Case report 698: Osteoma of the clavicle

We have presented a case of an osteoma of the clavicle in a 41-year-old man. The possibility of alternate diagnoses--in particular, ancient osteochondroma, posttraumatic hyperostosis, and parosteal osteosarcoma--was addressed. However, the pathological examination was most consistent with the diagnosis of osteoma. This benign bone lesion is most often found in the calvarium, jaw, and face. Osteomas of long bones remain extremely rare, except in the setting of Gardner's syndrome.

Detection of internal mammary lymph node enlargement: comparison of CT scans and conventional roentgenograms

Sixty-two patients with breast cancer had thoracic computed tomography (CT) scans and conventional chest radiographic (CXR) examinations separated by an average of 29 days. CT served as the gold standard showing 13 cases with enlarged internal mammary nodes 0.4 to 7 cm in diameter. Original CXR interpretations were available. Additionally, these films were reinterpreted, without knowledge of the CT results, with special attention to the retrosternal region on the lateral film including the use of a bright light and comparison to prior lateral views. Original CXR interpretations detected only one (7 cm) enlarged node. Sensitivity was 8% and specificity 100%. Reinterpretation of the CXRs, without knowledge of the CT results, with special attention to the retrosternal region yielded five true positive and seven false positive determinations for a sensitivity of 38% and specificity of 86%. No enlarged node under 2.5 cm in diameter was detected on CXR. Sensitivity of CXR can be considerably improved by careful evaluation of the retrosternal space, but at the cost of considerable increase in false positive examinations. CT is necessary to achieve reasonable sensitivity and specificity in the detection of internal mammary lymphadenopathy.

Focal pulmonary lesions in patients with AIDS: percutaneous transthoracic needle biopsy

The authors performed percutaneous transthoracic needle biopsy (PTNB) in 13 patients with acquired immunodeficiency syndrome (AIDS) and previously undiagnosed focal pulmonary lesions. Findings with PTNB were diagnostic in 11 of 13 cases. Complications included minimal hemoptysis in one case and small pneumothoraxes in two cases, one of which required chest tube drainage. The authors did not experience the high complication rate reported previously by some authors who used this diagnostic procedure in AIDS patients. In cases in which findings at fiberoptic bronchoscopy with transbronchial biopsy and lavage failed to provide a diagnosis, PTNB provided a reliable, relatively safe diagnostic tool to establish the cause of pulmonary masses or focal infiltrates in AIDS patients.

Bone marrow perfusion evaluated with gadolinium-enhanced dynamic fast MR imaging in a dog model

The authors studied, in a dog model, the feasibility of using gadolinium-enhanced dynamic magnetic resonance (MR) imaging to noninvasively monitor bone marrow perfusion of the proximal femur. With a gradient-recalled acquisition, sequential images of 10 hips in five healthy dogs were obtained for 14 minutes after an intravenous bolus injection of 0.2 mmol of gadopentetate dimeglumine per kilogram. The study was repeated after unilateral arterial embolization of major femoral vessels. Radiolabeled microspheres were injected before and after vessel occlusion. After unilateral embolization, statistically significant differences in enhancement were observed between embolized and control sides (eg, 31% vs 83% average peak enhancement in the femoral neck). There was a high correlation (r = .81 [average]) between the MR data and the microsphere blood flow measurements. The postembolization data indicate that contrast-enhanced fast MR imaging may allow early detection of abnormal bone marrow flow. This technique may be valuable in evaluating patients at risk for avascular necrosis of the femoral head, especially in posttraumatic cases.

Extramedullary hematopoiesis mimicking the appearance of carcinomatosis or peritoneal mesothelioma: computed tomography demonstration

The computed tomographic (CT) appearance of extensive intra-abdominal extramedullary hematopoiesis is illustrated in a 51-year old woman with agnogenic myeloid metaplasia. The CT images closely simulate peritoneal carcinomatosis or peritoneal mesothelioma.

Normal age-related patterns of cellular and fatty bone marrow distribution in the axial skeleton: MR imaging study

Knowledge of age-related distribution patterns of cellular and fatty marrow is critical to the interpretation of magnetic resonance (MR) imaging studies. To determine such patterns, the authors retrospectively evaluated 70 examinations each of the skull, cervical spine, thoracic spine, lumbar spine, pelvis, and proximal femur (420 examinations) in patients without known bone marrow abnormality who ranged in age from 6 months to older than 70 years. Two to four distinct patterns were identified in each anatomic area on spin-echo images obtained with a short repetition time and a short echo time. The relative frequency of the patterns for different age groups is consistent with the known physiologic conversion from cellular to fatty marrow with advancing age. Knowledge of these patterns should help in the interpretation of MR images of the axial skeleton.

