'Wind-up' in Parkinson's disease: A functional magnetic resonance imaging study.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder mainly marked by selective degeneration of dopaminergic neurons that leads to disabling motor and cognitive impairment. This condition is less widely appreciated as a disease associated with a substantial variety of pain syndromes, although the prevalence of pain is relatively high. Repeated painful stimulation of peripheral nerves can cause pain 'wind-up' if the frequency of the stimulation is adequate and specifically stimulates the afferent C-fibres. We presumed that in case of PD, pain or pain severeness might be frequently caused by the aggravation of the 'wind-up' phenomenon due to any central or peripheral lesions or functional alterations. METHODS: To test for this hypothesis, we compared three groups (patients with left- and right-dominant PD and control subjects) using functional magnetic resonance imaging and thermally induced pain. RESULTS: Patient showed higher average 'wind-up' scores, compared to the healthy subjects, with lower values on the more affected sides compared to the less affected ones. In group level comparisons, patients had higher activation during 'wind-up' compared to control subjects in two main areas; these were the posterior division of cingulate gyrus and the precuneus cortex. In case of patients, further analyses showed that applied heat pain on the less affected side elicited higher activation in the supramarginal and postcentral gyri. CONCLUSIONS: These differences may arise from the deficiency in the efferent information, as well as the alterations in the central processing. It is highly likely that both processes contribute to this phenomenon simultaneously.

Cortical involvement during myotonia in myotonic dystrophy: an fMRI study.

OBJECTIVE: Myotonic dystrophy type 1 (DM1) is a common adulthood muscular dystrophy, characterized by muscle wasting, myotonia, and multisystemic manifestations. The phenomenon of involuntary muscle contraction during myotonia offers a unique possibility of investigating brain motor functions. This study explores cortical involvement during grip myotonia in DM1. MATERIALS AND METHODS: Sixteen DM1 patients were enrolled in the study. Eight patients had apparent grip myotonia, while eight patients did not (control subjects). All patients underwent functional MRI grip task examination twice: prior a warm-up procedure (myotonia was elicited in patients with apparent grip myotonia) and after a warm-up procedure (myotonia was attenuated in patients with apparent grip myotonia). No myotonia was elicited during either examination in patients without apparent grip myotonia. Cerebral blood oxygen level-dependent (BOLD) signals were compared both between groups with and without apparent myotonia, and between pre- and post-warm-up sessions. RESULTS: Significantly higher BOLD signal was found during myotonia phase in patients with apparent grip myotonia compared to corresponding non-myotonia phase of patients without apparent grip myotonia in the supplementary motor area and in the dorsal anterior cingulate cortex. Significant differences in BOLD signal levels of very similar pattern were detected between prewarm-up session myotonia phase and post-warm-up session myotonia absent phase in the group of patients with apparent grip myotonia. CONCLUSION: We showed that myotonia is related to cortical function in high-order motor control areas. This cortical involvement is most likely to represent action of inhibitory circuits intending motor termination.

A statistical model for intervertebral disc degeneration: determination of the optimal T2 cut-off values.

PURPOSE: The aim of this study was to investigate the possibility of quantitative classification in intervertebral disc degeneration using spin-spin relaxation time (T2) cut-off values with regard to morphological classifications. METHODS: Lumbar magnetic resonance (MR) imaging was performed on 21 subjects (a total of 104 lumbar disks). The T2 relaxation time was measured in the nucleus pulposus using a sagittal multi-echo spin-echo sequence. The morphological classification of disc degeneration was assessed independently by three experienced neuroradiologists according to the Pfirrmann and Schneiderman classifications. Receiver operating characteristic analysis was performed among grades to determine T2 cut-off values in each classification. Intra- and interobserver differences were calculated using kappa statistics. RESULTS: Moderate overall interobserver agreement was found between observers in both the Pfirrmann and Schneiderman classification schemes (kappa 0.46 and 0.51), while intraobserver reliability was substantial to almost perfect. The interobserver reliability was only fair in Pfirrmann grades III and IV (kappa 0.33 and 0.36), but the T2 cut-off values still indicated a significant difference between grades (p<0.05). CONCLUSIONS: Interobserver agreement of MR evaluation in patients with intervertebral disc degeneration was only fair to moderate on the classification of more severe disc degeneration in the Pfirrmann and Schneiderman schemes. Based on our results, quantitative T2 cut-off values seem to be a more reliable method to define the degree of disc degeneration, which may help staging intervertebral disc degeneration (IVDD) even if the interobserver reliability is low.

