Troubleshooting Tips for Diagnosing Complex Fetal Genitourinary Malformations.

Fetal genitourinary anomalies can present a diagnostic challenge for the radiologist. The absence of a normally located kidney may represent agenesis or be secondary to a fusion or migration abnormality. A dilated renal pelvis should prompt evaluation for a specific cause, including ureteropelvic junction obstruction, reflux, or an obstructed duplicated system. Cystic parenchymal changes are characteristic of a multicystic dysplastic kidney but may also be seen in obstructive cystic dysplasia. There are numerous causes of megacystis including chromosomal (trisomy 18 syndrome), obstruction (posterior urethral valves, urethral atresia), or muscular dysfunction (prune belly syndrome, megacystis microcolon intestinal hypoperistalsis syndrome). Important mimics of a large bladder include hydrocolpos and urogenital sinus or cloacal malformation. Complications of genitourinary malformations are common and include oligohydramnios, urinary ascites, and urinoma. Making an accurate diagnosis often requires additional US views beyond those obtained in the standard fetal survey and occasionally performing fetal MRI. The appropriate use of orthogonal T2-weighted sequences, in conjunction with diffusion-weighted images for evaluation of the kidneys and gradient-recalled-echo sequences for evaluation of T1-hyperintense meconium in the colon, can play an integral role in diagnosis. Accurate diagnosis of fetal genitourinary malformations is vital to direct patient counseling and pregnancy management as outcomes are highly variable. Some conditions can be surgically corrected quite simply, some require multiple complex procedures, and some are lethal. The authors offer troubleshooting tips to narrow the differential diagnosis for four observations: unilateral absent kidney, dilated renal pelvis, cystic renal parenchyma, and megacystis and its mimics. ©RSNA, 2023 Test Your Knowledge questions are available in the Online Learning Center.

Sonographic Assessment of Fetal Growth Abnormalities.

Fetal growth abnormalities have significant consequences for pregnancy management and maternal and fetal well-being. The accurate diagnosis of fetal growth abnormalities contributes to optimal antenatal management, which may minimize the sequelae of inadequate or excessive fetal growth. An accurate diagnosis of abnormal fetal growth depends on accurate pregnancy dating and serial growth measurements. The fetal size at any given stage of pregnancy is either appropriate or inappropriate for the given gestational age (GA). Pregnancy dating is most accurate in the first trimester, as biologic variability does not come into play until the second and third trimesters. The authors describe the determination of GA with use of standard US measurements and how additional parameters can be used to confirm dating. Once dates are established, serial measurements are used to identity abnormal growth patterns. The sometimes confusing definitions of abnormal growth are clarified, the differentiation of a constitutionally small but healthy fetus from a growth-restricted at-risk fetus is described, and the roles of Doppler US and other adjunctive examinations in the management of growth restriction are discussed. In addition, the definition of selective growth restriction in twin pregnancy is briefly discussed, as is the role of Doppler US in the classification of subtypes of selective growth restriction in monochorionic twinning. The criteria for diagnosing macrosomia and the management of affected pregnancies also are reviewed. The importance of correct pregnancy dating in the detection and surveillance of abnormal fetal growth and for prevention of perinatal maternal and fetal morbidity and mortality cannot be overstated. The online slide presentation from the RSNA Annual Meeting is available for this article. ©RSNA, 2020.

Accuracy and Interobserver Reliability of Magnetic Resonance Imaging for Placenta Accreta Spectrum Disorders.

