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

Deep Learning in Knee MRI: A Prospective Study to Enhance Efficiency, Diagnostic Confidence and Sustainability

RATIONALE AND OBJECTIVES

The objective of this study was to evaluate a combination of deep learning (DL)-reconstructed parallel acquisition technique (PAT) and simultaneous multislice (SMS) acceleration imaging in comparison to conventional knee imaging.

MATERIALS AND METHODS

Adults undergoing knee magnetic resonance imaging (MRI) with DL-enhanced acquisitions were prospectively analyzed from December 2023 to April 2024. The participants received T1 without fat saturation and fat-suppressed PD-weighted TSE pulse sequences using conventional two-fold PAT (P2) and either DL-enhanced four-fold PAT (P4) or a combination of DL-enhanced four-fold PAT with two-fold SMS acceleration (P4S2). Three independent readers assessed image quality, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiomics features.

RESULTS

34 participants (mean age 45±17years; 14 women) were included who underwent P4S2, P4, and P2 imaging. Both P4S2 and P4 demonstrated higher CNR and SNR values compared to P2 (P<.001). P4 was diagnostically inferior to P2 only in the visualization of cartilage damage (P<.005), while P4S2 consistently outperformed P2 in anatomical delineation across all evaluated structures and raters (P<.05). Radiomics analysis revealed significant differences in contrast and gray-level characteristics among P2, P4, and P4S2 (P<.05). P4 reduced time by 31% and P4S2 by 41% compared to P2 (P<.05).

CONCLUSION

P4S2 DL acceleration offers significant advancements over P4 and P2 in knee MRI, combining superior image quality and improved anatomical delineation at significant time reduction. Its improvements in anatomical delineation, energy consumption, and workforce optimization make P4S2 a significant step forward.

Magnetic resonance imaging of masticatory muscles in patients with duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in children. Impairment of masticatory function and swallowing disorders, potentially leading to aspiration and gastrostomy, are linked to fatty infiltration in the masticatory muscles, as previously observed in muscle ultrasound. This study aims to quantify muscle volume and fat fraction in muscle magnetic resonance imaging (MRI) in the masticatory muscles in non-ambulant DMD patients compared to healthy controls and evaluate their correlation with maximum bite force (MBF), which has not been previously described. Fifteen patients with DMD and 16 controls were included. MBF was measured with an oral dynamometer and total muscle volume (TMV) and fat signal fraction (FSF) were quantified using MRI with the Dixon technique. Four DMD patients presented with masticatory or swallowing difficulties. DMD patients had a significantly lower median MBF (141.8 N) compared with healthy controls (481.6 N, p < 0.0001). Additionally, median FSF was significantly higher in DMD patients (47.07 %) compared to controls (5.31 %, p < 0.0001). A strong negative correlation between TMV and MBF was observed in DMD patients (ρ = -0.70, p = 0.0048). A significant negative correlation between MBF and normalized FSF was observed in healthy controls (ρ = -0.5487, p = 0.300) and DMD patients (ρ = -0.5893, p = 0.0224). A non-significant positive correlation between age and FSF in DMD was detected (ρ = 0.38, p = 0.17). MBF, TMV and FSF quantified with the Dixon MRI are sensitive measures to evaluate masticatory function in DMD patients and may serve as biomarkers for clinical follow up. Studies in older patients are needed to evaluate the predictive role of MBF, TMV and FSF in the nutritional status of patients and the need for therapeutic interventions such as gastrostomy.

International standardization of pediatric magnetic resonance imaging protocols: creation of the World Federation of Pediatric Imaging MR Protocols Committee

The World Federation of Pediatric Imaging (WFPI) MR Protocols Committee was formed in response to the critical need for standardized magnetic resonance imaging (MRI) protocols tailored specifically for pediatric populations. This initiative addresses the inherent challenges and variabilities in pediatric MRI practices due to the unique physiological and anatomical characteristics of children, which often result in extended scan times, increased costs, and greater need for sedation. The committee, comprising a diverse group of international radiologists, pediatric imaging societies, and major MRI vendors, collaboratively developed a comprehensive set of MRI protocols. These protocols are designed to enhance diagnostic accuracy, reduce sedation use, and streamline workflows, thereby minimizing healthcare disparities across global regions. Protocols cover a wide range of applications, including neuroradiology, abdominal imaging, and musculoskeletal conditions, with specific focus on practical implementation in both high-resource and resource-limited settings. After rigorous development and refinement through global feedback, these protocols have been made accessible through the WFPI website and will be directly integrated into MRI systems via vendor collaborations. These protocols provide a flexible, foundational approach that can be adapted to suit the needs of centers worldwide. This ensures that even basic protocols are accessible across different settings, allowing customization based on available resources and specific clinical demands.

