Significance of incidental focal fluorine-18 fluorodeoxyglucose uptake in colon/rectum,thyroid,and prostate:With a brief literature review

BACKGROUND Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography(F-18 FDG PET/CT),a functional imaging method,is usually performed on the entire torso,and regions of unexpected suspicious focal hypermetabolism are not infrequently observed.Among the regions,colon,thyroid,and prostate were found to be the common organs in a recent umbrella review.Some studies reported that a high rate of malignancy was shown in incidentally identified focal hypermetabolic regions and suggested that further examinations should not be ignored.AIM To investigate the malignancy rate of incidental focal FDG uptake,useful PET parameters and their cutoffs in discrimination between malignant and benign lesions.METHODS Retrospectively,the final reports of 16510 F-18 FDG PET/CT scans performed at our hospital between January 2016 and March 2022 were reviewed to identify incidentally observed FDG uptake in the colon/rectum,thyroid,and prostate.The scans of patients with current or prior malignancies at each corresponding location,without the final reports of histopathology or colonoscopy(for colon and rectum)for the corresponding hypermetabolic regions,or with diffuse(not focal)hypermetabolism were excluded.Finally,88 regions of focal colorectal hypermetabolism in 85 patients(48 men and 37 women with mean age 67.0±13.4 years and 63.4±15.8 years,respectively),48 focal thyroid uptakes in 48 patients(12 men and 36 women with mean age 62.2±13.1 years and 60.8±12.4 years,respectively),and 39 focal prostate uptakes in 39 patients(mean age 71.8±7.5 years)were eligible for this study.For those unexpected focal hypermetabolic regions,rates of malignancy were calculated,PET parameters,such as standardized uptake value(SUV),capable of distinguishing between malignant and benign lesions were investigated,and the cutoffs of those PET parameters were determined by plotting receiver operating characteristic curves.RESULTS In the colon and rectum,29.5%(26/88)were malignant and 33.0%(29/88)were premalignant lesions.Both SUVmax and SUVpeak differentiated malignant/premalignant from benign lesions,however,no parameters could distinguish malignant from premalignant lesions.Higher area under the curve was shown with SUVmax(0.752,95%CI:0.649-0.856,P<0.001)and the cutoff was 7.6.In the thyroid,60.4%(29/48)were malignant.The majority were well-differentiated thyroid cancers(89.7%,26/29).The results of BRAF mutation tests were available for 20 of the 26 welldifferentiated thyroid cancers and all 20 had the mutation.Solely SUVmax differentiated malignant from benign lesions and the cutoff was 6.9.In the prostate,56.4%(22/39)were malignant.Only SUVmax differentiated malignant from benign lesions and the cutoff was 3.8.Overall,among the 175 focal hypermetabolic regions,60.6%(106/175)were proven to be malignant and premalignant(in colon and rectum)lesions.CONCLUSION Approximately 60%of the incidentally observed focal F-18 FDG uptake in the colon/rectum,thyroid,and prostate were found to be malignant.Of the several PET parameters,SUVmax was superior to others in distinguishing between malignant/premalignant and benign lesions.Based on these findings,incidental focal hypermetabolism should not be ignored and lead physicians to conduct further investigations with greater confidence.

Assessment of incidental focal colorectal uptake by analysis of fluorine-18 fluorodeoxyglucose positron emission tomography parameters

