Major depressive disorder (MDD) is a psychiatric disorder that leads to reduced quality of life and poses a significant societal burden; however, its diagnosis still relies on subjective evaluation. Consequently, task-based functional magnetic resonance imaging (fMRI) has emerged as a crucial tool for exploring the neurobiological mechanisms of MDD and identifying objective biomarkers. This review systematically examines fMRI studies on cognitive dysfunction in patients with MDD, summarizing the representative tasks and associated functional abnormalities in neural circuits across three core domains: executive function, negative bias, and reward processing. Deficits in executive function manifest as inefficiency in the fronto-parietal network and failure to suppress the default mode network during n-back and Stroop tasks. Negative bias was identified through the Self-Referent Encoding Task and Autobiographical Memory Test, revealing hyperactivity in bottom-up emotional responses and failure of top-down regulation. In the domain of reward processing, studies using Monetary Incentive Delay and reinforcement learning tasks have consistently reported that blunted reward prediction error signals and hypoactivation of the thalamo-striatal-prefrontal circuitry are associated with anhedonia. By integrating these findings from task-based fMRI research, this review aimed to define the neurocognitive characteristics that distinguish MDD and provide practical guidance for future studies.

Extraskeletal Ewing sarcoma (EES) is a rare, malignant small round-cell tumor, and involvement of the spinal epidural space is unusual. Here, we report a case of spinal epidural EES in a 46-year-old man who presented with back pain. Magnetic resonance imaging revealed a dumbbell-shaped right paravertebral mass extending through the ipsilateral neural foramen, with focal bone marrow infiltration. After surgical resection and adjuvant chemoradiotherapy, progressive bone marrow involvement and vertebral metastasis were observed on follow-up imaging. This case highlights the diagnostic challenges of epidural EES and underscores the importance of recognizing bone marrow involvement, which is rare in EES.

Hepatic angiomyolipoma is a rare benign tumor that often mimics hepatocellular carcinoma on imaging. Here, we report a rare case of hepatic angiomyolipoma with extensive hemorrhagic degeneration, resulting in a large hemorrhagic component that mimicked a complicated cystic neoplasm. A 43-year-old woman presented with mild abdominal distension, and imaging revealed a 16-cm multiloculated cystic mass in the left hepatic lobe. Computed tomography revealed a thick, enhancing wall and septa with hyperattenuating internal fluid. On gadoxetic acid-enhanced magnetic resonance imaging, arterial enhancement was observed along the thick wall, and a subtle opposedphase signal drop indicated a small fat component that was initially missed. Laparoscopic left lobectomy was performed under suspicion of a malignant cystic neoplasm. Histopathological examination revealed an angiomyolipoma composed of thick-walled vessels, spindle-shaped muscle bundles, and scant adipocytes, with human melanoma black 45 positivity and absence of an epithelial lining, consistent with hemorrhagic degeneration. This case highlights how hemorrhagic degeneration can pose a significant diagnostic challenge by masking the typical features of hepatic angiomyolipoma, leading to diagnostic confusion with complicated cystic tumors.

Purpose: The accurate localization of bifurcation points in the brain near the circle of Willis is essential for labeling cerebral arteries and detecting potential aneurysms. Studies on the development of segmentation-based landmark localization methods for cerebral angiography are lacking. This study aimed to develop and validate a method for localizing anatomical landmarks using a three-dimensional (3D) encoder-decoder deep convolutional neural network architecture. Materials and Methods: Time-of-flight magnetic resonance angiography (MRA) images of 224 subjects obtained from publicly available datasets were used. Ten anatomical landmark points were annotated, and four different landmark subset configurations were trained and validated. For each configuration, 3D U-Net-based models were developed using the MRA images and their corresponding annotated landmarks. The deep learning prediction results were evaluated in terms of landmark localization errors. Results: Among the four configurations, the configuration with five landmark subsets produced the smallest landmark localization errors in the test dataset. Post-processing of the U-Net-predicted segmentation masks further reduced the mean localization errors across all landmark points for the configuration with five subsets. Conclusion The proposed landmark localization method effectively identified major anatomical landmarks around the circle of Willis and showed the potential to automate segmental analyses of intracranial arterial tortuosity.

