Conjoined twins are a rare complication of monochorionic twinning. Although most conjoined twins are stillborn or die in the newborn period, surgical advances are such that many parents will continue a pregnancy in the hopes that live born infants can be separated. Well-described types of conjoined twins account for most cases, with some rarer forms occasionally seen. Each type is associated with specific degrees of organ sharing, structural abnormalities, complications, and challenges with regard to potential separation. Thorough multidisciplinary prenatal assessment of conjoined twins is essential to appropriately counsel parents, to manage the pregnancy, and to create an appropriate delivery plan. This pictorial essay presents the imaging findings of the more common types of conjoined twins. Selected clinical and autopsy images are used to illustrate shared anatomy. The nomenclature for description of conjoined twins is reviewed, the imaging findings of each type are illustrated, and the challenges to separation are discussed.
Breast density assessment is an important component of the screening mammography report and conveys information to referring clinicians about mammographic sensitivity and the relative risk for developing breast cancer. These topics have gained substantial attention because of recent legislation in several states that requires patients to be informed of dense breast tissue and the potential for associated breast cancer risk and decreased mammographic sensitivity. Because of the considerable implications of diagnosing a woman with dense breast tissue, radiologists should strive to be as consistent as possible when assessing breast density. Commonly used methods of breast density assessment range from subjective visual estimation to quantitative calculations of area and volume density percentages made with complex computer algorithms. The basic principles of currently available commercial methods of calculating fibroglandular density are described and illustrated. There is no criterion standard for determining breast density, but understanding the pros and cons of the various assessment methods will allow radiologists to make informed decisions. Radiologists should understand the basic factors involved in breast density assessment, the changes related to density assessment described in the fifth edition of the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) lexicon, and the capabilities of currently available software. Online supplemental material is available for this article.
Epidemiologic/Diagnostic study, level III.
SM + DBT reduces false positives compared to FFDM, while maintaining the CDR and other desirable audit outcome data. SM + DBT is more accurate than FFDM alone, and is a desirable alternative to FFDM + DBT, given the added benefit of radiation reduction.
Olfactory loss and traumatic brain injury (TBI) both lead to anatomical brain alterations in humans. Little research has been done on the structural brain changes for TBI patients with olfactory loss. Using voxel-based morphometry, the gray matter (GM) density was examined for 22 TBI patients with hyposmia, 24 TBI patients with anosmia, and 22 age-matched controls. Olfactory bulb (OB) volumes were measured by manual segmentation of acquired T2-weighted coronal slices using a standardized protocol. Brain lesions in the olfactory-relevant areas also were examined for TBI patients. Results showed that patients with anosmia have more frequent lesions in the OB, orbitofrontal cortex (OFC), and the temporal lobe pole, compared with patients with hyposmia. GM density in the primary olfactory area was decreased in both groups of patients. In addition, compared with controls, patients with anosmia showed GM density reduction in several secondary olfactory eloquent regions, including the gyrus rectus, medial OFC, anterior cingulate cortex, insula, and cerebellum. However, patients with hyposmia showed a lesser degree of GM reduction, compared with healthy controls. Smaller OB volumes were found for patients with olfactory loss, compared with controls. TBI patients with anosmia had the smallest OB volumes, which were caused by the lesions for OB. In addition, post-TBI duration was negatively correlated with GM density in the secondary olfactory areas in patients with hyposmia, but was positively correlated with GM density in the frontal and temporal gyrus in patients with anosmia. The GM density and OB volume reduction among TBI patients with olfactory loss was largely dependent on the location and severity of brain lesions in olfactory-relevant regions. Longer post-TBI duration had an impact on brain GM density changes, which indicate a decreased olfactory function in patients with hyposmia and possible compensatory mechanisms in patients with anosmia.
Embryology, Anatomy, and Prenatal Imaging Featuresloacal malformations constitute a group of severe nonhereditary anorectal malformations. Failure of division of the cloaca or urogenital sinus early in embryogenesis results in either convergence of the genital, urinary, and intestinal contents into a single common channel (cloaca) or the formation of two channels: a common genitourinary channel (urogenital sinus) separate from the hindgut. Although rare, with a quoted incidence of 1 per 20,000 live births, 1 a tertiary referral center may encounter up to 1 or 2 cases per year based on our institutional experience.Recent retrospective reviews by Bischoff et al 2 and Livingston et al 3 found that the prenatal diagnosis of cloacal malformation was suspected in only 6% of their patients with a diagnosis of cloacal malformation at birth, despite the presence of suspicious sonographic findings in as many as 62% of the cases when the prenatal imaging reports were reviewed. 2 The results of their studies indicate a need for improved pattern recognition by obstetric imagers.In this series, we present the prenatal findings in a series of 6 proven cases of cloacal malformation. Characteristic imaging features of our cases in combination with a literature review are described, in addition to pitfalls and important differential considerations. Information on the prognosis and general management is provided for guidance in counseling and referring affected families. Cloacal extrophy is a distinct entity from cloacal malformation and will not be discussed. CASE SERIESCloacal malformation is a rare but important anomaly. Prenatal diagnosis is possible with knowledge of the distinctive imaging features. The purpose of this case series is to illustrate characteristic prenatal sonographic and magnetic resonance imaging features of cloacal malformation using imaging from 6 cases seen at a single academic center to augment published data. The imaging feature common to all cases was a central cystic pelvic mass containing a characteristic fluid-fluid level. Additional anomalies include uterine and vaginal duplication, hydronephrosis, and lumbosacral anomalies. Prenatal magnetic resonance imaging showed the absence of the normal T1-hyperintense meconium-filled rectum in all cases. Prenatal diagnosis may affect immediate neonatal care (eg, immediate drainage of hydrocolpos) with an ultimate improved outcome.
A developing asymmetry is a focal asymmetry that is new or increased in conspicuity compared with the previous mammogram. It is challenging to evaluate, as it often looks similar to fibroglandular tissue at mammography. A developing asymmetry should be viewed with suspicion because it is an uncommon manifestation of breast cancer. Diagnostic mammography forms the foundation of diagnostic evaluation of a developing asymmetry and begins with additional spot compression, lateral, and/or rolled views to evaluate and localize it in three-dimensional space. Digital breast tomosynthesis can aid in evaluation by improving radiologists' sensitivity and specificity, as well as allowing localization of the lesion. Once the developing asymmetry has been fully characterized and localized with diagnostic mammography, targeted ultrasonography (US) should be performed to identify potentially benign causes of the developing asymmetry or identify a target for biopsy. However, lack of a US correlate should not preclude biopsy of a developing asymmetry. Diagnostic breast magnetic resonance imaging can be used in a minority of cases for problem solving or biopsy planning if no US correlate is identified and stereotactic biopsy is not feasible. The purpose of this article is to review the definition of developing asymmetry, describe the multimodality diagnostic tools available to the radiologist for evaluation of this challenging entity, and review the various causes, both benign and malignant.
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