Time-of-flight scatter rejection in x-ray radiography.

Objective.Time-of-flight (TOF) scatter rejection allows for identifying and discarding scattered photons without the use of an anti-scatter grid (ASG). Although TOF scatter rejection was initially presented for cone-beam computed tomography, we propose, herein, to extend this approach to x-ray radiography. This work aims to evaluate with simulations if TOF scatter rejection can outperform ASGs for radiography.Approach.GATE was used to simulate the radiography of a head and a torso and a water cylinder with bone inserts in a system with total timing jitters from 0 ps up to 500 ps full-width-at-half-maximum. The transmission factor of TOF scatter rejection for primary and scattered photons was evaluated as if it were a virtual ASG.Main results.With a total timing jitter of 50 ps, TOF scatter rejection can reach a selectivity of 4.93 with a primary photons transmission of 99%. Reducing the timing jitter close to 0 ps increases the selectivity up to 15.85 for a head and torso radiography, outperforming typical ASGs which usually have a selectivity from 2.5 to 10 with a primary photons transmission from 50% to 70%.Significance.This suggests that TOF scatter rejection may be suitable to replace ASGs in applications requiring lower radiation exposure if sufficiently low timing jitter is achieved.

Evaluación de la rehabilitación intensiva con bloqueo continuo del nervio supraescapular para el tratamiento de la capsulitis adhesiva refractaria de hombro. Serie de casos / Evaluation of intensive rehabilitation under continuous suprascapular nerve blockade for the treatment of refractory adhesive shoulder capsulitis. Case series

Introducción: El tratamiento de la capsulitis adhesiva refractaria de hombro es difícil. Este estudio observacional retrospectivo evaluó la efectividad a largo plazo del protocolo de fisioterapia intensiva con bloqueo periférico continuo del nervio supraescapular (BNSE). Método: Revisamos 29 historias clínicas de pacientes con capsulitis adhesiva y les tratamos con fisioterapia intensiva con BNSE durante 10 días. Se registraron los resultados del cuestionario de la escala DASH (Disabilities of the Arm, Shoulder and Hand Outcome Questionnaire) y los movimientos de hombro al inicio, a los 10 días de la infusión de anestésico local y transcurridos tres meses del procedimiento. Resultados: Veintiséis pacientes mejoraron los movimientos de hombro transcurridos 10 días de tratamiento. Se realizó seguimiento completo de 16 pacientes transcurridos tres meses del programa de rehabilitación. El rango de cuatro movimientos de hombro, compatible con una vida diaria normal, fue adquirido por nueve pacientes transcurridos tres meses. No se observó diferencia significativa en términos de movimiento de hombro entre la infusión de AL y transcurridos tres meses. Al finalizar la infusión, la puntuación DASH se redujo significativamente a 59,3 (n=26), y transcurridos tres meses se mantuvo en 42,1 (n=16). A los tres meses, el 33% de la población inicial alcanzó objetivamente los cuatro objetivos, compatibles con una calidad de vida correcta. Conclusión: La rehabilitación con BNSE está asociada a una mejora significativa a largo plazo en términos de movimiento de hombro y calidad de vida en los pacientes con capsulitis adhesiva. Son necesarios ensayos controlados aleatorizados para demostrar nuestros resultados alentadores.(AU)

Introduction: Treatment of refractory adhesive shoulder capsulitis is a challenge. This observational retrospective study evaluated the long-term effectiveness of intensive physiotherapy protocol under a continuous peripheral blockade of the suprascapular nerve (cSSNB). Method: We reviewed 29 medical records of patients suffering from adhesive capsulitis and treated with intensive physiotherapy under cSSNB during 10 days. The “disabilities of the arm, shoulder and hand” outcome questionnaire (DASH score) and shoulder movements were recorded at the beginning, 10 days after local anesthetic infusion and three months after. Results: Twenty six patients significant improved shoulder movements after 10 days of treatment. Sixteen patients were followed completely until 3 months after rehabilitation program. Range of four shoulder motion compatible with a normal daily life was acquired in nine patients at three months. There is no significant difference in shoulder motion between the end of LA infusion and at three months. At the end of infusion, DASH score is significantly decreased to 59.3 (n=26), and persists three months 42.1 (n=16). At three months, 33% of the initial population objectively reach the 4 goals, compatible with a correct quality of life. Conclusion: Rehabilitation under cSSNB is associated with a significant long term improvement in shoulder motion and quality of life in patients with adhesive capsulitis. Randomized controlled trials will be necessary to demonstrate our encouraging results.(AU)

Evaluation of intensive rehabilitation under continuous suprascapular nerve blockade for the treatment of refractory adhesive shoulder capsulitis. Case series.

