2-(fluorine-18)-fluoro-2-deoxy-D-glucose PET in detection of pancreatic cancer: value of quantitative image interpretation

Clinical Impact of 18F-FDG PET/CT in the Diagnostic Workup of Pancreatic Ductal Adenocarcinoma: A Systematic Review

In this review, the performance of fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in the diagnostic workup of pancreatic ductal adenocarcinoma (PDAC) is evaluated. A comprehensive literature search up to September 2020 was performed, selecting studies with the presence of: sample size ≥10 patients and index test (i.e., “FDG” or “18F-FDG” AND “pancreatic adenocarcinoma” or “pancreas cancer” AND “PET” or “positron emission tomography”). The methodological quality was evaluated using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool and presented according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Basic data (authors, year of publication, country and study design), patients’ characteristics (number of enrolled subjects and age), disease phase, type of treatment and grading were retrieved. Forty-six articles met the adopted research criteria. The articles were divided according to the considered clinical context. Namely, besides conventional anatomical imaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), molecular imaging with FDG PET/CT is an important tool in PDAC, for all disease stages. Further prospective studies will be necessary to confirm the cost-effectiveness of such imaging techniques by testing its real potential improvement in the clinical management of PDAC.

Follicular pancreatitis: A rare pancreatic inflammatory pseudotumor

Inflammatory pseudotumors imitate neoplasms on imaging but actually represent focal inflammation. We report a case of follicular pancreatitis, which is a recently recognized distinct form of mass-forming focal chronic pancreatitis pathologically characterized by lymphoid infiltration with abundant reactive germinal centers. In our patient, follicular pancreatitis manifested as a pancreatic tail mass that was resected due to imaging findings, which were suggestive of pancreatic malignancy. We performed a literature review of this rare condition and present a summary of reported imaging findings. The most distinguishing feature from pancreatic adenocarcinoma is the enhancement pattern, as follicular pancreatitis enhances more than the surrounding pancreatic parenchyma on delayed post-contrast images which is unusual for pancreatic adenocarcinoma. If this benign diagnosis is suggested on imaging, unnecessary surgery and its potential complications may be avoided.

The Role of 18F-FDG PET/CT and PET/MRI in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a difficult disease to treat and continues to portend a poor prognosis, as most patients are unresectable at diagnosis. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with CT (PET/CT) has been a cornerstone in oncological imaging of different cancers; however, the role of PET/CT in PDAC is continually evolving and currently not well established. Studies have shown the potential of PET/CT in guiding the management of patients with PDAC, with possible added benefit over anatomic imaging with CT or MRI in certain scenarios. PET/CT may be useful in diagnosis, initial staging, treatment response assessment, differentiation of recurrent tumor from post-treatment fibrosis, and radiotherapy planning. Additionally, PET/CT may be a cost-effective modality due to upstaging of patients originally deemed as surgical candidates. Recently, the advent of simultaneous PET/MRI represents an exciting advancement in hybrid functional imaging with potential applications in the imaging of PDAC. The advantages of PET/MRI include simultaneous acquisition to improve registration of fusion images, lower radiation dose, superior soft tissue contrast, and availability of multiparametric imaging. Studies are underway to evaluate the utility of PET/MRI in PDAC, including in initial staging and treatment response assessment and to determine the subgroup of patients that will benefit from PET/MRI. Further studies are warranted in both PET/CR and PET/MRI to better understand the role of these modalities in PDAC.

Is Positron Emission Tomography Using 18F-Fluorodeoxyglucose and 11C-Acetate Valuable in Diagnosing Indeterminate Pancreatic Masses?

Background:

It can be impossible to differentiate a mass forming chronic pancreatitis from adenocarcinoma of the pancreas using standard anatomical imaging. Positron emission tomography using 2-[18F] fluoro-2deoxy-D-glucose (18FDG-PET) and 1-[11C]-acetate (11C-acetate-PET) are methods taking advantage of the metabolic differences between benign and malignant tissues.

Aims:

To determine the diagnostic accuracy of 18FDG-PET and 11C-acetate-PET in indeterminate pancreatic masses.

Methods:

Twenty patients with an indeterminate mass of the head of the pancreas were prospectively studied. All patients underwent 18FDG-PET and eighteen of them 11C-acetate-PET. Scans were evaluated qualitatively and quantitatively; the later by using regional standardised uptake value (SUV). Final diagnosis was established using histopathologic evaluation of resected specimen or biopsy.

Results:

Adenocarcinoma was diagnosed in twelve patients and chronic pancreatitis in eight. Qualitative evaluation of 18FDG-PET imaging revealed three false negative and one false-positive results. The sensitivity, specificity, and diagnostic accuracy were 75 %, 88 %, and 80 %, respectively. The cut-off SUV to differentiate malignant from benign disease was 3,5 demonstrating a sensitivity of 91.7 % and a specificity of 75 %.

Conclusion:

18FDG-PET imaging could not confirm or exclude malignancy in indeterminate masses of the head of the pancreas with high sensitivity and diagnostic accuracy. 11C-acetate-PET provided no additional diagnostic benefits.

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.

Positron emission tomography (PET) has limited utility in the staging of pancreatic adenocarcinoma

BACKGROUND

Positron emission tomography (PET) as an adjunct to conventional imaging in the staging of pancreatic adenocarcinoma is controversial. Herein, we assess the utility of PET in identifying metastatic disease and evaluate the prognostic potential of standard uptake value (SUV).

METHODS

Imaging and follow-up data for patients diagnosed with pancreatic adenocarcinoma were reviewed retrospectively. Resectability was assessed based on established criteria, and sensitivity, specificity, and accuracy of PET were compared to those of conventional imaging modalities.

