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

Preoperative FDG-PET predicts early recurrence and a poor prognosis after resection of pancreatic adenocarcinoma

OBJECTIVE

The aim of this study was to evaluate the clinical utility of preoperative 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) as a prognostic predictor of resectable pancreatic adenocarcinoma.

METHODS

A total of 128 patients with resected pancreatic adenocarcinoma who preoperatively underwent FDG-PET examinations were studied. The maximum standard uptake value (SUVmax) was calculated for each primary lesion. A receiver operating characteristics (ROC) curve was constructed to estimate the optimal cutoff value of the SUVmax. In order to determine which outcomes of interest were appropriately demonstrated, ROC curve analyses were conducted for six outcomes: 6-, 12-, and 24-month disease-free survival (DFS), and 6-, 12-, and 24-month overall survival (OS). A multivariate analysis was conducted to identify prognostic factors.

RESULTS

The ROC curves revealed that the SUVmax predicted the 6-month DFS most optimally (area under the curve 0.757), with a cutoff value of 6.0. Of the 69 patients with an SUVmax ≥ 6.0, 34 (49 %) developed recurrence within 6 months. In contrast, only 3 of 59 (5 %) patients with an SUVmax < 6.0 exhibited early recurrence (p < 0.001). The median OS time was 37 months in patients with an SUVmax < 6.0 and 18 months in patients with an SUVmax ≥ 6.0 (p < 0.001). The multivariate analysis revealed lymph node metastasis (hazard ratio [HR] 2.31; p = 0.001) and an SUVmax ≥ 6.0 (HR 2.05; p = 0.002) to be significantly correlated with a poor survival.

CONCLUSIONS

An SUVmax ≥ 6.0 was a significant predictor of early postoperative recurrence and subsequent poor survival following resection of pancreatic adenocarcinoma.

[18F]Fluorodeoxyglucose PET/Computed Tomography in Gastrointestinal Malignancies

This article discusses the current state-of-the-art application of 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG)-PET and FDG-PET/computed tomography (CT) in the management of patients with gastrointestinal malignancies. Gastrointestinal malignancies include many different cell types, several common malignancies of which may be imaged by FDG-PET/CT. This review focuses on gastric carcinoma, pancreatic carcinoma, hepatocellular carcinoma, cholangiocarcinoma, colorectal carcinoma, and stroma cell tumors. The role of FDG-PET/CT in staging these malignancies is discussed, in addition to (re)staging, detection of recurrent disease, patient selection/prognostication, and response assessment, using the currently available literature.

Imaging diagnosis of pancreatic cancer: A state-of-the-art review

Pancreatic cancer (PC) remains one of the deadliest cancers worldwide, and has a poor, five-year survival rate of 5%. Although complete surgical resection is the only curative therapy for pancreatic cancer, less than 20% of newly-diagnosed patients undergo surgical resection with a curative intent. Due to the lack of early symptoms and the tendency of pancreatic adenocarcinoma to invade adjacent structures or to metastasize at an early stage, many patients with pancreatic cancer already have advanced disease at the time of their diagnosis and, therefore, there is a high mortality rate. To improve the patient survival rate, early detection of PC is critical. The diagnosis of PC relies on computed tomography (CT) and/or magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP), or biopsy or fine-needle aspiration using endoscopic ultrasound (EUS). Although multi-detector row computed tomography currently has a major role in the evaluation of PC, MRI with MRCP facilitates better detection of tumors at an early stage by allowing a comprehensive analysis of the morphological changes of the pancreas parenchyma and pancreatic duct. The diagnosis could be improved using positron emission tomography techniques in special conditions in which CT and EUS are not completely diagnostic. It is essential for clinicians to understand the advantages and disadvantages of the various pancreatic imaging modalities in order to be able to make optimal treatment and management decisions. Our study investigates the current role and innovative techniques of pancreatic imaging focused on the detection of pancreatic cancer.

Diagnostic evaluation of solid pancreatic masses

Determining the etiology of a solid pancreatic lesion is a critical first step toward developing an appropriate treatment plan for patients with a benign or malignant pancreatic mass. Technological advances in cross-sectional and endoscopic imaging modalities offer pancreatic imaging options with degrees of resolution that were not available even 15-20 years ago. In most cases, the nature of a solid pancreatic mass can be determined using computerized tomography, magnetic resonance imaging, and endoscopic ultrasound with fine-needle aspiration. Knowledge about the basics of these modalities, as well as their strengths and limitations, plays an important role in understanding how patients with solid pancreatic masses should be evaluated.

Limited efficacy of (18)F-FDG PET/CT for differentiation between metastasis-free pancreatic cancer and mass-forming pancreatitis

OBJECTIVE

Differentiation between metastasis-free pancreatic cancer and mass-forming pancreatitis is important to avoid unnecessary operative procedures. This study was aimed at evaluating the efficacy of PET/CT with F-FDG (FDG PET/CT) for the differential diagnosis between them.

PATIENTS AND METHODS

FDG-PET/CT was performed in 47 study patients with pancreatic masses and without any detectable metastases, 33 of which cases were finally diagnosed as pancreatic cancer and the other 14 as pancreatitis, and the corresponding imaging data were evaluated retrospectively. The maximal SUV (SUVmax) within the masses were determined at 1 hour and mostly at 2 hours after intravenous injection of FDG.

