MMA #5 "MRI Wrist Positioning Nightmare? Not Anymore – Here’s How to Nail It"

Описание: Episode #5 of Magnetic Minds Academy!

Welcome to Magnetic Minds Academy, where MRI education meets real-world clinical mastery.

In this advanced training episode, we take you through one of the most technically difficult wrist MRI scenarios: scanning the wrist with the arm positioned at the patient’s side. Rated a 10/10 in difficulty, this approach is rarely taught in textbooks, yet it’s critical for patients with shoulder immobility, post-operative pain, trauma, or neurological limitations who cannot tolerate the traditional "Superman" or prone positioning.

This episode is your step-by-step guide to achieving diagnostic-quality images despite compromised patient positioning and complex scanning variables.
(Special Thank you to our Volunteer "Zachary")

What You'll Learn:
Patient Positioning – Arm at Side

• Step-by-step setup when prone/Superman isn’t possible
• How to use pads, wedges, straps, and coil workarounds to stabilize the forearm and wrist
• Coil tips: How you can use a dedicated wrist/Hand coil effectively
• Leveling the wrist and minimizing angulation errors even when the table isn’t ideal
• Isocenter challenges: How to adjust your scan plane when the wrist is off midline

Who Is This For?

MRI Technologists – looking to expand their problem-solving toolkit for non-standard cases
MRI Students – gaining real-world experience beyond the registry exam protocols
Radiology Educators & Instructors – teaching advanced protocol adjustments and patient care
Imaging Centers – that serve orthopedic clinics, trauma care, and post-surgical patients

Protocol Customization for Off-Center Wrist MRI

When imaging the wrist in a non-standard position—particularly with the arm down at the patient’s side protocol adjustments are essential to maintain diagnostic image quality despite geometric limitations and positioning constraints.

Recommended Parameters for Off-Center Wrists:

Field of View (FOV): 100–120 mm
Small enough to preserve spatial resolution while allowing for slight positional variation.

Slice Thickness: 2–3 mm with minimal or no interslice gap
Enables high-resolution imaging of small joint structures while minimizing partial volume effects.

Matrix: High-resolution (minimum 256 × 256)
Essential for evaluating fine anatomic detail such as ligaments (e.g., SL, LT) and tendon insertions.

Additional Technical Adjustments:

Phase and Frequency Direction:
Modify phase-encoding direction to prevent motion artifacts from the thoracic wall or shoulder. For arm-down positioning, consider using a phase direction that runs perpendicular to the source of motion (e.g., superior-inferior or anterior-posterior).

Oversampling / No Phase Wrap:

Activate oversampling (50–100%) or apply a No Phase Wrap technique to eliminate aliasing, especially in tight FOVs where adjacent anatomy (arm, chest wall) could wrap into the image.

Fat Suppression Strategy:

Fat Sat may yield sharper contrast but is sensitive to B0 inhomogeneity, use with caution if the wrist is significantly off-center.

STIR is preferred in cases with uneven magnetic field homogeneity or off-isocenter geometry, as it provides more consistent fat suppression.

Information provided by “Boyd’s Comprehensive Guide to MRI”. (www.boydsimaging.com)

00:00 Introduction
01:20 Wrist positioning
03:32 Localizer
08:30 Reposition
12:30 Axial
15:20 Coronal
17:45 Sagittal
20:42 SNR
23:18 Anatomy
26:32 COR STIR
30:34 Wrap up!