BACKGROUND Colon and rectal cancers are among the top five cancers worldwide in terms of their incidence and mortality rates.As the treatment options for cure include surgery even in specific advanced-stage cases,the early detection of lesions is important for applying active treatment methods.Fluorine-18 fluorodeoxyglucose(F-18 FDG)positron emission tomography/computed tomography(PET/CT)is an established imaging study for many types of cancers;however,physiologic uptake in the gastrointestinal tract is a frequent finding and may interfere with lesion identification.Nevertheless,as unexpectedly observed focal colorectal F-18 FDG uptake may harbor malignant lesions,further examination must not be avoided.AIM To assess the clinical implications of unexpected focal colorectal F-18 FDG uptake by analyzing FDG PET parameters.METHODS A total of 15143 F-18 FDG PET/CT scans performed at our hospital between January 2016 and September 2021 were retrospectively reviewed to identify incidentally observed focal colorectal FDG uptake.Finally,83 regions showing focal colorectal FDG uptake with final histopathological reports from 80 patients(45 men and 35 women with mean ages of 66.9±10.7 years and 63.7±15.3 years,respectively)were eligible for inclusion in the present study.Each focal hypermetabolic colorectal region was classified as malignant,premalignant,or benign according to the histopathological report.PET parameters such as maximum and peak standardized uptake value(SUVmax and SUVpeak),metabolic tumor volume(MTV),mean SUV of the metabolic tumor volume(mSUVmtv),and total lesion glycolysis(TLG)were measured or calculated for the corresponding hypermetabolic regions.Parametric and nonparametric statistical comparisons of these parameters were performed among the three groups.Receiver operating characteristic curves were plotted to identify cut-off values.RESULTS The detection rate of incidental focal colorectal uptake was 0.53%(80/15,143).Of the 83 regions with unexpected focal colorectal hypermetabolism,28.9%(24/83)were malignant,32.5%(27/83)were premalignant,and 38.6%(32/83)were benign.Overall,61.4% of the regions had malignant or premalignant lesions.SUVmax,SUVpeak,and mSUVmtv differentiated malignant and/or premalignant lesions from benign lesions with statistical significance(P<0.05).mSUVmtv3.5 differentiated malignant from benign lesions,with the largest area under the curve(AUC)of 0.792 and a cut-off of 4.9.SUVmax showed the largest AUC of 0.758 with a cut-off value of 7.5 for distinguishing between premalignant and benign lesions.Overall,SUVmax with a cut-off value of 7.6(AUC:0.770,95% confidence interval(CI):0.668-0.872;sensitivity,0.686;specificity,0.688)was a superior parameter for distinguishing between malignant/premalignant and benign lesions or physiologic uptake.No parameters differentiated malignant from premalignant lesions.Moderate or weak positive correlations were observed between the long diameter of the malignant lesions and PET parameters such as SUVpeak and some mSUVmtv.CONCLUSION Approximately two-thirds(61.4%)of incidental focal hypermetabolic colorectal regions were malignant/premalignant lesions,for which SUVmax was an independent diagnostic parameter.Unexpected suspicious focal colorectal FDG uptake should not be avoided and consideration for further evaluation is strongly recommended not to miss the two-thirds.

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.

Imaging of atherosclerotic aorta of rabbit model by detection of plaque inflammation with fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography

Abstract：Background Atherosclerotic plaque rupture is the primary mechanism of thrombosis which plays a key role in the onset of acute coronary syndromes. Detection of these plaques prone to rupture （vulnerable plaque） could be clinically significant for prevention of cardiac events. It has been shown that high metabolism cells have a high uptake of fluorine-18 fluorodeoxyglucose （18F-FDG）. The objective of this study was to investigate the correlation of FDG uptake and the immuno-histochemistry parameters of plaques, and the effect of atorvastatin on vulnerable atherosclerotic plaque in a rabbit model.Methods Ten male New Zealand White rabbits were divided into three groups as follows： （1） normal control group （n=2,C group）： the animals were fed a standard diet at 120 g/d and were given water ad labium; （2） atherosclerosis group （n=4,As group）： animals were fed with high fat diet for 5 months after aortic endothelia damage; （3） treatment group （atherosclerosis ＋ atorvastatin, n=4, Statin group）： animals were fed with high fat diet for 5 months and then changed into normal chow plus atorvastatin （2.5 mg·d-1·kg-1） treatment for another 4 months. Then these four rabbits were imaged with fluorine-18 fluorodexyglucose positron emission tomography/computed tomography （PET/CT） and sacrificed for pathohistologic studies. FDG uptake by the aorta was expressed as target-to-background ratio （TBR）. Maximal standardized uptake value （SUV） was measured over the thoracic and abdominal aortas. The aortic smooth muscle cell （SMC） number, CD-14 antibody positive cell （macrophage） number and the ratio of the thickness of fibrous cap to the thickness of lipid core （cap-to-core ratio） in atherosclerotic plaques were analyzed.Results As group showed significantly higher uptake of FDG than C group （SUVs： 0.746±0.172 vs. 0.286±0.073, P 〈0.001）. After 4 months of atorvastatin treatment and the modification of diet, SUVs decreased significantly （Statin group：0.550±0.134, compared to As group, P 〈0.001）. However, no marked difference was found in TBR, the number of macrophages, the number of SMC and the cap-to-core ratio in the aortic segments between Statin group and As group.The correlation of aortic FDG uptake with SMC assessed by histopathology was negatively significant （r=0.57, P〈0.001）. When aortic FDG uptake was expressed as TBR, it correlated significantly （r=0.69, P 〈0.001） with the macrophage number, and also correlated significantly （r=0.78, P 〈0.001） with the cap-to-core ratio.Conclusion 18F-FDG PET/CT might serve as a useful non-invasive imaging technique for detection of atherosclerotic plaque and potentially permit monitoring of relative changes in inflammation within the atherosclerotic lesion.

Prognostic value and clinical correlations of18-fluorodeoxyglucose metabolism quantifiers in gastriccancer

AIM： To investigate the correlations of pre-treatmentpositron emission tomography-computer tomography（PET-CT） metabolic quantifiers with clinical data ofunstratified gastric cancer （GC） patients.METHODS： Forty PET-CT scans utilising 18-fluorodeoxyglucosein patients who received no prior treatmentwere analysed. Analysis involved measurements ofmaximum and mean standardised uptake volumes（SUV）, coefficient of variation （COV）, metabolictumour volumes and total lesion glycolysis of differentthresholds above which the tumor volumes wereidentified. The threshold values were： SUV absolutevalue of 2.5, 30% of SUVmax, 40% of SUVmax,and liver uptake-based （marked 2.5, 30, 40 and liv,respectively）. Clinical variables such as age, sex,clinical stage, performance index, weight loss, tumorhistological type and grade, and CEA and CA19.9 levelswere included in survival analysis. Patients receivedvarious treatment modalities appropriate to theirdisease stage and the outcome was defined by time tometastasis （TTM） and overall survival （OS）. Clinical andmetabolic parameters were evaluated by analysis of variance, receiver operating characteristics, univariateKaplan-Meier, and multivariate Cox models. P 〈 0.05was considered statistically significant.RESULTS： Significant differences were observedbetween initially disseminated and non-disseminatedpatients in mean SUV （6.05 vs 4.13, P = 0.008）, TLG2.5（802 cm3 vs 226 cm3; P = 0.031）, and TLG30 （436 cm3vs 247 cm3, P = 0.018）. Higher COV was associatedwith poor tumour differentiation （0.47 for G3 vs0.28 for G1 and G2; P = 0.03）. MTV2.5 was positivelycorrelated to patient weight loss （〈 5%, 5%-10%and 〉 10%： 40.4 cm3 vs 123.6 cm3 vs 181.8 cm3,respectively, P = 0.003）. In multivariate Cox analysis,TLG30 was prognostic for OS （HR = 1.001, 95%CI：1.0009-1.0017; P = 0.047） for the whole group ofpatients. In the same model yet only including patientswithout initial disease dissemination TLG30 （HR = 1.009,95%CI： 1.003-1.014; P = 0.004） and MTV2.5 （HR = 1.02,95%CI： 1.002-1.036; P = 0.025） were prognostic forOS; for TTM TLG30 was the only significant prognosticvariable （HR = 1.006, 95%CI： 1.001-1.012; P = 0.02）.CONCLUSION： PET-CT in GC may represent a valuablediagnostic and prognostic tool that requires furtherevaluation in highly standardised environments such asrandomised clinical trials.

