Experimental measurements of gamma-photon production and estimation of electron/positron production on the PETAL laser facility

This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser(PETAL)laser.The experiments were performed during the commissioning of the laser.The laser had an energy of about 400 J,an intensity of 8×10^(18)W cm^(−2),and a pulse duration of 660 fs(FWHM).It was shot at a 2 mm-thick solid tungsten target.The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target.This paper reports measurements of electrons,protons and photons.Hot electrons up to35 MeV with a few-MeV temperature were recorded by a spectrometer,called SESAME(SpectreÉlectronS Angulaire MoyenneÉnergie).K-and L-shells were clearly detected by a photon spectrometer called SPECTIX(Spectromètre PetalàCristal en TransmIssion pour le rayonnnement X).High-energy photons were diagnosed by CRACC-X(Cassette de RAdiographie Centre Chambre-rayonnement X),a bremsstrahlung cannon.Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape.Different shapes can exhibit similar reproductions of the experimental data.To eliminate dependence on the shape hypothesis and to facilitate analysis of the data,simulations of the interaction were performed.To model the mechanisms involved,a simulation chain including hydrodynamic,particle-in-cell,and Monte Carlo simulations was used.The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse,the acceleration of electrons inside the plasma,the generation of MeV-range photons from these electrons,and the response of the detector impacted by the energetic photon beam.All this work enabled reproduction of the experimental data.The high-energy photons produced have a large emission angle and an exponential distribution shape.In addition to the analysis of the photon spectra,positron production was also investigated.Indeed,if high-energy photons are generated inside the solid target,some positron/electron pairs may be produced by the Bethe–Heitler process.Therefore,the positron production achievable within the PETAL laser facility was quantified.To conclude the study,the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.

On-chip ultrafast stackable dielectric laser positron accelerator

We present a first on-chip positron accelerator based on dielectric laser acceleration.This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus,enhancing its feasibility for diverse applications.By utilizing a stacked acceleration structure and far-infrared laser technology,we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods.Additionally,we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process,compared with the traditional methods,the positron beam is compressed to a greater extent.We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam.

Guiding function of positron emission tomographycomputed tomography examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma

AIM:To explore the role of positron emission tomographycomputed tomography(PET-CT)examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma(OAML).METHODS:The general clinical data,postoperative PET-CT results,treatment regimens,and the prognosis of 21 histopathologically confirmed OAML patients between October 2017 and September 2021 were collected.Among the 21 patients,five patients underwent surgical treatment alone,13 patients underwent surgical treatment combined with radiotherapy,and three patients underwent surgical treatment combined with chemotherapy.RESULTS:The follow-up period ranged from 8 to 79mo,with four cases of recurrence and no deaths.Through PETCT examination,two patients exhibited both local ocular metabolic elevation and systemic metastasis,and one of these patients had cervical lymph node metastasis,while the other had submandibular and parotid gland metastasis.Nine patients showed only local ocular metabolic elevation,while 10 patients had no abnormal metabolic activity locally.CONCLUSION:PET-CT examination plays a crucial role in detecting residual lesions and recurrence following tumor resection,aiding in precise disease staging,and facilitating the development of personalized treatment plans,ultimately improving patient prognosis.

Application of ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography imaging in recurrent anastomotic tumors after surgery in digestive tract tumors

