Ultrasonography of the pancreas. 4. Contrast-enhanced imaging

Pancreatic solitary and synchronous metastasis from breast cancer: a case report and systematic review of controversies in diagnosis and treatment

Background

Metastases from breast cancer cause the frequent involvement of lung, bone, liver, and brain, while the occurrence of metastases to the gastrointestinal tract is rare, and more frequently discovered after a primary diagnosis of breast cancer. Solitary pancreatic metastases from breast cancer, without widespread disease, are actually unusual, and only 19 cases have been previously described; truly exceptional is a solitary pancreatic metastasis becoming evident together with the primary breast cancer.

Case presentation

A 68-year-old woman reported general fatigue, lethargy, and jaundice. Abdominal ultrasound (US) and magnetic resonance imaging (MRI) showed an ampulloma of Vater’s papilla; moreover, a neoplastic nodule in the left breast was diagnosed. She underwent surgery for both breast cancer and ampulloma of Vater’s papilla. Pathological examination of pancreatic specimen, however, did not confirm primary carcinoma of the duodenal papilla, but showed a metastatic involvement of pancreas from lobular breast cancer. Immunohistochemistry has been essential to confirm the origin of the malignancy: hormone receptors and mammaglobin were expressed in both the primary breast tumor and the pancreatic metastasis.

Conclusions

This is one of the few reported cases in literature of an isolated and synchronous pancreatic metastasis from breast cancer, where the definitive diagnosis was obtained only after surgery. We discuss the controversies in this diagnosis and the choice of correct treatment. The surgical resection of solitary metastases can be performed in the absence of disseminated disease.

Three-dimensional contrast-enhanced ultrasonography of intraductal papillary mucinous neoplasms of the pancreas: a comparison with magnetic resonance imaging

OBJECTIVES

The objective of this study was to prospectively compare the diagnostic accuracy of 3-dimensional contrast-enhanced ultrasonography (3D-CEUS) with that of magnetic resonance imaging (MRI) in the study of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas.

METHODS

Thirty consecutive patients with IPMN were studied.

RESULTS

Three patients (10.0%) did not undergo diagnostic 3D-CEUS because of technical problems. Three dimensional CEUS identified 12 (44.4%) main-duct IPMNs versus no cases by MRI (P < 0.001). Intraductal papillary mucinous neoplasm localization showed poor agreement between 3D-CEUS and MRI (κ = 0.058), whereas good agreement was found in detecting the pancreatic calcifications (κ = 1.000). Significant differences between 3D-CEUS and MRI were found regarding the number of lesions detected (1.4 ± 0.8 vs 3.8 ± 3.6; P < 0.001), the detection of mucinous plugs (3.7% vs 50.0%; P < 0.001), chronic pancreatitis (7.4% vs 26.7%; P = 0.031), pancreatic atrophy (0% vs 50.0%; P < 0.001), thick septa (22.2% vs 53.3%; P = 0.004), and mural nodules (25.9% vs 3.3%; P = 0.016). Three dimensional CEUS showed similar results as compared with MRI in evaluating IPMNs smaller than 1 cm of diameter or greater than 2 cm.

CONCLUSIONS

Even if MRI remains the criterion standard technique for the diagnosis of IPMNs, 3D-CEUS can be safely used to follow patients with IPMNs of less than 1 cm.

Qualitative and quantitative contrast enhanced ultrasonography of the pancreas using bolus injection and continuous infusion methods in normal dogs

Quantitative contrast enhanced ultrasound is a major breakthrough for ultrasound imaging in recent years. However, contrast enhancement of the pancreas is brief with bolus injection. To assess if continuous infusion of Sonazoid^® can prolong the duration of pancreatic enhancement over bolus injections, eight adult dogs received bolus injection and continuous infusion of Sonazoid^® on separate days. Contrast enhanced ultrasound of the pancreatic parenchyma and proximal descending duodenum was performed, and time intensity curves reflecting tissue perfusions were generated. Perfusion parameters- time to initial upslope, peak time, time to wash-out and peak intensity were calculated and evaluated. Fast wash-in to intense peak, followed by rapid wash-out was observed for time intensity curves of bolus injection. With continuous infusion, contrast wash-in to peak intensity was gradual, followed by long plateau and slow wash-out. Median contrast enhancement durations of the pancreas and duodenum were significantly prolonged by continuous infusion from 11 sec (range, 10 to 23 sec) and 16 sec (range, 3 to 43 sec) at bolus injection to 205 sec (range, 170 to 264 sec, P<0.01) and 193 sec (range, 169 to 216 sec, P<0.05), respectively. Median peak intensity of the pancreas was 100.9 MPV (range, 80.2 to 124.3 MPV) at bolus injection and 77.6 MPV (range, 58.2 to 99.5 MPV, P<0.05) at continuous infusion. Prolonged continuous imaging is afforded by continuous infusion of contrast agent. Peak intensity of the pancreas was slightly diminished in continuous infusion, but offered adequate imaging subjectively.

