Faculty Bibliography

OBJECTIVE:This study aims to determine the diagnostic performance of sub-5-min combined sixfold parallel imaging (PIx3)-simultaneous multislice (SMSx2)-accelerated deep learning (DL) super-resolution 3T knee MRI in children and adolescents. MATERIALS AND METHODS/METHODS:Children with painful knee conditions who underwent PIx3-SMSx2-accelerated DL super-resolution 3T knee MRI and arthroscopy between October 2022 and December 2023 were retrospectively included. Nine fellowship-trained musculoskeletal radiologists independently scored the MRI studies for image quality and the presence of artifacts (Likert scales, range: 1 = very bad/severe, 5 = very good/absent), as well as structural abnormalities. Interreader agreements and diagnostic performance testing was performed. RESULTS:Forty-four children (mean age: 15 ± 2 years; range: 9-17 years; 24 boys) who underwent knee MRI and arthroscopic surgery within 22 days (range, 2-133) were evaluated. Overall image quality was very good (median rating: 5 [IQR: 4-5]). Motion artifacts (5 [5-5]) and image noise (5 [4-5]) were absent. Arthroscopy-verified abnormalities were detected with good or better interreader agreement (κ ≥ 0.74). Sensitivity, specificity, accuracy, and AUC values were 100%, 84%, 93%, and 0.92, respectively, for anterior cruciate ligament tears; 71%, 97%, 93%, and 0.84 for medial meniscus tears; 65%, 100%, 86%, and 0.82 for lateral meniscus tears; 100%, 100%, 100%, and 1.00 for discoid lateral menisci; 100%, 95%, 96%, and 0.98 for medial patellofemoral ligament tears; and 55%, 100%, 98%, and 0.77 for articular cartilage defects. CONCLUSION/CONCLUSIONS:Clinical sub-5-min PIx3-SMSx2-accelerated DL super-resolution 3T knee MRI provides excellent image quality and high diagnostic performance for diagnosing internal derangement in children and adolescents.

OBJECTIVES/OBJECTIVE:Metal artifact reduction MRI can exceed specific absorption rate (SAR) limits due to high-bandwidth radiofrequency pulses, causing scan interruptions and prolonged acquisition times. The aim of the current study is to reduce SAR and potentially scan time in metal artifact reduction MRI using an optimized variable refocusing flip angle (VRFA) scheme compared with the standard constant refocusing flip angle (CRFA). MATERIALS AND METHODS/METHODS:Three VRFA variants (VRFA1 to VRFA3) were developed to maximize tissue signal and contrast while minimizing SAR and image blur. The optimal variant was selected through quantification of metal artifacts and image blur in phantoms and tissue signal in a volunteer. Patients with hip arthroplasty underwent CRFA and optimal VRFA imaging using high-bandwidth turbo-spin-echo (HBW-TSE) and compressed-sensing slice-encoding-for-metal-artifact-correction (CS-SEMAC) sequences. Three readers ranked paired CRFA and VRFA scans for quality. Analyses included repeated measures ANOVA, noninferiority testing, and paired t/Wilcoxon signed-rank tests. RESULTS:CRFA and VRFA1 to VRFA3 showed no significant differences in image blur (full-width-at-half-maximum, mean ± SD, 1.9 ± 0.2 vs 1.9 ± 0.2 vs 1.9 ± 0.3 vs 1.9 ± 0.3 pixels, P = 0.06) or metal artifacts (8.2 ± 2.8 vs 8.4 ± 2.7 vs 8.4 ± 2.6 vs 8.4 ± 2.7 pixels, P = 0.57). The optimal VRFA variant (VRFA3) preserved 81% of CRFA fat-muscle contrast at 77% SAR and 70% scan time on proton-density (PD), and 94% of fluid-muscle contrast at 80% SAR and 67% scan time on short-tau-inversion-recovery (STIR). In 23 patients [mean age, 67.3 y ± 12.2 (SD); 14 females], the optimal VRFA was noninferior to CRFA in all quality metrics (all 95% CI < noninferiority margin = 0.1) and significantly reduced SAR (mean, PD-HBW-TSE/STIR-HBW-TSE/PD-CS-SEMAC/STIR-CS-SEMAC: 1.11/1.35/1.17/1.18 vs 1.85/1.83/1.49/1.46 W/kg, all P ≤ 0.001). In HBW-TSE, reduced SAR allowed longer echo trains and 15% to 32% shorter scan times. CONCLUSION/CONCLUSIONS:Metal artifact reduction MRI with VRFA reduces SAR without compromising image quality. It allows shorter acquisitions in HBW-TSE.

