Proton magnetic resonance spectroscopy and intracranial tumours: clinical perspectives

Proton magnetic resonance spectroscopy (1H-MRS) was applied to characterize intracranial tumours of different hystological types. Seventy patients with intracranial neoplasms were studied before receiving surgery, radiotherapy or chemotherapy. All tumours were characterized by reduced or absent N-acetylasparate and increased signal from choline-containing compounds. Distinctive patterns were observed only for primitive brain neoplasms; high-grade gliomas were differentiated from low-grade ones by higher levels of choline-containing compounds. The metabolic aspects of metastatic lesions were similar to high-grade gliomas. These results, together with the limitations of 1H-MRS and future applications are reviewed.

Discordant clinical and neuroradiological features of congenital bilateral perisylvian syndrome in monozygotic female twins

We here report a case of monozygotic female twins, only one of whom had congenital bilateral perisylvian syndrome (CBPS). The affected girl had all of the essential and some additional diagnostic criteria according to Kuzniecky et al. [1993]; her twin sister was completely normal both clinically and neuroradiologically. This observation may contribute towards our understanding of the etiopathogenetic mechanisms of cortical dysplasia in CBPS: fetal brain ischemia or hypoxia in only one twin seems to be a reasonable explanation in this particular case.

Spontaneous involution of optic pathway lesions in neurofibromatosis type 1: serial contrast MR evaluation

PURPOSE

To evaluate with contrast MR the evolution in size, signal, and contrast enhancement of optic pathway lesions in four patients with neurofibromatosis type 1.

METHODS

The four reported patients are children with ages ranging from 21 months to 13 years affected by neurofibromatosis type 1 and optic pathway lesions. No treatment of the optic pathway lesions was carried out in these patients. They have been followed by serial contrast MR.

RESULTS

In all patients a change in size, signal, and enhancement of optic pathways lesions was noted with time, and in the last follow-up study a marked reduction in size and enhancement of optic pathway lesions was observed in all cases.

CONCLUSIONS

Modification and regression of optic pathway lesions with spontaneous disappearance of the enhancement is demonstrated. This finding could have a crucial influence on the therapeutic approach of the optic pathway lesions.

Acute subarachnoid haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography

To evaluate the efficacy and reliability of 3D time-of-flight MR angiography (TOF MRA) as a noninvasive procedure, 27 patients with acute subarachnoid haemorrhage (SAH) were studied with MRA immediately before or after intra-arterial digital subtraction angiography (DSA).3DTOF MRA was performed with an axial slab of 60 mm centered on the circle of Willis and isotropic voxels. DSA showed 22 aneurysms and 1 dural arteriovenous fistula in 21 patients; the aneurysms ranged in size from 2 to 8mm. MRA failed to show 2 small aneurysms, at the origin of the posterior and anterior communicating arteries. The 3D display of the intracranial vessels obtained with maximum intensity projection (MIP) or targetted MIP sometimes rendered the aneurysms better than DSA. However, due to its high spatial resolution, DSA more clearly defined the overall anatomy of the walls of the normal and abnormal vessels.

A bioimaging integration system implemented for neurological applications

A system aimed at the management and fusion of multimodal biomedical images, including X-ray computed tomography, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography, has been implemented for neurological applications. This bioimaging integration system (BIS) consists of a network for image transmission from acquisition machines to dedicated image processing workstations, a software library for image standardization, and an image registration technique to project multimodal volumetric images into a common reference space. The registration procedure was evaluated in MRI/PET correlation studies, in which misalignment errors of 2.6 mm in the xy transaxial plane and 3.4 mm along the z axis were found. BIS has been validated for the anatomical-functional correlation analysis of MRI and PET images in neurological research protocols and clinical studies.

Evidence of a congenital midline brain anomaly in pituitary dwarfs: a magnetic resonance imaging study in 101 patients

BACKGROUND

Magnetic resonance imaging (MRI) of the brain in pituitary dwarfs has revealed a previously unknown entity: ectopia of the posterior pituitary (PPE), absence or hypoplasia of the pituitary stalk and hypoplasia of the anterior pituitary. The pathogenesis of these findings was explained originally by a traumatic transection of the pituitary stalk during delivery. A high incidence of breech delivery has been reported in these groups, but the traumatic hypothesis cannot explain the findings in the relatively high percentage of patients with normal delivery, nor account for a different feature also found in other pituitary dwarfs consisting of pituitary hypoplasia with normal posterior pituitary. A second hypothesis could then been proposed, based on dysgenesis or abnormal embryonic development of both adenohypophysis and neurohypophysis.

