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.

Gamma knife treatment for refractory epilepsy in seizure focus localized by positron emission tomography/CT

A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The loci of 60% of the patients could be positioned using a combined positron emission tomography/CT imaging modality. Hyper- and hypometabolism foci were examined as part of this study. Patients who had abnormal metabolism in positron emission tomography/CT imaging were divided into intermittent-phase group and the seizure-phase group. The intermittent-phase group was further divided into a single-focus group and a multiple-foci group according to the number of seizure foci detected by imaging. Following gamma knife treatment, seizure frequency was significantly lower in the intermittent-phase group and the seizure-phase group. Wieser＇s classification reached Grade I or II in nearly 40% of patients. Seizure frequency was significantly lower following treatment, but Wieser＇s classification score was significantly higher in the seizure-phase group compared with the intermittent-phase group. Seizure frequency was significantly lower following treatment in the single-focus group, but Wieser＇s classification score was significantly higher in the single-focus group as compared with the multiple-foci group.

Diagnostic Efficacy of^(18)F-FDG PET/CT in Detecting Bone Marrow Infiltration in Patients with Newly Diagnosed Diffuse Large B-Cell Lymphoma

Objective Diffuse large B-cell lymphoma(DLBCL)is often associated with bone marrow infiltration,and 2-deoxy-2-(18F)fluorodeoxyglucose positron emission tomography/computed tomography(^(18)F-FDG PET/CT)has potential diagnostic significance for bone marrow infiltration in DLBCL.Methods A total of 102 patients diagnosed with DLBCL between September 2019 and August 2022 were included.Bone marrow biopsy and^(18)F-FDG PET/CT examinations were performed at the time of initial diagnosis.Kappa tests were used to evaluate the agreement of^(18)F-FDG PET/CT with the gold standard,and the imaging features of DLBCL bone marrow infiltration on PET/CT were described.Results The total detection rate of bone marrow infiltration was not significantly different between PET/CT and primary bone marrow biopsy(P=0.302)or between the two bone marrow biopsies(P=0.826).The sensitivity,specificity,and Youden index of PET/CT for the diagnosis of DLBCL bone marrow infiltration were 0.923(95%CI,0.759-0.979),0.934(95%CI,0.855-0.972),and 0.857,respectively.Conclusion^(18)F-FDG PET/CT has a comparable efficiency in the diagnosis of DLBCL bone marrow infiltration.PET/CT-guided bone marrow biopsy can reduce the misdiagnosis of DLBCL bone marrow infiltration.

How does the motor relearning program improve neurological function of brain ischemia monkeys?

The motor relearning program can significantly improve various functional disturbance induced by ischemic cerebrovascular diseases. However, its mechanism of action remains poorly understood. In injured brain tissues, glial fibrillary acidic protein and neurofilament protein changes can reflect the condition of injured neurons and astrocytes, while vascular endothelial growth factor and basic fibroblast growth factor changes can indicate angiogenesis. In the present study, we induced ischemic brain injury in the rhesus macaque by electrocoagulation of the M1 segment of the right middle cerebral artery. The motor relearning program was conducted for 60 days from the third day after model establishment. Immunohistochemistry and single-photon emission CT showed that the numbers of glial fibrillary acidic protein-, neurofilament protein-, vascular endothelial growth factor- and basic fibroblast growth factor-positive cells were significantly increased in the infarcted side compared with the contralateral hemisphere following the motor relearning program. Moreover, cerebral blood flow in the infarcted side was significantly improved. The clinical rating scale for stroke was used to assess neurological function changes in the rhesus macaque following the motor relearning program. Results showed that motor function was improved, and problems with consciousness, self-care ability and balance function were significantly ameliorated. These findings indicate that the motor relearning program significantly promoted neuronal regeneration, repair and angiogenesis in the surroundings of the infarcted hemisphere, and improve neurological function in the rhesus macaque following brain ischemia.

