Diagnostic usefulness of FDG PET for pancreatic mass lesions

Role of dual-point 18F-FDG-PET/CT in the diagnosis of pancreatic adenocarcinoma, in patients with and without concomitant chronic pancreatitis: Comparison with CECT and EUS

PURPOSE

The aim of this study was to evaluate the diagnostic performance of dual-time-point-PET/CT, CECT and EUS + FNA in diagnosing pancreatic-ductal-adenocarcinomas (PDAC), in context of concomitant Chronic Pancreatitis (CP).

METHODS

18F-FDG-PET/CTs were prospectively acquired in 22 confirmed CP and 23 confirmed PDAC patients (calculated for 90% power); and cut-offs of 2.2 for early-SUV(∼1hr), 2.4 for delayed-SUV(∼3hr) and 1.36 for Retention-index (RI), were derived. These cut-offs were validated in PET/CTs of 75 patients (51.9 ± 13.3years; 54 men) with pancreatic masses of unknown nature. Comparisons were made with triple-phase-CECT (73 patients) and EUS + FNA (54 patients). Histopathology was obtained in 68 patients (including all PDACs) and 7 were followed up for minimum of 2 years.

RESULTS

In patients without concomitant CP, sensitivity, specificity and accuracy for diagnosing malignancy in standard-acquisition-PET/CT, dual-time-point-PET/CT, CECT and EUS + FNA were 97.4%, 83.3%, 94.0%; 97.4%, 75.0%, 92%; 94.6%, 66.7%, 87.8% and 92.6%, 88.9%, 91.7% respectively. Corresponding values in patients with concomitant CP were 88.9%, 57.1%, 80.0%; 100%, 57.1%, 88%; 82.4%, 57.1%, 75% and 100%, 100%, 100% respectively. In lesions ≤2 cm (AJCC-T1), dual-time-point-PET/CT was the most sensitive (95.8%). ROC-analysis revealed significantly higher area-under-the-curve for RI over early-SUV (p = 0.002) in cases with concomitant CP only. In patients with confirmed liver-metastases, PET/CT and CECT identified 15/16 and 13/16 lesions. PET/CT identified additional lung-metastases in 3 and bone-metastasis in one patient.

CONCLUSION

In patients without concomitant CP and with larger lesions, PET/CT and CECT are equivocal as screening modalities, with no benefit of dual-time-point-PET/CT acquisitions. However, in patients with concomitant CP and smaller lesions, dual-time-point PET/CT is better; with sensitivity comparable to EUS + FNA.

A case report of mucinous adenocarcinoma derived from intra-ampullary papillary-tubular neoplasm with a malignant course

Background

Intra-ampullary papillary-tubular neoplasm (IAPN) has been classified as a Vater papillary tumor. The prognosis of IAPN is generally relatively good. Here, we describe a patient with a mucinous adenocarcinoma cluster in the Vater papilla of IAPN origin.

Clinical presentation

The patient was a 66-year-old man who was admitted to our hospital after a diagnosis of pancreatic head carcinoma based on a pancreatic duct dilatation found on abdominal ultrasound. CT showed a 40 mm lesion in the pancreatic head and expansion of the main pancreatic duct to a maximum diameter of 9 mm on the caudal side of the lesion. The extrahepatic bile duct had also expanded to a maximum diameter of 8 mm. PET/CT showed fluorodeoxyglucose (FDG) accumulation of SUV_max 6.02 that corresponded to the tumor in the pancreatic head, though it did not suggest distant metastasis. The patient was diagnosed with pancreatic head carcinoma T3 N0 M0 Stage IIA and underwent a pancreaticoduodenectomy. Pathology indicated that the tumor in the pancreatic head was a benign inflammatory lesion. On the other hand, the papillotubular tumor pervading the lumen in the duodenal papillary common channel met the criteria for IAPN, and a mucinous adenocarcinoma cluster found in the surrounding stroma suggested malignant transformation of IAPN. No metastasis to lymph nodes was demonstrated. With regard to the mucus phenotype of each lesion, the IAPN was MUC2 and MUC5AC positive, while the mucinous adenocarcinoma was MUC2-positive and MUC5AC-negative. In addition, CD10 was negative in both lesions, suggesting that mucus transformation from the gastric type to the intestinal type was a key element. A blood test 10 months after surgery showed increased CA19-9 (105 U/mL) and CEA (7.1 ng/mL). Abdominal CT showed multiple cystoid nodes in the liver, which were diagnosed as multiple liver metastases of mucinous adenocarcinoma transformed from the IAPN.

Conclusions

We reported a case with IAPN that developed in the Vater papilla, which took an extremely malignant course. IAPN generally has a good prognosis, but it is important to understand that a malignant course may occur.

O-Glycan-Altered Extracellular Vesicles: A Specific Serum Marker Elevated in Pancreatic Cancer

Simple Summary

Pancreatic cancer (PC) is among the most lethal malignancies due to an often delayed and difficult initial diagnosis. Therefore, the development of a novel, early stage, diagnostic PC marker in liquid biopsies is of great significance. In this study, we analyzed the differential glycomic profiling of extracellular vesicles (EVs) derived from serum using lectin microarray. The glyco-candidates of PC-specific EVs were quantified using a high-sensitive exosome-counting system, ExoCounter. An absolute quantification system for altered glycan-containing EVs elevated in PC serum was established. EVs recognized by O-glycan-binding lectins ABA or ACA were identified as candidate markers by lectin microarray. Quantitative analyses using ExoCounter revealed that the ABA- or ACA-positive EVs were significantly increased in the serum of PC patients. These specific EVs with O-glycans can act as potential biomarkers in a liquid biopsy for PC patients screening.

Abstract

Pancreatic cancer (PC) is among the most lethal malignancies due to an often delayed and difficult initial diagnosis. Therefore, the development of a novel, early stage, diagnostic PC marker in liquid biopsies is of great significance. In this study, we analyzed the differential glycomic profiling of extracellular vesicles (EVs) derived from serum (two cohorts including 117 PC patients and 98 normal controls) using lectin microarray. The glyco-candidates of PC-specific EVs were quantified using a high-sensitive exosome-counting system, ExoCounter. An absolute quantification system for altered glycan-containing EVs elevated in PC serum was established. EVs recognized by O-glycan-binding lectins ABA or ACA were identified as candidate markers by lectin microarray. Quantitative analyses using ExoCounter revealed that the ABA- or ACA-positive EVs were significantly increased in the culture of PC cell lines or in the serum of PC patients including carbohydrate antigen 19-9 negative patients with high area under curve values. The elevated numbers of EVs in PC serum returned to normal levels after pancreatectomy. Histological examination confirmed that the tumors stained with ABA/ACA. These specific EVs with O-glycans recognized by ABA/ACA are elevated in PC sera and can act as potential biomarkers in a liquid biopsy for PC patients screening.

Pancreatic sarcomatoid carcinoma: CT, MRI, and 18F-FDG PET/CT features

AIM

To investigate computed tomography (CT), magnetic resonance imaging (MRI), and combined 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron-emission tomography (PET)/CT features of pancreatic sarcomatoid carcinoma (PSC).

MATERIALS AND METHODS

The hospital database was searched retrospectively for the patients with PSC confirmed at histopathology after surgery. Ten patients who underwent unenhanced and enhanced CT (n=4), unenhanced and enhanced MRI (n=2), ¹⁸F-FDG PET/CT (n=2), and both enhanced CT and ¹⁸F-FDG PET/CT (n=2) were enrolled. Two patients underwent additional delayed PET/CT. The maximum standardised uptake value (SUVmax) was measured on PET/CT images.

