Keywords

The Brain section of this book is the largest and covers a combination of normal variants, normal anatomy, and artifacts that can mimic disease. Although there is an attempt to organize such normal variations by region or anatomic structure, such a classification is inherently problematic because some normal variants can be in multiple locations (e.g., choroid plexus or dilated perivascular spaces), while some commonly encountered artifacts can occur anywhere in the brain (e.g., flow voids). Thus, this section of the book is generally organized starting from inferiorly at the skull base to more superiorly, while normal variants that can occur anywhere in the brain are generally placed in the middle. Also, artifacts or magnetic resonance related sequence phenomena that may simulate disease are placed toward the end of this section.

Some basic terminology and abbreviations regarding standard sequences is necessary, since magnetic resonance imaging (MRI) manufacturers unfortunately have not adopted one standard for sequences outside of the routine ones such as T1-weighted images, T2-weighted images, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted images. Thus, standard terminology used throughout this section and the remainder of the book is described below.

1 Terminology

1.5 T and 3 T:

1.5 Tesla and 3.0 Tesla MRI magnet field strengths

3D:

Three dimensional

BFFE:

Balance FFE (similar to CISS)

CECT:

Contrast-enhanced computed tomography (CT)

CISS:

Constructive interference in steady state, similar to T2WI, emphasizes cerebrospinal fluid hyperintensity

DWI:

Diffusion-weighted image

FFE:

Fast field echo (either T1- or T2-weighted)

FLAIR:

Fluid-attenuated inversion recovery imaging

GE:

Gradient echo

GE T2*WI:

Gradient echo T2*-weighted imaging

IR:

Inversion recovery imaging

T1IR:

T1-weighted IR imaging

T2IR:

T2-weighted IR imaging

MiniP:

Minimum intensity projection

MIP:

Maximum intensity projection

MPR:

Multiplanar reformat

MRA:

MR angiography

TOF MRA:

Time-of-flight MRA

NECT:

Non-enhanced CT

SWI:

Susceptibility-weighted imaging

T1WI:

T1-weighted imaging

T2WI:

T2-weighted imaging

T2*WI:

GE T2*WI

US:

Ultrasound