVpeak10 (range: pre 0.40, post 0.23), and is also smaller between SUVmax and SUVpeak10 than between SUVmax and SUVpeak15 (rang: 0.62, post 0.35). Conclusions: SUVmax and SUVpeak were statistically significant prognostic variables for overall survival estimated using the Kaplan-Meire method. SUVmax as FDG-PET uptake parameter was correlated closely to SUVpeak, but there was proportional bias between SUVmax and SUVpeak. The smaller the sphere's radius of SUVpeak the smaller the 95% limits of agreement is., EANM'13 - Annual Congress of the European Association of Nuclear Medicine

Objectives: FBP is a standard method for quantitative analysis in human neuroreceptor binding assay, while OS-EM is used widely in tumor PET imaging. Owing to noise propagation from projection data, especially at high subset number, OS-EM leads to loss of signal to noise (SNR) and quantitative accuracy. A novel reconstruction algorithm DRAMA can suppress the noise propagation by using dynamic relaxation parameter with faster convergence compared to OSEM algorithm. In this study, we compared regional radioactivity concentrations and binding potential (BP) values between FBP, OS-EM and DRAMA to assess the effect of DRAMA algorithm on estimating human nuroreceptor binding. Methods: The PET scanning was carried out with Eminence Sophia(shimadzu corp.) . After 4min pre-injection transmission scan, [11C] FLB457, 90min dynamic PET scans were performed with 3D acquisition mode. To compare reconstruction parameter, a phantom scan was done with same scan protocol. Images were reconstructed with FBP, OSEM and DRAMA to assess quantitative accuracy and noise characteristics. Results: To evaluate the SNR, we performed the image quality tests along with NEMA NU-2 2007. Noise of DRAMA was 7% lower than that of FBP. On the other hands, Q10/N10 number of DRAMA was 5.3% higher than that of FBP,similarly, it is 3.5% higher than that of OS-EM. In patient study, the difference of BP by OSEM with iteration 4, subset 16 compared to FBP was+3.17% at maximum in the caudate, while that of DRAMA was +1.59%. Conclusions:There were no significant differences of BP values in thalamus,frontal cortex, temporal cortex and occipital cortex between DRAMA and FBP. Furthermore, noise propagation was not shown in DRAMA in phantom studies. These results indicated that DRAMA could provide similar performance of FBP with the improved SNR, therefore, DRAMA can be a novel standard reconstruction method of neuroreceptor PET studies., EANM'13 - Annual Congress of the European Association of Nuclear Medicine

Objective Various parameters are used for measuring tumor glucose metabolic activity with 18F-FDG PET including measuring the single maximum pixel value within the slice with highest radioactivity concentration (SUVmax) or placing a fixed ROI in the area of the tumor with the highest level of 18F-FDG uptake (SUVpeak), which it defines as the largest possible mean value of a spherical VOI with radius 10 mm positioned within a tumor (SUVpeak10). It is said that the amount of tumor stroma correlates with prognosis of patients with cancer. We estimated the amount of tumor stroma with 18F-FDG-PET using SUVmax and SUVpeak10, and evaluated the prediction performance of the amount of tumor stroma with 18F-FDG-PET after surgery of pancreatic cancer. Methods Sixteen pre-surgery patients with either proven or suspected primary pancreatic cancer underwent 18F-FDG-PET/CT. The pathologically confirmation found out 13 malignancy in all cases. According to pathological findings, the stroma of tumors were quantitatively classified in 3 types (Scirrhous type: abundant stroma, Intermediate type: a type intermediate between the scirrhous type and the medullary type, and Medullary type: scanty stroma). We evaluated the correlation between the amount of tumor stroma and each 3 indexes, SUVmax, SUVpeak10 and SUVstroma. SUVstroma was calculated by the following equation: SUVstroma =1- [SUVpeak10] / [SUVmax] 18F-FDG accumulates in tumor cells but does not accumulate so much in stromal cells. The tumor with abundant stroma might be low SUVpeak10, so SUVstroma might be high. Because the tumor cell avidly accumulates 18F-FDG but stroma does not so much. Each 3 indexes of SUV (SUVmax, SUVpeak10 and SUVstroma) were statistically compared with 3 types of stroma classification using the Mann-Whitney's U test. The overall survival (OS) was calculated using Kaplan-Meier method by SUVs found statistically-significant with Mann-Whitney's U test. Results There was no patient with Medullary type in our cases. Statistically-significant difference was observed between Scirrhous type and Intermediate type in SUVstroma (p0.3 had markedly lower OS rate than those with SUVstroma, EANM'13 - Annual Congress of the European Association of Nuclear Medicine

