MR arthrography of the shoulder: evaluation of isotropic 3D intermediate-weighted FSE and hybrid GRE T1-weighted sequences.

PURPOSE: To compare the diagnostic accuracy of three-dimensional (3D) fast spin echo (FSE) intermediate-weighed (IW-3D) and 3D hybrid double-echo steady-state T1-weighted sequences (Hy-3D) and two-dimensional (FSE) images (2D) at shoulder MR arthrography (MRA). MATERIALS AND METHODS: Institutional review board approval was obtained and informed consent was waived for this retrospective study. From September 2011 to October 2014, 102 patients who had undergone 1.5 Tesla MRA of the shoulder, including conventional 2D-FSE and IW-3D and Hy-3D images were included in our study. The mean interval between MRA and surgery was 21 days (range 2-70 days). MR images were retrospectively and independently reviewed by two experienced radiologists blinded to the clinical and surgical data. Supraspinatus tendon (SST), infraspinatus tendon (IST) and subscapularis tendon (SCT) tears, as well as antero-inferior, superior and posterior labral lesions were assessed, using surgery as the reference standard. Each reader's performance in assessing rotator cuff and labrum abnormalities was evaluated using the area under the receiver operating characteristic curve (AUC) and 95% confidence intervals (CIs). The difference was evaluated using a univariate z test. The sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and accuracy (Acc) for all types of rotator cuff tears and labral lesions were calculated. A value of p < 0.05 was considered statistically significant. Inter-observer agreement was calculated using kappa statistics. RESULTS: The difference of diagnostic accuracy achieved was not significant (p > 0.05). In particular, differences in AUC values ranged from 0.002 (p = 0.98) to 0.014 (p = 0.82) as regards the comparison between 2D and IW-3D images, from 0.002 (p = 0.98) to 0.034 (p = 0.08) concerning the comparison between 2D and Hy-3D images and from 0.010 (p = 0.82) to 0.032 (p = 0.09) when comparing Hy-3D to IW-3D images. Accuracy values in evaluating RC lesions and labral lesions were 95.1, 92.1, 91.2, 93.1, 93.1 and 94.1% by reading 2D, Hy-3D and IW-3D images, respectively. The difference of diagnostic accuracy achieved using the datasets analyzed was not significant (p > 0.05). Inter-observer agreement was very good for each of the datasets that were evaluated, with near-perfect agreement for 2D dataset (k = 0.86), Hy-3D (k = 0.81) and IW-3D (k = 0.83). CONCLUSIONS: The accuracy of IW-3D and Hy-3D images was not significantly higher than the 2D sequences in evaluating RC and labral lesions.

Acoustic radiation force impulse with shear wave speed quantification of pancreatic masses: A prospective study.

BACKGROUND: Acoustic Radiation Force Impulse (ARFI) is a new ultrasound technique that evaluates mechanical properties of tissues. To evaluate the use of ARFI with shear waves speed quantification for pancreatic masses characterization during the ultrasound examination. METHODS: 123 pancreatic lesions were prospectively evaluated. Median shear waves speeds were compared with Mann-Whitney U test. Two reading methods were applied for the characterization of adenocarcinoma: more than one measurement above the top shear waves speed (SWS) value. Two reading methods were applied to diagnose mucinous lesion: at least 2 (method 1) or 3 (method 2) numerical measurements. Sensitivity, specificity, positive and negative predictive values and accuracy of each reading method were calculated. Forty volunteers were included for normal ARFI values. RESULTS: In the adenocarcinoma group median SWS value was 2.74 m/s. In the volunteers group the median SWS value was 1.17 m/s. Significant difference between SWS median values of adenocarcinoma and normal pancreas was found (P < 0.05). For the diagnosis of pancreatic solid masses if more than one measurement is above the top SWS value of 4.00 m/s results in the study, the diagnosis of ductal adenocarcinoma is highly specific with specificity and PPV of 100%. Good sensitivity (73.3%) and specificity (83.3%) were obtained for the characterization of mucinous cystic lesions. CONCLUSIONS: Acoustic Radiation Force Impulse imaging could help in the non-invasive characterization of solid and cystic lesions of the pancreas during a conventional US examination.

A rare case of incidental pancreatic arteriovenous malformation correctly diagnosed with MDCT.

CONTEXT: Pancreatic arteriovenous malformations are a rare entity that can be incidentally discovered during MDCT examinations. CASE REPORT: We describe a rare case of asymptomatic arteriovenous malformation presenting at MDCT as a hypervascular mass in the pancreatic head. CONCLUSION: Pancreatic arteriovenous malformations are a rare entity, often asymptomatic, that can be correctly diagnosed by MDCT, especially with the use of specific electronic reconstructions.

