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S Delorme

Publications and source records attributed to S Delorme.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Imaging the smallest tumor vessels using color Doppler ultrasound in an experiment].

PURPOSE: We present an experimental, statistical approach to estimate the size required for small vessels to become detectable with color Doppler sonography. MATERIALS AND METHODS: A murine experimental tumor was examined with color Doppler sonography after injection of 1.5 ml of the contrast medium Levovist. Histologically, we measured vessel diameters inside the tumor as well as other, clearly identifiable locations. RESULTS: With color Doppler at a transmit frequency of 7 MHz, vessels were only detected in the tumor's environment, but not inside. From the 95% quantiles of the vessel diameter distribution found histologically, we estimate that vessels 80-140 microns in diameter or above may be detectable with color Doppler sonography, while vessels 40 microns in diameter or smaller are indetectable. CONCLUSIONS: Although a direct sonographic--histologic correlation is impossible for small vessels, a systematic assessment of the size distribution in clearly identifiable regions permits to estimate the sensitivity of color Doppler to detect blood flow in small vessels. According to our results, capillary blood flow is indetectable, and precapillary vessels may be detected only under optimal conditions.

Animals↗
PubMed2001

[Ultrasound mammography and magnetic resonance mammography as adjunctive methods in mammography screening].

Ultrasonography and magnetic resonance (MR) tomography are helpful tools to evaluate unclear lesions found at screening mammography. Ultrasound is particularly useful to prove the presence of a cyst or to further examine unclear, asymmetrical densities. With MR mammography, carcinomas can be found even when x-ray mammography or ultrasonography are limited due to diffuse, benign, proliferative changes. Ultrasound guidance has greatly facilitated core needle biopsy for suspicious lesions. Additionally, approved devices for MR-guided biopsy are commercially available. As a primary screening tool, ultrasound or MR mammography may be used only in women who are positive for BRCA-1 or BRCA-2 mutations or who are otherwise at high risk for breast cancer.

Adult↗
PubMed2001

Preoperative and early postoperative three-dimensional changes of the rib cage after posterior instrumentation in adolescent idiopathic scoliosis.

Rib cage deformity is an important component of scoliosis, but few authors have reported the three-dimensional (3-D) effect of surgical procedures with posterior instrumentation systems on the shape of the rib cage. The objective of this prospective clinical study was to measure the short-term 3-D changes in the shape of the rib cage at the apex of the curve after corrective surgery of adolescent idiopathic scoliosis by a posterior approach using a multi rod, hook and screw system. The 3-D shape of the spine and rib cage was modelled pre- and postoperatively using a 3-D reconstruction technique based on multi-planar radiography in a group of 29 adolescents with idiopathic scoliosis. Geometrical indices describing the scoliotic deformity of the rib cage were computed from these models and were compared pre- and postoperatively using Student's t-tests. The frontal spinal curve correction averaged 53% in the frontal plane, while no significant change was noted in the sagittal plane. Significant changes were noted in the shape of the rib cage: rib hump at the apex and at the adjacent lower level were improved (36% and 38%), and small but significant differences were detected in rib frontal orientation in the concavity of the curves at the apex and adjacent lower rib levels. Multi rod, hook and screw instrumentation systems, such as Cotrel-Dubousset instrumentation, are effective in producing significant improvements in the 3-D shape of the rib cage, but these changes are less important than those observed at the spine level.

Adolescent↗
PubMed2001

Fibroadenomas: computer-assisted quantitative evaluation of contrast-enhanced power Doppler features and correlation with histopathology.

We aimed to evaluate whether the histopathologic variability of fibroadenomas accounts for their varied appearance in contrast enhanced power Doppler (PD). Forty patients with fibroadenomas (aged 19 to 61 years) underwent power Doppler ultrasound (US) prior to and following IV bolus injection of a microbubble contrast agent. A 3-min computer-assisted assessment of the color pixel density (CPD) was used for objective evaluation of the increase in color Doppler signals. Enhancement characteristics were correlated to histopathologic features of microvessel density and epithelial hyperplasia, patient's age, tumor size, use of exogenous hormones and menopausal status. Epithelial hyperplasia was diagnosed in 19 patients. Compared to baseline values, patients with epithelial hyperplasia showed a significant increase in mean CPD following contrast media administration (p < 0.01). There was a significant correlation to patient's age (p < 0.0001) and tumor size (p < 0.0001), but not to the use of exogenous hormones and menopausal status. Microvessel counts did not show a significant correlation to CPD at baseline (p = 0.07) or with CPD on contrast enhanced PD (p = 0.13), or with patient age (p = 0.43) or tumor size (p = 0.34). Intratumoral epithelial hyperplasia, primarily occurring in young patients, may contribute to the differential diagnostic overlap in some fibroadenomas and thus limit the ability of PD to distinguish between benign and malignant masses on the basis of enhancement characteristics.