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.

Incidental anal ^18fluorodeoxyglucose uptake:Should we further examine the patient?

BACKGROUND There are no studies on incidental anal ^18F-fluorodeoxyglucose(^18FDG)uptake.AIM To assess the rate and aetiologies of incidental anal ^18FDG uptake and to evaluate the correlation between ^18FDG positron-emission tomography/computed tomography(PET/CT)parameters and the diagnosis of an anorectal disease.METHODS The data from patients with incidental anal ^18FDG uptake were retrospectively analysed.Patients who underwent anorectal examinations were identified and compared to those who did not undergo examinations.Patients who were offered treatment were then identified and compared to those who did not receive treatment.RESULTS Among the 43020^18FDG PET/CT scans performed,197^18FDG PET/CT scans of 146 patients(0.45%)reported incidental anal uptake.Among the 134 patients included,48(35.8%)patients underwent anorectal examinations,and anorectal diseases were diagnosed in 33(69.0%)of these patients and treated in ^18/48(37.5%)patients.Among the examined patients,those with a pathology requiring treatment had significantly smaller metabolic volumes(MV)30 and MV41 values and higher maximal and mean standardized uptake value measurements than those who did not require treatment.CONCLUSION Incidental anal ^18FDG uptake is rare,but a reliable anorectal diagnosis is commonly obtained when an anorectal examination is performed.The diagnosis of an anorectal disease induces treatment in more than one-third of the patients.These data should encourage practitioners to explore incidental anal ^18FDG uptake systematically.

Prognostic value of pre-treatment F-18-FDG PET-CT in patients with hepatocellular carcinoma undergoing radioembolization

AIM To evaluate the value of pre-treatment 18F-FDG PET/CT in patients with HCC following liver radioembolization.METHODS We identified 34 patients with HCC who underwent an FDG PET/CT scan prior to hepatic radioembolization at our institution between 2009 and 2013. Patients wereseen in clinic one month after radioembolization and then at 2-3 mo intervals. We assessed the influence of FDG tumor uptake on outcomes including local liver control(LLC), distant liver control(DLC), time to distant metastases(DM), progression free survival(PFS) and overall survival(OS).RESULTS The majority of patients were males(n = 25, 74%), and had Child Pugh Class A(n = 31, 91%), with a median age of 68 years(46-84 years). FDG-avid disease was found in 19(56%) patients with SUVmax ranging from 3 to 20. Female patients were more likely to have an FDG-avid HCC(P = 0.02). Median follow up of patients following radioembolization was 12 months(1.2-62.8 mo). FDG-avid disease was associated with a decreased 1 year LLC, DLC, DM and PFS(P < 0.05). Using multivariate analysis, FDG avidity predicted for LLC, DLC, and PFS(all P < 0.05).CONCLUSION In this retrospective study, pre-treatment HCC FDGavidity was found to be associated with worse LLC, DLC, and PFS following radioembolization. Larger studies are needed to validate our initial findings to assess the role of F-18-FDG PET/CT scans as biomarker for patients with HCC following radioembolization.

Xanthogranulomatous cholecystitis mimicking gallbladder carcinoma with a false-positive result on fluorodeoxyglucose PET

Recently, several reports have demonstrated that fluorine-18 fluorodeoxyglucose positron emission tomography （FDG-PET） is useful in differentiating between benign and malignant lesions in the gallbladder. However, there is a limitation in the ability of FDG-PET to differentiate between inflammatory and malignant lesions. We herein present a case of xanthogranulomatous cholecystitis misdiagnosed as gallbladder carcinoma by ultrasonography and computed tomography. FDG-PET also showed increased activity. In this case, FDG-PET findings resulted in a false-positive for the diagnosis of gallbladder carcinoma.

