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B J Erickson

Publications and source records attributed to B J Erickson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Evaluating a picture archiving and communications system workstation.

An efficient environment for picture archiving and communications systems (PACS) in the radiology department and throughout a medical practice requires good hardware, good software, and integration of the information sources that exist in a radiology department and institution. This tutorial will describe some of the considerations in evaluating a PACS workstation, with a view to the hardware requirements, user interface designs, and integration with the information systems.

Computer Systems↗
PubMed1999

Chemotherapy for advanced CNS ependymoma.

BACKGROUND: The role of chemotherapy in recurrent ependymoma is poorly defined. This study was performed to help clarify the benefits of chemotherapy in this setting. PATIENTS AND METHODS: We retrospectively reviewed the charts of patients with advanced ependymoma of the CNS who received chemotherapy in our institution between 1974 and 1993, inclusive. Sixteen consecutive patients were treated with regimens containing either nitrosourea, platinum, or other combinations exclusive of nitrosourea or platinum. No patient received nitrosourea and platinum concurrently. Two methods were used to define response. The first was a direct comparison of radiographic images before and after chemotherapy more than one month apart. A second broader definition of response that employed four other criteria in addition to imaging studies (symptoms, signs, performance status, and neurologic functional status) was also used. RESULTS: Results were as follows (response rate by imaging studies followed by response rate by scoring in parenthesis): Platinum-based chemotherapy resulted in a 67% (83%) response rate with 33% (0%) remaining stable. Nitrosourea-based regimens resulted in a 25% (60%) response rate with 50% (10%) remaining stable. When combinations other than platinum or nitrosourea were used, 11% (22%) responded and 56% (44%) remained stable. Relative differences in response rates between chemotherapy regimens persisted when the data were analyzed by grade. Median time to progression was 6, 10, and 3 months, respectively. CONCLUSION: Platinum-based chemotherapy regimens appear to result in higher response rates with lower rates of progression than nitrosourea-based regimens. Other regimens that do not include cisplatinum or nitrosourea appear to be even less effective.

Adolescent↗
PubMed1999

Preliminary comparison of the endoscopic transnasal vs the sublabial transseptal approach for clinically nonfunctioning pituitary macroadenomas.

OBJECTIVE: To assess the advantages and disadvantages of an endoscopic transnasal approach to pituitary surgery for a select group of clinically nonfunctioning macroadenomas and to compare results of this approach with the sublabial transseptal approach at a single institution. PATIENTS AND METHODS: We retrospectively reviewed the records of 26 patients with clinically nonfunctioning pituitary macroadenomas approached endoscopically and 44 matched control patients with the same tumors approached sublabially between January 1, 1995, and October 31, 1997. RESULTS: At baseline, the groups were not significantly different for age, sex distribution, number of comorbid conditions, visual field defects, degree of anterior pituitary insufficiency, or preoperative assessment of tumor volume or invasiveness. Mean (SD) operative times were significantly reduced in the endoscopic group vs the sublabial group: 2.7 (0.7) hours vs 3.4 (0.9) hours (P < .001). Postoperative assessment of surgical resection and postoperative alterations of anterior pituitary function or visual fields were not significantly different between groups, and complication rates were similar in both groups. CONCLUSION: This endoscopic transnasal approach to pituitary resection results in significantly shorter operative time without compromising the extent of tumor resection. The distinct disadvantage of this approach is an off-center view of the sella and a diminished working channel to the sella turcica. For these reasons, the endoscopic approach or its variation is an alternative to the sublabial approach but should be considered only by experienced pituitary neurosurgeons.

Adenoma↗
PubMed1998

Clinician usage patterns of a desktop radiology information display application.

We developed a system for delivering radiologic images and reports to desktop computers used for the electronic medical record (EMR). This system was used by both primary care physicians and specialists primarily in the out-patient setting. The system records all physician interactions with the application to a database. This usage information was then studied in order to understand the value and requirements of an application that could display radiology information (reports and images) on EMR workstations. In this report we describe some of the differences and similarities in usage patterns for the two physician groups. A very high percentage of physicians indicated that having image display capabilities on the workstations was very valuable.

Computer Communication Networks↗
PubMed1998

An algorithm for automatic segmentation and classification of magnetic resonance brain images.

In this article, we describe the development and validation of an automatic algorithm to segment brain from extracranial tissues, and to classify intracranial tissues as cerebrospinal fluid (CSF), gray matter (GM), white matter (WM) or pathology. T1 weighted spin echo, dual echo fast spin echo (T2 weighted and proton density (PD) weighted images) and fast Fluid Attenuated Inversion Recovery (FLAIR) magnetic resonance (MR) images were acquired in 100 normal patients and 9 multiple sclerosis (MS) patients. One of the normal studies had synthesized MS-like lesions superimposed. This allowed precise measurement of the accuracy of the classification. The 9 MS patients were imaged twice in one week. The algorithm was applied to these data sets to measure reproducibility. The accuracy was measured based on the synthetic lesion images, where the true voxel class was known. Ninety-six percent of normal intradural tissue voxels (GM, WM, and CSF) were labeled correctly, and 94% of pathological tissues were labeled correctly. A low coefficient of variation (COV) was found (mean, 4.1%) for measurement of brain tissues and pathology when comparing MRI scans on the 9 patients. A totally automatic segmentation algorithm has been described which accurately and reproducibly segments and classifies intradural tissues based on both synthetic and actual images.

