Memantine prevents acute radiation-induced toxicities at hippocampal excitatory synapses.

Background: Memantine has shown clinical utility in preventing radiation-induced cognitive impairment, but the mechanisms underlying its protective effects remain unknown. We hypothesized that abnormal glutamate signaling causes radiation-induced abnormalities in neuronal structure and that memantine prevents synaptic toxicity. Methods: Hippocampal cultures expressing enhanced green fluorescent protein were irradiated or sham-treated and their dendritic spine morphology assessed at acute (minutes) and later (days) times using high-resolution confocal microscopy. Excitatory synapses, defined by co-localization of the pre- and postsynaptic markers vesicular glutamate transporter 1 and postsynaptic density protein 95, were also analyzed. Neurons were pretreated with vehicle, the N-methyl-d-aspartate-type glutamate receptor antagonist memantine, or the glutamate scavenger glutamate pyruvate transaminase to assess glutamate signaling. For animal studies, Thy-1-YFP mice were treated with whole-brain radiotherapy or sham with or without memantine. Results: Unlike previously reported long-term losses of dendritic spines, we found that the acute response to radiation is an initial increase in spines and excitatory synapses followed by a decrease in spine/synapse density with altered spine dynamics. Memantine pre-administration prevented this radiation-induced synaptic remodeling. Conclusion: These results demonstrate that radiation causes rapid, dynamic changes in synaptic structural plasticity, implicate abnormal glutamate signaling in cognitive dysfunction following brain irradiation, and describe a protective mechanism of memantine.

The use of prophylactic Nunchaku stents to reduce the risk of nasolacrimal duct obstruction in patients with midfacial tumours undergoing radiotherapy.

The treatment of midfacial tumours with radiotherapy, chemotherapy and radio-iodine can cause nasolacrimal duct fibrosis resulting in epiphora. Nasolacrimal patency can be maintained by stenting. We report our experience of prophylatic Nunchaku stent insertion in 5 patients prior to midfacial radiotherapy. Four out of 5 patients (80%) had patent nasolacrimal ducts without any symptoms of epiphora following removal of the stents. One patient was initially asymptomatic with patent nasolacrimal duct, but subsequently developed epiphora. Nunchaku stents may provide a simple and effective way of preventing epiphora, obviate the need for nasal retrieval that is required for other nasolacrimal stents, and reduce the risk of requiring further lacrimal surgery.

[Radiotherapy during pregnancy]. / Radiothérapie et grossesse.

The diagnostic of cancer during pregnancy is a rare and delicate situation. As the developments of the embryo and the human fetus are extremely sensitive to ionizing radiations, the treatment of these tumors should be discussed. The studies - preclinical and clinical - based mostly on exposure accidents show that subdiaphragmatic treatments are possible during pregnancy. When radiotherapy is used, phantom estimations of the dose to the fetus, confirmed by in vivo measurements are required. Irradiation and imaging techniques should be arranged to decrease as much as possible the dose delivered to the fetus and hold below the threshold of 0.1Gy.

Imaging of trauma in the pregnant patient.

The pregnant trauma patient presents an important and challenging encounter for the clinical team and radiologist. In this article, we present several key aspects of the imaging workup of pregnant trauma patients, beginning with a review of the modalities that are used in this setting. Ultrasonography plays an important role in initial evaluation of the fetus but a limited role in evaluation of maternal injuries. Given that conventional radiography and computed tomography are the "workhorse" modalities for evaluation of pregnant trauma patients, radiologists must pay particular attention to radiation dose concerns. Magnetic resonance imaging can be used after the initial evaluation and for follow-up imaging, and safety concerns related to its use in pregnant patients are addressed. At imaging interpretation, radiologists must contend not only with the typical spectrum of injuries that can be seen in any trauma patient but also with pregnancy-specific injuries, such as placental abruption and uterine rupture. Particularly unusual situations, such as a ruptured ectopic pregnancy in a trauma patient, are presented. Although pregnant trauma patients are infrequently encountered, familiarity with imaging findings of injuries in these patients is essential to providing the best care for the mother and fetus.

The fisherman's cards: how to address past and future radiation exposures in clinical decision making.

