Extracting knowledge from science: a conversation with Elias Zerhouni. Interview by Barbara J. Culliton

National Institutes of Health (NIH) director Elias Zerhouni is pushing hard for innovation and the risk taking required to make major leaps in medicine. Fully attuned to cutting-edge work that crosses disciplines, he cites nanotechnology, clinical databases designed to answer research questions, systems biology, and an openness to radical ideas among his top priorities. The NIH director's job, he says, "is to have a vision." This requires leveraging NIH funding so that money is spent more wisely and has a cumulative effect on population health. Knowledge can be extracted from science, and health system transformation is made possible.     

Transmural contractile reserve after reperfused myocardial infarction in dogs

OBJECTIVES

The goal of this study was to characterize detailed transmural left ventricular (LV) function at rest and during dobutamine stimulation in subendocardial and transmural experimental infarcts.

BACKGROUND

The relation between segmental LV function and the transmural extent of myocardial necrosis is complex. However, its detailed understanding is crucial for the diagnosis of myocardial viability as assessed by inotropic stimulation.

METHODS

Short-axis tagged magnetic resonance images were acquired at five to seven levels encompassing the LV from base to apex in seven dogs 2 days after a 90-min closed-chest left anterior descending coronary occlusion, followed by reflow. Myocardial strains were measured transmurally in the entire LV by harmonic phase imaging at rest and 5 ig.kg⁻¹.min⁻¹ dobutamine. Risk regions were assessed by radioactive microspheres, and the transmural extent of the infarct was assessed by 2,3,5 triphenyltetrazolium chloride staining.

RESULTS

Circumferential shortening (Ecc), radial thickening (Err) and maximal shortening at rest were greater in segments with subendocardial versus transmural infarcts, both in subepicardium (−1.1 ± 1.0 vs. 2.5 ± 0.6% for Ecc, −0.5 ± 1.9 vs. −1.8 ± 1.0% for Err, p < 0.05) and subendocardium (−2.0 ± 1.4 vs. 2.8 ± 0.8%, 2.4 ± 1.7 vs. 0.0 ± 0.9%, respectively, p < 0.05). Under inotropic stimulation, risk regions retained maximal contractile reserve. Recruitable deformation was found in outer layers of subendocardial infarcts (p < 0.01 for Ecc and Err) but also in inner layers (p < 0.01). Conversely, no contractile reserve was observed in segments with transmural infarcts.

CONCLUSIONS

Under dobutamine challenge, recruitment of myofiber shortening and thickening was observed in inner layers of segments with subendocardial infarcts. These results may have important clinical implications for the detection of myocardial viability.     

Sickle cell beta-thalassaemia compared with sickle cell anaemia in Algeria

Clinical, haematological and biochemical features in 42 subjects with S-beta thalassaemia (31 subjects with S-beta thalassaemia and 11 subjects with S-beta+ thalassaemia); and in 42 with homozygous sickle cell disease were compared. Persistent splenomegaly was more common and painful crises less common in the S-beta thalassaemia group. Total Hb was higher and reticulocyte count lower in S-beta+ thalassaemia than in S-beta thalassaemia or SS disease. Microcytosis was marked in the S-beta thalassaemia group while the MCV was normal in sickle cell anaemia. Hb F was significantly higher in the S-beta thalassaemia group, without any influence on the severity of the disease. Many features suggest that sickle cell thalassaemia is more severe in Algeria than in Negro subjects and similar to the disease in Italian patients.     

The intrathoracic kidney: should we fix it?

BackgroundIntrathoracic kidney is a rare congenital anomaly, with only 13 cases reported in the pediatric age group over the past 25 years. The relevant literature is limited to individual case reports or small case series with no follow-up data. Both operative and nonoperative management has been advocated. We report our experience in the management of children with an intrathoracic kidney as well as the efficacy of nonoperative management in select patients.MethodsFive cases of intrathoracic kidney were collected prospectively since 1992 and carefully followed up long term.ResultsTwo children presented with acute respiratory distress and underwent right diaphragmatic hernia repair and nephropexy. Incidental diagnosis of a left intrathoracic kidney was made in 3 children. Long-term follow-up has demonstrated normal function and development of these kidneys in all 5 children with no late bowel herniation in the nonoperative group.ConclusionIntrathoracic kidney associated with bowel in the chest should undergo standard repair and nephropexy. An isolated intrathoracic kidney without evidence of bowel herniation can safely be observed. This is the largest pediatric series of intrathoracic kidney as well as the first to document the efficacy of nonoperative management with long-term follow-up.     

