The role of MRI in diagnostic algorithm of cervicofacial vascular anomalies in children.

BACKGROUND: Vascular anomalies are usually diagnosed through their clinical picture and history. The purpose of this study was to assess the role of MR imaging in initial assessment of cervicofacial vascular anomalies in children. MATERIAL/METHODS: Twenty pediatric patients with vascular anomalies located in the cervicofacial region underwent MRI examination in our department. Images were evaluated for lesion detectability and its signal characteristics (on T1w, T2w images with fat suppression and contrast enhanced T1w sequences); the extent of the lesions and surrounding tissue involvement were also assessed. RESULTS: In the studied group MR images revealed all anomalies and provided information of their anatomic extent and invasion of surrounding anatomic structures. Nine hemangiomas and six venous malformations were found among studied patients. Two children had multiloculated lesions corresponding to lymphatic malformations. One examination visualized a lesion consisting mainly of dilated vascular channels with an apparent feeding artery, which was consistent with arteriovenous malformation. Two remaining lesions were mixed malformations. Nine patients had lesions limited to subcutaneous tissue. Two masses infiltrated bone structures. There was muscle involvement found in nine cases. CONCLUSIONS: MR imaging is a well-established method for detection and monitoring of vascular anomalies in children. With ultrasound used mostly for initial diagnosis and additional flow assessment, angiography viewed as an invasive therapeutic method and computed tomography used only in specific situations due to its high irradiation dose, magnetic resonance is the best imaging method used in differential diagnosis and topographical characterization of vascular malformations and tumors of cervicofacial area in pediatric patients. Noninvasively and without irradiation, it enables evaluation of the extent and characteristics of lesions and planning proper therapeutic strategy.

Prenatal diagnosis of a vein of Galen aneurysmal malformation with MR imaging - report of two cases.

BACKGROUND: Vein of Galen malformations (VGMs) are rare congenital defects of cerebral vessels. They are formed between the 6(th) and 11(th) week of gestation. The background of this defect involves presence of one or more arterovenous fistulas directing bloodflow toward a persistent, dilated, proximal part of median prosencephalic vein (MProsV). Ultrasound examination is a basic test for diagnosis of VGMs. It has now become possible to acquire images of diagnostic value using magnetic resonance (MR) techniques. CASE REPORT: This work presents two cases of vein of Galen aneurysms diagnosed prenatally with magnetic resonance imaging. In both patients fetal CNS malformations were diagnosed in ultrasound examinations. MR imaging of the fetal head was performed for further diagnostics. CONCLUSIONS: Because of the ability to precisely determine the size of the ventricular system, presence of raised intraventricular pressure and topographic relationships between pathologically changed vessels and particular cerebral structures as well as the presence of ischemic areas MR examination is currently not only complementary to ultrasonography, but is becoming an independent examination method in the diagnostics of vein of Galen malformations.

Signal intensity and T2 time of extraocular muscles in assessment of their physiological status in MR imaging in healthy subjects.

BACKGROUND: Lack of standardised orbital MR protocols leads to a situation, when each institution/centre may arbitrarily choose sequence parameters. Therefore, the results obtained and published by the authors may not be compared freely, and what is most important may not be considered fully reliable. Signal intensity (IS) and T2 time (T2) are important parameters in estimation of inflammatory processes of extraocular muscles in the clinical practice. The aim of this study was to determine the reference values (i.e. cut-off values) for absolute signal intensity and T2 relaxation time in healthy subjects, their relativised values to white matter (WM) and temporal muscles (TM) and to evaluate the correlation between those parameters. MATERIAL/METHODS: The orbital examination was performed in healthy volunteers according to the protocol prepared in the Radiology-Imaging Diagnostic Department of the Medical University of Lodz for patients with suspected/diagnosed thyroid orbitopathy. Using two of the standard sequences IS and T2 time were calculated for the muscles and two relativisation tissues in realtion to WM and TM. Subsequently cut-off values for healthy volunteers were calculated. RESULTS: The differences between muscles for IS, IS MAX, IS/TM, IS/WM, IS MAX/TM, IS MAX/WM and T2 MAX/WM were not statistically significant. Therefore one cut-off value of these parameters for all the rectus muscles was calculated. T2-relaxation time and T2 relativised to white matter had to be calculated separately for each muscle. CONCLUSIONS: No statistical correlation was found between IS and T2-time for extraocular muscles in healthy volunteers. We calculated the reference ranges (cut-off values) for absolute IS and T2-time values and relativised parameters. In the clinical practice the objectification of IS and T2-time values should be done to WM, than to IS or T2 of the temporal muscle. The T2 MAX/WM seems to have the highest clinical utility for the assessment of the pathophysiological status of extraocular muscles.

Functional rearrangement of the primary and secondary motor cortex in patients with primary tumors of the central nervous system located in the region of the central sulcus depending on the histopathological type and the size of tumor: Examination by means of functional magnetic resonance imaging.

