Spontaneous intracranial hypotension: the value of brain measurements in diagnosis by MRI

Caudal brain displacement is inconstantly reported as an MRI feature of spontaneous intracranial hypotension (SIH). We reviewed the clinical data and MRI of eight patients diagnosed as having SIH and investigated the possibility of more precise assessment. On midsagittal images we measured four anatomical landmarks: the position of the cerebellar tonsils, fourth ventricle, and infundibular recess, plus the angle between the bicommissural line and a line tangential to the floor of the fourth ventricle; midsagittal images from 89 normal controls were also measured. On statistical analysis, all measurements differed in the two groups, and the difference was significant for the cerebellar tonsils, fourth ventricle, and infundibular recess. Some overlap between patients and controls was found for each measurement; however, all the patients had two (two patients) or more (six) values outside the range in normal controls range or not above their 1st quartile. Measurement of the position of the third ventricle seemed particularly sensitive. We suggest that examination of midsagittal images can help in diagnosing clinically suspected SIH.

An unusual spinal presentation of Whipple disease

SUMMARY

When Whipple disease (WD) is confined to the CNS, diagnosis may be difficult. We report a case of WD with spinal presentation in an otherwise healthy woman who had a 5-year history of relapsing-remitting cervico-thoracic myelopathy. We suggest that the diagnosis of WD should be considered in the presence of an enlarged and enhancing spinal cord even in the absence of any systemic involvement.

Multicentric glioma with unusual clinical presentation

Multiple glioma is a well-recognized but uncommon entity. They are grouped in two categories: multifocal and multicentric gliomas. Multifocal gliomas grow through dissemination along an established route, spreading through commissural pathways, CSF channels, or the blood or by local extension through satellite formation; at the opposite end of the spectrum, multicentric gliomas are widely separated lesions whose simultaneous presence cannot be attributed to any of the above pathways. Reports in the literature refer to single cases or small series of multicentric gliomas, almost always in adult patients, their occurrence in children being even less frequent. We report the case of a 12-year-old boy with multicentric glioma, atypical acute clinical onset and fast growth of three other tumors in 8 months, and then discuss the problems of diagnosis and therapy.

Hippocampus and parahippocampal gyrus linear measurements based on magnetic resonance in Alzheimer's disease

MRI-based linear measurements of the hippocampus and parahippocampal gyrus complex (HPC) discriminated 39 subjects with probable Alzheimer's disease, from 15 patients with other dementias and 33 miscellaneous controls without evidence of dementia. The best discriminating parameter was the left height of the HPC at the level of the mammillary bodies, with a sensitivity of 79.49% and a specificity of 68.75%. The diagnostic value of these results is discussed considering the volumetric data found in the current literature.

MRI T-staging of laryngeal tumours: role of contrast medium

Our aim was to evaluate the relative diagnostic accuracy of MRI without contrast medium and MRI before and after contrast medium in the assessment of T-staging of laryngeal tumours. We studied 25 men (mean age 51.8, range 41-61) with laryngeal squamous cell carcinomas, using Spin-echo (SE) T1-weighted and fast SE T2-weighted sequences. The T1-weighted sequences were then repeated after gadolinium-diethylene-triaminepenta-acetic acid (Gd DTPA) 0.1 ml/kg. All patients then underwent biopsy and surgery. Two radiologists independently assessed the anonymised images by filling-out two multiple-choice forms, one for each technique, at a 2 week interval. The forms included a judgement concerning tumour identification and infiltration of the anterior commissure, supraglottic region, arytenoid cartilage, Morgagni's ventricle, paraglottic space, thyroid and cricoid cartilages, thyro-hyo-epiglottic space, vocal cords, subglottic region, and epiglottis. Similar forms were filled out by the surgeon and the pathologist after surgery. The sensitivity, specificity and diagnostic accuracy of MRI were unaffected by the use of contrast medium. Since it did not provide additional staging information, its continued routine use in these cases is not justified.

