Erik Hedström

Purpose: To develop and evaluate, in a feasibility study, a computationally efficient image‐reconstruction pipeline for 3D balanced steady state free precession (bSSFP) CINE fetal cardiac MRI that reduces radial streaking artifacts, increases effective temporal resolution, and improves diagnostic image quality compared with previous work. Methods: Three‐dimensional bSSFP CINE data from 10 volunteers were used. Coil compression was performed using the region‐optimized virtual coils (ROVir) technique and compared with singular value decomposition (SVD) coil compression. For ROVir, the region of interest encompassed the fetal thorax, while the region of interference was positioned over the maternal subcutaneous fat to suppress unwanted signal contributions. Image reconstruction was performed for multiple temporal samplings. Two observers evaluated diagnostic image quality using a visual‐analog scale, and results were analyzed using visual grading characteristics (VGC). Computational efficiency was evaluated using reconstruction runtime and memory usage. Results: Average 3D CINE acquisition time was 5 min, with a reconstruction time of approximately 5 h for both SVD (8channels and 8 phases) and ROVir (3 channels and 16 phases), with approximately equal memory usage. ROVir enabled higher temporal resolution by reducing the channels required. VGC analysis showed a preference for ROVir across all diagnostic criteria (AUC > 0.5), including edge sharpness, perceived image contrast, artifact suppression, papillary muscles, great vessels, and extracardiac diagnostic image quality, with comparable median scores across temporal samplings. Conclusion: ROVir coil compression improved diagnostic quality and reduced reconstruction time. By reducing memory demands, reconstruction with a higher number of cardiac phases was also possible.

Background: The geometrical relationship between atrial and ventricular short‐axis cross‐sectional area determines the hydraulic forces acting on intracardiac blood. This is important for diastolic filling. In patients undergoing heart transplantation (HTx), the left atrium is often enlarged as a result of the standard surgical technique. We hypothesized that diastolic filling in HTx patients is affected by the surgery altering the geometrical relationship between atrium and ventricle. Methods and Results: This retrospective, cross‐sectional study included 25 HTx patients (median age, 52 [range, 25–70] years), 15 patients with heart failure with reduced ejection fraction (median age, 63 [range, 52–75] years), 15 patients with heart failure with preserved ejection fraction (median age, 74 [range, 56–82] years), and 15 healthy controls (median age, 64 [range, 58–67] years) who underwent cardiac magnetic resonance imaging. Left ventricular, atrial, and total heart volumes (THV) were obtained. Atrioventricular area difference at end diastole and end systole was calculated as the largest ventricular short‐axis area minus the largest atrial short‐axis area. Left atrial minimum volume normalized for THV (LA _min /THV) was larger in HTx patients (median, 0.13 [range, 0.07–0.19]) compared with controls (median, 0.05 [range, 0.03–0.08], P <0.001), whereas left ventricular volume normalized for THV (left ventricular end‐diastolic volume/THV) was similar between HTx and controls (median, 0.19 [range, 0.12–0.24] and median, 0.22 [range, 0.20–0.25], respectively). At end diastole, when atrioventricular area difference reached its largest positive value in controls, 11 HTx patients (44%) had a negative atrioventricular area difference, indicating impaired diastolic filling. Conclusions: Diastolic filling is impaired in HTx patients due to an altered geometrical relationship between the left atrium and ventricle. When performing cardiac transplantation, a surgical technique that creates a smaller left atrium may improve diastolic filling by aiding hydraulic forces.

Background: Photon-counting computed tomography (PCCT) is a new clinical method that may show better diagnostic quality at lower radiation doses than conventional CT.Objective: To investigate the diagnostic quality and radiation dose of paediatric cardiovascular PCCT for diagnosis of congenital heart defects at 70 kV and 90 kV.Materials and methods: This retrospective assessment included clinical non-gated paediatric PCCT examinations for assessment of congenital heart defects. Radiation doses were recorded, and overall and specific diagnostic quality (1–4) were scored by four paediatric radiologists. Agreement, differences, and trends were assessed by percent rater agreement, intraclass correlation, Mann–Whitney tests, and Jonckheere-Terpstra tests.Results: Seventy children with congenital heart defects were examined at 70 kV (n = 35; age 2 days–16 years; 63% boys) or 90 kV (n = 35; age 2 days–17 years; 51% boys). All observers gave a median score of 4 (high diagnostic quality) for both 70 kV and 90 kV, with no difference in median values between tube voltages (all P > 0.06). Agreement for overall scores was 66–94% for 70 kV and 60–77% for 90 kV. Agreement for specific scores was 80–97% for 70 kV and 83–89% for 90 kV. Size-dependent dose estimate was 0.68 mGy (0.25–2.02 mGy) for 70 kV and 1.10 mGy (0.58–2.71 mGy;P < 0.001) for 90 kV. Effective dose was 0.30 mSv (0.15–0.82 mSv) for 70 kV and 0.39 mSv (0.22–1.51 mSv;P = 0.01) for 90 kV.Conclusion: Paediatric cardiovascular PCCT yields images for congenital heart defects of high diagnostic quality with low radiation dose at both 70 kV and 90 kV.

