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Biomedical subjects

Richard Tello

Publications and source records attributed to Richard Tello.

14 recordsLinked to original sources
PubMed2005

Observer performance in assessing anemia on thoracic CT.

OBJECTIVE: The purpose of this study was to evaluate the ability of expert reviewers to differentiate an anemic from a nonanemic state on the basis of visual assessment of the relative attenuation of blood in the left ventricle on noncontrast thoracic CT images and to compare reviewer performance with quantitative measurement of CT density in Hounsfield units. MATERIALS AND METHODS: One hundred two noncontrast thoracic CT examinations were qualitatively reviewed by three independent reviewers. Hounsfield unit measurements of the blood in the left ventricle were recorded by a fourth individual. Anemia was defined as a hemoglobin level of less than 10 g/dL. Receiver operating characteristic (ROC) analyses of expert reviewers were compared with measured Hounsfield units. RESULTS: Hounsfield unit measurements performed significantly better than subjective reviewer analyses for differentiation of an anemic from a nonanemic state (area under ROC curve = 0.85 vs 0.72, 0.70, and 0.69; 95% confidence interval, 0.78-0.92 vs 0.63-0.81, 0.61-0.79, and 0.60-0.78, respectively; p < 0.05). With use of a CT density threshold of 35 H, the sensitivity for anemia was 76% and specificity was 81%, whereas the sensitivity of three reviewers was 40-72% with a specificity of 60-83%. Interobserver agreement was found to be poor by kappa statistic (0.0906-0.2128). The correlation coefficient for the analysis of Hounsfield unit versus hemoglobin level was 0.72. Separating data by patient sex revealed a correlation coefficient of 0.81 for men versus 0.52 for women, although the actual regression lines were not statistically different (p > 0.05). CONCLUSION: Despite expert reviewer analyses, subjective evaluations of blood attenuation characteristics are prone to inaccuracy and show poor interobserver agreement. Quantitative measurements of CT density in Hounsfield units should be performed to accurately differentiate an anemic from a nonanemic state when serum hemoglobin levels are not readily available.

Adult↗
PubMed2005

Gadolinium-enhanced MDCT angiography of the abdomen: feasibility and limitations.

OBJECTIVE: The purpose of this study was to evaluate a protocol for gadolinium-enhanced MDCT angiography of the abdomen and to identify technical parameters that optimize image quality. CONCLUSION: The degree of enhancement and image quality achieved using this gadolinium-enhanced MDCT angiography appear adequate for angiographic evaluation of the abdominal aorta and its major branches.

Abdomen↗
PubMed2005

Presence of a yolk sac on transvaginal sonography is the most reliable predictor of single-dose methotrexate treatment failure in ectopic pregnancy.

OBJECTIVE: The purpose of this study was to determine which imaging characteristics can be used as prognostic indicators in conjunction with beta-human chorionic gonadotropin (beta-hCG) levels in the treatment of ectopic pregnancy (EP) with single-dose methotrexate (MTX). METHODS: A retrospective study was performed on 62 patients (age range, 16-47 years; mean, 29 years) treated with MTX for EP from November 2000 to August 2003. The transvaginal sonographic findings in each case were analyzed for the presence and size of an extraovarian mass or a pseudogestational sac, amount of free fluid, presence of a yolk sac, and fetal heart motion. Patient age and beta-hCG level were also noted. Success of treatment was defined as a single dose of MTX that resulted in appropriate lowering of beta-hCG levels. RESULTS: Of 62 patients, 17 (27%) had single-dose MTX treatment failure. A yolk sac was identified in 15 (88%) of the 17 treatment failures and in none of the cases in which treatment was successful (positive predictive value, 100%). The average beta-hCG level in the cohort of patients who had single-dose treatment failure was 3282 mIU/mL compared with 1544 mIU/mL in the treatment success cohort. The presence of fetal heart motion was seen in only 1 patient, and this patient had treatment failure. The age of the patient, size of the extraovarian mass, presence of a pseudogestational sac, and amount of free fluid did not correlate with outcome. CONCLUSIONS: The presence of a yolk sac was always associated with treatment failure in single-dose MTX treatment of EP and was the most reliable predictor of failure among all features analyzed. The beta-hCG level was a useful adjunct. A prediction rule was created correlating the probability of treatment success with the beta-hCG level.

Abortifacient Agents, Nonsteroidal↗
PubMed2004

Accessory renal arteries are not related to hypertension risk: a review of MR angiography data.