Contrast-enhanced ultrasound in the differential diagnosis of exocrine versus neuroendocrine pancreatic tumors

OBJECTIVES

Contrast-enhanced ultrasound (CEUS) has been developed to better characterize the microvasculature of solid masses in several organs, including the pancreas. In this study, we assessed CEUS accuracy in differentiating exocrine from endocrine pancreatic tumors.

METHODS

A total of 127 patients with single, undetermined pancreatic masses were prospectively examined with transabdominal ultrasound and CEUS, before surgical resection or percutaneous biopsy.

RESULTS

Exocrine and endocrine pancreatic tumors showed different intralesional vascularization patterns: 98.9% (90/91) of exocrine tumors were hypoenhancing, whereas 95.8 % (23/24) of endocrine tumors had a hypervascular supply. A hypoenhancing pattern, indicative of ductal adenocarcinoma, had a significant (P < 0.001) diagnostic accuracy of 91.3% with a sensitivity of 96.8%, a specificity of 85.3%, a positive predictive value and a negative predictive value of 94.7% and 90.6%, respectively. The hyperenhancing pattern, indicative of endocrine tumors, had a significant (P = 0.031) diagnostic accuracy of 73.8% with a sensitivity of 83.3%, a specificity of 60.0%, a positive predictive value and negative predictive value of 83.3% and 60.0%, respectively.

CONCLUSIONS

Contrast-enhanced ultrasound has a valuable diagnostic accuracy in differentiating exocrine from endocrine pancreatic tumors, which is a fundamental step to address appropriate histological evaluation, therapeutic approach, and follow-up.

Application of contrast-enhanced ultrasound in the diagnosis of solid pancreatic lesions--a comparison of conventional ultrasound and contrast-enhanced CT

OBJECTIVE

To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) by comparison with conventional ultrasound (US) and contrast-enhanced CT (CECT) in solid pancreatic lesions.

METHOD

Ninety patients with solid pancreatic focal lesions were enrolled, including 36 cases of pancreatic carcinoma, 28 cases of pancreatitis, 6 cases of pancreatic neuroendocrine tumor, 12 cases of solid pseudopapillary tumor of the pancreas, 6 cases of pancreatic metastases, 1 case of cavernous hemolymphangioma and 1 case of lymphoma. US and CEUS were applied respectively for the diagnosis of a total of 90 cases of solid pancreatic lesions. The diagnostic results were scored on a 5-point scale. Results of CEUS were compared with CECT.

RESULTS

(1) 3-score cases (undetermined) diagnosed by CEUS were obviously fewer than that of US, while the number of 1-score (definitely benign) and 5-score (definitely malignant) cases diagnosed by CEUS was significantly more than that of US. There was a significant difference in the distribution of final scores using the two methods (p<0.001). The overall diagnostic accuracies of the 90 cases for CEUS and US were 83.33% and 44.44%, respectively, which indicated an obvious advantage for CEUS (p<0.001). (2) The diagnostic consistency among three ultrasound doctors: the kappa values calculated for US were 0.537, 0.444 and 0.525, compared with 0.748, 0.645 and 0.795 for CEUS. The interobserver agreement for CEUS was higher than that for US. (3) The sensitivity, specificity and accuracy of the diagnosis of pancreatic carcinoma with CEUS and CECT were 91.7% and 97.2%, 87.0% and 88.9%, and 88.9% and 92.2%, respectively, while for the diagnosis of pancreatitis, the corresponding indices were 82.1% and 67.9%, 91.9% and 100%, and 88.9% and 90%, respectively, showing no significant differences (p>0.05).

CONCLUSION

CEUS has obvious superiority over conventional US in the general diagnostic accuracy of solid pancreatic lesions and in the diagnostic consistency among doctors. The performances of CEUS are similar to that of CECT in the diagnosis of pancreatic carcinoma and focal pancreatitis.

Contrast-enhanced EUS for differential diagnosis of pancreatic mass lesions: a meta-analysis

BACKGROUND

Distinguishing pancreatic adenocarcinomas from other pancreatic masses remains challenging with current imaging techniques. Contrast-enhanced EUS further improved the efficacy of EUS to characterize pancreatic lesions.

OBJECTIVE

To assess the accuracy of contrast-enhanced EUS for diagnosing adenocarcinoma in patients with pancreatic masses by pooling data of existing trials.

DESIGN

We systematically searched the Medline, PubMed, Web of Science, Embase, and Cochrane Central Trials databases for relevant studies published. Meta-analysis was performed. Pooling was conducted in a fixed-effect model or a random-effects model.

PATIENTS

Twelve studies involving 1139 patients were included.

INTERVENTION

Contrast-enhanced EUS.

MAIN OUTCOME MEASUREMENTS

Meta-analysis and meta-regression analysis.

