Sonographic diagnosis of pancreatic islet cell tumor: value of intermittent harmonic imaging

Contrast-enhanced harmonic endoscopic ultrasonography for differential diagnosis of localized gallbladder lesions

BACKGROUND AND AIM

Differential diagnosis of localized gallbladder lesions is challenging. The aim of the present study was to evaluate the utility of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) for diagnosis of localized gallbladder lesions.

METHODS

One hundred and twenty-five patients with localized gallbladder lesions were evaluated by CH-EUS between March 2007 and February 2014. This was a single-center retrospective study. Utilities of fundamental B-mode EUS (FB-EUS) and CH-EUS in the differentiation of gallbladder lesions and sludge plug were initially compared. Thereafter, these two examinations were compared with respect to their accuracy in the diagnosis of malignant lesions. Five reviewers blinded to the clinicopathological results evaluated microcirculation patterns in the vascular and perfusion images.

RESULTS

In the differentiation between gallbladder lesions and sludge plug, FB-EUS had a sensitivity, specificity, and accuracy of 82%, 100%, and 95%, respectively, whereas CH-EUS had a sensitivity, specificity, and accuracy of 100%, 99%, and 99%, respectively. FB-EUS-based diagnosis of carcinomas based on tumor size and/or shape had a sensitivity, specificity, and accuracy of 61-87%, 71-88%, and 74-86%, respectively. Additional information regarding irregular vessel patterns in the vascular image and/or heterogeneous enhancement in the perfusion image on CH-EUS increased the sensitivity, specificity, and accuracy for the diagnosis of carcinomas to 90%, 98%, and 96%, respectively. There was a significant difference between FB-EUS and CH-EUS in terms of carcinoma diagnosis.

CONCLUSION

CH-EUS was useful for the evaluation of localized gallbladder lesions.

Resectable pancreatic adenocarcinoma: depiction of tumoral margins at contrast-enhanced ultrasonography

To evaluate if contrast-enhanced ultrasonography (CEUS) improves the depiction of tumoral margins of pancreatic adenocarcinoma in relation to tumor enhancement, using pathology as criterion standard.

METHODS

Two hundred forty-one patients affected by pancreatic ductal adenocarcinoma were investigated at CEUS with a second-generation contrast medium of sulfur-hexafluoride microbubbles. Sixty-seven (27.8%) of 241 tumors were resected. By consensus, 2 radiologists reviewed the CEUS examination results of the 67 tumors judging the enhancement as low (hypovascular lesions, hypoechoic tothe adjacent parenchyma) or high (iso- or hypervascular lesions, iso- or hyperechoic to the adjacent parenchyma). The resected tumors were evaluated at pathology for the presence of positive neoplastic (R+) or negative neoplastic (R-) resected margins.

RESULTS

Of the 67 resected tumors, 35 (52.3%) were R-, whereas 32 (47.7%) were R+. Moreover, at CEUS, of the 67 resected tumors, 43 (64.1%) were hypovascular with low enhancement and 24 (35.8%) were iso-hypervascular with high enhancement. In the R- group, 27 (77.1%) of 35 tumors were hypovascular. In the R+ group, 16 (50%) of 32 lesions were hypovascular.

CONCLUSIONS

At CEUS the depiction of tumoral margins of pancreatic adenocarcinoma is more accurate in low enhancement than in high enhancement. The pattern of enhancement of pancreatic adenocarcinoma influences the depiction of tumoral margins at CEUS.

