Pulmonary TB bacteriologically confirmed by induced sputum among children at Bugando Medical Centre, Tanzania.

BACKGROUND: The diagnosis of paediatric tuberculosis (TB) remains difficult in resource-: poor settings. OBJECTIVE: To evaluate induced sputum collection and examination using microscopy, culture and Xpert(®) MTB/RIF assay for the diagnosis of pulmonary TB (PTB) in a Tanzanian hospital vs. PTB diagnosis using clinical scoring tools alone. METHODS: We conducted a cross-sectional study from October 2013 to April 2014 at our hospital in northwestern Tanzania. Children presumed to have TB were assessed using four TB score charts and sputum examination. Sputum samples were analyzed using fluorescence microscopy, solid culture and Xpert. The number of cases microbiologically confirmed was compared to the number of TB cases suspected based on TB score charts. RESULTS: A total of 192 patients were enrolled. Sputum specimens were successfully obtained in 187 (97.4%) patients without any major complications. Ten (5.2%) children were confirmed to have PTB by sputum examination. More than half (50-90%) of the confirmed cases were not detected by score charts alone. CONCLUSION: Sputum induction is both safe and feasible in a severely resource-limited hospital, and can lead to microbiological PTB diagnosis that would not be detected by clinical criteria alone.

Screening for pulmonary tuberculosis in a Tanzanian prison and computer-aided interpretation of chest X-rays.

SETTING: Tanzania is a high-burden country for tuberculosis (TB), and prisoners are a high-risk group that should be screened actively, as recommended by the World Health Organization. Screening algorithms, starting with chest X-rays (CXRs), can detect asymptomatic cases, but depend on experienced readers, who are scarce in the penitentiary setting. Recent studies with patients seeking health care for TB-related symptoms showed good diagnostic performance of the computer software CAD4TB. OBJECTIVE: To assess the potential of computer-assisted screening using CAD4TB in a predominantly asymptomatic prison population. DESIGN: Cross-sectional study. RESULTS: CAD4TB and seven health care professionals reading CXRs in local tuberculosis wards evaluated a set of 511 CXRs from the Ukonga prison in Dar es Salaam. Performance was compared using a radiological reference. Two readers performed significantly better than CAD4TB, three were comparable, and two performed significantly worse (area under the curve 0.75 in receiver operating characteristics analysis). On a superset of 1321 CXRs, CAD4TB successfully interpreted >99%, with a predictably short time to detection, while 160 (12.2%) reports were delayed by over 24 h with conventional CXR reading. CONCLUSION: CAD4TB reliably evaluates CXRs from a mostly asymptomatic prison population, with a diagnostic performance inferior to that of expert readers but comparable to local readers.

Contexte : La Tanzanie est lourdement frappée par la tuberculose (TB) et les prisonniers sont un groupe à haut risque qui devrait bénéficier d'un dépistage actif, comme le recommande l'Organisation Mondiale de la Santé. Les algorithmes de dépistage qui débutent par une radiographie pulmonaire peuvent détecter des cas asymptomatiques, mais ils requièrent des lecteurs de radiographies expérimentés, qui sont rares dans le contexte pénitentiaire. Des études récentes sur des patients sollicitant des soins pour des symptômes liés à la TB ont mis en évidence une bonne performance diagnostique du logiciel CAD4TB.Objectif : Evaluer le potentiel d'un dépistage assisté par ordinateur en utilisant CAD4TB au sein d'une population carcérale en majorité asymptomatique.Schéma : Étude transversale.Résultats : CAD4TB et sept professionnels de santé lisant des radiographies dans des services de TB locaux ont évalué un ensemble de 511 radiographies pulmonaires provenant de la prison d'Ukonga à Dar es Salaam et les performances ont été comparées grâce à une radiographie de référence. Deux lecteurs ont été significativement plus performants que CAD4TB, trois ont été comparables et deux ont été significativement moins bons (zone sous la courbe de 0,75 dans l'analyse ROC ­fonction d'efficacité du receveur). Sur un ensemble de 1321 radiographies pulmonaires, CAD4TB en a interprété avec succès plus de 99% avec un délai de détection prévisible court, tandis que 160 (12,2%) réponses ont été retardées de plus de 24 h avec la méthode de lecture conventionnelle.Conclusion : CAD4TB évalue de manière fiable les radiographies pulmonaires dans une population en majorité asymptomatique de détenus, avec une performance diagnostique inférieure à celle de lecteurs experts mais comparable à celle des lecteurs locaux.

Marco de referencia: Tanzania es un país con una alta tasa de morbilidad por tuberculosis (TB) y las personas en los establecimientos penitenciarios constituyen un grupo de alto riesgo de contraer la enfermedad; en esta población se debe practicar la detección sistemática activa como lo recomienda la Organización Mundial de la Salud. Los algoritmos de detección cuya etapa inicial es la radiografía de tórax pueden detectar los casos asintomáticos, pero su eficacia depende de la experiencia del profesional que interpreta las imágenes y esta competencia es escasa en los entornos penitenciarios. Algunos estudios recientes de pacientes que buscan atención sanitaria por síntomas asociados con la TB han revelado un buen rendimiento diagnóstico con la utilización del programa informático CAD4TB. Objetivo: Evaluar la utilidad de la detección sistemática de la TB asistida por el programa CAD4TB, en una población penitenciaria en su mayoría asintomática.Método: Fue este un estudio de tipo transversal.Resultados: Siete profesionales de atención sanitaria de los servicios locales de TB analizaron 511 radiografías de tórax provenientes de la prisión de Ukonga, en Dar es-Salam, con la ayuda del programa CAD4TB; se preparó un conjunto de referencia radiográfica de lectura con el fin de evaluar el rendimiento diagnóstico. El desempeño de dos de los lectores fue significativamente superior al resultado del programa CAD4TB, tres lectores obtuvieron una puntuación comparable al programa y en dos lectores se observó un rendimiento significativamente inferior (área bajo la curva: 0,75 en el análisis de eficacia diagnóstica). En un conjunto especial de 1321 radiografías de tórax el programa CAD4TB interpretó eficazmente más del 99%, con un corto lapso previsible hasta la detección, en contraste con la lectura clásica de las radiografías que dio lugar a un retraso superior a 24 horas en 160 informes (12,2%).Conclusión: El programa CAD4TB realizó una evaluación fiable de las radiografías provenientes de una población penitenciaria en su mayor parte asintomática. El rendimiento diagnóstico del programa fue inferior al rendimiento de los lectores expertos, pero comparable con el rendimiento de los lectores locales.

