Biomedical subjects
Publications and source records attributed to William J Kostis.
We report a case of an electrocardiographic artifact simulating atrial flutter in a patient undergoing continuous veno-venous hemodialysis. As end-stage renal disease and hemodialysis are associated with atrial tachyarrhythmias, physicians should be aware of the possibility of such artifacts induced by the dialysis equipment itself.
The pulmonary nodule is the most common manifestation of lung cancer, the most deadly of all cancers. Most small pulmonary nodules are benign, however, and currently the growth rate of the nodule provides for one of the most accurate noninvasive methods of determining malignancy. In this paper, we present methods for measuring the change in nodule size from two computed tomography image scans recorded at different times; from this size change the growth rate may be established. The impact of partial voxels for small nodules is evaluated and isotropic resampling is shown to improve measurement accuracy. Methods for nodule location and sizing, pleural segmentation, adaptive thresholding, image registration, and knowledge-based shape matching are presented. The latter three techniques provide for a significant improvement in volume change measurement accuracy by considering both image scans simultaneously. Improvements in segmentation are evaluated by measuring volume changes in benign or slow growing nodules. In the analysis of 50 nodules, the variance in percent volume change was reduced from 11.54% to 9.35% (p = 0.03) through the use of registration, adaptive thresholding, and knowledge-based shape matching.
PURPOSE: To determine reproducibility of volume measurements of small pulmonary nodules on computed tomographic (CT) scans and to estimate critical time to follow-up CT. MATERIALS AND METHODS: One hundred fifteen pulmonary nodules for which two thin-section small-field-of-view CT scans were obtained and which were stable during 2-year observation were evaluated. A standard group of 94 nodules (with no or minimal artifact) and an expanded group of 105 nodules (including those with moderate artifacts) were examined. Percentage volume change (PVC) and monthly volumetric growth index (MVGI) were computed for each nodule pair. By using estimates of the variation in PVC in stable nodules as a function of initial diameter, critical time to follow-up CT was estimated; this time is the earliest point at which growth in a nodule of a given size can be reliably identified with repeat CT. RESULTS: The SD of PVC decreased with increasing nodule size from 18.5% in 2-5-mm nodules to 10.6% in 5-8-mm nodules and to 7.47% in 8-10-mm nodules. Inclusion of cases with moderate motion artifacts increased the SD of PVC to 27.4% in 2-5-mm nodules, to 17.1% in 5-8-mm nodules, and to 19.3% in 8-10-mm nodules. Critical time to follow-up CT for nodules detected at baseline screening was 12, 5, and 3 months and 1 month for those with initial sizes of 2, 5, 8, and 10 mm, respectively. For nodules detected at annual repeat screening, it was 4 and 3 months and 1 month for nodules that were 3, 4, and 5 mm or larger in size, respectively. Mean MVGI in 94 standard cases was 0.06%, and standard error was 0.21%. CONCLUSION: Factors that affect reproducibility of nodule volume measurements and critical time to follow-up CT include nodule size at detection, type of scan (baseline or annual repeat) on which the nodule is detected, and presence of patient-induced artifacts.
BACKGROUND: The pattern of results in the Mayo Lung Project (MLP), which is the basis for the prevailing recommendations against radiographic screening for lung carcinoma, has led to the assertion that up to 50% of the diagnosed cases of early-stage disease in that trial may have represented overdiagnosed, indolent cases. This finding suggests the possibility of such a high frequency of overdiagnosis in chest radiographic lung carcinoma screening in general. In the current study, the authors analyzed data from the MLP and its counterpart study at Memorial Sloan-Kettering Cancer Center (MSK) to estimate the frequency of overdiagnosis in these studies. METHODS: For the cases diagnosed as Stage I in the MLP and the MSK studies, the doubling times of tumor volumes were calculated. The calculations were based on size measurements recorded by the original investigators from chest radiographs taken during the course of each study. RESULTS: The median doubling times were 101 days in the MLP and 144 days in the MSK, times that are somewhat shorter than those reported in published series of adenocarcinoma cases diagnosed outside screening, and only 5% had doubling times exceeding 400 days. CONCLUSIONS: The hypothesis that early-stage lung tumors diagnosed on chest radiography during lung carcinoma screening may frequently be overdiagnosed, indolent cases needs to be rejected.
