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PubMed2005

[Imaging of the temporal bone. An overview].

Diseases of the temporal bone should be diagnosed by high resolution computed tomography (CT) and magnetic resonance imaging (MRI). Because of the excellent imaging of bony structures, CT is the method of choice for diagnosing pathologies of the external auditory channel, middle ear, and mastoid. Imaging of trauma is performed with CT. For examining the labyrinth system and interior auditory channel, MRI is the method of choice. This article gives an overview of the anatomy of the temporal bone and describes the most important pathologies.

Diagnosis, Differential↗
PubMed1993

Use of a clinical MR scanner for imaging the rat brain.

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy are established techniques that enable noninvasive anatomic and functional tissue characterization in vivo. These tools have been employed to probe experimental models of neoplasia, cerebrovascular disease, brain injury, and neurotransplantation in small animals. To date, these studies have been executed primarily on research-dedicated instruments of limited availability or resolution. Using relatively straightforward software and hardware modifications of a widely used clinical MRI unit, we were able to image numerous structures within the living rat brain including the neostriatum, hippocampus, periaqueductal gray, and the ventricular system. Illustrative applications of this imaging technique in two intracerebral infusion models involving rats are presented. Such adaptation of clinical MRI scanners has the potential to significantly expand the availability of high resolution in vivo imaging of small animals for a variety of experimental protocols.

Animals↗
PubMed2006

Differential aging of the brain: patterns, cognitive correlates and modifiers.

Deciphering the secret of successful aging depends on understanding the patterns and biological underpinnings of cognitive and behavioral changes throughout adulthood. That task is inseparable from comprehending the workings of the brain, the physical substrate of behavior. In this review, we summarize the extant literature on age-related differences and changes in brain structure, including postmortem and noninvasive magnetic resonance imaging (MRI) studies. Among the latter, we survey the evidence from volumetry, diffusion-tensor imaging, and evaluations of white matter hyperintensities (WMH). Further, we review the attempts to elucidate the mechanisms of age-related structural changes by measuring metabolic markers of aging through magnetic resonance spectroscopy (MRS). We discuss the putative links between the pattern of brain aging and the pattern of cognitive decline and stability. We then present examples of activities and conditions (hypertension, hormone deficiency, aerobic fitness) that may influence the course of normal aging in a positive or negative fashion. Lastly, we speculate on several proposed mechanisms of differential brain aging, including neurotransmitter systems, stress and corticosteroids, microvascular changes, calcium homeostasis, and demyelination.

Age Factors↗
PubMed1993

Magnetic resonance imaging in the diagnostic management of diseases of the knee.

Magnetic resonance imaging (MRI) of the knee is fast assuming a major role in evaluating disorders of the knee. The major advantage of MRI is that it is a totally non-invasive procedure with superior soft tissue contrast resolution and multi-planar capabilities. In contrast to arthrography, intra-articular as well as extra-articular structures in the knee can be evaluated by MRI. Indications include studying abnormalities of the menisci, ligament, patella and quadriceps mechanisms, articular cartilage, bone, bursa and other soft tissue. A review of the literature comparing MRI to arthrography and arthroscopy of the knee, especially in relation to meniscal injuries and anterior cruciate ligament tears, shows wide ranges in the accuracy rates of MRI. There are pitfalls in the interpretation of meniscal tears on MRI like normal variants, tears at the free edge and healed or previously repaired tears. Arthrography remains a useful diagnostic modality in some of these settings.

Arthroscopy↗
PubMed2006

Enhanced perfusion in eyes and cerebral perfusion defects in a patient with Fragile X Syndrome.

