The clinical value of dual-time point 18F-FDG PET/CT for differentiating extrahepatic cholangiocarcinoma from benign disease. Clin Nucl Med. 2013;38:e106-e111. [PMID: 23354026 DOI: 10.1097/rlu.0b013e318266f402]

Comparable Diagnostic Value of 99mTc-FAPI-46 SPECT/CT and 18F-FDG PET/CT in Cholangiocarcinoma: A Case Report

We describe a 51-year-old man with cholangiocarcinoma of the common bile duct. Initially deemed nonmetastatic, he was a candidate for curative surgery and liver transplantation. However, during laparotomy, peritoneal seeding was discovered, necessitating omentectomy and lesion resection. Following chemotherapy, the patient underwent 18F-FDG PET/CT for re-staging, revealing uptake in the primary tumor and a right iliac bone metastasis. Subsequently, FAPI-based scintigraphy using 99mTc-FAPI-46 as a novel conventional imaging agent demonstrated comparable uptake in both lesions. This case highlights the diagnostic potential of 99mTc-FAPI-46 SPECT/CT as an alternative to 18F-FDG PET/CT and 68Ga-FAPI in cholangiocarcinoma, particularly in resource-limited settings.

PET/MRI: pictorial review of hepatobiliary and pancreatic applications

PET and MRI both play valuable roles in the management of hepatobiliary and pancreatic (HBP) malignancies. Simultaneous PET/MRI combines the excellent soft-tissue resolution and anatomic details from MRI with functional information from PET in a single comprehensive examination. MRI is the main imaging modality in evaluating HCC, playing important roles in screening, characterization, local extent, and evaluating tumor response, whereas 18F-fluorodeoxyglucose (FDG) PET can help evaluate for lymph node involvement and metastatic disease. In cholangiocarcinoma and pancreatic malignancies, both PET and MRI have excellent utility in initial staging as well as assessing treatment response. In all HBP malignancies, FDG-PET/MRI is a unique problem-solving tool in complex cases and diagnostic challenges, especially after locoregional therapy and when differentiating residual or recurrent viable disease from inflammatory and other benign processes. In this manuscript, we review the role of PET/MRI in the diagnosis, staging, assessing treatment response, and characterizing post-treatment processes. With the introduction of multiple new tracers, the value of PET/MRI has not yet been fully realized, and more studies are needed to demonstrate the utility and efficacy of PET/MRI in improving patient care in hepatobiliary and pancreatic oncology.

Diagnostic Superiority of Dual-Time Point [18F]FDG PET/CT to Differentiate Malignant from Benign Soft Tissue Tumors

[18F]FDG PET/CT is used in the workup of indeterminate soft tissue tumors (STTs) but lacks accuracy in the detection of malignant STTs. The aim of this study is to evaluate whether dual-time point [18F]FDG PET/CT imaging (DTPI) can be useful in this indication. In this prospective study, [18F]FDG PET/CT imaging was performed 1 h (t1) and 3 h (t2) after injection. Tumor uptake (SUVmax) was calculated at each time point to define a retention index (RI) corresponding to the variation between t1 and t2 (%). Sixty-eight patients were included, representing 20 benign and 48 malignant tumors (including 40 sarcomas). The RI was significantly higher in malignant STTs than in benign STTs (median: +21.8% vs. -2%, p < 0.001). An RI of >14.3% predicted STT malignancy with a specificity (Sp) of 90% and a sensitivity (Se) of 69%. An SUVmaxt1 of >4.5 was less accurate with an Sp of 80% and an Se of 60%. In a subgroup of tumors with at least mild [18F]FDG uptake (SUVmax ≥ 3; n = 46), the RI significantly outperformed the diagnostic accuracy of SUVmax (AUC: 0.88 vs. 0.68, p = 0.01). DTPI identifies malignant STT tumors with high specificity and outperforms the diagnostic accuracy of standard PET/CT.

Comparison of Conventional Imaging and 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Diagnostic Accuracy of Staging in Patients with Intrahepatic Cholangiocarcinoma

We aimed to examine the accuracy of tumor staging of intrahepatic cholangiocarcinoma (ICC) by using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT). From January 2001 to December 2021, 202 patients underwent PET-CT, CT, and MRI for the initial staging of ICC in two institutions. Among them, 102 patients had undergone surgical treatment. Ninety patients who had a histopathological diagnosis of ICC were retrospectively reviewed. The sensitivity and specificity of 18F-FDG PET-CT, CT, and magnetic resonance imaging (MRI) in detecting tumors, satellite focus, vascular invasion, and lymph node metastases were analyzed. Ninety patients with histologically diagnosed ICC were included. PET-CT demonstrated no statistically significant advantage over CT and MR in the diagnosis of multiple tumors and macrovascular invasion, and bile duct invasion. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET-CT in lymph node metastases were 84%, 86%, 91%, 84%, and 86%, respectively. PET-CT revealed a significantly higher accuracy compared to CT or MRI (86%, 67%, and 76%, p < 0.01, respectively) in the diagnosis of regional lymph node metastases. The accuracy of tumor staging by PET-CT was higher than that by CT/MRI (PET-CT vs. CT vs. MRI: 68/90 vs. 47/90 vs. 51/90, p < 0.05). 18F-FDG PET-CT had sensitivity and specificity values for diagnosing satellite focus and vascular and bile duct invasion similar to those of CT or MRI; however, PET-CT showed higher accuracy in diagnosing regional lymph node metastases. 18F-FDG PET-CT exhibited higher tumor staging accuracy than that of CT/MRI. Thus, 18FDG PET-CT may support tumor staging in ICC.

