Overview

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Patient Prep

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Knee Protocol (8.01.08)

Overview

Evaluation of the knee including the patello-femoral joint, medial and lateral compartments as well as related tendons and ligaments and the popliteal fussa is performed with a high resolution proton density sequence acquired in 3 planes: Axial, Sagittal and Coronal. Start with the axial sequence and then use this as a locator for prescribing the subsequent sequences. Evaluation of bone marrow for contusion requires a STIR or T2 fat saturation sequence in either coronal or sagittal planes. If the patient has a suspicious mass then post-Gd T1 fat saturation images are help to determine if the mass is benign or malignant and better delineate its full extent. An arteriogram can be obtained during the injection of the gadolinium. Finally in patients with hemophilia or PVNS a gradient echo sequence is useful for evaluating the extent of hemorrhagic synovitis.

 

Patient Preparation


3 PLANE LOC
Calibration
AXL PD
SAG PD FREQ A/P


SAG PD FSAT FREQ A/P COR PD FSAT FREQ R/L COR PD FREQ R/L
IMAGING PARAMETERS
Plane 3-PLANE
AXIAL AXIAL OBLIQUE OBLIQUE OBLIQUE OBLIQUE
Mode
2D 2D 2D 2D 2D 2D 2D
Pulse Seq
Gradient Echo Gradient Echo FSE-XL FSE-XL FSE-XL FSE-XL FSE-XL
PSD Name
-- -- -- -- -- -- --
Imaging Options
Seq Fast Fast Calib FC NPW TRF Fast FC NPW Fast FC NPW Fast NPW EDR TRF Fast FC NPW EDR TRF Fast
SCAN TIMING
# of Echoes
1 1 1 1 1 1 1
TE
-- -- 34.0 34.0 40.0 41.0 34.0
TR --
-- 4600.0 4834.0 3550.0 3650.0 5050.0
Flip Angle
-- -- -- -- -- -- --
Bandwidth
-- -- 31.25 20.83 20.83 20.83 31.25
ADDITIONAL PARAMETERS (see attached instructions)
SAT
             
ACQUISITION TIMING
Freq
256 -- 512 512 256 320 512
Phase
128 -- 256 320 224 224 256
NEX
1.00 -- 2.00 2.00 2.00 2.00 2.00
Phase FOV 1.00
1.00 -- -- -- -- -- --
Locs Before Pause
-- -- -- -- -- -- --
Freq Dir
Unswap A/P A/P A/P A/P R/L R/L
Auto Center Freq
             
Auto Shim
Auto Auto Auto Auto On On Auto
Contrast o
No No No No No No No
SCANNING RANGE
FOV 24.0 48.0
14.0 16.0 16.0 14.0 14.0
Slice Thickness
3.0 6.0 3.5 4.0 4.0 3.0 3.0
Spacing
1.0 0.0 0.0 0.0 0.0 0.0 0.0
Start - End
             
# of Slices
27 50 30 24 24 28 28
Scan Time              

 

 

 

 

Common Indications

ICD9 Codes

Knee pain 719.46
Knee instability 718.86
Knee mass 719.66

Scheduling Guidelines:

 

Patient Preparation:

       Fill out safety screening and clinical information form

       Vitamin E capsule on the site of symptoms and on any masses

       Measure distance left or right from centerline of magnet

 

Coil: Extremity. Slightly externally rotate the foot by about 10-15 degrees to stretch the anterior cruciate ligament.

Pack some cushions around the knee to help it stay motion-free. A small cushion under the ankle helps to keep the leg straight.

 

Landmark: inferior region of patella.

 

Patient Positioning: Supine, feet first.

 

Series 1: Axial Proton Density

Enter left or right offset corresponding to distance from centerline of magnet. Then SCAN.

Right knee:

offset

R 75

Left knee:

offset

L 75

 

Series 2: Sagittal Proton Density

 

Series 3: Coronal Proton Density

 

Series 4: Coronal T2 Fat Sat (same as series 3 above)

 

 

Series 5: Optional Cartilage:

  • Usually cartilage is well seen on the proton density sequences (series 1-3). However this in patients with cartilaginous injuries, this extra sequence optimized for cartilage may be useful.
  • Do not film this sequence. It is viewed on the computer work station.