OBJECTIVE

To review the value and significance of these two different etiopathogenetic hypotheses by analyzing clinical, endocrinological, and MRI findings in a large population of pituitary dwarfs.

METHODS

One hundred and one consecutive patients with congenital idiopathic growth hormone deficiency (CIGHD) were studied by MRI; they were compared with a control group of 46 healthy short children. A complete clinico-endocrinological evaluation was obtained in both patients and controls to assess the perinatal history, the pituitary-hypothalamic function, and the neurological status. MRI studies were evaluated both qualitatively and quantitatively and the pituitary volume (PV) was calculated in both patients and controls. Quantitative data were statistically analyzed to compare the mean PV of the patients with the mean PV of controls, the hormonal therapy, the single or multiple pituitary hormone deficiency, and the presence of breech delivery.

RESULTS

MRI revealed PPE in 59 patients and a normal posterior pituitary (NPP) in 42. PV was extremely small in patients with PPE and in patients with NPP associated with a severely narrowed pituitary stalk; mean PV was significantly lower in CIGHD patients when compared with that of healthy short children. PV was not influenced by hormonal therapy and did not differ between patients with single and multiple pituitary hormone deficiency and between patients with normal and breech delivery. PPE patients differed from NPP patients for a higher male/female ratio (3:1 vs 1:1) and for a greater frequency of multiple pituitary hormone deficiency (49% vs 12%), breech delivery (32% vs 7%), and associated congenital brain anomalies (12% vs 7%). In PPE patients breech delivery was strongly associated with multiple pituitary hormone deficiency.

CONCLUSION

On the basis of this study the traumatic hypothesis could theoretically explain the pathogenesis of PPE only in 32% of the patients with this condition. On the basis of modern understanding of embryogenesis of anterior and posterior pituitary, it is then justified to propose that a defective induction of mediobasal structure of the brain in the early embryo could account for both the complex morphological MRI abnormality and the clinico-endocrinological features encountered in all PPE patients. The close contiguity between the future pituitary and hypothalamus, the peculiar association with congenital midline brain anomalies, and the recent data about a possible role of Pit-1 gene, all support the hypothesis of a congenital defect. Finally, breech delivery can be considered not as a cause of PPE, but as an effect of the embryonic pituitary-hypothalamic abnormalities.

Modern imaging techniques in GH secretory disorders

Magnetic resonance images of the pituitary-hypothalamic area in patients with GH secretory disorders, divided into two groups (hypersecretory and hyposecretory), were studied. In the first group there were 42 patients with pituitary adenoma; size, signal characteristics, direction of growth, and type of enhancement were analyzed and compared with similar studies in 40 age and sex matched control patients with non-GH secreting pituitary adenomas. No significant differences were found except for a higher frequency of chiasm involvement and a more pronounced contrast enhancement in the control group. The hyposecretory group was composed of 101 patients with congenital idiopathic growth hormone deficiency (CIGHD). MR revealed morphological abnormalities consisting of hypoplastic anterior pituitary and ectopic posterior pituitary (PPE) in 59 patients, without evidence of a complete pituitary stalk; in 42 patients the posterior pituitary was in normal position and the pituitary stalk visible. The group with PPE showed a greater frequency of multiple pituitary hormone deficiency (51% vs 12%), breech delivery (30% vs 7%) and associated congenital brain anomalies (12% vs 7%). These data suggest that CIGHD could be the result of a congenital midline brain anomaly in a significant proportion of patients.

