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

Transabdominal Ultrasound for Follow-Up of Incidentally Detected Low-Risk Pancreatic Cysts: A Prospective Multicenter Study

OBJECTIVE. The purpose of this study is to investigate the detection rate of transabdominal ultrasound (TAUS) for pancreatic cysts incidentally detected on CT or MRI as well as the factors that influence detection rates. SUBJECTS AND METHODS. Fifty-seven patients with low-risk pancreatic cysts (n = 77; cyst size, 5 mm to 3 cm) that were incidentally detected on CT or MRI were prospectively enrolled at five institutions. At each institution, TAUS was independently performed by two radiologists who assessed detection of cysts, cyst location and size, and the diameter of the main pancreatic duct (MPD). Cyst detection rates based on cyst size, location, and multiplicity and the body mass index of the patient were compared using the Mann-Whitney test. Kappa statistics and the interclass correlation coefficient were used to evaluate interobserver agreement regarding cyst detection and consistency of cyst size and the diameter of the MPD on TAUS versus prior CT or MRI. RESULTS. The detection rate for known low-risk pancreatic cysts was 81.8% (63/77) and 83.1% (64/77) for TAUS conducted by each of the two radiologists. The detection rate for larger (≥ 10 mm) cysts was significantly higher than that for smaller cysts (89.0% vs 63.6% for TAUS performed and interpreted by radiologist 1 [TAUS 1] and 89.0% vs 68.2% for TAUS conducted and interpreted by radiologist 2 [TAUS 2]; p < .05). A higher detection rate was noted for cysts located outside the tail of the pancreas compared with those located in the tail (89.5% vs 65.0% for TAUS 2; p = .01), and the detection rate was also significantly higher for single cysts than for multiple cysts (90.9% vs 69.7% for TAUS 1; p = .02). However, no significant difference was observed for body mass index. Interobserver agreement was excellent regarding the size of the detected cysts (inter-class correlation coefficient: 0.964 [95% CI, 0.940-0.979] for CT, TAUS 1, and TAUS 2 and 0.965 [95% CI. 0.924-986] for MRI, TAUS 1, and TAUS 2) and the diameter of the MPD (interclass correlation coefficient, 0.934; 95% CI, 0.898-0.959). CONCLUSION. TAUS could be a useful alternative imaging tool for surveillance of known low-risk pancreatic cysts, especially single pancreatic cysts and those that are of larger size (≥ 1 cm) or are located outside the tail.

Comparison between B-mode ultrasonography and contrast-enhanced ultrasonography for the surveillance of early stage pancreatic cancer: a retrospective study

Background

Contrast-enhanced ultrasonography (CE-US) brings a higher signal-to-noise ratio and a higher sensitivity for slow flow than traditional B-mode ultrasonography (US). However, it remains unclear whether CE-US is also superior to B-mode US in detecting early-stage pancreatic cancer (PC).

Methods

This was a retrospective study enrolling patients suspected of pancreatic insufficiency between June 2015 and December 2019. Enrolled patients successively received B-mode US and CE-US examinations, and some their demographic and clinical data were collected. The diagnostic capacity of the two examinations was calculated and receiver operating characteristic (ROC) curves was used to compare the area under the curve (AUC). A subgroup analysis was performed to explore the effects of tumor size on the diagnostic accuracy of B-mode US and CE-US.

Results

There were 128 patients enrolled in this study; 74 patients were diagnosed as early-stage PC patients and the remaining 54 were diagnosed with benign pancreatic lesions. The mean size of the PC was 17.8±4.9 mm. The results revealed that 68 of the 74 PC patients were correctly diagnosed by CE-US, and all 54 patients with benign pancreatic lesions were also correctly diagnosed. Meanwhile, only 55 of the 74 PC patients and 50 of the 54 patients with benign pancreatic lesions were diagnosed correctly using B-mode US. The ROC curve showed that the AUCs of CE-US and B-mode US were 0.959 and 0.835, respectively. According to the subgroup analysis, CE-US exhibited better accuracy than B-mode US for smaller tumors (size <20 mm, P=0.002; size <10 mm, P=0.043; size <5 mm, P=0.025).

Conclusions

CE-US was clearly superior to the conventional B-mode US in detecting early-stage PC, especially smaller sized PC.

