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How bats mitigate mutual interference is a long-standing question that has ecological and technological implications as biosonar systems continue to outperform artificial sonar systems in noisy, cluttered environments. Echolocating bats display a mutual suppression response, slowing their pulse emission rates when flying in groups to gain a net improvement in sonar performance. However, flight paths, directional effects, plus contextual and attentional processes influence the levels of mutual interference, causing some noises to be more deleterious than others. To tease apart the impact of these factors, we used playback experiments with flying Mexican free-tailed bats, Tadarida brasiliensis, to test whether the relative directional orientation of an interfering signal versus its returning echoes had a greater impact on a bat's sonar performance. We tested two competing hypotheses: (1) the intensity hypothesis predicts that a signal that is emitted towards a signalling bat is louder and will mask returning echoes more than a signal that is emitted in the same direction as a bat's emitted signal; (2) the similarity hypothesis predicts that a signal that is emitted in the same direction as a bat's signal will create echoes similar in amplitude and timing to those of the signalling bat's own echoes , which should cause greater interference than a loud, less similar signal. We analysed emission rates of bats navigating in both open and cluttered spaces while we varied the directional orientation of an artificial stimulus relative to the bat's flight trajectory. Both emission rates and navigational performance decreased significantly when playback was directed in the same heading as the flying bat, indicating that competing echo wave-fronts are more disruptive to a flying bat than the much louder source signal that produced them. This observation is important because it potentially reveals the impact of attentional processes on sonar performance. This study provides new information on how echolocating bats experience interference and the behavioural strategies they use to overcome jamming.

Bats are facing threats from disease, wind power development, and climate change, which are causing populations of many species to decline. The northern range limits of many temperate species are not well characterized, but the true distribution of threatened bat species is critical information for their conservation. We used passive acoustic monitoring and false-positive occupancy models to estimate the distributions of six species of bats in northern Ontario (north of ca. 50.5°N). We confirmed the presence of big brown bats (Eptesicus fuscus), hoary bats (Lasiurus cinereus), eastern red bats (Lasiurus borealis), silver-haired bats (Lasionycteris noctivagans), little brown myotis (Myotis lucifugus), northern long-eared myotis (Myotis septentrionalis), and tri-colored bats (Perimyotis subflavus) in our study area. We found that big brown bats, hoary bats, and little brown myotis likely are more widespread and common in northern Ontario than previously thought. Our models also provided evidence of associations between temperature and habitat types and bat occupancy probabilities. Our occupancy probability maps for each species support bat conservation by providing much finer-scale distribution information than previously available. These results provide a much-needed baseline for future studies of the distribution of these bat species in northern Ontario against which to measure the effects of white-nose syndrome, resource development, and climate change.

As molecular tools for assessing trophic interactions become common, research is increasingly focused on the construction of interaction networks. Here, we demonstrate three key methods for incorporating DNA data into network ecology and discuss analytical considerations using a model consisting of plants, insects, bats and their parasites from the Costa Rica dry forest. The simplest method involves the use of Sanger sequencing to acquire long sequences to validate or refine field identifications, for example of bats and their parasites, where one specimen yields one sequence and one identification. This method can be fully quantified and resolved and these data resemble traditional ecological networks. For more complex taxonomic identifications, we target multiple DNA loci, for example from a seed or fruit pulp sample in faeces. These networks are also well resolved but gene targets vary in resolution and quantification is difficult. Finally, for mixed templates such as faecal contents of insectivorous bats, we use DNA metabarcoding targeting two sequence lengths (157 and 407 bp) of one gene region and a MOTU, BLAST and BIN association approach to resolve nodes. This network type is complex to generate and analyse, and we discuss the implications of this type of resolution on network analysis. Using these data, we construct the first molecular-based network of networks containing 3,304 interactions between 762 nodes of eight trophic functions and involving parasitic, mutualistic and predatory interactions. We provide a comparison of the relative strengths and weaknesses of these data types in network ecology.