OBJECTIVE. The purpose of this article is to describe how to address patients' past-and future potential-radiation exposures when making an imaging decision in a given situation. CONCLUSION. The Biologic Effects of Ionizing Radiation committee has endorsed a linear no-threshold model to explain the relationship between radiation exposure and cancer risk. This model implies that past and future potential exposures should not impact current decisions. We present an analogy that deconstructs these counterintuitive conclusions and facilitates translation of key radiation risk principles to practice.

Risco da radiação ionizante em mulheres férteis submetidas à ablação por radiofrequência / Risk of ionizing radiation in women of childbearing age undergoing radiofrequency ablation

FUNDAMENTO: A Comissão Internacional de Radiologia indica rastreamento com teste de gravidez a todas pacientes do gênero feminino em período fértil que serão submetidas a exame radiológico. Sabe-se que a radiação é teratogênica e que seu efeito é cumulativo. O potencial teratogênico inicia-se com doses próximas às das utilizadas durante esses procedimentos. Não se sabe a prevalência de teste de gravidez positivo em pacientes submetidos a estudo eletrofisiológico e/ou à ablação por cateter em nosso meio. OBJETIVO: Avaliar a prevalência de teste de gravidez positivo em pacientes do gênero feminino encaminhadas para estudo eletrofisiológico e/ou ablação por radiofrequência. MÉTODOS: Estudo transversal com análise de 2.966 pacientes submetidos a estudo eletrofisiológico e/ou ablação por cateter, de junho 1997 a fevereiro 2013, no Instituto de Cardiologia do Rio Grande do Sul. Foram realizados 1.490 exames em mulheres sendo que, destas, 769 encontravam-se em idade fértil. Todas as pacientes foram rastreadas com teste de gravidez no dia anterior ao procedimento. RESULTADOS: Detectou-se positividade do teste em três pacientes, impossibilitando a realização do exame. Observou-se prevalência de 3,9 casos por 1.000 mulheres em idade fértil. CONCLUSÃO: Devido ao baixo custo e à segurança, indica-se a realização de teste de rastreamento para gravidez a todas pacientes em idade fértil, uma vez que o grau de radiação ionizante necessária nesse procedimento é muito próximo ao limiar de teratogenicidade, principalmente no primeiro trimestre, quando os sinais de gestação não são exuberantes.

BACKGROUND: The International Commission of Radiology recommends a pregnancy screening test to all female patients of childbearing age who will undergo a radiological study. Radiation is known to be teratogenic and its effect is cumulative. The teratogenic potential starts at doses close to those used during these procedures. The prevalence of positive pregnancy tests in patients undergoing electrophysiological studies and/or catheter ablation in our midst is unknown. OBJECTIVE: To evaluate the prevalence of positive pregnancy tests in female patients referred for electrophysiological study and/or radiofrequency ablation. METHODS: Cross-sectional study analyzing 2966 patients undergoing electrophysiological study and/or catheter ablation, from June 1997 to February 2013, in the Institute of Cardiology of Rio Grande do Sul. A total of 1490 procedures were performed in women, of whom 769 were of childbearing age. All patients were screened with a pregnancy test on the day before the procedure. RESULTS: Three patients tested positive, and were therefore unable to undergo the procedure. The prevalence observed was 3.9 cases per 1000 women of childbearing age. CONCLUSION: Because of their safety and low cost, pregnancy screening tests are indicated for all women of childbearing age undergoing radiological studies, since the degree of ionizing radiation needed for these procedures is very close to the threshold for teratogenicity, especially in the first trimester, when the signs of pregnancy are not evident.

Risk of ionizing radiation in women of childbearing age undergoing radiofrequency ablation.

