Thin collagen film scaffolds for retinal epithelial cell culture

Collagen films have been used in biological implantation and surgical grafts. The development of thin collagen films on the order of 10 microm thick that ensure a planar distribution of implanted cells is a necessary step towards surgical grafts for treatment of age-related macular degeneration (AMD). Here, collagen films were manufactured on a Teflon support to a thickness of 2.4+/-0.2 microm, comparable to that of native Bruch's membrane. Because one important function of Bruch's membrane is allowing the flow of nutrients and waste to and from the retinal pigment epithelium the diffusion properties of the collagen films were studied using blind-well chambers. The diffusion coefficient of the collagen film was determined to be 4.1 x 10(-10)cm(2)/s for 71,200 Da dextran molecules. Viability studies utilizing the blind-well chambers also confirmed that nutrient transport through the films was sufficient to sustain retinal pigment epithelial (RPE) cells. The films were bioassayed in a RPE cell culture model to confirm cell attachment and viability. RPE cells were shown to form an epithelial phenotype and were able to phagocytize photoreceptor outer segments.     

The internet as a potential source of information about radiological procedures for patients

The purposes of this study were to determine what percentage of patients in a typical radiology outpatient setting own or have access to a computer with internet capabilities and how many of these patients would find an educational radiology website useful. During a 3-month period, surveys were given to all adult outpatients undergoing computed tomography. The survey asked 4 questions: (1) Do you own a computer?, (2) If you own a computer, does it have Internet access?, (3) If you do not own a computer, do you have access to a computer with Internet capabilities?, and (4) If we provide helpful information regarding preparation for and the conduct of various radiological procedures on the Internet, would you use it? Four hundred surveys were collected. Two hundred one of the respondents (50.3%) owned a computer; 189 of the 201 (94.0%) had Internet access on their computer or had access to another computer with Internet capabilities. One hundred ninety-nine of the 400 respondents (49.8%) did not own a computer, 57 of these (28.6%) had access to a computer and the Internet. Of the 246 of those with Internet access, 205 (83.3%) indicated that they would use a website that provided helpful information regarding radiological examinations. The Internet is an excellent resource for educational information for patients about various radiological procedures. This study showed that 61.5% of patients had access to the Internet, and 83.3% of these would use such a site. It is likely that these numbers will increase with the rapid growth of the Internet and the steadily increasing number of homes with computers.Key words: computers, education, Internet     

Rett syndrome: an eye‐tracking study of attention and recognition memory

Aim

The aim of this study was to examine attention and recognition memory for faces and patterns in Rett syndrome, a severely disabling neurodevelopmental disorder caused by mutations in the X‐linked MECP2 gene.

Method

Because Rett syndrome impairs speech and hand use, precluding most neuropsychological testing, the visual paired‐comparison paradigm (VPC) was used, together with eye tracking. In the VPC, two identical stimuli are presented for familiarization. On test, the familiar stimulus and a new one are paired, and recognition inferred from preferential looking to the novel target. Attention is measured by looking time, gaze dispersion, and number/length of fixations. Twenty‐seven female patients with Rett syndrome (mean age 10y 6mo; SD 6y 8mo, age range 2–22y) from the Rett clinic at a children's hospital were assessed in this study, along with 30 age‐ and sex‐matched typically developing participants (outpatients from the same hospital).

Results

Although patients with Rett syndrome showed recognition of both faces and patterns, with novelty scores greater than chance (50%), their performance was significantly poorer than that of the typically developing comparison group. Their attention to both was less mature and marked by a more narrowly focused gaze, with fewer and longer fixations. When inspecting faces, attention to the eyes was similar in both groups; however, patients with Rett syndrome tended to ignore the nose and mouth.

Interpretation

This is one of the first studies to characterize attention and memory in individuals with Rett syndrome. Visually based techniques, such as the VPC, open a new avenue for quantifying the cognitive phenotype associated with this syndrome.     

Periadventitial dissection of the superior mesenteric artery for locally advanced pancreatic cancer: Surgical planning with the “halo sign” and “string sign”

Most patients diagnosed with pancreatic cancer are classified as nonoperative candidates based on the contemporary guidelines of resectability. The advent of more potent control of systemic disease using neoadjuvant chemotherapy has enabled more aggressive operative interventions. In our multidisciplinary practice, patients with Stage III, locally advanced pancreatic cancer and superior mesenteric artery (SMA) encasement are now carefully triaged with high quality, preoperative imaging to determine if they can be considered candidates for operative resection with periadventitial dissection of the SMA. Patients displaying a “halo sign,” where the encased SMA remains fully patent and free from arterial invasion, are now candidates for SMA periadventitial dissection. This procedure involves the surgical stripping of the infiltrated neurolymphatic tissue off the SMA leaving behind a bare “skeletonized artery.” Alternatively, the “string sign” involving the SMA confers a more likely case of arterial invasion, where a complete oncologic resection cannot be achieved successfully. This method of patient selection in case of SMA involvement abandons the traditional metrics of circumferential degrees of the arterial encasement to guide surgical decisions. Our institutional approach has allowed us to meaningfully expand our operative methods of resection with the potential for improved longitudinal outcomes to pancreatic cancer patients who were deprived historically from the more effective and possibly curative treatment.     

