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Biomedical subjects

Ruth C Carlos

Publications and source records attributed to Ruth C Carlos.

32 records · Page 2Linked to original sources
PubMed2004

Apparent diffusion coefficient mapping of the normal parotid gland and parotid involvement in patients with systemic connective tissue disorders.

PURPOSE: We hypothesized that a difference in restricted diffusion would exist in patients with connective tissue disorders (CTD) as compared with those without CTD. Our purpose was to determine whether the apparent diffusion coefficient (ADC) measurement could be used to identify parotid abnormalities in patients with CTD. METHODS: One neuroradiologist, who was unaware of patient histories, retrospectively measured the ADC values for the parotid glands in 121 patients who underwent clinically indicated brain MR imaging in which the parotid glands were sufficiently depicted. Regions of interest were obtained from both the left and right parotid glands. After the medical records were reviewed and exclusion criteria were used, 90 non-CTD and seven CTD patients (systemic lupus erythematosus = 5; discoid lupus erythematosus = 1; Sjögren syndrome = 1) remained. The two groups were then compared. Statistical analysis consisted of Wilcoxon sign rank and Mann-Whitney tests. RESULTS: The combined mean ADC for both parotid glands in 90 healthy patients was 0.50 +/- 0.28 x 10(-3) mm(2)/s (95% CI, 0.44 x 10(-3), 0.56 x 10(-3)). The combined mean ADC for both parotid glands in the seven CTD patients was 0.96 +/- 0.24 x 10(-3) mm(2)/s (95% CI, 0.79 x 10(-3), 1.14 x 10(-3)). The mean ADC for the CTD patients' parotid glands was significantly higher than that of the non-CTD patients (P =.0001), which suggests there is less restricted diffusion in parotid glands affected by CTD when compared with normal parotid glands. CONCLUSION: These results suggest that ADCs may be used to detect parotid abnormalities in patients with CTD that are not identified by standard imaging. Although preliminary, the results indicate a potential role for ADC mapping in detection of subclinical parotid disease.

Adolescent↗
PubMed2003

Making cost-effectiveness analyses clinically relevant: the effect of provider expertise and biliary disease prevalence on the economic comparison of alternative diagnostic strategies.

RATIONALE AND OBJECTIVES: This study was performed to assess the incremental cost-effectiveness of initial magnetic resonance cholangiopancreatography (MRCP) and initial endoscopic ultrasonography (EUS) compared with initial endoscopic retrograde cholangiopancreatography (ERCP) and to evaluate the effect of MRCP provider expertise on the relative cost-effectiveness of the three methods. MATERIALS AND METHODS: Thirty patients with suspected biliary disease and referred for ERCP were prospectively evaluated with EUS, MRCP, or ERCP within 24 hours of referral, according to institutional review board-approved protocol. Performance characteristics were measured for EUS and MRCP, with ERCP as the reference standard. A decision analysis compared the clinical and economic effects of three diagnostic strategies (ERCP, EUS followed by ERCP [EUS-ERCP], and MRCP followed by ERCP [MRCP-ERCP]) using prospective EUS and MRCP test characteristics and Medicare reimbursements. The added costs per additional correct diagnosis and per additional false-positive finding averted and the rates and costs of ERCP-related complications were calculated for EUS-ERCP and MRCP-ERCP. Two additional MRCP readers reviewed MRCP data to evaluate interobserver variability and estimate provider expertise. Additional economic analyses incorporated these estimates. RESULTS: Compared with initial ERCP, EUS-ERCP demonstrated 72% of biliary abnormalities and reduced ERCP-related complications by 60%; the corresponding percentages for MRCP-ERCP were 48% and 40%. Initial EUS and initial MRCP decreased the number of ERCP procedures performed by 69% and 49%, respectively. Each correct diagnosis made with ERCP that would not have been made with initial EUS or initial MRCP cost an additional 4,875 dollars or 2,580 dollars, respectively. Each false-positive diagnosis averted with initial ERCP that would have been made with EUS-ERCP or MRCP-ERCP cost an additional 9,750 dollars or 1,548 dollars, respectively. The decision model was most sensitive to disease prevalence. As provider expertise increased, the additional cost of an additional correct diagnosis increased for ERCP compared with MRCP-ERCP, with disease prevalence accentuating provider effects. CONCLUSION: Initial EUS and initial MRCP are less costly than initial ERCP, but provider expertise, biliary disease prevalence, and procedural costs influence incremental cost-effectiveness.

