Biomedical subjects

A B Jani

Publications and source records attributed to A B Jani.

8 recordsLinked to original sources

PubMed2001

Changing face and different countenances of prostate cancer: racial and geographic differences in prostate-specific antigen (PSA), stage, and grade trends in the PSA era.

The purpose of this investigation was to examine changes in pretreatment prostate-specific antigen (PSA), stage, and grade over the past decade as a function of race and geographic region. A multiinstitutional database representing 6,790 patients (1,417 African-American, 5,373 white) diagnosed with nonmetastatic prostate cancer between 1988 and 1997 was constructed. PSA, stage, and grade data were tabulated by calendar year and region, and time trend analyses based on race and region were performed. There was an overall decline of PSA of 0.8%/year, which was significant (P = 0.0001), with a faster rate of decline in African-Americans (1.9%/year) than for whites (0.6%/year). The odds ratio (OR) for a stage shift was 1.09, which was significant (P < 0.0001), and this shift was greater in whites. The OR for an overall grade shift was 1.15, which was significant (P < 0.0001). Although grade and PSA trends were similar for the different regions, there were significant regional differences in stage trends. The implications are that the face of prostate cancer has changed over the past decade; i.e., the distributions of stage, grade, and PSA (the most important prognosticators) have changed. In addition, the countenances of that face are different for whites and African-Americans. For African-Americans, this is good news: the stage, grade, and PSA distributions are more favorable now than before. For whites, the trends are more complex and more dependent on region. These findings should be used for future clinical and health-policy decisions in the screening and treatment of prostate cancer.

Black People↗

PubMed2001

Equivalent racial outcome after conformal radiotherapy for prostate cancer: a single departmental experience.

PURPOSE: African-American (AA) men with prostate cancer present with advanced disease, relative to white (W) men. This report summarizes our clinical and biochemical control (bNED) rates after conformal radiotherapy (RT). In particular, we aim to characterize any race-based outcome differences seen after comparable treatment. PATIENTS AND METHODS: We reviewed 893 patients (418 AA and 475 W) with clinically localized prostate cancer treated between 1988 and 1997. Neoadjuvant hormonal blockade was used in 22.5% of cases, and all patients received conformal RT to a median dose of 68 Gy (range, 60 to 74.8 Gy). Biochemical failure was defined according to the American Society of Therapeutic Radiology and Oncology consensus definition. Median follow-up was 24 months (range, 1 to 114 months). RESULTS: The 5-year actuarial survival, disease-free survival, and bNED rates for the entire population were 80.5%, 70.0%, and 57.6%, respectively. When classified by prognostic risk category, the 5-year actuarial bNED rates were 78.7% for favorable, 57.7% for intermediate, and 39.8% for unfavorable category patients. AA men presented at younger ages and with more advanced disease. Controlled for prognostic risk category, AA and W men had similar 5-year actuarial bNED rates in favorable (78% v 79%, P: = .91), intermediate (52% v 62%, P: =.44), and unfavorable categories (36% v 45%, P: = .09). Race was not an independent prognostic factor (P: = .36). CONCLUSION: Conformal RT is equally effective for AA and W patients. More research is needed in order to understand and correct the advanced presentations in AA men. These data suggest a need for early screening in AA populations.

Actuarial Analysis↗

PubMed2000

Analysis of the role of adjuvant chemotherapy for invasive carcinoma of the esophagus.

The purpose of this report is to analyze the role and optimum integration of chemotherapy for invasive carcinoma of the esophagus in the combined modality setting. The charts of 157 patients with primary invasive nonmetastatic carcinoma of the esophagus treated with curative intent between 1984 and 1998 were reviewed. Various combinations of chemotherapy (C), radiotherapy (R), and surgery (S) were used. Chemotherapy was multiagent (typically 5-fluorouracil [5-FU]/cisplatin/hydroxyurea, 5-FU/cisplatin/leucovorin, or docetaxel/cisplatin) for all but seven patients treated with single agents. The clinical endpoints examined were overall survival (OS) and cause-specific survival (CSS). Multivariate analyses and pairwise comparisons were made for determination of the benefit of chemotherapy. On the multivariate analyses, only American Joint Committee on Cancer stage and chemotherapy were statistically significant determinants of both OS and CSS. Following are the results of the pairwise analyses: 3-year OS: (no C) versus (any C): 16% versus 27% (p = 0.02); (S) versus (C+S): 19% versus 34% (p = 0.35); (R) versus (C+R): 0% versus 13% (p = 0.05); (R + S) versus (C + R + S): 18% versus 33% (p = 0.03). The administration of adjuvant chemotherapy can improve survival in patients with invasive nonmetastatic esophageal carcinoma. This benefit appears to be greater when chemotherapy is given with radiotherapy (with or without surgery) than in the absence of radiotherapy, perhaps because of a radiosensitizing effect not possible when using surgery is the only local control modality.

Adenocarcinoma↗

PubMed2000

Volume rendering quantification algorithm for reconstruction of CT volume-rendered structures: Part I. Cerebral arteriovenous malformations.