Encephalocraniocutaneous lipomatosis: case report and review of the literature

Encephalocraniocutaneous lipomatosis is a congenital disorder characterized by unilateral cerebral malformations and ipsilateral scalp, face, and eye lesions. Distinguishing histopathologic features are dysgenesis and neoplasia of the adipose tissue. A Caucasian boy had soft tumors and elastic papules on his head since birth, associated with atrophic areas, and a bilobed lesion on the upper right eyelid. On the bulbar conjunctiva of the right eye, an oval 6-mm lesion was present. Ultrasonogram, computerized tomographic scan, and magnetic resonance imaging revealed a dilation of the right lateral ventriculus, a mass on the pontocerebellar angle, agenesia of the corpus callosum, an arachnoidal cyst on the right hemisphere, microcalcifications, and pachygyria. The histology of a soft cutaneous tumor was consistent with a fibrolipoma, and dispersed extracellular lipid globules in the upper dermis were found on electron microscopy. The diagnosis suggested by these findings was encephalocraniocutaneous lipomatosis. Even in view of the rarity of the syndrome (11 cases described in the literature), this patient seems unusual because of the bilateral distribution of the cutaneous lesions and because of the agenesia of the corpus callosum. The peculiar ultrastructural findings require further confirmation.

Three dimensional time-of-flight magnetic resonance angiography in carotid artery surgery: a comparison with digital subtraction angiography

Three dimensional time-of-flight magnetic resonance angiography (MRA) and intra-arterial digital subtraction angiography (DSA), considered the gold-standard technique, were compared for pre- and postoperative evaluation of the carotid bifurcation. Images of suitable quality of 194 bifurcations were available with both techniques. Percentage stenosis was graded into 5 groups: A = 0-29%, B = 30-59%, C = 60-89%, D = 90-99%, E = 100% (occlusion). Preoperative MRA (126 bifurcations) overgraded the stenosis in 14 cases and undergraded it in 11. The two techniques agreed in 101 cases and the extent of misgrading was never more than one category. Regression analysis showed a good correlation between the two methods. Severe ulceration was better identified by DSA. As far as the surgical indication was concerned, MRA had a sensitivity of 92.6% and a specificity of 98.3%. In 68 operated cases, postoperative MRA and intraoperative completion angiography showed a satisfactory endarterectomy with no residual stenosis in any of the cases. In conclusion, MRA seems an accurate modality for imaging of carotid bifurcations. Significant limitations still exist for an adequate demonstration of intracranial circulation.

Superficial siderosis of the CNS: MR diagnosis and clinical findings

PURPOSE

To report the clinical and neuroradiologic findings of superficial siderosis of the CNS, due to chronic subarachnoid bleeding of unknown origin.

MATERIALS AND METHODS

We observed seven cases. The main clinical manifestations were progressive deafness and ataxia. Four patients had had previous cranial or cervical trauma, with root avulsion in two, many years before onset of deafness and ataxia. Neuroradiologic studies included MR (0.5 T in four and 1.5 T in three) and angiography of the brain in all cases, CT in six cases, MR of the spine in six, and myelography in four.

RESULTS

MR demonstrated a rim of marked hypointensity in T2-weighted images, consistent with hemosiderin deposits, on the surface of cerebellum, brain stem, inferior part of cerebral hemispheres, and spinal cord. CT showed cerebellar atrophy in five cases, and a rim of mild hyperdensity around the brain stem in two. Angiographic studies were negative. Myelography showed cervical nerve root avulsion in two cases and a cervicodorsal extradural cyst in one. Cerebrospinal fluid contained RBCs in all the six examined cases.

CONCLUSION

Although CT may occasionally suggest the diagnosis of superficial siderosis, MR demonstrates this abnormality to better advantage.

Brain stem magnetic resonance imaging and evoked potential studies of symptomatic multiple sclerosis patients

