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R Tello

Publications and source records attributed to R Tello.

At least 55 records · Page 3Linked to original sources
PubMed1992

Spiral CT of the thorax with reduced volume of contrast material: a comparative study.

The effectiveness of spiral computed tomography (CT) of the thorax performed with 60 mL of 60% contrast material was compared with that of conventional dynamic incremental CT performed with 120 mL of 60% contrast material. Fifty patients in whom contrast material-enhanced thoracic CT examination was necessary were assigned to undergo either spiral CT or dynamic incremental CT. Vascular opacification and mediastinal-lung image quality were graded independently by two observers. Vascular opacification and lung image quality were better with spiral CT than with conventional CT. Results of this pilot study encourage the use of spiral CT to decrease the volume of contrast medium used in patients undergoing thoracic CT.

Adult↗
PubMed1992

Assessment of the thoracic aorta by spiral CT.

A recently developed technique, spiral CT, allows rapid data acquisition through an entire anatomic region during a single breath-hold. High-quality spiral CT scans of the thoracic region have been obtained with volumes of contrast material that are small relative to those used with conventional CT. This essay illustrates the diseases of the aorta as seen on spiral CT performed with low volumes of contrast material.

Aged↗
PubMed1985

Flow determination using computed tomography: application to aortic dissection. Part I.

The CT method of flow determination evaluated in this study was based on the application of contrast enhancement dynamics. In order to characterize flow, such parameters as mean transit time, rise time, peak CT value, curve width and variance, and others were derived from the venoarterial indicator dilution curves using a perfect mixers-in-series model of curve fitting analysis and a bolus injection of contrast medium. The technique was first validated in a steady state phantom model that simulated in vivo conditions of right-sided mixing closely by the introduction of a number of mixers. A series of flows through small tubes was measured. Good correlation was obtained (r = .85). For a fixed number of mixers, the central second moment of the primary peak of the indicator dilution curve or variance decreased with increasing flow and peak CT value increased. Applied to the clinical situation, this method would allow characterization of blood flow using an intravenous bolus of contrast.

Aortic Dissection↗
PubMed1982

Single dose treatment with praziquantel (Cesol R, EmBay 8440) of human cestodiasis caused by Diphyllobothrium pacificum.

Diphyllobothrium pacificum, a large tapeworm of seals, is often found as an accidental parasite of man in Perú. The main symptoms is causes are abdominal pain, meteorismus and flatulence, and diarrhea. We report the results of 32 single-dose (10 mg/kg weight) treatments with Praziquantel (Cesol R, EmBay 8440) in 31 patients. One of these patients was shown to be cured but presented a reinfection 270 days later, and required retreatment. Praziquantel was effective in all cases. All patients were clinically cured. No ova were found in stool examinations at 30, 60, and 90 days after treatment, while pretreatment stools were positive for ova with all the techniques used. The antiparasitic effect was evident in 11 cases which segments of the tapeworm were eliminated within the first 3 days of treatment: the fragments were all partially digested or autolysed. A treatment scheme incorporating a purge may be best, to recover the parasite in its entirety and thus ascertain cure with no repeated controls.

Adolescent↗
PubMedDate not supplied

MR perfusion imaging of the kidney pre- and post-dipyridamole stress.

Animal studies have demonstrated that renal MR contrast enhancement depends on the timing of image acquisition. Limited human studies have demonstrated effects of dipyridamole (DP) on total renal perfusion. This study assessed the effect of DP on total and regional renal perfusion using gated perfusion MRI for patients undergoing DP stress. Five subjects with no evidence of renal ischemia were examined at rest and after DP stress. Rest MRI images in the left kidney were acquired using electrocardiogram (ECG)-gated MR: turbo fast low-angle shot (FLASH); echo time (TE) = 12, repetition time (TR) = 6, flip angle = 12, inversion time (TI) = 100) 10 to 45 seconds after injection of gadopentetate dimeglumine. Stress was induced in the MRI scanner (DP, .56 mg/kg over 4 minutes) followed by stress MRI after a second bolus of gadopentetate dimeglumine in the same position and identical time intervals. MR signal in the whole left kidney and renal medulla and cortex pre- and post-DP demonstrated a 70% depression of total renal perfusion with relative preservation of cortical perfusion at the expense of medullary perfusion. Post-DP MR images demonstrated a decrease in cortical perfusion with an additional 29% depression of medullary perfusion (P < .001) with respect to cortical perfusion. Turbo FLASH MRI can provide adequate time and spatial resolution to demonstrate changes in renal perfusion. Depression of renal medullary perfusion after DP appears to be caused by the intrarenal effect of DP and may have clinical impact.

