P160 RIGHT SISTEMIC VENTRICLE AND PREGNANCY

Patient with complex congenital heart disease: situs inversus with dextrocardia and transposition of the great vessels (D–TGA), right aortic arch and inferior cava agenesis with azygos continuation; at 4 months Mustard atrial switch (intratrial baffle for redirection of the systemic venous circulation in the left subpulmonary left ventricle and of the pulmonary venous circulation in the right subaortic systemic ventricle). At 22 years, 1st pregnancy without complications, caesarean section, birth weight 2.2 kg. Two pregnancies spontaneously terminated in the firts trimester. At 29 years echocardiography: right systemic ventricle hypertrophic, dilated and slightly hypokinetic with tricuspid (systemic) valve with mild to moderate insufficiency; Mustard circuit normally functioning on the systemic side, mild stenosis of the pulmonary buffle (Gmax 6mmHg). At 33 years monochorionic biamniotic twins pregnancy; the risk linked to pregnancy for the patient on the basis of her heart disease was included in a WHO class III worsened by twinning. Because of the high probability of maternal and fetal complications related to the continuation of pregnancy, it was necessary to recommend a selective interruption of the pregnancy of the fetus affected by severe selective underdevelopment with signs of twin to twin transfusion at the 20th week of gestation. Maternal clinical and haemodynamic conditions have been stable during pregnancy. At the 24th week of gestation echocardiography: worsening of the systemic right function ventricle, moderate tricuspid insufficiency and increased gradients in the Mustard circuit (systemic Gmax 13mmHg and pulmonary venous Gmed 8mmHg). After the pregnancy team‘s discussion, a delivery plan was proposed to transfer the patient to a third level cardiac surgery center with experience in congenital heart disease adult between the 35th and 36th week. This was not possible because the patient at 32th week presented preterm labor with caesarean section without maternal and newborn complications (birth weight 1,650 kg). In the puerperium ehocardiography: hypertrophic, dilated and moderately hypokinetic systemic right ventricle with moderate tricuspid insufficiency; Mustard circuit: systemic baffle max gradient 16mmHg and pulmonary venous medium gradient 9mmHg. 7 years after this pregnancy at the last visit: stable clinical and echocardiographic situation with persistence of moderate dysfunction of the systemic right ventricle.

Collapse

P398 A CASE OF MIS–C: SARS–COV2 AND MYOCARDITIS IN PEDIATRIC AGE

A 12–year–old patient with paucisymptomatic SARS–COV2 infection in November 2020 with negative swab after 10 days. After 3 weeks access to pediatric emergency room for fever, maculo–papular rash on the trunk, conjunctivitis, nausea and abdominal pain: evidence of thrombocytopenia, increased CPK, LDH, AST and inflammation markers. She starts antibiotic therapy for suspected sepsis. After 24 hours asthenia, general illness, hypotension and tachycardia: echocardium with diffuse hypokinesia of the left ventricle (EF 35%); worsening of thrombocytopenia, D–Dimer, BNP and CPK increase, hyponatremia, troponin positivity, ATIII reduction; negative viral markers. On the basis of the most recent literature, the diagnosis of MIS–C is made, a post–infection SARS–COV2 multisystemic inflammatory syndrome. After discussion with the 3rd level SARS–COV2 Pediatric Center, the following therapy begins: iv diuretic, iv cortisone, sc heparin, iv immunoglobulins, Anakinra. For a progressive clinical worsening by cardiogenic shock with evolution to DIC, she is transferred by military plane to the pediatric intensive care of 3rd level SARS–COV2 Center. The patient is subjected to mechanical ventilation, therapy with inotropes (adrenaline and milrinone) and CRRT ultrafiltration in order to reduce the excessive levels of inflammatory mediators responsible for rapid multiorgan failure. After 4 days, haemodynamic parameters improvement (EF 50%); sartan and low dose diuretic have been started because of the presence of diastolic dysfunction. Discharge after 1 month of hospitalization with good clinical and haemodynamic stability. After 6 months from myocarditis onset with cardiogenic shock in MIS–C, cardiac MRI with evidence of EF 57% and small area of delayed enhancement on the anterior IVS with non–ischemic pattern, no longer present by imaging after 1 year by acute event. Currently the patient reports subjective well–being by the regular follow–up without arrhythmias by Holter monitoring. SARS–COV2 post–infection multisystemic inflammatory syndrome (MIS–C) represents a serious complication with possible myocardial involvement also following a paucysymptomatic infection as in the described case. What happened shows us that SARS–COV2 infection is still a devious clinical entity that needs close follow–up in the short and long term.

Collapse

IMPULSE: A scalable algorithm for design of minimum specific absorption rate parallel transmit RF pulses

PURPOSE

Managing local specific absorption rate (SAR) in parallel transmission requires ensuring that the peak SAR over a large number of voxels (> 10 5 ) is below the regulatory limit. The safety risk to the patient depends on cumulative (not instantaneous) SAR thus making a joint design of all RF pulses in a sequence desirable. We propose the Iterative Minimization Procedure with Uncompressed Local SAR Estimate (IMPULSE), an efficient optimization formulation and algorithm that can handle uncompressed SAR matrices and optimize pulses for all slices jointly within a practical time frame.

THEORY AND METHODS

IMPULSE optimizes parallel transmit pulses for small-tip-angle slice selective excitation to minimize a single cost function incorporating multiple quantities (local SAR, global SAR, and per-channel power) averaged over the entire multislice scan subject to a strict constraint on excitation accuracy. Pulses for an 8-channel 7T head coil were designed with IMPULSE and compared with pulses designed using generic optimization algorithms and VOPs to assess the computation time and SAR performance benefits.

RESULTS

IMPULSE achieves lower SAR and shorter computation time compared with a VOP approach. Compared with the generic sequential quadratic programming algorithm, computation time is reduced by a factor of 5-6 by using IMPULSE. Using as many as 6 million local SAR terms, up to 120 slices can be designed jointly with IMPULSE within 45 s.

CONCLUSIONS

IMPULSE can handle significantly larger number of SAR matrices and slices than conventional optimization algorithms, enabling the use of uncompressed or partially compressed SAR matrices to design pulses for a multislice scan in a practical time frame.

Evaluation of 3D radio-frequency electromagnetic fields for any matching and coupling conditions by the use of basis functions

A procedure for evaluating radio-frequency electromagnetic fields in anatomical human models for any matching and coupling conditions is introduced. The procedure resorts to the extraction of basis functions: such basis functions, which represent the fields produced by each individual port without any residual coupling, are derived through an algebraic procedure which uses the S parameter matrix and the fields calculated in one (only) full-wave simulation. The basis functions are then used as building-blocks for calculating the fields for any other S parameter matrix. The proposed approach can be used both for volume coil driven in quadrature and for parallel transmission configuration.

Electromagnetic characterization of an MR volume coil with multilayered cylindrical load using a 2-D analytical approach

We present an analytical method for the analysis of Radio Frequency (RF) volume coils for Magnetic Resonance Imaging (MRI), using a 2-D full wave solution with loading by multilayered cylinders. This allows the characterization of radio-frequency E, H, B1, B1(+) fields. Comparisons are provided with experimental data obtained at 7.0 T. The procedure permits us to clearly separate the solution to single line source problem (which we call the primordial solution) and the composite solution (i.e. full coil, i.e. the summations of primordial solutions according to the resonator drive configuration). The capability of separating the primordial solution and the composite one is fundamental for a thorough analysis of the phenomena of dielectric resonance, and of standing wave and multi-source interference. We show that dielectric resonance can be identified only by looking at the electromagnetic field from a single line source.