Biliary Tract Diseases↗
PubMed2003

Diagnostic accuracy of 2-[fluorine-18]fluro-2-deoxy-D-glucose positron emission tomography imaging in nonsquamous tumors of the head and neck.

PURPOSE: To evaluate the diagnostic accuracy of 2-[fluorine-18]fluro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for detecting nonsquamous tumors of the extracranial head and neck (NSTHN). MATERIALS AND METHODS: The records of all patients with suspected or proven NSTHN undergoing PET imaging in our institution over a 12-year period were reviewed. Forty-four patients (24 males and 20 females; age range, 6-81 years; mean age, 51.2 years) were classified into 3 main groups: thyroid tumors (n = 19), salivary gland tumors (n = 7), and miscellaneous lesions (n = 18). The PET findings for each individual group with respect to the primary site, cervical nodal and distant metastases, were correlated with histopathology or follow-up (2-year minimum) RESULTS: The overall diagnostic accuracy of FDG-PET for all NSTHN was 86%, However, the diagnostic accuracy varied for the histologic subtype (thyroid, salivary, miscellaneous) and the area being evaluated (primary site, nodal metastases, distant metastases). CONCLUSION: There is variable diagnostic accuracy of FDG-PET in detecting different histologic subtypes of NSTHN. This information should be taken into consideration when considering PET for evaluation of NSTHN.

Adolescent↗
PubMed2003

Percutaneous stenting of incidental unilateral renal artery stenosis: decision analysis of costs and benefits.

PURPOSE: To determine the incremental cost-effectiveness of prophylactic percutaneous transluminal angioplasty with stent placement (PTA-S) in patients with incidentally discovered, asymptomatic renal artery stenosis (RAS) compared to delaying PTA-S until patients develop refractory hypertension or renal insufficiency (therapeutic PTA-S). METHODS: The Markov decision analysis model was used to determine the incremental cost per quality adjusted life year (QALY) saved for prophylactic PTA-S as compared to therapeutic PTA-S in a hypothetical cohort of patients with 50% unilateral atherosclerotic RAS followed from age 61 to death. RESULTS: Prophylactic PTA-S compared to therapeutic PTA-S results in more QALYs/patient (10.9 versus 10.3) at higher lifetime costs ($23,664 versus $16,558). The incremental cost effectiveness of prophylactic PTA-S was estimated to be $12,466/QALY. Prophylactic stenting was not cost effective (>$50,000/QALY) if the modeled incidence of stent restenosis exceeded 15%/year and the incidence of progression in the contralateral renal artery was <2% of arteries/year. CONCLUSIONS: PTA-S of incidental, asymptomatic unilateral RAS may improve patients' quality of life at an acceptable incremental cost. However, this technology should be used hesitantly until a randomized comparison confirms its effectiveness.

Angioplasty, Balloon↗
PubMed2003

Effectiveness of MR imaging in characterizing small hepatic lesions: routine versus expert interpretation.

OBJECTIVE: The aim of our study was to compare the effectiveness of MR imaging characterization of small (<or=2 cm) hepatic lesions made in a routine clinical setting with the effectiveness of such characterization made under standardized conditions by radiologists who are expert interpreters of MR imaging. MATERIALS AND METHODS: Forty-eight patients with 69 small (<or=2 cm) hepatic lesions considered indeterminate on a prior routine CT scan were included in the study. The diagnosis for all lesions had been verified by histology (n = 10), surgery and intraoperative sonography (n = 5), imaging follow-up (n = 35), or clinical follow-up (n = 19). Using the initial radiology reports, the diagnoses based on MR imaging were rated on a 5-point confidence scale. In addition, two radiologists experienced in MR imaging who were unaware of the initial interpretations of the images or the clinical histories of the patients independently analyzed the MR imaging studies and characterized the lesions using the same 5-point scale. The observer performance for the initial MR imaging interpretations and the expert interpretations were measured using receiver operating characteristic analysis. Interobserver agreement was determined with weighted kappa statistics. RESULTS: Fifty-eight lesions were benign (six cysts, 22 hemangiomas, four regenerating nodules, two steatohepatitic lesions, one atypical blood vessel, three focal fat and five focal fat-sparing lesions, 13 flow-related pseudolesions, one diaphragmatic insertion, and one unspecified lesion), and 11 lesions were malignant (nine metastases and two hepatocellular carcinoma). The areas under the curve were 0.94 (initial reports), 0.88 (observer 1), and 0.84 (observer 2). Substantial agreement was found between the expert interpreters (kappa = 0.74), and moderate agreement, between the expert interpreters and initial interpreters (kappa = 0.44 each). CONCLUSION: MR imaging is an effective method of characterizing small (<or=2 cm) hepatic lesions in routine clinical practice.