OBJECTIVE: It has been hypothesized that accessory renal arteries are related to the risk of hypertension. Our goal was to determine the prevalence of accessory renal arteries in hypertensive patients using MR angiography and to assess the relationship between accessory renal arteries and hypertension risk. MATERIALS AND METHODS: From 1996 to 2002, 185 hypertensive patients underwent MR angiography of the renal arteries at our institution for assessment of renal artery stenosis. MR angiograms were obtained using a 1.5-T magnet, IV gadolinium, and 3D gradient-echo sequences. Interpretations of the MR angiograms were retrospectively reviewed. RESULTS: Of 185 hypertensive patients, 45 (24%) showed accessory renal arteries. Of these 45 patients, nine (20%) showed renal artery stenosis and 36 (80%) showed no significant stenosis. Of the 140 patients with a single renal artery, 42 (30%) showed renal artery stenosis and 98 (70%) showed no stenosis. The odds ratio of renal artery stenosis in the accessory renal artery group versus the single renal artery group was 0.58 (95% confidence interval, 0.26-1.3%), which is not statistically significant at a power of 0.85 (chi(2) = 1.705; p = 1.0). CONCLUSION: We found no statistically significant difference in the prevalence of renal artery stenosis between patients with accessory renal arteries and those without accessory renal arteries. Assuming that the presence of two separate causes of hypertension in the same patient would be unlikely, this finding implies that accessory renal arteries are a vascular anomaly and not a direct cause of hypertension. The findings are potentially relevant in refuting the theory of accessory renal arteries as an anatomically treatable cause of hypertension.

Adult↗
PubMed2003

Technical note: postgadolinium two-dimensional time-of-flight MR angiography of the foot.

OBJECTIVE: The purpose of this study was to determine the ability of postgadolinium time-of-flight (TOF) MR angiography to image the foot of patients compared to conventional TOF MR angiography. SUBJECTS AND METHODS: Six feet in five patients were included in this prospective study. Standard two-dimensional axial TOF sequences of the lower extremities, followed by three-dimensional (3D) contrast-enhanced moving-table images of the aorta to the foot during the intravenous bolus administration of gadolinium, were obtained in all patients. Two-dimensional axial respiratory-compensated TOF sequences were then obtained over the foot. Axial images and maximum intensity projections (MIP) reconstructions were evaluated by two blinded radiologists and images rated with respect to overall image quality, large-vessel and small-vessel visualization, degree of venous overlap, and extent of vessel stenosis. RESULTS: The 2D postgadolinium TOF technique resulted in an improvement in all areas of image quality compared with the noncontrast acquisition method, with very good interobserver agreement (kappa 0.67). Postcontrast images provided superior vessel visualization ( p=0.024, Wilcoxon signed rank test), with minimal artifact (84% with none, kappa 1.0), and excellent agreement on grading of dorsalis pedis stenosis (kappa 0.78). Vessel-to-background signal intensity ratio was doubled compared to the standard technique (mean 19.5, SD 6.5 versus 8.8, SD 4.5; p=0.016). CONCLUSION: Postgadolinium TOF MR angiography of the foot demonstrates significantly improved image quality over noncontrast techniques.

Aged↗
PubMed2003

Hypothesis testing III: counts and medians.

Radiology research involves comparisons that deal with the presence or absence of various imaging signs and the accuracy of a diagnosis. In this article, the authors describe the statistical tests that should be used when the data are not distributed normally or when they are categorical variables. These nonparametric tests are used to analyze a 2 x 2 contingency table of categorical data. The tests include the chi2 test, Fisher exact test, and McNemar test. When the data are continuous, different nonparametric tests are used to compare paired samples, such as the Mann-Whitney U test (equivalent to the Wilcoxon rank sum test), the Wilcoxon signed rank test, and the sign test. These nonparametric tests are considered alternatives to the parametric t tests, especially in circumstances in which the assumptions of t tests are not valid. For radiologists to properly weigh the evidence in the literature, they must have a basic understanding of the purpose, assumptions, and limitations of each of these statistical tests.

Diagnostic Imaging↗
PubMed2003

Hypothesis testing II: means.

Whenever means are reported in the literature, they are likely accompanied by tests to determine statistical significance. The t test is a common method for statistical evaluation of the difference between two sample means. It provides information on whether the means from two samples are likely to be different in the two populations from which the data originated. Similarly, paired t tests are common when comparing means from the same set of patients before and after an intervention. Analysis of variance techniques are used when a comparison involves more than two means. Each method serves a particular purpose, has its own computational formula, and uses a different sampling distribution to determine statistical significance. In this article, the authors discuss the basis behind analysis of continuous data with use of paired and unpaired t tests, the Bonferroni correction, and multivariate analysis of variance for readers of the radiology literature.

Analysis of Variance↗
PubMed2003

A web based video tool for MR arthrography.

OBJECTIVE: Our objective was to integrate digital video and web technology to construct a useful self paced learning tool to deliver recorded techniques of magnetic resonance (MR) arthrography for junior radiology residents and medical students. CONCLUSION: The streaming of audio media, an emerging technology, is an effective vehicle to deliver educational material over the Internet using commercially available PCs and modems, especially when teaching resources are limited.

Computer-Assisted Instruction↗
PubMed2003

T2 dark blood MRA for renal artery stenosis detection: preliminary observations.