This study analyzed insolation data to account for multiple scattering in calculating optimal tilt angles for stationary and seasonally moving photovoltaics on three different roof types in the US Pacific Northwest: vegetated roofs, white roofs, and dark roofs. Using these results, we modeled the energy savings for vegetated roofs and roofs covered in varying numbers of photovoltaic panels. We then calculated the net present value, internal rate of return, and other economic measures for all possible combinations of covering rooftops in mixes of photovoltaic arrays and vegetation, accounting for installation costs, proposed carbon taxes, stormwater management discounts, and other relevant factors. Our results quantify how, in the US Pacific Northwest and similar locations, photovoltaics produce higher returns on investment than do vegetated roofs for new buildings, while vegetated roofs produce better returns on investment than do photovoltaics for older buildings. This is important because in many areas, some buildings have photovoltaics when a vegetated roof would have been more cost and energy efficient, while other buildings have vegetated roofs when photovoltaics would have been more cost and energy efficient. Potential applications include modifying incentive programs and other policies to account properly for building age, use, and other relevant factors to ensure building owners make the most energy-efficient decisions between photovoltaic versus vegetated roof installation. Our research also demonstrates how positive returns on investment can be realized in the US Pacific Northwest and similar regions through vegetated roofs and photovoltaics provided they are each installed optimally.

Intraspecific variation in animal energy and water balances may play an important role in local adaptation of populations to specific habitats such as deserts. We examined Kuhl's pipistrelle (Pipistrellus kuhlii), a common bat in Israel that ranges in distribution from mesic Mediterranean to hyperarid desert habitats, for intraspecific differences in metabolic rate (MR) and evaporative water loss (EWL) among populations along a climatic gradient. We tested the prediction that EWL, especially at high ambient temperatures is lower in Kuhl's pipistrelles from desert habitats than from mesic habitats. We measured MR and total evaporative water loss (TEWL) at four ambient temperatures (10 °C, 20 °C, 30 °C and 35 °C) in three groups of bats using open-flow respirometry. We fitted the bats with a mask to separate cutaneous water loss (CWL) from respiratory water loss (RWL) at 35 °C. At 35 °C, mean TEWL in the southernmost group, from the hyperarid location, was significantly lower than in the other two groups, with no apparent difference in mean MR. The source of difference TEWL was that the southern group had significantly lower CWL than the other two groups; RWL did not differ among them. This suggests that there are mechanisms that reduce EWL from the skin of the bats; a likely candidate is modification of the lipids in the outer layer of the dermis that make the skin possibly less permeable to water as has been described in birds and a few other species of bat.

Natural bodies of open water in desert landscapes are important resources for survival of desert-dwelling animals and in recent years artificial bodies of water may have become equally important. In the present study we are testing if species richness and activity of bats are related to the water chemistry both in natural and artificial bodies of water, and if these measures can indicate water quality in desert habitats where water is scarce. We combined acoustic monitoring of bat activity and species richness in artificial and natural bodies of water in the Negev desert, Israel and measured 27 variables of water chemistry and quality at each site. Significant differences in water chemistry and quality were found between natural and artificial bodies of water. Species richness and activity of bats did not differ between artificial and natural bodies of water, indicating that desert-dwelling bats may benefit from artificial bodies of water, however activity within species differed between natural and artificial bodies of water. Some species of bats were only recorded at natural bodies of water, suggesting that these species are not tolerant to lower quality of water and emphasizes the importance of natural bodies of water in desert ecosystems. Our results demonstrate that community measures, such as total bat activity and species richness of bats in desert habitats, may not be sufficient to indicate changes in water chemistry and quality. Rather it is recommended and applicable to use the activity of specific species as indicators of water quality in desert habitats.

Passive acoustic monitoring is a common tool used for monitoring bat activity levels. Identifying periods and locations of peak levels provides insight into bat ecology and has important management implications. One limitation of passive acoustic monitoring is the relative nature of the data, often relying on subjective interpretation of descriptive terminology such as “higher” or “lower”. We propose the use of percentile thresholds (PTs) for objectively identifying peak activity. By compiling a reference data set, it is possible to define percentiles of the observed activity levels and these percentiles can provide objective thresholds for comparing activity levels. We used acoustic recordings from sites in Canada and calculated PTs based on the distribution of the number of calls per hour across all nights and sites for three species of bat. Given species ecologies (e.g., hibernating, migrating), we were able to use PTs to objectively identify peak activity levels on a species-specific basis. Percentile thresholds are also a replicable method of describing within-night activity by evaluating species-specific activity patterns and important times of night. Our analyses and examples represent a proof of concept. The next step is to move towards a standardized distribution to generate PTs. Creating a public repository of acoustic data sets to evaluate activity of a species in the context of its entire range would allow us to standardize terms such as “high” activity in an objective manner.

