Soft-copy mammographic readings with different computer-assisted detection cuing environments: preliminary findings.

PURPOSE: To assess the performance of radiologists in the detection of masses and microcalcification clusters on digitized mammograms by using different computer-assisted detection (CAD) cuing environments. MATERIALS AND METHODS: Two hundred nine digitized mammograms depicting 57 verified masses and 38 microcalcification clusters in 85 positive and 35 negative cases were interpreted independently by seven radiologists using five display modes. Except for the first mode, for which no CAD results were provided, suspicious regions identified with a CAD scheme were cued in all the other modes by using a combination of two cuing sensitivities (90% and 50%) and two false-positive rates (0.5 and 2.0 per image). A receiver operating characteristic study was performed by using soft-copy images. RESULTS: CAD cuing at 90% sensitivity and a rate of 0.5 false-positive region per image improved observer performance levels significantly (P < .01). As accuracy of CAD cuing decreased so did observer performances (P < .01). Cuing specificity affected mass detection more significantly, while cuing sensitivity affected detection of microcalcification clusters more significantly (P < .01). Reduction of cuing sensitivity and specificity significantly increased false-negative rates in noncued areas (P < .05). Trends were consistent for all observers. CONCLUSION: CAD systems have the potential to significantly improve diagnostic performance in mammography. However, poorly performing schemes could adversely affect observer performance in both cued and noncued areas.

Effect of early or delayed insertion of tympanostomy tubes for persistent otitis media on developmental outcomes at the age of three years.

BACKGROUND: A main indication for the insertion of tympanostomy tubes in infants and young children is persistent otitis media with effusion, reflecting concern that this condition may cause lasting impairments of speech, language, cognitive, and psychosocial development. However, evidence of such relations is inconclusive, and evidence is lacking that the insertion of tympanostomy tubes prevents developmental impairment. METHODS: We enrolled 6350 healthy infants from 2 to 61 days of age and evaluated them regularly for middle-ear effusion. Before the age of three years 429 children with persistent effusion were randomly assigned to have tympanostomy tubes inserted either as soon as possible or up to nine months later if effusion persisted. In 402 of these children we assessed speech, language, cognition, and psychosocial development at the age of three years. RESULTS: By the age of three years, 169 children in the early-treatment group (82 percent) and 66 children in the late-treatment group (34 percent) had received tympanostomy tubes. There were no significant differences between the early-treatment group and the late-treatment group at the age of three years in the mean (+/-SD) scores on the Number of Different Words test, a measure of word diversity (124+/-32 and 126+/-30, respectively); the Percentage of Consonants Correct-Revised test, a measure of speech-sound production (85+/-7 vs. 86+/-7); the General Cognitive Index of McCarthy Scales of Children's Abilities (99+/-14 vs. 101+/-13); or on measures of receptive language, sentence length, grammatical complexity, parent-child stress, and behavior. CONCLUSIONS: In children younger than three years of age who have persistent otitis media, prompt insertion of tympanostomy tubes does not measurably improve developmental outcomes at the age of three years.

Statistical test to assess rank-order imaging studies.

RATIONALE AND OBJECTIVES: Rank-order experiments often provide a reasonable method of determining whether a large-scale receiver operating characteristic study can be justified. The authors' purpose was to formalize a proposed method for analyzing rank-order imaging experiments and provide methods that can be used in determining sample sizes for both cases and raters. MATERIALS AND METHODS: Simulations were conducted to determine the adequacy of the normal approximation of a statistic used to test the null hypothesis of random ordering. For a multireader experiment, formulas are presented and guidelines are provided to enable investigators to determine the number of required readers (raters) and cases for a specific study. RESULTS: When there are at least five ordered images per case, 10 cases are sufficient to test a random rank order. When there are only three or four images for a case, 20 cases are required. The authors constructed tables of statistical power for selected numbers of ordered images, numbers of cases, and degrees of trend, and they also provide an approximation for use in situations that are not tabled. CONCLUSION: The statistical methods for analyzing rank-order experiments and estimating sample sizes for study planning are relatively simple to implement. The derived formulas for sample size estimation, when applied to typical imaging experiments, indicate that modest numbers of cases and readers are required for rank-order studies.

