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.

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.

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.

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.

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.

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.

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.

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.

Positron emission tomography/computer tomography:Challenge to conventional imaging modalities in evaluating primary and metastatic liver malignancies

Computer tomography (CT) and magnetic resonance imaging (MRI),as conventional imaging modalities,are the preferred methodology for tumor,nodal and systemic metastasis (TNM) staging. However,all the noninvasive techniques in current use are not sufficiently able to identify primary tumors and even unable to define the extent of metastatic spread. In addition,relying exclusively on macromorphological characteristics to make a conclusion runs the risk of misdiagnosis due mainly to the intrinsic limitations of the imaging modalities themselves. Solely based on the macromorphological characteristics of cancer,one cannot give an appropriate assessment of the biological characteristics of tumors. Currently,positron emission tomography/computer tomography (PET/CT) are more and more widely available and their application with 18F-fluorodeoxyglucose (18F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors,and monitoring the therapeutic efficacy in hepatic malignancies. Recently,investigators have measured glucose utilization in liver tumors using 18F-FDG,PET and PET/CT in order to establish diagnosis of tumors,assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. PET/ CT with 18F-FDG as a radiotracer may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis,staging,restaging and evaluating its biological characteristics,which can benefit the patients suffering from hepatic metastases,hepatocellular carcinoma and cholangiocarcinoma.

Clinical significance of prostate 18F-labelled fluorodeoxyglucose uptake on positron emission tomography/computed tomography:A five-year review

AIM To determine the significance and need for investigation of incidental prostatic uptake in men undergoing ^(18)F-labelled fluorodeoxyglucose(^(18)F-FDG) positron emission tomography/computed tomography(PET/CT) for other indications.METHODS Hospital databases were searched over a 5-year period for patients undergoing both PET/CT and prostate magnetic resonance imaging(MRI). For the initial analysis, the prostate was divided into six sectors and suspicious or malignant sectors were identified using MRI and histopathology reports respectively. Maximum and mean ^(18)F-FDG standardised uptake values were measured in each sector by an investigator blinded to the MRI and histopathology findings. Two agematched controls were selected per case. Results were analysed using a paired t-test and one-way ANOVA. For the second analysis, PET/CT reports were searched for prostatic uptake reported incidentally and these patients were followed up. RESULTS Over a 5-year period, 15 patients underwent both PET/CT and MRI and had biopsy-proven prostate cancer.Malignant prostatic sectors had a trend to higher ^(18)F-FDG uptake than benign sectors, however this was neither clinically nor statistically significant(3.13 ±0.58 vs 2.86 ± 0.68, P > 0.05). ^(18)F-FDG uptake showed no correlation with the presence or histopathological grade of tumour. ^(18)F-FDG uptake in cases with prostate cancer was comparable to that from age-matched controls. Forty-six(1.6%) of 2846 PET/CTs over a 5-year period reported incidental prostatic uptake. Of these, 18(0.6%) were investigated by PSA, 9(0.3%)were referred to urology, with 3(0.1%) undergoing MRI and/or biopsy. No cases of prostate cancer were diagnosed in patients with incidental ^(18)F-FDG uptake in our institute over a 5-year period.CONCLUSION ^(18)F-FDG uptake overlaps significantly between malignant and benign prostatic conditions. Subsequent patient management was not affected by the reporting of incidental focal prostatic uptake in this cohort.

Role of 18F-fluorodeoxyglucose positron emission tomography imaging in surgery for pancreatic cancer