BACKGROUND: The International Commission of Radiology recommends a pregnancy screening test to all female patients of childbearing age who will undergo a radiological study. Radiation is known to be teratogenic and its effect is cumulative. The teratogenic potential starts at doses close to those used during these procedures. The prevalence of positive pregnancy tests in patients undergoing electrophysiological studies and/or catheter ablation in our midst is unknown. OBJECTIVE: To evaluate the prevalence of positive pregnancy tests in female patients referred for electrophysiological study and/or radiofrequency ablation. METHODS: Cross-sectional study analyzing 2966 patients undergoing electrophysiological study and/or catheter ablation, from June 1997 to February 2013, in the Institute of Cardiology of Rio Grande do Sul. A total of 1490 procedures were performed in women, of whom 769 were of childbearing age. All patients were screened with a pregnancy test on the day before the procedure. RESULTS: Three patients tested positive, and were therefore unable to undergo the procedure. The prevalence observed was 3.9 cases per 1000 women of childbearing age. CONCLUSION: Because of their safety and low cost, pregnancy screening tests are indicated for all women of childbearing age undergoing radiological studies, since the degree of ionizing radiation needed for these procedures is very close to the threshold for teratogenicity, especially in the first trimester, when the signs of pregnancy are not evident.

[Diagnosis and management of lung cancer during pregnancy]. / Le cancer bronchique de la femme enceinte : prise en charge diagnostique et thérapeutique en 2012.

The incidence of lung cancer during pregnancy is very low, but it is becoming more frequent in industrialized countries both because of the increase in smoking in young women and because women are becoming pregnant later in life. Usually, the cancer has a poor prognosis due to the presence of metastatic disease at the time of diagnosis. Diagnosis and management are delicate, and should deal with the gestational age, the maternal prognosis, the fetal toxicity of treatments, but also with the worsening of maternal prognosis and the risk of neoplastic cells being transmitted to the fetus in case of delayed treatment. Psychological and ethical considerations complicate the decision process. We present a review of the epidemiology, clinical characteristics, management, and prognosis concerning lung cancer during pregnancy. Finally, it is important to remember that young women with lung cancer should be advised to use a reliable form of contraception.

Medical imaging radiation safety for the female patient: rationale and implementation.

For the modern practitioner of women's imaging, achieving a balance between the positive diagnostic benefits available from current medical imaging on the one hand, and the potentially deleterious effects of ionizing radiation exposure on the other, has become a central issue. Increased public and professional awareness of the side effects of radiation now require a comprehensive understanding of the facts involved, the various risks to which patients are exposed, and the measures that can be implemented to minimize these risks. The major challenges posed by pregnancy, radiosensitive breast tissue, lactation, and an inability to easily exclude ovaries from the imaging field make female patients particularly vulnerable to medical imaging radiation exposure. The nature of this vulnerability changes frequently and depends on the imaging being performed, the age of the patient, and the clinical situation. For this reason, attention to gynecologic imaging radiation exposure across the whole life span is vitally important.

[Radiation protectors within the radiation safety system for extended duration exploration missions].

Radiation environment in extended duration exploration missions is scrutinized in the context of the probability of the risks of deterministic and stochastic effects of radiation. Though the probability of severe radiation damage due to solar flare is very low, nonetheless it is requisite that the crew must be provided with appropriate, including pharmacological safeguards. The current nomenclature of radiation protectors composes short-term agents against acute radiation damage. Among the others, preparation B-190 is distinguished by particularly high effectiveness and universal action, and good tolerance even when organism is exposed to the extreme factors of space flight Regimen of B-290 therapy alone and with combination with aminothiol preparations have been developed to render treatment following multiple solar events. Effectiveness of radioprotectors can be increased substantially by local shielding of the abdomen and pelvis. The most promising nonspecific stimulators of total resistance of organism are riboxin (inosin) and combined preparation aminotetravit as well as vitamins tocopherol and retinol. Therapy combining B-190 with riboxin and aminotetravit is also under discussion. Cytokine neipogen is also viewed as a candidate agent for early therapy. Concern is raised about possible development of chronic oxidative stress in long-duration exploration missions. Highlighted is the significance of adequate nutrition supplemented with fresh vegetables as a source of the most valuable bioflavonoids. Antioxidants L-selenomethionine and melatonin proved their effectiveness against heavy nuclei of galactic radiation. An open issue is how to make natural antioxidants beneficial to oxidative stress control and attenuation of low-intensity galactic radiation.

Radiation exposure and pregnancy.

