Laser Microdissection: A Review of an Excellent Tool in Molecular Analysis

Abstract

Molecular analysis of any type can be a labor-intensive, expensive technique. Despite the expense and time, molecular methods are becoming the norm in research and clinical laboratories. While performing these methods, laboratory personnel often seek ways to increase the specificity of the assay and the purity of the sample. Laser microdissection may provide the answer. Laser microdissection is a great tool that improves molecular analysis results. Laser microdissection can eliminate the multiple cell types obtained from homoaenization and extraction methods. It allows the acquisition of specific cell types with minimal or no contamination from adjacent cells, and it eliminates the need for manual microdissection. Today, laser microdissection gives us several method options to capture an individual cell or a group of cells and is much easier than the manual cell dissection methods previously used. (The J Histotechnol 28:235, 2005)

Submitted November 14, 2005; accepted with revisions December 5, 2005     

The Cancer Imaging Archive (TCIA): Maintaining and Operating a Public Information Repository

The National Institutes of Health have placed significant emphasis on sharing of research data to support secondary research. Investigators have been encouraged to publish their clinical and imaging data as part of fulfilling their grant obligations. Realizing it was not sufficient to merely ask investigators to publish their collection of imaging and clinical data, the National Cancer Institute (NCI) created the open source National Biomedical Image Archive software package as a mechanism for centralized hosting of cancer related imaging. NCI has contracted with Washington University in Saint Louis to create The Cancer Imaging Archive (TCIA)—an open-source, open-access information resource to support research, development, and educational initiatives utilizing advanced medical imaging of cancer. In its first year of operation, TCIA accumulated 23 collections (3.3 million images). Operating and maintaining a high-availability image archive is a complex challenge involving varied archive-specific resources and driven by the needs of both image submitters and image consumers. Quality archives of any type (traditional library, PubMed, refereed journals) require management and customer service. This paper describes the management tasks and user support model for TCIA.     

Quantitative Imaging Biomarkers: The Application of Advanced Image Processing and Analysis to Clinical and Preclinical Decision Making

The importance of medical imaging for clinical decision making has been steadily increasing over the last four decades. Recently, there has also been an emphasis on medical imaging for preclinical decision making, i.e., for use in pharamaceutical and medical device development. There is also a drive towards quantification of imaging findings by using quantitative imaging biomarkers, which can improve sensitivity, specificity, accuracy and reproducibility of imaged characteristics used for diagnostic and therapeutic decisions. An important component of the discovery, characterization, validation and application of quantitative imaging biomarkers is the extraction of information and meaning from images through image processing and subsequent analysis. However, many advanced image processing and analysis methods are not applied directly to questions of clinical interest, i.e., for diagnostic and therapeutic decision making, which is a consideration that should be closely linked to the development of such algorithms. This article is meant to address these concerns. First, quantitative imaging biomarkers are introduced by providing definitions and concepts. Then, potential applications of advanced image processing and analysis to areas of quantitative imaging biomarker research are described; specifically, research into osteoarthritis (OA), Alzheimer's disease (AD) and cancer is presented. Then, challenges in quantitative imaging biomarker research are discussed. Finally, a conceptual framework for integrating clinical and preclinical considerations into the development of quantitative imaging biomarkers and their computer-assisted methods of extraction is presented.     

Image Quality in Real-Time Teleultrasound of Infant Hip Exam Over Low-Bandwidth Internet Links: a Transatlantic Feasibility Study

Evolution of communication systems, especially internet-based technologies, has probably affected Radiology more than any other medical specialty. Tremendous increase in internet bandwidth has enabled a true revolution in image transmission and easy remote viewing of the static images and real-time video stream. Previous reports of real-time telesonography, such as the ones developed for emergency situations and humanitarian work, rely on high compressions of images utilized by remote sonologist to guide and supervise the unexperienced examiner. We believe that remote sonology could be also utilized in teleultrasound exam of infant hip. We tested feasibility of a low-cost teleultrasound system for infant hip and performed data analysis on the transmitted and original images. Transmission of data was accomplished with Remote Ultrasound (RU), a software package specifically designed for teleultrasound transmission through limited internet bandwidth. While image analysis of image pairs revealed statistically significant loss of information, panel evaluation failed to recognize any clinical difference between the original saved and transmitted still images.     

