breast MRI

Breast Mass Protocol

Overview

Currently breast MRI has five primary purposes; evaluation for breast implant rupture, as diagnostic tool in the evaluation of known or suspected breast cancer, imaging of the axillary region in cases of axillary lymphadenopathy with unknown primary, monitoring response to post-surgical primary chemotherapy, and pre-surgical evaluation of residual disease following neo-adjuvant chemotherapy.  

The following protocol is designed for evaluation of patients with known or suspected breast cancer and not for breast implant rupture.

Gadolinium (Gd) enhanced imaging is the mainstay of breast MRI in evaluation of a known or suspected breast tumor, extent of disease in patients with known breast malignancy, and recurrence of tumor after treatment.  Post-contrast high spatial resolution images are ideal for evaluating lesion morphology.  Post-contrast high temporal resolution images generally have lower spatial resolution but allow analysis of enhancement kinetics in any lesion.  The sequences described below are optimized for a spatial resolution sufficient to allow lesion morphology analysis and for a temporal resolution sufficient to evaluate the enhancement kinetics.  Currently the highest specificity can be attained evaluating both lesion morphology and the kinetic enhancement pattern of the lesion on dynamic 3D spoiled gradient echo (SPGR) with fat saturation study. 

Scheduling Guidelines

��        Approved Reimbursable Indications

1.      diagnosis is inconclusive, even after standard workup

2.      post-op: when scar tissue cannot be differentiated from tumors

3.      positive axillary nodes but no known primary

4.      rupture of breast implant

5.      determination of extent of disease in patients with known malignancy, prior to treatment (to assure confinement to one segment of the breast)

��        First Ask

1.      Why is the breast MRI being requested?  Does the referring physician want one or both breasts imaged?

2.      Do you have breast implants?

3.      Do you have a breast mass?

4.      Have you had breast cancer?

            

For patients with breasts implants, please ask the following:

1.           How long have you had the implants?

2.           What type of implants do you have?  Silicone, saline or both?

3.           Has there been a recent change in your implants?

4.           Do you or your doctor think there has been an implant rupture?

The breast MRI for evaluation of implant rupture alone does not require Gd injection. If the patient has a mass not related to the implant then she will require an injection of Gd.

For patients with a breast mass, ask the following questions:

1.     Have you had a recent mammogram?

2.     Did your mammogram have an abnormal finding?  Was the abnormal finding in the area where you feel the mass?

3.     Have you had a breast ultrasound?

4.     Have you had a biopsy of the breast mass?  If the answer is ��yes��, what were the results?

5.     Do you have a personal or family history of breast cancer?

6.     Is the breast MRI intended to better characterize the known breast mass, look for other areas of disease in the same breast, in the contralateral (opposite) breast or all of the above?

For patients with a history of breast cancer, ask the following questions:

1-     When did you have breast cancer?

2-     Did you have surgery?  When and what type of surgery did you have?

3-     Were your lymph nodes involved with cancer?

4-     Have you had chemotherapy or radiation therapy?  If yes, when did you stop your treatments?

5-     Is your doctor concerned about recurrent cancer or a new breast cancer?   In the same breast or the opposite breast?

6-     Have you had a recent mammogram?  Did it show a change?

7-     Can you or your doctor feel a new mass?  If yes, is it in the same area as your previous cancer or in a new area?

8-     Do you know if your breast cancer has spread to other parts of your body?

9-     Is the breast MRI intended to better characterize the new or recurrent finding, look for other areas of disease in the same breast, in the opposite breast or all of the above?

��        Ask the patient to bring all available mammograms with her at the time of the MRI examination. This is extremely important. If mammograms are not available, notify the radiologist who will be monitoring the exam.  Also have all recent mammogram and ultrasound reports faxed to MRI unit prior to the date of breast MRI study.  All breast masses will be evaluated with Gd.

��        Whenever possible schedule exam to occur between day five and day fifteen of the menstrual cycle (day one is the 1st day of menstruation). Otherwise there may be excessive enhancement of normal breast glandular tissue requiring a callback exam for reevaluation. 

Patient preparation

��        Start intravenous line (20 or 22 gauge IV). If IV caliber is smaller than 22 gauge, then it may be useful warming Gd contrast up to body temperature to reduce its viscosity.

��        Valium (5-10mg PO) or Xanax (1-2 mg po) if patient is claustrophobic.

��        Ear plugs

Coil:  Dedicated breast coil is optimal for superior signal to noise.

Patient Positioning:  Prone, head first.  Patient must have comfortable pillow for head and arms. Be careful that patient is centered in the coil. There is a tendency for patient to slide too far superiorly in the coil. To counteract this tendency, ask the patient to slide 2-3 cm toward feet after she lies prone on the coil.