Past history of otitis media and balance in four-year-old children.

OBJECTIVES/HYPOTHESIS: To obtain normative data for a population of children 4 years of age with respect to standard vestibular and balance test protocols and to determine, in the absence of concurrent middle ear effusion (MEE), the possible changes caused by a history of recurrent or persistent MEE. STUDY DESIGN: Comparative studies of the results of vestibular and balance tests in a cohort of young children with and without a history of MEE. METHODS: Seventy-one children, 4 years of age, with a well-documented history since early infancy regarding the presence or absence of MEE were evaluated using pneumatic otoscopy, tympanometry, audiometry, and vestibular and balance (rotational and moving platform posturography) tests. For the results of the vestibular and balance tests, comparisons were made between the group of 31 children (43.7%) without and the group of 40 children (56.3%) with a history of recurrent or persistent MEE, when a positive disease history was defined as at least a 10% cumulative percentage of time with MEE between early infancy and time of testing. RESULTS: When compared with children with a negative history of significant MEE, children with a positive history had a lower average gain to a rotational stimulus of 0.1 Hz, 150 degrees/s (0.57 vs. 0.44; P = .007). There were no significant differences between groups with respect to other measures. CONCLUSIONS: These results suggest that a history of recurrent or persistent MEE affects the vestibular and/or balance function of 4-year-old children when tested in the absence of a concurrent episode of MEE. The possible sequelae of the disease should be weighed in future considerations of early intervention for MEE.

Language, speech sound production, and cognition in three-year-old children in relation to otitis media in their first three years of life.

OBJECTIVE: As part of a prospective study of possible effects of early-life otitis media on speech, language, cognitive, and psychosocial development, we tested relationships between children's cumulative duration of middle ear effusion (MEE) in their first 3 years of life and their scores on measures of language, speech sound production, and cognition at 3 years of age. METHODS: We enrolled 6350 healthy infants by 2 months of age who presented for primary care at 1 of 2 urban hospitals or 1 of 2 small town/rural and 4 suburban private pediatric practices. We intensively monitored the children's middle ear status by pneumatic otoscopy, supplemented by tympanometry, throughout their first 3 years of life; we monitored the validity of the otoscopic observations on an ongoing basis; and we treated children for otitis media according to specified guidelines. Children who met specified minimum criteria regarding the persistence of MEE became eligible for a clinical trial in which they were assigned randomly to undergo tympanostomy tube placement either promptly or after a defined extended period if MEE remained present. From among those remaining, we selected randomly, within sociodemographic strata, a sample of 241 children who represented a spectrum of MEE experience from having no MEE to having MEE whose cumulative duration fell just short of meeting randomization criteria. In subjects so selected, the estimated duration of MEE ranged from none to 65.6% of the first year of life and 44.8% of the first 3 years of life. In these 241 children we assessed language development, speech sound production, and cognition at 3 years of age, using both formal tests and conversational samples. RESULTS: We found weak to moderate, statistically significant negative correlations between children's cumulative durations of MEE in their first year of life or in age periods that included their first year of life, and their scores on formal tests of receptive vocabulary and verbal aspects of cognition at 3 years of age. However, the percent of variance in these scores explained by time with MEE in the first year of life beyond that explained by sociodemographic variables ranged only from 1.2% to 2.9%, and the negative correlations were concentrated in the subgroup of children whose families had private health insurance (rather than Medicaid). We found no significant correlations in the study population as a whole or in any subgroup between time with MEE during antecedent periods and children's scores on measures of spontaneous expressive language, speech sound production, or other measured aspects of cognition. In contrast, by wide margins, scores on all measures were consistently highest among the most socioeconomically advantaged children and lowest among the most socioeconomically disadvantaged children. CONCLUSIONS: Our findings suggest either that persistent early-life MEE actually causes later small, circumscribed impairments of receptive language and verbal aspects of cognition in certain groups of children or that unidentified, confounding factors predispose children both to early-life otitis media and to certain types of developmental impairment. Findings in the randomized clinical trial component of the larger study should help distinguish between causality and confounding as explanations for our findings.language, speech, cognition, development, otitis media, middle ear effusion.

