Estimating Local Cellular Density in Glioma Using MR Imaging Data

BACKGROUND AND PURPOSE:Increased cellular density is a hallmark of gliomas, both in the bulk of the tumor and in areas of tumor infiltration into surrounding brain. Altered cellular density causes altered imaging findings, but the degree to which cellular density can be quantitatively estimated from imaging is unknown. The purpose of this study was to discover the best MR imaging and processing techniques to make quantitative and spatially specific estimates of cellular density.MATERIALS AND METHODS:We collected stereotactic biopsies in a prospective imaging clinical trial targeting untreated patients with gliomas at our institution undergoing their first resection. The data included preoperative MR imaging with conventional anatomic, diffusion, perfusion, and permeability sequences and quantitative histopathology on biopsy samples. We then used multiple machine learning methodologies to estimate cellular density using local intensity information from the MR images and quantitative cellular density measurements at the biopsy coordinates as the criterion standard.RESULTS:The random forest methodology estimated cellular density with R² = 0.59 between predicted and observed values using 4 input imaging sequences chosen from our full set of imaging data (T2, fractional anisotropy, CBF, and area under the curve from permeability imaging). Limiting input to conventional MR images (T1 pre- and postcontrast, T2, and FLAIR) yielded slightly degraded performance (R² = 0.52). Outputs were also reported as graphic maps.CONCLUSIONS:Cellular density can be estimated with moderate-to-strong correlations using MR imaging inputs. The random forest machine learning model provided the best estimates. These spatially specific estimates of cellular density will likely be useful in guiding both diagnosis and treatment.

Increased cellular density (CD) is a hallmark of cancer and a key feature in histologic glioma analysis.¹ Mapping cellular density throughout a tumor would be a valuable tool to probe how tumors infiltrate and analyze the transition between diseased and healthy brain. However, measuring CD requires tissue, which entails additional risks and is expensive to obtain. There is no currently accepted clinical algorithm to translate imaging data into quantitative assessments of CD.There is great need for a method to estimate CD noninvasively in human patients with gliomas. In this article, we describe the development of such a method using MR imaging data inputs by correlating with multiple biopsy specimens acquired during a prospective human clinical trial. We obtained comprehensive MR imaging, including conventional, diffusion, perfusion, and permeability imaging sequences. We used machine learning approaches to correlate imaging findings with CD measurements from pathology, devised an algorithm to estimate CD from MR imaging inputs, and generated CD maps for the visual display of the predictions. We identified the most informative imaging data subset. This work has multiple applications in the diagnosis and treatment of patients with gliomas: For example, the method can be used to guide biopsy, resection, and surgery and delineate tumor borderzones both pre- and postoperatively.²     

Citation analysis of the most influential articles on traumatic spinal cord injury

Objective: We conducted a citation analysis in order to catalog and pay tribute to the 100 most influential clinical research articles in traumatic spinal cord injury.

Design: The Thomson Reuters Web of Science was searched in a two-step process without time period limitations. Review articles were excluded. In the first stage of data extraction, a Boolean query was used to identify the top 100 most cited clinical papers on traumatic spinal cord injury. One hundred and seven keywords were manually chosen and extracted from titles and abstracts. A second Boolean query used these keywords to broaden search results. The top 100 articles from this second stage search comprised the final list.

Outcome Measures: For each article, measures evaluated were number of citations, average number of citations per year, time elapsed before first citation, and time elapsed until the year in which each article received its respective highest number of citations in a one-year period.

Results: 119,991 articles were found in the second stage search. The top 100 most cited articles meeting inclusion criteria were identified within the first 2,104 results. Archives of Physical Medicine and Rehabilitation was the most represented journal, with 20 of the top 100 articles. The top 100 list averaged 255 citations per article. The most highly cited article was the NASCIS 2 trial by Bracken et al., cited 1500 times, which investigated the efficacy of methylprednisolone or naloxone for spinal cord injury.

Conclusion: Clinical research in traumatic spinal cord injury has grown over time, expanding to encompass rehabilitation and experimental therapies in addition to acute management trials. The list may serve as an archive and reference for further studies in this field.     

