Assignment of opsonic values to pneumococcal reference serum 007sp and a second pneumococcal OPA calibration serum panel (Ewha QC sera panel B) for 11 serotypes.

Pneumococcal conjugate vaccines (PCVs) have been effective in reducing the disease burden caused by Streptococcus pneumoniae. The first licensed PCV (PCV7) was composed of capsular polysaccharides from seven serotypes. This was followed by PCV10, then PCV13, and currently there are a number of higher valency vaccines in development. As part of licensure, new vaccine iterations require assessment of immunogenicity. Since some antibodies can be non-functional, measuring functional antibodies is desirable. To meet this need, opsonophagocytic assays (OPAs) have been developed. Previous studies have shown there can be significant variations in OPA results from different laboratories. We have previously shown that standardizing OPA data using reference serum 007sp can decrease this variation. To extend this approach to additional serotypes, a panel of sera was tested by five laboratories using a multiplexed OPA for serotypes 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F. Each sample was tested in five runs with 007sp tested three times in each run. Results were analyzed using a mixed effects ANOVA model. Standardization of the results significantly decreased the inter-laboratory variation for some serotypes. For serotypes 2, 8, and 11A, the variability was reduced by 40%, 45%, and 40%, respectively. For serotypes 12F, 17F, and 20B, the reductions were more modest (14%, 19%, and 24%, respectively). Standardization had little effect for the remaining serotypes. In many cases, the impact of normalization was blunted by the results from five sera that were collected after an extended post-vaccination interval. We have previously reported consensus values for 007sp for 13 serotypes, as well as the creation of a calibration serum panel ("Ewha Panel A"). Here, we report consensus values for 11 additional serotypes for 007sp and the creation of a second serum panel ("Ewha Panel B"). These consensus values will facilitate the development of next-generation PCVs.

Creation, characterization, and assignment of opsonic values for a new pneumococcal OPA calibration serum panel (Ewha QC sera panel A) for 13 serotypes.

Pneumococcal conjugate vaccines (PCVs) have been very effective in reducing the disease burden caused by Streptococcus pneumoniae serotypes covered by the current vaccine formulations. However, the incidence of disease caused by serotypes not covered by the vaccine is increasing. Consequently, there are active efforts to develop new PCVs with additional serotypes in order to provide protection against the emergent serotypes. Due to costs and ethical issues associated with performing true vaccine efficacy studies, new PCVs are being licensed based on their immunogenicity, which may be assessed with 2 in vitro assays: enzyme-linked immunosorbent assay (ELISA) for quantitating antibody level and opsonophagocytic assay (OPA) for assessing protective function. While a standardized ELISA has been developed, OPA results from different laboratories can be quite disparate, even among laboratories utilizing the same platform. In order to harmonize OPA data, a recent international collaboration assigned opsonic indices to the US Food and Drug Administration (US FDA) reference serum, 007sp, as well as a panel of US FDA calibration sera. However, due to a low number of aliquots, the availability of these calibration sera is extremely limited. Because calibration sera are critical to establish the performance characteristics of an OPA, a second calibration serum panel was created, comprised of 20 sera collected from adults immunized with the 23-valent polysaccharide vaccine, with 150 to 500 aliquots prepared for each serum. In order to establish consensus OPA values of the 20 sera for the 13 serotypes in 13-valent PCV, the sera were tested by 4 laboratories in an international collaborative OPA study. The 007sp results of 1 laboratory deviated significantly from those obtained by the other laboratories, as well as from previously assigned values. Due to these discrepancies, the consensus values for the calibration sera were determined based on the data from the remaining laboratories. Thus, we were able to create a panel of sera with consensus opsonic values that could be used by outside laboratories to calibrate pneumococcal OPAs. Our results also confirmed findings of a previous study that normalization of OPA results significantly reduces interlaboratory variation, with normalization based on 007sp reducing variation by 43% to 74%, depending on serotype.

Artificial luminal narrowing on contrast-enhanced magnetic resonance angiograms on an occasion of stent-assisted coiling of intracranial aneurysm: in vitro comparison using two different stents with variable imaging parameters.

OBJECTIVE: Intracranial stenting for stent-assisted coiling of aneurysms requires adequate follow-up imaging. The aim of this in vitro study was to compare in-stent artificial luminal narrowing on contrast-enhanced MR angiograms (CE-MRA) when applying Neuroform® and Enterprise® stents for stent-assisted coiling. MATERIALS AND METHODS: Two intracranial nitinol stents (Enterprise® and Neuroform®) were placed in silicon tubes and then imaged at 3 T and 1.5 T by the use of a T1-weighted three-dimensional spoiled gradient-echo sequence with minimal TR and TE. CE-MRAs were obtained by using different imaging planes, voxel sizes, and bandwidths, and with or without parallel imaging. Artificial lumen narrowing (ALN) was calculated and the results were compared. RESULTS: Lower magnetic field strength, axial plane perpendicular to axis of stent, and wider bandwidth resulted in a lower ALN on CE-MRA for both stents. Larger voxel size resulted in lower ALN for Neuroform® stent. The parallel imaging acceleration factor did not affect ALN. The mean ALN was lower for Neuroform®, but it was not significant by a paired t test. CONCLUSION: CE-MRA of the stented lumen of vascular phantom was partially impaired with ALN. Consequently, image plane orientation, magnetic field strength, bandwidth, and voxel size should be adjusted appropriately to reduce ALN.