RESULTS

SUVmax at 1 hour in pancreatic cancer was significantly higher than that in mass-forming pancreatitis, and the change in SUVmax from 1- to 2-hour time points was more consistent with pancreatic cancer than with mass-forming pancreatitis. However, there remained considerable overlapping between the SUVmax values of both diseases except either at the higher range for pancreatic cancer (> 7.7 at 1 hour or > 9.98 at 2 hours) or at the lower range for mass-forming pancreatitis (<3.37 at 1 hour or <3.53 at 2 hours). No obvious difference was found in the FDG uptake patterns of the mass areas between both diseases.

CONCLUSIONS

Differentiation between metastasis-free pancreatic cancer and mass-forming pancreatitis is difficult by FDG-PET/CT due to considerable overlapping between the SUVmax values of the two diseases, although the differential diagnosis may be possible either at the higher range of SUVmax (> 7.7 at 1 hour or > 9.98 at 2 hours) for pancreatic cancer or at the lower range of SUVmax (<3.37 at 1 hour or <3.53 at 2 hours) for mass-forming pancreatitis.

Application of nanoparticles on diagnosis and therapy in gliomas

Glioblastoma multiforme (GBM) is one of the most deadly diseases that affect humans, and it is characterized by high resistance to chemotherapy and radiotherapy. Its median survival is only fourteen months, and this dramatic prognosis has stilled without changes during the last two decades; consequently GBM remains as an unsolved clinical problem. Therefore, alternative diagnostic and therapeutic approaches are needed for gliomas. Nanoparticles represent an innovative tool in research and therapies in GBM due to their capacity of self-assembly, small size, increased stability, biocompatibility, tumor-specific targeting using antibodies or ligands, encapsulation and delivery of antineoplastic drugs, and increasing the contact surface between cells and nanomaterials. The active targeting of nanoparticles through conjugation with cell surface markers could enhance the efficacy of nanoparticles for delivering several agents into the tumoral area while significantly reducing toxicity in living systems. Nanoparticles can exploit some biological pathways to achieve specific delivery to cellular and intracellular targets, including transport across the blood-brain barrier, which many anticancer drugs cannot bypass. This review addresses the advancements of nanoparticles in drug delivery, imaging, diagnosis, and therapy in gliomas. The mechanisms of action, potential effects, and therapeutic results of these systems and their future applications in GBM are discussed.

Positron emission tomography in malignancies of the liver, pancreas and biliary tract - indications and potential pitfalls

Abstract Malignancies of the hepato-pancreatico-biliary (HPB) system are relatively common and generally characterized by a dismal prognosis. Positron emission tomography (PET) is a functional imaging technique that has emerged as an important modality in oncological decision-making. The principal radiopharmaceutical in PET imaging is the glucose analog (18)F-fluorodeoxyglucose, which is able to detect altered glucose metabolism in malignant tissue. PET is typically used in conjunction with computed tomography (CT), and previous studies have supported several uses of PET/CT in HPB malignancies, including staging, differential diagnostics and monitoring of treatment response and progress of disease. A review of PET/CT in the context of HPB malignancies will be presented, including indications and potential pitfalls.

FDG PET and PET/CT

Molecular imaging with positron emission tomography (PET) using tumour-seeking radiopharmaceuticals has gained wide acceptance in oncology with many clinical applications. The hybrid imaging modality PET/CT allows assessing molecular as well as morphologic information at the same time. Therefore, PET/CT represents an efficient tool for whole body staging and re-staging within one imaging modality. In oncology the glucose analogue (18)F-fluorodeoxyglucose (FDG) is the most widely used PET and PET/CT radiopharmaceutical in clinical routine. FDG PET and PET/CT have been used for staging and re-staging tumour patients in numerous studies. This chapter will discuss the use and the main indications of FDG PET and PET/CT in oncology with special emphasis on lung cancer, oesophageal cancer, colorectal cancer, head and neck cancer, lymphoma and breast cancer (among other tumour entities). A review of the current literature will be given with respect to primary diagnosis, staging and diagnosis of recurrent disease (local, lymph node and distant metastases). Besides its integral role in diagnosis, staging and re-staging of disease in oncology, there is increasing evidence that FDG PET and PET/CT can significantly contribute to therapy response assessment possibly influencing therapeutic management and treatment planning, to therapy tumour control and prediction of prognosis in oncologic patients, which will also be discussed in this chapter.

Utility of contrast-enhanced FDG-PET/CT in the clinical management of pancreatic cancer: impact on diagnosis, staging, evaluation of treatment response, and detection of recurrence

OBJECTIVES

Fluorodeoxyglucose (FDG)-positron emission tomography/contrast-enhanced computed tomography (PET/CE-CT) involving whole-body scanning first by non-CE-CT and FDG-PET followed by CE-CT has been used for detailed examination of pancreatic lesions. We evaluated PET/CE-CT images with regard to differential diagnosis, staging, treatment response, and postoperative recurrence in pancreatic cancer.

METHODS

Positron emission tomography/CE-CT was conducted in 108 patients with pancreatic cancer and in 41 patients with other pancreatic tumor diseases.