RESULTS

The pooled sensitivity of contrast-enhanced EUS for the differential diagnosis of pancreatic adenocarcinomas was 94% (95% CI, 0.91-0.95), and the specificity was 89% (95% CI, 0.85-0.92). The area under the curve under summary receiver operating characteristic was 0.9732. The pooled positive likelihood ratio was 8.09 (95% CI, 4.47-14.64), and the negative likelihood ratio was 0.08 (95% CI, 0.06-0.10). The subgroup analysis by exclusion of the outliers provided a sensitivity of 93% (95% CI, 0.91-0.95) and a specificity of 93% (95% CI, 0.89-0.95) for the differential diagnosis of pancreatic adenocarcinomas. The area under the curve under summary receiver operating characteristic was 0.9745.

LIMITATIONS

A small number of studies met the inclusion criteria.

CONCLUSION

Contrast-enhanced EUS is a promising, reliable modality for the differential diagnosis of pancreatic adenocarcinoma in patients with pancreatic mass lesions. The finding of a hypoenhanced lesion was a sensitive and accurate predictor of pancreatic adenocarcinomas. It seems to be a useful tool in clinical practice.

Contrast-enhanced ultrasound in abdominal imaging

The administration of a contrast agent is considered an essential tool to evaluate abdominal diseases using Ultrasound. The most targeted organ is the liver, especially to characterize focal liver lesions and to assess the response to percutaneous treatment. However, the expanding abdominal indications of contrast-enhanced ultrasound make this technique an important tool in the assessment of organ perfusion including the evaluation of ischemic, traumatic, and inflammatory diseases.

Intra-/Interobserver Agreement of Enhancement Pattern for Pancreatic Head Lesions Using Contrast-Enhanced Ultrasound: According to EFSUMB Guidelines

Objective: To evaluate the intra-/interobserver agreement of the visual interpretation of contrast-enhanced ultrasound (CEUS) of pancreatic head lesions and its concordance with the histological test results. Material and Methods: Two observers (A + B) evaluated by simple visual interpretation 40 consecutive CEUS examinations of pancreatic head lesions and one of the observers evaluated the examinations twice (A1 + A2). The examinations were evaluated according to the criteria outlined in EFSUMB guidelines. The two experienced observers were blinded to histological evidence and clinical information of tumor type and to each other’s results. Results: The kappa value for the intraobserver evaluation between observer A1 and A2 was 0.89, equating to almost perfect agreement. The kappa value for the interobserver evaluation between observer A1 and B was 0.76 and between observer A2 and B it was 0.75, both equating to substantial agreement. Evaluation of the visual interpretation compared to the histological test result showed a positive predictive value for A1, A2 and B versus biopsy of 97%, 94% and 90% respectively and an accuracy of 83%, 88% and 73% respectively. Conclusions: Visual interpretation for assessment of contrast enhancement of pancreatic head lesions seemed to be an accurate method with reproducible results and good concordance with the histological test results.

Metastatic disease to the pancreas: an imaging challenge

Metastatic lesions of the pancreas are uncommon, accounting for approximately 2% of pancreatic malignancies. Many tumours involve the pancreas secondarily and may manifest with different clinical and imaging characteristics. Although many patients have widespread disease, isolated metastases can be found. Surgical management is associated with improved survival in these cases. The experience of the pancreatic surgery unit and imaging department of our hospital in many patients presenting with pancreatic metastases is presented, and a review of the recent literature is undertaken. Main Messages • The early recognition of secondary pancreatic tumours on US, CT and MRI is extremely important. • Pancreatic metastases may mimic primary pancreatic adenocarcinoma or induce acute pancreatitis. • Most pancreatic metastases are discovered on a CT examination performed for follow-up.

Solid pseudopapillary tumors of the pancreas: contrast-enhanced sonographic features

OBJECTIVES

The aims of this study were to determine the features of solid pseudopapillary tumors of the pancreas on contrast-enhanced sonography and correlate them with pathologic findings.

METHODS

Five patients with solid pseudopapillary tumors of the pancreas underwent conventional sonographic, color Doppler flow imaging, and contrast-enhanced sonographic examinations. Time-intensity curves were used to calculate the contrast enhancement times, wash-out times, and enhancement patterns of the lesions. Three of the 5 patients also underwent contrast-enhanced computed tomography. All cases were confirmed by surgery and pathologic examination.

RESULTS

The study included 3 women and 2 men. Tumor diameters ranged from 4.4 to 13.0 cm. Sonography revealed round well-defined encapsulated tumors. Two appeared as mixed cystic-solid and 3 as solid masses on conventional sonography. One mass had a macrocalcification. Some areas of blood flow were seen in 3 of the masses on color Doppler flow imaging. On contrast-enhanced sonography, the peripheral rims of the tumors showed isoenhancement during the early arterial phase, and the interiors of the masses showed heterogeneous enhancement consisting of regions of isoenhancement, hypoenhancement, and nonenhancement. Progressive wash-out of the contrast agent during venous phases revealed hypoenhancement compared with normal adjacent pancreatic parenchyma. Pathologic findings showed that each tumor was completely encapsulated and had varying degrees of internal hemorrhage and necrosis.