OBJECTIVE: This study aims to define the accuracy, predictive value, and interobserver reliability of magnetic resonance imaging (MRI) in the diagnosis of placenta accreta spectrum (PAS) disorders. STUDY DESIGN: Two experienced radiologists independently interpreted the MRI studies of patients with possible PAS from two referral centers. Radiologists were blinded to sonographic and clinical information. We calculated diagnostic testing characteristics and kappa statistics of interobserver reliability for MRI findings of PAS. RESULTS: Sixty-eight MRI cases were evaluated. Confirmed PAS and severe PAS were present in 44 (65%) and 20 (29%) cases. For the diagnosis of any PAS, MRI had a sensitivity 66%, specificity 71%, positive predictive value (PPV) 81%, negative predictive value (NPV) 53%, and accuracy 68%. For the diagnosis of severe PAS (percreta), MRI had a sensitivity 85%, specificity 79%, PPV 63%, NPV 93%, and accuracy 81%. The accuracy of individual signs of PAS was lower (44-65%). Interobserver agreement was almost perfect for previa; substantial for myometrial interruptions, PAS, severe PAS, and placental bulging/balling; and moderate to slight for other signs of PAS. CONCLUSION: Although the interobserver reliability of MRI for a diagnosis of PAS is substantial, the accuracy and predictive value are modest and lower than previously reported.

A Radiologist's Guide to the Performance and Interpretation of Obstetric Doppler US.

Doppler US provides a unique window to the fetoplacental circulation, allowing assessment of fetal well-being. Doppler US of the umbilical artery is an integral component of managing the fetus with growth restriction; and Doppler US of the middle cerebral artery, as a noninvasive means of detecting fetal anemia, has revolutionized the management of pregnancies complicated by alloimmunization. Serial use of amniocentesis, with its attendant risks, has been replaced by serial Doppler US examinations. Invasive procedures are now reserved for the treatment of anemia with intrauterine transfusion. Technique is critical to obtain the best waveforms for ease of shape assessment, velocity measurement, and calculation of various ratios. In this article, the safety of Doppler US is reviewed, the fetal circulation is described, and the role of Doppler US is demonstrated in first-trimester screening and in the evaluation of growth restriction, anemia, and other causes of fetal compromise in the second and third trimesters. Sampling technique is explained, and normal and abnormal waveforms are illustrated for the ductus venosus, umbilical artery, umbilical vein, middle cerebral artery, and uterine artery. Some examples of clinical cases are provided to illustrate how the results are used in clinical practice. Clinical examples of velamentous insertion and vasa previa are also provided to aid the practicing radiologist with recognition of these entities. In particular, vasa previa is considered a critical finding; it alters pregnancy management, requiring hospital admission, administration of steroid therapy, and planned early cesarean delivery. ©RSNA, 2019.

Magnetic resonance imaging is often misleading when used as an adjunct to ultrasound in the management of placenta accreta spectrum disorders.

BACKGROUND: Magnetic resonance imaging is reported to have good sensitivity and specificity in the diagnosis of placenta accreta spectrum disorders, and is often used as an adjunct to ultrasound. But the additional utility of obtaining magnetic resonance imaging to assist in the clinical management of patients with placenta accreta spectrum disorders, above and beyond the information provided by ultrasound, is unknown. OBJECTIVE: We aimed to determine whether magnetic resonance imaging provides data that may inform clinical management by changing the sonographic diagnosis of placenta accreta spectrum disorders. STUDY DESIGN: In all, 78 patients with sonographic evidence or clinical suspicion of placenta accreta spectrum underwent magnetic resonance imaging of the abdomen and pelvis in orthogonal planes through the uterus utilizing T1- and T2-weighted imaging sequences at the University of Utah and the University of Colorado from 1997 through 2017. The magnetic resonance imaging was interpreted by radiologists with expertise in diagnosis of placenta accreta spectrum who had knowledge of the sonographic interpretation and clinical risk factors for placenta accreta spectrum disorders. The primary outcome was a change in diagnosis from sonographic interpretation that could alter clinical management, which was defined a priori. Diagnostic accuracy was verified by surgical and histopathologic diagnosis at the time of delivery. RESULTS: A change in diagnosis that could potentially alter clinical management occurred in 28 (36%) cases. Magnetic resonance imaging correctly changed the diagnosis in 15 (19%), and correctly confirmed the diagnosis in 34 (44%), but resulted in an incorrect change in diagnosis in 13 (17%), and an incorrect confirmation of ultrasound diagnosis in 15 (21%). Magnetic resonance imaging was not more likely to change a diagnosis in the 24 cases of posterior and lateral placental location compared to anterior location (33% vs 37%, P = .84). Magnetic resonance imaging resulted in overdiagnosis in 23% and in underdiagnosis in 14% of all cases. When ultrasound suspected severe disease (percreta) in 14 cases, magnetic resonance imaging changed the diagnosis in only 2 cases. Lastly, the proportion of accurate diagnosis with magnetic resonance imaging did not improve over time (61-65%, P = .96 for trend) despite increasing volume and increasing numbers of changed diagnoses. CONCLUSION: Magnetic resonance imaging resulted in a change in diagnosis that could alter clinical management of placenta accreta spectrum disorders in more than one third of cases, but when changed, the diagnosis was often incorrect. Given its high cost and limited clinical value, magnetic resonance imaging should not be used routinely as an adjunct to ultrasound in the diagnosis of placenta accreta spectrum until evidence for utility is clearly demonstrated by more definitive prospective studies.