 

If there is a Solid Mass suspicious for CANCER:

then make sure there is a vitamin E capsule marking the site of the mass and perform dynamic 2D or 3D Gd MRA during the injection of single dose gadolinium followed by axial and either sagittal or coronal T1 fat sat spin echo sequences

 

Series 6: Optional 2D Projection MRA

  • This requires a custom pulse sequence written by Yi Wang. Actually 2 programs are required, one for data acquisition and another for data processing to perform complex subtractions.(yiwang@mail.med.cornell.edu)
  • Set slab width to include mass and arteries: typically 50-100 mm.
    • Sagittal: if mass is on front or back of knee
    • Coronal if mass is on medial or lateral aspect of knee
  • Select enough phases to last for 60 seconds
  • Recontruction Instructions:
    • Log on to scanner:
      • MRSI blue scanner telnet 192.168.30.21
      • MRSI red scanner telnet 192.168.30.23
      • Hospital Scanner telnet 140.251.78.51
    • Name: Signa
    • Password: adw2.0
    • Change directory: cd /usr/g/mraw
    • List files plist
    • Run post-prorcessing lx2dsa
    • Use the second image as a mask for subtraction and store as series 20.
    • repeat the subtraction using a mask which immediately precedes arrival of contrast in popliteal artery

 

Series 7: Optional Post Gd T1 fat sat

  • Perform in axial plane as 4-10 mm thick slices covering the mass with interleave or 25% gap
  • Keep the TR under 600msec
  • TE min full : do not use minimum TE
  • Obtain one additional plane:
    • Sagittal if the mass is on the front or the back
    • Coronal if the mass is on the left or the right side

 

If there is hemophilia or if PVNS is suspected:

Do a gradient echo sequence

Series 8: Optional Gradient Echo:

  • This sequence is useful for patient with hemophilia or PVNS
  • Make sure to cover all of the synovium

 

Series 9: Optional Sagittal Spin Echo Proton Density:

This sequence is for use when fast spin echo is not considered adequate to diagnose a meniscal tear. It replaces series 2. Note that there is controversy over whether spin echo or fast spin echo is superior for diagnosing meniscal tears.

 

Filming Instructions:

Series 1 2 sheets 12 on 1 zoom in and shift to center knee

Series 2 2 sheets 12 on 1 and also film meniscal windows

Series 3 2 sheets 12 on 1

Series 4 2 sheets 12 on 1

 

ICD9 Codes

Internal derangement of knee 717.0-717.9
Articular cartilage disorder, site unspecified 718.00
Tear of medial cartilage or meniscus 836.0
Tear of lateral cartilage or meniscus 836.1
Other tear of cartilage or meniscus 836.2
Sprains and strains of knee and leg 844.0-844.9
Ankylosis of joint, fibrous, osseous 718.05
Cyst of bone 733.20-733.29
Malignant neoplasm lower limb 195.5
Benign neoplasm, short bones of lower limb 213.8
Lesion of lateral popliteal nerve 355.3
Lesion of medial popliteal nerve 355.4
Aneurysm of lower extremity 442.3

 

Billing code:

(any joint, lower extremity) 73721

 

Sample Dictation

Dr.

 

Re:

Exam:                   knee MRI

Exam Date: January , 2000

 

Clinical Statement: knee pain

 

Technique:              Extremity coil (right knee only):

Axial, Sagittal and Coronal proton density

Coronal T2 with fat saturation

Sagittal 3D SPGR fat sat for cartilage

 

Findings:

Effusion:

Patella retinaculae:

Anterior cruciate ligament:

Posterior cruciate ligament:

Popliteus tendon:

Lateral collateral lig complex:

Medial collateral ligament::

Medial meniscus:

Lateral meniscus

Bone marrow:

Cartilage:

Patella tendon:

Quadracepts tendon

 

 

Impression:

 

 

Examples:

 

 

 

 

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