RESULTS

Eleven lesions were detected in 10 patients. Solid and cystic components (n=6), intratumoural haemorrhage (n=1), nodular calcification (n=2), main pancreatic duct dilatation resulted from lesion obstruction (n=5) or compression (n=3), cholangiectasis (n=5), vascular and peripheral organ invasion (n=5 and 6, respectively), hepatic and lymphatic metastases (n=4 and 2, respectively) were detected. All five lesions in four patients who underwent PET/CT showed intense FDG uptake on PET/CT with SUVmax (16, range 10.9-21.1). Increase of FDG uptake (SUVmax = 18.9, 20.1, and 27.3, respectively) was revealed on the delayed scan of three lesions in two patients.

CONCLUSIONS

PSCs were more commonly ill-defined solid cystic masses, which caused pancreatic duct obstruction/compression without pancreatic parenchymal atrophy, and these masses on PET/CT showed high FDG uptake on both initial and delayed PET/CT.

Is 18F-FDG PET/CT useful for diagnosing relapsing polychondritis with airway involvement and monitoring response to steroid-based therapy?

Background

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a promising tool for diagnosing relapsing polychondritis (RP). However, its usefulness in assessing RP with airway involvement is unknown.

Objective

This study aimed to further evaluate and confirm the potency of ¹⁸F-FDG PET/CT in diagnosing RP with airway involvement and monitoring response to steroid-based therapy.

Methods

A total of 30 patients from a dedicated respiratory centre, diagnosed with RP in accordance with McAdam, Damiani or Levine criteria, were included in this study. All patients underwent baseline ¹⁸F-FDG PET/CT, and 10 patients underwent second scans after 2.5–15 months of steroid-based therapy. Visual scores (VS) and maximal standard uptake values (SUV_max) were analysed.

Results

In the initial scan, 83.3% (25/30) of patients were found to have FDG uptake in more than one cartilage. The median VS and SUV_max in the cartilages were 3 (range, 1–3) and 3.8 (range, 1.9–17.9), respectively. Positive rates for PET/CT-guided biopsy in nasal, auricular, and tracheal/bronchial cartilages were 100% (5/5), 88.9% (8/9), and 10.5% (2/19), respectively, but the positive biopsy rate in the auricular cartilage was 92.3% (12/13) even without PET/CT assessment. Based on biopsy-proven sites, the sensitivity of PET/CT was 55.6%, and the specificity was 5.3%. Compared with the baseline scan, the second scan showed much lower median VS (2 vs 3, respectively; p < 0.0001) and SUV_max (2.9 vs 3.8, respectively; p < 0.001). Of 10 patients who underwent second PET/CT, 8 had complete therapeutic response, while 2 had partial response.

Conclusion

¹⁸F-FDG PET/CT assists in identifying multiple cartilage involvement in RP, but it seems neither a sensitive nor specific modality in diagnosing RP with airway involvement. Moreover, PET/CT has limited utility in locating biopsy sites and monitoring therapeutic response to corticosteroids.

18-Fluorodeoxyglucose Positron Emission Tomography Predicts Recurrence in Resected Pancreatic Ductal Adenocarcinoma

BACKGROUND

We aimed to determine whether treatment should be stratified according to 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) maximum standardized uptake values (SUV_max) in pancreatic ductal adenocarcinoma.

METHODS

Patients who underwent preoperative 18F-FDG PET/CT between 2006 and 2014 (n = 138) were stratified into high (≥ 4.85) and low (< 4.85) PET groups. The clinicopathological characteristics and prognostic outcomes were analyzed retrospectively.

RESULTS

The primary tumor SUV_max was positively correlated with preoperative CA19-9 levels (P < 0.001). The high PET group failed to achieve postoperative CA19-9 normalization (P = 0.014). Disease-specific (P < 0.001), recurrence-free (P < 0.001), liver recurrence-free (P < 0.001), and peritoneal recurrence-free (P = 0.020) survivals were significantly shorter in the high PET group. The primary tumor SUV_max was an independent predictive risk factor for liver metastasis (hazard ratio 3.46, 95% confidence interval 1.61-7.87; P = 0.001) and peritoneal recurrence (hazard ratio 3.36, 95% confidence interval 1.18-10.89; P = 0.023).

CONCLUSIONS

Surgical resection failed to achieve CA19-9 normalization in the high PET group and distant recurrence was frequent. This suggests the potential for residual cancer at distant sites, even after curative resection. Stronger preoperative systemic chemotherapy is preferred for the high PET group patients.

Imaging modalities for characterising focal pancreatic lesions

BACKGROUND

Increasing numbers of incidental pancreatic lesions are being detected each year. Accurate characterisation of pancreatic lesions into benign, precancerous, and cancer masses is crucial in deciding whether to use treatment or surveillance. Distinguishing benign lesions from precancerous and cancerous lesions can prevent patients from undergoing unnecessary major surgery. Despite the importance of accurately classifying pancreatic lesions, there is no clear algorithm for management of focal pancreatic lesions.

OBJECTIVES

To determine and compare the diagnostic accuracy of various imaging modalities in detecting cancerous and precancerous lesions in people with focal pancreatic lesions.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Embase, and Science Citation Index until 19 July 2016. We searched the references of included studies to identify further studies. We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We planned to include studies reporting cross-sectional information on the index test (CT (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography), EUS (endoscopic ultrasound), EUS elastography, and EUS-guided biopsy or FNA (fine-needle aspiration)) and reference standard (confirmation of the nature of the lesion was obtained by histopathological examination of the entire lesion by surgical excision, or histopathological examination for confirmation of precancer or cancer by biopsy and clinical follow-up of at least six months in people with negative index tests) in people with pancreatic lesions irrespective of language or publication status or whether the data were collected prospectively or retrospectively.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the references to identify relevant studies and extracted the data. We planned to use the bivariate analysis to calculate the summary sensitivity and specificity with their 95% confidence intervals and the hierarchical summary receiver operating characteristic (HSROC) to compare the tests and assess heterogeneity, but used simpler models (such as univariate random-effects model and univariate fixed-effect model) for combining studies when appropriate because of the sparse data. We were unable to compare the diagnostic performance of the tests using formal statistical methods because of sparse data.