Fat-containing Retroperitoneal Lesions: Imaging Characteristics, Localization, and Differential Diagnosis.

The complex anatomy of the retroperitoneum is reflected in the spectrum of neoplastic and nonneoplastic conditions that can occur in the retroperitoneum and appear as soft-tissue masses. The presence of fat within a retroperitoneal lesion is helpful in refining the differential diagnosis. Fat is easily recognized because of its characteristic imaging appearance. It typically is hyperechoic at ultrasonography and demonstrates low attenuation at computed tomography (-10 to -100 HU). Magnetic resonance imaging is a more ideal imaging modality because it has better soft-tissue image contrast and higher sensitivity for depicting (a) microscopic fat by using chemical shift imaging and (b) macroscopic fat by using fat-suppression techniques. Whether a lesion arises from a retroperitoneal organ or from the soft tissues of the retroperitoneal space (primary lesion) is determined by examining the relationship between the lesion and its surrounding structures. Multiple imaging signs help to determine the organ of origin, including the "beak sign," the "embedded organ sign," the "phantom (invisible) organ sign," and the "prominent feeding artery sign." Adrenal adenoma is the most common adrenal mass that contains microscopic fat, while myelolipoma is the most common adrenal mass that contains macroscopic fat. Other adrenal masses, such as pheochromocytoma and adrenocortical carcinoma, rarely contain fat. Renal angiomyolipoma is the most common fat-containing renal mass. Other fat-containing renal lesions, such as lipoma and liposarcoma, are rare. Fatty replacement of the pancreas and pancreatic lipomas are relatively common, whereas pancreatic teratomas are rare. Of the primary retroperitoneal fat-containing lesions, lipoma and liposarcoma are common, while other lesions are relatively rare. (©)RSNA, 2016.

Holoprosencephaly: a survey of the entity, with embryology and fetal imaging.

Structural malformations of the brain are an important cause of childhood mortality and morbidity, with the latter having long-term financial and psychosocial implications for the affected child and family. Holoprosencephaly (HPE) is a severe brain malformation characterized by abnormal cleavage of the prosencephalon in the 5th gestational week. Aprosencephaly and atelencephaly occur earlier because of failure in the formation of the prosencephalon and telencephalon, respectively. The HPE holoprosencephaly spectrum classically includes alobar, semilobar, and lobar forms, although there are no clear-cut defining features. The middle interhemispheric variant (MIH), also known as syntelencephaly, is classified as a variant of HPE holoprosencephaly with midline interhemispheric fusion. Other conditions sometimes included in the spectrum of HPE holoprosencephaly include septo-optic dysplasia (SOD); "minimal" HPE holoprosencephaly , which is associated with subtle craniofacial malformations and mild developmental delay; and microform HPE holoprosencephaly , which by definition excludes brain involvement. The focus of this article will be on the spectrum of findings visible in fetal manifestation of the HPE holoprosencephaly spectrum. Brain embryology; the imaging characteristics, epidemiology, and embryology of HPE; and the more common associated anomalies, particularly those of the face ("the face predicts the brain") are reviewed. Recognition of these anomalies is important for accurate parental counseling, since the prognosis is poor but not invariably lethal; children with the milder forms may live well into their teens with severe developmental delays, endocrine dysfunction, and disrupted homeostasis. Available data on outcome in surviving children are summarized. Illustrative fetal ultrasonographic and magnetic resonance images are presented with clinical, autopsy, and postnatal imaging correlation.