The Early Lung Cancer Action Project (ELCAP) recently demonstrated that earlier diagnosis of lung cancer can be achieved with CT, and these results have led to considerable demand for CT screening. The advisability of screening seems obvious, as screening has been shown to provide for lung cancer treatment at a relatively early stage, leading to a better chance to avert death from lung cancer than when treatment is prompted by symptoms and/or signs. There are, however, countervailing ideas that CT lung cancer screening has not yet been demonstrated to 'save lives.' Further, it has been stated that CT screening has a notable problem of "overdiagnosis," meaning that screening finds lesions that are not life threatening, leading to unnecessary surgery. These concerns have led to the argument that assessing 'lives saved,' as well as the effects of overdiagnosis, can only be achieved with a randomized, controlled trial comparing CT screening with no screening, using a mortality endpoint. To this end, the National Lung Screening Trial (NLST) has been funded. This randomized, controlled trial is the most expensive screening study ever proposed. It compares CT screening with chest X-ray screening, and its designers envision that it will provide an answer about the benefit of CT screening, or lack thereof, in about 10 years. We do not question the value of the randomized design of 'treatment' trials for comparing competing interventions (treatments), but we have serious concerns about the use of randomization in the evaluation of a diagnostic test, such as CT. We feel that randomization is not necessary for evaluating a diagnostic test and may generate misleading results. Rather, we feel that the desired information is how often and how early is the disease diagnosed using that test. The purpose of this article is to raise the general level of concern about the underpinnings of such randomized 'screening' trials, and to convey some of the evidence that led to our pessimism about the NLST.
Small pulmonary nodules are a common radiographic finding that presents an important diagnostic challenge in contemporary medicine. While pulmonary nodules are the major radiographic indicator of lung cancer, they may also be signs of a variety of benign conditions. Measurement of nodule growth rate over time has been shown to be the most promising tool in distinguishing malignant from nonmalignant pulmonary nodules. In this paper, we describe three-dimensional (3-D) methods for the segmentation, analysis, and characterization of small pulmonary nodules imaged using computed tomography (CT). Methods for the isotropic resampling of anisotropic CT data are discussed. 3-D intensity and morphology-based segmentation algorithms are discussed for several classes of nodules. New models and methods for volumetric growth characterization based on longitudinal CT studies are developed. The results of segmentation and growth characterization methods based on in vivo studies are described. The methods presented are promising in their ability to distinguish malignant from nonmalignant pulmonary nodules and represent the first such system in clinical use.
PURPOSE: The aim of this study was to assess the significance of Stage I diagnoses of lung cancer in the baseline cycle of screening for this disease, with special reference to the potential for overdiagnosis. METHODS: We reviewed all 69 cases of Stage I lung cancer diagnosis resulting from our baseline CT screening. Among these 69 cases of lung cancer, 24 presented as solid, 30 as part-solid, and 15 as nonsolid nodules. The extent to which these represented genuine malignancy was assessed by a panel of experts on lung pathology, and the "aggressiveness" of these cases was addressed by the criterion of the tumor's volume doubling time being less than 400 days. RESULTS: The expert panel confirmed all 69 cases as representing genuine malignancy. Among the 69 cases without evidence of metastases, the proportion that satisfied the aggressiveness criterion was 60/69=87%. The corresponding proportions by presentation as solid, part-solid, and nonsolid nodule were 23/24 (96%), 27/30 (90%), and 10/15 (67%), respectively. CONCLUSIONS: In baseline CT screening for lung cancer, overdiagnosis of the disease is uncommon, with cases presenting as a nonsolid nodule a possible exception to this.