AIM： To evaluate the role of positron emission tomography using 18F-fluorodeoxyglucose （FDG-PET） in the surgical management of patients with pancreatic cancer, including the diagnosis, staging, and selection of patients for the subsequent surgical treatment. METHODS： This study involved 53 patients with proven primary pancreatic cancer. The sensitivity of diagnosing the primary cancer was examined for FDG-PET CT, cytological examination of the bile or pancreatic juice, and the serum levels of carcinoembrionic antigens （CEA） and carbohydrate antigen 19-9 （CA29-9）. Next, the accuracy of staging was compared between FDG-PET and CT. Finally, FDG-PET was analyzed semiquantitatively using the standard uptake value （SUV）. The impact of the SUV on patient management was evaluated by examining the correlations between the SUV and the histological findings of cancer. RESULTS： The sensitivity of FDG-PET, CT, cytological examination of the bile or pancreatic juice, and the serum levels of CEA and CA19-9 were 92.5%, 88.7%, 46.4%, 37.7% and 69.8%, respectively. In staging, FDG-PET was superior to CT only in diagnosing distant disease （bone metastasis）. For local staging, the sensitivity of CT was better than that of FDG-PEr. The SUV did not correlate with the pTNM stage, grades, invasions to the vessels and nerve, or with the size of the tumor. However, there was a statistically significant difference （4.6 ± 2.9 vs 7.8 ± 4.5, P = 0.024） in the SUV between patients with respectable and unresectable disease. CONCLUSION： FDG-PET is thus considered to be useful in the diagnosis of pancreatic cancer. However, regarding the staging of the disease, FDG-PET is not considered to be a sufficiently accurate diagnostic modality. Although the SUV does not correlate with the patho-histological prognostic factors, it may be useful in selecting patients who should undergo subsequent surgical treatment.

^(18)F-fluorodeoxyglucose positron emission tomography in the diagnosis of small pancreatic cancer

AIM:To investigate the role of 18 F-fluorodeoxyglucose positron emission tomography(FDG-PET) in the diagnosis of small pancreatic cancer. METHODS:This study involved 31 patients with proven invasive ductal cancer of the pancreas.The patients were divided into 3 groups according to the maximum diameter of the tumor:TS1(maximum tumor size≤2.0 cm) ,TS2(>2.0 cm and≤4.0 cm) or TS3-4(>4.0 cm) .The relationships between the TS and various diagnostic tools,including FDG-PET with dual time point evaluation,were analyzed. RESULTS:The tumors ranged from 1.3 to 11.0 cm in diameter.Thirty of the 31 patients(97%) had a positive FDG-PET study.There were 5 patients classified as TS1,15 as TS2 and 11 as TS3-4.The sensitivity of FDG-PET,computed tomography(CT) and magnetic resonanceimaging(MRI) were 100%,40%,0%in TS1,93%,93%,89%in TS2 and 100%,100%,100%in TS3-4. The sensitivity of FDG-PET was significantly higher in comparison to CT and MRI in patients with TS1(P< 0.032) .The mean standardized uptake values(SUVs) did not show a significant difference in relation to the TS(TS1:5.8±4.5,TS2:5.7±2.2,TS3-4:8.2±3.9) ,respectively.All the TS1 tumors(from 13 to 20 mm) showed higher SUVs in FDG-PET with dual time point evaluation in the delayed phase compared with the early phase,which suggested the lesions were malignant. CONCLUSION:These results indicate that FDG-PET with dual time point evaluation is a useful modality for the detection of small pancreatic cancers with a diameter of less than 20 mm.

Diagnosis and evaluation of gastric cancer by positron emission tomography

Gastric cancer is the second leading cause of cancer mortality worldwide. The diagnosis of gastric cancer has been significantly improved with the broad availability of gastrointestinal endoscopy. Effective technologies for accurate staging and quantitative evaluation are still in demand to merit reasonable treatment and better prognosis for the patients presented with advanced disease. Preoperative staging using conventional imaging tools, such as computed tomography (CT) and endoscopic ultrasonography, is inadequate. Positron emission tomography (PET), using 18F-fluorodeoxyglucose (FDG) as a tracer and integrating CT for anatomic localization, holds a promise to detect unsuspected metastasis and has been extensively used in a variety of malignancies. However, the value of FDG PET/CT in diagnosis and evaluation of gastric cancer is still controversial. This article reviews the current literature in diagnosis, staging, response evaluation, and relapse monitoring of gastric cancer, and discusses the current understanding, improvement, and future prospects in this area.