Complex abdominal wall defects: appearances at prenatal imaging.

Abdominal wall defects are a complex group of anomalies, and many are incorrectly diagnosed. Evaluation of the defect relative to the umbilical cord insertion site is fundamentally important in differentiating among the various malformations. The two most common abdominal wall defects are gastroschisis, in which the defect is on the right side of the normally inserting cord and free-floating bowel loops are present, and omphalocele, in which the cord inserts on a membrane-covered midline defect. Omphalocele may also form a portion of a more complex defect that may remain undiagnosed without thorough evaluation. In cloacal exstrophy, the defect extends inferiorly and the bowel loops extrude between the two bladder halves. In pentalogy of Cantrell, the defect extends superiorly and is typically associated with ectopia cordis. Bladder exstrophy is a lower abdominal defect in which the hallmark finding is absence of a fluid-filled bladder. The cord insertion site is normal to low but does not form part of the defect. Both body stalk anomaly and abdominoschisis due to amniotic bands cause severe malformations, often involving extrusion of solid organs and the bowel. Although these two entities have many overlapping features, body stalk anomaly may be recognized on the basis of absence of a free-floating umbilical cord. With use of an algorithmic approach beginning with discovery of the location of the defect, a more precise diagnosis can be determined that may directly affect pre- and postnatal management decisions.

Accuracy of ultrasound for the prediction of placenta accreta.

OBJECTIVE: Ultrasound has been reported to be greater than 90% sensitive for the diagnosis of accreta. Prior studies may be subject to bias because of single expert observers, suspicion for accreta, and knowledge of risk factors. We aimed to assess the accuracy of ultrasound for the prediction of accreta. STUDY DESIGN: Patients with accreta at a single academic center were matched to patients with placenta previa, but no accreta, by year of delivery. Ultrasound studies with views of the placenta were collected, deidentified, blinded to clinical history, and placed in random sequence. Six investigators prospectively interpreted each study for the presence of accreta and findings reported to be associated with its diagnosis. Sensitivity, specificity, positive predictive, negative predictive value, and accuracy were calculated. Characteristics of accurate findings were compared using univariate and multivariate analyses. RESULTS: Six investigators examined 229 ultrasound studies from 55 patients with accreta and 56 controls for 1374 independent observations. 1205/1374 (87.7% overall, 90% controls, 84.9% cases) studies were given a diagnosis. There were 371 (27.0%) true positives; 81 (5.9%) false positives; 533 (38.8%) true negatives, 220 (16.0%) false negatives, and 169 (12.3%) with uncertain diagnosis. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 53.5%, 88.0%, 82.1%, 64.8%, and 64.8%, respectively. In multivariate analysis, true positives were more likely to have placental lacunae (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.4-1.6), loss of retroplacental clear space (OR, 2.4; 95% CI, 1.1-4.9), or abnormalities on color Doppler (OR, 2.1; 95% CI, 1.8-2.4). CONCLUSION: Ultrasound for the prediction of placenta accreta may not be as sensitive as previously described.

Interobserver variability of sonography for prediction of placenta accreta.

OBJECTIVES: The sensitivity of sonography to predict accreta has been reported as higher than 90%. However, most studies are from single expert investigators. Our objective was to analyze interobserver variability of sonography for prediction of placenta accreta. METHODS: Patients with previa with and without accreta were ascertained, and images with placental views were collected, deidentified, and placed in random sequence. Three radiologists and 3 maternal-fetal medicine specialists interpreted each study for the presence of accreta and specific findings reported to be associated with its diagnosis. Investigator-specific sensitivity, specificity, and accuracy were calculated. κ statistics were used to assess variability between individuals and types of investigators. RESULTS: A total of 229 sonographic studies from 55 patients with accreta and 56 control patients were examined. Accuracy ranged from 55.9% to 76.4%. Of imaging studies yielding diagnoses, sensitivity ranged from 53.4% to 74.4%, and specificity ranged from 70.8% to 94.8%. Overall interobserver agreement was moderate (mean κ ± SD = 0.47 ± 0.12). κ values between pairs of investigators ranged from 0.32 (fair agreement) to 0.73 (substantial agreement). Average individual agreement ranged from fair (κ = 0.35) to moderate (κ = 0.53). CONCLUSIONS: Blinded from clinical data, sonography has significant interobserver variability for the diagnosis of placenta accreta.

