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.

^(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

AIM To compare ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography(^(18)F-FDG PET/CT) features in gastric lymphoma and gastric carcinoma.METHODS Patients with newly diagnosed gastric lymphoma or gastric carcinoma who underwent ^(18)F-FDG PET/CT prior to treatment were included in this study. We reviewed and analyzed the PET/CT features of gastric wall lesions,including FDG avidity,pattern(focal/diffuse),and intensity [maximal standard uptake value:(SUVmax)]. The correlation of SUVmax with gastricclinicopathological variables was investigated by χ~2 test,and receiver-operating characteristic(ROC) curve analysis was performed to determine the differential diagnostic value of SUVmax-associated parameters in gastric lymphoma and gastric carcinoma. RESULTS Fifty-two patients with gastric lymphoma and 73 with gastric carcinoma were included in this study. Abnormal gastric FDG accumulation was found in 49 patients(94.23%) with gastric lymphoma and 65 patients(89.04%) with gastric carcinoma. Gastric lymphoma patients predominantly presented with type Ⅰ and type Ⅱ lesions,whereas gastric carcinoma patients mainly had type Ⅲ lesions. The SUVmax(13.39 ± 9.24 vs 8.35 ± 5.80,P < 0.001) and SUVmax/THKmax(maximal thickness)(7.96 ± 4.02 vs 4.88 ± 3.32,P < 0.001) were both higher in patients with gastric lymphoma compared with gastric carcinoma. ROC curve analysis suggested a better performance of SUVmax/THKmax in the evaluation of gastric lesions between gastric lymphoma and gastric carcinoma in comparison with that of SUVmax alone.CONCLUSION PET/CT features differ between gastric lymphoma and carcinoma,which can improve PET/CT evaluation of gastric wall lesions and help differentiate gastric lymphoma from gastric carcinoma.

Tumor characteristics of ductal carcinoma in situ of breast visualized on [F-18] fluorodeoxyglucose-positron emission tomography/computed tomography: Results from a retrospective study

AIM To clarify clinicopathological features of ductal carcinoma in situ(DCIS) visualized on [F-18] fluorodeoxyglucosepositron emission tomography/computed tomography(FDG-PET/CT).METHODS This study retrospectively reviewed 52 consecutive tumors in 50 patients with pathologically proven pure DCIS who underwent [F-18] FDG-PET/CT before surgery. [F-18] FDG-PET/CT was performed after biopsy in all patients. The mean interval from biopsy to [F-18] FDGPET/CT was 29.2 d. [F-18] FDG uptake by visual analysis and maximum standardized uptake value(SUVmax) was compared with clinicopathological characteristics.RESULTS[F-18] FDG uptake was visualized in 28 lesions(53.8%) and the mean and standard deviation of SUVmax was 1.63 and 0.90. On univariate analysis, visual analysis and the SUVmax were associated with symptomatic presentation(P = 0.012 and 0.002, respectively), palpability(P = 0.030 and 0.024, respectively), use of core-needle biopsy(CNB)(P = 0.023 and 0.012, respectively), ultrasound-guided biopsy(P = 0.040 and 0.006, respectively), enhancing lesion ≥ 20 mm on magnetic resonance imaging(MRI)(P = 0.001 and 0.010, respectively), tumor size ≥ 20 mm on histopathology(P = 0.002 and 0.008, respectively). However, [F-18] FDG uptake parameters were not significantly associated with age, presence of calcification on mammography, mass formation on MRI, presence of comedo necrosis, hormone status(estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2), and nuclear grade. The factors significantly associated with visual analysis and SUVmax were symptomatic presentation(P = 0.019 and 0.001, respectively), use of CNB(P = 0.001 and 0.031, respectively), and enhancing lesion ≥ 20 mm on MRI(P = 0.001 and 0.049, respectively) on multivariate analysis.CONCLUSION Although DCIS of breast is generally non-avid tumor, symptomatic and large tumors(≥ 20 mm) tend to be visualized on [F-18] FDG-PET/CT.