OBJECTIVES/OBJECTIVE:To perform a Delphi-based consensus on published evidence on image-guided injections for facet joint pain (FJP) and provide clinical indications. METHODS:We report the results of an evidence-based Delphi consensus of 38 experts from the European Society of Musculoskeletal Radiology and the European Society of Neuroradiology, who reviewed the published literature for evidence on image-guided injections for FJP. Experts drafted a list of statements and graded them according to the Oxford Centre for evidence-based medicine levels of evidence. Consensus was considered strong when ≥ 95% of experts agreed with the statement or broad when > 80% but < 95% agreed. The results of the consensus were used to write the paper. RESULTS:Twenty statements on image-guided FJP treatment have been drafted. Eighteen statements received strong consensus, while two received broad consensus. Three statements reached the highest level of evidence, all of them regarding the lumbar spine. All radiological methods are used for image-guided injections for FJP, and regardless of the radiological method used, all show good safety and efficacy. Facet joint injections and medial branch blocks are used in all spinal regions to treat FJP, and both show similar clinical outcomes. Advanced technological solutions have been studied in the field of lumbar FJP; however, the level of evidence for these is low. CONCLUSION/CONCLUSIONS:Despite promising results reported by published papers on image-guided injections for FJP, there is still a lack of evidence on injection efficacy, appropriateness of imaging methods, and optimal medication. KEY POINTS/CONCLUSIONS:Question Image-guided injections to treat facet joint pain (FJP) are performed throughout the spine; however, the highest level of evidence exists for the lumbar spine. Findings Regardless of the imaging method used, image-guided injections for facet joint pain treatment are safe, with only minor adverse events in rare cases. Clinical relevance All imaging methods are used for injection guidance to treat FJP, each with advantages and disadvantages. These statements on image-guided injections for FJP provide a concise and up to date overview on the topic, serving as a list of clinical indications.

MR neurography offers a specialized approach for detailed nerve imaging when clinical symptoms indicate involvement. Imaging peripheral nerves in the foot and ankle is demanding due to their small size and challenging anatomy. This article provides an overview of foot and ankle nerve assessment, highlighting the importance of technical expertise and anatomic knowledge for accurate diagnosis.

OBJECTIVE:To evaluate the Neuropathy Score-Reporting and Data System (NS-RADS) MRI grading system in conjunction with electrodiagnostic (EDx) testing for radial neuropathy at the elbow. MATERIALS AND METHODS/METHODS:Patients presenting between 2010 and 2023 with suspected radial neuropathy who underwent both EDx testing in the form of electromyography and nerve conduction studies and MRI within a 12-month period were evaluated. Three blinded radiologists used the NS-RADS grading system to evaluate nerve entrapment (E grades), muscle denervation (M grades) proximally within the supinator/extensor carpi radialis brevis (ECRB), and more distally within the forearm extensor muscles. These grades and the presence of lateral epicondylitis were then correlated with EDx abnormalities. RESULTS:Forty-nine participants were included. Inter-reader reliability for M grades in the forearm extensor muscles was good (ICC = 0.90 [95% CI = 0.83 - 0.94], p < 0.001), as was reliability for the supinator/ECRB muscles (ICC = 0.91 [95% CI = 0.86-0.95], p < 0.001). Inter-reader reliability for E grades was moderate (ICC = 0.83 [95% CI = 0.69-0.90], p < 0.001). Patients with positive EDx studies had a significantly different distribution of M grades for the forearm extensors and supinator/ECRB than those with negative studies (all p values < 0.001). However, overall consensus reads showed no significant difference in the distribution of E grades between patients with positive and negative EDx studies. CONCLUSION/CONCLUSIONS:Muscle grading strongly correlated with EDx positivity, with a high level of inter-reader agreement for muscle denervation-related alterations. Nerve grading, however, did not show a statistical correlation.

PURPOSE/OBJECTIVE:mapping technique for imaging of body parts containing metal hardware, based on magnitude images acquired with turbo spin echo (TSE) pulse sequences. THEORY AND METHODS/METHODS:values were validated against gradient-recalled and spin echo dual angle methods, as well as a vendor-provided TurboFLASH-based mapping sequence, in gel phantoms and human subjects without and with metal implants. RESULTS:shimming. CONCLUSION/CONCLUSIONS:values in regions near metal hardware, overcoming susceptibility-related and narrow-range limitations of standard mapping techniques.