Neonatal brain and body imaging in the MR-compatible incubator

Comprehensive Neonatal Cardiac, Feed and Wrap, Non-contrast, Non-sedated, Free-breathing Compressed Sensing 4D Flow MRI Assessment

BACKGROUND

Cardiac MRI is an important imaging tool in congenital cardiac disease, but its use has been limited in the neonatal population as general anesthesia has been needed for breath-holding. Technological advances in four-dimensional (4D) flow MRI have now made nonsedated free-breathing acquisition protocols a viable clinical option, but the method requires prospective validation in neonates.

PURPOSE

To test the feasibility of compressed sensing (CS) 4D flow MRI in the neonatal population and to compare with standard previously validated two-dimensional (2D) phase-contrast (PC) flow MRI.

STUDY TYPE

Prospective, cohort, image quality.

POPULATION

A total of 14 healthy neonates (median [range] age: 2.5 [0-80] days; 8 male).

FIELD STRENGTH AND SEQUENCE

Noncontrast 2D cine gradient echo sequence with through-plane velocity encoding (PC) sequence and compressed sensing (CS) three-dimensional (3D), time-resolved, cine phase-contrast MRI with 3D velocity-encoding (4D flow MRI) at 3 T.

ASSESSMENT

Aortic 2D PC, and aortic, pulmonary trunk and superior vena cava CS 4D flow MRI were acquired using the feed and wrap technique (nonsedated) and quantified using commercially available software. Aortic flow and peak velocity were compared between methods. Internal consistency of 4D flow MRI was determined by comparing mean forward flow of the main pulmonary artery (MPA) vs. the sum of left and right pulmonary artery flows (LPA and RPA) and by comparing mean ascending aorta forward flow (AAo) vs. the sum of superior vena cava (SVC) and descending aorta flows (DAo).

STATISTICAL TESTS

Flow and peak-velocity comparisons were assessed using paired t-tests, with P < 0.05 considered significant, and Bland-Altman analysis. Interobserver and intraobserver agreement and internal consistency were analyzed by intraclass correlation co-efficient (ICC).

RESULTS

There was no statistically significant difference between ascending aortic forward flow between 2D PC and CS 4D Flow MRI (P = 0.26) with a bias of 0.11 mL (-0.59 to 0.82 mL) nor peak velocity (P = 0.11), with a bias of -5 cm/sec and (-26 to 16 cm/sec). There was excellent interobserver and intraobserver agreement for each vessel (interobserver ICC: AAo 1.00; DAo 0.94, SVC 0.90, MPA 0.99, RPA 0.98, LPA 0.96; intraobserver ICC: AAo 1.00; DAo 0.99, SVC 0.98, MPA 1.00, RPA 1.00, LPA 0.99). Internal consistency measures showed excellent agreement for both mean forward flow of main pulmonary artery vs. the sum of left and right pulmonary arteries (ICC: 0.95) and mean ascending aorta forward flow vs. the sum of superior vena cava and descending aorta flows (ICC: 1.00).

CONCLUSION

Sedation-free neonatal feed and wrap MRI is well tolerated and feasible. CS 4D flow MRI quantification is similar to validated 2D PC free-breathing imaging with excellent interobserver and intraobserver agreement.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Neonatal body magnetic resonance imaging: preparation, performance and optimization

Performing and optimizing MRI of the chest, abdomen and pelvis in neonates and young infants can be challenging. This is a result of several factors, including patient size, desire to avoid or minimize sedation/general anesthesia, and the relative rarity of these examinations. However, with proper preparation and protocol optimization, high-quality diagnostic images can be acquired that can aid in diagnosis and patient management. In addition, numerous special considerations arise when performing body MRI in neonates compared to older pediatric patients. This review article provides an update on the performance and optimization of MRI of the body in neonates and infants. Furthermore, the authors present common indications for neonatal body MRI and discuss the use of intravenous gadolinium-based contrast agents in this vulnerable patient population.