Consistency of response and image recognition, pulmonary nodules.

OBJECTIVE: To investigate the effect of recognition of a previously encountered radiograph on consistency of response in localized pulmonary nodules. METHODS: 13 radiologists interpreted 40 radiographs each to locate pulmonary nodules. A few days later, they again interpreted 40 radiographs. Half of the images in the second set were new. We asked the radiologists whether each image had been in the first set. We used Fisher's exact test and Kruskal-Wallis test to evaluate the correlation between recognition of an image and consistency in its interpretation. We evaluated the data using all possible recognition levels-definitely, probably or possibly included vs definitely, probably or possibly not included by collapsing the recognition levels into two and by eliminating the "possibly included" and "possibly not included" scores. RESULTS: With all but one of six methods of looking at the data, there was no significant correlation between consistency in interpretation and recognition of the image. When the possibly included and possibly not included scores were eliminated, there was a borderline statistical significance (p = 0.04) with slightly greater consistency in interpretation of recognized than that of non-recognized images. CONCLUSION: We found no convincing evidence that radiologists' recognition of images in an observer performance study affects their interpretation on a second encounter. ADVANCES IN KNOWLEDGE: Conscious recognition of chest radiographs did not result in a greater degree of consistency in the tested interpretation than that in the interpretation of images that were not recognized.

On the choice of acceptance radius in free-response observer performance studies.

OBJECTIVES: Choosing an acceptance radius or proximity criterion is necessary to analyse free-response receiver operating characteristic (FROC) observer performance data. This is currently subjective, with little guidance in the literature about what is an appropriate acceptance radius. We evaluated varying acceptance radii in a nodule detection task in chest radiography and suggest guidelines for determining an acceptance radius. METHODS: 80 chest radiographs were chosen, half of which contained nodules. We determined each nodule's centre. 21 radiologists read the images. We created acceptance radii bins of <5 pixels, <10 pixels, <20 pixels and onwards up to <200 and 200+ pixels. We counted lesion localisations in each bin and visually compared marks with the borders of nodules. RESULTS: Most reader marks were tightly clustered around nodule centres, with tighter clustering for smaller than for larger nodules. At least 70% of readers' marks were placed within <10 pixels for small nodules, <20 pixels for medium nodules and <30 pixels for large nodules. Of 72 inspected marks that were less than 50 pixels from the centre of a nodule, only 1 fell outside the border of a nodule. CONCLUSION: The acceptance radius should be based on the larger nodule sizes. For our data, an acceptance radius of 50 pixels would have captured all but 2 reader marks within the borders of a nodule, while excluding only 1 true-positive mark. The choice of an acceptance radius for FROC analysis of observer performance studies should be based on the size of larger abnormalities.

Quantifying the clinical relevance of a laboratory observer performance paradigm.

OBJECTIVE: Laboratory observer performance measurements, receiver operating characteristic (ROC) and free-response ROC (FROC) differ from actual clinical interpretations in several respects, which could compromise their clinical relevance. The objective of this study was to develop a method for quantifying the clinical relevance of a laboratory paradigm and apply it to compare the ROC and FROC paradigms in a nodule detection task. METHODS: The original prospective interpretations of 80 digital chest radiographs were classified by the truth panel as correct (C=1) or incorrect (C=0), depending on correlation with additional imaging, and the average of C was interpreted as the clinical figure of merit. FROC data were acquired for 21 radiologists and ROC data were inferred using the highest ratings. The areas under the ROC and alternative FROC curves were used as laboratory figures of merit. Bootstrap analysis was conducted to estimate conventional agreement measures between laboratory and clinical figures of merit. Also computed was a pseudovalue-based image-level correctness measure of the laboratory interpretations, whose association with C as measured by the area (rAUC) under an appropriately defined relevance ROC curve, is as a measure of the clinical relevance of a laboratory paradigm. RESULTS: Low correlations (e.g. κ=0.244) and near chance level rAUC values (e.g. 0.598), attributable to differences between the clinical and laboratory paradigms, were observed. The absolute width of the confidence interval was 0.38 for the interparadigm differences of the conventional measures and 0.14 for the difference of the rAUCs. CONCLUSION: The rAUC measure was consistent with the traditional measures but was more sensitive to the differences in clinical relevance. A new relevance ROC method for quantifying the clinical relevance of a laboratory paradigm is proposed.

