Surface coil MR imaging of abdominal viscera. Part I. Theory, technique, and initial results.

Prototype surface coil magnetic resonance (MR) images were obtained from phantoms and 42 subjects at 0.6 T to assess the feasibility of imaging relatively deep abdominal structures. Surface coil images demonstrated a two- to fourfold improvement in signal-to-noise ratio (SNR) when compared with whole-body coil images with the same resolution elements.

Chemical shift imaging of bone marrow: preliminary experience.

A phase-contrast method of chemical shift imaging was used to evaluate bone marrow in normal volunteers and in patients with metabolic, inflammatory, traumatic, and neoplastic disorders. Five normal volunteers were examined in order to obtain preliminary data on normal patterns of signal intensity in hematopoietic and fatty marrow using both conventional magnetic resonance imaging and proton chemical shift imaging. Normally, hematopoietic marrow yields low signal intensity on phase-contrast images; pathologic conditions affecting hematopoietic marrow typically result in increased signal intensity due to either accumulated lipid or water.

Magnetic resonance imaging of the interatrial septum and atrial septal defects.

Magnetic resonance images were obtained in six patients with known or suspected interatrial septal defects (ASD) and 33 subjects without congenital heart disease. Image planes were oriented to the long and short axes of the left ventricle and septum and provided reproducible display of pertinent anatomic landmarks. Of the images in 33 control subjects, three (9%) were falsely positive showing apparent ASD.

Early detection of cardiac allograft rejection with proton nuclear magnetic resonance.

No reliable, noninvasive technique is currently available for the early detection of cardiac transplant rejection. In this study, pulse nuclear magnetic resonance (NMR) spectroscopy was used (20 MHz) to detect cardiac allograft rejection in rats. Proton spin-lattice relaxation time (T1), proton spin-spin relaxation time (T2), and water content were measured in both recipient and donor hearts at 2, 4, 6, and 8 days after transplantation.

Adrenal pseudomasses due to varices: angiographic-CT-MRI-pathologic correlations.

Periadrenal and adrenal portosystemic collaterals are a recently reported cause of adrenal pseudotumor on computed tomography (CT). Nine patients with this left adrenal pseudotumor illustrate its typical position and appearance on CT, angiography, CT-angiography, and magnetic resonance imaging (MRI). The anatomic basis for variceal adrenal pseudotumors is the left inferior phrenic vein, which passes immediately anterior to the left adrenal gland and which serves as a collateral pathway from splenic to left renal vein in portal hypertension.

Sacrococcygeal chordoma: magnetic resonance imaging and computed tomography.

Magnetic resonance imaging (MRI) was compared to computed tomography (CT) in four cases of sacrococcygeal chordoma. Both techniques yielded important anatomic information and represented important advances over early radiologic imaging methods. MRI provides superior contrast with surrounding soft tissues because of the prolonged T1 and T2 times of the tumors.

High-resolution surface-coil imaging of lumbar disk disease.

Seventeen patients with lumbar disk disease were studied using a prototype magnetic resonance (MR) surface coil. The high signal-to-noise ratio achieved with the surface coil permitted increases in spatial resolution to 0.9 X 0.

MR velocity imaging by phase display.

The ability of the nuclear magnetic resonance signal to encode information about macroscopic motion has been recognized since the works of Hahn and Carr and Purcell. In the medical imaging setting this ability has led to a variety of ingenious magnetic resonance flow imaging schemes that ultimately may become competitive with X-ray angiography in sensitivity and specificity while remaining radically noninvasive. This work demonstrates that conventional spin-echo Fourier transform image acquisitions naturally encode a component of flow velocity that lies within the image plane.

Iron-EHPG as an hepatobiliary MR contrast agent: initial imaging and biodistribution studies.

The paramagnetic metal complex iron(III) ethylenebis-(2-hydroxyphenylglycine) [Fe(EHPG)-] is an effective hepatobiliary contrast agent for liver enhancement in magnetic resonance (MR) imaging. The intravenous administration of 0.2 mmol/kg of Fe(EHPG)- to rats yields a 200% increase in the signal intensity of the liver when using a T1-weighted inversion recovery pulse sequence on a 1.

MR imaging of the acoustic nerves and small acoustic neuromas at 0.6 T: prospective study.

To evaluate the capability of magnetic resonance (MR) in imaging normal acoustic nerves, 12 volunteers without signs or symptoms of intracranial disease were examined using a 0.6 T superconductive system. Several spin-echo (SE) pulse sequences were tested to identify the optimal sequence for demonstration of the acoustic nerve bundle.

Study of vitreous liquifaction by NMR spectroscopy and imaging.

The vitreous gel is primarily composed of collagen, hyaluronic acid, and water (98-99%) and can break down into a liquid state devoid of collagen. The liquifaction of vitreous gel that occurs with age and in certain other disease states is believed to be important in the pathogenesis of retinal tears and detachments. The authors report measurements of water proton relaxation times and water proton nuclear magnetic resonance (NMR) imaging to study the process of vitreous liquifaction in extracted vitreous and in the intact bovine eye.

Magnetic resonance imaging: present and future applications.

Magnetic resonance (MR) imaging has created considerable excitement in the medical community, largely because of its great potential to diagnose and characterize many different disease processes. However, it is becoming increasingly evident that, because MR imaging is similar to computed tomography (CT) scanning in identifying structural disorders and because it is more costly and difficult to use, this highly useful technique must be judged against CT before it can become an accepted investigative tool. At present MR imaging has demonstrated diagnostic superiority over CT in a limited number of important, mostly neurologic, disorders and is complementary to CT in the diagnosis of certain other disorders.

