CSF flow measurement in syringomyelia.

BACKGROUND AND PURPOSE: CSF circulation has been reported to represent a major factor in the pathophysiology of syringomyelia. Our purpose was to determine the CSF flow patterns in spinal cord cysts and in the subararachnoid space in patients with syringomyelia associated with Chiari I malformation and to evaluate the modifications of the flow resulting from surgery. METHODS: Eighteen patients with syringomyelia were examined with a 3D Fourier encoding velocity imaging technique. A prospectively gated 2D axial sequence with velocity encoding in the craniocaudal direction in the cervical region was set at a velocity of +/- 10 cm/s. Velocity measurements were performed in the larger portion of the cysts and, at the same cervical level, in the pericystic subarachnoid spaces. All patients underwent a surgical procedure involving dural opening followed by duroplasty. Pre- and postoperative velocity measurements of all patients were taken, with a mean follow-up of 10.2 months. We compared the velocity measurements with the morphology of the cysts and with the clinical data. Spinal subarachnoid spaces of 19 healthy subjects were also studied using the same technique. RESULTS: A pulsatile flow was observed in syrinx cavities and in the pericystic subarachnoid spaces (PCSS). Preoperative maximum systolic cyst velocities were higher than were diastolic velocities. A systolic velocity peak was well defined in all cases, first in the cyst and then in the PCSS. Higher systolic and diastolic cyst velocities are observed in large cysts and in patients with a poor clinical status. After surgery, a decrease in cyst volume (evaluated on the basis of the extension of the cyst and the compression of the PCSS) was observed in 13 patients. In the postoperative course, we noticed a decrease of systolic and diastolic cyst velocities and a parallel increase of systolic PCSS velocities. Diastolic cyst velocities correlated with the preoperative clinical status of the patients and, after surgery, in patients with a satisfactory foraminal enlargement evaluated on the basis of the visibility of the cisterna magna. CONCLUSION: CSF flow measurement constitutes a direct evaluation for the follow-up of patients with syringomyelic cysts. Diastolic and systolic cyst velocities can assist in the evaluation of the efficacy of surgery.

[Morphological and functional study of pulmonary arteries by MRI]. / Etude morphologique et fonctionnelle des artères pulmonaires par l'IRM.

This article presents an exhaustive review of MRI in the assessment of the pulmonary arteries (sequences, normal results, clinical signs of the main diseases). Its current preferential indications are: the study of the main pulmonary artery trunks (primary tumours, proximal embolism, caliber abnormalities, anatomical relations with central tumours), the assessment and post-treatment follow-up of pulmonary arterial malformations. Angio-MRI is currently being developed and, in the near future, should allow the reliable diagnosis of pulmonary embolism and will therefore be indicated alongside spiral computed tomography. MRI also allows functional assessment of the right circulation (measurements of circulatory velocity and flow rates). It should rapidly become an examination of choice in the haemodynamic follow-up of patient with pulmonary hypertension and transplant recipients and as an evaluation tool for new drugs.

[Computerized evaluation of tumor volume with MRI. Applications to the surveillance of acoustic neurinoma]. / Evaluation informatique du volume tumoral en IRM. Applications à la surveillance des neurinomes de l'acoustique.

Routine volume measurement techniques most often produce a rough approximate with poor accuracy for smaller structures. The results are generally improved by increasing the examination time, so that the technique then becomes unusable in daily practice. We propose a semiautomated volume calculation method with MRI, and its application to the surveillance of non-operated acoustic neuromas. This calculation technique, based on a threshold-setting method, allows accurately delineating the contours of the structures to be measured on each section and quickly calculating the total volume. After testing its reliability on control volumes, this techniques has been used to assess the evolutive nature of 16 acoustic neuromas with mild symptoms in 15 patients rejected for surgery. The radiological examinations were 428 days apart in average. On the basis of the obtained results, a theoretic tumor doubling time was calculated, thus allowing comparison between all patients. All controlled neuromas had a theoretic doubling time ranging from 427 to 4,884 days, corresponding to little- or non-evolutive lesions, which may be explained by the series selection bias excluding evolutive tumors referred to surgery. Owing to its rapidity and easy use, this semiautomated volume calculation technique for MRI seems to be very interesting as it allows reliably quantifying a volume variation that is usually estimated approximately.

[Mass and geometry of the left ventricle. Contribution of ultrafast computed x-ray tomography and magnetic resonance imaging]. / Masse et géométrie ventriculaire gauche. Apports de la tomodensitométrie ultrarapide et de l'imagerie par résonance magnétique.

Ultrafast computed tomography and magnetic resonance imaging are two new methods of cardiac imaging. Measurements of left ventricular volume (end-diastolic, end-systolic volume, stroke volume) and mass have been validated with both methods. The calculations are independent of the geometric shape of the ventricle. Although regional analysis is difficult because of the complex movement of the left ventricle in the tomographic cuts, these methods present a number of advantages: excellent temporospatial tomographic resolution, approximately the same in all dimensions, appreciation of endocardial movement from an epicardial centre, the potential to record their transform spatial data in 3 dimensions from initial planar acquisition. However, all potential regional measurements are still being validated as they are operator-dependent and require visual identification and manual tracing of the cardiac contours or local infrastructures which affect the results of these techniques which are still relatively little used in cardiac imaging. In the context of clinical evaluation, these relatively non-invasive methods will become extremely accurate in the appreciation of parameters of left ventricular geometry and function. They will become very useful in the determination of the myocardial effects of drugs, surgery or other interventional procedures in different models of cardiac disease.

A selective histochemical method for the quantitative estimation of elastic fibers by computerized morphometric analysis. Effect of colchicin treatment.

A morphometric technique is reported that uses a new selective staining of the elastic system fibers in skin biopsy specimens to facilitate the quantitative evaluation of the volume fraction occupied by these elastic fibers in the tissue. The study of elastic fibers in the dermis of 30 patients, before and after six months of treatment with Colchicin, was carried out with a Quantimet 720 system. Preelastic (oxytalan and elaunin) fibers and mature elastic fibers were quantitated separately. Compared to the average volume fraction (surface occupied by the elastic fibers) before treatment with Colchicin (1.449 +/- 0.64%), the mean values after treatment were significantly increased (2.076 +/- 0.61%). The same results were found for the preelastic fibers: 0.807 +/- 0.51% before treatment and 1.025 +/- 0.54% after treatment. These results demonstrate the advantages of our monochromatic staining method for automatic quantitation of elastic fibers as well as the possibilities of the quantitative study of the elastic fibers in human dermis. This methodology should be applicable to other inherited or acquired diseases affecting skin elastic fibers as well as to other tissues containing elastic fibers.