The ability to make quantitative measurements of radioactivity is extremely essential for human brain PET. Recently, several MRI-based attenuation correction methods that estimate the spatial distribution of the attenuation coefficient (mu-map) for a PET/MRI scan have been reported. The accuracy of mu-map from an MRI image depends on correctness of tissue segmentation and attenuation coefficients to be assigned (mu-values). In our previous study, we developed a hybrid segmentation-atlas method for PET attenuation correction in PET/MRI and demonstrated that can provide the accurate tissue segmentation reflecting mu-value differences [1]. In this study, we focused on the estimation of mu-values to construct the proper mu-map for human brain PET/MRI. Figure 1 shows the brief procedure and schematic diagram of the proposed method. An external radiation source was placed at the fixed position and the radioactive attenuation by tissue was acquired with PET detectors. In addition, partial pathlengths of tissues are calculated from the simulation on the virtual scanner with the segmented MR image. The mu-values of tissues are calculated by inverting the linear system; y=Ax, where y is the radioactive attenuation vector of m detectors ln(I0/I), x is the mu-value vector of n tissues and each element of matrix A is the partial pathlength of radiation ray in n-th tissue from the source to the m-th detector. The proposed method was evaluated on the simulation with the mu-map and T1-weighted image (T1WI) of a human head acquired. The T1WI was segmented into air, bone, brain and soft tissues other than brain. The simulation of the transmission scan was performed by Geant 4.9.6. The bore of virtual HR+ scanner was divided into elements that equal to the voxel size of acquired mu-map. The intra-voxel radiation pathlength were calculated from the source to every detector. The radioactive attenuation was calculated from the sum of products between the acquired mu-map and intra-voxel radiation pathlength on the way to each detector. The partial pathlength of each tissue was calculated on the segmented T1WI. Figure 2 shows the acquired mu-map and T1WI and the segmented image. Figure 3 shows histograms of error rates on estimated and actual mu-values for bone, brain and soft tissue. The error rate is defined as (muact.(r)-muest.)/muact.(r), where r is the position vector of voxels. The estimated mu-value of brain agrees well with actual value. However, the estimated mu-values of bone and soft tissue are over- and under estimated, respectively. The accuracy of the estimation may depend on the length of radiation pathrength for each tissue. Our previous study showed the accuracy of brain mu-value strongly affects on quantitative measurements of radioactivity for the human brain PET, while that of bone and soft tissue affects a little [2]. In conclusion, the proposed method contributes to quantitative measurements of radioactivity for the human brain PET/MRI. Additionally, this method can decrease the production cost for rotation system, increase the freedom of mechanical design and reduce additional several minutes for every PET scan compared with the conventional transmission scan. \nReferences [1] A. Tanigawa, et al. "Hybrid segmentation-atlas method for PET-MRI attenuation correction" , IEEE NSS-MIC 2012, M10-54. Anaheim, USA, 2012. [2] Kawaguchi et al., "Evaluation of MRI-based attenuation correction methods for quantitative human brain PET", International Forum on Medical Imaging in Asia 2012, O6-4, Daegeon, Korea, 2012., PSMR 2013 / 4th Julich MR-PET Workshop

The ability to make quantitative measurements of radioactivity is essential for human brain PET. Several attenuation correction methods have been reported for PET/MRI scanners, however, their influence on pixel intensity in reconstructed images has not yet been thoroughly evaluated. In this study, we evaluated the effect of these potential problems on human brain 18F-FDG-PET. The results indicate that pixel intensities on reconstructed images depend on the attenuation correction method used. Incorrect assignment of the attenuation coefficient for brain causes a larger error in the measured radioactivity than for bone and soft tissues., 2nd SNU-NIRS Workshop on Nuclear Medicine Imaging Science and Technology

