HEAD IMAGING - MRI Protocol Overview

    January 29 1999 Stay in Touch :-)

These Protocols have been developed for a Siemens VISION B31D with EPI Overdrive. They are posted to the web for the information and consideration of other MRI users and are not intended to be absolutely prescriptive. All MRI examinations are conducted in a dynamic interactive mode, with changes being made as required.

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Contents

General Preparation

• Use the Head coil with a sheet on the table, and a paper disposable towel for the coil sponge.

Besides standard room exclusions, remove dentures, hair clips, hair combs, earrings, nose rings, necklaces.
• Remove upper body clothing with metallic trim i.e. studs, neck zippers, epaulette buttons, appliqué or embroidery or any clothes likely to create static electricity i.e. mohair, nylon.
• The patient must be given disposable earplugs to attenuate the gradient switching noise, unless either of these add significantly to claustrophobia.
• Position the patient so their head and neck are relaxed, but without rotation in either plane. The patient should be well supported to minimize movement. Pillows under the knees can help to decrease strain on the knees and lumbar lordosis, and also stabilize motion of the lower body.

Excessive attempts at immobilization rarely work, but the comfort kit may stabilize involuntary movements
• Centre the field of view on the Nasion in the midline, making minor adjustments for baseline tilt.
• Protocols have been developed to deal with a range of typical requests and presentations, but always review the images as they are collected and modify the examination as appropriate. Optional sequences are suggestions for better defining the lesions, and may be undertaken at the Radiographers' discretion or suggestion, or at the request of the Radiologist.
• When time permits, and where the patient is not distressed, experiment with these and other likely sequence options. Then share your experience with the other MRI radiographers to help develop better protocols.
• Never Override the SAR limits on the Head Coil of the VISION.    The fuse will blow.

Magnetic Resonance Imaging of the Brain. R Jager I Moseley Current Medical Literature London 1998 ISBN 185009 107 2
  

Sequences stored under Head/Standard_Brain_Exam

SCOUT 3 plane GRE localisers
PD + T2 AXIAL Turbo spin echo (TSE) axials. 5 mm thick with 50% gap

FLAIR AXIAL 5 mm slices 0.9 mm resolution FOV 230 mm

T1 CORONAL Spin Echo coronals 5 mm thick with 50% gap

Optional Sequences

MP-RAGE isotropic T1
Use this if there are multiple lesions, when you need 2 T1 views, or when needing a slice thickness less than 4 mm. Reconstruct images as required.

Contrast

Post contrast, Scan 5 minutes after contrast. Use the MP-RAGE for most lesions except ? Lymphoma or in where there is a solitary metastases. In those cases use the SE sequence with a short TR and MTC

 Filming

• Use 20 format.
• Magnify to present 200 mm FOV (magnify 1.25 or 1.15)
• Label the FLAIR sheet
• Measure any mass lesions and create appropriate magnified views

 

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CEREBELLO-PONTINE ANGLE (CPA) PROTOCOL

Typical Indications

• ? acoustic neuroma
• ? CP angle lesion
• SN deafness
• Vertigo or Tinnitus

SCOUT Three plane low resolution scout

PD + T2 AXIAL Full brain coverage TSE axials. 5 mm thick with 50% gap

CISS_Axial High resolution 3D bright fluid sequence to define the cochlea and semi-circular canals and outline the cranial nerves.

Variations & Optional Sequences

• If the CISS images show an acoustic neuroma, or look suspicious do the isotropic MP-RAGE and make axial MPRs.
• For follow up of known acoustics, and lesions treated with radiosurgery just do post contrast isotropic MP-RAGE with axial and coronal reconstructions.

FILMING

CP Angle Views
12 format film 135 mm presented FOV

1.5 magnification for CISS
1.85 magnification for MP-RAGE

Fast Spin Echo MR Imaging of the Temporal Bone. Ric Harnsberger P91-93, Second International Conference on Magnetic Resonance Imaging 1995 Notes

MRI of Cranial Nerves. Part 2. MRI DECISIONS Vol.4 No. 4 Pp.2-16
 

Typical Indications

• Hormonal disturbances - Amenorhea, Hyperprolactinaemia, Acromegaly
• Query or known microadenoma (<10 mm) or macroadenoma (> 10 mm)
• Pituitary apoplexy (bleeding in pituitary) Sudden visual loss

SCOUT Three plane low resolution scouts

T2_CORONAL TurboSE T2 coronals positioned through the sella or lesion.

