Titanium hip implants for improved magnetic resonance and computed tomography examinations.

The value of magnetic resonance imaging (MRI) for assessment of the hip has been demonstrated, particularly in cases of avascular necrosis. Magnetic resonance imaging can be used to provide anatomic evaluation of the femoral head, acetabulum, hip joint, joint fluid, and the surrounding structures. MR examinations of two patients with hip fractures fixed with stainless steel hip implants were compared with nine patients with hip fractures fixed with titanium hip implants, one of which showed avascular necrosis of the femoral head. The titanium implants resulted in less MRI artifacts, allowing for improved depiction of the femoral head and surrounding soft tissue. For this reason titanium fixation devices are recommended as a substitute for stainless steel in the hip joint region in a patient who may need future MR examination.     

Advances in imaging of rheumatoid arthritis

Several new imaging modalities have been found useful in clinical evaluation of patients with rheumatoid arthritis (RA). Magnetic resonance (MR) imaging has proven to be an excellent noninvasive method to evaluate the spine, shoulder, hip, and knees; its use for the evaluation of smaller joints is still being investigated. In patients with RA, MR imaging has been used to evaluate cervical spine instability, rotator cuff tear, osteonecrosis, and osteomyelitis. Patients with RA may have advanced osteoporosis, predisposing to insufficiency fractures. This includes fractures associated with increased activity after hip or knee arthroplasty. Newer methods for measuring the degree of osteoporosis include single photon absorptiometry, dual photon absorptiometry, quantitative computed tomography (CT), and dual-energy projection radiography. It has not yet been determined which of these methods will be most widely used in the future, but quantitative CT and dual-energy projection radiography currently show the most promise. Ultrasonography provides an excellent noninvasive method for the diagnosis of popliteal cysts, and color Doppler sonography can differentiate cyst and popliteal aneurysm. As compared to radiography or conventional CT, high-resolution CT provides an improved method to detect the early changes of RA in the lung parenchyma.     

Imaging the ankle and foot and using magnetic resonance imaging

Magnetic resonance (MR) imaging has improved the possibility of evaluating musculoskeletal structures thus gaining an important role in the diagnosis and treatment of foot and ankle pathologies. In this review, the normal and pathological images of the ankle and foot obtained using MR techniques are presented and discussed. The high soft-tissue contrast resolution and the multiplanar sections of MRI allow the imaging of contiguous tissues where small contrast differences exist, such as ligamentous and tendinous injuries or impingement syndromes. The spatial resolution with high sensitivity for bone signal changes offers an early detection of osseous abnormalities such as stress fractures or osteonecrosis. Here it is specified possibilities and limitations of MRI in the diabetic foot: this technique is superior to nuclear medicine and computed tomography (CT), however it is unable to distinguish between neuro arthropathy and infection.     

Multimodal imaging quantitation of the lesion size in osteonecrosis of the femoral head

Early diagnosis of osteonecrosis of the femoral head is important for initiating early treatment, which is associated with a more favorable outcome for patients. Confusion in evaluating the severity of the disease, and the clinical outcome after treatment partially is attributed to the use of various staging systems that are based on qualitative rather than quantitative criteria. At the authors' institution, 45 patients (77 hips) with osteonecrosis of the femoral head were evaluated using a multimodal imaging approach that included conventional radiography, bone scintigraphy, and magnetic resonance imaging. A computerized image analysis program that allowed quantification of the lesion size on radiographs and magnetic resonance images was used. Measurements of the extent of involvement on radiographs and selected serial magnetic resonance images were compared in 33 hips (42.9%) before collapse versus 44 hips (57.1%) after collapse. The size of the necrotic lesion varied significantly according to the specific stage of disease. Quantification of the lesion during the course of the disease provided a record of the progression of osteonecrosis, despite a spurious stability in staging. In general, conventional radiography closely approximated measurements of the lesion size obtained by magnetic resonance imaging. Bone scintigraphy and magnetic resonance imaging were well suited for detection of osteonecrosis at an early stage. Finally, precise quantification of the lesion size was an optimal preoperative means for evaluating the extent of involvement of the femoral head in the early and advanced stages of osteonecrosis.     

