Search

We developed a human-scale single-ring OpenPET (SROP) system, which had an open space allowing us access to the subject during measurement. The SROP system consisted of 160 4-layer depth-of-interaction detectors. The open space with the axial width of 430 mm was achieved with the ring axial width of 214 mm and the ring inner diameter of 660 mm. The detectors were axially shifted to each other so that the detector ring was aligned along a plane horizontally tilted by 45° against the axial direction. The system was developed as a mobile scanner to be used not only in clinical positron emission tomography (PET) rooms but also in charged-particle therapy treatment rooms as well as animal experiment rooms. Almost uniform spatial resolution better than 3 mm throughout the entire field of view (FOV) was realized with an iterative image reconstruction method. Peak absolute sensitivity was 3.1%, and there was a region with sensitivity better than 0.8% for a length of more than 700 mm. An in-beam imaging experiment conducted at the heavy ion medical accelerator in Chiba showed that the system was operable even at the highest beam intensity available for heavy-ion therapy. In addition, we conducted entire-body monkey dynamic imaging utilizing the long region inside the gantry by positioning a monkey along the direction having the longest FOV tilted by 45° against the axial direction. We concluded the developed system has a capability to realize versatile PET applications by utilizing its wide-open space and mobility in addition to high spatial resolution with sufficiently good sensitivity. -9mm]Please consider rephrasing the sentence “We concluded the developed system” for clarity.

Makoto Kobayashi, Eiji Yoshida, Takuro Kyuno, Ryoko Kawagishi, Kei Sato, Tsuyoshi Kono, Takehiro Chiba, Hitoshi Yonezawa, Osamu Funato, Akinori Takagane Department of Surgery, Hakodate Goryoukaku Hospital, Hakodate City, Hokkaido, 040-8611, JapanCorrespondence: Makoto KobayashiDepartment of Surgery, Hakodate Goryoukaku Hospital, 38-3 Goryoukaku-cho, Hakodate City, Hokkaido, 040-8611, JapanTel +81-138-51-2295Fax +81-138-56-2696Email koba86gg@gmail.comPurpose: Faster surgery has been associated with better outcomes. In the present study, we aimed to determine whether surgical duration affected overall survival (OS) in patients undergoing esophagectomy. Additionally, we assessed factors that influence surgical duration.Patients and Methods: This single-center retrospective cohort study included 128 patients who underwent Ivor-Lewis esophagectomy by a single surgeon between 2005 and 2019. The Cox proportional hazard model was used to evaluate the association of OS with the following variables: surgical duration, neo-adjuvant chemotherapy, pathological grade of depth of tumor invasion, lymph node (LN) metastasis, body mass index (BMI), and cervical LN dissection. Additionally, factors associated with prolonged surgical duration were examined by logistic regression analysis.Results: Based on the multivariate analysis, surgical duration was not associated with OS [hazard ratio (HR), 1.065; 95% confidence interval (CI), 0.586– 1.937; P = 0.837]. On the other hand, tumor invasion (HR, 2.901; 95% CI, 1.483– 5.674; P = 0.002) and LN metastasis (HR, 2.338 2.403; 95% CI, 1.237– 4.420 1.257– 4.593; P = 0.009 0.008) significantly influenced OS. The assessment of variables affecting surgical duration showed that BMI had a significant effect on surgical duration (odds ratio, 2.790; 95% CI, 1.254– 6.204, P = 0.012).Conclusion: According to the analysis of patients who underwent the same surgical approach by a single surgeon, surgical duration of esophagectomy for esophageal cancer was significantly influenced by BMI; however, surgical duration had no impact on patient survival.Keywords: esophagectomy, Ivor-Lewis approach, depth of tumor invasion, lymph node metastasis, body mass index, overall survival

Using time-of-flight (TOF) information in image reconstruction improves image signal-to-noise ratio and quantitative accuracy in positron emission tomography (PET). A new TOF-PET detector module with a 3.2 mm pitch lutetium fine silicate (LFS) scintillator array one-to-one coupled to a 16×16 (256-ch) silicon photomultiplier (SiPM) array was made commercially available (C13500 series, Hamamatsu Photonics K.K.). In this study, as a candidate detector module for the next generation brain-dedicated PET, we changed the scintillator length of 20 mm to 10 mm according to our helmet-type PET geometry and investigated the basic performance of the PET detector module, including its energy resolution, sensitivity, coincidence response function (CRF) and coincidence timing resolution (CTR). All performance values were compared with those of the 4.2 mm pitch 144-ch detector module which was selected for our current helmet-type PET prototype. The energy resolution was 12% at 511 keV. The sensitivity was about 10% lower compared with those of the 4.2 mm pitch module. The average full width at half maximum (FWHM) of the CRFs was 1.9 mm. The CTRs had values of 235–241 ps with various energy windows after applying timing calibration. The CTR was not significantly changed (

