MRI of knee osteonecrosis in children with leukemia and lymphoma: Part 2, clinical and imaging patterns

OBJECTIVE: This aim of this study was to explore the relationship between MRI findings and clinical symptoms of knee osteonecrosis in children and to determine the significance of this relationship. Such information is important for early diagnosis of this frequent complication and for choosing an appropriate treatment strategy. MATERIALS AND METHODS: Osteonecrotic lesion size and location were determined in a retrospective analysis of MR images of the knee obtained in our institution during the past 10 years. Association between MRI findings and clinical symptoms expressed by the knee scores was tested for a subgroup of our patient population who had clinical evaluation of the knees in the orthopedic clinic within 6 weeks of their MRI studies. RESULTS: In 80% of patients, osteonecrosis was bilateral. Lesions were distributed as follows: femur and tibia, 66% of the knees; femur alone, 26%; and tibia alone, 8%. Clinical symptoms of knee osteonecrosis were associated with lesions involving the articular surface of the distal femur, large lesions, and involvement of any part of the tibia. MR images showed milder osteonecrosis in patients who were less than 10 years old at the time of primary diagnosis. CONCLUSION: Osteonecrosis affecting the knees of children treated for leukemia and lymphoma is mostly asymptomatic. Children who are 10 years old or older have signs of more advanced osteonecrosis. Clinical symptoms often lag MRI presentation and may develop late in the course of the disease. Routine MRI evaluation is recommended for timely diagnosis of treatment-induced osteonecrosis.     

Changes in the cartilaginous contour of Legg-Calvé-Perthes disease: calculation on T1-weighted MR images]

T1-weighted MR images of Legg-Calvé-Perthes disease (LCPD) were classified into three groups on the basis of radiographic stage, and morphological differentiation for staging was attempted. In the stage of fragmentation, both enlargement and flattening of the cartilaginous contour surrounding the epiphysis could be recognized on MRI, and the growth plate showed more curvature than normal. This produced flattening of the epiphysis in the shape of a crescent. We confirmed these findings using four indexes for the measurement of cartilaginous outline, and the stage of avascular necrosis and fragmentation could be clearly differentiated. Cartilaginous deformities on MRI are very useful for differentiating between the stage of avascular necrosis and fragmentation.     

Physeal widening in the knee due to stress injury in child athletes

OBJECTIVE: The objective of our study was to describe the MRI appearance of and possible mechanism responsible for physeal widening in the knees of high-level child athletes. CONCLUSION: Widened physes in the knees of skeletally immature child athletes have MR signal characteristics similar to the normal physis but likely are a sign of stress injury. These children should cease the offending sport and rest the knee to allow rapid healing.     

Dynamic contrast-enhanced subtraction and delayed MRI of gastric tumors: radiologic-pathologic correlation

PURPOSE: Our goal was to determine whether dynamic MR subtraction images could be used to detect and stage gastric tumors. METHOD: Dynamic MR subtraction images were prospectively performed in 20 patients without gastric lesions and in 39 patients with gastric tumors. The flat- or depressed-type early gastric cancers were excluded. The MR findings were assessed for layered pattern of the normal gastric wall, detectability of tumors, enhanced pattern of tumor, and depth of the tumor invasion. Surgical specimens were obtained from 30 of the patients with tumors, and histopathologic sections were made in the dynamic MR scanning direction. RESULTS: The three-layered structure of the normal gastric wall was apparent in more of the dynamic MR subtraction images (60%) than of the nonsubtraction images (30%) in the control group. All 39 gastric tumors were detected by MRI. The intact inner layers overlying stromal tumors and outer layers interrupted by advanced gastric cancers were clear on the subtracted images. MRI accurately T-staged 88% of the gastric cancers. CONCLUSION: Dynamic MR subtraction images can be used to identify gastric tumors and to stage gastric cancers.     

Transverse geniculate ligament of the knee: appearance and frequency on plain radiographs.