Multimodality functional imaging using DW-MRI and 18F-FDG-PET/CT during radiation therapy for human papillomavirus negative head and neck squamous cell carcinoma: Meixoeiro Hospital of Vigo Experience

AIMTo noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging (DW-MRI) and glucose metabolism measured by 18F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) during radiation therapy (RT) for human papillomavirus negative (HPV-) head and neck squamous cell carcinoma (HNSCC).METHODSIn this prospective study, 6 HPV- HNSCC patients underwent a total of 34 multimodality imaging examinations DW-MRI at 1.5 T Philips MRI scanner [(n = 24) pre-, during- (2-3 wk), and post-treatment (Tx), and 18F-FDG PET/CT pre- and post-Tx (n = 10)]. All patients received RT. Monoexponential modeling of the DW-MRI data yielded the imaging metric apparent diffusion coefficient (ADC) and the mean of standardized uptake value (SUV) was measured from 18F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year.RESULTSThere was a strong negative correlation between the mean of pretreatment ADC (ρ = -0.67, P = 0.01) and the pretreatment 18F-FDG PET SUV. The percentage (%) change in delta (∆) ADC for primary tumors and neck nodal metastases between pre- and Wk2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31%, respectively, for those who were dead with disease.CONCLUSIONThese results are preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience.

Clinical implication of FDG uptake of bone marrow on PET/CT in gastric cancer patients with surgical resection

AIM To determine the relationship between F-18 fluorodeoxyglucose(FDG) uptake of bone marrow(BM) on positron emission tomography/computed tomography(PET/CT) and clinical factors and to assess the prognostic value of FDG uptake of BM in gastric carcinoma.METHODS We retrospectively enrolled 309 gastric cancer patients who underwent staging FDG PET/CT and curative surgical resection. FDG uptake of primary tumor was visually classified as positive or negative FDG uptake. Mean FDG uptake of BM(BM SUV) and BM-to-liver uptake ratio(BLR) were measured. The relationships of BM SUV or BLR with clinical factors were evaluated. The prognostic values of BM SUV, BLR, and other clinical factors for predicting recurrence-free survival(RFS) and overall survival(OS) were assessed.RESULTS Of 309 patients, 38 patients(12.3%) experienced cancer recurrence and 18 patients(5.8%) died. Patients with advanced gastric cancer, positive FDG uptake, and recurrence had higher values of BM SUV and BLR than those with early gastric cancer, negative FDG uptake, and no recurrence(P < 0.05). BM SUV and BLR were significantly correlated with hemoglobin level, neutrophil-to-lymphocyte ratio, and platelet-tolymphocyte ratio(P < 0.05). On multivariate analysis, multiple tumors, T stage, lymph node metastasis, tumor involvement of resection margin, and BLR were significantly associated with RFS(P < 0.05). T stage, lymph node metastasis, hemoglobin level, and BLR were significantly associated with OS(P < 0.05). CONCLUSION BLR on PET/CT was an independent prognostic factor for RFS and OS in gastric cancer patients with curative surgical resection.

Combination of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging is an optimal way to evaluate rheumatoid arthritis in rats dynamically

Background Rheumatoid arthritis （RA） is a chronic,systemic autoimmune inflammatory disorder.Many methods have been used to observe the progress of RA.The purpose of this study was to observe the progress of RA in rats with 18F-fluorodeoxyglucose （FDG） positron emission tomography/computed tomography （PET/CT）,magnetic resonance （MR） imaging and arthritis score,and analyze the relationships among different methods in evaluation of RA.Methods Sixteen healthy Sprague Dawley （SD） rats about 8-week old were randomly assigned to a RA group and a control group.Bovine type Ⅱ emulsified incomplete Freud＇s adjuvant was used to induce arthritis in the RA group.Arthritis score of the rats in two groups were recorded,and 18F-FDG PET/CT,MR imaging were performed both on the corresponding rats every 3 days.All the rats were sacrificed at week 5,and histopathological examination was performed on rat knees stained with haematoxylin and eosin.Results The arthritis score and the standard uptake value （SUV） of knee joints in RA rats increased with the progression of arthritis gradually.Both peaks of arthritis score and SUV appeared at 21 days after the first immune injection,then the arthritis score and SUV of knee joints decreased slowly.The arthritis scores of knee joints in RA rats were positively correlated with their SUV changes.The MR images were confirmed by the histopathological studies.Conclusion PET/CT can detect the earliest molecular metabolism changes of RA,and MR imaging can follow up the dynamical anatomical changes of RA,all of which indicated that PET/CT and MR imaging may be applied as useful tools to monitor the progress of RA.

