CT in the differentiation of pancreatic neoplasms--progress report

CT-based measurement of visceral adipose tissue volume as a reliable tool for assessing metabolic risk factors in prediabetes across subtypes

Visceral adipose tissue (VAT) is a well-established risk factor for the development of diabetes in individuals with prediabetes. We aimed to evaluate various adiposity and metabolic indices, including visceral adipose tissue (VAT) volume measured by CT, in individuals with prediabetes, based on their different subtypes. This retrospective study included 78 prediabetes individuals aged ≥ 20 years whose VAT volumes were evaluated by CT. Individuals were classified into prediabetes subtypes: impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and combined IFG and IGT (C-IFG/IGT). We conducted a comparison of the patients' adiposity indices and their associations with one other, as well as with insulin resistance, based on the different prediabetes subtypes. Individuals with C-IFG/IGT had higher levels of visceral obesity than those with IFG or IGT. VAT volume was more strongly associated with insulin resistance than other adiposity indices, regardless of prediabetes subtypes. Additionally, VAT volume and liver attenuation index showed a significant correlation with the other indices studied across the prediabetes subtypes. CT-based measurement of VAT volume may be a valuable tool for evaluating metabolic risk factors among individuals with prediabetes.

Association between visceral adipose tissue volume, measured using computed tomography, and cardio-metabolic risk factors

We evaluated the associations between metabolic parameters with visceral adipose tissue (VAT) volume in women with prediabetes or type 2 diabetes (T2DM), and we compared the VAT volume with the VAT area. We enrolled women aged > 20 years with prediabetes or T2DM, who underwent oral glucose tolerance test and whose VAT was evaluated using computed tomography (CT) at our institution between 2017 and 2019. All participants underwent unenhanced spiral CT with a 3-mm slice thickness from the level of the diaphragm to the level of the mid-thigh. The two VAT areas were defined as the free drawn area on the levels of the umbilicus and L2 vertebra. The VAT areas were also manually drawn from the level of the diaphragm to the level of the pelvic floor and were used to calculate the VAT volumes by summing all areas with a slice thickness of 3 mm after setting the attenuation values from -45 to -195 Hounsfield Unit. All metabolic characteristics, except blood pressure, were significantly correlated with the VAT volume. The VAT areas measured at the level of the L2 vertebra and umbilicus were correlated with serum triglyceride, high-density lipoprotein cholesterol, and Framingham steatosis index alone. Multivariable regression analyses revealed that the VAT volume was significantly associated with several metabolic parameters. In conclusion, in women with prediabetes and T2DM, the VAT volume acquired from CT-based calculation has more significant correlations with metabolic risk factors compared with the VAT area.

Anaplastic pancreatic cancer diagnosed with endoscopic ultrasound guided fine needle aspiration showing hypervascular tumor: A case report

RATIONALE

Pancreatic ductal carcinoma is a hypovascular tumor, and characteristic findings are observed on imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), in most cases.

PATIENT CONCERNS

Here we report a case of anaplastic carcinoma of the pancreas (ACP) with characteristics of hypervascular tumor diagnosed by endoscopic ultrasound guided fine needle aspiration (EUS-FNA). A 70-year-old woman was admitted to hospital because of exacerbation of diabetes. Contrast-enhanced CT revealed a hypervascular tumor at the head of the pancreas.

DIAGNOSIS

EUS-FNA was performed. Osteoclast-like giant cells and tumor cells with polymorphic nuclei were found on pathological examination and she was diagnosed with ACP.

INTERVENTIONS

Although it was a surgical indication at the time of diagnosis, the tumor rapidly worsened. Oral administration of TS-1 (tegafur/gimeracil/oteracil) was initiated. Chemotherapy was discontinued after the end of 2 courses because the tumor had increased prominently on CT.

OUTCOMES

She died approximately a year since the onset of the illness.

LESSONS

ACP occasionally exhibits the characteristics of a hypervascular tumor and may require differentiation from other pancreatic tumors, such as neuroendocrine tumor. Therefore, pathological diagnosis by EUS-FNA at an early stage is important to determine treatment strategies.