RESULTS

The maximum standardized uptake value (SUV(max)) overlapped in benign and malignant cases, suggesting that differential diagnosis of pancreatic tumors based on the SUV(max) is difficult. In the evaluation of staging in 31 resectable pancreatic cancer by PET/CE-CT, the diagnostic accuracy rate was more than 80% for most factors concerning local invasion and 94% for distant metastasis but only 42% for lymph node metastasis. Significant positive correlations were found between the SUV(max) and tumor size/markers, suggesting that SUV(max) may be a useful indicator for the treatment response. Regarding the diagnosis of the postoperative recurrence, PET/CE-CT correctly detected local recurrence in all the 11 cases of recurrence, whereas abdominal CE-CT detected only 7 of 11 cases, suggesting that PET/CE-CT is superior in this context.

CONCLUSIONS

Positron emission tomography/CE-CT is useful for the clinical management of pancreatic cancer.

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

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

Stroma targeting nuclear imaging and radiopharmaceuticals

Malignant transformation of tumor accompanies profound changes in the normal neighboring tissue, called tumor stroma. The tumor stroma provides an environment favoring local tumor growth, invasion, and metastatic spreading. Nuclear imaging (PET/SPECT) measures biochemical and physiologic functions in the human body. In oncology, PET/SPECT is particularly useful for differentiating tumors from postsurgical changes or radiation necrosis, distinguishing benign from malignant lesions, identifying the optimal site for biopsy, staging cancers, and monitoring the response to therapy. Indeed, PET/SPECT is a powerful, proven diagnostic imaging modality that displays information unobtainable through other anatomical imaging, such as CT or MRI. When combined with coregistered CT data, [(18)F]fluorodeoxyglucose ([(18)F]FDG)-PET is particularly useful. However, [(18)F]FDG is not a target-specific PET tracer. This paper will review the tumor microenvironment targeting oncologic imaging such as angiogenesis, invasion, hypoxia, growth, and homing, and also therapeutic radiopharmaceuticals to provide a roadmap for additional applications of tumor imaging and therapy.

Pancreatic cancer: translational research aspects and clinical implications

Despite improvements in surgical techniques and adjuvant chemotherapy, the overall mortality rates in pancreatic cancer have generally remained relatively unchanged and the 5-year survival rate is actually below 2%. This paper will address the importance of achieving an early diagnosis and identifying markers for prognosis and response to therapy such as genes, proteins, microRNAs or epigenetic modifications. However, there are still major hurdles when translating investigational biomarkers into routine clinical practice. Furthermore, novel ways of secondary screening in high-risk individuals, such as artificial neural networks and modern imaging, will be discussed. Drug resistance is ubiquitous in pancreatic cancer. Several mechanisms of drug resistance have already been revealed, including human equilibrative nucleoside transporter-1 status, multidrug resistance proteins, aberrant signaling pathways, microRNAs, stromal influence, epithelial-mesenchymal transition-type cells and recently the presence of cancer stem cells/cancer-initiating cells. These factors must be considered when developing more customized types of intervention ("personalized medicine"). In the future, multifunctional nanoparticles that combine a specific targeting agent, an imaging probe, a cell-penetrating agent, a biocompatible polymer and an anti-cancer drug may become valuable for the management of patients with pancreatic cancer.

An autopsy study to clarify characteristics of local recurrence after extended pancreatectomy with intraoperative radiation therapy in patients with pancreatic cancer

PURPOSE

Local relapses frequently occur even after curative resection of pancreatic cancer. To control local recurrence, we adopted extended radical resection combined with intraoperative radiation therapy.

METHODS

A retrospective review was conducted on 41 patients who underwent extended radical pancreatectomy combined with intraoperative radiation therapy for pancreatic cancer. Fourteen patients underwent autopsies. We took en bloc specimens of the abdominal aorta with surrounding connective tissue to evaluate histological characteristics of local status at autopsies.

RESULTS

Autopsies disclosed microscopic local recurrence in five (36%) of the 14 patients, although no evidence of local relapse was observed in either follow-up images or macroscopic findings at autopsy. Of the three patients with R1 resection, two had no local recurrence microscopically at autopsy. Histological features of local recurrence in autopsy samples showed small numbers of cancer cells surrounded by thick connective tissue without mass formation.

CONCLUSIONS

The autopsy study revealed that a characteristic of local recurrence after this treatment was tiny cancer cells scattered in dense connective tissue; these cells were undetected by follow-up imaging.

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

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

Recurrent pancreatic carcinoma and cholangiocarcinoma: 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT)

Although the current literature is limited, available data suggest that (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) imaging improves the evaluation of patients with recurrent pancreatic carcinoma and cholangiocarcinoma. There is evidence that PET/CT is particularly useful in the setting of elevated tumor markers and negative or equivocal CT findings. This article reviews the nature of these carcinomas in the post-therapy setting and describes the strengths and limitations of PET/CT when used for monitoring recurrence.

Local recurrence of pancreatic cancer after primary surgical intervention: how to deal with this devastating scenario?