Algorithms↗
PubMed1998

County drift: a type of geographic mobility of chronic psychiatric patients.

This study describes "County Drift," the tendency of chronic psychiatric patients to move from outlying counties to the central county containing the psychiatric hospital. Changes of residence of repeat visitors to a Psychiatric Emergency Service were examined to substantiate that a higher proportion (34.2%) moved to the central county than the reverse (5.3%). An analysis comparing patients who moved to the central county with those who did not showed that patients already connected to treatment and with schizophrenic/psychotic, disorders remained in their home counties. Patients presenting complications reflected by secondary diagnoses of personality or substance use disorders were more likely to relocate to the area of the psychiatric facility.

Adult↗
PubMed1998

Detection of subtle abnormalities on chest radiographs after irreversible compression.

PURPOSE: To assess the effect of wavelet-based compression of posteroanterior chest radiographs on detection of small uncalcified pulmonary nodules and fibrosis. MATERIALS AND METHODS: Computed tomography (CT) of the chest was used to identify 20 patients with normal posteroanterior chest radiographs, 20 with a solitary uncalcified pulmonary nodule 1-2 cm in diameter, and 20 with fibrotic disease. A double-blind protocol for readings of original images and images compressed at 40:1 and 80:1 was analyzed by using the nonparametric receiver operating characteristic to measure differences in diagnostic accuracy and their statistical significance. RESULTS: There was no substantial difference in the overall diagnostic accuracy (measured by the area under the curve index) for both nodules and fibrosis between images compressed at 40:1 and 80:1 and uncompressed images. Readers tended to perform better on images compressed at 40:1 compared with uncompressed images. The "high-sensitivity" portion of the 80:1 compression curve for nodules was below that for the uncompressed curve, although this was not statistically significant. CONCLUSION: Lossy compression of chest radiographs at 40:1 can be used without decreased diagnostic accuracy for detection of pulmonary nodules and fibrosis. There is no statistically significant difference in diagnostic accuracy at 80:1 compression, but detection ability is decreased.

Algorithms↗
PubMed1998

Effects of a stereotactic headframe assembly on proton magnetic resonance spectroscopy.

The effects of a magnetic resonance-compatible stereotactic headframe assembly on single voxel proton magnetic resonance spectroscopy (MRS) were investigated. Multiple stimulated echo acquisition mode (STEAM) spectra were obtained within a commercially available brain metabolite phantom placed within the headframe assembly (Leksell, Model G). All acquisition parameters were kept constant, except voxel location. Maximal distortion occurred for voxels acquired in the immediate vicinity of a headframe fixation pin, manifested by spectral broadening, changes in peak area and height and distortion of the baseline, rendering these acquisitions nondiagnostic. The range of this interaction was short, and a voxel acquired with nearest edge located 2.0 cm or greater from the fixation pin tip produced NAA/Cr, Cho/Cr and mI/Cr ratios differing by less than 7.5% from a spectrum obtained at the phantom center. The feasibility of performing single voxel MRS with a stereotactic headframe in place is demonstrated.

Brain Mapping↗
PubMed1998

The Mayo Clinic-Canadian Cooperative trial of sulfasalazine in active multiple sclerosis.

OBJECTIVE: To determine whether sulfasalazine is better than placebo in slowing disability progression in MS. METHODS: In this randomized, double-blind, placebo-controlled phase III trial, 199 patients with active relapsing-remitting (n = 151) or progressive (n = 48) MS were evaluated at 3-month intervals for a minimum of 3 years (94% completed 3 years of follow-up; mean follow-up, 3.7 years). MRI studies were performed at 6-month intervals on a subset of 89 patients. RESULTS: Sulfasalazine failed to slow or prevent disability progression as measured by the primary outcome (confirmed worsening of the Expanded Disability Status Scale [EDSS] score by at least 1.0 point on two consecutive 3-month visits). Sulfasalazine influenced favorably a number of secondary outcomes during the first 18 months of the trial (e.g., annualized relapse rate, proportion of relapse-free patients; progressive subgroup only: rate of EDSS progression at 1 and 2 years, median time to EDSS progression) but these positive findings were not sustained into the second half of the trial. CONCLUSIONS: Sulfasalazine does not prevent EDSS score progression in the subset of MS patients studied by this protocol. Treatments may improve relapse-related outcomes in MS, at least temporarily, without providing sustained slowing of EDSS progression. Phase III MS trials should be of sufficient length to determine a meaningful impact on disease course.

Adult↗
PubMed1997

Evaluation of irreversible compression of digitized posterior-anterior chest radiographs.