RESULTS

For 123 patients evaluated 2005-2011, PET and CT/MRI were concordant in 108 (88 %) cases; however, PET identified occult metastatic lesions in seven (5.6 %). False-positive PETs delayed surgery for three (8.3 %) patients. In a cohort free of metastatic disease in 78.9 % of cases, the sensitivity and specificity of PET for metastases were 89.3 and 85.1 %, respectively, compared with 62.5 and 93.5 % for CT and 61.5 and 100.0 % for MRI. Positive predictive value and negative predictive value of PET were 64.1 and 96.4 %, respectively, compared with 75.0 and 88.9 % for CT and 100.0 and 91.9 % for MRI. Average difference in maximum SUV of resectable and unresectable lesions was not statistically significant (5.65 vs. 6.5, p = 0.224) nor was maximum SUV a statistically significant predictor of survival (p = 0.18).

CONCLUSION

PET is more sensitive in identifying metastatic lesions than CT or MRI; however, it has a lower specificity, lower positive predictive value, and in some cases, can delay definitive surgical management. Therefore, PET has limited utility as an adjunctive modality in staging of 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.

The usefulness of (18)F-FDG PET/MRI fusion image in diagnosing pancreatic tumor: comparison with (18)F-FDG PET/CT

PURPOSE

This study aimed at demonstrating the feasibility of retrospectively fused (18)F FDG-PET and MRI (PET/MRI fusion image) in diagnosing pancreatic tumor, in particular differentiating malignant tumor from benign lesions. In addition, we evaluated additional findings characterizing pancreatic lesions by FDG-PET/MRI fusion image.

METHODS

We analyzed retrospectively 119 patients: 96 cancers and 23 benign lesions. FDG-PET/MRI fusion images (PET/T1 WI or PET/T2WI) were made by dedicated software using 1.5 Tesla (T) MRI image and FDG-PET images. These images were interpreted by two well-trained radiologists without knowledge of clinical information and compared with FDG-PET/CT images. We compared the differential diagnostic capability between PET/CT and FDG-PET/MRI fusion image. In addition, we evaluated additional findings such as tumor structure and tumor invasion.

RESULTS

FDG-PET/MRI fusion image significantly improved accuracy compared with that of PET/CT (96.6 vs. 86.6 %). As additional finding, dilatation of main pancreatic duct was noted in 65.9 % of solid types and in 22.6 % of cystic types, on PET/MRI-T2 fusion image. Similarly, encasement of adjacent vessels was noted in 43.1 % of solid types and in 6.5 % of cystic types. Particularly in cystic types, intra-tumor structures such as mural nodule (35.4 %) or intra-cystic septum (74.2 %) were detected additionally. Besides, PET/MRI-T2 fusion image could detect extra benign cystic lesions (9.1 % in solid type and 9.7 % in cystic type) that were not noted by PET/CT.

CONCLUSIONS

In diagnosing pancreatic lesions, FDG-PET/MRI fusion image was useful in differentiating pancreatic cancer from benign lesions. Furthermore, it was helpful in evaluating relationship between lesions and surrounding tissues as well as in detecting extra benign cysts.

Is intraoperative confirmation of malignancy during pancreaticoduodenectomy mandatory?

INTRODUCTION

Differentiating between chronic pancreatitis and pancreatic adenocarcinoma can be difficult due to considerable overlap in disease presentation and radiological signs and the frequent co-existence of the two conditions. In this situation, surgeons may have to proceed to "blind" pancreaticoduodenectomy or attempt to confirm malignancy intraoperatively with frozen section (FS) histology.

METHODS

This study attempted to ascertain the false-negative and false-positive rates of undertaking pancreaticoduodenectomies (PD) based on clinical suspicion (CS) or after intraoperative confirmation of malignancy using FS histology.

RESULTS

Of patients, 13.6% (nine out of 66) underwent a benign PD in the CS group; 6.7% of patients had a missed malignancy in the FS group (n = 62), but intraoperative histology prevented PD in 35% of patients with benign disease in the FS group. Specificity and sensitivity of intraoperative FS in detecting malignancy was 100% and 89.7%, respectively. Sensitivity of clinical assessment in detecting malignancy was 86.4%.

CONCLUSIONS

In experienced hands, intraoperative confirmation of malignancy is effective and will avoid resection in patients with benign disease. However, for many surgeons the chance of missing a small tumour with a false-negative biopsy will be unacceptable and they would prefer to undertake a "blind" resection and accept the mortality risk of pancreaticoduodenectomy for benign disease.

Predictive value of metabolic 18FDG-PET response on outcomes in patients with locally advanced pancreatic carcinoma treated with definitive concurrent chemoradiotherapy

BACKGROUND

We aimed to study the predictive value of combined 18F-fluoro-deoxy-D-glucose positron emission tomography and computerized tomography (FDG-PET-CT), on outcomes in locally advanced pancreatic carcinoma (LAPC) patients treated with concurrent chemoradiotherapy (C-CRT).

METHODS

Thirty-two unresectable LAPC patients received 50.4 Gy (1.8 Gy/fr) of RT and concurrent 5-FU followed by 4 to 6 cycles of gemcitabine consolidation. Response was evaluated by FDG-PET-CT at post-C-CRT 12-week. Patients were stratified into two groups according to the median difference between pre- and post-treatment maximum standard uptake values (SUVmax) as an indicator of response for comparative analysis.

RESULTS

At a median follow-up of 16.1 months, 16 (50.0%) patients experienced local/regional failures, 6 of which were detected on the first follow-up FDG-PET-CT. There were no marginal or isolated regional failures. Median pre- and post-treatment SUVmax and median difference were 14.5, 3.9, and -63.7%, respectively. Median overall survival (OS), progression-free survival (PFS), and local-regional progression-free survival (LRPFS) were 14.5, 7.3, and 10.3 months, respectively. Median OS, PFS, and LRPFS for those with greater (N = 16) versus lesser (N = 16) SUVmax change were 17.0 versus 9.8 (p = 0.001), 8.4 versus 3.8 (p = 0.005), and 12.3 versus 6.9 months (p = 0.02), respectively. On multivariate analysis, SUVmax difference was predictive of OS, PFS, and LRPFS, independent of existing covariates.