A survey of breast cancer screening techniques: thermography and electrical impedance tomography

Abstract

Breast cancer is a disease that threat many women’s life, thus, the early and accurate detection play a key role in reducing the mortality rate. Mammography stands as the reference technique for breast cancer screening; nevertheless, many countries still lack access to mammograms due to economic, social and cultural issues. Last advances in computational tools, infra-red cameras and devices for bio-impedance quantification allowed the development of parallel techniques like, thermography, infra-red imaging and electrical impedance tomography, these being faster, reliable and cheaper. In the last decades, these have been considered as complement procedures for breast cancer diagnosis, where many studies concluded that false positive and false negative rates are greatly reduced. This work aims to review the last breakthroughs about the three above-mentioned techniques describing the benefits of mixing several computational skills to obtain a better global performance. In addition, we provide a comparison between several machine learning techniques applied to breast cancer diagnosis going from logistic regression, decision trees and random forest to artificial, deep and convolutional neural networks. Finally, it is mentioned several recommendations for 3D breast simulations, pre-processing techniques, biomedical devices in the research field, prediction of tumour location and size.     

Human heart: tagging with MR imaging--a method for noninvasive assessment of myocardial motion

Specified regions of the myocardium can be labeled in magnetic resonance (MR) imaging to serve as markers during contraction. The technique is based on locally perturbing the magnetization of the myocardium with selective radio-frequency (RF) saturation of multiple, thin tag planes during diastole followed by conventional, orthogonal-plane imaging during systole. The technique was implemented on a 0.38-T imager and tested on phantoms and volunteers. In humans, tags could be seen 60-450 msec after RF saturation, thus permitting sampling of the entire contractile phase of the cardiac cycle. Tagged regions appear as hypointense stripes, and their patterns of displacement reflect intervening cardiac motion. In addition to simple translation and rotation, complex motions such as cardiac twist can be demonstrated. The effects of RF pulse angle, relaxation times, and heart rate on depiction of the tagged region are discussed.     

Quantification and validation of left ventricular wall thickening by a three-dimensional volume element magnetic resonance imaging approach

We have developed a method to quantify and map regional wall thickening throughout the left ventricle (LV) with magnetic resonance imaging. In contrast to methods that measure planar wall thickness and thickening, this method uses the three-dimensional (3D) geometry of the left ventricle to calculate the perpendicular thickness of the wall. We tested this method at three levels of increasing complexity using 1) phantom studies, 2) in vivo experiments in dogs with normal cardiac function, and 3) in vivo studies in dogs during acute ischemia. Experiments were conducted in 15 open-chest dogs imaged by a 0.38 T iron core magnet. Five short-axis images at end diastole and end systole were obtained with the spin echo technique by use of the QRS as a trigger for end diastole and the second heart sound, S2, to time end systole. After acquisition of preischemic images, acute ischemia was induced by either coronary artery ligation (n = 5) or intracoronary dental rubber injection (n = 5), which produced severe transmural ischemia. By use of computer-aided contouring of the endocardial and epicardial borders, each image was divided into 16 segments with radial lines originating from the midwall centroid. A 3D volume element was defined as that generated by connecting two matched planar segments in two adjacent image planes. This defined 64 volume elements comprising the entire left ventricle. Thickness and thickening before and during ischemia were then calculated by using the planar segments and the 3D volume elements. In phantom studies, the 3D method was accurate, independent of the angle of inclination of the image plane to the phantom wall, whereas the planar method showed considerable overestimation of thickness when the image plane was oblique to the phantom wall. In the dogs before induction of ischemia, the 3D method demonstrated the well-established normal taper in end-diastolic wall thickness from 1.10 +/- 0.02 cm at the base to 1.05 +/- 0.11 cm at the apex (p less than 0.01). By contrast, the planar method did not detect the decrease in thickness toward the apex (1.13 +/- 0.07 cm at the base vs. 1.16 +/- 0.14 cm at the apex, p = NS). During acute ischemia, thickening was calculated by both methods at the center of the ischemic zone defined by Monastral blue nonstaining and compared with the preischemic values.(ABSTRACT TRUNCATED AT 400 WORDS)     

Calf hematoma — computed tomographic and magnetic resonance findings

Four patients with hematomas of the calf are presented. The diagnosis was made by computed tomography (CT) in three cases and CT/magnetic resonance imaging (MRI) in one case. In all cases, CT or MRI clarified a confusing clinical picture. CT and MRI can help differentiate the types of calf mass (i.e., hematoma, tumor, Baker cyst, thrombophlebitis) and assist proper clinical management in a rapid, noninvasive fashion.