UMMPerfusion: an Open Source Software Tool Towards Quantitative MRI Perfusion Analysis in Clinical Routine

To develop a generic Open Source MRI perfusion analysis tool for quantitative parameter mapping to be used in a clinical workflow and methods for quality management of perfusion data. We implemented a classic, pixel-by-pixel deconvolution approach to quantify T1-weighted contrast-enhanced dynamic MR imaging (DCE-MRI) perfusion data as an OsiriX plug-in. It features parallel computing capabilities and an automated reporting scheme for quality management. Furthermore, by our implementation design, it could be easily extendable to other perfusion algorithms. Obtained results are saved as DICOM objects and directly added to the patient study. The plug-in was evaluated on ten MR perfusion data sets of the prostate and a calibration data set by comparing obtained parametric maps (plasma flow, volume of distribution, and mean transit time) to a widely used reference implementation in IDL. For all data, parametric maps could be calculated and the plug-in worked correctly and stable. On average, a deviation of 0.032 ± 0.02 ml/100 ml/min for the plasma flow, 0.004 ± 0.0007 ml/100 ml for the volume of distribution, and 0.037 ± 0.03 s for the mean transit time between our implementation and a reference implementation was observed. By using computer hardware with eight CPU cores, calculation time could be reduced by a factor of 2.5. We developed successfully an Open Source OsiriX plug-in for T1-DCE-MRI perfusion analysis in a routine quality managed clinical environment. Using model-free deconvolution, it allows for perfusion analysis in various clinical applications. By our plug-in, information about measured physiological processes can be obtained and transferred into clinical practice.     

Estimating contrast agent motion from ultrasound images using an anisotropic diffusion-based optical flow technique

The purpose of this study was to suggest a novel optical flow method to estimate the motion patterns of contrast agents from an ultrasound image. We first recomposed the original image with relative structural and textural parts. We embedded an anisotropic diffusion model into a slightly non-convex total variation-L1 approximation scheme to provide more reliable estimates. An intermediate bilateral filter was adopted after each computation step to prevent over-smoothing effects. Ultrasound data were acquired during continuous injection of contrast agent into a tissue mimicking phantom. The results showed that our method provided robust performance for estimating contrast agent flow patterns.     

Optimisation of radiographic acquisition parameters for direct digital radiography: A systematic review

IntroductionThe objective of this systematic review was to uncover and synthesise all available literature regarding appropriate acquisition parameters for direct digital radiography. It sought to either confirm current practices as optimal, or to uncover practices that may produce more optimised results.MethodsA comprehensive search of published and unpublished literature was undertaken to find studies that evaluated how adjustment of different acquisition parameters affected subjective image quality and patient radiation dose. Eight hundred and fifty-eight studies were retrieved for title and abstract screening. Eighty-nine studies were retrieved for full-text screening, and 23 were included for review and methodological quality screening.ResultsNarrative synthesis of the 23 included studies revealed limited evidence to guide any potential change or acceptance of currently accepted best practice. Meta-analysis was unable to be performed for any of the included studies due to high levels of methodological heterogeneity. A key finding of this review was that the goals of optimisation research varied greatly across the included studies.ConclusionSignificant methodological heterogeneity in the included studies limited the number of clinically relevant findings that would give evidence to an acceptance of, or suggest changes to, currently accepted best practice. Improving consistency in approach across future works of technique optimisation will ensure future systematic reviews will be able to provide strong evidence and meta-analysis will be able to be performed.Implications for clinical practiceThis review highlights that in the literature, studies of optimisation of radiographic acquisition parameters have varying goals. This methodological heterogeneity limits the applicability of systematic reviews and precludes the use of meta-analysis. The authors recommend that a framework for optimisation research be produced as a priority to help improve homogeneity in future research.     

To keep or reject,that is the question - A survey on radiologists and radiographers’ assessments of plain radiography images