Early evaluation for treatment efficacy of 5-fluorouracil and hyperthermia on HCT-116 colon cancer cells by fluorine-18-fluorodeoxyglucose uptake

Backgroud Fluorine-18-fluorodeoxyglucose （18F-FDG） positron emission tomography imaging can be used to assess the treatment efficacy of chemotherapy and prognosis.The aim of this study was to determine the uptake rate of 18F-FDG in colon cancer HCT-116 cells,and to evaluate the treatment efficacy of chemotherapy,hyperthermia and thermo-chemotherapy through the uptake inhibition rate of 18F-FDG.Methods The uptake rate of 18F-FDG in HCT-116 ceils was determined at various experimental conditions.The inhibition rate of cell growth,uptake rate of 18F-FDG and uptake inhibition rate of l8F-FDG in HCT-116 cells treated with 5-fluorouracil （5-FU） at various concentrations were determined.In HCT-116 cells subjected to chemotherapy （5-FU,100 μg/ml）,hyperthermia （43℃,40 minutes） and thermo-chemotherapy for 24 hours,the inhibition rate of cell growth and uptake inhibition rate of 18F-FDG were determined; early apoptosis,the morphology and ultrastructure of HCT-116 cells were examined; and the contents of glucose and lactate dehydrogenase （LDH） in the cell culture medium of HCT-116 cells were determined.One-way analysis of variance （ANOVA） and correlation analyses were conducted by using SPSS 16.0 software.Results The uptake rate of 18F-FDG in HCT-116 cells was （44.25±2.19）%.Under the condition of adding 5-FU at various concentrations for 24 hours,the uptake rate of 18F-FDG was negatively correlated with 5-FU dosage （r=-0.879,P 〈0.01）; the inhibition rate of cell growth revealed a positive correlation with the uptake inhibition rate of 18F-FDG （r=0.831,P 〈0.01）.In HCT-116 cells subjected to hyperthermia,chemotherapy,and thermo-chemotherapy for 24 hours,the uptake inhibition rates of 18F-FDG were （12.94±2.80）%,（28.25±4.59）%,and （21.60±3.68）%,respectively.The early apoptotic rates of HCT-116 cells were （9.80±0.16）%,（19.80±2.40）%,and （15.70±1.80）%,respectively.Moreover,the contents of glucose and LDH in cell culture medium of HCT-116 cells after treatments were higher than those before treatment.Conclusion The uptake inhibition rate of 18F-FDG can be used for early evaluation of hyperthermia and 5-FU treatment efficacy on cancer cells although hyperthermia （43℃,40 minutes） does not reveal the synergistic effect on 5-FU at the low dosage.

Prognostic value of baseline FDG uptake on PET-CT in esophageal carcinoma

AIM: To evaluate the influence of baseline maximum standardized uptake value(SUVmax) on survival in a cohort of patients, undergoing positron emission tomography-computed tomography(PET-CT) scan for esophageal carcinoma. METHODS: The pre-treatment SUVmax numeric reading was determined in patients with confirmed esophageal or junctional cancer having PET-CT scan during the time period 1st January 2007 until 31 st July 2012. A minimum follow up of 12 mo was required. Patients were subdivided into quartiles according to SUVmax value and the influence of SUVmax on survival was assessed using univariate and multivariate analysis. The following pre-treatment factors were investigated: patient characteristics, tumor characteristics and planned treatment. RESULTS: The study population was 271 patients(191male) with esophageal or junctional carcinoma. The median age was 65 years(range 40-85) and histologic subtype was adenocarcinoma in 197 patients and squamous carcinoma in 74 patients. The treatment intent was radical in 182 and palliative in 89 patients. SUVmax was linked to histologic subtype(P = 0.008), tumor site(P = 0.01) and Union for International Cancer Control(UICC) stage(P < 0.001). On univariate analysis, prognosis was significantly associated with SUVmax(P = 0.001), T-stage(P < 0.001) and UICC stage(P < 0.001). On multivariate analysis, only T-stage and UICC stage remained significant. CONCLUSION: Pretreatment SUVmax was not a useful marker in isolation for determining prognosis of patients with esophageal carcinoma.