Summary 1. Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using different strategies, for example opportunistic foraging, or switching between multiple trophic niches. 2. The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) poses different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism. 3. Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera) and noctuid moths with bat-detecting ears. Laboratory observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores. 4. In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low-intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences. 5. Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.

In southern Ontario, Canada, the range and distribution of bats is well known, but their activity in the northeastern part of the province (north of 47°N, east of 85°W) is poorly documented. Using acoustic sampling, we documented the occurrence of six species of bats in the boreal forest of northeastern Ontario: Eptesicus fuscus (Big Brown Bat), Lasiurus borealis (Eastern Red Bat), L. cinereus (Hoary Bat), Myotis lucifugus (Little Brown Bat), M. septentrionalis (Northern Long-eared Bat), and Lasionycteris noctivagans (Silver-haired Bat). Hoary Bats were recorded more frequently than all other species. Little Brown Bats were second-most frequently recorded, and the remaining four species were encountered (mean number passes/hour) significantly less often. Our records are the most northerly for Big Brown Bats in this part of Ontario. Although the other species were expected in this area, this is the first study to identify and confirm the bats present in the boreal forest of northeastern Ontario. T...

Echolocating bats face the challenge of actively sensing their environment through their own emissions, while also hearing calls and echoes of nearby conspecifics. How bats mitigate interference is a long-standing question that has both ecological and technological implications, as biosonar systems continue to outperform man-made sonar systems in noisy, cluttered environments. We recently showed that perched bats decreased calling rates in groups, displaying a behavioral strategy resembling the back-off algorithms used in artificial communication networks to optimize information throughput at the group level. We tested whether free-tailed bats (Tadarida brasiliensis) would employ such a coordinated strategy while performing challenging flight maneuvers, and report here that bats navigating obstacles lowered emission rates when hearing artificial playback of another bat’s calls. We measured the impact of acoustic interference on navigation performance and show that the calculated reductions in interference rates are sufficient to reduce interference and improve obstacle avoidance. When bats flew in pairs, each bat responded to the presence of the other as an obstacle by increasing emissions, but hearing the sonar emissions of the nearby bat partially suppressed this response. This behavior supports social cohesion by providing a key mechanism for minimizing mutual interference.

Summary The probability of detecting the echolocation calls of bats is affected by the strength of the signal as well as the directionality and frequency response of the acoustic detectors. Regardless of the research question, it is important to quantify variation in recording system performance and its impacts on bat detection results. The purpose of this study was to compare the detection of echolocation calls among five commonly used bat detectors: AnaBat SD2 (Titley Scientific), Avisoft UltraSoundGate 116 CM16/CMPA (Avisoft Bioacoustics), Batcorder 2·0 (ecoObs), Batlogger (Elekon AG) and Song Meter SM2BAT (Wildlife Acoustics). We used playback of synthetic calls to optimize detection settings for each system. We then played synthetic signals at four frequencies (25, 55, 85 and 115 kHz) at 5-m intervals (5–40 m) and three angles (0°, 45°, 90°) from the detectors. Finally, we recorded free-flying bats (Lasiurus cinereus), comparing the number of calls detected by each detector. Detection was most affected by the frequency dominating the signal and the distance from the source. The effect of angle was less apparent. In the synthetic signal experiment, Avisoft and Batlogger outperformed other detectors, while Batcorder and Song Meter performed similarly. Batlogger performed better than the other detectors at angles off-centre (45° and 90°). AnaBat detected the fewest signals and none at 85 kHz or 115 kHz. Avisoft detected the most signals. In the free-flying bat experiment, Batlogger recorded 93% of calls relative to Avisoft, while AnaBat, Batcorder and Song Meter recorded 40–50% of the calls detected by Avisoft. Numerous factors contribute to variation in data sets from acoustic monitoring; our results demonstrate that choice of detector plays a role in this variation. Differences among detectors make it difficult to compare data sets obtained with different systems. Therefore, the choice of detector should be taken into account in designing studies and considering bat activity levels among studies using different detectors.