In this study we evaluated the sensitivity of neuroradiological and neurophysiological tests for detecting brain stem (BS) lesions in multiple sclerosis patients, since the recent introduction of the gradient motion rephasing technique has markedly increased the image quality of magnetic resonance imaging (MRI). From 50 MS patients (33 women and 17 men; mean age 35.9 +/- 8.3 years; mean duration of the disease 7.2 +/- 4.1 years) with clinical signs of BS involvement, brain MRI, BS auditory evoked potentials (BAEPs), and left and right median somatosensory evoked potentials (mSEPs) were obtained. BS MRI lesions were detected in 41 patients (82%); in 14 cases they were located in the medulla oblongata, in 55 in the pons, and in 24 in the midbrain. Single lesions were present in 20 patients, while two or more BS lesions were demonstrated in 21 patients; 30 patients had at least one lesion located close to the inner or the outer cerebrospinal fluid border. BAEPs were abnormal in 19 of the 50 patients (38%), and BS components of mSEPs were abnormal in 15 of 46 (33%). With combined use of these neurophysiological techniques, BS abnormalities were revealed in 24 patients (48%). Only 1 patient had neurophysiological BS abnormalities and normal MRI. Moreover, there was a good correlation (74%) between the clinical and MRI BS findings in the 23 patients with signs referable to focal neurological BS lesions. The concordances considering clinical and evoked potential reports were positive, but less marked.(ABSTRACT TRUNCATED AT 250 WORDS)

Solitary plasmacytoma of the sphenoid sinus involving the pituitary fossa: a case report and review of the literature

A rare case of solitary plasmacytoma of the sphenoid sinus involving the pituitary fossa is reported. A 50-year-old woman with a history of diplopia and a mass in the sphenoid sinus and the sellar region, documented by computed tomography, was referred to our department with a presumed diagnosis of nonfunctioning pituitary adenoma. The clinical and biochemical characteristics were unrevealing, but magnetic resonance imaging examination demonstrated the extrapituitary origin of the lesion. The patient was operated on by the transsphenoidal approach, and the lesion was histologically diagnosed as a plasmacytoma. Review of the literature disclosed 11 previously described cases of myelomatous disease presenting clinically as a pituitary adenoma. Our case demonstrates that magnetic resonance imaging investigation may help in distinguishing the extrapituitary origin of a mass involving the pituitary fossa.

Paraclinical tests in acute-onset optic neuritis: basal data and results of a short follow-up

Up to now it is still doubtful whether there is a real risk of developing multiple sclerosis (MS) after initial monosymptomatic optic neuritis (ON). In this study we evaluated 43 patients with isolated acute-onset ON, in order to demonstrate the presence of oligoclonal bands (OBs) in the cerebrospinal fluid (CSF) and any additional clinically silent central nervous system (CNS) lesions. All examinations were performed from 5 days to 4 months (mean 43 days), from the onset of visual disturbances. Brain magnetic resonance imaging (MRI) detected white matter areas with increased signal in 21 patients (49%), while somatosensory and brainstem auditory evoked potentials revealed CNS abnormalities in only 5 patients (12%). OBs were present in the CSF of 20 patients (46%). Visual evoked potentials were abnormal in 39 patients (91%). Seven out of the 37 patients (19%) with at least one year follow-up, (mean duration of the follow-up = 32 months, range = 12-74), developed clinically definite MS (CDMS). All 7 patients had positive brain MRI and 6 had positive CSF examination at the basal evaluation. Our data suggest that MRI and CSF-OBs are the most reliable means of identifying patients with isolated ON who subsequently develop CDMS. They may therefore have a predictive value in defining MS risk.

Head holder for PET, CT, and MR studies

A new head holder for the fixation and repositioning of the patient head in PET, CT, and MR scanners has been designed and tested. With this device, a bidimensional correlation between functional and anatomical brain images can also be obtained. Head fixation and repositioning are achieved using the patient's dental morphology as an anatomical reference. With a dentistic material, a mold of the patient's teeth is obtained in a few minutes. The molding substance rests on a plastic support, fixed to the head holder. Each time the patient undergoes a new study, his/her personal mold is used, ensuring accurate head repositioning. External markers fixed on the head holder (made visible in lateral PET and CT projection images, midsaggital MR images, and also on the axial images) make it possible to record and recognize the angular orientation and the position of the brain in the three-dimensional space, to correlate images of the same patient obtained with different neuroimaging modalities, and to accurately reposition patients for follow-up studies. The head holder was tested on several subjects. Fixation and repositioning accuracy of within 2.5 mm were achieved in the three-dimensional space. Orientation accuracy was 1 degree.