Comparison of current to past outcomes in congenital diaphragmatic hernia using mri observed-to-expected total fetal lung volume.

BACKGROUND: Fetal Centers use imaging studies to predict congenital diaphragmatic hernia (CDH) prognosis and the need for fetal therapy. Given improving CDH survival, we hypothesized that current fetal imaging severity predictions no longer reflect true outcomes and fail to justify the risks of fetal therapy. METHODS: We analyzed our single-center contemporary data in a left-sided CDH cohort (n = 58) by prognostic criteria determined by MRI observed-to-expected total fetal lung volumes: severe <25%, moderate 25-35%, and mild >35%. We compared contemporary survival to prior studies and the TOTAL trials. RESULTS: Contemporary survival was significantly higher than past studies for all prognostic classifications (mild 100% vs 80-94%, moderate 95% vs 59-75%, severe 79% vs 13-25%; P < 0.01), and to either control or fetal therapy arms of the TOTAL trials. CONCLUSIONS: Current fetal imaging criteria are overly pessimistic and may lead to unwarranted fetal intervention. Fetal therapies remain experimental. Future studies will require updated prognostic criteria.

Ultrasonography of the Explanted Uterus in Placenta Accreta Spectrum: Correlation With Intraoperative Findings and Gross Pathology.

OBJECTIVE: To better understand placenta accreta spectrum (PAS) by correlating postoperative ultrasonographic findings of the explanted uteroplacental interface with intraoperative findings and gross pathology. METHODS: We enrolled consecutive pregnant patients aged 18 years and older with a prior cesarean delivery and antenatal diagnosis of lower uterine segment PAS who planned to undergo hysterectomy into this prospective, descriptive study. All underwent cesarean hysterectomy with standardized intraoperative photography. Ultrasonography of explanted postsurgical uteruses was performed by expert radiologists to obtain standard detailed images of the myometrial-placental interface and other areas of interest. Sagittal views of the gross pathologic specimen were photographed. We correlated the intraoperative, ultrasonographic, and gross pathologic findings as a study team and report four consistent patterns that emerged from this systematic evaluation. RESULTS: Thirty-four consecutive eligible patients were enrolled. The following consistent observations emerged: 1) The uteroplacental interface in the explanted specimen was smooth and distinct. At the point of maximal placental protrusion, the myometrium was imperceptible, but the placenta was confined by a smooth thin echogenic line of uterine serosa (the scar shell) unless surgically disrupted. 2) Every specimen of PAS grade 2-3 showed placenta bulging through the lower uterine segment in the region of prior hysterotomy. 3) Placentas extended to, but not through, the uterovesical interface or scar shell. Dense adhesive disease was found between the placenta and bladder. There were no cases of true bladder invasion. 4) Placental extension beyond the serosa (invasion) has a distinct appearance on postoperative ultrasonography with irregular frond-like protrusion of placental tissue. This appearance was always the result of surgical manipulation and was not present before delivery of the neonate. CONCLUSION: These findings suggest that PAS severity is likely mediated by progressive scar dehiscence and uterine remodeling, not placental invasion. This challenges the existence of in situ invasive percreta as it is currently described.

Cloacal malformation: embryology, anatomy, and prenatal imaging features.

Cloacal 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.

Neurological and clinical outcomes in infants and children with a fetal diagnosis of asymmetric ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum.