Clinical application of dynamic contrast enhanced ultrasound in monitoring the treatment response of chemoradiotherapy of pancreatic ductal adenocarcinoma

OBJECTIVES

To investigate the value of dynamic contrast enhanced ultrasound (D-CEUS) in monitoring the chemoradiotherapy (CRT) therapeutic response of local advanced pancreatic ductal adenocarcinoma (LAPC).

PATIENTS AND METHODS

From October 2017 to December 2018, 11 patients diagnosed as LAPC were included (7 men, 4 women; mean age: 61.1±8.6 years). The algorithm of CRT was as following: the radiotherapy dose was 50.4 Gy/28Fx with S-1 40 mg bid orally taken in radiotherapy day. Conventional ultrasound scan and CEUS were performed before and 4 weeks after CRT. All ultrasound examinations were performed by an ACUSON Oxana 2 ultrasound equipment (Siemens Medical Solutions, Germany) with a C 6-1 convex array transducer (1-6 MHz). Time intensity curves (TICs) were generated in the region of interests (ROIs) both in LAPC lesions and in its surrounding pancreas parenchyma by SonoLiver software (TOMTEC Imaging Systems). Quantitative perfusion parameters including maximum intensity (MI), rise time (RT), mean transit time (mTT) and time to peak (TTP) were analyzed and compared before and after CRT.

RESULTS

No significant difference could be found by conventional B mode ultrasound scan after CRT. TICs of CEUS showed lower ascending and descending slopes rate after CRT. Among all perfusion quantitative parameters, MI decreased significantly after CRT (42.1±18.8% vs 27.8±17.2%, P < 0.05).

CONCLUSIONS

Depending on its unique advantages as non-radiation, effective and convenient, D-CEUS analysis and quantitative parameters, particularly MI, has potential application value in following up of the CRT treatment response in LAPC patients.

Prevalence of Asymptomatic Intraductal Papillary Mucinous Neoplasms in Healthy and Ill Populations Detected by Ultrasonography: A Single-Center Study of 6353 Outpatients

OBJECTIVES

The aim of this study was to establish the prevalence of intraductal papillary mucinous neoplasms (IPMNs) without and with high-risk stigmata (HRS)/worrisome features (WF) and the epidemiologic association between IPMNs and other diseases.

METHODS

Ultrasound examinations of outpatients were evaluated. The IPMN was confirmed by magnetic resonance imaging. The prevalence of IPMNs and HRS/WF IPMNs was calculated. The association between IPMNs and other diseases was studied.

RESULTS

The prevalence rate of IPMNs was 3.4%. A total of 1,531,264 IPMNs were expected in Italian population (2.5%), whereas 2257 per 100,000 citizens (2.3%) were expected in the European standard population (ESP2013). The prevalence rates of HRS/WF IPMNs were 0.5%, 0.7%, and 0.6%, in our, the Italian, and the ESP2013 populations, respectively. A total of 432,881 and 620 HRS/WF IPMNs per 100,000 residents were expected in the Italian and the ESP2013 populations, respectively. The IPMN prevalence increased over 50 years of age (odds ratio [OR], 3.2; P < 0.001) and over 70 years of age (OR, 1.9; P < 0.001). Female sex was related to the presence of IPMNs (OR, 1.9; P < 0.001).

CONCLUSIONS

Intraductal papillary mucinous neoplasms had a high prevalence in asymptomatic nonhospitalized populations. Age older than 50 years identified a possible risk category.

Imaging modalities for characterising focal pancreatic lesions

BACKGROUND

Increasing numbers of incidental pancreatic lesions are being detected each year. Accurate characterisation of pancreatic lesions into benign, precancerous, and cancer masses is crucial in deciding whether to use treatment or surveillance. Distinguishing benign lesions from precancerous and cancerous lesions can prevent patients from undergoing unnecessary major surgery. Despite the importance of accurately classifying pancreatic lesions, there is no clear algorithm for management of focal pancreatic lesions.

OBJECTIVES

To determine and compare the diagnostic accuracy of various imaging modalities in detecting cancerous and precancerous lesions in people with focal pancreatic lesions.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Embase, and Science Citation Index until 19 July 2016. We searched the references of included studies to identify further studies. We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We planned to include studies reporting cross-sectional information on the index test (CT (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography), EUS (endoscopic ultrasound), EUS elastography, and EUS-guided biopsy or FNA (fine-needle aspiration)) and reference standard (confirmation of the nature of the lesion was obtained by histopathological examination of the entire lesion by surgical excision, or histopathological examination for confirmation of precancer or cancer by biopsy and clinical follow-up of at least six months in people with negative index tests) in people with pancreatic lesions irrespective of language or publication status or whether the data were collected prospectively or retrospectively.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the references to identify relevant studies and extracted the data. We planned to use the bivariate analysis to calculate the summary sensitivity and specificity with their 95% confidence intervals and the hierarchical summary receiver operating characteristic (HSROC) to compare the tests and assess heterogeneity, but used simpler models (such as univariate random-effects model and univariate fixed-effect model) for combining studies when appropriate because of the sparse data. We were unable to compare the diagnostic performance of the tests using formal statistical methods because of sparse data.