Positron emission tomography/computed tomography with ^(18)F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma

Patients suffering from hepatocellular carcinoma (HCC) with tumor thrombus in the portal vein generally have a poor prognosis. Portal vein tumor thrombus must be distinguished from portal vein blood thrombus, and this identification plays a very important role in management of HCC. Conventional imaging modalities have limitations in discrimination of portal vein tumor thrombus. The application of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for discrimination between tumor extension and blood thrombus has been reported in few cases of HCC, while portal tumor thrombosis and portal vein clot identified by 18F-FDG PET/CT in HCC patients has not been reported so far. We present two HCC cases, one with portal vein tumor thrombus and one thrombosis who were identified with 18F-FDG PET/CT. This report illustrates the complimentary value of combining the morphological and functional imaging in achieving a correct diagnosis in such clinical situations.

Comparisons between glucose analogue 2-deoxy-2-(^(18)F)fluoro-D-glucose and ^(18)F-sodium fluoride positron emission tomography/computed tomography in breast cancer patients with bone lesions

AIM: To compare 2-deoxy-2-(18F)fluoro-D-glucose(18F-FDG) and 18F-sodium (18F-NaF) positron emission tomography/computed tomography (PET/CT) accuracy in breast cancer patients with clinically/radiologically suspected or known bone metastases.METHODS: A total of 45 consecutive patients with breast cancer and the presence or clinical/biochemical or radiological suspicion of bone metastatic disease underwent 18F-FDG and 18F-fluoride PET/CT. Imaging results were compared with histopathology when available, or clinical and radiological follow-up of at least 1 year. For each technique we calculated: Sensitivity (Se), specificity (Sp), overall accuracy, positive and negative predictive values, error rate, and Youden’s index. McNemar’s χ2 test was used to test the difference in sensitivity and specificity between the two diagnostic methods. All analyses were computed on a patient basis, and then on a lesion basis, with consideration ofthe density of independent lesions on the co-registered CT (sclerotic, lytic, mixed, no-lesions) and the divergent site of disease (skull, spine, ribs, extremities, pelvis). The impact of adding 18F-NaF PET/CT to the work-up of patients was also measured in terms of change in their management due to 18F-NaF PET/CT findings.RESULTS: The two imaging methods of 18F-FDG and 18F-fluoride PET/CT were significantly different at the patient-based analysis: Accuracy was 86.7% and 84.4%, respectively (McNemar’s χ2 = 6.23, df = 1, P = 0.01). Overall, 244 bone lesions were detected in our analysis. The overall accuracy of the two methods was significantly different at lesion-based analysis (McNemar’s χ2 = 93.4, df = 1, P < 0.0001). In the lesion density-based and site-based analysis, 18F-FDG PET/CT provided more accurate results in the detection of CT-negative metastasis (P < 0.002) and vertebral localizations (P < 0.002); 18F-NaF PET/CT was more accurate in detecting sclerotic (P < 0.005) and rib lesions (P < 0.04). 18F-NaF PET/CT led to a change of management in 3 of the 45 patients (6.6%) by revealing findings that were not detected at 18F-FDG PET/CT.CONCLUSION: 18F-FDG PET/CT is a reliable imaging tool in the detection of bone metastasis in most cases, with a diagnostic accuracy that is slightly, but significantly, superior to that of 18F-NaF PET/CT in the general population of breast cancer patients. However, the extremely high sensitivity of 18F-fluoride PET/CT can exploit its diagnostic potential in specific clinical settings (i.e., small CT-evident sclerotic lesions, high clinical suspicious of relapse, and negative 18F-FDG PET and conventional imaging).

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.

2-deoxy-2-(^(18)F)fluoro-D-glucose positron emission tomography/computed tomography imaging in paediatric oncology

Positron emission tomography(PET) is a minimally in-vasive technique which has been well validated for the diagnosis, staging, monitoring of response to therapy, and disease surveillance of adult oncology patients. Tra-ditionally the value of PET and PET/computed tomogra-phy(CT) hybrid imaging has been less clearly defined for paediatric oncology. However recent evidence has emerged regarding the diagnostic utility of these mo-dalities, and they are becoming increasingly important tools in the evaluation and monitoring of children with known or suspected malignant disease. Important indi-cations for 2-deoxy-2-(18F)fluoro-D-glucose(FDG) PET in paediatric oncology include lymphoma, brain tumours, sarcoma, neuroblastoma, Langerhans cell histiocytosis, urogenital tumours and neurofibromatosis type Ⅰ. This article aims to review current evidence for the use of FDG PET and PET/CT in these indications. Attention will also be given to technical and logistical issues, the description of common imaging pitfalls, and dosimetric concerns as they relate to paediatric oncology.

