Quantitative evaluation of ischemic myocardial scar tissue by unenhanced T1 mapping using 3.0 Tesla MR scanner

PURPOSE

We aimed to use a noninvasive method for quantifying T1 values of chronic myocardial infarction scar by cardiac magnetic resonance imaging (MRI), and determine its diagnostic performance.

MATERIALS AND METHODS

We performed cardiac MRI on 29 consecutive patients with known coronary artery disease (CAD) on 3.0 Tesla MRI scanner. An unenhanced T1 mapping technique was used to calculate T1 relaxation time of myocardial scar tissue, and its diagnostic performance was evaluated. Chronic scar tissue was identified by delayed contrast-enhancement (DE) MRI and T2-weighted images. Sensitivity, specificity, and accuracy values were calculated for T1 mapping using DE images as the gold standard.

RESULTS

Four hundred and forty-two segments were analyzed in 26 patients. While myocardial chronic scar was demonstrated in 45 segments on DE images, T1 mapping MRI showed a chronic scar area in 54 segments. T1 relaxation time was higher in chronic scar tissue, compared with remote areas (1314±98 ms vs. 1099±90 ms, P < 0.001). Therefore, increased T1 values were shown in areas of myocardium colocalized with areas of DE and normal signal on T2-weighted images. There was a significant correlation between T1 mapping and DE images in evaluation of myocardial wall injury extent (P < 0.05). We calculated sensitivity, specificity, and accuracy as 95.5%, 97%, and 96%, respectively.

CONCLUSION

The results of the present study reveal that T1 mapping MRI combined with T2-weighted images might be a feasible imaging modality for detecting chronic myocardial infarction scar tissue.In ischemic cardiac diseases, differentiating viable from nonviable myocardial tissue is important for clinical decision-making (1). The viable myocardium with decreased blood-flow such as hibernating or stunned myocardium will recover function following coronary revascularization, whereas during the chronic stage of infarction, a dense fibrotic scar replaces the infracted myocardium and this scar tissue will not recover function (2). Sometimes more aggressive treatment is needed to improve blood flow such as angioplasty, stenting, and coronary artery bypass surgery. Therefore, evaluation of viability is critical for myocardium.Positron-emission-tomography, single-photon-emission computed tomography and dobutamine echocardiography are noninvasive techniques for assessing myocardial viability. Although these techniques have proven use in clinical practice, there are several limitations that may reduce their diagnostic accuracy (3). Infracted or noninfracted myocardium is determined arbitrarily within a viewing window (i.e., the range of gray/color values to be selected for viewing) by these techniques (4). Therefore, assessment of myocardial viability will vary qualitatively and subjectively due to the pitfalls of the techniques.Recently, delayed contrast-enhancement (DE) cardiac magnetic resonance imaging (MRI) has been used for an increasing number of clinical applications in cardiac diseases. However, there are conflicting reports concerning the utility of contrast-enhanced MRI after infarct healing. Firstly, this method makes a qualitative assessment of myocardial fibrosis, similar to previously mentioned methods. In addition, with conventional DE-MRI sequences, signal intensity is expressed on an arbitrarily scale that differs from one imaging to another. Therefore, this method is not suitable for direct signal quantification (5). Furthermore, concerns about the increased risk of gadolinium-induced nephrogenic systemic fibrosis have increased gradually in populations with impaired renal function (6, 7).T1 mapping is a novel cardiac MRI technique and it allows measurements of absolute T1 relaxation times for each pixel (8). This technique involves the sampling of signal recovery during multiple measurements following a preparation pulse. The resulting relaxation time is then determined for each pixel contained in a parametric image, referred to as T1 mapping (9). In contrast to other imaging techniques, T1 mapping achieves signal quantification (in milliseconds) on a standardized scale. It reflects tissue changes without need for signal intensity thresholds, post-processing, reference region-of-interest, or contrast material. The quantitative evaluation of myocardial T1 values (T1 mapping) has been used recently to identify patients with diffuse fibrosis or myocarditis, or acute and chronic myocardial infarction (MI) (4, 10). In addition, although previous studies show that MI quantification can be achieved using a magnetic field strength of 1.5 Tesla (T) (7), to our knowledge, these values have not yet been reported on chronic infarction for 3.0 T cardiac MRI.The purpose of this study was to use high-resolution unenhanced T1 mapping to investigate the feasibility of using 3.0 T cardiac MRI to detect scar areas in myocardium resulting from chronic MI.     

