[Guidelines in medical imaging : objectives, limits and radiation protection]. / Recommandations en imagerie médicale : objectifs, limites et radioprotection.

CONTEXT: Guidelines in medical imaging are aimed at increasing the appropriateness of prescriptions, eliminating unnecessary examina- tions, reducing the exposure of the population and minimizing the costs to public health. METHOD: Our analysis is based on a bibliographic search and the discussions of the " quality " working group of the BELMIP platform. RESULTS: The introduction in 2004 and its 2014 revision of the guideliness in medical imaging in Belgium had no measurable effect on the imaging prescription. These recommendations are in fact unrecognized, incomplete, poorly constructed and often unusable. CONCLUSION: Recommendations in medical imaging need to be reviewed and will be reviewed in the near future in order to be better structured and usable. The legal and medico-legal constraints should be integrated in order for Belgium to comply with the relevant European directive.

Contexte : Les recommandations en imagerie médicale visent à augmenter la pertinence des prescriptions, éliminer les examens inutiles, réduire l'irradiation de la population et minimiser les coûts pour la santé publique. Méthode : Notre analyse se base sur une recherche bibliographique et sur les discussions du groupe de travail " qualité " de la plateforme BELMIP. Résultats : L'introduction en 2004 et sa révision en 2014 des recommandations en imagerie médicale en Belgique n'a pas eu d'effet mesurable sur la prescription d'imagerie. Ces recommandations sont en effet méconnues, incomplètes, mal construites et souvent inutilisables. CONCLUSION: Les recommandations en imagerie médicale doivent être revues et le seront dans un avenir proche afin d'être mieux structurées et utilisables. Les contraintes légales et médico- légales devraient y être intégrées afin que la Belgique se mette en conformité par rapport à la directive européenne concernée.

Community survey of rabies knowledge and exposure to bats in homes - Sumter County, South Carolina, USA.

Subsequent to a human rabies death in Sumter County, South Carolina, we assessed the frequency of exposures to bats in homes and citizens' rabies knowledge. A self-administered survey was mailed to 6033 randomly selected Sumter County addresses. The survey inquired about household exposures to bats and respondents' rabies knowledge. Surveys were returned by mail for descriptive analysis. Of 597 respondents, 3.5% (21/597) reported having bats living in (2.8% or 17/597) or entering their homes (2.5% or 15/597) during 2010-2012. Respondents generally understood that mammals transmit rabies virus through bites, but were less aware of the severity of rabies illness and modern post-exposure vaccine administration. Respondents were unsure about how to exclude bats from homes and ranked highly both healthcare and non-healthcare entities as preferred resources for obtaining assistance with bat-related concerns. We found potential for human exposures to bats in Sumter County households and gaps in citizen knowledge of rabies and bat exclusion. Public health officials should engage non-healthcare partners in assistance disseminating rabies educational materials and for providing appropriate referral for persons potentially exposed to bats.

Tuning of automatic exposure control strength in lumbar spine CT.

OBJECTIVE: To investigate the impact of tuning the automatic exposure control (AEC) strength curve (specific to Care Dose 4D®; Siemens Healthcare, Forchheim, Germany) from "average" to "strong" on image quality, radiation dose and operator dependency during lumbar spine CT examinations. METHODS: Two hospitals (H1, H2), both using the same scanners, were considered for two time periods (P1 and P2). During P1, the AEC curve was "average" and radiographers had to select one of two protocols according to the body mass index (BMI): "standard" if BMI <30.0 kg m(-2) (120 kV-330 mAs) or "large" if BMI >30.0 kg m(-2) (140 kV-280 mAs). During P2, the AEC curve was changed to "strong", and all acquisitions were obtained with one protocol (120 kV and 270 mAs). Image quality was scored and patients' diameters calculated for both periods. RESULTS: 497 examinations were analysed. There was no significant difference in mean diameters according to hospitals and periods (p > 0.801) and in quality scores between periods (p > 0.172). There was a significant difference between hospitals regarding how often the "large" protocol was assigned [13 (10%)/132 patients in H1 vs 37 (28%)/133 in H2] (p < 0.001). During P1, volume CT dose index (CTDIvol) was higher in H2 (+13%; p = 0.050). In both hospitals, CTDIvol was reduced between periods (-19.2% in H1 and -29.4% in H2; p < 0.001). CONCLUSION: An operator dependency in protocol selection, unexplained by patient diameters or highlighted by image quality scores, has been observed. Tuning the AEC curve from average to strong enables suppression of the operator dependency in protocol selection and related dose increase, while preserving image quality. ADVANCES IN KNOWLEDGE: CT acquisition protocols based on weight are responsible for biases in protocol selection. Using an appropriate AEC strength curve reduces the number of protocols to one. Operator dependency of protocol selection is thereby eliminated.