Dynamic MR based analysis of tumor movement in upper and mid lobe localized lung cancer.

BACKGROUND AND PURPOSE: Tumor motion is a very important factor in the radiotherapy of lung cancer. Uncertainty resulting from tumor movement must be considered in 3D therapy planning especially in case of IMRT or stereotactic therapy. The aim of our dynamic MR based study was to detect tumor movements in upper and mid lobe lung tumors. PATIENT AND METHODS: Twenty-four patients with newly diagnosed stage II-IV lung cancer were enrolled into the study. According to tumor localization in the right S1-S3 segments 9, in the right S4-S6 segments 2, in the left S1-S3 segments 9 and in the left S4-S6 segments 4 lesions were detected. In normal treatment position individual dynamic MR examinations were performed in axial, sagittal and coronal planes (100 slices/30 sec). For tumor motion analysis E-RAD PAC's software was used. RESULTS: Movements of the tumor under normal breathing conditions were registered in the three main directions. The mean antero-posterior deviation was 0,109 cm (range: 0,063 cm-0,204 cm), the mean medio-lateral deviation was 0,114 cm (range: 0,06 cm- 0,244 cm). The greatest deviation was measured in cranio-caudal direction (mean: 0,27 cm, range: 0,079 cm- 0,815 cm). The mean direction independent deviation was 0,18 cm (range: 0,09 cm- 0,48 cm). CONCLUSION: Dynamic MR is a sensitive and well tolerated method for tumor motion monitoring in high precision 3D therapy planning of lung cancer patients. Our results demonstrate that tumors located in the upper and mid lobes have moderate breath synchronous movements. The greatest deviation occur in cranio-caudal direction.

Magnetic resonance imaging technique for the examination of canine mammary tumours.

The aim of this study was to adapt the human magnetic resonance imaging (MRI) sequences for use in the routine examination of canine mammary glands. MRI was performed on 10, middle- to old-aged dogs of different breeds. It was found that T1- and T2-weighted spin echo, short T1 inversion recovery sequences and a gradient echo (GE) dynamic T1-weighted measurement made in the coronal and transversal planes were the most informative MR diagnostic methods for imaging canine mammary tumours. The static MR technique is the most detailed imaging modality for differentiating the tissue types in the substance of the mammary gland. The MRI findings were in close relationship with the histological result (five malignant mixed tumours and five cases of invasive ductal carcinoma). Using the GE dynamic contrast-enhanced sequence the morphological patterns as well as the kinetic parameters proved to be malignant. By the dynamic measurement technique initial information was obtained on the contrast enhancing properties, which are valuable factors during in vivo staging and in the prognostic work.

Is downregulation of MHC class I antigen expression in human non-small cell lung cancer associated with prolonged survival?

PURPOSE: To characterize HLA class I antigen expression in non-small cell lung cancer (NSCLC) lesions, and to assess the clinical significance of these molecules' downregulation. METHODS: One hundred and ninety primary formalin fixed, paraffin embedded NSCLC lesions were stained with HLA class I heavy chain-specific mAb HC-10. Results were scored as percentage of stained tumor cells and categorized into three groups: 0-24% (negative), 25-75% (heterogeneous) and >75% (positive). HLA class I antigen expression was correlated with clinical and pathologic predictors of time to progression and survival and analyzed using the chi-square test. Association between HLA class I antigen expression and survival was assessed using Cox regression models, while controlling for confounders. RESULTS: HLA class I antigen expression was negative, heterogeneous and positive in 153, 25 and 12 primary NSCLC lesions, respectively. Independent variables significantly associated with survival included tumor stage, PS and weight loss. The median survival times were 40.6, 44.0 and 17.9 months for patients with a HLA class I antigen expression scored as negative, heterogeneous and positive, respectively. CONCLUSION: HLA class I antigen defects were found with high frequency (93.6%) in NSCLC lesions. HLA class I antigen downregulation was associated with improved survival, although this association was not statistically significant. These results, which parallel similar findings in uveal melanoma and in breast carcinoma, raise the possibility that NK cells may play a role in the control of NSCLC tumors.

Determination of the lean meat percentage of pig carcasses using magnetic resonance imaging.