Tips and tricks for the diagnosis and management of biliary stenosis-state of the art review

Biliary stenosis may represent a diagnostic and therapeutic challenge resulting in a delay in diagnosis and initiation of therapy due to the frequent difficulty in distinguishing a benign from a malignant stricture. In such cases, the diagnostic flowchart includes the sequential execution of imaging techniques, such as magnetic resonance, magnetic resonance cholangiopancreatography, and endoscopic ultrasound, while endoscopic retrograde cholangiopancreatography is performed to collect tissue for histopathological/cytological diagnosis or to treat the stenosis by insertion of stent. The execution of percutaneous transhepatic drainage with subsequent biopsy has been shown to increase the possibility of tissue diagnosis after failure of the above techniques. Although the diagnostic yield of histopathology and imaging has increased with improvements in endoscopic ultrasound and peroral cholangioscopy, differential diagnosis between malignant and benign stenosis may not be easy in some patients, and strictures are classified as indeterminate. In these cases, a multidisciplinary workup including biochemical marker assays and advanced technologies available may speed up a diagnosis of malignancy or avoid unnecessary surgery in the event of a benign stricture. Here, we review recent advancements in the diagnosis and management of biliary strictures and describe tips and tricks to increase diagnostic yields in clinical routine.

Role of dual-time point 18F-FDG PET/CT imaging in the primary diagnosis and staging of hilar cholangiocarcinoma

PURPOSE

The aim of this study was to evaluate the role of dual-time point 18F-FDG PET/CT imaging in the primary diagnosis and staging of hilar cholangiocarcinoma (HCCA).

METHODS

Dual-time point FDG PET/CT findings, including early phase whole-body scanning and abdominal delayed phased performed 1 and 2 h after radiotracer injection, respectively, were retrospective reviewed in 69 patients conformed HCCA by histology. PET/CT was evaluated based on visual interpretation and the semiquantitative index of SUVmax and tumor-to-normal liver tissue ratio (TNR) for both early and delayed images.

RESULTS

For all 69 HCCA patients, the mean SUVmax of the lesion and TNR in delayed phase was significantly higher than that in early phase (6.1 ± 4.7, 2.2 ± 1.7, vs 5.1 ± 3.4, 1.6 ± 1.1; P < 0.001). The sensitivity and accuracy value of detection primary lesions was 69.6% and 70% in early phase vs 76.8% and 76.8% in delay phase, respectively. There was a significant correlation between lesion SUVmax and Ki67 index in both dual-time imaging (r = 0.462, P < 0.001 in early phase vs r = 0.47, P < 0.001 in delay phase). The sensitivity, specificity and accuracy value of metastatic lymph nodes prediction was 50%, 67.3% and 71% in early phase vs 62.5%, 73.3% and 76.8% in delayed phase, respectively. The sensitivity, specificity and accuracy of FDG PET/CT in detecting distant metastasis in our study was 75%, 100% and 97.1%. There was no difference of predicting distant metastasis between early phase and delayed phase.

CONCLUSION

Delayed phase in dual-time point 18F-FDG PET/CT scan provides additional usefulness for detection primary tumor and lymph nodes metastases in HCCA, but there was no added benefit of delayed PET/CT imaging in detection of distant metastases in this study. SUVmax in early and delayed phase could be used to assess tumor aggressiveness in pre-treatment HCCA.

Prognostic value of metabolic parameters measured by pretreatment dual-time-point 18F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with intrahepatic or perihilar cholangiocarcinoma: A STROBE study