The aims of the study were to determine the frequency of visualization of the normal transverse geniculate ligament (TGL) of the knee on lateral plain radiographs with magnetic resonance imaging (MRI) as a reference, and to determine features that make this ligament apparent on plain radiographs. 50 consecutive lateral plain radiographs and sagittal T1-weighted images of corresponding knees were evaluated prospectively. A TGL was considered visualized on plain radiographs when an opacity of soft-tissue density was apparent in the posterior part of the Hoffa's fat pad. The TGL was identified in 29 of the 50 (58%) sagittal MR images; a TGL was observed on the lateral plain radiographs of six patients (12%). Correlation with the MR images showed that, when visualized on plain radiographs, the ligament is at least 3 mm thick and completely surrounded by fat. Our study shows that the TGL is a normal variant that can be recognized frequently on lateral plain radiographs of the knee.     

Acute injury of the ligaments of the knee: magnetic resonance evaluation

Eleven acutely injured knees and 13 normal knees were examined by magnetic resonance imaging (MRI) to assess the value of this modality in detecting acute ligamentous injury of the knee. The presence of torn ligaments in the injured knees was determined by arthroscopy and/or arthrotomy in ten cases and clinical follow-up in one case. The anterior and posterior cruciate ligaments (ACL and PCL) were demonstrated by sagittal spin echo (SE) images through the intercondylar notch (TE = 30 ms; TR = 2,000 ms). The tibial and fibular collateral ligaments (TCL and FCL) were evaluated on coronal SE images (TE = 30 ms, TR = 200 or 530 ms; TE = 120 ms, TR = 2,000 or 2,120 ms). The ACL and PCL were considered torn on MR if they appeared disrupted or were not seen in their normal anatomical positions. The collateral ligaments were considered torn if abnormal high-intensity signal was noted in adjacent soft tissues on TE = 120 ms images or if disruption of a ligament was apparent. Eleven of 15 torn ligaments and 80 of 81 normal ligaments were correctly identified by these criteria. It is concluded that MR imaging may be useful in detecting acute injury of ligaments of the knee.     

CT与MRI对创伤性膝关节积脂血症的诊断价值

目的探讨CT与MRI对创伤性膝关节积脂血症(traumaticlipohemarthrosis,TLH)的诊断价值。方法回顾性分析34例TLH的普通X线平片、CT及MRI的影像学表现,并探讨其诊断价值。结果 34例患者中,左膝关节22例,右侧膝关节12例。34例均行普通X线平片检查,提示膝关节骨折32例;16例行CT检查,15例可见明确脂肪、关节液、血液不同成分的分层密度改变。18例行MRI检查,均可见"脂肪-血液接口征"。并拟诊隐性骨折2例。结论 X线平片对骨折的诊断意义大,对积脂血症的诊断帮助不大。CT及MRI均能很好显示创伤性TLH,均有"脂肪-血液接口征"这一特征性表现,尤其MRI除显示积脂血症的典型征象外,对隐性骨折的诊断更有意义。     

The utility of MR in assessing Blount disease

OBJECTIVE: To review the MR appearances of Blount disease. DESIGN AND PATIENTS: The MR examinations of six knees in four patients (ages 6-7 years) with Blount disease were reviewed. RESULTS: All patients showed delay in ossification of the medial tibial epiphysis. A spectrum of changes was seen in and around the tibial growth plate including: widening and depression of the medial growth plate; small and deep intrusions of cartilage into the metaphysis; edema of the medial tibial epiphysis and medial and lateral metaphysis; varus deformity of the lower leg; widening of the lateral growth plate; osteochondral injury to the medial femoral condyle; hypertrophy of the medial meniscus; focal bone bridging. CONCLUSION: MR appearances are consistent with the primary abnormality in Blount disease, which is failure of endochondral ossification of the medial growth plate. MR examination is useful in surgical planning.     