CONCLUSIONS

Solid pseudopapillary tumors of the pancreas have characteristic findings on contrast-enhanced sonography, including peripheral rim isoenhancement and internal heterogeneous enhancement with nonenhanced portions; these features may help differentiate solid pseudopapillary tumors from other pancreatic neoplasms.

Cystic pancreatic lesions: current evidence for diagnosis and treatment

Pancreatic cystic neoplasms are detected at an increasing frequency due to an increased use and quality of abdominal imaging. There are well known differential diagnostic difficulties concerning these lesions. The aim is to review current literature on the diagnostic options and the following treatment for cystic lesions in the pancreas focusing on serous cystadenomas, primary mucinous neoplasm of the pancreas and mucinous cystadenocarcinomas, as well as intraductal papillary mucinous neoplasms, starting with excluding pseudocysts. A conservative approach is feasible in patients with a clinical presentation suggestive of an asymptomatic serous cystadenoma. Surgical management, as well as follow-up, is discussed for each of the types of neoplastic lesions, including an uncharacterized cyst, based on patient data, symptoms, serum analysis, cyst fluid analysis and morphological features. Aspects for future diagnostics and management of these neoplasia are commented upon.

Histological observation of islet hemorrhage induced by diagnostic ultrasound with contrast agent in rat pancreas

Contrast enhanced diagnostic ultrasound CEDUS has been shown to induce capillary hemorrhage in heart and kidney. This study characterized the capillary hemorrhage induced in rat pancreas. The pancreata of anesthetized hairless rats were accessed by laparotomy. A 1.5 MHz diagnostic ultrasound probe with 2.3 MPa peak rarefactional pressure amplitude and 1 s intermittent trigger was used to scan the pancreas, located at the focus (3.8 cm), through saline coupling. The probe was swept to expose the entire organ in 5 min during infusion of Definity® contrast agent at 10 µL/kg/min, and this was repeated in a reverse sweep. The entire pancreas was removed, spread flat for fixation and histological slides were prepared from the mid-plane. Slides were scored blind for islet hemorrhage over the entire area of the organ. Intra-islet microlesions were evident and hemorrhage surrounded many islets. The hemorrhage often impacted nearby acini, and expanded into inter-lobular septa. In CEDUS pancreata removed soon after scanning, 76.2±11.8% (n = 6) of islets had evidence of hemorrhage and/or islet microlesions compared to 1.1±2.5% (n = 5) for sham CEDUS (P<0.001). In pancreata removed after 4 hr, fibrin formation was detected by immunohistology in the hemorrhage and intra-islet microlesions. Diagnostic ultrasound with contrast agent induced substantial capillary hemorrhage in rat pancreas, concentrated particularly in the islets.

Future perspectives on neuroendocrine tumors

In the last 30 years the incidence and prevalence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has increased substantially. This could be partly due to improvements in diagnostic imaging, which lead to the incidental diagnosis of asymptomatic cases. However, despite these improvements, patients typically experience long delays before they are diagnosed. In this review, we discuss both the limitations and advances in our understanding of the pathogenesis, molecular and cellular biology, diagnosis, classification, staging, and treatment of GEP-NETs in order to identify which factors could be contributing to the delay in diagnosis and timely treatment of these patients. Within this context, the results from the most relevant clinical trials the available targeted therapies for the treatment of GEP-NETs, such as the "RAD001 in Advanced Neuroendocrine Tumors," will be discussed.

The application value of contrast-enhanced ultrasound in the differential diagnosis of pancreatic solid-cystic lesions

OBJECTIVE

To retrospectively determine the accuracy of baseline ultrasound (BUS) and of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of pancreatic solid-cystic lesions.

METHODS

Fifty-four pancreatic solid-cystic lesions in 52 patients were examined with BUS and CEUS, two different seniority radiologists read the images independently, Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic value of BUS and CEUS in the diagnosis of benign or malignant pancreatic solid-cystic lesions, the diagnostic consistency between different seniority radiologists was evaluated by Kappa statistics.

RESULTS

Among the 54 lesions, there were pancreatic cyst five cases, pancreatic pseudocyst twenty cases, pancreatic cystadenoma eight cases, pancreatic cystadenocarcinoma seven cases, intraductal papillary mucinous neoplasm of pancreas (IPMN) three cases, pancreatic carcinoma combined liquefied six cases, solid-pseudopallary tumor of pancreas (SPTP) three cases, pancreatic myopericytoma one case, pancreatic lymphangioma one case. After ROC analysis, the areas under the ROC curve (Az) were 0.752 by BUS, 0.928 by CEUS to resident radiologist, and 0.896 by BUS, 0.954 by CEUS to staff radiologist. The correct diagnosis rate of specific disease was 42.6% by BUS, 64.8% by CEUS to staff radiologist (P<0.05), and 33.3% by BUS, 53.7% by CEUS to resident radiologist (P<0.05). The interobserver agreement in CEUS is higher than that in BUS, the Kappa value was 0.889 ± 0.062 and 0.428 ± 0.126 respectively.

