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Biomedical subjects

M Kormano

Publications and source records attributed to M Kormano.

At least 55 records · Page 3Linked to original sources
PubMed1993

Magnetic resonance imaging of the discs and trunk muscles in patients with chronic low back pain and healthy control subjects.

This study aimed to evaluate the lumbar intervertebral discs and the maximum isometric strength and size of the trunk muscles of middle-aged healthy volunteers (60 persons) and low back pain patients (48 persons). Disc degeneration was more frequently seen in the patients than in the healthy volunteers. The psoas and back muscles (erector spinae and multifidus) of the patients were smaller than those of the volunteers. Patients had also more fat deposits in the back muscles than controls. The maximum isometric strength of trunk muscles of the patients was on average weaker than that of the volunteers. However, the size of the back muscles was not related to the maximum isometric extension strength of the trunk.

Adipose Tissue↗
PubMed1993

Computed tomography of liver tumors.

Computed tomographic (CT) scan acquisition speed, interscan delay time, and image quality have significantly improved during the past decade. Thus CT has become a standard against which newer techniques such as magnetic resonance imaging (MRI) are validated. Comparison between CT and other modalities, however, lack validity unless the protocol for each procedure is optimized. The authors emphasize the importance of correct CT contrast enhancement techniques in order to obtain reproducible and optimal anatomical information for defining liver tumor morphology, which will determine resectability. Three-dimensional reconstruction using contiguous volume imaging with appropriate enhancement of vessels and tumor also provides important preoperative evaluation for possible resection. Analysis of the hemodynamic status of the liver parenchyma and of the lesions within it is also possible with contrast-enhanced CT although rarely practiced. With appropriate scanning techniques, excellent anatomical and functional information is obtained simultaneously using CT, although histologic specificity often remains insufficient without biopsy.

Humans↗
PubMed1993

Magnetization transfer imaging of normal and abnormal liver at 0.1 T.

RATIONAL AND OBJECTIVES: Magnetization transfer (MT) contrast is a new technique that may improve contrast in magnetic resonance imaging. High-protein tissues have a greater MT effect, resulting in a decrease in signal intensity. This study evaluates the MT technique on normal and abnormal liver tissue on a low-field system. The magnitude of the magnetization transfer was studied to determine its effect on image visualization and tissue characterization. METHODS: Ten volunteers and 25 patients with benign and malignant liver pathology, including left lateral segment hepatectomy, were imaged on a 0.1 T system. Gradient-recalled-echo T2-weighted sequence pairs were obtained with and without MT pulse saturation. Signal intensity measurements were made using region-of-interest tracings in liver, spleen, skeletal muscle, fat, and selected liver pathology. Liver-to-lesion contrast ratios and conspicuity changes were analyzed. RESULTS: The average signal intensity decrease for normal liver was .27. Skeletal muscle demonstrated the greatest MT effect (.48), while fat showed minimal (.01) MT change. Two hemangiomas and two liver cysts showed a small MT effect (.13 and .02, respectively). Of the malignant lesions imaged, melanoma metastases showed a mean MT effect of .34, while hepatomas showed mean effect of .15. Edematous liver tissue had an intermediate mean effect of .18. CONCLUSIONS: While T2 sequences are more versatile for standard liver imaging, an MT sequence may be helpful for tissue characterization in specific imaging situations. Melanoma metastases and hepatomas demonstrated significant MT effect and increased conspicuity of the malignant lesions.

Adult↗
PubMed1993

MR relaxation times and fiber type predominance of the psoas and multifidus muscle. An autopsy study.

MR relaxation times, fiber composition, nonmyofiber space, water content, and fat content of human psoas and multifidus muscle samples of 10 male cadavers were studied in vitro. The T1 and T2 relaxation times of multifidus muscle were significantly longer than those of the psoas muscle. On average, type 1 fibers (slow fibers with a small cross-sectional diameter) predominated in both muscles. There was no correlation between the relative mass of type 1 or 2 fibers (fast fibers with a large cross-sectional diameter) or nonmyofiber space and the relaxation times. The quantity of fat in the muscle did not correlate with the relaxation times either.

Adolescent↗
PubMed1992

Breast coil design for low-field MRI.

Four double-breast coils were designed for the low-field resistive magnet MR imaging of female breasts at 0.02, 0.04, and 0.1 T. The signal-to-noise ratio is optimized by shaping the coils, by constructing two different size coils at 0.02 T, and by using special wire for the turns of the solenoidal coils. The approximate linear dependence of the SNR on the Larmor frequency is estimated.

Breast↗
PubMed1992

Nordic teleradiology development.

In the Nordic countries there are several reasons why teleradiology has been an interesting topic of research during the last years. The distances in rural areas are long, and radiology expert service is not available in every health centre which is able to provide X-rays. Also, the telecommunication network is on a very advanced level in the Nordic countries. The staff is well educated and they are used to operating with computers. This all means that the infrastructure to develop and use systems like teleradiology exists. This paper describes two separate systems developed in Norway and Finland. Their development has been in many respects the same. The common hardware and software features, as well as the differences and the clinical experiences, are discussed in this paper.

Computer Systems↗
PubMed1992

Lumbar disc and back muscle degeneration on MRI: correlation to age and body mass.

