Trauma to the foot

Minor trauma to the foot may cause stress fracture, avulsion fracture or ligamentous and tendon injury. Plain radiographs are frequently normal. Radionuclide bone scan is a sensitive detector of early bone injury. A stress fracture may develop focal uptake or diffuse uptake throughout the bone involved. MR imaging is the most sensitive means of evaluating injury to the soft tissues. Acute edema, partial tear, complete tear, and chronic tendinitis have distinct features on T1- and T2-weighted images. Major trauma occurs most commonly as a result of falls from heights and from motor-vehicle accidents. Plain films are useful in the initial evaluation of the extent of trauma. CT is particularly useful in evaluating calcaneal fractures that involve the subtalar joint. Both MR imaging and CT scans are useful in detecting injured or entrapped tendons associated with fracture-dislocations.     

Imaging of lower extremity stress fracture injuries

Stress reactions and stress fractures in the lower extremities occur frequently in military and athletic populations. As the clinical symptoms of stress fracture may mimic other less severe musculoskeletal injuries, the diagnosis of stress fracture can often be delayed. The following article reviews the characteristics, advantages and disadvantages of the various imaging tools available to detect stress fracture of the lower limbs in order to clarify their utility when diagnosing this condition. Plain radiography, the primary imaging tool for diagnosing suspected stress injuries, may not detect stress fracture injury until fracture healing is well underway. In some cases of suspected stress fracture, this delay in diagnosis can lead to catastrophic fracture and surgical intervention. Bone scintigraphy has long been recommended for the diagnosis of stress fracture, claiming that skeletal scintigraphy is 100% sensitive for the detection of stress fracture. However, there is a potential for a false negative examination and findings might be nonspecific as tumours or infections may mimic stress injury. In addition, bone scintigraphy involves ionizing radiation and it should not be used whenever there is an alternative. Computed tomography (CT) provides exquisitely fine osseous detail, but should be reserved only for specific indications because it also involves ionizing radiation. Magnetic resonance (MR) imaging, which is noninvasive, has no ionizing radiation, is more rapidly performed than bone scintigraphy, and should be the method of choice for stress fracture diagnosis whenever it is available. However, using MR imaging demands an experienced diagnostician in order to decrease reported false-positive injuries. The ultrasonography technique, which is being used increasingly in the evaluation of the musculoskeletal system has recently been shown to have some potential in the diagnosis of stress fracture; however, currently the imaging modalities are insufficient. The peripheral quantitative CT (pQCT) device, which has been developed to specifically assess skeletal status of the extremities, provides data on bone geometry, strength and density. However, the pQCT needs further evaluation prior to being considered for use in diagnosis stress changes in bone. This article reviews the utility of each of the imaging modalities currently available to detect stress fracture injuries of the lower extremities, as well as other utilization factors, which include exposure to ionizing radiation, the ability to detect early- and late-stage reactions in the bone and surrounding soft tissues, and the ability to differentiate between different types of bone lesions.     

Multidetector CT of the spine in multiple myeloma: comparison with MR imaging and radiography

OBJECTIVE: The purpose of this study was to compare multidetector CT (MDCT) of the thoracic and lumbar segments of the spine with MR imaging and conventional radiography for bone lesion detection and for evaluating the risk of vertebral fracture in multiple myeloma. SUBJECTS AND METHODS: Eighteen patients with multiple myeloma stage III (according to the criteria of Durie and Salmon) underwent MDCT, conventional radiography, and MR imaging of the lumbar and thoracic spine. MDCT was performed using a standard protocol with no contrast material. Source images were reconstructed using an effective slice thickness of 3 mm with an overlapping reconstruction increment (0.8 mm). Secondary coronal and sagittal multiplanar reformations were exclusively used for establishing the diagnosis. Findings were compared with those of MR imaging and conventional radiography. RESULTS: In all patients, coronal and sagittal multiplanar reformations depicted the extent of osseous destruction and provided detailed information about osseous infiltration and potential bone instability. Compared with conventional radiography, an additional 24 affected vertebrae, 15 additional vertebral fractures, and six vertebrae at further risk of fracture were detected on MDCT. Compared with MR imaging, three additional endangered vertebrae were detected on MDCT. MR imaging alone would have lead to an understaging of five (27.8%) of 18 patients. Using combined radiography and MR imaging, disease in three (16.7%) of 18 patients would have been understaged. CONCLUSION: MDCT seems to be preferable to conventional radiography in evaluating bone destruction in multiple myeloma. In combination with MR imaging, detailed information for staging these tumors is obtained. For the initial staging in patients with multiple myeloma, MDCT in combination with MR imaging seems to be the method of choice.     