CONCLUSION

Compared with BUS, CEUS can significantly enhance the diagnostic rate of pancreatic solid-cystic lesions.

Transabdominal contrast-enhanced ultrasonography of pancreatic cancer

Since its introduction, contrast-enhanced ultrasonography (CEUS) has significantly extended the value of ultrasonography (US). CEUS can be used to more accurately determine pancreatic lesions compared to conventional US or to characterize lesions already detectable by US. Thus, CEUS can aid in the differential diagnosis of pancreatic tumors. Using US contrast media, it is possible to visually detect microvessels in the majority of pancreatic ductal adenocarcinomas. Thus, the use of quantitatively evaluated transabdominal CEUS can help in the differentiation of patients with mass-forming pancreatitis from patients with pancreatic adenocarcinomas. In neuroendocrine pancreatic tumors, different enhancement patterns can be observed in relation to the tumor mass: larger ones show a rapid early enhancement sometimes combined with necrotic central structures, and smaller ones disclose a capillary-blush enhancement. Pseudocysts, the most widespread cystic lesions of the pancreas, are not vascularized. They do not show any signal in CEUS and remain entirely anechoic in all phases, while true cystic pancreatic tumors usually have vascularized septa and parietal nodules. In summary, CEUS is effective for differentiating solid pancreatic tumors in most cases. CEUS is safe and cost effective and can better discriminate solid from cystic pancreatic lesions, thereby directing further imaging modalities.

Pancreatic multicenter ultrasound study (PAMUS)

AIM

To describe the typical CEUS pattern of pancreatic lesions and to evaluate the diagnostic accuracy of Contrast-enhanced ultrasound (CEUS) in their characterization.

MATERIALS AND METHODS

All US and CEUS examinations of focal pancreatic masses performed in six centers during a period of five years were reviewed. Inclusion criteria were: focal pancreatic mass pathologically proved, visible at ultrasound (US) and studied with CEUS. All lesions were then evaluated for size, aspect and enhancement pattern. Sensitivity, specificity, positive and negative predictive values with 95% CIs were calculated to define diagnostic accuracy of CEUS in respect to pathology. Diagnostic confidence of US and CEUS, discerning between benign and malignant lesions, were represented by using ROC (receiver operating characteristics) curves. Agreement was evaluated by means of k statistics.

RESULTS

1439 pancreatic lesions were included. At CEUS the lesions were divided into solid (89%) and cystic (12%) masses and classified into six and eight categories, respectively. Among the solid lesions, adenocarcinomas were characterized with an accuracy of 87.8%. Among the cystic lesions, cystic tumors were diagnosed with an accuracy of 97.1%. ROC curve area increased from 0.637 for US to 0.877 for CEUS (p<0.0001). Inter-observer agreement was slightly higher for solid (k=0.78) than cystic (k=0.62) lesions. In none of the centers side effects were reported.

CONCLUSION

CEUS is accurate in the characterization of pancreatic lesions. CEUS should be considered as a complementary imaging method for pancreatic lesions characterization.

Enhancing pancreatic adenocarcinoma delineation in diffusion derived intravoxel incoherent motion f-maps through automatic vessel and duct segmentation

Diffusion-based intravoxel incoherent motion imaging has recently gained interest as a method to detect and characterize pancreatic lesions, especially as it could provide a radiation- and contrast agent-free alternative to existing diagnostic methods. However, tumor delineation on intravoxel incoherent motion-derived parameter maps is impeded by poor lesion-to-pancreatic duct contrast in the f-maps and poor lesion-to-vessel contrast in the D-maps. The distribution of the diffusion and perfusion parameters within vessels, ducts, and tumors were extracted from a group of 42 patients with pancreatic adenocarcinoma. Clearly separable combinations of f and D were observed, and receiver operating characteristic analysis was used to determine the optimal cutoff values for an automated segmentation of vessels and ducts to improve lesion detection and delineation on the individual intravoxel incoherent motion-derived maps. Receiver operating characteristic analysis identified f = 0.28 as the cutoff for vessels (Area under the curve (AUC) = 0.901) versus tumor/duct and D = 1.85 μm(2) /ms for separating duct from tumor tissue (AUC = 0.988). These values were incorporated in an automatic segmentation algorithm and then applied to 42 patients. This yielded clearly improved tumor delineation compared to individual intravoxel incoherent motion-derived maps. Furthermore, previous findings that indicated that the f value in pancreatic cancer is strongly reduced compared to healthy pancreatic tissue were reconfirmed.

Contrast-enhanced and targeted ultrasound

Ultrasonic imaging is becoming the most popular medical imaging modality, owing to the low price per examination and its safety. However, blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies. For perfusion imaging, markers have been designed to enhance the contrast in B-mode imaging. These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells. In this review, the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described. Furthermore, an outline of clinical imaging applications of contrast-enhanced ultrasound is given. It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition, and how these phenomena may be utilized in ultrasonic imaging. Aided by high-speed photography, our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques. More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves, and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs. These are beginning to be accepted into clinical practice. In the long term, targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.

