MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction.

OBJECTIVE: The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose. SUBJECTS AND METHODS: Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions. RESULTS: With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage. CONCLUSION: The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.

A novel technique for the reconstruction of infected full-thickness chest wall defects.

BACKGROUND: Chest wall resection and reconstruction can be performed with minimal mortality and excellent functional and cosmetic results using synthetic meshes, methylmethacrylate, or other substitutes. However, these techniques are less easily applicable if chest wall resections have to be performed for infections. METHODS: We report a novel technique for this purpose using a modified latissimus dorsi flap harvested in continuity with the thoracolumbar fascia. The vascularized fascia was sutured into the chest wall defect, providing a stable base for the muscular component of the flap. Three patients requiring large full-thickness resections of the anterolateral chest wall for chronic infections were treated accordingly, two presenting with chronic radionecrosis and osteomyelitis and one with chest wall invasion by pulmonary aspergillosis. RESULTS: There were no intraoperative or postoperative complications and immediate extubation was possible in all 3 patients without the need for postoperative ventilation or tracheotomy. Healing of the infected chest wall was observed in all 3 patients. Postoperative cinemagnetic resonance imaging revealed concordant movements of the replaced segments without evidence of paradoxical motion during inspiration and expiration. CONCLUSIONS: This technique is easy and safe. It allows a stable and satisfactory reconstruction after large anterolateral full-thickness chest wall resections of infected, previously irradiated tissues, using only well-vascularized autologous tissue.

A Monte Carlo-based procedure for independent monitor unit calculation in IMRT treatment plans.

Intensity-modulated radiotherapy (IMRT) treatment plan verification by comparison with measured data requires having access to the linear accelerator and is time consuming. In this paper, we propose a method for monitor unit (MU) calculation and plan comparison for step and shoot IMRT based on the Monte Carlo code EGSnrc/BEAMnrc. The beamlets of an IMRT treatment plan are individually simulated using Monte Carlo and converted into absorbed dose to water per MU. The dose of the whole treatment can be expressed through a linear matrix equation of the MU and dose per MU of every beamlet. Due to the positivity of the absorbed dose and MU values, this equation is solved for the MU values using a non-negative least-squares fit optimization algorithm (NNLS). The Monte Carlo plan is formed by multiplying the Monte Carlo absorbed dose to water per MU with the Monte Carlo/NNLS MU. Several treatment plan localizations calculated with a commercial treatment planning system (TPS) are compared with the proposed method for validation. The Monte Carlo/NNLS MUs are close to the ones calculated by the TPS and lead to a treatment dose distribution which is clinically equivalent to the one calculated by the TPS. This procedure can be used as an IMRT QA and further development could allow this technique to be used for other radiotherapy techniques like tomotherapy or volumetric modulated arc therapy.

Esophageal and pharyngeal strictures: report on 1,862 endoscopic dilatations using the Savary-Gilliard technique

Treatment of symptomatic pharyngeal and esophageal strictures requires endoscopic dilatation. The Savary-Gilliard bougienage was developed by our department and has been used since 1980 for this purpose. We report our experience using this technique. The records of patients seen from January 1, 1963 to December 31, 2005, who had pharyngeal and esophageal strictures needing dilatation, were reviewed. The prevalence of different etiologies, and the incidence of complications using the Savary-Gilliard dilators were assessed. Efficiency of dilatation was assessed over a 17-year segment of this period, using number of dilatations and time intervals between dilatations until resolution of symptoms as outcome measures. Of the 2,652 pharyngeal and esophageal strictures reviewed, 90% were of organic origin (45% benign and 55% malignant stenoses), and 10% were of functional etiology. The most common etiologies were peptic strictures before the era of proton pump inhibitors, and postoperative anastomotic strictures thereafter. A total of 1,862 dilatations using the Savary-Gilliard technique were analyzed. Complication and mortality rates were 0.18 and 0.09% for benign and 4.58 and 0.81% for malignant etiologies, respectively. The number of dilatations per stricture and the time interval between different sessions were dependent on the type of strictures, varying from 1 to 23 dilatations and 7 days to 16 years, respectively. Pharyngeal and esophageal dilatations using the Savary-Gilliard technique were safe when used together with fluoroscopy. Overall, the efficiency of the dilatation procedure was good, but some types of strictures (e.g., caustic, post-surgical and/or post radiotherapy) were refractory to treatment and required repeated dilatations.