MAIN RESULTS

We included 54 studies involving a total of 3,196 participants evaluating the diagnostic accuracy of various index tests. In these 54 studies, eight different target conditions were identified with different final diagnoses constituting benign, precancerous, and cancerous lesions. None of the studies was of high methodological quality. None of the comparisons in which single studies were included was of sufficiently high methodological quality to warrant highlighting of the results. For differentiation of cancerous lesions from benign or precancerous lesions, we identified only one study per index test. The second analysis, of studies differentiating cancerous versus benign lesions, provided three tests in which meta-analysis could be performed. The sensitivities and specificities for diagnosing cancer were: EUS-FNA: sensitivity 0.79 (95% confidence interval (CI) 0.07 to 1.00), specificity 1.00 (95% CI 0.91 to 1.00); EUS: sensitivity 0.95 (95% CI 0.84 to 0.99), specificity 0.53 (95% CI 0.31 to 0.74); PET: sensitivity 0.92 (95% CI 0.80 to 0.97), specificity 0.65 (95% CI 0.39 to 0.84). The third analysis, of studies differentiating precancerous or cancerous lesions from benign lesions, only provided one test (EUS-FNA) in which meta-analysis was performed. EUS-FNA had moderate sensitivity for diagnosing precancerous or cancerous lesions (sensitivity 0.73 (95% CI 0.01 to 1.00) and high specificity 0.94 (95% CI 0.15 to 1.00), the extremely wide confidence intervals reflecting the heterogeneity between the studies). The fourth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (dysplasia) provided three tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing invasive carcinoma were: CT: sensitivity 0.72 (95% CI 0.50 to 0.87), specificity 0.92 (95% CI 0.81 to 0.97); EUS: sensitivity 0.78 (95% CI 0.44 to 0.94), specificity 0.91 (95% CI 0.61 to 0.98); EUS-FNA: sensitivity 0.66 (95% CI 0.03 to 0.99), specificity 0.92 (95% CI 0.73 to 0.98). The fifth analysis, of studies differentiating cancerous (high-grade dysplasia or invasive carcinoma) versus precancerous (low- or intermediate-grade dysplasia) provided six tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing cancer (high-grade dysplasia or invasive carcinoma) were: CT: sensitivity 0.87 (95% CI 0.00 to 1.00), specificity 0.96 (95% CI 0.00 to 1.00); EUS: sensitivity 0.86 (95% CI 0.74 to 0.92), specificity 0.91 (95% CI 0.83 to 0.96); EUS-FNA: sensitivity 0.47 (95% CI 0.24 to 0.70), specificity 0.91 (95% CI 0.32 to 1.00); EUS-FNA carcinoembryonic antigen 200 ng/mL: sensitivity 0.58 (95% CI 0.28 to 0.83), specificity 0.51 (95% CI 0.19 to 0.81); MRI: sensitivity 0.69 (95% CI 0.44 to 0.86), specificity 0.93 (95% CI 0.43 to 1.00); PET: sensitivity 0.90 (95% CI 0.79 to 0.96), specificity 0.94 (95% CI 0.81 to 0.99). The sixth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (low-grade dysplasia) provided no tests in which meta-analysis was performed. The seventh analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) provided two tests in which meta-analysis was performed. The sensitivity and specificity for diagnosing cancer were: CT: sensitivity 0.83 (95% CI 0.68 to 0.92), specificity 0.83 (95% CI 0.64 to 0.93) and MRI: sensitivity 0.80 (95% CI 0.58 to 0.92), specificity 0.81 (95% CI 0.53 to 0.95), respectively. The eighth analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) or benign lesions provided no test in which meta-analysis was performed.There were no major alterations in the subgroup analysis of cystic pancreatic focal lesions (42 studies; 2086 participants). None of the included studies evaluated EUS elastography or sequential testing.

