November 2014

Introduction

Presurgical Mapping with fMRI and DTI: Soon the Standard of Care?

Lotfi Hacein-Bey

Lotfi Hacein-Bey

The technique of fMRI has been around for over 30 years, and DTI for about 15 years. The first application of fMRI was by Ogawa et al, in 1990. In a rat model, this team was able to manipulate the blood oxygen level–dependent (BOLD) signal by inducing changes in deoxyhemoglobin concentrations with insulin-induced hypoglycemia and anesthetic gases. … more »

Review Article

Cerebrovascular Reactivity Mapping: An Evolving Standard for Clinical Functional Imaging

Jay Pillai

Jay Pillai

We decided to write this review to highlight a relatively under-recognized phenomenon that substantially impacts interpretation of clinical fMRI examinations that are performed for presurgical mapping. This rather poorly understood phenomenon is known as “neurovascular uncoupling” (NVU). The NVU problem can be adequately addressed with breath-hold cerebrovascular reactivity mapping (BH CVR) in cases of focal … more »

Brain

Diffusion Tensor Imaging of Cerebral White Matter: A Pictorial Review of Physics, Fiber Tract Anatomy, and Tumor Imaging Patterns

Aaron S. Field

Aaron S. Field

DTI exemplifies a commonly observed life cycle of new imaging technology: an initial honeymoon period of unbridled enthusiasm, characterized by frequent publications and presentations, is soon tempered by (valid) questions regarding reproducibility and growing skepticism over real-world applications. Eventually a divide occurs: proponents continue undaunted, using the method and publishing their experience, perhaps acknowledging the … more »

Stroke

Chronic Neurovascular Uncoupling Syndrome

David Mikulis

David Mikulis

It is well known that blood flow and oxygen consumption increase during neuronal activation. Measurement of these parameters in perhaps the most quoted work has shown a blood flow increase of 45% over baseline but only a 16% increase in oxygen consumption.1 To this day the explanation for the high increase in flow that delivers … more »

Neurosurgery

Functional Brain Mapping and Neurosurgical Decision-Making: Toward Improved Patient Outcomes

Wade Mueller

Wade Mueller

John L. Ulmer

John L. Ulmer

Surgical excision of tumors is important to prolong survival, reduce steroid dependence, improve neurologic function (in up to 50% of glioma patients), and establish histologic diagnoses that determine postsurgical treatment algorithms. Advanced functional imaging MR-based techniques, such as fMRI and DTI, have shown applications in establishing … more »

Neurosurgery

Functional Magnetic Resonance Imaging and Cortical Reorganization: A Context-Specific Approach

John L. Ulmer

John L. Ulmer

fMRI of eloquent cortex is established as a potentially useful technique to predict the risk of surgical resection or endovascular obliteration and can help guide therapeutic approaches. Blood oxygen level–dependent (BOLD) fMRI has been used for presurgical mapping for over 3 decades, but the technique has significant limitations that contribute to making it an … more »