An experimental evaluation of the Agility MLC for motion-compensated VMAT delivery.

An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) for use in motion-compensated VMAT delivery. For five VMAT patients, dosimetric measurements were performed using the Delta(4) radiation detector (ScandiDos, Uppsala, Sweden) and the accuracy of dMLC tracking was evaluated using a gamma-analysis, with threshold levels of 3% for dose and 3 mm for distance-to-agreement. For a motion trajectory with components in two orthogonal directions, the mean gamma-analysis pass rate without tracking was found to be 58.0%, 59.0% and 60.9% and was increased to 89.1%, 88.3% and 93.1% with MLC tracking, for time periods of motion of 4 s, 6 s and 10 s respectively. Simulations were performed to compare the efficiency of the Agility MLC with the MLCi MLC when used for motion-compensated VMAT delivery for the same treatment plans and motion trajectories. Delivery time increases from a static-tumour to dMLC-tracking VMAT delivery were observed in the range 0%­20% for the Agility, and 0%­57% with the MLCi, indicating that the increased leaf speed of the Agility MLC is beneficial for MLC tracking during lung radiotherapy.

An experimental comparison of conventional two-bank and novel four-bank dynamic MLC tracking.

The AccuLeaf mMLC featuring four multileaf-collimator (MLC) banks has been used for the first time for an experimental comparison of conventional two-bank with novel four-bank dynamic MLC tracking of a two-dimensional sinusoidal respiratory motion. This comparison was performed for a square aperture, and for three conformal treatment apertures from clinical radiotherapy lung cancer patients. The system latency of this prototype tracking system was evaluated and found to be 1.0 s and the frequency at which MLC positions could be updated, 1 Hz, and therefore accurate MLC tracking of irregular patient motion would be difficult with the system in its current form. The MLC leaf velocity required for two-bank-MLC and four-bank-MLC tracking was evaluated for the apertures studied and a substantial decrease was found in the maximum MLC velocity required when four-banks were used for tracking rather than two. A dosimetric comparison of the two techniques was also performed and minimal difference was found between two-bank-MLC and four-bank-MLC tracking. The use of four MLC banks for dynamic MLC tracking is shown to be potentially advantageous for increasing the delivery efficiency compared with two-bank-MLC tracking where difficulties are encountered if large leaf shifts are required to track motion perpendicular to the direction of leaf travel.

Performance of the Xpert® MTB/RIF assay in an active case-finding strategy: a pilot study from Tanzania.

In this pilot study, we evaluated the Xpert® MTB/RIF assay in an active case-finding strategy, using two spot sputum samples collected within a 1-hour interval from household contacts of smear-positive TB index cases. Tuberculosis (TB) confirmed by culture served as the reference standard. Among 219 enrolled contacts, the yield of active TB was 2.3%. While the sensitivity of smear microscopy was 60% (95%CI 14.7-94.7), Xpert MTB/RIF achieved a sensitivity of 100% (95%CI 47.81-100.0). All culture-confirmed cases tested positive by Xpert MTB/RIF on the first submitted sample, suggesting that the evaluation of only one sample could be sufficient for TB diagnosis in this context.

Time for abstention from caffeine before an adenosine myocardial perfusion scan.

Seventy patients undergoing adenosine myocardial perfusion scintigraphy were studied. All patients reported abstention from products containing caffeine in the 12 h prior to the test. Blood samples were drawn prior to initiation of the stress test, and serum caffeine levels were determined using high-performance liquid chromatography. All patients were also asked about their coffee and tea drinking habits. Seventy-four percent of patients had measurable serum caffeine levels (n = 52) ranging from 0.1 to 8.8 mg.l-1. Results were correlated with maximum pulse rate, systolic and diastolic blood pressure changes and clinical symptoms during the test. There was no correlation between coffee or tea drinking habits and serum caffeine levels. A serum caffeine level of 2.9 mg.l-1 was considered a cut-off point for comparing patients. No significant difference was seen in mean maximum change of pulse rate, systolic and diastolic blood pressure between patients with serum caffeine levels > or = 2.9 mg.l-1 and those with lower serum caffeine levels. Of eight patients with serum caffeine levels > or = 2.9 mg.l-1, six had no symptoms (75%). When patients were classified as patients with no symptoms or patients with symptoms (mild, moderate or severe), a significant difference was demonstrated between patients with serum caffeine levels > or = 2.9 mg.l-1 and those with lower levels. This suggests 12 h abstention from caffeine may be insufficient. Whether this translates into false-negative perfusion scans should be the subject of a larger study.