Role of the corpus callosum in the somatosensory activation of the ipsilateral cerebral cortex: an fMRI study of callosotomized patients

To verify whether the activation of the posterior parietal and parietal opercular cortices to tactile stimulation of the ipsilateral hand is mediated by the corpus callosum, a functional magnetic resonance imaging (fMRI, 1.0 tesla) study was performed in 12 control and 12 callosotomized subjects (three with total and nine with partial resection). Eleven patients were also submitted to the tactile naming test. In all subjects, unilateral tactile stimulation provoked a signal increase temporally correlated with the stimulus in three cortical regions of the contralateral hemisphere. One corresponded to the first somatosensory area, the second was in the posterior parietal cortex, and the third in the parietal opercular cortex. In controls, activation was also observed in the ipsilateral posterior parietal and parietal opercular cortices, in regions anatomically corresponding to those activated contralaterally. In callosotomized subjects, activation in the ipsilateral hemisphere was observed only in two patients with splenium and posterior body intact. These two patients and another four with the entire splenium and variable portions of the posterior body unsectioned named objects explored with the right and left hand without errors. This ability was impaired in the other patients. The present physiological and anatomical data indicate that in humans activation of the posterior parietal and parietal opercular cortices in the hemisphere ipsilateral to the stimulated hand is mediated by the corpus callosum, and that the commissural fibres involved probably cross the midline in the posterior third of its body.

Posttraumatic epilepsy risk factors: one-year prospective study after head injury

PURPOSE

Prospective evaluation of risk factors for posttraumatic epilepsy (PTE) by using clinical, EEG, and brain computed tomography (CT) data in four assessments from the head injury (HI) acute phase to 1 year later; and evaluation of the possible epileptogenic role of hemosiderin as shown by brain magnetic resonance imaging (MRI).

METHODS

Risk factors for PTE were evaluated by using Kaplan-Meier curves, log-rank test, and the Cox model in 137 consecutively enrolled adult inpatients. Percentage differences of patients with brain hyperintense and/or hemosiderin areas shown by MRI 1 year after HI were statistically evaluated by univariate tests considering two subgroups [e.g., patients with (PTE) and without (WLS) late seizures].

RESULTS

The PTE subgroup included 18 patients with at least two seizures between the second and twelfth months. Kaplan-Meier curves demonstrated that Glasgow Coma Scale low score, early seizures, and single brain CT lesions are PTE risk factors, as is the development of an EEG focus 1 month after HI. No significant percentage difference was found between PTE and WLS patients with hemosiderin spots shown by MRI 1 year after HI.

CONCLUSIONS

the Cox model indicates that, for HI patients with early seizures and brain CT single temporal or frontal lesions in the acute phase, the PTE risk is 8.58 and 3.43 times higher, respectively, than for those without. An EEG focus 1 month after HI is a risk factor 3.49 times higher than for patients without such EEG changes. One year after HI, a higher percentage of PTE than WLS patients had cortical MRI hyper-intense areas including hemosiderin.

Contrast-enhanced MR angiography (CE MRA) in the study of the carotid stenosis: comparison with digital subtraction angiography (DSA)

PURPOSE

To determine sensitivity, specificity and diagnostic accuracy of contrast-enhanced magnetic resonance angiography (CE MRA) compared to digital subtraction angiography (DSA) in the study of carotid stenosis.

METHODS AND MATERIAL

We studied 23 patients with suspected cerebro-vascular insufficiency by carotid stenosis. Diagnostic examinations by means of CE MRA and DSA were carried out within 24 hours of each other. A 1.5 T superconductive magnet (Signa-General Electric) was used for CE MRA. This technique was performed using a fast spoiled gradient echo recalled (SPGR) sequence acquired in coronal plane 13 sec after injection of contrast medium. Imaging parameters were: TR/TE/FA 8 msec/1 msec/60 degrees, matrix 256 x 128, 1 excitation, FOV 18 x 13 cm, 28 slices per slab, slice thickness of 1 mm, acquisition time of 32 sec. The post-processing was performed using maximum intensity projection (MIP) and targeted MIP. For DSA examinations a Politron 1000 VR unit (Siemens) was used.