The dismal prognosis of pancreatic cancer reflects into the increased recurrence rate, even after R0 pancreaticoduodenectomy. Although, conventional radiation-, chemo- or surgical therapy in much selected cases, seem to work out favorably long term, less invasive and non-toxic methods with more immediate results are always preferred, concerning the already aggravated status of this group of patients. We present hereby a comprehensive review of the literature concerning the treatment of recurrent pancreatic cancer based on the case of a patient who 20 months after a pancreaticoduodenectomy developed portal hypertension and symptomatic first degree esophageal, gastric and mesenteric varices, caused by the nearly complete splenic vein obstruction at the portal vein confluence. The varices were revascularized by a percutaneous transhepatic placement of an endovascular stent into the splenic vein, along with a sequent stereotactic body radiation therapy for the local tumor control. Thanks to the accuracy and safety of the present combined treatment, the patient one year later presents control of the disease and its complications. Our paper is the first in the international literature that tries to review all the treatment modalities available (surgical, adjuvant, neoadjuvant and palliative therapy) and their efficacy, concerning the locally recurrent pancreatic cancer; furthermore, we tried to analyze the application of the above mentioned combined therapeutic approach in similar cases, elucidating simultaneously all the questions that arise. The limited existing data in the international literature and the lack of randomized controlled trials make this effort difficult, but the physician should be aware after all of all the available and innovative treatment modalities, before he chooses one. Finally, we would like to emphasize the fact that not only the local control but also the management of the complications are important for a prolonged median survival and a better quality of life after all.

FDG-PET for hepatobiliary and pancreatic cancer: Advances and current limitations

In Japan, the use of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for some malignant tumors came to be covered by the National Health Insurance in 2002. In 2010, the health insurance coverage was expanded to all types of malignant tumors. However, since PET examination requires a large amount of capital investment, facilities at which PET is available are still limited. On the other hand, PET equipment has rapidly been introduced in large hospitals and in the diagnostic imaging centers of major cities during the past few years. Although numerous middle-sized and small hospitals cannot afford to perform PET, physicians can refer their patients to facilities where PET is available. Therefore, it is essential for general physicians to gain accurate knowledge on PET, including the appropriate indications for PET, in order to select patients for referral to PET facilities. PET is not always a useful tool, especially for lesions of the pancreas and hepatobiliary system, which is the main topic of this review. The indications of PET for lesions in these organs vary depending on the purpose of the examination. In this article, we review the indications for PET (or PET/computed tomography [CT]) using FDG of the liver, biliary tract, and pancreas.

Reactive hypertrophy of an accessory spleen mimicking tumour recurrence of metastatic renal cell carcinoma

De novo occurrence of an accessory spleen after splenectomy is worth noting for two reasons. First, it is known that splenectomy can cause reactive hypertrophy of initially inactive and macroscopically invisible splenic tissue. Second, it can mimic tumour recurrence in situations in which splenectomy has been performed for oncological reasons. This might cause difficulties in differential diagnosis and the clinical decision for reoperation. We report the case of a patient with suspected recurrence of renal cell carcinoma after total pancreatectomy and splenectomy for metastatic renal cell carcinoma, which finally revealed an accessory spleen as the morphological correlate of the newly diagnosed mass in the left retroperitoneum.

Value of contrast-enhanced 18F-fluorodeoxyglucose positron emission tomography/computed tomography in detection and presurgical assessment of pancreatic cancer: a prospective study

BACKGROUND AND AIM

Positron Emission Tomography (PET) using (18)F-fluorodeoxyglucose (FDG) associated with computed tomography (CT) is increasingly used for the detection and the staging of pancreatic cancer, but data regarding its clinical added value in pre-surgical planning is still lacking. The aim of this study is to investigate the performance of FDG PET associated with contrast-enhanced CT in detection of pancreatic cancer.

METHODS

We prospectively evaluated FDG PET/CT studies obtained in patients with suspicion of operable pancreatic cancer between May 2006 and January 2008. Staging was conducted according to a standardized protocol, and findings were confirmed in all patients by surgical resection or biopsy examination.

RESULTS

Forty-five patients with a median age of 69 (range 22-82) were included in this study. Thirty-six had malignant tumors and nine had benign lesions (20%). The sensitivity of enhanced versus unenhanced PET/CT in the detection of pancreatic cancer was 96% versus 72% (P=0.076), the specificity 66.6% versus 33.3% (P=0.52), the positive predictive value 92.3% versus 80% (P=0.3), the negative predictive value 80% versus 25% (P=0.2), and the accuracy 90.3% versus 64% (P=0.085).

CONCLUSIONS

Our preliminary data obtained in a limited number of patients shows that contrast-enhanced FDG PET/CT offers good sensitivity in the detection and assessment of pancreatic cancer, but at the price of a relatively low specificity. Enhanced PET/CT seems to be superior to unenhanced PET/CT. Further larger prospective studies are needed to establish its value for pre-surgical diagnosis and staging in pancreatic cancer.

CT diagnosis of recurrence after pancreatic cancer: Is there a pattern?

AIM: To investigate predilection sites of recurrence of pancreatic cancer by computed tomography (CT) in follow-up after surgery.

METHODS: Seventy seven patients with recurrence after pancreatic cancer surgery were retrospectively identified. The operative technique, R-status, T-stage and development of tumor markers were evaluated. Two radiologists analyzed CT scans with consensus readings. Location of local recurrence, lymph node recurrence and organ metastases were noted. Surgery and progression of findings on follow-up CT were considered as reference standard.