Aged↗
PubMedDate not supplied

Standard dose Gd-DTPA dynamic MR of renal arteries.

Renal MR contrast enhancement depends on the timing of image acquisition. Limited human trials have demonstrated efficacy of renal artery stents on salvage of renal function. This study assessed the ability of dynamic gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) administration to demonstrate renal artery stenosis and renal stent patency compared to conventional angiography as the gold standard. Twenty subjects referred for renal angiography underwent 22 dynamic MR studies, including 7 with renal artery stenting (Palmaz P204 or P201, Johnson & Johnson, Sydney, Australia). All were examined with conventional angiography and after dynamic Gd-DTPA infusion. Coronal MR images of the kidneys were acquired using a GE Signa 1.5-T magnet (General Electric Medical Systems, Milwaukee, WI) (fast spoiled gradient echo [FSPGR]; TE=4.2 msec, TR=68-150 msec, flip angle=75 degrees) 0 to 600 seconds after iv bolus injection of 15 ml of Gd-DTPA during sequential breath-hold acquisitions, 13 to 32 seconds each. All 51 renal arteries (13 stenosed, 38 normal) were detected with dynamic MRI. Severity of renal artery stenosis was classified correctly with an accuracy of 98% (95% confidence interval [CI]: 85-100), yielding 98% specificity and 100% sensitivity. All nine renal stents were visualized with 100% accurate patency documentation. FSPGR MRI with bolus Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate renal artery stenosis.

Adult↗
PubMedDate not supplied

Case report: legionella infected thoracic aortic graft.

A case of a thoracic aortic graft in a patient with Marfan's syndrome infected with legionella is presented. The pathogenesis of graft infection and aspects of examination with aortography, gallium scanning, magnetic resonance imaging (MRI), and spiral volumetric computed tomography (CT) are presented, and the pathophysiology and management of thoracic aortic graft infections is briefly discussed.

Aortic Dissection↗
PubMedDate not supplied

Comparison of spiral CT and conventional CT in 3D visualization of facial trauma: work in progress.

Spiral computed tomography (SCT) differs from conventional CT (CCT) in that regions of the body can be rapidly imaged via continuous scanning. This is accompanied by simultaneous advancement of the patient, thus allowing volumetric data acquisition of up to 60 cm in less than a minute. Thus motion is minimized and slice misregistration is minimized when multiplanar and three dimensional reconstructions are performed. This paper compares the utility of SCT and CCT in facial trauma. A total of six patients were studied with either CCT or SCT of the face after trauma. SCT scans were obtained using a Siemens Somatom Plus-S CT scanner (2 mm thick collimation and 3 mm/sec table feed for 32 s). Three-dimensional (3D) and multiplanar reconstruction images of the facial bones were generated after appropriate thresholds were selected by the radiologist; similar images generated with a CCT (GE quick 9800) were compared using a three point scale with kappa analysis. SCT is able to generate axial and reformatted images of comparable quality to CCT (k = 0.47-0.89) in less than half the time to perform an examination (26 min vs 63 min). SCT can rapidly produce (3D) and multiplanar reformatted images of facial trauma with minimal motion, or misregistration artifact when compared to CCT.

Adult↗
PubMedDate not supplied

Biliary tree necrosis in transplanted liver detected by spiral CT with three-dimensional reconstruction.