RESULTS

In the identification and quantification of lesions, CE MRA showed values of 100%. In particular, in comparison to DSA, CE MRA was accurate in diagnosing all true negative and positive cases. The location of stenosis evaluated with CE MRA agreed in all cases with DSA.

CONCLUSION

In our experience CE MRA proved to be a very valuable technique in diagnosing carotid stenosis, showing the same diagnostic accuracy as DSA. In this way CE MRA appears to be a substantial alternative technique to conventional MRA and other non-invasive diagnostic methods.

Proton magnetic resonance spectroscopy of the brain in pediatric patients

H1-MRS is a non-invasive technique which provides different levels of information on brain tissue: the N-acetyl aspartate (NAA) is an indicator of neuronal development, the choline containing compound peak (Cho) provides information on myelination and on cell membrane turnover and gliosis, inositol (Ins) is considered a marker of neuronal degeneration. Lactate may be detected in presence of defective energy metabolism. In the perineonatal period, the brain is apt to be insulted by a variety of events including asphyxia, hypoxemia, hemorrhage, which may subsequently cause delay in development. It is clinically important to assess the degree of brain damage and to obtain the prognostic information in the neonatal and early infantile period. MRS has become available for clinical examinations of the brain during development and these techniques can be used to document improvement or the progression towards irreversible damage.

Localization of the first and second somatosensory areas in the human cerebral cortex with functional MR imaging

BACKGROUND AND PURPOSE

Our objective was to map by means of a conventional mid-field (1.0 T) MR imaging system the somatosensory areas activated by unilateral tactile stimulation of the hand, with particular attention to the areas of the ipsilateral hemisphere.

METHODS

Single-shot echo-planar T2*-weighted imaging sequences were performed in 12 healthy volunteers to acquire 10 contiguous 7-mm-thick sections parallel to the coronal and axial planes during tactile stimulation of the hand. The stimulation paradigm consisted of brushing the subjects' palm and fingers with a rough sponge at a frequency of about 1 Hz.

RESULTS

Stimulation provoked a signal increase (about 2% to 5%) that temporally corresponded to the stimulus in several cortical regions of both hemispheres. Contralaterally, activation foci were in the anterior parietal cortex in an area presumably corresponding to the hand representation zone of the first somatosensory cortex, in the posterior parietal cortex, and in the parietal opercular cortex forming the upper bank of the sylvian sulcus and probably corresponding to the second somatosensory cortex. Activation foci were also observed in the frontal cortex. Ipsilaterally, activated areas were in regions of the posterior parietal and opercular cortices roughly symmetrical to those activated in the contralateral hemisphere. The same activation pattern was observed in all subjects.

CONCLUSION

The activated areas of the somatosensory cortex described in the present study corresponded to those reported in other studies with magnetoelectroencephalography, positron emission tomography, and higher-field functional MR imaging. An additional area of activation in the ipsilateral parietal operculum, unnoticed in other functional MR imaging studies, was also observed.

High-resolution magnetic resonance angiography of the internal carotid artery: 2D vs 3D TOF in stenotic disease

The aim of this study was to compare high-resolution 2D TOF with high-resolution 3D TOF in the study of internal carotid artery disease. Sixty-four patients with clinical signs of cerebrovascular insufficiency were studied with a superconductive 1.5 T magnet using two techniques: 2D and 3D TOF. Digital subtraction angiography (DSA) was the gold standard. The 2D TOF technique was performed using the following parameters: TR/TE/FA/MA 49 ms/9 ms/60 degrees/512 x 256; the 3D TOF was performed with the following parameters: TR/TE/FA/MA 50 ms/8 ms/20 degrees/512 x 256. The 2D TOF agreed with DSA in 116 of 128 diagnostic judgments (90%) and overestimated seven times. The 3D TOF technique agreed with DSA in 125 of 128 diagnostic judgments (97%) with one overestimation and two underestimations. There was no statistically significant difference (P < 0.05) between the two different techniques. Our study confirms the high reliability of the methodology carried out with the high-resolution 2D and 3D technique.