Isotropic_MPRAGE Used for multi-planar reformatting.

Optional Sequences

T2_SAGITTAL
For enhanced display of cystic lesions if they are not clearly visible on the MP RAGE images

Multi-planar Reconstructions

• Create 12 sagittal and 12 coronal T1 weighted images.
• Slice Thickness 1 or 2 mm for micro-adenomas, 3 mm or 4 mm for macro-adenomas.
• Use Double Oblique prescription on an axial work image to ensure that the planes are anatomically true.
• Define the sagittal locations from the right to the left, and the coronals from posterior to anterior to ensure easy filming in the proper direction.

FILMING

• Film on 12 format
• Use a Display FOV of 100 mm. ie magnification = FOV/100 (MP-RAGE 2.5, T2TSE 2.9)
• Position the top of the magnified FOV just above the top of the lateral ventricles for the coronal views. Include the posterior nasal space in the sagittal views.

Typical Indications

• Cushings Disease with asymmetric results in petrosal venous sampling, or other cases after discussion with Dr Taylor.

Preparation & Kit

• 20G Jelco
• 10 ml Saline
• Minimum volume extension tube
• Tape and tourniquet
• 2 x 10 ml syringes

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Contrast Doses (Half dose)

Technique

Rapid_T1_Coronal_51297
This is a series of TSE T1 coronal images intended to be used with a fast injection of half dose contrast. The injection is rapidly given at the start of the 2^nd measurement. There is a 10 second pause between the first (precontrast) scan and the start of the continuous string of post contrast measurements to prepare the injector and give a countdown.

Filming and Analysis.

• Use Evaluate Dynamic Analysis to subtract each of the post contrast sequences from the precontrast mask.
• Film on 12 format
• Identify the slice locations within that cover the pituitary gland (usually 3 but can be 6)
• Magnify image to present a 53 mm FOV (magnify x 3)
• Film the normal views and the subtracted views as shown below, using 2 sheets for each if more than 3 locations include the gland.
• Use the same window settings for each image and for each series. The right levels are determined in the 3^rd post contrast image.

Time curve analysis

• Select Evaluate Mean/Curve
• On the 3^rd post contrast view, set up 4 adjacent circular ROIs that cover the pituitary gland from right to left. Enter the appropriate image image numbers to make a set of enhancement curves.
• Film as shown below on a 6 format sheet

 

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MULTIPLE SCLEROSIS HEAD EXAMINATION

Typical Indications

• MS
• Demyelanation
• Nystagmus (especially in young patient)
• Optic Neuritis

SCOUT 3 plane GRE localisers
Double_Echo_AXIAL Turbo spin echo (TSE) axials. 5 mm thick with 50% gap

Sagittal_FLAIR 5 mm slices 0.9 mm resolution FOV 230 mm

T1 CORONAL Spin Echo coronals 5 mm thick with 40% gap

Filming

• Use 20 format.
• Magnify to present 200 mm FOV (magnify 1.25 or 1.15)
• Label the FLAIR sheet

 

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TEMPORAL LOBE STUDY

Typical Indications

Temporal lobe epilepsy (TLE)

Complex partial seizures (CPS)

Mesial temporal sclerosis (MTS)

Short term memory loss (STM)

Partial seizures

Temporal focus on EEG

Sequences stored under Head / Temporal_Lobe

Scout 3 plane GRE localisers

Sagittal Scout 3 sagittal FLASH images to help identify the line of the hippocampal grey matter.

PD + T2 AXIAL Turbo spin echo (TSE) axials. 5 mm thick with 50% gap

T1 Isotropic MP-Rage (sagittal acquisition)

T2 TSE Coronal 3 mm slices 0.65mm resolution

FLAIR Coronal 5 mm slices 0.9 mm resolution FOV 230 mm

Optional Sequences

True IR Axials

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