CONCLUSIONS

Significantly higher OS, PFS, and LRPFS in patients with greater SUVmax difference suggest that FDG-PET-CT-based metabolic response assessment is an independent predictor of clinical outcomes in LAPC patients treated with definitive C-CRT.

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.

PET and PET/CT for pancreatic malignancies

FDG PET imaging is useful for preoperative diagnosis of pancreatic carcinoma in patients with suspected pancreatic cancer in whom CT fails to identify a discrete tumor mass or in whom FNAs are nondiagnostic. FDG PET imaging is useful for M staging and restaging by detecting CT occult metastatic disease, allowing noncurative resection to be avoided in this group of patients. FDG PET can differentiate post-therapy changes from recurrence and holds promise for monitoring neoadjuvant chemoradiation therapy. The technique is less useful in periampullary carcinoma and marginally helpful in staging except for M staging. As with other malignancies, FDG PET is complementary to morphologic imaging with CT, therefore, integrated PET/CT imaging provides optimal images for interpretation and thus more optimal patient care.

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.

Comparison of CT and PET-CT based planning of radiation therapy in locally advanced pancreatic carcinoma

BACKGROUND

To compare computed tomography (CT) with co-registered positron emission tomography-computed tomography (PET-CT) as the basis for delineating gross tumor volume (GTV) in unresectable, locally advanced pancreatic carcinoma (LAPC).

METHODS

Fourteen patients with unresectable LAPC had both CT and PET images acquired. For each patient, two three-dimensional conformal plans were made using the CT and PET-CT fusion data sets. We analyzed differences in treatment plans and doses of radiation to primary tumors and critical organs.

RESULTS

Changes in GTV delineation were necessary in 5 patients based on PET-CT information. In these patients, the average increase in GTV was 29.7%, due to the incorporation of additional lymph node metastases and extension of the primary tumor beyond that defined by CT. For all patients, the GTVCT versus GTVPET-CT was 92.5 +/- 32.3 cm3 versus 104.5 +/- 32.6 cm3 (p = 0.009). Toxicity analysis revealed no clinically significant differences between two plans with regard to doses to critical organs.

CONCLUSION

Co-registration of PET and CT information in unresectable LAPC may improve the delineation of GTV and theoretically reduce the likelihood of geographic misses.

Preoperative evaluation of pancreatic adenocarcinoma

The preoperative evaluation of resectability for pancreatic cancer fails to identify up to 25% of patients who are unfortunately found to be unresectable at surgical exploration. Inoperative findings in this circumstance is usually due to either small volume metastatic disease or regional tumor invasion. While advances in computed tomography (CT) technology has increased accuracy of local tumor extent, occult metastatic disease remains a common problem. Although 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) has been demonstrated to be useful in the staging of many malignancies (e.g. esophageal cancer, recurrent colorectal cancer, lung cancer), it has not been found to significantly increase the accuracy of determining resectability preoperatively in pancreatic cancer, especially with regard to detection of small volume metastatic disease. There are a variety of pancreatic cancer-specific antigens which are being developed as a method for targeted molecular imaging; we provide preliminary data targeting the integrin alpha(v)beta(6) to demonstrate the potential feasibility of this approach. Further developments may allow the accurate determination of patients with resectable pancreatic cancer, and more importantly, those with unresectable disease that may forego unnecessary surgery, the associated morbidity, and the subsequent delay of appropriate therapy.

PET and PET/CT for Pancreatic Malignancies

FDG PET imaging is useful for preoperative diagnosis of pancreatic carcinoma in patients with suspected pancreatic cancer in whom CT fails to identify a discrete tumor mass or in whom FNAs are nondiagnostic. FDG PET imaging is useful for M staging and restaging by detecting CT occult metastatic disease, allowing noncurative resection to be avoided in this group of patients. FDG PET can differentiate post-therapy changes from recurrence and holds promise for monitoring neoadjuvant chemoradiation therapy. The technique is less useful in periampullary carcinoma and marginally helpful in staging except for M staging. As with other malignancies, FDG PET is complementary to morphologic imaging with CT, therefore, integrated PET/CT imaging provides optimal images for interpretation and thus more optimal patient care.

Differential diagnosis of benign and malign pancreatic masses with 18F-fluordeoxyglucose-positron emission tomography recorded with a dual-head coincidence gamma camera

INTRODUCTION

Metabolic imaging using 18F-fluordeoxyglucose and a ring-positron emission tomography camera is an established method in the differential diagnosis of pancreatic masses. Ring-positron emission tomography cameras, however, are expensive and available in only few specialized centres. The aim of this study was to investigate how far 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera could differentiate between benign and malign pancreatic masses.

MATERIAL AND METHODS

Forty-one patients (male/female: 25/16; mean age: 64.0 years; range: 41-86 years) with a pancreatic mass detected by ultrasound, computed tomography or MRI were included. In all patients 18F-fluordeoxyglucose scan was performed after overnight fasting and injection of 4 mCi 18F-fluordeoxyglucose using an ADAC Vertex MCD dual head gamma-camera (ADAC; Milpitas, California, USA), equipped with a 5/8-inch NaI-crystal. Images were acquired through a 180 degrees grade rotation in the three dimensional mode. The chosen matrix was 128 x 128 x 16, a Butterworthfilter (ADAC) was used and data were transferred into visible sinograms via Fourier-Rebinning. Coronar, sagittal and transversal slices of 3.9 mm thickness each were acquired. Focal tracer enhancement was suspicious for a malignoma and therefore regarded as positive, diffuse or no tracer uptake was suspicious for a benign process and was regarded as negative for cancer. DEFINITION OF GOLD STANDARDS: A diagnosis of cancer had to be confirmed histologically by specimens obtained by 18G-needle biopsy, surgical resection or at autopsy. A diagnosis of an inflammatory mass was considered proven, if no carcinoma could be found histologically in the surgically resected mass or at autopsy, or if there was no progression of the disease during a follow-up of at least 12 months.

