Comparison of cardiac volumetry using real-time MRI during free-breathing with standard cine MRI during breath-hold in children

Background Cardiac real-time magnetic resonance imaging (RT-MRI) provides high-quality images even during free- breathing. Difficulties in post-processing impede its use in clinical routine. Objective To demonstrate the feasibility of quantitative analysis of cardiac free-breathing RT-MRI and to compare image quality and volumetry during free-breathing RT-MRI in pediatric patients to standard breath-hold cine MRI. Materials and methods Pediatric patients (n= 22) received cardiac RT-MRI volumetry during free breathing (1.5 T; short axis; 30 frames per s) in addition to standard breath-hold cine imaging in end-expiration. Real-time images were binned retrospec- tively based on electrocardiography and respiratory bellows. Image quality and volumetry were compared using the European Cardiovascular Magnetic Resonance registry score, structure visibility rating, linear regression and Bland–Altman analyses. Results Additional time for binning of real-time images was 2 min. For both techniques, image quality was rated good to excellent. RT-MRI was significantly more robust against artifacts (P< 0.01). Linear regression revealed good correlations for the ventricular volumes. Bland–Altman plots showed a good limit of agreement (LoA) for end-diastolic volume (left ventricle [LV]: LoA -0.1 ± 2.7 ml/m2, right ventricle [RV]: LoA -1.9 ± 3.4 ml/m2), end-systolic volume (LV: LoA 0.4 ± 1.9 ml/m2, RV: LoA 0.6 ± 2.0 ml/m2), stroke volume (LV: LoA -0.5± 2.3 ml/m2, RV: LoA -2.6± 3.3 ml/m2) and ejection fraction (LV: LoA -0.5 ± 1.6%, RV: LoA -2.1 ± 2.8%). Conclusion Compared to standard cine MRI with breath hold, RT-MRI during free breathing with retrospective respiratory binning offers good image quality, reduced image artifacts enabling fast quantitative evaluations of ventricular volumes in clinical practice under physiological conditions

Apnea of prematurity: from cause to treatment

Apnea of prematurity (AOP) is a common problem affecting premature infants, likely secondary to a “physiologic” immaturity of respiratory control that may be exacerbated by neonatal disease. These include altered ventilatory responses to hypoxia, hypercapnia, and altered sleep states, while the roles of gastroesophageal reflux and anemia remain controversial. Standard clinical management of the obstructive subtype of AOP includes prone positioning and continuous positive or nasal intermittent positive pressure ventilation to prevent pharyngeal collapse and alveolar atelectasis, while methylxanthine therapy is a mainstay of treatment of central apnea by stimulating the central nervous system and respiratory muscle function. Other therapies, including kangaroo care, red blood cell transfusions, and CO2 inhalation, require further study. The physiology and pathophysiology behind AOP are discussed, including the laryngeal chemoreflex and sensitivity to inhibitory neurotransmitters, as are the mechanisms by which different therapies may work and the potential long-term neurodevelopmental consequences of AOP and its treatment

Scimitar syndrome in infancy

Scimitar syndrome, if presenting in infancy, is associated with signs of heart failure and pulmonary hypertension. The typical pathological features are sequestration of a segment of the lung, usually the right lower lobe, with arterial supply arising from the abdominal aorta, and partial anomalous pulmonary venous connection, with the sequestered segment draining to the inferior caval vein. The typical angiographic features of an infant with Scimitar syndrome. is presented in this articlepeer-reviewe

Transcatheter closure of symptomatic aortopulmonary window in an infant

An aortopulmonary window is a rare congenital cardiac defect. In the majority of symptomatic neonates and infants, primary surgical repair is the treatment of choice. In selected infants, catheter closure of the defect with a device may be feasible. We report on the successful closure of an AP window in a 12 month old infant, using a 6mm Amplatzer septal occluder. The procedure and follow-up were uneventful

Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain

Copyright 2002 Wiley-Liss, Inc.The potential of multiparametric MRI parameters for differentiating between reversibly and irreversibly damaged brain tissue was investigated in an experimental model of focal brain ischemia in the rat. The middle cerebral artery (MCA) was occluded by intraluminal suture insertion for 60 or 90 min, followed by 4.5 h of reperfusion. The apparent diffusion coefficient (ADC) of brain water, T-1 and T-2 relaxation times, and CBFi, an MR-derived index of cerebral perfusion, were repeatedly measured and correlated with the outcome from the ischemic impact. A novel user-independent approach for segmentation of ADC maps into classes of increasing injury was introduced to define regions of interest (ROIs) in which these parameters were evaluated. MCA occlusion led to a graded decline of ADC, which corresponded with both the severity of flow reduction and an increase in T-1 and T-2 relaxation times. Removal of the suture led to a triphasic restitution of blood flow consisting of a fast initial rise, a secondary decline, and final normalization. Postischemic reperfusion led to a rise of ADC irrespective of the duration of ischemia. However, the quality of recovery declined with increasing severity of the ischemic impact. Throughout the observation time, T-1 and T-2 showed a continuous increase, the intensity of which correlated with the severity of ADC decline during ischemia. Particularly with longer ischemia time, elevated T-2 in combination with reduced ADC yielded a lower probability of recovery during recirculation, while intraischemic perfusion information contributed less to the prediction of outcome. In conclusion, the combination of MR parameters at the end of ischemia correlated with the probability of tissue recovery but did not permit reliable differentiation between reversibly and irreversibly damaged tissue

Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain.

Item does not contain fulltextThe potential of multiparametric MRI parameters for differentiating between reversibly and irreversibly damaged brain tissue was investigated in an experimental model of focal brain ischemia in the rat. The middle cerebral artery (MCA) was occluded by intraluminal suture insertion for 60 or 90 min, followed by 4.5 h of reperfusion. The apparent diffusion coefficient (ADC) of brain water, T(1) and T(2) relaxation times, and CBF(i), an MR-derived index of cerebral perfusion, were repeatedly measured and correlated with the outcome from the ischemic impact. A novel user-independent approach for segmentation of ADC maps into classes of increasing injury was introduced to define regions of interest (ROIs) in which these parameters were evaluated. MCA occlusion led to a graded decline of ADC, which corresponded with both the severity of flow reduction and an increase in T(1) and T(2) relaxation times. Removal of the suture led to a triphasic restitution of blood flow consisting of a fast initial rise, a secondary decline, and final normalization. Postischemic reperfusion led to a rise of ADC irrespective of the duration of ischemia. However, the quality of recovery declined with increasing severity of the ischemic impact. Throughout the observation time, T(1) and T(2) showed a continuous increase, the intensity of which correlated with the severity of ADC decline during ischemia. Particularly with longer ischemia time, elevated T(2) in combination with reduced ADC yielded a lower probability of recovery during recirculation, while intraischemic perfusion information contributed less to the prediction of outcome. In conclusion, the combination of MR parameters at the end of ischemia correlated with the probability of tissue recovery but did not permit reliable differentiation between reversibly and irreversibly damaged tissue