MAIN RESULTS

We included 54 studies involving a total of 3,196 participants evaluating the diagnostic accuracy of various index tests. In these 54 studies, eight different target conditions were identified with different final diagnoses constituting benign, precancerous, and cancerous lesions. None of the studies was of high methodological quality. None of the comparisons in which single studies were included was of sufficiently high methodological quality to warrant highlighting of the results. For differentiation of cancerous lesions from benign or precancerous lesions, we identified only one study per index test. The second analysis, of studies differentiating cancerous versus benign lesions, provided three tests in which meta-analysis could be performed. The sensitivities and specificities for diagnosing cancer were: EUS-FNA: sensitivity 0.79 (95% confidence interval (CI) 0.07 to 1.00), specificity 1.00 (95% CI 0.91 to 1.00); EUS: sensitivity 0.95 (95% CI 0.84 to 0.99), specificity 0.53 (95% CI 0.31 to 0.74); PET: sensitivity 0.92 (95% CI 0.80 to 0.97), specificity 0.65 (95% CI 0.39 to 0.84). The third analysis, of studies differentiating precancerous or cancerous lesions from benign lesions, only provided one test (EUS-FNA) in which meta-analysis was performed. EUS-FNA had moderate sensitivity for diagnosing precancerous or cancerous lesions (sensitivity 0.73 (95% CI 0.01 to 1.00) and high specificity 0.94 (95% CI 0.15 to 1.00), the extremely wide confidence intervals reflecting the heterogeneity between the studies). The fourth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (dysplasia) provided three tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing invasive carcinoma were: CT: sensitivity 0.72 (95% CI 0.50 to 0.87), specificity 0.92 (95% CI 0.81 to 0.97); EUS: sensitivity 0.78 (95% CI 0.44 to 0.94), specificity 0.91 (95% CI 0.61 to 0.98); EUS-FNA: sensitivity 0.66 (95% CI 0.03 to 0.99), specificity 0.92 (95% CI 0.73 to 0.98). The fifth analysis, of studies differentiating cancerous (high-grade dysplasia or invasive carcinoma) versus precancerous (low- or intermediate-grade dysplasia) provided six tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing cancer (high-grade dysplasia or invasive carcinoma) were: CT: sensitivity 0.87 (95% CI 0.00 to 1.00), specificity 0.96 (95% CI 0.00 to 1.00); EUS: sensitivity 0.86 (95% CI 0.74 to 0.92), specificity 0.91 (95% CI 0.83 to 0.96); EUS-FNA: sensitivity 0.47 (95% CI 0.24 to 0.70), specificity 0.91 (95% CI 0.32 to 1.00); EUS-FNA carcinoembryonic antigen 200 ng/mL: sensitivity 0.58 (95% CI 0.28 to 0.83), specificity 0.51 (95% CI 0.19 to 0.81); MRI: sensitivity 0.69 (95% CI 0.44 to 0.86), specificity 0.93 (95% CI 0.43 to 1.00); PET: sensitivity 0.90 (95% CI 0.79 to 0.96), specificity 0.94 (95% CI 0.81 to 0.99). The sixth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (low-grade dysplasia) provided no tests in which meta-analysis was performed. The seventh analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) provided two tests in which meta-analysis was performed. The sensitivity and specificity for diagnosing cancer were: CT: sensitivity 0.83 (95% CI 0.68 to 0.92), specificity 0.83 (95% CI 0.64 to 0.93) and MRI: sensitivity 0.80 (95% CI 0.58 to 0.92), specificity 0.81 (95% CI 0.53 to 0.95), respectively. The eighth analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) or benign lesions provided no test in which meta-analysis was performed.There were no major alterations in the subgroup analysis of cystic pancreatic focal lesions (42 studies; 2086 participants). None of the included studies evaluated EUS elastography or sequential testing.

AUTHORS' CONCLUSIONS

We were unable to arrive at any firm conclusions because of the differences in the way that study authors classified focal pancreatic lesions into cancerous, precancerous, and benign lesions; the inclusion of few studies with wide confidence intervals for each comparison; poor methodological quality in the studies; and heterogeneity in the estimates within comparisons.

18F-FLT PET imaging of cellular proliferation in pancreatic cancer

Pancreatic ductal adenocarcinoma is known for its poor prognosis. Since the development of computerized tomography, magnetic resonance and endoscopic ultrasound, novel imaging techniques have struggled to get established in the management of patients diagnosed with pancreatic adenocarcinoma for several reasons. Thus, imaging assessment of pancreatic cancer remains a field with scope for further improvement. In contrast to cross-sectional anatomical imaging methods, molecular imaging modalities such as positron emission tomography (PET) can provide information on tumour function. Particularly, tumour proliferation may be assessed by measurement of intracellular thymidine kinase 1 (TK1) activity level using thymidine analogues radiolabelled with a positron emitter for use with PET. This approach, has been widely explored with [(18)F]-fluoro-3'-deoxy-3'-L-fluorothymidine ((18)F-FLT) PET. This manuscript reviews the rationale and physiology behind (18)F-FLT PET imaging, with special focus on pancreatic cancer and other gastrointestinal malignancies. Potential benefit and challenges of this imaging technique for diagnosis, staging and assessment of treatment response in abdominal malignancies are discussed.

Value of 18F-fluorodeoxyglucose positron emission tomography and 18F-fluorodeoxyglucose positron emission tomography/computed tomography in diagnosis of pancreatic cancer: A systemic review and meta-analysis

AIM: To evaluate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) and ¹⁸F-FDG PET/computed tomography (CT) in the diagnosis of pancreatic cancer.

METHODS: Medline, EMBASE, Science Direct, Springer link, CBM, Cnki, Wan fang and VIP databases were searched by computer before April 1, 2015 to retrieve articles on the study of ¹⁸F-FDG PET and ¹⁸F-FDG PET/CT in diagnosing pancreatic cancer. Studies were selected according to the inclusion and exclusion criteria, and quality assessment was made using the QUADAS scale. Meta-Disc 1.4 software was used to analyze the heterogeneity of the included articles, and the SROC curve was plotted to calculate the pooled sensitivity and specificity. The publication bias was assessed with Stata 12.0 software.

RESULTS: A total of 51 English-language articles were included. The summary sensitivity and specificity of ¹⁸F-FDG PET in diagnosing pancreatic cancer were 87% (95%CI: 85%-89%) and 78% (95%CI: 74%-81%), respectively. The positive and negative likelihood ratios were 3.38 (95%CI: 2.64-4.33) and 0.18 (95%CI: 0.14-0.23), respectively. The diagnostic odds ratio (DOR) was 21.91 (95%CI: 14.15-33.93), and the area under the SROC curve was 0.8930. The summary sensitivity and specificity of ¹⁸F-FDG PET/CT in diagnosing pancreatic cancer were 91% (95%CI: 88%-93%) and 77% (95%CI: 72%-82%), respectively. The positive and negative likelihood ratios were 3.57 (95%CI: 2.96-4.31) and 0.14 (95%CI: 0.11-0.18), respectively. The DOR was 28.52 (95%CI: 19.63-41.42), and the area under the SROC curve was 0.9315.

CONCLUSION: ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET have higher diagnostic value than CT in diagnosing pancreatic cancer. ¹⁸F-FDG PET/CT is superior to ¹⁸F-FDG PET in terms of sensitivity and both of them can be used as diagnostic tools for pancreatic cancer with negative traditional examinations.

Site-specifically labeled CA19.9-targeted immunoconjugates for the PET, NIRF, and multimodal PET/NIRF imaging of pancreatic cancer

Molecular imaging agents for preoperative positron emission tomography (PET) and near-infrared fluorescent (NIRF)-guided delineation of surgical margins could greatly enhance the diagnosis, staging, and resection of pancreatic cancer. PET and NIRF optical imaging offer complementary clinical applications, enabling the noninvasive whole-body imaging to localize disease and identification of tumor margins during surgery, respectively. We report the development of PET, NIRF, and dual-modal (PET/NIRF) imaging agents, using 5B1, a fully human monoclonal antibody that targets CA19.9, a well-established pancreatic cancer biomarker. Desferrioxamine (DFO) and/or a NIRF dye (FL) were conjugated to the heavy-chain glycans of 5B1, using a robust and reproducible site-specific (ss) labeling methodology to generate three constructs ((ss)DFO-5B1, (ss)FL-5B1, and (ss)dual-5B1) in which the immunoreactivity was not affected by the conjugation of either label. Each construct was evaluated in a s.c. xenograft model, using CA19.9-positive (BxPC3) and -negative (MIAPaCa-2) human pancreatic cancer cell lines. Each construct showed exceptional uptake and contrast in antigen-positive tumors with negligible nonspecific uptake in antigen-negative tumors. Additionally, the dual-modal construct was evaluated in an orthotopic murine pancreatic cancer model, using the human pancreatic cancer cell line, Suit-2. The (ss)dual-5B1 demonstrated a remarkable capacity to delineate metastases and to map the sentinel lymph nodes via tandem PET-computed tomography (PET/CT) and NIRF imaging. Fluorescence microscopy, histopathology, and autoradiography were performed on representative sections of excised tumors to visualize the distribution of the constructs within the tumors. These imaging tools have tremendous potential for further preclinical research and for clinical translation.