BACKGROUND: The aim of this study was to analyze the reorganization of the centers of the motor cortex in patients with primary neuroepithelial tumors of the central nervous system (CNS) located in the region of the central sulcus in relation to the histopathological type and the size of tumor, as determined by means of functional magnetic resonance imaging (fMRI). MATERIAL/METHODS: The fMRI was performed prior to the surgical treatment of patients with tumors located in the region of the central sulcus (WHO stage I and II, n=15; WHO stage III and IV, n=25). The analysis included a record of the activity in the areas of the primary motor cortex (M1) and the secondary motor cortex: the premotor cortex (PMA) and the accessory motor area (SMA). The results were correlated with the histopathological type of the tumor and its size expressed in cm(3). RESULTS: The frequency of activation of the motor center was higher in the group of patients who had less aggressive tumors, such as low-grade glioma (LGG), as well as in tumors of lower volume, and this was true both for the hemisphere where the tumor was located and in the contralateral one. Mean values of t-statistics of activation intensity, mean numbers of activated clusters, and their ranges were lower in all analyzed motor areas of LGG tumors. The values of t-statistics and activation areas were higher in the case of small tumors located in ipsilateral centers, and in large tumors located in contralateral centers, aside from the SMA area where the values of t-statistics were equal for both groups. The contralateral SMA area was characterized by the highest stability of all examined centers of secondary motor cortex. No significant association (p>0.05) was observed between the absolute value of the mean registered activity (t-statistics) and the size of examined areas (number of clusters) when the groups were stratified with regards to the analyzed parameters. CONCLUSIONS: The presence of a neoplastic lesion, its histopathological type and finally its size modulate the functional reorganization of the motor centers as suggested by the differences in the frequency of the neural center activation in the analyzed groups. Processes of functional rearrangement are more pronounced and more precisely defined in patients with less aggressive and/or smaller tumors. The contralateral accessory area is the most frequently activated center in all analyzed groups irrespective of the grade and size of the tumor.

[Estimation of brain tissue in schizophrenic patients using magnetization transfer imaging--preliminary report]. / Ocena tkanki mózgowej u chorych na schizofrenie za pomoca obrazowania rezonansu magnetycznego z uzyciem transferu magnetyzacji--doniesienie wstepne.

INTRODUCTION: Volumetric loss of some cerebral structures is noticed during morphometrical investigations, and it is one of the most frequent abnormalities in schizophrenic patients' brains. The new methods of MRI investigations show subtle changes in cerebral white matter, which are undetectable by standard MRI. The magnetic transfer imaging (MTI) may be used to estimate the structural integrity of white matter and allows for visualisation of minimal changes in cerebral tissue. AIM: The aim of this work was to estimate the cerebral tissue using magnetic transfer imaging and the analysis of magnetic transfer ratio (MTR) maps in schizophrenic patients. METHOD: We examined 15 patients with schizophrenia and 15 healthy volunteers. We used sequences of: SE, FLAIR and GE with- and without saturation pulse, acquiring standard T1- and T2-weighted anatomical images and images with magnetic transfer effect and without it. For quantitative estimation of magnetic transfer, the MTR-maps were calculated from a standard formula: MTR=Mo-Ms/Mo'l00%, and the obtained MTR-values, from regions of interest in schizophrenics were compared with MTR-values in healthy persons. RESULTS: Both, in the schizophrenic group and in the controls, MTR-values (from the analysed regions of white matter) were between 30-50%. We observed a statistically significant reduction of MTR of schizophrenic patients in the white matter of the left temporal and left frontal lobes. CONCLUSIONS: With the help of the technique and methods of statistical analysis, the identification of altered MTR-areas in patients with schizophrenia is possible. The results confirm the presence of areas of minimal injuries in schizophrenic persons' brain tissue, which are detectable using magnetic transfer imaging.

Magnetization transfer imaging in chronic schizophrenia.

BACKGROUND: It has recently been suggested that new imaging methods such as magnetization transfer imaging (MTI) may play an important role in detecting subtle gray- and white-matter abnormalities in schizophrenia. The aim of the study was to investigate whether MTI, analyzed on a voxel-by-voxel basis, could identify areas of abnormal magnetization transfer ratio (MTR) in patients with schizophrenia. MATERIAL/METHODS: Twenty schizophrenic patients and 23 healthy controls matched for handedness and demographic variables underwent MTI and T1-weighted structural MRI in a 3-tesla scanner. Post-processing was performed with SPM99 and included co-registration of the MT-weighted and non-MT-weighted images, calculation of the MTR maps, spatial normalization, and smoothing. Differences in the MTR maps between groups were assessed using two-sample t-tests. Significant changes in MTR were detected at an individual voxel threshold of p < 0.05. RESULTS: Group comparisons revealed no significant MTR changes, although there was a trend towards MTR reduction in the left superior temporal gyrus, in the right occipital cortex, and left periventricular white matter in patients compared with controls prior to correction for multiple comparisons (p < 0.001, uncorrected). CONCLUSIONS: MTI and voxel-by-voxel statistical analysis used in the study failed to identify regions of significant MTR reductions in schizophrenic patients. Our results disagree with findings of widespread MTR abnormalities reported in recent literature.