Preoperative [18]fluorodeoxyglucose-positron emission tomography/computed tomography in early stage breast cancer: Rates of distant metastases

AIM To investigate rates of distant metastases(DM) detected with [18]fluorodeoxyglucose-positron emissiontomography/computed tomography(^(18)FDG-PET/CT) in early stage invasive breast cancer.METHODS We searched the English language literature databases of PubM ed, EMBASE, ISI Web of Knowledge, Web of Science and Google Scholar, for publications on DM detected in patients who had ^(18)FDG-PET/CT scans as part of the staging for early stages of breast cancer(stage Ⅰ?and Ⅱ), prior to or immediately following surgery. Reports published between 2011 and 2017 were considered. The systematic review was conducted according to the PRISMA guidelines.RESULTS Among the 18 total studies included in the analysis, the risk of DM ranged from 0% to 8.3% and 0% to 12.9% for stage Ⅰ?and Ⅱ invasive breast cancer, respectively. Among the patients with clinical stage Ⅱ, the rate of occult metastases diagnosed by ^(18)FDG-PET/CT was 7.2%(range, 0%-19.6%) for stage ⅡA and 15.8%(range, 0%-40.8%) for stage ⅡB. In young patients(< 40-yearold), ^(18)FDG-PET/CT demonstrated a higher prevalence of DM at the time of diagnosis for those with aggressive histology(i.e., triple-negative receptors and poorly differentiated grade).CONCLUSION Young patients with poorly differentiated tumors and stage ⅡB triple-negative breast cancer may benefit from ^(18)FDG-PET/CT at initial staging to detect occult DM prior to surgery.

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.

Congenital hyperinsulinism:Role of fluorine-18L-3, 4 hydroxyphenylalanine positron emission tomography scanning

Congenital hyperinsulinism(CHI) is a rare but complex heterogeneous disorder caused by unregulated secre-tion of insulin from the β-cells of the pancreas leading to severe hypoglycaemia and neuroglycopaenia. Swift diagnosis and institution of appropriate management is crucial to prevent or minimise adverse neurodevel-opmental outcome in children with CHI. Histologically there are two major subtypes of CHI, diffuse and focal disease and the management approach will significantly differ depending on the type of the lesion. Patients with medically unresponsive diffuse disease require a near total pancreatectomy, which then leads on to the de-velopment of iatrogenic diabetes mellitus and pancre-atic exocrine insufficiency. However patients with focaldisease only require a limited pancreatectomy to re-move only the focal lesion thus providing complete cure to the patient. Hence the preoperative differentiation of the histological subtypes of CHI becomes paramount in the management of CHI. Fluorine-18L-3, 4-hydroxy-phenylalanine positron emission tomography(18F-DOPA-PET) is now the gold standard for pre-operative differentiation of focal from diffuse disease and locali-sation of the focal lesion. The aim of this review article is to give a clinical overview of CHI, then review the role of dopamine in β-cell physiology and finally discuss the role of 18F-DOPA-PET imaging in the management of CHI.

Cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography in tumours other than lung cancer: A systematic review

AIM: To systematically review published data on the cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography(FDG-PET) or PET/computed tomography(PET/CT) in tumours other than lung cancer. METHODS: A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus and Embase databases through the 10th of October in 2013 was carried out. A search algorithm based on a combination of the terms:(1) "PET" or " PET/computed tomography(PET/CT)" or "positron emission tomography"; and(2) "cost-effectiveness" or "cost-utility" or "cost-efficacy" or "technology assessment" or "health technology assessment" was used. Only cost-effectiveness or cost-utility analyses in English language were included. Exclusion criteria were:(1) articles not within the field of interest of this review;(2) review articles, editorials or letters, conference proceedings; and(3) outcome evaluation studies, cost studies or health technology assessment reports. For each included study, information was col-lected concerning basic study, type of tumours evaluated, perspective/type of study, results, unit and comparison alternatives. RESULTS: Sixteen studies were included. Head and neck tumours were evaluated in 4 articles, lymphoma in 4, colon-rectum tumours in 3 and breast tumours in 2. Only one article was retrieved for melanoma, oesophagus and ovary tumours. Cost-effectiveness results of FDG-PET or PET/CT ranged from dominated to dominant. CONCLUSION: Literature evidence about the costeffectiveness of FDG-PET or PET/CT in tumours other than lung cancer is still limited. Nevertheless, FDGPET or PET/CT seems to be cost-effective in selective indications in oncology(staging and restaging of head and neck tumours, staging and treatment evaluation in lymphoma).

