Magnetic resonance imaging of cystic and endocrine pancreatic neoplasms

Endoscopic Ultrasound Imaging for Diagnosing and Treating Pancreatic Cysts

Cystic pancreatic lesions are increasingly diagnosed owing to the abundant use of cross-sectional imaging. Given their malignant potential, true pancreatic cysts should be considered for resection or periodic follow-up. Cystic lesions of the pancreas (CLPs) require further evaluation and management. Therefore, it is important to establish a solid diagnosis at the time of detection. Endoscopic ultrasound examination is the imaging modality of choice. Fine needle aspiration provides fluid for cytologic, biochemical, and molecular assays to classify lesions and predict biological behavior. This review provides an overview of the diagnosis and management of various types of commonly encountered true CLPs.

Clinical importance of Familial Pancreatic Cancer Registry in Japan: a report from kick-off meeting at International Symposium on Pancreas Cancer 2012

Pancreatic cancer is still a highly lethal disease with a 5-year survival rate of approximately 5 %. Early detection offers one of the best hopes for improving survival. Previous cohort studies and case-control studies showed that 4-10 % of pancreatic cancers have a hereditary basis, and individuals with a family history have an increased risk of developing pancreatic and extra-pancreatic malignancies. Since individuals with a family history of pancreatic cancer and those with a known genetic syndrome that predisposes to pancreatic cancer will be the first to benefit from early detection tests as they become available, familial pancreatic cancer (FPC) registries have been established in the US and Europe, but not yet in Japan. Such registries form the basis for epidemiological studies, clinical trials, and basic research on familial pancreatic cancer. There is a need for FPC registries in Japan as cancer risk varies among different populations and discoveries made in Western populations may not translate to the Japanese population. These registries in Japan will align with ongoing international efforts and add to a better understanding of the natural history, risk factors, screening strategies, and responsible genes, for improving survival of this dismal disease.

Staging accuracy of MR for pancreatic neuroendocrine tumor and imaging findings according to the tumor grade

PURPOSE

To investigate staging accuracy of MR for pancreatic neuroendocrine neoplasms (PNETs) and imaging findings according to the tumor grade.

MATERIALS AND METHODS

Our study consisted of 39 patients with PNET G1 (n = 24), PNET G2 (n = 12), and pancreatic neuroendocrine carcinoma (PNEC) (n = 3). All underwent preoperative MRI. Two radiologists retrospectively reviewed MR findings including tumor margin, SI on T2WI, enhancement patterns, degenerative change, duct dilation, and ADC value. They also assessed T-stage, N-stage, and tumor size. Statistical analyses were performed using Chi square tests, ROC analysis, and Fisher's exact test.

RESULTS

Specific findings for PNEC or PNET G2 were ill-defined borders (P = 0.001) and hypo-SI on venous- and delayed-phase (P = 0.016). ADC value showed significant difference between PNET G1 and G2 (P = 0.007). The Az of ADC value for differentiating PNET G1 from G2 was 0.743. Sensitivity and specificity were 70% and 86%. Accuracy for T-staging was 77% (n = 30) and 85% (n = 33), and for N-staging was 92% (n = 36) and 87% (n = 34) with moderate agreement. T-stage showed significant difference according to tumor grade (P < 0.001), although there was no significant difference in tumor size or N-stage.

CONCLUSION

Ill-defined borders and hypo-SI on venous- and delayed-phase imaging are common findings of higher grade PNET, and ADC value is helpful for differentiating PNET G1 from G2. MR is useful for preoperative evaluation of T-, N-stage. Tumor size of PNET and T-stage showed significant difference according to tumor grade.

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.

Variation in precursor lesions of pancreatic cancer among high-risk groups

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) surveillance programs are currently offered to high-risk individuals aiming to detect precursor lesions or PDAC at an early stage. We assessed differences in frequency and behavior of precursor lesions and PDAC between two high-risk groups.

EXPERIMENTAL DESIGN

Individuals with a p16-Leiden germline mutation (N = 116; median age 54 years) and individuals from familial pancreatic cancer (FPC) families (N = 125; median age 47 years) were offered annual surveillance by MRI and magnetic resonance cholangiopancreatography (MRCP) with or without endoscopic ultrasound (EUS) for a median surveillance period of 34 months (0-127 months) or 36 months (0-110 months), respectively. Detailed information was collected on pancreatic cystic lesions detected on MRCP and precursor lesions in surgical specimens of patients who underwent pancreatic surgery.

RESULTS

Cystic lesions were more common in the FPC cohort (42% vs. 16% in p16-Leiden cohort), whereas PDAC was more common in the p16-Leiden cohort (7% vs. 0.8% in FPC cohort). Intraductal papillary mucinous neoplasm (IPMN) was a common finding in surgical specimens of FPC-individuals, and was only found in two patients of the p16-Leiden cohort. In the p16-Leiden cohort, a substantial proportion of cystic lesions showed growth or malignant transformation during follow-up, whereas in FPC individuals most cystic lesions remain stable.