The purpose of Workpackage 3 of the European Eupigclass project was to test indirect methods of measuring the lean meat percentage of a carcass that would be less costly, at least as accurate and more consistent than dissection. Magnetic resonance imaging was one of the three indirect methods tested to measure the lean meat weight and the lean meat percentage of pig carcasses, the other methods being X-ray CT and vision techniques. One hundred and twenty carcasses from three different genotypes and from both sexes were slaughtered. The left parts of the carcasses were fully dissected and the right parts were investigated with an indirect method using a 1.5T MRI system. The acquisition protocol was chosen to give an optimized contrast between fat and muscle tissues. Two different approaches, image segmentation and PLS regression, were used to extract information from the images. Automatic image segmentation was performed to quantify the volume of muscle in the images and gave a standard error of prediction using a linear regression with the dissection of the left half carcasses of 586g and 1.10% for lean meat weight and lean meat percentage, respectively. PLS regression using the signal intensities histograms gave an estimation error of 465g for lean meat weight. These results showed that MRI could be used in place of full dissection for authorizing and monitoring classification equipment of pig carcasses.

Fast method for longitudinal relaxation time and water content mapping of the human brain on a clinical MR scanner.

BACKGROUND: Longitudinal relaxation time (T(1)) map generation from human brain slices renders possible the in vivo follow-up of the changes in T(1) values during the course of several pathologies such as stroke, multiple sclerosis, traumatic brain injury etc. T(1) values can be converted to water contents, thus brain oedema reducing therapy can be non-invasively evaluated. The purpose of the study was to work out a fast and simple MRI method to obtain T(1) and water maps of the human brain. METHOD: The T(1) values of Gadolinium solutions with different concentrations were determined by means of MRI methods at a clinical MR scanner operating at 1 Tesla. In order to validate these measurements, T(1) values of the same Gadolinium solutions were also quantified with a relaxometer operating at the same field strength. T(1) and water maps from the brains of healthy volunteers were obtained with an inversion prepared spoiled gradient echo sequence (turbo-FLASH). FINDINGS: The T(1) values of Gadolinium solutions measured with the relaxometer showed a strong correlation (r > 0.999) with those determined with MRI sequences on the whole body scanner. The fastest MRI method to produce T(1) and consequent water maps from human brain was the inversion prepared turbo-FLASH sequence. CONCLUSIONS: The implemented turbo-FLASH method can produce T(1) and water map of a single virtual brain slice within 2 minutes. However, brain tissue containing haemorrhage should be excluded from the measurement due to the large influence of excessive haemoglobin concentration on longitudinal relaxation. The proposed method is available on most of the MR scanners, thus T(1) and water mapping of human brain can be routinely performed.

Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues. In newborn foals the bursa podotrochlearis could not be determined with the used sequences. For both the adult and newborn limbs the most visualization of the same tissue structures including the fluid spaces and growth plates were taken by the inversion recovery sequence. T2 sequence was very informative in adult cases but moderately in newborn foals.

A novel technique with a flexible applicator for MRI-based brachytherapy of cervical cancer.

PURPOSE: To introduce a novel technique for magnetic resonance (MR)-based 3-dimensional planned high-dose rate intracervical brachytherapy (BT). MATERIALS AND METHODS: During 2002, 16 patients received external beam radiotherapy and BT as part of radiochemotherapy for cervical cancer. A special adjustable applicator device was designed and used for BT. The isodose distribution was calculated from MR images with the applicator in place. RESULTS: The planning target volume coverage was adequate and the radiation burden on the organs at risk was within acceptable limits. Complete regression was achieved in two patients (12.5%), and partial regression in ten (62.5%) patients. The overall response rate for the complex treatment was 93.75%. In three cases the disease was considered to be stable. CONCLUSION: The MR-compatible, flexible applicator allows safe and reproducible cervical radiotherapy with no added discomfort or hazard for the patient.

Metabolic changes induced by regular submaximal aerobic exercise in meat-type rabbits.

Pannon White growing rabbits (a group of 8) were exposed to treadmill exercise (3-9 m/s, 1.2-1.6 km/day) twice a day for 4 weeks, while additional 8 animals, kept inactive, were assigned as the control group. Weekly, 12 hours after exercise, venous blood was taken for serum metabolite and enzyme activity measurements. Total serum protein, albumin and creatinine levels significantly increased during the second half of the training, as compared to the control group. Triacylglycerol levels in the exercised group as compared to controls, however, were higher only after the first and the fourth weeks of the experiment. Resting non-esterified fatty acid (NEFA) concentration of the trained rabbits was lower at the end of the trial. On the other hand, there were no significant differences, as compared to the respective controls, in serum urea, total and HDL cholesterol levels. At the end of the exercise alkaline phosphatase activity was higher and total lactate dehydrogenase activity was lower in the trained rabbits. Serum alanine aminotransferase, aspartate aminotransferase and gamma-glutamyl transpeptidase activities were not changed, while creatine kinase activity was slightly lower in the trained group. The serum cortisol concentration was not different in the trained and control rabbits.