Purpose: To characterize the electromagnetic (EM) behavior of a monopole and dipole hybrid (MDH) antenna and evaluate its performance relative to monopole and dipole antennas for 10.5 tesla (T) magnetic resonance imaging (MRI) applications. Materials and Methods: Full-wave EM simulations were performed to model an inductor-shortened 20-cm dipole and an MDH antenna with asymmetric 9-cm and 12-cm poles. Single elements and 16-channel arrays were arranged on cylindrical formers (inner diameter 25 cm) around a tissue-mimicking phantom (εr = 49, σ = 0.6 S/m, diameter = 18 cm, height = 30 cm) with ~4 cm inter-element spacing and no additional decoupling circuitry. The eight-channel monopole antenna and MDH arrays were further modeled and analyzed with and without coaxial feed cables to assess cable-induced effects on magnetic (B) field distribution. Relative individual transmit field maps of the 8-channel monopole antenna and MDH arrays were acquired on a 10.5 T MRI system using a gradient echo (GRE) sequence (repetition time [TR] = 4000 ms, echo time [TE] = 3.0 ms, acquisition time [TA] = 7:48 ms, flip angle = 60°, field of view [FOV] = 354 × 354 mm3 , resolution = 3.0 × 1.5 × 3.0 mm3 ). Results: The MDH antenna demonstrated enhanced longitudinal B-field concentration and improved directivity compared with the dipole antenna element. Across the 8- and 16-channel arrays, the MDH structures consistently exhibited lower coupling, reducing S 21 by up to 10 dB relative to the monopole and dipole antenna arrays. Cable attachment significantly altered the MDH field patterns, reflecting dipole-like sensitivity to commonmode currents; however, appropriate cable management preserved field stability. Conclusion The MDH antenna provides intrinsic decoupling advantages and robust multichannel behavior without requiring additional decoupling circuitry. These characteristics make the MDH architecture a strong candidate for next-generation high-density arrays for ultra-high field MRI.

Purpose: To evaluate several hybrid multi-element configurations to enhance B1+ effi-ciency, defined as the transmit magnetic field generated by the radiofrequency (RF) coil normalized by the net input power, and spatial coverage for 10.5 tesla (T) human brain imaging. Materials and Methods: Finite-difference time-domain simulations were performed using an anatomically detailed human head model to assess circularly polarized B1+ fieldsgenerated by 8-channel loop, dipole antenna, and monopole and dipole hybrid antenna (MDH) arrays. These baseline designs were extended to 16-channel arrays combining loops with dipole antennas or MDHs and to interleaved MDH-based arrays incorporating axially displaced dipole or monopole antennas. Results: The 8-channel MDH array yielded the highest central B1+ efficiency, exceedingloop and dipole antenna arrays by 38.5% and 33.3%, respectively, but peripheral coverage remained limited. The 16-channel loop + dipole antenna and loop + MDH arrays improved overall B1+ efficiency by up to 28.9% relative to their 8-channel counterparts.Interleaved combined structure arrays further enhanced peripheral excitation and superior–inferior coverage, with the T-shaped monopole antenna + MDH configuration achieving a high central efficiency. Conclusion MDH-centered combined structure arrays effectively balance deep-field efficiency and peripheral coverage at 10.5 T. Interleaving monopole antenna-type elements beneath MDHs provides additional improvement and represents a promising design pathway for achieving more uniform excitation in 10.5 T brain imaging.

Acute lymphoblastic leukemia (ALL) primarily affects the bone marrow and peripheral blood. Extramedullary manifestations, especially in the sinonasal cavity, are rare and difficult to diagnose. We report a case of B-cell ALL in a 4-year-old girl who initially presented with a sinonasal mass mimicking a primary malignant neoplasm. The patient developed right eye protrusion upon nasal blowing over a period of 2 weeks. Imaging studies revealed an aggressive-appearing mass in the right maxillary sinus with extensive local invasion. The radiologic differential diagnosis included rhabdomyosarcoma, lymphoma, and other pediatric sinonasal malignancies. Histopathologic examination of the biopsy specimen and subsequent bone marrow evaluation established the diagnosis of B-cell ALL with BCR/ABL1 fusion. This case highlights the importance of including ALL in the differential diagnosis of sinonasal masses in pediatric patients, particularly when imaging features suggest an aggressive malignancy accompanied by hematologic abnormalities. A comprehensive evaluation, including imaging studies, routine laboratory tests, tissue biopsy, and bone marrow examination, is crucial for establishing an accurate diagnosis and initiating appropriate treatment.

