Current and Advanced Applications of Gadoxetic Acid-enhanced MRI in Hepatobiliary Disorders.

Gadoxetic acid is an MRI contrast agent that has specific applications in the study of hepatobiliary disease. After being distributed in the vascular and extravascular spaces during the dynamic phase, gadoxetic acid is progressively taken up by hepatocytes and excreted to the bile ducts during the hepatobiliary phase. The information derived from the enhancement characteristics during dynamic and hepatobiliary phases is particularly relevant in the detection and characterization of focal liver lesions and in the evaluation of the structure and function of the liver and biliary system. The use of new MRI sequences and advanced imaging techniques (eg, relaxometry, multiparametric imaging, and analysis of heterogeneity), the introduction of artificial intelligence, and the development of biomarkers and radiomic and radiogenomic tools based on gadoxetic acid-enhanced MRI findings will play an important role in the future in assessing liver function, chronic liver disease, and focal liver lesions; in studying biliary pathologic conditions; and in predicting treatment responses and prognosis. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Clinical impact of artificial intelligence-based solutions on imaging of the pancreas and liver.

Artificial intelligence (AI) has experienced substantial progress over the last ten years in many fields of application, including healthcare. In hepatology and pancreatology, major attention to date has been paid to its application to the assisted or even automated interpretation of radiological images, where AI can generate accurate and reproducible imaging diagnosis, reducing the physicians' workload. AI can provide automatic or semi-automatic segmentation and registration of the liver and pancreatic glands and lesions. Furthermore, using radiomics, AI can introduce new quantitative information which is not visible to the human eye to radiological reports. AI has been applied in the detection and characterization of focal lesions and diffuse diseases of the liver and pancreas, such as neoplasms, chronic hepatic disease, or acute or chronic pancreatitis, among others. These solutions have been applied to different imaging techniques commonly used to diagnose liver and pancreatic diseases, such as ultrasound, endoscopic ultrasonography, computerized tomography (CT), magnetic resonance imaging, and positron emission tomography/CT. However, AI is also applied in this context to many other relevant steps involved in a comprehensive clinical scenario to manage a gastroenterological patient. AI can also be applied to choose the most convenient test prescription, to improve image quality or accelerate its acquisition, and to predict patient prognosis and treatment response. In this review, we summarize the current evidence on the application of AI to hepatic and pancreatic radiology, not only in regard to the interpretation of images, but also to all the steps involved in the radiological workflow in a broader sense. Lastly, we discuss the challenges and future directions of the clinical application of AI methods.

Multiparametric MR Imaging in Abdominal Malignancies.

Modern MR imaging protocols can yield both anatomic and functional information for the assessment of hepatobiliary and pancreatic malignancies. Diffusion-weighted imaging is fully integrated into state-of-the-art protocols for tumor detection, characterization, and therapy monitoring. Hepatobiliary contrast agents have gained ground in the evaluation of focal liver lesions during the last years. Perfusion MR imaging is expected to have a central role for monitoring therapy in body tumors treated with antivascular drugs. Approaches such as Magnetic resonance (MR) elastography and (1)H-MR spectroscopy are still confined to research centers, but with the potential to grow in a short time frame.

[Total body MRI in early detection of bone metastasis and its indication in comparison to bone scan and other imaging techniques]. / RM de cuerpo entero en la detección precoz de las metástasis óseas y su indicación frente a la gammagrafia ósea y otras técnicas de imagen.

Bone metastases are a recognized prognostic factor in patients with prostate cancer. Currently, Tc99 bone scan is the most frequently used imaging technique for their detection, showing a high sensitivity but a limited specificity. Thus, new morphological and mainly functional imaging techniques based on PET and MRI, or hybrid techniques such as PET-CT or PET-MRI have been introduced to improve metastases detection, estimation of total tumor load and for therapeutic monitoring. In this clinical scenario, total body MRI has arisen as a very promising technique in detection and therapeutic monitoring of bone metastases of prostate cancer, because it neither uses ionizing radiation nor needs the administration of contrast media. The incorporation of MR diffusion to the morphologic total body MRI protocols provides functional information, improving the sensitivity in oncological lesions detection in general and osteolytic bone metastases of PCa in particular. Its integration in protocols with morphological sequences and its quantification through ADC maps enables us to better understand metastatic bone disease patterns and their changes with different therapies. Total body D MRI enables the early classification of the response to treatment with evident advantages over other imaging techniques and the purely morphological approach with MRI. In any case, prospective and cost-effectiveness studies are necessary to establish the role of total-body D MRI in the management of patients with PCa.

RM de cuerpo entero en la detección precoz de las metástasis óseas y su indicación frente a la gammagrafia ósea y otras técnicas de imagen / Total body MRI in early detection of bone metastasis and its indication in comparison to bone scan and other imaging techniques

Las metástasis óseas son un factor pronóstico reconocido en los pacientes con CaP. Actualmente, la GO con Tc99 es la técnica de imagen más utilizada para su detección, demostrando una elevada sensibilidad pero una especificidad limitada. Por ello, se han introducido nuevas técnicas de imagen morfológicas y principalmente funcionales basadas en la PET y la RM, o técnicas híbridas como la PET-TC o PET-RM, para mejorar la detección de las metástasis, la estimación de la carga tumoral total y la monitorización terapéutica. En este escenario clínico, la RM-CC ha surgido como una técnica muy prometedora en la detección y monitorización terapéutica de las metástasis óseas del CaP, ya que no utiliza radiación ionizante ni necesita de la administración de contraste. La incorporación de la difusión con RM a los protocolos morfológicos de RM-CC aporta información funcional, mejorando la sensibilidad en la detección de lesiones oncológicas en general y de las metástasis óseas osteolíticas del CaP en particular. Su integración en protocolos con secuencias morfológicas y su cuantificación mediante mapas ADC permite comprender mejor los patrones de enfermedad metastásica ósea y sus cambios con las diferentes terapias. La RM-CC-D permite evaluar de forma temprana la respuesta a tratamiento con ventajas evidentes sobre otras técnicas de imagen y a la aproximación puramente morfológica con RM. De cualquier forma, son necesarios todavía estudios prospectivos y de coste-efectividad para establecer el papel de la RM-CC-D en el manejo de los pacientes con CaP

Bone metastases are a recognized prognostic factor in patients with prostate cancer. Currently, Tc99 bone scan is the most frequently used imaging technique for their detection, showing a high sensitivity but a limited specificity. Thus, new morphological and mainly functional imaging techniques based on PET and MRI, or hybrid techniques such as PET-CT or PET-MRI have been introduced to improve metastases detection, estimation of total tumor load and for therapeutic monitoring. In this clinical scenario, total body MRI has arisen as a very promising technique in detection and therapeutic monitoring of bone metastases of prostate cancer, because it neither uses ionizing radiation nor needs the administration of contrast media. The incorporation of MR diffusion to the morphologic total body MRI protocols provides functional information, improving the sensitivity in oncological lesions detection in general and osteolytic bone metastases of PCa in particular. Its integration in protocols with morphological sequences and its quantification through ADC maps enables us to better understand metastatic bone disease patterns and their changes with different therapies. Total body D MRI enables the early classification of the response to treatment with evident advantages over other imaging techniques and the purely morphological approach with MRI. In any case, prospective and cost-effectiveness studies are necessary to establish the role of total-body D MRI in the management of patients with PCa