Pretargeted Immuno-PET of Pancreatic Cancer: Overcoming Circulating Antigen and Internalized Antibody to Reduce Radiation Doses

5B1 is a fully human, monoclonal antibody that has shown promise for the PET imaging of cancers expressing carbohydrate antigen 19.9 (CA19.9)--a carbohydrate prevalent in cells with aberrant glycosylation and an established effector of metastasis. The long physiologic half-life of the antibody and interference from circulating CA19.9 may increase the time required to generate quality images as well as the risk of radiation exposure to healthy tissues during repeated PET imaging. Pretargeting methodologies are an effective approach to expeditiously acquire PET images, but in this case, the pretargeting approach is complicated by the internalization of 5B1 by CA19.9-expressing cells. We sought to adapt and optimize a pretargeting strategy that exploits the bioorthogonal reaction between transcyclooctene (TCO) and tetrazine (Tz) to overcome these complications.

METHODS

5B1 was modified with TCO, and a novel NOTA-PEG7-Tz radioligand was synthesized with the goal of improving on a previously reported analog. BxPC3 and Capan-2 cells were evaluated for their ability to internalize anti-CA19.9 antibodies using a fluorometric assay, and xenografts of the same lines were used for in vivo studies. The pretargeting approach was optimized, and the 2 radioligands were compared using biodistribution and PET imaging in murine models of pancreatic cancer.

RESULTS

BxPC3 and Capan-2 cells were shown to rapidly internalize anti-CA19.9 monoclonal antibodies, including 5B1. (64)Cu-NOTA-PEG7-Tz showed improved in vivo pharmacokinetics relative to (64)Cu-NOTA-Tz using 5B1-TCO as the targeting vector. PET imaging and biodistribution studies showed that injecting the radioligand 72 h after the administration of 5B1-TCO resulted in the best uptake (8.2 ± 1.7 percentage injected dose per gram at 20 h after injection) and tumor-to-background activity concentration ratios. Dosimetry calculations revealed that the pretargeting system produced a greater than 25-fold reduction in total body radiation exposure relative to (89)Zr-desferrioxamine-5B1. PET/CT imaging in an orthotopic Capan-2 xenograft model--which secretes large amounts of CA19.9 and more rapidly internalizes anti-CA19.9 antibodies--showed that this approach is viable even in the difficult circumstances presented by a circulating antigen and internalized targeting vector.

CONCLUSION

The 5B1-TCO and (64)Cu-NOTA-PEG7-Tz system evaluated in these studies can delineate CA19.9-positive xenografts in murine models of pancreatic cancer despite the challenges posed by the combination of circulating antigen and internalization of the 5B1-TCO.

Pilot study: Evaluation of dual-energy computed tomography measurement strategies for positron emission tomography correlation in pancreatic adenocarcinoma

We sought to determine whether dual-energy computed tomography (DECT) measurements correlate with positron emission tomography (PET) standardized uptake values (SUVs) in pancreatic adenocarcinoma, and to determine the optimal DECT imaging variables and modeling strategy to produce the highest correlation with maximum SUV (SUVmax). We reviewed 25 patients with unresectable pancreatic adenocarcinoma seen at Mayo Clinic, Scottsdale, Arizona, who had PET-computed tomography (PET/CT) and enhanced DECT performed the same week between March 25, 2010 and December 9, 2011. For each examination, DECT measurements were taken using one of three methods: (1) average values of three tumor regions of interest (ROIs) (method 1); (2) one ROI in the area of highest subjective DECT enhancement (method 2); and (3) one ROI in the area corresponding to PET SUVmax (method 3). There were 133 DECT variables using method 1, and 89 using the other methods. Univariate and multivariate analysis regression models were used to identify important correlations between DECT variables and PET SUVmax. Both R2 and adjusted R2 were calculated for the multivariate model to compensate for the increased number of predictors. The average SUVmax was 5 (range, 1.8-12.0). Multivariate analysis of DECT imaging variables outperformed univariate analysis (r = 0.91; R2 = 0.82; adjusted R2 = 0.75 vs. r < 0.58; adjusted R2 < 0.34). Method 3 had the highest correlation with PET SUVmax (R2 = 0.82), followed by method 1 (R2 = 0.79) and method 2 R2 = 0.57). DECT thus has clinical potential as a surrogate for, or as a complement to, PET in patients with pancreatic adenocarcinoma.

Usefulness of F-18-fluorodeoxyglucose positron emission tomography to confirm suspected pancreatic cancer: a meta-analysis

INTRODUCTION

Pancreatic cancer is among the five most lethal malignancies in the world. Unfortunately, many malignant tumors go undetected by the current primary diagnostic tools. (18)FDG-PET and (18)FDG-PET/CT might be useful to confirm suspected pancreatic cancer.

METHODS

A meta-analysis was performed using all major search engines. Methodological quality of included studies was assessed as well as quality of the PET-protocol. The following pooled estimates served as primary outcome measures: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

RESULTS

Thirty-five studies were included. Pooled estimates for (18)FDG-PET were: sensitivity 90%, specificity 76%, PPV 90%, NPV 76% and accuracy 86%. Pooled estimates for (18)FDG-PET/CT were: sensitivity 90%, specificity 76%, PPV 89%, NPV 78% and accuracy 86%. The pooled sensitivity and specificity for (18)FDG-PET to differentiate between pancreatic cancer and chronic pancreatitis were 90% and 84%, respectively.

CONCLUSION

Both (18)FDG-PET and (18)FDG-PET/CT offer no benefit over the current primary diagnostic tools in diagnosing pancreatic cancer. However, the (18)FDG-PET/CT systems are still improving. We should investigate the sensitivity and specificity of these new systems while reevaluating the tradeoff between false positive and false negative results. Yet, (18)FDG-PET/CT may have a role in the staging of pancreatic cancer, in survival prediction, and may add to other diagnostic information, like histology.