INTRODUCTION: Treatment of refractory adhesive shoulder capsulitis is a challenge. This observational retrospective study evaluated the long-term effectiveness of intensive physiotherapy protocol under a continuous peripheral blockade of the suprascapular nerve (cSSNB). METHOD: We reviewed 29 medical records of patients suffering from adhesive capsulitis and treated with intensive physiotherapy under cSSNB during 10 days. The "disabilities of the arm, shoulder and hand" outcome questionnaire (DASH score) and shoulder movements were recorded at the beginning, 10 days after local anesthetic infusion and three months after. RESULTS: Twenty six patients significant improved shoulder movements after 10 days of treatment. Sixteen patients were followed completely until 3 months after rehabilitation program. Range of four shoulder motion compatible with a normal daily life was acquired in nine patients at three months. There is no significant difference in shoulder motion between the end of LA infusion and at three months. At the end of infusion, DASH score is significantly decreased to 59.3 (n = 26), and persists three months 42.1 (n = 16). At three months, 33% of the initial population objectively reach the 4 goals, compatible with a correct quality of life. CONCLUSION: Rehabilitation under cSSNB is associated with a significant long term improvement in shoulder motion and quality of life in patients with adhesive capsulitis. Randomized controlled trials will be necessary to demonstrate our encouraging results.

Prevalence of elevated blood lead levels and risk factors among children living in Patna, Bihar, India 2020.

Childhood lead exposure remains a key health concern for officials worldwide, contributing some 600,000 new cases of intellectually disabled children annually. Most children affected by high exposure to lead live in low- and middle-income countries. The leaded gasoline phase out in India was completed in 2000. Yet, in 2020, an estimated 275 million children aged 0 to 9 years had blood lead levels (BLLs) ≥ 5 µg/dL known to adversely affect intelligence and behavior. Lead sources reported in India include spices, cookware, paint, traditional medicines and cosmetics, and lead-acid battery recycling and repair. However, their relative contribution has not been characterized. More than 200 lead pollution sites related to battery recycling and repair activities were identified in Bihar and Jharkhand, India. Ninety percent of the recycling sites had soil lead concentrations exceeding the US Environmental Protection Agency's standards. We compared blood and environmental lead levels in two groups of children in Patna, Bihar. Households in proximity to battery recycling operations (Proximal n = 67) versus households distal to these operations (Distal n = 68). The average age of children was 40 months; 46% were female. Overall, the geometric mean (GM) BLL was 11.6 µg/dL. GM BLLs of children in Proximal and Distal households were not significantly different (10.2 µg/dL vs. 13.1 µg/dL respectively; p≤0.07). About 87% children, 56 Proximal and 62 Distal had BLLs ≥5 µg/dl. Lead concentrations in environmental samples were significantly higher in Proximal households (soil mean 9.8 vs. 1.6 µg/ft2; dust mean 52.9 vs. 29.9 µg/ft2 p<0.001; Proximal vs. Distal respectively) whereas concentrations in all spices were higher in Distal households (mean 46.8 vs 134.5 ppm p<0.001; Proximal vs. Distal respectively), and turmeric (mean 59.4 vs. 216.9 ppm Proximal vs. Distal respectively). In multivariate analyses for all children lead in spices and turmeric and number of rooms in the house were significant while for the Proximal group only lead in spices remained in the model. The predictive value of these models was poor. For the Distal group, a model with lead concentration in spices, turmeric and soil and number of rooms in the house was a much better fit. Of the 34 water samples collected, 7 were above the Indian standard of 10 ppb for lead in drinking water (2 in the Proximal area, 5 in the Distal area). Children in Patna, Bihar, India are exposed to multiple sources of lead, with lead levels in house dust and loose, locally sourced spices the most likely to increase blood lead levels. A holistic approach to blood lead testing and source identification and remediation are necessary to prevent lead exposure.

[Treatment of post-total knee replacement gonalgy by radiofrequency ablation of the genicular nerves]. / Traitement de gonalgies post-remplacement prothétique total de genou par thermoablation des nerfs géniculés.