The ability to make quantitative measurements of radioactivity is essential for human brain PET. Several attenuation correction methods have been reported for PET/MRI scanners, however, their influence on pixel intensity in reconstructed images has not yet been thoroughly evaluated. In addition, when a transmission scan is unavailable assigning literature values for the attenuation coefficient can be problematic. In this study, we evaluated the effect of these potential problems on human brain 18F-FDG- PET. The results indicate that pixel intensities on reconstructed images depend on the attenuation correction method used. Incorrect assignment of the attenuation coefficient for brain causes a larger error in the measured radioactivity than for bone and soft tissues. Moreover, the influence of an incorrect attenuation coefficient for brain is larger in deep gray matter, such as the striatum and thalamus, than in the occipital and temporal cortices. In contrast, an incorrect attenuation coefficient for bone and superficial soft tissue has a larger influence on cortical pixel intensities than on those in deep gray matter. According to the present results, it is necessary to assign the attenuation coefficients to be within 5% of the true value to achieve an error of within 5% of the true pixel intensity on the reconstructed image. This accuracy is needed when performing PET/MRI on subjects with age-related brain atrophy or brain diseases such as hydrocephalia where the attenuation coefficient can differ from its value in normal subjects., International Forum on Medical Imaging in Asia (IFMIA 2012)

Purpose: Various parameters are used for measuring tumor glucose metabolic activity with 18F-FDG PET including measuring the single maximum pixel value within the slice with highest radioactivity concentration (SUVmax) or placing a fixed ROI in the area of the tumor with the highest level of 18F-FDG uptake (SUVpeak), which it defines as the largest possible mean value of a 1 cm3 spherical VOI positioned within a tumor. SUVmax is avoided inter-observer variation, but a major drawback of this approach is its susceptibility to noise in the data. SUVpeak is also removed inter-observer variation, and the averaging of multiple voxels reduces the susceptibility to noise. In this study we determined which parameter of glucose metabolic activity provided the most robust predictions of patient prognosis of pancreas cancer treated by carbon ion radiotherapy. Materials and Methods: A total of 41 patients (28 males, 13 females; mean age, 65 + 8+- y) with pancreas cancer underwent 18F-FDG PET/CT scan before carbon ion radiotherapy. The following parameters on the pretreatment scans were measured: maximum standardized uptake value (SUVmax), two types of peak SUV (small: SUVpeak5, large: SUVpeak10), and average SUV (SUVave). SUVpeak5 and SUVpeak10 are measured using spherical VOI with radius 5 mm and 10 mm, respectively. SUVave is an average pixel value of the circular ROI with radius 5 mm within the slice with the highest radioactivity concentration. Correlation coefficients were calculated for these parameters, and receiver operating characteristic (ROC) analysis was performed to compare the prediction performance of each parameter for pancreas patients. Results: Pretreatment SUVmax, SUVpeak5, SUVpeak10, and SUVave averaged 6.6, 6.1, 5.1, and 6.0, respectively. Correlation coefficients between all four parameters, SUVmax and SUVpeak5, SUVmax and SUVpeak10, SUVmax and SUVave, SUVpeak5 and SUVpeak10, SUVpeak5 and SUVave, SUVpeak10 and SUVave, were 0.995, 0.964, 0.994, 0.973, 0.995, and 0.969, respectively. The areas under the ROC curve of SUVmax, SUVpeak5, SUVpeak10, and SUVave were 0.69, 0.69, 0.92, and 0.70, respectively. ROC curves of SUVmax, SUVpeak5 and SUVave were closely approximated to each other, but the ROC curve of SUVpeak10 was different from others and much better than others. Conclusions: Four FDG-PET uptake parameters were correlated closely. ROC analysis showed that SUVpeak10 was much better than others for prediction of pancreas patient prognosis. It seemed that relatively large sphere for calculating SUVpeak is better than small sphere if the tumor is large enough for setting the sphere within it., Annual Congress of the European Association of Nuclear Medicine

Objective FDG-PET provides quantitative information regarding the tumor glucose metabolism which is useful for the clinical diagnosis of tumor diseases. It is said that the amount of tumor stroma correlates with prognosis of patients with cancer. FDG accumulates in cancer cells but does not accumulate so much in stroma tissues. So cancer tissue with abundant stroma might show relatively lower accumulation of FDG than that with scanty stroma. We estimated the amount of tumor stroma with FDG-PET (STRpet), and evaluated prognosis of patients using STRpet after surgery of pancreatic cancer. Methods Sixteen pre-surgery patients with either proven or suspected primary pancreatic cancer underwent FDG- PET/CT. The pathologically confirmation found out 13 malignancy in all cases. The STRpet in tumor was evaluated for the 13 cases with the following equation: STRpet = [Mean value of spherical VOI of 10mm in radius with SUVmax in the center of it] / [SUVmax] The tumor with abundant stroma might be low STRpet, because the tumor cell accumulates FDG avidly but stroma does not so much. According to pathological findings, the stroma of tumors (STRpatho) were quantitatively classified in the following 3 types (Scirrhous type: abundant stroma, Intermediate type: a type intermediate between the scirrhous type and the medullary type, and Medullary type: scanty stroma). The STRpet were statistically compared with STRpatho using the Mann-Whitney's U test. The 1-year disease- free survival (DFS) and overall survival (OS) for STRPEt and STRpatho were calculated using Kaplan-Meier method. Results There is no patient with Medullary type in our cases. Statistically-significant difference was observed in STRpet between Scirrhous type and Intermediate type (p, Annual Congress of the European Association of Nuclear Medicine