The role of 18F-fluorodeoxyglucose positron emission tomography in the management of patients with pancreatic adenocarcinoma

Pancreatic cancer continues to have a grim prognosis with 5-year survival rates at less than 5 %. It is a particularly challenging health problem given these poor survival outcomes, aggressive tumor biology, and late onset of symptoms. Most patients present with advanced unresectable cancer however, margin-negative resection provides a rare chance for cure for patients with resectable disease. The standard imaging modality for the diagnosis and management of pancreatic cancer is contrast-enhanced multidetector computed tomography. Remarkable advances in CT technology have led to improvements in the ability to detect small tumors and intricate vasculature involvement by the tumor, yet CT is still restricted to providing a morphological portrait of the tumor. Diagnosis can be challenging due to similar appearance of certain benign and malignant disease. Distant metastatic disease can be silent on CT leading to improper staging, and thus management, of certain patients. Furthermore, radiation-induced fibrosis and necrosis complicate assessment of treatment response by CT alone. F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is becoming a prevalent tool employed by physicians to improve accuracy in these clinical scenarios. Malignant transformation causes a high metabolic activity of cancer cells. 18F-FDG-PET captures this functional activity of malignancies by capturing areas with high glucose utilization rates. Imaging function rather than morphological appearance, 18F-FDG-PET has a unique role in the management of oncology patients with the ability to detect regions of tumor involvement that may be silent on conventional imaging. Literature on the sensitivity and specificity of 18F-FDG-PET fails to reach a consensus, and improvements resulting in hybridization of 18F-FDG-PET and CT imaging techniques are preliminary. Here we review the potential role of 18F-FDG-PET and PET/CT in improving accuracy in the initial evaluation and subsequent steps in the management of pancreatic cancer patients.

Comparison of F-18-FDG PET/CT findings between pancreatic solid pseudopapillary tumor and pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic solid pseudopapillary tumor (SPT) is a rare benign tumor. Little data are available on positron emission tomographic/computed tomographic (PET/CT) characteristics of this tumor. Therefore, we analyzed the metabolic characteristics of SPT using F-18-FDG PET/CT and compared the results with those of pancreatic ductal adenocarcinoma.

METHODS

We retrospectively reviewed the records of 11 SPT patients and 46 patients with ductal adenocarcinoma. Ten SPT patients had primary tumors and 1 patient had metastatic SPT. Maximum standardized uptake value (max SUV), mean SUV, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor-to-background ratio (TBR) were evaluated. Mann-Whitney U test between pancreatic SPT and ductal adenocarcinoma was performed. In addition, age, gender and tumor size-adjusted analysis of covariance (ANCOVA) was done between pancreatic SPT and ductal adenocarcinoma.

RESULTS

Compared with pancreatic ductal adenocarcinomas, SPTs had significantly higher tumor size-adjusted MTV and TLG. MTV and TLG values were significantly correlated with T-stage of the SPTs. In 1 SPT patient, metastases in the liver and mesentery were revealed by intense uptake of FDG on F-18-FDG PET/CT, and after PET/CT had suggested the presence of pancreatic SPT.

CONCLUSION

We recommend that SPT be considered when a solid pancreatic mass with increased FDG metabolism is encountered on PET/CT. F-18-FDG PET/CT may be useful in detecting subtle metastases of SPT.

FDG-PET in diagnosis, staging and prognosis of pancreatic carcinoma: A meta-analysis

AIM: To investigate the potential role of positron emission tomography (PET) in the diagnosis, staging and prognosis predicting of pancreatic carcinoma (PC).

METHODS: A systematic review of relevant literatures in PubMed, Embase and Cochrane Library was performed. The sensitivity and specificity of diagnostic and staging studies, and HRs for prognosis predicting studies were pooled. The bivariate model was used for diagnostic studies and the random-effect model for prognostic studies. Heterogeneity between included studies was tested using χ² test, and subgroup analysis was performed to explain the heterogeneities. All of the calculations were performed using Stata version 11.0.

RESULTS: A total of 39 studies were included. The pooled sensitivity of PET in diagnosing PC (30 studies, 1582 patients), evaluating N stating (4 studies, 101 patients) and liver metastasis (7 studies, 316 patients) were 0.91 (95%CI: 0.88-0.93), 0.64 (95%CI: 0.50-0.76), and 0.67 (95%CI: 0.52-0.79), respectively; and the corresponding specificity was 0.81 (95%CI: 0.75-0.85), 0.81 (95%CI: 0.25-0.85), and 0.96 (95%CI: 0.89-0.98), respectively. In prognosis analysis (6 studies, 198 patients), significant difference of overall survival was observed between high and low standardized uptake value groups (HR = 2.39, 95%CI: 1.57-3.63). Subgroup analysis showed that PET/CT was more sensitive than PET alone in evaluating liver metastasis of PC, 0.82 (95%CI: 0.48-0.98) and 0.67 (95%CI: 0.52-0.79), respectively.

CONCLUSION: PET can be used as a valuable diagnostic and predictive tool for PC, but its effect in the staging of PC remains indeterminate.

State-of-the-art PET/CT of the pancreas: current role and emerging indications

Fused positron emission tomography (PET)/computed tomography (CT) is a recently developed technology that couples the functional information of PET with the anatomic details of CT. Integrated PET/CT scanners produce both PET and contrast material-enhanced CT images of the entire body in one setting. Typically, the amount of fluorine 18 (18F) fluorodeoxyglucose (FDG) uptake in normal pancreatic parenchyma is insignificant compared with that of the liver. However, both malignant (eg, adenocarcinoma) and benign (eg, acute pancreatitis) pancreatic conditions may demonstrate intense FDG uptake. PET/CT provides an opportunity to depict pancreatic tumors and distant metastases, perform preoperative staging, and monitor response to treatment, and it has proved useful in distinguishing postoperative fibrosis from recurrence. In selected cases, PET/CT findings may be used to help diagnose autoimmune pancreatitis mimicking a mass by depicting systemic involvement. PET/CT may also be used to direct biopsy to sites more likely to yield representative tumor tissue. Novel radiolabeled molecules, such as sigma-receptor ligands and 18F-3'-fluoro-3'-deoxy-l-thymidine (FLT), may play an even greater role in distinguishing tumor recurrence from postoperative fibrosis or inflammation.

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

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

Pancreatic and hepatobiliary cancers

Morphology-based imaging modalities have replaced classical conventional nuclear medicine modalities for detection of liver or pancreatic lesions. With positron emission tomography and the glucose analog F-18 fluorodeoxyglucose (FDG), a sensitive and specific modality for the detection of hepatic metastases and extrahepatic tumor deposits from hepatocellular or pancreatic cancer is available. F-18 FDG PET can increase the accuracy of staging primary tumors of the liver or the pancreas, and can be used for response monitoring. Radiopharmaceuticals such as Ga-68 DOTATOC and F-18 DOPA allow the specific detection of neuroendocrine pancreatic tumors and their metastatic deposits. Hybrid scanners such as PET-CT integrate morphologic and metabolic information, and allow to increase the sensitivity and specificity of noninvasive imaging in many tumor entities. The development of specific radiopharmaceuticals and technical innovations such as SPECT-CT has increased the reliability of conventional scintigraphic imaging. This chapter focuses on the use of PET-CT in hepatobiliary and pancreatic cancers.

The role of PET scanning in pancreatic cancer

The strength of functional imaging lies in its ability to detect malignant disease irrespective of lesion morphology. In this setting, 18FDG-PET can complement management by providing a more accurate diagnosis. When combined as an adjunct to CT, 18FDG-PET can increase the sensitivity, specificity, and accuracy for detecting a pancreatic malignancy, especially in patients in whom CT alone fails to identify a discrete mass or in whom biopsy results are indeterminate. This capability is accentuated with small lesions of the pancreas. 18FDG-PET is significantly more sensitive in detecting metastatic disease than conventional CT imaging. Moreover, 18FDG-PET is able to differentiate tumor response to therapy in the postoperative setting, and could potentially serve to monitor recurrence patterns in the setting of neoadjuvant or adjuvant chemoradiotherapy. Finally, as 18FDG-PET/CT fusion modalities become more widespread and technical advances in image acquisition progress, 18FDG-PET will continue to have an increasing role in the diagnosis, staging, and surveillance of pancreatic cancer, integrating anatomic information with functional imaging.

