Focal incidental colorectal fluorodeoxyglucose uptake:Should it be spotlighted?

Fluorine-18 fluorodeoxyglucose(F-18 FDG)positron emission tomography/computed tomography(PET/CT)has emerged as a cornerstone in cancer evaluation imaging,with a well-established history spanning several years.This imaging modality,encompassing the examination of the body from the base of the skull to the upper thighs,comprehensively covers the chest and abdominopelvic regions in a singular scan,allowing for a holistic assessment of nearly the entire body,including areas of marginal interest.The inherent advantage of this expansive scan range lies in its potential to unveil unexpected incidental abnormal hypermetabolic areas.The identification of incidental focal FDG uptake within colorectal regions during PET/CT scans is not an uncommon occurrence,albeit fraught with challenges associated with non-specific FDG uptake.The presence of benign colorectal lesions or physiological uptake poses a particular obstacle,as these may manifest with FDG uptake levels that mimic malignancy.Consequently,physicians are confronted with a diagnostic dilemma when encountering abnormal FDG uptake in unexpected colorectal areas.Existing studies have presented divergent results concerning these uptakes.Standardized uptake value and its derivatives have served as pivotal metrics in quantifying FDG uptake in PET images.In this article,we aim to succinctly explore the distinctive characteristics of FDG,delve into imaging findings,and elucidate the clinical significance of incidental focal colorectal uptake.This discussion aims to contribute valuable insights into the nuanced interpretation of such findings,fostering a comprehensive understanding.

A Quasi-Experimental Study of English Vocabulary Teaching Based on Incidental Acquisition

Recent years have witnessed a phenomenon that major English teachers in China have adopted the traditional teaching pattern, mechanically linking English pronunciations directly with the meaning of Chinese, which gradually dampens learners’ enthusiasm. The chief purpose of this paper was to design one English vocabulary teaching lesson based on incidental acquisition. More specifically, the questions raised are, on the one hand, whether incidental vocabulary teaching imprints differences on the learning outcomes for middle school students, and, on the other hand, whether incidental acquisition results in positive feedback between teachers and students. The technique we applied was referred to as questionnaires and interviews addressed to a sample of 68 students. Focusing on the effect of incidental vocabulary acquisition, the analysis demonstrated that it could enhance students’ vocabulary capacity. In addition, it was interesting to note that excellent students and average students tended to embrace the new teaching style while underachievers were on the opposite side. On this basis, it is recommended for English teachers to design English vocabulary lessons, adopting visual, auditory, oral, reading or writing training. More precisely, they should use phonics rules and patterns, holistic learning, classified vocabulary teaching, visual illustration or multimedia teaching to give lessons effectively and expand learners’ vocabulary.

Incidental gallbladder cancer diagnosis confers survival advantage irrespective of tumour stage and characteristics

BACKGROUND Incidental gallbladder cancer(IGBC)represents 50%-60%of gallbladder cancer cases.Data are conflicting on the role of IGBC diagnosis in oncological outcomes.Some studies suggest that IGBC diagnosis does not affect outcomes,while others that overall survival(OS)is longer in these cases compared to non-incidental diagnosis(NIGBC).Furthermore,some studies reported early tumour stages and histopathologic characteristics as possible confounders,while others not.AIM To investigate the role of IGBC diagnosis on patients’overall survival,especially after surgical treatment with curative intent.METHODS Retrospective analysis of all patient referrals with gallbladder cancer between 2008 and 2020 in a tertiary hepatobiliary centre.Statistical comparison of patient and tumour characteristics between IGBC and NIGBC subgroups was performed.Survival analysis for the whole cohort,surgical and non-surgical subgroups was done with the Kaplan-Meier method and the use of log rank test.Risk analysis was performed with univariable and multivariable Cox regression analysis.RESULTS The cohort included 261 patients with gallbladder cancer.65%of cases had NIGBC and 35%had IGBC.A total of 90 patients received surgical treatment(66%of IGBC cases and 19%of NIGBC cases).NIGBC patients had more advanced T stage and required more extensive resections than IGBC ones.OS was longer in patients with IGBC in the whole cohort(29 vs 4 mo,P<0.001),as well as in the non-surgical(14 vs 2 mo,P<0.001)and surgical subgroups(29 vs 16.5 mo,P=0.001).Disease free survival(DFS)after surgery was longer in patients with IGBC(21.5 mo vs 8.5 mo,P=0.007).N stage and resection margin status were identified as independent predictors of OS and DFS.NIGBC diagnosis was identified as an independent predictor of OS.CONCLUSION IGBC diagnosis may confer a survival advantage independently of the pathological stage and tumour characteristics.Prospective studies are required to further investigate this,including detailed pathological analysis and molecular gene expression.