RESULTS: The mean follow-up interval was 3.9 ± 1.8 mo, with a mean relapse-free interval of 12.9 ± 10.4 mo. The predominant site of recurrence was local (65%), followed by lymph node (17%), liver metastasis (11%) and peritoneal carcinosis (7%). Local recurrence emerged at the superior mesenteric artery (n = 28), the hepatic artery (n = 8), in an area defined by the surrounding vessels: celiac trunk, portal vein, inferior vena cava (n = 22), and in a space limited by the mesenteric artery, portal vein and inferior vena cava (n = 17). Lymph node recurrence occurred in the mesenteric root and left lateral to the aorta. Recurrence was confirmed by surgery (n = 22) and follow-up CT (n = 55). Tumor markers [carbohydrate antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA)] increased in accordance with signs of recurrence in most cases (86% CA19-9; 79.2% CEA).

CONCLUSION: Specific changes of local and lymph node recurrence can be found in the course of the cardinal peripancreatic vessels. The superior mesenteric artery is the leading structure for recurrence.

Multimodality Imaging of Integrin α(v)β(3) Expression

Over the last decade, integrin α_vβ₃ has been studied with every single molecular imaging modality. Since no single modality is perfect and sufficient to obtain all the necessary information for a particular question, combination of certain molecular imaging modalities can offer synergistic advantages over any modality alone. This review will focus on multimodality imaging of integrin α_vβ₃ expression, where the contrast agent used can be detected by two or more imaging modalities, such as combinations of PET and optical, SPECT and fluorescence, PET and MRI, SPECT and MRI, and lastly, MRI and fluorescence. Most of these agents are based on certain type(s) of nanoparticles. Contrast agents that can be detected by more than two imaging modalities are expected to emerge in the future and a PET/MRI/fluorescence agent will likely find the most future biomedical/clinical applications. Big strides have been made over the last decade for imaging integrin α_vβ₃ expression and several PET/SPECT probes have been tested in human studies. For dualmodality and multimodality imaging applications, a number of proof-of-principle studies have been reported which opened up many new avenues for future research. The next decade will likely witness further growth and continued prosperity of molecular imaging studies focusing on integrin α_vβ₃, which can eventually impact patient management.

Pancreatic and hepatobiliary cancers

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

The role of PET scanning in pancreatic cancer

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

Role and limitations of 18F-FDG positron emission tomography (PET) in the management of patients with pancreatic lesions

The 18-fluorine-18-fluoro-2-deoxyglucose Positron Emission Tomography coupled with computed tomography is a non invasive exploration. Several studies have shown that PET-CT has superior efficacy over conventional imaging techniques in distinguishing a benign pancreatic tumor from a malignant one. It contributes to the diagnosis of cancer in patients with a doubtful mass, much more in case of chronic pancreatitis. PET-CT is also an important help for the diagnosis of cystic tumors of the pancreas; the results can affect the management strategy. It is interesting for the endocrine tumors, particularly since the emergence of new markers. The aim of this paper is to summarize the role and limitations of 18-F-FDG PET-CT in the management of patients with pancreatic lesions (adenocarcinoma, cystic tumors, endocrine tumors, etc…) concerning the malignancy diagnosis, the detection of metastases, the monitoring after non surgical treatments and to evaluate interpretation difficulties, particularly in case of diabetes or chronic pancreatitis.

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.

A prospective diagnostic accuracy study of 18F-fluorodeoxyglucose positron emission tomography/computed tomography, multidetector row computed tomography, and magnetic resonance imaging in primary diagnosis and staging of pancreatic cancer

OBJECTIVE

To prospectively compare the accuracy of combined positron emission tomography/computed tomography using F-fluorodeoxyglucose (FDG-PET/CT), multidetector row computed tomography (MDCT), and magnetic resonance imaging (MRI) in the evaluation of patients with suspected pancreatic malignancy.

SUMMARY BACKGROUND DATA

FDG-PET/CT imaging is increasingly used for staging of pancreatic cancer. Preliminary data suggest a significant influence of FDG-PET/CT on treatment planning, although its role is still evolving.

METHODS

Thirty-eight consecutive patients with suspicion of pancreatic malignancy were enrolled. Patients underwent a protocol including FDG-PET/CT, MDCT, and MRI combined with magnetic resonance cholangiopancreatography, all of which were blindly evaluated. The findings were confirmed macroscopically at operation and/or by histopathologic analysis (n = 29) or follow-up (n = 9). Results of TNM classification of different imaging methods were compared with clinical TNM classification.

RESULTS

Pancreatic adenocarcinoma was diagnosed in 17 patients, neuroendocrine tumor in 3, mass-forming pancreatitis in 4, cystic lesion in 6, and fibrosis in 2. Six patients had a finding of a normal pancreas. The diagnostic accuracy of FDG-PET/CT for pancreatic malignancy was 89%, compared with 76% and 79% for MDCT and MRI, respectively. In the differential diagnosis of suspected malignant biliary stricture at endoscopic retrograde cholangiopancreaticography (n = 21), FDG-PET/CT had a positive predictive value of 92%. In 17 patients with advanced pancreatic adenocarcinoma, FDG-PET/CT had a sensitivity of 30% for N- and 88% for M-staging. Both MDCT and MRI had sensitivities of 30% for N- and 38% for M-staging. Furthermore, the clinical management of 10 patients (26%) was altered after FDG-PET/CT.