Volume rendering is a visualization technique that has important applications in diagnostic radiology and in radiotherapy but has not achieved widespread use due, in part, to the lack of volumetric analysis tools for comparison of volume rendering to conventional visualization techniques. The volume rendering quantification algorithm (VRQA), a technique for three-dimensional (3-D) reconstruction of a structure identified on six principal volume-rendered views, is introduced and described. VRQA involves three major steps: 1) preprocessing of the partial surfaces constructed from each of six volume-rendered images; 2) merging these processed partial surfaces to define the boundaries of a volume; and 3) computation of the volume of the structure from this boundary information. After testing on phantoms, VRQA was applied to CT data of patients with cerebral arteriovenous malformations (AVM's). Because volumetric visualization of the cerebral AVM is relatively insensitive to operator dependencies, such as the choice of opacity transfer function, and because precise volumetric definition of the AVM is necessary for radiosurgical treatment planning, it is representative of a class of structures that is ideal for testing and calibration of VRQA. AVM volumes obtained using VRQA are intermediate to those obtained using axial contouring and those obtained using CT-correlated biplanar angiography (two routinely used visualization techniques for treatment planning for AVM's). Applications and potential expansions of VRQA are discussed.

Algorithms↗

PubMed1999

Volumetric visualization of head and neck CT data for treatment planning.

PURPOSE: To demonstrate the utility of volume rendering, an alternative visualization technique to surface rendering, in the practice of CT based radiotherapy planning for the head and neck. METHODS AND MATERIALS: Rendo-avs, a volume visualization tool developed at the University of Chicago, was used to volume render head and neck CT scans from two cases. Rendo-avs is a volume rendering tool operating within the graphical user interface environment of AVS (Application Visualization System). Users adjust the opacity of various tissues by defining the opacity transfer function (OTF), a function which preclassifies voxels by opacity prior to rendering. By defining the opacity map (OTF), the user selectively enhances and suppresses structures of various intensity. Additional graphics tools are available within the AVS network, allowing for the manipulation of perspective, field of view, data orientation. Users may draw directly on volume rendered images, create a partial surface, and thereby correlate objects in the 3D scene to points on original axial slices. Information in volume rendered images is mapped into the original CT slices via a Z buffer, which contains the depth information (Z coordinate) for each pixel in the rendered view. Locally developed software was used to project conventionally designed GTV contours onto volume rendered images. RESULTS: The lymph nodes, salivary glands, vessels, and airway are visualized in detail without prior manual segmentation. Volume rendering can be used to explore the finer anatomic structures that appear on consecutive axial slices as "points." Rendo-avs allowed for acceptable interactivity, with a processing time of approximately 5 seconds per 256 x 256 pixel output image. CONCLUSIONS: Volume rendering is a useful alternative to surface rendering, offering high-quality visualization, 3D anatomic delineation, and time savings to the user, due to the elimination of manual segmentation as a preprocessing step. Volume rendered images can be merged with conventional treatment planning images to add anatomic information to the treatment planning process.

Head↗

PubMed1999

PSA-based outcome analysis after radiation therapy for prostate cancer: a new definition of biochemical failure after intervention.

OBJECTIVES: To examine pretreatment variables that influence biochemical failure, and to describe and test a new definition of prostate-specific antigen (PSA)-based biochemical failure. METHODS: We introduce and describe a new definition of biochemical failure, which is based on quadratic fitting of the logarithm of the follow-up PSA profile curve. From a data base of 449 patients with prostate cancer treated with definitive radiation therapy, 230 patients who had at least five follow-up PSA observations were chosen for analysis. The new definition of failure was applied to this cohort, as was the conventional definition of two consecutive PSA rises. Univariate and multivariate analyses were performed using established pretreatment prognostic factors as covariates. Also, the association of both definitions of failure with clinical outcome (local recurrence and any recurrence) was examined. RESULTS: Application of the new definition of biochemical failure resulted in smoothing of the "noise" that is inherent in using definitions based on successive PSA rises. This smoothing was verified by smaller P values for the statistically significant covariates in the univariate analysis. Furthermore, the new definition correlated better with clinical outcome, as demonstrated by the statistically significant P values on regression analysis when using the quadratic fitted nadir compared with using the observed nadir. CONCLUSIONS: We devised a new criterion based on quadratic curve fitting for PSA-based biochemical failure. This definition is based on all available PSA information, correlates with both pretreatment factors and post-treatment clinical outcome, is relatively insensitive to noise, and allows for prediction of time of failure.

Humans↗

PubMed1995

MR image classification algorithms for neurosurgical and stereotactic radiosurgical trajectory planning and volumetric analysis.

Neurosurgical and stereotactic radiosurgical trajectory planning involves a phase of image data acquisition followed by localization of tissues to be avoided or crossed during the procedure. Success of the procedure is often assessed during follow-up by performing volumetric analysis of tissues of interest. Both localization and volumetric analysis can be facilitated by classifying the input data into different tissue types. This study compares classification results based on four different input image data: (1) MR data obtained with one TR and TE parameter combination, (2) MR data acquired with eight combinations of TR and TE parameters, (3) input data compressed into four principal components, and (4) the input data (3) together with first- and second-order texture features. The algorithms (a) to reduce the dimensionality using principal components, (b) to generate texture features, (c) to determine feature usefulness in classification using the Wilk's lambda criterion, and (d) to classify the input set are described. Classification results are found to be poor for input data 1 and much improved (qualitatively and quantatively) for input data 2. Input data 3 produces classification results (quantitatively and qualitatively) similar to that of 2. Input data 4 is found to produce quantitative results similar to those of 2 and 3, but the qualitative results show enhanced classification of some tissues and distortion of others.

Algorithms↗

PubMedDate not supplied

Accuracy of object depiction and opacity transfer function optimization in CT volume-rendered images.

Volume rendering is a visualization technique that has important applications in diagnostic radiology and radiotherapy. A methodology is presented for (a) evaluation of the quantitative accuracy of representation of known objects in volume-rendered scenes and for (b) optimization of the opacity transfer function to achieve the most accurate representation of a particular structure. Results using this methodology are shown for structures representing each of the major tissue interfaces and are discussed.

Algorithms↗