Positron emission tomography/computed tomography findings of multiple cystic lymphangiomas in an adult: A case report

BACKGROUND Lymphangioma is a rare benign cystic tumor believed to be a proliferation of heterotopic lymphocytes.It is caused by congenital lymphatic dysplasia or other acquired factors related to surgery,trauma,infection,or cancer.In this article,we present the case of an adult patient who underwent multi-modal imaging and whose condition was finally confirmed to be multiple cystic lymphangiomas by pathological examination.CASE SUMMARY A 61-year-old man was referred to our hospital for having suffered from painless gross hematuria for 2 wk.Multiple masses rising from the retroperitoneum and pelvis were found incidentally by urinary ultrasonography.Contrast-enhanced abdominal-pelvic computed tomography showed multiple well-defined hypodense cystic lesions without enhancement.The lesions showed no uptake on F-18-fluorodeoxyglucose positron emission tomography/computed tomography images.Exploratory laparotomy was performed,and the case was confirmed as multiple cystic lymphangiomas.CONCLUSION When retroperitoneal and pelvic masses are found,clinicians should always consider cystic lymphangioma when making a differential diagnosis.

Differentiating gastric cancer and gastric lymphoma using texture analysis(TA)of positron emission tomography(PET)

Background:Texture analysis(TA)can quantify intra-tumor heterogeneity using standard medical images.The present study aimed to assess the application of positron emission tomography(PET)TA in the differential diagnosis of gastric cancer and gastric lymphoma.Methods:The pre-treatment PET images of 79 patients(45 gastric cancer,34 gastric lymphoma)between January 2013 and February 2018 were retrospectively reviewed.Standard uptake values(SUVs),first-order texture features,and second-order texture features of the grey-level co-occurrence matrix(GLCM)were analyzed.The differences in features among different groups were analyzed by the two-way Mann-Whitney test,and receiver operating characteristic(ROC)analysis was used to estimate the diagnostic efficacy.Results:InertiaGLCM was significantly lower in gastric cancer than that in gastric lymphoma(4975.61 vs.11,425.30,z=-3.238,P=0.001),and it was found to be the most discriminating texture feature in differentiating gastric lymphoma and gastric cancer.The area under the curve(AUC)of inertiaGLCM was higher than the AUCs of SUVmax and SUVmean(0.714 vs.0.649 and 0.666,respectively).SUVmax and SUVmean were significantly lower in low-grade gastric lymphoma than those in high grade gastric lymphoma(3.30 vs.11.80,2.40 vs.7.50,z=-2.792 and-3.007,P=0.005 and 0.003,respectively).SUVs and first-order greylevel intensity features were not significantly different between low-grade gastric lymphoma and gastric cancer.EntropyGLCM12 was significantly lower in low-grade gastric lymphoma than that in gastric cancer(6.95 vs.9.14,z=-2.542,P=0.011)and had an AUC of 0.770 in the ROC analysis of differentiating low-grade gastric lymphoma and gastric cancer.Conclusions:InertiaGLCM and entropyGLCM were the most discriminating features in differentiating gastric lymphoma from gastric cancer and low-grade gastric lymphoma from gastric cancer,respectively.PET TA can improve the differential diagnosis of gastric neoplasms,especially in tumors with similar degrees of fluorodeoxyglucose uptake.