Intrapancreatic accessory spleen: findings on MR Imaging, CT, US and scintigraphy, and the pathologic analysis

Although the tail of the pancreas is the second most common site of an accessory spleen, intrapancreatic accessory spleen (IPAS) has rarely been noted radiologically. However, as the imaging techniques have recently advanced, IPAS will be more frequently detected as an incidental pancreatic nodule on CT or MRI. Because accessory spleens usually pose no clinical problems, it is important to characterize accessory spleens as noninvasively as possible. An IPAS has similar characteristics to those of the spleen on the precontrast and contrast-enhanced images of all the imaging modalities. In particular, inhomogeneous enhancement of an IPAS in its early phases may be a diagnostic clue. Superparamagnetic iron oxide (SPIO)-enhanced MRI and Levovist-enhanced US, and the mechanisms of which are theoretically similar to that of Tc-99m scintigraphy, can be used as alternative tools to confirm the diagnosis of IPAS. An IPAS shows a significant signal drop similar to the spleen on the SPIO-enhanced T2 or T2*-weighted imaging and prolonged enhancement on the delayed hepatosplenic phase of contrast-enhanced US. We review and illustrate the differential points between IPAS and hypervascular pancreatic tumors in this manuscript.

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.

Diagnosis of gallbladder diseases by contrast-enhanced phase-inversion harmonic ultrasonography

We evaluated the usefulness of contrast-enhanced ultrasonography(US) for detecting and differentiating gallbladder lesions. Contrast-enhanced coded phase-inversion harmonic US was performed on 90 patients with gallbladder abnormalities. After administering Levovist, we observed the gallbladders in real time. Contrast-enhanced coded phase-inversion harmonic ultrasonography was compared with B-mode US and contrast-enhanced computer tomography (CT) with regard to the sensitivity and specificity in depicting the elevated gallbladder lesions. Furthermore, we assessed how the vascular patterns of the elevated gallbladder lesions depicted by contrast-enhanced US correlated with the diagnosis. Contrast-enhanced US efficiently discriminated true lesions from biliary sludge, unlike B-mode US. Consequently, contrast-enhanced US was more specific (100%) than B-mode US (81%), although their sensitivities were similar (98% and 96%, respectively). Contrast-enhanced US was also more sensitive that contrast-enhanced CT (98% versus 79%), although the two methods were equally sensitive (100% versus 95%). We classified the vascular patterns of the abnormalities depicted by contrast-enhanced US in the 90 cases into types 1 to 4, which represent branch-like, heterogeneous, homogeneous, and avascular patterns, respectively. All type 1 and 2 lesions were over 10 mm in size while most (88%) type 3 lesions were 10 mm or less in size. While the majority of carcinomas (86%) were type 1 or 2, three benign lesions also showed these patterns. Thus, the vascular pattern may simply reflect the size of the lesion and therefore its usefulness in diagnosing gallbladder lesions may be limited. Nevertheless, contrast-enhanced US is clearly superior to the other techniques in discriminating biliary sludge from other lesions.

Contrast-Enhanced Sonography of Intrapancreatic Accessory Spleen in Six Patients

OBJECTIVE

The purpose of this article is to describe the characteristic findings of intrapancreatic accessory spleen over time on contrast-enhanced sonography.

CONCLUSION

On contrast-enhanced sonography, intrapancreatic accessory spleens showed a characteristic inhomogeneous enhancement on the early vascular phase, enhancement similar to the main spleen during the postvascular phases, and prolonged enhancement on the delayed hepatosplenic phase.

Echo-enhanced ultrasound--a new imaging modality for the differentiation of pancreatic lesions

INTRODUCTION

Echo-enhanced ultrasound is a newly available mode of imaging for differential diagnosis of pancreatic tumours. Ductal carcinomas are often hypovascularised compared with the surrounding tissue. Neuroendocrine tumours, on the other hand, are hypervascularised lesions. Tumours associated with pancreatitis have a different vascularisation pattern depending on inflammation and necrosis. Cystadenomas frequently have many vessels along the fibrotic strands.

RESULTS

Data from prospective studies have demonstrated, on the basis of these imaging criteria, that the sensitivity and specificity of echo-enhanced sonography for differentiation of pancreatic masses are >or=85 and >or=90%, respectively.

CONCLUSIONS

Pancreatic tumours have a different vascularisation pattern in echo-enhanced ultrasound. These characteristics can be used with high diagnostic accuracy for differential diagnosis.

Contrast-enhanced sonography of pancreatic carcinoma: correlations with pathological findings

BACKGROUND

We examined contrast-enhanced harmonic gray-scale sonographic findings of pancreatic carcinoma in relation to the pathological findings in resected specimens to evaluate correlations between observations made by this modality and the pathological findings.

