Steffen Reissberg

Classification of Severe Head Injury Based on Magnetic Resonance Imaging

SummaryObject. In 1991 a new pioneering classification of severe head injuries had been proposed, based on CT findings. Unfortunately CT cannot visualise all lesions. Especially brain stem lesions may escape CT in spite of modern equipment, but may be demonstrated by MRI. The high incidence of CT negative but MRI positive posttraumatic brain stem lesions has already been demonstrated in a limited number of cases. A statistically significant evaluation is still missing. Therefore we have investigated a series of 102 comatose patients, in whom a statistical evaluation of MRI findings and their correlation with mortality and outcome of survivors was possible. Patients and Methods. MRI was obtained within 8 days after servere head injury in 102 patients with a minimum of 24 hours of coma. The location of the lesions, identified by a neuroradiologist who was unaware of the clinical findings, was correlated with mortality, outcome of surviors and duration of coma. The correlation was analysed statistically. Follow-up ranged from 3 months to 3 years with a mean of 22 months. Four groups of lesions gave significant correlations: Grade I lesions were lesions of the hemispheres only; Grade II lesions were unilateral lesions of the brain stem at any level with or without supratentorial lesions; Grade III lesions were bilateral lesions of the mesencephalon with or without supratentorial lesions. Grade IV lesions were bilateral lesion of the pons with or without any of the foregoing lesions of lesser grades. Results. Mortality increased from 14% in grade I lesions to 100% in grade IV lesions. The Glasgow outcome score differed significantly for each grade. The mean duration of coma increased from 3 days in grade I patients to 13 days in grade III. The correlations between the lesions grade I to IV with mortality, outcome of survivors and duration of coma were highly significant. Conclusion. The statistically significant correlations between the 4 groups of severe head injury patients, as identified by MRI, with mortality and outcome of survivors justify a new classification based on early MRI findings.

Measurement of the noise components in the medical x-ray intensity pattern due to overlaying nonrecognizable structures

There are many aspects that influence and deteriorate the detection of pathologies in X-ray images. Some of those are due to effects taking place in the stage of forming the X-ray intensity pattern in front of the x-ray detector. These can be described as motion blurring, depth blurring, anatomical background, scatter noise and structural noise. Structural noise results from an overlapping of fine irrelevant anatomical structures. A method for measuring the combined effect of structural noise and scatter noise was developed and will be presented in this paper. This method is based on the consideration that within a pair of projections created after rotation of the object with a small angle (which is within the typical uncertainty in positioning the patient) both images would show the same relevant structures whereas the projection of the fine overlapping structures will appear quite differently in the two images. To demonstrate the method two X-ray radiographs of a lung phantom were produced. The second radiograph was achieved after rotating the lung by an angle of about 3. Dyadic wavelet representations of both images were regarded. For each value of the wavelet scale parameter the corresponding pair of approximations was matched using the cross correlation matching technique. The homologous regions of approximations were extracted. The image containing only those structures that appear in both images simultaneously was then reconstructed from the wavelet coefficients corresponding to the homologous regions. The difference between one of the original images and the noise-reduced image contains the structural noise and the scatter noise.

Respiratory function after lesions in medulla oblongata

Abstract Objectives: To evaluate the correlation of lesions of the brain as visualized in cranial magnetic resonance imaging (MRI) and the ability of spontaneous respiration. Methods: In a prospective concept, cranial MRI after traumatic brain injury or spontaneous intracerebral hemorrhage was performed in 250 subjects at an early stage. All MRI findings were correlated with respiratory conditions on the day of examination. Sedation was performed only to facilitate toleration of the artificial ventilation, as and when necessary. Spontaneous respiration could hence be registered clinically. Results: Thirteen subjects (5.2%) had no spontaneous respiration. In these cases, a bilateral lesion of the distal medulla oblongata could be displayed. In four of these cases, no additional injuries of the brainstem were detected. These subjects awoke 2 days after the impact with tetraparesis and apnea. Combined lesions of the medulla oblongata and other brainstem regions were found in nine subjects. All these patients died without awakening. In the absence of a bilateral lesion of the caudal medulla oblongata, spontaneous respiration was always possible. A unilateral lesion of the caudal medulla oblongata was visualized in one patient who had the ability of spontaneous respiration. Conclusions: This work confirms the presence of autonomous respiratory centers within the caudal medulla oblongata that allows sufficient adequate respiration in coma. Respiration ceases in the presence of a bilateral lesion of this area.

Bipolar Radiofrequency Ablation of Spinal Neoplasms: Average Power to be the Most Predictive Value in Respect of Induced Extent of Ablation Volume

Objective: To obtain an equation for the prediction of radiofrequency induced ablation volumes. Summary of Background Data: Radiofrequency ablation of tumor masses is an established procedure and is increasingly used as pain therapy of unresectable spine tumors. The bipolar radiofrequency ablation potentially minimizes the risk of injury to adjacent structures. Predictability of the extent of the induced ablation zosne has been hown on an ex-vivo model. There has been no investigation examining the parameters of radiofrequency ablation in an in-vivo model. Methods: 38 lesions of the spine in 36 patients were treated using bipolar radiofrequency ablation. Extent of ablated tissue, amount of administered energy, average power and total duration of ablation were recorded. Results: Induced Volume of Necrosis (VN) correlates with Average Power (AP) following the equation VN=-3.579+0.998*AP. Conclusion: Average power can be used as the most predictive parameter for calculation of the induced necrosis volume in an in-vivo model too.