Seminars in Ultrasound Ct and Mri最新文献

Primary central nervous system lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin's lymphoma that accounts for 1%-5% of all central nervous system tumors. Contrast-enhanced MR is the imaging technique of choice. PCNLs have a predilection for the periventricular and superficial regions, often abutting the ventricular or meningeal surfaces. Although PCNLs may have characteristic imaging features on conventional MRI, none of these will unequivocally differentiate PCNSLs from other brain lesions. Diffusion restriction, relative hypoperfusion, increased choline/creatinine, decrease of N-acetyl aspartate (NAA) peak as well as the presence of lactate and lipid peaks are consistent advanced imaging findings in CNS lymphoma that may help in the differentiation of Primary central nervous system lymphomas (PCNSLs) from other malignancies. Furthermore, advanced imaging techniques will presumably play an important role in the planning of new targeted therapies, for prognostication, and for the monitoring of treatment response in the future.

Dual-energy CT (DECT) imaging makes it possible to identify the characteristics of materials that cannot be recognized with conventional single-energy CT (SECT). In the postprocessing study phase, virtual monochromatic images and virtual-non-contrast (VNC) images, also permits reduction of dose exposure by eliminating the precontrast acquisition scan. Moreover, in virtual monochromatic images, the iodine contrast increases when the energy level decreases resulting in better visualization of hypervascular lesions and in a better tissue contrast between hypovascular lesions and the surrounding parenchyma; thus, allowing for reduction of required iodinate contrast material, especially important in patients with renal impairment. All these advantages are particularly important in oncology, providing the possibility of overcoming many SECT imaging limits and making CT examinations safer and more feasible in critical patients. This review explores the basis of DECT imaging and its utility in routine oncologic clinical practice, with particular attention to the benefits of this technique for both the patients and the radiologists.

Neuroimaging plays a key role in the diagnosis and differentiation of brain metastases (BM) in patients with known or unknown malignancies. Computed tomography and magnetic resonance imaging are the key imaging modalities used in the detection of BM. Advanced imaging techniques including proton magnetic resonance spectroscopy, magnetic resonance perfusion, diffusion weighted imaging, and diffusion tensor imaging may aid in arriving at the correct diagnosis, in particular cases, such as newly diagnosed solitary enhancing brain lesions in patients without known malignancy. Imaging is also performed to predict and/or assess the efficacy of treatment, and to differentiate residual or recurrent tumors from therapy-related complications. Furthermore, the recent advent of artificial intelligence is opening up a vast scenario for the analysis of quantitative information deriving from neuroimaging. In this image-rich review, we provide an up-to-date overview on the application of imaging in patients with BM. We describe typical and atypical imaging findings of parenchymal and extra-axial BM on Computed tomography, magnetic resonance imaging, and positron emission tomography, focusing on the role of advanced imaging techniques, that can serve as problem-solving tools in the management of patients with BM.

Hepatocellular carcinoma (HCC) is the most common liver cancer and is one of the uppermost 2 causes of cancer death. About 70%-90% of HCCs develop within a cirrhotic liver. According to the most recent guidelines, the imaging characteristics of HCC on contrast-enhanced Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) are generally satisfactory to make a diagnosis. Recently, new advanced techniques such as contrast-enhanced ultrasound, CT perfusion, Dynamic Contrast-enhanced MRI, diffusion weighted imaging and radiomics have increased the diagnostic accuracy and characterization of HCC. This review illustrates the state of the art and recent advances in non-invasive imaging evaluation of HCC.

Gastrointestinal stromal tumors (GISTs) arise from the interstitial cells of Cajal in the gastrointestinal tract and are the most common intestinal tumors. Usually GISTs are asymptomatic, especially small tumors that may not cause any symptoms and may be found accidentally on abdominal CT scans. Discovering of inhibitor of receptor tyrosine kinases has changed the outcome of patients with high-risk GISTs. This paper will focus on the role of imaging in diagnosis, characterization and follow-up. We shall also report our local experience in radiomics evaluation of GISTs.

Currently, minimally invasive ablative techniques for the treatment of renal tumors have become a more common and feasible treatment option. New imaging technologies have been implemented and successfully merged with each other to improve the guidance of tumor ablation. In the present review, an overview of the real-time fusion of multiple imaging modalities, robotic and electromagnetic navigation and the application of artificial intelligence software, in field of tumor renal ablation treatment, are analyzed.

Urothelial cancers are often detected incidentally because of an exponential growth in medical cross-sectional imaging. Nowadays there is the need for improved lesion characterization to distinguish clinically significant tumors from benign conditions. The gold standard for diagnosis of bladder cancer is cystoscopy, while for upper tract urothelial cancer computed tomographic urography and flexible ureteroscopy are more appropriate modalities. Computed tomography (CT) is the cornerstone in the assessment of locoregional and distant disease, using a protocol with precontrastographic and postcontrastographic phases. In particular, renal pelvis, ureter and bladder lesions can be assessed during the urography phase in the acquisition protocol of the urothelial tumors. Multiphasic CT is associated with overexposure to ionising radiation and repeated infusion of iodinated contrast media, which can be problematic especially in certain types of patients (allergic, nephropathic, pregnant women and in paediatric age). Dual-energy CT can overcome these difficulties with a number of methods, for example, by reconstructing virtual noncontrast images from a single-phase examination with contrast medium. In this review of the recent literature, we would like to highlight the role of Dual-energy CT in the diagnosis of urothelial cancer, its potential in this setting and possible advantages related to it.

The latest evolutions in Computed Tomography (CT) technology have several applications in oncological imaging. The innovations in hardware and software allow for the optimization of the oncological protocol. Low-kV acquisitions are possible thanks to the new powerful tubes. Iterative reconstruction algorithms and artificial intelligence are helpful for the management of image noise during image reconstruction. Functional information is provided by spectral CT (dual-energy and photon counting CT) and perfusion CT.

The vestibulocochlear nerve is the eighth cranial nerve, entering the brainstem in the medullopontine sulcus after crossing the internal auditory canal and cerebellopontine angle cistern. It is a purely sensitive nerve, originating from the Scarpa's and spiral ganglions, responsible for balance and hearing. It has 6 nuclei located in the lower pons. Magnetic resonance imaging (MRI) is useful for evaluating the vestibulocochlear nerve, although computed tomography may have a complementary role in assessing bone lesions. A heavily T2-weighted sequence, such as fast imaging employing steady-state acquisition (FIESTA) or constructive interference steady state (CISS), is crucial in imaging exams to depict the canalicular and cisternal segments of the vestibulocochlear nerve, as well as the fluid signal intensity in the membranous labyrinth. The vestibulocochlear nerve can be affected by several diseases, such as congenital malformations, trauma, inflammatory or infectious diseases, vascular disorders, and neoplasms. The purpose of this article is to review the vestibulocochlear nerve anatomy, discuss the best MRI techniques to evaluate this nerve and demonstrate the imaging aspect of the main diseases that affect it.