磁共振诊断脊椎骨母细胞瘤的临床应用价值

目的:探讨脊椎骨母细胞瘤的磁共振(MRI)表现、诊断价值及其临床特点。方法:8例脊椎骨母细胞瘤患者,术前均行MRI检查,主要症状为四肢不全性瘫痪及疼痛,治疗上行肿瘤切除或刮除治疗,椎体病变者行植骨及内固定术。结果:8例均经病理确诊为骨母细胞瘤,其中6例为良性,2例为侵袭性。肿瘤起源于脊椎椎体2例,起源于脊椎附件6例;发病部位颈椎2例,胸椎3例,腰椎3例。脊椎骨母细胞瘤MRI主要表现为椎体或附件溶骨性膨胀性骨质破坏,T1WI上为低或等信号,T2WI上可为低、等或高多种信号成分,肿瘤内钙化或骨化在T2WI上为低信号,T1WI上为等或低信号;周边硬化环在T1WI和T2WI上均为低信号;软组织肿块较明显,向椎管突出可压迫脊髓;增强扫描肿瘤中度到明显强化,囊变、硬化边缘不强化。侵袭性骨母细胞瘤边界不清,可侵犯周围组织。结论:脊椎骨母细胞瘤发病年龄较轻,发病部位以脊椎附件较多见。MRI多方位、多序列成像及增强扫描,能较好显示脊椎骨母细胞瘤的各种病理改变,对诊断、手术定位、分期尤其在显示脊髓继发改变有重要价值。     

Pathogenesis of the Segond fracture: anatomic and MR imaging evidence of an iliotibial tract or anterior oblique band avulsion

PURPOSE: To demonstrate the normal anatomy of the stabilizing structures of the lateral aspect of the knee and to investigate pathogenesis of the Segond fracture, with emphasis on the iliotibial tract (ITT) and anterior oblique band (AOB) of the fibular collateral ligament. MATERIALS AND METHODS: Dissection of the region of the AOB, ITT, and lateral capsular ligament was performed in three cadaveric knees, with placement of gadopentetate dimeglumine-filled tubes along their course and tibial insertions. These knees, in addition to three nondissected knees, were studied with magnetic resonance (MR) imaging by using standard and specialized oblique planes. Specimen sectioning provided anatomic correlation. Retrospective review of radiographs and MR images in 17 patients with acute Segond fractures was performed, and the relationship between the fragment and the demonstrated lateral supporting structures of the knee was noted. RESULTS: Anatomic dissection and MR imaging of the cadaveric knees demonstrated a broad tibial insertion of the ITT, with fibers extending posterior to the Gerdy tubercle. A firm band of tissue, the AOB, extended from the fibular collateral ligament to the midportion of the lateral tibia, the typical site of a Segond fracture. The lateral capsular ligament proved to be a mere thickening of the capsule, inserting at the lateral tibia. Clinical analysis of acute Segond fractures confirmed the frequent attachment of the ITT and AOB to the avulsed fragment. CONCLUSION: Anatomic and clinical findings suggest that fibers of the ITT and AOB are important factors in the pathogenesis of the Segond fracture.     

An arthroscopic analysis of lateral meniscal variants and a comparison with MRI findings

We reviewed 164 consecutive cases (158 patients) of arthroscopic examinations for lateral meniscal variants during the last 10 years. We classified lateral meniscal variants into four types by arthroscopic appearance, into six tear patterns by modifying OConnors classification, and compared magnetic resonance images (MRI) with arthroscopic findings. Regarding the four types, 131 cases were complete, 25 cases were incomplete, 4 cases were Wrisberg, and 4 cases were ring-shaped meniscus. The six tear patterns were as follows: 33 simple horizontal, 21 combined horizontal, 37 longitudinal, 27 central, 14 complex, and 12 radial tear. Among the 31 knees with a central tear or ring-shaped meniscus, we reviewed 25 MR images. Fifteen (60%) MRI findings were interpreted to represent a bucket-handle (displaced) tear of the normal C-shaped meniscus; 7(28%) MRI findings, a discoid meniscal tear; and the remaining 3(12%) MRI findings, a simple meniscal tear. Moreover, all ring-shaped menisci were interpreted as a displaced lateral meniscal tear on the MRI findings. Twelve patients (13 knees, 7.9%) had osteochondritis dissecans: Nine patients (10 knees) of them had a central tear, two patients (2 knees) of them had a simple horizontal tear of the discoid meniscus, and one patient (1 knee) had a ring-shaped meniscus. Twenty three patients (92.6%) with a central tear of the discoid meniscus did not have any traumatic events. For the differential diagnosis of a central tear or a ring-shaped meniscus from a bucket-handle tear of the normal C-shaped meniscus, we should take a careful history, in particular any traumatic events, we should also consider the possibility of misinterpreting the MR images though these images can provide additional information about associated abnormalities and probe carefully in the arthroscopic operations.     