Granulocytic sarcoma of the spine: MRI and clinical review.

OBJECTIVE: Granulocytic sarcoma is a tumor formed by myeloid precursors at an extramedullary site. The purpose of this study was to evaluate the MRI findings and clinical manifestations in 32 cases of granulocytic sarcoma of the spine. MATERIALS AND METHODS: Thirty-two patients (21 males, 11 females; mean age, 32 years) with myeloid leukemia and spinal granulocytic sarcoma were included in this study. All of the patients underwent radiotherapy with chemotherapy, and four patients underwent surgical decompression or excisional biopsy. All 32 patients underwent MRI of the spine; 21 patients underwent follow-up MRI. RESULTS: Nine patients had spinal granulocytic sarcoma in the initial manifestation of leukemia. The other 23 diagnoses were made during a remission or relapse period. The lumbosacral and thoracic portions of the spine were commonly involved. Twenty-seven patients had multiple or contiguous multilevel involvement. According to location, spinal granulocytic sarcoma was classified as epidural in the central spinal canal, epidural along the nerve course, thickening of the nerve root itself, or prevertebral. Lesions were seen as isointense on T1-weighted images and had intermediate signal intensity with homogeneous enhancement on T2-weighted images. Nine patients had complete reduction of the tumor volume, and 12 patients had partial reduction. The median survival period was 9 months, and the 1-year survival rate was 41%. CONCLUSION: Knowledge of the imaging findings of spinal granulocytic sarcoma, which consists of multiple extramedullary masses with diffuse leukemic bone marrow infiltration, can lead to early diagnosis and appropriate treatment to reduce neurologic symptoms.

Significance of nipple enhancement of Paget's disease in contrast enhanced breast MRI.

PURPOSE: To evaluate significance of nipple enhancement of Paget's disease in contrast enhanced (CE) breast MRI. METHODS: Ten patients of biopsy proven Paget's disease were included in this study. Preoperative mammogram and ultrasonogram (US) were obtained in all 10 patients, and 8 patients underwent CE breast MRI prior to surgery. Mammographic and US findings were reviewed retrospectively. On MRI, morphology (flattening or asymmetry or thickening) and enhancement of pathologically involved nipple were analyzed comparing with the opposite side, and also reviewed the abnormal enhancing lesion in the breast parenchyma. RESULTS: Morphologic changes of the nipple were detected in 2 out of 10 patients by mammogram and 6 out of 10 patients by US. On MRI, morphologic change was also revealed in 7 patients and abnormal enhancement of involved nipple was observed in all 8 patients. Associated parenchymal enhancing lesions were proved to be DCIS (7 out of 10) and invasive ductal carcinoma (2 out of 10). Remaining one patient had no underlying breast parenchymal malignancy. CONCLUSION: CE breast MRI allows for the correct detection of nipple involvement of Paget's disease even when clinical information or mammographic/US findings are not provided.

Necrotizing fasciitis versus pyomyositis: discrimination with using MR imaging.

OBJECTIVE: We wanted to evaluate the MR findings for differentiating between necrotizing fasciitis (NF) and pyomyositis (PM). MATERIALS AND METHODS: The MR images of 19 patients with surgically confirmed NF (n = 11) and pathologically confirmed PM (n = 8) were retrospectively reviewed with regard to the presence or absence of any MRI finding criteria that could differentiate between them. RESULTS: The patients with NF had a significantly greater prevalence of the following MR findings (p < 0.05): a peripheral band-like hyperintense signal in muscles on fat-suppressed T2-weighted images (73% of the patients with NF vs. 0% of the patients with PM), peripheral band-like contrast enhancement (CE) of muscles (82% vs. 0%, respectively) and thin smooth enhancement of the deep fascia (82% vs. 13%, respectively). The patients with PM had a significantly greater prevalence of the following MRI findings (p < 0.05): a diffuse hyperintense signal in muscles on fat-suppressed T2-weighted images (27% of the patients with NF vs. 100% in the patients with PM), diffuse CE of muscles (18% vs. 100%, respectively), thick irregular enhancement of the deep fascia (0% vs. 75%, respectively) and intramuscular abscess (0% vs. 88%, respectively). For all patients with NF and PM, the superficial fascia and muscle showed hyperintense signals on T2-weighted images and CE was seen on fat-suppressed CE T1-weighted images. The subcutaneous tissue and deep fascia showed hyperintense signals on T2-weighted images and CE was seen in all the patients with NF and in seven (88%) of the eight patients with PM, respectively. CONCLUSION: MR imaging is helpful for differentiating between NF and PM.