Ribbing disease (multiple diaphyseal sclerosis): imaging and differential diagnosis.

OBJECTIVE: This study describes the clinical presentation and the course of Ribbing disease in six patients and illustrates imaging features on plain radiography, conventional and computed tomography, and 99mTc-methylene diphosphonate bone scans. MATERIALS AND METHODS: Between 1982 and 1990, six female patients presented with painful bony lesions that were believed to be Ribbing disease. Ten bones were affected: both tibiae in three patients, a unilateral tibia in one, both femora in one, and a unilateral femur in one. Plain radiographs and either conventional or computed tomography were available for all patients and 99mTc-methylene diphosphonate bone scans, for five patients. All patients underwent open biopsy and/or surgical decompression. RESULTS: The diagnosis was reached in all patients through a combination of clinical findings (lack of systemic signs of infection or laboratory values suggesting metabolic bone disease), imaging, histologic evaluation, and specimen cultures. Radiographs and tomographic studies showed benign-appearing endosteal and periosteal cortical thickening. Intense uptake of radionuclide tracer was confined to the shaft of all involved bones. All pathologic specimens revealed nonspecific changes that included a slow increase in the mass of cortical and endosteal bone. These specimens also assisted in excluding neoplastic or infectious causes for the new bone formation. CONCLUSION: Ribbing disease is a rare disorder that, on imaging studies, may simulate stress fracture, chronic infection, bone-forming neoplasia, or a systemic metabolic or endocrine disorder. Clinical and imaging features may suggest the correct diagnosis.

Mammography fixed grid versus reciprocating grid: evaluation using cadaveric breasts as test objects.

In this study we use unfixed cadaveric breasts to obtain mammography images with fixed and reciprocating grids. Sheets of acrylic, containing one or more clusters of simulated calcifications and masses, were superimposed on two fresh cadaveric breasts (3.4 and 6.5 cm thick), and were imaged with a fixed grid and a reciprocating grid. Six radiologists, working independently, attempted to identify the number of clusters and/or masses in 114 images containing 139 clusters of simulated calcifications and 42 simulated masses. Thirty-four of these images were normal, containing no lesions. For the thinner breast, no statistically significant difference was found in the detection of clusters of calcifications in the images produced with the fixed grid compared to those produced with the reciprocating grid. However, for the detection of calcifications in images of the thicker breast, sensitivity of 74% for detection of calcifications when a fixed grid was used was significantly less than sensitivity of 86% when a reciprocating grid was used (P = 0.006). The mass detection sensitivity was 91% for images made with a fixed grid compared to 96% for images made with a reciprocating grid, but the difference was not statistically significant (P = 0.346). The use of cadaveric breasts as test objects was well accepted by radiologists. Only for the thick cadaveric breast were differences between the two grids significant, and these differences were restricted to the task of finding calcifications.

Imaging the diabetic foot.

Early and accurate diagnosis of infection or neuropathy of the diabetic foot is the key to successful management. Angiopathy leads to ischemia which, in combination with peripheral neuropathy, predisposes to pedal skin ulceration, the precursor of osteomyelitis. Chronic hyperglycemia promotes production of glycosylated end products which accumulate on endothelial proteins, causing ischemia of the vasa nervorum. When combined with axonal degeneration of the sensory nerves, the result is hypertrophic neuroarthropathy. Should the sympathetic nerve fibers also be damaged, the resultant loss of vasoconstrictive impulses leads to hyperemia and atrophic neuroarthropathy. Plain radiography, although less sensitive than radionuclide, magnetic resonance (MR), and computed tomographic examinations, should be the initial procedure for imaging suspected osteomyelitis in the diabetic patient. If the radiographs are normal but the clinical suspicion of osteomyelitis is strong, a three-phase 99mTc-MDP scan or MR imaging is recommended. An equivocal 99mTc-MDP scan should be followed by MR imaging. To exclude osteomyelitis at a site of neuroarthropathy, a 111In white blood cell scan is preferable. To obtain a specimen of bone for bacteriological studies, percutaneous core biopsy is the procedure of choice, with the entrance of the needle well beyond the edge of the subjacent ulcer.

