Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition.

In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high.In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR 'source' image data, while maintaining their resolution.It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover spatial resolution of the source image data.For different CT applications: dual energy imaging, liver imaging, spiral imaging, cardiac imaging, we show that SNR can efficiently be transferred from the composite image to the source image data at constant patient dose, while maintaining resolution properties of the source data.

Pulmonary vein stenosis: the UK, Ireland and Sweden collaborative study.

OBJECTIVE: To describe clinical features, morphology, management and outcome of pulmonary vein stenosis (PVS) in childhood. DESIGN AND SETTING: Retrospective international collaborative study involving 19 paediatric cardiology centres in the UK, Ireland and Sweden. PATIENTS: Cases of PVS presenting between 1 January 1995 and 31 December 2004 were identified. Cases where pulmonary veins connected to a morphological left atrium were included. Functionally univentricular hearts and total anomalous pulmonary venous connection were excluded. All available data and imaging were reviewed. RESULTS: 58 cases were identified. In 22 cases (38%) there was premature delivery. 46 (79%) had associated cardiac lesions; 16 (28%) had undergone previous cardiac surgery before PVS diagnosis. 16 children (28%) had a syndrome or significant extracardiac abnormality. 36 presented with unilateral disease of which 86% was on the left. Where there was adequate sequential imaging, disease progression was shown with discrete stenosis leading to diffusely small pulmonary veins. Collateral vessels often developed. 13 patients had no intervention. Initial intervention was by catheter in 17 and surgery in 28. Overall 3-year survival was 49% (95% CI 35% to 63%) with patients undergoing initial surgical intervention having greater freedom from death or re-intervention (hazard ratio 0.44, 95% CI 0.2 to 0.99, p = 0.023). CONCLUSIONS: PVS is a complex disease of uncertain cause and frequently associated with prematurity. Early intervention may be indicated to deter irreversible secondary changes.

Physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects.

AIM: To investigate physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects. SUBJECTS AND METHODS: Children who had undergone surgery for congenital heart defects and healthy controls in the Gothenburg area were invited to participate in the study. All participants were aged 9-11 or 14-16 years. The activity monitor ActiReg was used to assess physical activity. Participants were interviewed about their participation in sports and performed a maximal exercise test on a bicycle with measured oxygen uptake. RESULTS: A total of 32 and 25 patients, and 61 and 45 controls, in the two age-groups were included, respectively. The patients had a wide range of severity of congenital heart defects. The physical activity level was similar in the patients and the controls. The rate of sports participation was high for both patients and controls; 80-94% of all participants took part in sports at least once a week. The majority of the patients were considered to have at least a moderate level of aerobic fitness. CONCLUSIONS: Although children who have undergone surgery for congenital heart defects have a similar level of physical activity compared with that of healthy children, some of them may require support to participate in exercise and vigorous physical activity.

Relative cardiac expression of growth hormone receptor and insulin-like growth factor-I mRNA in congenital heart disease.

GH may exert direct growth-promoting and metabolic actions on target tissues, but most of its effects are mediated by circulating (endocrine) or local (auto-/paracrine) IGF-I. The GH/IGF-I system has an important role in cardiac development and in maintaining the structure and function of the heart. A subgroup of children with pronounced heart defects will eventually need transplants, owing to congestive heart failure. Since the symptoms are often severe and may progress while waiting for surgery, it is necessary to develop supportive medical treatment. GH has been proposed as a therapeutic agent in adults with heart failure, but to date studies are lacking on children and more information is necessary. We have examined the expression of IGF-I mRNA and GH-receptor (GH-R) mRNA in children undergoing surgery for congenital heart disease. Eighteen children scheduled for open-heart surgery were included in the study. Right auricular biopsies were taken at the time of venous catheterization preceding cardiac bypass. The specimens were analysed using realtime PCR. We were able to show expression of both IGF-I mRNA and GH-R mRNA in the pediatric heart. The relative expressions were intercorrelated (r=0.75, p<0.001). GH-R mRNA correlated positively to standardized weight (r=0.65, p=0.004), body mass index (BMI) (r=0.59, p=0.01), and standardized BMI (r=0.59, p=0.01). IGF-I mRNA only correlated to BMI (r=0.50, p=0.04). This is the first study displaying cardiac expression of IGF-I mRNA and GH-R mRNA in children with congenital heart disease, although further studies are needed to define a role for GH in the treatment of these patients.

