Quantitative volumetric analysis of gliomas with sequential MRI and ¹¹C-methionine PET assessment: patterns of integration in therapy planning.

PURPOSE: The aim of the study was to evaluate the volumetric integration patterns of standard MRI and (11)C-methionine positron emission tomography (PET) images in the surgery planning of gliomas and their relationship to the histological grade. METHODS: We studied 23 patients with suspected or previously treated glioma who underwent preoperative (11)C-methionine PET because MRI was imprecise in defining the surgical target contour. Images were transferred to the treatment planning system, coregistered and fused (BrainLAB). Tumour delineation was performed by (11)C-methionine PET thresholding (vPET) and manual segmentation over MRI (vMRI). A 3-D volumetric study was conducted to evaluate the contribution of each modality to tumour target volume. All cases were surgically treated and histological classification was performed according to WHO grades. Additionally, several biopsy samples were taken according to the results derived either from PET or from MRI and analysed separately. RESULTS: Fifteen patients had high-grade tumours [ten glioblastoma multiforme (GBM) and five anaplastic), whereas eight patients had low-grade tumours. Biopsies from areas with high (11)C-methionine uptake without correspondence in MRI showed tumour proliferation, including infiltrative zones, distinguishing them from dysplasia and radionecrosis. Two main PET/MRI integration patterns emerged after analysis of volumetric data: pattern vMRI-in-vPET (11/23) and pattern vPET-in-vMRI (9/23). Besides, a possible third pattern with differences in both directions (vMRI-diff-vPET) could also be observed (3/23). There was a statistically significant association between the tumour classification and integration patterns described above (p < 0.001, κ = 0.72). GBM was associated with pattern vMRI-in-vPET (9/10), low-grade with pattern vPET-in-vMRI (7/8) and anaplastic with pattern vMRI-diff-vPET (3/5). CONCLUSION: The metabolically active tumour volume observed in (11)C-methionine PET differs from the volume of MRI by showing areas of infiltrative tumour and distinguishing from non-tumour lesions. Differences in (11)C-methionine PET/MRI integration patterns can be assigned to tumour grades according to the WHO classification. This finding may improve tumour delineation and therapy planning for gliomas.

New MRI, 18F-DOPA and 11C-(+)-alpha-dihydrotetrabenazine templates for Macaca fascicularis neuroimaging: advantages to improve PET quantification.

Normalization of neuroimaging studies to a stereotaxic space allows the utilization of standard volumes of interest (VOIs) and voxel-based analysis (SPM). Such spatial normalization of PET and MRI studies requires a high quality template image. The aim of this study was to create new MRI and PET templates of (18)F-DOPA and (11)C-(+)-alpha-dihydrotetrabenazine ((11)C-DTBZ) of the Macaca fascicularis brain, an important animal model of Parkinson's disease. MRI template was constructed as a smoothed average of the scans of 15 healthy animals, previously transformed into the space of one representative MRI. In order to create the PET templates, (18)F-DOPA and (11)C-DTBZ PET of the same subjects were acquired in a dedicated small animal PET scanner and transformed to the created MRI template space. To validate these templates for PET quantification, parametric values obtained with a standard VOI-map applied after spatial normalization to each template were statistically compared to results computed using individual VOIs drawn for each animal. The high correlation between both procedures validated the utilization of all the templates, improving the reproducibility of PET analysis. To prove the utility of the templates for voxel-based quantification, dopamine striatal depletion in a representative monkey treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was assessed by SPM analysis of (11)C-DTBZ PET. A symmetric reduction in striatal (11)C-DTBZ uptake was detected in accordance with the induced lesion. In conclusion, templates of M. fascicularis brain have been constructed and validated for reproducible and automated PET quantification. All templates are electronically available via the internet.

Intraoperative 3 tesla magnetic resonance imaging: our experience in tumors. / Resonancia magnética intraoperatoria de 3 teslas: Nuestra experiencia en patología tumoral.

OBJECTIVE: To report our experience in the use of 3 tesla intraoperative magnetic resonance imaging (MRI) in neurosurgical procedures for tumors, and to evaluate the criteria for increasing the extension of resection. MATERIAL AND METHODS: This retrospective study included all consecutive intraoperative MRI studies done for neuro-oncologic disease in the first 13 months after the implementation of the technique. We registered possible immediate complications, the presence of tumor remnants, and whether the results of the intraoperative MRI study changed the surgical management. We recorded the duration of surgery in all cases. RESULTS: The most common tumor was recurrent glioblastoma, followed by primary glioblastoma and metastases. Complete resection was achieved in 28%, and tumor remnants remained in 72%. Intraoperative MRI enabled neurosurgeons to improve the extent of the resection in 85% of cases. The mean duration of surgery was 390±122minutes. CONCLUSION: Intraoperative MRI using a strong magnetic field (3 teslas) is a valid new technique that enables precise study of the tumor resection to determine whether the resection can be extended without damaging eloquent zones. Although the use of MRI increases the duration of surgery, the time required decreases as the team becomes more familiar with the technique.

