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Biomedical subjects

M Kormano

Publications and source records attributed to M Kormano.

At least 37 records · Page 2Linked to original sources
PubMed1996

Knee extension dynamometer: a new device for dynamic isokinetic magnetic resonance spectroscopy experiments.

In the present study we introduce a new device for exercise magnetic resonance spectroscopy (MRS). It operates in a standard whole-body scanner. Mechanical exertion unit allows maximal 10 degrees to 15 degrees short-arc knee extensions. The device operates hydraulically and is based on isokinetic movement. The force and work conducted are automatically controlled by the electronic control and computer unit. A small surface coil placed on the vastus medialis muscle allows the collection of spectra without interfering spectra from nearby resting muscles. The force used for the extensions can be followed simultaneously as a curve on the screen in the operator's room and the data is transferred to a personal computer for later analysis. Total work and fatigue percentage are also calculated by the device. It also allows the use of different isokinetic exercise protocols. The measurements of force proved reliable in repeat measurements using an isokinetic test device as a control. This device has been used clinically for over a year, is easy to operate, and offers reliable measurements. It is well suited to trials where muscle energy states versus time are followed since it allows noninvasive simultaneous quantification of muscle performance and collecting MRS spectra at rest, during exercise, and in the recovery phase.

Ergometry↗
PubMed1996

Magnetization transfer of pure DNA and purified sperm nuclei.

Magnetization transfer (MT) imaging provides a novel opportunity to characterize interactions between tissue water and macromolecules. Although several in vitro investigations have shown that proteins and lipids are important determinants of MT, the contribution of DNA is still unknown. This study was designed to determine whether DNA and cell nuclear material exhibit MT. We measured the magnetization transfer effect of pure DNA strands and purified bovine sperm head nuclei. Although no transfer of magnetization could be detected in samples of pure DNA strands, the sperm head nuclei exhibited a strong MT effect that increased with increasing solid content of the samples. Since the purified bovine sperm head samples consist of large nuclei with only minor traces of perinuclear matrix, the measured MT effect arises from the chromatin of the nuclei. The DNA fills 90% of the nuclear volume and it is extremely tightly packed as chromatin fibers by nucleoproteins. We hypothesize that the numerous intra- and intermolecular disulfide bonds that stabilize the chromatin fibers restrict the movement of the surface water binding sites of both DNA and protamines and thus facilitate the transfer of magnetization. Therefore, the results indicate that the amount of nuclear material may positively contribute to MT in tissues.

Animals↗
PubMed1996

Determination of saturation transfer parameters of human tissues in vivo.

In order to study the applicability of magnetization transfer contrast (MTC) to tissue differentiation, the determination of the magnetization transfer (MT) parameters of normal tissues is necessary for the evaluation of pathological conditions. The time-dependent saturation transfer technique was used to investigate the observed magnetization transfer parameters in several human tissues in vivo at 0.1 T. The length of the off-resonance saturation pulse varied from 0 to 750 ms. The magnetization transfer contrast (MTC) was 0.71 in striated muscle, 0.49 in liver, 0.49 in renal cortex, and 0.50 in spleen. The observed magnetization transfer rates (Rwm) were 5.5 s-1 for muscle, 3.1 s-1 for liver, and 1.5 s-1 for both renal cortex and spleen. Our results indicate that measuring Rwm and possibly other relaxation parameters could be useful in tissue differentiation.

Adult↗
PubMed1996

Dynamic Gd-DTPA-enhanced MR imaging of the kidney: comparison between T1- and T2-weighted sequences.