Reduced z-axis coverage in multidetector-row CT pulmonary angiography decreases radiation dose and diagnostic accuracy of alternative diseases.

OBJECTIVE: To investigate the effect of a two-third reduction of the scanned length (i.e. 10 cm) on diagnosis of both pulmonary embolism (PE) and alternative diseases. METHODS: 247 consecutive patients suspected of acute PE had a CT pulmonary angiography (CTPA) of the thorax (standard length, L). Based on this acquisition, a second set of images was created to obtain a scan length of 10 cm caudally to the aortic arch (l). Images were anonymized, randomized and interpreted by two independent readers. The quality of enhancement, the presence of PE and the possible alternative and/or complementary diagnoses were recorded. A McNemar exact test investigated differences in discrepancies between readers and between scan lengths. RESULTS: 57 (23%) patients had an acute PE. Among l sets, PE was missed by both readers in one (1.8%) patient, because the unique clot was localized in a subsegmental artery out of the 10-cm range. There were discrepancies between L and l sets in 9 (3.6%) and 11 (4.5%) patients, by Readers 1 and 2 (p=0.820), respectively. Discrepancies between the readers of L sets and those between both sets were not different regardless of the reader (p>0.99). There were discrepancies between both sets for alternative and/or complementary diagnoses in 43 (17.2%) patients. CONCLUSION: Although its performance in diagnosing PE is maintained, CTPA should not be restricted to a range of 10 cm centred over the pulmonary hilum, because alternative and/or complementary diagnoses could be missed. ADVANCES IN KNOWLEDGE: (1) A 10-cm CTPA acquisition reduces the radiation dose by two-thirds as compared with a standard one, but does not impair the accuracy for the diagnosis of PE. (2) Significant alternative diagnoses are missed in 17.2% of patients when reducing the acquisition height to 10 cm.

Prevention and control of rabies in an age of global travel: a review of travel- and trade-associated rabies events--United States, 1986-2012.

Rabies prevention and control efforts have been successful in reducing or eliminating virus circulation regionally through vaccination of specific reservoir populations. A notable example of this success is the elimination of canine rabies virus variant from the United States and many other countries. However, increased international travel and trade can pose risks for rapid, long-distance movements of ill or infected persons or animals. Such travel and trade can result in human exposures to rabies virus during travel or transit and could contribute to the re-introduction of canine rabies variant or transmission of other viral variants among animal host populations. We present a review of travel- and trade-associated rabies events that highlight international public health obligations and collaborative opportunities for rabies prevention and control in an age of global travel. Rabies is a fatal disease that warrants proactive coordination among international public health and travel industry partners (such as travel agents, tour companies and airlines) to protect human lives and to prevent the movement of viral variants among host populations.

Dosimetry: which dose for screening, diagnosis and follow-up?

The question of which dose for screening, diagnosing ad follow-up of pulmonary nodules is a permanent issue for radiologists and radiotherapists. The proposed dose values for 2013 reflect the possibilities of the latest CT generations, from 2010 or later and include all technical novelties such as iterative reconstructions, automatic tube potential selection, and latest detectors. As the technology is constantly evolving, these parameters are susceptible to lower every year.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis.

OBJECTIVE: To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT. METHODS: This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used. RESULTS: 46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M. CONCLUSION: Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis. ADVANCES IN KNOWLEDGE: In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.

Automatic computed tomography patient dose calculation using DICOM header metadata.

The present work describes a method that calculates the patient dose values in computed tomography (CT) based on metadata contained in DICOM images in support of patient dose studies. The DICOM metadata is preprocessed to extract necessary calculation parameters. Vendor-specific DICOM header information is harmonized using vendor translation tables and unavailable DICOM tags can be completed with a graphical user interface. CT-Expo, an MS Excel application for calculating the radiation dose, is used to calculate the patient doses. All relevant data and calculation results are stored for further analysis in a relational database. Final results are compiled by utilizing data mining tools. This solution was successfully used for the 2009 CT dose study in Luxembourg. National diagnostic reference levels for standard examinations were calculated based on each of the countries' hospitals. The benefits using this new automatic system saved time as well as resources during the data acquisition and the evaluation when compared with earlier questionnaire-based surveys.

