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Nancy Obuchowski

Publications and source records attributed to Nancy Obuchowski.

14 recordsLinked to original sources
PubMed2006

The predictive value of helical computed tomography for collecting-system entry during nephron-sparing surgery.

OBJECTIVES: To assess the ability of helical computed tomography (CT) including multiplanar reformatting and volume rendering (3D CT) to predict collecting system entry at surgery, as helical CT can be used to delineate renal tumour and normal renal anatomy before nephron-sparing surgery (NSS). PATIENTS AND METHODS: Knowledge of the possibility of collecting system entry during surgery might either dissuade some surgeons from NSS in elective situations or influence the operative approach or ablative technology in cases where NSS is imperative, or prepare the surgeon for the possibility of collecting system repair. We reviewed all 3D CT (349 scans) obtained before NSS at our institution over three consecutive years. Tumour size, central tumour extension, and presence of calyceal involvement were prospectively recorded at the time of 3D rendering. Collecting system entry was analysed for these three CT variables, and for three clinical variables (tumour side, size and surgical approach) collected retrospectively from the medical records. Multivariate logistic regression was used to assess the sensitivity, specificity, and positive and negative predictive values. RESULTS: Of 344 patients, 170 had collecting system entry reported at surgery. There were statistically significant associations between collecting system entry and central tumour location by CT (sensitivity 58.8%, specificity 80.5%, P < 0.001), calyceal involvement at CT (sensitivity 53.5%, specificity 78.2%, P < 0.001), and tumour size on CT of > 4 cm (sensitivity 39.4%, specificity 74.7%, P = 0.005). There were no significant associations with side or type of surgery (P > 0.83). CONCLUSION: Helical CT is a reliable predictor of calyceal entry at surgery.

Adolescent↗
PubMed2006

The accuracy of chest radiographs in the detection of congenital heart disease and in the diagnosis of specific congenital cardiac lesions.

BACKGROUND: Congenital heart disease (CHD) is a significant cause of morbidity and mortality in pediatric patients. Traditional teaching holds that specific types of CHD can be diagnosed on the chest radiograph (CXR) through pattern recognition. OBJECTIVE: To determine the accuracy of radiologists in detecting CHD on the CXR. MATERIALS AND METHODS: This study was a blinded retrospective review of chest radiographs from 281 patients (<12 years) by five pediatric radiologists from three institutions. Thirteen groups were evaluated that included 12 categories of CHD and a control group of patients without heart disease. Radiographs were assessed for heart size, heart and mediastinal shape and vascularity. Clinical information, angiography, echocardiograms and surgery were used as the gold standard for definitive diagnosis. RESULTS: The average accuracy of the five readers in distinguishing normal from CHD patients was 78% (range of 72% to 82%). The overall measure of accuracy in distinguishing specific congenital cardiac lesions among 13 groups of patients was 71% (range of 63% to 79%). CONCLUSION: CXR alone is not diagnostic of specific cardiac lesions, with a low accuracy of only 71%. We believe that less emphasis should be placed on the use of radiographs alone in diagnosing specific congenital cardiac lesions.

Child↗
PubMed2006

Total body screening: predicting actionable findings.

RATIONALE AND OBJECTIVES: Total body screening, despite its popularity, has not been evaluated in clinical trials. Even the appropriate target for screening has not been addressed. In this study, we determined the variables from a subject's demographic and medical and family history that are predictive of actionable findings on total body screening. MATERIALS AND METHODS: Over a 3-year period, 982 self-referred subjects underwent total body screening with multislice computed tomography and completed a demographic and medical history questionnaire. The study sample was divided into training and testing samples. Univariate and multiple-variable statistical methods were used on the training sample to derive models that predict actionable lung findings, actionable heart findings, actionable abdomen/pelvis findings, and any actionable findings on total body screening. The training models were then applied and evaluated on the test sample. RESULTS: A subject's age at the time of screening was the single most important predictor and often the only significant predictor of actionable findings. Among subjects younger than 40 years of age, 22.5% had actionable findings; this number nearly doubled, to 43.5%, for subjects between 40 and 49, and increased to 80% for subjects 80 years and older. Overall, every increase of 10 years in age brings an increase of 1.6 in the likelihood of an actionable finding. CONCLUSIONS: Total body screening targeted at older subjects has the highest yield of actionable findings. The efficacy and cost-effectiveness of total body screening for older subjects is unknown and needs further assessment.

Computer Simulation↗
PubMed2004

Analysis of changes in attenuation of proven renal cysts on different scanning phases of triphasic MDCT.