BACKGROUND This study was to investigate the application value of whole-body dynamic ^(18)F-fluorodeoxyglucose(FDG)positron emission tomography/computed tomogra-phy(PET/CT)imaging in recurrent anastomotic tumors of digestive tract after gastric and esophageal cancer surgery.Postoperative patients with gastric and esophageal cancer have a high risk of tumor recurrence,and traditional imaging methods have certain limitations in early detection of recurrent tumors.Whole-body dynamic ^(18)F-FDG PET/CT imaging,due to its high sensitivity and specifi-city,can provide comprehensive information on tumor metabolic activity,which is expected to improve the early diagnosis rate of postoperative recurrent tumors,and provide an important reference for clinical treatment decision-making.METHODS A retrospective analysis was performed on 53 patients with upper digestive tract tumors after operation and systemic dynamic ^(18)F-FDG PET/CT imaging indi-cating abnormal FDG uptake by anastomosis,including 29 cases of gastric cancer and 24 cases of esophageal cancer.According to the follow-up results of gas-troscopy and other imaging examinations before and after PET/CT examination,the patients were divided into an anastomotic recurrence group and anastomotic inflammation group.Patlak multi-parameter analysis software was used to obtain the metabolic rate(MRFDG),volume of distribution maximum(DVmax)of anastomotic lesions,and MRmean and DVmean of normal liver tissue.The lesion/background ratio(LBR)was calculated by dividing the MRFDG and DVmax of the anastomotic lesion by the MRmean and DVmean of the normal liver tissue,respectively,to obtain LBR-MRFDG and LBR-DVmax.An independent sample t test was used for statistical analysis,and a receiver operating characteristic curve was used to analyze the differential diagnostic efficacy of each parameter for anastomotic recurrence and inflammation.RESULTS The dynamic ^(18)F-FDG PET/CT imaging parameters MRFDG,DVmax,LBR-MRFDG,and LBR-DVmax of postoperative anastomotic lesions in gastric cancer and esophageal cancer showed statistically significant differences between the recurrence group and the inflammatory group(P<0.05).The parameter LBR-MRFDG showed good diagnostic efficacy in differentiating anastomotic inflammation from recurrent lesions.In the gastric cancer group,the area under the curve(AUC)value was 0.935(0.778,0.993)when the threshold was 1.83,and in the esophageal cancer group,the AUC value was 1.When 86 is the threshold,the AUC value is 0.927(0.743,0.993).CONCLUSION Whole-body dynamic ^(18)F-FDG PET/CT imaging can accurately differentiate the diagnosis of postoperative anastomotic recurrence and inflammation of gastric cancer and esophageal cancer and has the potential to be an effective monitoring method for patients with upper digestive tract tumors after surgical treatment.

Rim^(18)F-fluorodeoxyglucose uptake of hepatic cavernous hemangioma on positron emission tomography/computed tomography:A case report

BACKGROUND Peripheral FDG accumulation in a hepatic hemangioma presenting in a patient with prolonged fever is rare.Therefore,clinicians should pay close attention to patients with hepatic mass.CASE SUMMARY A 54-year-old woman with a 4-wk history of daily fevers was admitted to our hospital.A whole body^(18)-Fluordesoxyglucose(PET-FDG)positron emission tomography/computed tomography(PET/CT)was performed to elucidate the source of the fever.However,whole body^(18)-FDG PET/CT raised the suspicion of a malignant lesion because of peripheral FDG accumulation(SUVmax 3.5 g/mL)higher than that of the normal liver parenchyma(SUVmax 1.6 g/mL)surrounding a hypoactive area,and no other abnormalities were showed.Subsequently,the patient underwent liver mass resection.Histopathology showed a hepatic cavernous hemangioma with fatty infiltration around the lesion.The fever disappeared four days after surgery and the patient did not present any complications during follow-up.CONCLUSION Fatty infiltration in the peripheral parts of hepatic cavernous hemangioma may lead to subacute inflammation which further activate the Kupffer cells.This may cause prolonged fever and peripheral rim FDG accumulation on PET/CT.

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Utility of Preoperative Positron Emission Tomography (PET) in Localizing Perforator Vessels of Anterolateral Thigh Free Flap

Objectives: The anterolateral thigh (ALT) flap is often considered the workhorse in soft tissue reconstruction of head and neck defects secondary to trauma, infection, or tumor resection. Despite its many advantages, ALT flaps have been criticized due to variability in vasculature, which may result in inadequate or non-existent perforators. This retrospective study aims to investigate the utility and validity of positron emission tomography (PET) scan to identify the location and characteristics of perforators to the ALT flap. Methods: We performed a 10-year retrospective review of ALT flaps at our institution to identify patients with preoperative PET scans available for analysis. Three reviewers (attending physician, fellow, and resident) were asked to identify the number, location, and characteristics (myocutaneous versus septocutaneous) of ALT perforators on imaging, and reviewer agreement was assessed. Results were then compared to available operative data. Results: One hundred twenty-one patients were identified who underwent ALT free flap surgery. Thirty-eight preoperative PET scans were identified for review. At least one perforator was identified in 92.1% of scans. Agreement percentages regarding the number of perforators ranged from 53% - 61% whereas agreement regarding the location of a single perforator ranged from 79% - 90%. However, reviewers did not agree regarding the type of perforator, with agreement ranging from 34% - 53%. Poor agreement was observed when compared to intraoperative data, with the number of perforators ranging from 26% - 34% and the type of perforator 11% - 24%. These findings are likely due to insufficient data available in operative reports. Conclusion: Although initial studies suggest that PET scan shows promising evidence to support the capacity to preoperatively identify ALT perforators, future prospective studies are warranted to fully validate these findings.