Effects of luminance and resolution on observer performance with chest radiographs.

PURPOSE: To examine the combined effects of image resolution and display luminance on observer performance for detection of abnormalities depicted on posteroanterior chest radiographs. MATERIALS AND METHODS: A total of 529 radiographs were displayed on a specially constructed view box at three luminance levels (770, 260, and 85 cd/m(2)) and three resolutions (100-microm, 200-microm, and 400-microm pixels). Each image was reviewed nine times by six radiologists who participated in this study. The abnormalities included nodule, pneumothorax, interstitial disease, alveolar infiltrates, and rib fracture. Negative (normal) radiographs were also included. RESULTS: Receiver operating characteristic curves indicated that the effect of image luminance was greater than that of resolution. The detection of pneumothorax, interstitial disease, and rib fracture showed statistically significant differences (P <. 05) due to luminance. The detection of pneumothorax was the only abnormality with a statistically significant difference due to resolution. There was no evidence that luminance was related to image resolution for any of the abnormalities. CONCLUSION: At a resolution of 400-microm pixels or higher across the field of view and a luminance of 260 cd/m(2) or more, primary diagnosis with posteroanterior chest radiographs is not likely to be affected by the quality of display.

The heritability of otitis media: a twin and triplet study.

CONTEXT: Anatomical, physiological, and epidemiological data indicate that there may be a significant genetic component to prolonged time with and recurrent episodes of otitis media in children. OBJECTIVE: To determine the genetic component of time with and episodes of middle ear effusion and acute otitis media (AOM) during the first 2 years of life. DESIGN: Prospective twin and triplet cohort study with enrollment from 1982 through 1995. SETTING: Otitis Media Research Center in the ear, nose, and throat clinic of Children's Hospital of Pittsburgh, Pittsburgh, Pa. PATIENTS: A total of 168 healthy same-sex twin and 7 triplet sets were recruited within the first 2 months of life; zygosity results were available for 140 sets; 138 (99%) of these were followed up for 1 year and 126 (90%) for 2 years. MAIN OUTCOME MEASURES: Proportion of time with middle ear effusion, episodes of middle ear effusion, and episodes of AOM by zygosity status. RESULTS: At the 2-year end point, the estimate of heritability of time with middle ear effusion was 0.73 (P<.001). The estimates of discordance for 3 or more episodes of middle ear effusion were 0.04 for monozygotic twins and 0.37 for dizygotic twins (P = .01). The estimate of discordance of an episode of AOM in monozygotic twins was 0.04 compared with 0.49 in dizygotic twins (P = .005). CONCLUSIONS: Our study suggests there is a strong genetic component to the amount of time with middle ear effusion and episodes of middle ear effusion and AOM in children.

Parental stress and parent-rated child behavior in relation to otitis media in the first three years of life.