OBJECTIVE: To determine whether T1- or T2-weighted sequences are more informative and practical in dynamic Gd-DTPA-enhanced MR imaging for the evaluation of renal blood flow and function. MATERIALS AND METHODS: Dynamic Gd-DTPA-enhanced MR imaging of the kidney was performed in 7 patients by either T1-weighted TurboFLASH (TR/TE/TI/FA = 9/4/27/8) or T2-weighted FLASH (TR/TE/FA = 32/22/10) sequences for comparison of the enhancement pattern. None of the subjects had a suspicion of renal dysfunction from laboratory data, and the absence of renal artery stenosis was confirmed by conventional angiography. RESULTS: During the early phase, the marked signal increase in T1-weighted imaging in the renal cortex corresponded to a similar marked decrease in signal intensity in T2-weighted imaging. During the middle and late phases, the medulla was dramatically decreased in intensity on the T2-weighted imaging resulting in a good contrast between the cortex and medulla. CONCLUSION: Both sequences may provide almost similar information about the renal cortical blood flow. However, T2-weighted dynamic MR imaging may be more informative than T1-weighted dynamic MR imaging about the concentrating ability in the renal medulla. A high concentration of Gd-DTPA in the tubular structure was suspected to cause a dramatic decrease in intensity in the medulla in T2-weighted imaging.

Adult↗
PubMed1996

Upper airway size and collapsibility in snorers: evaluation with digital fluoroscopy.

This study addressed the question of whether there are any differences in the size and collapsibility of the upper airway measured by digital fluoroscopy, between snorers and controls whilst they were awake and breathing normally; and whether there are any correlations between these measurements and other clinical data. The dynamic changes of the upper airway size were evaluated using digital fluoroscopy in 33 patients and 16 normal controls. The measurements were compared with findings in an overnight sleep study, including a static-charge-sensitive bed (SCSB) and oximeter recordings. The minimum anteroposterior dimension at the velopharyngeal level was smaller in patients with partial upper airway obstruction than in controls (p<0.005); patients with complete obstruction did not differ from the controls. The velopharyngeal airways were also more collapsible in patients with severe partial obstruction (p<0.01) than in controls. At the oropharyngeal and hypopharyngeal levels, the dimensions and the collapsibilities were similar in patients and controls. The velopharyngeal collapsibility correlated with body mass index (p<O.001), whereas the airway size did not. The velopharyngeal collapsibility was more pronounced in patients with frequent episodes of arterial oxyhaemoglobin desaturation during sleep. Velopharyngeal collapsibility associated with high body mass index was the important determinant of nocturnal breathing disturbances. Digital fluoroscopy displays the dynamic changes of the upper airways throughout the respiratory cycle.

Adult↗
PubMed1995

Cross-sectional areas of lumbar muscles after surgical treatment of lumbar disc herniation. A study with magnetic resonance imaging after microdiscectomy or percutaneous nucleotomy.

We assessed in this study the potential development of postoperative muscle atrophy in the operation area in 39 patients treated by either microdiscectomy or percutaneous nucleotomy for lumbar disc herniation. The cross-sectional areas of the lumbar muscles were measured on magnetic resonance images created on the day preceding the operation and 6 months postoperatively. The cross-sections of the lumbar muscles remained unchanged during the observation period in all treated patients indicating that no muscle atrophy had developed in the operation area. Since peroperative tissue trauma may correlate with subsequent muscle denervation and atrophy, this finding may be due to the tissue sparing nature of microdiscectomy and percutaneous nucleotomy, thus encouraging the use of these techniques in the treatment of lumbar disc herniation.

Adult↗
PubMed1995

Low field MRI and scaphoid fracture.

18 consecutive patients suspected of and treated for an acute scaphoid fracture were examined by lowfield MRI. This showed 11 fractures while seven scaphoids were considered normal. T1 weighted images showed a fracture as an area of decreased signal intensity. Two radiologically obvious fractures produced normal MR images. These fractures proved to be the result of old trauma. A wide spectrum of additional traumatic lesions in the wrists, not detected by routine X-ray analysis, were also demonstrated. These included seven fragmented triangular fibrocartilages (TFC), torn scapho-lunate ligaments in four cases and one torn triquetro-lunate ligament. Bone bruises of other carpal bones and seven other carpal fractures were also detected. Low field MRI can be used to show scaphoid fractures and allows diagnosis of additional or simulating lesions.

Adolescent↗
PubMed1995

Magnetization transfer in protein solutions at 0.1 T: dependence on concentration, molecular weight, and structure.