Landmark: Mark at center of the breast coil

Series 1:  3-Plane Localizer 

This is a quick localizer sequence obtained in three planes. It is used to confirm optimal patient positioning within the breast coil. The sagittal views are most helpful. Bright signal from the inferior aspect of the coil should end at the inframamary fold. This will allow maximum coil signal superiorly.

 Series 2:  Sagittal T1

��        Prescribe graphically on an axial slice that is centered between the axilla and inframammary fold, not the center of the breast. This will allow better visualization of the axillary nodes.

��        Scan direction should be from left edge to right edge of the breast.

��        One or both breasts may be scanned depending on the clinical circumstances.

��        Make field of view large enough to include axilla to assess lymph nodes.

Series 3: Axial Inversion recovery (IR)

This sequence is helpful for differentiating the cysts from tumor or fibrosis.

Series 4&5:  3D Gd high temporal resolution

��   This is the main sequence to identify and characterize malignant lesions.

��   The scan plane may be sagittal for a single breast or axial for both breasts. With ��Vibrant�� it is possible to prescribe 2 separate volumes, one for each breast. Coronal can also cover both breasts but does not correspond to a standard mammographic view.

��   Keep FOV as small as possible but include both breasts. This helps to ensure homogeneous fat saturation and optimal spatial resolution.

��   If the # of scan locations or the phase encoding steps are increased, scan time will increase and the temporal resolution will be decreased. Longer scan time generally gives higher spatial resolution as a trade off to high temporal resolution. In the Scanning Range area the following options are available: FOV, slice thickness and number of scan locations. An optimal FOV is generally around 28-32 cm depending on patient size. If a larger volume is necessary, it is preferable to increase the slice thickness over the number of scan locations. This will allow one to cover a larger volume in the same amount of time, obviously at the expense of temporal resolution. However the ��ZIP2�� option allows obtaining relatively thin reconstructed images. These parameters are designed for imaging the breast tissue pre and post contrast. If one is interested in including the axillary region, a larger volume maybe necessary. This can be done by increasing the number of scan locations at the expense of temporal resolution. If the scan time is increased, check the multiphase screen as you may need to decrease the number of phases from nine to eight.

��        All pre, during and post-Gd acquisitions should be done in the same series to facilitate optimal subtraction technique. It is important to turn on the multiphase option to ensure that the scanner memory can accommodate the number of post contrast sequence planned. 

��   It is very important that the patient does not move between the pre, during and post-Gd scans. 

��   To minimize the chance of motion, be sure to start the IV line before performing the pre-contrast acquisition.  In general, the IV should be placed before the patient enters the magnet because the prone position can make starting the IV extremely difficult.

��    This sequence is obtained with the ��ZIP2�� option turned on. This allows you to obtain the images with a 5-6 mm slice thickness but to reconstruct the images at 2.5-3 mm for interpretative review.

��    Emphasize with the patient the importance of avoiding coughing, wiggling or other large motions during or in between these scans.

��   Manually prescan to ensure the best possible fat saturation (use cstun).  If homogeneous fat suppression is a problem with the larger FOV used for axial imaging, the scan can be performed without fat suppression and supplemented with a post processing subtraction technique for optimal visualization of areas of contrast enhancement. With ��Vibrant�� it is possible to optimize field homogeneity for two regions, one for each breast.

��    As the machine readily defaults to frequency R/L direction, make sure that the frequency direction is A/P. If the primary area of interest is in the axillary tail region, you may consider A/P phase encoding direction with R/L frequency encoding direction. This is the one exception to frequency A/P because if phase is A/P then cardiac and respiratory motion creates phase artifact that superimposes on the breasts. 

Dictation Template

Patient History: 

1.     Clinical abnormalities:  palpable lesion? (size, location, duration) nipple discharge?

2.     Previous biopsies:  date, location, results

3.     Hormonal status:  Last menstruation date (menstrual cycle phase), post-menopausal, peripartum,  exogenous hormones, tamoxifen

Comparison with Previous Studies:

��    Most recent mammogram (date)

��    Previous breast MRI (date)

��    Ultrasound or nuclear medicine study

Technique:

The patient was imaged in a 1.5 Tesla magnet using a dedicated breast coil.  Sagittal T1 weighted (6 mm), pre, during, and post-Gd 3D-FSPGR (2.5-3 mm) with fat saturation images were obtained.  An initial set of dynamic FSPGR gadolinium enhanced images were obtained in the axial plane to include both breasts with eight 3D data-sets acquired at 92 second intervals. IV ��.. mL of gadolinium bolus was administered in 20-30 seconds beginning simultaneously with the second dynamic acquisition. 

Post processing techniques:  MPR/MIP, time-intensity curves, subtraction