Adult↗
PubMed2001

Changes of tumor vascularity during gene therapy monitored with color Doppler US.

Using contrast-enhanced color Doppler (CD) sonography, we assessed alterations of tumor blood flow induced in 25 murine Morris hepatomas transfected with a gancyclovir- (GCV-)sensitizing Herpes simplex virus thymidine kinase (HSVtk) suicide gene in combination with systemic GCV treatment and compared findings with a control tumor. CD measurements were quantified by the color pixel density (CPD) and the mean encoded flow velocity (mean color value, MCV), using computer-assisted image analysis, and compared with histologic arteriole counts. During 5 days, the tumor volume remained constant. In HSVtk-expressing tumors, the median CPD dropped from 16% at baseline to 5% on day 5 (p = 0.001), remaining constant in controls. The MCV decreased from 1.9 cm/s to 1.6 cm/s in the HSVtk-expressing tumors (p = 0.001) and rose from 1.8 cm/s to 2.0 cm/s in the controls (p = 0.002). In an accompanying histologic arteriole assay, we found no alterations attributable to treatment.

Animals↗
PubMed2001

Acyl-homoserine lactone production is more common among plant-associated Pseudomonas spp. than among soilborne Pseudomonas spp.

A total of 137 soilborne and plant-associated bacterial strains belonging to different Pseudomonas species were tested for their ability to synthesize N-acyl-homoserine lactones (NAHL). Fifty-four strains synthesized NAHL. Interestingly, NAHL production appears to be more common among plant-associated than among soilborne Pseudomonas spp. Indeed, 40% of the analyzed Pseudomonas syringae strains produced NAHL which were identified most often as the short-chain NAHL, N-hexanoyl-L-homoserine lactone, N-(3-oxo-hexanoyl)-homoserine lactone, and N-(3-oxo-octanoyl)-L-homoserine lactone (no absolute correlation between genomospecies of P. syringae and their ability to produce NAHL could be found). Six strains of fluorescent pseudomonads, belonging to the species P. chlororaphis, P. fluorescens, and P. putida, isolated from the plant rhizosphere produced different types of NAHL. In contrast, none of the strains isolated from soil samples were shown to produce NAHL. The gene encoding the NAHL synthase in P. syringae pv. maculicola was isolated by complementation of an NAHL-deficient Chromobacterium mutant. Sequence analysis revealed the existence of a luxI homologue that we named psmI. This gene is sufficient to confer NAHL synthesis upon its bacterial host and has strong homology to psyI and ahlI, two genes involved in NAHL production in P. syringae pv. tabaci and P. syringae pv. syringae, respectively. We identified another open reading frame that we termed psmR, transcribed convergently in relation to psmI and partly overlapping psmI; this gene encodes a putative LuxR regulatory protein. This gene organization, with luxI and luxR homologues facing each other and overlapping, has been found so far only in the enteric bacteria Erwinia and Pantoea and in the related species P. syringae pv. tabaci.

4-Butyrolactone↗
PubMed2000

Fitness in soil and rhizosphere of Pseudomonas fluorescens C7R12 compared with a C7R12 mutant affected in pyoverdine synthesis and uptake.

Fluorescent pseudomonads have evolved an efficient strategy of iron uptake based on the synthesis of the siderophore pyoverdine and its relevant outer membrane receptor. The possible implication of pyoverdine synthesis and uptake on the ecological competence of a model strain (Pseudomonas fluorescens C7R12) in soil habitats was evaluated using a pyoverdine minus mutant (PL1) obtained by random insertion of the transposon Tn5. The Tn5 flanking DNA was amplified by inverse PCR and sequenced. The nucleotide sequence was found to show a high level of identity with pvsB, a pyoverdine synthetase. As expected, the mutant PL1 was significantly more susceptible to iron starvation than the wild-type strain despite its ability to produce another unknown siderophore. As with the wild-type strain, the mutant PL1 was able to incorporate the wild-type pyoverdine and five pyoverdines of foreign origin, but at a significantly lower rate despite the similarity of the outer membrane protein patterns of the two strains. The survival kinetics of the wild-type and of the pyoverdine minus mutant, in bulk and rhizosphere soil, were compared under gnotobiotic and non-gnotobiotic conditions. In gnotobiotic model systems, both strains, when inoculated separately, showed a similar survival in soil and rhizosphere, suggesting that iron was not a limiting factor. In contrast, when inoculated together, the bacterial competition was favorable to the pyoverdine producer C7R12. The efficient fitness of PL1 in the presence of the indigenous microflora, even when coinoculated with C7R12, is assumed to be related to its ability to uptake heterologous pyoverdines. Altogether, these results suggest that pyoverdine-mediated iron uptake is involved in the ecological competence of the strain P. fluorescens C7R12.