Preoperative 18[F]-fluorodeoxyglucose positron emission tomography/computed tomography predicts early recurrence after pancreatic cancer resection

BACKGROUND

An important step in deciding the treatment strategy for pancreatic cancer is to preoperatively predict the possibility of early recurrence. We reviewed whether 18[F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) before pancreatic cancer resection could predict tumor recurrence in the early postoperative period.

METHODS

FDG-PET/CT was performed preoperatively on 56 patients with pancreatic cancer. The maximum standardized uptake (SUV(max)) values obtained by FDG-PET/CT were compared between two groups: patients with and without recurrence within the first 6 postoperative months. SUV(max) analyses were also performed to determine whether age, sex, CA 19-9 values, the operative method, and portal vein resection were also predictive of recurrence within less than 6 months after tumor resection.

RESULTS

The median SUV(max) values of the recurrence group and no-recurrence group were 7.9 and 4.2, respectively (P = 0.0042). The SUV(max) was the only risk factor for recurrence in the first 6 postoperative months identified by multivariate analysis (P = 0.0062).

CONCLUSIONS

Preoperative SUV(max) was higher in the recurrence group during the early postoperative period, and a high SUV(max) was a risk factor for early postoperative recurrence. Based on these results, we conclude that FDG-PET/CT is predictive of the recurrence of pancreatic cancer in the early postoperative period.

Imaging techniques in pancreatic tumors

Conventional ultrasonography represents the first diagnostic imaging modality for the study of pancreatic tumors. Contrast-enhanced ultrasound has significantly improved the accuracy of first-line examination and may influence the choice of second-line investigations: multidetector computed tomography is considered the gold standard for studying pancreatic solid lesions and tumor staging, while MRI with magnetic resonance cholangiopancreatography allows better study of pancreatic cystic lesions and the ductal system. To definitely diagnose a pancreatic lesion, image-guided fine-needle-aspiration or biopsy are very often required. PET with 18-fluorodeoxyglucose, endoscopic ultrasound and intraoperative ultrasonography remain techniques often employed in the third line. This article reviews the imaging techniques generally used for diagnosing the main pancreatic tumors, and a work-up algorithm is finally proposed.

18 F-FDG PET/CT influences management in patients with known or suspected pancreatic cancer

BACKGROUND

The aims of this study were (i) to assess and validate the incremental information of positron emission tomography/computed tomography (PET/CT) over conventional staging investigations (CSI) and (ii) to assess the management impact of PET/CT in patients with known or suspected pancreatic cancer.

METHODS

Between October 2007 and September 2008, 22 PET/CT scans were performed using a dedicated PET/CT scanner in 21 patients with known or suspected pancreatic cancer. Follow up was used to reconcile discordance between PET/CT and CSI. The pre-PET/CT management plan and/or intent were prospectively recorded in all scans. The post-PET/CT management plan was determined from the medical record and/or discussions with treating clinicians. The management impact of PET/CT was classified as high, medium, low or none defined using Australian and New Zealand Association of Physicians in Nuclear Medicine PET data collection project criteria.

RESULTS

PET/CT and CSI were discordant in 14/22 (64%: 95% CI; 43-84%) scans. Of the 14 discordant scans, PET/CT assessment was correct in eight, conventional imaging in four and there was insufficient information in two. Overall, PET/CT management impact was classified as high (n= 6), medium (n= 3), low (n= 9) or none (n= 4). Significant changes in management (high or medium impact) were induced by PET/CT in 9/22 scans (41%: 95% CI; 20-62%) predominantly by correctly modifying the disease extent.

CONCLUSION

PET/CT has an incremental benefit over CSI and has a significant impact on management in patients with known or suspected pancreatic cancer. PET/CT merits consideration as part of the non-invasive evaluation of patients with known or suspected pancreatic cancer.

Usefulness of 18F-FDG PET, combined FDG-PET/CT and EUS in diagnosing primary pancreatic carcinoma: a meta-analysis

The aim was to evaluate the diagnostic value of (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG PET), combined (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography ((18)F-FDG PET/CT) and endoscopic ultrasonography (EUS) in diagnosing patients with pancreatic carcinoma. MEDLINE, EMBASE, Cochrane library and some other databases, from January 1966 to April 2009, were searched for initial studies. All the studies published in English or Chinese relating to the diagnostic value of (18)F-FDG PET, PET/CT and EUS for patients with pancreatic cancer were collected. Methodological quality was assessed. The statistic software called "Meta-Disc 1.4" was used for data analysis.

RESULTS

51 studies were included in this meta-analysis. The pooled sensitivity estimate for combined PET/CT (90.1%) was significantly higher than PET (88.4%) and EUS (81.2%). The pooled specificity estimate for EUS (93.2%) was significantly higher than PET (83.1%) and PET/CT (80.1%). The pooled DOR estimate for EUS (49.774) was significantly higher than PET (32.778) and PET/CT (27.105). SROC curves for PET/CT and EUS showed a little better diagnostic accuracy than PET alone. For PET alone, when interpreted the results with knowledge of other imaging tests, its sensitivity (89.4%) and specificity (80.1%) were closer to PET/CT. For EUS, its diagnostic value decreased in differentiating pancreatic cancer for patients with chronic pancreatitis. In conclusion, PET/CT was a high sensitive and EUS was a high specific modality in diagnosing patients with pancreatic cancer. PET/CT and EUS could play different roles during different conditions in diagnosing pancreatic carcinoma.

Is (18)F-fluorodeoxyglucose positron emission tomography meaningful for estimating the efficacy of corticosteroid therapy in patients with autoimmune pancreatitis?

BACKGROUND

Autoimmune pancreatitis (AIP) is often misdiagnosed as pancreatic cancer (PC). Both conditions accumulate (18)F-fluorodeoxyglucose (FDG), so FDG positron emission tomography (FDG-PET) is not discriminatory. This study aimed to evaluate the pattern of FDG accumulation, and the change in FDG uptake after steroid treatment in AIP and PC.

METHODS

We compared FDG-PET patterns between 18 patients with AIP and 20 patients with PC, and also evaluated the short-term changes in FDG uptake after steroid therapy.

RESULTS

FDG uptake was observed in 88.9% in AIP and 90.0% in PC. FDG uptake in extra-abdominal lymph nodes was seen more frequently in AIP, and uptake in salivary glands, eyes and biliary ducts was seen only in AIP. Follow-up PET was performed in 6 AIP patients and in 3 PC patients. Changes in SUV(max) after steroid therapy were estimated within 1 week in 5 AIP patients and in all 3 PC patients, retrospectively. In 4 AIP patients, the change in SUV(max) was more than 10%. On the other hand, in PC, SUV(max) increased or remained almost unchanged (within 10%).

CONCLUSIONS

FDG-PET pattern at baseline, and a decrease in FDG uptake after a short steroid trial can be useful for discriminating AIP from PC.

Surgical outcome of solid pseudopapillary tumor of the pancreas

BACKGROUND/PURPOSE

The best surgical treatment for solid pseudopapillary tumor of the pancreas is a matter of debate.

METHODS

Fourteen patients with solid pseudopapillary tumor of the pancreas who underwent surgical resection, including enucleation, between June 1996 and January 2007 were retrospectively analyzed to evaluate the effect of the treatment.