Migration of central lines from the superior vena cava to the azygous vein.

AIM: To report 11 cases of central venous access catheters migrating from the superior vena cava to the azygos vein in order to raise radiologists' awareness of this possibility. MATERIALS AND METHODS: This is a retrospective review of the clinical history and imaging of 11 patients whose central line migrated from the superior vena cava to the azygos vein. The time course of migration, access route of the catheters, outcome, and depth of placement in the superior vena cava were evaluated. RESULTS: All of these catheters were placed from the left; six through the subclavian vein, four as PICC lines, and one from the left internal jugular vein. Seven of the catheters were originally positioned in the superior vena cava. Four of the catheters were originally positioned in the azygos vein and were repositioned into the superior vena cava at the time of placement. The time to migration ranged from 2 to 126 days, average 43 days. In three cases, the migration was not reported at the first opportunity, resulting in a delay in diagnosis ranging from 10 to 27 days. All but one of the catheters extended at least 3.5 cm (range 1.8-7 cm) below the top of the right mainstem bronchus when in the superior vena cava. CONCLUSION: Risk factors for migration into the azygos vein include placement from a left-sided approach and original positioning in the azygos vein with correction at placement. The depth of placement in the superior vena cava was not a protective factor. It is important to recognize migration because of the elevated risk of complications when central lines are placed in the azygos vein.

Computed tomographic evaluation of calcaneal fractures.

Computed tomography (CT) can be a useful adjunct to conventional radiographs in the evaluation and treatment planning of comminuted calcaneal fractures. Either a combination of direct coronal and axial scan planes or a single set of oblique images may be used to study the calcaneus. CT can show the fracture planes, including the amount of displacement of fracture lines entering the posterior subtalar facet and the relationship of the sustentaculum tali to the remainder of the bone. Evaluation of the calcaneocuboid joint and any widening that has occurred due to the fracture is also easily accomplished with CT. CT should be interpreted in conjunction with the conventional radiographs as rotational components and flattening of the Böhler angle may be appreciated better on them than on CT.

Magnetic resonance imaging of the musculoskeletal system: part 7. The ankle.

Diagnosis of many traumatic or attritional lesions about the ankle may be difficult with only the history, physical examination, and conventional radiographs. When uncertainty is present clinically or when precise depiction of the extent of injury will assist with treatment planning, magnetic resonance imaging may be a useful adjunct to these basic methods of evaluation. In particular, magnetic resonance imaging is useful for the identification and evaluation of tendinitis, tendon dislocations, osteochondral lesions, and occult fractures. Additional clinical settings in which magnetic resonance imaging may be helpful include evaluation of tumors, osteomyelitis, and tarsal coalition.

Pelvic insufficiency fractures associated with radiation atrophy: clinical recognition and diagnostic evaluation.

Pelvic bone injuries are infrequent complications of radiotherapy. However, insufficiency fractures in irradiated pelvic bones may be underdetected, particularly in postmenopausal women. We describe the clinical presentation, radiologic evaluation, and course of disease in three patients with postradiation pelvic insufficiency fractures. Differential diagnosis included metastatic disease, tumor recurrence, and second malignancy. Recognition of radiographic features may prevent unnecessary, possibly morbid treatments.

Low-grade chondrosarcoma in a 12-year-old boy.

We present a case of a rare central chondrosarcoma in a 12-year-old boy and discuss its radiographic and magnetic resonance appearance.

Imaging of the total hip arthroplasty.

More than 75,000 total hip arthroplasties are done yearly in the United States. Although modern cementing techniques have improved the longevity of cemented implants, uncemented prostheses have become popular, especially in younger, more active patients. There is also a trend toward modular components. These mechanical devices will all ultimately fail if subjected to sufficient use and stresses over time, though the specific causes and modes of failure vary widely. Loosening remains the primary cause of implant failure. There is a growing awareness of the role of wear particles in periprosthetic bone resorption with or without loosening. Stress shielding, dislocation, periprosthetic and prosthetic fractures, infection, heterotopic ossification, and stress concentration are also frequently encountered clinical problems. Conventional radiographs are the mainstay in evaluating total hip arthroplasty, with computed tomography and nuclear medicine imaging playing smaller roles.