The purpose of this study was to determine the glucose metabolism at delay phase measured by pretreatment dual-time-point 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/ computed tomography (CT) provides prognostic information independent of well-known prognostic factors in patients with intrahepatic or perihilar cholangiocarcinoma (ICC or PCC).From July 2012 to December 2017, 55 patients (men 27, women 28, mean age 68 ± 11 years) with pathologically proven ICC or PCC were enrolled in this retrospective study. The dual-time-point 18F-FDG PET/CT as part of a staging workup was performed in all patients. The patient's data includes age, sex, serum CA19-9, presence of LN or distant metastasis, early SUVmax (early maximum standardized uptake value [eSUV]), delay SUVmax (delay maximum standardized uptake value [dSUV]), retention index of SUVmax (percent change of maximum standardized uptake values [ΔSUV]), neutrophil to lymphocyte ratio (NLR) and histopathology including pCEA, p53, Ki-67 index. The analysis of the relationship between metabolic parameters and survival was done using the Kaplan-Meier curve and Cox proportional hazards regression model.Median survival for all patients was 357 days. Median early and delay SUVmax was 5.2 (range: 2.0-21.4) and 6.5 (range 2.7-24.5), respectively. The overall survival was found to be significantly related to eSUV, dSUV, ΔSUV, age, serum CA19-9 and NLR in univariate analysis. In multivariate analysis, dSUV (P = .014, 95%CI; 1.30-10.7, HR 3.74) and ΔSUVmax (P = .037, 95%CI; 1.05-6.12, HR 2.5) were independent factors of overall survival. Kaplan-Meier curve analysis clearly showed the significant difference of overall survival between 2 groups (high eSUV, low eSUV + high ΔSUV vs low eSUV and ΔSUV, P < .001) among the comparisons of the SUV parameters on FDG PET. In the receiver operating characteristic analysis using combinations of the SUV parameters, the 2 groups [eSUV + ΔSUV (P = .0001, area under the curve [AUC] 0.68) and dSUV + ΔSUV (P = .0002, AUC 0.71)] showed significantly larger AUC than the other groups applying eSUV or dSUV alone (AUC 0.61 and AUC 0.68).dSUV and ΔSUV on pretreatment dual-time-point 18F-FDG PET/CT can be useful parameters in the prediction of survival in patients with ICC or PCC.

Relationship between Standard Uptake Values of Positron Emission Tomography/Computed Tomography and Salivary Metabolites in Oral Cancer: A Pilot Study

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) is usually used for staging or evaluation of treatment response rather than for cancer screening. However, ¹⁸F-FDG PET/CT has also been used in Japan for cancer screening in people with no cancer symptoms, and accumulating evidence supports this application of ¹⁸F-FDG PET/CT. Previously, we have observed a correlation between the saliva and tumor metabolomic profiles in patients with oral cancer. Hence, if salivary metabolites demonstrate a significant correlation with PET parameters such as the maximum standardized uptake value (SUV_max), they may have the potential to be used as a screening tool before PET/CT to identify patients with high SUV_max. Hence, in this study, we aimed to explore the relationship between salivary metabolites and SUV_max of ¹⁸F-FDG PET/CT using previously collected data. ¹⁸F-FDG PET/CT was performed for staging 26 patients with oral cancer. The collected data were integrated and analyzed along with quantified salivary hydrophilic metabolites obtained from the same patients with oral cancer and controls (n = 44). In total, 11 metabolites showed significant correlations with SUV_max in the delayed phases. A multiple logistic regression model of the two metabolites showed the ability to discriminate between patients with oral cancer and controls, with an area under the receiver operating characteristic curve of 0.738 (p = 0.001). This study uniquely confirmed a relationship between salivary metabolites and SUV_max of PET/CT in patients with oral cancer; salivary metabolites were significantly correlated with SUV_max. These salivary metabolites can be used as a screening tool before PET/CT to identify patients with high SUV_max, i.e., to detect the presence of oral cancer.

PET/MRI of the hepatobiliary system: Review of techniques and applications

Simultaneous positron emission tomography and MRI (PET/MRI) is an emerging technology that offers the benefits of MRI, including excellent soft tissue contrast, lack of ionizing radiation, and functional MRI techniques, with the physiologic information provided by PET. Although most PET/MRI systems are currently installed in tertiary care centers, PET/MRI technology is becoming increasingly widespread. The usefulness of PET/MRI varies by tumor type and organ system and has been shown to have utility in evaluation of primary and secondary hepatic neoplasms. Understanding the appropriate applications, techniques and relevant imaging findings is important for practicing radiologists considering or currently utilizing PET/MR for the evaluation of primary liver neoplasms, including hepatocellular carcinoma (HCC), as well as staging of biliary neoplasms including cholangiocarcinoma and gallbladder cancer, identification of liver metastases, and staging of neuroendocrine tumor.

Comparison of magnetic resonance imaging and 18-fludeoxyglucose positron emission tomography/computed tomography in the diagnostic accuracy of staging in patients with cholangiocarcinoma: A meta-analysis

BACKGROUND

Accurate clinical staging of patients with cholangiocarcinoma (CCA) has a significant impact on treatment decisions. In this study, we aimed to compare the diagnostic value of magnetic resonance imaging (MRI) and 18-fludeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) for staging of CCA.

METHODS

We performed comprehensive systematic search in Web of Science (including MEDLINE) and Excerpta Medica Database for relevant diagnostic studies in accordance with the preferred reporting items for systematic reviews and meta-analysis statement. Based on data extracted from patient-based analysis, we calculated the pooled sensitivity and specificity with the 95% confidence intervals (CIs). In addition, the publication bias was assessed by Deek funnel plot of the asymmetry test. The potential heterogeneity was explored by threshold effect analysis and subgroup analyses.

