Magnetic resonance imaging of the cirrhotic liver in the eraof gadoxetic acid

Gadoxetic acid improves detection and characterization of focal liver lesions in cirrhotic patients and can estimate liver function in patients undergoing liver resection.The purpose of this article is to describe the optimal gadoxetic acid study protocol for the liver,the unique characteristics of gadoxetic acid,the differences between gadoxetic acid and extra-cellular gadolium chelates,and the differences in phases of enhancement between cirrhotic and normal liver using gadoxetic acid.We also discuss how to obtain and recognize an adequate hepatobiliary phase.

New advances in radiomics of gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are uncommon neoplasms of the gastrointestinal tract with peculiar clinical,genetic,and imaging characteristics.Preoperative knowledge of risk stratification and mutational status is crucial to guide the appropriate patients’treatment.Predicting the clinical behavior and biological aggressiveness of GISTs based on conventional computed tomography(CT)and magnetic resonance imaging(MRI)evaluation is challenging,unless the lesions have already metastasized at the time of diagnosis.Radiomics is emerging as a promising tool for the quantification of lesion heterogeneity on radiological images,extracting additional data that cannot be assessed by visual analysis.Radiomics applications have been explored for the differential diagnosis of GISTs from other gastrointestinal neoplasms,risk stratification and prediction of prognosis after surgical resection,and evaluation of mutational status in GISTs.The published researches on GISTs radiomics have obtained excellent performance of derived radiomics models on CT and MRI.However,lack of standardization and differences in study methodology challenge the application of radiomics in clinical practice.The purpose of this review is to describe the new advances of radiomics applied to CT and MRI for the evaluation of gastrointestinal stromal tumors,discuss the potential clinical applications that may impact patients’management,report limitations of current radiomics studies,and future directions.

Value of serial magnetic resonance imaging in the assessment of brain metastases volume control during stereotactic radiosurgery

AIM To evaluate brain metastases volume control capabilities of stereotactic radiosurgery(SRS) through serial magnetic resonance(MR) imaging follow-up. METHODS MR examinations of 54 brain metastases in 31 patients before and after SRS were reviewed. Patients were included in this study if they had a pre-treatment MR examination and serial follow-up MR examinations at 6 wk, 9 wk, 12 wk, and 12 mo after SRS. The metastasis volume change was categorized at each follow-up as increased(> 20% of the initial volume), stable(± 20% of the initial volume) or decreased(< 20% of the initial volume). RESULTS A local tumor control with a significant(P < 0.05) volume decrease was observed in 25 metastases at 6-wk follow-up. Not significant volume change was observed in 23 metastases and a significant volume increase was observed in 6 metastases. At 9-wk followup, 15 out of 25 metastases that decreased in size at 6 wk had a transient tumor volume increase, followed by tumor regression at 12 wk. At 12-wk follow-up there was a significant reduction in volume in 45 metastases, and a significant volume increase in 4 metastases. At 12-mo follow-up, 19 metastases increased significantly in size(up to 41% of the initial volume). Volume tumor reduction was correlated to histopathologic subtype.CONCLUSION SRS provided an effective local brain metastases volume control that was demonstrated at follow-up MR imaging.

Loco-regional treatment of hepatocellular carcinoma:Role of contrast-enhanced ultrasonography

Hepatocellular carcinoma(HCC)is one of the few cancers for which locoregional treatments(LRTs)are included in international guidelines and are considered as a valid alternative to conventional surgery.According to Barcelona Clinic Liver Cancer classification,percutaneous treatments such as percutaneous ethanol injection,radiofrequency ablation and microwave ablation are the therapy of choice among curative treatments in patients categorized as very early and early stage,while transcatheter arterial chemoembolization is considered the better option for intermediate stage HCC.A precise assessment of treatment efficacy and surveillance is essential to optimize survival rate,whereas residual tumor requires additional treatment.Imaging modalities play a key role in this task.Currently,contrast-enhanced computed tomography/magnetic resonance imaging are considered the standard imaging modalities for this purpose.Contrast enhanced ultrasound(CEUS),using second generation contrast agents,plays an increasingly important role in detecting residual disease after LRTs.CEUS is a straightforward to perform,repeatable and cost-effective imaging modality for patients with renal failure or iodine allergies.Due to the ability to focus on single regions,CEUS can also provide high temporal resolution.Moreover,several studies have reported the same or better diagnostic accuracy as contrast-enhanced computed tomography for assessing tumor vascularity 1 mo after LRTs,and recently three-dimensional(3D)-CEUS has been reported as a promising technique to improve the evaluation of tumor response to therapy.Furthermore,CEUS could be used early after procedures in monitoring HCC treatments,but nowadays this indication is still debated,and data from literature are conflicting,especially after transcatheter arterial chemoembolization procedure.