Neurotomy of genicular nerves by radiofrequency is a technique efficient to reduce mecanic knee pain and pain after total knee replacement. In this article, we describe the case of a patient that has suffered from chronic knee pain after total knee replacement. The patient has successfully benefited of a neurotomy of genicular nerves by radiofrequency in the inferior right limb.

La thermoablation par radiofréquence des nerfs géniculés est une technique permettant d'atténuer les gonalgies d'origine mécanique ainsi que celles persistant après remplacement prothétique total de genou. Dans cet article, nous rapportons le cas d'une patiente souffrant de gonalgies persistantes après remplacement prothétique total du genou droit qui a bénéficié avec succès d'une neurolyse par radiofréquence des nerfs géniculés (ou thermocoagulation des nerfs géniculés) du membre inférieur droit.

Time-of-flight computed tomography - proof of principle.

Computed tomography has greatly improved over the last decade, especially through x-ray dose exposure reduction while maintaining image quality. Herein, a new concept is proposed to improve the contrast-to-noise ratio (CNR) by including the time-of-flight (TOF) information of individual photons to obtain further insight on the photon's trajectory and to reject scatter contribution. The proof of the concept relies on both simulation and experimental measurements in a cone-beam computed tomography arrangement. Results show a statistical difference between the TOF of scattered and primary photons exploitable in TOF computed tomography. For a large volume of the size of a human abdomen, a scatter reduction from 296% to 4% is achieved in our simulation setup with perfect timing measurements which yields a 110% better CNR, or a dose reduction by a factor of four. Cup artifacts are also reduced from 24.7% to 0.8%, and attenuation inaccuracies are improved from -26.3% to -0.8%. With 100 ps and 10 ps FWHM timing jitters, respectively 75% and 95% of the scatter contribution can be removed with marginal gains below 10 ps. Experimental measurements confirm the feasibility of measuring statistical differences between the TOF of scattered and primary photons.

[Platelet-rich plasma (PRP) and disc lesions: A review of the literature]. / Plasma riche en plaquettes (PRP) et lésions discales : revue de la littérature.

The spine has been the subject of extensive clinical research since it is the source of many painful complaints. However, there is little scientific evidence concerning the therapeutic proposals. During the course of life, the intervertebral disc degenerates, which over time diminishes its damping capacity and facilitates the expulsion of the nucleus pulposus through the annulus fibrosus. The degeneration of the intervertebral disc (DDI) is the origin of some back pain and various specific treatments have been developed. These include the infiltration at the center of the intervertebral disc of plasma rich platelet (PRP), composed of multiple growth factors which act on the disc degeneration. This treatment is recent and less invasive than surgery. Preliminary results seem promising. However, many gray areas and several parameters remained to be clarified. In an attempt to do this, a literature review was conducted based on bibliographic databases Pubmed, Medline and Scopus® using the following Mesh terms : PRP, platelet-rich plasma, intradiscal disc degeneration, disc, intradiscal, discogenic. This analysis reveals that at the present time, no reported study has a sufficient perspective to judge the effectiveness of the infiltration of PRP. Early harvest results will be used to set the limits of this treatment. Accordingly, it is therefore currently recommended to introduce PRP injection as a complementary solution to comprehensive care of the spine. Future research will need to generate randomized controlled studies including comparing the results with conservative treatment and measure the cost-benefit relationship.

[Pain complaints in a patient with schizophrenia]. / Vignette diagnostique de l'étudiant. Analyse critique des plaintes douloureuses du patient atteint de schizophrénie.

Schizophrenia is a complex pathology. Its prevalence reaches almost 1 %. Its semiology can be diversified. Sensorial perception can be altered included pain perception. Most of the studies conclude that psychotic patients have a hypoalgesia. It's important to consider this fact to avoid missing potentially grave somatic disease.

La schizophrénie est une pathologie complexe dont la prévalence avoisine 1 %. Sa sémiologie peut prendre de multiples formes. La discrimination sensorielle peut être altérée, y compris la perception douloureuse. La grande majorité des études réalisées à ce jour démontrent une hypoalgésie chez les patients atteints de schizophrénie. Il est important de tenir compte de ces données dans la prise en charge des patients exprimant des idées délirantes ou des hallucinations afin d'éviter de passer à côté d'affections non psychiatriques potentiellement graves.