Magnetic resonance imaging in a patient with soft tissue sarcoma of the leg.

A patient with a high grade malignant fibrous histiocytoma of the leg is presented. Staging studies included a 99mTc diphosphonate bone scan, an arteriogram, a computed tomogram (CT) and a proton (1H) magnetic resonance imaging (MRI) study. By manipulating imaging parameters to enhance contrast between normal and neoplastic tissues, the latter technique more accurately delineated the extent of the soft tissue sarcoma than the other imaging modalities.

Assessment of myocardial ischemia with proton magnetic resonance: effects of a three hour coronary occlusion with and without reperfusion.

Proton (hydrogen-1) magnetic resonance imaging techniques have potential for the detection and characterization of changes associated with myocardial ischemia. Since image contrast is dependent on T1 and T2 relaxation times, we examined these parameters in a canine preparation of occlusion of the left anterior descending coronary artery. Of 16 dogs studied, seven underwent 3 hr of coronary artery occlusion and nine underwent 3 hr of occlusion followed by 1 hr of reperfusion.

The effect of the suspensor and gibberellic acid on Phaseolus vulgaris embryo protein content.

The role of the suspensor in the early development of the dicot embryo has not yet been defined. It has been described as merely an anchor and also as the major route of nutrients into the embryo. In order to further elucidate the role of the suspensor, early 0.

Proton chemical shift imaging: an evaluation of its clinical potential using an in vivo fatty liver model.

The potential laboratory and clinical utility of proton chemical shift imaging (PCSI) was evaluated by studying fatty liver change in rats, which offered a simple animal model for tissue lipid buildup. There was excellent correlation between lipid group signal intensities from in vivo PCSI studies and liver triglyceride levels obtained from in vitro measurements (R = 0.97).

In vivo 19F NMR imaging.

In vitro and in vivo 19F spectra and images were obtained using various clinically safe fluorinated compounds. Standard and chemical shift images were acquired in solutions of fluorinated anesthetics with the chemical shift images clearly separating signals arising from a mixture of halothane and methoxyflurane. The 19F images of halothane in rats were unsuccessful at anesthetic concentration.

Preparation and water relaxation properties of proteins labeled with paramagnetic metal chelates.

The proteins bovine serum albumin (BSA) and bovine immunoglobulin (IgG) have been labeled with paramagnetic gadolinium (III) and manganese (II) complexes using the bifunctional chelate approach. Diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) were attached to several free amino groups on the proteins using cyclic anhydride forms of these ligands. The incorporation of the metal ions Gd+3 and Mn+2 into the chelating groups yielded highly paramagnetic proteins.

The fluorinated anesthetic halothane as a potential NMR biologic probe.

Fluorinated anesthetics such as halothane preferentially partition into hydrophobic environments such as cell membranes. The 19F-NMR spectrum of halothane in a rat adenocarcinoma (with known altered lipid metabolism and membrane composition) shows an altered chemical shift pattern compared to the anesthetic in normal tissue. In eight tumor samples examined, the 19F-NMR spectra exhibit two distinct resonances, compared to a single resonance observed in normal tissues.

The evaluation of musculoskeletal disease with magnetic resonance imaging.

Magnetic resonance imaging (MRI) techniques provide a versatile method of manipulating soft tissue contrast in the extremities. Different pulse sequence techniques are discussed with respect to the optimization of contrast differences between muscle, marrow, and abnormal tissue.

Magnetic resonance imaging of the heart: positioning and gradient angle selection for optimal imaging planes.

Electrocardiographically gated magnetic resonance images were acquired in 20 subjects using a spin-echo pulse sequence. For optimizing the display of cardiac anatomy, a technique was developed which uses patient positioning in addition to alteration of gradient angle to select image planes. High-quality images were acquired in three basic cardiac projections: (1) the long axis of the left ventricle, through the aortic valve and apex, parallel to the interventricular septum, (2) the long axis of the left ventricle, perpendicular to the septum, and (3) the short axis of the left ventricle at multiple levels including outflow, papillary muscle, and apex.

Nuclear magnetic resonance imaging in evaluation of clinical stroke syndromes.

Proton nuclear magnetic resonance (NMR) imaging was performed on normal volunteers and patients with various types of clinical strokes. True three-dimensional volumetric data were obtained for subsequent reconstruction of images at various orientations, including transverse, coronal, and sagittal, and for specific matching to x-ray computed tomographic planes. A variety of radiofrequency pulse sequences was used to generate images weighted by the NMR parameters spin density (p) and spin-lattice (T1) and spin-spin (T2) relaxation times.

Transcatheter embolization with sodium tetradecyl sulfate. Experimental and clinical results.

Sodium tetradecyl sulfate (Sotradecol), which has been employed for sclerotherapy of varicose veins, was evaluated in dogs and humans as an agent for selective arterial embolization. In dogs, intraarterial injection of Sotradecol 3% into the proximally occluded renal, hepatic, splenic, and deep femoral arteries produced arterial occlusion and tissue destruction. Transcatheter embolization with Sotradecol was performed in 11 patients and was successful in 10; in the remaining patient, failure was attributed to rapid dilution by unobstructed blood flow in arteriovenous malformations of the neck.