Purpose Image reconstruction for most nuro-transmission PET scan data is performed by FBP because of a positive bias caused by the noise propagation in OS-EM algorithm. A positive bias affects the estimation of binding potential (BP) calculated from radioactive concentrations of reference regions and target region in nuroreceptor binding assay. To suppress the noise propagation in OS-EM algorithm, the hybrid wavelet shrinkage (HWS) filter is developed. In this study, we performed the phantom study to evaluate the effect of HWS filter on noise propagation in OS-EM algorithm. \nMaterials and Methods Phantom studies are performed by SET-3000GCT/X (shimadzu corp). To evaluate the effect of the HWS filter, we planned the some phantom study. IEC body phantom filled with 18F (activity concentration ratios relative to background of 4:1) are used for evaluation of image quality. A pool phantom filled with 18F (11.4kBq/ml) is scanned by dynamic scan mode for evaluation the quantification of PET image. Prior to emission scans, a transmission scan (6min) for attenuation correction with a 137Cs point source with a BGO transmission detector ring coaxially attached to the GSO emission detector ring. Reconstruction parameters of PET images are follows; FBP with Gaussian filter 5.0mm, OS-EM, OS-EM with HWS filter (OS-EMw). Iteration numbers in OS-EM algorithm are varied from 1 to 100 to evaluate the noise propagation. \nResults In pool phantom study, a positive bias at low count rate is shown in PET images reconstructed by OS-EM algorithm, while any biases are not shown in images reconstructed by FBP and OS-EMw algorithm. The N10 values are diverged due to noise propagation in OS-EM algorithm while N10 values calculated from PET image reconstructed by OS-EMw algorithm are convergence at the point of 10 iterations in IEC body phantom study. Similarly, the Q10 values are diverged depends on iteration number in OS-EM algorithm while that of OS-EMw has fast convergence. Furthermore, these results indicate that OS-EMw has the fast convergence of pixel number and suppress the noise propagation. \nConclusion According to our study, OS-EMw has fast convergence and suppresses the noise propagation in OS-EM algorithm. These results show that HWS filter can be a standard de-noising method for nuro-recptor PET imaging with OS-EM algorithm., Annual Congress of the European Association of Nuclear Medicine

Background: We found inter-scanner differences in dopamine receptor imaging. In order to evaluate different effects of physical performances on tracer kinetics images, we tested accuracy in deadtime correction and scatter correction using phantoms mimicked the head and whole body of human subject. \nMethods: The two PET scanners used were Eminence Sophia (Shimadzu, Corp) and EXACT HR+ (Siemens). Each scanner was tested the following examinations. The deadtime correction was tested using Hoffman phantom filled by 3mCi C-11 radioactivity. The effects of the scatter emitted from the whole bogy were evaluated using three uniform pool phantoms, one inside of FOV mimicking the head and two outside of FOV mimicking the whole body. These pools are filled by 3 mCi of [C-11] radioactivity for the inside of FOV and two of 12 mCi for the outside FOV. Dynamic scan were performed over 4 hours. Images were reconstructed by the filtered back-projection method. Images were analyzed using PMOD. \nResults: Both PET scanners did not show any significant systematic errors in the deadtime correction. The existence of a massive (8 times) radioactivity in the outside the FOV was overestimated image concentrations of the pool at the inside FOV by 10% in Eminence, and this overestimation was continued till the radioactivity was decayed. However, the overestimation was reduced less than a few percent after software correction. In HR+ scanner, the same experiment resulted in the underestimation of the image concentration by 10-20% for the early phase but the underestimation was become negligible in late phase. \nConclusions: The phantom studies mimicking the head and whole body for the receptor imaging did not explain the inter-scanner difference in dopamine imaging, The 9th International Symposium on Functional Neuroreceptor Mapping of the Living Brain (NRM12)