The National Lung Screening Trial (NLST) is a randomized multicenter study comparing low-dose helical computed tomography (CT) with chest radiography in the screening of older current and former heavy smokers for early detection of lung cancer, which is the leading cause of cancer-related death in the United States. Five-year survival rates approach 70% with surgical resection of stage IA disease; however, more than 75% of individuals have incurable locally advanced or metastatic disease, the latter having a 5-year survival of less than 5%. It is plausible that treatment should be more effective and the likelihood of death decreased if asymptomatic lung cancer is detected through screening early enough in its preclinical phase. For these reasons, there is intense interest and intuitive appeal in lung cancer screening with low-dose CT. The use of survival as the determinant of screening effectiveness is, however, confounded by the well-described biases of lead time, length, and overdiagnosis. Despite previous attempts, no test has been shown to reduce lung cancer mortality, an endpoint that circumvents screening biases and provides a definitive measure of benefit when assessed in a randomized controlled trial that enables comparison of mortality rates between screened individuals and a control group that does not undergo the screening intervention of interest. The NLST is such a trial. The rationale for and design of the NLST are presented.

Background The National Lung Screening Trial (NLST), a randomized study conducted at 33 US sites, is comparing lung cancer mortality among persons screened with reduced dose helical computerized tomography and among persons screened with chest radiograph. In this article, we present characteristics of the study population. Methods Eligible participants were aged 55–74 years and were current or former smokers with a cigarette smoking history of at least 30 pack-years. Randomization was stratified by site, sex, and age. To assess representativeness of the study population, demographic characteristics of individuals from the general population who met NLST age and smoking history inclusion criteria were obtained from the Tobacco Use Supplement of the US Census Bureau Current Population Surveys. Results The NLST enrolled 53 456 persons, with 26 733 randomly assigned to chest radiograph screening and 26 723 to computerized tomography screening. Characteristics of the participants were as follows: 31 533 (59%) were men, 39 234 (73%) were younger than 65 years, 25 779 (48%) were current smokers, and 16 839 (32%) had a college or higher degree. Median cigarette exposure was 48 pack-years. Among Tobacco Use Supplement respondents who met NLST age and smoking history criteria, 59% were men, 65% were younger than 65 years, and 57% were current smokers. Median cigarette exposure among this group was 47 pack-years, and 14% had a college degree or higher. Conclusion The NLST cohort has a distribution of sex and pack-year history that is similar to the component of the general US population that meets the major NLST eligibility criteria; however, NLST participants are younger, better educated, and less likely to be current smokers.

Lung cancer continues to be a major public health problem, and more patients die from this disease than any other cancer. The vast majority of patients present with advanced stage disease when therapeutic options are limited and the overall 5 year survival rate remains approximately 15%. Screening with low dose helical computed tomography (CT)has been suggested for early detection, although the effect on mortality is currently under investigation. As part of the National Lung Cancer Screening Trial, a specimen biorepository including blood, sputum, and urine were collected serially for the primary purpose of validating early detection lung cancer biomarkers. In addition tumor samples have been obtained from patients diagnosed with lung cancer to be included in a tissue microarray. This commentary describes the rationale, composition, intent, and availability of specimen in the biorepository.