CONCLUSION

In p16-Leiden mutation carriers, cystic lesions have a higher malignant potential than in FPC-individuals. On the basis of these findings, a more intensive surveillance program may be considered in this high-risk group.

Simultaneous EUS-FNA Diagnosis and TNM Staging of a Pancreatic Neuroendocrine Tumor in a Patient with an Unrecognized MEN Type 1

We report the case of a woman who, during oncological followup for bronchial carcinoid (diagnosed in 2005), papillary thyroid carcinoma, and bilateral parathyroid adenoma (simultaneously diagnosed in 2007), performed a pancreatic endoscopic ultrasonography with fine needle agobiopsy (EUS-FNA) for a positron emission tomography (PET) suspicion of pancreatic and hepatic lesions; during the procedure, the pancreatic and liver lesions were confirmed, and a peripancreatic lymph node involvement was found, allowing a complete pTNM staging during the same procedure.

Screening for pancreatic cancer in a high-risk cohort: an eight-year experience

BACKGROUND

Pancreatic adenocarcinoma is the fourth leading cause of cancer death.

METHODS

A prospective cohort study was undertaken between 2003 and 2011 at a tertiary care centre in Toronto, Canada. Two hundred and sixty-two subjects were enrolled based on an elevated estimated lifetime risk for pancreatic cancer due to known genetic mutations and/or cancer family history. Subjects underwent annual magnetic resonance imaging, followed by additional investigations if abnormal findings were detected. Evidence of malignancy or suspicious macroscopic abnormalities prompted referral for surgical intervention.

RESULTS

Average length of follow-up was 4.2 years, during which 84/262 (32%) subjects demonstrated pancreatic abnormalities. Three participants developed pancreatic adenocarcinoma (one 1.5-cm tumor was resected but recurred, while the other two subjects developed metastatic cancer), and a fourth participant developed a pancreatic neuroendocrine tumor that was resected. Fifteen subjects had radiologic evidence of branch-duct intraductal papillary mucinous neoplasms, of which two underwent surgical resection. Sixty-five subjects had simple pancreatic cysts that have remained stable.

CONCLUSION

Magnetic resonance imaging can detect small pancreatic tumors and cystic lesions, but further improvement in sensitivity is needed. An understanding of the natural history of pre-invasive lesions in members of high-risk families is necessary for developing a more effective screening program.

Magnetic resonance imaging versus endoscopic ultrasonography for the detection of pancreatic tumours in multiple endocrine neoplasia type 1

OBJECTIVE

In multiple endocrine neoplasia type 1, the main risk factor for metastases is pancreatic tumour size. We and others recommend limiting surgery to non-functioning pancreatic tumors ≥20 mm or growing, based on their size measured with endoscopic ultrasonography. Because endoscopic ultrasonography is invasive, we compared endoscopic ultrasonography (EUS) to non-invasive magnetic resonance imaging (MRI) for the detection of pancreatic tumours ≥10 mm in multiple endocrine neoplasia type 1 patients.

METHODS

A prospective study was performed in nine participating centres; 90 patients with multiple endocrine neoplasia type 1 underwent EUS and MRI with gadolinium infusion. Gastroenterologists and radiologists were blinded to the results, magnetic resonance images were reviewed centrally.

RESULTS

EUS detected 86 tumours ≥10 mm, and 48 (53.3%) patients had at least one tumour ≥10 mm. MRI detected 67 tumours ≥10 mm, and 46 (51.1%) patients had at least one tumour ≥10 mm. EUS and MRI agreement was moderate for detection of tumours ≥10 mm (Kappa coefficient=0.49), and for selection of patients with tumours ≥10 mm (Kappa coefficient=0.55). EUS and MRI missed 11/24 and 4/24 lesions ≥20 mm, respectively. EUS failed to identify 9/57 (15.7%) patients with pancreatic tumours ≥10 mm, and MRI failed to identify 11/57 (19.3%) patients with pancreatic tumours ≥10 mm.

CONCLUSIONS

EUS and MRI are complementary and should be performed at initial evaluation in multiple endocrine neoplasia type 1 patients. Whether follow-up should be based on either technique or both, requires further evaluation.

Advances in biomarker research for pancreatic cancer

Pancreatic cancer (PC) is a leading cause of cancer related deaths in United States. The lack of early symptoms results in latestage detection and a high mortality rate. Currently, the only potentially curative approach for PC is surgical resection, which is often unsuccessful because the invasive and metastatic nature of the tumor masses makes their complete removal difficult. Consequently, patients suffer relapses from remaining cancer stem cells or drug resistance that eventually lead to death. To improve the survival rate, the early detection of PC is critical. Current biomarker research in PC indicates that a serum carbohydrate antigen, CA 19-9, is the only available biomarker with approximately 90% specificity to PC. However, the efficacy of CA 19-9 for assessing prognosis and monitoring patients with PC remains contentious. Thus, advances in technology and the detection of new biomarkers with high specificity to PC are needed to reduce the mortality rate of pancreatic cancer.

