fs41 p34 aptip body oncology
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Publication for the Philips MRI Community
FieldStrengthIssue 41 September 2010
SPECIAL ISSUEMR in oncology
This article is part ofField Strength issue 41,September 2010
Tips for abdomen/pelvisoncology imaging
FieldStrength Issue 41 September 201034
Tips for abdomen/pelvis oncology imaging
At the Body/Oncology MR Council organized by Philips in August 2009 the needs for a standardized routine protocol for oncology MR imaging were discussed. The group outlined a concise protocol to help in oncology staging.
John Penatzer, RT,
Philips MR Application
1.5T ExamCard 3.0T ExamCard
For the abdomen/pelvis area such an examination should be possible within 15-20 minutes, both at 1.5T and 3.0T. When also the chest needs to be included, 25 minutes exam time was considered acceptable. Apart from the scout and the SENSE reference scan, the ExamCard should include the T1-weighted, T2-weighted fat suppressed, diffusion weighted and post-contrast e-THRIVE sequences.
Basic 1.5T and 3.0T ExamCards were set up with this input and the R2.6.1 versions are shared on NetForum. Below are some tips for optimizing results with these ExamCards.
Even taking into consideration the time needed to give breath-hold instructions, the actual time to complete the exam is within 15-20 minutes at both 1.5T and 3.0T. Parameters in Tips 1-6 below refer to the 1.5T ExamCard. Tip 7 explains where 3.0T is different.
Philips MR Application
Tip 1: Patient positioning
Position the SENSE Torso XL coil so that it covers pubic symphysis and includes the complete liver. This should cover the abdomen and pelvis and limit the need for repositioning the coil.
Apply the respiratory belt according to instruction in the Application Guides for use with the respiratory triggered scans.
Tip 2: Scout scan and reference scan(s)
The single shot T2-weighted scout scan provides a fast overview in three planes that can be used in diagnosis and for planning the subsequent scans. It uses 10 mm slices with 2 mm gap, and takes two breath holds of 23 sec. 30 transverse, 10 coronal and 10 sagittal slices are obtained.
Tip 3: T1-weighted pre-contrast scan
A two station approach is implemented. Planning should be done so that the abdomen is included in the first station and pelvis in the second station. Geolinks are used for consistent positioning of all scans and to aid in the postprocessing of the data.
In the 3D T1-TFE scan 60 slices with 2 x 2 x 2.25 mm voxels, overcontiguous are acquired for the abdomen and pelvis, each in a 19 sec. breath hold. Automatic post- processing of this scan will use MobiView and MPR to reconstruct the coronal images.
Coronal MPR MobiView
FieldStrength Issue 41 September 201036
Tip 4: DWIBS with three b-values
DWIBS is often very useful to visualize lesions. Many users prefer viewing DWIBS images with an inverse window, as this more closely resembles the images produced by PET. Three different b-values are used. The b0 images resemble T2-weighted fat suppressed imaging. The b1000 provides the strongest contrast. The b100 scan is added because this contrast helps to distinguish blood vessels (dark) from potential lesions (bright). Acquisition of this b-value also allows the user the choice to create maps with either the b0 value and/or b100 as the starting point for ADC calculation.
The diffusion weighted scan (DWIBS) is performed with free breathing. Voxel sizes are 3.0 x 3.0 x 7 mm, 35 slices are acquired with no gap. Slab MIPs of the abdomen and pelvis stations are automatically made and then manually stitched with MobiView.
DWIBS b=0 DWIBS b=100 DWIBS b=1000
DWIBS b=1000 MobiView (slab MIP)
Visit the MRI NetForum community for downloading ExamCards or for more application tips.
Tip 5: T2-weighted fat suppressed scan
A single shot T2-weighted TSE is used with SPAIR fat suppression. Voxel sizes are 1.4 x 1.8 x 7 mm, 30 slices are acquired with 1 mm slice gap. Respiratory triggering is used to acquire one slice per respiration.
If navigator is available (Release 2.6 or higher), it can be used as an alternative to the respiratory belt for the upper station.
Tip 6: e-THRIVE post-contrast scan
e-THRIVE is used for dynamic post-contrast imaging. The 3D T1 TFE scan with fat suppression acquires 2 x 2 x 2.25 mm voxels, 60 overcontiguous slices in two 19 sec. breath holds.
Tip 7: Differences in the 3.0T version of the ExamCard
The 3.0T ExamCard has two different reference scans for the two stations. The T1 TFE images have higher resolution: 1.5 x 1.5 x 2 mm, 119 slices in 22 sec. breath holds. The T2-weighted scan has higher in-plane resolution: 1.3 x 1.6 mm. The 3.0T inversion time is longer for DWIBS. e-THRIVE has higher resolution: 1.5 x 1.5 x 2 mm, 119 slices in 20 sec. breath holds.