OBJECTIVE: As part of a long-term study of possible effects of early-life otitis media on speech, language, cognitive, and psychosocial development, we tested relationships between parents' ratings of parent-child stress at ages 1, 2, and 3 years, and of their children's behavior problems at ages 2 and 3 years, and the children's cumulative duration of middle-ear effusion (MEE) in their first 3 years of life. METHODS: We enrolled healthy infants by age 2 months who presented for primary care at 1 of 2 urban hospitals or 1 of 2 small-town/rural and 4 suburban private pediatric practices. We obtained standardized baseline measures of parental stress; we intensively monitored the children's middle-ear status by pneumatic otoscopy, supplemented by tympanometry, throughout their first 3 years of life; we monitored the validity of the otoscopic observations on an ongoing basis; and we treated children for otitis media according to specified guidelines. We obtained parent ratings of parental stress using the Parenting Stress Index/Short Form when the children reached ages 1, 2, and 3 years, and parent ratings of children's behavior using the Child Behavior Checklist when the children reached ages 2 and 3 years. RESULTS: In 2278 children we found no substantial relationships between parents' ratings of parent-child stress when the children reached ages 1, 2, and 3 years, or of their children's behavior problems at ages 2 and 3 years, and the cumulative duration of the children's MEE during antecedent periods. On the other hand, ratings both of parent-child stress and of behavior problems were consistently highest among the most socioeconomically disadvantaged children and lowest among the most socioeconomically advantaged children. Ratings also tended to be highest among children whose parents' baseline stress scores were highest. CONCLUSIONS: Parent-child stress and children's behavior problems in the first 3 years of life, as rated by parents, bear little or no relationship to the children's previous cumulative duration of MEE.

Adenoidectomy and adenotonsillectomy for recurrent acute otitis media: parallel randomized clinical trials in children not previously treated with tympanostomy tubes.

CONTEXT: Adenoidectomy and adenotonsillectomy are commonly performed in US children to reduce the occurrence of persistent or recurrent otitis media, but evidence supporting the efficacy of the operations is limited. OBJECTIVES: To test the efficacy of adenoidectomy and adenotonsillectomy in children with persistent or recurrent otitis media who had not previously undergone tube placement and to compare the relative efficacy of adenoidectomy alone vs adenotonsillectomy in such children. DESIGN: Two parallel randomized clinical trials. SETTING AND PARTICIPANTS: A total of 461 children aged 3 to 15 years were enrolled at Children's Hospital of Pittsburgh, Pa, between April 1980 and April 1994. Four hundred ten children were observed for up to 3 years. INTERVENTIONS: Children without recurrent throat infection or tonsillar hypertrophy (304 enrolled; 266 followed up) were randomized to either an adenoidectomy, adenotonsillectomy, or control group; children who had such conditions (157 enrolled; 144 followed up) were randomized to an adenotonsillectomy or control group. MAIN OUTCOME MEASURES: Occurrence rate of episodes of acute otitis media by treatment group and estimated proportion of time with otitis media. RESULTS: In both trials, most subjects were eligible because of recurrent acute otitis media, with or without persistent otitis media with effusion. A total of 47 children assigned to surgical treatment groups had no surgery. The efficacy of surgery in both trials was modest and limited mainly to the first follow-up year. The largest differences in that year were found in the 3-way trial between the adenotonsillectomy group and the control group: mean annual rate of episodes of acute otitis media, 1.4 vs 2.1 (P<.001); and mean estimated percentage of time with otitis media, 18.6% vs 29.9% (difference, 11.3%; 95% confidence interval, 4.4%-18.2%; P=.002). Perioperative and postoperative complications or other adverse events occurred not infrequently, especially among subjects undergoing adenotonsillectomy (14.6%). CONCLUSIONS: Our study showed limited and short-term efficacy of both adenoidectomy and adenotonsillectomy; given the risks, morbidity, and costs of these procedures, these data suggest that neither operation should ordinarily be considered as a first surgical intervention in children whose only indication is recurrent acute otitis media.

Observer sensitivity to small differences: a multipoint rank-order experiment.

OBJECTIVE: To evaluate observer sensitivity to small differences in image presentation, a multipoint rank-order experiment was used to identify small differences or trends in observations. MATERIALS AND METHODS: Ten observers were presented with 50 sets of breast images that had been compressed at five different levels. Each set contained six images ranging from noncompressed to approximately 101:1 compression. Observers were asked to review all images of a case side by side and rank order the quality of each to enable determination of the presence or absence of masses and clustered microcalcifications. RESULTS: As a group, observers were able to detect small differences among the images, even at the lower compression levels (p < .001). As compression levels and image degradation increased, the ability to identify differences between different modes also increased. Large observer variability in discrimination ability was observed. CONCLUSION: Multipoint rank ordering of images viewed side by side can be an efficient method to identify small differences in image presentation. This approach to image ranking could be used to rule out or confirm the need for objective observer performance-type studies.