MR angiography in carotid stenosis: a comparison of three techniques

PURPOSE

To compare the accuracy of three different magnetic resonance angiography (MRA) techniques for studying steno-occlusive disease of carotid arteries.

METHODS

64 patients were evaluated with three MRA techniques- three-dimensional (3D) time-of-flight (TOF), two-dimensional (2D) TOF, and 3D Phase-Contrast (PC); the acquisition was in the axial plane, the volume included the carotid bifurcation. Digital subtraction angiography (DSA) was considered the 'gold standard'. The MRA images were reprojected with a maximum intensity pixel ray-tracing (MIP) algorithm. The three MRA techniques were blindly graded as normal, mildly stenotic (0-29%), moderately stenotic (30-49%), severely stenotic (70-99%), or occluded.

RESULTS

DSA provided 128 diagnostic judgments: 92 were negatives and 36 positives. 2D TOF was in agreement with angiography in 116 of 128 cases (90%), but overestimated the results in seven cases and underestimated in five cases. 3D TOF agreed with angiography in 125 of 128 cases (97%), with one overestimation and two under estimations. 3D PC was concordant in 116 of 128 cases (90%), overestimating in six cases, underestimating in six cases. The sensitivity, specificity and diagnostic accuracy for 2D TOF was, respectively 84%, 94%, and 92%, while for 3D TOF was 94%, 100%, and 98%, and for 3D PC 86%, 98%, and 95%. The comparison of the three different MRA techniques provided no statistically significant difference (Friedman test P < 0.05).

CONCLUSION

The high degree of diagnostic accuracy of MRA found in the study of the steno-occlusive disease of the carotid arteries confirms the high degree of reliability of this methodology carried out with the 3D TOF technique, compared to 2D TOF and 3D PC.

Transcranial Doppler sonographic monitoring during cerebral aneurysm embolization: a preliminary report

BACKGROUND AND PURPOSE

The wide application of embolization in the treatment of aneurysms has created the need for an intraprocedural means to anticipate a poor outcome by monitoring hemodynamic changes in the brain.

METHODS

Transcranial Doppler sonography was used to monitor flow velocity in the middle cerebral artery (MCA) in 23 patients undergoing embolization with Guglielmi detachable coils (GDCs) of either incidental or symptomatic intracranial aneurysms. Sonographic values were recorded from the ipsilateral MCA at the beginning, middle, and end of the interventional procedure and 24 hours afterward.

RESULTS

No complications occurred in 15 patients. In these cases, sonography showed an average decrease in MCA flow velocity of 2.7% after GDC application, returning to baseline at the end of treatment and then increasing by about 17% 24 hours later. In four patients with vasospasm on posttreatment angiograms, MCA flow velocity increased to values higher than 120 cm/s after GDC application, returning to baseline after 24 hours. In four patients with ischemic complications (two transient ischemic attacks, one stroke, one vascular death), MCA flow velocity decreased more than 30% and did not return to preoperative values within 24 hours.

CONCLUSION

The application of transcranial Doppler sonographic monitoring during endovascular treatment may help to identify patients at risk for posttreatment cerebral ischemia.

Carotid stenosis: a comparison between MR and spiral CT angiography

We performed a preliminary study comparing three-dimensional time-of-flight (3 D TOF) magnetic resonance angiography (MRA) and spiral CT angiography (SCTA) in the detection and assessment of internal carotid artery stenosis. Digital subtraction angiography (DSA) was the reference examination. We examined 20 patients with signs of cerebrovascular insufficiency, who underwent MRA, SCTA and DSA within a 3 day period. Both internal carotid arteries were assessed by three blinded readers for degree of stenosis at two different levels (bulb and remaining section) giving a total of 80 assessments. Interobserver variability, sensitivity, specificity, diagnostic accuracy, concordance, overestimation and underestimation were assessed. Interobserver variability was not statistically significant. MRA showed higher sensitivity, specificity, diagnostic accuracy and concordance than SCTA (92.0% vs 80.8%, 98.2% vs 96.4%, 96.3% vs 91.3% and 96.0% vs 88.0%, respectively). MRA gave rise to a 5.0% overestimation rate, whereas SCTA occasioned a 7.5% underestimation rate. These differences are not statistically significant. These results suggest that MRA is a more useful, noninvasive modality for assessment of the internal carotid artery with a more than 70% stenosis.

