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Chronic obstructive pulmonary disease (COPD) is becoming one of the leading causes of mortality and morbidity throughout the world. The National Emphysema Treatment Trial demonstrated that lung volume reduction surgery can improve pulmonary function, exercise capacity, and quality of life in select subgroups of patients with COPD. In recent years, few bronchoscopic lung volume reduction (BLVR) procedures have undergone clinical trials with the goal of establishing an effective and safe alternative approach for reducing hyperinflation in patients with severe emphysema who are symptomatic despite optimal medical management, but are poor surgical candidates. Of these BLVR procedures, only deployment of 1-way endobronchial valves (EBVs) has the largest pool of scientific data available to date to support its clinical utility. Two EBV systems have been food and drug administration-approved within the last year to meet the clinical demands of this select group of patients with COPD. On the basis of the results of multiple randomized clinical trials, the recommendations of the original 2016 Expert Panel Report on BLVR usage criteria of EBV have been updated in 2019. The outcome of EBV therapy is maximized in certain image-based COPD phenotypes. Imaging plays a major role in patient selection, target lobe identification, and in the management of postprocedural adverse events. With the expected widespread use of EBV therapy in the coming years, knowledge and familiarity of the Role of Imaging in BLVR using EBVs is essential for radiologists attempting to make meaningful contribution toward improving clinical outcomes.

C lustered microcysts represent the terminal duct lobular unit or a portion of it with cystic dilation of individual acini (1-3). Clustered microcysts represent one form of benign fibrocystic change of the breast, which also includes simple cysts, fibrosis, and adenosis (1). The epithelium lining the acini may be bland or, equally likely, may undergo apocrine metaplasia and be composed of a tall secretory columnar epithelium (1-3).Clustered microcysts are common, especially in perimenopausal women, and are seen in up to 6% of US examinations (4). Clustered microcysts are often an incidental finding observed at mammography or sonography (4). The most common mammographic finding of clustered microcysts is that of a round or oval mass with circumscribed or microlobulated but not indistinct margins (2). Calcifications, typically sedimented (milk of calcium), may occasionally be observed (2,5,6). The Breast Imaging Reporting and Data System (BI-RADS) defines clustered microcysts at US as clusters of anechoic masses, each 2-3 mm in size, separated by thin septations smaller than 0.5 mm, although several series include lesions with individual cystic components up to 5-7 mm (2,4,7,8). No discrete solid component should be observed; however, individual microcysts may demonstrate fluid-debris levels or low-level echoes, making it difficult to exclude a solid component (1,7).There are limited published data on the appropriate assessment and management recommendation for clustered microcysts on breast US images, which sometimes leads to uncertainty for interpreting radiologists and varied management recommendations (1,2). The BI-RADS 5th edition states, "The relatively small number of cases studied limits precision in estimating the likelihood of malignancy to be  2%; the data would be more convincing if at least 500 cases were studied" (7). There are six prior series with reported outcomes for a combined total of 330 clustered microcysts with acceptable imaging follow-up or tissue sampling (1,2,4,(8)(9)(10). Our investigation attempts to contribute enough additional cases to the existing literature to more confidently support a recommendation of benign (BI-RADS category 2), thus avoiding biopsy or follow-up imaging.