Background: Severe left-sided cardiac obstructions are associated with high morbidity and mortality if not detected in time. The correct prenatal diagnosis of coarctation of the aorta (CoA) is difficult. Fetal cardiac magnetic resonance imaging (CMR) may improve the prenatal diagnosis of complex congenital heart defects. Flow measurements in the ascending aorta could aid in predicting postnatal CoA, but its accurate visualization is challenging.Objectives: To compare the flow in the descending aorta (DAo) and umbilical vein (UV) in fetuses with suspected left-sided cardiac obstructions with and without the need for postnatal intervention and healthy controls by fetal phase-contrast CMR flow. A second objective was to determine if adding fetal CMR to echocardiography (echo) improves the fetal CoA diagnosis.Methods: Prospective fetal CMR phase-contrast flow in the DAo and UV and echo studies were conducted between 2017 and 2022.Results: A total of 46 fetuses with suspected left-sided cardiac obstructions [11 hypoplastic left heart syndrome (HLHS), five critical aortic stenosis (cAS), and 30 CoA] and five controls were included. Neonatal interventions for left-sided cardiac obstructions (n = 23) or comfort care (n = 1 with HLHS) were pursued in all 16 fetuses with suspected HLHS or cAS and in eight (27%) fetuses with true CoA. DAo or UV flow was not different in fetuses with and without need of intervention. However, DAo and UV flows were lower in fetuses with either retrograde isthmic systolic flow [DAo flow 253 (72) vs. 261 (97) ml/kg/min, p = 0.035; UV flow 113 (75) vs. 161 (81) ml/kg/min, p = 0.04] or with suspected CoA and restrictive atrial septum [DAo flow 200 (71) vs. 268 (94) ml/kg/min, p = 0.04; UV flow 89 vs. 159 (76) ml/kg/min, p = 0.04] as well as in those without these changes. Adding fetal CMR to fetal echo predictors for postnatal CoA did not improve the diagnosis of CoA.Conclusion: Fetal CMR-derived DAo and UV flow measurements do not improve the prenatal diagnosis of left-sided cardiac obstructions, but they could be important in identifying fetuses with a more severe decrease in blood flow across the left side of the heart. The physiological explanation may be a markedly decreased left ventricular cardiac output with subsequent retrograde systolic isthmic flow and decreased total DAo flow.

Diagnosis and treatment of patients with suspected chronic coronary syndrome (CCS) currently relies on the degree of coronary artery stenosis and its significance for myocardial perfusion. However, myocardial perfusion can be affected by factors other than coronary stenosis. The aim of this study was to investigate to what extent sex, age, diabetes, hypertension and smoking affect quantitative myocardial perfusion, beyond the degree of coronary artery stenosis, in patients with suspected or established CCS. Eighty‐six patients [median age 69 (range 46−86) years, 24 females] planned for elective coronary angiography due to suspected or established CCS were included. All patients underwent cardiac ¹³N‐NH₃ positron emission tomography to quantify myocardial perfusion at rest and stress. Lowest myocardial perfusion (perfusion_min) at stress and rest and lowest myocardial perfusion reserve (MPR_min) for all vessel territories was used as dependent variables in a linear mixed model. Independent variables were vessel territory, degree of coronary artery stenosis (as a continuous variable of 0%−100% stenosis), sex, age, diabetes, hypertension and smoking habits. Degree of coronary artery stenosis (p < 0.001), male sex (1.8 ± 0.6 vs. 2.3 ± 0.6 mL/min/g, p < 0.001), increasing age (p = 0.025), diabetes (1.6 ± 0.5 vs. 2.0 ± 0.6 mL/min/g, p = 0.023) and smoking (1.9 ± 0.6 vs. 2.1 ± 0.6 mL/min/g, p = 0.052) were independently associated with myocardial perfusion_min at stress. Degree of coronary artery stenosis (p < 0.001), age (p = 0.040), diabetes (1.8 ± 0.6 vs. 2.3 ± 0.7, p = 0.046) and hypertension (2.2 ± 0.7 vs. 2.5 ± 0.6, p = 0.033) were independently associated with MPR_min. Sex, increasing age, diabetes, hypertension and smoking affect myocardial perfusion independent of coronary artery stenosis in patients with suspected or established CCS. Thus, these factors need to be considered when assessing the significance of reduced quantitative myocardial perfusion of patients with suspected or established CCS.