RESULTS

In 22 patients carcinoma was diagnosed (pancreatic cancer: n=17; endocrine tumour: n=3; carcinoma of the common bile duct: n=2). 18F-fluordeoxyglucose scan showed a focal tracer enhancement in 19 of these 22 patients (sensitivity: 86.4%). False negative results were acquired in two patients with cancer of the common bile duct and in one patient with poorly controlled insulin-dependent diabetes mellitus. In 19 patients the final diagnosis was an inflammatory pancreatic mass. 18F-fluordeoxyglucose scan showed a diffuse tracer enhancement in 15 of these 19 patients (specificity: 78.9%). False positive results were acquired in three patients whose blood tests showed signs of an acute episode of chronic pancreatitis. Positive and negative predictive values of 18F-fluordeoxyglucose scan were 82.6% and 83.3%, respectively.

CONCLUSION

18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera is a highly sensitive and specific method in the differential diagnosis of benign and malign pancreatic masses.

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.

The clinical usefulness of 18-fluorodeoxyglucose positron emission tomography in the differential diagnosis, staging, and response evaluation after concurrent chemoradiotherapy for pancreatic cancer

GOALS

The aims of this study were to determine the clinical use of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the differential diagnosis of patients with suspected pancreatic cancer and in the determination of tumor response after concurrent chemoradiotherapy for pancreatic cancer.

BACKGROUND

Despite advances in diagnostic tools for pancreatic cancer, it is difficult to differentiate pancreatic cancer from mass-forming pancreatitis. Even with current imaging modalities, it is also difficult to assess tumor response to therapeutic intervention.

STUDY

One hundred two patients with suspected pancreatic cancer were selected for this study. Dynamic computerized tomography (CT) scan and FDG-PET were used sequentially to diagnose pancreatic cancer. After diagnostic confirmation their diagnostic yields were compared. We also evaluated the treatment response in 15 patients who underwent chemoradiation therapy with dynamic CT scan and FDG-PET and compared their results.

RESULTS

In 93 out of 102 patients, pancreatic cancer was confirmed. FDG-PET showed higher diagnostic accuracy than CT scan (95.1% vs. 76.5%). FDG-PET was also superior to CT in the detection of liver metastasis. FDG-PET detected treatment response in 5 out of 15 cases after chemoradiation therapy, whereas CT could not detect any treatment response. Comparing responder and nonresponder, FDG-PET was able to predict significantly different prognosis (399 vs. 233 d, P<0.05).

CONCLUSIONS

FDG-PET is a very useful tool in diagnosing pancreatic cancer. FDG-PET may be also used as an adjunct for determining the treatment modality of pancreatic cancer and evaluating tumor response to chemoradiation therapy.

Gastrointestinal malignancies evaluated with (18)F-fluoro-2-deoxyglucose positron emission tomography

(18)F-fluoro-2-deoxyglucose positron emission tomography has demonstrated high accuracy in the staging and evaluation of colorectal and esophageal carcinomas. FDG PET is demonstrating increasing utility in a number of other gastrointestinal tumours and clinical scenarios. The established clinical indications for its use, the diagnostic accuracy, and limitations will be reviewed. Data on the emerging indications and limitations for pancreatic, hepatocellular, and gastric carcinomas, as well as gastrointestinal stromal tumours, cholangiocarcinoma, and carcinoma of unknown primary will also be briefly discussed. The use of combined PET-CT is demonstrating further improvements in diagnostic accuracy.

Autoimmune pancreatitis with hepatic inflammatory pseudotumor

We report a case of autoimmune pancreatitis (AIP) with hepatic inflammatory pseudotumor (IP). The patient was clinically diagnosed as having multiple metastatic tumors originated from cholangiocellular carcinoma as well as autoimmune pancreatitis and underwent left lobectomy of the liver. Histological examination showed a diffuse or dense lymphoplasmacytic infiltration with obliterating phlebitis but an absence of neoplastic proliferation both in the liver tumor and in the biopsy specimen of the pancreas. Abundant IgG4-positive plasma cells were seen in the lesions. This is the first case report that shows a simultaneous occurrence of hepatic IP and AIP, suggesting that these lesions appeared on the background of the recently proposed entity of IgG4-related systemic disease.

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.

Ultrasonography, computed tomography and magnetic resonance imaging for diagnosis and determining resectability of pancreatic adenocarcinoma: a meta-analysis

OBJECTIVE

To compare ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) in the diagnosis and determination of resectability of pancreatic adenocarcinoma.

METHODS

Articles reporting US, CT, or MRI data of patients with known or suspected pancreatic adenocarcinoma and at least 20 patients verified with histopathology, surgical findings, or follow-up were included. A bivariate random effects approach was used to calculate sensitivity and specificity for diagnosis and resectability of pancreatic adenocarcinoma.

RESULTS

Sixty-eight articles fulfilled all inclusion criteria. For diagnosis, sensitivities of helical CT, conventional CT, MRI, and US were 91%, 86%, 84%, and 76% and specificities were 85%, 79%, 82%, and 75% respectively. Sensitivities for MRI and US were significantly lower compared with helical CT (P = 0.04 and P = 0.0001). For determining resectability, sensitivities of helical CT, conventional CT, MRI, and US were 81%, 82%, 82, and 83% and specificities were 82%, 76%, 78%, and 63% respectively. Specificity of US was significantly lower compared with helical CT (P = 0.011).

