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.     

Cardiovascular magnetic resonance of cardiac tumors and masses

Cardiac masses diagnosis and treatment are a true challenge, although they are infrequently encountered in clinical practice. They encompass a broad set of lesions that include neoplastic (primary and secondary), non-neoplastic masses and pseudomasses. The clinical presentation of cardiac tumors is highly variable and depends on several factors such as size, location, relation with other structures and mobility. The presumptive diagnosis is made based on a preliminary non-invasive diagnostic work-up due to technical difficulties and risks associated with biopsy, which is still the diagnostic gold standard. The findings should always be interpreted in the clinical context to avoid misdiagnosis, particularly in specific conditions (e.g., infective endocarditis or thrombi). The modern multi-modality imaging techniques has a key role not only for the initial assessment and differential diagnosis but also for management and surveillance of the cardiac masses. Cardiovascular magnetic resonance (CMR) allows an optimal non-invasive localization of the lesion, providing multiplanar information on its relation to surrounding structures. Moreover, with the additional feature of tissue characterization, CMR can be highly effective to distinguish pseudomasses from masses, as well as benign from malignant lesions, with further differential diagnosis of the latter. Although histopathological assessment is important to make a definitive diagnosis, CMR plays a key role in the diagnosis of suspected cardiac masses with a great impact on patient management. This literature review aims to provide a comprehensive overview of cardiac masses, from clinical and imaging protocol to pathological findings.     

The “spoke wheel” sign in hepatic focal nodular hyperplasia

Abdominal Radiology -     

Doppler echocardiographic assessment of fetal descending aortic and umbilical blood flows. Validation studies in fetal lambs

BACKGROUND. Doppler ultrasound has been used to assess abdominal aortic and umbilical blood flows in the human fetus, but the accuracy of this approach has not been demonstrated in an animal model. METHODS AND RESULTS. We compared abdominal aortic and umbilical blood flows determined by Doppler echocardiography in 12 fetal lambs with invasive flow measurements using radionuclide-labeled microspheres and electromagnetic flow transducers. We varied fetal blood flow from 100 to 950 ml/min in the abdominal aorta and from 130 to 610 ml/min in the umbilical vein. Invasive and Doppler echocardiographic flow measurements correlated well at both sites (y = 68 + 1.02x, r = 0.94, and y = 33 + 1.1x, r = 0.91, respectively). A slight overestimation of flow using the Doppler method may require a correction factor to assess actual flow. The degree of overestimation was not systematically related to measurements taken in smaller vessels or at larger angles of incidence. CONCLUSIONS. The present study demonstrates that determination of abdominal aortic and umbilical venous flows by echocardiography and pulsed Doppler ultrasound is feasible. Doppler measurements appear to be suited to serial comparison of actual flow.     

The Widened Pipe Model of plant hydraulic evolution

Shaping global water and carbon cycles, plants lift water from roots to leaves through xylem conduits. The importance of xylem water conduction makes it crucial to understand how natural selection deploys conduit diameters within and across plants. Wider conduits transport more water but are likely more vulnerable to conduction-blocking gas embolisms and cost more for a plant to build, a tension necessarily shaping xylem conduit diameters along plant stems. We build on this expectation to present the Widened Pipe Model (WPM) of plant hydraulic evolution, testing it against a global dataset. The WPM predicts that xylem conduits should be narrowest at the stem tips, widening quickly before plateauing toward the stem base. This universal profile emerges from Pareto modeling of a trade-off between just two competing vectors of natural selection: one favoring rapid widening of conduits tip to base, minimizing hydraulic resistance, and another favoring slow widening of conduits, minimizing carbon cost and embolism risk. Our data spanning terrestrial plant orders, life forms, habitats, and sizes conform closely to WPM predictions. The WPM highlights carbon economy as a powerful vector of natural selection shaping plant function. It further implies that factors that cause resistance in plant conductive systems, such as conduit pit membrane resistance, should scale in exact harmony with tip-to-base conduit widening. Furthermore, the WPM implies that alterations in the environments of individual plants should lead to changes in plant height, for example, shedding terminal branches and resprouting at lower height under drier climates, thus achieving narrower and potentially more embolism-resistant conduits.