Radiation dose optimization in thoracic imaging.

Guidelines for reduction of CT radiation dose were introduced in 1997 and are now more than 12 years old. The process initiated by the European Regulatory authorities to reduce the excess of radiation from CT has however not produced the expected results. Reference diagnostic levels (DRL) from surveys are still twice as high as needed in most European countries and were not significantly reduced as compared to the initial European ones. Many factors may at least explain partially the lack of dose reduction. One of them is the complexity of the dose optimization process while maintaining image quality at a diagnostically acceptable level. Chest is an anatomical region where radiation dose could be substantially reduced because of high natural contrasts between structures, such as air in the lungs and fat in the mediastinum. In this article, the concept of CT radiation dose optimization and the factors that contribute to maintain global excess in radiation dose are reviewed and a brief summary of results from research in the field of chest CT radiation dose is given.

[Pain: thought about risks and benefits of imaging test in primary care]. / Imagerie de la douleur en soins primaires: réflexions à propos des risques et bénéfices.

In 2007, the budget of medical imaging in Belgium was of more than 920,000,000 Euro. A small part of this amount is attributed to prescription by general practitioners. The yearly costs of medical imaging generated by an individual general practitioner is approximately of 12,000 Euro. Pain is one of the most frequent clinical condition for which imaging tests are requested. The effectiveness of imaging in diagnosing acute painful disorders is well established. However, in case of subacute or chronic pain, the benefits of imaging tests are reduced or not clearly defined. The objective of this review is to highlight the balance between benefit, costs and risks (i.e. radiation risk) of imaging tests in case of acute, subacute and chronic pain. Four of the most frequently encountered clinical conditions illustrate this review.

Role of Smad3 in the regulation of rat telomerase reverse transcriptase by TGFbeta.

Telomerase is induced in certain pathological conditions such as cancer and tissue injury and repair. This induction in fibroblasts from injured lung is repressed by transforming growth factor beta (TGFbeta) via yet unknown mechanisms. In this study, the role of Smad3 in the inhibition of telomerase reverse transcriptase (TERT) gene transcription by TGFbeta was investigated. The rat TERT (rTERT) gene promoter was cloned by PCR amplification and fused with a luciferase reporter gene. This construct was used to analyse regulation of promoter activity in fibroblasts isolated from bleomycin-injured lung with induced telomerase activity. The results showed that TGFbeta inhibited rTERT transcription while stimulating Smad3 expression. Interestingly, TGFbeta also inhibited the expression of c-myc. Cotransfection with a Smad3 expressing plasmid further repressed rTERT transcription and c-myc expression, while cotransfection with the corresponding antisense Smad3 construct had the opposite effect. Mutation of an E-box in the rTERT promoter suppressed its activity, which could be further reduced by TGFbeta treatment. In contrast, mutation at a Smad binding element enhanced promoter activity whose inhibition was impaired by TGFbeta treatment. Thus TGFbeta inhibition of rTERT gene expression was directly mediated by Smad3 via the Smad binding element, while c-myc appears to primarily regulate its constitutive or induced expression.

Radiation dose in computed tomography of the chest.

Since the beginning of the eighties, computed tomography (CT) has been more and more widely used as this technique provides precise anatomical details on the lungs, the mediastinum, and the chest wall. However, CT requires the use of ionizing radiations. The collective radiation from CT is therefore in constant increase. As evaluated on atomic bomb survivors, ionizing radiations increase the mortality by cancer. The risk is proportional to the dose and the dose related to CT is much higher than that related to a chest radiograph, both being in the field "of low-level radiations" a range of radiation dose from which no increase in cancer mortality could be demonstrated. This article outlines the risk estimation in the field of low-level radiations, the various methods to measure and estimate the radiation dose, the CT parameters influencing the radiation dose, dose comparisons between CT and most other imaging techniques of the chest, the newly developed so called "Low-Dose" CT techniques and highlights some of the unresolved questions related to radiation dose in clinical CT practice.

Cholecystoduodenal fistula in a porcelain gallbladder.

Calcification of the gallbladder wall (porcelain gallbladder) is rare. Its appearance is quite characteristic on plain films, ultrasonography and computed tomography. Sporadic cases of cholecystitis have been described in porcelain gallbladders. Enterobiliary fistula may complicate acute or chronic cholecystitis in non-calcified gallbladder. We report a unusual case of acute cholecystitis with cholecystoduodenal fistula in a porcelain gallbladder.