The outcome of children born with pulmonary atresia and intact ventricular septum in Sweden from 1980 to 1999.

OBJECTIVE: To study the outcome of all children born with pulmonary atresia and intact ventricular septum in Sweden between 1980 and 1999. DESIGN: Retrospective study of medical records with review of the initial, preoperative angiocardiographic and echocardiographic examinations. RESULTS: A total of 84 children were born with pulmonary atresia and intact ventricular septum, giving an incidence of 4.2 per 100,000 live births. In all, 77 were operated on with a 1-year survival rate of 75%. Thirty-six children had ventriculocoronary communications, with a 1-year survival rate of 50%. At the end of the study period, 52 children were alive, 32 with biventricular repair, and 19 with univentricular repair. Follow-up time was 14 days-20 years (median, 6 years). Statistical analysis of incremental risk factors for death showed statistical significance for low birth weight, male sex, muscular pulmonary atresia, and having a systemic-to-pulmonary shunt as the sole initial intervention. CONCLUSION: Complete national data of all patients born with pulmonary atresia and intact ventricular septum during 1980-1999 in Sweden revealed a total mortality in accordance with previous reports for results for surgery. Further improvements demand a thorough preoperative investigation of the cardiac anatomy, particularly of the ventriculocoronary communications, to enable right ventricular decompression whenever possible.

Centralization of pediatric heart surgery in Sweden.

In Sweden, which has a population of 8.9 million people, pediatric heart surgery was previously performed in four cities. After a long, difficult process, centralization of pediatric heart surgery to two centers was achieved in 1993. The overall 30-day mortality for open-heart surgery on infants and children of 9.5% before the centralization (1988-1991) was reduced to 1.9% in 1995-1997. A causal relationship between the mortality rates before and after the centralization is impossible to prove. Heart surgery was concentrated to the two centers with the lowest surgical mortality, and the reduction in surgical mortality was observed over a short period of time which makes it likely that the centralization of the surgical activity promoted the improved results. During the later time period the amount of more complex surgery was clearly increased compared to that performed previously.

Preoperative evaluation and surgery in isolated ventricular septal defects: a 21 year perspective.

OBJECTIVE: To study short and long term results after surgical closure of isolated ventricular septal defects (VSDs) from 1976 to 1996, especially in relation to changes in preoperative evaluation during this period. DESIGN: Retrospective study. SETTING: Tertiary referral centre for paediatric cardiac care. PATIENTS: All children under 18 years of age who had corrective surgery for VSD between 1976 and 1996. MAIN OUTCOME MEASURES: Preoperative evaluation, indications for surgery, diagnostic errors, and early and late results. RESULTS: A significant decrease in the use of invasive preoperative studies in favour of non-invasive methods was found; from 1976 to 1990, a total of 109/110 patients had preoperative invasive study as compared to 43/167 from 1991 to 1996 (p < 0.001). Pulmonary hypertension in small children, without detailed information on Qp:Qs ratio, as well as small or modest shunts without pulmonary hypertension, were more frequent indications for surgery in recent years. Early mortality after surgery occurred in 10 patients, with a significantly lower mortality rate found between 1991 and 1996 than between 1976 and 1990 (0.6% v 8.2%, p < 0.001). Children with large VSDs experienced perioperative complications significantly less often between 1991 and 1996 than between 1976 and 1990 (16/105 v 28/96, p < 0.05). Diagnostic errors showed a tendency to decrease between the two time periods. No late deaths occurred. CONCLUSIONS: Significant reductions in early mortality, perioperative complications, and diagnostic mistakes were seen during the study period, even though less invasive diagnostic procedures were being performed.

The effect of changing attitudes to Down's syndrome in the management of complete atrioventricular septal defects.

OBJECTIVES: To describe the evaluation, decision making, and care of children with a complete atrioventricular septal defect (CAVSD). STUDY DESIGN: Retrospective study of 136 consecutive cases from 1970 to 1996. RESULTS: A total of 115 (85%) children had Down's syndrome. Denial of surgery without obvious medical reasons was more common in the early years, as was parental refusal of offered surgery and institutional care of the children. Improved results in later years encouraged surgical treatment for all these patients, but more liberal attitudes towards patients with Down's syndrome preceded the improved results. The use of echocardiography as a screening method for all newborns with Down's syndrome made it possible to plan for correction within the 1st months of life. CONCLUSIONS: Changing attitudes in society and widespread use of echocardiography have significantly improved the management of children with a CAVSD and Down's syndrome.