Primary central nervous system lymphoma treated with rituximab plus temozolomide in a second line schedule.

We report a case of primary CNS lymphoma treated with high-dose methotrexate in the first line. After disease progression the patient received cranial radiotherapy with concomitant temozolomide, followed by rituximab plus temozolomide, with complete remission of the disease maintained for at least two years and without major toxicity.

[Neuroradiologic findings of glutaric aciduria type I]. / Hallazgos neurorradiológicos de la Acidosis Glutárica tipo I.

Glutaric aciduria type I is a rare disorder of organic acid metabolism caused by deficiency of glutaryl-CoA dehydrogenase, a mitochondrial enzyme. Improper degeneration of amino acids: tryptophan, lysine, and hydroxylysine, results in increased levels of glutaric acid, which typically becomes clinically manifest as an acute dystonic crisis in young children. Accumulation of glutaric acid causes neurotoxicity in the basal ganglia and fronto-temporal cortex which can lead to progressive dystonia, hypotonia, permanently impaired speech and seizures. Because dietary and drug therapy may alter the natural history of the disease, early diagnosis of such patients is critical. We report the magnetic resonance (MR) imaging findings in a 16 year-old girl with this disorder who presented with a chronic dystonic syndrome and previously diagnosed of brain paralysis. MR imaging demonstrated bilateral involvement of the putamina and periventricular white matter, and bilateral temporal atrophy and widened Silvian fissures.

Intra-arterial and intravenous chemotherapy for the treatment of malignant glioma. Preliminary results.

Twenty-one patients with malignant glioma were treated with cis-diamminedichloroplatinum II (CDDP II) 60-90 mg/m2 intra-arterial (I.A.) bolus on day 1 and Carmustine (BCNU) 100 mg/m2 intravenously (I.V.) on days 1 and 2. Three patients received additional Aziridinylbenzoquinone (AZQ) 7 mg/m2 (I.V.) on days 1 and 2. At the time of this treatment, seven patients had local recurrence after previous surgery and radiotherapy. Nine patients had subtotal tumor resection or biopsy, one patient had macroscopic tumor resection, and four patients had no previous surgery because of medical contraindication. Six patients received five or more courses of I.A. and I.V. chemotherapy. Five of these patients showed complete remission (CR) and one had a partial remission (PR) by brain computerized tomography (CT scan). Another 15 patients treated with two to four courses of I.A., and I.V. chemotherapy showed eight partial responses (PR), and seven showed no changes (NC) by brain CT scan. Five patients died with disease. Patients who achieved CR also received radical radiotherapy for remission consolidation. Sixteen patients are still alive; five patients are off treatment, four of these with no evidence of disease (NED), one alive with disease (AWD); and the remaining 11 patients are still on treatment. Toxicity, symptomatic neurological recovery, disease stabilization, and causes of death will be discussed.

Magnetic resonance imaging in a patient with a dual-chamber pacemaker.

The presence of an implanted cardiac pacemaker has been considered an absolute contraindication for magnetic resonance imaging due to the interactions between the pulse generators and the magnetic and radiofrequency fields generated by the magnetic resonance unit. We describe the case of a patient with a dual-chamber pacemaker who underwent two magnetic resonance imaging examinations of the head without any sequelae. Both procedures were performed with a 1 Tesla unit, with the pacemaker programmed to the AOO mode. The only interference observed was activation of the reed switch -probably due to the static magnetic field- resulting in asynchronous atrial pacing at the magnet rate. Although the general policy of never exposing a patient with a pacemaker to magnetic resonance imaging should not be revised, we think that if the testing is considered essential, it could be safely used in certain carefully selected patients.

[Surgery of the posterior semicircular duct for the treatment of BPPV]. / Cirugía del conducto semicircular posterior para el tratamiento del VPPB.