Mathematical Wave Functions and 3D Finite Element Modelling of the Electron and Positron

The wave/particle duality of particles in Physics is well known. Particles have properties that uniquely characterize them from one another, such as mass, charge and spin. Charged particles have associated Electric and Magnetic fields. Also, every moving particle has a De Broglie wavelength determined by its mass and velocity. This paper shows that all of these properties of a particle can be derived from a single wave function equation for that particle. Wave functions for the Electron and the Positron are presented and principles are provided that can be used to calculate the wave functions of all the fundamental particles in Physics. Fundamental particles such as electrons and positrons are considered to be point particles in the Standard Model of Physics and are not considered to have a structure. This paper demonstrates that they do indeed have structure and that this structure extends into the space around the particle’s center (in fact, they have infinite extent), but with rapidly diminishing energy density with the distance from that center. The particles are formed from Electromagnetic standing waves, which are stable solutions to the Schrödinger and Classical wave equations. This stable structure therefore accounts for both the wave and particle nature of these particles. In fact, all of their properties such as mass, spin and electric charge, can be accounted for from this structure. These particle properties appear to originate from a single point at the center of the wave function structure, in the same sort of way that the Shell theorem of gravity causes the gravity of a body to appear to all originate from a central point. This paper represents the first two fully characterized fundamental particles, with a complete description of their structure and properties, built up from the underlying Electromagnetic waves that comprise these and all fundamental particles.

Polyarteritis nodosa presenting as leg pain with resolution of positron emission tomography-images:A case report

BACKGROUND Although fluorodeoxyglucose-positron emission tomography/computed tomography(FDG-PET/CT)is widely used for diagnosis and follow-up of large sized vessel vasculitis,it is still not widely used for small to medium sized vessel vasculitis.CASE SUMMARY This is the case of a 68-year-old male who presented at the emergency department complaining of fever,myalgia,and bilateral leg pain of over two weeks duration,with elevated levels of C-reactive protein.He was subsequently admitted and despite the absence of clinically significant findings,the patient continued to exhibit recurrent fever.A fever of unknown origin workup,which included imaging studies using FDG-PET/CT,revealed vasculitis involving small to medium-sized vessels of both lower extremities,demonstrated by linear hypermetabolism throughout the leg muscles.The patient was treated with methylprednisolone and methotrexate after diagnosis leading to the gradual resolution of the patient’s symptoms.Three weeks later,a follow-up FDGPET/CT was performed.Previously hypermetabolic vessels were markedly improved.CONCLUSION Our case report demonstrated that FDG-PET/CT has tremendous potential to detect medium-sized vessel inflammation;it can also play a crucial role in prognosticating outcomes and monitoring therapeutic efficacy.

Enhancement of electron–positron pairs in combined potential wells with linear chirp frequency

Effect of linear chirp frequency on the process of electron–positron pairs production from vacuum is investigated by the computational quantum field theory.With appropriate chirp parameters,the number of electrons created under combined potential wells can be increased by two or three times.In the low frequency region,frequency modulation excites interference effect and multiphoton processes,which promotes the generation of electron–positron pairs.In the high frequency region,high frequency suppression inhibits the generation of electron–positron pairs.In addition,for a single potential well,the number of created electron–positron pairs can be enhanced by several orders of magnitude in the low frequency region.

