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Biomedical subjects

W S Hinshaw

Publications and source records attributed to W S Hinshaw.

17 recordsLinked to original sources
PubMed1995

Display of cross sectional anatomy by nuclear magnetic resonance imaging. 1978.

High definition cross-sectional images produced by a new nuclear magnetic resonance (NMR) technique are shown. The images are a series of thin section scans in the coronal plane of the head of a rabbit. The NMR images are derived from the distribution of the density of mobile hydrogen atoms. Various tissue types can be distinguished and a clear registration of gross anatomy is demonstrated. No known hazards are associated with the technique.

Animals↗
PubMed1983

Potential hazards and artifacts of ferromagnetic and nonferromagnetic surgical and dental materials and devices in nuclear magnetic resonance imaging.

The risks to patients with metal surgical implants who are undergoing nuclear magnetic resonance (NMR) imaging and the artifacts caused by such implants were studied. Twenty-one aneurysm and other hemostatic clips and a variety of other materials (e.g., dental amalgam, 14 karat gold) were used. Longitudinal forces and torques were found to be exerted upon 16 of the 21 clips. With five aneurysm clips, forces and torques sufficient to produce risk of hemorrhage from dislocation of the clip from the vessel or aneurysm, or cerebral injury by clip displacement without dislodgement were identified. The induced ferromagnetism was shown to be related to the composition of the alloys from which the clips were manufactured. Clips with 10-14% nickel are evidently without sufficient induced ferromagnetism to cause hazard. The extent of NMR imaging artifacts was greater for materials with measurable ferromagnetic properties, but metals without measurable ferromagnetism in our tests also resulted in significant artifacts. Dental amalgam and 14 karat gold produced no imaging artifacts, but stainless steels in dentures and orthodontic braces produced extensive artifacts in the facial region.

Aneurysm↗
PubMed1982

Preliminary experimental results in humans and animals with a superconducting, whole-body, nuclear magnetic resonance scanner.

In order to determine the clinical usefulness of nuclear magnetic resonance (NMR) imaging, the investigators examined a variety of normal volunteers, patients with neoplastic lesions, and experimental animals. Preliminary results were obtained with the use of potential contrast agents. It was found that imaging applications of NMR in the vascular system, spine, brain, lung, and mediastinum offer certain advantages over other modalities. The absence of biological hazard as well as the ability to obtain unenhanced, noninvasive, gated images of the vascular system, as demonstrated in this study, make NMR particularly attractive. In addition to single-section capability, NMR makes it possible to obtain volume images of the spine and other organs which can be displayed in any desired plane or section thickness.

Animals↗
PubMed1982

Cranial anatomy and detection of ischemic stroke in the cat by nuclear magnetic resonance imaging.

Proton nuclear magnetic resonance (NMR) images of cat heads were obtained using a small, experimental imaging system. As a prelude to the study of experimental ischemic brain infarction, the normal cat head was imaged for identification of anatomical features. Images of one cat which had undergone ligation of the middle cerebral artery three weeks previously showed brain changes associated with chronic ischemic stroke and compared favorably with findings on computed tomography (CT). The NMR images have millimetric spatial resolution. NMR parameters inherent in the tissues provide intensity variations and are sufficiently sensitive to yield contrast resolution surpassing that of CT.

Animals↗
PubMed1982

Proton nuclear magnetic resonance imaging of regionally ischemic canine hearts: effect of paramagnetic proton signal enhancement.

In a study to evaluate the potential of proton nuclear magnetic resonance (NMR) imaging with and without manganese contrast with and without manganese contrast enhancement for detecting acute myocardial infarction, 12 dogs underwent 90-minute occlusion of the left circumflex coronary artery. Transverse-section NMR images of the excised, nonbeating heart were obtained at 1-cm intervals using the steady-state-free-precession (SSFP) technique. All NMR images revealed detailed structure of the heart. The three hearts without manganese showed no difference in intensity between the normal and the ischemic posterior regions, whereas those with manganese demonstrated a clearly demarcated zone of reduced signal intensity consistent with the ischemic zone. It is concluded that high-resolution tomograms of the excised canine myocardium can be obtained using proton NMR imaging. With the SSFP imaging technique, proton signal enhancement with manganese infusion is necessary to differentiate between ischemic and nonischemic myocardium after 90 minutes of coronary occlusion.

Animals↗
PubMed1982

NMR imaging of forearms in healthy volunteers and patients with giant-cell tumor of bone.