New frontiers in liver ultrasound:From mono to multi parametricity

Modern liver ultrasonography(US)has become a“one-stop shop”able to provide not only anatomic and morphologic but also functional information about vascularity,stiffness and other various liver tissue properties.Modern US techniques allow a quantitative assessment of various liver diseases.US scanning is no more limited to the visualized plane,but three-dimensional,volumetric acquisition and consequent post-processing are also possible.Further,US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations.Effective and safe microbubble�based contrast agents allow a real time,dynamic study of contrast kinetic for the detection and characterization of focal liver lesions.Ultrasound can be used to guide loco-regional treatment of liver malignancies and to assess tumoral response either to interventional procedures or medical therapies.Microbubbles may also carry and deliver drugs under ultrasound exposure.US plays a crucial role in diagnosing,treating and monitoring focal and diffuse liver disease.On the basis of personal experience and literature data,this paper is aimed to review the main topics involving recent advances in the field of liver ultrasound.

Focal liver lesions in cirrhosis:Role of contrast-enhanced ultrasonography

Contrast-enhanced ultrasound(CEUS)represents a great innovation for the evaluation of focal liver lesions(FLLs).The main advantage of CEUS is the realtime imaging examination and the very low toxicity in patients with renal failure.Liver cirrhosis has been recognized as a major risk factor for the onset of hepatocellular carcinoma(HCC)and intrahepatic cholangiocarcinoma(ICC).HCC in liver cirrhosis develops as the last step of a complex that leads to the gradual transformation from regenerative nodule through dysplastic nodule to HCC.In patients with liver cirrhosis,a surveillance program is recommended consisting of ultrasound(US)for detecting small focal lesions.A wide spectrum of benign and malignant lesions other than HCC may be found in the cirrhotic liver and their differentiation is important to avoid errors in staging diseases that may preclude potentially curative therapies.Several published studies have explored the value of CEUS in liver cirrhosis and they have been shown to have excellent diagnostic and prognostic performances for the evaluation of non-invasive and efficient diagnosis of FLLs in patients at high risk for liver malignancies.The purpose of this article is to describe and discuss CEUS imaging findings of FLLs including HCC and ICC,all of which occur in cirrhotic livers with varying prevalence.

Breast dynamic contrast-enhanced-magnetic resonance imaging and radiomics:State of art

Breast cancer represents the most common malignancy in women,being one of the most frequent cause of cancer-related mortality.Ultrasound,mammography,and magnetic resonance imaging(MRI)play a pivotal role in the diagnosis of breast lesions,with different levels of accuracy.Particularly,dynamic contrastenhanced MRI has shown high diagnostic value in detecting multifocal,multicentric,or contralateral breast cancers.Radiomics is emerging as a promising tool for quantitative tumor evaluation,allowing the extraction of additional quantitative data from radiological imaging acquired with different modalities.Radiomics analysis may provide novel information through the quantification of lesions heterogeneity,that may be relevant in clinical practice for the characterization of breast lesions,prediction of tumor response to systemic therapies and evaluation of prognosis in patients with breast cancers.Several published studies have explored the value of radiomics with good-to-excellent diagnostic and prognostic performances for the evaluation of breast lesions.Particularly,the integrations of radiomics data with other clinical and histopathological parameters have demonstrated to improve the prediction of tumor aggressiveness with high accuracy and provided precise models that will help to guide clinical decisions and patients management.The purpose of this article in to describe the current application of radiomics in breast dynamic contrast-enhanced MRI.