Adult↗
PubMed2003

Developing a prediction rule to assess hepatic malignancy in patients with cirrhosis.

OBJECTIVE: The objectives of our study were to identify independent clinical, demographic, and MR imaging correlates of malignancy in patients with cirrhosis and to develop a predictive model based on identified correlates of malignancy. MATERIALS AND METHODS: Sixty examinations of 58 patients with biopsy proof of lesions suggestive of hepatocellular carcinoma on MR imaging were retrospectively reviewed. The signal intensity of the lesion on T2-weighted imaging and dynamic gadolinium-enhanced imaging, the size of the lesion, and the number of suspicious lesions were recorded; in addition, patient age and sex, alpha-fetoprotein level, and hepatitis C viral genotype were noted. The association between malignancy and each predictor variable was evaluated using the chi-square test or the two-group t test. The final logistic regression model included the variables that were shown to have a significant association with malignancy and the clinically relevant predictors. We used the adjusted odds ratios to measure the strength of each association. The discriminant ability of the model for detecting hepatic malignancy was assessed using receiver operating characteristic curve analysis. RESULTS: The prevalence of hepatic malignancy in our study population was 64%. The area under the receiver operating characteristic curve for the logistic regression model was 0.82. Venous washout (odds ratio = 9.2), alpha-fetoprotein level (odds ratio = 3.2), and number of lesions (odds ratio = 1.5) were significant predictors for malignancy (p < 0.05). When arterial enhancement and venous washout were either both present or both absent, alpha-fetoprotein level contributed little to the prediction of malignancy. CONCLUSION: The MR characteristics of hepatic lesions during the dynamic venous phase in conjunction with the serum alpha-fetoprotein level and number of lesions are predictors of hepatic malignancy. The use of these predictors can facilitate explicit estimation of malignancy in individuals with underlying cirrhosis, potentially improving clinical decision-making.

Adult↗
PubMed2003

Incorporating patient-centered outcomes in the analysis of cost-effectiveness: imaging strategies for renovascular hypertension.

OBJECTIVE: Our aim was to assess the contribution of patient-centered short-term disutilities and quality-of-life measures in the cost-effectiveness analysis of CT angiography, MR angiography, and conventional angiography in patients with medication-resistant hypertension. MATERIALS AND METHODS: A decision analytic model compared the life expectancy and incremental cost per life year using three initial diagnostic tests in a cohort of hypothetical individuals with medication-resistant hypertension over a range of renal artery stenosis probabilities: CT angiography (sensitivity, 96%; specificity, 96%; cost, $865); MR angiography (98%, 94%, $850); and conventional angiography (99%, 99%, $2,627). All imaging strategies were compared with a base case scenario mimicking the natural history of medication-resistant hypertension and with a scenario immediate enhanced medical therapy without prior imaging. Individuals without evidence of renal artery stenosis on initial testing underwent conventional angiography if enhanced medical therapy failed to control hypertension. Individuals diagnosed with renal artery stenosis on MR angiography required conventional angiography for definitive stent treatment ($11,1223). Blood pressure response to renal artery stenting or enhanced medical therapy varied according to blood pressure, as did the incidence of myocardial infarction and stroke resulting from hypertension. Patients who progressed to end-stage renal disease received dialysis ($60,000 per year). Quality-of-life adjustments were made for patients with hypertension, end-stage renal disease, myocardial infarction, and stroke. Short-term disutilities from undergoing an imaging test were included. The analysis accounted for direct costs derived from Medicare reimbursements and total costs derived from the literature. RESULTS: All imaging strategies were cost-effective compared with enhanced medical therapy alone or with natural history. When only direct costs were considered, MR angiography was the preferred strategy, with conventional angiography as a cost-effective alternative to MR angiography. When total costs were considered, conventional angiography dominated all other strategies. Adjusting for quality of life decreased the incremental cost-effectiveness ratios, making an already competitive strategy a more favorable alternative to the base case. Adjusting for test-related disutility did not significantly influence the cost-effectiveness of any of the imaging tests. Despite marked variation in the key clinical and cost variables, MR angiography remained the most cost-effective strategy. CONCLUSION: In the evaluation and treatment of medication-resistant hypertension, strategies that included preliminary imaging saved more lives than did the immediate institution of enhanced medical therapy at a lesser cost.

