Recurrent glioblastoma multiforme versus radiation injury: a multiparametric 3-T MR approach.

OBJECTIVE: The discrimination between recurrent glioma and radiation injury is often a challenge on conventional magnetic resonance imaging (MRI). We verified whether adding and combining proton MR spectroscopic imaging ((1)H-MRSI), diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) information at 3 Tesla facilitate such discrimination. MATERIALS AND METHODS: Twenty-nine patients with histologically verified high-grade gliomas, who had undergone surgical resection and radiotherapy, and had developed new contrast-enhancing lesions close to the treated tumour, underwent MRI, (1)H-MRSI, DWI and PWI at regular time intervals. The metabolite ratios choline (Cho)/normal( n )Cho n , N-acetylaspartate (NAA)/NAA n , creatine (Cr)/Cr n , lactate/lipids (LL)/LL n , Cho/Cr n , NAA/Cr n , Cho/NAA, NAA/Cr and Cho/Cr were derived from (1)H-MRSI; the apparent diffusion coefficient (ADC) from DWI; and the relative cerebral blood volume (rCBV) from PWI. RESULTS: In serial MRI, recurrent gliomas showed a progressive enlargement, and radiation injuries showed regression or no modification. Discriminant analysis showed that discrimination accuracy was 79.3 % when considering only the metabolite ratios (predictor, Cho/Cr n ), 86.2 % when considering ratios and ADC (predictors, Cho/Cr n and ADC), 89.7 % when considering ratios and rCBV (predictors, Cho/Cr n , Cho/Cr and rCBV), and 96.6 % when considering ratios, ADC and rCBV (predictors, Cho/Cho n , ADC and rCBV). CONCLUSIONS: The multiparametric 3-T MR assessment based on (1)H-MRSI, DWI and PWI in addition to MRI is a useful tool to discriminate tumour recurrence/progression from radiation effects.

Multislice computed tomography overestimates superior semicircular canal dehiscence syndrome.

OBJECTIVES: We assessed the prevalence of superior semicircular canal dehiscence (SSCD) through examination of ultrahigh-resolution computed tomography (CT) scans of the temporal bone and attempted to verify the correspondence between a radiologic diagnosis of SSCD and clinical signs of SSCD syndrome. METHODS: A prospective study was carried out on 191 consecutive patients who underwent temporal bone ultrahigh-resolution CT scans. Cases that matched the radiologic diagnosis of SSCD were subsequently referred for a comprehensive audiological evaluation that might enable a final diagnosis of SSCD syndrome. RESULTS: Among the 191 patients, 17 had a radiologic diagnosis of SSCD, which was bilateral in 5 cases, for a total of 22 SSCD cases, with a prevalence rate of 5.8%. In 2 of the 17 patients, the audiological examination revealed signs and symptoms indicative of SSCD syndrome, with a total prevalence rate of 0.5%. CONCLUSIONS: Our data confirm that the radiologic diagnosis of SSCD, performed by mean thin-section CT scans reformatted in the plane of the superior semicircular canal, is not necessarily related to the clinical presentation of SSCD syndrome. Our study also showed a prevalence rate of SSCD syndrome that was similar to the prevalence of SSCD reported from studies of histologic specimens.

Unilateral visual loss due to ischaemic injury in the right calcarine region: a functional magnetic resonance imaging and diffusion tension imaging follow-up study.

To study the functional recovery of a patient with cerebrovascular injury using combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). A 24-year-old woman with left hemianopsia underwent fMRI and DTI in a 1.5-tesla machine both in the acute phase and 1 month after an ischaemic stroke involving the right calcarine cortex. Acute-phase fMRI demonstrated that peripheral left visual field stimulation did not activate the right primary visual cortex, whereas stimulation 1 month later activated the visual cortex bilaterally. Analysis of acute-phase DTI data disclosed that a reduction of fractional anisotropy in the right optic radiation had almost resolved after 1 month. Fibre direction was normal at either time point. fMRI and DTI can demonstrate functional damage and recovery in patients with neuro-ophthalmological lesions.