[How I treat? complex regional pain syndrome]. / Comment je traite ... le syndrome douloureux régional complexe (SDRC).

Complex regional pain syndrome (CRPS), formerly known as algoneurodystrophy, is a painful condition of a part of the body, associated with vasomotor, motor and trophic dysfunctions that can occur after trauma. The epidemiology, diagnostic criteria and advances in physiopathology of CRPS will be briefly described. Then the different therapeutic approaches available today will be clarified.

Le syndrome douloureux régional complexe (SDRC), anciennement connu sous le nom d'algoneurodystrophie, est un état douloureux d'une région du corps, souvent un membre, associé à des troubles vasomoteurs, moteurs et trophiques, qui peut survenir après un traumatisme. Nous décrivons brièvement l'épidémiologie, les critères diagnostiques et les avancées dans la physiopathologie. Nous explicitons ensuite les différents schémas thérapeutiques disponibles actuellement.

[Regional anesthesia: an extra-benefit for our patients]. / L'anesthésie locorégionale, un plus pour nos patients ....

Regional anesthesia is gaining popularity. It provides various benefits, including high quality postoperative analgesia. This leads to a diminished postoperative opioid consumption, less sensitization of peripheral and central neurons, and a reduced risk of persistent chronic pain. Moreover, regional blocks optimize functional recovery after surgery and improve the outcome of cancer patients who undergo surgery. They also reduce the risk of postoperative complications, especially wound complications. Also, regional blocks are frequently used in the management of chronic pain. Finally, in recent years, technological progress (such as the use of ultrasonography) has made these anesthesia techniques safer and more comfortable for the patient.

Pregnancy affects morphology of induced endometriotic lesions in a mouse model through alteration of proliferation and angiogenesis.

OBJECTIVE: Pregnancy is known to alleviate the symptoms of endometriosis and is also known to be a pro-angiogenic condition affecting blood and lymphatic vessels. However, angiogenesis actively participates in the development of endometriosis. The objective of our study was to study the impact of pregnancy on endometriotic tissue. Study design We performed a cross-sectional, control versus treatment study in a mouse model of endometriosis. Thirty-one female C57Bl6 mice were mated and became pregnant and 31 females were not mated and served as control. Intraperitoneal endometriotic lesions were surgically induced in C57Bl6 mice which were subsequently mated or not (group P: pregnant, group NP: non-pregnant). P and NP mice were sacrificed on day E15.5 of the pregnancy of P mice and lesions were harvested. Lesions were weighed and analyzed by histology, immunohistology, flow cytometry and real-time quantitative RT-PCR (qRT-PCR). RESULTS: Pregnancy reduced lesion weight, decreased the proportion of cystic component (0.02 vs. 0.4; p<0.001) and modified the architecture of peritoneal endometriotic lesions. Pregnancy also increased cell proliferation in both stromal and glandular tissue as shown by the increase in Ki 67-positive cells in the P group (glandular: 19 vs. 3.9%, p<0.001; stromal: 8.7 vs. 3.3%, p<0.01). Finally, pregnancy increased angiogenesis in endometriotic lesions as indicated by an increased microvessel density (CD-31 and LYVE-1 stainings: respectively 2.2 vs. 5.1%, p<0.01 and 0.4 vs. 0.9%, p<0.001), an increased number of LYVE1 positive cells evaluated by flow cytometry (18.9 vs. 4.6%, p<0.05) and a rise in VEGF-A, -R2 and -R3 RNA expression shown by qRT-PCR (p<0.001; p<0.01; p<0.05). CONCLUSION: These challenging results provide insight in understanding the pathophysiology of endometriosis and evoke a correlation between lesion architecture and symptomatology.

[Cyber-bullying in adolescents: associated psychosocial problems and comparison with school bullying]. / Le cyber-bullying à l'adolescence : problèmes psycho-sociaux associés et spécificités par rapport au bullying scolaire.