The longitudinal course of hand osteoarthritis in a male population

In this prospective analysis of the natural history of osteoarthritis (OA) of the hand, the incidence and progression of various radiographic features of OA were examined in 177 men who participated in the Baltimore Longitudinal Study of Aging. Subjects who were less than 60 years old were selected based on the availability of at least 4 hand radiographs taken during at least 20 years of followup, while subjects who were age 60 or older were required to have had at least 4 hand radiographs taken during only 14 years of followup. Individual joints of the hands were graded for the presence and severity of 5 features of OA: osteophytes, joint space narrowing, subchondral sclerosis, lateral deformity, and cortical collapse. They were also graded according to the global Kellgren/Lawrence scale. The incidence and rate of progression of OA, as measured by all scales, increased in progressively older age groups. Cox's proportional hazards models showed that isolated doubtful osteophytes (Kellgren/Lawrence grade 1) and isolated joint space narrowing predicted the development of the radiographic features of OA. The rate of OA progression slowed as the severity increased. We conclude that, in men, the incidence of radiographic features of hand OA increases with age. Regardless of age, the earliest radiographic signs of OA are joint space narrowing and doubtful osteophytes.

Computed tomography evaluation of the sacroiliac joints in Crohn disease. Radiologic/clinical correlation

Computed tomography (CT) was used in a prospective study of the sacroiliac joints in 86 patients with Crohn disease to determine the type and frequency of sacroiliac joint abnormalities present in this population. The CT findings were correlated with review of the clinical history in 64 patients. Computed tomography demonstrated changes of sacroiliitis in 29% of the study group. This high prevalence of sacroiliac joint abnormality was found even in those under 30 years of age. It exceeds the 11-19% previously reported from plain film examination, reflecting the greater sensitivity of CT. In the subgroup of 64 patients studied clinically, 19 (30%) had abnormal sacroiliac joints on CT, but only 2 (3%) reported symptoms related to the sacroiliac joints.

Predicting femoral neck strength from bone mineral data. A structural approach

An interactive computer program was developed to derive femoral neck geometry from raw bone mineral image data for an estimate of hip strength using single plane engineering stress analysis. The program, which we call Hip Strength Analysis (HSA), was developed as an attempt to improve the predictive value of hip bone mineral data for osteoporosis fracture risk assessment. We report a series of experiments with an aluminum phantom and with cadaver femora, designed to test the accuracy of derived geometric measurements and strength estimates. Using data acquired with both Lunar DP3 (DPA) and Hologic QDR-1000 (x-ray) scanners, HSA computed femoral neck cross-sectional areas (CSA) and cross-sectional moments of inertia (CSMI) on an aluminum phantom were in excellent agreement with actual values (r greater than .99). Using Lunar DP3 data, CSA and CSMI measurements at mid-femoral necks of 22 cadaver specimens were in good general agreement with literature values. HSA computed cross-sectional properties of three of these specimens were compared with measurements derived from sequential CT cross-sectional images. Discrepancy between the two methods averaged less than 10% along the length of the femoral neck. Finally, breaking strengths of 20 of the femora were measured with a materials testing system, showing better agreement with HSA predicted strength (r = .89, percent standard of the estimate (%SEE) = 21%) than femoral neck bone mineral density (r = .79, %SEE = 28%).

New radiographic grading scales for osteoarthritis of the hand. Reliability for determining prevalence and progression

We developed and evaluated scales for grading the prevalence and progression of the individual radiographic features of osteoarthritis (OA) of the hand. Four equally time-spaced hand radiographs from 50 participants in the Baltimore Longitudinal Study of Aging, who were followed for at least 20 years, were read separately and "blindly" by 4 experienced, trained readers. Eleven hand joints were individually assessed for the presence of osteophytes, joint space narrowing, subchondral cysts, subchondral sclerosis, lateral deformity, and cortical collapse, and were also graded using the Kellgren/Lawrence scale, a global estimate of OA. The intraclass correlation coefficient was used to determine cross-sectional inter- and intrareader reliability. Interreader agreement on OA progression was evaluated using life-table analysis. Each of the grading scales for the individual radiographic features of OA of the hand, except for cysts, were cross-sectionally reliable between readers. Each reader was able to reproduce his original scores almost perfectly when grading the radiographs a second time. Using these scales, the different readers agreed on all the features of longitudinal progression of OA of the hand, except cysts. We believe that this method for grading hand radiographs for OA has proved to be reliable for both cross-sectional and longitudinal studies.