Journal Article↗
PubMed2000

A three-dimensional radiographic comparison of Cotrel-Dubousset and Colorado instrumentations for the correction of idiopathic scoliosis.

STUDY DESIGN: A prospective clinical study comparing two instrumentation systems for the correction of idiopathic scoliosis. OBJECTIVES: To measure the short-term three-dimensional changes in the shape of the spine after corrective surgery and compare the Cotrel-Dubousset instrumentation to the more recent Colorado instrumentation to determine whether one system provides better three-dimensional correction. SUMMARY OF BACKGROUND DATA: Adequate three-dimensional correction of scoliotic deformities has been reported with the Cortrel-Dubousset instrumentation system. During the past decade, a new generation of more versatile and user-friendly spinal implants has appeared, but there are no reports available to indicate whether similar or better correction can be obtained with these newer systems. METHODS: The three-dimensional geometry of the thoracic and lumbar spine was documented in the standing position using a three-dimensional reconstruction technique based on multiplanar radiography in 67 adolescents with idiopathic scoliosis undergoing correction by a posterior approach. Changes in spinal shape were measured 3 days before and 1 month after the surgery in 31 patients with Cotrel-Dubousset instrumentation and 36 patients with Colorado instrumentation. RESULTS: In both groups, adequate three-dimensional correction of the scoliotic deformities was documented for thoracic and lumbar curves, with significant changes in the frontal plane, in the plane of maximum curvature, and in its orientation. When comparing both groups, better correction was obtained in the frontal plane with the Colorado instrumentation (65% vs. 48% with Cotrel-Dubousset), a finding that may be explained by the significantly greater proportion of pedicle screws used in this group. CONCLUSION: Both instrumentation techniques achieve an effective and comparable three-dimensional correction of the scoliotic deformities.

Adolescent↗
PubMed2000

[Radiological diagnosis of the liver].

Highly specific methods are required for the diagnostic workup of focal hepatic lesions, since benign circumscribed liver changes are very common. Although cross-sectional imaging techniques have a high diagnostic accuracy, radionuclide imaging techniques such as colloid, red blood cell, or hepatobiliary scan are commonly performed when a benign lesion is assumed since these permit a definite diagnosis with high specificity. The diagnosis of a primary or secondary malignant liver tumor, however, usually relies on radiological imaging techniques alone, supported by needle biopsy. Whether positron emission tomography as a primary or supplementary diagnostic tool will have a role in the routine staging of malignant tumors remains to be determined.

Focal Nodular Hyperplasia↗
PubMed2000

Contrast-enhanced power Doppler harmonic imaging--influence on visualization of renal vasculature.

To compare contrast-enhanced power Doppler (PD) harmonic imaging (CHI) with contrast-enhanced power Doppler fundamental imaging (CPD) in the depiction of renal cortical vessels, 20 healthy volunteers were subjected to PD imaging and HI assessment of the kidney after bolus injection of Levovist(R) (SH U 508A). System settings were standardized and the pulse-repetition frequencies (PRF) systematically toggled from 750 to 500 and 250. Videotapes were independently reviewed by three readers with regard to the presence of artefacts, the degree of Doppler signal enhancement, demarcation of vessels and the extent of visualization. The assessments were graded separately for each PRF in accordance with a multistage scoring system. In comparison to contrast-enhanced PD, artefacts were significantly lower with CHI for all PRF (p = 0.0001). Vessels were better visualized (p = 0.002) and less blurred (p = 0.006) with CHI than with CPD. There was no significant difference in the extent of Doppler signal increase between CPD and the contrast-enhanced harmonic mode. Combination of the contrast-enhanced harmonic method and PD allows the PRF to be lowered and, by balancing the greater susceptibility of PD to interference from clutter, increases the likelihood of detection of flow in small vessels.

Adult↗
PubMed2000

Relevance of sonographic B-mode criteria and computer-aided ultrasonic tissue characterization in differential/diagnosis of solid breast masses.