Evaluation of response to gemcitabine plus cisplatin-based chemotherapy using positron emission computed tomography for metastatic bladder cancer

BACKGROUND The purpose of the present study was to examine retrospectively the contribution of 18Fluorodeoxyglucose positron emission tomography computed tomography(18FDG-PET/CT)to the evaluation of response to first-line gemcitabine plus cispla-tin-based chemotherapy in patients with metastatic bladder cancer.AIM To evaluate the response to Gemcitabine plus Cisplatin-based chemotherapy using 18FDG-PET/CT imaging in patients with metastatic bladder cancer.METHODS Between July 2007 and April 2019,79 patients underwent 18FDG-PET/CT imaging with the diagnosis of Metastatic Bladder Carcinoma(M-BCa).A total of 42 pa-tients(38 male,4 female)were included in the study,and all had been admi-nistered Gemcitabine plus Cisplatin-based chemotherapy.After completion of the therapy,the patients underwent a repeat 18FDG-PET/CT scan and the results were compared with the PET/CT findings before chemotherapy according to European Organisation for the Research and treatment of cancer criteria.Mean age was 66.1 years and standard deviation was 10.7 years(range:41–84 years).RESULTS Of the patients,seven(16.6%)were in complete remission,17(40.5%)were in partial remission,six(14.3%)had a stable disease,and 12(28.6%)had a pro-gressive disease.The overall response rate was 57.1 percent.CONCLUSION 18FDG-PET/CT can be considered as a successful imaging tool in evaluating response to first-line chemotherapy for metastatic bladder cancer.Anatomical and functional data obtained from PET/CT scans may be useful in the planning of secondline and thirdline chemotherapy.

Appearance of aseptic vascular grafts after endovascular aortic repair on[(18)F]fluorodeoxyglucose positron emission tomography/computed tomography

BACKGROUND Diagnosis of prosthetic vascular graft infection with[(18)F]fluorodeoxyglucose positron emission tomography/computed tomography(18F-FDG PET/CT)allows for early detection of functional changes associated with infection,based on increased glucose utilization by activated macrophages and granulocytes.Aseptic vascular grafts,like all foreign bodies,can stimulate an inflammatory response,which can present as increased activity on 18F-FDG PET/CT.Consequently,distinguishing aseptic inflammation from graft infection,though important,can be difficult.In the case of endovascular aneurysm repair(EVAR),a minimally invasive procedure involving the transfemoral insertion of an endoprosthetic stent graft,the normal postoperative appearance of these grafts on 18F-FDG PET/CT can vary over time,potentially confounding study interpretation.AIM To investigate the visual,semiquantitative,and temporal characteristics of aseptic vascular grafts in patients status post EVAR.METHODS In this observational retrospective cohort study,patients with history of EVAR who underwent 18F-FDG PET/CT for indications other than infection were identified retrospectively.All patients were asymptomatic for graft infection-no abdominal pain,fever of unknown origin,sepsis,or leukocytosis-at the time of imaging and for≥2 mo after each PET/CT.Imaging studies such as CT for each patient were also reviewed,and any patients with suspected or confirmed vascular graft infection were excluded.One hundred two scans performed on 43 patients(34 males;9 females;age=77±8 years at the time of the final PET/CT)were retrospectively reviewed.All 43 patients had an abdominal aortic(AA)vascular graft,40 patients had a right iliac(RI)limb graft,and 41 patients had a left iliac(LI)limb graft.Twentytwo patients had 1 PET/CT and 21 patients had from 2 to 9 PET/CTs.Grafts were imaged between 2 mo to 168 mo(about 14 years)post placement.Eight grafts were imaged within 6 mo of placement,including three that were imaged within three months of placement.The mean interval between graft placement and PET/CT for all 102 scans was 51±39 mo.PET/CT data was reconstructed with region-of-interest analysis of proximal,mid and distal portions of the grafts and background ascending aorta.Maximum standardized uptake value(SUVmax)was recorded for each region.SUVmax-to-background uptake ratios(URs)were calculated.Visual assessment was performed using a 2-pattern grading scale:Diffuse(homogeneous uptake less than liver uptake)and focal(one or more areas of focal uptake in any part of the graft).Statistical analysis was performed.RESULTS In total,there were 306 AA grafts,285 LI grafts,282 RI grafts,and 306 ascending aorta background SUVmax measurements.For all 102 scans,mean SUVmax values for AA grafts were 2.8-3.0 along proximal,mid,and distal segments.Mean SUVmax values for LI grafts and RI grafts were 2.7-2.8.Mean SUVmax values for background were 2.5±0.5.Mean URs were 1.1-1.2.Visual analysis of the scans reflected results of quantitative analysis.On visual inspection,98%revealed diffuse,homogeneous 18F-FDG uptake less than liver.Graft URs and visual pattern categories were significantly associated for AA graft URs(F-ratio=21.5,P<0.001),LI graft URs(F-ratio=20.4,P<0.001),and RI graft URs(F-ratio=30.4,P<0.001).Thus,visual patterns of 18F-FDG uptake corresponded statistically significantly to semiquantitative URs.The age of grafts showing focal patterns was greater than grafts showing diffuse patterns,87±89 vs 50±37 mo,respectively(P=0.02).URs were significantly associated with graft age for AA grafts(r=0.19,P=0.001).URs were also significantly associated with graft age for LI grafts(r=0.25,P<0.0001),and RI grafts(r=0.31,P<0.001).Quartiles of similar numbers of graft(n=25-27)grouped by graft age indicated that URs were significantly higher for 4th quartile vs 2nd quartile URs(F-ratio=19.5,P<0.001).When evaluating URs,graft SUVmax values within 10%-20%of the ascending aorta SUVmax is evident in aseptic grafts,except for grafts in the oldest quartiles.In this study,grafts in the oldest quartiles(>7 years post EVAR)showed SUVmax up to 30%higher than the ascending aorta SUVmax.CONCLUSION Characteristics of an aseptic vascular stent graft in the aorta and iliac vessels on 18F-FDG PET/CT include graft SUVmax values within 10%-20%of the ascending aorta background SUVmax.The SUVmax of older aseptic grafts can be as much as 30%above background.The visual uptake pattern of diffuse,homogeneous uptake less than liver was seen in 98%of aseptic vascular grafts,making this pattern particularly reassuring for clinicians.