RESULTS

Thirty-two studies with 1626 patients were included in present analysis. In T stage, the pooled sensitivity and specificity of MRI were 0.90 (95% CI 0.86-0.93), 0.84 (95% CI 0.73-0.91) respectively. The pooled sensitivity and specificity of F-FDG PET/CT were 0.91 (95% CI 0.83-0.95) and 0.85 (0.64-0.95) respectively. In N stage, the pooled sensitivity and specificity of MRI were 0.64 (95% CI 0.52-0.74) and 0.69 (95% CI 0.51-0.87) respectively. The pooled sensitivity and specificity of PET/CT were 0.52 (95% CI 0.37-0.66) and 0.92 (95% CI 0.79-0.97) respectively. In M stage, the pooled sensitivity and specificity of F-FDG PET/CT were 0.56 (95% CI, 0.42-0.69) and 0.95 (95% CI, 0.91-0.97) respectively. The Deek test revealed no significant publication bias. No threshold effect was identified. The subgroup analyses showed that pathological type (extrahepatic cholangiocarcinoma vs hilar cholangiocarcinoma/intrahepatic cholangiocarcinoma), country (Asia vs non-Asia) and type of MRI (1.5T vs. 3.0T) were potential causes for the heterogeneity of MRI studies and country (Asia vs non-Asia) was a potential source for F-FDG PET/CT studies.

CONCLUSION

The analysis suggested that both modalities provide reasonable diagnostic accuracy in T stage without significant differences between them. We recommend that both modalities be considered based on local availability and practice for the diagnosis of primary CCA tumors. In N stage, the diagnosis of lymph node metastasis (N) of CCA is still limited by MRI and F-FDG PET/CT, due to unsatisfactory diagnostic accuracy of both. Nevertheless, F-FDG PET/CT can be used to confirm lymph node metastasis while a negative result may not rule out metastasis. Furthermore, F-FDG PET/CT have a low sensitivity and a high specificity for detection of distant metastasis.

Dynamic whole-body 18F-FDG PET for differentiating abnormal lesions from physiological uptake

PURPOSE

Serial assessment of visual change in ¹⁸F-FDG uptake on whole-body ¹⁸F-FDG PET imaging was performed to differentiate pathological uptake from physiological uptake in the urinary and gastrointestinal tracts.

METHODS

In 88 suspected cancer patients, serial 3-min dynamic whole-body PET imaging was performed four times, from 60 min after ¹⁸F-FDG administration. In dynamic image evaluation, high ¹⁸F-FDG uptake was evaluated by two nuclear medicine physicians and classified as "changed" or "unchanged" based on change in uptake shape over time. Detectability of pathological uptake based on these criteria was assessed and compared with conventional image evaluation.

RESULTS

Dynamic whole-body PET imaging provided images of adequate quality for visual assessment. Dynamic image evaluation was "changed" in 118/154 regions of high physiological ¹⁸F-FDG uptake (77%): in 9/19 areas in the stomach (47%), in 32/39 in the small intestine (82%), in 17/33 in the colon (52%), and in 60/63 in the urinary tract (95%). In the 86 benign or malignant lesions, 84 lesions (98%) were "unchanged." A high ¹⁸F-FDG uptake area that shows no change over time using these criteria is highly likely to represent pathological uptake, with sensitivity of 97%, specificity of 76%, PPV of 70%, NPV of 98%, and accuracy of 84%.

CONCLUSION

Dynamic whole-body ¹⁸F-FDG PET imaging enabled differentiation of pathological uptake from physiological uptake in the urinary and gastrointestinal tracts, based on visual change of uptake shape.

18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) for patients with biliary tract cancer: Systematic review and meta-analysis

BACKGROUND & AIMS

The role of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) in the diagnosis and staging of patients with biliary tract cancers (BTCs) remains controversial, so we aimed to provide robust information on the utility of ¹⁸FDG-PET in the diagnosis and management of BTC.

METHODS

This systematic review and meta-analysis explored the diagnostic test accuracy of ¹⁸FDG-PET as a diagnostic tool for diagnosis of primary tumour, lymph node invasion, distant metastases and relapsed disease. Subgroup analysis by study quality and BTC subtype were performed. Changes in management based on ¹⁸FDG-PET and impact of maximum standardised uptake values (SUVmax) on prognosis were also assessed. A random effects model was used for meta-analyses.