Categorization of acromial shape: interobserver variability with MR imaging and conventional radiography.

OBJECTIVE: Our purpose was to determine interobserver variability in the interpretation of the shape of the acromion on sagittal oblique MR images and conventional radiographs. The shape of the acromion was defined according to a previously described classification scheme. MATERIALS AND METHODS: We reviewed 26 sets of sagittal oblique MR images and corresponding conventional Y- or outlet-view radiographs of the shoulder. The shape of the acromion was graded for each study independently by four reviewers. Interobserver agreement was measured by using the kappa statistic. Analysis of variance and the chi 2-test were used for univariate analysis. RESULTS: The acromion was interpreted most often as being curved. The observers scored 9% of MR images and 28% of conventional radiographs as nondiagnostic (p < .001) (41% of transscapular Y views and 3% of supraspinatus outlet views were also considered nondiagnostic [p < .0001]). Kappa values were .23 for MR images and .43 for conventional radiographs. Variability in interpretation between techniques when controlled for observer was not statistically significant. CONCLUSION: Although sagittal oblique MR images were significantly more likely than conventional radiographs to be considered diagnostic by observers, interobserver agreement for MR examinations was poor. There was moderate agreement with conventional radiographs. This calls into question the usefulness of the previous system of interpretation and suggests that it might be more applicable with conventional radiographs than with MR images.

Radiographic findings of extremity tuberculosis in childhood: back to the future?

Since 1985, there has been an increase in the incidence of skeletal tuberculosis. Although this recent increase may prove to be temporary, familiarity with the protein manifestations of the disease is essential. The authors studied radiographs of 45 children in whom tuberculosis of the extremities had been diagnosed between 1937 and July 1991. Disease involved the hip in 18 cases; the knee in 17; the ankle in five; the shoulder in two; the midfoot in two; and the elbow, wrist, and hands in one each. Radiographic findings included joint effusion, periarticular osteopenia, joint space narrowing, cortical irregularity, lytic lesions, periosteal new bone formation, and advanced epiphyseal maturity. When the hip was involved, subluxation was a common finding. There is no single pathognomonic finding with which to make the diagnosis of skeletal tuberculosis. Clinical information may be helpful.

Magnetic resonance imaging of the postoperative shoulder.

The use of MR imaging in the evaluation of the postoperative shoulder and the findings indicative of postoperative pathology remain largely unexplored. MR imaging does seem to be diagnostic of complete rotator cuff tears following cuff repair. In all postoperative cases, a key to differentiating the expected from the pathologic is to be familiar with the procedure that was performed.

A simple and effective postangiographic femoral artery pressure dressing.

We describe a simple, inexpensive pressure dressing which supplements manual pressure and may be applied quickly and easily following femoral arterial puncture for angiography. This technique has been used on several thousand patients without complications.

World War II military led the way in screening chest radiography.

World War I recruits were screened for tuberculosis almost exclusively with a history and physical exam. Radiography was unavailable on a large scale and expensive. New techniques developed in Brazil and elsewhere in the 1930s made mass radiographic screening practical. During World War II, the U.S. Army and Navy took advantage of this new technology to screen an estimated 10 million personnel. This ambitious and successful case-finding program inspired, in part, continuing radiographic screening efforts among the civilian population following the war, including mass screening of asymptomatic individuals and routine hospital admission chest films.

An ectopic rim sign in hepatobiliary scintigraphy.

A 59-year-old man with gangrenous cholecystitis is presented along with an hepatobiliary scan that demonstrated nonvisualization of the gallbladder and a curvilinear area of increased activity in the region of the fissure for the ligamentum teres or common hepatic duct. There was no "rim sign" in the gallbladder fossa. We propose that perforation of the gallbladder and resultant pockets of pus may, through edematous compression of liver parenchyma, produce an ectopic rim sign if inflammation comes in contact with another portion of the liver.