School of MRI 2016 Advanced MR Imaging of the Musculoskeletal System November 10-12, 2016 Menton/FR
Topic 5 Knee L. Sconfienza io@lucasconfienza.it
THE KNEE Luca Maria Sconfienza, MD PhD Unit of Diagnostic and Interventional Radiology IRCCS Istituto Ortopedico Galeazzi, Milano Department of Biomedical Sciences for Health Università degli Studi di Milano ITALY SCHOOL OF MRI 2016 ADVANCED MRI IMAGING OF THE MSK SYSTEM Menton, 12 November 2016
Imaging protocol Outline Cruciate and collateral ligaments Menisci Cartilage Bone marrow edema
Sequence Protocol
Sequence Protocol
Sequence Protocol Int FS: is a fat suppressed sequence with a long TR and a TE between that of a traditional PD (e.g. TE= 10-20) and a traditional T2 (e.g. TE=80-100). The advantage of this sequence is that the TE is short enough to maintain sufficient signal for visualisation of the anatomy (like a PD) yet long enough to be more fluid sensitive (like a T2).
Intra-articular, extrasynovia Anterior Cruciate Ligament Two main fiber bundles: anteromedial bundle (AMB) posterolateral bundle (PLB)
Non-contact trauma Anterior Cruciate Ligament High risk sports: Ski Soccer, american football Gymnastics LANDING, TWISTING and DECELERATION, particularly with knee in full extension ISOLATED ACL TEARS ARE VERY UNCOMMON Mamoru Niitsu. Springer 2013
Three main mechanisms of injury Pivot shift Hyperextension Clip injury Anterior Cruciate Ligament Sanders TG. Radiographics. 2000 Oct;20 Spec No:S135-
Anterior Cruciate Ligament Mechanism of injury: PIVOT SHIFT INJURY
Anterior Cruciate Ligament Associated Findings Buckling of the PCL (steep course of distal portion of PCL)
Anterior Cruciate Ligament (ACL) Mechanism of injury: HYPEREXTENSION INJURY If a valgus force is also applied at hyperextension, the kissing contusions will be located medially Sanders TG. Radiographics. 2000 Oct;20 Spec No:S135
Anterior Cruciate Ligament CLIP INJURY: O Donoghue triad or unhappy triad
Anterior Cruciate Ligament (ACL) MRI FINDINGS: Partial Tears Partial tears may appear as Focal loss of the normal striated appearance (leaving intact fibers on at least one slice) Increased signal intensity on T2-W images with mild swelling of the ligament. AMB constitute the primary (96%) restraining force to anterior drawer at 30 knee flexion Rupture of AMB is believed to be functionally equivalent to complete ACL tear Distinguish partial tears from complete ruptures may be difficult in sagittal plane 40-75% sensitivity 62-89% specificity Non-specificity of signal intensity changes Chen WT. Acta Radiol. 2002 Sep;43(5):511 Stoller DW. Lippincot Williams & Wilkins 2007:
Anterior Cruciate Ligament (ACL) INTERPRETATION PITFALLS INTRALIGAMENTOUS GANGLION CYSTS Cysts are located in the proximal-middle portions of intact ACL Herniation of synovial tissue through capsular defect vs mucoid degeneration High signal on fluid-sensitive pulse sequences Do not enhance after intravenous contrast Roberts CC. Magn Reson Imaging Clin N Am. 2007;15 (1): 73-
Anterior Cruciate Ligament (ACL) Simple anterior cruciate ligament ganglion cyst involving the whole ligament
Anterior Cruciate Ligament (ACL) MUCOID DEGENERATION ( Celery Stalk Sign ) Mucoid degeneration/fusiform enlargement of the ligament May coesist with intraligamentous cyst
Anterior Cruciate Ligament (ACL) CHRONIC TEARS NON-VISUALIZATION of the ligament empty notch sign on coronal MR images ANGULATION of the ligament instead of a straight course Scarring and fibrosis BONE BRUISES typically not present LATERAL FEMORAL NOTCH SIGN Deepened sulcus Indicates a chronic insufficiency of ACL It may be seen in acute injury (impaction) Mamoru Niitsu. Springer 2013
Posterior Cruciate Ligament (PCL) Intra-articular, extra-synovial structure. Is the primary restraint against posterior subluxation of the tibia Two bundles similar to ACL, but more tightly grouped Two-to four-fold stronger than ACL uniform low signal intensity on MR Impossible to differentiate on MRI
Posterior Cruciate Ligament Mechanism of injury DASHBOARD INJURY It is caused by force on the anterior proximal tibia with the knee in flexion It is associated with anterior tibial and posterior patellar edema Associated with rupture of PCL and posterior joint capsule Sanders TG. Radiographics. 2000 Oct;20 Spec No:S135-
Posterior Cruciate Ligament Chronic Partial Tear
Posterior Cruciate Ligament Complete Tear
Collateral Ligaments Classified in three grades: Grade 1: sprain or strain, mainly consisting of elongation of the ligament without any functional loss. Treated conservatively. Grade 2: partial tear. Grade 3: complete tear. Differentiating between grade 2 and 3 may be impossible (often written as grade 2 3 tear )) Mamoru Niitsu. Springer 2013 De Maeseneer M. Radiographics. 2000 Oct;20 Spec No:S8