Prevalence and associated factors of treatment failure among HIV/AIDS patients on HAART attending University of Gondar Referral Hospital Northwest Ethiopia

Background

The initiation of highly active antiretroviral therapy (HAART) plays a significant role in the clinical management of HIV infected people by preventing morbidity and mortality. This benefit becomes, the most terrible when treatment failure develops. Thus, this research aims to assess the prevalence and associated factors of treatment failure among HIV/AIDS patients on HAART attending University of Gondar Referral Hospital Northwest Ethiopia.

Results

Patients on ART with a minimum of 6?months and up to 12?years of treatment were being enrolled. The prevalence of treatment failure, immunological failure and virological failure among people living with HIV/AIDS attending University of Gondar referral hospital were 20.3, 13.2, and 14.7%, respectively. Patients who had no formal education (Adjusted odds ratio (AOR): 3.8; 95% CI, 1.05–13.77), primary level education (AOR: 4.2; 95% CI, 1.16–15.01) and duration on ART <?6?years (AOR: 2.1; 95%CI, 1.12–3.81) were a significant risk factor. However, initial adult regimen D4T?+? 3TC+ EFV (AOR: 0.025; 95% CI, 0.002–0.36), AZT +3TC?+?NVP (AOR: 0.07; 95% CI, 0.01–0.71), AZT?+? 3TC?+?EFV (AOR: 0.046; 95% CI, 0.004–0.57) andTDF+3TC?+?EFV (AOR: 0.04; 95% CI, 0.004–0.46) were significantly protective for treatment failure.

Conclusions

Timely and early identification of associated factors and monitoring antiretroviral therapy treatment failure should be done to enhance the benefit and to prevent further complication of the patients. It is preferable to initiate ART using any one of the following ART regimens: AZT +3TC?+?NVP, AZT?+?3TC?+?EFV and TDF?+?3TC?+?EFV to prevent treatment failure. Since the prevalence of this treatment failure and its associated factor may be different from other ART centers and community in Ethiopia, further national representative institutional based cross-sectional researches are needed across all ART centers of Ethiopia in order to determine the prevalence of treatment failure and its associated factors.

     

Multiple correspondence analysis as a tool for analysis of large health surveys in African settings

Background

More than two thirds of the total population of Ethiopia is estimated to be at risk of malaria. Therefore, malaria is the leading public health problem in Ethiopia.

Objective

To investigate the determinants of malaria Rapid Diagnosis Test (RDT) result and the association between socio-economic, demographic and geographic factors.

Method

The study used data from household cluster malaria survey which was conducted from December 2006 to January 2007. A total of 224 clusters of about 25 households each were selected from the Amhara, Oromiya and Southern Nation Nationalities and People (SNNP) regions of Ethiopia. A multiple correspondence analysis was used to jointly analyse malaria RDT result, socio-economic, demographic and geographic factors.

Results

The result from multiple correspondence analysis shows that there is association between malaria RDT result and different socio-economic, demographic and geographic variables.

Conclusion

There is an indication that some socio-economic, demographic and geographic factors have joint effects. It is important to confirm the association between socio-economic, demographic and geographic factors using advanced statistical techniques.     