CONCLUSIONS

Helical CT is preferable as an imaging modality for the diagnosis and determination of resectability of pancreatic adenocarcinoma.

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.

FDG-PET is able to detect pancreatic carcinoma in chronic pancreatitis

PURPOSE

2-(18F)-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is an imaging technique which enables detection of malignancies. FDG-PET has been established as a tool for the diagnosis of pancreatic carcinoma (CA). Early detection is mandatory as cure can only be achieved in non-advanced disease. This is, however, very difficult with conventional radiological techniques. Patients with chronic pancreatitis (CP) are at risk of developing CA. A simple, reliable screening method for malignant degeneration is highly desirable. We set out to investigate whether FDG-PET is able to detect CA in the setting of CP and can fulfil a potential role in the early detection of CA in CP.

METHODS

FDG-PET was performed in 77 CP patients and in six patients with CP complicated by CA (CP + CA). We included 26 CA patients as a positive control. A positive scan was defined as focal FDG accumulation in the pancreas region.

RESULTS

In 67 of the 77 CP (87%) patients, pancreatic FDG accumulation was absent. Six patients had significant accumulation. In CA, 24/26 patients had a positive PET. Five out of the six patients with CP + CA had focal uptake, while minor uptake was seen in one patient. FDG-PET was positive in almost all CA patients and CP + CA patients. FDG-PET was negative in the large majority (87%) of CP patients, which suggests that a positive PET scan in CP patients must lead to efforts to exclude a malignancy.

CONCLUSION

These data suggest that FDG-PET has a potential role as a diagnostic tool for detecting CA in longstanding CP.

PET imaging in assessing gastrointestinal tumors

The clinical usefulness of FDG-PET imaging is now firmly established in various situations, such as the preoperative staging of esophageal cancer and recurrent colorectal carcinoma and the detection and staging of recurrent colorectal cancer when there is a clinical or biologic suspicion with inconclusive conventional findings. Encouraging results were obtained in the evaluation of the therapeutic response of various gastrointestinal malignancies, either during the treatment or after its completion. There is no firm consensus regarding its role in pancreatic cancer, either proved or suspected, but it may be valuable in selected clinical situations. Its role seems fairly limited in patients with hepatocellular carcinoma, although PET findings may have prognostic implications. Evaluation of cholangiocarcinoma is an emerging indication, albeit with limited data to date. Finally, PET/CT is very likely to enhance the role of FDG imaging further in the work-up of patients with gastrointestinal tumors.

FDG-PET scanning in the diagnosis of gastrointestinal cancers

This review deals with the current, well-established indications for two-(18F)-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scanning in patients with gastrointestinal cancers. FDG-PET is a non-invasive, functional imaging technique. FDG exploits the native glucose transporter to enter the cell. Since many tumours have enhanced glucose uptake, FDG is readily accumulated in malignant cells and can be detected by a PET camera. FDG-PET has been established as an important diagnostic tool in clinical oncology. This review deals with the current, well-established indications for FDG-PET scanning in patients with gastrointestinal cancers. In the current practice, FDG-PET is most commonly used to stage oesophageal carcinoma, to detect and stage recurrence of colorectal carcinoma and to differentiate between benign and malignant pancreatic lesions. The benefit of FDG-PET scanning in patients with oesophagus carcinoma is best established in stage IV disease, as the diagnostic accuracy to detect metastatic disease is higher compared to the combination of computed tomography (CT) and endoscopic ultrasound (EUS). In patients with a history of colorectal carcinoma, FDG-PET scanning is particularly effective in diagnosing recurrent disease, especially in those with a rising carcinoembryonic antigen without a suspect lesion on conventional imaging. Large series have indicated that the sensitivity and specificity for detecting recurrent colorectal carcinoma are in the range of 87%-100% and 66%-100%, respectively. Equally, FDG-PET has a high sensitivity (68%-96%) and specificity (78%-100%) in detecting pancreatic carcinoma in patients with a suspicious-looking pancreatic mass on CT scan. Lastly, we focus on the use of FDG-PET as a modality for early monitoring of treatment response in patients with gastrointestinal stromal cell tumours. Without doubt, future developments will further establish the diagnostic role of the FDG-PET scan in the care of patients with gastrointestinal cancers.

PET/CT imaging in recurrent head and neck cancer

PET/CT offers advantages over PET alone, which is limited by poor anatomic localization and CT alone, which provides morphologic data only. Retrospective fusion of separately acquired PET and CT images allows for potential fusion misregistration in the mobile head and neck between imaging sessions. Indications for PET/CT include recurrent neoplasm, tumor surveillance, and staging. This article will focus on recurrent head and neck neoplasm including, head and neck cancer, thyroid cancer, recurrent skull base tumor. PET/CT may change management in facilitating earlier detection of recurrence than is possible with conventional CT or MR imaging, in guiding biopsy, and in detecting second primary sites and distant metastases. Limitations of PET/CT include physiologic uptake, metabolically active tissue, and muscle contraction during uptake phase. PET/CT, however, is better equipped than is PET alone to mitigate these limitations by precisely localizing FDG uptake to anatomic structures. In addition, small lesions (< 1 cm) may be below scanner resolution and, therefore, a lower SUV (that is < or = 3), may suggest neoplasm. Recent treatment may result in false negative findings, especially when PET is performed within 4 months of radiation therapy. Finally, tumors of low metabolic activity (e.g., salivary gland tumors) may be prone to false negative results. In the future, PET/CT imaging will become more useful in staging head and neck cancer with improved scanner resolution. Development of specific tumor markers may allow for tumor-specific ligands that will increase sensitivity to head and neck neoplasia. Treatment targeting for radiation therapy is an application that is likely to become widely used.

