Towards endometriosis diagnosis by gadofosveset-trisodium enhanced magnetic resonance imaging

Endometriosis is defined as the presence of endometrial tissue outside the uterus. It affects 10-15% of women during reproductive age and has a big personal and social impact due to chronic pelvic pain, subfertility, loss of work-hours and medical costs. Such conditions are exacerbated by the fact that the correct diagnosis is made as late as 8-11 years after symptom presentation. This is due to the lack of a reliable non-invasive diagnostic test and the fact that the reference diagnostic standard is laparoscopy (invasive, expensive and not without risks). High-molecular weight gadofosveset-trisodium is used as contrast agent in Magnetic Resonance Imaging (MRI). Since it extravasates from hyperpermeable vessels more easily than from mature blood vessels, this contrast agent detects angiogenesis efficiently. Endometriosis has high angiogenic activity. Therefore, we have tested the possibility to detect endometriosis non-invasively using Dynamic Contrast-Enhanced MRI (DCE-MRI) and gadofosveset-trisodium as a contrast agent in a mouse model. Endometriotic lesions were surgically induced in nine mice by autologous transplantation. Three weeks after lesion induction, mice were scanned by DCE-MRI. Dynamic image analysis showed that the rates of uptake (inwash), persistence and outwash of the contrast agent were different between endometriosis and control tissues (large blood vessels and back muscle). Due to the extensive angiogenesis in induced lesions, the contrast agent persisted longer in endometriotic than control tissues, thus enhancing the MRI signal intensity. DCE-MRI was repeated five weeks after lesion induction, and contrast enhancement was similar to that observed three weeks after endometriosis induction. The endothelial-cell marker CD31 and the pericyte marker α-smooth-muscle-actin (mature vessels) were detected with immunohistochemistry and confirmed that endometriotic lesions had significantly higher prevalence of new vessels (CD31 only positive) than the uterus and control tissues. The diagnostic value of gadofosveset-trisodium to detect endometriosis should be tested in human settings.     

Oesophageal carcinoma demonstrated by whole-body nuclear magnetic resonance imaging.

The quality of the images produced by nuclear magnetic resonance (NMR) imaging has steadily improved over the past five years. Images of the head, thorax, and abdomen have clearly shown the normal anatomy. A clinical trial of NMR imaging has therefore been started in Aberdeen to assess its diagnostic accuracy and compare it with conventional radiography and other imaging technique. The first patient examined by whole-body NMR imaging had carcinoma of the oesophagus diagnosed on barium meal examination. A technetium-99m-sulphur colloid liver scan also showed hepatic metastases. NMR imaging showed a large tumour in the lower third of the oesophagus, and areas of increased proton spin-lattice relaxation time (T1) on a section through the liver corresponded with the metastases shown on the radionuclide scan. Increased areas of T1 were present in some vertebrae, and a technetium-99m bone scan confirmed the presence of bone metastases. The NMR images in this patient compared well with the images from other techniques. The continuing clinical trial may show that NMR is an accurate diagnostic aid which will complement existing techniques for diagnosing intrathoracic and intra-abdominal conditions.     

In vitro tracheal mechanics by nuclear magnetic resonance imaging

Images of rabbit tracheal cross sections were obtained at a series of transmural pressures ranging from 22 to -95 cmH2O by use of a nuclear magnetic resonance imaging microscope. The excised, washed tracheas were immersed in a solution of phosphate-buffered saline made up in deuterium oxide (D2O, pH 7.3). The images are maps of proton density in the image slice (2.5 mm thick). All but one series of images showed a collapse process in which the trachealis muscle invaginated asymmetrically, i.e., the muscle appeared to favor one side of the cartilage ring system more than the other. The connecting tissue between the cartilage rings appeared to be more compliant than the rings themselves, thus suggesting that the tracheal lumen became corrugated at negative pressures. In the plane of a cartilage ring, the lumen appeared to remain patent at pressures as low as -95 cmH2O. However, between rings, where the tracheal wall was more compliant, the lumen appeared to be totally occluded at -53 cmH2O. Lumen areas in both the plane of the cartilage rings and in a plane between rings were measured from each series of printed images for six tracheas. These measurements, when normalized, averaged, and plotted against transmural pressure gave asymptotic logarithmic compliances (n1 in the model of Lambert et al., J. Appl. Physiol. 52: 44-56, 1982) of 1.2 +/- 0.4 and 20 +/- 7 for the interring and ring regions, respectively. These values are greater than the critical value of 0.5 (J. Appl. Physiol. 62: 2426-2435, 1987) and are thus consistent with wave speed flow limitation being possible anywhere in the trachea during forced expiration.     

Developing functional magnetic resonance imaging techniques for alert macaque monkeys

Functional magnetic resonance imaging (fMRI) has developed rapidly into a major non-invasive tool for studying the human brain. However, due to a variety of technical difficulties, it has yet to be widely adopted for use in alert, trained non-human primates. Our laboratory has been developing techniques for such fMRI studies. As background, we first consider basic principles of fMRI imaging, experimental design, and post-processing. We discuss appropriate MRI system hardware and components for conducting fMRI studies in alert macaques, and the animal preparation and behavior necessary for optimal experiments. Finally, we consider alternative fMRI techniques using exogenous contrast agents, arterial spin labeling, and more direct measures of neural activation.     