Training-induced alterations of the fatty acid profile of rabbit muscles.

The present study was designed to investigate whether meat-type rabbits are able to perform treadmill running as a daily routine exercise, and if so, whether the exercise induces specific proportional changes in the fatty acid composition of their muscles. After a four-week training period 8-week-old rabbits were slaughtered and the total activity of plasma lactate dehydrogenase was measured, showing a significant difference between the exercised and control groups (429 +/- 126 IU/l vs. 639 +/- 203 IU/l). Furthermore the fatty acid composition of m. longissimus dorsi (MLD) and m. vastus lateralis (MVL) was determined by means of gas chromatography. Exercise increased the proportions of oleic acid (C18:1 n-9) in both MLD and MVL as compared to the control group. However, the level of stearic (C18:0) and arachidonic (C20:4 n-6) acids significantly decreased in the MVL after the exercise. Changes in the fatty acid profile resulting from the physically loaded condition were of the same tendency in both muscles, adding that the MVL might have been exposed to the exercise more intensively; alterations there occurred in a more pronounced manner. Based on the inference that the composition of membrane structure was also affected, these alterations may have important consequences on meat quality.

Right prefrontal activation produced by arterial baroreceptor stimulation: a PET study.

This study was performed to test the hypothesis of greater right hemispheric involvement in the processing of baroreceptor stimuli. Carotid sinus baroreceptors were stimulated by rhythmically decreasing air pressure in a neck chamber, and under control conditions the thorax was stimulated in a similar manner. Changes in regional cerebral blood flow (rCBF) were measured by PET. Baroreceptor stimulation resulted in rCBF increase in the right anterior-inferior prefrontal cortex (Brodmann areas (BA) 10/44/47) and bilaterally in BA 6/8. We conclude that in at least some stages of baroreceptor information processing the right hemisphere plays a greater role than the left hemisphere.

Normal brain and brain tumor: multicomponent apparent diffusion coefficient line scan imaging.

Magnetic resonance line scan diffusion imaging of the brain, with diffusion weighting between 5 and 5,000 sec/mm(2), was performed in healthy subjects and patients with a 1.5-T machine. For each voxel, biexponential signal decay fits produced two apparent diffusion constants and respective signal amplitudes. Images based on these parameters show potential for use in the differentiation of gray and white matter, edema, and tumor.

Brain water and proton magnetic resonance relaxation in preterm and term rabbit pups: their relation to tissue hyaluronan.

The present study was performed to investigate simultaneously total brain water, T1 and T2 relaxation times, and hyaluronan (HA) in fetal and neonatal rabbits. Attempts were also made to establish the relationship of HA to total brain water and to T2-derived motionally distinct water fractions, since HA is known to bind water and to limit tissue water mobility. Experiments were carried out in fetal Pannon white rabbit pups at gestational ages of 25, 27, 29, and 31 days and at a postnatal age of 4 days. The brain tissue water content (desiccation method), T1 and T2 relaxation times (H1-NMR method), and HA concentration (radioassay HA 50) were measured, and free and bound water fractions were calculated by using multicomponent fits of the T2 relaxation curves. Compared with values in newborn pups, water and HA contents were found to be highly elevated in the preterm brain and decreased markedly during early postnatal life. The trends and time courses of T1 and T2 relaxation times proved to be similar, but the postnatal decrease in T2 was preceded by a significant decline in late gestation. Maturity-related changes occurred in the T2 relaxation derived bound water fraction which amounted to 4-19% of brain water. The bound water fraction appeared to be independent of total brain water and HA concentration, and HA is, therefore, unlikely to be the only factor controlling brain water mobility. The clear dissociation of bound water fraction from total water suggests restructuring of brain water during the perinatal period.

[MR-guided diagnostic and therapeutic interventions. Review and own preliminary experience]. / MR-vezérelt diagnosztikus és terápiás beavatkozások (Attekintés és saját kezdeti tapasztalatok).