To determine reasons for nonparticipation in a trial of supplemental screening with magnetic resonance (MR) imaging after mammography and ultrasonography (US).Women(n = 2809) at elevated risk of breast cancer were enrolled in the American College of Radiology Imaging Network 6666 US Screening Protocol at 21 institutions. Fourteen institutions met technical and experience requirements for this institutional review board-approved, HIPAA-compliant substudy of supplemental screening with MR imaging. Those women who had completed 0-, 12-, and 24-month screenings with mammography combined with US were considered for a single contrast material-enhanced MR examination within 8 weeks after completing the 24-month mammography-US screening. A total of 1593 women had complete MR substudy registration data: 378 of them were ineligible for the study, and 1215 had analyzable data. Reasons for nonparticipation were determined. Demographic data were compared between study participants and nonparticipants.Of 1215 women with analyzable data, 703 (57.9%), with a mean age of 54.8 years, were enrolled in the MR substudy and 512 (42.1%) declined participation. Women with a 25% or greater lifetime risk of breast cancer were more likely to participate (odds ratio, 1.53; 95% confidence interval: 1.10, 2.12). Of 512 nonparticipants, 130 (25.4%) refused owing to claustrophobia; 93 (18.2%), owing to time constraints; 62 (12.1%), owing to financial concerns; 47 (9.2%), because their physician would not provide a referral and/or did not believe MR imaging was indicated; 40 (7.8%), because they were not interested; 39 (7.6%), because they were medically intolerant to MR imaging; 29 (5.7%), because they did not want to undergo intravenous injection; 27 (5.3%), owing to additional biopsy or other procedures that might be required subsequently; 21 (4.1%), owing to MR imaging scheduling constraints; 11 (2.2%), because of the travel required; seven (1.4%), owing to gadolinium-related risks or allergies; and six (1.2%), for unknown reasons.Of 1215 women with elevated breast cancer risk who could, according to protocol guidelines, undergo breast MR imaging, only 57.9% agreed to participate.

Many animals reside in burrows that may serve as refuges from predators and adverse environmental conditions. Burrow design varies widely among and within taxa, and these structures are adaptive, fulfilling physiological (and other) functions. We examined the burrow architecture of three scorpion species of the family Scorpionidae: Scorpio palmatus from the Negev desert, Israel; Opistophthalmus setifrons, from the Central Highlands, Namibia; and Opistophthalmus wahlbergii from the Kalahari desert, Namibia. We hypothesized that burrow structure maintains temperature and soil moisture conditions optimal for the behavior and physiology of the scorpion. Casts of burrows, poured in situ with molten aluminum, were scanned in 3D to quantify burrow structure. Three architectural features were common to the burrows of all species: (1) a horizontal platform near the ground surface, long enough to accommodate the scorpion, located just below the entrance, 2-5 cm under the surface, which may provide a safe place where the scorpion can monitor the presence of potential prey, predators, and mates and where the scorpion warms up before foraging; (2) at least two bends that might deter incursion by predators and may reduce convective ventilation, thereby maintaining relatively high humidity and low temperature; and (3) an enlarged terminal chamber to a depth at which temperatures are almost constant (±2-4 °C). These common features among the burrows of three different species suggest that they are important for regulating the physical environment of their inhabitants and that burrows are part of scorpions' "extended physiology" (sensu Turner, Physiol Biochem Zool 74:798-822, 2000).

Context Identifying key spatio–temporal periods of an organism’s activity is an important focus of many ecological studies. Bat activity, as assessed by passive acoustic monitoring, can be extremely variable and currently there exists no agreed-upon method for identifying periods of high activity. Aims We proposed a new application for the space–time scan statistic (SaTScan) as an objective technique for identifying peak periods of bat activity. We aimed to test the validity of SaTScan as a method for identifying peaks in bat activity and demonstrate its use for assessing species-specific temporal patterns of activity. Methods To evaluate the effectiveness of SaTScan for detecting peaks in activity, we compared SaTScan to peaks identified with percentile thresholds. We evaluated peaks in activity across three scales: within nights; among nights at a site; and among sites. We applied SaTScan to demonstrate analysis of species-specific activity as further use of this technique. Key results SaTScan was effective at identifying peak time periods that included the majority of the high activity minutes. Timing of peaks of activity was most consistent for Myotis lucifugus during swarming and Lasiurus borealis during migration. All other activity for five species at three sites was indicative of foraging activity, with peaks in the first 5h after sunset. Conclusions SaTScan can be a valuable tool for quickly identifying peaks in acoustic activity of bats, with an objective, replicable and statistically sound method that can be applied at many temporal and spatial scales. Implications This tool has the potential for many more applications in ecology. Beyond acoustic analyses of bat activity, this technique could easily identify peaks in a research or management context, such as study activity among habitats, commercial developments or years at a single site.

