Radiographically negative avascular necrosis: detection with MR imaging

To correlate the morphologic appearance on magnetic resonance (MR) images of radiographically negative avascular necrosis (AVN) of the femoral head with that on computed tomographic (CT) and radionuclide scans, the radiographic and clinical records of 24 patients were reviewed retrospectively. In 18 patients the MR signal intensity features were monitored by means of serial imaging. All MR studies included T1-weighted (short repetition time [TR], short echo delay time [TE] ) imaging and T2-weighted imaging (long TR, long TE). Thirty-one hips were determined with MR to be involved by AVN; 27 were staged on the basis of signal intensity characteristics within the low-intensity rim. Core decompression was performed on 18 hips. Afterward, progression of disease occurred in only one hip. Fourteen of the 16 asymptomatic patients (88%) had early-stage focal lesions. CT scans were obtained in 15 patients and radionuclide scans in 21. Ten hips at radionuclide imaging and five at CT appeared normal when MR results were distinctly abnormal. MR can depict early radiographically negative AVN in asymptomatic individuals. At this early stage, the lesions in this series appear to be nonprogressive after treatment.     

MR imaging of femoral head avascular necrosis with STIR sequence

The uncomplicated bone necrosis is usually demarcated by reactive interface (RI). To analyze signal characteristics of RI, MR imaging of the hip was done using short TI IR (STIR) as well as short/long TR pulse sequences at 0.22 tesla. On STIR sequence the RI was observed as a high-signal line or ring with the shape identical to that of short TR image. The double line sign was not seen in early stage. The best explanation of high signal intensity of RI on STIR is that it has prolonged T1 and T2 secondary to high water content. It is concluded that STIR is an unique way to demonstrate RI in early osteonecrosis.     

Carpal avascular necrosis: MR imaging

The authors evaluated the use of magnetic resonance (MR) imaging in diagnosis of avascular necrosis (AVN) of carpal bones by examining 21 patients with wrist pain and two healthy volunteers. MR images were compared with conventional radiographs in every case and with bone scintigrams in 18 cases. MR imaging was slightly less sensitive than bone scintigraphy in depicting AVN, but in patients who were imaged with long repetition time (TR)/long echo time (TE) sequences in addition to short TR/short TE sequences, MR imaging was found to be more specific. While the authors believe that bone scintigraphy remains the screening test of choice for patients with wrist pain and normal plain radiographs, MR imaging promises to add significant diagnostic information in cases in which bone scans are abnormal.     

The role of MR imaging in avascular necrosis of the femoral head

Due to the pattern of its blood supply, the femoral head is particularly vulnerable to avascular necrosis (AVN). Nontraumatic AVN is a devastating disorder affecting young patients, and despite treatment it normally follows a progressive course toward a destructive osteoarthropathy. Magnetic resonance (MR) imaging is currently used in major classification systems solely for early detection of femoral head AVN when plain radiographs are normal. More recent data have shown that MR imaging may improve staging, investigate radiologically occult collapse, depict other causes of disability and pain, assess prognosis, and evaluate treatment. This article reviews the established and evolving role of MR imaging in patients at risk or with known femoral head AVN.     

MR imaging of iliopsoas bursitis and concurrent avascular necrosis of the femoral head

The magnetic resonance (MR) features of iliopsoas bursitis secondary to an inflammatory arthropathy of the hip are described in a patient with concurrent avascular necrosis of the femoral heads. The MR findings of avascular necrosis were demonstrated on one side where radiography, bone scan, and CT were negative.     

股骨头缺血坏死的分期与早期影像学诊断

目的 研究股骨头缺血坏死（ＡＮＦＨ）的分期、早期影像学表现及诊断价值。方法 ６２例双侧股骨头行Ｘ线、ＣＴ及低场ＭＲＩ检查,并对其影像学改变进行分期及等级稚和Ｈ检验和敏感性对照。结果 全部患者Ｘ线平片均诊断为早期ＡＮＦＨ,共９１个部位。其中Ⅰ期４６个,表现为骨疏松及骨硬化;Ⅱ期４５个,为骨硬化和囊状透亮区。ＣＴ发现５６例早期ＡＮＦＨ,共８６个部位。其中Ⅰ３４个,表现为星芒结构变形、骨疏松和骨硬化;Ⅱ     

MR imaging of avascular necrosis of the femoral head: value of small-field-of-view sagittal surface-coil images