Virtual analysis of pancreatic cystic lesion fluid content by ultrasound acoustic radiation force impulse quantification.

OBJECTIVES: The purpose of this study was to prospectively evaluate the application of acoustic radiation force impulse (ARFI) imaging implemented with Virtual Touch tissue quantification (Siemens AG, Erlangen, Germany) in the study of pancreatic cystic lesions by using different analysis methods compared with the final diagnosis (pathologic or by magnetic resonance imaging and endoscopic sonographic findings). METHODS: Thirty-eight patients with pancreatic cystic focal lesions (diameter >3 cm and located at a depth of 5.5 cm) were included in the study and underwent conventional sonography. For every patient, 5 measurements in the Virtual Touch tissue quantification region of interest were obtained. To distinguish mucinous (potentially malignant) from serous (mainly benign) cystic lesions, the result XXXX/0 was considered to mean simple liquids (comparable to water), and the accuracy of Virtual Touch tissue quantification in differentiating pancreatic cystic lesions was calculated. To consider a lesion as containing complex fluids (potentially mucinous), two different reading methods were applied: (1) at least 2 numerical values when obtaining 5 measurements; and (2) the prevalence of numerical values irrespective of the number of measurements. The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for the differential diagnosis between mucinous and nonmucinous cystic lesions. RESULTS: By the first reading method, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the group of cystic lesions were 68.8%, 77.3%, 68.8%, 77.3%, and 73.7%, respectively; by the second method, the values were 37.5%, 100%, 100%, 68.8%, and 73.3%. CONCLUSIONS: Acoustic radiation force impulse imaging with Virtual Touch tissue quantification can have a role in the noninvasive characterization of pancreatic cystic lesions during conventional sonographic examinations.

Pancreatic mucinous cystoadenomas and cystoadenocarcinomas: differential diagnosis by means of MRI.

OBJECTIVE: To determine the accuracy of MRI in differentiating mucinous cystoadenomas (MCAs) from mucinous cystoadenocarcinomas (MCACs) of the pancreas, with histopathological analysis as the reference standard, for better surgical planning. METHODS: A total of 65 patients with histopathologically proven mucinous cystic neoplasms (MCNs) underwent MRI and surgery. Quantitative image analysis included size, septa and wall thickness and number of loculations. Qualitative image analysis included nodules; hyperintensity of the cystic content on T1 weighted images; compression and/or infiltration of adjacent vessels or organs; and metastases. A comparison between MCAs and MCACs was performed with Student's t-test for quantitative variables and with Fisher test for qualitative variables. Receiver operating characteristic analysis was performed to determine the accuracy in the differential diagnosis between MCAs and MCACs on the basis of a score system obtained by giving 1 point for each quantitative and qualitative variable observed in each patient. RESULTS: At histopathology, 43 lesions were MCAs and 22 lesions were MCACs. A statistically significant difference was observed for size >7cm (<0.001), septa and wall thickness >3 mm (<0.0001), number of loculations >4 (<0.0001), nodules (<0.0001), hyperintensity of the cystic content on T1 weighted images (<0.0001), compression (<0.01) and/or infiltration (<0.01) of adjacent vessels or organs and metastases (<0.05). The best cut-off value to discriminate MCAs from MCACs was the presence of three features (p < 0.001), with an accuracy of 91%. CONCLUSION: MRI has an accuracy of 91% in the differential diagnosis between MCA and MCAC, helping in identifying forms that could undergo parenchyma-sparing surgery (MCAs), reducing post-surgical morbidity and mortality. ADVANCES IN KNOWLEDGE: In this study, the differentiation between MCAs and MCACs of the pancreas by means of MRI is addressed. The differential diagnosis allows selecting benign forms, susceptible of parenchyma-sparing surgery, with the advantage of reducing post-surgical morbidity and stratifying prognosis of MCNs.

Oncocytic Intraductal Papillary Mucinous Neoplasms of the Pancreas: Imaging and Histopathological Findings.