Value of ^(18)F-FDG PET/CT and MRI in diagnosing primary endometrial small cell carcinoma

Primary small cell carcinoma（SCC） is a group of aggressive neoplasms that mainly arise from the lung and digestive tract. Endometrial small cell carcinoma（ESCC） is extremely rare. To our knowledge, less than 90 cases have been reported, and most of these reports were dedicated to describing the clinicopathologic or immunochemical features of ESCC. Herein, we present a new case of ESCC involving a 51-year-old woman and mainly focus on the magnetic resonance imaging（MRI） and positron emission tomography/computed tomography（PET/CT） findings. MRI showed that the uterus was significantly enlarged（11.6 cm × 11.1 cm × 14.4 cm）, and a giant irregular mass（7.5 cm × 8.4 cm × 8.5 cm） was observed in the uterine cavity. The lesion demonstrated an extremely low apparent diffusion coefficient（ADC） value [（0.553±0.088）×10^–3 mm^2/s] and a high FDG uptake value（22.7）. Multiple metastatic lymph nodes（LNs） were identified at different positions, with diameters ranging from 0.3 to 2.8 cm and a maximum standardized uptake value（SUV max） ranging from 6.9 to 19.3.

Dynamic contrast-enhanced MRI versus ^(18)F-FDG PET/CT: Which is better in differentiation between malignant and benign solitary pulmonary nodules?

Objective： To prospectively compare the discriminative capacity of dynamic contrast enhanced-magnetic resonance imaging（DCE-MRI） with that of^18F-fluorodeoxyglucose（^18F-FDG） positron emission tomography/computed tomography（PET/CT） in the differentiation of malignant and benign solitary pulmonary nodules（SPNs）.Methods： Forty-nine patients with SPNs were included in this prospective study. Thirty-two of the patients had malignant SPNs, while the other 17 had benign SPNs. All these patients underwent DCE-MRI and ^18F-FDG PET/CT examinations. The quantitative MRI pharmacokinetic parameters, including the trans-endothelial transfer constant（K^trans）, redistribution rate constant（Kep）, and fractional volume（Ve）, were calculated using the Extended-Tofts Linear two-compartment model. The ^18F-FDG PET/CT parameter, maximum standardized uptake value（SUV（max））, was also measured. Spearman＇s correlations were calculated between the MRI pharmacokinetic parameters and the SUV（max） of each SPN. These parameters were statistically compared between the malignant and benign nodules. Receiver operating characteristic（ROC） analyses were used to compare the diagnostic capability between the DCE-MRI and ^18F-FDG PET/CT indexes.Results： Positive correlations were found between K^trans and SUV（max）, and between K（ep） and SUV（max）（P〈0.05）.There were significant differences between the malignant and benign nodules in terms of the K^trans, K（ep） and SUV（max） values（P〈0.05）. The areas under the ROC curve（AUC） of K^trans） K（ep） and SUV（max） between the malignant and benign nodules were 0.909, 0.838 and 0.759, respectively. The sensitivity and specificity in differentiating malignant from benign SPNs were 90.6% and 82.4% for K^trans; 87.5% and 76.5% for K（ep）; and 75.0% and 70.6%for SUV（max）, respectively. The sensitivity and specificity of K^trans and K（ep） were higher than those of SUV（max）, but there was no significant difference between them（P〉0.05）.Conclusions： DCE-MRI can be used to differentiate between benign and malignant SPNs and has the advantage of being radiation free.

Clinical role of ^(18)F-FDG PET/CT-based simultaneous modulated accelerated radiotherapy treatment planning for locally advanced nasopharyngeal carcinoma

Objective The aim of this study was to compare the long-term local control, overall survival, and late toxicities of positron emission tomography/computed tomography （PET/CT）-guided dose escalation radio- therapy versus conventional radiotherapy in the concurrent chemoradiotherapy treatment of locally ad- vanced nasopharyngeal carcinoma （NPC）. Methods Atotal of 48 patients with stage IIl-IVa NPC were recruited and randomly administered PET/CT- guided dose escalation chemoradiotherapy （group A） or conventional chemoradiotherapy （group B）. The dose-escalation radiotherapy was performed using the simultaneous modulated accelerated radiotherapy technique at prescribed doses of 77 gray （Gy） in 32 fractions （f） to the gross target volume （GTV）： planning target volume （PTV） 1 received 64 Gy/32 f, while PTV2 received 54.4 Gy/32 f. Patients in group B received uniform-dose intensity-modulated radiotherapy, PTV1 received 70 Gy/35 f and PTV2 received 58 Gy/29 f. Concurrent chemotherapy consisted of cisplatin [20 mg/m2 intravenous （IV） on days 1-4] and docetaxel （75 mg/m2 IV on days 1 and 8） administered during treatment weeks 1 and 4. All patients received 2-4 cycles of adjuvant chemotherapy of the same dose and drug regimen. Results The use of fluorine-18-fluorodeoxyglucose （18F-FDG） PET/CT significantly reduced the treat- ment volume delineation of the GTV in 83.3% （20/24） of patients. The 5-year local recurrence-free survival rates of the two groups were 100% and 79.2%, respectively （P = 0.019）. The 5-year disease free survival （DFS） rates were 95.8% and 75.0%, respectively （P = 0.018）. The 5-year local progression-free survival and DFS rates were significantly different. The 5-year overall survival （OS） rates were 95.8% and 79.2%, re- spectively. Differences in OS improvement were insignificant （P = 0.079）. Late toxicities were similar in the two groups. The most common late toxicities of the two arms were grade 1-2 skin dystrophy, xerostomia, subcutaneous fibrosis, and hearing loss. There were no cases of grade 4 late toxicity. Conclusion The use of 18F-FDG PET/CT-guided dose escalation radiotherapy is well tolerated and can reduce local recurrence rates for patients with locally advanced NPC compared to conventional chemora- diotherapy.

