A Bayesian network for diagnosis of primary bone tumors.

The authors developed a Bayesian network to differentiate among five benign and five malignant neoplasms of the appendicular skeleton using the patient's age and sex and 17 radiographic characteristics. In preliminary evaluation with physicians in training, the model identified the correct diagnosis in 19 cases (68%), and included the correct diagnosis among the two most probable diagnoses in 25 cases (89%). Bayesian networks can capture and apply knowledge of primary bone neoplasms. Further testing and refinement of the model are underway.

Hindfoot coronal alignment: a modified radiographic method.

Accurate clinical evaluation of the alignment of the calcaneus relative to the tibia in the coronal plane is essential in the evaluation and treatment of hindfoot pathologic condition. Previously described radiographic views of the foot and ankle do not demonstrate the true coronal alignment of the calcaneus relative to the tibia. Some of these views impose on the patient an unnatural posture that itself changes hindfoot alignment, whereas other methods distort the coronal alignment by the angle of the x-ray beam. Our purpose was to develop a modified radiographic view and measurement method for determining an angular measurement of hindfoot coronal alignment based on a cadaver study of the radiographic characteristics of the calcaneus and motion analysis of standing subjects. The view was obtained by having the subject stand on a piece of cardboard to create a foot template. The template was then positioned so that each foot was x-rayed perpendicular to the cassette while still maintaining the natural base of support. A method using multiple ellipses was developed to determine more accurately the coronal axis of the posterior calcaneus. A study using cadavers was performed in which radio-opaque markers were placed on multiple bony landmarks on the calcaneus. The tibia was held fixed in a vertical position, and the foot was x-rayed using the above techniques in different degrees of rotation without changing the relation of the calcaneus to the tibia. The radiographs of the modified Cobey and our view were examined to verify which markers were visible at different angles of rotation and how the hindfoot alignment measurements changed with foot rotation. To define further the differences between the views, an analysis of postural stability was conducted while the subjects were standing with the feet in the positions for imaging both the Buck modification of the Cobey view and our hindfoot alignment view. The combined results of the cadaver, radiographic measurement, and postural stability segments of the study reveal that this coronal hindfoot alignment view and measurement method is reproducible, more closely measures "true" coronal hindfoot alignment, and is more clinically applicable because the alignment is measured while the patient is standing with a normal angle and base of stance. The modified radiographic measurement method relies on posterior calcaneal anatomic landmarks, is less affected by rotation of the foot and ankle, and is reproducible between observers.

Detection of osteomyelitis in the neuropathic foot: nuclear medicine, MRI and conventional radiography.

The diagnostic efficacy of (1) combined three-phase bone scintigraphy and In-111 labeled WBC scintigraphy (Bone/WBC), (2) MRI, and (3) conventional radiography in detecting osteomyelitis of the neuropathic foot was compared. Conventional radiography was comparable to MRI for detection of osteomyelitis. MRI best depicted the presence of osteomyelitis in the forefoot. Particularly in the setting of Charcot joints, Bone/WBC was more specific than conventional radiography or MRI.

MR imaging of the abnormal sternoclavicular joint--a pictorial essay.

The sternoclavicular (SC) joint can be affected by a wide variety of pathologic conditions. Imaging is usually needed for diagnosis and staging. Although the use of magnetic resonance (MR) imaging has become indispensable in the evaluation of most joints, MR has received little attention in SC joint evaluation. Recently, however, it has been shown that detailed MR images of the normal SC joint can be obtained. This pictorial essay explores the differential diagnosis of the abnormal SC joint and helps to determine the role of MR imaging in the SC joint imaging algorithm.

Hemochromatosis-like arthropathy in diabetes mellitus without hemochromatosis.

We describe 3 patients with non-insulin-dependent diabetes mellitus who presented with hand pain and swollen joints. All 3 had radiographic changes in the affected joints typical of those associated with hemochromatosis. None of these patients had hemochromatosis. This is the first description of hemochromatosis-like arthropathy in diabetes mellitus without hemochromatosis.

MR imaging of the normal sternoclavicular joint: spectrum of findings.

Although MR imaging has become an important imaging method in the evaluation of most joints, it is rarely used to evaluate the sternoclavicular joint. The purpose of this study was to determine the spectrum of findings identified on MR images of the normal sternoclavicular joint as seen on images of cadavers, healthy volunteers, and patients with normal joints. Knowledge of these findings can prevent misdiagnosis of a normal variant as an abnormality.

Increased signal in the normal supraspinatus tendon on MR imaging: diagnostic pitfall caused by the magic-angle effect.