Contrast agents for nuclear magnetic resonance imaging

Nuclear magnetic resonance imaging relies upon differences in relaxation times for much of its ability to resolve anatomical structures and to detect changes in tissue. The natural differences can be changed by the administration of paramagnetic substances, such as metal complexes and stable organic free radicals, and ferromagnetic materials, such as small particles of magnetite. Detailed studies of the chemistry and biophysics of such substances in the body are required if they are to become safe and effective contrast agents for use in medical NMR imaging.     

Recent developments in technics of nuclear magnetic resonance imaging

Three main aspects of presently developed nuclear magnetic resonance imaging techniques are pointed out in this short review: first, the importance of Fourier transform as reconstruction technique is recalled; secondly, the problem of the choice of the magnetic field value is raised and third, new trends in magnetic imaging are noticed such as the use of nuclei other than hydrogen or the improvement of phase contrast methods.     

Differentiation between hemosiderin- and ferritin-bound brain iron using nuclear magnetic resonance and magnetic resonance imaging.

MRI is an optimal clinical (research) tool to provide information on brain morphology and pathology and to detect metal ions that possess intrinsic magnetic properties. Non-heme iron is abundantly present in the brain in three different forms: "low molecular weight" complexes, iron bound to "medium molecular weight complexes" metalloproteins such as transferrin, and "high molecular weight" complexes as ferritin and hemosiderin. The total amount and form of iron may differ in health and disease, and MRI can possibly quantify and monitor such changes. Ferritin-bound iron is the main storage form of iron and is present predominantly in the extrapyramidal nuclei where its amounts normally increase as a function of age. Ferritin is water soluble and shortens both, T1 and T2 relaxation, with as result a signal change on the MR images. Hemosiderin, a degradation product of ferritin, is water-insoluble with a stronger T2 shortening effect than ferritin. The larger cluster size of hemosiderin and its water-insolubility also explain a lack of significant T1-shortening effect on T1-weighted images. Using both in vitro specimens and intact brain tissue in vivo we demonstrate here that MRI may be able to distinguish between ferritin- and hemosiderin-bound iron.     

A nuclear magnetic resonance imaging technique designed for studies of water in plant leaves.

A new imaging technique is described which uses nuclear magnetic resonance (NMR) to create a water profile of plant leaves. The water profile shows the average distribution of water as a function of depth into a leaf along a line perpendicular to the leaf surface; it can be used to measure the thickness of cell layers and the quantity of water in each layer. Two-dimensional NMR methods were used to avoid chemical shift distortion which degrades the resolution in leaf images made by conventional NMR techniques; image resolution was improved further by deconvolution analysis. To illustrate its application, the technique was used to follow changes in the internal structure of developing leaves.     

A case of pituitary stalk tumor diagnosed with magnetic resonance (MRI)]

Authors present a case of 28-year old female with anterior hypopituitarism and diabetes insipidus, with properly functioning anterior pituitary cells as showed by means of measuring pituitary hormones in response to neurohormones i.v. injections. Magnetic resonance imaging revealed neoplastic tissue in the pituitary stalk destroying supraopticohypophysial and paraventriculohypophysial tracts, as well as portal blood system, thus preventing release of vasopressin and these hypothalamic neurohormones from accessing anterior pituitary.     

Spatial distribution of oil in groundnut and sunflower seeds by nuclear magnetic resonance imaging

Abstract. The nuclear magnetic resonance imaging technique has been used to obtain images of different transverse and vertical sections in groundnut and sunflower seeds. Separate images have been obtained for oil and water components in the seeds. The spatial distribution of oil and water inside the seed has been obtained from the detailed analysis of the images. In the immature groundnut seeds obtained commercially, complementary oil and water distributions have been observed. Attempts have been made to explain these results.     

Functional imaging of plants by magnetic resonance experiments.

Microimaging based on magnetic resonance is an experimental technique that can provide a unique view of a variety of plant physiological processes. Particularly interesting applications include investigations of water movement and spatially resolved studies of the transport and accumulation of labelled molecules in intact plant tissue. Some of the fundamental principles of nuclear and electron magnetic resonance microimaging are explained here and the potential of these techniques is shown using several representative examples.     

Conformational studies of alanine oligopeptides by nuclear magnetic resonance.

We have studied the nmr spectra of the series of alanine oligopeptides containing a methoxyethoxyethoxyacetyl blocking group on the N-terminal residue and a morpholino blocking group on the C-terminal residue. Spectra were measured in chloroform–trifluoroacetic acid solvent systems. For oligomers with chain lengths of five or more, “double peaks” are observed for the α-CH protons. Addition of trifluoroacetic acid causes the peaks to coalesce. The amount of trifluoroacetic acid necessary for coalescence increases from the pentamer to the nonamer. These findings are general since alanine oligomers with different blocking groups exhibit similar “double peak” phenomena. We explain the “double peak” phenomenon in terms of specific folded forms of the oligopeptides which arise from intramolecular hydrogen bonding. Additional evidence for such hydrogen bonding is presented based upon infrared studies. Slight aggregation probably occurs for the pentamer and hexamer which may stabilize the folded forms.