To improve positron emission tomography (PET) image quality, depth-of-interaction (DOI) information and time-of-flight (TOF) information are key technologies. In this work, we developed the DOI-TOF detector based on our original single-ended readout scheme with the continuous layered gadolinium fine aluminum garnet (GFAG) array. The size of each GFAG crystal is $1.45\times 1.45\times 20$ mm3. The multipixel photon counter (MPPC) used as a photo sensor has a surface area of $3.0\times 3.0$ mm2. One pair of crystals coupled with a partial optical window is arranged across two MPPCs. Boundaries without the partial optical window are covered with optical reflectors. Each pair is coupled with paired MPPCs of different patterns. Crystal identification is obtained from paired MPPCs of different patterns and output rates. By limiting the spread of scintillation light, the proposed DOI detector based on the local centroid calculation was expected to improve crystal response, including the edge. For performance comparison, we prepared three discrete layers of the GFAG array with the same total thickness. For the continuous layer, the DOI resolution, the energy resolution and the timing resolution of the pair of detectors are 4.7 mm, 14%, and 402 ps, respectively. Their respective values are 29%, 20%, and 33% better than those with the three discrete layers.

A synthetic route to ecteinascidin 743 has been established via an intramolecular cascade Heck reaction to construct the diazabicyclo[3.3.1]nonane skeleton while controlling the two contiguous stereogenic centers. The strategically formed five-membered ring was oxidatively cleaved to generate a dialdehyde intermediate, from which the B ring of ecteinascidin 743 was constructed.

Background In pancreatic cancer surgery, accurate identification and resection of intrapancreatic residual tumors are quite difficult. We have developed a novel open-typed PET system (called 'OpenPET'), which enables high-resolution PET-guided surgery in real time, and demonstrated that OpenPET-guided surgery with intraperitoneally administered 64Cu-labeled anti-epidermal growth factor receptor antibody cetuximab is useful to detect and resect primary pancreatic cancer. Here, we investigated applicability of OpenPET-guided surgery for unexpected residual intrapancreatic tumors and examined its survival benefit over conventional surgery. Methods A mouse model with large (>1 cm) resectable pancreatic cancer of xPA-1-DC cells expressing red fluorescent protein was used. OpenPET-guided surgery was conducted 24 h after intraperitoneal administration of 64Cu-labeled cetuximab (7.4 MBq/mouse). For comparison, similar surgical procedures were conducted, and conventional tumor resection was attempted using only the naked eye (control). Survival rate after OpenPET-guided surgery was compared to that after control operations. Results Intraoperative OpenPET guidance enabled detection and resection of small residual tumors. Ten residual tumor specimens (3-10 mm in diameter) were intraoperatively isolated with OpenPET guidance (n = 7 mice). All isolated specimens showed tumor RFP signals. No resection of tumor tissue was performed in control group because the tumor could not be clearly detected with the naked eye alone. Mice after OpenPET-guided surgery showed significantly longer survival rates than those in control group. Conclusions OpenPET-guided surgery with 64Cu-labeled-cetuximab enabled intraoperative identification and resection of intrapancreatic small residual tumors. This technology could be useful to prevent tumor residuals during surgery and improve pancreatic cancer survival.

In pancreatic cancer surgery, accurate identification and resection of intrapancreatic residual tumors are quite difficult. We have developed a novel open-typed PET system (called 'OpenPET'), which enables high-resolution PET-guided surgery in real time, and demonstrated that OpenPET-guided surgery with intraperitoneally administered 64Cu-labeled anti-epidermal growth factor receptor antibody cetuximab is useful to detect and resect primary pancreatic cancer. Here, we investigated applicability of OpenPET-guided surgery for unexpected residual intrapancreatic tumors and examined its survival benefit over conventional surgery.