Myocardial function after autologous bone marrow transplantation in children: a prospective long-term study.

Early cardiac complications after autologous bone marrow transplantation (ABMT) were recorded for 49 children with haematological malignancies. There was no procedure-related mortality and only two cases of early post-transplant cardiac complications of clinical relevance, both of which were reversible. For 35 long-time survivors (median follow-up 7 y) serial evaluations before and after ABMT included ECG, chest radiography, echocardiography and equilibrium radionuclide ventriculography (RVG). One patient had frequent supraventricular ectopic beats after ABMT, a finding not previously noted. The mean left ventricular diastolic diameter (LVDD) was 104% of expected before ABMT (95% confidence interval 99-110). During the first year post-transplant LVDD was about 110% of expected, but thereafter normalization occurred. The mean shortening fraction before ABMT was 31% (CI 29-34), compared with the mean value of 34% for healthy children in our laboratory, and it ranged between 29% and 33% during the follow-up period. Mean left ventricular ejection fraction determined by RVG was 65% (CI 61-69) and mean right ventricular ejection fraction was 46% (CI 43-49) before ABMT, and they did not change during follow-up. It is encouraging that these heavily pre-treated children could be autografted without serious cardiac complications or deterioration in myocardial performance in a 5-10-y prospect, but longer follow-up is needed for a final evaluation.

Inflammatory reactions following homograft insertion in children with congenital heart disease.

A study was carried out to assess significant short-term postoperative complications in children undergoing valved homograft surgery for congenital heart defects. Clinical and laboratory parameters of 50 patients undergoing this type of surgery were compared with those of 50 randomly selected but age-matched controls in whom open-heart surgery was performed without a homograft. Extracorporeal circulation, aortic clamping and intensive care times and the duration of febrile response were significantly longer in the study patients than in the controls (each p < 0.0001). In laboratory data the only significant difference between the two groups was in the C-reactive protein response, which was high in the study group (p < 0.0004) and did not correlate with extracorporeal circulation time or with positive blood cultures. The prolonged febrile and acute-phase reactant response following valved homograft surgery is an inflammatory reaction to the foreign antigen.

Endomyocardial biopsy in heart-transplanted children: comparison of sheaths to guide biopsy forceps.

The risk of perforation during 65 endomyocardial biopsies (380 specimens) was investigated using two different sheaths to guide the biopsy forceps in five heart-transplanted children aged 1.6-12.9 years. One of the sheaths guided the biopsy forceps simply into the right ventricle (prefabricated 110 degrees curved tip); the other (specially curved sheath) had two curves, the distal one of which guided the forceps posteriorly toward the interventricular septum. The position of the sheath was evaluated by biplane fluoroscopy and, in children

Balloon angioplasty of recurrent coarctation: a 12-year review.

OBJECTIVES: This study was undertaken to investigate the long-term outcome of balloon angioplasty for recurrent coarctation of the aorta in a large series of patients. BACKGROUND: Balloon angioplasty has become the standard treatment for residual or recurrent aortic coarctation. Despite the widespread use of this treatment modality, there are few data outlining the long-term outcome of a large patient cohort. METHODS: Clinical, echocardiographic, hemodynamic and angiographic data on 90 consecutive patients who underwent balloon angioplasty between January 1984 and January 1996 were reviewed. RESULTS: Mean systolic pressure gradients were reduced from 31 +/- 21 to 8 +/- 9 mm Hg after dilation (p = 0.0001). The mean diameter of the stenotic site, measured in the frontal and lateral views, increased by 38% and 35%, respectively (p = 0.001). Neurologic events occurred in two patients, with one death. An aortic tear occurred in one patient, requiring surgical intervention. Optimal results were defined as a postprocedure gradient < 20 mm Hg and were obtained acutely in 88% of patients. At long-term follow-up (12 years), 53 (72%) of 74 patients with an early optimal result remained free from reintervention. Transverse arch hypoplasia, defined as an arch dimension < 2 SD below the mean for age, was the primary predictor of the need for reintervention. CONCLUSIONS: Although the majority of patients undergoing percutaneous balloon angioplasty for recoarctation of the aorta will achieve long-term benefit, the need for further surgical intervention in those with transverse arch hypoplasia remains high.