Prevalence of incidental prostate cancer in patients undergoing radical cystoprostatectomy： data from China and other Asian countries

The purpose of this study is to investigate the frequency of prostate cancer （Pca） discovered incidentally in radical cystoprostatectomy specimens in Asia and to determine the feasibility of prostate-sparing cystectomy （PSC） for Asian patients. Ninety-two male bladder cancer patients who underwent radical cystoprostatectomy at our center between January 2003 and January 2008 were included in this study. The mean age of patients was 67.1 years （range： 32-75 years）. Prostate-specific antigen （PSA） levels and digital rectal examination （DRE） results before surgery were obtained retrospectively. Prostates of all patients were embedded and sectioned at 5-mm intervals. The same pathologist examined the prostatic tissues from radical cystoprostatectomy specimens. Finally, a structured literature review was performed using MEDLINE and PUBMED to estimate the occurrence of incidental Pca in Asia. Of the 92 patients, 3 （3.3%） were found to have Pca; in one out of three （33.3%） patients the disease was clinically significant due to a Gleason grade 4 carcinoma. Eight articles were included in our review. The overall incidence of Pca discovered incidentally in radical cystoprostatectomy specimens in Asia was 9.9% （64/642）. When age was restricted to 〈 60 years, only 7 out of 222 （3.2%） patients were found to have synchronous Pca, and none of the cases was clinically significant. The occurrence of Pca in radical cystoprostatectorny specimens in Asia is much lower than that in Western countries. PSC might be feasible for Asian patients under a strict preoperative selection.

Incidental gall bladder cancers:Are they truly incidental?

AIM: To seek and analyze features suggestive of gallbladder cancer(GBC) on preoperative imaging and intraoperative findings in patients diagnosed as having incidental GBC(IGBC). METHODS: The study was conducted on 79 patients of IGBC managed in our department over a 10-year period(2003-2012). Review of preoperative imaging and operative notes was done to ascertain any suspicion of malignancy-in-retrospect.RESULTS: Of the 79 patients, Ultrasound abdomen showed diffuse thickening, not suspicious of malignancy in 5 patients, and diffuse suspicious thickening was seen in 4 patients. Focal thickening suspicious of malignancy was present in 24 patients. Preoperative computed tomography/magnetic resonance imaging was done in 9 patients for suspicion of malignancy. In 5 patients, dif-ficult Cholecystectomy was encountered due to dense/inflammatory adhesions. Intraoperative findings showed focal thickening of the gallbladder and a gallbladder mass in 9 and 17 patients respectively. On overall analysis, 37 patients had preoperative imaging or intraoperative findings suggestive of malignancy, which was either a missed GBC or an unsuspected/unexpected GBC. In 42(53.2%) patients, there was no evidence suggestive of malignancy and was an unanticipated diagnosis.CONCLUSION: Our study highlights a potential and not-so-rare pitfall of Laparoscopic Cholecystectomy. A greater awareness of this clinical entity along with a high index of suspicion and a low threshold for conversion to open procedure, especially in endemic areas may avert avoidable patient morbidity and mortality.

Incidental non-benign gallbladder histopathology after cholecystectomy in an United Kingdom population: Need for routine histological analysis?

AIM To analyse the range of histopathology detected in the largest published United Kingdom series of cholecystectomy specimens and to evaluate the rational for selective histopathological analysis.METHODS Incidental gallbladder malignancy is rare in the United Kingdom with recent literature supporting selective histological assessment of gallbladders after routine cholecystectomy.All cholecystectomy gallbladder specimens examined by the histopathology department at our hospital during a five year period between March 2008 and March 2013 were retrospectively analysed.Further data was collected on all specimens demonstrating carcinoma,dysplasia and polypoid growths.RESULTS The study included 4027 patients.The majority(97%) of specimens exhibited gallstone or cholecystitis related disease.Polyps were demonstrated in 44(1.09%),the majority of which were cholesterol based(41/44).Dysplasia,ranging from low to multifocal high-grade was demonstrated in 55(1.37%).Incidental primary gallbladder adenocarcinoma was detected in 6 specimens(0.15%,5 female and 1 male),and a single gallbladder revealed carcinoma in situ(0.02%).This large single centre study demonstrated a full range of gallbladder disease from cholecystectomy specimens,including more than 1% neoplastic histology and two cases of macroscopically occult gallbladder malignancies.CONCLUSION Routine histological evaluation of all elective and emergency cholecystectomies is justified in a United Kingdom population as selective analysis has potential to miss potentially curable life threatening pathology.