Diagnosis of pancreatic cancer using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) --usefulness and limitations in "clinical reality"

The present review will provide an overview of the literature concerning the FDG PET diagnosis of pancreatic cancer and a summary from our experience of 231 cases of pancreatic lesions. FDG PET can effectively differentiate pancreatic cancer from benign lesion with high accuracy. Newly-developed PET scanners can detect small pancreatic cancers, up to 7 mm in diameter, by their high resolution, which could make a great contribution to the early detection of resectable and potentially curable pancreatic cancers. FDG PET is useful and cost-beneficial in the pre-operative staging of pancreatic cancer because an unexpected distant metastasis can be detected by whole-body PET in about 40% of the cases, which results in avoidance of unnecessary surgical procedures. FDG PET is also useful in evaluation of the treatment effect, monitoring after the operation and detection of recurrent pancreatic cancers. However, there are some drawbacks in PET diagnosis. A relatively wide overlap has been reported between semiquantitative uptake values obtained in cancers and those in inflammatory lesions. As for false-positive cases, active and chronic pancreatitis and autoimmune pancreatitis sometimes show high FDG accumulation and mimic pancreatic cancer with a shape of focal uptake. There were 8 false negative cases in the detection of pancreatic cancer by FDG PET, up to 33 mm in diameter, mainly because of their poor cellularity in cancer tissues. In addition, there are 19% of cancer cases with a decline in FDG uptake from 1 hr to 2 hr scan. FDG PET was recently applied to and was shown to be feasible in the differential diagnosis of cystic pancreatic lesions, such as intraductal papillary mucinous tumor of the pancreas. Further investigations are required to clarify the clinical value of FDG PET in predicting prognosis of the pancreatic patients.

Pancreatic cancer: preliminary experience with sodium iodide fluorodeoxyglucose positron emission tomography in Australia

Previous studies of fluorodeoxyglucose positron emission tomography (FDG-PET) in pancreatic cancer have used Bismuth Germinate detector systems. This preliminary Australian study aims to confirm the accuracy of FDG-PET in pancreatic cancer using a dedicated sodium iodide (NaI) PET system. Fifteen consecutive patients underwent FDG-PET using a GE QUEST dedicated NaI PET scanner. The indications were the characterization of a pancreatic mass seen on CT or ultrasonographic imaging (nine cases), diagnosis or exclusion of recurrent disease following surgery and adjuvant therapy (four cases) and presurgical staging of primary pancreatic cancer (two cases). The final diagnosis was determined from histology or, when no histology was available, by radiological and clinical follow up. The FDG-PET accurately characterized eight out of nine pancreatic masses (seven were true negative, one was true positive and one was false positive). Of the four cases performed to determine recurrent disease, three were accurately diagnosed (two true negatives and one true positive). In the fourth case, PET accurately detected a liver metastasis but did not detect the local recurrence. Results in the two cases where PET was performed for preoperative staging comprised one true positive and one false negative. Sodium iodide FDG-PET is useful in the diagnosis of pancreatic cancer, particularly in the presence of a previously detected mass.

Timing and extent of surgical intervention in patients from hereditary pancreatic cancer kindreds

Our knowledge of the molecular and genetic etiology of hereditary pancreatic cancer has expanded considerably and is steadily increasing. However, there are only a few hard data available regarding the clinical and surgical management of these patients. Surgery is currently performed when we detect dysplastic changes in the pancreas or when cancer is suspected. Of the available diagnostic modalities, endoscopic ultrasonography has proven so far to be the most useful for detecting dysplastic changes in the pancreases of patients from hereditary pancreatic cancer kindreds. It seems reasonable, once dysplasia has been diagnosed in a high-risk patient, to proceed to total pancreatectomy. The multifocal nature of dysplastic lesions precludes any type of operation that would leave behind pancreatic tissue. Currently, prophylactic whole-organ resection in the absence of premalignant lesions cannot be recommended since we do not know the exact risk for the development of cancer.

Whole-body FDG-PET imaging in the management of patients with cancer

Fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is increasingly used for the management of patients with cancer. The technique is now well accepted by most physicians as an effective complement to the existing imaging modalities. For many malignancies, PET achieves high sensitivity and specificity. The critical role of this powerful technique is realized increasingly in the day-to-day practice of oncology. This is particularly true for the management of patients with non-small-cell lung cancer (NSCLC). The contribution of PET for the selection of patients eligible for curative treatments in this setting is well established. Convincing data also exist to support the use of PET for evaluating patients with recurrent colorectal carcinoma, for staging and restaging lymphomas, and for diagnosing recurrent thyroid carcinoma in the presence of elevated thyroglobulin and negative 131I scans. Other indications include staging of various recurrent malignancies, such as breast cancer, melanoma, and head and neck and gynecologic carcinomas. Existing data are limited for the determination of the impact of PET in certain malignancies, and further studies, which should include outcome information, will allow clarification of the role of this modality for such indications. Despite the small number of studies specifically designed to assess changes in management plans for some malignancies after performing PET the overall favorable results are encouraging enough at this time to include this modality as an essential element of the practice of modern oncology. Finally, the evolving role of PET imaging as a predictor of response after local or systemic treatment may add a major dimension to the application of this novel technique.

Is a preoperative multidiagnostic approach to predict surgical resectability of periampullary tumors still effective?

BACKGROUND

Multimodality staging is recommended in patients with periampullary tumors to optimize preoperative determination of resectability. We investigated the potency of currently used diagnostic procedures in order to determine resectability.

