Anthony J. Wilson

Diagnostic performance of CT, MPR and 3DCT imaging in maxillofacial trauma

CT imaging of complex maxillofacial fractures is common practice now, but the relative diagnostic value of spiral computed tomography (CT), multiplanar reformations (MPR), and three-dimensional (3D) reconstructions in evaluating maxillofacial fractures is not established with independent validation of correct diagnosis. We studied these modalities and measured their diagnostic value in a carefully controlled observer based rated response experiment. Multiple fractures were created by blunt experimental trauma in nine adult cadaver heads (five males, four females). Spiral CT scans were performed on all specimens before (control) and after trauma. Axial slices (CT), sagittal and coronal multiplanar reconstructions (MPR), and 3D volumetric reconstructions views were generated. Truth was determined by defleshing the specimens and direct inspection of the traumatized skull. Three expert readers separately interpreted CT, MPR and 3D film hard copy images presented in random order blinded to patient identification or experimental conditions. We measured the time to diagnose each case as recorded by a monitor who was present while evaluations were performed. Twenty-eight facial regions were evaluated using rated response and free response illustrative formats. Each region was considered separately. Sensitivity and specificity were calculated to measure observer performance. We found that 3D and CT had a similar performance in fracture detection and both were markedly better than MPR. For free response illustrative data, CT correctly identified 10% more orbital fractures than 3D, and approximately 10% fewer zygomatic fractures. Fracture localization was best with 3D. Reader confidence was highest with CT, but assessment time was faster with 3D. We conclude that CT and 3D are comparable in detecting midfacial fractures and both are superior to MPR. 3D reconstructions are superior for localization of complex fractures involving multiple planes.

Quantitative analysis of the plain radiographic appearance of aneurysmal bone cysts.

RATIONAL AND OBJECTIVESTo quantitate radiographic features that distinguish the plain radiographic appearance of aneurysmal bone cyst (ABC) from other solitary lesions of bone. MATERIALS AND METHODS Seven hundred nine cases of focal bone lesions, including 32 ABCs were analyzed according to demographic, anatomic, and plain radiographic features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the appearance of ABC in contrast with other lesions in the data base. RESULTS Aneurysmal bone cysts most consistently are medullary-based, either eccentric or centric (94%), show lysis (100%), cortical thinning (97%), enlargement of the host bone (100%), and geographic bone destruction (94%). They have well-defined edges (84%), no fallen fragment (100%), no evidence of periosteal reaction (75%), and no visible matrix (91 %). Although they typically occur in the metadiaphysis of long bones, the anatomic location and demographic data did not significantly affect the sensitivity or specificity for detection of ABCs. The vector analysis-generated differential diagnoses include giant cell tumor, unicameral bone cyst, nonossifying fibroma, enchondroma, and fibrous dysplasia as the major lesions. CONCLUSIONS A relatively specific set of radiographic features can be defined, which will assist in the radiographic interpretation and improve on current textbook descriptions.

QUANTITATIVE ANALYSIS OF THE PLAIN RADIOGRAPHIC APPEARANCE OF BRODIE'S ABSCESS

RATIONALE AND OBJECTIVES The authors quantitate the radiographic features that distinguish the plain radiographic appearance of Brodies abscess (BA) from other solitary lesions of bone. METHODS Plain radiographs of 709 solitary bone lesions were reviewed, including 21 BAs. These were analyzed according to demographic, gross anatomic, and structural features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the radiographic appearance of BA relative to other lesions of bone. RESULTS Brodies abscesses, in our series, are most commonly medullary-based (86%) lytic lesions (100%), with a geographic pattern of destruction (100%), well-defined edges (90%), marginal sclerosis (86%), and no bone enlargement (95%). In general, they have no periosteal reaction (71%), cortical break (95%), or visible matrix (90%). They typically are localized to the diaphysis or metaphysis (86%) of tubular bones, particularly in the lower extremity (63%). By vector analysis, the radiographic and demographic description of BA that provided the greatest sensitivity (67%-76%) while maintaining high prevalence (20%-21%) included a well-defined lytic lesion with a geographic pattern of destruction, and no bone enlargement or matrix or cortical break arising in patients younger than 40 years old. Although BAs commonly are small lesions with maximum diameters < 50 mm, size criteria did not greatly affect the sensitivity or specificity for detection of BA in our database. The differential diagnosis generated by vector analysis includes osteoid osteoma, nonossifying fibroma, giant cell tumor, eosinophilic granuloma chondroblastoma, and fibrous dysplasia, as the major lesions. CONCLUSIONS Although BA can present with a variety of radiographic features, a relatively specific set of radiographic characteristics can be defined to assist in plain-film diagnosis and to help refine the differential diagnosis of similar-appearing lesions.