OBJECTIVE: The purpose of this study is to document changes in attenuation values on triphasic MDCT of histologically or surgically proven cystic renal lesions. MATERIALS AND METHODS: A retrospective study of all renal lesions greater than 1 cm that underwent triphasic MDCT was performed in 90 patients before partial nephrectomy. Three reviewers independently measured the mean attenuation of all lesions in three phases (unenhanced, corticomedullary, and parenchymal) in a blinded retrospective fashion. Forty-three lesions identified at CT in 27 patients had pathologic or surgical confirmation as cysts (fluid-filled lesions). Mean change in attenuation between phases was calculated and correlated with size, unenhanced density, and percentage of the lesion exophytic from renal parenchyma. All scans were obtained after 150 mL of nonionic contrast material was injected at 3 mL/sec. Scanning delays were 30-40 sec (corticomedullary phase) and 120 sec (parenchymal phase). RESULTS: The mean change in attenuation coefficient of the cysts from the unenhanced to the parenchymal phase was -1.8 H (SD, +/- 4.4 H); from the unenhanced to the corticomedullary phase was -2.3 H (+/- 3.9 H); and from the corticomedullary to the parenchymal phase was 0.6 H (+/- 4.2 H). No cyst increased more than 10 H between the unenhanced and the parenchymal phases; more than 95% of cysts increased less than 8 H between any scanning phases. No significant difference was seen in enhancement related to lesion size (p > 0.054), unenhanced attenuation (p > 0.255), or percentage of the lesion that was exophytic (p > 0.124). CONCLUSION: The attenuation coefficient of a cystic renal lesion increased by no more than 10 H among the unenhanced, corticomedullary, and parenchymal phase scans.

Contrast Media↗
PubMed2004

Creating an international comprehensive web-based curriculum in pediatric radiology.

OBJECTIVE: This article describes the creation of a standardized comprehensive resident curriculum in pediatric radiology that uses adult learning principles authored by international experts and addresses the six general competencies required by the Accreditation Council for Graduate Medical Education. CONCLUSION: Web-based learning with an online curriculum has the potential to become an integral component of residency training. The use of radiology experts as authors allows compilation of an authoritative, comprehensive, and current body of knowledge that enhances the current teaching file approach to Web-based instruction in radiology. We describe the approach, design, and tools necessary for the construction of a complete Web-based curriculum in pediatric radiology that includes self-assessment through pre- and post-testing, text with interactive images, curriculum evaluation, and the ability to record trainee demographics.

Computer-Assisted Instruction↗
PubMed2004

Whole-body CT screening for cancer and coronary disease: does it pass the test?

Even though whole-body CT scanning is being marketed directly to patients and they are starting to demand it, does it meet the standards of a good screening test for cancer and coronary artery disease? This article is a step-by-step, disease-specific discussion of the characteristics of a good screening test, and whether whole-body CT scanning meets these standards.

Colorectal Neoplasms↗
PubMed2003

Do segmented reconstruction algorithms for cardiac multi-slice computed tomography improve image quality?

PURPOSE: To evaluate segmented reconstruction algorithms for spiral multi-slice computed tomography (MSCT) that use data from two cardiac cycles to improve temporal resolution (tau) for imaging of the heart. MATERIALS AND METHODS: An initial group of 78 cardiac patients (heart rates [HR] = 63-167 beats per minute [bpm]) were imaged on a 4-slice, 500 ms gantry rotation time scanner (scanner 1). Images were reconstructed with a single-segment algorithm using data from one cardiac cycle with a reconstruction window of fixed length (tau = 250 ms). Images were also reconstructed with two variants of a multi-segment algorithm using data from two cardiac cycles where only one end of the reconstruction window was fixed and the other end was freely moveable to allow adjustment of tau according to HR: (1) "2-segment fixed start" with fixed start of reconstruction, (2) "2-segment fixed end" with fixed end of reconstruction (for both, tau = 125-250 ms). The resulting image sets were ranked from best to worst (1-3, respectively) in a side-by-side, blinded comparison by two independent readers. A second group of 26 patients (HR = 74-90 bpm) were imaged on a 12-slice, 420 ms gantry rotation time scanner (scanner 2). Data were reconstructed with a single-segment algorithm (tau = 210 ms) and a "2-segment fixed start" algorithm (tau = 105-210 ms) and image sets were ranked from best to worst (1-2, respectively). RESULTS: There was no clear evidence that any one technique is superior for imaging on scanner 1. Reader 1 ranked single-segment images the highest for all HRs, but statistically significant differences among the three algorithms were only found for the lowest HRs (< 80 bpm), where reader 1 preferred single-segment over "2-segment fixed end" techniques (p = 0.048). The highest rankings given by reader 2 varied according to HR: single-segment images were superior for lowest HRs, while "2-segment fixed start" images were superior for HRs > 80 bpm; none of these comparisons reached statistical significance. Improved performance of 2-segment reconstruction was found with scanner 2. Both readers ranked "2-segment fixed start" images the highest (p < 0.01). CONCLUSIONS: The added value of 2-segment cardiac reconstruction algorithms for spiral MSCT was not demonstrated for a 4-slice, 500 ms gantry rotation time scanner but shown to be beneficial for a 12-slice, 420 ms gantry rotation time scanner in the crucial HR range of 74-90 bpm.

