Digital imaging of dose distributions using NMR imager.
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Gels↗
Biomedical subjects
H Ikehira
Publications and source records attributed to H Ikehira.
[Development of a gel phantom for dose distributions by MR imager].
We reported a method of determining spatial dose distributions in tissue-equivalent phantoms using nuclear magnetic resonance imaging. To make a gel phantom, a cross-linked dextran gel (Sephadex G-200) was used as fixation agent of a ferrous sulphate solution. Although high quality images are obtained, the cost is very expensive to make the gel. We developed a new gel which is combined with an extra water absorbent polymer (Sumikagel N-100) and Sephadex G-200. The gel permits the determination of dose distributions for three dimensional treatment planning.
Ferrous Compounds↗
High-energy phosphate metabolism of the myocardium in normal subjects and patients with various cardiomyopathies--the study using ECG gated MR spectroscopy with a localization technique.
Nuclear magnetic resonance spectroscopy (MRS) is a new technique for the evaluation of myocardial metabolism. Recently, localized MRS has been clinically available to measure by a non-invasive method the relative concentrations of the high-energy phosphate metabolites in the myocardium. We performed ECG gated P-31 MRS using ISIS (image-selected in vivo spectroscopy) in 15 normal volunteers, 12 patients with hypertrophic cardiomyopathy, 12 with left ventricular hypertrophy, 6 with dilated cardiomyopathy and 11 with specific heart muscle disease. Myocardial peak height ratios of PCr/gamma-ATP, Pi/gamma-ATP and PCr/Pi were measured. Myocardial P-31 MRS demonstrated a significant decrease in the ratio PCr/ATP in patients with hypertrophic cardiomyopathy and specific heart muscle disease as compared with normal subjects, indicating myocardial metabolic disturbance in these patients. The ratio of PCr/ATP in patients with dilated cardiomyopathy did not differ significantly from that of normal subjects. However, exercise MRS revealed a marked decrease of PCr peak in an asymptomatic patient with dilated cardiomyopathy, which may indicate a latent metabolic disturbance in the myocardium of dilated cardiomyopathy.
Adenosine Triphosphate↗
[Magnetic resonance imaging in multiple system atrophy].
We studied 18 patients with multiple system atrophy (MSA) by high field strength MRI: 6 striatonigral degeneration (SND), 4 Shy-Drager syndrome (SDS), and 8 olivo-ponto-cerebellar atrophy (OPCA). We also studied 30 Parkinson's disease (PD) and 10 age-matched controls. The diagnoses of SND, SDS, and OPCA were based on criteria after Hirayama et al (1985). Bradykinesia, rigidity, and tremor were assessed with the summed scores of the signs used as the extrapyramidal scores. The mean extrapyramidal scores were not significantly different in patients with SND, SDS, OPCA, and PD. MRI studies were performed on 1.5 tesla MRI unit, using a T2 weighted spin echo pulse sequence (TR2500 ms/TE40 ms). The width of the pars compacta signal in all subjects was measured by the method of Duguid et al (1986). Intensity profiles were made on a straight line perpendicular to the pars compacta through the center of the red nucleus on an image of the midbrain. We measured the width of the valley at half-height between the peaks of intensity representing the red nucleus and the crus cerebri-pars reticulata complex and used this measurement as an index of the width of the pars compacta signal. The mean widths of the pars compacta signal were: 2.8 +/- 0.4 mm (SND), 2.8 +/- 0.7 mm (SDS), 3.6 +/- 0.6 mm (OPCA), 2.7 +/- 0.3 mm (PD), and 4.3 +/- 0.6 mm (control). The mean widths of the pars compacta signal in PD, SND, and SDS were significantly narrower than that in the control group (p < 0.05), while the OPCA group was not significantly narrower.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Intramuscular degeneration process in Duchenne muscular dystrophy--investigation by longitudinal MR imaging of the skeletal muscles].
Intramuscular degeneration process of Duchenne dystrophy skeletal muscles was investigated by longitudinal skeletal muscle imaging with high-field-strength NMR-CT of 1.5 Tesla. Thigh muscles in 10 cases ranging in age from 4 to 19 years were examined by T1-weighed longitudinal images (TR = 215-505 ms, TE = 19-20 ms). Following results were obtained: (1) Skeletal muscle degeneration was depicted as high signal intensity area reflecting its high fat contents. (2) These high signal intensity areas had a longitudinally streaky appearance in parallel direction with myofibers. (3) These findings were more prominent toward myotendon junction than muscle bellies. (4) Skeletal muscle degeneration progressed rapidly between 7 to 10 years of age, and reached a plateau after that.
Adult↗
Quantitative measurement of uptake of radiolabeled monoclonal antibody by means of planar data.