[Echocardiographic findings before and after interventional occlusion of a persistent ductus arteriosus Botalli using the Rashkind Occluder System]. / Echokardiographische Befunde vor und nach interventionellem Verschluss eines persistierenden Ductus arteriosus Botalli mit Hilfe des Rashkind-Okkluder-Systems.

AIM: The aim of this study was to investigate whether before releasing the Rashkind occluder system for occlusion of persistently patent ductus arteriosi Botalli from the delivery catheter its position can be adequately demonstrated sonographically to avoid angiography. METHOD: From March to August 1993 occlusion of a persistently patent ductus arteriosus by means of the Rashkind system was carried out in 10 patients. A standard technique using transthoracic echocardiography was used. RESULTS: Echocardiography allowed to demonstrate and locate the occluder system in all cases. CONCLUSION: Echocardiography is a reliable means for locating the Rashkind occluder system avoiding angiography.

Extreme underdevelopment of the left heart. The ultimate hypoplastic left heart syndrome.

We report a case of extreme underdevelopment of the left heart with a 12-day survival. At postmortem, neither a left atrium nor connecting pulmonary veins were identified. The left ventricle was only identified on histology. This was, effectively, a case of absence of the left heart.

Aplasia of the right aortic cusp in a neonate: a life-threatening but curable anomaly.

A case of absent right aortic cusp causing serious aortic incompetence in a neonate is reported. A "bicuspidalization" repair broke down within 24 hours, but reoperation with annular enlargement and insertion of a 19-mm prosthetic valve resulted in complete recovery. This rare but life-threatening anomaly of the aortic valve can be recognized with Doppler echocardiography. Valve replacement in conjunction with aortic annular enlargement should be performed as primary repair.

Analysis of survival in patients with pulmonic valve atresia and ventricular septal defect.

This study reviews the clinical course of 104 consecutive patients with pulmonic valve atresia and ventricular septal (VSD) defect who were diagnosed in the first year of life and followed for a mean period of 4.95 years (range 2 days to 13.75 years). Specific attention was paid to the nature of the pulmonary blood supply and to its influence on patient outcome. Confluent pulmonary arteries supplied by a single ductus arteriosus were present in 72 patients (69%, group I), whereas 32 patients (31%, group II) had a pulmonary blood supply that was partially or exclusively dependent on systemic collateral arteries. An estimate of the probability of survival for 10 years was 69% in the entire cohort, with no different between patients in group I and group II. Definitive surgical repair was performed in 33 of 72 group I patients (46%), compared with 5 of 32 group II patients (16%). Arborization and distribution abnormalities of the pulmonary arteries as well as intrapulmonary stenoses that were exclusively present in patients with systemic collateral arteries (p less than 0.00001) accounted for the significantly lower probability of undergoing corrective surgery in group II patients.

Friedreich's ataxia in 13 children: presentation and evolution with neurophysiologic, electrocardiographic, and echocardiographic features.

Thirteen children with Friedreich's ataxia were reviewed. The clinical presentation and evolution of the disease was compared to that observed in large series--based mainly on adult patients--and the few studies in children. The mean age of onset (5.3 +/- 2.7 years) was lower than that reported in the former studies. Progressive unremitting ataxia of all four limbs was the earliest and most consistent finding, whereas dysarthria and loss of joint or vibration sense occurred with less frequency than that reported in adult series. The tendon jerks were absent or reduced in the lower limbs in almost all children. The universal absence of lower limb reflexes was shown to be too rigid to be obligatory for the diagnosis of early cases of Friedreich's ataxia. Electrophysiologic investigations revealed typical findings, ie, normal or low-normal motor conduction velocities and absent sensory responses. Electromyography showed more features of denervation in the lower limbs than in the upper limbs. Cardiac symptoms and signs were minimal, whereas electrocardiographic abnormalities occurred in 92% of patients, presenting mostly as significant T-wave changes. Concentric symmetric thickening of both the interventricular and left ventricular posterior walls was the major echocardiographic finding.