Anatomical pulmonary magnetic resonance imaging segmentation for regional structure-function measurements of asthma

PURPOSE

Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as intermediate endpoints of asthma severity and control. In particular, pulmonary (1)H MRI can be used to provide quantitative lung structure-function measurements longitudinally and in response to treatment. However, to translate such biomarkers of asthma, robust methods are required to segment the lung from pulmonary (1)H MRI. Therefore, their objective was to develop a pulmonary (1)H MRI segmentation algorithm to provide regional measurements with the precision and speed required to support clinical studies.

METHODS

The authors developed a method to segment the left and right lung from (1)H MRI acquired in 20 asthmatics including five well-controlled and 15 severe poorly controlled participants who provided written informed consent to a study protocol approved by Health Canada. Same-day spirometry and plethysmography measurements of lung function and volume were acquired as well as (1)H MRI using a whole-body radiofrequency coil and fast spoiled gradient-recalled echo sequence at a fixed lung volume (functional residual capacity + 1 l). We incorporated the left-to-right lung volume proportion prior based on the Potts model and derived a volume-proportion preserved Potts model, which was approximated through convex relaxation and further represented by a dual volume-proportion preserved max-flow model. The max-flow model led to a linear problem with convex and linear equality constraints that implicitly encoded the proportion prior. To implement the algorithm, (1)H MRI was resampled into ∼3 × 3 × 3 mm(3) isotropic voxel space. Two observers placed seeds on each lung and on the background of 20 pulmonary (1)H MR images in a randomized dataset, on five occasions, five consecutive days in a row. Segmentation accuracy was evaluated using the Dice-similarity-coefficient (DSC) of the segmented thoracic cavity with comparison to five-rounds of manual segmentation by an expert observer. The authors also evaluated the root-mean-squared-error (RMSE) of the Euclidean distance between lung surfaces, the absolute, and percent volume error. Reproducibility was measured using the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) for two observers who repeated segmentation measurements five-times.

RESULTS

For five well-controlled asthmatics, forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) was 83% ± 7% and FEV1 was 86 ± 9%pred. For 15 severe, poorly controlled asthmatics, FEV1/FV C = 66% ± 17% and FEV1 = 72 ± 27%pred. The DSC for algorithm and manual segmentation was 91% ± 3%, 92% ± 2% and 91% ± 2% for the left, right, and whole lung, respectively. RMSE was 4.0 ± 1.0 mm for each of the left, right, and whole lung. The absolute (percent) volume errors were 0.1 l (∼6%) for each of right and left lung and ∼0.2 l (∼6%) for whole lung. Intra- and inter-CoV (ICC) were <0.5% (>0.91%) for DSC and <4.5% (>0.93%) for RMSE. While segmentation required 10 s including ∼6 s for user interaction, the smallest detectable difference was 0.24 l for algorithm measurements which was similar to manual measurements.

CONCLUSIONS

This lung segmentation approach provided the necessary and sufficient precision and accuracy required for research and clinical studies.

Methods and Problems of a Stroke Rehabilitation Trial

There are conflicting views on the effectiveness of rehabilitation after stroke; several studies have attempted to compare progress following intensive therapy with that following community care1–6 or no formal treatment,7–9 but for a number of reasons the evidence is inconclusive. Consequently, we have been engaged in a randomised controlled trial of the effectiveness of different intensities of out-patient rehabilitation following stroke. This paper outlines the design, methods and problems of the study.

Experiences and meanings of integration of TCAM (Traditional, Complementary and Alternative Medical) providers in three Indian states: results from a cross-sectional, qualitative implementation research study

OBJECTIVES

Efforts to engage Traditional, Complementary and Alternative Medical (TCAM) practitioners in the public health workforce have growing relevance for India's path to universal health coverage. We used an action-centred framework to understand how policy prescriptions related to integration were being implemented in three distinct Indian states.

SETTING

Health departments and district-level primary care facilities in the states of Kerala, Meghalaya and Delhi.