Acquired cavo-varus deformity caused by an accessory calcaneus: a case report and literature review

We describe an unusual cause of an acquired cavo-varus foot deformity produced by progressive enlargement of an accessory calcaneal ossicle. A 13-year-old boy with constitutional plano-valgus flat feet noted a gradual change in foot shape associated with lateral ankle pain on ambulation following an inversion injury 2 years earlier. CT and MRI scans confirmed a large accessory calcaneal ossicle lying within the sinus tarsi, with associated marrow oedema. Following surgical excision of the ossicle, the foot returned to its original shape and the symptoms were alleviated. This is the fifth reported case of an accessory calcaneal ossicle, but the only case that has occurred in a flatfooted individual. We also present the first reported MRI images of the lesion confirming pathological marrow oedema as a response to mechanical stress.     

Evaluation of meniscal repair with serial magnetic resonance imaging: a comparative study between conventional MRI and indirect MR arthrography

Objective: To prospectively investigate the healing process of meniscal repair with plain magnetic resonance imaging (MRI) and indirect MR arthrography and to compare the two methods. Materials and methods: Twenty patients with an arthroscopic meniscal repair without clinical symptoms underwent conventional and indirect MR arthrography of the affected knee, 3, 6 and 12 months after the index operation applying a T1-w Spin Echo sequence in three planes. The size of the tear gap was measured on transverse images. The signal-to-noise ratio and the configuration of the abnormal signal were evaluated in the coronal images. Results: All patients demonstrated abnormal signal intensity at the side of the meniscal repair. The size of the gap at the previous tear side, reduced significantly by 45 and 40% on conventional MRI and indirect MR arthrography respectively, from 3 months to 1 year (P<0.05). The signal-to-noise ratio of the intrameniscal abnormal signal reduced significantly and approximately 50% from 3 to 6 months, and from 6 to 12 months postoperatively, as demonstrated with indirect MR arthrography. However, as opposed to normal meniscus, the signal-to-noise ratio of the abnormal area remains 5.5 times higher 12 months postoperatively. In contrast, the reduction of signal-to-noise ratio of the abnormal area at conventional MRI was not significant even from 3 to 12 months. In 90% of the cases, the indirect MR arthrography showed the intrameniscal abnormal signal on plain MRI, to extend to the articular surface as opposed to 25% on plain MRI. Conclusion: With indirect MR arthrography, the natural process of meniscal healing can be evaluated. Significant reduction of the size of the tear gap and significant reduction of the signal-to-noise ratio of the abnormal signal as well as its configuration are the main parameters interpretating the normal healing process.     

Osgood-Schlatter lesion: fracture or tendinitis? Scintigraphic, CT, and MR imaging features.

To determine whether the Osgood-Schlatter lesion (OS) is produced by avulsion fracture or injury to the patellar tendon, all images obtained in 28 cases of OS in 20 patients (16 scintigrams, 34 computed tomographic [CT] scans, and 27 magnetic resonance [MR] images) were retrospectively analyzed. In 21 cases, imaging was performed before and after treatment; in 20 cases, relief from pain was complete at the time of repeat examination. In all patients (100%), abnormal size of the tendon, decreased attenuation, and increase in signal intensity were compatible with the CT and MR imaging appearance of tendinitis. Distended deep infrapatellar bursa was a frequent finding, particularly on MR studies. These abnormalities had partially disappeared at follow-up examination. An ossicle was seen in only nine of 28 cases (32%); in three of seven cases with follow-up, the ossicle remained nonunited to the tibial tuberosity on follow-up studies despite relief from symptoms. This implies that healing of fracture is not essential for relief from symptoms. These results strengthen the argument that in most cases of OS, insult to the tendon and associated soft tissues, rather than avulsion fracture, causes OS.     

