The Utility of PET and CT in the Differential Diagnosis of Pancreatic Masses: A Prospective Study in 34 Patients

Transcription

1 The Utility of PET and CT in the Differential Diagnosis of Pancreatic Masses: A Prospective Study in 34 Patients Jui-Hao Chen 1,4, Kuo-Ching Yang 1,4, Chin-Chu Wu 2, Yen-Kung Chen 3,4,5 1 Division of Gastroenterology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan 2 Department of Radiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan 3 Department of Nuclear Medicine and PET Center, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan 4 Taipei Medical University, Taipei, Taiwan 5 School of Medicine, Fu Jen Catholic University, Taipei, Taiwan Background: Positron emission tomography (PET) using 18 F-fluoro-2-deoxy-D-glucose (FDG) can differentiate benign from malignant lesions, yet lack of anatomic information in FDG-PET images limits utility. Dualmodality FDG-PET/computed tomography (PET /CT) provides intrinsically aligned functional and anatomical data. Our aim was to determine if PET/CT can differentiate benign from malignant pancreatic lesions. Methods: A total of 34 patients with pancreatic lesions were prospectively enrolled to receive PET/CT. The standard uptake value (SUV) was calculated 1 h after initiating the scan, and a delayed PET/CT scan at 2 h was performed in 21 of 34 patients. All patients also received sonography and contrast enhanced computed tomography scan (cect). Only part of patients received endoscopic retrograde cholangiopancreaticography (ERCP). Results: There were 14 benign tumors (proven by histology in 4 cases and by follow-up in 10 cases) and 20 malignant tumors (proven by histology in 14 cases and by follow-up in 6 cases). SUV in benign masses was 0.42 to 4.41 (mean, ), and in malignant masses was 1.24 to (mean, ). Using Received 12/2/2009; revised 1/13/2010, accepted 1/14/2010. For correspondence and reprints contact: Yen-Kung Chen, M.D., Ph.D., Department of Nuclear Medicine and PET Center, Shin Kong Wu Ho-Su Memorial Hospital. 95 Wen Chang Road, Shih Lin District, Taipei 111, Taiwan. Tel: (886) ext. 2280, Fax: (886) , M004149@ms.skh.org.tw SUV = 4.4 as a cut-off, sensitivity was 80% and specificity was 93%. There were 4 false-negative patients in the malignant group. PET/CT is superior to sonography in differential diagnosis. Conclusion: PET/CT scan is a sensitive and specific method for differential diagnosis of pancreatic lesions, yet PET/CT seems not superior to cect alone. Key words: PET/CT, FDG, standard uptake value, pancreatic cancer Ann Nucl Med Sci 2010;23:1-9 Introduction Computed tomography (CT) is the primary technique for staging of suspected pancreatic cancer at most institutions [1], yet CT may be unable to differentiate benign from malignant lesions. Positron emission tomography (PET), especially with 18 F-fluoro-2-deoxy-D-glucose (FDG-PET), has been combined with CT (PET/CT) for diagnosing pancreatic cancer because the dual-modality method provides both anatomic and staging information [2]. In general, PET/CT has proven useful in determining lymph node involvement of lung cancer [3], staging of colorectal cancer [4], diagnosing recurrence of breast cancer [5], and monitoring response to therapy of lung cancer, mesothelioma, colorectal cancer, lymphoma, and melanoma [6]. Yet PET/CT is not recommended for staging prostate cancer [6], and it remains controversial

2 Chen JH et al for pancreatic cancer [7]. There is little evidence that PET provides additional information relevant to diagnosis or staging in pancreatic cancer patients with equivocal CT findings [7], although an earlier study apparently did not use dualmodality PET/CT. Limitations that have been noted for PET/CT include that it can increase the rate of false positives in lung cancer staging [8], and that incidental findings by PET/CT can complicate the diagnostic picture [9,10], especially in whole-body PET. Pancreatic cancer has a relatively poor prognosis [11]. Surgical resection provides the only opportunity for cure, but it can be hard to determine which patients are appropriate for surgery [12]. Contrast-enhanced computed tomography (cect) has been used for