RESULTS

A total of 2,125 patients were included from 47 eligible studies. The sensitivity (Se) and specificity (Sp) of ¹⁸FDG-PET for the diagnosis of primary tumour were 91.7% (95% CI 89.8-93.2) and 51.3% (95% CI 46.4-56.2), respectively, with an area under the curve (AUC) of 0.8668. For lymph node invasion, Se was 88.4% (95% CI82.6-92.8) and Sp was 69.1% (95% CI 63.8-74.1); AUC 0.8519. For distant metastases, Se was 85.4% (95% CI 79.5-90.2) and Sp was 89.7% (95% CI86.0-92.7); AUC 0.9253. For relapse, Se was 90.1% (95% CI 84.4-94.3) and Sp was 83.5% (95% CI 74.4-90.4); AUC 0.9592. No diagnostic threshold effect was identified. Meta-regression did not identify significant sources of heterogeneity. Sensitivity analysis revealed no change in results when analyses were limited to studies with low risk of bias/concern. The pooled proportion of change in management was 15% (95% CI 11-20); the majority (78%) due to disease upstaging. Baseline high SUVmax was associated with worse survival (pooled hazard ratio of 1.79; 95% CI 1.37-2.33; p <0.001).

CONCLUSIONS

There is evidence to support the incorporation of ¹⁸FDG-PET into the current standard of care for the staging (lymph node and distant metastases) and identification of relapse in patients with BTC to guide treatment selection; especially if the identification of occult sites of disease would change management, or if diagnosis of relapse remains unclear following standard of care imaging. The role for diagnosis of the primary tumour remains controversial due to low sensitivity and ¹⁸FDG-PET should not be considered as a replacement for pathological confirmation in this setting.

LAY SUMMARY

A positron emission tomography (PET scan), using ¹⁸F-fluorodeoxyglucose (¹⁸FDG), can help doctors identify areas of cancer in the body by highlighting "hot spots". These hotspots may be cancerous (true positive) but may also be non-cancerous, like inflammation (false positive). We show that PET scans are useful to assess how far advanced the cancer is (by assessing spread to lymph glands and to other organs) and also to identify if the cancer has recurred (for example after surgery), thus helping doctors to make treatment decisions. However, a biopsy is still needed for the initial diagnosis of a biliary tract cancer, because of the high chance of a "false positive" with PET scans.

Clinical presentation, diagnosis and staging of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a heterogeneous group of tumours, derived from cells of the biliary tree, which represent the second most frequent primary liver tumour. According to the most recent classifications, CCA can be subdivided into intrahepatic (iCCA) and extrahepatic (eCCA) which include perihilar (pCCA) and distal (dCCA) CCA. CCA are usually identified at advanced stages, when the primary tumour grows enough to produce a large liver mass or when jaundice has developed because of biliary tree obstruction. The ongoing challenges in the identification of risk factors and definition of a specific population at higher risk of developing CCA are the main challenges for the development of screening programs. Therefore, late diagnosis remains an unresolved issue in CCA. Imaging plays an important role in the detection and characterization of CCA, helping with radiological diagnosis, guiding biopsy procedures and allowing staging of the tumour. This review focuses on clinical presentations and diagnosis and staging techniques of CCA.

Imaging of Cholangiocarcinoma

Cholangiocarcinoma (CC) is the second most common primary hepatobiliary tumour, and it is increasing in incidence. Imaging characteristics, behaviour, and therapeutic strategies in CC differ significantly, depending on the morphology and location of the tumour. In cross-sectional imaging, CCs can be classified according to the growth pattern (mass-forming, periductal infiltrating, intraductal) and the location (intrahepatic, perihilar, extrahepatic/distal). The prognosis of CC is unfavourable and surgical resection is the only curative treatment option; thus, early diagnosis (also in recurrent disease) and accurate staging including the evaluation of lymph node involvement and vascular infiltration is crucial. However, the diagnostic evaluation of CC is challenging due to the heterogeneous nature of the tumour. Diagnostic modalities used in the imaging of CC include transabdominal ultrasound, endosonography, computed tomography, magnetic resonance imaging with cholangiopancreatography, and hybrid imaging such as positron emission tomography/computed tomography. In this review, the potential of cross-sectional imaging modalities in primary staging, treatment monitoring, and detection of recurrent disease will be discussed.

Does Delayed-Time-Point Imaging Improve 18F-FDG-PET in Patients With MALT Lymphoma?: Observations in a Series of 13 Patients

To determine whether in patients with extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue lymphoma (MALT), delayed–time-point 2-¹⁸F-fluoro-2-deoxy-d-glucose-positron emission tomography (¹⁸F-FDG-PET) performs better than standard–time-point ¹⁸F-FDG-PET.

Role of 18F-FDG PET/CT Imaging in Intrahepatic Cholangiocarcinoma

PURPOSE

Although intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy after hepatocellular carcinoma, there are limited data available on PET/CT imaging in ICC. This retrospective study analyzed the role of PET/CT imaging in the evaluation of ICC.

METHODS

FDG PET/CT findings were reviewed in 65 patients with histologically confirmed ICC. PET/CT was evaluated based on visual interpretation and the semiquantitative index of SUVmax and tumor-to-normal liver tissue ratio (TNR), which were consequently further analyzed and correlated with tumor localization, differentiation, size, and serum levels of tumor markers. Forty-five cases also underwent abdominal MRI examinations.