Fragile X syndrome (FXS) is known as the most common form of inherited mental retardation. In our study, brain perfusion single photon emission computed tomography (SPECT) was performed in a 6 year-old boy diagnosed with FXS. Diffuse bilateral uptake of Technetium-99m hexamethyl propylene amine oxime (99mTc-HMPAO) was noted in his orbits, as well as cortical perfusion defects (hypoperfusion in the right parietal and the left temporal lobe). Ophthalmologic examination showed no pathological findings. Magnetic resonance imaging (MRI) revealed no abnormality in the orbital structures, although hypoplasia of cerebellum and vermis was visualized. Since the patient was crying during the injection, the increased blood flow or the increased metabolism of the eyes and/or ocular muscles may be responsible for this orbital finding. Alternatively, the enhanced uptake of HMPAO in the orbits may reflect the pathology associated with FXS, because patients with FXS might have visual-motor abnormalities. To the best of our knowledge, there has been no report documenting such an orbital uptake of HMPAO. Moreover, the visualization of decreased cerebral perfusion, with the normal findings of MRI, indicates that brain SPECT imaging with HMPAO is helpful for detecting brain abnormalities in children with FXS.

Child↗
PubMed2000

Cerebellar vermis area in schizophrenic patients - a post-mortem study.

Neuroimaging studies of cerebellar atrophy in schizophrenia have yielded contradictory results. In computer-tomography (CT) studies, cerebellar atrophy was found in up to 40% of schizophrenic patients. However, several recent magnetic resonance imaging (MRI) studies could not replicate these early findings; in addition, contradictory observations of enlargement of vermal structures were reported. In contrast to the number of CT and MRI studies, there are only a few neuropathological reports on this subject. In a post-mortem study we analyzed the midsagittal vermal area of formaldehyde-fixed cerebella of 12 deceased schizophrenic patients and 12 age- and gender-matched control subjects by using morphometrical methods. Statistical analysis using ANOVA revealed no significant group effects, but there were interactions with gender and cerebellar brain weight. In view of the present results, the common concept of cerebellar atrophy in schizophrenic patients appears premature. Gender effects and secondary processes (e.g., relevant alcohol or drug abuse) cannot be excluded as possible factors causing decrease of vermal areas in schizophrenic patients.

Adolescent↗
PubMed2006

Early lung cancer detection based on registered perfusion MRI.

Lung cancer remains the most common fatal malignancy in both men and women in the United States and elsewhere around the world among people who have been exposed passively or actively to tobacco smoke. Technological advances have produced imaging modalities that are proving to be useful for the early detection of lung cancer. In the usual modes, computed tomography (CT) and magnetic resonance imaging (MRI) can identify suspicious lesions, but further work is needed to detect cancer in its early stage. Tumor angiogenesis assessed by perfusion-sensitive MRI is a promising method for early and accurate identification of lung cancer that avoids patient stress and the potential progression to a less treatable stage inherent in serial imaging. However, compensating for the respiratory and anatomical structure motion is a challenge. In order to use perfusion MRI in a signal imaging session to define metabolic and vascular characteristics of tumors, we present a novel affine registration method for perfusion MRI that can register points of interest by tracking image intensity changes around the target point. The registration results are used to generate accurate time intensity curves (TIC) of different regions of interest (ROI). The patterns of different TICs are mapped on the cancer and other structures. The method is computationally efficient and performs well in our perfusion MRI sequence analysis.

Artifacts↗
PubMed2005

Cortical gray matter differences identified by structural magnetic resonance imaging in pediatric bipolar disorder.

OBJECTIVE: Few magnetic resonance imaging (MRI) studies of bipolar disorder (BPD) have investigated the entire cerebral cortex. Cortical gray matter (GM) volume deficits have been reported in some studies of adults with BPD; this study assessed the presence of such deficits in children with BPD. METHODS: Thirty-two youths with DSM-IV BPD (mean age 11.2 +/- 2.8 years) and 15 healthy controls (HC) (11.2 +/- 3.0 years) had structured and clinical interviews, neurological examinations, neurocognitive testing, and MRI scanning on a 1.5 T GE Scanner. Image parcellation divided the neocortex into 48 gyral-based units per hemisphere, and these units were combined into frontal (FL), temporal (TL), parietal (PL), and occipital (OL) lobe volumes. Volumetric differences were examined using univariate linear regression models with alpha = 0.05. RESULTS: Relative to controls, the BPD youth had significantly smaller bilateral PL, and left TL. Analysis of PL and TL gyri showed significantly smaller volume in bilateral postcentral gyrus, and in left superior temporal and fusiform gyri, while the parahippocampal gyri were bilaterally increased in the BPD group. Although the FL overall did not differ between groups, an exploratory analysis showed that the right middle frontal gyrus was also significantly smaller in the BPD group. CONCLUSIONS: Children with BPD showed deficits in PL and TL cortical GM. Further analyses of the PL and TL found differences in areas involved in attentional control, facial recognition, and verbal and declarative memory. These cortical deficits may reflect early age of illness onset.

