Lauren W. Averill

Major depressive disorder (MDD) is one of the most prevalent mental diseases; early intervention and treatment are crucial. Unfortunately, the complexity of this disorder makes timely intervention challenging. A clear understanding of the biochemical mechanisms in depression will benefit the diagnosis, stratification, and treatment of prevalent mental disorders. One chemical pathway that has attracted interest is the kynurenine (KYN) pathway, which plays several complex roles in the human body, including regulating immune and inflammatory responses. Dysregulated tryptophan metabolism is widely involved in neuropsychiatric disorders, including depression. Decreased tryptophan and its metabolites and the imbalance between the neuroprotective and neurotoxic arms of the KYN pathway are consistently found in patients with major depression. Tryptophan-based radiotracers provide valuable information in studying whole-body tryptophan depletion-related depression and antidepressant mechanisms. Understanding the relationship between the peripheral and central KYN pathway and the biological mechanisms underlying the heterogeneous symptoms with functional imaging in depression is a pivotal part of enhancing potential patient stratification, developing effective diagnostic tools for subtypes, guiding personalized drug development, and improving treatment strategies. We review tryptophan-based radiopharmaceuticals in the study of depression. We summarize the key findings, noting both broad consensus and inconsistencies, as well as limitations. Finally, we offer our perspective on the future development of tryptophan radiopharmaceuticals in guiding depression diagnosis, targeted interventions, treatment evaluation, and drug development in these prevalent mental disorders.

Cerebrospinal fluid (CSF) shunts are critical for managing hydrocephalus by diverting excess CSF from the craniospinal axis to absorptive sites. Imaging plays a pivotal role in the assessment of shunt function, early postoperative changes, and a wide array of complications. Understanding the imaging characteristics of both normal postoperative appearances and potential complications with different imaging modalities enhances diagnostic accuracy and enables timely clinical management. This comprehensive review outlines the anatomical and functional aspects of various shunt systems.

Mucopolysaccharidosis IVA (Morquio A) is a progressive lysosomal disorder caused by a deficiency of N‐acetylgalactosamine‐6‐sulfate sulfatase, resulting in the accumulation of glycosaminoglycans, primarily in cartilage and bone. The condition leads to skeletal dysplasia, impaired ossification, and growth imbalance, causing cervical compression, tracheal obstruction, hip dysplasia, and cardiopulmonary complications. Although existing natural history studies have clarified several aspects of disease progression, objective methods to quantify skeletal pathology and its functional impact remain limited. Standard endurance‐based assessments, including the 6‐min walk test, 3‐min stair climb, and spirometry, are variable and infeasible for young children, wheelchair‐dependent individuals, or patients with respiratory or postoperative limitations. Their dependence on motivation, training, and site‐specific differences restricts their value as reliable endpoints. Significant gaps persist in the objective evaluation of skeletal dysplasia progression and its functional impact. There remains an unmet need for non‐invasive, quantitative tools that capture multisystem involvement across the full phenotypic spectrum. Objective tools exist as we reported but have not been widely implemented or standardized, and data supporting their use as regulatory endpoints remain limited. Emerging longitudinal, multidisciplinary evaluations and surrogate biochemical biomarkers show potential to define disease severity, support prognosis, and serve as validated endpoints for therapeutic monitoring and surgical risk stratification. In conclusion, to address the limitations of prior studies, we propose a novel natural history program of innovative, non‐invasive assessments based on our compiled data. Such approaches may contribute to more consistent longitudinal data and help inform the development of clinical endpoints for emerging therapies.

Radiopharmaceutical therapy (RPT) has emerged as a transformative modality in oncology, particularly for patients with metastatic or inoperable tumors. By leveraging molecularly targeted carriers conjugated to cytotoxic radionuclides, RPT enables precise delivery of ionizing radiation to tumor sites while minimizing off-target effects. Central to this approach are alpha (α) and beta (β) particle-emitting radionuclides. This review aims to provide a comprehensive overview of all clinically relevant alpha and beta emitters and incorporates the most recent advances from 2017–2025, offering a comprehensive and up-to-date perspective. Alpha and beta emitters hold significant promises for the future, especially in nuclear medicine, energy, and environmental monitoring. Medically, these emitters are at the forefront of targeted radiotherapy, offering new hope for cancer treatment. Alpha emitters such as Actinium-225 and Radium-223 are gaining attention for their high linear energy transfer, which allows them to effectively kill cancer cells while minimizing damage to surrounding healthy tissues. Beta emitters, including Lutetium-177 and Iodine-131, are already widely used for treating thyroid cancer, neuroendocrine tumors, and prostate cancer. They offer a longer range in tissue penetration than alpha particles, making them suitable for larger or more diffuse tumors. Alpha and beta emitters hold tremendous promise in targeted radiotherapy. However, current research is limited by an incomplete understanding of resistance pathways, insufficient long-term safety and efficacy data, and underdeveloped personalized treatment frameworks. As production technologies improve and safety protocols advance, these emitters will likely play an even more prominent role in both health care and scientific innovation.

Purpose The objective of this study was to report our experience using ultrasound guidance for percutaneous needle quadricepsplasty in patients with arthrogryposis multiplex congenita and congenital knee dislocation. Methods We describe the anatomy, imaging protocol and optimization, procedural logistics, surgical technique, and patient clinical results of this procedure. The study sample was comprised of five pediatric patients with knee extension contractures and treated with ultrasound-guided percutaneous quadricepsplasty using an 18-gauge needle between 2022 and 2024. Results Nine knees (five patients) with knee extension contractures were evaluated. Range of motion increased to greater than 90 degrees after the US-guided percutaneous quadricepsplasty. Conclusion Large incisions can be avoided in the treatment of knee contractures using ultrasound-guided quadricepsplasty. A minimally invasive approach avoids the formation of tight scars which can become a deforming force or create significant contractures which can limit motion. Graphical Abstract