Medial Collateral Ligament Primary valgus + internal/external rotation stabilizer (Layer I: Thin sheet that overlies the two heads of the gastrocnemius and the structures of the popliteal fossa.) Layer II: Superficial layer of the MCL (tibial collateral ligament) Layer III: Deepest layer of the MCL called medial capsular ligament, which is continuous with the medial joint capsule. Mamoru Niitsu. Springer 2013 De Maeseneer M. Radiographics. 2000 Oct;20 Spec No:S8
Medial Collateral Ligament
Medial Collateral Ligament Linear hyperintensity representing edema along the ligament s fibers due to sprain or strain can be seen. This imaging finding can also be found in medial meniscal tear and knee osteoarthritis. Coronal FS PDWI Mamoru Niitsu. Springer 2013
Medial Collateral Ligament Edematous changes can extend into the surrounding medial retinaculum and vastus medialis Mamoru Niitsu. Springer 2013
Medial Collateral Ligament Discontinuity of the fibers and signal abnormalities due to edema and hematoma Mamoru Niitsu. Springer 2013
Collateral Ligaments and Posterior Corners MCL tear More than half of MCL tear occurs at the (femoral) portion, but it can less commonly occur in the distal (tibial) portion Mamoru Niitsu. Springer 2013
Posterolateral Corner Primary stabilizer for varus + external rotation Secondary stabilizer (with CLs) anterior + posterior translation during early (0-30 ) flexion Three layers LCL Popliteus tendon Popliteofibular ligament Rosas H, Radiographics 2016
Normal Anatomy Rosas H, Radiographics 2016
LCL grade I tear Rosas H, Radiographics 2016
LCL grade tears Grade II Grade III Rosas H, Radiographics 2016
Popliteus strain Rosas H, Radiographics 2016
Popliteomeniscal fascicles Rosas H, Radiographics 2016
Popliteofibular ligament Normal PFL Torn PFL Avulsed PFL Rosas H, Radiographics 2016
Arcuate ligament injury Rosas H, Radiographics 2016
Arcuate + fabellofibular ligament injury Rosas H, Radiographics 2016
Associated findings Rosas H, Radiographics 2016
Menisci Menisci are comprised of fibrous cartilage, mainly of type I collagen. Collagen fibers form two zones: 1. Peripheral zone: the outer third of the meniscus. Fibers are oriented in circumferential fashion resist longitudinal stresses 2. Inner zone: internal two-third of the meniscus. Fibers are radially oriented prevent longitudinal splitting due to excessive compression Radial fibers Circumferential fibers Aagaard H. Scand J Med Sci Sports. 1999 Jun;9(3):13
Menisci Anterior horn Medial Lateral Posterio r horn
Discoid Meniscus
Meniscal Tears May be categorized into: TRAUMATIC result from excessive force on a normal meniscus DEGENERATIVE normal force on an abnormally degenerated meniscus Contact with the articular surface on one or two or more sequential images increases confidence of a tear (sensitivity > 90%) Abnormal meniscal morphology: second diagnostic criteria for a tear De Smet AA. AJR Am J Roentgenol. 2001 Jan;176(1):6 Crues JV et al. Radiology. 1987 Aug;164(2):445-
Degenerative Tears 0 Normal meniscus 1 Focal hyperintensity 2 Linear hyperintensity 3 (3A) 4 (3B) linear hyperintensity reaching the surface = tear multiple linear hyperintensity = multiple tears Degenerative asymptomatic Pain
Degenerative Tears
Degenerative Tears
Degenerative Tears
Horizontal tear (cleavage tear): parallel to the tibial plateau Longitudinal tear (vertical tear): perpendicular to the tibial plateau; parallel to the long axis of the meniscus Radial tear: perpendicular to the tibial plateau and the long axis of the meniscus Longitudinal Meniscal Tears Radial Flap Complex Jee WH. AJR Am J Roentgenol. 2003 Jan;180(1):93 Kaplan PA. AJR Am J Roentgenol. 1991 Feb;156(2):333
VERTICAL RADIAL TEARS traverse circumferential fibers SHEAR FORCES Meniscal Tears VERTICAL LONGITUDINAL TEA between circumferential fibers COMPRESSION FORCES
VERTICAL RADIAL TEARS coronal S a g i t t a l
DISPLACED MENISCAL TEARS VERTICAL Longitudinal tear -> Bucket-handle VERTICAL Radial tear -> Parrot-beak HORIZONTAL tear -> Flap
BUCKET-HANDLE TEAR
BUCKET-HANDLE TEAR
Harper KW. AJR Am J Roentgenol. 2005 Dec;185(6):1429-34. 1 2 3 4 5 6 PARROT-BEAK TEAR Radial tear on the inner part of the meniscus and longitudinal in the peripheral aspect
MENISCAL ROOT TEAR
Superficial Zone Transitional Zone - Arc-like oriented collagen II fibrils - Chondrocytes Proteoglycans - Water Radial Zone -Vertically oriented collagen II fibrils -Chondrocytes -Proteoglycans -Water Tide Mark Calcified Cartilage - steplike Jiunction Subchondral bone plate Vascular plexus
Arthroscopic Cartilage Lesion Classification System described by Outerbridge Grade 0 = normal cartilage Grade 1 = thickening and softening Deep disruption of the collagen framework allowing the proteoglycans to increase the hydratation of cartilage, leading to cartilage thickening and softening Grade 2 = Superficial fissuring Articular Cartilage Damage: Grading Grade 3 = Deep partial-thickness defect Grade 4 = Full-thickness cartilage defect Grades 2, 3 and 4 can be visualized with imaging These grades can be used by radiologists (Yulish et al.)
Grade 0 Normal articular cartilage Normal cartilage with gray-scale stratification
Superficial lesions, chondral softening Increase signal in articular cartilage Grade 1
Superficial lesions extending down to <50% of cartilage depth Fissure, fibrillation involving < 50% thickness Linear-to-ovoid foci of increased signal involving <50% thickness Grade 2 Fibrillation <50% Fissure <50%
Defects extending down >50% of depth but not through subchondral bone Blisters/fissures/ fibrillation involving >50% thickness Linear-to-ovoid foci increased signal involving >50% of cartilage but not extending down to bone Grade 3
Transverse T2 FS weighted MR of patella. Focal ulceration is seen Grade 3 chondropathy.
Ulceration to subchondral bone Exposed subchondral bone Complete loss of articular cartilage or surface flap Grade 4
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Fat-Sat T2-FSE Fat-Sat IW-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Grade 2b Fissuring Fat-Sat IW-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Fat-Sat T2-FSE Fat-Sat IW-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Grade 2b Fissuring Fat-Sat IW-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Fat-Sat IW-FSE Fat-Sat T2-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Grade 2b Flap Tear Fat-Sat T2-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt IW-FSE Fat-Sat IW-FSE
Dark Cartilage Lesions True Positive Courtesy of R. Kijowski and BK Markhardt Grade 1b Fibrillation Fat-Sat IW-FSE
Dark Cartilage Lesions False Positive Courtesy of R. Kijowski and BK Markhardt IW-FSE Fat-Sat IW-FSE
Dark Cartilage Lesions False Positive Courtesy of R. Kijowski and BK Markhardt Normal Fat-Sat IW-FSE
Dark Cartilage Lesions Areas of low T2 signal within morphologically normal cartilage may be seen on all articular surfaces of knee joint Significant proportion of dark cartilage lesions were found to correspond to areas of cartilage degeneration at arthroscopy Dark cartilage lesions should be reported as areas of possible cartilage degeneration, especially in older individuals Courtesy of R. Kijowski and BK Markhardt
Dijkgraaf LC et al, 1995 Quantitative MR imaging Cartilage microstructure breaks down Decreased organization of matrix Loss of PG and GAG Increased water content Ability to detect changes prior to morphological degradation
Limitations Accumulation inversely proportional to [GAG] dgemric Reduced T1 relaxation times in regions with high [Gd(DTPA)2- ] T1 relaxation used as quantitative outcome, with lower T1 indicating reduced [GAG]
MARATHON BEFORE 1 DAY 1 WEEK
Healthy cartilage traps water molecules -> lower SI on T2w Degenerated cartilage has increased free water content -> higher SI on T2w 3D multi-echo sequences Efficacy proven in vivo and in vitro Remarkable limitations T2 mapping
T2 mapping Cartilage degradation -> T2 prolongation
Pre-treatment Monitoring of the effect of intra-articular injections of hyaluronates Ferrero et al. Eur Radiol 2017 in press T2 MAPPING Post-treatment Yun Sun Choi, et al 2008
PROs Higher image resolution Susceptibility artifacts Isotropic 3D sequences Faster acquisition UTE-T2* mapping T2* mapping Anisotropy Joint fluid CONs
T2* mapping
Sodium MRI Ultrashort TE (UTE): T2/T2*; (T1/T1rho) GAG chemical exchange saturation transfer (gagcest) DWI Other techniques
Bone Marrow Edema Differential diagnosis Secondary to cartilage wear Osteoarhtritis Inflammatory osteoartrhopathy SONK Insufficiency fracture Stress fracture SONK Other
Bone Marrow Edema SONK
Bone Marrow Edema Insufficiency fracture
Bone Marrow Edema Stress fracture
Osteochondritis Dissecans Main features Age: 10-20 years Location: lateral surface of medial condyle (55%), central portion (25%) Associated to discoid meniscus In older patients, signs may overlap to SONK Osteochondrosis characterized by necrosis of bone followed by reossification and healing History of trauma in 50% of patients Vascular theory
Imaging protocol Outline Cruciate and collateral ligaments Menisci Cartilage Bone marrow edema
ThankYou. Luca Maria Sconfienza, MD PhD Chair, Unit of Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Galeazzi Associate Professor of Radiology, University of Milano Milano, Italy io@lucasconfienza.it