We compared coronal, large-field-of-view, body-coil MR images with sagittal, small-field-of-view, surface-coil images of 30 hips for their sensitivities in establishing the diagnosis of avascular necrosis; spatially localizing the avascular necrosis; and detecting joint-space narrowing, femoral head collapse, articular cartilage fracture, and joint fluid. We also compared the two separate plane/coil combinations for detection of the "double-line" sign (high signal inside a band of low signal, believed to be characteristic for avascular necrosis) and intertrochanteric conversion of hematopoietic marrow to fatty marrow. Coronal, large-field-of-view, body-coil images provided an adequate screening examination for the presence of avascular necrosis (sensitivity of 94%) and were preferred in all cases for mediolateral localization of focal abnormality. They were also better for assessing joint fluid and detecting fatty conversion of marrow. Sagittal, small-field-of-view, surface-coil images were preferred for anteroposterior localization in all cases and for superoinferior localization of focal abnormality in 15 of 18 cases. They detected additional cases of joint-space narrowing, articular cartilage fracture, and the double-line sign missed by coronal, body-coil images. Sagittal, small-field-of-view, surface-coil images are a valuable adjunct to MR evaluation of femoral avascular necrosis because they provide additional information that may be useful for planning surgical therapy.     

股骨头缺血性坏死的MRI诊断价值

目的探讨股骨头缺血性坏死（ANFH）的影像学表现及各种影像检查方法对其诊断价值。方法回顾性分析了28例40髋ANFH病例,男23例,女5例,平均年龄36岁,病程3个月～8a。所有病例均行普通X线平片、CT及MRI检查。结果 X线平片、CT及MRI发现ANFH的阳性率分别是75.6%、84.5%及97.8%。结论 MRI诊断ANFH最敏感,其次为CT,最后为普通X线平片检查。     

早期成人股骨头缺血坏死的对比影像学诊断研究

目的：探讨早期成人股骨头缺血坏死（FHN）的MRI、CT、单光子发射计算机体层摄影（SPECT）和DR 4种影像学检查方法之间的对应关系及其敏感性,建立早期诊断的影像学检查途径。方法：分析和总结22例30髋随访具有典型影像学表现的早期（ARCOⅠ～Ⅱ期）成人FHN患者的髋关节影像学资料。全部病例均行同期MRI、CT、SPECT、DR检查。结果：MRI 30髋出现“线样征”,其中15髋为“单线征”,15髋为“双线征”;CT上对应部位显示为较模糊的高密度硬化线14髋,硬化线下伴行低密度带7髋;高密度硬化斑点5髋;SPECT上股骨头呈环形和弧形放射性浓聚带23髋,DR上模糊硬化条带13髋。结论：MRI上“线样征”、CT上承重区高密度硬化线和硬化线下低密度带,SPECT上股骨头环形和弧形放射性浓聚带以及DR片上模糊硬化带相互对应为诊断早期FHN的特异性征象。综合比较对早期成人FHN诊断的敏感性MRI最高。     

Fat intensity within the hypointense zone on MR imaging of avascular necrosis of the femoral head

In some patients with avascular necrosis of the femoral head (ANFH), an area of signal intensity similar to that of subcutaneous fat tissue is found within or proximal to the hypointense zone of spin echo MR images. We refer to these MR findings as the "fat intensity" sign. This fat intensity sign was positive in 62 (47%) of 133 MR examinations of femoral heads with radiographically proven ANFH; this sign was negative in all hips with other diseases including degenerative joint disease, transient osteoporosis, rapidly destructive coxoarthrosis, and rheumatoid arthritis.     

Chemical-shift MR imaging of the femoral head: an in vitro study of normal hips and hips with avascular necrosis

To study the conventional and chemical-shift MR images of fatty, hemopoietic, and ischemic bone marrow, four normal femurs from autopsies and six femoral heads from total hip replacement done for avascular necrosis (AVN) were imaged with a small-bore 1.4-T MR unit. T1- and T2-weighted spin-echo images, fat- and water-selective spin-echo images, and out-of-phase images were obtained. The specimens were then sectioned, radiographed, and studied histologically. The capital epiphysis and greater trochanter in normal femurs had the highest signal on T1-weighted, fat-selective, and out-of-phase images owing to their high fat content. Fat-selective and water-selective images accurately depicted regions of fat and water, whereas T1-weighted, T2-weighted, and out-of-phase images were misleading in some cases. On T2-weighted images, a double line consisting of a rim of low signal with a high-signal inner border was noted surrounding AVN lesions. Histologic correlation showed that the low-signal outer rim was due to sclerotic bone, while the high-intensity inner border was due to granulation tissue and/or chondroid metaplasia. Fractures within the six AVN lesions were best seen on T2-weighted images, but these could not be distinguished from granulation tissue. On T2-weighted images, the weight-bearing cartilage had lower signal in five of six femoral heads with AVN. We conclude that the MR appearance of AVN reflects its complex histopathology. Direct spin-echo chemical-shift imaging can help correlate MR images with histology by providing information not available from conventional or out-of-phase images.     