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo in the otolaryngology clinic. The liberatory maneuvers are the treatment of choice in this entity. In a low percentage of patients, about 5-10%, we found no response to the maneuvers. The occlusion of the posterior semicircular canal is offered for intractable cases. We report a case of woman with an intractable BPPV in which an occlusion of the posterior semicircular was done. We describe the indications, how to perform the surgery and the functional results of this technique.

Effect of brightness in the evaluation of lumbar pedicular screws position: clinical study.

Artifact may lead to confusion when evaluating postoperative CT scans of lumbar pedicle screws. The aim of our study was to develop a specific metal artifact reduction image protocol, in order to reduce metal artifact caused by titanium pedicular screw in patients undergoing lumbar pathology by lumbar fusion. Therefore, the reduction in metal artifacts in lumbar pedicle screws allows surgeons to do an accurate diagnosis of the exact placement of inserted pedicle screws, minimizes false reexploration, and maximizes proper and prompt treatment of misplaced screw. In a first step, we performed a retrospective study of 103 titanium alloy pedicle screws in patients undergoing a lumbar instrumented fusion for treatment for degenerative disease. CT scan was performed postoperatively evaluating the possible overdimension caused by artifact. In a second step, a prospective study was performed using a 64-slice multidetector-row computed tomography (MDCT) in 104 titanium alloy pedicle screws in patients undergoing a lumbar instrumented fusion for treatment for degenerative disease. Our results show that on the group of sequential CT scan, mean overdimension (on each side) due to brightness was 1.045 mm (SD 0.45). On the group of 64-slice multichannel CT, mean overdimension (on each side) due to brightness was 0.005 mm at the proximal part of the screw and 0.025 mm at the distal part of the screw. The results observed suggest that beam-hardening artifacts caused by the screw on CT after lumbar fusion are dramatically reduced by using specific metal artifact reduction image protocol in a 64-slice MDCT.

[Neuroimaging in brain tumors]. / Neuroimagen de los tumores cerebrales.

Advances in neuroimaging have modified diagnosis, treatment and clinical management of brain tumors. However, neuropathological study remains necessary in order to get the best clinical management. Surgery and radiotherapy planning are imaging-dependent procedures, and MRI is the standard imaging modality for determining precisely tumor location and its anatomical relationship with surrounding brain structures. In high-grade tumors it has been accepted that tumoral areas with contrast uptake in CT, or T1-weighted MRI contrast enhancement corresponds to solid tumor. However, relationship between MRI and invasive tumor areas remains less defined. Therefore, it is generally accepted that conventional MRI is not sufficient to delineate the real extension of brain tumors. In recent years, PET using 18FDG and amino acid radiotracers ((11)C-Methionine, (18)FDOPA, (18)FET) and SPECT with (201-)Thallium, as well as advanced MRI sequences (Perfusion, Diffusion-weighted, Diffusion tensor imaging and tractography), and functional MRI, have added important complementary information in the characterization, therapy planning and recurrence differential diagnosis of brain tumors. In this continuing education review of neuroimaging in brain tumors, technical aspects and clinical applications of different imaging modalities are approached in a multidisciplinary way.

[Stereotactic radiation therapy]. / Radioterapia estereotáctica.

Stereotactic radiotherapy is a form of external radiotherapy that employs a system of three dimensional coordinates independent of the patient for the precise localisation of the lesion. It also has the characteristic that the radiation beams are conformed and precise, and converge on the lesion, making it possible to administer very high doses of radiotherapy without increasing the radiation to healthy adjacent organs or structures. When the procedure is carried out in one treatment session it is termed radiosurgery, and when administered over several sessions it is termed stereotactic radiotherapy. Special systems of fixing or immobilising the patient (guides or stereotactic frames) are required together with radiotherapy devices capable of generating conformed beams (lineal accelerator, gammaknife, cyberknife, tomotherapy, cyclotrons). Modern stereotactic radiotherapy employs intra-tumoural radio-opaque frames or CAT image systems included in the irradiation device, which make possible a precise localisation of mobile lesions in each treatment session. Besides, technological advances make it possible to coordinate the lesion's movements in breathing with the radiotherapy unit (gating and tracking) for maximum tightening of margins and excluding a greater volume of healthy tissue. Radiosurgery is mainly indicated in benign or malign cerebral lesions less than 3-4 centimetres (arteriovenous malformations, neurinomas, meningiomas, cerebral metastases) and stereotactic radiotherapy is basically administered in tumours of extracraneal localisation that require high conforming and precision, such as inoperable early lung cancer and hepatic metastasis.