Empiric assessment of parameters that affect the design of multireader receiver operating characteristic studies.

RATIONALE AND OBJECTIVES: The authors attempted to assess experimentally the magnitude of reader variability and the correlations and interactions among cases, readers, and modalities during observer performance studies and their possible effects on study design and sample size. MATERIALS AND METHODS: Published data from 32 selected receiver operating characteristic (ROC) studies were reviewed to compare the magnitude of the variance component from readers with the variance component from modality. Estimates of correlation and interactions among cases, readers, and modalities were also computed directly from ROC data ascertained during two large studies performed in our laboratory. Each of these two studies included 529 cases and six readers, but one study used eight modalities and the other nine. RESULTS: Published results indicate that reader variability is task dependent and larger (P < .05) than modality variability in detection of interstitial disease. Measured correlations between modalities for the same reader were task dependent and ranged from 0.35 to 0.59. Modality-by-reader and modality-by-case interactions often are not important factors. The random error term was greater than the modality-by-reader interaction in 11 of 20 comparisons and greater than the modality-by-case interaction in eight of 20 comparisons. CONCLUSION: Use of the same cases interpreted with different modes is justifiable in many situations because of the high variability from readers. This comprehensive review of existing ROC studies resulted in parameter assessments that can be used to better estimate sample-size requirements in multireader ROC studies.

Selection of subtle cases for observer-performance studies: the importance of knowing the true diagnosis.

RATIONALE AND OBJECTIVES: To assess the usefulness of classifying degree of difficulty in abnormality detection and to determine the effect of knowing the true diagnosis when selecting subtle images for observer-performance studies. MATERIALS AND METHODS: A total of 529 posteroanterior chest images that had been used in a multiabnormality, multireader observer-performance study were rated by three observers as to the difficulty of determining the presence or absence of each abnormality when the true diagnosis was known and when it was not known. Changes in image subtlety ratings were evaluated, and actual observer-performance results for the different groups of images grouped according to raters' classifications with and without availability of the true diagnosis were compared. RESULTS: The majority of negative cases (9,168 of 12,258, 74.8%) were rated as "easy" to determine. Substantial changes were made during the selection of the "subtle" case category when the truth was known compared with when the truth was not provided. These changes caused differences between typical and subtle cases in terms of observer performance. Combined ratings of case subtlety by agreement of multiple classifiers resulted in a well-ordered selection with decreasing observer performance as a function of subtlety ratings. CONCLUSION: Cases for observer-performance studies that stress the diagnostic system can be successfully selected in the multiple-disease setting by experienced readers and should be selected with the truth known to the raters. The degree of agreement by multiple raters can be used to refine subtlety ratings.

Forced choice and ordinal discrete rating assessment of image quality: a comparison.

This study compared a five-category ordinal scale and a two-alternative forced-choice subjective rating of image quality preferences in a multiabnormality environment. 140 pairs of laser-printed posteroanterior (PA) chest images were evaluated twice by three radiologists who were asked to select during a side-by-side review which image in each pair was the "better" one for the determination of the presence or absence of specific abnormalities. Each pair included one image (the digitized film at 100 microns pixel resolution and laser printed onto film) and a highly compressed (approximately 60:1) and decompressed version of the digitized film that was laser printed onto film. Ratings were performed once with a five-category ordinal scale and once with a two-alternative forced-choice scale. The selection process was significantly affected by the rating scale used. The "comparable" or "equivalent for diagnosis "category was used in 88.5% of the ratings with the ordinal scale. When using the two-alternative forced-choice approach, noncompressed images were selected 66.8% of the time as being the "better" images. This resulted in a significantly lower ability to detect small differences in perceived image quality between the noncompressed and compressed images when the ordinal rating scale is used. Observer behavior can be affected by the type of question asked and the rating scale used. Observers are highly sensitive to small differences in image presentation during a side-by-side review.