Staging pancreatic carcinoma by computed tomography

Pancreatic carcinoma is becoming more common in our environment; the mortality rate for this tumor has barely changed over the last 20 years. Early diagnosis and accurate staging are crucial to ensure an appropriate therapeutic approach, which should aim to improve survival in patients in whom complete resection is possible and to minimize surgical morbidity and mortality in those with a high risk of residual disease after the intervention. Various imaging techniques are used for tumor staging: multidetector computed tomography (CT), magnetic resonance imaging, positron emission tomography (PET)-CT, endoscopic ultrasound, and diagnostic laparoscopy. Currently, multidetector CT is the technique of choice for the study of pancreatic tumors; thus, this article aims to review the state of the art in staging adenocarcinoma of the pancreas, focusing mainly on the applications and limitations of this technique.

Dynamic computed tomography is useful for prediction of pathological grade in pancreatic neuroendocrine neoplasm

BACKGROUND AND AIM

Pathological grading is important in defining the therapeutic strategy in pancreatic neuroendocrine neoplasm (PNEN) but is difficult for unresectable cases. Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) is useful in the diagnosis of PNEN, but its usefulness for pathological grading is not well established. No studies have examined the diagnostic ability of dynamic computed tomography (CT) for pathological grading of PNEN. We investigated the usefulness of EUS-FNA and dynamic CT in the diagnosis and pathological grading of PNEN.

METHODS

In this retrospective study, 39 PNEN patients finally diagnosed via EUS-FNA and/or surgical resection underwent dynamic CT. Pathological samples were diagnosed based on WHO2010; staging was based on the European Neuroendocrine Tumor Society classification. The proportion of the quantification value in the tumor to the pancreatic parenchyma in arterial phase was defined as the CT ratio. Immunohistochemical staining with CD31 was performed to evaluate microvessel density (MVD). We evaluated the relationship between pathological grade, CT ratio, and MVD.

RESULTS

By using EUS-FNA, 35 of 39 (90%) cases were diagnosed as PNEN. As for pathological grade, 15 of 35 (43%) cases could be identified correctly. CT ratio could predict pathological Grade 3 disease. The sensitivity, specificity, and diagnostic accuracy were 100%, 94%, and 95%. MVD was significantly correlated with CT ratio (r = 0.83, P < 0.0001) and pathological grade (P = 0.0074).

CONCLUSIONS

Computed tomography ratio has a relationship with pathological grade in PNEN, which would help decide therapeutic strategy in unresectable cases and cases in which pathological grading is difficult.

Insulinoma case series: Experience of a tertiary care center

BACKGROUND

Insulinomas are usually solitary; benign and encapsulated small lesions and majority of them measure <2 cm in diameter. They pose a challenge for pre-operative localization. Definitive treatment is surgical excision of the tumor. Intra-operative ultrasonography (IOUS), transhepatic portal venous sampling (THPVS) and positron emission tomography (PET) scan can be done for tumors not localized by conventional imaging modalities.

MATERIALS AND METHODS

A retrospective study of patients diagnosed with insulinoma during the period 2004-2012 (8 years) was done. Biochemical diagnostic criteria used were plasma concentrations of glucose <55 mg/dl with corresponding insulin level >3.0 μU/ml (18 pmol/L) and C-peptide of >0.6 ng/ml (0.2 nmol/L). The localization of the tumor was done by various modalities namely computed tomography (CT), magnetic resonance imaging (MRI), IOUS, PET and portal venous sampling. The initial localizing technique in most of these patients were CT or MRI imaging, or both and those who were not localized by the above modalities were subjected to PET CT or THPVS or intra-operative ultrasound depending on the initial imaging results and patient's consent. All the modalities were not used in the same patient, but the modalities were decided as per the imaging results, patient's consent and affordability for the procedure.