Lumbar intervertebral discs and paraspinal muscles in 74 healthy volunteers ranging in age from 19 to 74 years were evaluated with MRI, and the occurrence of degeneration was correlated to age and body mass. Muscle size and the amount of fat in the muscles was studied from MRI cross sections. When the back muscles were degenerated, they were small and contained fat deposits. By contrast, the psoas muscles never showed gross fat deposits. Degeneration of both the lumbar discs and muscles increased with age. No correlation was found between muscle degeneration and overweight. Muscle degeneration is as common as disc degeneration in the lumbar area. MRI is an excellent method to assess both muscle and disc degeneration.

Adipose Tissue↗
PubMed1992

T1 in subacute and chronic brain infarctions. Time-dependent development.

RATIONALE AND OBJECTIVES: Time-dependent behavior of T1 in brain infarcts and in brain tissue of the contralateral hemisphere was studied in the subacute and early chronic stages of stroke. METHODS: T1 was measured from magnetic resonance images (MRIs) of 29 patients as a function of infarct location and age. Another group of 11 patients was studied with consecutive MRI studies during the first 5 weeks after the onset of infarct, and the distribution of T1 in the infarctions was analyzed from T1 maps using a histographic method. RESULTS: During the first 2 months after a stroke, T1 was longer in the infarcted gray matter than in the infarcted white matter (P = .002), and prolonged linearly in both. The histographic analysis showed a component arising from tissue breakdown products that could be identified for up to 5 weeks. A transient lengthening in T1 of the contralateral hemisphere, reaching a maximum at 3 weeks, also was observed. CONCLUSIONS: These characteristics of recent infarctions differentiate them from older, gliotic lesions. The lengthening of T1 in the contralateral hemisphere may reflect remote flow and metabolic effects of brain infarctions.

Acute Disease↗
PubMed1991

Magnetic field dependence of longitudinal relaxation rates of solutions of various protein-gadolinium3+ chelate conjugates.

Bovine serum albumin (BSA) and porcine serum fibrinogen (FIB) were multiply labeled with gadolinium3+ by using three different ligands: DTPA dianhydride, isothio-cyanato-benzyl-DTPA (ITCB-DTPA), in which none of the five coordinating carboxylates is employed for macromolecular linkage, and isothiocyanatobenzyl-TRITA, a macrocyclic ligand. The nuclear magnetic resonance dispersion (NMRD) profiles of the protein-(Gd chelate) conjugates were characteristic to each chelate involved, possessing, as expected, greater longitudinal relaxivities than the corresponding Gd chelates alone and exhibiting prominent peaks at the proton Larmor frequency range of 10 to 40 MHz. Particularly favorable relaxation enhancement was measured in the solutions of BSA-(ITCB-DTPA-Gd) at this field range. When the number of chelates conjugated with protein increased, up to 163 Gd chelates per one fibrinogen, a progressive decrease in relaxivity was observed. This study demonstrates the relaxation properties of novel macromolecular contrast agents designed for magnetic resonance imaging.

Animals↗
PubMed1991

Disc degeneration in magnetic resonance imaging. A comparative biochemical, histologic, and radiologic study in cadaver spines.

Magnetic resonance imaging (MRI) findings of 89 autopsied intervertebral discs from 22 cadaveric lumbar spines were correlated with biochemical composition, conventional radiography, and histologic structure to study the nature of disc intensity changes seen in MRI. Discs with a low signal intensity on T2-weighted MRI were characterized by shortening of relaxation times, dehydration, and decreases in total proteoglycan content and chondroitin-keratan sulfate ratios in the nucleus pulposus. This corresponded well with previously published studies. In histologic structure, no obvious differences between MRI findings were found. In conclusion, a low signal intensity in a lumbar disc on T2-weighted MRI probably reflects a true biochemical disc degeneration, but its relation to structural degenerative changes is uncertain. Therefore, MRI seems to be a sensitive and a specific imaging modality for detecting pathologic biochemical disc changes in the spine of a young adult.

Adult↗
PubMed1991

MR imaging of patellar cartilage degeneration at 0.02 T. Study of 23 cadaveric patellae.

MR imaging with a 0.02 T resistive magnet was used to establish the correlation between the histologic grading of patellar cartilage degeneration and fat water separation images or T1- and T2-relaxation times. We examined 23 cadaveric patellae. There was a positive correlation between histologically graded cartilage degeneration and T1-relaxation time. Patellar cartilage was well differentiated from surrounding structures on chemical shift water proton images, and an evaluation of cartilage degeneration was possible. No correlation was found between cartilage damage and T2-relaxation time. Chemical shift imaging at 0.02 T is easy to perform and gives further information of cartilage disorders.

Adult↗
PubMed1990

Proton relaxation enhancement of albumin, immunoglobulin G, and fibrinogen labeled with Gd-DTPA.

Bovine serum albumin, immunoglobulin G, and fibrinogen were labeled with Gd-DTPA using a bifunctional chelating agent DTPA anhydride. The protein-(Gd-DTPA) conjugates had 1.4- to 2.0-fold greater longitudinal relaxivities at 0.02 and 0.44 T than the relaxivity of plain Gd-DTPA. The increase of longitudinal relaxivity was not directly related to the size of carrier protein. Up to 50 Gd-DTPA chelates per protein, longitudinal relaxivity of the conjugates was proportional to the concentration of Gd and independent of the Gd/protein ratio.

Animals↗