PARTICIPANTS

In each state, two or three districts were chosen that represented a variation in accessibility and distribution across TCAM providers (eg, small or large proportions of local health practitioners, Homoeopaths, Ayurvedic and/or Unani practitioners). Per district, two blocks or geographical units were selected. TCAM and allopathic practitioners, administrators and representatives of the community at the district and state levels were chosen based on publicly available records from state and municipal authorities. A total of 196 interviews were carried out: 74 in Kerala, and 61 each in Delhi and Meghalaya.

PRIMARY AND SECONDARY OUTCOME MEASURES

We sought to understand experiences and meanings associated with integration across stakeholders, as well as barriers and facilitators to implementing policies related to integration of Traditional, Complementary and Alternative (TCA) providers at the systems level.

RESULTS

We found that individual and interpersonal attributes tended to facilitate integration, while system features and processes tended to hinder it. Collegiality, recognition of stature, as well as exercise of individual personal initiative among TCA practitioners and of personal experience of TCAM among allopaths enabled integration. The system, on the other hand, was characterised by the fragmentation of jurisdiction and facilities, intersystem isolation, lack of trust in and awareness of TCA systems, and inadequate infrastructure and resources for TCA service delivery.

CONCLUSIONS

State-tailored strategies that routinise interaction, reward individual and system-level individual integrative efforts, and are fostered by high-level political will are recommended.

Engineering hydrophobically modified chitosan for enhancing the dispersion of respirable microparticles of levofloxacin

The potential of amphiphilic chitosan formed by grafting octanoyl chains on the chitosan backbone for pulmonary delivery of levofloxacin has been studied. The success of polymer synthesis was confirmed using FT-IR and NMR, whilst antimicrobial activity was assessed against Pseudomonas aeruginosa. Highly dispersible dry powders for delivery as aerosols were prepared with different amounts of chitosan and octanoyl chitosan to study the effect of hydrophobic modification and varying concentration of polymer on aerosolization of drug. Powders were prepared by spray-drying from an aqueous solution containing levofloxacin and chitosan/amphiphilic octanoyl chitosan. l-leucine was also used to assess its effect on aerosolization. Following spray-drying, the resultant powders were characterized using scanning electron microscopy, laser diffraction, dynamic light scattering, HPLC, differential scanning calorimetry, thermogravimetric analysis and X-ray powder diffraction. The in vitro aerosolization profile was determined using a Next Generation Impactor, whilst in vitro antimicrobial assessment was performed using MIC assay. Microparticles of chitosan have the property of mucoadhesion leading to potential increased residence time in the pulmonary mucus, making it important to test the toxicity of these formulations. In-vitro cytotoxicity evaluation using MTT assay was performed on A549 cell line to determine the toxicity of formulations and hence feasibility of use. The MTT assay confirmed that the polymers and the formulations were non-cytotoxic. Hydrophobically modifying chitosan showed significantly lower MIC (4-fold) than the commercial chitosan against P. aeruginosa. The powders generated were of suitable aerodynamic size for inhalation having a mass median aerodynamic diameter less than 4.5μm for formulations containing octanoyl chitosan. These highly dispersible powders have minimal moisture adsorption and hence an emitted dose of more than 90% and a fine particle fraction (FPF) of 52%. Powders with non-modified chitosan showed lower dispersibility, with an emitted dose of 72% and FPF of 20%, as a result of high moisture adsorption onto the chitosan matrix leading to cohesiveness and subsequently decreased dispersibility.

Colorectal cancer detection: time to abandon barium enema?

OBJECTIVES

To assess the sensitivity of double contrast barium enema (DCBE) for diagnosing colorectal cancer (CRC).

DESIGN

Retrospective evaluation of DCBE performed in the 2 years prior to diagnosis of CRC.

SETTING

Teaching hospital in Cambridge, UK.

PATIENTS

1310 consecutive cases of CRC identified from cancer registry data.

INTERVENTIONS

DCBE and colonoscopy.

MAIN OUTCOME MEASURES

Sensitivity of DCBE for diagnosing CRC.

RESULTS

215 patients had undergone a DCBE within the 2 years prior to diagnosis with CRC. After excluding those reported as inadequate, 37 of these were reported as normal, giving a sensitivity of 83% (81-85%).