METHODS

The pathological findings of surgical specimens obtained from 16 patients were examined in relation to the contrast-enhanced harmonic gray-scale sonography findings. Lesion vascularity was examined by contrast-enhanced harmonic gray-scale sonography from 20 to 50 s after the injection of Levovist (Schering, Berlin, Germany) (early phase), and lesion enhancement was also monitored at approximately 90 s after injection (delayed phase).

RESULTS

Contrast-enhanced harmonic gray-scale sonography showed positive enhancement in 12 of the 16 lesions (peripheral tumor region alone, n = 9; entire tumor, n = 3), while the other 4 lesions showed no contrast enhancement in any region. Twelve enhanced regions (9 peripheral tumor region and 3 entire tumor regions) detected by contrast-enhanced harmonic gray-scale sonography showed: (1) mild fibrosis with inflammation, in 10 regions (83%); (2) the presence of both carcinoma cells and residual acinar cells in 8 (67%); and (3) presence of relatively large arteries in 2 (17%). In contrast, 13 non-enhanced regions (4 entire tumor regions and 9 central regions) showed: (1) severe fibrosis in 10 regions (77%); (2) necrosis in 7 (54%); and (3) mucin in 4 (31%).

CONCLUSIONS

Contrast-enhanced harmonic gray-scale sonographic findings of pancreatic carcinoma are influenced by interstitial histological features associated with tumor growth.

Dynamic imaging of pancreatic diseases by contrast enhanced coded phase inversion harmonic ultrasonography

BACKGROUND

Coded phase inversion harmonic ultrasonography, a newly available sonographic technique, enables visualisation of slow flow in minute vessels in a real time fashion with the use of a sonographic contrast agent containing monosaccharide. Our purpose was to employ this novel technique to observe microvessels in pancreatic tumours.

SUBJECTS AND METHODS

Sixty five patients with suspicious pancreatic tumours received contrast enhanced coded phase inversion harmonic ultrasonography, contrast enhanced computed tomography, and endosonography. Final diagnoses based on histological findings were pancreatic ductal carcinomas in 49 patients, inflammatory pseudotumours with chronic pancreatitis in seven, and endocrine tumours in nine. For contrast enhanced coded harmonic ultrasonography, Levovist, a contrast agent, was injected intravenously as a bolus. When the first microbubble signal appeared in the pancreas, images of the ideal scanning plane were displayed in a real time continuous fashion (vessel images). Subsequently, interval delay scanning (perfusion images) was taken to demonstrate parenchymal flow. Tumour vascularity was evaluated by using the two types of imaging. Sensitivities for depicting pancreatic tumours were compared between three examinations.

RESULTS

Contrast enhanced ultrasonography demonstrated tumour vessels in 67% of pancreatic ductal carcinomas, although most were relatively hypovascular compared with the surrounding pancreatic tissue. The vascular patterns of tumours obtained by contrast enhanced ultrasonography were closely correlated with those obtained by contrast enhanced computed tomography. Values for sensitivity in depicting pancreatic tumours of 2 cm or less in size were 68% for contrast enhanced computed tomography, 95% for endosonography, and 95% for contrast enhanced ultrasonography.

CONCLUSION

Contrast enhanced coded phase inversion harmonic ultrasonography successfully visualised fine vessels in pancreatic tumours and may play a pivotal role in the depiction and differential diagnosis of pancreatic tumours.

Contrast-enhanced power Doppler sonography of ductal pancreatic adenocarcinomas: correlation with digital subtraction angiography findings

PURPOSE

The purpose of this prospective study was to utilize contrast-enhanced power Doppler sonography to evaluate the enhancement characteristics of ductal pancreatic adenocarcinomas and correlate them with the tumor vascularity observed on digital subtraction angiography (DSA).

