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Biomedical subjects

P Millet

Publications and source records attributed to P Millet.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Influence of bolus volume and dose of gadolinium chelate for first-pass myocardial perfusion MR imaging studies.

First-pass MR myocardial perfusion measurements require a well-defined left ventricular (LV) blood pool input function. We used a peripheral intravenous (i.v.) injection of a gadolinium (Gd) chelate to obtain a well-characterized LV time-intensity curve. Using a strongly T1-weighted subsecond MR sequence, we performed cardiac MR imaging after administering an IV bolus injection of one of three different doses of the Gd chelate: a standard dose (0.1 mmol/kg, group I, n = 8); a low dose with two bolus volumes (0.01 mmol/kg, 1/10e bolus volume, group II, n = 7, and 0.01 mmol/kg diluted in saline, same bolus volume as group I, group III, n = 3); and an intermediate dose (0.05 mmol/kg, group IV, n = 5). Unlike in group I (high dose), in groups II and III (low dose), the LV curve had a well-defined first peak, followed by a downslope and a recirculation peak. With the intermediate dose (group IV), a saturation effect still remained on the LV curve. The signal intensity (SI) enhancement of the myocardium was respectively 580 +/- 77% at 0.1 mmol/kg, 362 +/- 95% at 0.05 mmol/kg, and at 0.01 mmol/kg, it was 184 +/- 33% in group II and 272 +/- 8% in group III. In conclusion, with subsecond T1-weighted MR imaging and a low dose of Gd chelate (i.e., 0.01 mmol/kg), the LV input function is a well-defined first step for MR perfusion modeling.

Contrast Media↗
PubMedDate not supplied

Comparison of single-breath-hold fast spin-echo sequences with routine non-breath-hold techniques: application to MRI of renal masses.

In 24 patients presenting with 55 renal lesions (mean size, 20.8 mm), single-breath-hold (SBH) fast spin-echo (FSE) techniques allowing T1 and T2 images to be produced within 20 and 23 sec, respectively, were compared with routine non-breath-hold (NBH) spin-echo (SE) T1 and NBH-FSE T2 sequences. Contrast-to-noise ratios (CNRs) measured from SBH-FSE T1 images were an average of 97% higher than their NBH counterparts (P = .0001) and allowed an improved lesion conspicuity in 80% of the cases (P = 0.0001). For T2 imaging, SBH-FSE and NBH-FSE sequences were not statistically different with respect to lesion conspicuity (P = .55) and CNR values (P = .19). This was observed despite a 35% average decrease in CNR of SBH-FSE compared to NBH-FSE images. By reducing respiratory motion artifacts while preserving SE-like image contrast, SBH-FSE techniques have the potential to replace routine NBH sequences for an optimal diagnosis of renal masses.

Adult↗
PubMedDate not supplied

Extraction of functional volumes from medical dynamic volumetric data sets.

A method based on factor analysis is presented to process dynamic volumetric (t + 3D) data sets acquired for flow, excretion, or metabolic studies. It estimates a reduced number of underlying physiological kinetics and their associated spatial distributions, corresponding to functional volumes, using dedicated algorithms. The global (t + 3D) approach is shown to be superior to the conventional one, which repeats estimations on each (t + 2D) data set, obtained for each slice or projection of the volume.

Algorithms↗
PubMedDate not supplied

Immune response to Plasmodium falciparum liver stage antigen-1: geographical variations within Central Africa and their relationship with protection from clinical malaria.

Two populations of schoolchildren from Gabon and Cameroon were tested in 1995 for their immunological reactivity to synthetic peptides (LSA-Rep, LSA-J and LSA-CTL) from Plasmodium falciparum liver stage antigen-1 (LSA-1). The prevalence and levels of both cellular (lymphocyte proliferation, tumour necrosis factor alpha (TNF alpha), interferon gamma (IFN gamma), and interleukin-10 (IL-10)) and humoral (immunoglobulin G) responses were determined. Protection from clinical malaria, determined after a prospective 1 year study in both sites, was associated with elevated proliferative responses to LSA-Rep and LSA-CTL in the Gabonese children, as well as with higher antibody levels to both schizont extract and LSA-Rep. The prevalence of peptide-stimulated TNF-alpha secretion was higher in the Cameroonian group, but higher levels of antibodies to LSA-Rep and LSA-J were found in the Gabonese children. The immunological differences observed between children in the 2 study sites are discussed in the context of both epidemiological and individual host factors.

Animals↗
PubMedDate not supplied

Comparison after 10 years of two 100-patient cohorts operated on for eviscerations or enucleations.

PURPOSE: To compare the indications, surgical techniques, and operative outcome between two 100-patient populations operated on for evisceration or enucleation with a 10-year interval. METHODS: This retrospective study involved 100 patients operated on between 1987 and 1990 (Group 1) compared with another 100 patients operated on between 1996 and 2000 (Group 2). Group 1 included 64 males and 36 females, mean age 49 years; Group 2 included 60 males and 40 females, mean age 53. RESULTS: In Group 1, 19 eviscerations were performed, versus 55 in Group 2. In both groups, half of the indications for surgery were a painful blind eye. In Group 1, endophthalmia (23%) came second, whereas it was trauma (15%) in Group 2. Sixty-eight patients were implanted in Group 1 (silicone spheres 69%) versus 86 in Group 2 (hydroxyapatite spheres 69%). Twenty spheres (20%) were rejected in Group 1 versus 7% in Group 2. DISCUSSION AND CONCLUSIONS: The proportion of eviscerations increased in 10 years. The number of endophthalmitis-related operations decreased and trauma-related operations increased. The number of implantations increased with hydroxyapatite as the first choice material instead of silicone. This most likely contributed to reducing the number of rejections.

Adolescent↗
PubMedDate not supplied

[Behavior of a dental rotary instrument alloy after titanium nitride coating].

A titanium nitride coating has been deposited on steel and tungsten carbide dental rotary instruments. This process is carried out under partial vacuum, by reacting vapourized metal (titanium) and nitrogen in a plasma. The instruments temperature is around 500 degrees C during coating. We have determined by micro-analysis the treatment modifications upon the different bursa components. VICKERS microhardness tests have shown the coating temperature effects towards the heat treatments of employed steels.

Dental High-Speed Equipment↗