Quantitative contrast-enhanced ultrasonographic analysis of perfusion in the kidneys, liver, pancreas, small intestine, and mesenteric lymph nodes in healthy cats

OBJECTIVE

To evaluate perfusion of abdominal organs in healthy cats by use of contrast-enhanced ultrasonography.

ANIMALS

10 young healthy anesthetized cats.

PROCEDURES

Contrast-enhanced ultrasonography of the liver, left kidney, pancreas, small intestine, and mesenteric lymph nodes was performed on anesthetized cats.

RESULTS

Typical perfusion patterns were found for each of the studied organs. Differences in perfusion among organs were associated with specific physiologic features. The liver was enhanced gradually and had a more heterogeneous perfusion pattern because of its dual blood supply and close proximity to the diaphragm, compared with other organs. An obvious and significant difference in perfusion was detected between the renal cortex and medulla. No significant differences in perfusion were detected among the pancreas, small intestine, and mesenteric lymph nodes.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that contrast-enhanced ultrasonography can be used in cats to estimate organ perfusion as in other species. Observed differences in perfusion variables can be mostly explained by physiologic differences in vascularity.

Assessment of contrast-enhanced ultrasonography in diagnosis and preoperative localization of insulinoma

OBJECTIVE

This study was to evaluate the value of contrast-enhanced ultrasonography (CEUS) in the diagnosis and preoperative localization of insulinoma and explore the enhancement patterns of the tumors.

METHODS

Unenhanced and contrast-enhanced ultrasonographic examinations of 31 patients who underwent resection of insulinomas were retrospectively reviewed. The diagnosis sensitivity and localization specificity of CEUS for insulinomas were determined. Results of unenhanced ultrasonography and CEUS were compared by Chi-square test.

RESULTS

Unenhanced ultrasonography could display 9 of 37 (24.3%) surgically verified insulinomas in 31 patients, while the diagnosis sensitivity and localization specificity of preoperative CEUS was 33 (89.2%) and 32 (86.5%) of the 37 tumors, respectively. In contrast to the unenhanced ultrasonography, the improvement of CEUS in the diagnosis and preoperative localization of insulinomas was significant (p<0.0001). The enhancement pattern of insulinoma on CEUS was fast wash-in and slow wash-out. All the tumors were homogeneous hypervascularity in the earlier arterial phase, while the tumors still displayed hyperenhancing pattern in the late phase.

CONCLUSION

Our study demonstrates the great potential of CEUS in the diagnosis and preoperative localization of insulinomas. Since CEUS is a convenient, inexpensive, effective and non-invasive modality, the study supports the use of CEUS as a primary tool in the evaluation of patients with insulinomas.

Usefulness of contrast-enhanced transabdominal ultrasound for tumor classification and tumor staging in the pancreatic head

OBJECTIVE

To evaluate contrast-enhanced ultrasound (CEUS) and compare it to ultrasound (US) and 64-slice-CT (64-CT) for diagnosing, staging and evaluation of resectability of pancreatic cancer.

MATERIAL AND METHODS

US, CEUS and 64-CT were performed in 49 consecutive patients with pancreatic head tumors and with suspected cancer. After evaluation 44 patients had pancreatic head adenocarcinoma and 5 had chronic pancreatitis, all confirmed by histology.

RESULTS

The sensitivity of US, CEUS and 64-CT for diagnosing malignant pancreatic head tumors was 89%, 86% and 93%, respectively, and the overall accuracy was 82%, 86% and 88% respectively. There was no significant difference in the malignant tumor size measurement between US and CEUS (p = 0.3619) or between US and 64-CT (p = 0.2129), but a significant difference was seen in the size measured by CEUS and 64-CT (p = 0.0197). The CEUS measurements on the tumor size were smaller. The overall accuracy for M staging of the patients who had surgery for adenocarcinoma was 86% and 90% for US + CEUS and 64-CT, respectively. By performing the CEUS and 64-CT we additionally found, respectively, 35% and 45% non-resectable patients of a group of patients, who were considered resectable on the primary radiological image material.

CONCLUSIONS

CEUS may be a useful diagnostic tool in the diagnosis and staging of pancreatic head tumors. For the assessment of resectability CEUS did not prove useful. However, CEUS seemed very useful as an additional instrument in the detection of non-resectable patients already considered resectable on primary radiological image material.

Contrast-enhanced ultrasound in the staging of acute pancreatitis

OBJECTIVE

To determine the diagnostic value of contrast-enhanced ultrasound (CEUS) in the assessment of acute pancreatitis, with computed tomography (CT) as the reference standard.

METHODS

Fifty consecutive patients (mean age 58.4 years; range 23-86 years) with acute pancreatitis underwent prospectively both CT and ultrasonography, including CEUS, within a 24-h interval. Pancreatic vascularisation was evaluated with CEUS after injection of a second-generation US contrast-enhancing agent. Acute pancreatitis severity was graded according to the Balthazar index. The results were compared with CT severity index and clinical outcome by using Spearman's correlation coefficient.