Prognostic value of post-treatment ^(18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy

Objective：To clarify the prognostic value of post-treatment 18F-fluorodeoxyglucose （FDG） positron emission tomography （PET）/computed tomography （CT） in patients with advanced head and neck squamous cell carcinoma （HNSCC） after combined intra-arterial chemotherapy and radiotherapy （IACR）.Methods：Thirty-six patients with HNSCC who underwent IACR were recruited.The period from the end of IACR to the last post-treatment 18F-FDG PET/CT examination was 8-12 weeks.Both patient-based and lesion-based analyses were used to evaluate the PET/CT images.For lesion-based analysis,36 regions （12 lesions of recurrences and 24 scars at primary sites） were selected.The Kaplan-Meier method was used to assess the overall survival （OS） stratified by 18F-FDG uptake or visual interpretation results.Results：Twelve patients with recurrence were identified by six months after IACR.The sensitivity and specificity in the patient-based analysis were 67％ （8/12） and 88％ （21/24）,respectively.The mean OS was estimated to be 12.1 months （95％ CI,6.3-18.0 months） for the higher maximum standardized uptake value （SUVmax） group （n=7） and 44.6 months （95％ CI,39.9-49.3 months） for the lower SUVmax group （n=29）.OS in the higher SUVmax group （cut-off point,6.1） or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group （P＜0.001 and P＜0.05,respectively）.Conclusions：The SUVmax and visual interpretation of HNSCC on post-IACR 18F-FDG PET/CT can provide prognostic survival estimates.

Role of F-18 FDG PET/CT imaging in the diagnosis of paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes(PNS) is a series of rare neurologic disorders which happen with an underlying malignancy. It has various clinical symptoms proceding to the diagnosis of tumors. Although the abnormality of anti-neuronal antibodies is suggestive of PNS and tumors, there exist many false positive and false negative cases. The diagnosis of PNS is usually a challenge in clinic. Positron emission tomography/computed tomography(PET/CT) imaging is an anatomical and functional fusion imaging method, which provides the whole-body information by single scan. Fluorodeoxyglucose(FDG) PET/CT imaging can not only detect potential malignant lesions in the whole body, but also assess functional abnormality in the brain. In this review, the mechanism, clinical manifestation, diagnostic procedure and the recent progress of the utility of FDG PET/CT in PNS are introduced respectively.

Ewing sarcoma/primitive neuroectodermal tumor of the ureter:A case report and literature review

Ewing sarcoma/primary neuroectodermal tumors are rare,invasive,and small round blue cell tumors.There are few reports of its occurrence in the urinary system.Here,we present the first middle-aged female patient whose Ewing sarcoma primary site was in the ureter.The main clinical manifestation was intermittent hematuria.She was in good health after complete surgical resection and adjuvant radiotherapy.To date,there has been no recurrence or metastasis.Accurate early diagnosis and appropriate treatment can help prolong survival.18F-fluorodeoxyglucose positron emission tomography/computed tomography is expected to be an effective means of evaluating treatment effects and detecting metastasis and recurrence.In this article,besides introducing a case of Ewing sarcoma/primitive neuroectodermal tumor of the ureter,we review the literature to discuss the current status of diagnosis and treatment.