Awl versus intravenous cannula stillete in circummandibular wiring��a prospective comparative study

Purpose

The management of paediatric mandibular fractures using an acrylic splint is a time-tested procedure. Traditionally, an awl is used to place wires to secure such splints. In this article, we have designed prospective study to compare a new technique of using intravenous cannula stillete (IVCS) as against conventional awl in placement of the circummandibular wires.

Methods

A total of 45 patients were included in the study. Group I included 22 subjects in whom an awl was used, and group II included 23 subjects in whom IVCS was used for placement of circummandibular wires. Parameters such as post-operative pain, swelling and ease of penetration, size of entry and exit wound and injury to adjacent structures were compared.

Results

Statistically significant reduction in post-operative pain and swelling were noticed in groupie. The operating surgeons experienced greater ease in using IVCS, and the size of the entry and exit wounds were also relatively small as compared to using an awl.

Conclusion

The IVCS, which is disposable, having finer diameter, a sharp bevel and internal wire carrying capacity, clearly demonstrates statistically significant advantages over the usage of a conventional awl.     

Noonan syndrome: a case report

Noonan syndrome is a developmental disorder characterized by facial dysmorphia, short stature, cardiac defects and skeletal malformations. It may be sporadic or inherited as an autosomal dominant or recessive trait and occurs, one in 1,000-2,500 children. This is a case report of a 13 year-old girl who was referred by a general dental practitioner to a pediatric dentist for management. Full mouth dental rehabilitation was done and the child was brought to a dental institution for correction of orofacial and occlusal defects. Multidisciplinary treatment is the key to success in managing children with Noonan syndrome and the pediatric dentists play an important position to lead the health team.     

Spontaneous closure of midline diastema following frenectomy

Maxillary midline diastema is a common aesthetic problem in mixed and early permanent dentitions. The space can occur either as a transient malocclusion or created by developmental, pathological or iatrogenical factors. Many innovative therapies varying from restorative procedures such as composite build-up to surgery (frenectomies) and orthodontics are available. Although literature says every frenectomy procedure should be preceded by orthodontic treatment, we opted for frenectomy technique without any orthodontic intervention. Presented herewith is a case report of a 9-year-old girl with a high frenal attachment that had caused spacing of the maxillary central incisors. A spontaneous closure of the midline diastema was noted within 2 months following frenectomy. The patient was followed up for 4 months after which the space remained closed and there was no necessity for an orthodontic treatment at a later stage.     

A comparison of costs in providing dental care for special needs patients under sedation or general anaesthesia in the North East of England.

OBJECTIVE: To compare the costs of providing dental treatment under general anaesthesia or sedation for special needs patients. METHODS: After a Delphi exercise, a questionnaire was designed, piloted and then sent to nine NHS Trust dental service managers, within the Salaried Dental Services in the North East of England, to obtain information on the costs incurred during the treatment of special needs patients using sedation or general anaesthesia. The questionnaire related to the average number of such patients treated per session, staff costs, depreciation cost for buildings and equipment, and overhead costs including consumables and drugs. RESULTS: All nine dental service managers returned completed questionnaires. The all-inclusive cost for treatment per patient under general anaesthesia ranged from 203.65-479.50 pounds (mean cost: 285.79 pounds) and for sedation from 57.60-153.50 pounds (mean cost: 90.81 pounds). On average three special needs patients were treated per session. The greatest variation in the costs for general anaesthesia was due to staffing costs, which ranged from 1064.10 to 350.00 pounds per session across the Trusts. CONCLUSIONS: In the small number of centres sampled, the cost of delivering dental care under sedation or general anaesthesia was shown to vary widely. Overall, the mean cost of sedation was one-third that of general anaesthesia. However, the cost of both was substantial and cognisance needs to be taken of the costs of such services.     

Fabrication of an auricular prosthesis: a case report

The fabrication of ear prosthesis is considered by many prosthetists to be one of the more difficult replacements in maxillofacial reconstruction. The severe undercuts and pronounced convolutions of the ear's surface present a challenge in simulating a natural proportioned prosthesis. The mould for the ear is generally made by creating a three surface die to reproduce the unique configuration adequately and to allow retrieval of the finished prosthesis without damage. This article presents an outlined procedure in the basic fabrication of a prosthetic ear by a conventional technique where the wax pattern is fabricated from the impression of an individual with a similarly proportioned ear. CLINICAL RELEVANCE: Fabricating an auricular prosthesis may be part of the work of a maxillofacial department.