Incidental prostate cancer in radical cystoprostatectomy specimens

Aim： To investigate the rates of prostate cancer （PCa） in radical cystoprostatectomy （RCP） specimens for bladder cancer in China's Mainland. To determine the follow-up outcome of patients with two concurrent cancers and identify whether prostate-specific antigen （PSA） is a useful tool for the detection of PCa prior to surgery. Methods： From January 2002 to January 2007, 264 male patients with bladder cancer underwent RCP at our center. All patients underwent digital rectal examination （DRE） and B ultrasound. Serum PSA levels were tested in 168 patients. None of the patients had any evidence of PCa before RCP. Entire prostates were embedded and sectioned at 5 mm intervals. Results： Incidental PCa was observed in 37 of 264 （14.0%） RCP specimens. Of these, 12 （32.4%） were clinically significant according to an accepted definition. The PSA levels were not significantly different between patients with PCa and those without PCa, nor between patients with significant PCa and those with insignificant PCa. Thirty-four patients with incidental PCa were followed up. During a mean follow-up period of 26 months, two patients with PSA 〉 4 ng/mL underwent castration. None of the patients died of PCa. Conclusion： The incidence of PCa in RCP specimens in China's Mainland is lower than that in most developed countries. PSA cannot identify asymptomatic PCa prior to RCP. In line with published reports, incidental PCa does not impact the prognosis of bladder cancer patients undergoing RCE

Predictors of incidental gallbladder cancer in elderly patients

BACKGROUND： At the time of diagnosis, most patients with gallbladder cancer are in advanced stage and the cancer is unresectable. Long-term survivors are usually seen in a small number of patients with incidental gallbladder cancer. This study aimed to identify preoperative predictors of incidental gallbladder cancer in elderly patients.METHODS： A total of 4014 patients of more than 44 years old who had undergone cholecystectomy at our department from January 2000 to December 2010 were retrospectively reviewed Univariate and multivariate modalities were used to identify the predictive factors of incidental gallbladder cancer.RESULTS： Twenty-nine of the 4014 patients who had under gone cholecystectomy for benign gallbladder diseases were histologically diagnosed as having incidental gallbladder can cer. Multivariate analysis identified that elevated carbohydrate antigen 19-9 combined with carcinoembryonic antigen and/or carbohydrate antigen 125 （P=0.045）, a gallbladder polyp greater than or equal to 1.2 cm （P=0.043） and focal gallblad der wall thickening of more than or equal to 5 mm （P=0.002）were predictive factors of incidental gallbladder cancer.CONCLUSION： Cholecystectomy is suggested for patients with these predictive factors and intraoperative frozen section should be considered to rule out carcinoma.

Incidental adenocarcinoma in patients undergoing surgery for stricturing Crohn's disease

AIM To evaluate frequency and clinical course of incidental adenocarcinoma in patients with stricturing Crohn's disease(CD).METHODS In this study, consecutive patients, who were operated on for stricturing CD between 1997-2012, were included at an academic tertiary referral center. Demographic data and clinical course were obtained by an institutional database and individual chart review. Besides baseline characteristics, intraoperative findings and CD related history were also recorded. Colorectal cancer was classified and staged according to the Union for International Cancer Control(UICC).RESULTS During the study period 484 patients underwent resections due to stricturing CD. Incidental adenocarcinoma was histologically confirmed in 6(1.2%) patients(4 males, 2 females). Patients diagnosed with colorectal cancer had a median age of 43(27-66)years and a median history of CD of 16(7-36) years. Malignant lesions were found in the rectum(n = 4, 66.7%), descending colon(n = 1, 16.7%) and ileocolon(n = 1, 16.7%). According to the UICC classification two patients were stages as?Ⅰ(33.3%), whereas the other patients were classified as stage ⅡA(16.7%), stage ⅢB(16.7%), stage ⅢC(16.7%) and stage Ⅳ(16.7%), respectively. After a median follow-up of 2(0.03-8) years only 1 patient is still alive.CONCLUSION The frequency of incidental colorectal cancer in patients, who undergo surgery for stenotic CD, is low but associated with poor prognosis. However, surgeons need to be aware about the possibility of malignancy in stricturing CD, especially if localized in the rectum.