RESULTS

Nineteen patients had hilar ICC, whereas 46 patients had peripheral ICC. Sixty cases of ICC showed elevated FDG uptake with an average SUVmax of 8.3 ± 4.7 and TNR of 3.1 ± 1.7. Five cases located in the hilum were false negative on PET/CT imaging. Compared with hilar ICC, SUVmax and TNR of peripheral ICC were significantly higher (P < 0.05). FDG accumulation correlated with the degree of ICC differentiation. SUVmax and TNR correlated with tumor size, whereas there was no correlation observed with serum levels of carbohydrate antigen 19-9. The sensitivity, specificity, and accuracy of PET/CT and MRI in the diagnosis of regional lymph node metastases were 70.0% versus 50%, 91.7% versus 83.3%, and 81.8% versus 68.2%, respectively. PET/CT upstaged 12.3% and downstaged 3.1% of cases and had no impact on patient management in the remaining 84.6% of cases.

CONCLUSIONS

Combination of FDG PET/CT and abdominal MRI might improve the diagnostic accuracy for ICC.

Tubular adenoma of the common bile duct with uptake in 18F-FDG PET: A case report

A 64-year-old man presented with epigastric discomfort and nausea. Laboratory analyses revealed increased levels of total and direct bilirubin, and increased levels of aminotransferases. Computed tomography revealed the presence of a mass in the distal common bile duct. Endoscopic retrograde cholangiopancreatography and intraductal ultrasonography revealed a 25 mm filling defect in the distal common bile duct, and biopsy of the lesion disclosed the presence of tubular adenoma. Using fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) revealed an increased accumulation of the tracer in the lesion, with a maximum standard uptake value (SUV_max) of 3.3. The patient received a pylorus-preserving pancreatoduodenectomy. The histopathological examination revealed a tubular adenoma with low-grade atypia. The patient remains alive 15 months following the surgery, with no evidence of recurrence of the adenoma. ¹⁸F-FDG PET has been successfully applied in clinical practice to detect a wide variety of tumor types, including lymphoma, lung, colon and bile duct cancer. In the present study, a case of bile duct adenoma with low-grade atypia was reported, revealing the uptake of ¹⁸F-FDG. ¹⁸F-FDG PET may be able to detect premalignant tumors of the bile duct, although whether ¹⁸F-FDG PET is able to differentially discriminate between diagnoses of adenoma and carcinoma of the bile duct remains to be fully elucidated, and the assessment of further case studies is required.

Dual-time-point Imaging and Delayed-time-point Fluorodeoxyglucose-PET/Computed Tomography Imaging in Various Clinical Settings

The techniques of dual-time-point imaging (DTPI) and delayed-time-point imaging, which are mostly being used for distinction between inflammatory and malignant diseases, has increased the specificity of fluorodeoxyglucose (FDG)-PET for diagnosis and prognosis of certain diseases. A gradually increasing trend of FDG uptake over time has been shown in malignant cells, and a decreasing or constant trend has been shown in inflammatory/infectious processes. Tumor heterogeneity can be assessed by using early and delayed imaging because differences between primary versus metastatic sites become more detectable compared with single time points. This article discusses the applications of DTPI and delayed-time-point imaging.

Synchronous double primary squamous cell carcinoma and adenocarcinoma of the extrahepatic bile duct: a case report

Introduction

Synchronous double cancers of the bile duct are exceptionally rare. We here report a case of synchronous squamous cell carcinoma and adenocarcinoma of the extrahepatic bile duct.

Case presentation

A 67-year-old Asian man visited our clinic complaining of jaundice and dark urine. Direct hyperbilirubinemia and an elevated cancer antigen 19–9 level were detected. Preoperative abdominal computed tomography and positron emission tomography showed two masses at the bifurcation of the common hepatic duct and at the distal common bile duct. After biliary drainage, we performed radical pylorus-preserving pancreaticoduodenectomy, without resection margin involvement. Pathological findings revealed that the proximal lesion was a squamous cell carcinoma and that the distal lesion was an adenocarcinoma. Both cholangiocarcinomas were confined to the fibromuscular layer, and there was no communication between the two tumors. Multiple conglomerated metastatic tumors were detected in his liver 3 months after surgery. He died 8 months after diagnosis.

Conclusions

The disease displayed very aggressive behavior and a very poor prognosis. The only chance for long-term survival is treatment with radical resection. Preoperative positron emission tomography-computed tomography is useful in detecting occult cancer.

Dual-phase 18F-FDG PET/CT imaging in the characterization of pancreatic lesions: does it offer prognostic information?

OBJECTIVE

The primary aim of our prospective study was to evaluate the usefulness of dual-phase F-fluoro-deoxy-glucose PET/computed tomography (F-FDG PET/CT) in the characterization of pancreatic masses. The secondary aim was to assess whether delayed imaging revealed any prognostic information.