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.

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.

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.

Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography for Osteochondromas Utilizing a Triple-Time Point Protocol

Purpose: The purpose of this study was to assess solitary osteochondroma and hereditary multiple osteochondral exostoses (HMOCE) utilizing FDG PET and a triple time point protocol. Methods: Seven patients were consented and recruited for PET evaluation of presumed benign osteochondroma. Following injection of 15 mCi of FDG, the lesion(s) of interest was imaged with PET-CT at 45 minutes post injection, whole body at 50 minutes post, and lesion of interest at 95 minutes post injection. A maximum standardized uptake value (SUVmax) was obtained for the lesion(s) of interest at each time point, and an SUVΔ was calculated for each lesion of interest from the first time point to the third time point. Results: 16 lesions from 7 patients were included in the study. Mean SUVmax for all 3 time points was 1.04 with a standard deviation of 0.50 (range 0.3 - 2.2). The mean SUV was 0.096 with a range of 0 - 0.4. Among the 3 patients with histologically confirmed osteochondromas, mean SUVmax was 0.67, with standard deviation of 0.23 and range of 0.3 to 1.0. The mean SUVΔ13 was 0.081 (range 0 - 0.4), mean SUVΔ12 was 0.10 (0 - 0.3), and mean SUVΔ23 was 0.11 (range 0 - 0.4) (p = 0.74). Conclusion: Benign lesions were found to not have progressively increasing uptake on multiple time point FDG PET. Until chondrosarcomas are evaluated using triple time point 18FDG PET, its applicability in the evaluation of osteochondroma versus malignant change remains uncertain.

Prognostic value of pre-and post-transplantation 18F-fluorodeoxyglucose positron emission tomography results in non-Hodgkin lymphoma patients receiving autologous stem cell transplantation

Objective： High-dose chemotherapy （HDC） followed by autologous stem cell transplantation （ASCT） is the standard of care in the upfront or relapsed/refractory setting in some patients with non-Hodgkin lymphoma （NHL）. However, a proportion of patients do not respond to ASCT. lSF-fluorodeoxyglueose （FDG） positron emission tomography （PET）/computed tomography （CT） has been widely used for staging, response evaluation, and prognosis prediction. Here, we investigated the prognostic role of PET/CT in NHL patients before and after ASCT. Methods： A retrospective study was conducted at Peking University Cancer Hospital. All NHL patients who underwent ASCT between March 2010 and July 2016 were identified. Patients who had PET/CT scan before and after ASCT were included. Deauville criteria （5-point scale） were used to interpret PET scans. Univariate and multivariate survival analyses were performed using Cox regression. The predictive value of PET scanning was estimated by comparing the area under the receiver operating characteristic （ROC） curve. Results： In total, 79 patients were enrolled in this study. In univariate analysis, pre- and post-ASCT PET result was identified as prognostic factors for 3-year progression-free survival （PFS） and overall survival （OS）. Patients with negative pre-ASCT PET result demonstrated significantly better PFS （84.2% vs. 54.2%） and OS （89.2% vs. 63.6%） than patients with positive pre-ASCT PET result. PFS （91.6% vs. 25.3%） and OS （96.5% vs. 36.8%） were also significantly different between patients with negative and positive post-ASCT PET result. Multivariate analysis also showed a significant association between survival and post-ASCT PET result. ROC analysis revealed that the predictive value of post-ASCT PET result was superior to that of pre-ASCT PET result alone. Combined pre- and post-ASCT PET result is better for predicting outcomes in patients with NHL receiving transplantation. Deauville criteria score 〉3 was identified as the best cutoffvalue for post-ASCT PET. Conclusions： Post-ASCT PET result was more important than pre-ASCT PET result in predicting outcomes for NHL patients who underwent ASCT. The prognostic significance can be improved when combining pre- ASCT PET result with post-ASCT PET result. Deauville criteria can be used for interpreting PET scans in this scenario.