Mesenteric CT angiography: a discussion of techniques and selected applications

Sixty-four slice MDCT with advanced three-dimensional (3D) visualization software provides a unique opportunity for noninvasive evaluation of the mesenteric vasculature. Although standard axial computed tomography (CT) scanning has always allowed identification of the mesenteric arteries and veins, it is limited in its ability to adequately image small branches and complex anatomy. However, the submillimeter collimation possible with 64-slice CT scanners now allows the acquisition of true isotropic data and therefore high spatial resolution is now maintained in any imaging plane. This ability to visualize the mesenteric vasculature in real-time using 3D rendering and multiplanar reconstruction is crucial for comprehensive review of the complex mesenteric vessels. In this article, we discuss CT scanning protocols and 3D imaging techniques that can be utilized for CT angiography of the mesenteric vessels. Additionally, we will discuss several key conditions that illustrate the value of 3D imaging over standard axial images in mesenteric CT angiography.     

Thin section dual-phase multidetector-row computed tomography detection of peritoneal metastases in gynecologic cancers

PURPOSE: To determine the sensitivity, specificity, and accuracy of multidetector-row computed tomography (CT) using thin sections and multiplanar reconstruction for the detection of peritoneal implants in patients with ovarian cancer. METHOD: Seventeen thin section dual-phase multidetector-row CT scans were performed on 17 women with potential peritoneal metastases from ovarian cancer, which scans were then followed by surgery. Axial and multiplanar images from the CT scans were reviewed by 2 observers, and the results were compared with the operative and clinical notes. RESULTS: Peritoneal metastases were detected by both readers in all 7 patients presenting with ovarian cancer and disease at laparotomy. Metastases were detected in 5/6 patients with recurrent tumor by observer 1 and in 4/6 patients by observer 2. Sensitivity, specificity, and accuracy for detecting peritoneal metastases at individual sites in the abdomen and pelvis were improved when both axial and multiplanar images were reviewed. Sensitivities were highest for the paracolic gutters and infracolic omentum (>70%). Approximately 50% of liver and diaphragmatic lesions were detected. Specificities approached 100% for all sites and accuracies were >80% for most sites of disease. CONCLUSION: The sensitivity, specificity, and accuracy of CT for peritoneal metastases in patients is high using thin slices and axial and multiplanar review of the data.     

Current role of CT in imaging of the stomach.

Recent advances in computed tomographic (CT) technology and three-dimensional (3D) imaging software have sparked renewed interest in using CT to evaluate gastric disease. Multidetector row CT scanners allow thinner collimation, which improves the visualization of subtle tumors as well as the quality of the 3D data sets. When water is used as an oral contrast agent, subtle disease is easier to visualize, especially when a rapid contrast material bolus is intravenously administered. Adenocarcinoma is the most common gastric malignancy and typically appears as focal or segmental wall thickening or a discrete mass. Gastric lymphoma can have a CT appearance similar to that of adenocarcinoma. Both gastric adenocarcinoma and lymphoma may be associated with adenopathy. Gastrointestinal stromal tumors (GISTs) tend to appear as well-defined masses that arise from the gastric wall and may be exophytic when large. GISTs are usually not associated with significant adenopathy. In addition to gastric malignancies, CT can also help detect inflammatory conditions of the stomach, including gastritis and peptic ulcer disease. CT angiography is especially helpful for depicting the gastric vasculature, which may be affected by a variety of disease conditions. Copyright RSNA, 2003.     

Distinction of long bone stress fractures from pathologic fractures on cross-sectional imaging: how successful are we?

OBJECTIVE: The objectives of our study were to define CT and MRI features that distinguish pathologic fractures from stress fractures and to compare the performance of CT and MRI with radiography. MATERIALS AND METHODS: Two reviewers retrospectively reviewed 45 MR images, 37 CT scans, and 43 radiographs in 59 patients (30 biopsy-proven pathologic fractures and 29 stress fractures followed to resolution). The features observed on MRI were abnormal bone marrow (well-defined, ill-defined); intracortical, periosteal, or muscle T1 or T2 signal; endosteal scalloping; and a soft-tissue mass. The features seen on CT were marrow abnormality and character (well-defined, ill-defined, permeative, moth-eaten), endosteal scalloping, periosteal reaction (benign, aggressive), and a soft-tissue mass. Reviewers rated their confidence for diagnosing a pathologic fracture on a 1-3 scale (< 50%, 50-95%, > 95% sure, respectively) with each technique. Performance of each technique was defined by reviewer accuracy and area under the receiver operating characteristic curve (Az); the frequency with which the MRI and CT features were associated with pathologic and stress fractures was calculated. RESULTS: For both reviewers, accuracy for differentiating pathologic from stress fractures was highest on MRI (accuracy/Az: reviewer 1, 98%/0.97; reviewer 2, 93%/0.99); CT (reviewer 1, 88%/0.83; reviewer 2, 82%/0.90) was less accurate than radiography (reviewer 1, 94%/0.98; reviewer 2, 88%/0.96). On MRI, pathologic fractures compared with stress fractures exhibited well-defined T1 marrow signal (83% vs 7%, respectively; p < 0.001), endosteal scalloping (58% vs 0%, p < 0.001), muscle signal (83% vs 48%, p = 0.026), and a soft-tissue mass (67% vs 0%, p < 0.001). On CT, pathologic fractures compared with stress fractures exhibited marrow abnormality (84% vs 17%, respectively; p = 0.001), endosteal scalloping (44% vs 0%, p = 0.006), and aggressive periosteal reaction (36% vs 0%, p = 0.04). CONCLUSION: MRI is useful for distinguishing pathologic from stress fractures, especially after inconclusive radiographic findings. Specifically, pathologic fractures exhibit well-defined T1 marrow alterations, endosteal scalloping, and adjacent soft-tissue abnormalities.