AUTHORS' CONCLUSIONS

We were unable to arrive at any firm conclusions because of the differences in the way that study authors classified focal pancreatic lesions into cancerous, precancerous, and benign lesions; the inclusion of few studies with wide confidence intervals for each comparison; poor methodological quality in the studies; and heterogeneity in the estimates within comparisons.

Differential diagnosis between intraductal papillary mucinous neoplasm with an associated invasive carcinoma and pancreatic ductal adenocarcinoma on ultrasonography: the utility of echo intensity and contrast enhancement

Purpose

The aim of this study was to investigate the utility of echo intensity and contrast enhancement in the differential diagnosis between intraductal papillary mucinous neoplasm with an associated invasive carcinoma (IPMN-IC) and pancreatic ductal adenocarcinoma (PDAC) on ultrasonography.

Methods

This study included eight and 37 patients who had pathologically confirmed IPMN-IC and PDAC, respectively, and were enrolled for a comparative analysis of the sonographic features of the tumors. In the quantitative echo intensity evaluation, the two groups were compared with respect to the difference between the tumor intensity and the pancreatic intensity (TI-PI) and between the tumor intensity and the vascular intensity (TI-VI). In the quantitative contrast enhancement evaluation, the increase in echo intensity (ΔTI) and increase in echo intensity per unit of time (slope) were compared between the groups. The echo intensity and contrast enhancement were also compared between the two groups in patients with T3-T4 disease. In addition, the correlations of the histological type, tumor size, stromal type, and T factor with echogenicity and contrast enhancement were analyzed.

Results

IPMN-IC had significantly greater echo intensity and contrast enhancement than PDAC (TI-PI, P=0.004; TI-VI, P=0.001; ΔTI, P=0.012; slope, P=0.002). In T3-T4 disease, IPMN-IC also showed greater echo intensity and faster enhancement than PDAC. Echo intensity and contrast enhancement were correlated with histological type (TI-PI, P=0.003; TI-VI, P<0.001; ΔTI, P=0.007; slope, P<0.001).

Conclusion

IPMN-IC and PDAC can be differentiated by the quantitative evaluation of echo intensity and contrast enhancement.

Contrast-enhanced ultrasound of pancreatic tumours

Indication/purpose: To review contrast‐enhanced ultrasound features of the most common pancreatic tumours.

Methods: Contrast‐enhanced ultrasound (CEUS) can provide distinctive features of pancreatic tumours that are reported in the present paper, providing radiologic‐pathological correlations and clarifying the main differential diagnosis.

Conclusion: Contrast‐enhanced ultrasound plays a well‐established role in the evaluation of pancreatic tumours. When possible, CEUS should be always performed after the initial US diagnosis, in order to improve the accuracy of the first line examination.

Differential diagnosis of solid pancreatic lesions using contrast-enhanced three-dimensional ultrasonography

Purpose

To investigate the usefulness of contrast-enhanced three-dimensional ultrasonography (CE 3D US) for differential diagnosis of solid pancreatic lesions.

Methods

Eighty-five patients with solid pancreatic lesions who underwent CE 3D US were retrospectively analyzed. Sixty-four patients had pancreatic ductal adenocarcinoma (PDAC), 10 had mass-forming pancreatitis (MFP), and 11 had neuroendocrine tumor (NET). Two blinded readers evaluated the enhancement patterns using four features: vascularity in the arterial phase, vascularity in the venous phase, vessel location, and vessel form. Vascularity in both phases was classified as hypervascular, isovascular, or hypovascular. Vessel location was classified into peritumoral or intratumoral. Vessel form was classified into fine or irregular. Kappa values were used to assess inter-reader agreement. The institutional review board approved this study, and informed consent was obtained.

Results

Kappa values of the four features were 0.75, 0.72, 0.85, and 0.65, which were graded as good or excellent. The most typical combined enhancement pattern in PDAC was hypovascularity in both phases with peritumoral and irregular vessels; MFP was isovascular in both phases with intratumoral and fine vessels; and NETs were hypervascular in both phases with intratumoral and irregular vessels. The sensitivity and positive predictive value of the three patterns were 93.8% and 96.7% for the PDAC pattern, 80.0% and 100% for the MFP pattern, and 81.8%, and 69.2% for the NET pattern, respectively. The accuracy of these diagnostic criteria was 90.5%.

Conclusion

CE 3D US allows detailed visualization of the enhancement patterns of various pancreatic lesions and can be used for the differential diagnosis.