The purpose of this article is to assess lossy image compression of digitized chest radiographs using radiologist assessment of anatomic structures and numerical measurements of image accuracy. Forty posterior-anterior (PA) chest radiographs were digitized and compressed using an irreversible wavelet technique at 10, 20, 40, and 80:1. These were presented in a blinded fashion with an uncompressed image for A-B comparison of 11 anatomic structures as well as overall quality assessments. Mean error, root-mean square (RMS) error, maximum pixel error, and number of pixels within 1% of original value were also computed for compression ratios from ratios from 5:1 to 80:1. We found that at low compression (10:1) there was a slight preference for compressed images. There was no significant difference at 20:1 and 40:1. There was a slight preference on some structures for the original compared with 80:1 compressed images. Numerical measures showed high image faithfulness, both in terms of number of pixels that were within 1% of their original value, and by the average error for all pixels. Our findings suggest that lossy compression at 40:1 or more can be used without perceptible loss in the representation of anatomic structures. On this finding, we will do a receiver-operator characteristic (ROC) analysis of nodule detection in lossy compressed images using 40:1 compression.

Artifacts↗
PubMed1997

Image display for clinicians on medical record workstations.

Image display on electronic medical record (EMR) workstations is an important step in widespread implementation of picture archiving and communications systems (PACS). We describe a pilot project for implementing image display capability that is integrated with the EMR software, and will allow display of images on the physician's workstation. We believe this pilot will provide valuable information about usage patterns in image display needs, which will be valuable in planning further expansion of PACS in our institution.

Data Display↗
PubMed1997

An analytical look at the effects of compression on medical images.

This article will take an analytical look at how lossy Joint Photographic Experts Group (JPEG) and wavelet image compression techniques affect medical image content. It begins with a brief explanation of how the JPEG and wavelet algorithms work, and describes in general terms what effect they can have on image quality (removal of noise, blurring, and artifacts). It then focuses more specifically on medical image diagnostic content and explains why subtle pathologies, that may be difficult for the human eye to discern because of low contrast, are generally very well preserved by these compression algorithms. By applying a wavelet decomposition to the whole image and to specific regions of interest (ROI), and by understanding how the lossy quantization step attenuates signals in those decomposition energy subbands, much can be learned about how tolerant various anatomical structures are to compression. High-frequency anatomical structures that have their energy represented by a few large coefficients (in the wavelet domain) will be well preserved, while, those structures with high frequency energy distributed over numerous smaller coefficients are the most vulnerable to compression. Digitized films showing subtle chest nodules, a subtle stress fracture, and CT and MR images are used to show these results.

Algorithms↗
PubMed1997

READS: a radiology-oriented electronic analysis and display station.

READS is a picture archiving and communications system (PACS) display program that is tailored to allow a radiologist to efficiently perform image review tasks. In this study, the image review process was observed and functional patterns were identified. These were used to define a design that was considered to represent the optimal balance of compromises for a low-cost review station that also allowed easy addition of new functionality. As a result, a program was designed and implemented that has been found to be acceptable for image review and for special image processing function development.

Data Display↗
PubMed1997

A method for rapid computation of maximum intensity projection images.

We describe a method for rapid calculation of maximum intensity projection (MIP) images. The method is applied to 10 example cases with more extensive testing in 1 case. Measurements of calculation time for all 10 cases show good performance (less than 1.2 seconds) for calculating a MIP image that is a very faithful representation of the original (less than 2% of pixels differ from original image). We also demonstrate that the computation time is related linearly to the number of pixels used, allowing arbitrarily rapid computation rates. This technique may be helpful as a navigation aid in evaluation magnetic resonance (MR) angiography data.

Humans↗
PubMed1997

Time study of psychiatric emergency service evaluations.

The study of consultation time at the Psychiatric Emergency Service (PES) can be a valuable guide to allocation of resources in a time of scarcity. Most reports have dealt with the duration of evaluations in the medical emergency room, but more comprehensive PES services use separate space, staff, and 'holding units' to allow proper handling of the psychiatric emergency. The purpose of this study was to determine what factors influence the time course of PES consultations. Consecutive evaluations done at the PES during the first quarter of 1995 (N = 895) were reviewed. Analysis of variance with multiple comparisons and multiple linear regression techniques were used to select out significant variables and quantify their contribution to time of evaluation. Waiting times to receive psychiatric services were longer on day and evening shifts, compared with the night shift. Substance abuse diagnosis, police/ mobile team referral, and the need for emergency medication also lengthened waiting times. Contact time to deliver psychiatric services was longer during the busy evening shift. It was longer if emergency medication had to be administered, if hospitalization had to be provided, or if the patient had past hospitalization history. The duration of psychiatric evaluations was greatly affected by the high acuity patient who may require management of disturbed behavior. This is different from the situation in medical ERs when the low acuity patient has the longest delays. The medical literature describes sources of delay in terms of waiting for lab tests, consults, and computed tomography results, whereas in the PES behavior management fills this role.

Appointments and Schedules↗