IntroductionThis study aimed to survey radiographers and radiologists' assessment of plain radiographs to identify the imaging clinicians’ differences in acceptance of image quality.MethodAn online, questionnaire was distributed among radiographers (n = 116) and radiologists (n = 76) in a hospital trust in Norway, including 30 clinical cases (one image and a short referral text) that were divided into 3 categories; keep, could keep and reject, based on European guidelines. When rejecting, the respondents identified the main reason by ticking a list (positioning, collimation, centering, artifact or exposure error). Group differences were explored using 2-tailed chi-squared test. Inter-subjectivity was measured using Cohen's kappa for multi-rater sample.ResultsIn total, 36% of the radiographers (n = 42) and 14% of the radiologists (n = 14) responded to the survey. Total response rate was 30% (56/192). Analysis showed significant difference between radiographers and radiologists in the categories of Reject (χ² = 6.3, df = 1, p = 0.01), and Could keep (χ² = 6.3, df = 1, p = 0.01), identifying radiologists as keeping more images compared to radiographers. Agreement among radiographers (Cohen's κ: 0,39; 95% CI: 0.30–0.48; p < 0.001) and radiologists (Cohen's κ: 0,23; 95% CI: 0.09–0.37; p < 0.001) respectively, is fair. The most common reason for rejecting an image is suboptimal positioning. Suboptimal collimation constituted 15% of the rejected images among radiographers, compared to 5% among radiologists. Centering, artifacts and exposure error showed quite similar rates as reasons for rejection.ConclusionRadiographers and radiologists seem to agree on the assessment of good quality images, however, radiographers seem more reluctant to accept images of lower quality than radiologists.Implications for practiceFurther research on reasons for differences in image quality assessment between radiographers and radiologists is needed. This could enable reduction in reject rates and increase image quality in conventional X-ray examinations.     

Differentiation between Clear Cell Sarcoma of the Kidney and Wilms' Tumor with CT

ObjectiveClear cell sarcoma of the kidney (CCSK) is the second-most common but extremely rare primary renal malignancy in children after Wilms'' tumor. The aims of this study were to evaluate the imaging features that could distinguish between CCSK and Wilms'' tumor and to assess the features with diagnostic value for identifying CCSK.Materials and MethodsWe reviewed the initial contrast-enhanced abdominal-pelvic CT scans of children with CCSK and Wilms'' tumor between 2010 to 2019. Fifty-eight children (32 males and 26 females; age, 0.3–10 years), 7 with CCSK, and 51 with Wilms'' tumor, were included. The maximum tumor diameter, presence of engorged perinephric vessels, maximum density of the tumor (Tmax) of the enhancing solid portion, paraspinal muscle, contralateral renal vein density, and density ratios (Tmax/muscle and Tmax/vein) were analyzed on the renal parenchymal phase of contrast-enhanced CT. Fisher''s exact tests and Mann-Whitney U tests were conducted to analyze the categorical and continuous variables, respectively. Logistic regression and receiver operating characteristic curve analyses were also performed.ResultsThe age, sex, and tumor diameter did not differ between the two groups. Engorged perinephric vessels were more common in patients in the CCSK group (71% [5/7] vs. 16% [8/51], p = 0.005). Tmax (median, 148.0 vs. 111.0 Hounsfield unit, p = 0.004), Tmax/muscle (median, 2.64 vs. 1.67, p = 0.002), and Tmax/vein (median, 0.94 vs. 0.59, p = 0.002) were higher in the CCSK compared to the Wilms'' group. Multiple logistic regression revealed that engorged vessels (odds ratio 13.615; 95% confidence interval [CI], 1.770–104.730) and Tmax/muscle (odds ratio 5.881; 95% CI, 1.337–25.871) were significant predictors of CCSK. The cutoff values of Tmax/muscle (86% sensitivity, 77% specificity) and Tmax/vein (71% sensitivity, 86% specificity) for the diagnosis of CCSK were 1.97 and 0.76, respectively.ConclusionPerinephric vessel engorgement and greater tumor enhancement (Tmax/muscle > 1.97 or Tmax/vein > 0.76) are helpful for differentiating between CCSK and Wilms'' tumor in children aged below 10 years.     

Pictorial Review of Mediastinal Masses with an Emphasis on Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has become a crucial tool for evaluating mediastinal masses considering that several lesions that appear indeterminate on computed tomography and radiography can be differentiated on MRI. Using a three-compartment model to localize the mass and employing a basic knowledge of MRI, radiologists can easily diagnose mediastinal masses. Here, we review the use of MRI in evaluating mediastinal masses and present the images of various mediastinal masses categorized using the International Thymic Malignancy Interest Group''s three-compartment classification system. These masses include thymic hyperplasia, thymic cyst, pericardial cyst, thymoma, mediastinal hemangioma, lymphoma, mature teratoma, bronchogenic cyst, esophageal duplication cyst, mediastinal thyroid carcinoma originating from ectopic thyroid tissue, mediastinal liposarcoma, mediastinal pancreatic pseudocyst, neurogenic tumor, meningocele, and plasmacytoma.