Minor cerebral alterations observed by magnetic resonance imaging in syndromic children with mental retardation

OBJECTIVE

To evaluate the anomalies of the central nervous system (CNS) by magnetic resonance imaging (MRI) in normal subjects and in syndromic patients.

METHODS AND MATERIAL

Seventy-three normal subjects and 50 different syndromic patients with mental retardation (from 3 months to 16 years) were studied utilizing several morphometric parameters (degree of myelination of the white matter, evaluation of liquoral spaces, septo-caudate distance, Evans index, Aboulezz method, and length, width and angles of corpus callosum).

RESULTS

A high frequency of anomalies of the corpus callosum, the Chiari anomaly and alterations either of the white matter or of the ventricular and periencephalic system have been observed.

CONCLUSION

The authors point out the importance of cerebral MRI in the study of CNS in patients with malformation syndromes. The present research, carried out on a large number of both normal subjects and patients with malformation syndromes, represents one of the first systematic studies in this field.

[Stenosis-occlusion of the carotid bifurcation. Angiography with MR and contrast media versus digital angiography]

PURPOSE

To evaluate the comparative sensitivity, specificity and diagnostic accuracy of contrast enhanced magnetic resonance angiography (CE MRA) and digital subtraction angiography (DSA) in the study of carotid bifurcation stenoses.

MATERIAL AND METHODS

Twenty-three patients with suspected cerebrovascular insufficiency by carotid stenosis were examined with CE MRA and DSA within 24 hours of each other. A 1.5 superconductive unit (Signa, General Electric) was used for CE MRA; fast spoiled gradient echo recalled (SPGR) images were acquired on the coronal plane 12 s after contrast medium injection, with the following parameters: TR/TE/FA 8/1/60, MA 256 x 128, NEX 1, FOV 18 x 13, slices/slab 28, slice thickness 1 mm, TA 32 s. The images were postprocessed with the maximum intensity projection (MIP) and the targeted MIP algorithms. A Siemens Politron 1000 VR unit was used for DSA examinations.

RESULTS

DSA diagnosed 21 true positives, namely 4 grade II, 4 grade III, 10 grade IV and 3 grade V stenoses. CE MRA scored 100% in stenosis identification and grading, accurately diagnosing all the true negatives and the true positives and was always in agreement with DSA as to stenosis site.

CONCLUSION

CE MRA can be considered the technique of choice to study stenosis occlusion in the epiaortic vessels, because it permits a rapid panoramic study of the neck vessels and accurate stenosis grading with similar patterns to those of DSA. Thus, CE MRA appears to be a valid alternative to DSA.

[Magnetic resonance angiography of the vessels of the neck: the optimization of a dynamic technic during the rapid infusion of a paramagnetic contrast medium]

INTRODUCTION

A new noninvasive technique, dynamic Magnetic Resonance Angiography (MRA) during rapid infusion of paramagnetic contrast medium, has been recently developed for the study of neck vessels. This study was carried out to optimize technical parameters.

MATERIALS AND METHODS

Twenty healthy volunteers (10 men and 10 women; age range: 25 to 50 years) were examined with a 1.5 T MR unit equipped with fast imaging software and a dedicated coil. Dynamic MRA was performed using fast spoiled gradient recalled (fast SPGR) sequences acquired on the coronal plane 13 s after contrast medium injection. Imaging parameters were: Echo Time (TE): 1 ms, Repetition Time (TR): 8 ms, flip angle: 60 degrees, matrix 256 x 128, number of excitations: 1, field of view: 18 x 13 cm, number of partitions per slab: 28, slice thickness: 1 mm, acquisition time: 32 s. A dose of .2 mmol/kg of paramagnetic contrast medium was administered with an MR compatible automatic injector, at a speed rate of 1.5 ml/s. Angiographic images were postprocessed with the maximum intensity projection (MIP) and targeted MIP algorithms.