CONCLUSIONS

The performance of DCBE is inadequate for the exclusion of CRC. Expansion of colonoscopy and CT colonography capacity is urgently required nationally so that DCBE can finally be abandoned as a firstline test in patients at risk of CRC.

Undergraduate medical education in the Gulf Cooperation Council: a multi-countries study (Part 1)

BACKGROUND

The Gulf Cooperation Council (GCC) countries have witnessed over the last 40 years a rapid and major social, cultural, and economic transformation. The development of medical education in the region is relatively new, dating from the late 1960s. An important goal among the medical colleges in the region is to graduate national physicians who can populate the healthcare service of each country.

AIM

The aim of this study is to provide understanding of undergraduate medical education in each of the six GCC countries and the challenges that each face.

METHODS

This is a descriptive cross-sectional study. Fourteen senior medical faculty were requested to submit information about undergraduate medical education in their own countries, focusing on its historical background, student selection, curriculum, faculty, and challenges.

RESULTS

The information provided was about 27 medical colleges: 16 from the Kingdom of Saudi Arabia (KSA), five from the United Arab Emirates (UAE), two from the Kingdom of Bahrain, two from Sultanate of Oman, one from Kuwait, and one from the State of Qatar. It was found that older colleges are reviewing their curriculum while new colleges are developing their programs following current trends in medical education, particularly problem-based learning and integrated curricula. The programs as described 'on paper' look good but what needs to be evaluated is the curriculum 'in action'. Faculty development in medical education is taking place in most of the region's medical colleges.

CONCLUSION

The challenges reported were mainly related to shortages of faculty, availability of clinical training facilities and the need to more integration with the National Health Care services. Attention to quality, standards, and accreditation is considered essential by all colleges.

Utility of provider volume as an indicator of medical care quality and for policy decisions

Associations between hospital volume or physician caseload and patient outcome have been used to assess the performance of health care providers. Although most studies have focused on major surgical procedures, in-hospital or 30-day mortality from many nonsurgical conditions and procedures has also been examined. Although high volume may be a surrogate for the provider's skill and experience, and better outcomes may attract greater volumes, aggregate data on provider volume show many outliers indicating that the outcome for some low-volume providers is better than that for high-volume providers. Mortality is only one measure of medical care quality. Although high volume may not always be indicative of favorable outcome, referral of patients from low-volume to high-volume providers has been recommended. It has also been suggested that patients choose health care providers on the basis of physician caseload. It is unclear how such recommendations could be implemented in practice; furthermore, they would deprive many patients from access to, as well as disrupt the provision of, adequate health care in many areas. An alternative to requiring patients to receive care from high-volume providers is to adopt other measures for improving outcomes, such as improving the quality of care provided by low-volume providers and attracting better providers to low-volume areas.

Urban-rural differences in the quality of care for medicare patients with acute myocardial infarction

BACKGROUND

There are urban-rural differences in health care utilization in Kansas. This study was conducted to determine if similar differences exist in the quality of inpatient care provided for patients with acute myocardial infarction (AMI).

METHODS

All acute care hospitals in the state were stratified into 12 urban, 31 semirural, and 76 rural hospitals according to their location. Data from medical records of 2521 Medicare patients 65 years and older who had survived AMI and were discharged alive from hospitals during an 8-month period in 1994/1995 were abstracted. The measures of the quality of care (quality indicators [QIs]) were the use of aspirin (during hospital stay and at discharge) and the administration of beta-blockers, intravenous (IV) nitroglycerin, heparin, and reperfusion by thrombolytic therapy or primary angioplasty.

RESULTS

A significantly higher proportion of ideal candidates for the use of aspirin during hospital stay and at discharge, heparin, and IV nitroglycerin received these medications in urban hospitals, and a lower proportion of similar patients received these medications in rural hospitals compared with the patients in semirural hospitals (P<.001). Similar trends in each of the 6 QIs were observed for less than ideal patients (P<.05). Patient age was associated with a relatively poor quality of care in terms of the 6 QIs. Except for the administration of IV nitroglycerine to less than ideal patients, age adjustments did not change the observed urban-rural differences in the QI measures.

CONCLUSION

Relatively poor quality of care for patients with AMI was provided by rural hospitals where greater opportunity for improvement exists.