Adolescent↗
PubMed2003

Volumetric evidence of a left laterality effect in epileptic psychosis.

We investigated anatomic alterations and lateralization effect in the mesial temporal lobe structures (amygdala and hippocampus) in epileptic psychosis MRI volumetric measurements. Patients with epileptic psychosis and normal controls were studied. Left hippocampus values were significantly smaller for patients (P<0.001). Hippocampal ratio was significantly greater for patients (P<0.01). Group (patients x normal) was the only factor explaining the statistically significant variation of left hippocampus and hippocampal ratio (P<0.001 and P<0.05). Twenty patients had hippocampal atrophy (4 on the right side, 15 on the left side, and 1 bilateral) associated with mesial temporal sclerosis. These results confirm the existence of anatomic alterations and a left laterality effect in the mesial temporal lobe structures of patients with epileptic psychosis.

Adult↗
PubMed1993

Single photon emission computed tomography in cancer imaging.

Although structural imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have revolutionized the noninvasive assessment of visceral anatomy, significant difficulties remain in the diagnosis and surveillance of cancer. Differences in the metabolism and biochemistry of tumors, compared with normal tissues, are known to precede and are responsible for the changes in structural anatomy imaged by CT or MRI. Recent advances in nuclear imaging techniques utilizing single photon emission computed tomography (SPECT) provide improved 3D spatial resolution, compared with previous planar 2D nuclear imaging techniques. New techniques are also able to characterize differences in the biochemistry and functional metabolism of neoplastic tissue, compared with normal tissue. These new technologies offer potent advantages over previous nuclear imaging and structural imaging techniques, not only in the diagnosis of cancer but also as possible tools for monitoring and predicting the effects of therapy on cancer metabolism.

3-Iodobenzylguanidine↗
PubMed2001

Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study.

The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the lesion involved the medial longitudinal fasciculus. Most lesions were located medially and ventrally to the PSN on transverse slices. Our results underline the high localizing value of changes in the R1 component of the blink reflex in patients with ipsilateral pontine functional deficits. Although available physiological evidence suggests that the R1 component of the blink reflex traverses an oligosynaptic pathway, this MRI study does not support the view that synaptic transmission in the PSN subserves R1. The reflex arc probably descends more medially and ventrally on its course to the facial nucleus.

Adult↗
PubMedDate not supplied

MRI of callosal disconnection due to cerebral infarction.

Magnetic resonance imaging (MRI) was performed to study two cases of callosal disconnection due to cerebral infarction. Both cases had pure alexia and right homonymous hemianopsia. Midsagittal inversion recovery (IR) images demonstrated that the corpus callosum was completely intact, and coronal IR images revealed involvement of the lingual gyrus, fusiform gyrus, forceps major, inferior longitudinal fascicle, and optic radiation in the dominant cerebral hemisphere in both cases. Midline sagittal images provided direct visualization of the corpus callosum but did not provide sufficient information for the study of callosal disconnection syndromes. Coronal reconstructions aided in visualizing the relationship of lesions to the adjacent structures of cerebral white and gray matter. MRI may be one of the most useful tools for understanding the process of interhemispheric transference of information.

Aged↗
PubMed1994

Progressive hemifacial atrophy with agenesis of the head of the caudate nucleus.

We describe a woman with right hemifacial atrophy, a high palate, partial left motor seizures, and mild atrophy of the left arm. CT scan showed asymmetrical lateral ventricles and MRI (magnetic resonance imaging) showed atrophy of the right cerebral hemisphere and agenesis of the head of the right caudate nucleus. To our knowledge, this is the first report of Parry-Romberg syndrome associated with structural abnormalities of the basal nuclei documented by MRI. We suggest that a neurovascular aetiology can explain the spectrum of segmental defects associated with hemifacial atrophy.