Objectives: Positron emission tomography with [11C]raclopride and [11C]FLB457 has been utilized for imaging dopamine D2 receptors in the striatum and extrastriatum, respectively. PET scans with these ligands require 60-90 min consecutive acquisition for a quantitative analysis. Therefore, head movement is often observed during scanning, and it hampers the reliability of quantitative outcomes, especially for small brain structures. Image-based motion correction with frame-to-frame realignment is a practical method, since it dose not require motion information obtained by an online tracking system. However, frame-to-frame realignment for emission PET images causes a mismatch between the emission scan and transmission scan used for the attenuation correction, and it may result in the error of quantitative analysis. In the present study, optimal image-based motion correction method including the transmission scan was evaluated for PET studies with [11C]raclopride and [11C]FLB457, and investigated the effect of this correction method on quantitative analysis outcomes. Methods: In 60-min dynamic PET scan with [11C]raclopride and 90-min dynamic PET scan with [11C]FLB457, emission sinograms were reconstructed with or without attenuation correction. In the first method, 6 motion parameters (x-translation, y-translation, z-translation, roll, pitch, and yaw) were estimated frame-by-frame by realigning each frame of attenuation corrected image (AC) with a reference image using normalized mutual information [1]. Four kinds of images were used as the reference image for realignment, those are, summed image of all frames, summed image of the first 2 min, one frame image with high count, and MR image coregistered to PET summation image. Meanwhile, in the second method, motion parameters were estimated by realigning each frame of non-attenuation corrected images (NAC) by a similar way. Then µ-map obtained from a transmission scan was realigned using estimated motion parameters to correct a mismatch between the transmission and emission scans [2], and attenuation correction and reconstruction were performed sequentially. After motion correction, time-activity curves (TAC) for the striatum or frontal cortex were obtained. The binding potentials (BP) were estimated for these TACs by a simplified reference tissue model with the cerebellum as a reference region, and compared with BP estimates before the correction. Results: The motion correction using NAC images could realign each frame image to every reference images for both [11C]raclopride and [11C]FLB457 studies, and the mismatch between the emission and transmission scan was also corrected using estimated motion parameters. However, the motion correction using AC images did not realign each frame image. After the correction with NAC, a discontinuity of TACs in the striatum and frontal cortex was improved. In the subject with the large movement during PET scanning, BP value of the striatum increased about 25% after the motion correction. Conclusion: Head movement during the PET dynamic scan with [11C]raclopride and [11C]FLB457 could be accurately corrected by applying the image-based realignment to non-attenuation corrected images., The 9th International Symposium on Functional Neuroreceptor Mapping of the Living Brain (NRM2012)

Objectives: FDG-PET provides quantitative information regarding the tumor glucose metabolism which is useful for the clinical diagnosis of tumor diseases. A diffusion weighted image (DWI) by MRI can be useful in detecting malignancies similar to FDG-PET imaging. We studied the potential prognostic significance of pre-surgery FDG-PET and MRI in pancreatic cancer. Materials and Methods: Pre-surgery patients with either proven or suspected primary pancreatic cancer underwent a FDG-PET/CT and DWI by MRI. The malignancy or benignancy of excised specimens was pathologically confirmed in all cases. The apparent diffusion coefficient (ADC) was measured with DWI. We obtained standardized uptake value (SUV) in PET image. We can slightly improve SUV by using blood glucose corrected SUV (SUV*g: SUV X blood glucose level). The value of each factor for differential diagnosis of tumor malignancy was determined by receiver operating characteristic (ROC) analysis with suspected pancreatic cancer. Similarly, the predictive value of each factor for 1-year disease-free survival (DFS) and overall survival (OS) were determined by ROC analysis with proven pancreatic cancer. Results: On ROC analysis for differential diagnosis of tumor malignancy, the areas under the curve (AUC) of ADC, SUV and SUV*g were 0.830, 0.855 and 0.892, respectively. We considered that these three factors were good indexes for the diagnosis of tumor malignancy. For DFS, the AUC of ADC, SUV and SUV*g were 0.600, 0.843 and 0.811, respectively. The AUC of SUV and SUV*g were larger than the AUC of ADC. For OS, the AUC of ADC, SUV and SUV*g were 0.573, 0.648 and 0.867, respectively. The AUC of SUV*g was larger than the AUC of ADC and SUV. The SUV and SUV*g of FDG-PET/CT might be better indexes for estimation of prognosis. The 1-year DFS rate above the cutoff (SUV>4.3, SUV*g>400) were markedly lower than the rate below the cutoff (SUV>4.3, SUV*g>400) (0% vs. 67% p400) tended to be lower than the rate below the cutoff (SUV*g>400) (0% vs. 57%, p=0.06). Conclusions: The results of FDG-PET/CT were significantly associated with outcome after definitive therapy of pancreatic cancer. FDG-PET/CT in preoperative evaluation of pancreatic tumor might be useful not only for differential diagnosis of tumor malignancy but also for estimation of prognosis., The 2011 EANM Congress