Electroacupuncture at Tianshu (ST 25) for diarrhea-predominant irritable bowel syndrome using positron emission tomography Changes in visceral sensation center

Previous studies have demonstrated that electroacupuncture therapy is effective in the treatment of irritable bowel syndrome. However, the precise mechanism of this therapy is unknown. The present study served to investigate the effects of electroacupuncture therapy on treatment of patients with diarrhea-predominant irritable bowel syndrome （IBS）. We compared brain activation maps based on the changes of cerebral glucose metabolism obtained by 18-fluorodeoxyglucose positron emission tomography scanning under three conditions： resting, rectal balloon distension and rectal balloon distension plus electroacupuncture. Under the resting condition, compared with healthy controls, IBS patients displayed an increasing regional cerebral metabolic rate of glucose over a wide range： bilateral superior temporal gyrus, right middle occipital gyrus, superior frontal gyrus and bilateral middle frontal gyrus. However, there was no significant activity in the visceral pain center. Compared with the resting condition, under the rectal balloon distension condition, patients with IBS had a greater regional cerebral metabolic rate of glucose in the prefrontal cortex, left anterior cingulate cortex, postcentral gyrus, precentral gyrus and temporal gyrus. Under the rectal balloon distension plus electroacupuncture condition, stimulation by electroacupuncture at Tianshu （ST 25） manifested a decreased regional cerebral metabolic rate of glucose in the left cingulate gyrus, right insula, right caudate nucleus, fusiform gyrus and hippocampal gyrus. Electroacupuncture therapy relieved abdominal pain, distension or discomfort by decreasing glucose metabolism in the brain.

Early detection of response to imatinib therapy for gastrointestinal stromal tumor by using 18F-FDG-positron emission tomography and computed tomography imaging

A 41-year old female with metastatic gastrointestinal stromal tumor was referred to 18F-FDG-positron emission tomography and computed tomography （PET/CT） scan before and after one-month treatment with imatinib （Glivec, Gleevec, Novartis, Basel, Switzerland）, a tyrosine kinase inhibitor （400 mg/d）. Metabolic response was evaluated before and after one month of therapy. The decrease of the maximum standardised uptake value （SUV） was 79% （from 9.8 to 2.1）. Positron emission tomography demonstrated complete metabolic response after one-month of imatinib treatment. Additionally, the previous lesion was compared with the coronal computerized tomographic image. There was no difference in the size of the tumor before and after therapy according to CT images. However, metabolic activity was inhibited. 18F-FDG-PEr is a valuable method for the detection of response to one-month imatinib treatment in patients with gastrointestinal stromal tumors.

Highly metabolic thrombus of the portal vein:^(18)F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma

AIM： To assess the ability of ^18F-fluorodeoxyglucose positron emission tomography/computer tomography （^18F-FDG PET/CT） to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma （HCC） patients.METHODS： Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound （US）, computer tomography （CT） or magnetic resonance imaging （MRI） were studied with ^18F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on ^18F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. ^18SF-FDG PET/CT, and US, CT or MRI results were compared.RESULTS： Follow-up （1 to 10 mo） showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. ^18F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. ^18F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using ^18F-FDG PET/CT.CONCLUSION： ^18F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from ^18F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.

Clinical relevance of fluorodeoxyglucose positron emission tomography/computed tomography and magnifying endoscopy with narrow band imaging in decision-making regarding the treatment strategy for esophageal squamous cell carcinoma

