Free-breathing magnetic resonance imaging with radial k-space sampling for neonates and infants to reduce anesthesia

Practical strategies to improve MRI operations and workflow in pediatric radiology

Magnetic resonance imaging (MRI) is an essential tool in pediatric imaging. It offers detailed, high-contrast images without ionizing radiation, making it particularly suitable for children. Creating an efficient MRI service is challenging given the balancing priorities of image quality and scan time and the overlying logistical challenges, including MRI safety protocols, the need for sedation in certain patient populations, and flexibility to accommodate patients at different phases of care. This paper reviews practical strategies to improve MRI operations and workflows in pediatric radiology, emphasizing protocol standardization and customization, scheduling optimization, and identification of key performance indicators (KPIs). Operational data through dashboards and reports enable continuous quality assessment and improvement, while specialized staff training ensures high imaging and patient safety standards. The strategies outlined in this paper highlight the importance of a comprehensive, patient-centered approach to MRI operations. By prioritizing efficiency, quality, and patient care, radiology departments can improve diagnostic outcomes and patient experience.

French survey of sedation practices for pediatric magnetic resonance and computed tomography imaging

BACKGROUND

Pediatric magnetic resonance imaging (MRI) and computed tompgraphy (CT) require patient immobility and therefore often require sedation or general anesthesia of patients. Consensus on these procedures is lacking in France.

OBJECTIVE

Thus, the aim of this study was to describe the current sedation practices for pediatric MRI and CT in France.

MATERIAL AND METHODS

From January 2019 to December 2019, an online questionnaire was delivered by electronic mail to a representative radiologist in 60 pediatric radiology centers registered by the French-speaking pediatric and prenatal imaging society. Questions included protocols, drugs used, monitoring and side effects.

RESULTS

Representatives of 40 of the 60 (67%) radiology centers responded to the survey. Among them, 31 performed sedation including 17 (55%) centers where radiologists performed sedation without anesthesiologists present during the procedure. The premedication drugs were hydroxyzine (n = 8, 80%) and melatonin (n = 2, 20%), Sedation drugs used for children ages 0 to 6 years old were pentobarbital (n = 9, 60%), midazolam (n = 2, 13%), chloral hydrate (n = 2, 13%), diazepam (n = 1, 6.5%) and chlorpromazine (n = 1, 6.5%). A written sedation protocol was available in 10/17 (59%) centers. In 6/17 (35%) centers, no monitoring was used during the procedures. Blood pressure monitoring and capnography were rarely used (< 10%) and post-sedation monitoring was heterogeneous. No life-threatening adverse effect was reported, but 6 centers reported at least one incident per year.

CONCLUSION

For half of the responding radiology centers, radiologists performed sedation alone in agreement with the local anesthesiology team. Sedation procedures and monitoring were heterogenous among centers. Adjustment and harmonization of the practices according to the capacity of each center may be useful.

Chest examinations in children with real-time magnetic resonance imaging: first clinical experience

BACKGROUND

Real-time magnetic resonance imaging (MRI) based on a fast low-angle shot technique 2.0 (FLASH 2.0) is highly effective against artifacts caused due to the bulk and pulmonary and cardiac motions of the patient. However, to date, there are no reports on the application of this innovative technique to pediatric lung MRI.

OBJECTIVE

This study aimed to identify the limits of resolution and image quality of real-time lung MRI in children and to assess the types and minimal size of lesions with these new sequences.

MATERIALS AND METHODS

In this retrospective study, pathological lung findings in 87 children were classified into 6 subgroups, as detected on conventional MRI: metastases and tumors, consolidation, scars, hyperinflation, interstitial pathology and bronchiectasis. Subsequently, the findings were grouped according to size (4-6 mm, 7-9 mm and ≥ 10 mm) and evaluated for visual delineation of the findings (0 = not visible, 1 = hardly visible and 2 = well visualized).

RESULTS

Real-time MRI allows for diagnostic, artifact-free thorax images to be obtained, regardless of patient movements. The delineation of findings strongly correlates with the size of the pathology. Metastases, consolidation and scars were visible at 100% when larger than 9 mm. In the 7-9 mm subgroup, the visibility was 83% for metastases, 88% for consolidation and 100% for scars in T2/T1 weighting. Though often visible, smaller pathological lesions of 4-6 mm in size did not regularly meet the expected diagnostic confidence: The visibility of metastases was 18%, consolidation was 64% and scars was 71%. Diffuse interstitial lung changes and hyperinflation, known as "MR-minus pathologies," were not accessible to real-time MRI.

CONCLUSION

The method provides motion robust images of the lung and thorax. However, the lower sensitivity for small lung lesions is a major limitation for routine use of this technique. Currently, the method is adequate for diagnosing inflammatory lung diseases, atelectasis, effusions and lung scarring in children with irregular breathing patterns or bulk motion on sedation-free MRI. A medium-term goal is to improve the diagnostic accuracy of small nodules and interstitial lesions.

Respiratory Motion Management in Abdominal MRI: Radiology In Training

A 96-year-old woman had a suboptimal evaluation of liver observations at abdominal MRI due to significant respiratory motion. State-of-the-art strategies to minimize respiratory motion during clinical abdominal MRI are discussed.

State-of-the-art magnetic resonance imaging sequences for pediatric body imaging

Longer examination time, need for anesthesia in smaller children and the inability of most children to hold their breath are major limitations of MRI in pediatric body imaging. Fortunately, with technical advances, many new and upcoming MRI sequences are overcoming these limitations. Advances in data acquisition and k-space sampling methods have enabled sequences with improved temporal and spatial resolution, and minimal artifacts. Sequences to minimize movement artifacts mainly utilize radial k-space filling, and examples include the stack-of-stars method for T1-weighted imaging and the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER)/BLADE method for T2-weighted imaging. Similarly, the sequences with improved temporal resolution and the ability to obtain multiple phases in a single breath-hold in dynamic imaging mainly use some form of partial k-space filling method. New sequences use a variable combination of data sampling methods like compressed sensing, golden-angle radial k-space filling, parallel imaging and partial k-space filling to achieve free-breathing, faster sequences that could be useful for pediatric abdominal and thoracic imaging. Simultaneous multi-slice method has improved diffusion-weighted imaging (DWI) with reduction in scan time and artifacts. In this review, we provide an overview of data sampling methods like parallel imaging, compressed sensing, radial k-space sampling, partial k-space sampling and simultaneous multi-slice. This is followed by newer available and upcoming sequences for T1-, T2- and DWI based on these other advances. We also discuss the Dixon method and newer approaches to reducing metal artifacts.