EANM'11 - Annual Congress of the European Association of Nuclear Medicine

[Purpose] Detecting the distribution of positron emitter generated by nuclear fragmentation reaction in carbon ion beam therapy (auto-activation) applied at Heavy Ion Medical Accelerator in Chiba (HIMAC) by means of positron emission tomography (PET) is novel method for therapy quality assurance especially assessing irradiated area. Since a new 3D irradiation system with pencil-beam scanning (fast- scanning system) has been developed at NIRS, and we are planning to assess the accuracy of the delivered dose distribution by clinical auto-activation PET study. In preparation for this purpose, we performed some phantom experiments for determine optimal scan duration and compare PET image quality of auto-activation PET study between conventional irradiation system and fast scanning system. \n[Materials and Methods] A SET-3000GCT/X (PET/CT; Shimadzu Corp.) dedicated to the 3D-acquisition mode is used for auto-activation PET imaging. It uses gadolinium oxyorthosilicate (GSO) detectors and provides 99 sections with a center-to-center distance of 2.6mm. To determine the optical scan duration, the phantom irradiated with carbon-ion beam is scanned for 60min in list-mode, then a 5min transmission scan with a 137Cs point source is performed. Before reconstruction, list-mode events are histogrammed as PET raw data obtained at each acquisition time (10, 20, 30, 40, 50 and 60min). The emission images are reconstructed with the manufacturer software using Fourier rebinning followed by 2D-dynamic-RAMLA. Reconstructed images are evaluated visually and normal mean square error (NMSE) is assessed. In addition, image noise is derived from region-of-interest (ROI) analysis. Image noise was defined as the coefficient of variation (COV, 100 x SD/mean [%]) of the pixel values within a homogeneous ROI. \n[Results] There is no obvious difference of image quality between 40min acquisition and 60min acquisition by visually evaluation. Based on statistical analysis, NMSE value and COV are 0.0017 and 12% at 40min acquisition, respectively, while NMSE value and COV are 0.0023 and 14% at 30 min acquisition, respectively. According to these results, we conclude the 40min acquisition as optimal scan duration for clinical auto-activation PET study. The distribution of positron emitters generated by carbon ion beam for a clinical target volume (CTV) is slightly larger in fast-scanning system compared with conventional irradiation system. The difference is all explained by presence of penumbra in fast-scanning system. These results show that auto-activation PET method can visualize precisely the absorbed radiation area. \n[Conclusions] According to our analysis, it is clarified that auto-activation PET method can detect precisely absorbed radiation area and it plays an important role in quality assurance of heavy ion beam therapy., EANM Annual Congress 2011

Purpose Cu-62labeled diacetyl-bis (N(4)-methylthiosemicarbaone) (Cu-62-ATSM) is a well-knownhypoxic imaging PET tracer. The purpose of this study was to delineate thedifferences in intratumoral uptake and tracer distribution of Cu-62-ATSM andF-18 FDG in patients with pancreas cancer. The comparison of two tracers wasdone before and after carbon ion radiotherapy, and the relationship of traceruptake and patients prognosis was also investigated. Mehod Two male and twofemale (mean age, 62.5 y, range 52-69 y) with pancreas cancer underwent bothCu-62-ATSM and FDG PET/CT before the initiation of carbon ion radiotherapy(CIRT), and the set of PET/CT studies was done one month after termination ofCIRT. Two whole-body PET/CT scanners, Biograph-16 (Siemens) and Aquiduo(Toshiba) were used for data acquisition. Cu-62-ATSM and FDG were administratedapproximately 740 MBq and 370 MBq, respectively. Tumor uptake of each tracerwas analyzed semi-quantitatively by tumor to normal tissue ratio (TNR) forCu-62-ATSM and by standardized absorption value (SUV) for FDG. Result Cu-62-ATSMuptake didnt correlate with FDG uptake before CIRT, but it inverselycorrelated with FDG after CIRT because FDG uptake tended to decrease in allcases. Correlation coefficient of tumor uptake between Cu-62-ATSM and FDGbefore and after CIRT was 0.022 and -0.965, respectively. Average Cu-62-ATSMand FDG uptake before CIRT were 2.9 TNR (range 1.4-3.6 TNR) and 6.7 SUV (range2.9-10.6 SUV), and decreased to 2.7 TNR (range 1.2-4.7 TNR) and 3.8 SUV (range2.6-4.6) after CIRT, respectively. In three out of four patients before CIRTshowed high Cu-62-ATSM uptake that might reflect the trend of them beinghypoxic. A patient showed increase of Cu-62-ATSM uptake after CIRT, but FDGuptake of the same patient didnt increase and almost stable after CIRT. It mightindicate that change of Cu-62-ATSM uptake didnt necessarily correspond tochange of FDG uptake after radiotherapy. Only one patient died after CIRT, andhis Cu-62-ATSM and FDG uptake before therapy were not the highest uptake withinall patients, but both of them were relatively high. Conclusion Cu-62-ATSM andFDG didnt correlate each other before CIRT in pancreas cancer. The change ofCu-62-ATSM uptake didnt necessarily correspond to change of FDG uptake afterCIRT. Cu-62-ATSM and FDG uptake of a patient who died after CIRT were not thehighest uptake, but were relatively high., The 2010 EANM Congress

