A Novel Ultrasound-Guided Technique for Hysteroscopic Adhesiolysis in High-Risk Patients.

Hysteroscopy is a common gynecologic surgical procedure. Certain diagnoses, notably intrauterine adhesions and cervical stenosis, make hysteroscopy more complicated because of an increased likelihood of complications. Three patients, 1 with cervical stenosis and 2 with Asherman syndrome, underwent ultrasound (US)-guided adhesiolysis. Access to the uterine cavity was obtained by either direct balloon-aided dilation or the US-guided Seldinger technique, followed by balloon-aided dilation to enter the endometrial cavity and disrupt intrauterine/intracervical adhesions. In this case series, we describe a novel approach of using US-guided balloon dilation to safely and effectively treat intrauterine adhesions and to decrease the risk of perforation.

MDCT and MR Urogram Spectrum of Congenital Anomalies of the Kidney and Urinary Tract Diagnosed in Adulthood.

OBJECTIVE: Congenital anomalies of the kidneys and urinary tract (CAKUT) encompass a spectrum of anomalies that result from genetic, epigenetic, environmental, and molecular signal aberrations at key stages of urinary tract development. CAKUT can be seen incidentally on cross-sectional imaging of the abdomen or can be a cause for adult-onset chronic kidney disease, posing new challenges for nephrologists, urologists, and radiologists. CONCLUSION: Awareness of CAKUT and familiarity with their imaging findings permit optimal patient management and thorough workup to prevent hypertension and progression from CAKUT to renal failure. The purpose of this article is to review the cross-sectional imaging findings of CAKUT that may present in adulthood.

Chronic fibrosing conditions in abdominal imaging.

Chronic fibrosing conditions of the abdomen are relatively poorly understood and involve varied and often multiple organ systems. At histopathologic analysis, they share the unifying features of proliferative fibrosis and chronic inflammation. Different conditions in this group are often found in association with each other and with other fibrosing conditions outside the abdomen. Some of the confusion about these conditions stems from their complex nomenclature, which includes a gamut of alternate terms and eponyms. Many of them can be categorized within two large subgroups: the fibromatoses and immunoglobulin G4 (IgG4)-related disorders. While many of these entities are of uncertain etiology, some, especially the IgG4-associated conditions, appear to have an immune-mediated pathogenesis. Nephrogenic systemic fibrosis, sclerosing peritonitis, and retroperitoneal fibrosis have iatrogenic associations, while some of the fibromatoses are genetically inherited. Imaging differentiation of these conditions is difficult due to considerable overlap in their radiologic findings. However, certain conditions such as penile fibromatosis and sclerosing peritonitis may have unique imaging features that can help the radiologist make the diagnosis. Others such as deep fibromatoses and inflammatory pseudotumor demonstrate fibroproliferative mass formation and cannot be differentiated from neoplastic conditions at imaging. Thus, histopathologic correlation is often required to confirm their diagnosis.

Nanoparticle Contrast-enhanced MRI for Visualization of Retroplacental Clear Space Disruption in a Mouse Model of Placental Accreta Spectrum (PAS).

INTRODUCTION: Prior preclinical studies established the utility of liposomal nanoparticle blood-pool contrast agents in visualizing the retroplacental clear space (RPCS), a marker of normal placentation, while sparing fetuses from exposure because the agent does not cross the placental barrier. In this work, we characterized RPCS disruption in a mouse model of placenta accreta spectrum (PAS) using these agents. MATERIALS AND METHODS: Contrast-enhanced MRI (CE-MRI) and computed tomography (CE-CT) using liposomal nanoparticles bearing gadolinium (liposomal-Gd) and iodine were performed in pregnant Gab3-/- and wild type (WT) mice at day 16 of gestation. CE-MRI was performed on a 1T scanner using a 2D T1-weighted sequence (100×100×600 µm3 voxels) and CE-CT was performed at a higher resolution (70×70×70 µm3 voxels). Animals were euthanized post-imaging and feto-placental units (FPUs) were harvested for histological examination. RPCS conspicuity was scored through blinded assessment of images. RESULTS: Pregnant Gab3-/- mice showed elevated rates of complicated pregnancy. Contrast-enhanced imaging demonstrated frank infiltration of the RPCS of Gab3-/- FPUs. RPCS in Gab3-/- FPUs was smaller in volume, demonstrated a heterogeneous signal profile, and received lower conspicuity scores than WT FPUs. Histology confirmed in vivo findings and demonstrated staining consistent with a thinner RPCS in Gab3-/- FPUs. DISCUSSION: Imaging of the Gab3-/- mouse model at late gestation with liposomal contrast agents enabled in vivo characterization of morphological differences in the RPCS that could cause the observed pregnancy complications. An MRI-based method for visualizing the RPCS would be valuable for early detection of invasive placentation.

Multimodal postpartum imaging of a severe case of Couvelaire uterus.

Objectives: Placental abruption occurs when a normally implanted placenta prematurely separates, causing rupture of decidual spiral arteries and retroplacental hemorrhage. Estimates place the incidence of placental abruption somewhere between 0.22% and 1% of all deliveries. Clinical abruption represents a spectrum from mild to the most severe form, in which blood can extravasate into or through the myometrium, the broad ligament, or the peritoneum, causing the uterus and surrounding structures to take on a blue discoloration. This phenomenon is a clinical entity known as Couvelaire uterus, so named because it was first described by French physician Alexandre Couvelaire in the early 20th century as "uteroplacental apoplexy." Its incidence is difficult to estimate because it has classically been diagnosed only by direct intraoperative visualization. Imaging is not usually indicated in this clinical setting, so radiologic correlation with operative findings has not been previously described. Case presentation: In this report, we discuss the case of a multipara who presented with abdominal pain and vaginal discharge several days after a classical cesarean delivery. Her prolonged and complex clinical course led to evaluation via several radiologic modalities. At first, a focal placenta accreta or retained products of conception were suspected, however these diagnoses did not correlate with the patient's reported intraoperative findings of a clean endometrial cavity or with histopathology that was consistent with massive abruption. Conclusions: The clinical presentation and features identified on multimodal imaging were ultimately most consistent with the patient's intraoperative diagnosis of Couvelaire uterus.