Adult↗
PubMed1997

Magnetic resonance imaging in classification of congenital muscular dystrophies with brain abnormalities.

A survey was performed of magnetic resonance imaging (MRI) findings in 21 patients with congenital muscular dystrophy (CMD) with cerebral abnormalities to evaluate the contribution of MRI to the classification of CMD patients. In 5 patients with Walker-Warburg syndrome (WWS), MRI showed hydrocephalus due to aqueduct stenosis, generalized cerebral cortical agyric or pachygyric polymicrogyria, diffuse cerebral hemispheric white matter abnormalities, and malformations of posterior fossa structures. In 4 patients with muscle-eye-brain disease, MRI showed cortical dysplasia, but less severe than in WWS. The cerebral white matter either was normal or contained multiple focal abnormalities. Malformations of posterior fossa structures were present. Eight patients, classified as having classic merosin-deficient CMD (MD-CMD), had diffuse cerebral hemispheric white matter abnormalities, no other abnormalities. One patient with MD-CMD had only a few, focal white matter abnormalities. Three CMD patients had occipital agyria, otherwise normal gyration, multifocal or more diffuse cerebral white matter changes, and variable hypoplasia of pons and vermis. Two of the 3 patients had negative muscle merosin staining. The conclusion of the study is that MRI is an important adjunct in the classification of CMD patients. CMD with occipital agyria can be regarded as a newly recognized, separate CMD subtype.

Adolescent↗
PubMed1998

[Integration of functional and morphologic MRI data for preoperative 3D visualization of tumors. Example: cervical carcinoma].

PURPOSE: The goal of this exemplary study was to integrate morphological and functional MRI to establish computer-based, pre-operative therapy planning for tumors, instancing cervical carcinoma. METHODS: For morphological representation T1-weighted, filtered 3D sequences were investigated within a hierarchical segmentation approach. Using a method for image registration, segmented structures were combined and overlaid with functional information of contrast medium-enhanced, dynamic MRI. After assigning colour attributes to the segmented structures, they were presented using a method for direct volume visualisation. RESULTS: Segmentation of organs and vessels as well as tissue differentiation yielded a morphological visualisation of anatomical structures that were overlaid with pharmacokinetic parameters derived from dynamic MRI, subsequently. Thereby, three-dimensional, arbitrary views on the functional data were displayed. CONCLUSIONS: Image analysis and visualisation of the acquired MR data establishes both a morphologic and functional evaluation of suspect lesions and adjacent organs. By integrating morphologic and functional MRI additional information can be gathered that possibly impinge on preoperative planning.

Data Interpretation, Statistical↗
PubMed2002

A general algorithm for magnetic resonance imaging simulation: a versatile tool to collect information about imaging artefacts and new acquisition techniques.

An innovative algorithm for Magnetic Resonance Imaging (MRI) capable of demonstrating the source of various artefacts and driving the hardware and software acquisition process is presented. The algorithm is based on the application of the Bloch equations to the magnetization vector of each point of the simulated object, as requested by the instructions of the MRI pulse sequence. The collected raw data are then used to reconstruct the image of the object. The general structure of the algorithm makes it possible to simulate a great range of imaging situations in order to explain the nature of unwanted artefacts and to study new acquisition techniques. The way the algorithm structures the sequence has also allowed the easy implementation of MRI data acquisition on a commercial general-purpose DSP-based data acquisition board, thus facilitating the comparison between simulated and experimental results.

Algorithms↗
PubMed2001

Normal pituitary hypertrophy as a frequent cause of pituitary incidentaloma: a follow-up study.