OBJECTIVE: This study evaluated the ability of a fast spin echo T2 weighted dark blood sequence to characterize significant (>50%) renal artery stenosis compared to conventional angiography. METHODS: Sixteen patients underwent conventional catheter angiography for either renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with fast spin echo T2 weighted MR (TR 4000, TE 102, 8 echo train length) on a Superconducting 1.5T Magnet. Results were compared with angiography and inter and intra observer statistics were calculated. RESULTS: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis. Dark blood MRA (DBMRA) is 96% sensitive (95%CI: 89-100), 92% specific, with a predictive value positive of 96% for classifying real arteries as normal or significantly stenosed. Inter and intra observer statistics demonstrate good to excellent agreement in renal artery classification (kappa>0.60). CONCLUSION: DBMRA may be a useful adjunct to renal MR evaluation in hypertension. SUMMARY: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis.

Adult↗
PubMed2002

Prediction rule for etiology of vague abdominal pain in the emergency room: utility for imaging triage.

RATIONALE AND OBJECTIVES: To determine the predictive value of clinical parameters in patients with nonspecific abdominal pain undergoing computed tomography (CT) evaluation of the abdomen and pelvis in the emergency room (ER). MATERIALS AND METHODS: A cross-sectional study of a total of 164 sequential abdominal CT exams of the abdomen and pelvis during a 4 month period for nonspecific abdominal pain in the ER setting identified 100 abnormal scans in 164 patients (61 men, 103 women) of average age 46 years (range 4-97). Patient demographic characteristics (age, sex, temperature, white blood cell (WBC) count, and presence of peritoneal signs) were recorded at the time of CT examination. Results of the CT studies were correlated with the clinical data and discharge diagnosis to assess their positive predictive value using ordinal logistic regression. RESULTS: There were 17 cases of appendicitis, 9 cases of diverticulitis, 3 neoplasms, 3 abdominal abscesses, 2 pancreatitis, 2 duodenitis, 5 with fluid collections, 1 buttocks abscess, and 1 epiploic appendagitis were diagnosed with CT, 57 patients had unrelated findings on CT (common but not usually associated with vague pain). A diagnosis of appendicitis correlated with; elevated WBC count (>11.5) ( = 0.002), male sex ( = 0.001), and younger age (<25 years old) ( = 0.002). A positive CT correlated with an elevated WBC >11.5 (OR, 7.7; 95% CI, 3.3-18). The presence of peritoneal signs and fever did not correlate with a positive CT finding and diverticulitis had no predictive variables. Alternative diagnoses were correlated with female sex ( = 0.014). The combination of; age, sex, and WBC count allowed for a prediction rule with Area under the receiver operator curve of 0.92 to be generated. CONCLUSION: An elevated white blood cell (WBC) count is strong evidence of the presence of an inflammatory process. Alternative diagnostic considerations should be entertained in the context of a normal WBC count without strong clinical suspicion, particularly in women. The use of these factors alone allowed the construction of a prediction rule that can be used for CT protocol optimization.

Abdominal Pain↗
PubMed2002

Coronary artery bypass graft flow: qualitative evaluation with cine single-detector row CT and comparison with findings at angiography.

A four-point ordinal-scale qualitative flow index was used for assessment of patency of 75 coronary artery bypass grafts in 26 patients examined with spiral computed tomography (CT). CT findings were compared with selective graft angiographic findings. Of 54 open grafts, 52 were patent at initial selective graft angiography and 50 were patent at spiral CT; accuracy rates were 97% (73 of 75) and 95% (71 of 75), respectively. Spiral CT flow index agreed with angiographically determined flow in 85% (95% CI: 0.77, 0.93) of grafts. The kappa statistic demonstrated very good to excellent intermodality (0.75) and interobserver (0.89) agreement. Spiral CT may be a feasible means of assessing quality of flow in bypass grafts.

Coronary Angiography↗
PubMedDate not supplied

Prediction rule for diagnosis of arrhythmogenic right ventricular dysplasia based on wall thickness measured on MR imaging.

MRI is seeing an increasing role in the evaluation of suspected arrhythmogenic right ventricular dysplasia (ARVD). Our aims were to establish wall thickness criteria for diagnosis of ARVD based on MR imaging measurements. A cross-sectional case-control retrospective study of 21 cardiac MR exams over a 3 year period identified five patients (two men, three women) of average age 43 years (range 36-48) who were diagnosed with ARVD and 16 patients (nine men, seven women) of average age 52 years (range 25-78) who were diagnosed with normal right ventricular wall motion. Patient demographic characteristics (age, sex) and right ventricular free wall thickness (RVFWT) were evaluated for predictive ability. Calculated RVFWT was (mean+/-SD, in mm); (4.4+/-1.4) for ARVD, and (7.8+/-2.9), controls with P<0.001. Logistic regression analysis indicated that sex and age were not significant independent predictors (P>0.05). RVFWT allowed for a prediction rule with Area under the receiver operator curve of 0.94 to be generated. In our study, measurement of the thickness of the right ventricular free wall using cardiac-gated MRI proved to be a statistically significant predictor of ARVD.

Adult↗