OBJECTIVE: Increased signal intensity within the distal portion of the supraspinatus tendon during MR imaging is a frequent observation even in healthy subjects. This finding has been variously attributed to the presence of fat, muscle, connective tissue, abnormal vascularity, or degenerative changes. More recently, the effect of tendon orientation in the static magnetic field (Bo) has been implicated. It has been shown that tendons at the magic angle of 55 degrees to Bo show markedly increased signal. This study was designed to determine the contribution of the magic-angle effect to the MR signal in the distal portion of the supraspinatus tendon. SUBJECTS AND METHODS: Five healthy volunteers were imaged in a 1.5-T unit using short TR/TE sequences in standard supine position; they were then reimaged laterally flexed at the waist to reorient the plane of the distal portion of the supraspinatus tendon by approximately 20 degrees relative to Bo. In the second part of the study, three cadaveric shoulders were similarly imaged, first in standard position and then reoriented approximately 35 degrees by simple rotation of the specimen. The supraspinatus tendon was evaluated in each subject by noting the length of the segment with increased signal and the position of this segment relative to the insertion of the tendon on the greater tuberosity. Comparisons were made for each live and cadaveric subject between neutral and rotated positions. RESULTS: Segments of increased signal changed in length and position for each live and cadaveric subject from the neutral to the reoriented position. CONCLUSION: Our study suggests that tendon orientation contributes significantly to the presence of increased signal within the supraspinatus tendon, as caused by the magic-angle effect. Failure to recognize this effect may lead to diagnostic inaccuracy when evaluating the rotator cuff on short TR/TE sequences.

MR imaging of the major carpal stabilizing ligaments: normal anatomy and clinical examples.

The integrity of the ligamentous network of the wrist is critical, as disruption of this network may result in carpal instability and pain. The extrinsic (radiocarpal) and intrinsic (intercarpal) ligaments that maintain carpal stability can be evaluated with magnetic resonance (MR) imaging. The major extrinsic ligaments are the radioscaphocapitate, radiolunotriquetral, short radiolunate, and dorsal radiocarpal ligaments. The scapholunate and lunotriquetral ligaments are the most important intrinsic ligaments and the primary wrist stabilizers. The most common causes of carpal instability are unstable fracture of the scaphoid, scapholunate dissociation, and lunotriquetral dissociation. Carpal instability can be diagnosed from the sagittal MR image that includes the capitate, lunate, and radius and from the sagittal MR image that includes the scaphoid and radius. Knowledge of the MR imaging appearances of the major carpal stabilizing ligaments and common patterns of carpal instability allows more precise diagnosis in cases of wrist pain.

Acute calcific periarthritis of the finger joints: a syndrome of women.

We describe a 33-year-old woman with acute calcific periarthritis (ACP) of the interphalangeal joint of the thumb and review 42 reported cases of ACP involving the finger joints. A computer assisted literature search for reported cases of ACP involving the finger joints was performed. Clinical features of our case and those fulfilling the criteria for entry into this study were analyzed.

MRI of injury to the lateral collateral ligamentous complex of the ankle.

We retrospectively evaluated the lateral collateral ligamentous complex of 43 patients who had complained of ankle pain following ankle sprain. The MR signs of ligamentous abnormality included discontinuity or absence, increased signal within the ligament, and ligamentous irregularity or waviness with normal thickness and signal intensity. Using these criteria, 30 anterior talofibular, 20 calcaneofibular, and no posterior talofibular ligament injuries were diagnosed. Compared with surgery (nine patients), MRI demonstrated six of seven anterior talofibular ligament injuries and six of six calcaneofibular ligament injuries. Magnetic resonance showed ligamentous abnormalities in 12 of 23 cases with normal stress radiography. Magnetic resonance imaging provides useful information for the evaluation of patients presenting with chronic pain after ankle sprain.

Monoarticular gout following trauma: MR appearance.

We report a case of gout with monoarticular tophaceous involvement of the proximal interphalangeal joint of the middle finger, emphasizing MR findings. To the best of our knowledge, the MR appearance of gout is not commonly known.

High-resolution bone scintigraphy of the adult wrist.

Bony anatomic landmarks of the wrist (e.g., pisiform, hook of hamate, radioulnar joint, and styloid processes of the radius and ulna) were routinely identified in 28 adult patients examined for wrist pain. With the wrists prone and immobilized, bone scintigrams were obtained for 500,000 counts with an asymmetric (133 to 161 keV) Tc-99m energy window and either a converging (best choice) or straight-bore, high-resolution collimator. High-resolution scintigraphy precisely localized degenerative joint disease (nine patients), scaphoid fractures (five), pisiform fracture (one), lunate avascular necrosis (one), radioulnar arthritis (one), septic or inflammatory arthritis (six), ulnocarpal impingement (two), and reflex sympathetic dystrophy syndrome (two). Images obtained palm down with the wrist in ulnar deviation helped identify increased uptake within the scaphoid. Fracture and significant bone or joint disease were excluded in one patient.