多様な核医学用シンチレータについて、ごく簡単に概説した。

[Objectives] A PET system can be more efficient in terms of size and cost when it is designed as an organ-dedicated or application-specific system. Considering the potential need for brain PET, we proposed the concept of a hemispherical detector arrangement, which enables higher sensitivity with fewer number of detectors than a conventional cylindrical geometry has. A laboratory benchtop prototype has been evolved into a complete brain PET system, which has been commercialized in Japan under the product name of VrainTM. In this work, we characterize the system and carry out its first human imaging tests. [Methods] The VrainTM has 54 detectors. A hemispherical part is formed by 45 detectors and the other 9 detectors are located at the backside of the neck. Each detector is a one-to-one combination of lutetium-based scintillators (crystal element size: 4.1×4.1×10 mm3) and silicon photomultipliers (SiPMs) (active area size: 4×4 mm2). The inner diameter of the bottom detector ring is 279 mm. The crystal thickness is optimized by simulation to reduce the parallax error and to improve the TOF performance. The energy window is also optimized to 450–590 keV to get better image quality. We evaluated the physical performance of the VrainTM according to the NEMA NU 2-2018 standards. Some measurements were added and others were modified to suit the hemispherical detector arrangement. Finally, we carried out the first healthy volunteer imaging. 18F-FDG of 3.7 MBq/kg was intravenously injected to a male subject (42 years old). The PET measurement duration was 10 min starting at 45 min after injection. PET images were reconstructed using the OSEM with 4 iterations and 8 subsets. A Gaussian filter of 4 mm FWHM was applied to PET images. CT images, which were obtained by another PET/CT scanner, were used for attenuation and scatter corrections. [Results] The 2.2 mm rods of a small rod phantom were resolved. The TOF resolution at the peak noise-equivalent count ratio (NECR) (9.8 kBq/mL) was 256 ps and the TOF gain in sensitivity was calculated as 5.2 (20 cm diameter / 3.8 cm localization accuracy). The effective sensitivity was 21.8 kcps/MBq and the effective peak NECR was 129 kcps at 9.8 kBq/mL. The sensitivity was higher at the upper position in the axial direction. For the brain-sized image quality phantom evaluation, the percent contrast of the 10 mm sphere was 48% with the percent background variability of 8.6%. For the human FDG PET imaging, the whole brain was successfully imaged without any artifacts. Gray and white matters were clearly visualized with a high contrast. [Conclusion] The helmet-type brain PET system VrainTM showed 2.2 mm spatial resolution, 256 ps TOF resolution, and excellent image quality. The brain FDG PET images of the healthy volunteer were high contrast and low noise. Further studies are warranted to assess the potential clinical impact of PET imaging with the VrainTM., SNMMI 2022 Annual Meeting

Objective. For PET imaging systems, a smaller detector ring enables less intrinsic spatial resolution loss due to the photon non-collinearity effect as well as better balance between production cost and sensitivity, and a hemispherical detector arrangement is more appropriate for brain imaging than a conventional cylindrical arrangement. Therefore, we have developed a brain-dedicated PET system with a hemispherical detector arrangement, which has been commercialized in Japan under the product name of VRAINTM. In this study, we evaluated imaging performance of VRAIN. Approach. The VRAIN used 54 detectors to form the main hemispherical unit and an additional half-ring behind the neck. Each detector was composed of a 12 × 12 array of lutetium fine silicate crystals (4.1 × 4.1 × 10 mm3) and a 12 × 12 array of silicon photomultipliers (4 × 4 mm2 active area) with the one-to-one coupling. We evaluated the physical performance of VRAIN according to the NEMA NU 2–2018 standards. Some measurements were modified so as to fit the hemispherical geometry. In addition, we performed 18F-FDG imaging in a healthy volunteer. Main results. In the phantom study, the VRAIN showed high resolution for separating 2.2 mm rods, 229 ps TOF resolution and 19% scatter fraction. With the TOF gain for a 20 cm diameter object (an assumed head diameter), the peak noise-equivalent count rate was 144 kcps at 9.8 kBq ml−1 and the sensitivity was 25 kcps MBq−1. Overall, the VRAIN provided excellent image quality in phantom and human studies. In the human FDG images, small brain nuclei and gray matter structures were clearly visualized with high contrast and low noise. Significance. We demonstrated the excellent imaging performance of VRAIN, which supported the advantages of the hemispherical detector arrangement.