BACKGROUND Recent advances in endoscopic technology,especially magnifying endoscopy with narrow band imaging(ME-NBI)enable us to detect superficial esophageal squamous cell carcinoma(ESCC),but determining the appropriate method of resection,endoscopic resection(ER)vs surgical resection,is often challenging.Recently,several studies have reported that 18F-fluorodeoxyglucose positron emission tomography(FDG-PET)is a useful indicator for decision-making regarding treatment for superficial ESCC.Although,there are not enough reports on association between FDG-PET uptake and clinicopathological characteristics of superficial ESCC.And,there are not enough reports on evaluating the usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.This study evaluated clinical relevance of FDG-PET and ME-NBI in decision-making regarding the treatment strategy for ESCC.AIM To investigate the association between FDG uptake and the clinicopathological characteristics of superficial ESCC and its usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.METHODS A database of all patients with superficial ESCC who had undergone both MENBI and FDG-PET for pre-treatment staging at Aichi Cancer Center Hospital between January 2008 and November 2018 was retrospectively analyzed.FDG uptake was defined positive or negative whether the primary lesion was visualized or could be distinguished from the background,or not.The invasion depth of ESCC was classified according to the Japan Esophageal Society.Primary endpoint is to evaluate the association between FDG uptake and clinicopathological characteristics of superficial ESCC.Secondary endpoint is to investigate the efficacy of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.RESULTS A total of 82 lesions in 82 patients were included.FDG-PET showed positive uptake in 29(35.4%)lesions.Univariate analysis showed that uptake of FDG-PET had significant correlations with circumferential extension(P=0.014),pathological depth of tumor invasion(P<0.001),infiltrative growth pattern(P<0.001),histological grade(P=0.002),vascular invasion(P=0.001),and lymphatic invasion(P<0.001).On multivariate analysis,only depth of tumor invasion was independently correlated with FDG-PET/computed tomography visibility(P=0.018).The sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),and accuracy of Type B2 in ME-NBI for the invasion depth of T1a muscularis mucosae and T1b upper submucosal layer were 68.4%/79.4%/50.0%/89.3%/76.8%,respectively,and those of Type B3 for the depth of T1b middle and deeper submucosal layers(SM2 and SM3)were 46.7%/100%/100%/89.3%/90.2%,respectively.On the other hand,those of FDGPET for SM2 and SM3 were 93.3%/77.6%/48.2%/98.1%/80.5%,respectively,whereas,if the combination of positive FDG uptake and type B2 and B3 was defined as an indicator for radical esophagectomy or definitive chemoradiotherapy,the sensitivity,specificity,PPV,NPV,and accuracy were 78.3%/91.5%/78.3%/91.5%/87.8%,respectively.CONCLUSION FDG uptake was correlated with the invasion depth of superficial ESCC.Combined use of FDG-PET and ME-NBI,especially with the microvascular findings of Type B2 and B3,is useful to determine whether ER is indicated for the lesion.

Role of(～(18)F)2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

The role of whole-body FDG [(～(18)F)2-fluoro-2-deoxy-glucose] positron emission tomography(PET)scan-ning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades.FDG-PET has demonstrated signifi cant effi cacy in the staging,prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract,in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools.The sensitivity and specif icity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases,but also on histologi-cal cell type,reflecting underlying disparities in glucose metabolism.The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate signifi cantly with both the histological tumor response to treatment and with consequent improvements in overall survival.This may offer a future paradigm ofpersonalized treatment based on the PET response to chemotherapy.FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastro-intestinal malignancies,and in the detection of low vol-ume metastatic peritoneal disease.Efforts to improve the accuracy of PET include the use of novel radiotrac-ers such as(～(18)F)FLT(3-deoxy-3-fluorothymidine)or 11C-choline,or fusion PET-CT with concurrent high-res-olution computed tomography.This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointesti-nal tract,specif ically gastric,esophageal and pancreas carcinoma.

Port site and distant metastases of gallbladder cancer after laparoscopic cholecystectomy diagnosed by positron emission tomography

We report port site and distant metastases of unsuspected gallbladder cancer after laparoscopic cholecystectomy diagnosed by positron emission tomography （PET） in two patients. Patient 1, a 72-yearold woman was diagnosed as cholelithiasis and cholecystitis and received laparoscopic cholecystectomy. Unsuspected gallbladder cancer was discovered with histological result of well-differentiated squamous cell carcinoma of the gallbladder infiltrating the entire wall. A PET scan using F-18-fluorodeoxyglucose （FDG- PET） before radical resection revealed residual tumor in the gallbladder fossa and recurrence at port site and metastases in bilateral hilar lymph nodes. Patient 2, a 69-year-old woman underwent laparoscopic cholecystectomy more than one year ago with pathologically confirmed unsuspected adenosquamous carcinoma of stage pTlb. At 7-mo follow-up after surgery, the patient presented with nodules in the periumbilical incision. Excisional biopsy of the nodule revealed adenosquamous carcinoma. The patient was examined by FDG-PET, demonstrating increased FDG uptake in the right lobe of the liver and mediastinal lymph nodes consistent with metastatic disease. This report is followed by a discussion about the utility of FDG-PET in the gallbladder cancer.