The sacrum: pathologic spectrum, multimodality imaging, and subspecialty approach.

The sacrum is a structure that is imaged by both general and subspecialty radiologists. A wide variety of disease processes can involve the sacrum either focally or as part of a systemic process. Plain radiographs, although limited in evaluation of the sacrum, should be carefully examined when abnormalities of the sacrum are suspected. Cross-sectional imaging, particularly computed tomography and magnetic resonance (MR) imaging, plays a crucial role in identification, localization, and characterization of sacral lesions. Congenital lesions of the sacrum, including sacral agenesis and meningocele, are optimally imaged with MR. The most common sacral neoplasm is metastatic disease. Primary neoplasms of the sacrum, which include giant cell tumor, chordoma, and teratoma, are infrequent. Infection of the sacrum or sacroiliac joint is most often due to contiguous spread from a suppurative focus. A wide variety of arthritic disorders such as ankylosing spondylitis and osteoarthritis can involve the sacroiliac joints as part of a localized or systemic process. Sacral fractures related to acute trauma or repetitive stress are difficult to diagnose and treat. Knowledge of these abnormalities and familiarity with the imaging of these processes will allow radiologists of all subspecialties to contribute to the diagnosis and management of sacral disorders.     

Evaluation of hemangioma by positron emission tomography: role in a multimodality approach

PURPOSE: The relative utility of various preoperative diagnostic imaging modalities for the evaluation of hemangioma of the extremities, including positron emission tomography (PET) (using 18F-fluoro-2-deoxy-D-glucose [FDG] and fluorine-18 alpha-methyltyrosine [FMT]), computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA), was investigated. METHODS: Imaging findings in 16 patients with 16 histopathologically documented hemangiomas of the extremities were retrospectively reviewed. Preoperative imaging included: FDG-PET (n = 16), FMT-PET (n = 12), MRI (n =16), CT (n =11), and DSA (n =14). RESULTS: All 16 lesions examined by PET with FDG and/or FMT showed accumulation. The standardized uptake values (SUVs) for FDG-PET for the 16 examined tumors ranged from 0.7 to 1.67; for FMT-PET, they ranged from 0.14 to 1.00. The SUVs with both tracers indicated the benign nature of the tumor. Computed tomography demonstrated variable attenuation and phleboliths in two patients. The MRI signal characteristics were relatively consistent: heterogeneous signals were slightly higher than those of skeletal muscle on T1-weighted images and brighter than those of subcutaneous fat on T2-weighted images. The pooling and cotton-wool staining depicted in DSA was found to be significantly correlated with FDG accumulation, suggesting that localized blood retention-induced ischemia may accelerate anaerobic glycolysis, which leads to high FDG uptake. CONCLUSION: Although plain radiography, CT, MRI, and angiography may provide anatomic extent and be pathognomonic, FDG-PET and FMT-PET may be the most reliable among the studied imaging modalities for differentiating benign hemangiomas from other soft tissue tumors, especially malignant neoplasms.     

Isolated greater tuberosity fractures of the proximal humerus: anatomy,injury patterns,multimodality imaging,and approach to management

The greater tuberosity is an important anatomic structure and its integrity is important for shoulder abduction and external rotation. Isolated fractures of the greater tuberosity are often subtle and may not be detected on initial radiographs. Clinically, these patients display symptoms which mimic a full thickness rotator cuff tear. It is important to differentiate these two entities, as their treatment is different (typically nonsurgical management for minimally displaced fractures versus rotator cuff repair for acute full thickness rotator cuff tears). When greater tuberosity fractures are significantly displaced and allowed to heal without anatomic reduction, they can lead to impingement. This article will review greater tuberosity anatomy and function, as well as the clinical presentation and multimodality imaging findings of greater tuberosity fractures. Imaging optimization, pitfalls, and clinical management of these fractures will also be discussed.     

Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures

BACKGROUND AND PURPOSE: Differentiating acute benign from neoplastic vertebral compression fractures can pose a problem in differential diagnosis on routine MR sequences, as signal changes can be quite similar. Our purpose was to assess the value of increasing the diffusion weighting of a diffusion-weighted steady-state free precession (SSFP) sequence for differentiating these two types of vertebral compression fractures. METHODS: Twenty-nine patients with 32 acute vertebral compression fractures caused by osteoporosis (n = 15) or malignancy (n = 17) were examined with a diffusion-weighted SSFP sequence, a T1-weighted spin-echo sequence, and a short-inversion-time inversion recovery sequence. The SSFP sequence was performed with increased diffusion weighting (delta = 0.6, 3.0, 6.0, and 9.0 ms). The signal intensities of the fractured vertebral bodies were rated on a five-point scale from markedly hypointense to markedly hyperintense relative to normal adjacent vertebral bodies. Quantitative analysis was performed by region-of-interest measurements and by calculating the bone marrow contrast ratio. Statistical analysis was performed with the Mann Whitney U test and Student's t test. RESULTS: At delta = 3 ms, the osteoporotic fractures yielded hypointense signal in seven cases, isointense signal in six, and hyperintense signal in two. The fractures showed a progressive signal loss with increased diffusion weighting, so that hypointensity was reached in all but one case. All metastatic fractures had hyperintense signal with delta = 3 and 6.0 ms. With delta = 9.0 ms, four fractures became isointense. CONCLUSION: Increasing diffusion weighting can reduce false-positive hyperintense osteoporotic fractures or make hypointensity more obvious in cases of osteoporotic fractures.     

Integrated multimodality and multi-disciplinary team approach to pre-sacral lesions

The purpose of this article is to describe the clinical and radiological features of presacral lesions. CT and MRI are the diagnostic modalities of choice and are complimentary in the assessment of presacral lesions.Imaging findings of presacral lesions on CT and MRI are described with the use of examples. Preoperative biopsy, surgical and non-surgical managements are outlined.While the general radiologist cannot be familiar with every rare presacral condition, characterisation of a presacral lesion based on anatomy, demographics and imaging features can guide us in making a sound differential.     

Low-risk stress fractures

Stress fractures can occur in almost any bone in the body, with the lower extremity weightbearing bones, especially the tibia, tarsals, and metatarsals, being affected most frequently. Although the cause of these fractures is multifactoral, repetitive physical forces without adequate rest are the primary culprits. Stress fractures may be broadly classified as low-risk or high-risk injuries. Low-risk stress fractures, the topic of this review article, can be diagnosed through a thorough history, physical examination, and radiographs. Nuclear scintigraphy is occasionally necessary for confirmation, especially for fractures of the spine and pelvis. When diagnosed early and treated with restriction of activity, low-risk stress fractures have a favorable prognosis.     

Navicular stress fractures

Since the stress fracture of the tarsal navicular was first described in 1970, awareness of the injury has increased, and navicular stress fractures have represented up to 35% of stress fractures in recent series. However, these injuries remain difficult to diagnose and treat because of their often vague clinical presentation and the poor correlation between radiographic and clinical findings.     

Rib stress fractures

The ribs are an uncommon site of stress fracture. Typical locations are the first rib anterolaterally, the fourth through ninth ribs laterally and posterolaterally, and the posteromedial upper ribs. Muscular forces are predominantly responsible for these fractures. This article reviews the mechanisms of injury in various activities and illustrates the scintigraphic appearance of rib stress fractures.     

Sacral stress fractures

Sacral stress fractures are a relatively common occurrence and can be a debilitating source of low back pain. They generally occur in two distinctly different patient populations, and are of two different etiologies. Sacral insufficiency-type fractures are seen in elderly osteoporotic persons, and fatigue fractures are seen young active individuals. Although the clinical presentation of these fractures is similar, medical rehabilitation and interventional spine management strategies differ according to etiology. Although conservative management strategies have resulted in good outcomes, other treatment options have recently developed. This article provides an overview of the clinical presentation, pathology, and treatment options for sacral stress fractures and discusses some of the recent literature surrounding this interesting topic.     

Tarsal navicular stress fractures: radiographic evaluation

Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.     

Treatment of stress fractures: the fundamentals

This article is an introduction to the fundamentals of stress fracture management. Extrinsic and intrinsic factors, that may play a role in the development of stress fractures, are discussed and incorporated as possible treatment options. Different treatment modalities including ultrasound and electromagnetic fields are addressed, with an emphasis on literature support.     