Measurement of acetabular version on the axiolateral radiograph.

There are 3 definitions of acetabular version: true (anatomic) version, planar (radiographic) version, and operative version. Although planar version can be measured on standard radiographs, the measurement may be inaccurate when applied to metal-backed acetabular components. However, another version angle is depicted clearly on an angled, cross-table lateral radiograph of the hip--the axiolateral view, and this angle readily distinguishes anteversion from retroversion. If the angle of the xray beam is known or is standardized, version measured on the axiolateral view can be converted to the other version angles. Nomograms for these conversions are presented. In most cases, acetabular version measured on the axiolateral radiograph closely approximates planar version.

Labrocapsular ligamentous complex of the shoulder: normal anatomy, anatomic variation, and pitfalls of MR imaging and MR arthrography.

Magnetic resonance (MR) imaging is a useful modality for evaluating the labrocapsular ligamentous complex (LCLC) of the shoulder. MR arthrography is an important and occasionally indispensable supplementary modality for accurate differentiation between normal and deranged glenohumeral joints. Because of the joint distention that occurs during MR arthrography, it is especially helpful in detecting subtle capsular derangement, as occurs in patients with atraumatic instability. Also, some of the pitfalls associated with MR imaging of the LCLC are less likely to occur with MR arthrography. Radiologists should look for several key abnormalities when evaluating MR images of the shoulder: an anterior or posterior Bankart lesion; a Hill-Sachs defect; a tear of the rotator cuff, glenoid labrum, or superior labrum-biceps tendon attachment; and loose bodies. Knowledge of normal anatomy, normal variations, and pitfalls in image interpretation related to evaluation of the LCLC will help the radiologist accurately detect debilitating derangements associated with glenohumeral instability.

Imaging shoulder impingement.

Appropriate imaging and clinical examinations may lead to early diagnosis and treatment of the shoulder impingement syndrome, thus preventing progression to a complete tear of the rotator cuff. In this article, we discuss the anatomic and pathophysiologic bases of the syndrome, and the rationale for certain imaging tests to evaluate it. Special radiographic projections to show the supraspinatus outlet and inferior surface of the anterior third of the acromion, combined with magnetic resonance images, usually provide the most useful information regarding the causes of impingement.

Os odontoideum in identical twins: perspectives on etiology.

Most authorities favor the hypothesis of an acquired etiology of os odontoideum. We present the cases of identical twin sisters with os odontoideum in association with a congenital partial fusion of the posterior elements of the second and third cervical vertebrae, and discuss the implications. We believe that this is the first report of familial os odontoideum in a context which suggests a genetic etiology.

Teleconferencing for cost-effective sharing of radiology educational resources: potential and technical development.

To develop a cost-effective method of sharing educational resources, a dial-up teleconferencing network was implemented between three radiologic sites for a 30-day period of evaluation. By means of standard dial-up telephone channels, compressed video and audio signals displayed radiologic images, slides, and text, allowing residents and faculty from the three sites to participate in sight and sound interactions. Each of the three sites used compressed video/audio coder-decoders (codecs) conforming to the Consultative Committee on International Telegraphy and Telephony H.261 standard. Four video cameras were used at each site, and the audio was run in full duplex mode. A multipoint video bridge was used to broadcast codec output signals to the input lines of the other codecs. Our evaluation found audio quality to be suboptimal, but capable of being improved; diagnostic image quality was adequate when a video zoom mode was used; the digital-archive mode of the codec proved advantageous; the H.261 codec permitted participation from all sites; and all conference lecturers were able to conduct their conferences as they were accustomed. Although audio quality and spatial resolution need to be improved, the results of this pilot study imply that dial-up compressed video conferencing has the potential to become a practical, cost-effective method of sharing educational resources by means of interactive radiologic multisite educational programs.

Mammographic findings after the removal of breast implants.

