MRI of Legg-Calvé-Perthes Disease

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1 Pediatric Imaging Review Dillman and Hernandez MRI of Legg-Calvé-Perthes Disease Pediatric Imaging Review Jonathan R. Dillman 1 Ramiro J. Hernandez Dillman JR, Hernandez RJ Keywords: complications, Legg-Calvé-Perthes disease, MRI, staging DOI: /JR Received January 23, 2009; accepted after revision May 3, oth authors: Department of Radiology, University of Michigan Health System, and Section of Pediatric Radiology, C. S. Mott Children s Hospital, 1500 E Medical Center Dr., nn rbor, MI ddress correspondence to J. R. Dillman (jonadill@med.umich.edu). CME This article is available for CME credit. See for more information. JR 2009; 193: X/09/ merican Roentgen Ray Society MRI of Legg-Calvé-Perthes Disease OJECTIVE. Legg-Calvé-Perthes disease is a common cause of hip pain in children that may be initially clinically and radiographically difficult to diagnose and stage. The purpose of this article is to describe and illustrate the various MRI appearances of this condition. CONCLUSION. MRI may show proximal femoral abnormalities before radiography in the setting of Legg-Calvé-Perthes disease, allowing appropriate diagnosis and prompt treatment. MRI can also assess for revascularization, healing, and multiple complications. L egg-calvé-perthes (LCP) disease is a common cause of hip pain and limp in preadolescent children. Early in its course, this condition, a form of idiopathic osteonecrosis (or osteochondrosis), may be difficult to diagnose both clinically and radiographically. MRI is a useful tool for the evaluation of LCP disease that may assist with prompt diagnosis, staging, and evaluation of associated complications. In addition, a variety of MRI findings may provide valuable prognostic information. The MRI findings of LCP disease are quite variable depending on the different stages of the disease (avascular [or necrotic], revascularization, and healing [or reparative] phases). The purpose of this article is to illustrate the MRI appearances of the different stages of LCP disease as well as to present examples of various complications associated with this condition. Epidemiology and Pathogenesis of Legg-Calvé-Perthes Disease LCP disease is a relatively uncommon condition that affects approximately in 100,000 children ( %) [1]. oys are affected approximately five times more commonly than girls [1]. lmost all affected individuals are diagnosed between 2 and 14 years of age, with a peak incidence around 5 6 years of age [1]. Those children diagnosed at a younger age typically experience a more benign disease course, whereas those diagnosed at an older age typically require increased rates of intervention and generally experience poorer outcomes. Whites are more frequently affected by LCP disease than other ethnicities. lthough most cases of LCP disease are unilateral, approximately 15% of individuals are affected bilaterally [1]. When bilateral, the femoral heads are most commonly asynchronously affected. LCP disease is generally considered to be idiopathic without an identifiable inciting factor. No seasonal variation or space time clustering in the incidence of LCP disease has been recognized [1]. The incidence of this condition, however, has been correlated with lower socioeconomic status and delayed skeletal age [1]. LCP disease is considered to be a diagnosis of exclusion, and other causes of avascular necrosis (such as sickle cell disease, leukemia, corticosteroid administration, and Gaucher s disease) as well as epiphyseal dysplasia must be ruled out. recent study by Kenet et al. [2] failed to establish an association between LCP disease and a variety of genetic mutations responsible for certain thrombophilic states (including factor V Leiden), Gaucher s disease, and familial osteonecrosis of the femoral head (due to mutations affecting type 2 collagen). MRI of Legg-Calvé-Perthes Disease lthough radiography is the primary imaging technique used in the evaluation of patients with suspected or known LCP disease, MRI may play an important complimentary role. Using a combination of unenhanced and contrast-enhanced imaging sequences, this condition can be confidently diagnosed, even in the setting of normal or equivocal hip 1394 JR:193, November 2009

2 MRI of Legg-Calvé-Perthes Disease radiographs. Early diagnosis of LCP disease is important because it allows prompt initiation of potentially joint-preserving therapies [3]. In addition to providing early diagnosis, MRI also allows accurate staging of the disease process, evaluation of numerous associated complications, and differentiation of LCP disease from other epiphyseal lesions, such as multiple epiphyseal, spondyloepiphyseal, and Meyer dysplasias (Fig. 1). Finally, MRI may reveal other unsuspected causes of hip pain, such as juvenile chronic arthritis, fracture, and apophyseal injury (JR Dillman, unpublished data). MRI is both a sensitive and specific imaging technique for the evaluation of LCP disease. lthough MRI and bone scintigraphy findings in LCP disease correlate quite well [4, 5], MRI depicts the exact extent of femoral head involvement more precisely than pinhole scintigraphs [6] (Fig. 2). MRI also does not expose the pediatric patient to the potentially harmful effects of ionizing radiation. MR images of the hips may be acquired using either a body or a surface coil [4, 7 9]. Surface coils are preferred because they allow increased signal-to-noise ratio and improved spatial resolution. variety of pulse sequences can be used to evaluate for possible LCP disease. Unenhanced pulse sequences commonly used include T1-weighted spin-echo, T1-weighted spoiled gradient-recalled echo (SPGR) with or without fat saturation, T2- weighted fast spin-echo (FSE) with or without fat saturation (or T2-weighted STIR), and proton density weighted FSE with or without fat saturation. These sequences are typically acquired in the coronal and sagittal planes. Sagittal imaging has been shown to better reveal the extent of femoral head collapse as well as the angular span of involvement when compared with coronal imaging [10] (Fig. 3). Studies have also shown that sagittal and coronal images can be used to calculate the percentage of femoral head involvement [11], evaluate femoral head epiphyseal bone and cartilage heights [10], and predict risk of future collapse [12]. In a study by Ha et al. [10], femoral head collapse was seen only on sagittal imaging in 26% of cases reviewed. The axial plane is typically limited in the evaluation of LCP disease because the superior portion of the femoral head is often inadequately visualized because of partial volume averaging artifact. Imaging of the hips after the IV administration of gadolinium-containing contrast material may also be helpful in the evaluation of LCP disease [4, 5, 7]. Contrast-enhanced imaging is particularly useful in the assessment of proximal femoral epiphyseal perfusion. Hypoperfusion of the proximal femoral epiphysis may be one of the earliest indicators of LCP disease [4, 5, 7]. Standard unenhanced MR images may be normal in early LCP disease, with the proximal femoral ossific nucleus showing normal signal characteristics [4, 13]. Dynamic multiphasic imaging of the hips in the coronal plane using either a T1-weighted SPGR or SE pulse sequence after the IV administration of gadolinium-containing contrast material (typically administered at 0.1 mmol/kg) can be used to establish whether proximal femoral epiphyseal vascularity is intact [4, 5, 7, 9]. Delayed T1-weighted imaging 2 5 minutes after contrast material administration may also be obtained to further evaluate the vascular supply of the proximal femoral epiphysis. Digital subtraction imaging techniques (on a pixel-by-pixel basis) should be used to identify subtle alterations in perfusion and likely increase both the sensitivity and specificity of MRI in the evaluation of early LCP disease [4, 5]. Our institutional MRI protocol for the evaluation of suspected and known LCP disease is presented in Table 1. dditional MRI techniques may also play an important role in the evaluation of LCP disease. ased on multiple animal studies, diffusion-weighted imaging appears to be quite sensitive for early proximal femoral epiphyseal ischemia [14 16]. lthough diffusion appears to be restricted immediately after the ischemic insult [14, 16], both diffusion and apparent diffusion coefficients (DCs) begin to increase hours to a few days later [14 16]. In a study by Menezes et al. [15], diffusion and DC abnormalities were identified before evidence of reperfusion on contrast-enhanced (perfusion) imaging and persisted after blood flow was restored. MR arthrography of the hip (MRI performed after the intraarticular administration of gadolinium-containing contrast material) can also be used to evaluate patients with LCP disease. This imaging technique may be particularly beneficial in the evaluation of LCP disease-related complications. Intraarticular contrast material allows detailed evaluation of articular cartilage surfaces, the fibrocartilaginous labrum, and femoral head acetabular congruency. fter the intraarticular instillation of contrast material, a variety of T1-weighted spin-echo and SPGR imaging sequences with and without fat saturation should be acquired using a small field of view. Imaging of the vascular Phase The avascular or necrotic phase of LCP disease typically lasts for several months and is commonly painful and associated with a limp. ffected children, on occasion, may be asymptomatic early in the avascular phase. If acquired early in the avascular phase, radiographs can be entirely normal. It is during this time, however, that the earliest changes of LCP disease become evident on MRI [13]. variety of MRI findings may be observed in the avascular phase of LCP dis TLE 1: Institutional MRI Protocol for Evaluation of Suspected and Known Legg-Calvé-Perthes Disease Parameter STIR FSE T1-Weighted SE T2-Weighted FSE FS T1-Weighted SPGR FS 3D MR a T1-Weighted SPGR FS Contrast-Enhanced a Plane Coronal Coronal xial Coronal Coronal Coronal/sagittal No. of echo trains N N N Inversion recovery time (ms) 150 N N N N N Flip angle ( ) N N N TE (ms) TR (ms) 3, , No. of signal averages Note Coverage should extend from iliac crests through lesser trochanter of proximal femora. FSE = fast spin-echo, SE = spin echo, FS = fat-saturated, SPGR = spoiled gradient-recalled echo, MR = MR angiography, N = not applicable. a fter IV injection of 0.1 mmol/kg of gadolinium-based contrast material. JR:193, November

3 Dillman and Hernandez ease. ll or only a portion of the proximal femoral ossific nucleus may become necrotic [4, 17, 18]. Necrosis is most commonly subchondral and central in location (Figs. 3 5), and it is less often medial and lateral [9]. Proximal femoral epiphyseal MR signal abnormality may be observed early in the course of LCP disease on unenhanced imaging sequences. On T1-weighted imaging sequences, the proximal femoral ossific nucleus typically contains focal or diffuse abnormally low or intermediate signal [7, 18, 19] (Figs. 4 8). T2-weighted/STIR imaging sequences can show variable signal intensity, including areas of increased signal thought to represent bone marrow edema. On occasion, curvilinear subchondral T2-weighted signal hyperintensity and T1-weighted signal hypointensity may be observed in the anterosuperior aspect of the femoral head (Fig. 4). This finding, referred to as the crescent sign (or Caffey sign), is best seen on coronal and sagittal images and suggests the presence of a subchondral fracture. Epiphyseal signal hypointensity on all imaging sequences, including contrast-enhanced sequences, suggests more advanced necrosis as well as the presence of ossific nucleus microfractures [7, 9] (Figs. 5, 7, and 8). The normal hip shows early rapid enhancement after the IV administration of gadolinium-containing contrast material [4, 5]. Contrast-enhanced imaging may reveal partial (Figs. 1 4) or complete (Figs. 2, 6, and 7) nonenhancement of proximal femoral epiphysis in the avascular phase of LCP disease [4]. bnormal femoral head enhancement is best depicted approximately 2 minutes after the IV injection of contrast material using subtraction techniques [4, 5] (Figs. 2, 6, and 8 10). There is typically asymmetric anteroposterior involvement of the femoral head; the anterior portion is frequently the earliest and most prominently involved [10]. variety of other MRI findings may also be observed in early LCP disease. There is evidence to suggest that mild ischemia to the proximal femoral epiphysis may not result in frank necrosis but instead cause only delayed ossification and failure of ossification center growth [17]. Proximal femoral ossific nucleus morphologic changes, such as articular surface flattening, may also suggest early LCP disease [19]. This flattening is likely due to a combination of necrotic trabecular bone collapse and resorption. Mechanical deformation of the femoral head may result in additional ischemic episodes and increased necrosis [17]. Overlying femoral head articular cartilage can be abnormally thickened [8, 17, 19] and show abnormal signal characteristics [8]. rticular cartilage may continue to proliferate despite ischemia due to nutrition derived from synovial fluid [20]. djacent acetabular articular cartilage and the fibrocartilaginous labrum may also hypertrophy [19]. Finally, periarticular T2- weighted/stir signal hyperintensity and associated contrast enhancement are commonly observed, suggesting the presence of joint effusion and synovitis (pannus formation) [19, 21] (Figs. 1 and 4 10). Such synovitis may be visualized greater than 60 months after the diagnosis of LCP disease [21]. Imaging of Revascularization and Reparative Phases The revascularization and reparative or healing phases of LCP disease are characteristically symptomatic and typically persist for several years. During these phases, unenhanced and contrast-enhanced imaging sequences frequently reveal heterogeneous proximal femoral epiphyseal signal, likely reflecting a combination of necrotic changes, revascularization, and reparation (Figs. 5, 6, 8, and 9). fter the avascular phase, necrotic bone is eventually resorbed and replaced by granulation tissue. With time, granulation tissue is replaced by more mature fibrous tissue, cartilage, and, eventually, mature trabecular bone [7]. Revascularization of the proximal femoral epiphysis likely occurs by one of two processes [4, 22]. First, preexisting epiphyseal vessels may be recanalized. lternatively, reperfusion may occur via neovascularization. Revascularized areas of the proximal femoral epiphysis typically show T2-weighted/STIR signal hyperintensity and contrast enhancement [4, 13] (Figs. 5, 6, 8, and 9). reas of revascularized epiphysis may even hyperenhance after the IV administration of contrast material when compared with areas that were never avascular. Early reperfusion of the lateral column is associated with improved prognosis [4]. Revascularized portions of a femoral head may show persistent enhancement on delayed imaging [4]. variety of epiphyseal abnormalities may be observed in the revascularization and reparative phases of LCP disease. Morphologic changes related to epiphyseal necrosis may include articular surface flattening (coxa plana) and fragmentation (Figs. 8, 10, and 11). Epiphyseal fragments may show dissimilar signal characteristics, suggesting different phases of the disease process [9] (Fig. 8). MRI can also be used to assess for lateral subluxation of the femoral head or loss of containment (Figs. 7 14). This finding is thought most commonly to be due to a combination of cartilage thickening, joint effusion, and synovial thickening [8, 23]. Lateral displacement of the femoral head may also result in abnormal horizontal positioning or upward eversion of the fibrocartilaginous labrum [24] (Figs. 9 13). With healing, proximal femoral epiphyseal height is slowly restored, ossific fragments coalesce, and mature trabecular bone again constitutes the entire ossific nucleus. fter approximately 6 years, the epiphysis typically again shows normal MR signal characteristics [18]. Catterall et al. [17] also documented that the proximal femoral physis is abnormal in nearly all cases of LCP disease. Such physeal lesions may be the result of either the primary ischemic insult or secondary to abnormal mechanical loads. The normal proximal femoral physis is hypointense on T1-weighted imaging and hyperintense on T2-weighted/STIR imaging [24]. bnormalities of the physis are best depicted by MRI [8]. MRI findings that suggest possible physeal involvement by LCP disease include increased undulation of the growth plate (W- or M-shaped) (Figs. 7 and 14), deepening of the growth plate or cupping, epiphyseal metaphyseal osseous fusion (bone bridge or bar formation across the physis) (Fig. 12), or physeal cystic change [8, 24]. bnormal physeal signal and enhancement may also be due to the presence of abnormal transphyseal blood vessels (Figs. 2, 5, 7, 9, and 10). Such physeal abnormalities may disturb the physis, leading to premature growth arrest of the femur [8]. n assortment of metaphyseal findings may also be observed in the revascularization and reparative phases of LCP disease. t radiography, abnormal metaphyseal radiolucencies, or cysts, may be seen. t MRI, these areas of radiographic lucency commonly have signal characteristics identical to the adjacent physis, suggesting a cartilaginous cause, perhaps ectopic physeal cartilage [8]. Not all metaphyseal cysts are due to ectopic cartilage, however [17, 25, 26] (Fig. 15). Kim et al. [26] documented that such radiolucencies may be due to extension of physeal cartilage, metaphyseal osseous resorption, or fibrovascular (granulation) tissue deposition. Catterall et al. [17] showed that such radiolucencies may be due to increased metaphy 1396 JR:193, November 2009

4 MRI of Legg-Calvé-Perthes Disease seal adipose tissue, the presence of fibrocartilage, disorganized ossification, or, most commonly, metaphyseal extension of unossified growth plate. In a study by Eckerwall et al. [27], histopathologic examination of 22 core biopsy specimens from the proximal femoral metaphysis of 22 LCP disease patients revealed fat necrosis, vascular proliferation, and focal fibrosis. bnormal metaphyseal broadening (coxa magna) (Figs. 9 12) and shortening (coxa breva) (Figs. 9 11) may be observed with healing. MRI and Prognosis of Legg-Calvé- Perthes Disease Multiple MRI findings have prognostic value in the setting of LCP disease. First, the extent and distribution of epiphyseal necrosis have prognostic implications. s the extent of femoral head necrosis increases, overall prognosis worsens [9, 28]. Conversely, prognosis is improved when only a small amount of femoral head is affected. Prognosis is also adversely affected by involvement of the lateral column or pillar, the lateral most one third of the femoral head [10, 28, 29]. Conversely, preservation of femoral head lateral column perfusion appears to be associated with an improved prognosis [5, 22] (Figs. 1, 2, 8, and 10). Disturbance of the physis, including the presence of transphyseal neovascularity (Figs. 2, 5, 7, 9, and 10), is associated with overall worse prognosis, including increased risk of proximal femoral growth disturbance [4, 8, 24]. Up to 90% of femurs affected by LCP disease may show decreased growth and up to 25% of affected hips may have premature physeal closure at radiography [30]. The affected femur is on average cm shorter than the contralateral normal femur [31]. De Sanctis et al. [24] suggested that necrosis of less than 50% of the proximal femoral epiphysis was never associated with severe physeal involvement, increased lateral extrusion, or metaphyseal changes. They concluded that disturbance of the physis may be the greatest single predictor of poor outcomes in LCP disease [24]. Subchondral ossific nucleus fracture also has prognostic significance because the extent of this finding appears to correlate with the extent of eventual necrosis at radiography [32, 33]. This finding may also be visible at MRI (Fig. 4). Metaphyseal signal abnormalities (Figs. 2, 5, 9, and 15) in the setting of LCP disease, particularly physeal bridging (Fig. 12), worsen prognosis, with a resultant increased risk of future hip deformity and growth disturbance [8, 17, 26]. MRI and Complications of Legg- Calvé-Perthes Disease MRI can be used to depict and characterize several of the most important complications of LCP disease. lthough it is estimated that approximately 60 70% of hips affected by LCP disease heal spontaneously without functional impairment at maturity, a considerable number of affected hips become painful later in life, with many eventually requiring arthroplasty. Premature degeneration (secondary osteoarthrosis) of the hip joint is far and away the most common complication observed in healed LCP disease. Factors that predict early degeneration of the hip joint include later age of disease onset and abnormal shape of the femoral head at the time of skeletal maturity [31]. bnormal contour of the femoral head leads to incongruency between articular cartilage surfaces, promoting premature degeneration. Premature hip joint degenerative changes may be observed as early as the second or third decades of life in individuals affected by LCP disease and are well depicted by MRI. MRI findings include abnormal joint space narrowing, with thinning of femoral head and acetabular articular cartilage as well as subchondral cyst (geode) and osteophyte formation (Figs. 13 and 16). Conventional arthrography has traditionally played an important role in the assessment of femoral head containment and articular surface congruency [23, 34]. rthrography is particularly important in the evaluation of hip joint articular surface characteristics before surgery because there is little correlation between the contour of proximal femoral ossific nucleus and that of the cartilaginous femoral head [23, 35]. This imaging technique also allows dynamic multipositional imaging of the hip joint and the evaluation of range of motion and possible hinged abduction. With abduction of the affected hip, there may be hinging of the femoral head on the lateral acetabular margin, which results in failure of the femoral head to move medially and associated medial joint space widening [23, 34]. MRI can also be used to evaluate the relationship of femoral head and acetabular articular cartilage surfaces. Recent studies have shown that MRI is as accurate as conventional arthrography in evaluating hips affected by LCP disease. study by Jaramillo et al. [23] using multipositional MRI in an open magnet scanner configuration showed that this imaging technique was comparable to conventional arthrography for the evaluation of femoral head containment and congruency of articular surfaces. Their study also showed that MRI could be used to differentiate joint fluid from articular cartilage as well as to evaluate the extent of femoral head flattening, medial joint space widening, and femoral head acetabular coverage in abduction (increased, unchanged, or decreased [hinged]) [23]. Other advantages provided by MRI when compared with conventional arthrography include a lack of invasiveness, absence of ionizing radiation, reduced need for general anesthesia, and the ability to evaluate bone marrow [23]. MRI (without intraarticular instillation of contrast material) may also be more physiologic than conventional arthrography because no extra fluid has been added to the joint space [23]. study by Weishaupt et al. [34] also compared MR images of hips affected by LCP disease acquired in neutral, abducted, and adducted positions with conventional arthrography in an open MRI scanner configuration. Their study specifically evaluated for loss of femoral head sphericity, femoral head articular cartilage surface irregularity, the presence of hinged abduction, and loss of femoral head containment, and revealed complete agreement between conventional arthrography and MRI [34]. Loss of hip joint congruency can also be established after the intraarticular instillation of contrast material (Fig. 17). MRI can also assess for other LCP disease-related complications. Loss of femoral head containment and hinged abduction may result in repetitive labral trauma. Resultant labral signal hyperintensity and enlargement suggest premature labral degeneration (Fig. 13). Evaluation for frank labral tearing is best carried out using T1-weighted imaging sequences after the intraarticular instillation of gadolinium-containing contrast material. Using this imaging technique, tears appear as areas of focal labral signal hyperintensity (Fig. 17). Finally, MRI can also be used to excellently depict intraarticular ossific fragments (Fig. 14) as well as areas of transphyseal bone bridging (Fig. 12) that are associated with proximal femur deformity and growth arrest [8]. Summary MRI is a valuable tool in the evaluation of LCP disease that may be used to guide both nonsurgical and surgical management of the JR:193, November

5 Dillman and Hernandez condition. This imaging technique can be used to document the presence of femoral head necrosis, accurately stage the disease process, provide important prognostic information, and diagnose a variety of associated complications. Contrast-enhanced MRI may prove to be particularly beneficial in the evaluation of suspected early (radiographically occult) proximal femoral epiphyseal necrosis and in the appraisal of femoral head revascularization. Radiologists should be aware of the various MRI findings of LCP disease, including the condition s different stages. Early detection and treatment of LCP disease are imperative because they may prevent femoral head deformity, articular surface incongruity, and loss of containment, all of which adversely affect overall outcome. Finally, MRI may identify other causes of hip pain in the setting of suspected early LCP disease. References 1. arker DJ, Hall J. The epidemiology of Perthes disease. Clin Orthop Relat Res 1986; 209: Kenet G, Ezra E, Wientroub S, et al. Perthes disease and the search for genetic associations: collagen mutations, Gaucher s disease and thrombophilia. J one Joint Surg r 2008; 90: Mont M, Jones LC, Hungerford DS. Nontraumatic osteonecrosis of the femoral head: ten years later. J one Joint Surg m 2006; 88: Lamer S, Dorgeret S, Khairouni, et al. Femoral head vascularisation in Legg-Calvé-Perthes disease: comparison of dynamic gadolinium-enhanced subtraction MRI with bone scintigraphy. Pediatr Radiol 2002; 32: Sebag G, Ducou Le Pointe H, Klein I, et al. Dynamic gadolinium-enhanced subtraction MR imaging: a simple technique for the early diagnosis of Legg-Calvé-Perthes disease preliminary results. Pediatr Radiol 1997; 27: Uno, Hattori T, Noritake K, Suda H. Legg- Calvé-Perthes disease in the evolutionary period: comparison of magnetic resonance imaging with bone scintigraphy. 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Prognostic evaluation of Legg-Calvé-Perthes disease by MRI. Part I: The role of physeal involvement. J Pediatr Orthop 2000; 20: Johnson C, May D, McCabe KM, Guse R, Resnick D. Non-cartilaginous metaphyseal cysts in Legg-Calvé-Perthes disease: report of a case. Pediatr Radiol 1997; 27: Kim HK, Skelton DN, Quigley EJ. Pathogenesis of metaphyseal radiolucent changes following ischemic necrosis of the capital femoral epiphysis in immature pigs: a preliminary report. J one Joint Surg m 2004; 86-: Eckerwall G, Hochbergs P, Simesen K, Willén H, Egund N, Wingstrand H. Metaphyseal histology and magnetic resonance imaging in Legg-Calvé-Perthes disease. J Pediatr Orthop 1997; 17: Wiig O, Terjesen T, Svenningsen S. Prognostic factors and outcome of treatment in Perthes disease: a prospective study of 368 patients with fiveyear follow-up. J one Joint Surg r 2008; 90: Herring J, Kim HT, rowne R. Legg-Calve- Perthes disease. 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Femoral head shape in Legg- Calvé-Perthes disease: correlation between conventional radiography, arthrography and MR imaging. cta Radiol 1994; 35: JR:193, November 2009

6 MRI of Legg-Calvé-Perthes Disease Fig. 1 9-year-old boy with spondyloepiphyseal dysplasia and left hip pain., nteroposterior radiograph of pelvis and hips shows changes consistent with spondyloepiphyseal dysplasia, including flattening of femoral heads and platyspondyly (asterisk)., Two-dimensional T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced image reveals near-complete left proximal femoral ossific nucleus nonenhancement (white arrowheads), suggesting superimposed left hip avascular necrosis. Portion of left femoral head lateral column hyperenhances (arrow), and enhancement surrounding left femoral head and neck (black arrowheads) suggests synovitis. Fig. 2 5-year-old boy with bilateral Legg-Calvé-Perthes (LCP) disease., Three-dimensional T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced subtracted image acquired 1 minute after IV administration of gadolinium-containing contrast material shows necrosis of entire right femoral head. Medial aspect of left femoral head also fails to enhance, although left lateral column vascular supply is intact (arrow). Right proximal femoral metaphyseal (arrowheads) and physeal enhancement correspond to T2-weighted signal abnormality in same location (not shown) and is likely due to neovascularity and granulation tissue., one scintigraphy image acquired 3 hours after IV injection of 99m Tc methylene diphosphonate (MDP) shows no right femoral head radiopharmaceutical uptake (arrowhead), supporting diagnosis of necrotic phase LCP disease. Left femoral head was reported to be normal, although MRI shows necrosis involving medial proximal left femoral ossific nucleus. JR:193, November

7 Dillman and Hernandez Fig. 3 7-year-old boy with right hip pain. Sagittal 2D T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced MR image reveals central necrosis of right proximal femoral ossific nucleus (arrowheads) and sparing of anterior and posterior femoral head. Fig year-old boy with right hip pain and limp for 2 months. Right hip radiographs were normal. and, Coronal STIR MR image () shows curvilinear right proximal femoral epiphyseal subchondral (black arrowhead) and right hip joint (white arrowheads) signal hyperintensity, whereas coronal T1-weighted spin-echo MR image () shows femoral head signal hypointensity (black arrowhead). Findings suggest right hip subchondral fracture. (Fig. 4 continues on next page) 1400 JR:193, November 2009

8 MRI of Legg-Calvé-Perthes Disease C Fig. 4 (continued) 13-year-old boy with right hip pain and limp for 2 months. Right hip radiographs were normal. C, Three-dimensional T1-weighted spoiled gradient-recalled echo fat-saturated image acquired 2 minutes after IV administration of gadolinium-containing contrast material shows central nonenhancement of subchondral right proximal femoral ossific nucleus (arrows). D, nteroposterior radiograph 10 months later reveals findings consistent with right hip Legg-Calvé-Perthes disease, including proximal femoral epiphyseal flattening, fragmentation, and sclerosis as well as metaphyseal radiolucency. Fig. 5 5-year-old girl with known right Legg-Calvé-Perthes disease. MRI examination was performed for staging purposes., Coronal STIR MR image shows flattening and abnormal signal hypointensity involving central portion of proximal femoral ossific nucleus (arrow), whereas lateral and medial columns show mild signal hyperintensity. Note increased signal in right femoral proximal metaphysis as well as small amount of signal hyperintensity along medial aspect of hip joint (arrowhead)., Coronal T1-weighted spoiled gradient-recalled echo (SPGR) fat-saturated MR image reveals abnormal signal hypointensity involving central portion of right proximal femoral ossific nucleus (arrow). (Fig. 5 continues on next page) D JR:193, November

9 Dillman and Hernandez Fig. 5 (continued) 5-year-old girl with known right Legg-Calvé-Perthes disease. MRI examination was performed for staging purposes. C, Sagittal 3D T1-weighted SPGR fat-saturated contrast-enhanced MR image shows central proximal femoral ossific nucleus nonenhancement (arrow), confirming presence of necrosis. Note abnormal enhancement involving anterior proximal femoral metaphysis and physis (black arrowhead), whereas enhancement surrounding right femoral head and neck suggests synovitis (white arrowheads). Fig. 6 9-year-old boy with bilateral asynchronous Legg-Calvé-Perthes (LCP) disease., Coronal T1-weighted spin-echo MR image shows right proximal femoral ossific nucleus curvilinear signal hypointensity (arrowhead). Left femoral head is flattened and also contains abnormal signal hypointensity., Two-dimensional T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced subtraction image shows nonenhancement of entire right femoral head and extensive right hip joint synovitis. Note heterogeneous enhancement of left proximal femoral epiphysis and left hip synovitis as well. MRI findings support diagnosis of bilateral LCP disease, with right hip in necrotic phase and left hip likely in revascularization phase. C 1402 JR:193, November 2009

10 MRI of Legg-Calvé-Perthes Disease C Fig. 7 3-year-old boy with limp for 1 month., Coronal T1-weighted spin-echo MR image shows diffuse signal hypointensity (arrowheads) and flattening of right proximal femoral ossific nucleus., Sagittal T2-weighted fast spin-echo MR image also reveals diffuse right proximal femoral ossific nucleus signal hypointensity (arrowheads) and flattening. C, Coronal 2D T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced MR image shows near-complete nonenhancement of right proximal femoral ossific nucleus (white arrowheads), confirming diagnosis of right hip Legg-Calvé-Perthes (LCP) disease. Note small amount of enhancement along right femur proximal physis as well as enhancement surrounding right femoral head and neck due to synovitis (black arrowhead). lso note normal enhancement of left proximal femoral ossific nucleus and possible subtle left hip synovitis. D, Coronal T1-weighted spin-echo MR image acquired 2 years later shows findings consistent with bilateral LCP disease, including marked undulation of proximal femoral physes as well as lateral extrusion of femoral heads. D JR:193, November

11 Dillman and Hernandez Fig. 8 7-year-old boy with known left hip Legg-Calvé-Perthes disease. MRI examination was performed for staging purposes., Coronal T1-weighted spin-echo MR image shows flattening and fragmentation of left proximal femoral ossific nucleus (arrowheads) as well as mild loss of containment. ll ossific fragments show abnormal signal hypointensity., Three-dimensional T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced subtraction MR image shows nonenhancement of proximal femoral ossific nucleus central fragment (white arrowheads) confirming presence of necrosis. Note hyperenhancement of medial column, possibly due to neovascularity and granulation tissue, whereas there is normal lateral column enhancement (arrow), suggesting relatively preserved vascularity. Enhancement along medial aspect of left femoral head and neck is consistent with synovitis (black arrowheads). Fig. 9 7-year-old boy with known right Legg-Calvé-Perthes disease., Coronal STIR MR image shows abnormal signal hyperintensity involving proximal right femoral metaphysis and physis (black arrowheads) disrupting normal growth plate. bnormal signal hyperintensity is also seen along medial aspect of hip joint (white arrowhead). Right hip labrum is displaced upward (arrow), right femoral neck is shortened and broadened, and there is mild loss of containment., Coronal 2D T1-weighted spoiled gradient-recalled echo fat-saturated contrast-enhanced subtraction MR image shows focal central nonenhancement of right proximal femoral ossific nucleus (arrow), consistent with necrosis. Hyperenhancement in proximal right femoral metaphysis and physis (black arrowheads) corresponds to STIR signal abnormality in same location, likely representing neovascularity and granulation tissue. Enhancement along medial aspect of hip joint suggests synovitis (white arrowhead) JR:193, November 2009