INTRODUCTION: The effect of radiation on the fetus has been derived primarily from animal studies and human exposures to diagnostic and therapeutic radiation as well as atomic bomb exposure. Given the variety of sources, there is controversy over the dose of radiation in addition to the other environmental conditions that surrounded these events and their relationship to exposure today. METHODS: The effects of ionizing radiation on the fetus, the prenatal period, parental exposure, the pregnant clinician, and the pregnant patient are discussed in the context of their exposure to radiation. RESULTS: The fetus is most sensitive to radiation effects between 8 and 15 weeks of pregnancy. Stepping away from the table and using movable shields help reduce the exposure by a factor of four for every doubling of the distance between the operator and the radiation source. CONCLUSION: Proposed guidelines for pregnancy during vascular residency training involving fluoroscopic procedures can help bring about awareness, clarify maximal exposure, and better delineate the role of the pregnant resident.

SCAI consensus document on occupational radiation exposure to the pregnant cardiologist and technical personnel.

Concerns regarding radiation exposure and its effects during pregnancy are often quoted as an important barrier preventing many women from pursuing a career in Interventional Cardiology. Finding the true risk of radiation exposure from performing cardiac catheterization procedures can be challenging and guidelines for pregnancy exposure have been inadequate. The Women in Innovations group of Cardiologists with endorsement of the Society for Cardiovascular Angiography and Interventions aim to provide guidance in this publication by describing the risk of radiation exposure to pregnant physicians and cardiac catheterization personnel, to educate on appropriate radiation monitoring and to encourage mechanisms to reduce radiation exposure. Current data do not suggest a significant increased risk to the fetus of pregnant women in the cardiac catheterization laboratory and thus do not justify precluding pregnant physicians from performing procedures in the cardiac catheterization laboratory. However, radiation exposure among pregnant physicians should be properly monitored and adequate radiation safety measures are still warranted.

Imaging in pregnant patients: examination appropriateness.

A recurring source of contention between clinicians and radiologists continues to be examination appropriateness when imaging pregnant patients. With the multitude of references on potential radiation risks to the fetus, radiologists tend to be cautious and hesitant about exposing the fetus to radiation. This tendency is often interpreted by referring physicians as intrusion into and delay in the care of their patients. The risk burden of radiation exposure to the fetus has to be carefully weighed against the benefits of obtaining a critical diagnosis quickly and using a single tailored imaging study. In general, there is lower than expected awareness of radiation risks to the fetus from imaging pregnant patients. Modalities that do not use ionizing radiation, such as ultrasonography and magnetic resonance imaging, should be the preferred examinations for evaluating an acute condition in a pregnant patient. However, no examination should be withheld when an important clinical diagnosis is under consideration. Exposure to ionizing radiation may be unavoidable, but there is no evidence to suggest that the risk to the fetus after a single imaging study and an interventional procedure is significant. All efforts should be made to minimize the exposure, with consideration of the risk versus benefit for a given clinical scenario.

Dealing with pregnancy in radiology: a thin line between science, social and regulatory aspects.

The participation of pregnant women in radiology can be an emotional experience. The word "radiation" understandably invokes fear and uncertainty. Irradiation of a foetus should be avoided whenever possible. However, radiological examinations of pregnant women are often justified and unintended exposures do occur. Also pregnant radiology staff may remain working in the department. Lack of knowledge about the effects of both ionising (X-rays) and non-ionising (MRI) radiation is responsible for anxiety of patients and workers. If foetal exposures occur, they must be quantitatively evaluated and the risk put into perspective. This paper is intended to inform radiology managers, radiologists, technologists and referring clinicians in their management with pregnant patients and co-workers. The paper describes conceptus doses for both patient and worker that are associated with radiology practice, reviews the risks and effects of in utero irradiation, and discusses current national policies, international guidelines and practical aspects.

Medical radiation and pregnancy.

