Three-Dimensional Constructive Interference in Steady State (3D CISS) Imaging and Clinical Applications in Brain Pathology

Guidance for Pediatric Pituitary MRI Ordering: A Single Institution Improvement Initiative

We identified inconsistencies in the pituitary MRI ordering practices at our pediatric institution. We used an interdepartmental collaboration to develop a pituitary MRI ordering guide based on available evidence and local expertise. The initiative has led to an improvement in the appropriate use of intravenous gadolinium-based contrast agents for pediatric pituitary MRI studies.

T1 relaxation: Chemo-physical fundamentals of magnetic resonance imaging and clinical applications

A knowledge of the complex phenomena that regulate T1 signal on Magnetic Resonance Imaging is essential in clinical practice for a more effective characterization of pathological processes. The authors review the physical basis of T1 Relaxation Time and the fundamental aspects of physics and chemistry that can influence this parameter. The main substances (water, fat, macromolecules, methemoglobin, melanin, Gadolinium, calcium) that influence T1 and the different MRI acquisition techniques that can be applied to enhance their presence in diagnostic images are then evaluated. An extensive case illustration of the different phenomena and techniques in the areas of CNS, abdomino-pelvic, and osteoarticular pathology is also proposed. CRITICAL RELEVANCE STATEMENT: T1 relaxation time is strongly influenced by numerous factors related to tissue characteristics and the presence in the context of the lesions of some specific substances. An examination of these phenomena with extensive MRI exemplification is reported. KEY POINTS: The purpose of the paper is to illustrate the chemical-physical basis of T1 Relaxation Time. MRI methods in accordance with the various clinical indications are listed. Several examples of clinical application in abdominopelvic and CNS pathology are reported.

Adult Moyamoya Disease and Moyamoya Syndrome: What Is New?

BACKGROUND

Recent advances are in the genetics, diagnosis, pathophysiology, and management of moyamoya disease (MMD), and moyamoya syndrome (MMS), a term used to describe moyamoya-like vasculopathy associated with various systemic diseases or conditions.

SUMMARY

Ring finger protein (RNF213) has been reported to be a susceptibility gene not only for MMD but also for atherosclerotic intracranial arterial stenosis and ischemic stroke attributable to large artery atherosclerosis. The latest guidelines by the Research Committee on MMD of the Japanese Ministry of Health, Labor, and Welfare, removed limitations of the previous definition that required bilateral involvement of the intracranial carotid artery to make the diagnosis, given the increasing evidence of progression to bilateral involvement in unilateral MMD. 3-dimensional constructive interference in steady-state MRI is useful for the differential diagnosis of MMD from atherosclerosis. Recent advances in the pathophysiology of MMD suggest that genetic and environmental factors play important roles in vascular angiogenesis and remodeling via complex mechanisms. The latest Japanese Guidelines and American Scientific Statement described that antiplatelet therapy can be considered reasonable. Endovascular interventional stent placement fails to prevent ischemic events and does not halt MMD progression. In the Japan Adult Moyamoya trial, a randomized controlled trial for bilateral extracranial-intracranial direct bypass versus conservative therapy in patients with MMD, who had intracranial hemorrhage, recurrent bleeding, completed stroke, or crescendo transient ischemic attack was significantly fewer with direct bypass than with conservative care.

KEY MESSAGES

This review presents updated information on genetics, diagnosis, pathophysiology, and treatment of adult MMD and MMS. Despite recent advances, many mysteries still exist in the etiologies of moyamoya vasculopathy. The diagnostic criteria and treatment guidelines have been updated but not yet been globally established. Ongoing and future studies investigating underlying pathophysiological mechanisms of MMD and MMS may clarify potentially effective medical, surgical, or endovascular treatments.

Basics for Pediatric Brain Tumor Imaging: Techniques and Protocol Recommendations

This review provides an overview of the current state of pediatric brain tumor imaging, emphasizing the role of various imaging sequences and highlighting the advantages of standardizing protocols for pediatric brain tumor imaging in diagnosis and treatment response evaluation. Basic anatomical sequences such as pre- and post-contrast 3D T1-weighted, T2-weighted, fluid-attenuated inversion recovery, T2*-weighted, and diffusion-weighted imaging (DWI), are fundamental for assessing tumor location, extent, and characteristics. Advanced techniques like DWI, diffusion tensor imaging, perfusion imaging, magnetic resonance spectroscopy, and functional MRI offer insights into cellularity, vascularity, metabolism, and function. To enhance consistency and quality, standardized protocols for pediatric brain tumor imaging have been recommended by expert groups. Special considerations for pediatric patients, including the minimization of anesthesia exposure and gadolinium contrast agent usage, are essential to ensure patient safety and comfort. Staying up-to-date with diagnostic imaging techniques can contribute to improved communication, outcomes, and patient care in the field of pediatric neurooncology.

Quality requirements for MRI simulation in cranial stereotactic radiotherapy: a guideline from the German Taskforce "Imaging in Stereotactic Radiotherapy"

Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.

Comparing 1.5 T and 3.0 T MR data for 3D visualization of neurovascular relationships in the posterior fossa

BACKGROUND

Neurovascular relationships in the posterior fossa are more frequently investigated due to the increasing availability of 3.0 Tesla MRI. For an assessment with 3D visualization, no systematic analyzes are available so far and the question arises as to whether 3.0 Tesla MRI should be given preference over 1.5 Tesla MRI.

METHODS

In a prospective study, a series of 25 patients each underwent MRI investigations with 3D-CISS and 3D-TOF at 1.5 and 3.0 Tesla. For both field strengths separately, blood vessel information from the TOF data was fused into the CISS data after segmentation and registration. Four visualizations were created for each field strength, with and without optimization before and after fusion, which were evaluated with a rating system and verified with the intraoperative situation.

RESULTS

When only CISS data was used, nerves and vessels were better visualized at 1.5 Tesla. After fusion, flow and pulsation artifacts were reduced in both cases, missing vessel sections were supplemented at 3.0 Tesla and 3D visualization at 1.5 and 3.0 Tesla led to anatomically comparable results. By subsequent manual correction, the remaining artifacts were further eliminated, with the 3D visualization being significantly better at 3.0 Tesla, since the higher field strength led to sharper contours of small vessel and nerve structures.

CONCLUSION

3D visualizations at 1.5 Tesla are sufficiently detailed for planning microvascular decompression and can be used without restriction. Fusion further improves the quality of 3D visualization at 3.0 Tesla and enables an even more accurate delineation of cranial nerves and vessels.