We present a case where spiral computed tomography (CT) with three dimensional reconstruction was able to generate cholangiographic images demonstrating biliary tree necrosis in a transplanted liver. Volumetric CT as a one step diagnostic solution to establish a diagnosis in patients after liver transplantation can expedite appropriate therapy and reduce the number of invasive studies. By the integration of volumetric CT techniques and rapid three-dimensional display of biliary structures, volumetric cholangiography may become practical. Though spatial resolution may prove to be a limiting factor in replacing cholangiography for subtle mural disease, volumetric CT can yield clinically useful information.

Bile Ducts, Intrahepatic↗
PubMedDate not supplied

MR hysterography using axial long TR imaging with three-dimensional projections of the uterus.

A rapid screening technique for the presentation of uterine cavity anatomy obtained with MR is described. MR hysterographic (MRHG) images were generated and evaluated for uterine cavity abnormalities. Six patients referred for MRI evaluation of the uterus for infertility had an MRI using a pelvic phased array coil with axial 3 mm interleaved fast spin echo images (TR 9000 ms, TE 288 ms with fat saturation) processed using maximum intensity projection algorithms to construct MRHG images. Using the conventional MR sequence as the gold standard the MRHG images were evaluated by two reviewers and accuracy calculated. MRHG took less than 3 min, demonstrated the correct diagnosis in all with a quality score of diagnostic to optimal, and with excellent interobserver agreement (kappa 0.9).

Adult↗
PubMedDate not supplied

Value of spiral CT in hemodynamically stable patients following blunt chest trauma.

INTRODUCTION: Features of spiral CT (SCT)-fast scanning, dynamic injection of contrast allowing optimal vessel opacification, and supplemental multiplanar imaging-promises to provide increased accuracy in the diagnosis of acute and non acute thoracic vascular disease. Recent work demonstrating the cost effective triage of hemodynamically stable patients after blunt chest trauma for angiography based on dynamic CT findings has prompted an investigation into the accuracy of SCT in this clinical setting. METHODS: A retrospective review of all patients seen in the emergency department over the period of one year for aortic, thoracic, or blunt chest trauma evaluation was performed (74 patients) and all SCT scans available were reviewed and data reformatted for optimal delineation of pathology using maximum intensity projection and multiplanar reformation. The accuracy and predictive positive and negative values of SCT were calculated with respect to angiography, surgical, and/or clinical follow up evaluation. RESULTS: Twenty three (31%) patients went directly to angiography owing to mediastinal widening on chest film and hemodynamic instability, of which four were positive and required emergent surgery. Seven hemodynamically stable patients (9%) had noncontrast SCT owing to mediastinal widening on chest film, all of which had angiography with none having great vessel trauma. Fourty four hemodynamically stable patients (60%) had contrast enhanced SCT (ceSCT), of which five (11%) were abnormal and underwent angiography, four of these were positive for aortic damage, one for a subclavian artery laceration. Of the remaining 39 patients who had normal ceSCT; five had angiography, all of which were normal. Of the remaining 34 patients that had normal ceSCT none had adverse outcome on clinical follow-up, minimum of 12 months. CONCLUSION: The predictive positive value for aortic trauma of ceSCT in blunt trauma is 80%, with a predictive negative value of 100%, indicating that it is feasible for SCT to be a first line exam in blunt chest trauma in the future.

Adult↗
PubMedDate not supplied

MRI isolation of infected renal cyst in autosomal dominant polycystic kidney disease.

The use of gadolinium-enhanced magnetic resonance (MR) to isolate an infected renal cyst in the setting of autosomal dominant polycystic kidney disease (ADPKD) has not been previously described. A case in which T1- and T2-weighted and gadolinium-enhanced MR images were used to identify a single purulent cyst in a patient with ADPKD is herein presented. We suggest that gadolinium-enhanced MR be considered useful in the evaluation of ADPKD patients with suspected infected cyst.

Anti-Bacterial Agents↗
PubMedDate not supplied

In vitro and in vivo effects of three bismuth compounds on fermentation by colonic bacteria.

