Myocardial perfusion SPECT reconstruction: Receiver operating characteristic comparison of CAD detection accuracy of filtered backprojection reconstruction with all of the clinical imaging information available to readers and solely stress slices iteratively reconstructed with combined compensation

BACKGROUND: Past receiver operating characteristic (ROC) studies have demonstrated that single photon emission computed tomography (SPECT) perfusion imaging by use of iterative reconstruction with combined compensation for attenuation, scatter, and detector response leads to higher area under the ROC curve (A(z)) values for detection of coronary artery disease (CAD) in comparison to the use of filtered backprojection (FBP) with no compensations. A new ROC study was conducted to investigate whether this improvement still holds for iterative reconstruction when observers have available all of the imaging information normally presented to clinical interpreters when reading FBP SPECT perfusion slices. METHODS AND RESULTS: A total of 87 patient studies including 50 patients referred for angiography and 37 patients with a lower than 5% likelihood for CAD were included in the ROC study. The images from the two methods were read by 4 cardiology fellows and 3 attending nuclear cardiologists. Presented for the FBP readings were the short-axis, horizontal long-axis, and vertical long-axis slices for both the stress and rest images; cine images of both the stress and rest projection data; cine images of selected cardiac-gated slices; the CEQUAL-generated stress and rest polar maps; and an indication of patient gender. This was compared with reading solely the iterative reconstructed stress slices with combined compensation for attenuation, scatter, and resolution. With A(z) as the criterion, a 2-way analysis of variance showed a significant improvement in detection accuracy for CAD for the 7 observers (P = .018) for iterative reconstruction with combined compensation (A(z) of 0.895 +/- 0.016) over FBP even with the additional imaging information provided to the observers when scoring the FBP slices (A(z) of 0.869 +/- 0.030). When the groups of 3 attending physicians or 4 cardiology fellows were compared separately, the iterative technique was not statistically significantly better; however, the A(z) for each of the 7 observers individually was larger for iterative reconstruction than for FBP. Compared with results from our previous studies, the additional imaging information did increase the diagnostic accuracy of FBP for CAD but not enough to undo the statistically significantly higher diagnostic accuracy of iterative reconstruction with combined compensation. CONCLUSIONS: We have determined through an ROC investigation that included two classes of observers (experienced attending physicians and cardiology fellows in training) that iterative reconstruction with combined compensation provides statistically significantly better detection accuracy (larger A(z)) for CAD than FBP reconstructions even when the FBP studies were read with all of the extra clinical nuclear imaging information normally available.     

Systolic hypertension in the elderly. Relationship with cardiovascular disease

The risk of stroke and myocardial infarction is increased in patients with elevated systolic blood pressure. Although treatment trials have demonstrated the benefit of antihypertensive therapy in elderly patients with diastolic hypertension, the only trial conducted in elderly patients with isolated systolic hypertension is currently in progress. A six-month trial of nonpharmacologic therapy should generally be the initial treatment in patients with isolated systolic hypertension. Then, if systolic pressure remains elevated, a cautious trial of drug treatment is reasonable. The drug used should be started in a low dose, and the dose should be titrated slowly. With this approach, antihypertensive treatment of elderly patients with isolated systolic hypertension may be well tolerated and ultimately beneficial.     

When the right to be counted doesn’t count: The politics and challenges of researching the health of asylum seekers

A fundamental prerequisite of population health research is the ability to establish an accurate denominator. This in turn requires that every individual in the study population is counted. However, this seemingly simple principle has become a point of conflict between researchers whose aim is to produce evidence of disparities in population health outcomes and governments whose policies promote (intentionally or not) inequalities that are the underlying causes of health disparities. Research into the health of asylum seekers is a case in point. There is a growing body of evidence documenting the adverse affects of recent changes in asylum-seeking legislation, including mandatory detention. However, much of this evidence has been dismissed by some governments as being unsound, biased and unscientific because, it is argued, evidence is derived from small samples or from case studies. Yet, it is the policies of governments that are the key barrier to the conduct of rigorous population health research on asylum seekers. In this paper, the authors discuss the challenges of counting asylum seekers and the limitations of data reported in some industrialized countries. They argue that the lack of accurate statistical data on asylum seekers has been an effective neo-conservative strategy for erasing the health inequalities in this vulnerable population, indeed a strategy that renders invisible this population. They describe some alternative strategies that may be used by researchers to obtain denominator data on hard-to-reach populations such as asylum seekers.     

A rational approach to recurrent carotid stenosis

To further characterize the incidence and morbidity of recurrent carotid stenosis, we reviewed 184 consecutive carotid endarterectomies performed in a university hospital between August 1983 and January 1988, in patients followed after operation with serial duplex ultrasonography. Recurrent stenosis of greater than 50% diameter reduction developed in eleven arteries (6.0%) at a mean interval of 10.2 +/- 7.8 months. Three of the eleven (1.6% of the total) had associated transient ischemic attack, and none had strokes. Restenosis was significantly more frequent in diabetic patients than in nondiabetic patients (13.3% vs 4.5%; p less than 0.05); and among patients whose primary stenoses had been symptomatic compared to asymptomatic (11.0% vs 1.5%; p less than 0.02). No statistically significant association with restenosis could be established for gender, hypertension, or smoking. Completion angiography and/or Doppler spectral analysis had been performed, and results were normal at the primary operation in 10 of the 11 patients. Only six of 184 arteries (3.3%) had vein patch closure, but none of these restenosed. Uneventful reoperation with patch closure was performed in three patients with transient ischemic attacks and two with preocclusive restenoses. Lesions were myointimal hyperplasia in four and atheroma in one. Three of the unoperated restenoses have shown regression on duplex scanning, but a fourth progressed to asymptomatic occlusion. Carotid restenosis is uncommon, even without routine use of vein patch angioplasty. Reoperation should be reserved for patients with associated symptoms or greater than 80% restenosis.     