To improve positron emission tomography (PET) image quality, depth-of-interaction (DOI) information and timeof-flight (TOF) information are key technologies. In this work, we developed the DOI-TOF detector based on our original singleended readout scheme with the continuous layered gadolinium fine aluminum garnet (GFAG) array. The size of each GFAG crystal is 1.45×1.45×20 mm3. The multi-pixel photon counter (MPPC) used as a photo-sensor has a surface area of 3.0×3.0 mm2. One pair of crystals coupled with a partial optical window is arranged across two MPPCs. Boundaries without the partial optical window are covered with optical reflectors. Each pair is coupled with paired MPPCs of different patterns. Crystal identification is obtained from paired MPPCs of different patterns and output rates. By limiting the spread of scintillation light, the proposed DOI detector based on the local centroid calculation was expected to improve crystal response including the edge. For performance comparison, we prepared three discrete layers of the GFAG array with the same total thickness. For the continuous layer, the DOI resolution, the energy resolution and the timing resolution of the pair of detectors are 4.7 mm, 14% and 402 ps, respectively. Their respective values are 29%, 20% and 33% better than those with the three discrete layers.

PETを用いた小動物イメージングは創薬や病態解明研究に活用されている。一方で、全ての研究者にPETが十分に行き届いているとは言い難い。例えば、特定エリアでの管理が必要な遺伝子操作マウスのPET撮像、粒子線照射直後のラットのPET撮像、マウスやラットの全身薬物動態の観察、微小腫瘍内の不均一薬剤集積の可視化、限られたスペースへの小動物用PET装置の導入、といった様々なアンメットニーズが存在する。このような多様な研究ニーズに応えるべく、サブミリ分解能を有する多目的用途のポータブル小型PET装置を開発した。 独自に開発した22 mm角のcrosshair light-sharing (CLS) 検出器（1.45×1.45×15 mm3のGFAGシンチレータ14×14アレイと3×3 mm2の半導体光センサSiPM 8×8アレイを接合）を使用した。相互作用を起こした深さによって光の分配パターンに差がでるように反射材が組んであり、深さ方向の検出位置（DOI）を5 mm単位で識別できる。128個の検出器を用いて体軸方向視野207 mmの8リング装置を製作し、CLS-PETと名付けた（下図a）。ガントリやデータ収集機器は台車上に配置し、1人で移動できるポータブル仕様とした（重量約100 kg）。撮像場所を選ばないよう、100V電源1つで動作する仕様とした。空間分解能評価として、22Na密封ロッドファントム（1 MBq）の30分撮像を行った。小動物全身撮像の実証として、健常ラットに18F-NaF（37 MBq）を投与し、60分後より60分撮像を行った。ファントムでは0.75 mmロッドが識別でき、サブミリ分解能を達成した（下図b）。ラットNaF PETでは、骨構造が明瞭に描出された全身画像を得た（下図c）。 サブミリ分解能を有する多目的ポータブル装置CLS-PETを開発した。PET室に縛られないポータブル装置のため様々なニーズに対応でき、新しいPET応用研究を開拓できる可能性がある。, 第16回日本分子イメージング学会総会・学術集会参加発表

[Purpose] We developed the world’s first helmet-type time-of-flight (TOF) PET, which had a hemispherical detector arrangement. The developed system is characterized as its high-performance and compactness as well as an unusual seat-type design which enables keeping the subject’s eye view wide. Here, we report the basic performance characteristics and the first FDG imaging results of healthy volunteers. [Methods] The helmet-type PET consisted of 54 detectors. The 45 detectors were arranged to form a hemisphere and the other 9 detectors were placed to form a half-ring behind the neck. The detector was composed of 12×12 lutetium fine silicate (LFS) scintillators (4×4×10 mm3) connected to a 12×12 silicon photomultiplier (SiPM) array with one-to-one coupling. The energy window was 450–590 keV and the coincidence time window was 3.6 ns. Image reconstruction was performed using 3D-OSEM with 4 iterations and 8 subsets. The performance was characterized based on the NEMA NU2 standards. The coincidence timing resolution was measured using a 22Na point source. 18F-FDG PET and MRI were performed for 11 normal control subjects. The PET data were measured for 10 minutes starting at 45 minutes after injection of 285±23 MBq. [Results] The coincidence timing resolution was 235 ps. With the sensitivity gain of 5.7 (= 20-cm-diameter object / 3.5 cm TOF localization), the effective sensitivity was 24 cps/kBq and the effective noise-equivalent count ratio was 120 kcps@9 kBq/mL. The spatial resolution of the FBP image was 2.9 mm at the central position (1 cm offset) of the field-of-view. For the human FDG PET images, the gray matter was clearly visualized with a high contrast to the white matter. Small brain nuclei such as the substantia nigra, the red nucleus, and the superior colliculus were able to be identified. [Conclusion] We have successfully demonstrated first human imaging on the helmet-type PET., 第78回日本放射線技術学会総会学術大会