The predictive value of mean platelet volume in differential diagnosis of non-functional pancreatic neuroendocrine tumors from pancreatic adenocarcinomas

OBJECTIVE

The aim of the present study is to evaluate in a retrospective manner the diagnostic value of mean platelet volume (MPV) in pancreatic adenocarcinomas and pancreatic neuroendocrine tumors (PNETs).

PATIENTS AND METHODS

A total of 92 patients, who were admitted for pancreatic adenocarcinoma (n=76) and PNET (n=16) between March 2007 and December 2009, were analyzed retrospectively for demographics and clinical information.

RESULTS

Thirty-nine patients (51.3%) had a resectable, whereas 37 patients (48.7%) had an unresectable pancreatic adenocarcinoma. Nine patients (56.3%) had a non-functional PNET, 6 patients (37.5%) had an insulinoma, and the remaining one patient had a gastrinoma. The mean age was 59.3±10.5 for pancreatic adenocarcinomas and 45.1±10.6 for PNETs. The mean age at diagnosis was significantly higher in patients with pancreatic adenocarcinomas than the patients with PNET (p<0.001). Preoperative mean hemoglobin levels were significantly lower in patients with pancreatic adenocarcinoma than those with PNET (12.4±1.8g/dl vs 13.7±2.2g/dl), (p<0.013). The preoperative median MPV levels were significantly lower in patients with PNET 7.8fL (7.2-9.4) than in patients with pancreatic adenocarcinomas 8.6fL (6.6-13.5), (p<0.014). In subgroup analysis, a significant difference in MPV levels was mainly caused by the difference between pancreatic adenocarcinomas and non-functional PNETs (p=0.017). The cut-off value of MPV level for detection of PNETs was calculated as≤7.8fL using ROC analysis [Sensitivity: 66.7%, specificity: 75.9%, AUC: 0.734 (0.587-0.880) p=0.022]. In logistic regression analysis, independent predictive factors for determining PNETs in the differential diagnosis of pancreatic adenocarcinomas were calculated as age (OR=0.068, 95% CI: 0.012-0.398), Ca 19-9 (OR=0.039, 95% CI: 0.006-0.263), MPV (OR=0.595, 95% CI: 0.243-1.458), and hemoglobin (OR=1.317, 95% CI: 0.831-2.086).

CONCLUSION

Age, Ca 19-9, MPV, and hemoglobin levels have diagnostic value for distinguishing PNETs from pancreatic adenocarcinomas.

Diffusion-weighted MR imaging of solid and cystic lesions of the pancreas

Diffusion-weighted magnetic resonance (MR) imaging is increasingly used in the detection and characterization of pancreatic lesions. Diffusion-weighted imaging may provide additional information to radiologists evaluating patients who have cystic or solid neoplasms of the pancreas. Because of greater freedom of motion of water molecules in fluid-rich environments, simple cysts in the pancreas have higher signal intensity on diffusion-weighted images with a b value of 0 sec/mm2 and lower signal intensity on high-b-value images. High apparent diffusion coefficient (ADC) values can be obtained on ADC maps because of the T2 “shine-through” effect. In contrast, solid neoplasms of the pancreas show increased signal intensity relative to the pancreas on diffusion-weighted images with a b value of 0 sec/mm2 and relatively high signal intensity on high-b-value images. Diffusion-weighted imaging can help detect solid pancreatic neoplasms with extremely dense cellularity or extracellular fibrosis by demonstrating significantly low ADC values, and these neoplasms may be better detected on diffusion-weighted MR images because of better contrast, although the resolution is generally worse. However, diffusion-weighted imaging may not be capable of helping definitively characterize solid lesions as inflammatory or neoplastic because of an overlap in ADC values between the two types. For example, it is difficult to distinguish poorly differentiated pancreatic adenocarcinoma from mass-forming pancreatitis at diffusion-weighted imaging because of similarly low ADC values attributed to dense fibrosis.

Diagnosis and treatment of cystic pancreatic tumors

Cystic pancreatic tumors (CPTs) have more frequently been identified in the last decade because of increased use of cross-sectional abdominal imaging. Although serous CPTs follow an indolent course and do not necessarily require surgical resection or long-term follow-up, mucinous CPTs (mucinous cystic neoplasms and intraductal papillary mucinous neoplasms) have a greater risk for malignancy. Although most CPTs are initially detected with imaging modalities such as computed tomography or magnetic resonance imaging, these tests alone rarely permit an accurate clinical diagnosis. Endoscopic ultrasound and endoscopic ultrasound-guided, fine-needle aspiration allow real-time examination and biopsy analysis of CPTs, which increases diagnostic accuracy because cytopathology features and tumor markers in cyst fluid can be analyzed. Management of patients with mucinous CPTs by surgery or imaging surveillance is controversial, partially because of limited information about disease progression and the complexities of surgical resection. We review approaches to diagnosis and management of common CPTs.