We aimed to evaluate the differential diagnostic value of a method of computer-assisted texture analysis in comparison to established ultrasonographic B-mode characteristics in the examination of solid breast masses. At two centers, 77 patients presenting with a solid mass on B-mode scan were studied at 7.5 MHz. Description of B-mode appearance included assessment of tumor shape, borders, presence of an echogenic rim, tissue architecture, internal echo structure, absorption and elasticity. For statistical pattern recognition, the following parameters were used: form factor, mean grey level, signal-to-noise ratio, mean gradient and correlation from the co-occurrence matrix. At center 1, the most decisive parameter for differential diagnosis was distortion of tissue architecture (sensitivity, SN, 83%; specificity, SP, 92%) and, at center 2, relation to the adjacent tissue (SN 93%, SP 92%). Among texture parameters, best discrimination was achieved for correlation from the co-occurrence matrix at center 1 (SN 58%, SP 73%) and for form factor at center 2 (SN 93%, SP 77%). Among sonographic criteria, the highest contribution to the diagnosis was found for an unsharp border (odds ratio, OR, 12.2), architectural distortion (OR, 8.6), fixation to skin or chest wall (OR, 9.0) and fixation to adjacent breast parenchyma (OR, 8.8), according to texture analysis for parameters form factor (OR 4.0) and correlation from the co-occurrence matrix (OR 4.7). Ultrasonographic texture analysis can be helpful as an additional parameter in differential diagnosis of breast tumors, but did not reach differential diagnostic accuracy of sonomorphologic features.

Adult↗
PubMed2000

Prognostic assessment of sonography and tumor volumetry in advanced cancer of the head and neck by use of doppler ultrasonography.

OBJECTIVE: The objective of this trial was to examine the degree of tumor vascularity in lymph node metastases as depicted by computer-assisted color Doppler sonography and the tumor volumes associated with prognosis in carcinomas of the oropharynx and hypopharynx after primary radiochemotherapy. PATIENTS AND METHODS: In a prospective trial, 25 patients with advanced squamous cell carcinomas of the oropharynx and hypopharynx (stage IV UICC 1997) were treated with radiochemotherapy. The color Doppler findings were quantified with a computer-assisted protocol that quantitatively describes color Doppler images by the relative color pixel density (CPD). As important prognostic cofactor, total tumor volume (TTV) was calculated from CT sections and related to the degree of vascularity. RESULTS: Low CPD in neck metastases showed a correlation with better overall survival. A high-CPD group and a high-TTV group (median survival 10.1 months) were determined and were compared with all other CPD/TTV combinations (median survival 28.4 months); the difference in survival was significant (P = 0.002). CONCLUSION: The results indicate that high tumor vascularity in combination with high TTV indicates a particularly bad prognosis in patients treated with primary radiochemotherapy for head and neck cancer.

Adult↗
PubMed2000

Reconstruction of laser-scanned 3D torso topography and stereoradiographical spine and rib-cage geometry in scoliosis.

Assessments of scoliosis are routinely done by means of clinical examination and full spinal x-rays. Multiple exposure to ionization radiation, however, can be hazardous to the child and is costly. Here, we explain the use of a noninvasive imaging technique, based on laser optical scanning, for quantifying the three-dimensional (3D) trunk surface topography that can be used to estimate parameters of 3D deformity of the spine. The laser optical scanning system consisted of four BIRIS laser cameras mounted on a ring moving along a vertical axis, producing a topographical mapping of the entire torso. In conjunction with the laser scans, an accurate 3D reconstruction of the spine and rib cage were developed from the digitized x-ray images. Results from 14 scoliotic patients are reported. The digitized surfaces provided the foundation data to start studying concordance of trunk surface asymmetry and spinal shape in idiopathic scoliosis.

Calibration↗
PubMed2000

Pre-, intra-, and postoperative three-dimensional evaluation of adolescent idiopathic scoliosis.

The authors measured and compared the pre-, intra-, and postoperative three-dimensional shape of the spine during corrective surgery to quantify the specific contribution of positioning, anesthesia, surgical exposure, surgical instrumentation, and postural adaptation of the thoracic and lumbar spine. In 58 adolescent girls with idiopathic scoliosis undergoing corrective surgery by a posterior approach, the three-dimensional geometry of the thoracic and lumbar spine was documented in the standing position before and after surgery using a three-dimensional reconstruction technique based on multiplanar radiography, and the intraoperative three-dimensional geometry was measured using a three-dimensional magnetic digitizer before and after installation of the first rod. Prone positioning, anesthesia, and surgical exposure are responsible for a considerable decrease in all curves in the frontal and sagittal plane. Instrumentation with the first rod produces additional substantial and favorable three-dimensional changes with partial restoration of the normal sagittal curves and sagittal shift of the plane of maximum deformity. Although no loss of correction was observed in the frontal plane when patients resumed their standing position, a "spring-back" effect on the spine was noted in the sagittal plane and a loss of three-dimensional correction was seen in the orientation of the plane of maximum deformity. Surgeons can use the knowledge of these various changes to achieve better results by more careful attention to the preoperative positioning of patients and to curve correction in the sagittal plane when instrumentation is applied to the spine.

Adolescent↗