Percutaneous CT guided resection of osteoid osteoma of the tibial plafond.

Osteoid osteomas of the foot and ankle are relatively rare and notoriously difficult to diagnose. Juxta-articular osteoid osteomas are more difficult to treat and often have a significant delay in diagnosis. We report a case of a juxta-articular osteoid osteoma of the tibial plafond. Once the diagnosis was made, excisional biopsy was performed percutaneously under computed tomography (CT) guidance as an outpatient in the radiology suite. The patient had complete resolution of symptoms and remains pain free at two years follow-up. CT guided resection can be a lower morbidity and more cost effective technique to treat this lesion than traditional methods.

Imaging of infections and inflammatory conditions of the spine.

The lack of specific clinical, laboratory, and radiologic findings in patients with a disease as potentially debilitating as infectious spondylitis is challenging. Biopsy will frequently need to be performed but is itself often nondiagnostic and is not without risk. Therefore, identification of findings, often subtle, that strongly favor other entities in the differential may be of just as much clinical import as identifying findings worrisome for infection, particularly in the subset of patients who otherwise are felt unlikely to have a disc space infection. Radiography and magnetic resonance (MR) imaging are complementary imaging techniques and both should be performed. The pertinent vascular anatomy of the spine; the epidemiologic, microbiologic, and clinical features of infectious spondylitis; and the role of imaging are reviewed in this article. Particular emphasis is placed on imaging differentiation of the various discovertebral disease processes.

Selenium-based digital radiography versus conventional film-screen radiography of the hands and feet: a subjective comparison.

OBJECTIVE: The purpose of this study was to subjectively compare the visibility of normal anatomy of the hands and feet using selenium-based digital radiography versus conventional film-screen (100-speed) radiography. SUBJECTS AND METHODS: Digital and film-screen images of the hands and feet of 24 patients were obtained without an antiscatter grid using identical X-ray exposure. Each pair of images was evaluated independently by five experienced radiologists for visibility of normal anatomy using a six-point rating scale. Soft tissues, cortical bone, and trabeculae were evaluated. For each observer, "equivalence" was defined as a mean difference in image quality of less than 1 unit on the 0-5 scale used in the study. Paired t tests were also performed to determine whether the average visibility rating of one technique was statistically superior to that of the other at a .05 level of significance for each observer and at each anatomic landmark. RESULTS: In all categories, selenium-based digital images were rated equivalent to film-screen images by the five observers. Using the sum of the nine landmarks, four of the five observers rated the quality of selenium-based digital images superior to that of film-screen images. CONCLUSION: Subjective visibility of normal anatomy of the hands and feet using selenium-based digital radiography was similar to that achieved using conventional film-screen radiography.

The Bennett lesion of the shoulder.

In this article we review the imaging features and significance of the Bennett lesion of the shoulder. Standard radiographic, computed arthrotomographic, and MR findings in three baseball pitchers diagnosed with Bennett lesions of the shoulder are discussed. A crescent-shaped region of mineralization at the posteroinferior aspect of the glenoid rim, consistent with a Bennett lesion, arises at the insertion of the posterior joint capsule. The diagnosis of this lesion, typically in baseball pitchers, should raise suspicion for associated labral and rotator cuff abnormalities.

Osseous manifestations of SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome.

The SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome includes a complex group of disorders characterized by peculiar bone lesions, most commonly involving the anterior chest wall, and sometimes accompanied by dermatologic manifestations. The clinical and radiographic features of this syndrome are well described, but few studies have examined the histologic features of the bone lesions. We describe the clinical, radiographic, and histologic features of the osseous lesions encountered in eight patients with a clinical diagnosis of SAPHO syndrome. The patients included five female and three male patients ranging in age from 5 to 63 years (mean, 35.3 years). The most common clinical presentation was pain related to the sites of osseous involvement. Two patients also had some form of pustular dermatosis. The radiographic features of the osseous lesions varied but often suggested the possibility of a neoplasm. Nine pathologic specimens were available for review, five from the clavicle, two from the first rib, one from the calcaneus/cuboid, and one from the tibia. The histologic features varied but seemed related to the duration of the patients' musculoskeletal symptoms. Early lesions contained acute inflammation, edema, and prominent periosteal bone formation, histologically indistinguishable from ordinary bacterial osteomyelitis, whereas late lesions demonstrated markedly sclerotic bone trabeculae with prominent marrow fibrosis and only mild chronic inflammation; one of these biopsies appeared virtually identical to Paget's disease. One biopsy was performed after an intermediate duration of symptoms and contained prominent chronic inflammation only. The histologic findings in SAPHO are variable and nonspecific and may depend on the duration of disease, but it is important to recognize the spectrum of histologic changes possible in the syndrome and to realize that clinicopathologic correlation is necessary to avoid misdiagnosis and unnecessary long-term antibiotic therapy.