Serial proton nuclear magnetic resonance (NMR) images of distal upper extremities were obtained in four healthy volunteers and four patients with giant cell tumor of the distal radius. The steady-state-free-precession (SSFP) data collection technique and an 8-cm bore superconducting magnet (1.44 tesla) were used. All images demonstrated high spatial resolution and excellent soft-tissue contrast. In patients with giant cell tumor, the NMR images revealed bone marrow replacement by tumor, cortical bone thinning, and cortical bone destruction. The extent of tumor involvement was clearly delineated by the NMR images and corresponded to radiographic and surgical findings. NMR signal intensity was lower in tumors, suggesting altered relaxation times. These findings demonstrate that proton NMR imaging can provide high-resolution images of extremities and detect tumors by changes in both anatomic structure and relaxation times.

Adult↗
PubMed1982

Quantification of experimental myocardial infarction using nuclear magnetic resonance imaging and paramagnetic ion contrast enhancement in excised canine hearts.

Determination of myocardial infarct size is important for clinical management of patients with ischemic heart disease and for research on limiting infarct size. Nuclear magnetic resonance (NMR) imaging permits tomographic depiction of the distribution of mobile tissue protons. NMR images have demonstrated high spatial resolution and contrast. To evaluate the potential of this technique in measuring myocardial infarct size, NMR imaging was performed in six canine hearts excised 24 hours after circumflex coronary artery ligation. Before sacrifice, the dogs received i.v. manganous chloride (0.05 mmol/kg). After NMR imaging, the heart were sectioned and the myocardial slices were stained with triphenyl tetrazolium chloride. The pathologically determined infarct size was compared with the infarct size measured by NMR imaging. The correlation was good (regression line slope 1.06; r = 0.94). We conclude that NMR imaging with paramagnetic contrast agents can be used to determine infarct size in excised hearts.

Animals↗
PubMed1979

An in vivo study of the fore-arm and hand by thin section NMR imaging.

A series of transverse thin section NMR images of the living fore-arm and hand is compared with the morphology of corresponding cadaver sections. Each image is derived from the distribution of the density of mobile protons within the section. The contrast and spatial resolution achieved indicate the potential information that future whole-body systems could provide.

Forearm↗
PubMed1978

Internal structural mapping by nuclear magnetic resonance.

Nuclear magnetic resonance (NMR) is a well-established tool for studying the properties of materials at the molecular level. The technique has recently been applied to the internal morphological analysis of biological material by producing a series of thin cross-sectional images derived from the distribution of mobile protons. There are grounds for believing that NMR will be more than a mere alternative to computer tomography, for it may prove possible to achieve both a useful degree of tissue characterization through analysing components of the complex NMR signal and also an approach to the measurement of blood flow in vivo.

Humans↗
PubMed1978

A computer driven photoscanner for medical imaging.

A novel and versatile instrument for producing high quality monochrome and colour hard-copy of medical images from an array of digital information is described. Images are produced on standard photographic print paper mounted on the bed of a conventional X-Y plotter by scanning a time-modulated light source over the paper using a computer driven raster. A matrix board gives control of both greyscale and colour attribution. Examples of NMR images produced by the system are presented. A refinement of the technique which allows two variables to be displayed on one image is also described.

Color↗
PubMed1978

Display of cross sectional anatomy by nuclear magnetic resonance imaging.

High definition cross-sectional images produced by a new nuclear magnetic resonance (NMR) technique are shown. The images are a series of thin section scans in the coronal plane of the head of a rabbit. The NMR images are derived from the distribution of the density of mobile hydrogen atoms. Various tissue types can be distinguished and a clear registration of gross anatomy is demonstrated. No known hazards are associated with the technique.

Animals↗
PubMedDate not supplied

Proton NMR imaging in experimental ischemic infarction.

Proton nuclear magnetic resonance (NMR) images depict the distribution and concentration of mobile protons modified by the relaxation times T1 and T2. Using the steady-state-free-precession (SSFP) technique, serial coronal images were obtained sequentially over time in laboratory animals with experimental ischemic infarction. Image changes were evident as early as 2 hours after carotid artery ligation, and corresponded to areas of ischemic infarction noted pathologically. Resulting SSFP images in experimental stroke are contrasted to inversion-recovery NMR images in an illustrative patient with established cerebral infarction. Bulk T1 and T2 measurements were made in vitro in three groups of gerbils: normal, those with clinical evidence of infarction, and those clinically normal after carotid ligature. Infarcted hemispheres had significantly prolonged T1 and T2 (1.47 +/- .12 sec, 76.0 +/- 9.0 msec, respectively) when compared to the contralateral hemisphere (T1 = 1.28 +/- .05 sec, T2 = 58.7 +/- 3.9 msec) or to the other two groups. These data suggest that changes in NMR parameters occur and can be detected by NMR imaging as early as two hours after carotid artery ligation.

Animals↗