surgery planning, but this method may not identify small tumors and there is up to a 50% chance of falsely predicting resectability [13,14]. Endoscopic retrograde cholangiopancreaticography (ERCP) is useful for patients with suspected pancreatic cancer but only pancreatic duct or bile duct involvement can be identified [12]. Furthermore, it can be hard to distinguish benign pancreatic diseases (e.g., chronic pancreatitis with pseudotumor, cystadenoma, tuberculosis, and sarcoidosis) from pancreatic cancer. PET/CT may offer an advantage in differentiating benign and malignant pancreatic lesions [15]. There have been prior reports that PET can aid in the differential diagnosis of pancreatic tumors [2,11,15-19]. However, PET images yield limited anatomic information and this frequently restricts the ability to localize a lesion and to determine its infiltration into adjacent organs. Integrated dual-modality PET/CT tomography provides the opportunity to integrate functional and anatomical data sets [1-10,20]. A previous study at our institution suggests that PET/CT is more accurate than PET or CT alone for the depiction of mass lesions in the nasopharynx [21]. The goal of the present study is to investigate the ability of integrated dual-modality PET/CT to differentiate benign from malignant lesions in patients with pancreatic masses. Materials and Methods A total of 34 consecutive patients with a pancreatic mass were enrolled in a prospective PET/CT study from January 2003 to December Enrollment criteria were simply that patients were examined by ultrasonography or contrast-enhanced spiral CT (cect) scan, and that a pancreatic mass was observed. All patients had a follow-up cect scan. In addition, endoscopic retrograde cholangiopancreaticography (ERCP) was performed in a subset of patients with icterus or bile duct obstruction who consented to an invasive procedure. The cect was interpreted by a single radiologist to determine the presence or absence of tumor, existence of lymph nodes metastasis, and surgical respectability of the lesion. In CT scan, the pancreatic carcinoma is defined as a tumor typically enlarged only in part or entire gland of pancreatic parenchyma with altered attenuation less than normal parenchyma. Contrast enhanced CT revealed relative lack of enhancement in the pancreatic carcinoma. Levels of tumor marker CEA and CA19-9 were tested, and the cut-off values of CEA and CA19-9 were >5 ng/ml and >100 µg/ml, respectively [22]. These diagnostic studies were all completed several days before PET/CT dual tomography was performed. The patients, whose tumor had no tissue provable, surviving roughly 1 year without tumor enlargement or metastasis, and clinical manifestation disappeared are considered to have had benign disease. Patients were required to fast for at least 8 h before the PET scan, and patients had to be well hydrated and to avoid strenuous exercise for 24 h prior to the scan. In patients with diabetes, regular insulin was used for blood glucose control and plasma glucose was maintained at or below 140 mg/dl. FDG is a glucose analog, so it competes with glucose for transport into cells; consequently, hyperglycemia competitively inhibits FDG uptake and can potentially decrease tumor FDG uptake. Plasma glucose levels can be deranged in patients with pancreatic lesions, so patients were pre-treated to attain a uniformly low plasma glucose level before injection of FDG. If plasma glucose was below 140 mg/dl at the begining of the study, the emission images were acquired at 60 min ( 10 min) after FDG injection without administration of insulin. If plasma glucose was mg/dl at the begining of the study, the emission images were acquired at 90 min after FDG injection and no insulin was given. If plasma glucose was above 200 mg/dl at the beginning of the Ann Nucl Med Sci 2010;23:1-9 Vol. 23 No. 1 March