Magnetic resonance imaging of avascular necrosis of the femoral head

This study investigates the role of magnetic resonance imaging (MR) in identifying avascular necrosis (AVN) of the femoral head and in monitoring its therapy. The detection of AVN, particularly in its early stages, is imperative to give therapeutic intervention the best opportunity for successful management. The results of magnetic resonance imaging are compared with those of the standard diagnostic modalities in evaluation of patients with the lesion. Examinations were performed at 0.12 T with a repetition time (TR) of 143 ms and times to echo (TE's) of 10 or 20 ms. This study represents a retrospective review of 90 hips which were examined in 45 consecutive patients. Of these, 52 hips were biopsied as part of treatment. MR was shown to be sensitive in the detection of AVN. Comparison of MR with radionuclide imaging showed comparable sensitivity and specificity. MR was also noted to be sensitive in the detection of early AVN. Preliminary results suggest that MR can monitor treatment of the affected hip, and may even be able to predict patient response to therapy. Although further work is necessary to determine the role of MR in the evaluation of the patient presenting with hip pain, MR is a sensitive method in detecting AVN and in monitoring its course in patients suspected of having the disease.     

股骨头缺血坏死早期的CT研究

目的探讨股骨头缺血坏死(ANFH)早期CT表现并指导临床治疗。方法回顾性分析具有典型X线和CT表现并经临床病理或随访证实的49例成人ANFH的CT片,分析其CT早期征象并指导临床治疗。结果在49例的58个股骨头中20个股骨头骨小梁呈放射状密度增高的“星状征”,骨小梁境界清楚、锐利,属Ⅰ期;31个股骨头表现为骨硬化,骨小梁结构消失、模糊不清,骨密度减低及囊性改变,属Ⅱ期;并有7个股骨头在Ⅱ期影像改变基础上出现软骨下骨折及轻微塌陷,属Ⅲ期,X线和CT诊断的敏感性比较,得出x2=8.01,P<0.01,结果显示CT优于X线且差异有显著意义。结论CT可以诊断早期ANFH并能很好指导临床治疗。     

股骨头缺血性坏死基因治疗及早期影像学监测的研究进展

基因治疗是指将外源性基因导入靶细胞,以纠正或补偿因基因缺陷或异常而引起的疾病,以达到治疗目的.基因治疗作为一种新技术,已用于肿瘤、心血管和神经系统等疾病的治疗,为诸多难治性疾病的治疗带来了曙光.股骨头缺血性坏死是临床难治性疾病,也是骨科常见病,传统的手术疗法和保守疗法都有众多弊端,疗效难以令人满意,而基因治疗作为一种新型疗法,在骨科缺血性疾病的治疗中也展现了光明前景,大量动物实验已经证实了其可行性.该文着重介绍股骨头缺血性坏死基因治疗及早期监测方面的一些研究进展.     

Diagnostic performance of MR imaging in the assessment of subchondral fractures in avascular necrosis of the femoral head

Objective  A prospective study was conducted to determine the accuracy of routine magnetic resonance (MR) imaging in correctly identifying subchondral fracture in avascular necrosis of the femoral head without apparent focal collapse on standard radiographs. Materials and methods  Spiral computed tomography (CT) with coronal and sagittal reformations and routine MR imaging with spin-echo T1WI and fat-suppressed spin-echo T2WI coronal, axial, and sagittal images were performed in 28 hips of 25 patients (M/F = 20:5; age 16–76 years) suffering from early-stage avascular necrosis of the femoral head on standard radiographs. The MR images were reviewed by a musculoskeletal radiologist and a general radiologist in blinded fashion. Using CT as the standard of reference, the accuracy of MR imaging in diagnosing subchondral fractures in avascular necrosis was evaluated. Results  When the diagnoses of the two readers were compared with each other, only 16 of the 28 diagnoses (57.5%) agreed. Seventeen of the 28 MR imaging readings (60.7%) made by the musculoskeletal radiologist and 15 of the 28 (53.5%) made by the general radiologist agreed with those of the CT standard. False-positive diagnosis (that is, diagnosis of fracture when no fracture could be seen on CT) was more common than false-negative diagnosis. Conclusions  The accuracy of routine MR imaging in the evaluation of subchondral fracture is not satisfactory. False-positive diagnosis is not uncommon. Interpretation of routine MR imaging readout should be guarded.     

股骨头缺血性坏死的分期与早期MRI诊断

目的 研究股骨头缺血性坏死(ANFH)的分期，早期影像学表现及诊断价值。方法 回顾性分析40例的60个股骨头经临床证实为早期缺血性坏死的x线，CT及MRI影像学改变，并进行对比研究。结果 在40例60个股骨头缺血性坏死中，双侧22例，单侧16例，依据FICAT分期，I期42例，Ⅱ期18例，X片检查均为阴性，CT检查部分阳性。结论 在临床上凡是有髋部疼痛，功能障碍，长期饮酒及大量长期应用糖皮质激素者，都应进行MRI检查，力求早期诊断。