Enlargement of the pituitary gland is a frequent cause of incidentaloma and of referrals to endocrinologists for hormonal evaluation and therapeutic advice. In neuroradiological series, 25-50% of healthy women who are 18-35 yr old have a convex superior pituitary contour, but pituitary height exceeds 9 mm in less than 0.5% of cases. This study was performed to provide thorough clinical and hormonal data and long-term endocrinological and imaging follow-up data on subjects with incidentally discovered pituitary hypertrophy (height > 9 mm). Seven eugonadal nulliparous women, 15-27 yr old, referred between 1989 and 1998 with incidentally diagnosed pituitary gland enlargement (height > 9 mm) and a suspected pituitary tumor, were studied. At presentation and at yearly intervals, PRL plasma levels and corticotropic, somatotropic, and thyrotropic pituitary function were measured; and pituitary dimensions and signal on magnetic resonance imaging (MRI), before and after iv gadolinium-diethylene-triamine-pentaacetic acid injection, were assessed. PRL plasma levels were normal; and corticotropic, somatotropic, and thyrotropic pituitary function was considered normal in all cases. In all the women, the upper boundary of the pituitary was convex, on MRI, and touched the optic chiasm in four cases. The width and anteroposterior diameter of the gland were normal. The pituitary itself seemed normal, with a homogeneous signal, on plain and dynamic studies with iv contrast injection. Despite normal initial hormone values, two women underwent surgery, by the transsphenoidal approach, in another center. During surgery, the pituitary seemed normal in both cases, with no evidence of tumoral or inflammatory processes. Biopsy specimens showed the morphologic characteristics of a normal, nonhyperplastic pituitary gland. All seven women were seen at yearly intervals for 2-8 yr (median, 4 yr). Clinical and hormonal status remained stable, as did the structure and size of pituitary, on serial MRI. No tumor formation occurred, supporting the diagnosis of physiologic hypertrophy of the pituitary gland. In conclusion, these observations suggest that careful examination of MRI results may help to distinguish physiologic pituitary hypertrophy from pituitary tumors and infiltrating lesions. The former diagnosis is confirmed by normal baseline pituitary function in extensive hormonal tests. Correct identification of such patients is important to avoid unnecessary pituitary surgery and costly MRI surveillance.

Adenoma↗
PubMed1997

[Role of magnetic resonance in the evaluation of the normal and osteochondrosis hip in early and late childhood].

INTRODUCTION: Despite MR potentials, few studies investigate the features of normal hips and of hip osteochondrosis in early and late childhood. We report our personal experience with MRI of hip osteochondrosis in pediatric patients. MATERIAL AND METHODS: MR images were obtained with total body MR equipment at medium and high fields. The normal hips were studied in children aged 34 months to 6 years with abdominal-urinary tract disorders and in 9 patients of the same age with unilateral Perthes disease. Hip osteochondrosis was studied in 6 children with Catteral's type III and IV and in 3 with type I and II disease. General anesthesia was never necessary to perform MRI. RESULTS: MRI exactly defined the cephalic anatomic profiles of normal hips which are not depicted with conventional radiography before the femoral head cartilage ossifies completely. MR contrast resolution was very high in depicting the maturation of the epiphyseal nucleus and its exact site in the cartilagineous epiphyseal hemisphere proximal to the femur. The analysis of MR morphological and structural changes permitted to correlate MR findings with the histopathologic features described in the literature. In addition, MRI of childhood hip osteochondrosis showed maked structural changes of the epiphyseal nucleus which are usually missed with conventional radiography. MRI permits early location of the abnormal area and the recognition of growing disk abnormalities; it also shows the whole cephalic cartilage and the changes of the epiphyseal nucleus evolution, which permits to differentiate osteochondrosis evolution from recessive patterns. Finally, MRI clearly showed the increased equatorial diameters of the involved femoral heads and the associated decrease in polar diameters, which is essential to study the biomechanics of hip osteochondrosis and therefore to plan treatment. CONCLUSIONS: MRI, even with coronal sequences and T1-weighting only, permits: 1) to image normal hips and hip osteochondrosis, especially in early and late childhood; 2) to clearly define cephalocotyloid relationships; 3) to depict the actual anatomic margins of the head and its structure; 4) to investigate the head cartilage extent and to locate the ossification nucleus. These morphologic and structural data are very useful to diagnose and manage hip osteochondrosis in the evolutive age. MRI shows abnormal changes in anatomic structures which are not seen with conventional radiography and demonstrates the evolution of the osteochondrosis process over time. In children over six, at the end of the ossification process of the head cartilage, conventional radiography alone is often sufficient to depict cephalocotyloid relationships and the MR diagnostic criteria of bone-cephalic diseases are similar to those used in adult hip studies.

Adult↗