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Biomedical subjects

F Prigent

Publications and source records attributed to F Prigent.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Hereditary epidermolysis bullosa and laryngeal involvement].

Two cases of epidermolysis bullosa (EB) with laryngeal involvement are reported in 2 Algerian girls, aged 6 and 7 years. The first one with a junctional EB, received local treatment with good results. For the second, with an EB dystrophica, tracheostomy was necessary and remained so. Laryngeal involvement is rare in EB. It and remained so can be serious and life-threatening. Eight cases where previously reported. Their clinical and therapeutical particularities are discussed.

Child↗
PubMed1989

Quantitative single photon emission computed thallium-201 tomography for detection and localization of coronary artery disease: optimization and prospective validation of a new technique.

One hundred eight-three men underwent stress-redistribution thallium-201 myocardial perfusion tomography. After evaluation of various preprocessing filters in a phantom study, the Butterworth filter with a frequency cutoff of 0.2 cycles/pixel, order 5 (which provided optimal filter power) was used in the back projection algorithm of the patient studies. All short-axis and apical portions of vertical long-axis images were quantified by dividing each myocardial slice into 60 equal sectors and displaying the maximal count per sector as a linear profile. In a pilot group consisting of 20 normal men (less than 5% likelihood of coronary artery disease) and 25 men with coronary artery disease (greater than or equal to 50% coronary stenosis by angiography), profiles representing the lowest observed value below the mean normal profiles provided the best threshold for defining normal limits. Abnormal portions of the patient profiles were plotted on a two-dimensional polar map. The polar map was divided into 102 sectors, and sectors with a probability of greater than or equal to 80% for disease of each one of the three major coronary arteries were clustered to represent specific coronary artery territories. Receiver operating characteristic curve analysis for defect size showed that the optimal threshold for defining a definite perfusion defect was 12% for the left anterior descending and left circumflex and 8% for the right coronary artery territories. These criteria were prospectively applied to an additional 92 patients with angiographic coronary artery disease, 18 patients with normal coronary arteriograms and 28 patients with less than 5% likelihood of coronary disease. Sensitivity, specificity (in patients with normal coronary arteriograms) and normalcy rate (in patients with less than 5% likelihood of coronary artery disease) for overall detection of coronary disease were 96%, 56% and 86%, respectively. Sensitivity and specificity for identification of individual diseased vessels were, respectively, 78% and 85% for the left anterior descending, 79% and 60% for the left circumflex and 81% and 71% for the right coronary artery. These results were not significantly different from those of the pilot group. An optimized quantitative method for interpretation of stress thallium-201 myocardial perfusion tomography has been developed. Prospective application of this method indicates that the technique is accurate for the overall detection of coronary artery disease and identification of disease in individual arteries.

Coronary Circulation↗
PubMed1989

"Upward creep" of the heart: a frequent source of false-positive reversible defects during thallium-201 stress-redistribution SPECT.

A new cause of artifactual 201Tl defects on single photon emission computed tomography (SPECT) termed "upward creep" of the heart is described. In 102 consecutive patients undergoing 201Tl SPECT, 30 (29%) demonstrated upward creep defined by an upward movement of the heart of greater than or equal to 2 pixels during acquisition. In 45 consecutive patients with a less than 5% likelihood of coronary artery disease, 17 (38%) had upward creep. Of these nine had reversible 201Tl defects localized to the inferior and basal inferoseptal walls, while none of the 28 without upward creep had defects. The 17 low likelihood patients with upward creep had longer exercise duration and higher peak heart rate than those without upward creep. In five additional low likelihood patients with upward creep in whom imaging was immediately repeated, the upward creep pattern disappeared on the repeated images. After we changed our test protocol to begin imaging 15 min postexercise, only five (14%) of 36 low likelihood patients tested demonstrated upward creep. Upward creep is probably related to a transient increase in mean total lung volume early following exhaustive exercise, resulting in a mean lower position of the diaphragm (and thus the heart) at the beginning of imaging. The frequency of this source of false-positive 201Tl studies can be reduced by delaying SPECT acquisition until 15 min postexercise.

Adult↗
PubMed1988

Patient motion in thallium-201 myocardial SPECT imaging. An easily identified frequent source of artifactual defect.

Because Tl-201 SPECT requires that patients remain in an awkward position for a prolonged time, patient motion is a potentially serious source of artifactual defects on tomographic reconstructions. Thus, a simple method was developed for detection and correction of motion from SPECT images using a Co-57 point source placed on the lower anterior chest, an area remaining in the camera's field of view throughout imaging. In the absence of motion, this point source inscribes a straight line on planar summation of the 32 projections over 180 degrees. Movement is detected by deviation from this line. The number of pixels of motion is used to shift images so that the resultant images of the point source are linear. The method of motion detection and correction was tested in 48 consecutive patients undergoing Tl-201 SPECT. The corrected and uncorrected images were reconstructed and long and short axis tomographic cuts were quantitatively analyzed using circumferential profiles of maximal counts with comparison to the lower limits of normal. Motion was detected in eight of 48 patients (17%). The amount of motion was 2 pixels in three patients and 1 pixel in five patients. Quantitative defect extent was less after correction in seven of eight patients, with a mean decrease of 71% in patients with 2 pixel motion and 44% in patients with 1 pixel motion. This corresponded with a definite reduction in the size of the tomographic defect by visual analysis, and closer resemblance to quantitatively analyzed planar images performed either before or after tomography in the same patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Controlled study of plasma exchange in pemphigus.

To determine the potential steroid sparing effect of plasma exchange in pemphigus we enrolled 40 patients in a multicenter randomized study. Eighteen patients were treated by prednisolone alone, 22 by prednisolone plus ten large-volume plasma exchanges over four weeks. All patients received oral prednisolone in the same initial dosage (0.5 mg/kg/d), which was increased weekly if needed. The number of cases controlled at each therapeutic step did not differ between the two groups. In eight cases, four in each group, the disease was not controlled by the highest therapeutic step of the protocol, with four deaths from sepsis in the plasma exchange group. The controlled cases needed similar cumulative prednisolone doses (5237 +/- 5512 mg in the plasma exchange group vs 4246 +/- 1601 mg in the control group). The evolution of serum pemphigus antibody was not different in the two groups. These findings suggest that plasma exchange in association with low steroid doses alone are not effective in the treatment of pemphigus and may even promote sepsis.

Adult↗
PubMed1987

Comparative methods for quantifying myocardial infarct size by thallium-201 SPECT.

Maximum-count circumferential profile analysis of 201TI single photon emission computed tomograms (SPECT) was employed to quantify infarct size (15) in ten dogs with acute closed chest coronary occlusion (seven left anterior descending coronary artery and three left circumflex coronary artery) who underwent rest-redistribution 201TI SPECT. The extent of hypoperfused myocardium was calculated as a percentage of slice mass on rest-redistribution 201TI SPECT. Pathologic IS was determined by triphenyl tetrazolium chloride (TTC) staining. On each tomogram, SPECT IS was defined as the % of the maximum-count circumferential profile points falling below normal. To calculate total LV infarct size, slice ISs were added to one another after each was multiplied by a coefficient K that reflected the contribution of that slice to the total left ventricular mass. K was derived from an observed relationship in normal dogs between slice fractional distance from the apex and either its actual weight, its geometric SPECT area, or its count-based SPECT area, the assessment of which was independent of edge detection. Using any of these algorithms, there was a high linear correlation between the tomographic and TTC IS. A similar algorithm was also developed from tomograms of eight normal patients. These data offer promise for the clinical noninvasive assessment of the extent of hypoperfused myocardium.

Algorithms↗