RESULTS

Ninteen cases of insulinoma aged between 10 and 66 years, with a median age of 47 years were included in the analysis. There were 10 males and nine females. Eighty-three percent of patients presented with pre-prandial hypoglycemia (n = 15). Different modalities were employed for pre-operative localization of these patients out of which 5 (26.31%) cases were localized with CT, 5 (26.31) cases with MRI, 5 (26.31%) with THPVS, 1 (5.26%) case with PET CT, 3 (15.78%) of them could not be localized out of which 2 (10.52%) were localized by IOUS and 1 (5.26%) case the lesion could not be localized. Among 19 cases, 12 underwent surgery out of which one patient underwent distal pancreatectomy as tumor was not localized; eight underwent laparoscopic enucleation; three of them required intra-operative exploration and seven of them were not operated, as they did not give consent for surgery. In all the cases, the size of the insulinoma ranged between 1 and 2 cm.

CONCLUSION

We report our experience with 19 cases of insulinoma and analyze the role of pre- and intra-operative imaging modalities in the surgical management of insulinomas. Most of our cases were symptomatic, and the most common presentation was with pre-prandial hypoglycemia. THPVS, PET scan and intra-operative ultrasound added to diagnostic sensitivity in some cases not localized by CT or MRI.

Contrast-enhanced ultrasonographic findings in three dogs with pancreatic insulinoma

Abdominal ultrasonography is one of the most common diagnostic imaging modalities used for dogs with suspected insulinoma; however, pancreatic masses are clearly identified in fewer than half of affected dogs and benign pancreatic nodules can be difficult to differentiate from malignant ones. The purpose of this prospective study was to describe contrast-enhanced ultrasonography (CEUS) characteristics of confirmed pancreatic insulinoma in a group of dogs. Inclusion criteria were as follows: (1) repeated hypoglycemia (blood glucose levels <60 mg/dl, twice or more); (2) elevated blood insulin levels with hypoglycemia; (3) pancreatic nodules detected with conventional ultrasonography; and (4) histological confirmation of pancreatic islet cell carcinoma. Immediately following conventional ultrasonography of the entire abdomen, CEUS of the pancreatic nodule and adjacent parenchyma was performed using contrast-specific technology pulse inversion imaging and perflubutane microbubble contrast agent. Three dogs met inclusion criteria. Pancreatic nodules in all the three dogs became more clearly demarcated after injection of the contrast agent. Each nodule showed different enhancement patterns: markedly hyperechoic for 5 s, slightly hyperechoic for 1 s, and clearly hypoechoic for over 30 s. These results were not in complete agreement with previously reported CEUS findings in human patients with insulinoma. All nodules were surgically resected and histopathologically confirmed as malignant insulinomas. Findings from the current study indicated that contrast-enhanced ultrasound may help to increase conspicuity of pancreatic insulinomas in dogs and that enhancement characteristics may be more variable in dogs than in humans.

Pancreatic involvement by plasma cell neoplasms

INTRODUCTION

Pancreatic involvement by plasma cell neoplasms is an extremely rare event, with only 50 cases described in the literature. They can present as a primary solitary extramedullary plasmacytoma or plasmacytoma secondary to a plasma cell myeloma. Clinical manifestations are due to the presence of a pancreatic mass usually in the pancreas head, which causes extra-biliary obstruction and abdominal pain.

METHODS

Abdominal imaging including CT scan or endoscopic ultrasound with fine-needle aspiration tissue sampling is essential for the initial diagnostic procedure. However, immunohistochemical analysis of the biopsy specimen or flow cytometry of the aspirated material is crucial to prove the monoclonality and the final diagnosis of a plasma cell neoplasm.

DISCUSSION

Management of these situations include radiotherapy, chemotherapy, surgery or combined therapy. Novel medications including the immunomodulatory drugs or the proteasome inhibitors followed by consolidation with intensive chemotherapy and haematopoietic stem cell transplantation are nowadays used as upfront treatment in the cases associated to a plasma cell myeloma.

CONCLUSION

Despite the rarity, plasma cell neoplasms should be considered in the differential diagnosis of obstructive jaundice and pancreatic neoplasms since they are potentially treatable situations.