Pre-clinical magnetic resonance imaging of retroplacental clear space throughout gestation.

INTRODUCTION: Visualization of the retroplacental clear space (RPCS) may provide critical insight into the development of abnormally invasive placenta (AIP). In this pre-clinical study, we characterized the appearance of the RPCS on magnetic resonance imaging (MRI) during the second half of gestation using a liposomal gadolinium contrast agent (liposomal-Gd). MATERIALS AND METHODS: Studies were performed in fifteen pregnant C57BL/6 mice at 10, 12, 14, 16, and 18 days of gestation. MRI was performed on a 1T permanent magnet scanner. Pre-contrast and post-contrast images were acquired using T1-weighted gradient-recalled echo (T1w-GRE) and T2-weighted fast spin echo (T2w-FSE) sequences. Animals were euthanized after imaging and feto-placental units harvested for histological examination. Visualization of the RPCS was scored by a maternal-fetal radiologist and quantified by measuring the contrast-to-noise ratio (CNR) on T1w images. Feto-placental features were segmented for analysis of volumetric changes during gestation. RESULTS: Contrast-enhanced T1w images enabled the visualization of structural changes in placental development between days 10-18 of gestation. Although the placental margin on the fetal side was clearly visible at all time points, the RPCS was partially visible at day 10 of gestation, and clearly visible by day 12. Hematoxylin and eosin (H&E) staining of the placental tissue corroborated MRI findings of structural and morphological changes in the placenta. CONCLUSIONS: Contrast-enhanced MR imaging using liposomal-Gd enabled adequate visualization of the retroplacental clear space starting at day 12 of gestation. The agent also enabled characterization of placental structure and morphological changes through gestation.

Pre-clinical evaluation of a nanoparticle-based blood-pool contrast agent for MR imaging of the placenta.

INTRODUCTION: Non-invasive 3D imaging that enables clear visualization of placental margins is of interest in the accurate diagnosis of placental pathologies. This study investigated if contrast-enhanced MRI performed using a liposomal gadolinium blood-pool contrast agent (liposomal-Gd) enables clear visualization of the placental margins and the placental-myometrial interface (retroplacental space). Non-contrast MRI and contrast-enhanced MRI using a clinically approved conventional contrast agent were used as comparators. MATERIALS AND METHODS: Studies were performed in pregnant rats under an approved protocol. MRI was performed at 1T using a permanent magnet small animal scanner. Pre-contrast and post-liposomal-Gd contrast images were acquired using T1-weighted and T2-weighted sequences. Dynamic Contrast enhanced MRI (DCE-MRI) was performed using gadoterate meglumine (Gd-DOTA, Dotarem®). Visualization of the retroplacental clear space, a marker of normal placentation, was judged by a trained radiologist. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated for both single and averaged acquisitions. Images were reviewed by a radiologist and scored for the visualization of placental features. Contrast-enhanced CT (CE-CT) imaging using a liposomal CT agent was performed for confirmation of the MR findings. Transplacental transport of liposomal-Gd was evaluated by post-mortem elemental analysis of tissues. Ex-vivo studies in perfused human placentae from normal, GDM, and IUGR pregnancies evaluated the transport of liposomal agent across the human placental barrier. RESULTS: Post-contrast T1w images acquired with liposomal-Gd demonstrated significantly higher SNR (p = 0.0002) in the placenta compared to pre-contrast images (28.0 ± 4.7 vs. 6.9 ± 1.8). No significant differences (p = 0.39) were noted between SNR in pre-contrast and post-contrast liposomal-Gd images of the amniotic fluid, indicating absence of transplacental passage of the agent. The placental margins were significantly (p < 0.001) better visualized on post-contrast liposomal-Gd images. DCE-MRI with the conventional Gd agent demonstrated retrograde opacification of the placenta from fetal edge to the myometrium, consistent with the anatomy of the rat placenta. However, no consistent and reproducible visualization of the retroplacental space was demonstrated on the conventional Gd-enhanced images. The retroplacental space was only visualized on post-contrast T1w images acquired using the liposomal agent (SNR = 15.5 ± 3.4) as a sharply defined, hypo-enhanced interface. The retroplacental space was also visible as a similar hypo-enhancing interface on CE-CT images acquired using a liposomal CT contrast agent. Tissue analysis demonstrated undetectably low transplacental permeation of liposomal-Gd, and was confirmed by lack of permeation through a perfused human placental model. CONCLUSIONS: Contrast-enhanced T1w-MRI performed using liposomal-Gd enabled clear visualization of placental margins and delineation of the retroplacental space from the rest of the placenta; the space is undetectable on non-contrast imaging and on post-contrast T1w images acquired using a conventional, clinically approved Gd chelate contrast agent.

Magnetic resonance imaging of female urethral and periurethral disorders.

This article reviews the normal anatomy of the female urethra, magnetic resonance (MR) imaging techniques, and the role of MR imaging in the evaluation of diverse urethral and periurethral diseases. Salient MR imaging findings of common and uncommon cystic urethral lesions (urethral diverticulum, Skene cyst, and vaginal cysts), and masses (urethral carcinoma, leiomyoma, melanoma, fibroepithelial polyp, caruncle, and mucosal prolapse) are presented. The evolving role of dynamic MR in the evaluation of stress urinary incontinence is reviewed.