The Role of ¹⁸F-FDG PET/CT in Staging Breast Carcinoma in Hanoi Oncology Hospital, Vietnam

Purpose: This study aimed to evaluate the role of 18F-FDG PET/CT scans in staging breast carcinoma. Materials and Methods: A descriptive study on 46 patients who were diagnosed with breast carcinoma in Hanoi Oncology Hospital, Vietnam from June 2019 to June 2021. Those patients underwent 18F-FDG PET/CT scans for pre-treatment staging. Results: There was a positive correlation between the size of primary tumors and their SUV (p < 0.0001, r = 0.759). The mean SUV was reported to be 2.5 for tumors under 2 cm, 5.89 for tumors from 2 - 5 cm, 13.6 for tumors above 5 cm, and 8.23 for skin invasive lesions. In terms of regional lymph node metastasis detection, the sensitivity and specificity of 18F-FDG PET/CT were 75% and 100%, respectively. The rate of distant metastasis detection was 15.2% (7/46 patients). Metastatic lesions were found in bone, lungs, liver, and lymph nodes. There was a significant difference in SUV among organs (p < 0.001), with the highest SUV found in bone metastasis. The rates of stage I, II, III and IV diagnosed after PET/CT are 8.7%;45.7%;30.4% and 15.2% respectively, compared to 10.9%;54.3%;32.6%;2.2% before taking 18F-FDG PET/CT. After PET/CT, 17.4% patients (8/46) had their treatment plan changed. Conclusions: 18F-FDG PET/CT plays an important role in staging breast carcinoma. Determining accurately the breast carcinoma stage by 18F-FDG PET/CT could help alter treatment strategy to best suit with patients, and avoid unnecessary surgery.

Optimal Threshold of Stimulated Serum Thyroglobulin Level for ^(18)F-FDG PET/CT imaging in Patients with Thyroid Cancer

This study was to explore the optimal threshold of thyroid-stimulating hormone(TSH)-stimulated serum thyroglobulin(s-Tg) for patients who were to receive18F-fluorodeoxyglucose(18F-FDG) PET/CT scan owing to clinical suspicion of differentiated thyroid cancer(DTC) recurrence but negative post-therapeutic 131I whole-body scan(131I-WBS). A total of 60 qualified patients underwent PET/CT scanning from October 2010 to July 2014. The receiver operating characteristic(ROC) curve analyses showed that s-Tg levels over 49 μg/L led to the highest diagnostic accuracy of PET/CT to detect recurrence, with a sensitivity of 89.5% and a specificity of 90.9%. Besides, bivariate correlation analysis showed positive correlation between s-Tg levels and the maximum standardized uptake values(SUVmax) of18F-FDG in patients with positive PET/CT scanning, suggesting a significant influence of TSH both on Tg release and uptake of18F-FDG. So, positive PET/CT imaging is expected when patients have negative 131I-WBS but s-Tg levels over 49 μg/L.

The influence of ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography on the N-and M-staging and subsequent clinical management of intrahepatic cholangiocarcinoma

Background:Intrahepatic cholangiocarcinoma(ICC)is a highly metastatic cancer.^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography(^(18)F-FDG PET/CT)enables sensitive tumor and metastasis detection.Our aim is to evaluate the influence of pre-treatment PET/CT on the N-and M-staging and subsequent clinical management in ICC patients.Methods:Between August 2010 and August 2018,660 consecutive ICC patients,without prior anti-tumor treatments nor other malignancies,were enrolled.The diagnostic performance of PET/CT on the N-and M-staging was compared with conventional imaging,and the preoperative staging accuracy and treatment re-allocation by PET/CT were retrospectively calculated.Survival difference was compared between patients receiving PET/CT or not after propensity score matching.Results:Patients were divided into group A(n=291)and group B(n=369)according to whether PET/CT was performed.Among 291 patients with both PET/CT and conventional imaging for staging in group A,PET/CT showed significantly higher sensitivity(83.0%vs.70.5%,P=0.001),specificity(88.3%vs.74.9%,P<0.001)and accuracy(86.3%vs.73.2%,P<0.001)than conventional imaging in diagnosing regional lymph node metastasis,as well as higher sensitivity(87.8%vs.67.6%,P<0.001)and accuracy(93.5%vs.89.3%,P=0.023)in diagnosing distant metastasis.Overall,PET/CT improved the accuracy of preoperative staging from 60.1%to 71.8%(P<0.001),and modified clinical treatment strategy in 5.8%(17/291)of ICC patients,with unique roles in different tumor-node-metastasis(TNM)stages.High tumor-to-non-tumor ratio(TNR)predicted poor overall survival[hazard ratio(HR)=2.17;95%confidence interval(CI):1.49-3.15;P<0.001].Furthermore,patients performing PET/CT had longer overall survival compared with those without PET/CT(HR=0.74;95%CI:0.58-0.93;P=0.011)after propensity score matching.Conclusions:PET/CT was valuable for diagnosing regional lymph node metastasis and distant metastasis in ICC patients,and facilitated accurate tumor staging and optimal treatment allocation.