OBJECTIVE: Advances in prenatal imaging have facilitated improvements in the fetal diagnosis of congenital anomalies. Asymmetric ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum (AVID) is a constellation of congenital anomalies reported in fetal imaging. However, few data are available regarding postnatal outcomes of infants and children with a fetal diagnosis of AVID. The authors sought to report the neurodevelopmental outcomes of patients diagnosed with AVID before birth at a single institution. METHODS: An institutional fetal imaging database was queried to identify cases with ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum over a 10-year study period from 2000 to 2019. Overall, 41 maternal-infant dyads who met imaging criteria for AVID were identified; medical records were reviewed for prenatal variables including gestational age at birth, perinatal complications including fetal demise, and postnatal variables including demographics, mortality, hydrocephalus diagnosis and management, epilepsy, and neurodevelopmental outcomes at 2 years or the last follow-up. RESULTS: Among 41 patients, 25 (61%) were male. A slight majority of patients (55%) were born before 36 weeks of gestational age, and 27 patients (68%) were delivered via cesarean section because their head size precluded vaginal delivery. There were 8 incidences of fetal demise, 1 pregnancy was terminated, and 32 patients were born alive. Neonatal or early infant death occurred in 5 patients. Two children died during follow-up after the neonatal period (ages 7 months and 7 years). Twenty-six children survived to at least the 2-year follow-up, all of whom required treatment for hydrocephalus. Of those 26 children, 12 (46%) had a diagnosis of epilepsy, 14 (54%) could sit independently, 4 (16%) were in mainstream school, 16 (62%) had expressive language, and 7 (28%) had near-normal development without seizures. CONCLUSIONS: Among 41 maternal-fetal dyads with AVID, a majority of children survived to the 2-year follow-up, although all developed hydrocephalus. Many continued to have seizures, but expressive language use, attendance at mainstream school, and near-normal development without seizures were not infrequent. These data are critical for prenatal counseling and to establish the natural history of a diagnosis with limited outcome data.

Testicular epidermoid cysts: sonographic features with clinicopathologic correlation.

OBJECTIVE: The purpose of this series was to describe the sonographic features of intratesticular epidermoid cysts with clinicopathologic correlation. METHODS: A retrospective review of the sonographic features of all intratesticular epidermoid cysts within the radiologic pathology archive of the Armed Forces Institute of Pathology with correlation with clinical, surgical, and pathologic data was performed. On sonograms, intratesticular epidermoid cysts were evaluated for shape, borders, and the presence of characteristic features, including alternating hypoechoic and hyperechoic rings, mural calcifications, and echogenic central core. Color Doppler imaging was evaluated for the presence of internal flow. RESULTS: Of 21 cysts seen in 20 male patients (mean age, 24 years; range, 11-52 years), the most common finding was mural calcifications, which were seen in 18 lesions (86%). Concentric rings of alternating echogenicity were shown in 13 lesions (62%), and 7 cysts (33%) had an echogenic central core. No cysts showed internal vascularity. CONCLUSIONS: Testicular epidermoid cysts are uncommon solid-appearing testicular masses that usually present as palpable masses and are benign. Knowledge of the sonographic and pathologic features may help differentiate these lesions from malignancy and possibly prevent unnecessary orchiectomy.

The cavum septi pellucidi: why is it important?

OBJECTIVE: The cavum septi pellucidi (CSP) is routinely imaged in the fetal brain during obstetric sonography; in fact, for well over a decade, assessment of the CSP has been considered part of the required elements of a standard examination of fetal morphology in guidelines developed by multiple specialty societies. Our objective is to present the 4 reasons why all practicing sonologists and sonographers should be familiar with this anatomic structure. METHODS: Prenatal sonograms and magnetic resonance imaging examinations are used to review the following topics: terminology, embryology, and anatomy of the CSP; pitfalls in its identification; and a wide variety of abnormalities (predominantly relating to nonvisualization) associated with the CSP. RESULTS: Embryologic development of the CSP is intimately associated with the corpus callosum (CC); thus, correct identification of the CSP essentially excludes complete agenesis of the CC. Absence of the CSP is associated with an extremely wide spectrum of neuroanatomic malformations: these range from the lethal entities of hydranencephaly and alobar holoprosencephaly; to the potentially serious but nonlethal entities of schizencephaly, porencephaly, basilar encephaloceles, severe hydrocephalus, and the less severe prosencephalic cleavage disorders (including syntelencephaly); to the normal variant, the rare and somewhat controversial entity of isolated septal deficiency. The value of noting that the absent CSP allows diagnosis of very subtle and easily overlooked abnormalities such as septo-optic dysplasia is presented. CONCLUSIONS: Correct recognition of the CSP provides welcome reassurance of proper development of the central forebrain.

