Erika Rubesova

Effectiveness of a Staged US and CT Protocol for the Diagnosis of Pediatric Appendicitis: Reducing Radiation Exposure in the Age of ALARA

PURPOSE To evaluate the effectiveness of a staged ultrasonography (US) and computed tomography (CT) imaging protocol for the accurate diagnosis of suspected appendicitis in children and the opportunity for reducing the number of CT examinations and associated radiation exposure. MATERIALS AND METHODS This retrospective study was compliant with HIPAA, and a waiver of informed consent was approved by the institutional review board. This study is a review of all imaging studies obtained in children suspected of having appendicitis between 2003 and 2008 at a suburban pediatric emergency department. A multidisciplinary staged US and CT imaging protocol for the diagnosis of appendicitis was implemented in 2003. In the staged protocol, US was performed first in patients suspected of having appendicitis; follow-up CT was recommended when US findings were equivocal. Of 1228 pediatric patients who presented to the emergency department for suspected appendicitis, 631 (287 boys, 344 girls; age range, 2 months to 18 years; median age, 10 years) were compliant with the imaging pathway. The sensitivity, specificity, negative appendectomy rate (number of appendectomies with normal pathologic findings divided by the number of surgeries performed for suspected appendicitis), missed appendicitis rate, and number of CT examinations avoided by using the staged protocol were analyzed. RESULTS The sensitivity and specificity of the staged protocol were 98.6% and 90.6%, respectively. The negative appendectomy rate was 8.1% (19 of 235 patients), and the missed appendicitis rate was less than 0.5% (one of 631 patients). CT was avoided in 333 of the 631 patients (53%) in whom the protocol was followed and in whom the US findings were definitive. CONCLUSION A staged US and CT imaging protocol in which US is performed first in children suspected of having acute appendicitis is highly accurate and offers the opportunity to substantially reduce radiation.

Accuracy of MDCT in Predicting Site of Gastrointestinal Tract Perforation

OBJECTIVE The purpose of this study was to prospectively evaluate the accuracy of MDCT for preoperative determination of the site of surgically proven gastrointestinal tract perforations and to determine the most predictive findings in this diagnosis. SUBJECTS AND METHODS We prospectively studied 85 consecutive patients with extraluminal air on MDCT who had surgically proven gastrointestinal tract perforations. All patients underwent surgery within 12 hours after MDCT was performed. Two experienced radiologists, blinded to the surgical diagnosis, reached a consensus prediction of the site of the perforation using the following eight MDCT findings: concentration of extraluminal air bubbles adjacent to the bowel wall, free air in supramesocolic or inframesocolic compartments, extraluminal air in both abdomen and pelvis, focal defect in the bowel wall, segmental bowel-wall thickening, perivisceral fat stranding, abscess, and extraluminal fluid. MDCT imaging results were compared with surgical and pathologic findings. Logistic regression analyses were performed to assess the significance of the different radiologic criteria. RESULTS Analysis of MDCT images was predictive of the site of gastrointestinal tract perforation in 73 (86%) of 85 patients. Logistic regression showed that concentration of extraluminal air bubbles (p < 0.001), segmental bowel wall thickening (p < 0.001), and focal defect of the bowel wall (p = 0.007) were strong predictors of the site of bowel perforation. CONCLUSION MDCT is highly accurate for predicting the site of gastrointestinal tract perforations. Three of eight CT findings significantly correlate with surgical diagnosis.

A continuous heparin infusion does not prevent catheter-related thrombosis in infants after cardiac surgery.

Objective: To determine whether a continuous infusion of heparin reduces the rate of catheter-related thrombosis in neonates and infants post cardiac surgery. Central venous and intracardiac catheters are used routinely in postoperative pediatric cardiac patients. Catheter-related thrombosis occurs in 8% to 45% of pediatric patients with central venous catheters. Design: Single-center, randomized, placebo-controlled, double-blinded trial. Setting: Cardiovascular intensive care unit, university-affiliated childrens hospital. Patients: Children <1 yr of age recovering from cardiac surgery. Interventions: Patients were randomized to receive either continuous heparin at 10 units/kg/hr or placebo. The primary end point was catheter-related thrombosis as assessed by serial ultrasonography. Results: Study enrollment was discontinued early based on results from an interim futility analysis. Ninety subjects were enrolled and received the study drug (heparin, 53; placebo, 37). The catheter-related thrombosis rate in the heparin group, compared with the placebo group, was 15% vs. 16% (p = .89). Subjects in the heparin group had a higher mean partial thromboplastin time (52 secs vs. 42 secs, p = .001), and this difference was greater for those aged <30 days (64 secs vs. 43 secs, p = .008). Catheters in place ≥7 days had both a greater risk of thrombus formation (odds ratio, 4.3; p = .02) and catheter malfunction (odds ratio, 11.2; p = .008). We observed no significant differences in other outcome measures or in the frequency of adverse events. Conclusions: A continuous infusion of heparin at 10 units/kg/hr was safe but did not reduce catheter-related thrombus formation. Heparin at this dose caused an increase in partial thromboplastin time values, which, unexpectedly, was more pronounced in neonates.