Otitis media in 2253 Pittsburgh-area infants: prevalence and risk factors during the first two years of life.

OBJECTIVE: As part of a long-term study of possible effects of early-life otitis media on speech, language, cognitive, and psychosocial development, we set out to delineate the occurrence and course of otitis media during the first 2 years of life in a sociodemographically diverse population of infants, and to identify related risk factors. METHODS: We enrolled healthy infants by age 2 months who presented for primary care at one of two urban hospitals or one of two small town/rural and four suburban private pediatric practices. We intensively monitored the infants' middle-ear status by pneumatic otoscopy, supplemented by tympanometry, throughout their first 2 years of life; we monitored the validity of the otoscopic observations on an ongoing basis; and we treated infants for otitis media according to specified guidelines. RESULTS: We followed 2253 infants until age 2 years. The proportions developing > or = 1 episode of middle-ear effusion (MEE) between age 61 days (the starting point for data analysis) and ages 6, 12, and 24 months, respectively, were 47.8%, 78.9%, and 91.1%. Overall, the mean cumulative proportion of days with MEE was 20.4% in the first year of life and 16.6% in the second year of life. Tympanostomy-tube placement was performed on 1.8% and 4.2% of the infants during the first and second years of life, respectively. By every measure, the occurrence of MEE was highest among urban infants and lowest among suburban infants; these differences were greatest in the earliest months of life. Overall, unadjusted mean cumulative proportions of days with MEE were higher among boys than girls, higher among black than white infants, and higher among Medicaid than private health insurance enrollees. Cumulative proportions of days with MEE varied directly with the number of smokers in the household and with the number of other children to whom infants were exposed, whether at home or in day care, and varied inversely with birth weight, maternal age, level of maternal education, a socioeconomic index, and duration of breastfeeding. After adjustment, using multivariate analysis, the only variables that each remained independently and significantly related to the cumulative proportion of days with MEE were: during the first year of life, study site grouping, sex, the socioeconomic index, breastfeeding for > or = 4 months, the number of smokers in the household, and an index rating the degree of exposure to other children at home or in day care; and during the second year of life, sex, the socioeconomic index, and the child exposure index. The duration of breastfeeding and the degree of exposure to tobacco smoke contributed little to the explained variance; most was attributable to differences in the socioeconomic index and the child exposure index. CONCLUSIONS: Contrary to findings in many previous reports, the prevalence of otitis media during the first 2 years of life among lower-socioeconomic-status black infants appears to be as high as, if not higher than among lower-socioeconomic-status white infants, and certainly higher than among middle-class white infants. Among middle-class white infants the prevalence may also be higher than commonly assumed. The most important sociodemographic risk factors for otitis media appear to be low socioeconomic status and repeated exposure to large numbers of other children, whether at home or in day care.

Efficacy of antimicrobial prophylaxis for recurrent middle ear effusion.