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.

Evaluation of response to immune checkpoint inhibitors: Is there a role for positron emission tomography?

Strategies targeting intracellular negative regulators such as immune checkpoint inhibitors (ICPIs) have demonstrated significant antitumor activity across a wide range of solid tumors. In the clinical practice, the radiological effect of immunotherapeutic agents has raised several more relevant and complex challenges for the determination of their imaging-based response at single patient level. Accordingly, it has been suggested that the conventional Response Evaluation Criteria in Solid Tumors assessment alone, based on dimensional evaluation provided by computed tomography (CT), tends to underestimate the benefit of ICPIs at least in a subset of patients, supporting the need of immune-related response criteria. Different from CT, very few data are available for the evaluation of immunotherapy by means of 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET). Moreover, since the antineoplastic activity of ICPIs is highly related to the activation of T cells against cancer cells, FDG accumulation might cause false-positive findings. Yet, discrimination between benign and malignant processes represents a huge challenge for FDG-PET in this clinical setting. Consequently, it might be of high interest to test the complex and variegated response to ICPIs by means of PET and thus it is worthwhile to ask if a similar introduction of immune-related PET-based criteria could be proposed in the future. Finally, PET might offer a new insight into the biology and pathophysiology of ICPIs thanks to a growing number of non-invasive immune-diagnostic approaches based on non-FDG tracers.

^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography in intrahepatic cholangiocarcinoma: could it be a new paradigm?

Intrahepatic cholangiocarcinoma(iCCA)is the second most common type of liver cancer after hepatocellular carcinoma,accounting for 15%of all primary liver neoplasms.In particular,iCCA is the most lethal tumor of these types,with the greatest increase in incidence in Western countries over the last decade(1,2).Local resection is the only treatment that can achieve cure,but resection rates remain low and survival is still limited to less than 1 year in the presence of locally unresectable or distant metastases(3).Its incidence and mortality have increased in recent years,and the total number of new cases is expected to increase up to 10-fold over the next two to three decades.In recent years,new treatments for iCCA have been developed and overall survival has improved.

[^18F]2-fluoro-2-deoxyglucose positron emission tomography/ computed tomography in predicting radiation pneumonitis

Background Prevention is presently the only available method to limit radiation-induced lung morbidity. A good predictor is the key point of prevention. This study aimed to investigate if [^18F]2-fluoro-2-deoxyglucose （FDG） uptake changes in the lung after radiotherapy could be used as a new predictor for acute radiation pneumonitis （RP）. Methods Forty-one patients with lung cancer underwent FDG positron emission tomography/computed tomography （FDG-PET/CT） imaging before and after radiotherapy. The mean standardized uptake value （SUV） was measured for the isodose regions of 0-9 Gy, 10-19 Gy, 20-29 Gy, 30-39 Gy, 40-49 Gy. The mean SUV of these regions after radiotherapy was compared with baseline. The mean SUV in patients who developed RP was also compared with that in those who did not. The statistical difference was determined by matched pair t test. The Radiation Therapy Oncology Group （RTOG） criteria were used for diagnosis and grading of RP. Results With a median follow-up of 12 months, 11 （26.8%） of the 41 patients developed grade 2 and above acute RP. The mean SUV of regions （10-19 Gy, 20-29 Gy, 30-39 Gy, 40-49 Gy） increased after radiation therapy in all 41 patients. The mean SUVs after radiation therapy were 0.54, 0.68, 1.31, 1.74 and 2.27 for 0-9 Gy, 10-19 Gy, 20-29 Gy, 30-39 Gy and 40-49 Gy, respectively. Before the radiation therapy, the mean SUV in each region was 0.53, 0.52, 0.52, 0.53 and 0.54, respectively. These patients had significantly higher FDG activities in regions receiving 10 Gy or more （P 〈0.001）. Compared with their counterparts, the elevation of SUV was significantly greater in those patients who developed acute RP subsequently. Conclusion The mean SUV of the lung tissue may be a useful predictor for the acute RP. FDG-PET/CT may play a new role in the study of the radiation damage of the lung.