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Judy Yee

Publications and source records attributed to Judy Yee.

9 recordsLinked to original sources
PubMed2003

Comparison of supine and prone scanning separately and in combination at CT colonography.

PURPOSE: To compare colonic distention, adequacy of colonic preparation, and colorectal polyp detection as assessed with supine and prone scanning separately and in combination at computed tomographic (CT) colonography. MATERIALS AND METHODS: CT colonography and colonoscopy were performed in 182 patients. Distention and preparation of eight colonic segments were rated separately on a scale of 1-4 (1, segment completely distended or no residual material; 4, segment collapsed or large amounts of residual material). The distention, preparation, and polyp detection data were compared with regard to each position alone and then in combination. CT findings were correlated with colonoscopic findings. RESULTS: The percentage of colonic segments with grade 1 distention and preparation was 93.7% (1,364 of 1,456) and 66.6% (969 of 1,456), respectively, with combined scanning; 86.4% (1,258 of 1,456) and 52.1% (759 of 1,456), respectively, with supine scanning alone; and 85.6% (1,246 of 1,456) and 57.1% (831 of 1,456), respectively, with prone scanning alone. The sensitivity for detection of colorectal polyps 10 mm or larger, 5.0-9.9 mm, and smaller than 5 mm and polyps of all sizes was 92.7%, 79.8%, 60.3%, and 69.9%, respectively, with combined scanning. Sensitivity was 58.5%, 47.2%, 36.3%, and 42.1%, respectively, with supine scanning and 51.2%, 41.6%, 30.2%, and 36.3%, respectively, with prone scanning. The improved sensitivities for use of combined versus individual scanning positions were highly significant (P <.001) for polyps in all size categories. CONCLUSION: Colonic distention and preparation at CT colonography were significantly improved by using supine and prone scanning in combination, and results correlated directly with improved sensitivity of polyp detection.

Adult↗
PubMed2003

Computerized tomographic colonography: performance evaluation in a retrospective multicenter setting.

BACKGROUND & AIMS: No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps >or=10 mm in diameter) in a multi-institutional study. METHODS: A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps >or=10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms. RESULTS: The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion >or=10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms. CONCLUSIONS: Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

Colonic Neoplasms↗
PubMed2003

Screening CT colonography.

CT colonography (Virtual Colonoscopy) was first introduced in 1994 as a novel imaging technique for the detection of colorectal polyps and cancer. It is currently proposed as a new screening tool for colorectal carcinoma that may be more acceptable to patients than current methods. There are a growing number of published studies evaluating all aspects of CT colonography, including technique, imaging displays, interpretation methods, patient acceptance, and lesion detection accuracy. While there are multiple studies that have found excellent CT colonography results for the detection of larger polyps in high risk or symptomatic patient cohorts, there are very few published studies evaluating the performance of CT colonography in asymptomatic screening patients. Although we do not have the results of large, randomized, controlled trials documenting the performance of CT colonography in screening-type patients, this technique is currently employed at some sites as a screening tool for colorectal carcinoma. Thus, CT colonography has become a part of the controversy surrounding total body CT screening. In this article, the current techniques for colonic preparation and distention will be discussed, as well as the optimum CT protocol, and the recommended use of image displays for time-efficient interpretation. The results of the larger and newer studies will be presented, as well as some of the current clinical uses of CT colonography. Issues specific to the use of CT colonography as a screening test will also be discussed.

Colonography, Computed Tomographic↗
PubMed2002

Edge displacement field-based classification for improved detection of polyps in CT colonography.

Colorectal cancer can easily be prevented provided that the precursors to tumors, small colonic polyps, are detected and removed. Currently, the only definitive examination of the colon is fiber-optic colonoscopy, which is invasive and expensive. Computed tomographic colonography (CTC) is potentially a less costly and less invasive alternative to FOC. It would be desirable to have computer-aided detection (CAD) algorithms to examine the large amount of data CTC provides. Most current CAD algorithms have high false positive rates at the required sensitivity levels. We developed and evaluated a postprocessing algorithm to decrease the false positive rate of such a CAD method without sacrificing sensitivity. Our method attempts to model the way a radiologist recognizes a polyp while scrolling a cross-sectional plane through three-dimensional computed tomography data by classification of the changes in the location of the edges in the two-dimensional plane. We performed a tenfold cross-validation study to assess its performance using sensitivity/specificity analysis on data from 48 patients. The mean specificity over all experiments increased from 0.19 (0.35) to 0.47 (0.56) for a sensitivity of 1.00 (0.95).

Adult↗
PubMed2002

Quantification of distention in CT colonography: development and validation of three computer algorithms.

Three bowel distention-measuring algorithms for use at computed tomographic (CT) colonography were developed, validated in phantoms, and applied to a human CT colonographic data set. The three algorithms are the cross-sectional area method, the moving spheres method, and the segmental volume method. Each algorithm effectively quantified distention, but accuracy varied between methods. Clinical feasibility was demonstrated. Depending on the desired spatial resolution and accuracy, each algorithm can quantitatively depict colonic diameter in CT colonography.

Algorithms↗