Characterization and classification of matrix effects in biological samples analyses.

An exhaustive classification of matrix effects occurring when a sample preparation is performed prior to liquid-chromatography coupled to mass spectrometry (LC-MS) analyses was proposed. A total of eight different situations were identified allowing the recognition of the matrix effect typology via the calculation of four recovery values. A set of 198 compounds was used to evaluate matrix effects after solid phase extraction (SPE) from plasma or urine samples prior to LC-ESI-MS analysis. Matrix effect identification was achieved for all compounds and classified through an organization chart. Only 17% of the tested compounds did not present significant matrix effects.

The "open" chimney graft technique for juxtarenal aortic aneurysms with discrepant renal arteries.

OBJECTIVES: A straightforward original Chimney Graft (CG) protocol has been developed at our institution in selected cases of juxtarenal aortic aneurysm (JRAA). The aim of this study was to present our clinical experience of consecutive series with use of uncovered self-expanding stent (SES) as "Open Chimney" (OCh) in the endovascular repair (EVAR) of JRAA. METHODS: A standard endograft with suprarenal fixation struts is delivered with its proximal covered edge just below the highest RA in JRAA presenting the ostium of the two renal arteries at a different aortic level and the distance between the highest renal artery and the beginning of the aneurysm (improved landing zone) ≥10 mm. The low-lying renal artery is maintained patent by the OCh graft (standard SES) delivered from left brachial access (6 Fr). All clinical, anatomical, and operative data were prospectively collected and retrieved for the study analysis. RESULTS: From July 2010 to November 2012, OCh EVAR was offered to 22 consecutive patients considered unfit for JRAA open repair. All procedures were technically successful with aneurysm exclusion and patent OCh graft. One small perioperative type Ia endoleak spontaneously disappeared at the 3-month CT control. One patient died because of acute decompensated heart failure. One patient presented a left hemispheric stroke. The median follow-up of 18 months (range 7-35) showed aneurysm exclusion in all patients without type I and III endoleaks, SES stenosis, and/or renal impairment. CONCLUSIONS: OCh-EVAR is a straightforward technique that can be employed in selected cases of JRAA, avoiding the more complex and expensive fenestrated EVAR.

A new technique to improve tissue grip and contact force in arthroscopic capsulolabral repair: the MIBA stitch.

The success of anatomic repair of Bankart lesion diminishes in the presence of a capsule stretching and/or attenuation is reported in a variable percentage of patients with a chronic gleno-humeral instability. We introduce a new arthroscopic stitch, the MIBA stitch, designed with a twofold aim: to improve tissue grip to reduce the risk of soft tissue tear, particularly cutting through capsular-labral tissue, to and address capsule-labral detachment and capsular attenuation using a double loaded suture anchor. This stitch is a combination of horizontal mattress stitch passing through the capsular-labral complex in a "south-to-north" direction and an overlapping single vertical suture passing through the capsule and labrum in a "east-to-west" direction. The mattress stitch is tied before the vertical stitch in order to reinforce the simple vertical stitch, improving grip and contact force between capsular-labral tissue and glenoid bone.

Improved multiple-locus variable-number tandem-repeat assay for Staphylococcus aureus genotyping, providing a highly informative technique together with strong phylogenetic value.

We describe an improved multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) scheme for genotyping Staphylococcus aureus. We compare its performance to those of multilocus sequence typing (MLST) and spa typing in a survey of 309 strains. This collection includes 87 epidemic methicillin-resistant S. aureus (MRSA) strains of the Harmony collection, 75 clinical strains representing the major MLST clonal complexes (CCs) (50 methicillin-sensitive S. aureus [MSSA] and 25 MRSA), 135 nasal carriage strains (133 MSSA and 2 MRSA), and 13 published S. aureus genome sequences. The results show excellent concordance between the techniques' results and demonstrate that the discriminatory power of MLVA is higher than those of both MLST and spa typing. Two hundred forty-two genotypes are discriminated with 14 VNTR loci (diversity index, 0.9965; 95% confidence interval, 0.9947 to 0.9984). Using a cutoff value of 45%, 21 clusters are observed, corresponding to the CCs previously defined by MLST. The variability of the different tandem repeats allows epidemiological studies, as well as follow-up of the evolution of CCs and the identification of potential ancestors. The 14 loci can conveniently be analyzed in two steps, based upon a first-line simplified assay comprising a subset of 10 loci (panel 1) and a second subset of 4 loci (panel 2) that provides higher resolution when needed. In conclusion, the MLVA scheme proposed here, in combination with available on-line genotyping databases (including http://mlva.u-psud.fr/), multiplexing, and automatic sizing, can provide a basis for almost-real-time large-scale population monitoring of S. aureus.