Many pregnant women are exposed to radiation either as a patient or as an employee. Ignorance of the issues surrounding the radiation exposure of pregnant females is encountered among medical and other professionals, often leading to undue concern. The exposure of pregnant patients has to be justified and the risk/benefit carefully assessed. Diagnostic radiological and nuclear medicine procedures do not usually pose an increased risk to the fetus but therapeutic procedures and radiotherapy may do so. Risks are greatest during organogenesis and the first trimester. Informed consent and counseling of the patient are important. Pregnant females working with radiation also need separate consideration and careful monitoring. The author has personal experience of this working as an interventional radiologist throughout pregnancy. Education of professionals working with radiation and in medicine is essential and international organizations in radiation protection should continue to provide and support this role.

Keratinocyte growth factor prevents radiation damage to salivary glands by expansion of the stem/progenitor pool.

Irradiation of salivary glands during radiotherapy treatment of patients with head and neck cancer evokes persistent hyposalivation. This results from depletion of stem cells, which renders the gland incapable of replenishing saliva to produce acinar cells. The aim of this study was to investigate whether it is possible to expand the salivary gland stem/progenitor cell population, thereby preventing acinar cell depletion and subsequent gland dysfunction after irradiation. To induce cell proliferation, keratinocyte growth factor (DeltaN23-KGF, palifermin) was administered to C57BL/6 mice for 4 days before and/or after local irradiation of salivary glands. Salivary gland vitality was quantified by in vivo saliva flow rates, morphological measurements, and a newly developed in vitro salisphere progenitor/stem cell assay. Irradiation of salivary glands led to a pronounced reduction in the stem cells of the tissues, resulting in severe hyposalivation and a reduced number of acinar cells. DeltaN23-KGF treatment for 4 days before irradiation indeed induced salivary gland stem/progenitor cell proliferation, increasing the stem and progenitor cell pool. This did not change the relative radiation sensitivity of the stem/progenitor cells, but, as a consequence, an absolute higher number of stem/progenitor cells and acinar cells survived after radiation. Postirradiation treatment with DeltaN23-KGF also improved gland function, and this effect was much more pronounced in DeltaN23-KGF pretreated animals. Post-treatment with DeltaN23-KGF seemed to act through accelerated expansion of the pool of progenitor/stem cells that survived the irradiation treatment. Overall, our data indicate that DeltaN23-KGF is a promising drug to enhance the number of salivary gland progenitor/stem cells and consequently prevent radiation-induced hyposalivation. Disclosure of potential conflicts of interest is found at the end of this article.

Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.

Use of diagnostic imaging studies for evaluation of pregnant patients with medical conditions not related to pregnancy poses a persistent and recurring dilemma. Although a theoretical risk of carcinogenesis exists, there are no known risks for development of congenital malformations or mental retardation in a fetus exposed to ionizing radiation at the levels typically used for diagnostic imaging. An understanding of the effects of ionizing radiation on the fetus at different gestational stages and the estimated exposure dose received by the fetus from various imaging modalities facilitates appropriate choices for diagnostic imaging of pregnant patients with nonobstetric conditions. Other aspects of imaging besides radiation (ie, contrast agents) also carry potential for fetal injury and must be taken into consideration. Imaging algorithms based on a review of the current literature have been developed for specific nonobstetric conditions: pulmonary embolism, acute appendicitis, urolithiasis, biliary disease, and trauma. Imaging modalities that do not use ionizing radiation (ie, ultrasonography and magnetic resonance imaging) are preferred for pregnant patients. If ionizing radiation is used, one must adhere to the principle of using a dose that is as low as reasonably achievable after a discussion of risks versus benefits with the patient.

Facts and controversies about radiation exposure, part 2: low-level exposures and cancer risk.

In this 2-part article, the authors address the need to put in perspective the risks of radiation exposure in the rapidly changing field of radiology, considering the current state of knowledge of effects at low levels. The article is based on the content of the refresher course RC 516 presented at the Radiological Society of North America's 2005 annual meeting. In part 1, the authors presented a brief review of epidemiologic studies, a discussion of typical radiation doses experienced in medicine by both patients and professionals, and the description of practical approaches to reduce unnecessary exposures. Part 2 addresses a special concern for the unborn and discusses advisory and regulatory cancer risk estimates based mainly on epidemiologic studies. The limitations of epidemiologic studies at low-level exposures and recent new findings in radiobiology, some of which are summarized, challenge the notion that any amount of radiation causes adverse effects.