Computer-based videotape analysis of trauma resuscitations for quality assurance and clinical research.

PURPOSE To automate time (and motion) studies of major trauma resuscitations. TECHNIQUES We modified an existing time-motion study technique based on time-encoded videotaping for medical imaging workstation human factors analysis. Videotapes were recorded of the trauma room during normal clinical activity using an unobtrusive mounted camera. The videotapes are displayed through a customized interface using a Macintosh-based display system. Within this platform, the time-motion study module allows flexible task definition, multiple concordant task assignment, and various summary result presentations. We established an expert panel of two traumatologists, two emergency radiologists, and two time-motion study experts. The expert panel prospectively and uniquely defined important recognizable procedural and cognitive tasks and personnel (MD, RN, EMT, RT, etc.) involved in trauma resuscitation based on pilot recordings and collective experience. These task functions were used to define a menu in the time-motion analysis software. During retrospective videotape review, the beginning and ending times of each task performed were recorded by electronically highlighting each defined individual and task. The summary results can be displayed in list, tabular, or graphic form by individuals, personnel classifications, or tasks.

Diagnosis of Focal Bone Lesions Using Neural Networks

RATIONALE AND OBJECTIVES.Use of a neural network to diagnose focal lesions of bone was evaluated. METHODS.Imaging features of 709 lesions were encoded into a predetermined database. Data were divided into four groups and were analyzed using cross-validation by a two-layer feedforward neural network. RESULTS.The lesions comprised 43 different pathologic diagnoses. Overall, the network was 85% accurate in distinguishing benign from malignant lesions. With a differential list of five diagnoses, the list was internally consistent regarding benign and malignant lesions 81.9% of the time. The network correctly diagnosed 56% of the lesions by pathologic diagnosis as its first choice. It included the correct diagnosis 71.8% of the time in a differential list of three diagnoses and 87.3% of the time in a differential list of nine diagnoses. CONCLUSION.Although not yet adequate for clinical use, neural network diagnosis of bone lesions is in its infancy and has important implications for the future analysis of focal bone lesions.

Imaging the hand and wrist

This article reviews many of the most commonly used modalities for imaging the hand and wrist. Particular attention is paid to proper radiographic positioning, with emphasis on the four-view wrist series. Standard wrist measurements are detailed, and wrist arthrography is also discussed. Techniques for cross-sectional imaging, computed tomography, and MR imaging are reviewed, and several examples are presented as to where MR imaging is diagnostically valuable.

Quantitative analysis of the plain radiographic appearance of eosinophilic granuloma.

RATIONALE AND OBJECTIVESTo quantitate features that distinguish the plain radiographic appearance of eosinophilic granuloma (EG) from other solitary lesions of bone. MATERIALS AND METHODSSeven hundred nine focal bone lesions, including 26 EGs, were analyzed according to demographic, anatomic, and plain radiographic features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the appearance of EG in contrast to other lesions in the data base. RESULTSThe radiographic appearance of EGs was most consistently that of a medullary based lytic lesion (100%) with geographic destruction (76.9%), lobular contour (73.1%), and well-defined edges (73.1%). Long bone lesions showed these features more frequently than EGs in other locations. Periosteal reaction was visible in all long bone lesions but in only one nonlong bone lesion (5.9%). Characterization of EG in long bones as a lytic, medullary-based metaphyseal or diaphyseal lesion with geographic destruction, lobular contours, periosteal reaction, no matrix, and no subarticular extension showed a sensitivity of 55.6% of EG and prevalence of 22.7%. The vector analysis-generated differential diagnoses include unicameral bone cyst, aneurysmal bone cyst, giant cell tumor, Brodies abscess, enchondroma, chondrosarcoma, and malignant fibrous histiocytoma. CONCLUSIONSThe radiographic appearance of EG is relatively nonspecific but, using vector analysis, can be better elucidated than in current textbook descriptions.

