Visual Analytics for Hypothesis-Driven Exploration in Computational Pathology.

Recent advances in computational and algorithmic power are evolving the field of medical imaging rapidly. In cancer research, many new directions are sought to characterize patients with additional imaging features derived from radiology and pathology images. The emerging field of Computational Pathology targets the high-throughput extraction and analysis of the spatial distribution of cells from digital histopathology images. The associated morphological and architectural features allow researchers to quantify and characterize new imaging biomarkers for cancer diagnosis, prognosis, and treatment decisions. However, while the image feature space grows, exploration and analysis become more difficult and ineffective. There is a need for dedicated interfaces for interactive data manipulation and visual analysis of computational pathology and clinical data. For this purpose, we present IIComPath, a visual analytics approach that enables clinical researchers to formulate hypotheses and create computational pathology pipelines involving cohort construction, spatial analysis of image-derived features, and cohort analysis. We demonstrate our approach through use cases that investigate the prognostic value of current diagnostic features and new computational pathology biomarkers.

Compressed Adjacency Matrices: Untangling Gene Regulatory Networks.

We present a novel technique-Compressed Adjacency Matrices-for visualizing gene regulatory networks. These directed networks have strong structural characteristics: out-degrees with a scale-free distribution, in-degrees bound by a low maximum, and few and small cycles. Standard visualization techniques, such as node-link diagrams and adjacency matrices, are impeded by these network characteristics. The scale-free distribution of out-degrees causes a high number of intersecting edges in node-link diagrams. Adjacency matrices become space-inefficient due to the low in-degrees and the resulting sparse network. Compressed adjacency matrices, however, exploit these structural characteristics. By cutting open and rearranging an adjacency matrix, we achieve a compact and neatly-arranged visualization. Compressed adjacency matrices allow for easy detection of subnetworks with a specific structure, so-called motifs, which provide important knowledge about gene regulatory networks to domain experts. We summarize motifs commonly referred to in the literature, and relate them to network analysis tasks common to the visualization domain. We show that a user can easily find the important motifs in compressed adjacency matrices, and that this is hard in standard adjacency matrix and node-link diagrams. We also demonstrate that interaction techniques for standard adjacency matrices can be used for our compressed variant. These techniques include rearrangement clustering, highlighting, and filtering.

Rectocele repair by anterolateral rectopexy: long-term functional outcome.

INTRODUCTION: Rectoceles are frequently associated with feelings of pelvic discomfort and symptoms of obstructed defaecation (OD). Repair by a transvaginal or transanal approach might result in de novo dyspareunia in up to approximately 40% of the cases. This study was designed to investigate whether anterolateral rectopexy provides an adequate rectocele repair without dyspareunia as a side effect. METHOD: A consecutive series of 33 women (median age 55 years; range: 37-73) with a symptomatic rectocele (depth > 3 cm) underwent anterolateral rectopexy. Before the operation, all patients underwent evacuation proctography (EP), which was repeated 6 months after the repair in all but three patients. A standardized questionnaire concerning pelvic discomfort, OD and dyspareunia was used to assess the long-term effect of rectocele repair. The response rate was 91%. RESULTS: Six months after the procedure, EP revealed a recurrent or persistent rectocele in six patients (20%). However, in four of these six patients, the depth of the rectocele was < 3 cm. The median duration of follow-up was 74 months (range: 2-96). Among the patients with an adequate repair, signs of OD persisted in 55%. None of the patients encountered de novo dyspareunia after the procedure. CONCLUSION: Anterolateral rectopexy provides an effective tool for anatomical correction of rectoceles and does not result in dyspareunia as a side effect. However, despite adequate repair, OD persist in the majority of patients.

Enterocele repair by abdominal obliteration of the pelvic inlet: long-term outcome on obstructed defaecation and symptoms of pelvic discomfort.

OBJECTIVE: Enterocele is defined as a herniation of the peritoneal sac between the vagina and the rectum. This may contain either sigmoid colon or small bowel. It has been reported that enterocele is associated with obstructed defaecation and symptoms of pelvic discomfort. The aim of the present study was to evaluate the long-term effect of enterocele repair. METHOD: In the time period between 1994 and 2003, 54 women (median age 54 years; range: 31-80) with a symptomatic enterocele underwent obliteration of the pelvic inlet with a U-shaped Mersilene mesh. All patients underwent evacuation proctography (EP), which was repeated 6 months after the repair. In addition, they were contacted over the telephone to assess the long-term effect of enterocele repair. Forty-nine patients were willing to answer questions over the telephone. Five patients were lost to follow-up (response rate: 91%). RESULTS: Six months after the procedure, EP revealed a recurrent or persistent enterocele in five (9%) patients, which was symptomatic in two, both of whom underwent a second repair. Among the 49 patients without an enterocele after 6 months, 10 (23%) women encountered recurrent symptoms of pelvic discomfort at a median follow-up of 85 months (range: 3-137). Despite adequate correction of the enterocele, obstructed defaecation persisted in 21 (75%) patients of 28, who presented with this problem before the procedure. De novo dyspareunia occurred in 5% of the women after the procedure. CONCLUSION: Obliteration of the pelvic inlet with a U-shaped Mersilene mesh provides an effective tool for anatomical correction of enteroceles. However, in the long term one of four patients encounters recurrent symptoms of pelvic discomfort. It seems unlikely that enterocele contributes to obstructed defaecation, as evacuation difficulties persist in around three quarters of the patients.