Hypothalamic-pituitary dysfunction in growth hormone-deficient patients with pituitary abnormalities

Hypothalamic-pituitary function was studied in 45 patients with idiopathic GH deficiency (GHD), 33 of whom had pituitary abnormalities on magnetic resonance imaging: pituitary hypoplasia, undescended stalk and ectopia of the posterior lobe in 8 patients with isolated GHD (IGHD) (group I) and in 12 patients with multiple pituitary hormone deficiency (MPHD) (group II); isolated pituitary hypoplasia in 13 patients with IGHD (group III); no evidence of pituitary abnormalities in the remaining 12 patients with IGHD (group IV). Sellar and pituitary volumes were significantly lower in groups I, II, and III than in group IV (P less than 0.001). No significant differences were observed between group I and group II in the GH response to GHRH1-44 expressed both as peak serum GH and area under the curve. Mean GH peak in group III and IV was significantly higher than that in group I (P less than 0.005) and II (P less than 0.001), as were the mean AUC (P less than 0.005), suggesting hypothalamic defect. Delayed peak serum TSH after TRH was found in all patients of group II, and overt hypothyroidism in 11 of them. Furthermore, basal hyperprolactinemia was present in 6 patients and adrenal insufficiency in 7 cases of group II. Finally, a reduced response of FSH to GnRH was observed in all these patients (P less than 0.005 vs. each of the other groups), and clinical hypogonadism was present in all of them. We suggest that: 1) A high incidence of pituitary abnormalities seems to be present in idiopathic GHD patients; 2) Pituitary hormone deficiencies are more dependent on the type of the hypothalamic-pituitary abnormality than on the size of the pituitary per se: the association of pituitary hypoplasia, undescended stalk and ectopia of the posterior lobe should possibly be considered a distinct entity reflecting an early abnormality in hypothalamic development; 3) The majority of patients with IGHD or MPHD probably have a primary hypothalamic releasing hormone deficiency even if pituitary hypoplasia is associated; 4) Magnetic resonance imaging may have a role in the diagnosis and prognosis of patients with GHD through differentiation between patients who are at risk for developing MPHD vs. those who are candidates for having a persistently isolated GHD.

Hypopituitarism and stalk agenesis: a congenital syndrome worsened by breech delivery?

Thirty-seven patients with idiopathic hypopituitarism, of whom 12 had multiple pituitary hormone deficiencies (MPHD) and 25 isolated growth hormone deficiency (IGHD), were evaluated by magnetic resonance imaging (MRI). Twenty-two of the 37 showed congenital anterior pituitary hypoplasia, stalk agenesis and ectopic posterior pituitary gland at the infundibular recess (group A), while the remaining 15 presented isolated anterior pituitary hypoplasia (group B). Perinatal histories obtained from all patients demonstrated that 18/22 children of group A (81.81%) had histories of adverse perinatal events, with breech presentation in 15 (68.18%). Twelve of 12 children of group A born by breech delivery developed MPHD; 3 born by cesarean section for breech presentation had only IGHD. Patients of group B had also a high incidence of perinatal insults (12/15, 80%), but breech delivery was markedly less frequent (13.33 vs. 68.18% of group A) and responsible for only IGHD. Group B had also higher percentages of maternal spontaneous abortion and low birth weight. Our study suggests that several factors may play a role in the development of growth hormone deficiency. Some patients had severe perinatal insults apparently leading to hypopituitarism. We were able to define by MRI a group of patients with congenital abnormalities, such as anterior pituitary hypoplasia, stalk agenesis and posterior pituitary ectopia, among whom breech presentation was very common. In this group, breech delivery was always followed by MPHD while cesarean or normal delivery in such patients was followed by IGHD only.

Growth hormone deficiency in children: role of magnetic resonance imaging in assessing aetiopathogenesis and prognosis in idiopathic hypopituitarism

To search for the presence of morphostructural abnormalities of the hypothalamus-pituitary region in growth hormone deficient (GHD) children magnetic resonance imaging (MRI) was performed in 30 GHD patients (age 10.09 +/- 3.5 years) and in 15 healthy age-matched controls. MRI demonstrated a significantly small sella and pituitary volume compared to controls and normal literatures values. In 20 patients the structures were extremely small and an abnormal development of the pituitary stalk was observed, and in 18 of these patients the bright spot indicating the neurohypophysis was dislocated to the distal part of the maldeveloped stalk, although these children had a normal fluid balance. From a functional point of view hypothalamus and pituitary defects were equally distributed between the two morphological groups. The patients with multiple endocrine defects had the smallest pituitary volume and abnormal stalk. A possible pathogenetic role of perinatal trauma or dysembryogenic events are discussed. A careful follow up of patients with isolated GHD presenting MRI abnormalities of the pituitary is suggested for the possible evolution in panhypopituitarism.