OBJECTIVES: To evaluate and correlate computed tomography/magnetic resonance findings and histopathologic features of oncocytic intraductal papillary mucinous neoplasms (O-IPMNs). METHODS: Computed tomography/magnetic resonance examinations and resection specimens of 16 O-IPMNs were retrospectively reviewed. Qualitative and quantitative imaging features were analyzed according to "worrisome features" and "high risk stigmata." Correlations between radiological and histopathological findings were evaluated using Fisher test. RESULTS: Most O-IPMNs (75%) presented as large mixed- or main duct-type lesions (mean size, 56.9 mm; range, 20-180); all branch-duct type lesions were larger than 3 cm. Ten lesions presented main pancreatic duct dilation of 10 mm or greater. Solid enhancing nodules were found in 10 cases. Two lesions presented foci of invasion at histopathologic analysis, the remaining presented high-grade dysplasia. Neither invasive carcinoma nor nodal metastases were found. No significant correlations were found between radiological predictors of malignancy and histopathological features. CONCLUSIONS: Oncocytic tumors are rare subtypes of pancreatic IPMN, whose imaging features are similar to other IPMN subtypes. Imaging predictors of malignancy as large size and huge solid internal nodules are frequently encountered in O-IPMNs; despite this, these features are not correlated with histopathological findings, being probably inapplicable to O-IPMNs.

Diffusion-weighted imaging of pancreatic cancer.

Magnetic resonance imaging (MRI) is a reliable and accurate imaging method for the evaluation of patients with pancreatic ductal adenocarcinoma (PDAC). Diffusion-weighted imaging (DWI) is a relatively recent technological improvement that expanded MRI capabilities, having brought functional aspects into conventional morphologic MRI evaluation. DWI can depict the random diffusion of water molecules within tissues (the so-called Brownian motions). Modifications of water diffusion induced by different factors acting on the extracellular and intracellular spaces, as increased cell density, edema, fibrosis, or altered functionality of cell membranes, can be detected using this MR sequence. The intravoxel incoherent motion (IVIM) model is an advanced DWI technique that consent a separate quantitative evaluation of all the microscopic random motions that contribute to DWI, which are essentially represented by molecular diffusion and blood microcirculation (perfusion). Technological improvements have made possible the routine use of DWI during abdominal MRI study. Several authors have reported that the addition of DWI sequence can be of value for the evaluation of patients with PDAC, especially improving the staging; nevertheless, it is still unclear whether and how DWI could be helpful for identification, characterization, prognostic stratification and follow-up during treatment. The aim of this paper is to review up-to-date literature data regarding the applications of DWI and IVIM to PDACs.

CEUS of the pancreas: Still research or the standard of care.

Contrast-enhanced ultrasonography (CEUS) improves the characterization of pancreatic masses. CEUS is in fact a safe and accurate imaging method to evaluate the vascularity of pancreatic lesions. CEUS should be performed when possible immediately after the ultrasound (US) detection of a pancreatic mass. CEUS is accurate in the characterization of ductal adenocarcinoma. The use of CEUS in studying pancreatic lesions found at US, especially in the same session of ultrasound examination, is therefore recommendable to promote faster diagnosis mainly of pancreatic ductal adenocarcinoma.

Prognostication and response assessment in liver and pancreatic tumors: The new imaging.

Diffusion-weighted imaging (DWI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and perfusion computed tomography (CT) are technical improvements of morphologic imaging that can evaluate functional properties of hepato-bilio-pancreatic tumors during conventional MRI or CT examinations. Nevertheless, the term "functional imaging" is commonly used to describe molecular imaging techniques, as positron emission tomography (PET) CT/MRI, which still represent the most widely used methods for the evaluation of functional properties of solid neoplasms; unlike PET or single photon emission computed tomography, functional imaging techniques applied to conventional MRI/CT examinations do not require the administration of radiolabeled drugs or specific equipments. Moreover, DWI and DCE-MRI can be performed during the same session, thus providing a comprehensive "one-step" morphological and functional evaluation of hepato-bilio-pancreatic tumors. Literature data reveal that functional imaging techniques could be proposed for the evaluation of these tumors before treatment, given that they may improve staging and predict prognosis or clinical outcome. Microscopic changes within neoplastic tissues induced by treatments can be detected and quantified with functional imaging, therefore these techniques could be used also for post-treatment assessment, even at an early stage. The aim of this editorial is to describe possible applications of new functional imaging techniques apart from molecular imaging to hepatic and pancreatic tumors through a review of up-to-date literature data, with a particular emphasis on pathological correlations, prognostic stratification and post-treatment monitoring.

Liver volumetry: Is imaging reliable? Personal experience and review of the literature.