A recent wave of adverse publicity regarding silicone breast implants has led increasing numbers of women to undergo removal of their implants. In this pictorial essay, we present the spectrum of mammographic findings after implant removal. These range from a nearly normal appearance to architectural distortion and even residual spiculated silicone granulomas that may simulate malignant tumors. Our examples emphasize that comparison with previous mammograms and a detailed surgical history are essential if unnecessary investigations of postsurgical and residual benign abnormalities are to be avoided.

Effect of poor control of film processors on mammographic image quality.

With the increasingly stringent standards of image quality in mammography, film processor quality control is especially important. Current methods are not sufficient for ensuring good processing. The authors used a sensitometer and densitometer system to evaluate the performance of 22 processors at 16 mammographic facilities. Standard sensitometric values of two films were established, and processor performance was assessed for variations from these standards. Developer chemistry of each processor was analyzed and correlated with its sensitometric values. Ten processors were retested, and nine were found to be out of calibration. The developer components of hydroquinone, sulfites, bromide, and alkalinity varied the most, and low concentrations of hydroquinone were associated with lower average gradients at two facilities. Use of the sensitometer and densitometer system helps identify out-of-calibration processors, but further study is needed to correlate sensitometric values with developer component values. The authors believe that present quality control would be improved if sensitometric or other tests could be used to identify developer components that are out of calibration.

Testing mammography equipment: evolution over a 4-year period.

The results of quality control (QC) tests on 70 mammography units in Southern California from 1986 to 1990 are reported. Thirteen facilities, selected because they housed all of the mammography units in three communities involved in a National Institutes of Health research project, had their units tested twice at an interval of 1 year. Fourteen self-selected units were also tested twice at intervals ranging from 1-3 years. Forty-three self-selected units in 31 additional facilities had testing only once. All 70 units underwent measurement of focal spot size or resolution, tube output, half-value layer (HVL), automatic exposure control (AEC) accuracy, relative kVp accuracy, mean glandular dose, and imaging of several test objects. The test results for the units tested once showed no significant differences compared to those tested twice. For the latter, once the units were tested and determined to be acceptable, retesting showed differences only in overall film optical density, dose, and AEC performance.

The fallen wire sign. An indicator of hip prosthetic loosening.

Trochanteric osteotomy is commonly performed during total hip arthroplasty. Subsequent fatigue fracture of the osteotomy wires, although common, usually has no clinical sequelae. In four cases, wire fragments migrated down the medullary cavity of the femur, in the space created by a loosened femoral component. This roentgenographic observation seems not to have been previously reported and is a definitive sign of femoral prosthesis loosening.

Mammography screen-film selection: individual facility testing technique.

Variations in tube output, film processing, and radiologist's preferences affect the screen-film combination that is appropriate for any particular mammographic facility. A technique to test a variety of screen-film combinations for screening mammography is described. Films are selected for testing because of their densitometric characteristics. Dose and clinical reliability are established with phantoms before the screen-film combinations are used to image consecutive patients having bilateral examinations. The mammograms selected for evaluation are those with similar optical density ranges, and which also may be compared to available previous mammograms or which have unusual mammographic findings. All radiologists reading mammograms at a facility independently score the selected cases. Scores of "unacceptable," "acceptable," or "outstanding" are assigned to four basic imaging characteristics: sharpness, contrast, visibility of skin line, and noise. Interobserver variations by this method require normalization, unlike ROC analysis which is not applicable for this data because of the absence of proved pathologic diagnoses. The testing of 5 films and two screens using 42 patient examinations required 2 h of time from each radiologist. It took 7 h of the physicist's time to pretest the 5 films, select the 42 acceptable examinations for testing by the radiologists, and summarize the data.

Case report 748: Chondroblastoma of the femur with an aneurysmal bone cyst.

A case of chondroblastoma associated with an aneurysmal bone cyst has been described. The radiographic appearance of the lesion understandably reflects the combined features of both tumors. Up to one-half of all cases of aneurysmal bone cysts are found in association with other tumors, benign or malignant, and up to 15% of chondroblastomas are combined with an aneurysmal bone cyst (4).