Hypothalamic-pituitary dwarfism: comparison between MR imaging and CT findings

Magnetic Resonance (MR) imaging was carried out on 33 patients with idiopathic growth hormone deficiency, in 22 of whom CT scan had been carried-out previously. Twenty-one patients presented some complications at birth. Both MR and CT were positive in the evaluation of the sella. MR imaging exhibited a higher degree of accuracy than CT in the evaluation of pituitary gland, pituitary stalk and brain anomalies. On the basis of pituitary morphology demonstrated by MR imaging, and perinatal histories, a classification is proposed which divides our patients into three group: A) a first group of 13 patients presenting severe hypoplasia of the anterior pituitary lobe, hypoplasia of the stalk and ectopia of posterior lobe. The underlying cause of these anatomic defects might be developmental in origin, and date from early intrauterine life, probably worsened at birth. B) a second group of 10 patients presenting severe hypoplasia of the anterior pituitary lobe. A perinatal event and birth trauma might be responsible for pituitary damage. C) a third group of 10 patients with no morphological abnormalities of the pituitary gland. A derangement of the neuroendocrine mechanism which control the growth hormone secretion might account for these patients.

Evidence of morphological and functional abnormalities in the hypothalamus of growth-hormone-deficient children: a combined magnetic resonance imaging and endocrine study

Fifty-seven children with growth hormone deficiency and 15 healthy age-matched controls were studied by magnetic resonance imaging (MRI). Of the patients, 36 (63%) had isolated GH deficiency (IGHD) and 21 (37%) multiple pituitary hormone deficiency (MPHD). MRI studies showed a marked reduction in pituitary volume in all patients in comparison with normal controls. Moreover, a striking morphological abnormality with the apparent absence of the pituitary stalk and an ectopic posterior pituitary lobe was detected in 34 of the patients (59%). This pituitary stalk abnormality was detected in 95% of the MPHD patients and in 39% of the IGHD patients. All but one of the patients with a normal pituitary stalk had IGHD. Endocrine evaluation showed no correlation with MRI data: in particular patients with an apparent anatomical interruption of the hypothalamic-pituitary axis showed a variety of patterns of hormonal responses. In conclusion, our study shows a high frequency of hypothalamic-pituitary anomalies in patients with GH deficiency, particularly related with MPHD. However, further studies are needed to improve our understanding of the relationship between MRI and endocrine data.

Focal cerebral lesions found by magnetic resonance imaging in cryptogenic nonrefractory temporal lobe epilepsy patients

Brain magnetic resonance imaging (MRI) was studied in patients with mild-to-moderate temporal lobe epilepsy (TLE), well controlled by pharmacotherapy, and with normal computed tomographic (CT) scans. Magnetic resonance imaging abnormalities were found in 19 patients; of these, nine had abnormalities in temporomesial regions and four in temporobasal regions. Six patients had white matter MRI lesions of nonspecific significance. The temporomesial MRI lesions were compatible with sclerosis of Ammonis cornu. Patients with this MRI finding had more severe and longer lasting TLE than those without MRI abnormalities. The temporobasal lesions were interpreted as potentially developing brain lesions. Correlation between EEG and MRI findings was good. We conclude that MRI is more useful than CT for diagnosis of patients with mild-to-moderate TLE.

Electrophysiological and MRI evaluation of neurological involvement in Behçet's disease

Eight patients with stable Behçet's disease were studied by means of multimodality evoked potentials and magnetic resonance imaging to evaluate the possibility of an earlier and objective demonstration of clinical and subclinical Central Nervous System (CNS) involvement. It was shown that both diagnostic techniques are useful for quantitative evaluation of neurological involvement in Behçet's disease; of particular interest was the demonstration of subclinical CNS changes.