OBJECTIVES: This trial compared the efficacy of amoxicillin prophylaxis with that of placebo for the management of recurrent middle ear effusion (MEE) in children. METHODS: Children between 7 months and 12 years of age who were effusion-free at entry but had histories of chronic or recurrent MEE were randomly assigned to receive either amoxicillin (20 mg/kg once daily) or placebo for 1 year. They were examined monthly and when there were symptoms of ear, nose or throat disease. Acute otitis media (AOM) and new episodes of otitis media with effusion (OME) were treated with amoxicillin-clavulanate; tympanocentesis was performed when possible for episodes of AOM. Throat cultures were obtained at entry; 4, 8 and 12 months after entry; and with new episodes of AOM and OME. Tympanometry was performed at each visit and audiometry was performed at entry and 4, 8 and 12 months after entry. RESULTS: One hundred eleven children were entered in this study. The rates per person year of new episodes of disease in the amoxicillin and placebo groups, respectively, were: MEE, 1.81 vs. 3.18 (P < 0.001); AOM, 0.28 vs. 1.04 (P < 0.001); and OME, 1.53 vs. 2.15 (P = 0.016). Subjects in the amoxicillin group had less time with MEE than the placebo group (19.7 and 33.2%, respectively; P = 0.002). Middle ear and throat cultures did not reveal any increase in beta-lactamase-producing organisms or in Streptococcus pneumoniae attributable to daily use of amoxicillin. CONCLUSIONS: Amoxicillin prophylaxis lowered the rates of occurrence of MEE, AOM and OME and decreased the percentage of time with MEE. However, because of present day concerns regarding antibiotic resistance, management should be individualized.

Detecting hepatocellular carcinoma: value of unenhanced or arterial phase CT imaging or both used in conjunction with conventional portal venous phase contrast-enhanced CT imaging.

OBJECTIVE: Because rates of detection of hypervascular neoplasms by conventional dynamic incremental-bolus CT are lower than rates of detection of hypovascular tumors by CT and because both unenhanced CT imaging and arterial phase helical CT imaging may increase the detection of hypervascular tumors, such as hepatocellular carcinoma, we evaluated the value of unenhanced and arterial phase CT imaging used in conjunction with conventional portal venous phase CT imaging in patients with hepatocellular carcinoma. MATERIALS AND METHODS: Unenhanced and biphasic helical contrast-enhanced CT studies were performed on 81 patients with proven hepatocellular carcinoma. Arterial phase and portal venous phase images were obtained at 20-50 sec and at 60-100 sec, respectively. Three blinded readers evaluated portal venous phase images for the number of liver lesions. On separate dates, the readers compared the arterial phase images with the portal venous phase images and the unenhanced images with the portal venous phase images. The readers recorded the number of lesions that were seen on portal venous phase images and that were also detected on unenhanced or arterial phase images as well as the number of additional lesions seen on unenhanced or arterial phase images. Consensus readings of unenhanced, arterial phase, and portal venous phase images were obtained in the 42 patients who had definitive surgery or follow-up CT scans, documenting the total tumor burden in this patient subgroup. RESULTS: The readers identified 286-310 lesions on portal venous phase images. On unenhanced images, the readers identified 223-244 of the lesions seen on portal venous phase images and an additional 45-55 lesions that were not seen on portal venous phase images. Arterial phase imaging revealed 245-269 of the lesions seen on portal venous phase images and an additional 89-111 lesions that were not seen on portal venous images. The diagnosis of tumor was possible only on unenhanced images in two (3%) of 81 patients and only on arterial phase images in seven patients (9%). In the subset of 42 patients with proof of tumor burden, 157 proven lesions were found. Consensus readings identified 127 (81%) of these lesions on portal venous phase images, 98 (62%) of these lesions on unenhanced images, and 120 (76%) of these lesions on arterial phase images. Of the 30 lesions not seen on portal venous phase images, nine were seen on both unenhanced and arterial phase images, three were seen on unenhanced images only, and 18 were seen on arterial phase images only. CONCLUSION: In patients with known or suspected hepatocellular carcinoma, the use of unenhanced or arterial phase images or both in addition to conventional portal venous phase images resulted in more tumors being detected. The combination of arterial phase and portal venous phase images revealed significantly more hepatocellular carcinoma lesions than did the combination of unenhanced and portal venous phase images.

Craniofacial structure and obstructive sleep apnea syndrome--a qualitative analysis and meta-analysis of the literature.