Acromial morphology: relation to sex, age, symmetry, and subacromial enthesophytes.

PURPOSE: To evaluate acromial shape in relation to age, sex, symmetry, and presence of subacromial enthesophytes. MATERIALS AND METHODS: Three hundred ninety-four cadaveric scapulas were reviewed. Specimens were categorized by sex and age (age range, 20-89 years). Acromial morphology was typed according to the Bigliani classification: type I, flat; type II, curved; and type III, hooked. The presence and degree of subacromial enthesopathy was recorded. Selective radiographic correlation was obtained. RESULTS: The relative percentages of acromial types I, II, and III were 22.8% (90 acromions), 68.5% (270 acromions), and 8.6% (34 acromions), respectively. There was a greater percentage of type III in men (10.2% [21 of 205] vs 6.9% [13 of 189] and type I in women (27.5% [52 of 189] vs 18.5% [38 of 205]). There was no relationship between acromial type and age (P = .667). Enthesophytes were most common in type III (20 [59%] of 34 acromions) versus type II (115 [42.6%] of 270 acromions) and type I (22 [24%] of 90 acromions). Acromial morphology was symmetric in 135 (70.7%) of 191 pairs of acromions and asymmetric in 56 pairs (29.3%). CONCLUSION: Acromial shape does not vary significantly with age. It does, however, differ between sexes. The relative percentages of the types differ from previously reported values. Acromial shape tends to be symmetric. A trend between acromial type and the presence of enthesophytes is observed.

Accuracy of fat-suppressed three-dimensional spoiled gradient-echo FLASH MR imaging in the detection of patellofemoral articular cartilage abnormalities.

PURPOSE: To determine the accuracy of T1-weighted fat-suppressed (FS) three-dimensional (3D) fast low-angle shot (FLASH) magnetic resonance (MR) imaging for the detection of articular cartilage abnormalities of the patellofemoral joint. MATERIALS AND METHODS: Forty-one patients with suspected internal derangement of the knee were examined with a T1-weighted FS 3D FLASH sequence and subsequently underwent arthroscopy. The patellofemoral articular cartilage was graded blindly on both the MR and arthroscopic images with a modification of the Noyes classification scheme. RESULTS: For the detection of abnormal articular cartilage of the patellofemoral joint with the FS 3D FLASH sequence, sensitivity was 81%, specificity was 97%, and accuracy was 97%. Of the lesions detected on MR images, 77% were graded identically on MR and arthroscopic images. For the remaining 23%, MR imaging and arthroscopic ratings were within one grade of each other. CONCLUSION: T1-weighted FS 3D FLASH imaging is accurate for the detection and grading of articular cartilage abnormalities of the patellofemoral joint.

Calculation and number processing: assessment battery; role of demographic factors.

This paper describes the structure and contents of EC301, a standardized testing battery for the evaluation of brain-damaged adults in the area of calculation and number processing. The battery was administered to 180 normal subjects stratified by education (3 levels), age (3) and gender. EC301 is composed of a large variety of tasks dealing with basic arithmetic skills, and their linguistic, spatial, and mnesic dimensions. The three main notational systems for numbers--Arabic digits, written verbal, and spoken verbal number forms--are explored. Analysis of error rates indicated the effect of some demographic factors (principally, education; incidentally, gender) on normal performance in some tasks.

Fast spin-echo imaging of the knee: factors influencing contrast.

Conventional T2-weighted spin-echo magnetic resonance imaging of the knee requires a long TR. Fast spin-echo (FSE) imaging can improve acquisition efficiency severalfold by collecting multiple lines of k space for each TR. Compromises in resolution, section coverage, and contrast inevitably result. The authors examined the compromises encountered in FSE imaging of the knee and discuss the variations in image contrast and resolution due to choices of sequence parameters. For short TR/TE knee imaging, FSE does not appear to offer any advantages, since the increased collection efficiency for one section reduces the available number of sections, so that the total imaging time for a given number of sections remains constant relative to conventional spin-echo imaging. For T2-weighted images, considerable time can be saved and comparable quality images can be obtained. This saved time can be usefully spent on increasing both the resolution of the image and its signal-to-noise ratio, while still reducing total acquisition time by a factor of two. The preferred FSE T2-weighted images were acquired with a TR of 4,500 msec, TE of 120 msec, and eight echoes. The available number of sections is compromised, and the sequence remains sensitive to flow artifacts; however, the FSE sequence appears to be promising for knee imaging.

Prospective study of osseous, articular, and meniscal lesions in recent anterior cruciate ligament tears by magnetic resonance imaging and arthroscopy.