Late diagnosis of intraarticular osteoid osteoma treated as hip osteoarthritis--case report and review of the literature

A 34-year old men with left hip pain caused by intraarticular osteoid osteoma localized in the left femoral head is described. He was treated as a hip osteoarthritis for one year before the accurate diagnosis was established. Magnetic resonance imaging showed lesion indicating osteoid osteoma. Accurate diagnosis was established based on typical appearance of the osteoid osteoma on the computed tomography (CT). Osteoid osteoma rarely occures after 30 years of age and intraarticular locallisation is uncommon. This case report pinpoints the importance of careful analysis of monoarticular pain in order to avoid the possibile misdiagnosis of osteoid osteoma especially in young adult with an isolated osteoarthritis feature on the conventional radiography and normal laboratory findings. CT is specific and sensitive imaging modality for diagnosis of osteoid osteoma.     

Three-dimensional digital displays in congenital dislocation of the hip: preliminary experience

Four patients with congenital dislocation of the hip (CDH) were studied on a research basis with three-dimensional computed tomography (3-D CT) or, alternatively, with three-dimensional magnetic resonance imaging (3-D MR). 3-D CT and 3-D MR proved useful in demonstrating the extent of anterior and posterior acetabular coverage. 3-D CT was limited to patients greater than 6 months of age with ossified femoral heads. 3-D MR, in contrast to 3-D CT, demonstrated the cartilaginous femoral head in children less than 6 months of age, while avoiding gonadal irradiation. Both 3-D CT and 3-D MR appear promising in confirming the diagnosis and facilitating the choice of treatment modality in the child with complicated CDH.     

Diagnosis and imaging studies of traumatic hip dislocations in the adult

Traumatic dislocation of the hip represents a major injury that is associated with significant morbidity. In particular, the risk of osteonecrosis of the femoral head is greatly affected by the time it takes to reduce the hip. Therefore, thorough understanding of the clinical and radiologic features is essential if this injury is to be recognized and treated promptly. Most patients present in severe distress after a high-energy injury such as a motor vehicle accident. Associated injuries, particularly of the knee, are common and the leg usually is held in a specific posture characteristic of the direction of dislocation. Plain anteroposterior radiographs of the pelvis will clearly show the dislocation in most patients but lateral views or a computed tomography scan may be required to confirm the diagnosis and to show the direction if the signs are subtle. Associated acetabular wall fractures and femoral head fractures also may be identified by computed tomography scans. After reduction, plain radiographs alone are not adequate to assess reduction; computed tomography is more sensitive in detecting osteochondral fragments and may reliably detect residual subluxation of 2 mm in any part of the joint. Magnetic resonance imaging is useful in detecting changes of osteonecrosis but rarely is indicated in the early treatment of this condition.     

Post-traumatic peripheral facial nerve palsy: surgical and neuroradiological consideration in five cases of delayed onset

The facial nerve is frequently injured after head trauma with or without temporal bone fractures. Computed tomography (CT) is the best procedure for detecting the fracture line at the level of the facial nerve canal and for assessing any associated lesions within the temporal bone. Magnetic resonance (MR) is required if there is a facial nerve paralysis, unexplained by CT findings. We present five cases of delayed post-traumatic facial nerve palsy without evidence of temporal bone fractures on CT, thus studied on MR. MR was essential for diagnosing the nerve impairment. Neuroradiological findings, clinical presentation, and electrodiagnostic tests influenced the management of the patients.     

Impact of magnetic resonance on staging of renal carcinoma

Computerized tomography (CT), ultrasound, and angiography have been used for staging renal cell carcinoma. CT has proven to be the most reliable and sensitive of these techniques. Magnetic resonance (MR) has emerged recently as a viable alternative imaging modality. Five patients with renal cell carcinoma and suspected caval involvement were evaluated by CT, ultrasound, and MR. Caval extension and the differentiation of intra-versus retrocaval tumor was seen with greater clarity on MR scans; perinephric extension was seen equally well with both modalities. The primary tumor itself was better defined with CT. In patients with equivocal findings regarding the renal veins or inferior vena cava, MR is a valuable adjunct in preoperative evaluation. In patients at high risk for contrast administration, MR is the staging modality of choice.     