肝泡型包虫病的诊治进展

肝包虫病为慢性寄生虫病,由多房棘球蚴的幼虫引发,此病具有相当高的致残率和死亡风险,又被称作“虫癌”。临床上将肝包虫病分为肝泡型包虫病和肝囊型包虫病,肝包虫病在世界各地广泛流行,我国主要在西部农牧区居民群体中发生,对该地区居民的生存质量构成了巨大的威胁。目前临床上治疗肝包虫病以手术治疗方式为主,伴随着外科诊治技术的迅速发展和对肝包虫病研究不断深入,其诊治方案也不断完善。本文将主要综述肝泡型包虫病的诊断和治疗进展,旨在为临床医务人员提供参考,以尽早发现和治疗,降低疾病对患者产生的不良影响,改善患者预后。

Impact of random and scattered coincidences from outside of field of view on positron emission tomography/computed tomography imaging with different reconstruction protocols

Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outside the field of view(FOV)on PET image quality for different reconstruction protocols.Imaging was performed on the Discovery 690 PET/CT scanner,using experimental configurations including the NEMA phantom(a body phantom,with six spheres of different sizes)with a signal background ratio of 4:1.The NEMA phantom(phantom I)was scanned separately in a one-bed position.To simulate the effect of random and scatter coincidences from outside the FOV,six cylindrical phantoms with various diameters were added to the NEMA phantom(phantom II).The 18 emission datasets with mean intervals of 15 min were acquired(3 min/scan).The emission data were reconstructed using different techniques.The image quality parameters were evaluated by both phantoms.Variations in the signal-to-noise ratio(SNR)in a 28-mm(10-mm)sphere of phantom II were 37.9%(86.5%)for ordered-subset expectation maximization(OSEM-only),36.8%(81.5%)for point spread function(PSF),32.7%(80.7%)for time of flight(TOF),and 31.5%(77.8%)for OSEM+PSF+TOF,respectively,indicating that OSEM+PSF+TOF reconstruction had the lowest noise levels and lowest coefficient of variation(COV)values.Random and scatter coincidences from outside the FOV induced lower SNR,lower contrast,and higher COV values,indicating image deterioration and significantly impacting smaller sphere sizes.Amongst reconstruction protocols,OSEM+PSF+TOF and OSEM+PSF showed higher contrast values for sphere sizes of 22,28,and 37 mm and higher contrast recovery coefficient values for smaller sphere sizes of 10 and 13 mm.