Data obtained from planar images were used to measure the uptake of monoclonal antibody in organs and tumors. Background counts included in the region of interest were eliminated, and the attenuation of the photons emitted by the radionuclide through the intervening tissues was compensated for. The background counts and the intensity of the attenuation were determined from the results of phantom studies and numerical integration with a personal computer. The quantitative uptake of 111In labeled anti-melanoma Monoclonal Antibody (ZME-018) in a melanoma lesion, the liver, and the bone marrow of a patient was measured by the planar method which we developed.
Antibodies, Monoclonal↗
Study of biodistribution of enflurane in rats with in vivo 19F MRI.
In vivo 19F magnetic resonance imaging (MRI) of anesthetized rats enabled us to visualize the biodistribution of fluorinated anesthetics and to document the changes in MR signals in the body during the induction and the elimination phase of anesthesia. The authors examined in vivo 19F MRI in rats anesthetized with concentrations of 1.75-2.0% enflurane and demonstrated its in vivo distribution with concomitant 1H and 13C MRI to verify the anatomical correlation. Distinct 19F MR signals were acquired predominantly from the systemic adipose tissue and the liver. Additionally, the temporal changes in the tissue during and after anesthesia were characterized with in vivo 19F MRI in 6.4 min of the acquisition time. The 19F MR signals increased with time after anesthesia; however, the signals from the adipose tissue were apparently stronger than those from the liver. Following the discontinuation of inhalation, the MR signals in the liver decreased far more rapidly than those from the adipose tissue. When the animal woke up and began to move, the MR signals were still visible in the adipose tissue. These results confirmed the fact that enflurane dissolves preferentially in the adipose tissue and remains when the anesthetic effect disappears. Additionally, 19F MR signals of the liver during the elimination phase might reflect the concentration of enflurane in the blood.
Abdomen↗
In vivo sodium-23 MRI in brain tumors: evaluation of preliminary clinical experience.
In vivo sodium-23 magnetic resonance (MR) imaging in the head was performed in ten normal volunteers and six patients with brain tumors on a commercially available 1.5 Tesla whole-body MR system. Although sodium MR signal from the brain parenchyma could hardly be detected on routine spin echo (SE) pulse sequence, free induction decay (FID) image with echo time of 1.9 msec demonstrated MR signal in the normal brain tissue. On the other hand, extracellular sodium of cerebrospinal fluid, large venous sinus, and vitreous humor offered high sodium MR signal intensity due to the quantity of sodium and the relatively longer transverse relaxation time (50-60 msec) compared to that of intracellular sodium (less than a few msec). Strong signal was obtained in gliomas with superior contrast, though the delineation of the tumor tissue from edema was as difficult as when seen on proton T2 weighted SE image. Meningioma itself gave much less of a sodium MR signal compared to glioma. Peritumoral edema associated with meningioma showed a markedly high sodium MR signal which was more prominent adjacent to the tumor, although proton SE image revealed the peritumoral edema as homogeneous. Pathological tissues such as brain tumors and edema could be readily depicted as significantly high sodium-23 MR signal, apparently different from normal brain tissues. The current status of in vivo sodium MR imaging is discussed. The authors concluded that early clinical experience of in vivo sodium-23 MR imaging brought promising results in the evaluation of brain tumors and edema; otherwise, discrimination and quantification of multiple T2 components and the improvement of spatial resolution are desperately needed.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[The development of clinical high tesla MRI/S system].
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Animals↗
[31P-MRS (brain tumors)].
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Brain Neoplasms↗
[MRI in Parkinson's disease and vascular parkinsonism--study on the lesion of substantia nigra].
We examined the magnetic resonance (MR) image of midbrain and striatum in 30 patients with Parkinson's disease (PD), 10 patients with vascular parkinsonism (VP) and 10 age-matched control subjects. Studies were performed on a high field strength (1.5 tesla) MRI unit. T2 weighted spin echo pulse sequence (TR2500ms/TE40ms) was used. We measured the width of the pars compacta signal in patients and controls on the basis of the method described by Duguid et al. Intensity profiles of a straight line perpendicular to the pars compacta through the center of the red nucleus were made on an image of the midbrain. We measured the width of the valley at half-height between the peaks of intensity representing the red nucleus and the crus cerebri-pars reticulata complex and used this as an index of the width of the pars compacta signal. The results were as follows: 1. The mean width of the pars compacta signal was 2.7 mm (SD = 0.3) in the PD group and 4.3 mm (SD = 0.6) in controls. The difference between the means was highly significant (p less than 0.01). While not significant statistically, there was a trend toward narrowing of the width of pars compacta signal of substantia nigra in the PD group as the Yahr's grade or disease duration progressed. In hemiparkinsonism, MRI revealed significant narrowing of the pars compacta signal on the contra-lateral side to the clinical predominant side compared with the ipsi-lateral side. 2. The mean width of the pars compacta signal was 3.9 mm (SD = 0.4) in the VP group, but the decrease was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
In vivo 13C imaging enhanced by polarization transfer.