AIM: The aim of this study was to determine the prevalence of adolescents engaged in cyber-bullying and then to identify whether students involved in cyber- and school bullying present the same characteristics of internalizing problems (insomnia, perceived social disintegration, psychological distress) and externalizing problems (general aggressiveness, antisocial behavior). METHOD: Semi-structured interviews were conducted with 738 adolescents from a high-school and a middle-school (mean age=14.8 ± 2.7). The Electronic Bullying Questionnaire and the Olweus Bully/Victim Questionnaire were used to identify profiles of cyber-bullying (cyber-victim, cyber-bully, cyber-bully/victim and cyber-neutral) and school bullying (victim, bully, bully/victim and neutral). Internalizing problems were investigated using the Athens Insomnia Scale, a Perceived Social Disintegration Scale and a Psychological Distress Scale. Externalizing problems were assessed using a General Aggressiveness Scale and an Antisocial Behavior Scale. RESULTS: Almost one student in four was involved in cyber-bullying (16.4% as cyber-victim, 4.9% as cyber-bully and 5.6% as cyber-bully/victim); 14% of our sample was engaged in school bullying as a victim, 7.2% as a bully and 2.8% as a bully/victim. The majority of adolescents involved in cyber-bullying were not involved in school bullying. With regard to the problems associated with school bullying, internalizing problems were more prevalent in victims and bully/victims, whereas externalizing problems were more common in bullies and bully/victims. A similar pattern was found in cyber-bullying where internalizing problems were characteristic of cyber-victims and cyber-bully/victims. Insomnia was elevated in the cyber-bully group which is specific to cyberbullying. General aggressiveness and antisocial behavior were more prevalent in cyber-bullies and cyber-bully/victims. Looking at the differences between types of bullying, victims of "school only" and "school and cyber" bullying had higher scores for insomnia and perceived social disintegration than victims of "cyber only" bullying or students "non-involved". Higher general aggressiveness scores were observed for "school only" bullies and "school and cyber" bullies than for bullies in "cyber only" bullying or students "non-involved". Regarding antisocial behavior, "school only" bullies, "cyber only" bullies, "school and cyber" bullies had higher scores than students "non-involved". DISCUSSION: This study highlights the importance of investigating both school and cyber-bullying as many psychosocial problems are linked to these two specific and highly prevalent forms of bullying.

An outbreak of hepatitis A in recently vaccinated students from ice snacks made from contaminated well water.

On 30 May 2006, township S in Sichuan Province, China, reported an outbreak of hepatitis A (HA) in students who had recently received HA vaccine. The concern was raised that the vaccine had caused the outbreak. We attempted to identify the source of infection and mode of transmission. A HA case was defined as onset of jaundice or anorexia since 1 April 2006 with a twofold elevation of alanine aminotransferase (ALT) and anti-HA virus-IgM in a resident of or visitor to the township. Exposures to vaccine and snacks of 90 case-students to those of 107 control-students were compared. Thirty-four per cent of cases ate ice slush compared to 4.7% of controls (OR 4.1), and 51% of cases ate snow cones compared to 17% of controls (OR 8.3). The ice snacks were made with well water. HA virus RNA was detected by reverse transcription-polymerase chain reaction from patients' blood and well water. Untreated well water poses important dangers to the public in areas where piped, potable water is available.

[Regional analgesia after lower limb orthopaedic surgery]. / Analgésie après chirurgie orthopédique du membre inférieur: intérêt de l'anesthésie locorégionale périphérique.

To provide postoperative analgesia, the anaesthesist has at his disposal a panel of different medications and also regional techniques of neural blockade. Loco-Regional analgesia (epidural or peripheral nerve block), by the use of local anaesthetics, blocks conduction of the painful influx to th central nervous system. Pain relief using peripheral nerve blocks after lower limb surgery represents as good alternative to the epidural analgesia and is superior to controlled analgesia with morphine. Peripheral nerve blocks, by decreasing the use of opioids in the postoperative period, reduce the incidence of side effects related to these molecules. They are also devoided of the adverse events due to the epidural analgesia like urinary retention or need for continuous monitoring. Analgesia after total knee prosthesis and hallux valgus surgery has considerably evolved. Postoperative analgesia is important in these cases: it facilitates physical therapy and improves patient's rehabilitation and satisfaction, it also shortens hospital stay. The aim of this review is to explain the different techniques of peripheral neural blockade and assess the value of this technique for the postoperative period after these two surgeries.

Open surgery for abdominal aortic aneurysm or aorto-iliac occlusive disease--clinical and ultrasonographic long-term results.