12 MRI of Legg-Calvé-Perthes Disease Fig year-old boy with right Legg-Calvé-Perthes disease. MRI examination was performed for staging purposes., Coronal 2D T1-weighted spoiled gradient-recalled echo (SPGR) fat-saturated MR image shows abnormal flattening and fragmentation of right proximal femoral ossific nucleus. Right femoral neck appears abnormally broadened and shortened (asterisk), and there is mild lateral extrusion of right femoral head. Right acetabulum is deformed, and right hip joint labrum is horizontally oriented (arrow)., Coronal 3D T1-weighted SPGR fat-saturated contrast-enhanced subtraction MR image shows focal nonenhancement of right proximal femoral epiphysis (white arrowheads). Note abnormal enhancement along right femoral proximal physis (arrow) that likely represents neovascularity related to attempted revascularization as well as right hip joint synovitis (black arrowheads). Fig year-old boy with bilateral Legg-Calvé-Perthes disease. Coronal T1- weighted spoiled gradient-recalled echo fat-saturated MR image shows bilateral proximal femoral ossific nucleus flattening, fragmentation, and lateral extrusion. Femoral necks are abnormally shortened and broadened, whereas hip joint labra are horizontally oriented (arrows). Fig year-old boy with known right Legg-Calvé-Perthes disease. Coronal T1- weighted spoiled gradient-recalled echo fat-saturated MR image shows abnormal osseous bridging between right central proximal femoral metaphysis and adjacent epiphysis (arrowheads). Central right proximal femoral physis is interrupted. Right femoral head is flattened and laterally extruded, whereas right femoral neck is abnormally broadened. Right hip joint labrum is horizontally oriented (arrow). JR:193, November

13 Dillman and Hernandez Fig year-old girl with history of left Legg-Calvé-Perthes disease, left hip pain, and hinged abduction at radiography. Coronal T1-weighted image of left hip after intraarticular administration of contrast material shows femoral head deformity, loss of containment with increased medial joint space fluid (asterisk), and horizontal displacement of labrum (arrow). Left labrum contains extensive increased signal that is likely due to repetitive trauma. Degenerative subchondral cyst is seen in left femoral head (arrowheads), and there is marked femoral head articular surface irregularity and cartilage thinning. Fig year-old boy with left Legg-Calvé-Perthes disease and concern for intraarticular body. Coronal T1-weighted MR image shows focal signal hypointensity in left hip joint space (arrow), consistent with necrotic ossific intraarticular body. Note also evidence of femoral head deformity, loss of containment, and proximal femur physeal disturbance. Fig year-old boy with left hip Legg-Calvé-Perthes disease., Coronal T1-weighted spin-echo MR image shows diffuse left proximal femoral ossific nucleus signal hypointensity (arrowheads). dditional focus of metaphyseal signal hypointensity abuts physis (arrow)., Coronal T2-weighted spin-echo MR image shows focal signal hypointensity in medial left proximal femoral ossific nucleus (white arrowheads) as well as focal signal hyperintensity in metaphysis (arrow). Metaphyseal abnormality is behaving as cyst and shows signal characteristics different from physeal and articular cartilage. Signal hyperintensity medial to hip joint (black arrowheads) suggests presence of either joint effusion or synovitis JR:193, November 2009

14 MRI of Legg-Calvé-Perthes Disease Fig year-old woman with history of left Legg-Calvé-Perthes disease and increasing left hip pain., Coronal T1-weighted spin-echo MR image through anterior aspect of left femoral head shows multiple hyperintense subchondral cysts that contain proteinaceous fluid or blood products (black arrowheads). Note marked femoral head articular surface irregularity (white arrowhead)., nother T1-weighted spin-echo MR image shows marked loss of articular cartilage resulting in severe joint space narrowing (arrowhead) as well as multiple osteophytes (arrows). Fig year-old girl with history of left Legg-Calvé-Perthes (LCP) disease and intractable left hip pain., Coronal STIR MR image after intraarticular administration of gadolinium-containing contrast material reveals normal left femoral head bone marrow signal, consistent with healed LCP disease. Note left superomedial joint space widening due to loss of congruity between femoral head and acetabular articular cartilage surfaces (arrow)., Sagittal-oblique T1-weighted MR image from same study shows linear signal hyperintensity in anterosuperior left labrum (arrow), consistent with tear. FOR YOUR INFORMTION This article is available for CME credit. See for more information. JR:193, November