3 PET/CT PET/CT for pancreatic masses study, an insulin injection was given at least 30 min prior to the scan, the patient was asked to walk for 30 min, and blood glucose was tested every 30 min. If sugar level was still high, intravenous (IV) insulin was given again; FDG was injected when plasma glucose fell below 140 mg/dl and remained stable, implying that the insulin effect was complete. PET/CT imaging protocol All patients were imaged with an integrated dualmodality PET/CT system (Discovery LS, GE Medical Systems, Waukesha, WI, USA). Patients were scanned in as many sequential PET images as necessary to include the entire head, thorax, abdomen and pelvis. PET attenuation correction factors were calculated from the CT images. The CT portion of the integrated PET/CT examination used a 4 detector-row spiral CT (Light-Speed) scanner. Acquisitions occurred at 5-7 bed positions and had the following parameters: 140 kv, 40 ma, 0.8 s per CT rotation, a pitch of 6, a table speed of 22.5 mm/s, coverage of cm and an acquisition time of s. CT was performed before the emission acquisition. CT data were resized from a matrix to a matrix to match the PET data so that the images could be fused and CT transmission maps generated. The transaxial resolution (full width at half maximum) of PET/CT was 4.8 mm. Emission images were acquired for 5 min per bed position at min (range, 50 to 70) after IV administration of 370 MBq (10 mci) of FDG. A delayed scan done 2 h after FDG injection was performed on 21 of our patients, in whom the initial PET scan not definitive. Image datasets were obtained by iterative reconstruction (ordered-subset expectation maximization method). Images were displayed in 3 orthogonal projections and as wholebody maximum-pixel-intensity reprojection images for visual interpretation. A workstation (Xeleris, Elegems, Haifa, Israel) was used for image display and analysis. Image interpretation of PET/CT scan All study findings were interpreted jointly by a physician experienced in diagnostic radiology and a physician experienced in nuclear medicine. These physicians were aware of the patients clinical history and all available diagnostic images were used (cect, sonography, MRCP, or ERCP). Only the attenuation-corrected PET images were reviewed in transaxial, coronal, and sagittal planes and as maximum intensity projections. Visual analysis was used, and lesions with abnormal FDG uptake were recorded. Abnormal FDG uptake was defined as higher radiotracer accumulation in the pancreatic mass than in normal surrounding liver and pancreas tissue. Images were also analyzed semi-quantitatively using the standard uptake value (SUV). A region of interest (ROI) was placed over the lesion in the emission image with an FDG uptake area of 1 cm 2. SUV was calculated as follows: SUV = [activity (mci/ml) in ROI]/[injected dose (mci)/patient s weight (kg)]. Statistical analysis Continuous data are expressed either as means with standard deviations or as medians, while categorical data are expressed as frequency and percentage. Diagnostic values were expressed as counts per min. Sensitivity, specificity, positive predictive value (PPV), negative predicted value (NPV), and McNemar s test of equivalency were used to compare diagnostic tools. Data were analyzed using SAS 9.0 (SAS Institute Inc., Cary, NC, USA), and a P value <0.05 was accepted as statistically significant. Results From January 2003 to December 2005, a total of 34 patients (17 males, 17 females, mean age: years old) were enrolled prospectively. There were 14 benign and 20 malignant lesions. Benign lesions were proven by histology in 4 cases (1 chronic pancreatitis, 2 serous cystadenoma and 1 gastrinoma) and by long-term follow-up in 10 cases, with follow-up ranging from 6 months to 33 months (mean follow-up, 19.1 months). The final diagnosis of benign pancreatic lesions included chronic pancreatitis (9/14), serous cystadenoma (2/14), gastrinoma (1/14), and benign tumor of unknown nature (2/14). One patient died after 6 months because of a uremic complication. The other 9 patients were followed up from 11 months to 33 months; patients surviving roughly 1 year without tumor enlargement or metastasis and disappear- 2010;23:

4 Chen JH et al Table 1. Diagnostic values of PET/CT, Echo, CT and ERCP (or MRCP) Image modality Final diagnosis Benign Malignant PET/CT* Benign 13 4 Malignant 1 16 Sensitivity 80.0% Specificity 92.9% Positive predictive value (PPV) 94.1% Negative predictive value (NPV) 76.5% Echography* Benign 8 5 Malignant 6 15 Sensitivity 75.0% Specificity 57.4% Positive predictive value (PPV) 71.4% Negative predictive value (NPV) 61.5% CT* Benign 13 2 Malignant 1 18 Sensitivity 90.0% Specificity 92.8% Positive predictive value (PPV) 94.7% Negative predictive value (NPV) 86.7% ERCP (or MRCP)* Benign 7 1 Malignant 1 10 Sensitivity 90.9% Specificity 87.5% Positive predictive value (PPV) 90.9% Negative predictive value (NPV) 87.5% *P >0.05, McNemar s test; SUV = 4.4 as PET/CT reading cut point ance of clinical manifestation were considered to have had benign disease. Malignant lesions were proven by histology in 14 cases and by follow-up in 6 cases (follow-up period from 3 to 12 months showed metastases, malignant symptoms and signs). The final diagnosis of malignant pancreatic lesion included cancer of the pancreatic head (15/20), cancer of the pancreatic body (1/20), cancer of the papilla of Vater with invasion to the pancreas (1/20), cancer of the duodenum with invasion to the pancreas (1/20), cholangiocarcinoma with invasion to the pancreas (1/20), and intraductal papillary mucinous neoplasm of the pancreas (1/20). In 5 of 6 malignant lesions that were not proven by histology, patients died of pancreatic malignancy in 3 to 6 months. The sixth patient survived up to 1 year with liver metastasis. The diagnostic value of PET/CT was compared to echography, cect and ERCP (Table 1). The sensitivity was: ERCP (90.9%) = ~ cect (90%) > PET/CT (80%) > echography (75%). The specificity was: PET/CT (92.9%) ~ = cect (92.8%) > ERCP (specificity 87.5%) > echography (57.4%). The positive predictive value was: cect (94.7%) > PET/CT (94.1%) > ERCP (90.9%) > echography (71.4%). The negative predictive value was: ERCP (87.5%) > cect (86.7%) > PET/CT (76.5%) > echography (61.5%). There was no statistical difference between the four diagnostic modalities. The SUV in benign lesions ranged from 0.4 to 4.4 (mean ), while the SUV in malignant lesions ranged from 1.2 to 15.1 (mean ). A PET/CT scan of a patient with a malignant pancreatic lesion showed a high SUV (9.55) in the pancreatic head (Figure 1). Another PET/CT scan of a patient with a malignant pancreatic lesion showed a low SUV (1.89) in the pancreatic head (Figure 2). These images showed no evidence of muscle uptake (Figures 1 and 2), suggesting that the insulin effect on muscle uptake of FDG was minimal. There was a clear distinction between benign and malignant lesions by SUV (Figure 3). Receiver operating characteristic (ROC) analysis showed good differentiation between benign and malignant lesions (Figure 4). The area under the ROC curve was The SUV was set at a cut-off value of 4.4 retrospectively, and the resulting sensitivity of PET/CT was 80% and specificity was 93% (Figures 3 and 4). There were 4 false-negative lesions in the patients with malignancy. A delayed PET scan 2 h after the initial scan was performed in 21 of 34 patients, including 10 patients with malignant lesions and 11 patients with benign lesions; these patients included 11 patients in whom the initial PET scan was equivocal. Retention index was calculated as [(SUV at 2 h) - (SUV at 1 h)]/(suv at 1 h). In 9 of the 10 patients with malignancy, the SUV increased at 2 h (retention index from 11 to 48, mean 25.8); in the remaining patient with malignancy, the retention index was -42. In 7 of the 11 patients with benign lesions, the SUV decreased at 2 h (retention index from -3 to -44, mean -17.7); in the remain- Ann Nucl Med Sci 2010;23:1-9 Vol. 23 No. 1 March

5 PET/CT PET/CT for pancreatic masses A B A B C D C D Figure 1. The patient underwent FDG-PET/CT study using a GE discovery LS PET/CT hybrid imaging scanner. The arrows point to an increased FDG uptake (SUV = 9.55) in the cancer of pancreatic head. Figure 2. PET image shows cancer of pancreatic head (arrow) with low metabolic and SUV of Figure 3. Standard uptake value (SUV) distribution in patients with benign and malignant pancreatic lesions ing 4 patients, the retention indices were 1, 2, 20, and 33, respectively. Including all measured values, we found a significant difference in the retention index between benign and malignant lesions (Fisher s Exact test: P = ) (Table 2). Discussion Our results suggest that PET/CT offers good sensitivity Figure 4. Receiver operating characteristic (ROC) analysis of standard uptake values (SUV) of lesions in all 34 patients. This analysis suggests that PET/CT has good sensitivity for lesion diagnosis. 2010;23:

6 Chen JH et al Table 2. Results of the delayed PET scan Delayed PET scan* Benign Malignant SUV increase 4 9 SUV decrease 7 1 Total *P = , Fisher s Exact test and specificity for differentiating benign from malignant pancreatic lesions, in comparison to other diagnostic methods that are typically used for pancreatic lesions (Table 1). This finding may be controversial because PET was previously found to offer little additional information relevant to diagnosis or staging in pancreatic cancer patients with equivocal cect findings [7]. However, the earlier study [7] apparently did not use dual-modality PET/CT, and image fusion of PET and CT may offer significant advantages over either method alone. Our method also does not apparently increase the rate of false positives, which has caused a problem in lung cancer staging [8]. We made no incidental findings by PET/CT, so our method also does not complicate the diagnostic picture, as has been reported in other PET/CT studies [9,10]. At most institutions, cect is the primary technique for staging of suspected pancreatic cancer [1], yet cect may be unable to differentiate benign from malignant lesions. In our study, cect imaging seems more sensitive and specific than both echography and PET/CT (Table 1), but it is not statistically different. Hypodensity in cect images is a characteristic sign of pancreatic cancer [20], but it is possible to misdiagnose patients with malignant lesions because small or metastatic lesions are easily overlooked, and because it remains difficult to differentiate cancer from a pseudotumor or indeterminate results [23]. Chronic pancreatitis is a risk factor for pancreatic cancer, and pseudotumor formation is common in patients with chronic pancreatitis. Adjuvant imaging techniques, such as PET, can be a way to address the limitations of a cect scan. The FDG-PET method detects functional activity rather than lesion size [16], and normal tissue typically has a low uptake of FDG, while cancer has a high uptake [9]. This may be particularly true of pancreatic tissue, as our results suggest that the metabolic rate of healthy pancreatic tissue is quite low (Figures 1 and 2). In our study, dual-modality PET/CT had high sensitivity and specificity in the detection of pancreatic malignancy (80% and 92.9%, respectively). If we use SUV 4.4 as a retrospective cut-point, there were 4 false-negative patients (Figure 3). For these 4 patients, cect scans helped to make the diagnosis of malignant pancreatic tumor in 2 patients, but we found only pancreatic duct dilatation and/or common bile duct dilatation in the other 2 patients. Three of these 4 patients had tumors in the pancreatic head with jaundice (SUV = 3.23, 1.89, 1.24, respectively) and 1 of them had a small tumor in the pancreatic body (SUV = 1.53). This last patient had a tumor that was so small that the high SUV of tumor tissue might have been reduced by partial-volume inclusion of normal tissue in the imaging voxel. We note that serum CA19-9 was elevated in 3 of the 4 false negative patients and serum CEA was elevated in only 1 patient (results not reported). Furthermore, the serum CA19-9 values were 103, 294 and 130 µg/ml, respectively, whereas the last patient had normal serum CEA and CA19-9 values. Therefore, serum markers such as CA19-9 and CEA may help in the differential diagnosis of pancreatic lesions, if both PET/CT and cect are not diagnostic. False negative PET results have been reported with small (<2 cm) tumors [16], and we also found that this could be a problem. However, in our study and in another report [16], PET uptake was not related to tumor size in all cases; 2 of the 4 false negative patients in our study were large tumors (4-5 cm) as shown by the cect scan. Various earlier reports [16,24-27] concluded that PET was not suitable for