Applications of MALDI-TOF mass spectrometry in clinical diagnostic microbiology.

Until recently, microbial identification in clinical diagnostic laboratories has mainly relied on conventional phenotypic and gene sequencing identification techniques. The development of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) devices has revolutionized the routine identification of microorganisms in clinical microbiology laboratories by introducing an easy, rapid, high throughput, low-cost, and efficient identification technique. This technology has been adapted to the constraint of clinical diagnostic laboratories and has the potential to replace and/or complement conventional identification techniques for both bacterial and fungal strains. Using standardized procedures, the resolution of MALDI-TOF MS allows accurate identification at the species level of most Gram-positive and Gram-negative bacterial strains with the exception of a few difficult strains that require more attention and further development of the method. Similarly, the routine identification by MALDI-TOF MS of yeast isolates is reliable and much quicker than conventional techniques. Recent studies have shown that MALDI-TOF MS has also the potential to accurately identify filamentous fungi and dermatophytes, providing that specific standardized procedures are established for these microorganisms. Moreover, MALDI-TOF MS has been used successfully for microbial typing and identification at the subspecies level, demonstrating that this technology is a potential efficient tool for epidemiological studies and for taxonomical classification.

Sclerotherapy of telangiectasias: a painless two-step technique.

BACKGROUND: Sclerotherapy of telangiectasias and reticular leg veins can be unpleasant and painful for some patients. OBJECTIVE: To determine pain level with two different sclerotherapy techniques in a prospective randomized trial. METHODS: Patients with symmetrical telangiectasias and reticular veins on both legs (C(1A) or (S)E(P)A(S)P(N1) were randomized to the standard (successive injections of chromated glycerin mixed with one-third lidocaine-epinephrine 1%) or two-step technique (first treating only reticular veins with a single injection at the base of each cluster of telangiectasias and then successively injecting all remaining telangiectasias a few minutes later. Pain was assessed using a 100-point visual analogue scale (0 = no pain, 100 = maximum pain). RESULTS: Data from 53 consecutive patients could be evaluated. The two-step technique was significantly less painful (28.2) than the standard technique (40.6, p < .001). CONCLUSION: The two-step technique with chromated glycerin mixed with one-third lidocaine-epinephrine 1% significantly reduces sclerotherapy pain. This may be a useful technique for patients who are particularly sensitive or afraid of sclerotherapy.

Solid-phase microextraction as short-term sampling technique for BTEX occupational exposure

Solid phase microextraction (SPME) has been widely used for many years in various applications, such as environmental and water samples, food and fragrance analysis, or biological fluids. The aim of this study was to suggest the SPME method as an alternative to conventional techniques used in the evaluation of worker exposure to benzene, toluene, ethylbenzene, and xylene (BTEX). Polymethylsiloxane-carboxen (PDMS/CAR) showed as the most effective stationary phase material for sorbing BTEX among other materials (polyacrylate, PDMS, PDMS/divinylbenzene, Carbowax/divinylbenzene). Various experimental conditions were studied to apply SPME to BTEX quantitation in field situations. The uptake rate of the selected fiber (75 μm PDMS/CAR) was determined for each analyte at various concentrations, relative humidities, and airflow velocities from static (calm air) to dynamic (>200 cm/s) conditions. The SPME method also was compared with the National Institute of Occupational Safety and Health method 1501. Unlike the latter, the SPME approach fulfills the new requirement for the threshold limit value-short term exposure limit (TLV-STEL) of 2.5 ppm for benzene (8 mg/m3).