Resistive NMR of brain stem gliomas

Pediatric brainstem abscess with hemorrhage mimicking diffuse intrinsic pontine glioma: a case report

PURPOSE

We report a rare case of brainstem abscess with hemorrhage mimicking diffuse intrinsic pontine glioma (DIPG).

METHODS

A 7-month-old baby girl presented with lethargy and poor oral feeding. She had the mild fever for 1 month. Brain computed tomography revealed the hypodense lesion in the pons. Brain magnetic resonance images (MRI) showed around 1.4-cm-sized rim-enhanced mass with perilesional edema and internal hemorrhage in the pons. The cerebral blood volume was increased in the rim-enhanced area. The provisional diagnosis was DIPG, but the mass did not show the expansile mass with encasement of the basilar artery on the ventral pons.

RESULTS

The biopsy was done via the floor of the fourth ventricle, and the pathologic findings showed the many inflammatory cells and CD68-immunopositive macrophage which were compatible with abscess. The antibiotics with ceftriaxone and metronidazole were administrated for 11 weeks, and the follow-up MRI showed the slightly small enhanced lesion without central necrotic area. Three years later, follow-up MRI revealed the encephalomalacic change and atrophy of the pons. She had the stable neurologic deficit of left facial palsy and right hemiparesis.

CONCLUSION

The biopsy could be necessary for pontine lesions without typical radiologic findings of DIPG.

Diffuse intrinsic pontine glioma: a reassessment

Diffuse intrinsic pontine glioma (DIPG) is a disease of childhood whose abysmal prognosis has remained unchanged for over 50 years. Biologic investigation has been stymied by lack of pretreatment tissue, as biopsy has been reserved for atypical cases. Recent advances in surgical and molecular-analytic techniques have increased the safety and potential utility of biopsy; brainstem biopsy has now been incorporated into several prospective clinical trials. These and other recent efforts have yielded new insights into DIPG molecular pathogenesis, and opened new avenues for investigation.

Experimental study of medullary trigeminal evoked potentials: development of a new method of intraoperative monitoring of the medulla oblongata

OBJECT

The goal of this study was to develop a new method of intraoperative monitoring of functions located in the lateral portion of the medulla oblongata. Based on the fact that the spinal trigeminal nucleus and tract are located in the lateral portion of the medulla oblongata, the authors intended to investigate the efficacy of trigeminal evoked potentials (TEPs) in intraoperative monitoring for assessing functions of the medulla oblongata.

METHODS

Trigeminal evoked potentials induced by electrical stimulation of the infraorbital nerve were recorded from the dorsolateral portion of the medulla oblongata (M-TEP) and the cerebral sensory cortex (C-TEP) in dogs. When the lateral one-sixth portion of the medulla was cut, the amplitude of the M-TEP decreased markedly, but the amplitude of the C-TEP and the somatosensory evoked potential (SSEP) did not decrease. When the lateral one-third portion of the medulla was cut, the amplitude of the SSEP decreased, but that of the C-TEP showed no change. When the medulla was retracted, the amplitude of the M-TEP was more sensitive than that of SSEP. Pathological examinations revealed that retraction force less than 10 g and a reduction in the amplitude of the M-TEP less than 50% were safe.

CONCLUSIONS

These results suggest that M-TEPs obtained from the dorsolateral portion of the medulla oblongata by electrical stimulation of the trigeminal nerve are clinically applicable as a new means of intraoperative monitoring of the functions of the medulla oblongata.

Aqueduct stenosis--presentation and prognosis

In the 14-year period from 1974-1987 during which CT scanning was available in Edinburgh, 36 patients with benign, non-tumour related aqueduct stenosis were identified from a group of 342 patients with hydrocephalus. In terms of age at presentation, the patients separate into two groups, 9 cases diagnosed during the first year of life and 27 patients aged from 7 to 72 years. The presentation in the early cases was fairly acute, the diagnosis was secure and the operative treatment by ventricular peritoneal shunt was relatively free of complications. In the older patients, the first presentation was more chronic, and further investigation required a change of diagnosis in 5 of the 27 patients. More than half of the patients had recurrent symptoms which were much more acute and operative treatment was attended by a significant number of complications including death from intraventricular haemorrhage in one case.

A comparative study of CT and MRI in midline tumors of childhood and adolescence

In order to compare the validity of CT and MRI, we evaluated results of these studies in 40 children and adolescents suffering from supratentorial and infratentorial midline tumors. Plain and enhanced CT scans were compared with MRI for sensitivity, specificity and capacity to delineate the tumor. These parameters were evaluated by three independent investigators on a scale with four grades of accuracy. The results demonstrate greater sensitivity and better delineation of the tumor with MRI, but greater specificity in diagnosis of tumors with CT studies.

Lesions of the brain stem: assessment by magnetic resonance imaging

Ninety-six magnetic resonance imaging (MRI) studies demonstrating solitary brain stem lesions were reviewed in order to establish distinguishing features between tumours and other lesions. Histological confirmation of the radiological diagnoses was obtained in 33% of patients. The morphology of the lesion rather than its signal characteristics was the most useful feature in differential diagnosis, except after haemorrhage. However, areas of abnormal T2 recovery time were significantly more extensive than areas of abnormal T1 recovery time in tumours at presentation. In other lesions and in tumours following radiotherapy induced regression, the extent of abnormal T1 and T2 signal was the same. Possible reasons for this observation are discussed. The accuracy of computed tomography (CT) and MRI were similar for lesions causing brain stem expansion but for small lesions MRI was more sensitive and provided better topographical information.

