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Biomedical subjects

I Idy-Peretti

Publications and source records attributed to I Idy-Peretti.

29 records · Page 2Linked to original sources
PubMed1992

MR imaging of hemophilic arthropathy of the knee: classification and evolution of the subchondral cysts.

Magnetic resonance imaging was performed to assess the subchondral bone of the knee in 64 patients with severe hemophilia A. Using this method, subchondral cysts could be detected and evaluated. We separated the cysts into four classes (LL, LH, HH, C) depending on their signal intensities on T1- and T2-weighted images. Follow-up studies, performed on 25 patients during a period of 10-30 mo after the initial examination, suggest that these four classes of cysts correspond to four successive stages. Morphological changes within a class of cysts were also observed. Although histological confirmation was not possible, this study demonstrated that magnetic resonance imaging allows a better understanding of the pathophysiology and the natural evolution of the subchondral cysts in hemophilic arthropathy.

Adolescent↗
PubMed1992

[High-resolution MRI of the carpal tunnel. Anatomical correlations].

This anatomical study of the carpal tunnel compares magnetic resonance imaging sections and adult and fetal anatomical sections. The MRI studies were carried out in 12 normal controls. The use of an experimental high resolution module allows achieving as high a degree of spatial resolution as 0.13 mm2. The comparison of MR images with anatomical sections allows a very accurate analysis of the contents of the carpal tunnel, especially of the median nerve, of the flexor tendons and of the flexor retinaculum.

Adult↗
PubMed1991

In vivo proton relaxation times analysis of the skin layers by magnetic resonance imaging.

If in vivo magnetic resonance imaging is nowadays a powerful non-invasive method in medical diagnosis, its application in order to study the skin in vivo is not yet in common use because skin imaging requires a high resolution, at least in the direction perpendicular to the skin surface. We have therefore designed a specific imaging module, which, connected to a standard whole-body imager at 1.5 Tesla, allows us to obtain in vivo magnetic resonance images of skin on most parts of the body. With a depth resolution of about 70 microns, we are able to differentiate the skin layers: epidermis, dermis, subcutaneous fat, and even a thickened stratum corneum on palm as well as on heel. This paper reports the T1 and T2 water proton relaxation times of the different skin layers, in vivo, which are magnetic resonance parameters extracted from the images. Results show that skin layers are characterized by shorter T2 relaxation times than other biologic soft tissues. On the contrary, the measured T1 values are in the same range as in other tissues. These short T2 values may be assigned to the fibrous protein content of the skin and particularly of the dermis. This study on normal skin is the precursor of further works such as the influence of aging. As regards skin pathologies, it will be a powerful tool to follow the evolution of skin diseases under treatment.

Adult↗
PubMed1991

[Mass and geometry of the left ventricle. Contribution of ultrafast computed x-ray tomography and magnetic resonance imaging].

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.

Cardiac Volume↗
PubMed1991

[Contribution of MRI to the preoperative evaluation of rotator cuff tears].

The authors report a series of 38 patients who had been examined by MRI and then operated for a rotator cuff syndrome. The correlation between the description of the cuff lesions after MRI and the surgical observations were excellent for 37 patients. In one case MRI showed a false image of tear of the supra spinatus m. on its anterior edge. This was due to a bad knowledge of the anatomy of the muscle and tendon and to a poor orientation of the frontal cut plane. This study was completed with MRI and anatomic study of 12 non embalmed cadaveric shoulders. The results showed that MRI was very sensitive (0.93) and specific (0.94) for the diagnosis of rotator cuff tears. MRI allowed also to show partial tears of the tendons of the rotator cuff. The authors propose a MRI classification of cuff lesions which permits to establish a good surgical planning.

Female↗
PubMed1990

Spectroscopic MRI: a tool for the evaluation of systemic lipid storage disease.

Spectroscopic MR imaging allows to measure the lipid content of a region inside the human body. This technique has been applied to the case of a woman with a severe multisystemic triglyceride storage disease. Lipid contents of liver, pancreas, kidneys, left ventricle, skeletal muscles (calves, thighs, arms) were measured by using the Dixon spectroscopic imaging sequence. In some heterogeneous muscles, localized proton spectra were recorded. Results agreed with clinical findings (muscle weakness, normal renal and cardiac function, diabetes). These techniques could help to quantify the severity of the disease and to follow up its evolution under therapy.

Adult↗
PubMed1990

In vivo high-resolution MR imaging of the skin in a whole-body system at 1.5 T.

High-resolution magnetic resonance (MR) images of the skin were acquired with a whole-body MR system at 1.5 T by adding a specific imaging module: A saddle-shaped surface gradient coil was connected in place of one of the gradient coils of the system, and a surface radio-frequency coil with a 1.5-cm radius was placed at the center of the gradient coil. The images, acquired in 3 minutes 25 seconds, represent a field of view of 18 x 50 mm2, which corresponds to a pixel size of 70 x 390 micro2; the section thickness was 1.2 mm. With this spatial resolution, the different layers of the skin are clearly delineated: Epidermis appears as a high-signal-intensity layer, while dermis appears hypointense due to its very short T2. Pilosebaceous units appear as inclusions of epidermis inside dermis. The high quality of the images obtained enables in vivo MR characterization of skin.

Humans↗
PubMedDate not supplied

In vivo comparison of two through-plane MR velocity mapping methods: fast Fourier encoding and phase mapping.

Magnetic resonance imaging maps of velocity were acquired with a 1.5-T system in 10 subjects in a plane perpendicular to the main pulmonary artery. Velocity images were successively acquired with a method developed from Fourier-encoding velocity imaging (FEVI) principles with eight gradient steps and one excitation, and with two-point phase-subtraction mapping. Reconstruction in FEVI was implemented by zero-filling interpolation around the eight gradient steps and then around the four central steps. The methods were compared by using estimates of noise in velocity measurements based on the difference between the experimental map and a smooth fitted map. For the same acquisition time, FEVI with four encoding steps was more precise in velocity measurements than phase mapping. Precision was further increased by the use of eight encoding steps, but acquisition time was doubled.

Adult↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

MR tissue characterization of a right atrial mass: diagnosis of a lipoma.

A case of histologically confirmed benign lipoma of the right atrium is presented. Magnetic resonance imaging was successfully used to visualize and characterize the tumor previously detected by echocardiography. T1-weighted MR was superior to echocardiography and was in surgical agreement with examination in identifying the relationship of the lipoma to the right atrial wall, the coronary sinus, and the interatrial septum. Comparison of measurements of the tumor's signal intensities on T1- and T2-weighted images and T2 relaxation time with those of surrounding myocardium and mediastinal fat allowed a preoperative diagnosis of lipoma. Magnetic resonance may obviate surgical intervention in selected asymptomatic cases where the diagnosis of benign lipoma appears likely.

Aged↗