Left ventricular shape alterations predict cardiovascular outcomes and have been observed in children born preterm and after fetal growth restriction (FGR). The aim was to investigate whether left ventricular shape is altered in adolescents born very preterm and if FGR has an additive effect. Adolescents born very preterm due to verified early-onset FGR and two control groups with birthweight appropriate for gestational age (AGA), born at similar gestational age and at term, respectively, underwent cardiac MRI. Principal component analysis was applied to find the modes of variation best explaining shape variability for end-diastole, end-systole, and for the combination of both, the latter indicative of function. Seventy adolescents were included (13–16 years; 49% males). Sphericity was increased for preterm FGR versus term AGA for end-diastole (36[0–60] vs − 42[− 82–8]; p = 0.01) and the combined analysis (27[− 23–94] vs − 51[− 119–11]; p = 0.01), as well as for preterm AGA versus term AGA for end-diastole (30[− 56–115] vs − 42[− 82–8]; p = 0.04), for end-systole (57[− 29–89] vs − 30[− 79–34]; p = 0.03), and the combined analysis (44[− 50–145] vs − 51[− 119–11]; p = 0.02). No group differences were observed for left ventricular mass or ejection fraction (all p ≥ 0.33). Sphericity was increased after very preterm birth and exacerbated by early-onset FGR, indicating an additive effect to that of very preterm birth on left ventricular remodeling. Increased sphericity may be a prognostic biomarker of future cardiovascular disease in this cohort that as of yet shows no signs of cardiac dysfunction using standard clinical measurements.

Purpose: To ultimately make accurate and precise fetal noninvasive oxygen saturation (sO₂) measurements by T₂‐prepared bSSFP more widely available by systematically assessing error sources in order to potentially reduce perinatal mortality in cardiovascular malformations and fetal growth restriction.Methods: T₂‐prepared bSSFP data were acquired in phantoms; in flowing blood in adults in the superior sagittal sinus, ascending and descending aorta, and main pulmonary artery; and in the fetal descending aorta and umbilical vein. T₂ was assessed in relation to T₂ two‐ or three‐parameter curve‐fitting techniques, SSFP readout, refocusing time delay (τ), constant and pulsatile blood flow, and impact of T₁ recovery. Further, fetal T₂ and sO₂ variability were quantified in the descending aorta and umbilical vein in healthy fetuses and fetuses with cardiovascular malformation (gestational weeks 32–38).Results: In phantoms, three‐parameter fitting was accurate irrespective of phase FOV (2 was overestimated (up to 23 ms/10%; p = 0.001) beyond ±30 Hz off‐resonance. In the adult aorta, T₂ was underestimated during higher blood flow velocities and pulsatility for τ = 16 ms (−41 ms/−17%; p = 0.008). In fetuses, two‐parameter fitting overestimated T₂ compared with three‐parameter fitting (+33 ms/+18%; p = 0.03). T₂ variability was 18 ms/15% in the fetal descending aorta and 28 ms/14% in the umbilical vein. The resulting estimated sO₂ variability was ∼10% (15% of sO₂ value) in the fetal descending aorta.Conclusions: Errors due to T₂‐fitting techniques, off‐resonance, flow velocity, and insufficient T₁ recovery between image acquisitions could be mitigated by using three‐parameter fitting with included saturation‐prepared images approximating infinite T₂‐preparation time, adequate shimming covering the fetus and placenta, and by modifying acquisition parameters. Variability in fetal blood T₂ and sO₂, however, indicate that it is currently not feasible to use these methods for prediction of disease.

Background: Preterm birth and fetal growth restriction (FGR) are associated with structural and functional kidney changes, increasing long-term risk for chronic kidney disease and hypertension. However, recent studies in preterm children are conflicting, indicating structural changes but normal kidney function. This study therefore assessed kidney structure and function in a cohort of adolescents born very preterm with and without verified FGR. Methods: Adolescents born very preterm with FGR and two groups with appropriate birthweight (AGA) were included; one matched for gestational week at birth and one born at term. Cortical and medullary kidney volumes and T1 and T2* mapping values were assessed by magnetic resonance imaging. Biochemical markers of kidney function and renin–angiotensin–aldosterone system (RAAS) activation were analyzed. Results: Sixty-four adolescents were included (13–16 years; 48% girls). Very preterm birth with FGR showed smaller total (66 vs. 75 ml/m²; p = 0.01) and medullary volume (19 vs. 24 ml/m²; p < 0.0001) compared to term AGA. Corticomedullary volume ratio decreased from preterm FGR (2.4) to preterm AGA (2.2) to term AGA (1.9; p = 0.004). There were no differences in T1 or T2* values (all p ≥ 0.34) or in biochemical markers (all p ≥ 0.12) between groups. Conclusions: FGR with abnormal fetal blood flow followed by very preterm birth is associated with smaller total kidney and medullary kidney volumes, but not with markers of kidney dysfunction or RAAS activation in adolescence. Decreased total kidney and medullary volumes may still precede a long-term decrease in kidney function, and potentially be used as a prognostic marker. Graphical