pre-operative staging of pancreatic cancer, because it was not sensitive for detection of lymph node metastasis or peritoneal seeding. Our results cannot resolve this controversy, because most of our cases did not receive operation. Previous work has suggested that an SUV of 2.0 to 2.2 may be a useful cutoff value to differentiate benign from malignant pancreatic lesions [16]. However, such a low SUV increases the risk of a false positive due to inflammation from chronic pancreatitis [16]. We used a higher SUV cutoff value in our study, thereby increasing the risk of a false neg- Ann Nucl Med Sci 2010;23:1-9 Vol. 23 No. 1 March

7 PET/CT PET/CT for pancreatic masses ative result. However, when PET/CT is combined with other diagnostic modalities (Table 1), the risk of false negative results may be sufficiently minimized. A delayed PET scan at 2 h may also increase the ability to differentiate benign from malignant pancreatic lesions [19]. A prior study reported an increase in the SUV at 2 h in 81% of malignant lesions and a decrease in SUV at 2 h in 85% of benign lesions [19]. Our results agreed with this finding, as there was a significant difference in the retention index between benign and malignant lesions (Fisher s Exact test: P =0.0237). Our results show that a delayed scan at 2 h may be useful in differentiating benign from malignant pancreatic lesions. The determination of malignancy in pancreatic cystic tumors is difficult. Conventional imaging studies show some characteristic features in cystic tumors, but misdiagnosis and mistreatment are frequent. Analysis of cystic fluid aspiration, including cytology and tumor markers, is regarded as potentially useful in the differential diagnosis, but both false-negative results and the seeding of malignant cells may occur [28]. Nevertheless, high sensitivity (94%) and specificity (94-97%) of PET scans were reported in the diagnosis of pancreatic cystic lesions [29,30]. Previous work [31] emphasized the utility of PET scans in the detection of intraductal papillary mucinous neoplasm (IPMN). It is possible that PET is a good method to determine malignancy in pancreatic cystic tumors and a negative result by PET could avoid unnecessary surgery in asymptomatic or high-risk patients [30]. Conclusions Our results suggest PET/CT imaging is sensitive and specific for the differential diagnosis of pancreatic tumor. Although it may be less sensitive than cect alone, PET/CT can be used to differentiate chronic pancreatitis with pseudotumor from pancreatic malignancy. Further study is needed to determine if the retention index obtained from PET/CT imaging contributes enough additional information that it should be routinely performed in all patients with a pancreatic mass. References 1. Lall, CG, Howard TJ, Skandarajah A, DeWitt JM, Aisen AM, Sandrasegaran K. New concepts in staging and treatment of locally advanced pancreatic head cancer. AJR Am J Roentgenol 2007;189: Heinrich S, Goerres GW, Schafer M, et al. Positron emission tomography/computed tomography. Influences on the management of respectable pancreatic cancer and its cost-effectiveness. Ann Surg 2005;242: Freudenberg LS, Rosenbaum SJ, Beyer T, Bockisch A, Antoch G. PET versus PET/CT dual-modality imaging in evaluation of lung cancer. Radiol Clin N Am 2007;45: Veit-Haibach P, Kuehle CA, Beyer T, et al. Diagnostic accuracy of colorectal cancer staging with whole-body PET/CT colonography. JAMA 2006;296: Radan L, Ben-Haim S, Bar-Shalom R, Guralnik L, Israel O. The role of FDG-PET/CT in suspected recurrence of breast cancer. Cancer 2006;107: von Schulthess GK, Steinert HC, Hany TF. Integrated PET/CT: current applications and future directions. Radiology 2006;238: Lytras D, Connor S, Bosonnet L, et al. Positron emission tomography does not add to computed tomography for the diagnosis and staging of pancreatic cancer. Dig Surg 2005;22: Lee BE, von Haag D, Lown T, Lau D, Calhoun R, Follette D. Advances in positron emission tomography technology have increased the need for surgical staging in non-small cell lung cancer. J Thorac Cardiovasc Surg 2007;133: Metser U, Miller E, Lerman H, Even-Sapir E. Benign nonphysiologic lesions with increased 18 F-FDG uptake on PET/CT: characterization and incidence. AJR Am J Roentgenol 2007;189: Wang G, Lau EW, Shakher R, et al. How do oncologists deal with incidental abnormalities on whole-body fluorine-18 fluordeoxyglucose PET/CT. Cancer 2007;109: Delbeke D, Rose D, Chapman W, et al. Optimal interpretation of FDG PET in the diagnosis, staging and management of pancreatic carcinoma. J Nucl Med 1999;40: Alberts SR, Gores GJ, Kim GP, et al. Treatment options 2010;23:

8 Chen JH et al for hepatobiliary and pancreatic cancer. Mayo Clin Proc 2007;82: Diehl SJ, Lehman KJ, Sadick M, Lachmann R, Georgi M. Pancreatic cancer: value of dual-phase helical CT in assessing respectability. Radiology1998;206: Lu DSK, Reber HA, Krasny RM, Kadell BM, Sayre J. Local staging of pancreatic cancer: criteria for unresectability of major vessels as revealed by pancreaticphase, thin-section helical CT. AJR Am J Roentgenol 1997;168: Rajput A, Stellato TA, Faulhaber PF, Vesselle HJ, Miraldi F. The role of fluorodeoxyglucose a positron emission tomography in the evaluation of pancreatic disease. Surgery 1998;124: Keogan M, Tyler D, Clark L, et al. Diagnosis of pancreatic carcinoma: role of FDG-PET. AJR Am J Roentgenol 1998;171: Rose D, Delbeke D, Beauchamp D, et al. 18 Fluorodeoxyglucose-positron emission tomography in the management of patients with suspected pancreatic cancer. Ann Surg 1999;229: Imdahl A, Nitzsche E, Krautmann F, et al. Evaluation of positron emission tomography with 2-[ 18 F]fluoro-2- deoxy-d-glucose for the differentiation of chronic pancreatitis and pancreatic cancer. Brit J Surg 1999;86, Nakamoto Y, Higashi T, Sakahara H, et al. Delayed 18 F- fluoro-2-deoxy-d-glucose positron emission tomography scan for differentiation between malignant and benign lesions in the pancreas. Cancer 2000;89: Podoloff DA, Macapinlac HA. PET and PET/CT in management of the lymphomas. Radiol Clin N Am 2007;45: Chen YK, Su CT, Ding HJ, et al. Clinical usefulness of fused PET/CT compared with PET alone or CT alone in nasopharyngeal carcinoma patients. Anticancer Res 2006;26: Kim JE, Lee KT, Lee JK, Paik SW, Rhee JC, Choi KW. Clinical usefulness of carbohydrate antigen 19-9 as a screening test for pancreatic cancer in an asymptomatic population. J Gastroenterol Hepatol 2004;19: Orlando LA, Kulasingam SL, Matchar DB. Meta-analysis: the detection of pancreatic malignancy with positron emission tomography. Aliment Pharmacol Ther 2004; 20: Diederichs CG, Staib L, Vogel J, et al. Values and limitations of 18 F-fluoro-2-deoxy-D-glucose positron emission tomography with preoperative evaluation of patients with pancreatic masses. Pancreas 2000;20: Kalady MF, Clary BM, Clark LA, et al. Clinical utility of positron emission tomography in the diagnosis and management of periampullary neoplasms. Ann Surg Oncol 2002;9: Kasperk RK, Riesener KP, Wilms K, Schumpelick V. Limited value of positron emission tomography in the treatment of pancreatic cancer: surgeon s view. World J Surg 2001;25: Berberat P, Friess H, Kashiwagi M, Beger HG, Büchler MW. Diagnosis and staging of pancreatic cancer by positron emission tomography. World J Surg 1999;23: Jadvar H, Fischman AJ. Evaluation of pancreatic carcinoma with FDG PET. Abdom Imag 2001;26: Sperti C, Pasquali C, Chierichetti F, Liessi G, Ferlin G, Pedrazzoli S. Value of 18-fluorodeoxyglucose positron emission tomography in the management of patients with cystic tumors of pancreas. Ann Surg 2001;234: Sperti C, Pasquali C, Decet G, Chierichetti F, Liessi G, Pedrazzoli S. F-18-fluorodeoxyglucose positron emission tomography in differentiating malignant from benign pancreatic cysts: a prospective study. J Gastrointest Surg 2005;9: Yoshioka M, Sato T, Furuya T, et al. Positron emission tomography with 2-deoxy-2-[ 18 F]fluoro-d-glucose for the diagnosis of intraductal papillary mucinous tumor of the pancreas with parenchymal invasion. J Gastroenterol 2003;38: Ann Nucl Med Sci 2010;23:1-9 Vol. 23 No. 1 March

9 PET/CT PET/CT for pancreatic masses 34 1,4 1,4 2 3,4, (FDG) (PET) PET (PET/CT) PET/CT 34 PET/CT 1 (SUV) PET SUV ( ) ( ) SUV = 4.4 PET/CT 80% 93% 4 PET/CT / ;23: (02) (02) M004149@ms.skh.org.tw 2010;23: