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Biomedical subjects

S Gregory Jennings

Publications and source records attributed to S Gregory Jennings.

10 recordsLinked to original sources
PubMed2006

Distribution of stage I lung cancer growth rates determined with serial volumetric CT measurements.

PURPOSE: To retrospectively determine the distribution of stage I lung cancer growth rates with serial volumetric computed tomographic (CT) measurements. MATERIALS AND METHODS: This study was institutional review board approved and HIPAA compliant. The informed consent requirement was waived. Patients (n = 149) with stage I lung cancer who underwent two pretreatment CT examinations 25 or more days apart were identified. At the first and last examinations, tumor perimeters were manually inscribed by using software tools and the cross-sectional area was calculated. To calculate tumor volume, the summed areas were multiplied by the section increment and a formula was applied to reduce partial volume effects. Doubling time (DT) was calculated by using the volume and interscanning interval. The percentages of tumors that would surpass volume increase thresholds of 5%-25% for detectable growth at different time intervals were calculated. Age at diagnosis was compared with the reciprocal of DT, time interval between CT examinations, and initial tumor volume by using Pearson correlation. P < .05 denoted statistical significance. RESULTS: Lung cancer was stage IA in 99 patients and stage IB in 50. Median patient age was 72 years, and median interscanning interval was 130 days. Median tumor volumes were 3000 and 6213 mm3 at the first and last examinations, respectively. Median DT was 207 days; 21 tumors did not increase in volume between examinations. The interscanning interval required for 90% of growing tumors to surpass the growth threshold ranged from 8 weeks (5% threshold) to 37 weeks (25% threshold). Fifty-three percent of growing tumors would surpass the 25% threshold at 8 weeks, and 95% would surpass it at 1 year. Age at diagnosis was negatively correlated with growth rate (P = .047); there was no correlation between growth rate and either age at diagnosis or interscanning interval. CONCLUSION: At serial volumetric CT measurements, there was wide variability in growth rates. Some biopsy-proved cancers decreased in volume between examinations.

Adult↗
PubMed2004

Lung tumor growth: assessment with CT--comparison of diameter and cross-sectional area with volume measurements.

PURPOSE: To compare diameter and cross-sectional area measurements with volume measurements in the assessment of lung tumor growth with serial computed tomography (CT). MATERIALS AND METHODS: Patients with lung cancer who underwent at least one pair of chest CT examinations 25 or more days apart before treatment and with a tumor size of T1 (< or =3-cm diameter) at the initial CT examination were identified. A total of 63 patients (62 men, one woman) who underwent 93 pairs of CT examinations were included. Images obtained at each examination were displayed, and the maximum diameter, cross-sectional area, and volume of the tumor were measured. For each measurement, the change between examinations was assessed to determine whether the change reached a detection threshold for growth, as determined in a prior study with simulated tumors. Results were then compared between measurement methods, with volume change serving as the reference standard, by calculating Spearman rank-order coefficients between examinations. Tumor size or section width were also evaluated with the two-tailed Fisher exact probability test to determine if they affected agreement about tumor growth between measurement methods. RESULTS: Thresholds were as follows: diameter, 2.1 mm with hand-held calipers and 0.68 mm with electronic calipers; area, 9.4%; volume, 16.5%. The median time between examinations was 92 days (range, 25-1,221 days). Median diameter increased from 19.3 mm to 23.0 mm (19.2%), median area from 207 mm(2) to 267 mm(2) (29.0%), and median volume from 1,652 mm(3) to 2,443 mm(3) (47.9%). Growth assessment with these diameter (as assessed with hand-held and electronic calipers) and area thresholds disagreed with those obtained with volume in 34 (37%), 26 (28%), and 25 (27%) of the 93 pairs of CT examinations, respectively. Of diameter assessments with the hand-held caliper threshold, 28 (30%) were false-negative; false-negative results occurred with this diameter threshold and area threshold with examination intervals as long as 1 year. CONCLUSION: Growth assessment of T1 lung tumors on serial CT scans with nonvolumetric measurements frequently disagrees with growth assessment with volumetric measurements.

Adult↗
PubMed2004

Suspected acute pulmonary embolism: evaluation with multi-detector row CT versus digital subtraction pulmonary arteriography.

PURPOSE: To determine diagnostic accuracy of four-channel multi-detector row computed tomography (CT) in emergency room and inpatient populations suspected of having acute pulmonary embolism (PE) who prospectively underwent both CT and pulmonary arteriography (PA). MATERIALS AND METHODS: Patients referred for PA to assess suspected PE were eligible. Institutional review board approval and written informed consent were obtained. All patients underwent CT and PA within a 48-hour period. For CT, 4 x 2.5-mm collimation was used. Three readers independently evaluated each study for PE presence. PE status, vessel level, and lobar location were determined by means of majority rule, and interobserver agreement (kappa) was calculated for PE status, as assessed with each modality. Sensitivity and specificity of CT were calculated by using PA as the reference standard. Two radiologists later reviewed false-positive CT studies. RESULTS: The study group comprised 93 patients (median age, 56 years; range, 19-88 years). Sensitivity, specificity, and accuracy of CT were 100%, 89%, and 91%, respectively. kappa values were 0.71 and 0.83 for CT and PA, respectively, and were not significantly different between modalities. At PA, 18 patients (19%) had PE at 50 vessel levels (five main and/or interlobar, 24 segmental, and 21 subsegmental), 17 (94%) of which had PE at multiple sites. At CT, 26 patients (28%) had PE at 71 vessel levels (24 main and/or interlobar, 33 segmental, and 14 subsegmental). Twenty patients (77%) had PE at multiple sites. Review of eight false-positive CT studies showed an appearance highly suggestive of acute PE in three patients, chronic PE in one, and no PE in three; one study was inconclusive. CT better demonstrated large-level vessel involvement (P < .01), while PA better demonstrated small-level vessel involvement (P < .01). CONCLUSION: Multi-detector row CT has an accuracy of 91% in the depiction of suspected acute PE when conventional PA is used as the reference standard.

Acute Disease↗
PubMed2003

Effect of varying CT section width on volumetric measurement of lung tumors and application of compensatory equations.

PURPOSE: To determine how volume measurements of simulated and clinical lung tumors at standard computed tomographic (CT) lung window and level settings vary with section width and to derive and apply compensatory equations. MATERIALS AND METHODS: Spherical simulated tumors of varying diameters were imaged with varying CT section widths, the images were displayed on a workstation, the cross-sectional area of the tumor on each section was measured by using elliptical and perimeter methods, and the areas were integrated to compute tumor volume. The actual and measured tumor volumes for differing section widths and tumor diameters were compared, and compensatory equations were derived. The equations were applied to contemporaneous chest CT images obtained in patients with stage I lung cancer, and the difference between thick- and thin-section-derived volumes before and after application of the equations was determined. RESULTS: All simulated tumor volumes were overestimated 11%-278%; overestimation varied directly with section width and inversely with tumor diameter. With both measurement methods, mean thin-section volumes of clinical tumors in 55 patients were significantly smaller (P <.01) than mean thick-section volumes: Mean elliptical measurements were 15,025 mm3 (thin) and 18,037 mm3 (thick), with a 20.0% difference; mean perimeter measurements were 16,164 mm3 (thin) and 20,718 mm3 (thick), with a 22.2% difference. The thin-section-to-thick-section volume difference was larger for the smallest tumors. Thin-section volumes were smaller than thick-section volumes in 53 patients with the elliptical method and in 51 patients with the perimeter method. Applying the equations decreased the difference between thick- and thin-section volumes in 37 (67%) of the 55 patients with the elliptical method and in 41 (74%) patients with the perimeter method. The mean thin-section-to-thick-section volume difference became nonsignificant with the perimeter method but remained significant with the elliptical method. CONCLUSION: Measured lung tumor volumes vary significantly with varying CT section width; overestimation varies directly with section width and inversely with tumor size. Compensatory equations that are somewhat effective in reducing these effects can be derived.

Adult↗
PubMed2002

Agreement and reproducibility of subjective methods of measuring faculty time distribution.

RATIONALE AND OBJECTIVES: The authors performed this study to compare self-reported estimates of the time radiology members spend performing various activities between reporting methods and academic years. MATERIALS AND METHODS: For 3 consecutive academic years, the percentage of time each faculty member reported spending on clinical, teaching, research, and service and/or administrative activities was noted on each of three separate reports: a quarterly report to department administration, an annual report to university administration, and the annual review with his or her department supervisor. For each activity, the means were compared between methods and between years. RESULTS: In general, the year-to-year changes in mean percentage for each activity and method were not statistically significant (34 of 36 comparisons). Nineteen of 36 comparisons, however, showed significant differences between reporting methods for a particular activity. For example, the mean percentages obtained with the three methods from 1999 to 2000 varied from 49% to 66% (clinical), 14% to 34% (teaching), 8% to 15% (research), and 3% to 11% (service and/or administrative). CONCLUSION: Current methods used to quantify faculty time distribution yield significantly different results despite internal consistency from year to year for each method. New and clearer methods for determining faculty time distribution are needed.

Academic Medical Centers↗
PubMed2002

Volumetric growth rate of stage I lung cancer prior to treatment: serial CT scanning.

PURPOSE: To determine the range of growth rates of stage I lung cancers prior to treatment by using volumetric measurement at serial chest computed tomographic (CT) examinations. MATERIALS AND METHODS: The study population comprised 50 patients who underwent two CT examinations at 25-day or greater intervals. Tumor craniocaudal length and cross-sectional diameters and perimeters were used to volumetrically model each tumor in three ways (spherical, elliptical, perimeter). Volumes were compared by determining Pearson correlation coefficients. By using these volumes, tumor doubling time was determined for each patient. RESULTS: Volumes measured with all three methods were highly correlated. With the perimeter method, median doubling time was 181 days, with a very wide range. Eleven (22%) of 50 tumors had doubling times of 465 days or more. There was considerable overlap in doubling time between histologic subtypes. Assuming constant growth, only three (6%) of the 50 tumors would have been the size of a stage IA tumor for less than 1 year. CONCLUSION: Comparison of tumor volumes at serial CT examinations reveals a very wide range of growth rates. Some tumors grow so slowly that biopsy is required to prove they are malignant.

Adult↗
PubMed2002

Pulmonary embolism in pregnant patients: fetal radiation dose with helical CT.

PURPOSE: To calculate mean fetal radiation dose from helical chest computed tomography (CT) by using maternal-fetal geometries obtained from healthy pregnant women and to compare the calculated CT doses with the fetal doses reported with scintigraphy. MATERIALS AND METHODS: Maternal-fetal geometries were determined in 23 pregnant women with varying body mass index and fetal gestational age. Monte Carlo techniques were used to estimate the dose that would be received by each fetus from CT scanning performed with the following parameters: 120 kVp; 100 mA; scanning time, 1 second per section; collimation, 2.5 mm; pitch of 1. Craniocaudal extent of the scan was 11 cm, with the most caudal section edge being 5 mm inferior to the xiphoid process. RESULTS: For helical CT, estimated mean fetal doses in micrograys at varying gestational ages were as follows: 3.3-20.2 microGy, first trimester; 7.9-76.7 microGy, second trimester; and 51.3-130.8 microGy, third trimester. These values were all less than mean fetal doses reported with scintigraphy, with 37-74 MBq of macroaggregates of human serum albumin labeled with technetium 99m. If 200 mAs (pitch of 1.8) was used, the mean fetal doses were still less than those with scintigraphy. CONCLUSION: The average fetal radiation dose with helical CT is less than that with ventilation-perfusion lung scanning during all trimesters.

Adult↗
PubMed2002

Seasonal dyspnea.

Explore the source record for details and available documents.

Alveolitis, Extrinsic Allergic↗
PubMedDate not supplied

Computed tomography demonstration of lipomatous metaplasia of the left ventricle following myocardial infarction.

Replacement of myocardium by fat, particularly of the right ventricle, is often diagnosed as arrhythmogenic right ventricular dysplasia. At autopsy, however, 68% of scars associated with chronic ischemic heart disease have shown fatty metaplasia in the scar. Four patients with a past history of previous myocardial infarctions and computed tomography demonstration of fatty change in left ventricular regions of hypokinesis and infarction are presented. It is proposed that these findings represent ischemic fatty metaplasia, an alternative etiology of fatty tissue replacing myocardium.

Adipose Tissue↗