生长抑素受体显像术前定位诊断导致肿瘤诱发低磷骨软化症的原发肿瘤病灶

肿瘤诱发低磷骨软化症(tumor induced osteomalacia, TIO)为间叶源性肿瘤所致低磷骨软化症,多表现为进行性骨痛、骨质疏松、行走困难及活动受限甚至多发骨折,严重影响患者生活质量。手术切除原发灶为治疗TIO的有效方法,但间叶源性肿瘤往往位置隐匿、定位困难。本研究报道5例以生长抑素受体显像术前定位诱发TIO的磷酸盐尿性间叶肿瘤(phosphaturic mesenchymal tumor, PMT)原发病灶的结果。

脊椎侵袭性血管瘤^(18)F-FDG PET/CT表现

目的观察脊椎侵袭性血管瘤^(18)F-FDG PET/CT表现。方法回顾性收集24例脊椎侵袭性血管瘤患者,病变位于颈椎6例、胸椎14例、腰椎4例;观察其^(18)F-FDG PET/CT特点,比较具有不同CT表现病灶的最大标准摄取值(SUV_(max))。结果24例中,5例(5/24,20.83%)病变局限于椎体、19例(19/24,79.17%)病变累及椎体及附件;其中10例(10/24,41.67%)病变椎体见溶骨性破坏及内部残留骨质,6例(6/24,25.00%)伴单纯溶骨性破坏,4例(4/24,16.67%)伴骨小梁增粗、稀疏,4例(4/24,16.67%)骨质未见明显异常。相比邻近非病变椎体,12例(12/24,50.00%)病灶放射性摄取增高、9例(9/24,37.50%)接近、3例(3/24,12.50%)减低;14例(14/24,58.33%)放射性分布均匀、10例(10/24,41.67%)不均匀。24例血管瘤的SUV_(max)[2.50(1.53,4.13)]与肝脏SUV_(max)(2.79±0.53)差异无统计学意义(Z=0.261,P=0.794);其中,伴骨皮质破坏病灶的SUV_(max)高于无破坏病灶(P<0.05),伴骨折病灶的SUV_(max)高于无骨折病灶(P<0.05)。结论脊椎侵袭性血管瘤CT表现多样,其^(18)F-FDG代谢接近肝脏,合并骨皮质破坏及骨折病灶的代谢较高。

^(18)F-FDG PET/CT诊断肾细胞癌伴下腔静脉癌栓侵犯下腔静脉壁

目的 观察^(18)F-FDG PET/CT诊断肾细胞癌(RCC)伴下腔静脉(IVC)癌栓侵犯IVC壁的价值。方法 回顾性分析71例接受手术治疗的RCC伴IVC癌栓患者,根据癌栓是否侵犯IVC壁分为侵犯组(n=40)及无侵犯组(n=31);比较组间一般资料和PET/CT特征,分析各指标诊断癌栓侵犯IVC壁的效能。结果 组间原发灶最大标准摄取值(SUV_(max))、癌栓比、癌栓最大横径、长径,以及病理类型差异均有统计学意义(P均<0.05)。癌栓比和癌栓最大横径为RCC伴IVC癌栓侵犯IVC壁的影响因素(P均<0.05)。以1.33为最佳截断值,根据癌栓比诊断RCC伴IVC癌栓侵犯IVC壁的敏感度为47.50%,特异度为87.10%,AUC为0.70;以3.45 cm为最佳截断值,根据癌栓最大横径诊断的敏感度为65.00%,特异度为87.10%,AUC为0.81;二者联合诊断敏感度为90.00%,特异度为77.40%,AUC为0.86。结论 以^(18)F-FDG PET/CT所获癌栓比及癌栓最大横径可用于术前诊断RCC伴IVC癌栓侵犯IVC壁。