School-based mass distributions of mebendazole to control soil-transmitted helminthiasis in the Munshiganj and Lakshmipur districts of Bangladesh: An evaluation of the treatment monitoring process and knowledge,attitudes, and practices of the population

Bangladesh's national deworming program targets school-age children (SAC) through bi-annual school-based distributions of mebendazole. Qualitative and quantitative methods were applied to identify challenges related to treatment monitoring within the Munshiganj and Lakshmipur Districts of Bangladesh. Key stakeholder interviews identified several obstacles for successful treatment monitoring within these districts; ambiguity in defining the target population, variances in the methods used for compiling and reporting treatment data, and a general lack of financial and human resources. A treatment coverage cluster survey revealed that bi-annual primary school-based distributions proved to be an effective strategy in reaching school-attending SAC, with rates between 63.0% and 73.3%. However, the WHO target of regular treatment of at least 75% of SAC has yet to be reached. Particularly low coverage was seen amongst non-school attending children (11.4–14.3%), most likely due to the lack of national policy to effectively target this vulnerable group. Survey findings on water and sanitation coverage were impressive with the majority of households and schools having access to latrines (98.6–99.3%) and safe drinking water (98.2–100%). The challenge now for the Bangladesh control program is to achieve the WHO target of regular treatment of at least 75% of SAC at risk, irrespective of school-enrollment status.     

Surveillance of Bacterial Meningitis,Ethiopia, 2012–2013

Among 139 patients with suspected bacterial meningitis in Ethiopia, 2012–2013, meningococci (19.4%) and pneumococci (12.9%) were the major disease-causing organisms. Meningococcal serogroups detected were A (n = 11), W (n = 7), C (n = 1), and X (n = 1). Affordable, multivalent meningitis vaccines for the African meningitis belt are urgently needed.     

Maternal Mortality Predictors in Women with Hypertensive Disorders of Pregnancy: A Retrospective Cohort Study

Background

Hypertensive disorders of pregnancy (HDP) are multisystem disorders unique to human pregnancy. They are becoming the leading causes of maternal mortality worldwide, with the majority of deaths occurring in low income countries. However, little is known about the predictors of maternal mortality in women with HDP.

Methods

A retrospective cohort study was conducted between 2008 and 2013 in three university teaching hospitals among 1015 women admitted with a diagnosis of HDP. Statistically significant associations were assessed by the hazard ratio (HR) with 95% confidence using the Cox proportional hazards model and by the Log Rank test using the Kaplan-Meier survival analyses.

Results

There were 51(5%) maternal deaths and the majority died after they developed eclampsia. The median delay in arrival among the deaths was longer than the survivors. The multivariate survival analyses showed an increased risk of maternal mortality among women with eclampsia (HR=8.4), no antenatal care (HR=2.3), being grand multiparous (HR=2.8), having low diastolic blood pressure (HR=4.5), high creatinine level (HR=9.9), use of diazepam as anticonvulsant (HR=2.7) and untreated with antihypertensive drug (HR=4.2).

Conclusions

The case fatality rate of HDP was among the highest in the world and a delay in initiation of treatment because of delay in health care-seeking contributed to the majority of maternal deaths.     

Premature ovarian failure in the early age 20s: 3 case reports

Premature ovarian failure in the early age 20s is a very rare phenomenon. In a woman presenting with amenorrhea and symptoms of hypoestrogenism, the confirmatory diagnosis of premature ovarian failure relies upon the finding of postmenopausal level of the follicle-stimulating hormone (FSH > 40 mIU/ml). Three women at the age of 25, 30 and 32 years presented with 5, 6 and 10 years secondary amenorrhea, respectively. They used to have regular menses, and two of them gave birth to a healthy baby(ies). Although the etiology remains enigmatic, their gonadotropin and estradiol serum values were found to be in the postmenopausal range. Serum FSH values in the three cases were 135.4, 41.9 and 86.5 mlU/ml. Both combined oral contraceptive pills and progesterone challenge test were administered but couldn't bring about recommencement of menstrual flow. These three women who were diagnosed as a case of premature ovarian failure, evidenced by long standing secondary amenorrhea, secondary infertility, signs and symptoms of postmenopause and biochemical evidences of hypergonadotropic hypoestrogenism, were put on continuous combined oral contraceptive pills and felt better. Literature on the potential serious complications of premature menopause and treatment options in low setting areas is revised.