Treated invasive cervical carcinoma. Utility of computed tomography in distinguishing between skeletal metastases and radiation necrosis

The bony pelvis should be carefully evaluated on computed tomography (CT) scans of the lower abdomen and pelvis performed for staging cervical cancer or for evaluating suspected recurrence. CT provides optimal imaging of the spine and pelvis, frequently providing a clinically relevant supplement to bone scan or plain film information. In a study of eight patients with skeletal metastases from cervical carcinoma and three cases of radiation osteitis, overlap existed in their imaging characteristics. Metastases were always lytic but nearby sclerotic areas from radiation were often present. Radiation osteitis may be lytic, sclerotic, or mixed, and both may avidly accumulate bone-scanning radiotracers. The absence of a soft tissue mass, slow progression, blastic elements, and sharply defined borders on CT suggest radiation necrosis. However, in some lesions within a radiation portal, biopsy or MRI may be required for final diagnosis.

Fracture nonunion: CT assessment with multiplanar reconstruction

Nineteen patients with suspected or possible fracture nonunion underwent computed tomography (CT) with multiplanar reconstruction (MPR). Each case represented a difficult problem in fracture management in which clinical and conventional radiographic examinations had failed to provide a definitive diagnosis. CT with MPR demonstrated nonunion in 13 of 19 cases by delineating the lack of bone bridging across the fracture site in multiple planes. Variable amounts bridging were detected in six cases, indicating partial healing or delayed union. Evaluation of fracture healing with MPR was possible despite remaining metal hardware (ten cases), multiple operations (15 cases), or bone grafting (five cases). CT with MPR aided surgical planning and affected treatment options by providing a more detailed assessment of malalignment and angular deformities, the magnitude of the gap in bone, and the integrity of the adjacent weight-bearing joints in multiple projections. It is an important new modality for evaluating fracture nonunion.

Acetabular fractures: optimal imaging

In 19 cases of acetabular fracture, computed tomography (CT) with volumetric three-dimensional (3D) reconstructions displayed as video loops about horizontal and vertical axes of rotation replaced the traditional imaging combination of CT and multiple plain radiographs, while offering significant advantages. Overlying bowel content or foreign matter obscured detail in 36 of 45 plain radiographic views, and positioning or radiographic technique was suboptimal in 21. Three-dimensional reconstructions completely eliminated these problems. These 3D reconstructions accurately simulated oblique, inlet, and tangential views in all cases. In ten of 19 cases a nonconventional oblique view, and in 13 of 19 cases a cephalocaudal angulation other than the inlet, tangential, or anteroposterior view, best demonstrated the fracture. Elimination of five plain radiographs resulted in a skin radiation dose savings of 5 rad (50 mGy). No difficult or painful patient positioning was required beyond that necessary for the standard CT examination.

Acetabular protrusion in the Marfan syndrome

The Marfan syndrome is a genetic disorder of connective tissues resulting in ocular, cardiovascular, and musculoskeletal deformities. The authors reviewed 22 cases of Marfan syndrome. Forty-five percent (ten of 22) of the patients had acetabular protrusion, with one-half of these being unilateral and one-half bilateral. Scoliosis was associated with acetabular protrusion in 90% of cases (nine of ten). The authors conclude that acetabular protrusion is a common skeletal finding in the Marfan syndrome.

Fibrosarcoma in a patient with scleroderma

Malignancies have been described in association with various connective tissue disorders. While such associations may be relatively common in some disorders, such as polymyositis, the relationship between scleroderma and malignancy is more controversial. A case of fibrosarcoma of the tibia in a patient with scleroderma is presented, with correlation of conventional radiography, computed tomography, and histopathology.