Neonatal Liver Imaging: Techniques, Role of Imaging, and Indications

The neonatal liver may be affected by a variety of congenital and acquired diseases. Imaging has an important role in the workup and management of many neonatal hepatic abnormalities. Some aspects of imaging the liver and imaging findings are specific to neonatal patients when compared with those in older children. Therefore, selecting and tailoring the imaging technique for each indication in the neonate is important for optimal care, with minimal invasiveness. Common indications for imaging include incidental focal lesions, neonatal liver failure, cholestasis, and sepsis. US is the primary imaging modality, and for most conditions it is the only imaging modality required. MRI is the next modality after US for neonatal liver assessment and is especially required for complete assessment and staging of neoplasms, vascular abnormalities, and diagnosis of neonatal hemochromatosis. CT can be used when MRI is not available and should be used sparingly and in patients with acute conditions such as intra-abdominal bleeding. The authors emphasize imaging modalities that can be used for assessment of neonatal liver abnormalities, the imaging appearances of normal and changing structures in the neonatal liver, and indications for imaging. Abnormalities that are described include neonatal liver failure, infections, hepatic calcifications, umbilical venous catheter-related complications, and vascular abnormalities. ©RSNA, 2024 Supplemental material is available for this article.

Magnetic resonance imaging of the musculoskeletal system in the diagnosis of rheumatic diseases in the pediatric population

Magnetic resonance imaging (MRI) of the musculoskeletal system is an examination increasingly performed for suspected juvenile idiopathic arthritis, chronic nonbacterial osteomyelitis and juvenile idiopathic inflammatory myopathies, as well as other rheumatic diseases of developmental age. T1-, T2- and PD-weighted with or without fat suppression or short tau inversion recovery/turbo inversion recovery magnitude (STIR/TIRM) sequences and post-contrast sequences are evaluated to diagnose pathological changes in the synovial membrane, subchondral bone marrow and surrounding soft tissues. Magnetic resonance imaging allows detection of synovitis, tenosynovitis, bursitis, and enthesitis as well as bone marrow edema and soft tissue edema. Several pediatric-specific MRI scoring systems have been developed and validated to standardize and facilitate the assessment of the extent of the inflammatory process and disease activity in MRI. Early detection of inflammatory changes allows the inclusion of comprehensive pharmacotherapy giving the possibility of permanent remission and objective measurement of the effectiveness of treatment.

Improving image quality using the pause function combination to PROPELLER sequence in brain MRI: a phantom study

While some MRI systems offer a "pause" function, combining it with the PROPELLER method for image quality improvement remains underexplored. This study investigated whether repositioning the head after pausing during PROPELLER imaging enhances image quality. All brain phantom images in this study were obtained using a 3.0 T MRI and acquired using the fast spin-echo T2WI-based PROPELLER with motion correction. By combining the angle of rotational motion of the head phantom and the number of repositioning after a pause, two studies including seven trials were performed. Increasing the rotation angle decreased the image quality; however, pausing the image and repositioning the head phantom to the original angle improved the image quality. A similar result was obtained by repositioning the angle closer to its original angle. Experiments with multiple head movements showed that pausing the scan and repositioning the phantom with each movement improved image quality.