METHODS

Ninety-five consecutive patients with periampullary tumors prehospitally staged resectable underwent preoperative diagnostic tests: helical-computed tomography (CT) with maximum intensity projection of arterial vessels (MIP), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreaticography (MRCP), endoscopic ultrasonography (EUS), endoscopic retrograde cholangiopancreaticography (ERCP), digital subtraction angiography (DSA), and positron emission tomography (PET). Diagnoses were verified by surgery and histopathology.

RESULTS

In 45 patients with benign and 50 patients with malignant periampullary tumors sensitivity for tumor diagnosis was 89% to 96% in CT, MRI, EUS, and PET. Small tumors were best diagnosed by EUS (100%). Diagnosis of malignancy was made with 85% (EUS), 83% (CT), 82% (PET), and 72% (MRI) accuracy. Arterial vessel infiltration was best predicted by CT/MIP with an accuracy of 85%. For venous vessel infiltration MRI reached 85% accuracy. Accuracy rates for local nonresectability were 93% (EUS), 92% (MRI), and 90% (CT). Two and 4 of 8 patients with distant metastases were identified by CT and PET, respectively. The correct diagnosis of malignancy and determination of resectability was made by CT in 71% and by MRI in 70%. Biliary stenting reduced accuracy of CT diagnosis of malignancy from 88% to 73%.

CONCLUSIONS

CT obtained before stenting was the single most useful test, providing correct diagnosis in 88% and resectability in 71% of patients. If no tumor is depicted in CT, EUS should be added. Uncertain venous vessel infiltration can be verified by MRI or EUS. Angiography should no longer be a routine diagnostic procedure. Equivocal tumors or possible metastasis may be further examined with PET.

Positron emission tomography imaging in oncology

The applications for FDG-PET imaging are rapidly growing and accepted in the field of oncology. FDG-PET imaging does not replace other imaging modalities, such as CT, but seems to be very helpful in specific situations where CT has known limitations, such as differentiation of benign from malignant indeterminate lesions on CT, differentiation of post-treatment changes versus recurrent tumor, differentiation of benign from malignant lymph nodes, and monitoring therapy. The biggest use of FDG-PET presently is in N and M staging of various body tumors. The addition of FDG-PET in the evaluation of oncologic patients in well-defined algorithms including a combination of imaging studies seems to be cost effective by accurately identifying patients who benefit from invasive procedures and saving unnecessary costly invasive procedures on patients who do not benefit from them. Although PET imaging may decrease the cost of health care by reducing the number of invasive procedures, implementation of clinical PET has been hindered by the high cost of the purchase, operation expenses, and maintenance of PET systems; the need for immediate access to a source of 18F (owing to the 110-minute half-life); and the limited reimbursement for clinical procedures by third-party payers. These combined factors have resulted in the development by manufacturers of hybrid gamma camera systems capable of performing positron imaging. These systems can be used to image conventional radiopharmaceuticals used in general nuclear medicine and positron-emitting radiopharmaceuticals. The performance of these camera-based PET systems has improved markedly over the past few years with the introduction of thicker NaI (T1) crystals, iterative reconstruction algorithms, and attenuation correction. These new developments in medical imaging instrumentation have contributed to the expansion of the number of cyclotrons, and have driven the concept of commercial FDG distribution centers.

Limited value of positron emission tomography in treatment of pancreatic cancer: surgeon's view

We aimed to assess, from a surgical point of view, the value of positron emission tomography (PET) in the routine preoperative diagnostic evaluation of a pancreatic mass. In particular, we were interested in PET's ability to distinguish a malignancy from a nonmalignant process and its impact on surgical decision making. We documented prospectively the results of preoperative ultrasonography, computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP), and PET in terms of a correct diagnosis of malignancy in 103 patients. All patients underwent surgery at our department and had a complete histologic workup. We then related the preoperative findings to the intraoperative and histologic findings and analyzed the advantages and limitations of PET in comparison with conventional diagnostic techniques. Both CT and PET showed high sensitivities (82% and 84%, respectively) but rather low specificities (61%). ERCP showed good specificity at 83% but weak sensitivity at 46%. The positive predictive value was higher than 80% for all methods, whereas the negative predictive value was around 60% at best. Both the CT and the PET diagnoses were wrong in 15% of the cases. In all cases with a false CT diagnosis, the results of the other conventional examinations provided sufficient evidence to indicate the need for surgical intervention. In all cases where PET gave misleading results, CT findings indicated the need for surgery. PET overlooked pT1 cancers in three of the patients. PET does not reliably prove or exclude malignancy in situations where conventional diagnostic procedures leave doubt as to the nature of a pancreatic mass. PET does introduce a new procedure-related spectrum of misinterpretations to the diagnostic process.

Diagnostic usefulness of FDG PET for pancreatic mass lesions

The purpose of this study was to investigate the feasibility of [18F]2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET) in patients with a pancreatic mass by comparing the results with those of X-ray computed tomography (CT) and magnetic resonance (MR) imaging.

METHODS

Eighty-six patients with pancreatic lesions, included 65 malignant tumors and 21 benign masses (55 masses were proven histologically and the others were diagnosed clinically), were studied. The diagnostic factors of CT and MR imaging were evaluated, and those of FDG PET were also evaluated for malignant and benign masses by visual interpretation and quantitative interpretation with the standardized uptake value (SUV) and SUVgluc which was designed to reduce the effects of a high blood sugar level. Visual interpretations were evaluated only in FDG PET images, and quantitative interpretations were evaluated by referring to CT and/or MR imaging. The correlation between SUV and the degree of histological differentiation in pancreatic ductal adenocarcinoma was investigated.