Cost-Benefit Analysis↗
PubMed2002

Biliary imaging with Gd-EOB-DTPA: is a 20-minute delay sufficient?

RATIONALE AND OBJECTIVES: The authors performed this study to quantitate the change in intrabiliary signal intensity 20 minutes after gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) injection and to correlate the degree of biliary visualization with changes in biliary signal intensity. MATERIALS AND METHODS: Sixteen patients with known hepatic masses (without known biliary disease) who were candidates for resection were enrolled in an open-label protocol of Gd-EOB-DTPA. Three-dimensional spoiled gradient-echo magnetic resonance (MR) images obtained in the coronal plane with breath holding before and 20 minutes after Gd-EOB-DTPA made up the biliary MR cholangiogram study. Manually defined regions of interest were used to measure signal intensity in the bile ducts before and after contrast material administration. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated. Biliary visualization was qualitatively assessed by using a five-point scale. RESULTS: The SNR and CNR significantly increased (P < .0002) after the administration of contrast material. Average biliary visualization ratings were excellent, with moderate to excellent interobserver agreement. There was no correlation between measured SNR or CNR and visualization ratings. CONCLUSION: A 20-minute delay after Gd-EOB-DTPA administration appears to be sufficient for adequate biliary enhancement. Residual hepatic enhancement does not appear to interfere with biliary visualization.

Adult↗
PubMed2002

Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid as an intrabiliary contrast agent: preliminary assessment.

OBJECTIVE: We assessed the added efficacy of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (gadolinium-EOB) in depicting biliary structures compared with T2-weighted MR cholangiopancreatography (T2-MRCP) and measured reviewer preference and willingness-to-pay for the added value of biliary contrast. SUBJECTS AND METHODS: Ten patients prospectively underwent T2-MRCP and gadolinium-EOB-enhanced MR cholangiography (EOB-MRC). Three radiologists reviewed the unpaired, then the paired, examinations, rating biliary visualization using a 5-point scale. The common bile, right and left hepatic ducts, and second-order branches were evaluated. Improved biliary visualization using paired over unpaired tests indicated the added value of contrast media. Kappa values measured interobserver reliability. A regression model controlling for fixed effects due to reviewer and subject correlation quantified improvement in ratings attributable to paired review. RESULTS: Average visualization ratings for unpaired review of EOB-MRC were the following: common bile duct, 3.3; right hepatic duct, 2.7; left hepatic duct, 2.5; second-order branches, 1.4. Average visualization ratings for unpaired review of T2-MCRP were the following: common bile duct, 3.4; right hepatic duct, 1.8; left hepatic duct, 2.2; second-order branches, 0.9. Ratings improved using paired tests over EOB-MRC and T2-MRCP for all structures (p < 0.001) except for T2-MRCP common bile duct ratings (p > 0.05). Agreement was moderate to good except for EOB-MRC common bile duct ratings. Paired review improved ratings (chi(2) < 0.0001) over T2-MRCP alone by 1.05 and over EOB-MRC alone by 0.68. Despite significant improvement, reviewers preferred unpaired T2-MRCP (53%) over unpaired EOB-MRC (17%) or paired tests (30%). Reviewers were willing to pay $25 (median) for gadolinium-EOB. CONCLUSION: Combining T2-MRCP and EOB-MRC significantly improved biliary visualization over each test alone. However, improvement was small, and the perceived added value of gadolinium-EOB was modest.

Adult↗
PubMedDate not supplied

Colorectal cancer screening behavior in women attending screening mammography: longitudinal trends and predictors.