Carbon-13 NMR imaging has been combined with 1H-13C polarization transfer to improve image quality. Natural-abundance carbon images of Fischer rat bodies were obtained within a few minutes. Next 13C-labeled glucose was administered orally to rats, and spatial distributions of glucose and its derivatives were observed with this technique.
Animals↗
Magnetic resonance imaging of the cardiovascular system: application in function and tissue characterization.
Magnetic resonance imaging (MRI) is a new noninvasive technique for visualization of the cardiovascular system, and is used to evaluate tissue characteristics, cardiac function and blood flow abnormalities, as well as to obtain morphological information. In this paper we presented results of clinical and laboratory research obtained using conventional spin echo MRI with regard to cardiovascular anatomy, tissue characterization and physiology. Furthermore, experience with two new techniques, cine-MRI and volume-selected MR spectroscopy, and their potential clinical usefulness in detecting cardiovascular diseases are documented.
Cardiovascular Diseases↗
Carbon-13 NMR imaging study of in-vivo glucose metabolism.
Carbon-13 NMR spectroscopy and chemical shift selective imaging studies of in vivo glucose metabolism were performed at 2.0 T. Some metabolite peaks were observed in 13C NMR spectra, and carbon NMR imaging focused in the spectral region attributed to D-1-13C-glucose were also performed. A 13C NMR signal accumulated in the liver was detected and the average time resolution of these spectra and images were 10 and 30 minutes, respectively.
Animals↗
Duchenne muscular dystrophy carriers. Proton spin-lattice relaxation times of skeletal muscles on magnetic resonance imaging.
By means of magnetic resonance imaging (MRI), the proton spin-lattice relaxation times (T1 values) of the skeletal muscles were measured in Duchenne muscular dystrophy (DMD) carriers and normal controls. The bound water fraction (BWF) was calculated form the T1 values obtained, according to the fast proton diffusion model. In the DMD carriers, T1 values of the gluteus maximus and quadriceps femoris muscles were significantly higher, and BWFs of these muscles were significantly lower, than in normal control. Degenerative muscular changes accompanied by interstitial edema were presumed responsible for this abnormality. No correlation was observed between the muscle T1 and serum creatine kinase values. The present study showed that MRI could be a useful method for studying the dynamic state of water in both normal and pathological skeletal muscles. Its possible utility for DMD carrier detection was discussed briefly.
Adult↗
[Imaging of malignant melanoma with In-111-labeled monoclonal antibody (ZME-018) and Ga-67 scintigraphy].
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Antibodies, Monoclonal↗
Proton spin-lattice relaxation time of Duchenne dystrophy skeletal muscle by magnetic resonance imaging.
By means of proton MRI, the spin-lattice relaxation times (T1 values) of pelvic and leg muscles were measured in Duchenne muscular dystrophy (DMD) patients and normal controls. The bound water fraction (BWF) was calculated from the T1 value obtained. In normal children, the T1 value decreased, and BWF increased with age. In DMD, the T1 value rapidly decreased, from an abnormally high value in the early stages, with the progress of the disease. This reduction of the T1 value in DMD was not the same for all muscles; it was most prominent in the gluteus maximus and least prominent in the sartorius and gracilis muscles. BWF was below normal in the early stages of DMD. It is suggested that both regenerating and degenerating muscle fibers, together with the increased muscle water content, cause the high T1 value and low BWF in the early stages of DMD, whereas replacement of muscle by fat causes the decreased T1 value in the advanced stages.
Child↗
Fundamental tumor perfusion analysis with nuclear magnetic resonance imaging using gadolinium-diethylene triamine pentaacetic acid.
The measurement of blood perfusion is an important factor for both the diagnosis and follow-up of tumor lesions. However, noninvasive detection of this local blood flow factor is very difficult. To accomplish this, we tried to calculate tissue blood perfusion indexes with nuclear magnetic resonance imaging using gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA). We experimentally applied this method to C3H mouse's tumor NFSa (fibrosarcoma) and its recurrence tumor R1137, whose experimental hypoxic cell fraction is different; that is, R1137 is more oxic than NFSa. Imaging pulse sequence was T1 (TR = 1,000 ms, TI = 300 ms), and longitudinal relaxation rate (R1 = 1/T1) values were calculated. Injected dose of Gd-DTPA was 0.1 mmol/kg. The T1 images produced are from both the preinjection period from every 5 min postinjection for 30 min. Using two-exponential analysis and compartment analysis we calculated two fundamental parameters: uptake index and flow index as blood perfusion factors. We found that this method has the possibility of differentiating the tissue's hypoxic cell fraction and is effective both for follow-up study after radiation therapy and for tissue characterization.
Animals↗