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High resolution 3.0T knee exam, Penn State University

ExamCard
Mosher, Timothy, M.D. Penn State Milton S. Hersey Medical Center

 

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ExamCard Purpose

This 3-plane protocol specifies a scout and proton density and T2-weighted pulse sequences.

A coronal proton density TSE sequence is used instead of the traditional 3D T1-weighted fat-suppressed sequence due to its better ability to depict chrondral surface lesions and degenerative changes in the substance of the cartilage. For cases in which examination of the cartilage is specifically requested, the 3.0T system is used preferentially. Total scan time is about 17:00.

 

Patients typically (65-75%) present with suspected meniscal pathology or additional pathology associated with a known ACL tear. Also common are patients with ill-defined knee pain (e.g. patellar pain syndrome) in which the pre-MRI diagnosis is unclear; these often are younger patients. In addition, sports-related osteochondral injuries and suspected early osteoarthritis are regularly seen.

ExamCard overview

Scan 1Scout
Scan 2Reference scan (if SENSE is used)
Scan 3Axial SPIR TSE proton density
Scan 4Sagittal TSE proton density
Scan 5Sagittal TSE T2W
Scan 6Coronal SPIR TSE proton density

ExamCard Image steps

Scout R (ax) PD DRIVE SPIR (ax) PD TSE (sag)
Scout R (ax)
PD DRIVE SPIR (ax)
PD TSE (sag)
T2 SPIR (sag) PD SPIR (cor)
T2 SPIR (sag)
PD SPIR (cor)

Patient preparation

Patient positioning: feet first/supine

Coil(s): SENSE Knee coil   OR    Flex-M coil

Extended information per scan

1. Scout: Axial and 3-plane fast field echo scout

 

2. Reference scan: for SENSE Knee coil if SENSE is used

The reference scan determines the signal profile of each element of the [TJM1] 8-Channel SENSE Knee coil. Perform this scan after the scout and position it over the area to be examined. The SENSE reference scan is a once-only scan, performed during scan preparation to aid throughput, that can be used for all subsequent SENSE and CLEAR (Constant Level AppEARance) scans. The result is superb image quality even if the patient moves. Scan time: 0:30.

 

3. Axial SPIR TSE proton density: for internal knee joint/scout for sagittal and coronal

Evaluation of the patellar-femoral joint and patellar retinaculum. Secondary function is visualizing the ACL, PCL and collateral ligaments and posterior lateral corner. Also serves as scout for sagittal and coronal images. Scan time: 4:55.

 

4. Sagittal TSE proton density: for meniscal pathology, ligaments, tendons

Survey for meniscal pathology and in the interior compartment of the quadriceps-patellar tendon. Visualization of primary ligamentous structures (ACL, PCL), and posterior lateral corner. Scan time: 2:52.

 

5. Sagittal T2 TSE: for ACL pathology, bone marrow, joint effusion

Evaluation of bone marrow edema may indicate overlying cartilage lesion that can be investigated with the cartilage sequence. Pathology directly involving the bone marrow may include contusions, osteochondral lesions and degenerative marrow changes that may be associated with early osteoarthritis. Scan time: 3:48.

 

6. Coronal SPIR TSE proton density: for cartilage/ligaments

Examination of the articular cartilage, collateral ligaments, ACL and PCL. Secondary function is visualization of bone marrow and menisci. Scan time: 3:20.

Critical parameters/alternatives

  • To minimize chemical shift artifact at 3.0T, it is critical to maximize receiver bandwidth.

 

  • TR and phase encoding steps will vary between patients to account for more or fewer slices depending on patient size.

 

  • Susceptibility artifacts arising from implanted hardware (e.g., titanium interference screws for ACL reconstruction) have not caused significant problems, although patients with major hardware, such as an intermedullary femur rod or tibia rod are not scanned at 3.0T due to unacceptable artifact.

 

  • Per policy, patients with aneurysm clips and pregnant patients are not scanned on the 3.0T system.

Background information

Knee imaging at 3.0T affords greater signal-to-noise ratio over lower field strengths, enabling use of higher spatial matrices, which nominally increase resolution of subtle meniscal tears. More significantly, the improved SNR at 3.0T provides better visualization of cartilage surface and subsurface features, particularly when proton density sequences are used. The sequence that Penn State University (PSU) uses to visualize cartilage also provides information about bone marrow and menisci. In clinical research, PSU is exploring the connection between focally elevated T2 values in T2 parametric maps of articular cartilage and damage to the collagen matrix. (see references)

 

Besides using a higher spatial matrix, the 3.0T protocol presented here specifies the same parameters as PSU's 1.5T knee protocol.

Literature references

1.  Potter HG, Linklater JM, Allen AA, Hannafin JA, Haas SB.
Magnetic resonance imaging of articular cartilage in the knee. An evaluation with use of fast-spin-echo imaging.
J Bone Joint Surg Am 1998; 80:1276-1284.

 

2.  Nissi MJ, Toyras J, Laasanen MS, et al.
Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage. J Orthop Res 2004; 22:557-564.


 

3.  Gold GE, Han E, Stainsby J, Wright G, Brittain J, Beaulieu C.
Musculoskeletal MRI at 3.0 T: relaxation times and image contrast.
AJR Am J Roentgenol 2004; 183:343-351.


 

4.  Winalski CS, Gupta KB.
Magnetic resonance imaging of focal articular cartilage lesions.
Top Magn Reson Imaging 2003; 14:131-144.

 

5.  Hargreaves BA, Gold GE, Beaulieu CF, Vasanawala SS, Nishimura DG, Pauly JM.
Comparison of new sequences for high-resolution cartilage imaging.
Magn Reson Med 2003; 49:700-709.

 

6.  Mosher TJ, Liu Y, Yang QX, et al.
Age dependency of cartilage magnetic resonance imaging T2 relaxation times in asymptomatic women.
Arthritis Rheum 2004; 50:2820.


 

7.  Mosher TJ, Liu Y, Yang QX, Yao J, Smith R, Dardzinski BJ, Smith MB.
Age dependency of cartilage magnetic resonance imaging T2 relaxation times in asymptomatic women.
Arthritis & Rheumatism, Vol. 50, No. 9, September 2004, pp 2820-2828.



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ExamCard
Intera 3.0T
Release 10
Knee, Musculoskeletal
 

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