Lumbar spondylolysis: a review

Spondylolysis is an osseous defect of the pars interarticularis, thought to be a developmental or acquired stress fracture secondary to chronic low-grade trauma. It is encountered most frequently in adolescents, most commonly involving the lower lumbar spine, with particularly high prevalence among athletes involved in certain sports or activities. Spondylolysis can be asymptomatic or can be a cause of spine instability, back pain, and radiculopathy. The biomechanics and pathophysiology of spondylolysis are complex and debated. Imaging is utilized to detect spondylolysis, distinguish acute and active lesions from chronic inactive non-union, help establish prognosis, guide treatment, and to assess bony healing. Radiography with satisfactory technical quality can often demonstrate a pars defect. Multislice CT with multiplanar reformats is the most accurate modality for detecting the bony defect and may also be used for assessment of osseous healing; however, as with radiographs, it is not sensitive for detection of the early edematous stress response without a fracture line and exposes the patient to ionizing radiation. Magnetic resonance (MR) imaging should be used as the primary investigation for adolescents with back pain and suspected stress reactions of the lumbar pars interarticularis. Several imaging pitfalls render MR imaging less sensitive than CT for directly visualizing the pars defects (regional degenerative changes and sclerosis). Nevertheless, the presence of bone marrow edema on fluid-sensitive images is an important early finding that may suggest stress response without a visible fracture line. Moreover, MR is the imaging modality of choice for identifying associated nerve root compression. Single-photon emission computed tomography (SPECT) use is limited by a high rate of false-positive and false-negative results and by considerable ionizing radiation exposure. In this article, we provide a review of the current concepts regarding spondylolysis, its epidemiology, pathogenesis, and general treatment guidelines, as well as a detailed review and discussion of the imaging principles for the diagnosis and follow-up of this condition.     

Magnetic resonance appearance of sacral insufficiency fractures

Insufficiency fractures of the sacrum are a commonly recognized form of stress fracture typically occurring in elderly patients. As such patients usually present with low back pain, MR imaging is often performed initially as a means of evaluation. We present 5 patients with sacral insufficiency fractures imaged with MR. Metastatic disease was a leading clinical suspicion as all patients were elderly and three had known primary neoplasms. T₁-weighted sequences demonstrated bands of decreased signal intensity, usually paralleling the sacral aspect of the sacroiliac joints and occasionally occurring as a horizontal band across the sacral body. Four of five patients underwent further evaluation with computed tomography (CT) or nuclear bone scanning, which confirmed the diagnosis of sacral insufficiency fracture. We conclude that MRI is sensitive but not specific in detecting sacral insufficiency fractures. As MR imaging is rapidly becoming the method of choice for evaluating back pain, it is important to consider this diagnosis in elderly persons.     

Acute elbow trauma in children: spectrum of injury revealed by MR imaging not apparent on radiographs

OBJECTIVE. The objective of this study is to evaluate the frequency and significance of unrecognized bone or soft-tissue injury in pediatric patients with elbow trauma assessed with radiographs alone. SUBJECTS AND METHODS. Fifty children (32 boys and 18 girls; mean age, 7.3 years; age range, 2-12 years) with acute elbow trauma were examined with radiography and MR imaging. Radiographs were categorized into those showing normal findings, an effusion, an equivocal fracture, or an unequivocal fracture. MR examinations were assessed for an effusion, fracture, transphyseal fracture extension, physeal injury, bone bruising, and ligament or muscle injury. Average clinical follow-up was 1.6 years (range, 6-28 months) after injury. RESULTS. Radiographs showed normal findings in seven children (14%), an effusion only in 17 children (34%), and an unequivocal or equivocal fracture in 26 children (52%). MR imaging showed an effusion in 48 children (96%); unequivocal fracture in 37 children (74%), including transphyseal fracture in seven children (14%) and other physeal injury in three children (6%); bone bruising in 45 children (90%); ligament injury in six children (14%); and muscle injury in 19 children (38%). A less severe spectrum of injury occurred in children with normal findings on radiographs than in those with an effusion or fracture seen on radiography. Follow-up radiographs did not help in the detection of radiographically occult fractures. MR findings had no appreciable effect on patient treatment and no value in predicting duration of convalescence or clinical outcome at an average of 1.6 years after injury. CONCLUSION. In children with elbow trauma, MR imaging reveals a broad spectrum of bone and soft-tissue injury beyond that recognizable radiographically. However, the additional information afforded by MR imaging has little bearing on treatment or clinical outcome.     