Adolescent↗
PubMed2003

Noninvasive assessment of cardiac mechanics and clinical outcome after partial left ventriculectomy.

BACKGROUND: Partial left ventriculectomy (PLV) was developed as a therapy for end-stage heart failure, but results were variable with few a priori predictors of outcome. Little is known about its effects on myocardial mechanics and their relation to clinical outcome. METHODS: Twenty-four dilated cardiomyopathy patients underwent cardiac magnetic resonance imaging (MRI) before PLV, and 3 and 12 months after surgery. Left ventricular (LV) circumferential shortening and wall stress were computed at three short-axis levels. Exploratory outcome analysis grouped patients according to the timing of adverse cardiac events postsurgery. RESULTS: LV mass and volume were decreased at each postsurgical time point (all p < 0.01). At 3 months, regional wall stress was reduced at all short-axis levels; but by 12 months stress was reduced from baseline only at the apex. Circumferential shortening was increased significantly at both postsurgical time points at each level. On average, septal shortening was negative (stretching) before surgery, but increased significantly, and was positive, postsurgery. Exploratory outcome analysis found that negative values of basal septum circumferential shortening before surgery increased the probability of event-free survival beyond 6 months. CONCLUSIONS: Regional heterogeneity of LV myocardial function, associated with dilated cardiomyopathy, was diminished after PLV but was also related to patient outcome. MRI with tissue tagging is useful for assessing the efficacy of surgical therapies for congestive heart failure.

Adult↗
PubMed2003

Evaluation of left ventricular dysfunction using multiphasic reconstructions of coronary multi-slice computed tomography data in patients with chronic ischemic heart disease: validation against cine magnetic resonance imaging.

PURPOSE: Multi-slice computed tomography (MSCT) is an emerging technique for the angiographic assessment of coronary artery disease (CAD). The purpose of this work was to determine if multiphasic reconstructions of the same data used for the assessment of CAD could also be used for global functional evaluation of the left ventricle (LV). MATERIALS AND METHODS: Fifteen patients with chronic ischemic heart disease (CIHD) were imaged for CAD using a contrast-enhanced retrospective electrocardiographic-gated spiral technique on a MSCT scanner. The same data were reconstructed at both end-diastole and end-systole in order to measure left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF). The results were compared to values obtained using a cine true-fast imaging with steady-state precession technique on a magnetic resonance imaging (MRI) scanner. Interobserver variability in the measurement from MSCT images was also evaluated. RESULTS: For LVEF, there was substantial agreement between MSCT and MRI (intraclass correlation coefficient of 0.825); the intermodality reproducibility for LVEF (5%) was within an acceptable clinical range. However, mean values of LVEDV and LVESV with MSCT compared to cine MRI (LVEDV: 262.0 +/- 85.6 ml and 297.2 +/- 98.8 ml, LVESV: 196.2 +/- 75.6 ml and 218.6 +/- 90.99 ml, respectively) were significantly less for both volumes (p < 0.015). Intermodality variabilities for these measurements were high (15 and 13% for LVEDV and LVESV, respectively). Readers' mean measurements of LVESV from MSCT images were significantly different (p = 0.003) resulting in differences in calculation of LVEF (p < 0.024). Still, interobserver variabilities for all values were acceptable (6, 8, and 5% for LVEDV, LVESV, and LVEF, respectively). CONCLUSION: Although values for LVEDV and LVESV were less with MSCT than with MRI, LVEF values were in agreement. This suggests that combined imaging of CAD and the evaluation of global LV dysfunction due to CIHD is feasible with the same MSCT acquisition.

Adult↗
PubMed2003

An endoscopic pancreatic function test with cholecystokinin-octapeptide for the diagnosis of chronic pancreatitis.