RESULTS

The mean age of the patients was 39 years (range, 15 to 59 years). The mean size of the tumor was 4.4 cm (range, 2.0 to 12 cm). Ten tumors (71%) had a well-defined capsule, and 6 tumors (43%) extended beyond the pancreas. Eight of the 14 tumors (57%) had a cystic component, and calcification was observed in 6 tumors (43%). The frequency of microscopic venous invasion, lymphatic invasion, and nerve invasion was 29% (4 of 14), 0%, and 21% (3 of 14), respectively. No lymph node involvement or liver metastasis was observed. Six patients underwent positron emission tomography with 2-deoxy-2-[(18)F] fluoro-D-glucose (FDG), and stronger FDG accumulation compared with the surrounding pancreatic parenchyma was observed in 5 of the 6 patients. The median standardized uptake value (SUV) was 6.3 (range, 0.9 to 42.8). Distal pancreatectomy (n = 5), subtotal stomach-preserving pancreatoduodenectomy (n = 3), local resection (n = 3), enucleation (n = 2), and duodenum-preserving pancreatic head resection (n = 1) were performed. Overall morbidity and mortality rates were 43% and 0%, respectively. All patients were still alive without recurrent disease after a median follow-up of 46 months.

CONCLUSIONS

Patients with solid pseudopapillary tumor of the pancreas had a favorable outcome after surgical treatment, including enucleation.

Nonfunctioning endocrine pancreatic tumor examined with 18F-FDG PET/CT

A 71-year-old woman with type 2 diabetes mellitus complained of generalized fatigue. A 36-mm tumor in the pancreatic tail was detected with ultrasonography. The tumor was found to have marked hypervascularity with contrast-enhanced computed tomography (CT) and magnetic resonance. Combined (18)F-fluorodeoxyglucose positron emission tomography and CT ((18)F-FDG PET/CT) showed (18)F-FDG by the tumor with a maximal standardized uptake value of 2.98 at 50 min and 3.29 at 100 min following injection of (18)F-FDG. (18)F-FDG PET/CT suggested no extrapancreatic spread of the tumor. The patient had no pancreatic hormone-associated symptoms. Distal pancreatectomy was performed, and a well-differentiated endocrine tumor was diagnosed. The resected specimen showed neither infiltration of adjacent structures nor metastasis to regional lymph nodes. The present case suggests that (18)F-FDG PET/CT is a reliable modality for staging endocrine pancreatic tumors.

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

AIM: To evaluate the role of positron emission tomo-graphy using 18F-fluorodeoxyglucose (FDG-PET) in the surgical management of patients with pancreatic cancer, including the diagnosis, staging, and selection of patients for the subsequent surgical treatment.

METHODS: This study involved 53 patients with proven primary pancreatic cancer. The sensitivity of diagnosing the primary cancer was examined for FDG-PET, CT, cytological examination of the bile or pancreatic juice, and the serum levels of carcinoembrionic antigens (CEA) and carbohydrate antigen 19-9 (CA19-9). Next, the accuracy of staging was compared between FDG-PET and CT. Finally, FDG-PET was analyzed semiquantitatively using the standard uptake value (SUV). The impact of the SUV on patient management was evaluated by examining the correlations between the SUV and the histological findings of cancer.

RESULTS: The sensitivity of FDG-PET, CT, cytological examination of the bile or pancreatic juice, and the serum levels of CEA and CA19-9 were 92.5%, 88.7%, 46.4%, 37.7% and 69.8%, respectively. In staging, FDG-PET was superior to CT only in diagnosing distant disease (bone metastasis). For local staging, the sensitivity of CT was better than that of FDG-PET. The SUV did not correlate with the pTNM stage, grades, invasions to the vessels and nerve, or with the size of the tumor. However, there was a statistically significant difference (4.6 ± 2.9 vs 7.8 ± 4.5, P = 0.024) in the SUV between patients with respectable and unresectable disease.

CONCLUSION: FDG-PET is thus considered to be useful in the diagnosis of pancreatic cancer. However, regarding the staging of the disease, FDG-PET is not considered to be a sufficiently accurate diagnostic modality. Although the SUV does not correlate with the patho-histological prognostic factors, it may be useful in selecting patients who should undergo subsequent surgical treatment.

Nuclear medical methods for the diagnosis of pancreatic cancer: positron emission tomography

The functional imaging approach of nuclear medicine offers important information for the characterization of a tumor's pathobiology. In oncology, positron emission tomography (PET) especially has had great impact on the staging of tumor patients and the assessment of therapy. Both the development of new, tumor-specific, tracers and the introduction of by software- and hardware-driven image fusion emphasize the potential of this modality for an all-embracing diagnostic modality.

The efficacy of whole-body FDG-PET or PET/CT for autoimmune pancreatitis and associated extrapancreatic autoimmune lesions

PURPOSE

The aim of this study was to evaluate retrospectively the efficacy of whole-body (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) for autoimmune pancreatitis (AIP) and associated extrapancreatic autoimmune lesions.

METHODS

Whole-body FDG-PET or PET/computed tomography (CT) findings were reviewed in six patients with AIP. The initial PET scans were performed 1 h and 2 h after FDG injection in all six patients. Follow-up PET scans were performed during or following steroid therapy in five patients and in one patient who did not have steroid therapy.

RESULTS

The initial PET scans revealed intense FDG uptake by AIP in all six patients. The maximum standardized uptake value (SUVmax) increased in four patients and was stable in two patients. The intense uptake in the pancreas disappeared during or following steroid therapy in five patients and in one patient who showed spontaneous remission of AIP. Abnormal FDG uptake by extrapancreatic autoimmune diseases was observed in five of the six patients: sclerosing sialadenitis (n = 5), lymphadenopathy (n = 5), retroperitoneal fibrosis (n = 2), interstitial nephritis (n = 2) and sclerosing cholecystitis (n = 1). Abnormal FDG uptake disappeared in the salivary glands (n = 4), lymph nodes (n = 4), retroperitoneum (n = 2), kidneys (n = 1) and gallbladder (n = 1) during or following steroid therapy and remained in the salivary glands and lymph nodes of a spontaneous remission patient.

CONCLUSION

These results suggest that whole-body FDG-PET may be useful for detecting AIP and associated extrapancreatic autoimmune lesions and for monitoring their disease activity but that dual time point imaging may not be useful for differentiating malignancy from AIP.

The role of positron emission tomography in the management of pancreatic cancer

The role of positron emission tomography (PET) and PET/computed tomography (CT) in the assessment of a patient presenting with cancer of the pancreas is discussed in the overall context of the management of this condition. The clinical limitations persist, with many patients presenting late with unresectable disease and poor prospects for novel drug therapies. PET and PET/CT are best at diagnosing and staging but are relatively inefficient in the detection of nodal disease. The detection of late disease manifestations such as metastatic spread is often of little clinical consequence. PET/CT may be considered as a first-line imaging investigation but evidence for this approach needs to accrue. Overall detection sensitivity at diagnosis varies between 90% and 95% and specificity from 82% to 100%, whereas for staging, sensitivity data vary from 61% to 100% and specificity data from 67% to 100%.

Impact of FDG-PET/MRI image fusion on the detection of pancreatic cancer

BACKGROUND

This study assessed the value of image fusion with (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) in patients suspected of having pancreatic cancer.