OBJECTIVE: To determine postoperative and long-term outcome and assess the relevance of abdominal ultrasound (US) after surgery for abdominal aortic aneurysm (AAA) or aortoiliac occlusive disease (AIOD). METHODS: Records of 1704 consecutive patients having graft implantation from 1988 to 2000, either for AAA (n = 1144) or for AIOD (n = 560), were reviewed. In 2006, follow-up was 9180 patients-years for the AAA group and 5450 patients-years for the AIOD group. Among 1006 alive patients, 377 were invited randomly for US and clinical examination. RESULTS: Hospital death occurred in 99 patients (8.6%) of the AAA group (53% in ruptured and 2% in elective AAA), and in 18 patients of the AIOD group (3.2%). There were 581 late deaths, including eight due to prosthesis infection, one to pseudo-aneurysm rupture, and one to graft thrombosis (0.6% graft-related mortality). Prosthesis thrombosis occurred in 32 patients (26 in AIOD group, p < 0.001), and graft infection in 26 (17 in AAA group, p < 0.01). Pseudoaneurysms developed in 90 patients (68 in AIOD group, p < 0.001), including eight at the proximal aortic, one at the distal aortic, two at the iliac and 79 at the femoral anastomosis. In the AAA group only, surgery was required for a new thoraco-abdominal and pararenal aneurysm in eight and four patients, respectively, while US evidenced a 26-35 and a 36-50 mm supraanastomotic aortic dilatation in 65 (32%) and in 14 (7%) patients, at a mean follow-up of 10.5 and 9.3 years, respectively. CONCLUSION: Long-term results are good after open surgery for AAA or AIOD. Prosthesis infection and anastomotic pseudo-aneurysm are the main causes of graft-related mortality and morbidity, respectively. Because of high incidence of asymptomatic supraanastomotic aortic dilatation, all patients with a history of AAA repair should have regular abdominal US.

IL-9/IL-9 receptor signaling selectively protects cortical neurons against developmental apoptosis.

In mammals, programmed cell death (PCD) is a central event during brain development. Trophic factors have been shown to prevent PCD in postmitotic neurons. Similarly, cytokines have neurotrophic effects involving regulation of neuronal survival. Nevertheless, neuronal PCD is only partially understood and host determinants are incompletely defined. The present study provides evidence that the cytokine interleukin-9 (IL-9) and its receptor specifically control PCD of neurons in the murine newborn neocortex. IL-9 antiapoptotic action appeared to be time-restricted to early postnatal stages as both ligand and receptor transcripts were mostly expressed in neocortex between postnatal days 0 and 10. This period corresponds to the physiological peak of apoptosis for postmitotic neurons in mouse neocortex. In vivo studies showed that IL-9/IL-9 receptor pathway inhibits apoptosis in the newborn neocortex. Furthermore, in vitro studies demonstrated that IL-9 and its receptor are mainly expressed in neurons. IL-9 effects were mediated by the activation of the JAK/STAT (janus kinase/signal transducer and activator of transcription) pathway, whereas nuclear factor-kappaB (NF-kappaB) or Erk pathways were not involved in mediating IL-9-induced inhibition of cell death. Finally, IL-9 reduced the expression of the mitochondrial pro-apoptotic factor Bax whereas Bcl-2 level was not significantly affected. Together, these data suggest that IL-9/IL-9 receptor signaling pathway represents a novel endogenous antiapoptotic mechanism for cortical neurons by controlling JAK/STAT and Bax levels.

[Analgesia for wound dressing by continuous peripheral nerve block]. / Analgésie par blocs nerveux périphériques continus dans le cadre des soins de plaies cutanées.

We present the case of a patient with a circumferential venous ulcer at the level of the calf. She is hospitalized for surgical treatment by continuous aspiration dressing and coverage with skin graft. This patient presents a history of chronic pain, on which classical medications have few effects and are accompanied by side effects. After discussion with the patient, a double continuous peripheral nervous block (femoral and sciatic nerve) is set up to improve the tolerance to wound dressing. This technique presents favorable antalgic results. The indications and the different techniques of block performance (by electrostimulation or echo-guided) are described. The infectious risks related to the presence of catheter near cutaneous wounds are clarified according to recent data of literature. The relevance of these techniques in correlation with the development of chronic pain and on the trophicity of the wounds are also discussed.

Sci-Fri AM: YIS-02: Evaluation of the LabPET4 imaging capabilities for in vivo small animal imaging.