Magnetic resonance (MR) guided diagnostic and therapeutic interventions are relatively new methods in the larger field of radiologic interventions. Good spatial resolution and soft tissue characterisation, multiplanar imaging capability, functional imaging and up-to-date computer systems enable MR imaging to guide a wide range of interventional procedures. Biopsies, punctures and drainages of fluid collections, tumor ablations and vascular interventions can be performed with the help of MRI. MR imaging provides an unique opportunity for planning, guiding and monitoring certain types of intraoperative procedures. The authors outline the basic features of MR intervention and report their own initial experience in interventional procedures in 8 cases for the first time in Hungary.

Lung water and proton magnetic resonance relaxation in preterm and term rabbit pups: their relation to tissue hyaluronan.

The present study was performed to investigate simultaneously total lung water, T(1) and T(2) relaxation times, and hyaluronan (HA) in preterm and term rabbits. Attempts were also made to establish the relationship of HA to total lung water and to T(2)-derived motionally distinct water fractions. Experiments were performed in fetal Pannon white rabbit pups at gestational ages of 25, 27, 29, and 31 d and at a postnatal age of 4 d. Lung tissue water content (desiccation method), T(1) and T(2) relaxation times (H(1)-NMR method), and HA concentration (radioassay) were measured, and free and bound water fractions were calculated by using multicomponent fits of the T(2) relaxation curves. Lung water content and T(1) and T(2) relaxation times were highest at a gestational age of 27 d and then declined steadily during the whole study period. Similar trends and time courses were seen for the fast and slow components of the T(2) relaxation curve. The T(2)-derived free water fraction remained unchanged at a gestational age of 25-29 d ( approximately 67%), but increased progressively to a value of 78.5 +/- 7.9% at 31 d (p < 0. 001) and to 83.4 +/- 9.4% at the postnatal age of 4 d (p < 0.01). Opposite changes occurred in the bound water fraction. Lung HA concentration decreased with advancing gestation from 870.8 +/- 205.2 microg/g dry weight at 25 d to 162.6 +/- 32.4 microg/g dry weight at 31 d (p < 0.001), but it was increased 2-fold postnatally. HA correlated positively with total lung water (r = 0.39; p < 0.001) but not with the bound water fraction. It is suggested that the physiologic lung dehydration is associated with macromolecule-related reorganization of lung water and that the role of HA in this process needs to be further investigated.

Multi-component apparent diffusion coefficients in human brain: relationship to spin-lattice relaxation.

In vivo measurements of the human brain tissue water signal decay with b-factor over an extended b-factor range up to 6,000 s/mm(2) reveal a nonmonoexponential decay behavior for both gray and white matter. Biexponential parametrization of the decay curves from cortical gray (CG) and white matter voxels from the internal capsule (IC) of healthy adult volunteers describes the decay process and serves to differentiate between these two tissues. Inversion recovery experiments performed in conjunction with the extended b-factor signal decay measurements are used to make separate measurements of the spin-lattice relaxation times of the fast and slow apparent diffusion coefficient (ADC) components. Differences between the spin-lattice relaxation times of the fast and slow ADC components were not statistically significant in either the CG or IC voxels. It is possible that the two ADC components observed from the extended b-factor measurements arise from two distinct water compartments with different intrinsic diffusion coefficients. If so, then the relaxation results are consistent with two possibilities. Either the spin-lattice relaxation times within the compartments are similar or the rate of water exchange between compartments is "fast" enough to ensure volume averaged T(1) relaxation yet "slow" enough to allow for the observation of biexponential ADC decay curves over an extended b-factor range. Magn Reson Med 44:292-300, 2000.

[Dynamic MR examination of the breast--histological correlations]. / Az emló dinamikus MR-vizsgálata--szövettani korreláció.

The authors outline dynamic MR mammography (dMRM) as a highly sensitive diagnostic method for the examination of the breast. In a retrospective study relating to 84 processed cases, in the knowledge of the cytological-histological findings the diagnostic accuracy of the examinations was determined. The role of the method in detecting benign and malignant changes of the breast has been estimated. Misdiagnosed cases have been analysed and recommendations for the application of the method are included. The MR proved to be positive in 32 cases and negative in 3 cases of the analysed 35 malignant tumors. Benign lesions were found at microscopy in 49 cases, of which MR correctly diagnosed 40. The sensitivity and the specificity of dynamic MR mammography were 91% and 82%.