The combined therapeutic effects of ^(131)iodinelabeled multifunctional copper sulfide-loaded microspheres in treating breast cancer

Compared to conventional cancer treatment, combination therapy based on well-designed nanoscale platforms may offer an opportunity to eliminate tumors and reduce recurrence and metastasis.In this study, we prepared multifunctional microspheres loading ^(131)I-labeled hollow copper sulfide nanoparticles and paclitaxel( ^(131)I-HCu SNPs-MS-PTX) for imaging and therapeutics of W256/B breast tumors in rats.18 F-fluordeoxyglucose(18 F-FDG) positron emission tomography/computed tomography(PET/CT) imaging detected that the expansion of the tumor volume was delayed(Po0.05) following intra-tumoral(i.t.) injection with ^(131)I-HCu SNPs-MS-PTX plus near-infrared(NIR) irradiation. The immunohistochemical analysis further confirmed the anti-tumor effect. The single photon emission computed tomography(SPECT)/photoacoustic imaging mediated by ^(131)I-HCu SNPs-MS-PTX demonstrated that microspheres were mainly distributed in the tumors with a relatively low distribution in other organs. Our results revealed that ^(131)I-HCu SNPs-MS-PTX offered combined photothermal, chemo-and radio-therapies, eliminating tumors at a relatively low dose, as well as allowing SPECT/CT and photoacoustic imaging monitoring of distribution of the injected agents non-invasively. The copper sulfide-loaded microspheres, ^(131)I-HCu SNPs-MS-PTX, can serve as a versatile theranostic agent in an orthotopic breast cancer model.

The Analysis of Effective Radiation Dose during PET/CT Examination

Objective: In order to reduce the effective dose level of the patients to explore the best scanning conditions, various factors affecting the level of PET/CT examination were analyzed. Methods: The effective doses of CT and pet were calculated respectively during PET/CT examination, Scanning parameters of CT and PET were optimized to reduce the effective dose of patients to a minimum while maintaining the image quality. Results: The tube voltage and tube current of CT, the injection dose during PET examination can affect the effective dose of the patients significantly. Conclusion: According to different types of patients and diseases to develop personalized scanning program, the effective dose level of the patients can be significantly reduced.

Albumin mediated reactive oxygen species scavenging and targeted delivery of methotrexate for rheumatoid arthritis therapy

Rheumatoid arthritis(RA)is a common chronic systemic autoimmune disease.Although there are a variety of treatments for RA,the substantial clinical therapies are still limited to disease-modifying anti-rheumatic drugs(DMARD),which would induce obvious side-effect in patients after long-term administration.Herein,an uncomplicated drug-induced self-assembly strategy was proposed to fabricate enzyme-loaded albumin nanomedicine.The hydrophobic drug methotrexate(MTX)could induce self-assembly of superoxide dismutase(SOD)and human serum albumin(HSA)to form HSA-SOD-MTX nanoparticle.After intravenous injection,dual-modal imaging including fluorescence imaging or single-photon emission computed tomography(SPECT)/CT imaging exhibits high accumulation of cyanine 5.5(Cy5.5)or 125l labeled HSA-SOD-MTX nanoparticles in the joints of collagen-induced arthritis(CIA)mice.Importantly,using the synergy therapy of SOD enzyme to scavenge the reactive oxygen species(ROS)and MTX to suppress inflammation,HSA-SOD-MTX nanoparticles exhibit excellent therapeutic efficiency of RA in CIA mice compared with the other groups.Micro-CT and clinical arthritis score of RA mice further demonstrate that RA symptoms of mice treated with HSA-SOD-MTX nanoparticles is significantly relived,which was further demonstrated by the histological analysis and the inflammatory factors measurement.The synergy therapy of inflammation by MTX and SOD enzyme based on HSA-SOD-MTX nanoparticles show excellent therapeutic effects of RA without inducing obvious side effects.Therefore,our strategy may further promote the highly efficient therapy of RA using SOD enzyme to scavenge the ROS and decreasing the side-effect of MTX,which may provide the reference for clinical RA treatment.