RATIONALE AND OBJECTIVES: We observed the magnetization transfer rates in a variety of protein solutions at 0.1-T magnetic field and compared our results with previous investigations at high magnetic fields (> 0.5 T). The effects of protein concentration, size, pH, denaturation, cross linking, and fiber formation were investigated. METHODS: We used the saturation transfer technique to determine the transfer of magnetization in gamma globulin, fibronectin, collagen, fibrinogen, and albumin solutions. RESULTS: The observed transfer rate increased with increasing concentration and size of the protein. Protein degradation decreased the transfer rate. Cross linking and fiber formation each increased the transfer rate, whereas buffer pH had no effect. CONCLUSION: Protein denaturation, aggregation, and fiber formation are important determinants of magnetization transfer in vitro. The size, concentration, and cross linking of the proteins contribute strongly to the transfer of magnetization at low fields, and the effect seems to be at least as important as at the higher fields.

Hydrogen-Ion Concentration↗
PubMed1995

Experiences with a teleradiology system in pulmonary diseases.

Chest radiographs of 43 patients were digitized and sent from Paimio Hospital to Turku University Central Hospital. Fifteen of the patients had a pneumothorax, 12 had interstitial lung disease and 16 were controls. The images were interpreted by 5 radiologists during their duty shift. The first reading session consisted of images with 1,024 x 1,024 pixel resolution and the second of images with 2,048 x 2,048 matrix followed by the original chest radiographs. ROC studies were performed from the answers based on a 5-point confidence scale. In the pneumothorax group the average area under the individual ROC curve was 0.928 with the 1,024 x 1,024 matrix and 0.983 with the 2,048 x 2,048 matrix. In the fibrosis group the average area under the individual ROC curve was 0.877 with the 1,024 x 1,024 matrix and 0.831 with the 2,048 x 2,048 matrix. The results suggest that the 1,024 x 1,024 matrix is adequate in the detection of pneumothoraces and fibrosis.

Evaluation Studies as Topic↗
PubMed1994

Magnetic resonance image changes and clinical outcome after microdiscectomy or nucleotomy for ruptured disc.

Preoperative and postoperative magnetic resonance imaging (MRI) of the lumbar spine was performed on 41 patients treated either microsurgically or with percutaneous nucleotomy for lumbar disc herniation. On the first postoperative day, MRI revealed an edematous mass effect at the level of surgery in 25 (61%) patients. The mass effect caused compression of the anterior dural sac mimicking preoperative disc herniation. After the follow-up of 6 months, the mass effect had disappeared in all patients, and the MRI finding in the operated disc space was that of a prolapse in six (15%) patients and that of a protrusion in 16 (39%) patients. Postoperative scarring was detected in 23 (56%) patients. The amount of the epidural scar tissue was significantly (p = 0.0002) associated with the extent of the early postoperative hemorrhagic changes detected in these patients with MRI. No association was observed between these MRI findings (mass effect, disc herniation, epidural scarring) and the clinical outcome of the patients.

Adult↗
PubMed1994

Teleradiology in Turku University Hospital--diagnostic evaluation and clinical applications.

Teleradiology installation between the Radiology Departments of the Main Hospital Compound and the Paimio Hospital, both belonging to the Turku University Central Hospital has been in clinical use since August 1991. It is based on Unix workstations with 1280 x 1024 pixel display with 216 shades of gray. It has been used to receive previous chest images from Paimio to be compared with recent films taken at TUCH Emergency Department. Scanning resolution of 1024 x 1024 pixels seems to be enough for reference images and probably sufficient for most other purposes.

Computer Terminals↗
PubMed1994

X window system based user interface in radiology.

A teleradiology system was designed for image transfer between two hospitals. One of the main challenges of the work was the user interface, which was to be easy to operate and to learn, and was equipped with useful functions for image manipulation and diagnosing. The software tools used were the Unix operating system (HP-UX v.7.0), C programming language and the X Window System (or simply X). The graphical user interface (GUI) was based on OSF-Motif standard, and it was developed by using the HP-Interface Architect. Both OSF-Motif and HP-Interface Architect are based on X. The results of the development project were installed for clinical use in the Turku University Central Hospital. The work demonstrates, that the X Window System has useful and advantageous features for radiology department's computer network environment.

Computer Communication Networks↗