BACKGROUND & AIMS: Current pancreatic function tests are cumbersome and unavailable to the clinical gastroenterologist. We have developed a function test that can be modified to a purely endoscopic collection method (ePFT). The aim of this study was to compare the endoscopic and traditional Dreiling tube collection methods. METHODS: Two separate groups of healthy subjects and patients with chronic pancreatitis underwent pancreatic function testing. One group underwent the endoscopic collection method (ePFT). Intravenous cholecystokinin (CCK 40 ng x kg(-1) x h(-1)) was started in preprocedure area. Duodenal fluid was collected with upper endoscope during endoscopy at 30, 40, 50, and 60 minutes during infusion. Another group underwent the traditional Dreiling collection method. Intravenous CCK was started in postprocedure area after endoscopic tube placement. Duodenal fluid was collected at 0, 20, 40, 60, and 80 minutes during infusion. Lipase concentration was determined (IU/L) on laboratory autoanalyzer. RESULTS: Seventy-three patients were studied. Thirty-four underwent endoscopic collection and 39 underwent Dreiling collection. The mean peak lipase concentrations (+/- standard deviation) for healthy subjects and patients with chronic pancreatitis in the endoscopic collection method group were 1612500 +/- 556152 IU/L and 369594 +/- 281624 IU/L, respectively (P < 0.001). The mean peak lipase concentrations (+/- standard deviation) for healthy subjects and patients with chronic pancreatitis in the Dreiling tube collection method group were 1670324 +/- 786731 IU/L and 478956 +/- 406061 IU/L, respectively (P < 0.001). There was no statistical difference between collection methods at distinguishing healthy subjects and patients with chronic pancreatitis. Receiver operating characteristic curves (ROC) for the endoscopic and Dreiling collection methods were 0.993 (standard error of mean, 0.009) and 0.921 (standard error of mean, 0.041). A lipase concentration cut point of 810600 IU/L distinguishes healthy subjects from patients with chronic pancreatitis with a sensitivity and specificity of 92% and 95%, respectively. The ePFT was safe, short in duration, minimized costs (US dollars 1890 vs. US dollars 2659), required small amounts of fluid for analysis (1-3 mL), and eliminated radiation exposure. CONCLUSIONS: Analysis of timed endoscopic aspirations of pancreatic juice after hormonal stimulation can distinguish healthy subjects from patients with chronic pancreatitis. This new endoscopic collection method (ePFT) is less cumbersome and more time efficient, when compared to traditional collection methods. The ePFT broadens the availability of function testing to the practicing clinical gastroenterologist.

Adult↗
PubMed2003

An endoscopic pancreatic function test with synthetic porcine secretin for the evaluation of chronic abdominal pain and suspected chronic pancreatitis.

BACKGROUND: Pancreatic function tests are the most reliable methods for the diagnosis or exclusion of chronic pancreatitis in patients without obvious radiologic changes, but they are cumbersome, time consuming, and unavailable in clinical practice. Synthetic porcine secretin, a 27 amino acid peptide identical to the biologic form, is available for exocrine function testing. This study examined the utility of a simple, newly developed, purely endoscopic pancreatic function test with synthetic porcine secretin. METHODS: Three groups of patients were studied: patients with chronic abdominal pain with and without risk factors for chronic pancreatitis, and patients with advanced chronic pancreatitis. All patients with abdominal pain had "pancreatic type" pain for greater than 6 months and negative radiographic imaging studies. All patients with chronic pancreatitis had advanced disease based on retrograde pancreatography and/or CT findings. Participants underwent the following protocol: (1) standard endoscopy to the descending duodenum with the patient under conscious sedation; (2) intravenous administration of secretin (0.2 microgram/kg); (3) endoscopic duodenal fluid collection at 0, 15, 30, 45, and 60 minutes after secretin injection; and (4) fluid analysis for bicarbonate concentration. RESULTS: Eighteen patients were studied (5 abdominal pain without risk factors, 7 abdominal pain with risk factors, and 6 advanced chronic pancreatitis). Median peak (interquartile range) bicarbonate concentrations in meq/L for each group were, respectively, 87 (6, range 84-108), 72 (10, range 68-90), and 35 (27, range 18-88). Median peak bicarbonate concentration values for the 3 groups are significantly different (p = 0.010; Kruskal-Wallis test). Bicarbonate secretion in patients with chronic pancreatitis was markedly reduced compared with that in patients with abdominal pain without risk factors (p = 0.038; the Fisher exact test). The secretory function curve for patients with abdominal pain with risk factors was markedly abnormal, resembling the attenuated secretory curve seen in patients with chronic pancreatitis. The test was safe and well tolerated. CONCLUSIONS: A simple endoscopic pancreatic function test with synthetic porcine secretin appears to distinguish patients with known chronic pancreatitis from those with chronic abdominal pain without chronic pancreatitis. This simple, practical endoscopic test can be performed during upper endoscopy and may decrease the need for invasive procedures in patients with abdominal pain and normal radiographic imaging studies.

