Daphne J. Theodorou

Percutaneous balloon kyphoplasty for the correction of spinal deformity in painful vertebral body compression fractures

Vertebral body compression fractures can cause chronic pain and may result in progressive kyphosis. Although vertebroplasty has been used to treat pain, it does not attempt to restore vertebral body height and eliminate spinal deformity. Percutaneous balloon kyphoplasty is a novel technique, which involves the introduction of inflatable bone tamps into the fractured vertebral body for elevation of the endplates, prior to fixation of the fracture with bone cement. Our initial experience with this minimally invasive procedure indicates that percutaneous balloon kyphoplasty can be efficacious in the treatment of painful, osteoporotic vertebral compression fractures.

Post-traumatic and stress-induced osteolysis of the distal clavicle: MR imaging findings in 17 patients.

Abstract Objective. To describe the MR imaging findings in patients with osteolysis of the distal clavicle and to compare the MR imaging appearance of clavicular osteolysis following acute injury with that related to chronic stress. Design and patients. MR imaging examinations were reviewed in 17 patients (14 men, 3 women; ages 16–55 years) with the diagnosis of post-traumatic or stress-induced osteolysis of the clavicle. A history of a single direct injury was present in seven patients and a history of weight-lifting, participation in sports, or repetitive microtrauma was present in 10 patients. Results. MR imaging showed edema in the distal clavicle in 17 patients and, of these, eight also had edema in the acromion. The edema was most evident in STIR and fat-suppressed T2-weighted pulse sequences. Other findings about the acromioclavicular (AC) joint were prominence of the joint capsule in 14, joint fluid in eight, cortical irregularity in 12, and bone fragmentation in six patients. No differences in the MR imaging features of post-traumatic and stress-induced osteolysis of the distal clavicle were observed. Conclusion. Post-traumatic and stress-induced osteolysis of the distal clavicle have similar appearances on MR imaging, the most common and conspicuous MR imaging feature being increased T2 signal intensity in the distal clavicle.

MR imaging findings of pyogenic bacterial myositis (pyomyositis) in patients with local muscle trauma: illustrative cases

Pyogenic myositis (pyomyositis) represents a bacterial infection of muscle, usually caused by Staphylococcus aureus that is endemic in tropical regions. Pyomyositis commonly affects patients who are immunocompromised or who have underlying chronic disorders. Lower extremity localization of infection is typical. The most common pattern of disease, however, appears to be a solitary abscess in the quadriceps musculature. Delay in accurate diagnosis is frequent and clinical deterioration can be precipitous. In view of the high associated morbidity, early imaging to detect, localize, and define disease extent is important. Magnetic resonance imaging (MRI) plays a key role in the definitive diagnosis of pyomyositis. This article provides a pictorial illustration of the spectrum of MRI findings associated with pyogenic myositis.

Dual-energy X-ray absorptiometry in clinical practice:Application and interpretation of scans beyond the numbers

Dual-energy X-ray absorptiometry (DXA) is widely used for measurement of bone mineral density (BMD). In routine clinical practice, a diversity of DXA scan findings that deviate from anticipated anatomical landmarks and require a sophisticated approach to patient positioning and scan analysis may be identified. Recognition of various artifacts and pathologic processes that can falsely increase the measured BMD is essential to accurate DXA scan analysis. Critical evaluation of the DXA scan image, and careful appraisal of numeric data on the computer-generated printout by clinicians and radiology technologists are instrumental to ensure correct DXA scan interpretation. We demonstrate a spectrum of incidental findings that may influence BMD measurements and analyze common pitfalls of DXA scan interpretation. Radiographic correlation can help further evaluate a suspected abnormality displayed on the DXA image.

Quantitative computed tomography in the evaluation of spinal osteoporosis following spinal cord injury

Abstract: Disuse osteoporosis occurs in the lower extremities of patients with spinal cord injury (SCI). However, spinal osteoporosis is not usually observed in these patients. We investigated lumbar spine bone mineral density (BMD) in SCI patients using single energy quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA). Our study population consisted of 64 patients with long-standing SCI. Spine BMD (g/cm3) was assessed by QCT at four vertebrae ranging from T11 to L4 with single midvertebral CT slices 1 cm thick parallel to the vertebral end-plates. Confounding variables affecting normal trabecular bone pattern, such as compression fractures, surgical hardware or fat replacement, were excluded. For a subset of 29 patients, DXA values of the spine and femoral neck were also measured, and QCT and DXA Z-scores were compared On the average, the 64 SCI patients had Z-scores 2.0 ± 1.2 below those of age-matched controls. In the subset of 29 patients with both QCT and DXA measurements, the QCT and DXA Z-scores were 2.4 ± 1.1 below and 1.3 ± 2.3 above the mean, respectively (p<0.0001). Our results indicate that QCT reveals osteoporosis of the spine after SCI, in contrast to DXA. We postulate that QCT is more valuable for evaluating spinal osteoporosis following SCI than DXA and thus recommend QCT for spinal BMD studies in SCI.