CONCLUSION

FDG-PET/CT was more sensitive than conventional imaging in the diagnosis of both primary pancreatic adenocarcinoma and associated distant metastases. In contrast, the sensitivity of FDG-PET/CT was poor in detecting local lymph node metastasis, which would have been important for an assessment of resectability. We recommend the use of FDG-PET/CT in the evaluation of diagnostically challenging cases, especially in patients with biliary strictures without evidence of malignancy in conventional imaging.

Tumor relapse after pancreatic cancer resection is detected earlier by 18-FDG PET than by CT

INTRODUCTION

Pancreatic cancer recurrence is often difficult to detect by conventional imaging. Our aim was to evaluate the impact of fluorodeoxyglucose-positron emission tomography (FDG-PET) in the diagnosis of recurrent pancreatic cancer.

METHODS

One-hundred thirty-eight patients were followed after resection for pancreatic cancer. Sixty-six underwent only CT and were excluded. Seventy-two patients also had FDG-PET. Recurrent patients were divided in two groups: group-1, CT positive and group 2, CT non diagnostic, FDG-PET positive. Characteristics and survival curves of the two groups were compared. Significance was set at p < 0.05.

RESULTS

Overall, tumors recurred in 63 of 72 (87.5%) patients; two patients had a second cancer resected, thanks to FDG-PET. Tumor relapse was detected by CT in 35 patients and by FDG-PET in 61. Prognostic factors were similar in groups 1 and 2. Five out of 35 group 1 patients underwent surgery (two R0, two bypass, and one exploratory). Ten out of 28 group 2 patients underwent surgery (four R0, two R2, two bypass, and two exploratory). FDG-PET influenced treatment strategies in 32 of 72 patients (44.4%). Group 2 patients survived longer (P = 0.09), but the difference was not significant. Disease-free survival was similar in groups 1 and 2.

CONCLUSION

Tumor relapse is detected earlier by FDG-PET than by CT. FDG-PET can help select the best candidates for surgical exploration, although the real benefit is still to be defined. It influences treatment strategies in a significant percentage of patients. An earlier diagnosis did not influence survival due to the lack of effective therapies.

Metabolic restaging of hepatocellular carcinoma using whole-body F-FDG PET/CT

AIM

To evaluate the ability of (18)F-fluorodeoxyglucose positron emission and computed tomography ((18)F-FDG PET/CT) in restaging of hepatocellular carcinoma (HCC) after treatment.

METHODS

We reviewed a database of the diagnostic performance of (18)F-FDG PET/CT scan for patients with HCC following local or regional treatment. The database consisted of (18)F-FDG PET/CT information of 21 male and 4 female (age range, 27-81 years; mean age, 51.6 years) patients who had received surgical resection and/or interventional treatments and then underwent (18)F-FDG PET/CT scan. All patients had received enhanced CT scan of the liver two weeks before or after the (18)F-FDG PET/CT scan. Intrahepatic recurrence and/or extrahepatic metastases were confirmed by histological analysis or clinical and imaging follow-up. The accuracy of (18)F-FDG PET/CT study was determined by histopathological results or by clinical and imaging follow-up.

RESULTS

(18)F-FDG PET/CT was abnormal in 19 of the 25 (76.0%) patients. In detecting HCC recurrence, (18)F-FDG PET/CT scored 17 true positives, 5 true negatives, 2 false positives and 1 false negative. The sensitivity, specificity and accuracy of (18)F-FDG PET/CT in detecting HCC recurrence was 89.5%, 83.3% and 88%, respectively. (18)F-FDG PET/CT had an impact on management of these patients by settling the problem of an unexplained increase in alpha-fetoprotein after treatment (14 patients), by monitoring response to the treatment and guiding additional regional therapy (12 patients), by identifying extrahepatic metastases (10 patients), by identifying tumor growth or thrombosis in the portal vein (6 patients), or by guiding surgical resection of extrahepatic metastases (2 patients).

CONCLUSION

Our results suggest that whole body (18)F-FDG PET/CT may be useful in the early evaluation of residual, intrahepatic recurrent or extrahepatic metastatic lesions and able to provide valuable information for the management of HCC recurrence.

Molecular imaging and therapy of cancer with radiolabeled nanoparticles

This review summarizes the current state-of-the-art of radiolabeled nanoparticles for molecular imaging and internal radiotherapy applications targeting cancer. With the capacity to provide enormous flexibility, radiolabeled nanoparticles have the potential to profoundly impact disease diagnosis and patient management in the near future. Currently, the major challenges facing the research on radiolabeled nanoparticles are desirable (tumor) targeting efficacy, robust chemistry for both radionuclide encapsulation/incorporation and targeting ligand conjugation, favorable safety profile, as well as certain commercial and regulatory hurdles.

Significance of perivascular soft tissue around the common hepatic and proximal superior mesenteric arteries arising after pancreaticoduodenectomy: evaluation with serial MDCT studies

PURPOSE

To evaluate the interval change of perivascular soft tissue (PVST) around the common hepatic and proximal superior mesenteric arteries arising after pancreaticoduodenectomy (PD) and to compare the difference between post operative change (benign PVST) and recurrence (malignant PVST).

MATERIALS AND METHODS

Serial multidetector CT (MDCT) studies in 44 patients who underwent PD for periampullary carcinomas were retrospectively reviewed (Group A). The incidence and interval change of PVST were evaluated and compared to control group (Group B, 21 patients with PD for benign diseases).