The role of MR imaging in scaphoid disorders

The scaphoid bone of the wrist is one of the most commonly fractured bones in the body. Due to its importance in the biomechanics and functionality of the wrist, it is important to depict and characterize the type of injury. Plain radiographs and scintigraphy may fail to disclose the type and severity of the injury. In patients with normal initial plain radiographs, MR imaging can discriminate occult fractures from bone bruises and may also demonstrate ligamentous disruption. MR imaging can also discriminate the proximal pole viability versus avascular necrosis secondary to previous fracture, which is important for treatment planning. Treatment of non-united fractures with vascularized grafts can be evaluated with contrast-enhanced MR imaging. Idiopathic osteonecrosis or Preiser’s disease was originally described after trauma. The non-traumatic disorders of the scaphoid include post-traumatic osteoarthritis, inflammatory bone marrow edema in patients with rheumatoid arthritis, and osteomyelitis. MR imaging is helpful in all the above disorders to demonstrate early bone marrow edema, cartilage degeneration and associated subchondral marrow changes. The most commonly found tumors in the scaphoid are usually benign and include enchondroma, osteoblastoma and osteoid osteoma. MR imaging is not mandatory for the initial diagnosis, which should be based on plain X-ray findings.     

Soft-tissue and osseous impingement syndromes of the ankle: role of imaging in diagnosis and management.

Soft-tissue and osseous impingement syndromes of the ankle can be an important cause of chronic pain, particularly in the professional athlete. The main impingement syndromes are anterolateral, anterior, anteromedial, and posterior impingement. These conditions arise from initial ankle injuries, which, in the subacute or chronic situation, lead to development of abnormal osseous and soft-tissue thickening within the ankle joint. The relative contributions of the osseous and soft-tissue abnormalities are variable, but whatever component is dominant there is physical impingement and painful limitation of ankle movement. Conventional radiography is usually the first imaging technique performed and allows assessment of any potential bone abnormality, particularly in anterior and posterior impingement. Computed tomography (CT) and isotope bone scanning have been largely superseded by magnetic resonance (MR) imaging, but the accuracy and role of MR imaging in assessment of possible ankle impingement have not been clearly established. MR imaging can demonstrate osseous and soft-tissue edema in anterior or posterior impingement. Studies of conventional MR imaging have produced conflicting sensitivities and specificities in assessment of anterolateral impingement. CT and MR arthrographic techniques allow the most accurate assessment of the capsular recesses, albeit with important limitations in diagnosis of clinical impingement syndromes.     

长骨应力性骨折的MR诊断及鉴别诊断

目的 分析长骨应力性骨折的MR表现,提高对长骨应力骨折的MR诊断和鉴别诊断. 资料与方法 回顾性分析经临床病理或追踪复查证实的12例长骨应力骨折患者的MR图像. 结果 12例中股骨颈1例,股骨下段4例,胫骨上段6例,腓骨下段1例.MR均可见骨髓腔内大片长T1、长T2信号骨髓水肿,范围远较平片广泛,DWI像骨髓水肿区较T2WI更明显;并可见骨膜水肿,表现为骨皮质周围环形长T1、长T2信号;9例可见骨折线,矢状位和轴位PDWI和T2WI表现为局部骨皮质中断呈稍长T2信号,冠状位T2WI和PDWI髓腔内与骨皮质相连的横行低信号带;软组织肿胀呈弥漫性长T1、长T2信号. 结论 MRI能够更敏感地发现早期应力性骨折,为诊断和判断骨折愈合情况提供更多信息.     

A longitudinal insufficiency fracture of the tibia in association with a healed chronic osteomyelitis

Longitudinal stress fracture of the tibia often present with an atypical clinical presentation which can be mistaken for osseous tumor or osteomyelitis. We present a case of longitudinal stress fracture of the tibia which occurred in a patient with healed chronic osteomyelitis of the tibia. Magnetic resonance imaging failed to make the correct diagnosis. Accurate diagnosis was only obtained by helical CT which showed the longitudinal fracture line. Magnetic resonance imaging showed only non-specific signs of bone marrow edema, suggesting recurrence of osteomyelitis. Magnetic resonance imaging can be misleading in the absence of direct visualization of the fracture line. Received: 30 September 1999; Revised: 26 April 2000; Accepted: 2 May 2000     