[Functional topography of the human corpus callosum]. / Organisation topographique du corps calleux chez l'homme. Etude cartographique en imagerie par résonance magnétique fonctionnelle (f-IRM).

The concept of a topographical map of the corpus callosum (CC) has emerged from lesion studies in humans and from anatomical tracing investigations in other mammals. We conducted the first in vivo study aimed at outlining the topographical organization of the normal human CC, using non-invasive functional magnetic resonance imaging (fMRI). We tested cortical and callosal activation by the BOLD effect during simple sensory stimulation (tactile, gustatory and visual) and simple motor tasks in 38 volunteers. The axonal organization of callosal white matter was also studied in 16/38 subjects, using diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT). Activation foci evoked by taste stimuli were detected in most subjects in the anterior part of the CC, those elicited by motor tasks lay in the central portion of the body of the CC, and those elicited by tactile stimulation of different body regions lay in the posterior part of the body. Activation foci evoked by visual stimulation were seen in the splenium of the CC. Callosal fibers interconnecting the primary cortical areas activated by taste stimulation, motor tasks, and tactile and visual stimuli were shown by DTT. Anatomical correlates of the BOLD activation foci were demonstrated in the CC, with fibers crossing it at the level of the genu, anterior and posterior body, and splenium, respectively. This study demonstrates for the first time that the functional topographical organization of the human CC can be explored by fMRI in vivo. Our findings may have clinical implications, especially for neurosurgical planning.

Contribution of posterior corpus callosum to the interhemispheric transfer of tactile information.

Three total and three partial callosotomy patients underwent neuropsychological testing to evaluate interhemispheric transfer of tactile information. Tactile transfer is required to name objects presented to the left hand, to compare objects held in either hand, and to transfer topological information between hands. Tactile Naming, Same-Different Recognition, and Tactile Finger Localization Tests (intra- and intermanual tasks) were administered as specific tools. Results were compared with previous fMRI data from the same subjects and with the performance of a control group (20 age-matched subjects). Total callosotomy patients performed modestly: mean correct responses were 93% and 30% (right and left hand, respectively) in Tactile Naming; 68% in Same-Different Recognition; 84% and 76% (right and left hand stimulation, respectively) in intermanual Tactile Finger Localization, and 100% in the intramanual task. Partial callosotomy patients achieved 93-100% accuracy: all have an intact splenium, and one, and possibly all, also an intact posterior callosal body. Controls scored 99% in Tactile Naming, both hands, and Same-Different Recognition; 100% in intramanual Tactile Finger Localization; and 96% and 95%, with right and left hand stimulation, respectively, in the intermanual task. Differences between the two callosotomy groups were significant, as were those between total callosotomy patients and controls. The partial callosotomy group scored like the control subjects. Neuropsychological data agree with previous functional findings, further demonstrating that interhemispheric tactile transfer requires posterior corpus callosum integrity.

Functional MRI cortical activations from unilateral tactile-taste stimulations of the tongue.

Functional magnetic resonance imaging (fMRI) was used for revealing activations in the human brain by lateralized tactile-gustatory stimulations of the tongue. Salt, a basic taste stimulus, and water, now recognized as an independent taste modality, were applied to either hemitongues with pads similar to the taste strips test for the clinical psychophysical evaluation of taste. With both stimuli, the observed cortical patterns of activations could be attributed to a combined somatosensory and gustatory stimulation of the tongue, with no significant differences between salt and water. Stimulation of each hemitongue evoked a bilateral activation of the anterior insula-frontal operculum, ascribable to the gustatory component of the stimulation, and a bilateral activation of the inferior part of the postcentral gyrus, ascribable to the tactile component of the stimulation. The results are in line with the notion that the representation of the tongue in the cerebral hemispheres in both the touch and the taste modalities is bilateral. Clinical and brain stimulation findings indicate that this bilaterality depends primarily on a partial crossing of the afferent pathways, perhaps with a predominance of the crossed pathway in the touch modality and the uncrossed pathway in the taste modality. Previous evidence suggests that the corpus callosum is not indispensible for this bilateral representation, but can contribute to it by interhemispheric transfer of information in both modalities.