RESULTS

PVST was seen in all the 44 patients in Group A, and it was noted in 12 of 21 (57.1%) patients in Group B. Thirteen of 44 (29.5%) patients showed interval enlargement of PVST (malignant PVST), and 12 of 13 developed within 2 years after PD. There was higher incidence of malignant PVST in patients with lymph node metastasis (p < 0.01) and those with pancreas head carcinoma (p < 0.05).

CONCLUSION

PVST is common after PD regardless of whether patients had malignant or benign diseases. PVST should be monitored for at least 2 years to distinguish recurrence from post operative change. Patients with lymph node metastasis and pancreas head carcinoma had a higher incidence of malignant PVST.

In vivo characterization of proliferation for discriminating cancer from pancreatic pseudotumors

We have determined the ability of PET with the thymidine analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) to detect pancreatic cancer and to differentiate malignant from benign pancreatic lesions.

METHODS

In this prospective study, (18)F-FLT PET was performed on 31 patients with undefined pancreatic lesions. Routine diagnostic procedures included endoscopic ultrasound, MRI, or multislice helical CT of the upper gastrointestinal tract in all patients. Uptake of (18)F-FLT was evaluated semiquantitatively by calculation of mean and maximal standardized uptake values (SUVs). Results were correlated to the reference methods, which were histopathology (23/31) or cytology/clinical follow-up (8/31).

RESULTS

All 10 benign pancreatic lesions were negative on (18)F-FLT PET and showed only background activity (specificity, 100%; 90% confidence interval, 74%-100%). On visual interpretation, 15 of 21 malignant tumors presented as focal (18)F-FLT uptake higher than the surrounding background (sensitivity, 71.4%; 90% confidence interval, 52%-89%). (18)F-FLT PET missed 4 well-differentiated and 2 T1 cancers. Mean (18)F-FLT uptake was 3.1 in all malignant tumors (median, 2.8; range, 1.3-8.5), 3.7 in tumors with visual tracer uptake (median, 3.2; range, 2.1-8.5), and significantly higher in malignant than in benign tumors (mean/median, 1.4; range, 1.2-1.7; P<0.001). For discriminating cancer from benign pancreatic lesions, receiver-operating-characteristic analysis indicated a sensitivity of 81% and specificity of 100% (area under the curve, 0.93) using a mean (18)F-FLT SUV cutoff of 1.8 (maximal (18)F-FLT SUV: area under the curve, 0.92; SUV cutoff, 2.1).

CONCLUSION

In this pilot study, focal uptake of the in vivo proliferation marker (18)F-FLT was detected exclusively in malignant tumors. (18)F-FLT PET may therefore be useful as a diagnostic adjunct for differentiating cancer from benign pancreatic lesions.

Clinical role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative follow up of gastric cancer: Initial results

AIM: To evaluate the clinical role of ¹⁸F-fluorodeo-xyglucose positron emission and computed tomography (¹⁸F-FDG PET/CT) in detection of gastric cancer recurrence after initial surgical resection.

METHODS: In the period from January 2007 to May 2008, 23 patients who had previous surgical resection of histopathologically diagnosed gastric cancer underwent a total of 25 ¹⁸F-FDG PET/CT scans as follow-up visits in our center. The standard of reference for tumor recurrence consisted of histopathologic confirmation or clinical follow-up information for at least 5 mo after PET/CT examinations.

RESULTS: PET/CT was positive in 14 patients (61%) and negative in 9 (39%). When correlated with final diagnosis, which was confirmed by histopathologic evidence of tumor recurrence in 8 of the 23 patients (35%) and by clinical follow-up in 15 (65%), PET/CT was true positive in 12 patients, false positive in 2, true negative in 8 and false negative in 2. Overall, the accuracy of PET/CT was 82.6%, the negative predictive value (NPV) was 77.7%, and the positive predictive value (PPV) was 85.7%. The 2 false positive PET/CT findings were actually chronic inflammatory tissue lesions. For the two patients with false negative PET/CT, the final diagnosis was recurrence of mucinous adenocarcinoma in the anastomosis in one patient and abdominal wall metastasis in the other. Importantly, PET/CT revealed true-positive findings in 11 (47.8%) patients who had negative or no definite findings by CT. PET/CT revealed extra-abdominal metastases in 7 patients and additional esophageal carcinoma in one patient. Clinical treatment decisions were changed in 7 (30.4%) patients after introducing PET/CT into their conventional post-operative follow-up program.

CONCLUSION: Whole body ¹⁸F-FDG PET/CT was highly effective in discriminating true recurrence in post-operative patients with gastric cancer and had important impacts on clinical decisions in a considerable portion of patients.

PET/MRI dual-modality tumor imaging using arginine-glycine-aspartic (RGD)-conjugated radiolabeled iron oxide nanoparticles

The purpose of this study was to develop a bifunctional iron oxide (IO) nanoparticle probe for PET and MRI scans of tumor integrin alphavbeta3 expression.

METHODS

Polyaspartic acid (PASP)-coated IO (PASP-IO) nanoparticles were synthesized using a coprecipitation method, and particle size and magnetic properties were measured. A phantom study was used to assess the efficacy of PASP-IO as a T2-weighted MRI contrast agent. PASP-IO nanoparticles with surface amino groups were coupled to cyclic arginine-glycine-aspartic (RGD) peptides for integrin alphavbeta3 targeting and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N',N'',N''',-tetraacetic acid (DOTA) chelators for PET after labeling with 64Cu. IO nanoparticle conjugates were further tested in vitro and in vivo to determine receptor targeting efficacy and feasibility for dual PET/MRI.

