Design and evaluation of an abbreviated pixelwise dynamic contrast enhancement analysis protocol for early extracellular volume fraction estimation.

INTRODUCTION: T1-based method is considered as the gold standard for extracellular volume fraction (ECV) mapping. This technique requires at least a 10 min delay after injection to acquire the post injection T1 map. Quantitative analysis of Dynamic Contrast Enhancement (DCE) images could lead to an earlier estimation of an ECV like parameter (2 min). The purpose of this study was to design a quantitative pixel-wise DCE analysis workflow to assess the feasibility of an early estimation of ECV. METHODS: Fourteen patients with mitral valve prolapse were included in this study. The MR protocol, performed on a 3 T MR scanner, included MOLLI sequences for T1 maps acquisition and a standard SR-turboFlash sequence for dynamic acquisition. DCE data were acquired for at least 120 s. We implemented a full DCE analysis pipeline with a pre-processing step using an innovative motion correction algorithm (RC-REG algorithm) and a post-processing step using the extended Tofts Model (ECVETM). Estimated ECVETM maps were compared to standard T1-based ECV maps (ECVT1) with both a Pearson correlation analysis and a group-wise analysis. RESULTS: Image and map quality assessment showed systematic improvements using the proposed workflow. Strong correlation was found between ECVETM, and ECVT1 values (r-square = 0.87). CONCLUSION: A DCE analysis workflow based on RC-REG algorithm and ETM analysis can provide good quality parametric maps. Therefore, it is possible to extract ECV values from a 2 min-long DCE acquisition that are strongly correlated with ECV values from the T1 based method.

Synthetic MRI is not yet ready for morphologic and functional assessment of patellar cartilage at 1.5Tesla.

PURPOSE: The purpose of this study was to compare morphologic assessment and relaxometry of patellar hyaline cartilage between conventional sequences (fast spin-echo [FSE] T2-weighted fat-saturated and T2-mapping) and synthetic T2 short-TI inversion recovery (STIR) and T2 maps at 1.5T magnetic resonance imaging (MRI). METHOD: The MRI examinations of the knee obtained at 1.5T in 49 consecutive patients were retrospectively studied. There were 21 men and 28 women with a mean age of 45±17.7 (SD) years (range: 18-88 years). Conventional and synthetic acquisitions were performed, including T2-weighted fat-saturated and T2-mapping sequences. Two radiologists independently compared patellar cartilage T2-relaxation time on conventional T2-mapping and synthetic T2-mapping images. A third radiologist evaluated the patellar cartilage morphology on conventional and synthetic T2-weighted images. The presence of artifacts was also assessed. Interobserver agreement for quantitative variables was assessed using intraclass correlation coefficient (ICC). RESULTS: In vitro, conventional and synthetic T2 maps yielded similar mean T2 values 58.5±2.3 (SD) ms and 58.8±2.6 (SD) ms, respectively (P=0.414) and 6% lower than the expected experimental values (P=0.038). Synthetic images allowed for a 15% reduction in examination time compared to conventional images. On conventional sequences, patellar chondropathy was identified in 35 patients (35/49; 71%) with a mean chondropathy grade of 4.8±4.8 (SD). On synthetic images, 28 patients (28/49; 57%) were diagnosed with patellar chondropathy, with a significant 14% difference (P=0.009) and lower chondropathy scores (3.7±4.9 [SD]) compared to conventional images. Motion artifacts were more frequently observed on synthetic images (18%) than on conventional ones (6%). The interobserver agreement was excellent for both conventional and synthetic T2 maps (ICC>0.83). Mean cartilage T2 values were significantly greater on synthetic images (36.2±3.8 [SD] ms; range: 29-46ms) relative to conventional T2 maps (31.8±4.1 [SD] ms; range: 26-49ms) (P<0.0001). CONCLUSION: Despite a decrease in examination duration, synthetic images convey lower diagnostic performance for chondropathy, greater prevalence of motion artifacts, and an overestimation of T2 values compared to conventional MRI sequences.

Pregnancy impairs resistance of C57BL/6 mice to Leishmania major infection.

To determine if gestational factors affect the severity of L. major infection, this study assessed the levels of IL-4 mRNA and IFN-gamma mRNA in popliteal lymph node cells of pregnant C57BL/6 mice mated at 5 hours, 16 hours and 15 days post L. major infection using PCR. Infected pregnant C57BL/6 mice developed larger cutaneous footpad lesions compared with non-pregnant infected C57BL/6 mice. The resolution of footpad lesions commenced after 8th week in C57BL/6 mice mated at 16 hrs post L. major infection but 12 weeks in C57BL/6 mice mated at 5 hrs and 15 days post L. major infection. C57BL/6 mice that were infected 20 days post partum resolved L. major infection effectively. But, the lesions in infected pregnant C57BL/6 mice and infected non-pregnant C57BL/6 mice were not as large as in susceptible BALB/c mice. The mean litter weights were similar in pregnant infected C57BL/6 mice mated at different stages of L. major infection but were slightly lower than weights of litters from pregnant uninfected C57BL/6 mice. In 5 days infected pregnant C57BL/6 mice, the levels of IFN-gamma were raised compared with the levels of IL-4 but those mated at 15 days post L. major infection had highest level of IFN-gamma mRNA. In 10 days pregnant infected C57BL/6 mice, levels of IL-4 were raised compared with IFN-gamma but mice mated at 16 hrs post L. major infection had highest level of IL-4. In 15 days pregnant infected mice, the levels of IL-4 were higher than IFN-gamma irrespective of the stage of L. major infection when the mice were mated. Mice infected with L. major 20 days post-partum produced more IFN-gamma than IL-4 from 16 hrs post L. major infection onwards. It may be concluded that increased IL-4 in pregnant infected C57BL/6 mice impairs the resistance of C57BL/6 mice to L. major infection especially in mice that were pregnant before effective immunity (5 hours post L. major infection) is mounted against L. major infection.