Is it safe to follow side branch IPMNs?

Management of Bd-IPMN remains challenging. Critical appraisal of the published literature reveals that the actual treatment of what is presumed to be Bd-IPMN remains unsatisfactory, with a high rate of surgically overtreated patients. Until we accrue more precise knowledge of the natural history of Bd-IPMN, management of patients with this presumed diagnosis should be individually tailored and preferably carried out in centers with a high expertise. For now, the authors strongly think that the old guidelines should be followed in most patients because these have proven to correctly identify lesions that can be safely followed. Although the new guidelines allow for follow-up of lesions greater than 3 cm, and for the most part this is safe, they should be used cautiously in younger patients because very close surveillance would be required for their long remaining lifespan.

Intraductal papillary mucinous neoplasms of the pancreas: evaluation of malignant potential and surgical resectability by using MR imaging with MR cholangiography

PURPOSE

To evaluate the diagnostic performance of magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP) in determining the malignant potential and surgical resectability of pancreas intraductal papillary mucinous neoplasms (IPMNs).

MATERIALS AND METHODS

Institutional review board approval was obtained, and the requirement for informed consent was waived. Ninety-eight patients with pathologically proved pancreas IPMNs who underwent MR imaging with MRCP comprised the study population. MR images were analyzed for findings suggestive of high-risk stigmata or worrisome features, as proposed by the international consensus guidelines 2012. Interobserver agreement between two experienced observers (observers 1 and 2) and one inexperienced observer (observer 3) was assessed. Diagnostic performance of MR imaging in the evaluation of the malignant potential and surgical resectability of IPMNs was analyzed in these three observers by using receiver operating curve analysis.

RESULTS

MR imaging with MRCP showed sensitivity of 83% (35/42), 79% (33/42), and 90% (38/42); specificity of 80% (41/51), 51% (26/51), and 24% (12/51); and accuracy of 82% (76/93), 63% (59/93), and 54% (50/93) for observers 1, 2, and 3, respectively, in the evaluation of the malignant potential of pancreas IPMNs when at least one worrisome feature was present. Interobserver agreement in the detection of intramural nodules (κ = 0.349-0.574), enhanced solid components (κ = 0.318-0.574), and measurement of main pancreatic duct diameter (intraclass correlation coefficient = 0.9477) was fair to high. The respective sensitivity, specificity, and accuracy in determination of surgical resectability were 95% (81/85), 99% (84/85), and 88% (75/85); 69% (9/13), 69% (9/13), and 54% (7/13); and 92% (90/98), 95% (93/98), and 84% (82/98) for observers 1, 2, and 3.

CONCLUSION

MR imaging with MRCP is a useful modality in the evaluation of the malignant potential and resectability of IPMNs, with high sensitivity and moderate specificity in the experienced radiologists but relatively low specificity in the inexperienced radiology trainee.

Endoscopic ultrasonography for surveillance of individuals at high risk for pancreatic cancer

Pancreatic cancer is a highly lethal disease with a genetic susceptibility and familial aggregation found in 3%-16% of patients. Early diagnosis remains the only hope for curative treatment and improvement of prognosis. This can be reached by the implementation of an intensive screening program, actually recommended for individuals at high-risk for pancreatic cancer development. The aim of this strategy is to identify pre-malignant precursors or asymptomatic pancreatic cancer lesions, curable by surgery. Endoscopic ultrasound (EUS) with or without fine needle aspiration (FNA) seems to be the most promising technique for early detection of pancreatic cancer. It has been described as a highly sensitive and accurate tool, especially for small and cystic lesions. Pancreatic intraepithelial neoplasia, a precursor lesion which is highly represented in high-risk individuals, seems to have characteristics chronic pancreatitis-like changes well detected by EUS. Many screening protocols have demonstrated high diagnostic yields for pancreatic pre-malignant lesions, allowing prophylactic pancreatectomies. However, it shows a high interobserver variety even among experienced endosonographers and a low sensitivity in case of chronic pancreatitis. Some new techniques such as contrast-enhanced harmonic EUS, computer-aided diagnostic techniques, confocal laser endomicroscopy miniprobe and the detection of DNA abnormalities or protein markers by FNA, promise improvement of the diagnostic yield of EUS. As the resolution of imaging improves and as our knowledge of precursor lesions grows, we believe that EUS could become the most suitable method to detect curable pancreatic neoplasms in correctly identified asymptomatic at-risk patients.