MRI assisted treatment planning for radiation therapy of the head and neck

Improved visualization of head and neck tumors has been demonstrated with the use of magnetic resonance imaging (MRI). Using standard plastic radiation therapy immobilization casts and an MR positive surface marker system developed in this institution, we have utilized MRI as an adjunct to the simulation of complex radiation treatments for tumors of the head and neck. This technique includes an indirect display of field margins and/or isodose curves over selected MR images. The lack of induced artifact from the immobilization cast, improved delineation of tumor extension from normal anatomy and the ability to image in arbitrary planes without changing patient positioning favor the use of MR over CT for radiation therapy planning in the head and neck, while ensuring reproducibility of the treatment plan at subsequent therapy sessions.

Magnetic resonance imaging of the brain and spine

The efficacy of magnetic resonance imaging (MRI) in the diagnosis of diseases of the central nervous system is reviewed. MRI, computed tomography (CT) and certain radionuclide studies are compared in the evaluation of intracranial tumours, cerebral vascular disease, multiple sclerosis and other white matter diseases, dementia, head injury, infection, epilepsy, spinal lesions and in paediatric central nervous system disorders. The measurement of cerebrospinal fluid volumes and dynamics by MRI is discussed. MRI most clearly has advantages where CT is degraded by bone hardening and streak artefacts (spine, skull base, posterior and temporal fossa, sella and parasellar regions) and in diseases in which the X-ray attenuation of the suspected lesion differs little from normal parenchyma (paediatric brain disorders, demyelination and dysmyelination, early oedema associated with infarction, infection or low-grade infiltrating neoplasm, subacute and chronic haemorrhage and lesions in the spinal subarachnoid space and cord). Elsewhere MRI and CT should be seen as complementary rather than competitive methods of imaging. In spite of an absence of information about the contribution of MRI to management decisions and a lack of rigorous, prospective controlled trials, MRI will play an increasing role in the diagnosis of diseases of the central nervous system.

Solitary brainstem metastasis: comparisons of X-ray computed tomography and magnetic resonance imaging to pathology

A case of solitary brainstem metastasis from a bronchogenic adenocarcinoma is presented. X-ray computed tomography, magnetic resonance imaging, and specimens obtained at autopsy are compared. T2 weighted magnetic resonance images provided evidence for the diagnosis of a diffusely infiltrating process, whereas T1 weighted images demonstrated a clearly defined, well demarcated tumor. Contrast enhanced computed tomography supported evidence obtained from the T1 weighted image. At autopsy, the tumor was a well circumscribed pontine metastasis with surrounding edema. The importance of distinguishing between T1 and T2 weighted images is crucial for establishing a correct diagnosis and for instituting proper therapy. In contrast to some reports, we found that the T2 weighted image was misleading in regard to defining the extent of tumor. We conclude that both images must be considered together to provide an accurate diagnostic estimate.

The value of magnetic resonance imaging in treatment planning of nasopharyngeal carcinoma

Seven patients with AJCC Stage T4 nasopharyngeal carcinoma underwent both computed tomographic (CT) and magnetic resonance (MR) examinations prior to radiation therapy treatment planning. Lateral tumor extension into the infratemporal fossa was visualized by MR as less extensive in three cases than suggested by CT, as was inferior extension into the parapharyngeal soft tissues in three cases. MR clarified uncertainties on CT regarding involvement of the pontine cistern in three patients and of the cavernous sinus in two patients. Posterior extension of tumor was underestimated by CT in four of six cases shown by MR to involve the clivus. MR appeared superior in evaluating the presence of parenchymal brain involvement in three cases. The margins of the final boost treatment fields dictated by MR findings differed measurably from those derived from CT in six of seven cases. These findings lend support for greater utilization of MR in treatment planning of nasopharyngeal carcinoma.

Magnetic resonance imaging (MRI) in the diagnosis of cerebral arteriovenous angiomas

Eight patients with angiographically confirmed arteriovenous malformations (AVMs) were studied by CT and MRI. MRI scans were performed with a 0.35 Tesla wholebody scanner using three spin-echo sequences (SE 400/35, SE 1600/35, SE 1600/70). In CT and MRI, pathological findings were obtained in all cases. In MRI AVMs were displayed as lesions of low signal intensity in the applied sequences. Full extent of the lesions as well as the relationship to the surrounding structures were clearly demonstrated in MRI in all patients. Based on the characteristic sequence dependent signal intensity property of the lesions, the differential diagnosis in the sense of an AVM could be obtained by MRI in all cases. Concerning topographical imaging and/or differential diagnosis, MRI was superior to CT in 4 out of 8 cases. MRI offers advantages in the demonstration of AVMs of the cerebral midline, especially in brain stem angiomas.

Applications of magnetic resonance imaging in diseases of the pediatric central nervous system

Magnetic resonance imaging (MRI) is rapidly becoming the initial diagnostic step in the evaluation of gross abnormalities involving the brain or spinal cord in the pediatric patient. Control of patient motion and support of vital functions are critical if future utilization of MRI is to progress beyond its current outpatient diagnostic role. Currently, MRI's noninvasiveness, sensitivity and multiplanar graphic depiction of the disease process are supplanting the more traditional diagnostic modalities of CT, metrizamide CT, and myelography.

Magnetic resonance imaging of midline pediatric cerebral neoplasms

Over 80 cases of pediatric cerebral disease including 60 brain tumors, have been studied by low field 0.12 Tesla resistive NMR proton imaging. In addition, experience has been gained with proton imaging on a superconducting high field 1.5 Tesla system. Comparison of NMR images at both field strength, and comparison of the images to those obtained with high resolution CT is made. Examples of how NMR images can help to plan patient management is presented.