Imaging of the articular cartilage in osteoarthritis of the knee joint: 3D spatial-spectral spoiled gradient-echo vs. fat-suppressed 3D spoiled gradient–echo MR imaging

To compare three‐dimensional (3D) spatial‐spectral (SS) spoiled gradient‐recalled acquisition in the steady state (SPGR) imaging with fat‐suppressed 3D SPGR sequences in MR imaging of articular cartilage of the knee joint in patients with osteoarthritis.

MR assessment of normal fetal lung volumes: A literature review

OBJECTIVE Fetal lung volume can be assessed from MR images by planimetric measurement and comparison with normal values. We review 10 MRI articles that report normal fetal lung volumes based on gestational age to assess reproducibility and application of data. CONCLUSION The articles were analyzed for differences in methodology and disparities in reported normal lung volumes by gestational age. Overall, there is substantial variability among studies regarding reported normal fetal lung volumes as measured on MRI.

Fetal bowel anomalies--US and MR assessment.

The technical quality of prenatal US and fetal MRI has significantly improved during the last decade and allows an accurate diagnosis of bowel pathology prenatally. Accurate diagnosis of bowel pathology in utero is important for parental counseling and postnatal management. It is essential to recognize the US presentation of bowel pathology in the fetus in order to refer the patient for further evaluation or follow-up. Fetal MRI has been shown to offer some advantages over US for specific bowel abnormalities. In this paper, we review the normal appearance of the fetal bowel on US and MRI as well as the typical presentations of bowel pathologies. We discuss more specifically the importance of recognizing on fetal MRI the abnormalities of size and T1-weighted signal of the meconium-filled distal bowel.

Gd-Labeled Liposomes for Monitoring Liposome-Encapsulated Chemotherapy: Quantification of Regional Uptake in Tumor and Effect on Drug Delivery

Recently developed sterically stabilized liposomes are used clinically for delivery of anticancer chemotherapy (currently the drug doxorubicin, Doxil®). In investigational drug development they are studied as targeted (by surface attached antibody or receptor ligands) and nonspecific drug delivery strategies for a variety of pathologies (cancer, arthritis, AIDS). Liposomes have also been considered as potential MRI contrast media vehicles, primarily for blood pool enhancement (1) and for contrast enhancement in the diagnosis and characterization of tumors (2–7). However, little work has been aimed at using liposomal MRI contrast material for purposes of image-based tracking of drug delivery of liposome-drug formulations. Intravenously administered liposomes are distributed passively by flowing blood and extravasate, usually slowly, in territories where vascular endothelium is either (a) very leaky due to large intracellular gaps such as in inflammatory zones, tumors and healing wounds; or (b) fenestrated such as liver or spleen. Selective concentration of liposomes in tumors is slow-typically requiring day(s) for maximal accumulation—which imposes certain limitations on strategies for external image-based detection, as well as upon the liposome itself. Non-sterically stabilized liposomes are cleared from the blood within a few hours via the reticuloendothelial system and accumulation in tumor is obviated kinetically. Sterically stabilized liposomes are successful for antitumor application because they remain in the circulation much longer, with plasma half-lives on the order of days, and substantial accumulation in tumor is possible. Similarly for image-based external detection strategies, the use of PET or SPECT tracers bound to liposomes would fail to the short radioactive half-lives of acceptable radionuclides. Consequently, only liposomal-bound CT or MRI contrast media would be viable candidates for this purpose. In the current study, sterically stabilized liposomes labeled with encapsulated GdDTPA-BMA were examined as probes for quantitative tracking of liposomal drug delivery in implanted osteogenic sarcoma model. The purpose of the study was to evaluate dose-response in the context of intravenously administered dose versus the response of R1 accumulation in the tumor.

Magnetic resonance imaging in the prenatal diagnosis of congenital diarrhea

Congenital diarrhea is very rare, and postnatal diagnosis is often made once the condition has caused potentially lethal fluid loss and electrolyte disorders. Prenatal detection is important to improve the immediate neonatal prognosis. We aimed to describe the prenatal ultrasound and magnetic resonance (MRI) imaging findings in fetuses with congenital diarrhea.

Advances in Fetal Imaging

While ultrasound (US) has been a part of prenatal care for almost 40 years, technical progress over the last two decades has resulted in improved image quality and detection rate of congenital anomalies. The past 15 years have also seen the expansion of three-dimensional (3D) US, providing enhancements over with 2D US, and more realistic images of babies to parents and providers. Fetal magnetic resonance imaging (MRI) was first performed over 30 years ago, and has undergone major technical improvement over the past 15 to 20 years. Fetal MRI complements US by providing better visualization in the fetus when US is limited such as in oligohydramnios or severe maternal obesity. It offers a larger field of view and better tissue contrast than US and is not limited by shadowing from osseous structures. However, MRI has a limited resolution compared with US, is less readily available, and more expensive. While indications for fetal MRI have been clearly established for some abnormalities, such as neurological anomalies, other indications especially for fetal body imaging are not as clearly defined. In this article, we discuss recent developments in fetal MRI and 3D US and their common and newest indications.

Prediction of neonatal respiratory distress in pregnancies complicated by fetal lung masses

The objective of this article is to evaluate the utility of fetal lung mass imaging for predicting neonatal respiratory distress.