ObjectivesFDG-PET provides quantitative information regarding the tumor glucosemetabolism which is useful for the clinical diagnosis of tumor diseases. Adiffusion weighted image (DWI) by MRI can be useful in detecting malignanciessimilar to FDG-PET imaging. We evaluated the role of the clinical use ofFDG-PET/CT and DWI by MRI in the differential diagnosis of tumor malignancywith suspected pancreatic cancer, and in the prediction of tumor recurrence forpancreatic cancer. Materials and Methods Pre-surgery patients with eitherproven or suspected primary pancreatic cancer underwent a whole body FDG-PET/CTand DWI by MRI. The malignancy or benignancy of excised specimens waspathologically confirmed in all cases. The tumor glucose metabolism wasevaluated with standardized uptake value (SUV) in FDG-PET/CT (Aquiduo; Toshiba)study. After at least 6hours of fasting, each patient was injected with FDG(217.8-372.5MBq, average: 321.6MBq ) 60 min before imaging. DWI acquired with a3.0-T MRI scanner (Signa HDx 3T; GE Healthcare) with an 8 channel TORSO arraycoil (8US TORSOPA). The apparent diffusion coefficient (ADC) were measured withDWI using a spin echo echo-planar sequence, TR=10s; TE=80 ms; b value=400, 800,1200s/mm2. We obtained SUV from the FDG injected dose and patientbody weight, and ADC from DWI with three types of b values. ADC was calculatedusing the Advantage work station 4.2; fanctool2, GE Healthcare, and we used theaverage values for ADC value. The value of each factor for differentialdiagnosis of tumor malignancy was determined by analysis of the area under thereceiver operating characteristic (ROC) curve with suspected pancreatic cancer.Similarly, the predictive value of each factor for 1-year tumor recurrence wasdetermined by analysis of the area under the ROC curve with proven pancreaticcancer. Results On ROC curve analysis for differential diagnosis of tumormalignancy, the areas under the curve of SUV and ADC were 0.855 and 0.830,respectively. On ROC curve analysis for tumor recurrence, the areas under thecurve of SUV and ADC were 0.843 and 0.600, respectively. The 1-year recurrencefree survival rate above the cutoff (SUV>4.3) was markedly different fromthe rate below the cutoff (SUV≤4.3) (100% vs. 67%, p, The 2010 EANM Congress