Clues to predict incidental gallbladder cancer

Background: Consequences of incidental gallbladder cancer(iGBC) following cholecystectomy may include repeat operation(depending on T stage) and worse survival(if bile spillage occurred), both avoidable if iGBC were suspected preoperatively.Methods: A retrospective single-institution review was done. Ultrasound images for cases and controls were blindly reviewed by a radiologist. Chi-square and Student’s t tests, as well as logistic regression and Kaplan–Meier analyses were used. A P ≤ 0.01 was considered significant.Results: Among 5796 cholecystectomies performed 2000–2013, 26(0.45%) were iGBC cases. These patients were older(75.61 versus 52.27 years), had more laparoscopic-to-open conversions(23.1% versus3.9%), underwent more imaging tests, had larger common bile duct diameter(7.13 versus 5.04 mm) and higher alkaline phosphatase. Ultrasound imaging showed that gallbladder wall thickening(GBWT) without pericholecystic fluid(PCCF), but not focal-versus-diffuse GBWT, was associated significantly with iGBC(73.9% versus 47.4%). On multivariable logistic regression analysis, GBWT without PCCF, and age were the strongest predictors of iGBC. The consequences iGBC depended significantly on intraoperative bile spillage, with nearly all such patients developing carcinomatosis and significantly worse survival.Conclusions: Besides age, GBWT, dilated common bile duct, and elevated alkaline phosphatase, number of preoperative imaging modalities and the presence of GBWT without PCCF are useful predictors of iGBC.Bile spillage causes poor survival in patients with iGBC.

Neuroendocrine tumor incidentally detected during living donor hepatectomy: A case report and review of literature

To our best knowledge, no case of a tumor that was incidentally detected during living donor hepatectomy(LDH) has been reported in the English language medical literature. We present two cases in which grade Ⅰ neuroendocrine tumors(NET) were incidentally detected during our twelve-year LDH experience. First Case: A 26-yearold male underwent LDH for his brother suffering from HBV-related chronic liver disease(CLD). After right lobe LDH, intestinal length was measured as part of a study concerning the relationship between small intestinal lengths and surgical procedure. At this stage, a mass lesion with a size of 10 mm × 10 mm was detected on the antimesenteric surface, approximately 90 cm proximal to the ileocecal valve. A wedge resection with primary intestinal anastomosis was performed. Second Case: A 29-year-old male underwent right lobe LDH for his father with hepatitis B virus(HBV)-related CLD. An abdominal exploration immediately prior to the closure of the incision revealed that the appendix vermiformis was edematous and had firmness with a size of 8-10 mm at its tip. An appendectomy was performed. The pathological examinations of the specimens of both patients revealedgrade 1 NET. In conclusion, even if patients undergoing LDH are healthy individuals, whole abdominal cavity should be gently palpated and all findings recorded after completing laparotomy. Suspected masses or lesions should be confirmed by frozen section examination. Such an approach would avert potential medicolegal issues.

Incidental findings at MRI-enterography in patients with suspected or known Crohn's disease

AIM:To determine the frequency and clinical impact of incidental findings detected with magnetic resonance imaging(MRI)-enterography in patients with suspected or known Crohn's disease(CD). METHODS:Incidental findings were defined as unexpected lesions outside the small intestine,not previously known or suspected at the time of referral, and not related to inflammatory bowel disease.Through a systematic review of medical charts we analyzed the clinical impact of incidental findings,and compared the MRI findings with subsequent diagnostic procedures. RESULTS:A total of 283 patients were included in the analysis,and MRI detected active CD in 31%,fistula in 1.4%and abscess in 0.7%.Extra-intestinal findings notrelated to CD were recorded in 72 patients(25%),of which 58 patients(20%)had 74 previously unknown lesions.Important or incompletely characterized findings were detected in 17 patients(6.0%).Incidental findings led to 12 further interventions in 9 patients(3.2%) revealing previously unknown pathological conditions in 5(1.8%).One patient(0.4%)underwent surgery and one patient was diagnosed with a malignant disease. MRI detected incidental colonic lesions in 16 patients of which additional work-up in 4 revealed normal anatomy. Two patients(0.7%)benefitted from the additional examinations,whereas incidental findings led to unnecessary examinations in 9(3.2%). CONCLUSION:In a minority of patients with suspected or known CD,important incidental findings are diagnosed at MRI-enterography.However,a substantial number of patients experience unnecessary morbidity because of additional examinations of benign or normal conditions.