[Osteoarticular infection in children: evaluation of a diagnostic and management protocol]. / Infections ostéo-articulaires de l'enfant: étude de deux séries consécutives et évaluation d'un protocole de diagnostic et de traitement.

PURPOSE OF THE STUDY: The purpose of this study was to evaluate a diagnostic and management protocol for osteoarticular infection in children which was developed at the Rouen University Hospital in 1993. We studied the technical aspects of the protocol allowing improved certain diagnosis and bacteriological documentation as well as the reduction in intravenous treatments and hospital stay. MATERIAL AND METHODS: Two successive series were compared. The first constituted from May 1984 to February 1992 was a retrospective series of 106 children with osteoarticular infections. The second series was prospective an included 104 children with osteoarticular infection treated after institution of the protocol (January 1995 to December 1998). All children were treated in the same unit. Files were reviewed at a minimum follow-up of 18 months following the end of treatment. We analyzed: clinical, biological, and radiological data at admission; elements of the bacteriological study and their contribution to identification of the causal agent; duration of intravenous antibiotic therapy; total duration of antibiotic therapy, and hospital stay; complications and sequelae. RESULTS: After institution of the protocol, we observed significant progress: certain diagnosis of acute osteomyelitis improved from 67% to 85% after institution of a more comprehensive diagnostic program; bacteriological identification improved from 37.5% to 72.2% for acute osteomyelitis and from 41.6% to 59.5% for septic arthritis, with a growing number of recognized cases of Kingella kingae infections causing acute osteomyelitis (n=2) or septic arthritis (n=4) due to technical progress in sampling and culturing. Mean duration of intravenous antibiotic therapy (15 days versus 9.95 days), mean duration of total antibiotic therapy (47.3 versus 33.8 d) as well as length of hospital stay (17.5 d versus 12.5 d) were significantly improved. The shorter antibiotic therapy did not led to any supplementary morbidity. CONCLUSIONS: A systematic bacteriological diagnostic protocol has enabled an improvement in treatment and hospitalization. The protocol has been further updated and simplified in light of these findings and observations of insufficiencies, taking into account recent data in the literature and epidemiological features of osteoarticular infection in children.

[Tracheo-oesophageal fistula. A rare complication of percutaneous tracheostomy]. / Fistule trachéo-oesophagienne. Une complication rare de la trachéotomie percutanée.

Percutaneous tracheostomy is more and more used in the intensive care units. However, it's not devoid of risks. We report the case of a patient who developed a tracheo-esophageal fistula discovered after removal of the cannula 23 days after tracheotomy. During the procedure, difficulties occurred during the insertion of the cannula. This case report reminds the importance of a peroperative continuous endoscopic guidance and the need of a rigorous learning.

[Kingella kingae osteoarticular infections in children. A report of a series of eight new cases]. / Les infections ostéoarticulaires à Kingella kingae chez l'enfant. A propos d'une série récente de huit cas.

UNLABELLED: Kingella kingae is a Gram-negative bacillus which belongs to the Neisseriaceae family. Its involvement in osteoarticular infections is relatively recent. METHODS AND RESULTS: We report eight cases of Kingella kingae osteoarticular infections that have been diagnosed at the paediatric surgical centre of Rouen University Hospital since October 1995. Six boys and two girls (mean age: 30.6 months) presented with osteomyelitis in six cases and arthritis in two. Only 75% of patients had a fever at time of diagnosis. The biological findings were slightly modified. All samples were obtained from blood, bone or joint fluid. These samples were systematically inoculated into a blood culture tube. Positive Kingella kingae culture was achieved in seven local samples and in one blood culture. All children received two antibiotics via intravenous injection while waiting for the bacteriologic results. Later, the antibiotic treatment (amoxycillin) was given per os. The mean duration of treatment was 33 days. Patients were given intravenous treatment for a period of only ten days. Six patients were followed up for a period of more than 18 months and outcome was always uneventful. DISCUSSION: Kingella kingae is usually present in the nasopharyngeal mucosa and spreads in the blood due to various infections. Different types of Kingella kingae infection have been reported with a large frequency of osteoarticular infection. CONCLUSION: This type of infection does not present any unusual characteristics as compared to other osteoarticular infections. Because of its antibiotic sensitivity treatment duration could be reduced. Kingella kingae is a fragile microbe and its culture is often difficult; therefore, it is important to use blood culture tubes to inoculate joint fluid and bone samples.