[Purpose]Detectingthe distribution of positron emitter generated by nuclear fragmentationreaction in carbon ion beam therapy (auto-activation) applied at Heavy IonMedical Accelerator in Chiba (HIMAC) by means of positron emission tomography(PET) is novel method for therapy quality assurance especially assessingirradiated area. In clinical auto-activation PET settings, we have experienceda significant difference of image quality between LSO-based PET system andBGO-based PET system. Therefore, we planned and performed some phantomexperiments to compare PET scanner performance to image infinitesimalradioactivity. [Methods]Four different PET scanners were used; EXACT HR+,Biograph 16 HiRez (CTI-Siemens), SET-3000 GX/T (Shimadzu corp.) and jPET D4which provides four-layer-depth-of-interaction (DOI) measurement. The crystaldetector materials of each PET scanner were as follows: BGO, LSO, GSO and GSOwith DOI, respectively. A phantom was filled with 18F solution, and scannedevery 6hr until its radioactivity was decayed to the level of the infinitesimalradioactivity generated in clinical auto-activation PET settings. After CT scanor transmission scan for attenuation correction, emission scan was acquired for40min in 3D mode. The emission images were reconstructed by either FBP or OSEM.Reconstructed images were evaluated by visually.[Result]Image quality of thephantom became worse according to the decay of 18F. In particular, imagequality degraded severely when scanned with LSO-based PET system compared tothe others. GSO-based PET system improved the image of infinitesimal radioactivitybetter compared to that of BGO-PET system, because sensitivity of GSO-based PETsystem was 2-fold-higher than BGO-based PET system. Additionally, jPET D4 whichwas one of GSO-based PET system performed best in image quality for 18F phantomstudy due to high sensitivity derived from DOI measurement. The randomcoincidence events of LSO-based PET system were 1M counts when itsradioactivity was almost equally to clinical auto-activation settings, whilethe true coincidence was 0.2M counts. The true/random ratio was 24.3%, bycontrast, that of other PET systems was 99.9%. The reason why serious imagedegradation occurred when scanned with LSO-based PET system might be due topresence of 176Lu in LSO crystals[Conclusion]According to analysis of coincidenceevents, LSO-based PET system was not suitable for detecting infinitesimalradioactivity due to intrinsic radioactivity of 176Lu. An evaluation of imagequality suggested that high sensitive PET system, like jPET D4, was necessaryto detect infinitesimal radioactivity. To image the auto-activation using PETscanner, we must take characteristics of crystals and sensitivity of PET systeminto consideration., EANM Annual Congress 2010

Objectives FDG-PET provides quantitative information about tumor glucose utilization witch is useful for clinical diagnosis of tumor diseases. Standardized Uptake Value (SUV) is most commonly used for evaluation of tumor glucose utilization. But, SUV is affected by many factors that cannot be controlled or even taken into account. In that respect, brain reference index (BRI: ROI of tumor / ROI of cerebellum) is one of the novel quantitative approaches to eliminating the variety of factors that affect SUV. Meanwhile, a MRI pulse sequence could reveal the information about tissue cellularity. This information is useful to evaluate tumor nature. It suggests that it can be useful in the evaluation of malignancy in the lesions. We compared the role of glucose metabolism and cellularity for detection of pancreatic tumor malignancy. Materials and Methods PET/CT: Toshiba Aquiduo, LSO crystals, 3D acquisition mode: 3min, OS-EM Iteration: 4, Subset: 14, Gaussian post filter: 8.0mm 16 Multidetector-row CT, 120kV, Automatic exposure control (160 effective mAs), Helical pitch: 15mm/rot. MRI: GE healthcare Signa HDx 3T Pre-surgery patients with primary pancreatic tumor underwent a whole body FDG-PET/CT and 3Tesla MRI. The malignancy or benignancy of excised specimens was pathologically confirmed in all cases. Tumor glucose utilization was evaluated with SUV and BRI in FDG-PET/CT study, and tumor cellularity was determined with MRI factors, apparent diffusion coefficient (ADC), T2 value and tumor to non-tumor ratio of proton density (TNRPD) in MRI study. ADC were measured with a diffusion weighted image (DWI) using a spin-echo echo-planar sequence (TR=10s; TE=80ms; b factor=0, 400, 800,1200s/mm2). T2 value and proton density were measured with a spin-echo sequence (TR=3s; TE=40, 60, 80, 100ms). We calculated TNRPD from proton density values of tumor and normal pancreas. We compared these results with pathological findings. Results FDG uptake tended to be higher in malignant tumor than benign tumor. BRI seemed to distinguish malignant lesions from benign lesions more clearly than SUV alone. ADC was lower in malignant tumor than benign tumor. Malignant tumors showed higher TNRPD than benign tumors. Conclusions The tumor that shows high SUV, high BRI, low ADC, high TNRPD, high T2WI and high DWI indicate a high probability of pancreatic tumor malignancy. FDG-PET/CT in combination with MRI was superior to each modality alone for evaluating tumor malignant nature., The 2009 EANM Congress

Society of Nuclear Medicine 56ｔｈ annual meeting

Society of Nuclear Medicine 55ｔｈ Annual Meeting

Society of nuclear medicine 54rd Annual Meetng

Society of Nuclear Medicine 54ｔｈ Annual Meeting

Society of Nuclear Medicine 53nd Annual Meeting