Purpose: Cerebellar maturation is critical for neonatal development and is often disrupted during preterm birth. This study used magnetic resonance (MR) fingerprinting to quantify age-related cerebellar changes and determine the specific impact of prematurity. Materials and Methods: This retrospective study included 31 neonates (22 preterm and 9 term; 17 males; mean gestational age, 249.0 ± 20.7 days) who underwent brain MRI, including 2D multi-slice MR fingerprinting with 7 minutes 5 seconds scan time at termequivalent age. The T1 and T2 relaxation times were measured in the middle cerebellar peduncle, dentate nucleus, and cerebellar cortex using MR fingerprinting-derived T1 and T2 maps. Group differences and correlations with postmenstrual age were assessed using independent t-tests and Pearson’s correlation analysis. Results: Preterm neonates had longer T1 and T2 relaxation times in the middle cerebellar peduncle, dentate nucleus, and cerebellar cortex than did term neonates. In the middle cerebellar peduncle, T1 times were 1918 ± 88 ms vs. 1760 ± 68 ms (p < 0.001), and T2 times were 103 ± 8 ms vs. 97 ± 4 ms (p < 0.05). In the dentate nucleus, the T1 times were 2316 ± 174 ms vs. 1976 ± 144 ms (p < 0.001), and the T2 times were 141 ± 18 ms vs. 122 ± 11 ms (p < 0.05). In the cerebellar cortex, T1 was 2460 ± 98 ms vs. 2192 ± 127 ms (p < 0.001), and T2 was 152 ± 14 ms vs. 127 ± 23 ms (p < 0.05). Both T1 and T2 times negatively correlated with postmenstrual age across all regions (r ranged from -0.761 to -0.617, all p < 0.001). Prolonged relaxation times were associated with prematurity (odds ratio range: 1.03 to 1.16, p < 0.05). Conclusion The MR fingerprinting-derived T1 and T2 relaxation times showed developmental changes with postmenstrual age and were higher in preterm neonates, indicating immaturity.

Purpose: To assess the accuracy of supraspinatus muscle fat fraction and atrophy measured on the Y-view compared with the newly proposed fossa-view sagittal MRI plane. Materials and Methods: This study included 84 patients (36 male; mean age, 65.1 ± 10.1 years) who underwent shoulder MRI with extended oblique sagittal T1-weighted and three-dimensional (3D) six-echo Dixon imaging between December 2020 and November 2022. The reference fat fraction was calculated by integrating voxel-wise Dixon values, while supraspinatus muscle volume was quantified using a 3D nnU-Net algorithm and normalized to the scapular volume to derive the standardized muscle index (SMI). Fat fraction and cross-sectional area were quantified on the Y-view and fossaview and compared with the reference values. Subgroup analyses were performed using fatty degeneration and retraction grades. Results: Agreement with the reference fat fraction was significantly higher for the fossa-view (intraclass correlation coefficient [ICC], 0.923) than for the Y-view (ICC, 0.822;p = 0.006). The fossa-view showed smaller deviations and narrower limits of agreement.For SMI, the Y-view (ICC, 0.782) showed higher agreement than the fossa-view (ICC, 0.694), although the difference was not statistically significant (p = 0.219). Subgroup analyses showed better Y-view performance at lower retraction grades and better fossa-view performance at higher grades, although the differences were not statistically significant (all p > 0.05). Conclusion Both planes reliably quantified the fat fraction with greater accuracy in the fossa-view. However, single-plane assessment of muscle atrophy was less reliable, underscoring the need for MRI evaluation of the entire muscle.

Magnetic resonance (MR) enterography (MRE) plays a pivotal role in the management of patients with Crohn’s disease (CD) throughout the chronic disease process. With advantages such as its non-invasiveness and the ability to use several MR sequences to reflect findings of active inflammation, several MRE-based indices have been introduced to assess CD inflammatory activity. Although there is no universally accepted gold-standard score for clinical practice, the most studied scores include the Magnetic Resonance Index of Activity, simplified Magnetic Resonance Index of Activity, Nancy score, Clermont score, London score, and CD MRI Index. These MRE-based scoring systems share certain characteristics but also differ in terms of the imaging parameters included, the bowel segments evaluated, and the MR sequences required for assessment. This review article covers the key MR findings of active inflammation incorporated into these scoring systems, along with the detailed characteristics and clinical applications of MRE-based scoring systems in adult patients with CD.