MATERIALS AND METHODS

Fifty patients with periampullary or pancreatic masses on conventional imaging were included in this study. Early and delayed PET/CT was performed, followed by pathological examination in all patients. PET/CT parameters including uptake pattern, SUVearly, SUVdelayed, lesion to background ratio (L/B), and retention index (RI) were assessed for their ability to differentiate benign from malignant lesions. Patients with malignant lesions were followed up for a median duration of 26 months. The association of 11 variables with survival was analyzed by univariate and multivariate methods.

RESULTS

Thirty-one patients had malignant lesions and 19 had benign lesions. The mean SUVearly, L/B, SUVdelayed, and RI between the malignant and benign lesions were statistically significant. The F-FDG uptake pattern of the lesions had higher sensitivity (93.5%) and specificity (100%) compared with RI (cutoff 25.7%) (84 and 37%, respectively) for diagnosing malignancy (P<0.05). In univariate analysis both RI (>18.7%) and tumor size (>2.6 cm) predicted significantly poor survival, whereas in multivariate analysis RI (P=0.04) was the only predictor of poor survival.

CONCLUSION

Dual-phase F-FDG PET/CT is not useful in characterizing pancreatic masses as it cannot differentiate benign from malignant lesions, and focal uptake on early PET imaging is the best indicator of malignancy. A possible benefit in performing a delayed scan is that a high RI (>18.7) can predict poor survival and hence may be useful in treatment planning.

Radiological diagnosis in cholangiocarcinoma: Application of computed tomography, magnetic resonance imaging, and positron emission tomography

The purpose of radiological imaging in patients with suspected or known cholangiocarcinoma (CCA) is tumour detection, lesion characterization and assessment of resectability. Different imaging modalities are implemented complementary in the diagnostic work-up. Non-invasive imaging should be performed prior to invasive biliary procedures in order to avoid false positive results. For assessment of intraparenchymal tumour extension and evaluation of biliary and vascular invasion, MRI including MRCP and CT are the primarily used imaging modalities. The role of PET remains controversial with few studies showing benefit with the detection of unexpected metastatic spread, the differentiation between benign and malignant biliary strictures, and for discriminating post therapeutic changes and recurrent CCA.

Cutaneous metastasis of cholangiocarcinoma

AIM: To investigate the clinical characteristics and prognostic factors of cutaneous metastasis of cholangiocarcinoma by a retrospective analysis of published cases.

METHODS: An extensive search was conducted in the English literature within the PubMed database using the following keywords: cutaneous metastasis or skin metastasis and cholangiocarcinoma or bile duct. The data of 30 patients from 21 articles from 1978 to 2014 were analyzed. Patient data retrieved from the articles included the following: age, gender, time cutaneous metastasis occurred, number of cutaneous metastases throughout life, sites of initial cutaneous metastasis, anatomic site, pathology and differentiation of cholangiocarcinoma, and immunohistochemical results of the cutaneous metastasis. The assessment of overall survival after cutaneous metastasis (OSCM) was the primary endpoint.

RESULTS: The median age at diagnosis of cutaneous metastasis of cholangiocarcinoma was 60.0 years (range: 35-77). This metastasis showed a predilection towards males, with a male to female ratio of 3.29. In 8 cases (27.6%), skin metastasis was the first sign of cholangiocarcinoma. Additionally, 18 cases (60.0%) manifested single cutaneous metastasis, while 12 cases (40.0%) demonstrated multiple skin metastases. In 50.0% of patients, the metastasis occurred in the drainage region, while 50.0% of patients had distant cutaneous metastases. The scalp was the most frequently involved region of distant skin metastasis, occurring in 36.7% of patients. The median OSCM of cholangiocarcinoma was 4.0 mo. Patient age and cutaneous metastatic sites showed no significant relation with OSCM, while male gender and single metastasis of the skin were associated with a poorer OSCM (hazard ratio: 0.168; P = 0.005, and hazard ratio: 0.296; P = 0.011, respectively).

CONCLUSION: The prognosis of cutaneous metastasis of cholangiocarcinoma is dismal. Both male gender and single skin metastasis are associated with a poorer OSCM.

18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues

Background

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic ¹⁸F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals.

Methods

¹⁸F-FDG-avid lesions (not surgically manipulated or altered during ¹⁸F-FDG-directed surgery, and visualized both on preoperative and postoperative ¹⁸F-FDG PET/CT imaging) and corresponding background tissues were assessed for ¹⁸F-FDG accumulation on same-day preoperative and postoperative ¹⁸F-FDG PET/CT imaging. Multiple patient variables and ¹⁸F-FDG-avid lesion variables were examined.