METHODS

Twenty consecutive patients with ductal pancreatic adenocarcinoma underwent power Doppler sonography and DSA. Tumor vascularity was assessed using unenhanced and contrast-enhanced power Doppler sonography. The contrast agent Levovist was administered intravenously by bolus injection of a dose of 2.5 g at a concentration of 350 mg/mL; saline was administered immediately thereafter. The patients were asked to hold their breath for 30 seconds (for the period 15-45 seconds after saline injection) while the early phase of enhancement was studied; the delayed phase of enhancement was observed between 60 and 120 seconds after saline administration, while patients breathed gently.

RESULTS

None of the 20 pancreatic carcinomas showed any color signals on power Doppler sonography before administration of the contrast medium. Seventeen (85%) of the 20 pancreatic carcinomas also showed no enhancement in the early and delayed phases of contrast-enhanced power Doppler sonography. However, in the early phase of contrast-enhanced power Doppler sonography; 1 lesion showed pronounced enhancement and 2 showed mild enhancement. On DSA, the 17 carcinomas showing no enhancement on power Doppler sonography were found to be hypovascular, whereas the remaining 3 carcinomas with contrast enhancement on power Doppler sonography were found to be hypervascular.

CONCLUSIONS

The enhancement characteristics of the ductal pancreatic adenocarcinomas correlated well with the tumor vascularity observed on DSA. However, further study is needed to determine the accuracy of contrast-enhanced sonography in the diagnosis of pancreatic masses.

Evaluation of contrast enhancement patterns in pancreatic tumors by coded harmonic sonographic imaging with a microbubble contrast agent

OBJECTIVE

The purpose of the study was to assess patterns of primary pancreatic lesions by contrast-enhanced sonography for differentiating ductal carcinomas from other pancreatic tumors.

METHODS

One hundred six consecutive patients with pancreatic masses, consisting of 83 ductal carcinomas, 7 endocrine carcinomas, 5 intraductal papillary mucinous tumors, 3 cases of autoimmune-related pancreatitis, 3 solid pseudopapillary tumors, 2 cases of chronic pancreatitis, 1 serous cystadenoma, 1 osteoclastoid giant cell tumor, and 1 follicular lymphoma, were examined by contrast-enhanced sonography with coded harmonic imaging in a phase inversion harmonic technique. The contrast enhancement patterns were assessed, and specimens removed during pancreatectomy were subjected to pathologic examination.

RESULTS

Internal tumoral vascularity was detected in 47 (56.6%) of the 83 ductal carcinomas. Vascular image spreading and homogeneous staining throughout the tumors were observed in all endocrine carcinomas. Two of the 5 intraductal papillary mucinous tumors were positive for enhancement effects. Enhancement effects were observed in all 3 cases of autoimmune-related pancreatitis, but the degree varied. There was a significant correlation between the intensity of enhancement effects and the ratio of patent vessels in the tumors (P < .05).

CONCLUSIONS

Vascularity was detected by contrast-enhanced sonography in only about half of the ductal carcinomas, confirming the difficulty in distinguishing those tumors from other pancreatic tumors. There was a correlation between the patency of the vessels in the tumors and their vascularity.

The role of ultrasound in biliary and pancreatic diseases

The possibilities and the limits of transabdominal ultrasonography (US) in the diagnosis of bilio-pancreatic diseases are reviewed here in the light of the last 10 years' research. US remains the method of choice for the diagnosis of gallstones and is generally accepted as an initial imaging technique in gallstone complications, such as acute cholecystitis. Moreover the method can be useful for the detection of the biliary complications after laparoscopic cholecystectomy and after liver transplantation. US is still considered the first diagnostic procedure when stones are suspected in the common bile duct. The use of color Doppler can provide a differential diagnosis of gallbladder cancer with respect to other benign inflammatory or polypoid lesions. Color Doppler US allows to detect vascular complications of acute pancreatitis such as pseudoaneurysms. US is still considered useful for the initial screening of the pancreatic cancer. However, for staging other imaging techniques must be employed. With US useful informations are obtained in the diagnosis of cystic tumors of the pancreas and of pancreatic metastases. US is generally of little use for the diagnosis of endocrine tumors.