Volumetric rendering techniques: applications for three-dimensional imaging of the hip

Volumetric rendering is a new approach to three-dimensional (3D) imaging that overcomes many of the drawbacks of currently available surface-rendering systems. Its application on the Pixar Imaging System in two cases of acetabular fracture was assessed to illustrate the features of the technique. The fast-computing architecture and large memory of this system allow rapid generation of a series of high-quality 3D images in each plane of rotation (x or spinal axis, z or somersaulting axis) that can be viewed as independent static images or as an animated real-time video loop. Editing to remove the normal contralateral hemipelvis enhances appreciation of acetabular abnormalities. Every pixel of computed tomographic data is preserved, allowing representation of both soft tissue and bone as translucent overlap. The presentation of data also allows detection of subtle abnormalities and features and minimizes the artifact generation common in surface-rendered images.

Three-dimensional imaging of acetabular trauma

Computed tomography (CT) scanning is widely used in evaluation of acetabular fractures. Three-dimensional (3D) images of the pelvis can be created from CT scan data. This article reports two studies, each employing one type of 3D imaging in acetabular trauma cases. The first was a study of 21 patients utilizing surface-rendered 3D images, the second, a study of 19 patients using volume-rendered 3D images. Both types of 3D images were clinically helpful and can be used in lieu of conventional plain films as a supplement to CT examination. Advantages of volume-rendered images are described.

Pulmonary hamartoma: CT findings

Forty-seven patients with a proved (n = 31) or presumed (n = 16) diagnosis of pulmonary hamartoma were studied prospectively by thin-section computed tomography (CT). CT criteria for hamartoma included a diameter of 2.5 cm or less, a smooth edge, and focal collections of fat or fat alternating with areas of calcification. No case of cancer (n = 283) or metastatic disease (n = 72) fulfilled these criteria. Seventeen hamartomas with no detectable calcium or fat were not diagnosed by means of CT. Two other lesions contained diffuse calcium deposits. In 28 lesions, a CT diagnosis of hamartoma was based on the detection of fat (n = 18) or calcium plus fat (n = 10). Twelve such cases were proved histologically by means of thoracotomy or needle biopsy; the remainder, including eight in asymptomatic patients aged 65 years or older, were managed with conservative follow-up.

Multiplanar (MPR) imaging of the hip

Multiplanar CT expands the ability of the radiologist to define the extent of disease, to suggest appropriate surgery, and to offer a probable prognosis.

Femoral head avascular necrosis: CT assessment with multiplanar reconstruction

Thirty-two patients with avascular necrosis (AVN) of the femoral head underwent imaging studies using computed tomography with multiplanar reconstructions (CT/MPR). Staging of the disease by means of CT/MPR images was compared with traditional staging by means of routine frontal and frog-leg lateral radiographs. CT/MPR examination upgraded staging in 30% of the hips studied and made significant contributions to patient management in 14 (54%) of 26 patients for whom both CT scans and plain-film radiographs were available for comparison. Asymptomatic and radiographically normal contralateral hips were found at CT study to have stage II or stage III AVN in four patients. Subtle alterations in trabecular patterns, joint spaces, femoral-head contours, and acetabula were well defined on CT/MPR studies in many cases; previously undetected or ill-defined abnormalities were frequently visualized. The major weight-bearing components of the hip (anterior and posterior acetabular columns, acetabular dome, and superior pole of the femur), which may be poorly defined on CT scans due to partial volume effects on the transaxial images, were best seen on the sagittal and coronal reconstructions. A new system for staging AVN is suggested.

Focal lytic lesions associated with femoral stem loosening in total hip prosthesis

Focal lytic lesions may occur in the proximal femur associated with loosening of the femoral component of a total hip prosthesis. During long-term follow-up of 62 patients with total hip prostheses, five such lesions developed. Histologically the lesions appear to be a histiocytic response to fragmented methylmethacrylate. Radiographically the lesions may suggest infection or neoplasm. Pathologic fracture may occur through large lesions. Experience in one case suggests that thorough removal of the tissue at the time of revision may be necessary to prevent recurrence. The recent reports of several malignant neoplasms developing in association with the femoral components of total hip replacements makes recognition of these benign focal lytic lesions even more important.

Isolated nodular pulmonary amyloidosis: diagnosis by percutaneous needle aspiration biopsy

We have reported three cases of isolated nodular pulmonary amyloidosis, a rare condition whose roentgenographic presentation frequently mimics tumor metastatic to the lung or primary lung cancer. Computerized tomography is not helpful in diagnosing this condition. In our experience, the specific diagnosis could be made by aspiration needle biopsy, avoiding thoracotomy.