A picture is worth a thousand words - MRI in ACL injury

Transcription

1 A picture is worth a thousand words - MRI in ACL injury Poster No.: C-0820 Congress: ECR 2015 Type: Educational Exhibit Authors: F. Abubacker Sulaiman, V. Elangovan; Chennai/IN Keywords: Musculoskeletal joint, Musculoskeletal soft tissue, Extremities, MR, Decision analysis, Trauma DOI: /ecr2015/C-0820 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 26

2 Learning objectives Describe basic scanning protocols and image optimization techniques for ACL injury. Exemplify the normal anatomy and injured ACL appearance of knee joint. Describe a systematic technique for ACL evaluation using MRI. Background The anterior cruciate ligament (ACL) runs in an oblique course from the tibia to the lateral femoral condyle. It is an intra-articular extra synovial ligament composed of fibres running from the anterior inter condylar region of the proximal tibia to the medial aspect of the lateral femoral condyle within the intercondylar groove. The fibres of the ACL are arranged into two bundles known as the anteromedial and posterolateral bundle according to their tibial [1] insertion. The anteromedial bundle inserts at a more medial and superior aspect of the lateral femoral condyle, while the postero-lateral bundle inserts at a more lateral and distal aspect of the lateral femoral condyle. Occasionally there is an additional intermediate bundle in between these two bundles. [2,3] Page 2 of 26

3 Fig. 1: Normal ACL in extension and flexion References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN ACL tears may be partial or complete. A partial tear can involve both or only a single bundle to varying degree. [5] The mechanism of the ACL injury includes: Internal rotation of the tibia relative to the femur. Hyperextension such as occurs during jumping or high kick maneuvers and will lead to contra-coup bone contusion on the anterior tibia and femoral [4] 3. condyle. External rotation of the tibia relative to the femur with varus stress leading to impaction and bone edema medially and distraction laterally resulting in Segond fracture and tear of the lateral collateral ligament. The majority of the ACL injuries can be diagnosed by history and clinical examination (Anterior drawer test, Lachman test and pivot shift test). Association injury such as meniscal tear or chondral injury may also limit a full clinical examination. As a result, magnetic resonance imaging (MRI) is helpful in the assessment of suspected ACL injury. Page 3 of 26

4 Fig. 2: Sagittal section of Normal ACL appearance in MRI MERGE sequence. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Images for this section: Page 4 of 26

5 Fig. 1: Normal ACL in extension and flexion Page 5 of 26

6 Fig. 2: Sagittal section of Normal ACL appearance in MRI MERGE sequence. Page 6 of 26

7 Findings and procedure details The sequences used to visualize ACL include Turbo spin echo (TSE) Sagittal PD weighted sequence either with fat suppression and non-fat suppression, TSE coronal T2 weighted fat suppression sequence and TSE axial intermediate weighted with fatsuppression sequence. Different planes are used for anatomical correlation. Additional sequences comprise oblique views, flexion views (15 to 30 degrees) Fig. 8 on page 19, T1-weighted sequences and small FOV. T1-weighted sequences are useful for suspected fracture or characterizing loose bodies within the knee as any osseous fragments may contain a central marrow component. Oblique views are helpful in determining the presence, severity and location of ACL tears. Fig. 9 on page 20. Recently 3D fast spin echo imaging with or without suppression has been shown to have the same diagnostic accuracy as 2D sequences. This can decrease volume averaging [6] artifacts and shorten overall MR examination time. The normal ACL should have a taut, low to intermediate signal intensity with continuous fibres in all planes and sequences. It courses parallel or steeper than the intercondylar line. Fig. 3 on page 21. Diagnosis of ACL tear on MR images is usually based on direct signs [7, 8, 9]. The primary sign of ACL tear is fibre discontinuity the oblique sagittal plane is the most helpful. The empty notch sign on coronal imaging is a frequent finding in complete ACL tear [10]. Bone bruising is very common in ACL tears. In acute or sub-acute injury, thickening and oedema of the ACL is found characterized by increased signal intensity on T2 or intermediate weighted sequences in chronic case the fibre scan be completely absorbed or the residual. Page 7 of 26

8 ACL stump can become adherent to the synovial envelope covering the posterior cruciate ligament [11] Fig. 10 on page 22. Oblique coronal and sagittal views parallel to the ACL have been advocated and found to be effective in improving visualization of the ACL [12-14]. The sensitivity and specificity of MRI in the diagnosis of partial tears is poor [15, 16]. Potential pitfalls of MR in defining ACL tears are partial volume artifact. Fig. 3: 26-year-old man with no history of injury and clinical instability. Sagittal MERGE magnetic resonance image of the knee demonstrates a normal anterior cruciate ligament which is characterized by a taut, continuous, low signal intensity fibres Page 8 of 26

9 extending from the tibial plateau anteriorly to the medial aspect of the lateral femoral condyle. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Fig. 4: Sagittal T2W MRI image demonstrates avulsion of ACL from tibial attachment References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 9 of 26

10 Fig. 5: Sagittal T2W MRI demonstrates typical appearance of ACL tear at the midsubstance with fibres discontinuity of ACL. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 10 of 26

11 Fig. 6: Sagittal T2 weighted image of partial anterior cruciate ligament (ACL) tear. The ACL appears lax and concave in appearance. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 11 of 26

12 Fig. 7: Sagittal PD weighted image demonstrates complete tear of ACL. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 12 of 26