Positron Emission Tomography (PET) is a non-invasive technique to visualize metabolic and physiological processes in vivo. Excellent imaging capabilities such as spatial resolution and count rate performance are essential to achieve accurate information about the observed processes. It is for this purpose that the LabPET scanner, an avalanche photodiode (APD)-based fully digital scanner PET scanner, was initially developed. Two variants of the scanner exist: LabPET4 and LabPET8 with 3.75 and 7.5 cm axial lengths respectively. The range of the transaxial FOV is up to 10 cm therefore it can easily accommodate mice and rats. The aim of this work is to evaluate LabPET4 imaging in several phantoms and small animals. Spatial resolution was determined using a point source and hot spots phantoms. The latter were used to assess recovery coefficients (RC) obtained by taking the ratio of hot spot maximum values compared to the biggest spot maximum value. FBP reconstructed tangential/radial resolution is 1.3/1.4 mm FWHM (2.5/2.4 FWTM) at the field of view center. With an Ultra Micro Hot Spot Phantom, 1 mm spots are clearly resolved. Count rate performance was obtained for mouse-size and rat-size phantoms. For mouse phantom, scatter fraction is 18%, noise equivalent count rate (NEC) peak is 120 kcps at 5.6 mCi and true coincidences peak is 215 kcps at 6.6 mCi. Mice and rats were imaged with Na18F and 18FDG. LabPET4 imaging capabilities achieve state-of-the-art requirements for molecular imaging and therefore can provide excellent quality images.

Sci-Sat AM(1): Imaging-08: Small animal APD PET detector with submillimetric resolution for molecular imaging.

Visualization and quantification of biological processes in mice, the preferred animal model in most preclinical studies, require the best possible spatial resolution in positron emission tomography (PET). A new 64-channel avalanche photodiode (APD) detector module was developed to achieve submillimeter spatial resolution for this purpose. The module consists of dual 4 × 8 APD arrays mounted in a custom ceramic holder. Individual APD pixels having an active area of 1.1 × 1.1 mm2 at a 1.2 mm pitch can be fitted to an 8 × 8 LYSO scintillator block designed to accommodate one-to-one coupling. An analog test board with four 16-channel preamplifier ASICs was designed to be interfaced with the existing LabPET digital processing electronics. At a standard APD operating bias, a mean energy resolution of 27.5 ± 0.6% was typically obtained at 511 keV with a relative standard deviation of 13.8% in signal amplitude for the 64 individual pixels. Crosstalk between pixels was found to be well below the typical lower energy threshold used for PET imaging applications. With two modules in coincidence, a global timing resolution of 5.0 ns FWHM was measured. Finally, an intrinsic spatial resolution of 0.8 mm FWHM was measured by sweeping a 22Na point source between two detector arrays. The proposed detector module demonstrates promising characteristics for dedicated mouse PET imaging at submillimiter resolution.

Melatonin prevents learning disorders in brain-lesioned newborn mice.

Perinatal brain injuries often result in irreversible learning disabilities, which manifest in early childhood. These injuries are chiefly ascribable to marked susceptibility of the immature brain to glutamate-induced excitotoxicity. No treatments are available. One well-characterized model of perinatal brain injuries consists in injecting the glutamate analog ibotenate into the brain of 5-day-old mice. The resulting excitotoxic lesions resemble the hypoxic-ischemic gray-matter lesions seen in full-term and near-term newborns, as well as the white-matter lesions of preterm newborns. We previously reported that these lesions disrupted odor preference conditioning in newborn mice. The aim of this study was to assess the effectiveness of the neuroprotector melatonin in preventing learning disabilities in newborn mice with ibotenate-induced brain injury. In postnatal day (P) 6-P7 pups, we tested psychomotor reflexes, spontaneous preference for maternal odors as an index of memory, ultrasonic vocalization responses to stroking as an index of sensitivity to tactile stimuli, and conditioned preference for an odor previously paired with stroking as an index of learning abilities. Without melatonin, conditioning was abolished, whereas spontaneous odor preference, psychomotor reflexes, and sensitivity to tactile stimuli were normal. Thus, abolition of conditioning was not associated with sensorimotor impairments. Histological analysis confirmed the efficacy of melatonin in reducing white-matter lesions induced by ibotenate. Furthermore, treatment with melatonin protected the ability to develop conditioning. Thus, melatonin, which easily crosses the blood-brain barrier and has been proven safe in children, may be effective in preventing learning disabilities caused by perinatal brain injuries in human preterm infants.