胸腰段脊柱爆裂骨折前路与后路手术疗效对比观察

目的 对胸腰椎爆裂骨折行前路手术和后路手术的患者进行回顾性研究,客观评价不同手术入路治疗后的影像学结果,为胸腰椎爆裂骨折的外科治疗提供可靠的参考.方法 筛选2003年1月-2005年12月收治的41例胸腰椎爆裂骨折患者作为研究对象,随访24～48个月,平均38个月.按照手术人路分为前路手术和后路手术两组.根据随访X线侧位片测量Cobb角作为效果评价标准,并进行统计学分析.结果 前路手术组共19例,人院时平均Cobb角为27.3°,术后为3.1°,随访结束时为4.6°;后路手术组共22例,入院时平均Cobb角为26.1°,术后为3.0°,随访结束时为12.5°.两组患者术前和术后即刻Cobb角差异无统计学意义(P>0.05),但随访结束时两者差异有统计学意义(P<0.01).结论 前路手术对于改善和维持胸腰椎爆裂骨折后凸角度优于后路手术.     

Bilateral primary xanthoma of the humeri with pathologic fractures: A case report

Xanthomas are rare bone tumors that occur more often in the appendicular skeleton and typically appear radiographically benign,with a narrow zone of transition and a sclerotic rim.We report the case of a 57-year-old woman with hyperlipidemia presenting with bilateral shoulder pain after minor trauma.Radiographic and histopathologic investigation demonstrated intraosseous xanthoma with atypical features,including multifocality,a wide zone of transition and pathologic fractures-characteristics more commonly associated with aggressive lesions such as multiple myeloma or metastasis.The diagnosis,imaging,and histological appearance of xanthoma of bone are reviewed.     

Epidemiology of stress fractures

Stress fractures are a frequent cause of injury in competitive and recreational athletes. Although a number of epidemiologic studies have been conducted, the populations studied and data collection methods have varied. This article presents an overview of injury epidemiology and reviews the current body of literature regarding the occurrence of stress fractures in athletes. Given the heterogeneity of the populations studied and the variations in data collection, few broad conclusions can be drawn. There is a pressing need for large prospective studies to better establish the risks of stress fracture by sport, age, and gender.     

Femoral neck stress fractures

Femoral neck stress fractures are unusual but not rare athletic injuries. In one large series they accounted for 5% of all stress fractures. Early recognition of the signs and symptoms of this injury is important, as objective findings are often delayed. The potential problems from this fracture are serious. The aetiology includes repeated force above a certain load without internal bone response time. Loss of shock absorption due to muscle fatigue and limitation of ankle motion by boots or splints may also play a role. The diagnosis is based on the finding of groin pain and radiographic testing, which often requires plain films and bone scintigraphy. Regular radiographic findings present in stages progressing from a normal film through sclerosis to a disruption of the cortex and displacement. Bone scintigraphy may be positive 2 or more weeks before plain film changes are present. Classification schemes follow the radiographic changes. A classification system and treatment plan may be based on 3 categories of these fractures--compression side, tension side and displaced femoral neck fracture. Treatment ranges from rest with early symptoms to surgical stabilisation for any widening of cortical cracks and/or displaced fractures. Prompt diagnosis and carefully supervised treatment is the key to preventing displacement. Prolonged disability secondary to pain, nonunion or avascular necrosis is associated with displacement of the femoral neck stress fracture.     

Implementation of a multimodality program

Economic changes in the health care system have presented a unique opportunity for radiographers and other imaging personnel. Hospital administrators are becoming aware of the advantages of employing multiskilled technologists. The single-skilled technologist must recognize the benefits of additional education and overcome the negative perceptions of the profession. A well-conceived educational program developed and managed by a continuing education department will provide not only the required didactic and clinical courses to ensure competency, but also recognized credentialing for each modality.     

Femoral neck stress fractures

Fifty-four femoral neck stress fractures were studied prospectively to evaluate treatment methods. Fifty-four fractures in 49 patients were identified in a 4 year prospective study that included 1,049 stress fractures of all types. From our evaluation of treatment methods, a modification of existing classification systems was developed based on radiographic findings and treatment. Differences from earlier studies were noted in racial diversity, in nonprogression of tension-side fractures, and in return to function.