The amount of the future liver remnant volume is fundamental for hepato-biliary surgery, representing an important potential risk-factor for the development of post-hepatectomy liver failure. Despite this, there is no uniform consensus about the amount of hepatic parenchyma that can be safely resected, nor about the modality that should be chosen for this evaluation. The pre-operative evaluation of hepatic volume, along with a precise identification of vascular and biliar anatomy and variants, are therefore necessary to reduce surgical complications, especially for extensive resections. Some studies have tried to validate imaging methods [ultrasound, computed tomography (CT), magnetic resonance imaging] for the assessment of liver volume, but there is no clear evidence about the most accurate method for this evaluation. Furthermore, this volumetric evaluation seems to have a certain degree of error, tending to overestimate the actual hepatic volume, therefore some conversion factors, which should give a more reliable evaluation of liver volume, have been proposed. It is widespread among non-radiologists the use of independent software for an off-site volumetric analysis, performed on digital imaging and communications in medicine images with their own personal computer, but very few studies have provided a validation of these methods. Moreover, while the pre-transplantation volumetric assessment is fundamental, it remains unclear whether it should be routinely performed in all patients undergoing liver resection. In this editorial the role of imaging in the estimation of liver volume is discussed, providing a review of the most recent literature and a brief personal series of correlations between liver volumes and resection specimens' weight, in order to assess the precision of the volumetric CT evaluation.

Elastography of the pancreas.

Elastography has recently been presented in clinical studies as a new technique applied to US imaging. The challenge of this new technique is to distinguish different tissues on the basis of their specific consistency. Since malignant tumors tend to be harder than benign lesions and parenchyma, this new approach could result clinically relevant. Initial clinical experiences in US elastography have been promising in differentiating breast, thyroid and prostate nodules. Pancreatic applications of US elastography are relatively recent and under validation with several studies so far published in literature.

Noninvasive diagnosis of cirrhosis: a review of different imaging modalities.

Progressive hepatic fibrosis can lead to cirrhosis, so its early detection is fundamental. Staging fibrosis is also critical for prognosis and management. The gold standard for these aims is liver biopsy, but it has several drawbacks, as it is invasive, expensive, has poor acceptance, is prone to inter observer variability and sampling errors, has poor repeatability, and has a risk of complications and mortality. Therefore, non-invasive imaging tests have been developed. This review mainly focuses on the role of transient elastography, acoustic radiation force impulse imaging, and magnetic resonance-based methods for the noninvasive diagnosis of cirrhosis.

Autoimmune pancreatitis: Multimodality non-invasive imaging diagnosis.

Autoimmune pancreatitis (AIP) is characterized by obstructive jaundice, a dramatic clinical response to steroids and pathologically by a lymphoplasmacytic infiltrate, with or without a pancreatic mass. Type 1 AIP is the pancreatic manifestation of an IgG4-related systemic disease and is characterized by elevated IgG4 serum levels, infiltration of IgG4-positive plasma cells and extrapancreatic lesions. Type 2 AIP usually has none or very few IgG4-positive plasma cells, no serum IgG4 elevation and appears to be a pancreas-specific disorder without extrapancreatic involvement. AIP is diagnosed in approximately 2%-6% of patients that undergo pancreatic resection for suspected pancreatic cancer. There are three patterns of autoimmune pancreatitis: diffuse disease is the most common type, with a diffuse, "sausage-like" pancreatic enlargement with sharp margins and loss of the lobular contours; focal disease is less common and manifests as a focal mass, often within the pancreatic head, mimicking a pancreatic malignancy. Multifocal involvement can also occur. In this paper we describe the features of AIP at ultrasonography, computed tomography, magnetic resonance and positron emission tomography/computed tomography imaging, focusing on diagnosis and differential diagnosis with pancreatic ductal adenocarcinoma. It is of utmost importance to make an early correct differential diagnosis between these two diseases in order to identify the optimal therapeutic strategy and to avoid unnecessary laparotomy or pancreatic resection in AIP patients. Non-invasive imaging plays also an important role in therapy monitoring, in follow-up and in early identification of disease recurrence.

Acoustic radiation force impulse of the liver.

Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualitative or quantitative (wave velocity values) responses. Several non-invasive methods for assessing the staging of fibrosis are used, in order to avoid liver biopsy. Liver function tests and transient elastography are non-invasive, sensitive and accurate tools for the assessment of liver fibrosis and for the discrimination between cirrhotic and non-cirrhotic liver. Many published studies analyse ARFI performance and feasibility in studying diffuse liver diseases and compare them to other diagnostic imaging modalities such as conventional ultrasonography and transient elastography. Solid focal liver lesions, both benign and malignant, are common findings during abdominal examinations. The accurate characterization and differential diagnosis are important aims of all the imaging modalities available today. Only few papers describe the application of ARFI technology in the study of solid focal liver lesions, with different results. In the present study, the existing literature, to the best of our knowledge, about ARFI application on diffuse and focal liver pathology has been evaluated and results and statistical analyses have been compared, bringing to the conclusion that ARFI can be used in the study of the liver with similar accuracy as transient elastography in diagnosing significant fibrosis or cirrhosis and has got some advantages in respect to transient elastography since it does not require separate equipment, better displays anatomical structures and measurements can be successfully carried out almost in every patient.