[Adenocarcinoma of the endolymphatic sac in von Hippel-Lindau disease. A case report]. / Adenocarcinoma del saco endolinfático en la enfermedad de von Hippel-Lindau. A propósito de un caso.

Tumors originating in the endolymphatic system are extremely rare, and very few articles have been published about this type of tumors. Up to 15% of cases are associated to von Hippel-Lindau disease. This article describes the case of a patient previously diagnosed with von Hippel-Landau disease that presented a sudden loss of hearing in the left ear. Specific imaging tests (computed tomography [CT] and magnetic resonance imaging [MRI]) showed the presence of a neoplasm originating in the left endolymphatic sac. Histological analysis of the surgical specimen determined it corresponded to an adenocarcinoma of the endolymphatic sac.

Preliminary CT study of C1-C2 rotational mobility in normal subjects.

A CT study of normal atlanto-axial (C1-C2) rotary mobility was carried out on ten normal immature subjects. In order to determine the limits of normality, the ten children underwent clinical and radiological examination. The clinical study included checking for objective signs of joint laxity and measurement of rotational neck mobility. The radiological study included standard lateral radiographs in neutral and maximal flexion positions and a CT scan taken in maximal left and right side rotation at the C1-C2 articular processes joint. The superpositioning of the images taken in every rotational direction showed, in all ten children, a wide contact loss between the C1-C2 corresponding facets, ranging from 74 to 85% of the total articular surface. The report on these images, carried out by three independent radiologists, concluded that there was a rotary subluxation in all cases. In the ten children studied, there were no significant differences with regard to neck mobility or laxity signs in clinical or standard X-ray examination. Our results lead us to conclude that, except for complete C1-C2 rotational dislocation with facet interlocking, a CT scan showing a wide - but incomplete - rotational facet displacement is not sufficient to define a status of subluxation. This leads us to perceive that there is a risk of overdiagnosis when evaluating upper cervical spine rotational problems in children. The concept of both rotary C1-C2 fixation and subluxation should be revised.

Osteoid osteoma in the lumbar and sacral regions: two cases of difficult diagnosis.

We present two cases of osteoid osteoma affecting a lumbar vertebral body and the sacrum, being both in a very infrequent localization and difficult diagnosis. We found the scintigraphy to be of invaluable assistance in revealing the presence of this small nodular lesion of the spine, and the computed axial tomography (CAT) scan study was likewise useful for its precision in localizing the tumor as a basis for deciding upon a viable surgical approach. Without such techniques, correct diagnosis may be made too late. In our experience, surgical resection of the osteoid osteoma brings about immediate relief of the symptoms.

[Paraclinical tests in multiple sclerosis. Clinical correlation and predictive value]. / Tests paraclínicos en la esclerosis múltiple. Correlación clínica y valor predictivo.

The correlation between clinical signs and symptoms, Evoked Potentials (EP) and Magnetic Resonance Imaging (MRI) in Multiple Sclerosis (MS) is still uncertain. It seems necessary to perform comparative studies with homogeneous groups of patients to avoid the error provoked by the selection of patients and the use in the diagnosis of EP and MRI. The aims of this paper were to calculate the sensitivity of EP and MRI in MS in relation to time of evolution and type of MS, to determine the correlation between clinical data and EP and MRI alterations, and to show the predictive value of the paraclinical tests. We have performed clinical examination, EP and MRI in 47 patients with clinically definite MS, Poser's category 1a, without acute attack. Our results show significant correlation between VEP and visual functional scale (FS) (r = 0.43), brainstem auditory EP (BAEP) and Expanded Disability Status Scale (EDSS) (r = 0.33), BAEP and cerebellar FS (r = 0.36), BAEP and brainstem FS (r = 0.29) and somatosensory EP (SEP) and pyramidal FS (r = 0.4). Also, we found significant correlation among clinical data and MRI abnormalities in cerebellum (p < 0.01), brainstem (p < 0.001), and spinal cord (p < 0.01). The SEP (74%), cerebellar (92%) and spinal (83%) MRI alterations provided the greatest agreement with presumed clinical abnormalities. These data confirm the efficacy of EP and MRI to describe the status of MS and support its utility to evaluate the evolution.

Magnetic resonance angiography in meningovascular syphilis.

Meningovascular neurosyphilis (MN) is an unusual cause of stroke in young adults. The clinical manifestations include prodromal symptoms weeks or months before definitive stroke. The diagnosis is based on clinical findings and examination of the serum and cerebrospinal fluid. We report a case of MN with basilar artery irregularities demonstrated by magnetic resonance angiography.