RESULTS

A significant correlation between CT and CEUS was found for the CT severity index (r = 0.926), extent of necrosis (r = 0.893) and Balthazar grade (r = 0.884). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting severe acute pancreatitis based on CT findings (severity index greater than 3 and/or presence of necrosis) were respectively 91%, 100%, 100% and 83%. A significant correlation between CEUS severity index and clinical variables was found: Ranson score (r = 0.442), C-reactive protein (CRP) levels 48 h after admission (r = 0.385) and length of hospital stay (r = 0.362).

CONCLUSION

CEUS is comparable to CT in detecting pancreatic necrosis as well as predicting its clinical course. Therefore, when CT is contraindicated CEUS may be a valid alternative.

Imaging techniques in pancreatic tumors

Conventional ultrasonography represents the first diagnostic imaging modality for the study of pancreatic tumors. Contrast-enhanced ultrasound has significantly improved the accuracy of first-line examination and may influence the choice of second-line investigations: multidetector computed tomography is considered the gold standard for studying pancreatic solid lesions and tumor staging, while MRI with magnetic resonance cholangiopancreatography allows better study of pancreatic cystic lesions and the ductal system. To definitely diagnose a pancreatic lesion, image-guided fine-needle-aspiration or biopsy are very often required. PET with 18-fluorodeoxyglucose, endoscopic ultrasound and intraoperative ultrasonography remain techniques often employed in the third line. This article reviews the imaging techniques generally used for diagnosing the main pancreatic tumors, and a work-up algorithm is finally proposed.

Contrast-enhanced ultrasound of the pancreas

The introduction of contrast-enhanced ultrasonography (CEUS) has led to major improvements in the diagnostic capabilities of ultrasound (US). The innovative use of CEUS for study of the pancreas has created the need for a definition of the most frequent dynamic features of solid and cystic masses. CEUS is less expensive compared to computed tomography and magnetic resonance imaging and is able to significantly improve the accuracy of US, allowing better characterization and staging of pancreatic pathologies.

[Usefulness of contrast-enhanced ultrasonography in daily clinical practice: a multicenter study in Spain]

OBJECTIVES

We aimed to determine whether the use of ultrasonographic contrast agents improves the diagnostic performance of ultrasonography (US).

MATERIAL AND METHODS

We carried out a prospective multicenter study in 42 hospitals. We included 1786 patients with inconclusive US; 84.9% of the inconclusive studies were abdominal US (including studies of the liver, kidneys, spleen, and other sites), 6.2% were studies of the peripheral vessels, 4.3% were breast studies, and 4.6% were other studies. We evaluated the type of contrast-enhanced US (color Doppler or contrast-specific method), type of contrast agent, dose and number of doses, and type of administration (bolus or infusion). We evaluated whether the findings at contrast-enhanced US improved the diagnostic performance of unenhanced US and whether they enabled a conclusive diagnosis to be reached.

RESULTS

The contrast agent SonoVue was used in 99.9% of the studies; a single dose of contrast agent was used in 84.8%, and the contrast agent was administered in bolus in 98.5%. Contrast-enhanced US improved the diagnostic performance in 91.6% of cases and enabled the conclusive diagnosis in 69.2%. The best diagnostic performance was obtained in the supraaortic trunks, where a definitive diagnosis was reached in 95.4% of cases, followed by the abdominal area, with a conclusive diagnosis in 72.6% of cases.

CONCLUSIONS

The use of contrast-enhanced US significantly improved the diagnostic performance of US and enabled a conclusive diagnosis in most cases.

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.

Contrast-enhanced ultrasonography of the pancreas

Ultrasound is often the first examination performed in patients with suspicion of pancreatic disease. The introduction of contrast-enhanced ultrasonography (CEUS) has led to great developments in the diagnostic capabilities of ultrasound. Dynamic observation of an enhancement allows a highly sensitive evaluation of any perfusion of the abdominal organs. Study of the pancreas is a new and promising application of CEUS, and can be used to characterize pancreatic lesions visible with conventional ultrasonography (US). This article reviews the clinical and surgical applications of CEUS in different pancreatic diseases and in their management.

Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors

OBJECTIVE

Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered.

MATERIALS AND METHODS

We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearman's test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade.

RESULTS

In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022).

CONCLUSION

The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.

Pancreatic perfusion: noninvasive quantitative assessment with dynamic contrast-enhanced MR imaging without and with secretin stimulation in healthy volunteers--initial results

PURPOSE

To prospectively quantify pancreatic regional perfusion with dynamic contrast material-enhanced magnetic resonance (MR) imaging by using a one-compartment model and to assess perfusion changes during secretin stimulation in healthy volunteers.