Fifty-four patients with anterior cruciate ligament tears that were arthroscopically reconstructed within 3 months of initial injury were prospectively evaluated. Patients with grade 3 medial collateral ligament, lateral collateral ligament, or posterior cruciate ligament tears were excluded. Eighty percent of our patients had a bone bruise present on the magnetic resonance image, with 68% in the lateral femoral condyle. Two of the latter findings--an abnormal articular cartilage signal (P = 0.02) and a thin and impacted subchondral bone (P = 0.03)--had a significant relationship with injury to the overlying articular cartilage. Meniscal tears were found in 56% of the lateral menisci and 37% of the medial menisci. A significant association was present between bone bruising on the lateral femoral condyle and the lateral tibial plateau (P = 0.02). Results of our study support the concept that the common mechanism of injury to the anterior cruciate ligament involves severe anterior subluxation with impaction of the posterior tibia on the anterior femur. Determination of the significance of bone bruising, articular cartilage injury, or meniscal tears will require a long-term followup that includes evaluation for arthritis, stability, and function. These 54 patients represent the first cohort evaluated in this ongoing prospective clinical study.

Proactive interference in patients with amnesia resulting from anterior communicating artery aneurysm.

Diencephalic and temporal amnesics display an excessive sensitivity to proactive interference (PI) in memory tasks of the AB/AC kind. There exists considerable controversy about the nature of this sensitivity to PI. Moreover, it is an open question whether such sensitivity to PI is an obligatory feature of amnesia, or rather an incidental result of frontal damage often reported in amnesics. This question was reexamined by enrolling patients with an operated aneurysm of the anterior communicating artery (ACoA) and matched controls for an AB/AC learning task of two lists of 12 paired-associate words. It appeared that ACoA patients, like diencephalic and temporal amnesics, did indeed display a marked sensitivity to PI when compared to normals (Exp. I), even when performance of both groups in the learning of the first list was equated (Exp. II). The distribution of errors made in learning the second list, as well as the correlations between performance in learning the second list and a Stroop test, suggest that sensitivity to PI in ACoA amnesics could be the consequence of an inability to suppress irrelevant information at retrieval due to defective inhibitory attentional mechanisms. Complementary data collected in a small sample of Korsakoff's amnesic subjects are also described.

Medial malleolar stress fractures in seven patients: review of the clinical and imaging features.

Stress fractures of the medial malleolus were discovered in seven patients, five male and two female subjects aged 16-34 years. All except one were involved in running and jumping athletic activities. Gradual onset of pain over the medial malleolus occurred with repetitive activity. Focal intense increased uptake in the medial malleolus was present on bone scans. Conventional radiography and computed tomography demonstrated the presence of subtle fissures at the junction of the medial malleolus and the tibial plafond, and well-circumscribed lytic lesions were also seen in three patients. Two patients developed a complete fracture of the medial malleolus. Stress fractures of the medial malleolus should be suspected in patients involved in athletic and/or unusual activities who have experienced persistent and unexplained pain over the medial malleolus. Bone scans and radiographs should be obtained for diagnostic purposes in these patients.

Application of an artificial neural network in radiographic diagnosis.

The description of 44 cases of bone tumors was used by an artificial neural network to rank the likelihood of 55 possible pathologic diagnoses. The performance of the artificial neural network was compared with the performance of experienced (3 or more years of radiology training) residents and inexperienced (less than 1 year of radiology training) residents. The artificial neural network was trained using descriptions of 110 radiographs of bone tumors with known diagnoses. The descriptions of a separate set of 44 cases were used to test the neural network. The neural network ranked 55 possible pathologic diagnoses on a scale from 1 to 55. Experienced and inexperienced residents also ranked the possible diagnoses in the same 44 cases. Inexperienced residents had a significantly lower mean proportion of diagnoses ranked first or second than did the neural network. Experienced residents had a significantly higher proportion of correct diagnoses ranked first than did the network. Otherwise, a significant difference between the performance of the network and experienced or inexperienced residents was not identified. These results demonstrate that artificial neural networks can be trained to classify bone tumors. Whether neural network performance in classification of bone tumors can be made accurate enough to assist radiologists in clinical practice remains an open question. These preliminary results indicate that further investigation of this technology for interpretation assistance is warranted.

Segmentation of magnetic resonance images using an artificial neural network.

Signal intensities from intermediate and T2 weighted spin echo images of the brain were used as inputs into an artificial neural network (ANN). The signal intensities were used to train the network to recognize anatomically-important segments. The ANN was a self-organizing map (SOM) neural network which develops a continuous topographical map of the signal intensities within the two images. The neural network segmented images demonstrated good correlation with white matter, gray matter, and cerebral spinal fluid (CSF) spaces. This technique was rated better than manual thresholding of the intermediate images, but not as good as manual thresholding of the T2 weighted images.