RESULTS

PASP-IO nanoparticles made by single-step reaction have a core size of 5 nm with a hydrodynamic diameter of 45 +/- 10 nm. The saturation magnetization of PASP-IO nanoparticles is about 117 emu/g of iron, and the measured r2 and r2* are 105.5 and 165.5 (s.mM)(-1), respectively. A displacement competitive binding assay indicates that DOTA-IO-RGD conjugates bound specifically to integrin alphavbeta3 in vitro. Both small-animal PET and T2-weighted MRI show integrin-specific delivery of conjugated RGD-PASP-IO nanoparticles and prominent reticuloendothelial system uptake.

CONCLUSION

We have successfully developed an IO-based nanoprobe for simultaneous dual PET and MRI of tumor integrin expression. The success of this bifunctional imaging approach may allow for earlier tumor detection with a high degree of accuracy and provide further insight into the molecular mechanisms of cancer.

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.

Detection of disease recurrence and monitoring of therapy

The detection of disease recurrence and treatment monitoring pose high demands on diagnostic modalities. Whereas serum marker levels in most cases allow an assessment of tumor load and a respective response to therapy, they do not confer information on the localization of disease. Although this diagnostic gap is filled by imaging modalities, most techniques based on morphology will come to a limit when fibrotic tissue alterations have to be differentiated from viable tumor tissue in case of suspected recurrence or when residual masses after chemotherapy have to be assessed. The metabolic information on tumor cells gained by fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging appears not only to be more sensitive and reliable in this respect, but also appears to allow assumptions on response to therapy, and ultimately on patient prognosis.

Surgery for recurrent pancreatic ductal adenocarcinoma

OBJECTIVE

This study evaluates the outcome of patients who underwent surgery for recurrent pancreatic cancer.

SUMMARY BACKGROUND DATA

Recurrence of pancreatic ductal adenocarcinoma occurs in up to 80% of pancreatic cancer patients within 2 years of a potential curative resection because, in most cases, occult (local and/or distant) micrometastases are present at the time of the initial resection.

METHODS

Thirty patients were operated for recurrent pancreatic cancer between October 2001 and April 2005. Median time between the initial resection and recurrence was 12.0 months. While 15 patients were resected, 15 patients either underwent palliative bypass or only exploration. Prospectively recorded data were analyzed retrospectively. Survival analysis was performed using Kaplan-Meier estimation and log-rank test.

RESULTS

The overall median survival of patients with recurrent disease was 29.0 months. After the first reresection/exploration for recurrent disease, the median survival was 11.4 months. There was a tendency of increased median survival in the group of patients undergoing resection (17.0 months) compared with the bypass/exploration group (9.4 months), although this difference was not significant (P = 0.084). In addition, patients with a prolonged interval (>9 months) from resection to recurrence were more likely to benefit from reresection compared with patients with recurrence within 9 months (median survival 17.0 vs. 7.4 months; P = 0.004). The in-hospital morbidity and mortality rate of resected patients was 20% and 6.7% compared with 13.3% and 0% of patients who underwent only exploration/palliative bypass.

CONCLUSION

Resection for recurrent pancreatic cancer can be carried out safely. Further studies are required to address the question whether a subgroup of patients might actually benefit from this procedure.

Positron-emission tomography and computed tomography of cystic pancreatic masses

AIM

To investigate the sensitivity and specificity of computed tomography (CT), positron-emission tomography (PET), and both methods in combination, for determining whether cystic pancreatic tumours are malignant.

MATERIALS AND METHODS

We retrospectively identified all patients with cystic pancreatic tumours who underwent separate PET and contrast-enhanced CT examinations within a 1-month interval. Tumours were classified as benign or malignant on CT (two radiologists, independently), PET [a reported standardized uptake value (SUV) of 2.5 was taken as the cut-off between benign and malignant], and with PET and CT images together (two radiologists, in consensus). Readers were blinded to pathological and other radiological findings. Mean patient age and lesion size were compared between benign and malignant groups using Student's t-test. For CT findings, odds ratios (OR) and confidence intervals (CI) were calculated using multivariate logistic regression models. For CT, PET, and the combined images, sensitivities and specificities were calculated, and compared between groups using Fisher's exact test.

RESULTS

Thirty patients were identified. The best CT predictor of malignancy was size; mean diameter was 2.3 cm (benign) and 4.1 cm (malignant) (p<0.01); OR was 2.80 (95% CI, 1.26-6.20). Sensitivities of CT, PET and combined PET/CT images were 67-71, 57, and 86%, respectively. PET/CT was more sensitive than PET (p<0.01) or CT (p<0.01) alone. Specificities of CT, PET, and combined PET/CT images were 87-90, 65, and 91%, respectively. PET/CT was more specific than PET (p<0.01) but not CT (p>0.05).

CONCLUSION

The sensitivity and specificity of combined PET and CT images is comparable with or superior to either CT or PET alone in determining malignancy in cystic pancreatic lesions.

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

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

Positron emission tomography: clinical applications in oncology. Part 2

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