The simultaneous occurrence of renal artery stenosis and an aldosteronoma in a patient with hypertension

The simultaneous occurrence of renovascular hypertension and an adrenocortical adenoma is a rare entity. The case of a 64-year-old woman who underwent an aortorenal bypass graft for renovascular hypertension requiring a multidrug antihypertensive regimen is presented. Persistently elevated blood pressures in the postoperative period prompted further workup for other causes of hypertension. Laboratory evaluation showed hyperaldosteronism and hyporeninemia despite enalapril administration. Abdominal computerized tomography (CT) revealed a left adrenal mass which, on surgical removal, was found to be a cortical adenoma. Subsequently, her antihypertensive therapy has been reduced to a single agent. Previous authors have described only four patients with malignant hypertension who had the rare clinical combination of renal artery stenosis and an aldosteronoma. This case reemphasizes the critical need for a thorough search for other surgically correctable lesions in those patients who remain severely hypertensive after the "definitive" operation.     

Prevalence of transmitted HIV-1 drug resistance and the role of resistance algorithms: data from seroconverters in the CASCADE collaboration from 1987 to 2003

OBJECTIVES: To examine factors influencing the rate of transmitted drug resistance (TDR) among seroconverters, with particular emphasis on 3 widely used genotypic drug resistance algorithms. METHODS: The study used data from CASCADE (Concerted Action on Seroconversion to AIDS and Death in Europe), a collaboration of seroconverter cohorts in Europe and Canada. Genotypic resistance data were derived within 18 months of the last seronegative test or date of laboratory evidence of acute infection and before the initiation of antiretroviral therapy. The Stanford algorithm was used to analyze each individual's nucleotide sequence. A multivariate logistic model was used to assess independent relationships between the presence of TDR and exposure category, sex, age at seroconversion, and year of seroconversion. The paper also describes 3 alternative definitions of resistance: the Stanford algorithm, the key resistance mutations defined by the International AIDS Society, and the Agence Nationale de Recherches sur le Sida (ANRS) algorithm. RESULTS: Forty-five of 438 patients (10.3%) seroconverting between 1987 and 2003 were infected with a drug-resistant HIV-1 variant. Forty patients (9.1%) showed resistance mutations to only 1 class of antiretroviral drugs, 2 (0.5%) to 2 classes, and 3 (0.7%) to 3 classes of antiretroviral therapy. It was suggested that individuals seroconverting later in calendar time were more likely to have TDR (relative risk 3.89 and 95% CI: 0.84 to 18.02, and relative risk 4.69 and 95% CI: 1.03 to 21.31, for 1996-1999 and 2000-2003, respectively, compared with pre-1996; P trend = 0.08). This trend was apparent regardless of the definition of TDR used. The total estimated proportion of individuals with TDR varied between 10.3% and 15.5% according to which definition was used. CONCLUSIONS: Evidence was found for the rise of TDR over time. A specific definition of what constitutes TDR rather than a simple list of mutations is needed.     

Mediation of in vivo glucose sensor inflammatory response via nitric oxide release

In vivo glucose sensor nitric oxide (NO) release is a means of mediating the inflammatory response that may cause sensor/tissue interactions and degraded sensor performance. The NO release (NOr) sensors were prepared by doping the outer polymeric membrane coating of previously reported needle-type electrochemical sensors with suitable lipophilic diazeniumdiolate species. The Clarke error grid correlation of sensor glycemia estimates versus blood glucose measured in Sprague-Dawley rats yielded 99.7% of the points for NOr sensors and 96.3% of points for the control within zones A and B (clinically acceptable) on Day 1, with a similar correlation for Day 3. Histological examination of the implant site demonstrated that the inflammatory response was significantly decreased for 100% of the NOr sensors at 24 h. The NOr sensors also showed a reduced run-in time of minutes versus hours for control sensors. NO evolution does increase protein nitration in tissue surrounding the sensor, which may be linked to the suppression of inflammation. This study further emphasizes the importance of NO as an electroactive species that can potentially interfere with glucose (peroxide) detection. The NOr sensor offers a viable option for in vivo glucose sensor development.     

Risk factors for Clostridium difficile-associated diarrhea on an adult hematology-oncology ward

Nosocomial diarrhea caused by Clostridium difficile causes significant morbidity and mortality in an increasing proportion of hospitalized patients annually. This case-control study of patients admitted to the hematology-oncology ward of a tertiary academic medical center over a 2-year period demonstrates that patients with Clostridium difficile-associated diarrhea (CDAD) were 22 times more likely than ward-matched controls with diarrhea to have received any antibiotic either during hospitalization or in the month preceding admission (p < 0.005), and they were nearly three times as likely as controls to have received a cephalosporin during the same period (p < 0.005). Diarrhea among lung cancer patients was approximately three times more likely to be caused by this organism than to be due to other causes (p = 0.04). A trend towards CDAD patients receiving higher numbers of different antibiotics during hospitalization (3.3 vs. 2.6, 95%CI −1.42–0.02, p = 0.06) was noted. Administration of interleukin-2 either during hospitalization or in the 30 days preceding admission was seven times more likely to have occurred in CDAD cases (p = 0.04), raising the question of whether or not this agent increases risk.