The etiologic relevance of craniofacial structure to obstructive sleep apnea syndrome (OSAS) is controversial yet the premise of a causal association serves to justify many treatments. A qualitative and quantitative analysis of the literature was performed to examine the foundation for any relationship between craniofacial structure and OSAS. A MEDLINE search and investigation of the published and unpublished literature on diagnostic imaging and OSAS was toxonomically arranged. Each sample study was evaluated by using the following criteria: (a) appropriate control group, (b) "blinding" of evaluators, (c) reliability measured, (d) random assignment of treatment, and (e) "success" was defined adequately in efficacy studies. Morphologic variables were combined among studies and compared with controls drawn from either the same patient pool as the OSAS group, or matched for gender, age, and body mass index. Analysis revealed 32 review articles, 16 case reports, and 95 sample studies. Only seven sample studies drew a control group from the same patient pool, whereas five used matched controls. Only one of these studies satisfied all the qualitative criteria. Of the treatment efficacy studies, 10 defined outcome adequately. However, none of these met all the qualitative criteria. The most consistent, strong effect sizes with the highest potential diagnostic accuracies were for mandibular plane to hyoid, mandibular plane angle, and mandibular body length. Only mandibular body length demonstrated a clinically significant association with and diagnostic accuracy for OSAS. However, since this variable's controls were selected from the literature, possible explanations for a positive association include methodologic differences between studies, varying magnification factors, and morphologic differences.

Imaging systems evaluation: effect of subtle cases on the design and analysis of receiver operating characteristic studies.

OBJECTIVE: Large-scale receiver operating characteristic (ROC) studies are expensive and time-consuming. If most of the difference in diagnostic accuracy occurs in a subset of subtle cases, considerable effort could be saved by restricting comparisons to this subset. We investigate the effect of subtle cases on diagnostic accuracy, the magnitude of error that can occur because of an imbalance of subtle cases in two groups, and the potential for sample size reductions if only subtle cases are used. METHODS: Data from a previous study of posteroanterior chest radiographs were reanalyzed separately for subsets of typical cases and subsets of subtle cases. Actually positive and actually negative cases were classified as subtle or typical and as difficult or easy for diagnosis of the specific abnormality. The area under the ROC curve (Az) was used as the measure of diagnostic accuracy. Pairwise comparisons were done among three techniques and for the detection of nodules and interstitial disease. RESULTS: The performance index (Az) was significantly (> or = 25%) lower for the subset of subtle cases as compared with the subset of typical cases. The difference in observer performance between two techniques was more often greater in the subset of subtle cases than in the subset of typical cases. CONCLUSION: The difference in diagnostic accuracy between the subset of typical cases and the subset of subtle cases is large enough that a difference in the proportion of subtle cases in two samples could result in clinically significant false differences in observer performance. Furthermore, the generally larger difference observed in the group of subtle cases suggests that sample sizes for some experiments could be reduced by 45-90% if the experiment were restricted to subtle cases.

Otitis media in a population of black American and white American infants, 0-2 years of age.

To determine the incidence of otitis media (OM) and the bacteriology of acute otitis media (AOM) in a clinic population of young children in Pittsburgh, 138 black infants and 60 white infants were followed from birth to 2 years of age, examined at monthly intervals and whenever an upper respiratory tract infection (URI) or OM intervened. By 24 months of age the cumulative incidence of episodes of AOM was 43% and 42%, and of episodes of middle-ear effusion (MEE) was 86% and 85% in black and white infants, respectively. The average rate of episodes of AOM was 0.41 and 0.39 and of episodes of MEE was 1.68 and 1.70 in black and white infants, respectively. Tympanocentesis was performed for episodes of AOM and the following organisms were isolated from black and white infants, respectively: Streptococcus pneumoniae 43% and 43% of episodes; Moraxella catarrhalis 24% and 24%; non-typable Haemophilus influenzae 18% and 24%; and Haemophilus influenzae type b 5% and 0%. In both black and white infants first born children had less ear disease. We found no difference in the incidence of otitis media during the first 2 years of life between black and white infants.