RESULTS

Using the above parameters and rapid contrast medium injection, the carotid arteries on the coronal plane (including the vessels from the proximal aspect of the common carotid arteries to the intracranial tract of the internal carotid arteries) in 18 cases. In the other two cases the tortuosity and the position of the carotid arteries on two different planes, prevented their complete visualization. The vertebral arteries were completely demonstrated in 50% of the investigated population. Partial or total overlapping of jugular veins did not affect the recognition of the carotid vessels in 10 cases, also with targeted MIP postprocessing.

DISCUSSION

The vascular semiology of dynamic gadolinium enhanced MRA seems to be closer to that of conventional angiography than of conventional MRA, likely due to the same modality of vessel depiction, based on contrast medium administration. Flow artifacts, the major pitfall of conventional MRA causing signal void and overestimation of stenosis grade, are not frequent in dynamic MRA.

CONCLUSIONS

Gadolinium enhanced dynamic MRA ensures panoramic and high resolution angiographic-like depiction of the neck vessels, providing rapid and excellent definition of vascular morphology. Thus dynamic MRA appears to be a substantial alternative to conventional MRA and conventional angiography.

[Whole-body magnetic resonance angiography using a contrast medium. Technical optimization]

INTRODUCTION

We tried to optimize the technique of contrast enhanced MR Angiography (MRA) in the study of the main body arteries.

MATERIALS AND METHODS

Fifty volunteers were examined with contrast enhanced MRA with a superconductive magnet at 1.5 T (Signa GE) and 3D SPGR sequences acquired with the following parameters: TR 8.2 +/- 1.3 ms, TE 1.8 +/- 7 ms, FA 60 degrees, MA 128 X 256; the images were acquired on the sagittal or coronal planes. The contrast agent (Gd-DTPA) was injected with MedRad Spectris system, with the bolus technique and the following standard parameters: velocity 1.5 mL/s and single dose; circulation time was optimized with 2D SPGR for each vessel (pretest). The carotid and pulmonary arteries, the thoracic-abdominal aorta and the iliac arteries were studied. The reader used a multiple choice card to evaluate image quality, signal-to-noise ratio (SNR) and circulation time.

RESULTS

Circulation time was 10.2 s in the carotid arteries, 8.1 s in the pulmonary arteries, 10.3 s in the thoracic aorta, 12.2 s in the abdominal aorta and 13.8 s in the iliac arteries. The signal was 181.8 vs the noise 3.1 in the carotid arteries, 256.8 vs 23.2 in the thoracic aorta, 518.4 vs 23.5 in the pulmonary arteries, 258.8 vs 24.5 in the abdominal aorta and finally 262.7 vs 25.4 in the iliac arteries.

CONCLUSIONS

Our experience suggests that contrast enhanced MRA is a good technique to study body arteries.

Spiral CT angiography in the study of the carotid stenoses

PURPOSE

To determine sensitivity, specificity and diagnostic accuracy of spiral CT angiography (S-CTA) compared to Digital Subtraction Angiography (DSA).

MATERIALS AND METHODS

We studied 40 patients with suspected cerebro-vascular insufficiency by carotid stenosis. Diagnostic examinations by means of S-CTA and DSA were carried out within 24 hours of each other. Twelve of these patients underwent thromboendoarterectomy (TEA). Prospeed SX GE was used for S-CTA. Post-processing was performed using Maximum Intensity Projection (MIP) after deleting osteo-muscular structures and CT angiograms were displayed in an oblique anterior view at an angle of 10 degrees-15 degrees along the longitudinal axis. For DSA examinations, a Siemens Politron 1000 VR unit was used.

RESULTS

In this study S-CTA showed values of sensitivity, specificity and diagnostic accuracy of 88%, 100% and 96%, respectively.

CONCLUSIONS

In the future, with the improvement of non-invasive techniques (S-CTA, MRA), DSA should be replaced, as the gold-standard, in the evaluation of stenotic disease of the carotid bifurcation.