1例初始表现为急性弥散性血管内凝血的胃低分化腺癌伴多发转移:^(18)F-FDG PET/CT显像所见

患者女,20岁,无明显诱因阵发性下腹部疼痛伴牙龈出血、皮肤散在瘀斑及肛门坠胀感9天;既往体健。查体:贫血貌,全身皮肤散在片状瘀斑,四肢皮肤干燥;腹部柔软,无压痛及反跳痛。实验室检查:红细胞2.49×10^(12)/L,血小板36×10^(9)/L,血红蛋白70 g/L,血浆鱼精蛋白副凝固实验(+),D-二聚体>20 mg/L,纤维蛋白原降解产物>150.00 mg/L,糖类抗原12573.40 U/ml。

骨髓坏死^(18)F-FDG PET/CT与MRI对照分析

目的探索骨髓坏死氟-18-脱氧葡萄糖(^(18)F-fluorodeoxyglucose,^(18)F-FDG)正电子发射断层显像/计算机断层显像(positron emission tomography/computed tomography,PET/CT)表现,提高对该病的认识。方法回顾性分析9例磁共振成像(magnetic resonance imaging,MRI)诊断为骨髓坏死患者的PET/CT及临床资料,对照MRI影像,总结病变分布,选择最大病变,分析^(18)F-FDG代谢特点及CT征象。结果患者男6例,女3例,中位年龄28.0岁,均患淋巴瘤。MRI检查髋部6例、胸腰椎2例、膝部1例。6例髂骨病变,内部均为T1加权像(T1-weighted image,T1WI)高信号,T2脂肪抑制像(T2-fat suppressed image,T2FSI)低信号,伴T1WI边缘环状低信号,其中5例内部代谢减低,边缘代谢增高伴骨质硬化;1例密度及代谢未见异常,MRI显示病变狭长。2例脊柱病变T1WI呈等、低信号,T2FSI高信号,其中1例为等代谢,密度稍高;1例代谢减低,密度未见异常。1例股骨病变T1WI高信号,T2FSI低信号,代谢及密度增高。8例PET/CT发现MRI检查范围之外更多病变。8例更早期的PET/CT发现部分病变呈低代谢、等密度。结论^(18)F-FDG代谢减低,后期可伴有边缘线状代谢及密度增高,是骨髓坏死的常见PET/CT影像特点。PET/CT有助于检出骨髓坏死,发现多骨病变。

新型前列腺癌显像剂^(68)Ga-PSMA-4PY的初步临床研究

目的:评估一种体内快速清除的前列腺癌显像剂^(68)Ga-PSMA-4PY在临床应用中的潜力。方法:采用前体药盒化方法标记^(68)Ga-PSMA-4PY,进行质量控制确保其纯度和安全性;通过动态正电子发射体层成像(positron emission tomography,PET)分析^(68)Ga-PSMA-4PY在小鼠血液、肝脏和肾脏中的放射性摄取及清除。并通过临床显像研究比较^(68)Ga-PSMA-4PY与^(68)Ga-PSMA-11在前列腺癌患者体内的分布特性。结果:经前体药盒化标记的^(68)Ga-PSMA-4PY具有良好的标记效率和稳定性。小鼠动态PET结果显示,^(68)Ga-PSMA-4PY在血液中的清除特征与^(68)Ga-PSMA-11相近;^(68)Ga-PSMA-4PY在肾脏中的放射性摄取峰值出现在2 min内,并随后快速排出,而^(68)Ga-PSMA-11在肾脏中呈持续性增加,直至60 min时达到^(68)Ga-PSMA-4PY的11倍。临床研究表明,^(68)Ga-PSMA-4PY可以在前列腺癌中浓集,在肝、肾和脾脏中的放射性滞留明显低于^(68)Ga-PSMA-11,且唾液腺摄取降低了57.5%。结论:^(68)Ga-PSMA-4PY能够快速浓聚到PSMA阳性的肿瘤中,并迅速从正常组织中清除,将有助于减少非特异性摄取引起的不良反应,是一种具有良好前景的前列腺癌显像剂。