QUANTITATIVE ANALYSIS OF THE PLAIN RADIOGRAPHIC APPEARANCE OF EWING'S SARCOMA OF BONE

RATIONALE AND OBJECTIVES The authors quantitate the radiographic features that distinguish the plain radiographic appearance of Ewings sarcoma (ES) from other solitary lesions of bone. METHODS A total of 709 cases of focal bone lesions, including 44 ES, were analyzed according to demographic, anatomic, and plain radiographic features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the appearance of ES in contrast with other lesions in the database. RESULTS In our sample, Ewings sarcoma is most consistently a medullary-based (91%) lytic (89%) lesion with at least a partially permeative appearance (82%), poorly defined edges (82%), no margination (91%), and a soft-tissue mass (61%). When these lesions occur in long bones, they most commonly are found in the diaphysis (75%) and are proximal more often than distal. Vector analysis suggests that any primary bone lesion without radiographically visible matrix and with either a soft-tissue mass, an appearance of permeative destruction alone or in combination with other patterns of bone destruction is suspect for the diagnosis. This small subset of common features appears to have a high sensitivity (89%) and prevalence (47%) of ES among the lesions meeting these criteria. Limiting the age of the patients to progressively younger age groups increases the specificity but lowers sensitivity. The vector analysis-generated differential diagnoses includes osteosarcoma, giant-cell tumor, lymphoma, and chondrosarcoma. CONCLUSIONS A relatively specific set of radiographic features can be defined, which will assist in the radiographic diagnosis of ES and improve upon current textbook descriptions.

Quantitative analysis of solitary lesions of bone.

RATIONALE AND OBJECTIVES To quantitate the radiographic features of common solitary lesions of bone using vector analysis to optimize their radiographic description. METHODS Plain radiographs of 709 solitary bone lesions were reviewed. Relevant demographic, anatomic, and structural data were cataloged. These data were used to approximate the vector space defined by all possible solitary lesions of bone. Vector space analysis on the entire set of lesions was performed to determine similarities among and between lesion types. RESULTS The 709 lesions generated 614 separate vectors within the appearance vector space. Only 10 vectors were represented more than 3 times, indicating great variability among and between most lesion types. Osteochondromas (with two vectors repeated 10 and 15 times, respectively) and peripheral chondrosarcomas (with one vector repeated 5 times) were relatively uniform in appearance. Gender bias was present for multiple types of lesions. Larger lesions that involved more than one anatomic center were more likely to be malignant. Lesions occurring in the femoral diaphysis and pelvic flat bones were statistically more likely to be malignant. CONCLUSIONS Analysis shows that most lesions have highly varied vectors in the appearances within the vector space. More in-depth analysis of each lesion type using this quantitative technique is required to better define individual lesion subspaces and hence their radiographic appearances with respect to other bone lesions.

Results of the 1993 survey of the American Association of Academic Chief Residents in Radiology

RATIONALE AND OBJECTIVES A survey of chief residents of academic radiology programs is conducted annually on behalf of the American Association of Academic Chief Residents in Radiology (A3CR2). Data are obtained to improve the training of diagnostic radiology residents and to increase the understanding of radiologists and their associates about issues of interest to radiologists in training. METHODS Questionnaires were mailed to 133 accredited programs in the United States and Canada. A wide variety of demographic and common interest questions were asked. The analysis took into account geographic location of the responders and the size of the residency program. Comparisons were made to the data from prior years. RESULTS Completed surveys from 93 programs (70%) were returned. The percentage of women residents is increasing. Important regional and size variations exist in several areas including salary, workload, prior clinical training, resident/fellow ratios, post residency plans, and call schedules. Although many chief residents feel knowledgeable about the health care system, opinions about the future of radiology and medical care are tentative. CONCLUSIONS This survey provides important demographic information about academic radiology residency programs. The summary information regarding plans for fellowship training, resident call schedules, and opinions about socioeconomic issues may be useful for chief residents, program directors, and departmental chairmen.