Background Molecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely to speciate quickly. Pteronotus parnellii is a widespread Neotropical bat and the only New World species to use high-duty cycle echolocation, a trait otherwise restricted to Old World taxa. Here we analyze morphological and acoustic variation and genetic divergence at the mitochondrial COI gene, the 7th intron region of the y-linked Dby gene and the nuclear recombination-activating gene 2, and provide extensive evidence that P. parnellii is actually a cryptic species complex. Results Central American populations form a single species while three additional species exist in northern South America: one in Venezuela, Trinidad and western Guyana and two occupying sympatric ranges in Guyana and Suriname. Reproductive isolation appears nearly complete (only one potential hybrid individual found). The complex likely arose within the last ~6 million years with all taxa diverging quickly within the last ~1-2 million years, following a pattern consistent with the geological history of Central and northern South America. Significant variation in cranial measures and forearm length exists between three of the four groups, although no individual morphological character can discriminate these in the field. Acoustic analysis reveals small differences (5–10 kHz) in echolocation calls between allopatric cryptic taxa that are unlikely to provide access to different prey resources but are consistent with divergence by drift in allopatric species or through selection for social recognition. Conclusions This unique approach, considering morphological, acoustic and multi-locus genetic information inherited maternally, paternally and bi-parentally, provides strong support to conclusions about the cessation of gene flow and degree of reproductive isolation of these cryptic species.

Annual ultrasound screening may detect small, node-negative breast cancers that are not seen on mammography. Magnetic resonance imaging (MRI) may reveal additional breast cancers missed by both mammography and ultrasound screening.To determine supplemental cancer detection yield of ultrasound and MRI in women at elevated risk for breast cancer.From April 2004-February 2006, 2809 women at 21 sites with elevated cancer risk and dense breasts consented to 3 annual independent screens with mammography and ultrasound in randomized order. After 3 rounds of both screenings, 612 of 703 women who chose to undergo an MRI had complete data. The reference standard was defined as a combination of pathology (biopsy results that showed in situ or infiltrating ductal carcinoma or infiltrating lobular carcinoma in the breast or axillary lymph nodes) and 12-month follow-up.Cancer detection rate (yield), sensitivity, specificity, positive predictive value (PPV3) of biopsies performed and interval cancer rate.A total of 2662 women underwent 7473 mammogram and ultrasound screenings, 110 of whom had 111 breast cancer events: 33 detected by mammography only, 32 by ultrasound only, 26 by both, and 9 by MRI after mammography plus ultrasound; 11 were not detected by any imaging screen. Among 4814 incidence screens in the second and third years combined, 75 women were diagnosed with cancer. Supplemental incidence-screening ultrasound identified 3.7 cancers per 1000 screens (95% CI, 2.1-5.8; P.001). Sensitivity for mammography plus ultrasound was 0.76 (95% CI, 0.65-0.85); specificity, 0.84 (95% CI, 0.83-0.85); and PPV3, 0.16 (95% CI, 0.12-0.21). For mammography alone, sensitivity was 0.52 (95% CI, 0.40-0.64); specificity, 0.91 (95% CI, 0.90-0.92); and PPV3, 0.38 (95% CI, 0.28-0.49; P.001 all comparisons). Of the MRI participants, 16 women (2.6%) had breast cancer diagnosed. The supplemental yield of MRI was 14.7 per 1000 (95% CI, 3.5-25.9; P = .004). Sensitivity for MRI and mammography plus ultrasound was 1.00 (95% CI, 0.79-1.00); specificity, 0.65 (95% CI, 0.61-0.69); and PPV3, 0.19 (95% CI, 0.11-0.29). For mammography and ultrasound, sensitivity was 0.44 (95% CI, 0.20-0.70, P = .004); specificity 0.84 (95% CI, 0.81-0.87; P.001); and PPV3, 0.18 (95% CI, 0.08 to 0.34; P = .98). The number of screens needed to detect 1 cancer was 127 (95% CI, 99-167) for mammography; 234 (95% CI, 173-345) for supplemental ultrasound; and 68 (95% CI, 39-286) for MRI after negative mammography and ultrasound results.The addition of screening ultrasound or MRI to mammography in women at increased risk of breast cancer resulted in not only a higher cancer detection yield but also an increase in false-positive findings.clinicaltrials.gov Identifier: NCT00072501.