RESULTS

Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for CT imaging were 91, 62, 88, 68 and 84%, and for MR imaging 78, 70, 88, 54 and 76%, respectively. In visual interpretation of FDG PET images, the sensitivity, specificity, PPV, NPV and accuracy were 82, 81, 93, 59 and 81%, respectively. Significant differences between malignant and benign lesions existed in SUV and SUVgluc (p < 0.0001, each). With the cutoff value of SUV as 2.1 and SUVgluc as 2.2, the accuracy of diagnosis was maximal. With that cutoff value, the sensitivity, specificity, PPV, NPV and accuracy for SUV were 89, 76, 92, 70 and 86%, and for SUVgluc 91, 76, 92, 73 and 87%, respectively. The sensitivity and NPV of SUVgluc were higher than those of SUV, which suggests that SUVgluc may be more useful in reducing the number of overlooked malignant tumors. The specificity and PPV of FDG PET were superior to those of CT and MR imaging. There were no significant differences between the SUVs of moderately differentiated adenocarcinomas and those of well differentiated adenocarcinomas.

CONCLUSION

To improve the diagnostic procedure for classifying masses, FDG PET with not only SUV but also SUV corrected by the blood sugar level is required in addition to morphological diagnosis by CT and/or MR imaging.

Surveillance of pre-malignant disease of the pancreatico-biliary system

Technical advancements in ultrasonography, contrast-enhanced computed tomography and magnetic resonance imaging, as well as the wider availability of these ultramodern imaging techniques, have resulted in the early detection and a better classification of various asymptomatic and symptomatic pancreatico-biliary lesions. Pre-malignant biliary and pancreatic lesions are rare disorders, and no clear data are available to define their malignant potential. Because of the lack of controlled epidemiological data, the time span for malignant transformation and its frequency cannot be defined in the majority of these lesions. Adenomyomatosis of the gallbladder and gallbladder polyps larger than 10 mm should be treated by cholecystectomy even in asymptomatic patients because of an increased risk of malignant transformation. Chronic cholangitis, primary sclerosing cholangitis and choledochal cysts are also pre-malignant conditions. The timing of surgery, once it is advised for a pre-malignant condition that is still benign, should, however, be individualized to the particular patient situation. In patients with chronic pancreatitis, surgery may be indicated for disease-related complications. In as much as chronic pancreatitis predisposes to a higher risk of pancreatic cancer, any suspicion of malignancy should warrant a surgical exploration. Intraductal papillary tumours and mucin-producing pancreatic tumours are other pre-malignant pancreatic lesions whose malignant potential cannot be precisely determined pre-operatively. They should be resected in situations where there is a high degree of suspicion even without a clear objective diagnosis. In conclusion, pre-malignant hepato-biliary and pancreatic lesions of uncertain pathology should undergo early resection in view of treatment limitations and the dismal prognosis of established cancers. While hepato-biliary and pancreatic surgery is nowadays performed in specialized centres, with a low post-operative morbidity and mortality, it is equally important to understand that observation alone with regular computed tomography or magnetic resonance imaging control can no longer be recommended in the management of these lesions.

The role of nuclear medicine in the evaluation of pancreatic disease

F-18 FDG PET in patients with nonendocrine pancreatic cancer and somatostatin receptor imaging in patients with endocrine pancreatic cancer have an important role in detecting or confirming the presence of a mass in the pancreas--a crucial step in the management of these patients. Both agents also have an important role in staging and in defining which patients are good candidates for resection surgery. Somatostatin receptor imaging also has a crucial role in selecting from the various systemic therapeutic options available. I-131 MIBG therapy can be of value therapeutically, mostly palliative, in patients who demonstrate a markedly elevated concentration of tumor radioactivity.

Positron emission tomography (PET) and other nuclear medicine modalities in staging gastrointestinal cancer

Gastrointestinal (GI) cancers account for the second highest number of new tumor cases and deaths per year in the United States and Western Europe. The most frequently involved sites are, in descending order, the colorectum, stomach, pancreas, liver, bile duct, and esophagus. The most common tumor type is adenocarcinoma. Among the epithelial cancers, great attention has recently been given to the tumors of neuroendocrine origin. These concepts are relevant because nuclear medicine imaging is based on visualization by means of a particular uptake of radiolabelled tracers in cancer cells that concentrate the radioactive signal. This signal is detected and reconstructed in planar or tomographic images. Different radiopharmaceuticals have been proposed for diagnostic application in oncology (such as radiolabelled monoclonal antibodies (MAbs), receptor tracers, and positron-emitting radiopharmaceuticals), and they are currently used as tracers for tumor detection with different modalities and techniques. Most of these techniques demonstrate their clinical usefulness in the diagnosis of GI cancer. This work is not intended to be a comprehensive review of all the extensive experience and possibilities of nuclear medicine for the diagnosis of GI tumors; rather, it aims to summarize the current status of the most important approaches and their main indications in staging GI cancers.

Fluorodeoxyglucose positron emission tomography and the prognosis of pancreatic carcinoma

BACKGROUND

Pancreatic carcinoma is associated with a poor prognosis. The aim of this study was to determine whether glucose metabolism in pancreatic cancer has prognostic significance for patients suffering from this disease.

METHODS

The survival data of 52 patients with pancreatic carcinoma was correlated with the standardized uptake value (SUV) as a semiquantitative parameter of glucose metabolism, as determined with fluorodeoxyglucose positron emission tomography (FDG PET). A multivariate analysis, including SUV and accepted factors of prognosis, such as stage at presentation and tumor marker Ca 19-9, was performed to determine the prognostic value of FDG PET.

RESULTS

The median survival in 26 patients with low SUV (< 6.1) was 9 months (95% confidence interval 6-12 months) vs. 5 months (95% confidence interval 4-6 months) in 26 patients with high SUV (> or = 6.1). Multivariate analysis revealed SUV and tumor marker Ca 19-9 as independent factors of prognosis in patients with pancreatic carcinoma.

CONCLUSION

Glucose metabolism, as determined with FDG PET, provides additional prognostic information in patients with pancreatic carcinoma.