Height of lumbar discs measured from radiographs compared with degeneration and height classified from MR images

The relation between height of lumbar discs (measured from lateral radiographic views) and disc degeneration (classified from MR images) deserves attention in view of the wide, often parallel or interchanged use of both methods. The time sequence of degenerative signs and decrease of disc height is controversial. To clarify the issue, this cross-sectional study documents the relation between disc degeneration and disc height in a selected cohort. Forty-three subjects were selected at random from a cohort examined for potential disc-related disease caused by long-term lifting and carrying. From each subject a lateral radiographic view of the lumbar spine as well as findings from an MR investigation of (in most cases) levels T12/L1 to L5/S1 were available; thus, n = 237 lumbar discs were available for measurement and classification. Disc height was measured from the radiographic views with a new protocol compensating for image distortion and permitting comparison with normal, age- and gender-appropriate disc height. Degeneration as well as disc height were classified twice from MR images by independent observers in a blinded fashion. Disc degeneration classified from MR images is not related to a measurable disc height loss in the first stage of degeneration, whereas progressive degeneration goes along with progressive loss of disc height, though with considerable interindividual variation. Loss of disc height classified from MR images is on average compatible with loss of disc height measured from radiographs. In individual discs, however, classification of height loss from MR images is imprecise. The first sign of disc degeneration (a moderate loss of nucleus signal) precedes disc height decrease. As degeneration progresses, disc height decreases. Disc height decrease and progress of degeneration, however, appear to be only loosely correlated.     

Knee in early juvenile rheumatoid arthritis: MR imaging findings

PURPOSE: To determine the magnetic resonance (MR) imaging findings in the knee in early juvenile rheumatoid arthritis. MATERIALS AND METHODS: MR imaging (1.5 T) was performed in the more symptomatic knee in 30 children with juvenile rheumatoid arthritis with a symptom duration 1 year or less. Conventional, fast spin-echo, three-dimensional gradient-echo, and gadolinium-enhanced T1-weighted images were assessed. Two radiologists independently read the images, and a third resolved disagreements. These images were compared with knee radiographs in 27 children. RESULTS: Mean maximal synovial thickness was 4.8 mm +/- 2.4 (SD). Mean synovial volume was 15.4 mL +/- 10.8. Suprapatellar joint effusions were seen in 26 (87%) of 30 knees, meniscal hypoplasia in 11 (37%) of 30 knees, and abnormal epiphyseal marrow in eight (27%) of 30 knees. Three knees had articular cartilage contour irregularity, fissures, and/or thinning. One knee had a bone erosion. Knee radiographs showed suprapatellar fullness in 78% of the knees, joint space narrowing in one knee, and no bone abnormalities. CONCLUSION: Synovial hypertrophy and joint effusions are the most frequent MR imaging findings of knees in early juvenile rheumatoid arthritis. Early in the disease, radiographically occult cartilage and bone erosions are uncommonly seen at MR imaging. The potential relationship of synovitis to cartilage abnormalities deserves further study.     

MR imaging of Pellegrini-Stieda disease

OBJECTIVE: To describe the MR imaging of Pellegrini-Stieda disease, a post-traumatic ossification of the medial collateral ligament with typical radiographic findings. METHODS: Coronal and/or axial T2*-weighted field echo and T1-weighted conventional spin echo MR images were obtained with 1.5-Tesla or 0.5-Tesla units. Four patients with radiographic and clinical diagnoses of Pellegrini-Stieda disease were examined. Surgery was performed on one patient, and histopathologic correlation was obtained. RESULTS AND CONCLUSION: Delineating it as a signal void, T2*-weighted MR imaging indicated the precise extent of the osseous fragment in relation to the medial collateral ligament. T1-weighted imaging showed the presence of fatty marrow as a high signal region within the fragment, indicating maturity of the fragment. These findings may help to determine preoperative planning for resection of massive fragments around the ligament. Pellegrini-Stieda disease cannot be considered rare, since it is often encountered in daily MRI examinations.     