Basic principles of nuclear medicine techniques for detection and evaluation of trauma and sports medicine injuries

Nuclear medicine skeletal imaging is a very sensitive technique for evaluating bone and muscle abnormalities because it can detect minor changes in metabolism and blood flow. The specificity of bone imaging, however, depends on the ability of the nuclear medicine physician to make a differential diagnosis. To aid in making a specific diagnosis, this article describes the various patterns of abnormality in stress fractures, tibial stress syndrome (shin splints), compartment syndrome, enthesopathy, and traumatic fractures. The characteristic scintigraphic appearance of joint injuries, muscle injuries (rhabdomyolysis), and radionuclide arthrography is discussed and the way the scan patterns change with time in these various disorders is described. A brief summary of the basic anatomy and physiology of bone and muscle in normal and injured tissue is presented and the basic mechanisms which cause the various abnormal scan patterns is postulated. In addition, a staging system for stress fractures is presented to help direct the referring physician toward the proper management of the injured patient. In most cases, nuclear medicine skeletal imaging can be used to differentiate between acute muscle injury, tibial stress syndrome, skeletal injury (periosteal reaction, stress fracture, and traumatic fracture) or an abnormality that is entirely associated with the joint or connective tissue. This differential diagnosis is easier if the nuclear medicine procedure is performed within a few days after the onset of injury.     

Stress fractures in women

Stress fractures are common overuse injuries, reported more frequently in female athletes than in male athletes. The clinician should have a high index of suspicion for this injury whether an athlete presents with complaints of acute pain and disability or insidious onset of pain that is aggravated by activity and relieved by rest. Radiographs, bone scans, CT scans, and MR imaging may all be useful in confirming the diagnosis. Conservative treatment is usually successful, although one must be especially vigilant in treating a stress fracture prone to complications. Identifying risk factors for susceptibility to stress fracture development may help to avoid recurrence of the injury. More research is needed to determine cause versus association of these various risk factors in relationship to stress injury to bone.     

应力性骨折的早期低场强MRI与DR诊断分析

目的：通过对应力性骨折的DR与低场强MRI表现的对比,及分析应力性骨折的解剖学和生物力学特征,提高对应力性骨折早期的低场强MRI诊断的准确性。方法：回顾性分析经临床随访或病理证实29例不同部位应力骨折患者的MRI及DR图像。结果：29例中,胫骨12例（中上段为主）,股骨下段3例,胫骨上段和股骨下段同时发病3例,髂骨、耻骨、坐骨及股骨头颈部、股骨上段各2例,跖骨2例,腓骨中上段2例。MRI均可见骨髓腔内斑片状不均匀长T1、长T2水肿信号,范围远较DR片广泛,边界模糊;7例骨皮质周围见环形或半环形长T1、长T2骨膜水肿信号;6例可见隐匿骨折线;冠、矢状位表现为髓腔内斜形或横形线条状长T1、短T2信号影,其中骨皮质中断4例;10例可见骨皮质增厚,呈长T1、短T2信号;软组织肿胀呈弥漫性长T1、长T2信号。结论：MRI能够更敏感地发现早期应力性骨折,为诊断和判断骨折愈合情况提供更多信息。     

无骨折脱位型急性颈髓损伤的MR影像表现

目的:分析无骨折脱位型急性颈髓损伤的MR影像表现及其临床意义。材料与方法:无骨折脱位型急性颈髓损伤患者32例(其中男18例,女14例;年龄15～80岁,平均53岁)均在损伤后24小时内以西门子1.0T MR超导机行常规T_2和T_2加权磁共振成像。结果:无骨折脱位型急性颈髓损伤的MR影像主要表现为受损节段呈长T_1低信号或等信号及长T_2高信号,受损局部无明显受压或仅有轻微受压。结论:无骨折脱位型急性颈髓损伤的MR影像特征对早期确诊、指导治疗以及判断预后具有重要意义。     