Abdominal Pain↗
PubMed2002

Cholecystokinin-stimulated peak lipase concentration in duodenal drainage fluid: a new pancreatic function test.

OBJECTIVE: Hormonal stimulation with secretin or cholecystokinin (CCK) is the most sensitive means of assessing pancreatic function. Secretin is not available, and current CCK tests are cumbersome, requiring dual tube intubation and marker perfusion techniques. The aim of this study was to test the efficacy of a new CCK-stimulated pancreatic function test measuring peak lipase concentration. METHODS: A Dreiling gastroduodenal tube was inserted to the ligament of Treitz, and fluid was collected on ice for 80 min in four 20-min aliquots. CCK was infused i.v. at a constant rate of 40 ng/kg/h. Gastric aspirations were discarded. Duodenal aspirates were analyzed for volume and enzyme concentration with a clinical laboratory autoanalyzer. RESULTS: Nineteen healthy volunteers and 18 chronic pancreatitis patients were studied. Lipase concentration and secretory volume showed a peak response by 40 min of stimulation, whereas amylase response was variable. The mean peak lipase concentrations (+/-SEM) for normal volunteers and mild, moderate, and advanced chronic pancreatitis patients were 16.9+/-1.9, 7.9+/-1.7, 3.7+/-1.2, and 2.1+/-0.6 x 10 5 IU/L, respectively. Lower peak lipase concentrations were significantly associated with more advanced chronic pancreatitis (p < 0.001). The receiver operating characteristic curve area for all chronic pancreatitis patients was 0.944 (95% CI = 0.825-0.985). A peak lipase concentration of 780,000 IU/L provided a sensitivity and specificity of 0.833 and 0.867, respectively. This CCK test was well tolerated and without complications. CONCLUSIONS: Lipase concentration in duodenal fluid increases nearly 3-fold from baseline after CCK stimulation in healthy volunteers but is markedly reduced in patients with chronic pancreatic disease. Peak lipase concentration is a significant predictor of chronic pancreatitis and correlates with severity of pancreatic disease. Aspiration of duodenal drainage fluid with a Dreiling tube and analysis with a laboratory autoanalyzer are less cumbersome than marker perfusion and back titration techniques. Measurement of enzyme concentration instead of output could lead to the development of an endoscopic or through-the-scope screening method for assessing patients with suspected chronic pancreatitis or chronic abdominal pain.

Adult↗
PubMed2002

Enhancement characteristics of papillary renal neoplasms revealed on triphasic helical CT of the kidneys.

OBJECTIVE: The purpose of this study was to determine whether renal tumor enhancement or heterogeneity on triphasic helical CT scans is predictive of the papillary cell subtype or nuclear grade of renal cell carcinoma. MATERIALS AND METHODS: We reviewed the CT scans of 90 consecutive patients with renal masses who had undergone triphasic renal helical CT before a complete or partial nephrectomy (12 with papillary renal cell carcinomas, 66 with nonpapillary renal cell carcinomas, and 12 with benign lesions). Three radiologists who were unaware of the patients' diagnoses retrospectively and independently measured the attenuation of each patient's tumor, abdominal aorta, and normal renal parenchyma on the scans obtained during all three phases. Ratios of tumor-to-aorta enhancement and tumor-to-normal renal parenchyma enhancement were calculated for both of the phases performed after contrast material had been administered. Tumor heterogeneity was calculated as the difference between the highest and lowest attenuation values divided by the value of the enhancement of the aorta. Values were correlated with cell type and nuclear grade found at surgical pathology. RESULTS: Low tumor-to-aorta enhancement and low tumor-to-normal renal parenchyma enhancement ratios on the vascular phase scans significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Homogeneity and tumor-to-parenchyma enhancement ratios on the parenchymal phase scans also significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Heterogeneity and tumor enhancement ratios did not correlate with the nuclear grade of the carcinoma. CONCLUSION: Papillary renal cell carcinomas are typically hypovascular and homogeneous. A high tumor-to-parenchyma enhancement ratio (> or = 25%) essentially excludes the possibility of a tumor being papillary renal cell carcinoma. A low tumor-to-aorta enhancement ratio or tumor-to-normal renal parenchyma enhancement ratio is more likely to indicate papillary renal cell carcinoma.

Adult↗