Advantages of 3D High-Resolution Vessel Wall Imaging in a Patient With Blood Blister-Like Aneurysm: A Case Report and Literature Review

Blood blister-like aneurysms (BBAs) are rare and challenging intracranial aneurysms. They pose significant diagnostic and surgical risks due to their delicate walls. Accounting for a small percentage of intracranial aneurysms, BBAs are pathologically pseudoaneurysms, often resulting from arterial dissection, with a high tendency to rupture. This report underscores the critical nature of BBAs by reviewing a case in which subarachnoid hemorrhage caused by a BBA rupture was difficult to diagnose with conventional imaging. We highlight the efficacy of three-dimensional (3D) high-resolution vessel wall imaging (VWI) in discerning the subtle vascular abnormality of BBAs. The integration of the black-blood imaging technique within VWI provides superior contrast between the aneurysm and surrounding tissues, facilitating clearer visualization of the aneurysmal wall. The use of 3D T1-weighted imaging provides intricate details of the vessel wall including its contrast enhancement, which is crucial for a comprehensive assessment of a ruptured aneurysm. This case is consistent with the existing literature, supporting the role of VWI in the identification of ruptured BBAs, an area with limited but growing information on its diagnostic value. VWI is precise and accurate in the preoperative diagnosis of BBAs, emphasizing its potential to improve patient management and outcomes, especially in conditions with high risks of morbidity and mortality.

Feasibility of deep learning-reconstructed thin-slice single-breath-hold HASTE for detecting pancreatic lesions: A comparison with two conventional T2-weighted imaging sequences

Objective

The objective of this study was to evaluate the clinical feasibility of deep learning reconstruction-accelerated thin-slice single-breath-hold half-Fourier single-shot turbo spin echo imaging (HASTEDL) for detecting pancreatic lesions, in comparison with two conventional T2-weighted imaging sequences: compressed-sensing HASTE (HASTECS) and BLADE.

Methods

From March 2022 to January 2023, a total of 63 patients with suspected pancreatic-related disease underwent the HASTEDL, HASTECS, and BLADE sequences were enrolled in this retrospectively study. The acquisition time, the pancreatic lesion conspicuity (LCP), respiratory motion artifact (RMA), main pancreatic duct conspicuity (MPDC), overall image quality (OIQ), signal-to-noise ratio (SNR), and contrast-noise-ratio (CNR) of the pancreatic lesions were compared among the three sequences by two readers.

Results

The acquisition time of both HASTEDL and HASTECS was 16 s, which was significantly shorter than that of 102 s for BLADE. In terms of qualitative parameters, Reader 1 and Reader 2 assigned significantly higher scores to the LCP, RMA, MPDC, and OIQ for HASTEDL compared to HASTECS and BLADE sequences; As for the quantitative parameters, the SNR values of the pancreatic head, body, tail, and lesions, the CNR of the pancreatic lesion measured by the two readers were also significantly higher for HASTEDL than for HASTECS and BLADE sequences.

Conclusions

Compared to conventional T2WI sequences (HASTECS and BLADE), deep-learning reconstructed HASTE enables thin slice and single-breath-hold acquisition with clinical acceptable image quality for detection of pancreatic lesions.

Feasibility of online radial magnetic resonance imaging for adaptive radiotherapy of pancreatic tumors

Background and purpose

Online adaptive magnetic resonance (MR)-guided treatment planning for pancreatic tumors on 1.5T systems typically employs Cartesian 3D T ₂w magnetic resonance imaging (MRI). The main disadvantage of this sequence is that respiratory motion results in substantial blurring in the abdomen, which can hamper delineation accuracy. This study investigated the use of two motion-robust radial MRI sequences as main delineation scan for pancreatic MR-guided radiotherapy.

Materials and methods

Twelve patients with pancreatic tumors were imaged with a 3D T ₂w scan, a Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) scan (partially overlapping strips), and a 3D Vane scan (stack-of-stars), on a 1.5T MR-Linac under abdominal compression. The scans were assessed by three radiation oncologists for their suitability for online adaptive delineation. A quantitative comparison was made for gradient entropy and the effect of motion on apparent target position.

Results

The PROPELLER scans were selected as first preference in 56% of the cases, the 3D T ₂w in 42% and the 3D Vane in 3%. PROPELLER scans sometimes contained a large interslice variation which would have compromised delineation. Gradient entropy was significantly higher in 3D T ₂w patient scans. The apparent target position was more sensitive to motion amplitude in the PROPELLER scans, but substantial offsets did not occur under 10 mm peak-to-peak.

Conclusion

PROPELLER MRI may be a superior imaging sequence for pancreatic MRgRT compared to standard Cartesian sequences. The large interslice variation should be mitigated through further sequence optimization before PROPELLER can be adopted for online treatment adaptation.