Methicillin-resistant Staphylococcus aureus (MRSA) is the leading cause of infection in hospitalized patients and can be prevalent in humans and various animal species. In European countries, MRSA isolates belonging to clonal complex 398 have been detected at high rates in pigs. However, the prevalence of MRSA in pigs and farm environments in Japan remains unclear. MRSA isolates were obtained from pigs in slaughterhouses, diseased pigs on farms, imported breeding pigs, and farm dust. We conducted whole-genome sequencing (WGS) and analyzed the molecular epidemiological relationship between these MRSA isolates using core genome multilocus sequence typing (cgMLST). The prevalence rates of MRSA among pigs in slaughterhouses, diseased pigs on farms, imported breeding pigs, and farm dust were 5.2 %, 3.4 %, 28.8 %, and 0.06 %, respectively. ST 398 isolates that classified as ST398/t034 were isolated from pigs from all sources. The results of cgMLST showed that ST398/t034 isolates originating from domestic pigs clustered into the same cluster as the isolates from imported breeding pigs. However, some clusters only included isolates of domestic pig origin. Most MRSA isolates in this study carried resistance genes for aminoglycosides, β-lactams, macrolides, tetracyclines, and zinc. None of the MRSA isolates in this study harbored Panton-Valentine leukocidin toxin genes. Molecular epidemiological analysis suggested a relationship between isolates from slaughter pigs and imported breeding pigs and the presence of MRSA isolates of domestic origin. However, more data are needed for elucidation of the origin of these MRSA variants in the pig industry in Japan.

In this article, we developed the novel single-end readout depth-of-interaction (DOI) detector with quadrisected crystals comparable in size to a single photo sensor. The proposed DOI detector consists of 784 gadolinium aluminum gallium garnet (GAGG) crystals, which are arranged in four layers of $14\times14$ arrays coupled with an $8\times8$ multipixel photon counter (MPPC) array. The size of each GAGG crystal is $1.45\times 1.45\times4.5$ mm3. Also, each MPPC has a surface area of $3.0\times3.0$ mm2. One pair of four-layered crystals coupled with a partial optical window is arranged across two MPPCs. Boundaries without the partial optical window are covered with optical reflectors. Light sharing is done between a pair of four-layered crystals optically coupled at one end. Each pair is coupled with paired silicon photomultipliers of different patterns. Crystal identification from each pair is obtained from the output rate of two MPPCs. From 511-keV uniform irradiation, responses of all crystal elements in the four layers can be separated clearly on a 2-D position histogram after applying the Anger calculation. Also, DOI information can be mapped to each cluster on curved lines. The energy resolution for all crystals is 9.1% after event reduction of intercrystal scatter.

—In this article, we developed the novel single-end readout depth-of-interaction (DOI) detector with quadrisected crystals comparable in size to a single photo sensor. The proposed DOI detector consists of 784 gadolinium aluminum gallium garnet (GAGG) crystals, which are arranged in four layers of 14 × 14 arrays coupled with an 8 × 8 multipixel photon counter (MPPC) array. The size of each GAGG crystal is 1.45 × 1.45 × 4.5 mm3. Also, each MPPC has a surface area of 3.0 × 3.0 mm2. One pair of four-layered crystals coupled with a partial optical window is arranged across two MPPCs. Boundaries without the partial optical window are covered with optical reflectors. Light sharing is done between a pair of four-layered crystals optically coupled at one end. Each pair is coupled with paired silicon photomultipliers of different patterns. Crystal identification from each pair is obtained from the output rate of two MPPCs. From 511-keV uniform irradiation, responses of all crystal elements in the four layers can be separated clearly on a 2-D position histogram after applying the Anger calculation. Also, DOI information can be mapped to each cluster on curved lines. The energy resolution for all crystals is 9.1% after event reduction of intercrystal scatter.