Funktionelle Bildgebung beim Harnblasenkarzinom

Computed tomography (CT) represents the current standard imaging modality in muscle invasive bladder cancer; however, local tumor and lymph node staging is often impaired. Magnetic resonance imaging (MRI) with diffusion-weighted sequences, determination of apparent diffusion coefficient (ADC) values or utilization of supraparamagnetic iron nanoparticles potentially exhibits advantages in the assessment of local tumor and lymph node involvement and therefore might play a role in the staging of bladder tumor in the future. Likewise, positron emission tomography (PET) with the currently used tracers ¹⁸F fluorodeoxyglucose (¹⁸F-FDG), ¹¹C-choline and ¹¹C-acetate is being investigated in bladder cancer patients, mostly in combination with diagnostic CT. Although promising results could be obtained for PET/CT investigations to some extent, the true value cannot be determined at present.     

Postoperative assessment of vascularity of the femoral head after surgical hip dislocation

Treatment for femoroacetabular impingement includes surgical hip dislocation and recontouring the femoral head-neck junction. However, a potential complication of this procedure is avascular necrosis. The purpose of this study was to assess radiographically the vascularity of the femoral head after surgical hip dislocation. Ten patients underwent surgical hip dislocation and recontouring of the femoral head-neck junction for femoroacetabular impingement. Postoperatively, all 10 patients underwent magnetic resonance imaging of the hip. Magnetic resonance imaging revealed no evidence of osteonecrosis in all patients. This study provides clear radiographic evidence that surgical hip dislocation may be performed without causing avascular necrosis of the femoral head.     

Magnetic resonance imaging evaluation of congenital dislocation of the hips

Magnetic resonance (MR) images were obtained preoperatively and postoperatively for 12 pediatric patients with congenital dislocation of the hip (CDH). The images were compared with arthrograms and computed tomography scans. The MR images were more accurate in defining soft-tissue anatomy, hip position, and obstructive factors to relocation. MR imaging is an efficient diagnostic tool in CDH.     

Nuclear medicine imaging in osteonecrosis of hip:Old and current concepts

Osteonecrosis(ON) is caused by inadequate blood supply leading to bone death, which results in the collapse of the architectural bony structure. Femoral head is the most common site involved in ON. Magnetic resonance imaging(MRI) is a commonly used imaging modality to detect early ON. When MRI is inconclusive, bone scan is helpful in detecting ON during early phase of the disease. As newer nuclear medicine equipment, like single photon emission computed tomography/computed tomography(CT) and positron emission tomography/CT, are emerging in medical science, we review the role of these imaging modalities in ON of femoral head.     

A pathological fracture of the femoral neck associated with osteonecrosis of the femoral head and a stress fracture of the contralateral femoral neck

A pathological fracture of the right femoral neck associated with osteonecrosis of the right femoral head and a stress fracture of the contralateral femoral neck occurred in a 47-year-old man. Osteonecrosis was noted in almost the entire femoral head, and the pathological fracture occurred at the subcapital area. Six months later, a stress fracture was detected in the contralateral femoral neck. The stress fracture of the left femoral neck might have been caused by the incremental repetitive mechanical loading in the left hip as a result of the pathological fracture in the right hip. Therefore, it might be necessary to conduct a careful examination, using either a magnetic resonance imaging scan or a bone scan, of patients with extensive osteonecrosis of the femoral head because of the risk of osteonecrosis in the contralateral femoral head as well stress fractures in the contralateral femoral neck.     

Magnetic resonance imaging and histopathology in the femoral head

To correlate the magnetic resonance (MR) images with the histopathological findings in the femoral head, the histopathology of 24 femoral heads, 15 with osteonecrosis, five with osteoarthritis and four with other hip disorders were subjected to preoperative MR imaging which demonstrated low intensity areas due to long T1 relaxation time in the femoral head. The MR signal was low where fibrovascular tissue, disintegrated fibrovascular tissue, amorphous necrotic material, bone, or cartilagenous tissue occupied the medullary space. From this study, it seems possible to predict the histopathologic changes in the femoral head using MR images.     

Imaging the painful hip

With the advent of magnetic resonance imaging and, subsequently, magnetic resonance arthrography, the imaging algorithm for hip pain has evolved considerably. Magnetic resonance imaging has supplanted bone scintigraphy as the first line imaging test after conventional radiographs in the setting of suspected occult fracture, transient marrow edema, and osteonecrosis. Computed tomography scanning and magnetic resonance imaging are invaluable for the evaluation of monarticular arthropathies such as pigmented villonodular synovitis and synovial osteochondromatosis. By combining conventional magnetic resonance imaging with capsular distention afforded by arthrography, magnetic resonance arthrography has become the imaging examination of choice for disorders of the acetabular labrum and for the evaluation of articular cartilage at the hip.     