Comparison of clinical and histopathological features of patients who underwent incidental or emergency appendectomy

BACKGROUND Incidental appendectomy can be defined as the removal of a clinically normal appendix during another surgical procedure unrelated to appendicitis or other appendicular diseases.AIM To compare the demographic, biochemical, and histopathological features of the patients who underwent incidental and standard appendectomy.METHODS The demographic, biochemical, and histopathological data of 72 patients(Incidental App group) who underwent incidental appendectomy during living donor hepatectomy at our Liver Transplant Center between June 2009 and December 2016 were compared with data of 288 patients(Acute App group) who underwent appendectomy for presumed acute appendicitis. The Incidental App group was matched at random in a 1:4 ratio with the Acute App group in the same time frame. Appendectomy specimens of both groups were re-evaluated by two experienced pathologists.RESULTS Statistically significant differences were found between groups in terms of age(P= 0.044), white blood cell count(P < 0.001), neutrophil(P < 0.001), lymphocyte(P< 0.001), red cell distribution width(P = 0.036), mean corpuscular hemoglobin(P= 0.001), bilirubin(P = 0.002), appendix width(P < 0.001), and presence of acute appendicitis histopathologically(P < 0.001). However, no statistically significant differences were found between groups in terms of gender, platelet, mean platelet volume, mean corpuscular volume, platelet distribution width, appendix length. While the most common histopathological findings in the Incidental App group were normal appendix vermiformis(72.2%), fibrous obliteration(9.7%)and acute appendicitis(6.9%), the most common histopathological findings in the Acute App group were non-perforated acute appendicitis(62.8%), perforated appendicitis(16.7%), lymphoid hyperplasia(8.3%), and appendix vermiformis(6.3%).CONCLUSION Careful inspection of the entire abdominal cavity is useful for patients undergoing major abdominal surgery such as donor hepatectomy. We think that experience is parallel to the surgeon's foresight, and we should not hesitate to perform incidental appendectomy when

Mental Lexicon Study and Its Enlightening to Incidental Vocabulary Acquisition of L2

The theories of mental lexicon explain how words are organized and accessed in human brain from the angle of psycho linguistics. It draws great interest to study on the field of psycholinguistics and SLA. This paper focuses on incidental vocabulary acquisition of L2 and explores how to assist learners to reinforce and expand their network of mental lexicon by applying all kinds of mental connection in order to promote the learners to acquire English vocabulary.

Effects of Glosses and Involvement Loads on Incidental Vocabulary Acquisition

The present study aims at exploring the effects of different glosses and involvement loads on incidental vocabulary acquisition among non-English majors.It investigates whether glosses and involvement load would have an effect on the learners’immediate word gain and promote their word knowledge retention.The experiment chooses 96 non-English freshmen at a university in Si Chuan Province.Results indicate that Translation task with multiple-choice glosses is the most effective,and reading comprehension task with single glosses is the worst.

Incidental echocardiographic finding:Fractured inferior vena cava filter

Inferior vena cava filters have gained increasing popularity in recent decades and knowledge on rare complications becomes vital to practicing physicians. A 30-year-old African American male with diabetes mellitus, hypertension, end-stage renal disease, history of deep venous thrombosis and placement of venacaval filter who was seen in the cardiology clinic for cardiac risks stratification prior to renal transplant. Patient denied any cardiac symptoms. A transthoracic echocardiogram was performed and showed two linear echoes bright densities in the right atrium and right ventricle embedded which was later found to be fractured filter struts by computed tomography. We discuss the various outcomes associated with nonretrieval of retrievable inferior vena cava filters.

Incidental meandering right pulmonary vein,literature review and proposed nomenclature revision

We report a case of an anomalous pulmonary vein on chest X-ray resembling a scimitar sign in an 80-year-old female undergoing investigation of syncope.Multislice computed tomography(CT) with multiplanar reformatting and maximum intensity projections demonstrated an aberrant right inferior pulmonary vein coursing inferomedially towards the diaphragm before turning superiorly and draining normally into the left atrium.The diagnosis of an incidental meandering right pulmonary vein was established.The case is used to review the literature on this rare pulmonary anomaly,including pathogenesis,its relationship with scimitar syndrome and scimitar variant,and diagnosis,with an emphasis on the role modern CT techniques can play in noninvasive diagnosis.A revision to the nomenclature of pulmonary vascular anomalies is proposed to help reduce confusion in the literature.

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.

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.