Water transport through plants is a key driver of the carbon and other biogeochemical cycles (1–3) and is a crucial link in plant adaptation to climate and vegetation response to climate change (4–9). The water conducting cells of plants, xylem conduits, widen with distance from the stem tip, and, therefore, taller plants have wider conduits (6, 10–12). Xylem conduits are of two main types: tracheids, found in most gymnosperms, and vessels, found in most flowering plants. Tracheids have intact cell membranes, so water must flow from cell to cell through these membranes. Vessels are made up of cells aligned vertically end to end, with the cell membranes dissolved between successive members, forming a tube. Whatever their differences in structure, wider conduits are beneficial because they conduct more water. Tip-to-base widening is expected to help maintain conductance per unit leaf area constant as an individual plant grows taller, counterbalancing the resistance that would otherwise accrue with increasing conductive path length the individual grows (2, 13). Wider conduits, however, are more vulnerable to embolisms caused by cold and likely drought (8, 14–18) and cost more in terms of carbon for a plant (ref. 1; cf. ref. 19). Embolisms in the xylem even affect transport of photosynthates in the phloem (8, 20). This means that as trees grow taller, conductance, embolism vulnerability, and carbon costs must interrelate in a delicate evolutionary balance.Because of the importance of this balance in plant hydraulic evolution and in forest reactions to climate change (3, 6, 21–23), an important goal of plant biology is to construct models that predict how and why plants deploy conduit diameters throughout their bodies (1, 2, 17, 24–26). Some models predict that conduits should be of uniform diameter (27, 28), while others predict that they should widen tip to base (1, 2, 13, 24, 29, 30). But even current models include untested assumptions and large numbers of parameters, making it difficult to identify the biological causes of the predictions they make. For example, some invoke Da Vinci’s rule, the largely untested assumption that the summed wood area of the twigs is the same as that at the base (24, 26). Other models depict plant conduits as branching as they do in mammalian circulatory systems, but whether this happens along the entire stem in plants is unclear (30–33). There is an expectation that conduit diameter D should widen with distance from the stem tip L following a power-law (D ∝ L^b), but there is no agreement on the value of b, the conduit widening exponent (1, 2). Furthermore, even though within-individual tip-to-base conduit widening has been confirmed in a handful of species (34–36), and the scaling of conduit diameter with plant size across species is consistent with it (6, 10–12, 34), the expectation that conduits should widen similarly within stems across terrestrial vascular plant lineages and habits has yet to be empirically confirmed. Here we present the Widened Pipe Model (WPM), which correctly predicts the form of tip-to-base conduit widening across the span of plant size, life form, and habitat across the terrestrial plant phylogeny.     

Cardiac features of Emery-Dreifuss muscular dystrophy caused by lamin A/C gene mutations.

AIMS: Retrospective studies have identified a mutation in the lamin A/C (LMNA) gene in patients selected on the basis of a phenotype characterized by dilated cardiomyopathy, atrioventricular conduction disturbances and sudden death. However, the features of cardiac abnormalities in patients with an initial diagnosis of Emery-Dreifuss muscular dystrophy (EDMD) are poorly known. Aim of the present study was to investigate the spectrum of cardiac disease in patients with an initial diagnosis of EDMD caused by a mutation in the LMNA gene. METHODS AND RESULTS: Ten consecutive patients with EDMD and a LMNA gene mutation were evaluated with structured medical interview, physical examination, ECG, echocardiogram and 24-h Holter monitoring. Electrophysiological testing and cardiac catheterization were performed if a class 1 or 2 American Heart Association guidelines indication was present. Cardiac disease was found in eight of 10 patients and consisted in the variable combination of supraventricular arrhythmias, disorders of atrioventricular conduction, ventricular arrhythmias, dilated cardiomyopathy, non-dilated cardiomyopathy, restrictive cardiomyopathy and sudden death despite pacemaker implant. CONCLUSIONS: Cardiac disease is common in patients with an initial diagnosis of EDMD caused by a mutation in the LMNA gene and consists of arrhythmias, disorders of atrioventricular conduction, cardiomyopathies and sudden death despite pacemaker implant.