The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging. A case report and review of the literature

The piriformis syndrome (PS) is a controversial cause of hip pain because of the lack of objective findings to support the diagnosis. Computed tomography (CT) and magnetic resonance (MR) imaging revealed PS in a 27-year-old woman. This case may be one of the first reports in the literature on a piriformis muscle enlargement documented by CT and MR imaging.     

Correlation of the findings of magnetic resonance imaging with those of bone biopsy in patients who have stage-I or II ischemic necrosis of the femoral head

A prospective study was undertaken to determine the diagnostic accuracy of magnetic resonance imaging in the evaluation of a symptomatic hip for which a diagnosis of early ischemic necrosis of the femoral head was suspected. Fifteen patients (sixteen symptomatic hips), for whom the findings of magnetic resonance imaging were consistent with a diagnosis of osteonecrosis of the femoral head, had a core decompression and a biopsy of the contents of the core. Preoperative magnetic-resonance imaging was useful for planning which segment of the femoral head should be biopsied. Plain radiographs and tomograms of the hips were also made. On the basis of the plain radiographs, ten hips were determined to have Stage-I findings and six hips, Stage-II ischemic necrosis, according to the system of Ficat and of Arlet and Ficat. Histological study revealed evidence of necrosis in all of the biopsy specimens of bone. We concluded that findings of magnetic resonance imaging that are characteristic of osteonecrosis correlate well with the results of biopsies of bone in patients who have an early stage of ischemic necrosis. Magnetic resonance imaging is a highly sensitive and specific method for both the diagnosis and the location of Stage-I and Stage-II osteonecrosis.     

Magnetic resonance imaging after total hip arthroplasty: evaluation of periprosthetic soft tissue

BACKGROUND: The evaluation of periprosthetic osteolysis in patients who have had a total hip arthroplasty is challenging, and traditional imaging techniques, including magnetic resonance imaging and computerized tomography, are limited by metallic artifact. The purpose of the present study was to investigate the use of modified magnetic resonance imaging techniques involving commercially available software to visualize periprosthetic soft tissues, to define the bone-implant interface, and to detect the location and extent of osteolysis. METHODS: Twenty-eight hips in twenty-seven patients were examined to assess the extent of osteolysis (nineteen hips), enigmatic pain (five), heterotopic ossification (two), suspected tumor (one), or femoral nerve palsy (one). The results were correlated with conventional radiographic findings as well as with intraoperative findings (when available). RESULTS: Magnetic resonance imaging demonstrated the bone-implant interface and the surrounding soft-tissue envelope in all hips. Radiographs consistently underestimated the extent and location of acetabular osteolysis when compared with magnetic resonance imaging. Magnetic resonance imaging also disclosed radiographically occult extraosseous soft-tissue deposits that were similar in signal intensity to areas of osteolysis, demonstrated the relationship of these deposits to adjacent neurovascular structures, and allowed further visualization of hypertrophic synovial deposits that accompanied the bone resorption in twenty-five of the twenty-eight hips. CONCLUSIONS: Magnetic resonance imaging is effective for the assessment of the periprosthetic soft tissues in patients who have had a total hip arthroplasty. While not indicated for every patient who has pain at the site of an arthroplasty, these techniques can be effective for the evaluation of the surrounding soft-tissue envelope as well as intracapsular synovial deposits and are more effective than radiographs for the detection and evaluation of osteolysis, thus aiding in clinical management.     

Femoral Head Fracture without Dislocation by Low-Energy Trauma in a Young Adult

We describe the case of a healthy young man with a femoral head fracture by low-energy trauma that occurred without evidence of hip dislocation. While plain radiographs showed no definite fracture or dislocation, computed tomography (CT) and magnetic resonance imaging (MRI) revealed a femoral head fracture with a wedge-shaped cortical depression at the superomedial aspect of the femoral head. Our patient reported feeling that the right hip had been displaced from its joint for a moment. This probably represented subluxation with spontaneous relocation. The characteristic findings and possible mechanisms of this fracture were postulated on the basis of the sequential 3 dimensional-CT and MRI. The clinical results of conservative treatment were better than those of previously reported indentation fractures.