Cross-sectional imaging of primary osseous hemangiopericytoma

The aim of this study was to assess cross-sectional imaging features and the value of CT and MRI in primary hemangiopericytoma of bone. In five patients with histologically proven primary osseous hemangiopericytoma CT and MR scans were evaluated retrospectively. Both CT and MRI were available in four patients each. In three patients both imaging techniques were available. On CT primary hemangiopericytoma of bone presents as an expansive lytic lesion with bone destruction and inhomogeneous contrast enhancement. Magnetic resonance imaging depicts osseous hemangiopericytoma as hyperintense lesion on T2-weighted images with intermediate signal intensity on T1-weighted images. Curvilinear tubular structures of signal void in the tumor matrix on T1-weighted images and corresponding hyperintense structures on T2-weighted and on fat-suppressed short tau inversion recovery images were present in three patients. Although cross-sectional imaging findings are non-specific, they add to the diagnosis and provide valuable information about the extent of bone destruction and local tumor spread in patients with primary osseous hemangiopericytoma. While CT demonstrates the extent of bone destruction best, MRI better visualizes medullary and soft tissue extension of the tumor. Curvilinear signal abnormalities support the diagnosis of hemangiopericytoma of bone. This imaging pattern is best visualized on fat-suppressed or contrast enhanced T1-weighted MR images.     

Imaging of stress fractures

The imaging evaluation of a patient who has a clinically suspected stress reaction or fracture should begin with high-resolution radiographs of the area in question. In inconclusive or indeterminate cases, additional imaging should be obtained. CT provides exquisitely fine osseous detail, in multiple planes, often demonstrating the endosteal remodeling or fracture line that is not apparent on conventional radiographs. The sensitivity of nuclear scintigraphy depicts areas of even subtle osseous turnover and stress remodeling. Ultrasonography, used increasingly in the evaluation of the musculoskeletal system, can provide a limited evaluation of the superficial osseous structures, providing an imaging alternative, especially in patients who are MRI-incompatible. MRI, however, provides the most comprehensive evaluation of stress injuries, revealing both functional and morphologic information about the bone.     

Bone stress injuries

Bone stress injuries are due to cyclical overuse of the bone. They are relatively common in athletes and military recruits but also among otherwise healthy people who have recently started new or intensive physical activity. Diagnosis of bone stress injuries is based on the patient's history of increased physical activity and on imaging findings. The general symptom of a bone stress injury is stress-related pain. Bone stress injuries are difficult to diagnose based only on a clinical examination because the clinical symptoms may vary depending on the phase of the pathophysiological spectrum in the bone stress injury. Imaging studies are needed to ensure an early and exact diagnosis, because if the diagnosis is not delayed most bone stress injuries heal well without complications.     

隐性骨与软骨损伤的MRI诊断

目的探讨隐性骨与软骨损伤的MRI特点,分析骨挫伤、隐性骨折和关节软骨损伤间的关系。方法回顾性分析了101例隐性骨与软骨损伤,其中骨挫伤70例,隐性骨折13例,关节软骨损伤18例。观察病变的MRI特点、分布,检出骨挫伤的序列敏感性。结果T1WI,STIR或PDWI(f/s)检出骨挫伤的敏感性为95.7%及100%。骨挫伤病变在关节主要分布于骨骼的边缘,脊椎主要分布于椎体上缘终板下。隐性骨折骨折线走行方向不定,平均宽度为1.8 mm,邻近区域的骨挫伤是其重要的间接征象。关节软骨损伤MRI表现为关节软骨变薄、断裂或缺损,软骨下骨挫伤出现率为100%。结论隐性骨折和关节软骨损伤均合并有骨挫伤,MRI是诊断隐性骨与软骨损伤的敏感方法。     

Forefoot pain involving the metatarsal region: differential diagnosis with MR imaging.

Many disorders produce discomfort in the metatarsal region of the forefoot. These disorders include traumatic lesions of the soft tissues and bones (eg, turf toe, plantar plate disruption, sesamoiditis, stress fracture, stress response), Freiberg infraction, infection, arthritis, tendon disorders (eg, tendinosis, tenosynovitis, tendon rupture), nonneoplastic soft-tissue masses (eg, ganglia, bursitis, granuloma, Morton neuroma), and, less frequently, soft-tissue and bone neoplasms. Prior to the advent of magnetic resonance (MR) imaging, many of these disorders were not diagnosed noninvasively, and radiologic involvement in the evaluation of affected patients was limited. However, MR imaging has proved useful in detecting the numerous soft-tissue and early bone and joint processes that occur in this portion of the foot but are not depicted or as well characterized with other imaging modalities. Frequently, MR imaging allows a specific diagnosis based on the location, signal intensity characteristics, and morphologic features of the abnormality. Consequently, MR imaging is increasingly being used to evaluate patients with forefoot complaints. Radiologists should be familiar with the differential diagnosis and MR imaging features of disorders that can produce discomfort in this region.