13 Fig. 8: Sagittal T2 weighted image demonstrates normal appearance of ACL during flexion. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 13 of 26

14 Fig. 9: Oblique Sagittal T2 weighted image demonstrates normal course of ACL. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Page 14 of 26

15 Fig. 10: Sagittal T1 weighted MR image shows entrapped ACL stump. References: Radiology and Imaging Sciences, Chettinad Hospital and Research Institute, Chettinad Hospital and Research Institute - Chennai/IN Images for this section: Page 15 of 26

16 Fig. 4: Sagittal T2W MRI image demonstrates avulsion of ACL from tibial attachment Page 16 of 26

17 Fig. 5: Sagittal T2W MRI demonstrates typical appearance of ACL tear at the midsubstance with fibres discontinuity of ACL. Page 17 of 26

18 Fig. 6: Sagittal T2 weighted image of partial anterior cruciate ligament (ACL) tear. The ACL appears lax and concave in appearance. Page 18 of 26

19 Fig. 7: Sagittal PD weighted image demonstrates complete tear of ACL. Page 19 of 26

20 Fig. 8: Sagittal T2 weighted image demonstrates normal appearance of ACL during flexion. Page 20 of 26

21 Fig. 9: Oblique Sagittal T2 weighted image demonstrates normal course of ACL. Page 21 of 26

22 Fig. 3: 26-year-old man with no history of injury and clinical instability. Sagittal MERGE magnetic resonance image of the knee demonstrates a normal anterior cruciate ligament which is characterized by a taut, continuous, low signal intensity fibres extending from the tibial plateau anteriorly to the medial aspect of the lateral femoral condyle. Page 22 of 26

23 Fig. 10: Sagittal T1 weighted MR image shows entrapped ACL stump. Page 23 of 26

24 Conclusion The ACL ligament is a very important ligament structurally and it is also frequently injured. MRI helps in accurate assesment of ACL injuries and also the other conditions associated with ACL injury. Personal information Dr.F.Abubacker Sulaiman Associate Professor Department of Radiology and Imaging Sciences Chettinad Hospital and Research Institution Kelambakkam Kanchipuram District Tamilnadu References 1 Yasuda K, van Eck CF, Hoshino Y, Fu FH, Tashman S. Anatomicsingle- and doublebundle anterior cruciate ligamentreconstruction, part 1: basic science. Am J Sports Med 2011;39: Norwood LA, Cross MJ. Anterior cruciate ligament: functionalanatomy of its bundles in rotatory instabilities. Am JSports Med 1979; 7: Amis AA, Dawkins GP.Functional anatomy of the anteriorcruciate ligament.fibre bundle actions related to ligamentreplacements and injuries. J Bone Joint Surg Br 1991; 73: Weber WN, Neumann CH, Barakos JA, Petersen SA, SteinbachLS, Genant HK. Lateral tibial rim (Segond) fractures:mr imaging characteristics. Radiology 1991; 180: Page 24 of 26

25 5Larson RL. Prosthetic replacement of knee ligaments: Overview.In: Feagin JA, editor. The crucial ligaments: Diagnosisand treatment of ligamentous injuries about the knee. NewYork: Churchill Livingstone, 1988: Gene Saragnese.3D imaging of the knee takes a step forward.field strength. 2010; 42: Lee JK, Yao L, Phelps CT, Wirth CR, Czajka J, Lozman J. Anteriorcruciate ligament tears: MR imaging compared witharthroscopy and clinical tests. Radiology 1988; 166: McCauley TR, Moses M, Kier R, Lynch JK, Barton JW, JoklP. MR diagnosis of tears of anterior cruciate ligament of theknee: importance of ancillary findings. AJR Am J Roentgenol1994; 162: Mink JH, Levy T, Crues JV. Tears of the anterior cruciateligament and menisci of the knee: MR imaging evaluation.radiology 1988; 167: Tung GA, Davis LM, Wiggins ME, Fadale PD. Tears of theanterior cruciate ligament: primary and secondary signs atmr imaging. Radiology 1993; 188: Lo IK, de Maat GH, Valk JW, Frank CB. The gross morphology of torn human anterior cruciate ligaments in unstableknees. Arthroscopy 1999; 15: Duc SR, Zanetti M, Kramer J, Käch KP, Zollikofer CL, WentzKU. Magnetic resonance imaging of anterior cruciate ligamenttears: evaluation of standard orthogonal and tailoredparacoronal images. ActaRadiol2005; 46: Hong SH, Choi JY, Lee GK, Choi JA, Chung HW, Kang HS.Grading of anterior cruciate ligament injury.diagnostic efficacyof oblique coronal magnetic resonance imaging of theknee.j Comput Assist Tomogr2003; 27: Ng AW, Griffith JF, Law KY, Ting JW, Tipoe GL, Ahuja AT,Chan KM. Oblique axial MR imaging of the normal anteriorcruciate ligament bundles. Skeletal Radiol2011; Epub aheadof print. 15 Umans H, Wimpfheimer O, Haramati N, Applbaum YH,Adler M, Bosco J. Diagnosis of partial tears of the anterior cruciate ligament of the knee: value of MR imaging. AJR AmJ Roentgenol1995; 165: Yao L, Gentili A, Petrus L, Lee JK. Partial ACL rupture: anmr diagnosis? Skeletal Radiol1995; 24: Page 25 of 26

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