Results

For the 32 ¹⁸F-FDG-avid lesions making up the final ¹⁸F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative ¹⁸F-FDG PET/CT scans were 73 (±3, 70-78) and 530 (±79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean ¹⁸F-FDG-avid lesion SUV_max values were 7.7 (±4.0, 3.6-19.5) and 11.3 (±6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUV_max values were 2.3 (±0.6, 1.0-3.2) and 2.1 (±0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUV_max ratios were 3.7 (±2.3, 1.5-9.8) and 5.8 (±3.6, 1.6-16.2), respectively, (P < 0.001).

Conclusions

¹⁸F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for ¹⁸F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the ¹⁸F-FDG-avid lesion SUV_max values, decreased background SUV_max values, and increased lesion-to-background SUV_max ratios seen from preoperative to postoperative ¹⁸F-FDG PET/CT imaging have great potential for allowing for the integrated, real-time use of ¹⁸F-FDG PET/CT imaging in conjunction with ¹⁸F-FDG-directed interventional radiology biopsy and ablation procedures and ¹⁸F-FDG-directed surgical procedures, as well as have far-reaching impact on potentially re-shaping future thinking regarding the “most optimal” injection-to-scan acquisition time interval for all routine diagnostic ¹⁸F-FDG PET/CT oncologic imaging.

Diagnostic accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography in the evaluation of the primary tumor in patients with cholangiocarcinoma: a meta-analysis

OBJECTIVE

To meta-analyze published data about the diagnostic accuracy of fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) or PET/computed tomography (PET/CT) for primary tumor evaluation in patients with cholangiocarcinoma (CCa).

METHODS

A comprehensive literature search of studies published through December 31, 2013, was performed. Pooled sensitivity and specificity were calculated on a per patient based analysis. Subgroup analyses considering the device used (PET versus PET/CT) and the localization of the primary tumor (intrahepatic cholangiocarcinoma (IH-CCa), extrahepatic cholangiocarcinoma (EH-CCa), and hilar cholangiocarcinoma (H-CCa)) were carried out.

RESULTS

Twenty-three studies including 1232 patients were included in the meta-analysis. Pooled sensitivity and specificity of (18)F-FDG-PET or PET/CT were 81% and 82%, respectively. Pooled sensitivity and specificity, respectively, were 80% and 89% for PET, 82% and 75% for PET/CT, 95% and 83% for IH-CCa, 84% and 95% for H-CCa, and 76% and 74% for EH-CCa.

CONCLUSIONS

(18)F-FDG-PET and PET/CT were demonstrated to be accurate diagnostic imaging methods for primary tumor evaluation in patients with CCa. These tools have a better diagnostic accuracy in patients with IH-CCa than in patients with EH-CCa. Further studies are needed to evaluate the accuracy of (18)F-FDG-PET or PET/CT in patients with H-CCa.

The Clinical Role of Dual-Time-Point (18)F-FDG PET/CT in Differential Diagnosis of the Thyroid Incidentaloma

Thyroid incidentalomas are common findings during imaging studies including ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for cancer evaluation. Although the overall incidence of incidental thyroid uptake detected on PET imaging is low, clinical attention should be warranted owing to the high incidence of harboring primary thyroid malignancy. We retrospectively reviewed 2,368 dual-time-point ¹⁸F-FDG PET/CT cases that were undertaken for cancer evaluation from November 2007 to February 2009, to determine the clinical impact of dual-time-point imaging in the differential diagnosis of thyroid incidentalomas. Focal thyroid uptake was identified in 64 PET cases and final diagnosis was clarified with cytology/histology in a total of 27 patients with ¹⁸F-FDG-avid incidental thyroid lesion. The maximum standardized uptake value (SUVmax) of the initial image (SUV1) and SUVmax of the delayed image (SUV2) were determined, and the retention index (RI) was calculated by dividing the difference between SUV2 and SUV1 by SUV1 (i.e., RI = [SUV2 - SUV1]/SUV1 × 100). These indices were compared between patient groups that were proven to have pathologically benign or malignant thyroid lesions. There was no statistically significant difference in SUV1 between benign and malignant lesions. SUV2 and RI of the malignant lesions were significantly higher than the benign lesions. The areas under the ROC curves showed that SUV2 and RI have the ability to discriminate between benign and malignant thyroid lesions. The predictability of dual-time-point PET parameters for thyroid malignancy was assessed by ROC curve analyses. When SUV2 of 3.9 was used as cut-off threshold, malignancy on the pathology could be predicted with a sensitivity of 87.5 % and specificity of 75 %. A thyroid lesion that shows RI greater than 12.5 % could be expected to be malignant (sensitivity 88.9 %, specificity 66.3 %). All malignant lesions showed an increase in SUVmax on the delayed images compared with the initial images. But in the group of benign lesions, 37.5 % (6/16) showed a decrease or no change in SUVmax. Dual-time-point ¹⁸F-FDG PET/CT, obtaining additional images 2 h after injection, seems to be a complementary method for the differentiation between malignancy and benignity of incidental thyroid lesions.