METHODS

32 patients (12 women, 20 men; age 24-79 years; mean 56.6 years) were included. All patients underwent whole-body FDG-PET examinations and contrast-enhanced MRI. Image fusion used a semiautomatic voxel-based algorithm. Separate reading, side-by-side analysis and evaluation of fused PET/MRI images were performed. Results were correlated to histopathology (n = 30), or clinical follow-up (n = 2).

RESULTS

15/32 patients had pancreas cancer and 17/32 patients benign disease. The sensitivity and specificity for cancer detection by FDG-PET were 93 and 41% for visual and 86 and 58% for semiquantitative analysis whereas MRI achieved 100 and 76% respectively. Topographical assignment of PET foci by image fusion was superior to side-by-side analysis in 11/39 (28%) foci (in 8/32 patients). However, a true impact on therapeutic strategy was observed only in 1/8 patients as the presence of multiple metastases, irresectable primaries or medical reasons for inoperability prevented a curative setting.

CONCLUSION

Compared to side-by-side analysis, PET/MRI image fusion improves the anatomical assignment and interpretation of FDG foci. The therapeutic benefit for the patient however is limited in patients with multiple lesions or incurable primaries.

Positron emission tomography: clinical applications in oncology. Part 2

This review continues from a previous review on this topic, which was published in the December issue. In that review, the role of positron emission tomography in lung cancer, lymphoma, breast cancer, head and neck cancer, gastroesophageal cancer, colorectal cancer, malignant melanoma, bone tumors and ovarian cancer was discussed. In this review, the role of positron emission tomography in other malignancies, such as gynecological malignancies other than ovary, pancreatic cancer, hepatocellular cancer, gastrointestinal tumors, urological malignancies, neuroendocrine tumors, adrenocortical tumors, soft-tissue sarcomas, pituitary and brain tumors, is discussed.

2-Deoxy-2-[F-18]fluoro-d-glucose-Positron Emission Tomography Sensitivity to Serum Glucose: A Survey and Diagnostic Applications

OBJECTIVE

The positron emission tomography (PET) clinical utility of the sensitivity (gamma) of uptake (Q) to a change in plasma glucose concentration (C) is investigated.

METHODS

Gamma is obtained from data as [ln(Q (2)/Q (1))] / [ln(C(2)/C(1))], using previously published intrapatient studies varying C within a single patient and some interpatient ones. It can be theoretically related to the half-saturation constant in the Michaelis-Menten quantification of competitive uptake. One of its uses is making uptake corrections for desired vs. actual C using Q(2) = Q(1) (C(2)/C(1))(gamma).

RESULTS

Intrapatient studies proved to be preferable to interpatient ones, and a 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET survey with analyses for gamma yielded the following result: usually the gamma values of tumors and brain tissues were near -1, whereas those of other noncerebral tissues were near 0. Regarding correcting uptakes for C, instead of a universally assumed and applied gamma = -1, corrections should be for a single tissue using its known gamma. An advantageous use of gamma is predicting how C affects image contrast, including where glucose loading is sometimes preferable to fasting.

CONCLUSIONS

A potentially useful quantifier of uptake sensitivity to plasma glucose has been defined and values obtained. Correcting uptakes to some standard C requires special care. gamma can help PET clinicians select fasting or loading to achieve glucose levels for optimum contrast.

PET and cancer screening

Various carcinomas are discovered incidentally during FDG PET study. This points to the potential use of PET as a cancer screening modality. Our experience using three PET scanners showed that PET can be performed in many individuals, and a wide variety of carcinomas can be detected at potentially curable stages. PET screening targets various organs that conventional organ-specific screening tests cannot cover. PET used simultaneously with conventional tests can prevent the overlooking of cancer, reduce false-positive results, and assist in the interpretation of CT and MR images. Thus, PET can play a supportive role when used with conventional screening tests. To reduce false-positive and false-negative results in PET screening, however, experienced PET oncologists who can differentiate between distinct physiological FDG uptake and faint abnormal FDG uptake are needed. In Japan, more than half of the PET facilities offer PET examinations for cancer screening of asymptomatic persons. Not a few individuals pay for sophisticated cancer screenings. Guidelines concerning the use of PET for cancer screening were issued by the Japanese Society of Nuclear Medicine in 2004. The guidelines provide for maintenance of study quality and warn of overselling PET screening. It is unclear how much PET contributes to sophisticated cancer screening. Data are lacking as to whether mortality is reduced by PET screening. Scientific evidence should be presented demonstrating the value of PET in cancer screening.

Intense PET signal in the degenerative necrosis superimposed on chronic pancreatitis

Although fluorine-18 deoxyglucose-positron emission tomography (FDG-PET) is a sensitive diagnostic modality in detecting malignant tumors, differential diagnosis of malignant tumors from inflammatory lesion is challenging. We experienced a case of acute degenerative necrosis superimposed on chronic pancreatitis, which was difficult to distinguish from pancreatic cancer. The patient was a 66-year-old man with a complaint of upper abdominal pain. Abdominal computed tomography revealed low-density masses in the head and body of the pancreas. FDG-PET revealed intense accumulations at the head and body of the pancreas (mean standard uptake value for the head and body pancreatic tumors was 4.1 and 6.7, respectively) corresponding to the 2 tumors detected by computed tomography. Because of a possible malignant pancreatic tumor, the patient underwent pylorus-preserving pancreatoduodenectomy. Histologic examination of the resected specimen revealed a characteristic of chronic pancreatitis in a nontumorous area. Two tumors detected by FDG-PET consisted of degenerative necrosis surrounded by granulation tissue. The amount of granulation tissue was correlated to the levels of standard uptake value. No malignant tumors were observed. This case suggests a limitation of FDG-PET in distinguishing malignant neoplastic lesions in the pancreas, especially from acute degenerative changes in chronic pancreatitis. Repetitive PET examination is recommended for the accurate diagnosis.

Detection of recurrent pancreatic cancer: comparison of FDG-PET with CT/MRI

OBJECTIVE

To determine the value of fluorine-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the detection of recurrent pancreatic cancer in comparison to computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

Thirty-one patients with suspected recurrence after surgery were included. Inclusion criteria were sudden weight loss, pain or increased CA 19-9 levels. FDG-PET was performed in all patients. After visual analysis, maximal standardized uptake values (SUVmax) were determined by placing regions of interest on the pancreas bed. Additionally, all patients underwent contrast-enhanced multidetector CT (n = 14) or MR (n = 17) imaging. Positive findings at FDG-PET or CT/MRI were compared to follow-up.

RESULTS

All patients relapsed. Of 25 patients with local recurrences upon follow-up, initial imaging suggested relapse in 23 patients. Of these, FDG-PET detected 96% (22/23) and CT/MRI 39% (9/23). Local SUVmax ranged from 2.26 to 16.9 (mean, 6.06). Among 12 liver metastases, FDG-PET detected 42% (5/12). CT/MRI detected 92% (11/12) correctly. Moreover, 7/9 abdominal lesions were malignant upon follow-up of which FDG-PET detected 7/7 and CT/MR detected none. Additionally, FDG-PET detected extra-abdominal metastases in 2 patients.

CONCLUSION

In patients suspected of pancreatic cancer relapse; FDG-PET reliably detected local recurrences, whereas CT/MRI was more sensitive for the detection of hepatic metastases. Furthermore, FDG-PET proved to be advantageous for the detection of nonlocoregional and extra-abdominal recurrences.