MATERIALS AND METHODS

The study had institutional review board approval, and written informed consent was obtained. Ten healthy volunteers (five men, five women; mean age, 24.7 years +/- 1.9 [standard deviation]; range, 22-29 years) underwent MR imaging pancreatic perfusion studies performed twice without secretin and twice during secretin stimulation. Dynamic contrast-enhanced MR imaging consisted of saturation-recovery T1-weighted turbo-field-echo imaging with peripheral pulse triggering and respiratory tracking. A dose of 0.05 mmol gadodiamide per kilogram of body weight was injected at a rate of 3.5 mL/sec. Regional perfusion parameters were fitted with a one-compartment model. The analysis of variance test for repeated measurements was used to assess differences in pancreatic perfusion without and that with secretin administration.

RESULTS

Significant differences in perfusion parameters between the three pancreatic regions were observed (P < .05). During secretin stimulation, a significant difference was observed only between the body and the tail of the pancreas (P = .02). A significant increase (P = .003) in pancreatic perfusion was observed after secretin administration. Mean pancreatic perfusion was 184 mL/min/100 g of tissue +/- 71, 207 mL/min/100 g +/- 77, and 230 mL/min/100 g +/- 87 without secretin and 342 mL/min/100 g +/- 154, 338 mL/min/100 g +/- 156, and 373 mL/min/100 g +/- 176 after secretin stimulation in the head, body, and tail of the pancreas, respectively. Intraindividual variability was 21% without secretin stimulation and 46% with secretin stimulation.

CONCLUSION

Dynamic contrast-enhanced MR imaging enables noninvasive quantification of regional pancreatic perfusion in resting conditions and demonstrates the increase in pancreatic perfusion during secretin stimulation in healthy subjects.

Gastroenteropancreatic neuroendocrine tumours

Gastroenteropancreatic (GEP) neuroendocrine tumours (NETs) are fairly rare neoplasms that present many clinical challenges. They secrete peptides and neuroamines that cause distinct clinical syndromes, including carcinoid syndrome. However, many are clinically silent until late presentation with mass effects. Investigation and management should be highly individualised for a patient, taking into consideration the likely natural history of the tumour and general health of the patient. Management strategies include surgery for cure (which is achieved rarely) or for cytoreduction, radiological intervention (by chemoembolisation and radiofrequency ablation), chemotherapy, and somatostatin analogues to control symptoms that result from release of peptides and neuroamines. New biological agents and somatostatin-tagged radionuclides are under investigation. The complexity, heterogeneity, and rarity of GEP NETs have contributed to a paucity of relevant randomised trials and little or no survival increase over the past 30 years. To improve outcome from GEP NETs, a better understanding of their biology is needed, with emphasis on molecular genetics and disease modeling. More-reliable serum markers, better tumour localisation and identification of small lesions, and histological grading systems and classifications with prognostic application are needed. Comparison between treatments is currently very difficult. Progress is unlikely to occur without development of centers of excellence, with dedicated combined clinical teams to coordinate multicentre studies, maintain clinical and tissue databases, and refine molecularly targeted therapeutics.

Comparison of contrast-enhanced sonography and MRI in displaying anatomic features of cystic pancreatic masses

OBJECTIVE

The purpose of this study was to compare the accuracy rates of unenhanced sonography, contrast-enhanced sonography, and MRI in displaying the anatomic features of cystic pancreatic masses larger than 1.5 mm in diameter.

MATERIALS AND METHODS

Unenhanced and contrast-enhanced sonographic and MRI examinations of 33 patients who underwent resection of a cystic pancreatic mass were retrospectively reviewed. Two radiologists blinded to the final histologic diagnosis reviewed the images, specifically assessing the presence of intralesional mural nodules and septa. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated on the basis of correlation with surgical findings. Results of unenhanced sonography, contrast-enhanced sonography, and MRI were compared by McNemar test. Correlation of unenhanced and contrast-enhanced sonographic versus pathologic results was established with Spearman's test. Interobserver variability was determined.

RESULTS

Contrast-enhanced sonography correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 88.8%; positive predictive value, 87.5%; negative predictive value, 94.1%; accuracy, 90.9%) and nodules in six of eight lesions (sensitivity, 75%; specificity, 96%; positive predictive value, 85.7%; negative predictive value, 92.3%; accuracy, 90.9%). MRI correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 61.1%; positive predictive value, 66.6%; negative predictive value, 91.6%; accuracy, 75.7%) and nodules in seven of eight lesions (sensitivity, 87.5%; specificity, 80%; positive predictive value, 58.3%; negative predictive value, 95.2%; accuracy, 81.8%). The difference between the diagnostic accuracy of contrast-enhanced sonography and that of MRI was not significant (p = 0.05, McNemar test) in the identification of septa and nodules. The correlation between contrast-enhanced sonographic findings and pathologic results (Rs = 0.93; p < 0.001) was significantly better than that between sonographic and pathologic results (Rs = 0.52; p < 0.0001). Interobserver agreement had a kappa value of 0.86-0.94.

CONCLUSION

Contrast-enhanced sonography compares favorably with MRI in displaying the anatomic features of cystic pancreatic masses seen on transabdominal sonography.