磁性标记的小胶质细胞在大鼠脑内的MR示踪

目的 探讨超顺磁性氧化铁颗粒(SPIO)标记的小胶质细胞在正常大鼠及阿尔茨海默病(AD)大鼠体内移植后,MR活体示踪的可行性.方法 以日本血液凝集病毒包膜(HVJ-E)为标记载体,将SPIO标记的小胶质细胞经颈内动脉注入正常大鼠(5只)及AD大鼠动物模型(5只)体内,3 d后应用7.0 T MR行T2*序列扫描,并与脑组织切片组织化学染色结果对照.结果 在正常大鼠脑内,MRI可见数个点状的信号改变区,这些信号改变区散在地分布在脑内各处,脑组织切片显示铁颗粒标记细胞位置与信号改变部位一致.MRI能够检测到由数个标记细胞引起的信号强度的改变.在AD大鼠模型脑内,MRI可见β-淀粉样蛋白42(Aβ42)注射区信号强度明显下降,信号改变区面积较大.与之相比,生理盐水注射区信号改变的强度及面积均不如Aβ42注射区改变明显.Aβ42注射区的标记细胞数为(454±47)个/mm2,明显高于生理盐水注射区的标记细胞数(83±13)个/mm2(P<0.05).结论 MRI可作为一种非侵入性检测手段在活的动物体内追踪标记细胞,在AD细胞水平的治疗中具有一定临床应用前景.     

Osteoarthritis: MR imaging findings in different stages of disease and correlation with clinical findings

PURPOSE: To determine whether knee pain, stiffness, and limited function in patients with different stages of osteoarthritis correlate with the degree of disease assessed on magnetic resonance (MR) images and radiographs. MATERIALS AND METHODS: Radiographs in 50 patients with varying degrees of osteoarthritis of the knee were assessed by using the the Western Ontario and McMaster University (WOMAC) osteoarthritis index and the Kellgren-Lawrence (KL) scale. MR images were obtained and analyzed by two readers for cartilage lesions, bone marrow edema pattern, and ligamentous and meniscal lesions. RESULTS: Thirteen of 16 knees with a KL score of 4 showed full-thickness cartilage lesions and bone marrow edema pattern. Cruciate ligament tears were found in five of 12 knees with a KL score of 3 and in nine of 16 knees with a KL score of 4. While the KL score correlated significantly (P <.05) with the grade of cartilage lesions, and a substantially higher percentage of lesions with higher KL scores were found on MR images, the correlations between MR imaging findings and KL score versus clinical findings were not significant (P >.05). Significant differences between WOMAC scores were found only for the grades of cartilage lesions (P <.05). CONCLUSION: Cartilage lesions, bone marrow edema pattern, and meniscal and ligamentous lesions were frequently demonstrated on MR images in patients with advanced osteoarthritis. Clinical findings showed no significant correlations with KL score and extent of findings at MR imaging.     

Beurteilung des Ossifikationsstadiums der medialen Klavikulaepiphysenfuge

In forensic age estimation of the living in criminal proceedings the radiological examination of the ossification status of the medial clavicular epiphysis permits an assessment with regard to the completion of 21 years of age. In the present study the authors prospectively comparatively analyzed 8 prepared samples of the sternoclavicular region of individuals aged 15–17 years obtained during autopsy by means of projectional radiography, thin-slice computed tomography and magnetic resonance imaging. In 6 out of 15 examined sternoclavicular joints the ossification stage of the medial clavicular epiphysis was in agreement in each of the three imaging methods used. In the remaining cases the ossification stage was assessed as either one stage higher or lower in one of the imaging methods than in the other two techniques. In five cases compared to CT, and seven cases compared to MR, projectional radiography showed a higher ossification stage than CT and MR imaging. In two cases projectional radiography resulted in the determination of a lower stage than in CT and MR imaging. MR scans showed a less advanced ossification stage than CT-based images in two cases. In the practice of age estimation modality-specific reference studies based on projectional radiography and computed tomography are to be applied in order to guarantee an adequate assessment of the ossification stage of the medial clavicular epiphysis.