Placenta Accreta Spectrum Disorder: Uterine Dehiscence, Not Placental Invasion.

For decades, placenta accreta spectrum disorder has been classified, staged, and described as a disorder of placental invasion. In this commentary, we argue that placenta accreta spectrum exists as a disorder of defective decidua and uterine scar dehiscence, not as a disorder of destructive trophoblast invasion. Adopting this understanding of placenta accreta spectrum will help direct research efforts and clinical resources toward the prevention, accurate diagnosis, and safe treatment of this devastating-and increasingly common-disorder.

From the archives of the AFIP: Inflammatory and nonneoplastic bladder masses: radiologic-pathologic correlation.

Although the vast majority of bladder tumors are epithelial neoplasms, a variety of nonneoplastic disorders can cause either focal bladder masses or diffuse mural thickening and mimic malignancy. Some of these entities are rare and poorly understood such as inflammatory pseudotumor, which produces ulcerated, bleeding polypoid bladder masses. These masses may be large and have an extravesical component. Bladder endometriosis manifests as submucosal masses with characteristic magnetic resonance imaging features consisting of hemorrhagic foci and reactive fibrosis. Nephrogenic adenoma has no typical features, and pathologic evaluation is required for diagnosis. Although imaging features of malacoplakia are also nonspecific, characteristic Michaelis-Gutmann bodies are found at pathologic evaluation. The various types of cystitis (cystitis cystica, cystitis glandularis, and eosinophilic cystitis) require pathologic diagnosis. Bladder infection with tuberculosis and schistosomiasis produces nonspecific bladder wall thickening and ulceration in the acute phase and should be suspected in patients who are immunocompromised or from countries where these infections are common. The diagnosis of chemotherapy cystitis and radiation cystitis should be clinically evident, but imaging may be used to determine severity and to assess complications. Extrinsic inflammatory diseases such as Crohn disease and diverticulitis may be associated with fistulas to the bladder and focal bladder wall abnormality. The extravesical findings allow the diagnosis to be made easily. Finally, extrinsic masses arising from the prostate or distal ureter may cause filling defects, which can be confused with intrinsic bladder masses.

From the Archives of the AFIP: neoplasms of the urinary bladder: radiologic-pathologic correlation.

In the United States, primary bladder neoplasms account for 2%-6% of all tumors, with bladder cancer ranked as the fourth most common malignancy. Ninety-five percent of bladder neoplasms arise from the epithelium; the most common subtype is urothelial carcinoma, which accounts for 90% of cases. Squamous cell carcinoma accounts for 2%-15%, with rates varying widely according to geographic location. Adenocarcinoma (primary bladder, urachal, or metastatic) represents less than 2%. Bladder cancer typically occurs in men aged 50-70 years and is related to smoking or occupational exposure to carcinogens. Most urothelial neoplasms are low-grade papillary tumors, which tend to be multifocal and recur but have a relatively good prognosis. High-grade invasive tumors are less common and have a much poorer prognosis. Squamous cell carcinoma and adenocarcinoma occur in the setting of chronic bladder infection and irritation. Mesenchymal tumors represent the remaining 5% of bladder tumors, with the most common types being rhabdomyosarcoma, typically seen in children, and leiomyosarcoma, a disease of adults. Rarer mesenchymal tumors include paraganglioma, lymphoma, leiomyoma, and solitary fibrous tumor. Although imaging findings are not specific for these tumors, patterns of growth and tumor characteristics may allow differentiation. For accurate staging, computed tomography and magnetic resonance imaging are the modalities of choice.