PURPOSE: Nationally representative surveys demonstrate that the adherence to screening mammography guidelines are associated with increased prevalence of colorectal cancer (CRC) screening; however, the incidence of CRC screening in the screening mammography population is unknown. Our purpose was to describe non-fecal occult blood test (FOBT) CRC screening utilization by women prior to and subsequent to screening mammography at a large academic medical center. MATERIALS AND METHODS: Using the institutional administrative data base, 17,790 women aged 50 and older who underwent screening mammography between 1998 and 2002 were retrospectively identified. We determined that women were current with non-FOBT CRC screening at the time of mammography if they had undergone flexible sigmoidoscopy or double-contrast barium enema in the 5 years or colonoscopy since 1995, the earliest for which data are available. We excluded FOBT as a form of CRC screening because the administrative data base did not adequately capture episodes of FOBT. Women who were not current were considered eligible for non-FOBT CRC screening. We then assessed the number of women who underwent flexible sigmoidoscopy, barium enema, or colonoscopy within 12 months following mammography. Age, insurance status, Breast Imaging Reporting and Data System classification, recommendations after screening mammography and year of mammography were examined as potential predictors of non-FOBT CRC screening completion. RESULTS: At the time of mammography, 13.3% women were current with non-FOBT CRC screening. Of women eligible for non-FOBT CRC screening at the time of mammography, 1.1% completed non-FOBT CRC screening within 12 months after mammography. The rate of non-FOBT CRC screening completion increased over time. After multivariate analysis, being insured by a commercial managed care organization or by Medicaid remained significant predictors of non-FOBT CRC screening. CONCLUSION: The prevalence of non-FOBT CRC screening is low in the population of women undergoing screening mammography, with an incidence of 1.0%. Future studies should examine whether delivering CRC screening interventions at a screening mammography visit increase adherence to non-FOBT CRC screening.

Aged↗
PubMedDate not supplied

Computed tomography perfusion of squamous cell carcinoma of the upper aerodigestive tract. Initial results.

OBJECTIVE: To define the computed tomography (CT) perfusion characteristics of head and neck squamous cell carcinoma. METHODS: Fourteen consecutive patients with untreated squamous cell cancers of head and neck underwent CT of the head and neck along with CT perfusion imaging through the primary site. For the perfusion studies, CT density changes in blood and tissues were kinetically analyzed using the commercially available CT Perfusion 2 software (General Electric Medical Systems. Milwaukee, WI) on a GE Advantage Windows workstation. This yielded parameter maps of fractional tissue blood volume (mL/100 g), blood flow (mL x 100 g(-1) x min(-1)), mean transit time (s), and microvascular permeability surface area product (mL x 100 g(-1) x min(-1)). One head and neck radiologist analyzed perfusion data. Regions of interest (ROI) were placed over the primary tumor site, tongue base, and adjacent muscle groups. The average values of tissue blood volume (BV), blood flow (BF), mean transit time (MTT), and capillary permeability surface area product (CP) were then calculated for the tumor and compared with the average values for the tongue base and adjacent musculature. To determine a statistically significant difference between the tumor and muscle parameters, the Wilcoxon sign test, a nonparametric test for paired data, was employed. RESULTS: The average values of CP, BF, and BV were higher in primary tumor (41.9, 132.9, 6.2, respectively) than in tongue base or adjacent muscular structures. The MTT was reduced in primary tumors (4.0) compared with adjacent normal structures. The above differences were statistically significant (P<0.05). CONCLUSIONS: We obtained baseline perfusion data for head and neck squamous cell cancers and compared it with adjacent normal structures. Our initial results suggest that CT perfusion parameters (CP, BF, BV, and MTT) can be used to help differentiate head and neck squamous cell carcinoma (SCCA) from adjacent normal tissue.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Cardiovascular MR imaging: technique optimization and detection of disease in clinical practice.

Magnetic resonance (MR) imaging has emerged as an important and growing means of cardiovascular imaging, with many advantages over other radiologic modalities, including excellent spatial and temporal resolution, lack of ionizing radiation, and noninvasiveness. In this article, the utility of MR imaging in cardiovascular imaging and in the diagnosis of cardiovascular disease will be discussed. MR techniques for evaluating the heart and vasculature will be described, and troubleshooting techniques will be presented. Imaging findings in congenital anomalies such as septal defects, patent ductus arteriosus, transposition of the great arteries, and tetralogy of Fallot will be identified. Valvular lesions and methods for evaluating valvular function will be discussed. MR imaging findings in acquired disorders such as aneurysms and pericardial disease will be described.

Cardiovascular Diseases↗