Vascular invasion in pancreatic cancer: Imaging modalities, preoperative diagnosis and surgical management

Pancreatic cancer is associated with a poor prognosis, and surgical resection remains the only chance for curative therapy. In the absence of metastatic disease, which would preclude resection, assessment of vascular invasion is an important parameter for determining resectability of pancreatic cancer. A frequent error is to misdiagnose an involved major vessel. Obviously, surgical exploration with pathological examination remains the “gold standard” in terms of evaluation of resectability, especially from the point of view of vascular involvement. However, current imaging modalities have improved and allow detection of vascular invasion with more accuracy. A venous resection in pancreatic cancer is a feasible technique and relatively reliable. Nevertheless, a survival benefit is not achieved by curative resection in patients with pancreatic cancer and vascular invasion. Although the discovery of an arterial invasion during the operation might require an aggressive management, discovery before the operation should be considered as a contraindication. Detection of vascular invasion remains one of the most important challenges in pancreatic surgery. The aim of this article is to provide a complete review of the different imaging modalities in the detection of vascular invasion in pancreatic cancer.

An unusual presentation of pancreatic pseudocyst mimicking cystic neoplasm of the pancreas: a case report

In spite of their rarity, cystic neoplasms of the pancreas are characterized by existing or potential malignancy that cannot be ignored during decisive process with regard to the choice of treatment. Diagnostic difficulties in the differentiation of pancreatic pseudocyst and cystic pancreatic neoplasm can lead to misdiagnosis and inappropriate treatment, since clinical symptoms, preoperative imaging tests and even endoscopic retrograde cholangiopancreatography are often not sufficient to establish the correct diagnosis. We present a case of pancreatic cyst with no typical features of pseudocyst in the medical interview, treated by Child's subtotal pancreatectomy by reason of the high risk of neoplasia suggested by radiological and endoscopic examinations.

Limitations in improving detection of pancreatic adenocarcinoma

OBJECTIVE

To review the current trends in pancreatic cancer research and propose alternatives for an earlier diagnosis.

METHOD

A search was conducted using the PubMed and Scielo electronic databases to find statistics related to the incidence of pancreatic cancer.

RESULTS

Pancreatic cancer is the fourth most common cause of cancer mortality in the USA; in Colombia the incidence of this neoplasia is 4.5 per 100,000 individuals; and in Peru, amongst digestive diseases, it is the fifth most common cause. In Brazil and Chile this cancer has increased in incidence, while in Mexico, it has decreased in terms of the relative percentage of gastrointestinal cancers from 1976 to 2003. Chronic pancreatitis, cigarette smoking, diabetes, obesity and dietary mutagen exposure are the most consistent risk factors implicated in the development of pancreatic cancer; however, the genetic and molecular changes underlying the epidemiological association between these factors and pancreatic cancer remain largely unknown, and only 5-10% are hereditary in nature.

CONCLUSION

The prognosis for pancreatic cancer has not changed substantially for at least the last 20 years. The most useful tumor marker for pancreatic adenocarcinoma is still the carbohydrate antigen 19-9 (CA19-9). Currently, a multimodal-screening approach of endoscopic ultrasound, computed tomography and endoscopic retrograde cholangiopancreatography are the most effective methods to detect pancreatic cancer in high-risk patients. Future options for early detection of this malignancy are focused on new molecular markers, telomerase enzyme, receptor-targeted imaging using multifunctional nanoparticles, detection of glycan changes and epigenetics.

[Pancreatic incidentalomas. Correct assessment and therapy]

Due to recent advances in CT/MRI technology, incidentalomas of the pancreas are detected with increasing frequency. Pancreatic incidentalomas should be differentiated into solid and cystic tumors. In both subgroups definitive classification of the tumor is often not possible. Operative therapy is recommended in premalignant or malignant pathologies. Thus solid incidentalomas should be resected independently of their size, if the patient is without serious comorbidities. In case of cystic incidentalomas, benign cystic lesions should be excluded as far as possible. Otherwise they should be resected if their size is >or=2 cm. In case of IPMN with specific risk factors, resection is recommended when the tumor size exceeds 1 cm.