Mycotic aneurysms as lethal complication of brain pseudallescheriasis in a near-drowned child: a CT demonstration.

Intracranial true mycotic aneurysms are rare and generally lethal. We report a case of a near-drowned child with brain abscesses due to Pseudallescheria boydii, a saprophytic fungus, who died after subarachnoid hemorrhage occurred. CT showed contrast-enhancing lesions indicative of aneurysms of basilar and right posterior cerebral arteries that could not be appreciated 2 days before. P. boydii is often resistant to commonly used antimycotic drugs. Because CNS infection is frequently associated with near-drowning, early diagnosis and specific therapy are strongly recommended for these patients.

White-matter alterations and callosal abnormalities in syndromic patients with mental retardation.

The aim of this study was to evaluate the frequency of callosal abnormalities and white matter alterations in syndromic patients. The authors report on the cerebral magnetic resonance imaging (MRI) morphologic analysis of the corpus callosum and white matter in 73 normal subjects and 61 syndromic patients. The study of the corpus callosum was carried out by MRI using different morphometric methods: measurement of the dimensions of length and thickness of genu, body, and splenium; measurement of angles obtained using the sagittal plane; and application of the proportional grid of Talairach. The evaluation of the white matter was carried out by applying a subjective grading scale. Abnormalities of the corpus callosum were found in about 50% of the syndromic subjects; in half of these cases, the abnormalities were associated with white matter alterations. In five syndromic patients (8.2%), the white matter alterations were not associated with corpus callosum abnormalities. This study shows that corpus callosum abnormalities are frequent in syndromology regardless of the syndrome type.

Resolution of limbic encephalitis with detection and treatment of lung cancer: clinical-radiological correlation.

Paraneoplastic limbic encephalitis may develop in the setting of an otherwise occult malignancy. In the case reported here, the neuropsychiatric syndrome resolved with treatment of the underlying, previously undiagnosed small-cell lung cancer, and MR imaging showed resolution of the characteristic temporal lobe signal abnormalities.

Expanding experience with spontaneous dermoid rupture in the MRI era: diagnosis and follow-up.

With widespread use of CT and MR imaging, experience with spontaneous dermoid rupture has significantly increased. What was previously believed to be a generally severe or even fatal accident, being the diagnosis made either at surgery or autopsy, or in patients with such consequent conditions as chemical meningitis or obstructive hydrocephalus, now appears to be more frequent than previously thought, and there is some evidence that it may also cause only a slight symptomatology or even be quite asymptomatic. We reviewed the clinical and imaging data of our series of five patients with spontaneously ruptured dermoids, spinal in one case, and intracranial supratentorial in four. These had their diagnosis following mild symptoms (number two cases) or incidentally (number two cases); the spinal tumor caused acute bladder dysfunction, possibly while undergoing rupture, and was associated with indolent intracranial fat spread. Three of the patients also had MR demonstration of asymptomatic persistence of fat spread in the subarachnoid spaces, respectively, 3, 4, and 5 years after rupture. One of the five cases, concerning a parasellar dermoid followed up over 6 years, provides the first demonstration of MR signal intensity change of the tumor prior to rupture.

MRI assessment of post-traumatic spinal instability.

The imaging evaluation of patients with spinal trauma has evolved over the past decades, and there has been particular interest in the concept of instability, to predict which a series of criteria have been proposed. We retrospectively evaluated the magnetic resonance imaging (MRI) findings in 50 patients with post-traumatic spinal instability according to Denis's three-column method, Daffner et al.'s radiographic criteria, and Oner et al.'s categorization of MRI findings; additionally, we evaluated the cord, the prevertebral tissue, and the epidural space. We suggest that an integrated panel of MRI information might be standardized in order to provide a more complete evaluation of spinal injury in an individual case and help planning surgical treatment.