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.

Stress fractures of the lateral metatarsal bones in metatarsus adductus foot deformity: a previously unrecognized association.

Abstract Objective. To document a distinctive pattern of stress fractures in the lateral metatarsal bones of patients with metatarsus adductus foot deformity. Design and patients. Conventional radiographs and available medical records were reviewed in 11 patients (6 women, 5 men; ages 25–61 years) with stress fractures of the lateral (fourth or fifth) metatarsal bones and metatarsus adductus. Evaluation included the number and location of fracture(s), forefoot adduction angle, and qualitative assessment of bone mineral density. Conditions that might predispose patients to metatarsal fractures, including direct trauma, osteoporosis, and neuropathic osteoarthropathy were also recorded. Results. A total of 22 stress fractures were demonstrated, 17 of which involved the lateral metatarsals. A solitary fracture was present in six patients, while multiple fractures were evident in five patients. The sites of involvement were the fifth metatarsal (n=10), fourth metatarsal (n=7), third metatarsal (n=3), second metatarsal (n=1), and first metatarsal (n=1) bones. The locations of the stress fractures were in the proximal one-third of the metatarsal bones in 19 instances (86%) and in the middle one-third in three instances (14%). Forefoot adduction angle measured between 21° and 37° (normal range 8°–14°). Conclusion. Patients with metatarsus adductus may be at increased risk for stress fractures involving the lateral metatarsal bones, likely owing to the presence of altered biomechanics that place greater loads across the lateral aspect of the foot.

Imaging in the Dialysis Patient: Imaging in Dialysis Spondyloarthropathy

Destructive spondyloarthropathy has recently been described in patients who undergo maintenance hemodialysis for chronic renal disease. The condition most frequently involves the lower segment of the cervical spine, although the craniocervical junction also may be affected. Although the pathogenesis of destructive spondyloarthropathy remains unclear, the disorder is thought to relate to a hemodialysis‐associated amyloidosis. It appears that the disease correlates with the duration of hemodialysis, although it has been reported in patients with chronic renal insufficiency not associated with hemodialysis. Radiographic features simulate those of an infectious process, encompassing a range of abnormalities from superficial erosions to large bony defects. Computed tomography (CT) images reveal osteolytic areas, with bone sclerosis of adjacent vertebral endplates, and minimal osteophytosis. The intervertebral spaces appear narrow or obliterated. On magnetic resonance imaging (MRI), the disorder may show the imaging characteristics of spondylodiskitis. The absence of high signal intensity on T2‐weighted images generally helps to eliminate the diagnosis of an infection. With progression of the disease, collapse of a vertebral body and spinal instability may occur. Severe complications of destructive spondyloarthropathy in long‐term dialysis patients may include spinal cord compromise, necessitating surgical decompression, with or without spinal stabilization.

Sonography and venography of the lower extremities for diagnosing deep vein thrombosis in symptomatic patients

The purpose of this study was to investigate the efficacy of sonography and the frequency of indeterminate sonographic examinations in the evaluation of patients with suspected lower extremity deep vein thrombosis (DVT). We prospectively evaluated 136 symptomatic patients (157 extremities) with suspected DVT using sonography and contrast-enhanced venography (n=106 patients, 115 extremities). Using venography as the reference standard for diagnosing DVT, the sensitivity and specificity of sonography was 92.8% and 98%, respectively, yielding an accuracy of 96.8%. The frequency of indeterminate examinations for calf DVT was 32.4%. One (0.7%) fatal pulmonary embolus occurred in our patients. The pulmonary embolism (PE) rate was 1.6% after lower extremity sonography with negative results. Sonography is highly accurate in detecting lower extremity DVT in symptomatic patients. Because of the high frequency of indeterminate studies in the calf and the associated possible risk of pulmonary emboli, we urge radiologists exercise additional caution when evaluating symptomatic patients with clinically suspected lower extremity DVT.

Spontaneous spinal subarachnoid hemorrhage associated with subdural hematoma at different spinal levels

We describe the clinical features and MR-imaging findings of spontaneous spinal subarachnoid hemorrhage located in the lumbar spine associated with subdural hematoma at a higher, thoracic level in a 66-year-old man without neurological deficit. The sequential MR-imaging changes of hemorrhage at various stages in its evolution are portrayed. The possible pathogenetic mechanism for these very unusual, combined hemorrhages in both spinal compartments is discussed.