Dynamic computed tomography of the pancreas in normal dogs and in a dog with pancreatic insulinoma

To establish optimal imaging conditions for enhanced computed tomography (CT) for canine pancreatic tumors, 10 healthy beagles were subjected to dynamic CT. This technique was then applied to a dog with suspected insulinoma. The changes in mean peak enhancement and the delay time of the aorta and pancreas were determined. In normal beagles, maximal arterial and pancreatic CT enhancement was observed at 15 +/- 2 s (795 +/- 52 Housfield unit [HU]) and 28 +/- 9 s (118 +/- 16HU) after contrast medium injection, respectively. Multiphase enhanced CT was performed in a pug with suspected insulinoma using the CT protocol defined for the normal beagles with some parameters modified; the images were acquired at the arterial (14 s after contrast medium injection), pancreatic (after 28 s), and equilibrium (after 90 s) phases; scanning was followed by exploratory laparotomy. CT images were characterized by an enhanced mass in the left pancreatic lobe at the arterial phase, during which the difference between the CT values of the mass and normal pancreas was the highest. Histopathologic diagnosis of the pancreatic mass was insulinoma. Thus, it appears that enhanced CT imaging can be used to delineate the pancreas from a pancreatic mass, and it may be helpful in deciding the need for surgery.

Contrast-enhanced sonography in pancreatic diseases

Contrast-enhanced sonography is a widely available imaging modality for the diagnosis of pancreatic diseases. With this procedure, pancreatic tumours can be differentiated better. Furthermore, contrast-enhanced sonography produces good results in the staging of acute pancreatitis severity, especially in the detection of pancreatic necrosis. In this review article the value of contrast-enhanced sonography in the diagnosis of pancreatic diseases will be described and discussed.

Imaging of neuroendocrine tumors

Neuroendocrine tumors may arise from a wide range of organs and may occur in various locations in the body. They include carcinoid tumors, paragangliomas (pheochromocytomas), medullary thyroid carcinomas, and islet cell tumors of the pancreas. In this article the authors focus on the more common tumors with origins primarily in the abdomen, namely carcinoid, paraganglioma, and pancreatic islet cell tumors. Imaging assists in delineating the sites and extent of disease, in preoperative planning for resection of the primary tumor and metastatic disease, and in follow-up. Discussion is restricted to the main imaging modalities used in these tumors: cross-sectional imaging, namely CT and MRI, and nuclear medicine studies.

Diagnosing pancreatic cancer: the role of percutaneous biopsy and CT

AIMS

To determine the sensitivity and complications of percutaneous biopsy of pancreatic masses, and whether typical computed tomography (CT) features of adenocarcinoma can reliably predict this diagnosis.

MATERIALS AND METHODS

A 5 year retrospective analysis of percutaneous core biopsies of pancreatic masses and their CT features was undertaken. Data were retrieved from surgical/pathology databases; medical records and CT reports and images.

RESULTS

Three hundred and three patients underwent 372 biopsies; 56 of 87 patients had repeat biopsies. Malignancy was diagnosed in 276 patients, with ductal adenocarcinoma in 259 (85%). Final sensitivity of percutaneous biopsy for diagnosing pancreatic neoplasms was 90%; for repeat biopsy it was 87%. Complications occurred in 17 (4.6%) patients, in three of whom the complications were major (1%): one abscess, one duodenal perforation, one large retroperitoneal bleed. CT features typical of ductal adenocarcinoma were: hypovascular pancreatic mass with bile and/or pancreatic duct dilatation. Atypical CT features were: isodense or hypervascular mass, calcification, non-dilated ducts, cystic change, and extensive lymphadenopathy. Defining typical CT features of adenocarcinoma as true-positives, CT had a sensitivity of 68%, specificity of 95%, positive predictive value (PPV) of 98%, and negative predictive value of 41% for diagnosing pancreatic adenocarcinoma.

CONCLUSION

Final sensitivity of percutaneous biopsy for establishing the diagnosis was 90%. CT features typical of pancreatic adenocarcinoma had high specificity and PPV. On some occasions, especially in frail patients with co-morbidity, it might be reasonable to assume a diagnosis of pancreatic cancer if CT features are typical, and biopsy only if CT shows atypical features.

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.

Approach to cystic pancreatic lesions

Cystic neoplasms of the pancreas represent the best example of a malignant precursor in the pancreas. There are many parallels between pancreatic cystic neoplasms and the colon polyp-cancer sequence. In the past, cystic neoplasms of the pancreas were thought to be relatively rare, composing less than 10% of cancers of the pancreas. With the greater use of cross-sectional imaging, an increasing number of these neoplasms are being seen.