3.0 T magnetic resonance in neuroradiology.

Ever since the introduction of magnetic resonance (MR), imaging with 1.5 T has been considered the gold standard for the study of all body areas. Until not long ago, higher-field MR equipment was exclusively employed for research, not for clinical use. More recently, the introduction of 3.0 T MR machines for new and more sophisticated clinical applications has yielded in important benefits, especially in neuroradiology. Indeed, their high gradient power and field intensity allow adjunctive and more advanced diagnostic methodologies to be applied with excellent resolution in a fraction of the time of acquisition compared with earlier machines. The numerous advantages of these machines in terms of higher signal, increased spatial resolution and greater sensitivity, and their few limitations, which can be overcome and anyway do not adversely affect diagnostic efficacy, will make 3.0 T MR systems the gold standard for morphological and functional studies of the brain.

Gemella morbillorum deep brain abscess successfully treated with combined stereotactic, medical, and imaging approach.

A rare case of brain abscess due to Gemella morbillorum, a normal inhabitant of the oral cavity, is presented. The aim of this report is to draw the attention of radiology literature readers to this little known pathogen, which caused a potentially life-threatening condition in an immunocompetent young man, and to emphasise the usefulness of a combined stereotactic, medical, and imaging approach to deep-located brain abscesses.

Automatic detection, localization, and volume estimation of ischemic infarcts in noncontrast computed tomographic scans: method and preliminary results.

OBJECTIVES: Sensitivity of noncontrast computed tomography (NCCT) in detecting hyperacute (< 8 hours) and acute (< 24 hours) cerebral infarction is low. We propose an automatic method to detect and localize ischemic infarct and to assess its volume from a single NCCT scan. MATERIALS AND METHODS: The method automatically determines attenuation value ranges of cerebrospinal fluid and white and gray matter, separates the brain scan into the left and right hemispheres, and by analyzing hemisphere attenuation value distributions using percentile difference ratios, it detects, localizes, and quantifies the infarct without its segmentation. The method performance was evaluated on 576 patients with clinically confirmed stroke through NCCT scans acquired at 4 centers to measure how it matched with that of experts in detection, localization, and assessment of infarct volume. The time from the onset of symptoms ranged from 1.5 to 72 hours for 450 scans and more than 72 hours for 82 scans, most with pathologic findings in addition to cerebral infarction; the time was unavailable for 44 scans. In addition, the method was compared with the novice's (with 52 scans) and experienced readers' infarct detection (with 21 × 2 scans) in early ischemia detection (with the time from the onset of symptoms ranging from 1.5 to 7 hours). RESULTS: The method matches 100% the expert's infarct detection when chronic infarcts, leukoaraiosis cases, and infarct volumes less than 2 cm (determined by detection accuracy simulation) are excluded from the analysis. For all cases excluding infarct volumes less than 2 cm, the method detection accuracy is 95.7%. Overall, the method detection accuracy is 83.2%. The early method detection accuracy (≤ 3 hours) is 78.4%. The novice detection accuracy is 27.8% (≤ 3 hours), 37.5% (3 < to ≤ 8 hours), and 77.8% (> 8 hours), whereas the expert detection accuracy for these cases is 100%. Moreover, the method detected all 21 early infarcts, of which 15 were missed by the stroke experts and 14 of 15 were missed by a general radiologist. The method performs automatic analysis in approximately 7 seconds. CONCLUSIONS: The results demonstrate potential benefits of our method for enhancing expert's performance because it quickly localizes the infarct and detects cases missed by experts, and it is to be considered as an aid in the emergency department because it substantially outperforms novice readers (100% vs 27%) in infarct detection on NCCT.

Topographical organization of human corpus callosum: an fMRI mapping study.

The concept of a topographical map of the corpus callosum (CC) has emerged from human lesion studies and from anatomical tracing investigations in other mammals. Over the last few years, a rising number of researchers have been reporting functional magnetic resonance imaging (fMRI) activation in white matter, particularly the CC. In this study, the scope for describing CC topography with fMRI was explored by evoking activation through simple sensory stimulation and motor tasks. We reviewed our published and unpublished fMRI data on the cortical representation of tactile, gustatory, and visual sensitivity and of motor activation, obtained in 36 volunteers. Activation foci were consistently detected in discrete CC regions: anterior (taste stimuli), central (motor tasks), central and posterior (tactile stimuli), and splenium (visual stimuli). These findings demonstrate that the functional topography of the CC can be explored with fMRI.