Long bicipital tendon of the shoulder: normal anatomy and pathologic findings on MR imaging.

The tendon of the long head of the biceps muscle (long bicipital tendon) has a complex course from its muscle belly to its insertion onto the supraglenoid tubercle/glenoid labrum. It is stabilized by numerous tendinous and ligamentous structures and is, in turn, partly responsible for maintenance of normal glenohumeral function. In this report we describe the anatomy of this tendon, correlating high-resolution MR images with cryomicrotome sections. We illustrate typical MR findings in pathologic conditions affecting the long bicipital tendon sheath, the substance of the tendon, and finally the tendon position.

Increased sacroiliac joint uptake after lumbar fusion and/or laminectomy.

Of 753 adult patients undergoing SPECT and planar bone scintigraphy for the evaluation of low back pain, 43 (6%) showed either unilateral or bilateral increased sacroiliac joint (SIJ) uptake. Five of the 58 abnormal joints were only identified with SPECT (9%), whereas 20 of the 58 abnormal joints were much more convincingly demonstrated by SPECT (34%). Fifteen of the 43 patients with increased SIJ uptake had undergone prior lumbar laminectomy and/or spinal fusion. Such spinal surgery can increase impact loading on the SIJ, leading to mechanical overload and sacroiliitis. Degenerative joint disease, trauma, or other benign pathology accounted for the remaining patients with increased SIJ uptake. The authors conclude that for patients with a history of lumbar spinal fusion and/or laminectomy, increased SIJ uptake usually is caused by altered spinal mechanics rather than malignancy or infection.

Interdigital (Morton) neuroma: high-resolution MR imaging with a solenoid coil.

Fifteen patients (17 feet) with symptoms suggestive of plantar interdigital neuroma underwent magnetic resonance (MR) imaging at 1.5 T with a solenoid forefoot coil with an 8-cm field of view. Surgery was subsequently performed on six feet. Fifteen interdigital masses were identified with MR imaging. Five of these, in feet that underwent surgery, were pathologically confirmed neuromas. In the remaining foot that underwent surgery, flexor tendon injury with probable inflammatory reaction was demonstrated with MR imaging but was interpreted as indeterminate for neuroma. No neuronal was identified at surgery, which otherwise confirmed the MR imaging findings. Neuromas were most conspicuous on T1-weighted images as foci of decreased signal intensity well demarcated from adjacent fat tissue. The lesions were poorly seen on T2-weighted images, where they appeared isointense or slightly hypointense to fat tissue in all cases. Prominent regions of increased signal intensity, presumably representing fluid in intermetatarsal bursae, were seen proximal to 10 of the 15 masses found with MR imaging.

Effect of tendon orientation on MR imaging signal intensity: a manifestation of the "magic angle" phenomenon.

To determine whether orientation in the static field may be responsible for the frequent occurrence of increased signal intensity within normal tendons at magnetic resonance (MR) imaging, seven healthy volunteers were imaged by means of a 1.5-T unit and standard clinical pulse sequences. The wrist, ankle, and shoulder regions were evaluated with local coils. Imaging was performed with tendon orientations ranging from 0 degree to 90 degrees in relation to the constant magnetic induction field (B0). Markedly increased intratendinous signal intensity was observed at the "magic angle" of 55 degrees, intermediate signal intensity was observed at 45 degrees and 65 degrees, and no signal intensity was observed at 0 degree and 90 degrees. Signal intensity was evident only when a short echo time was used. The authors believe that tendon orientation greatly affects tendon signal intensity in vivo. Increased signal intensity due to the magic angle effect may be misdiagnosed as tendinous degeneration, tendinitis, or frank tear.

Bone remodelling after growth factor and cyclosporine A therapy for aplastic anemia.

We describe a patient with viral induced aplastic anemia who developed severe bone pain after treatment with multiple courses of antithymocyte globulin, cyclosporine A, recombinant human granulocyte macrophage colony stimulating factor and deferoxamine. Radiographs and bone biopsy revealed extensive new trabecular bone formation in long bone diaphyses and adjacent periosteal reaction. The effects of hematopoietic growth factors, cyclosporine A and deferoxamine on bone metabolism are reviewed.