Three bismuth compounds (tripotassium dicitrate bismuthate, bismuth subsalicylate, and bismuth subnitrate) were tested in vitro and in vivo for their effect on fermentation by colonic bacteria. The studies in vitro were done with use of a technique designed to determine the effect of each one of the bismuth compounds on the fermentation of several stool samples that had been mixed with lactose as additional fermentable substrate (fermentation of lactose-enriched stools, FLES). The three bismuth compounds reduced FLES significantly in 47 (81%) of 58 of the stool samples used to test their effect. Bismuth subsalicylate, which reduced FLES in 10 of 10 stool samples, showed the greatest reduction (mean reduction, 74%; P less than .0001). The in vivo studies, done in six flatulent patients, showed significant reduction (P less than .01) of colonic fermentation of ingested raffinose by oral bismuth subnitrate given for 8 days.

Adolescent↗
PubMedDate not supplied

Spiral CT evaluation of coronary artery bypass graft patency.

Spiral CT (SCT) differs from conventional CT in that the entire heart can be rapidly imaged in the axial plane following the peripheral infusion of small quantities of contrast material. As contrast material travels through coronary artery bypass graft segments, good image detail is achieved, allowing visualization of entire coronary artery graft segments during a single injection. The patency of 43 coronary artery bypass grafts in 14 patients on contrast enhanced SCT, with timing tailored to patient-specific transit times, was compared with that obtained by selective graft angiography. With use of 5 or 8 mm/s table feed and 24 s volumetric acquisitions, SCT established graft patency with 85.7% sensitivity and 100% specificity compared to angiographic examination (96.4% sensitivity and 100% specificity). The mean time between angiography and SCT was 2.1 days, with 86% of SCT studies done within 24 h after angiography. The utilization of dynamic scanning to establish the patient-specific time delay prior to initiation of SCT proved crucial in improving the quality and reliability of SCT bypass graft patency assessment. The paired McNemar test indicates no significant difference between angiography and SCT in establishing patency rates.

Aged↗
PubMedDate not supplied

A contrast agent delivery nomogram for hepatic spiral CT.

PURPOSE: A nomogram for hepatic spiral CT (SCT) was constructed based on randomization of patients into a prospective study using four different injection protocols. Its utility in a separate prospective randomized trial was subsequently evaluated in a new group of patients. METHODS: Thirty-nine patients randomized into four groups underwent SCT (Somatom-Plus S; 24 s exposure, 10 mm collimation, 10 mm/s) using 90 ml Omnipaque 240 (22 g I) at 2.5, 4, 5, or 6 ml/s. Peak and mean aortic and liver enhancement and time to peaks were measured and correlated with patients' age, weight, dose, rate, and contrast agent concentration, and a nomogram was constructed. In the validation experiment, 20 new patients were randomized to nomogram-guided and control groups for contrast dose administration during SCT. All patients underwent SCT (Somatom-Plus S; 32 s exposure, 10 mm collimation, 10 mm/s) using 90 ml Omnipaque 240 or 140 ml Hypaque 60 at 1.5-6 ml/s. Peak and mean aortic and liver enhancement and time to peaks were measured and correlated with patients' age, weight, dose, rate, and contrast agent concentration. Mean and peak aortic and hepatic enhancements were measured and rated by three blinded reviewers. RESULTS: Peak hepatic enhancement occurred 32 s after termination of contrast bolus administration in all groups. Correlation between the predicted and actual enhancement was very good (r = 0.7-0.9). Ninety-eight percent of the nomogram-guided group had optimal timing and utilized 10% less contrast agent than the control group. CONCLUSION: The phenomenon of peak hepatic enhancement occurring 32 s after the termination of contrast bolus regardless of injection rate may be of use in a nomogram for optimal contrast delivery for hepatic SCT.

Contrast Media↗
PubMedDate not supplied

Signal characteristics of focal liver lesions on double echo T2-weighted conventional spin echo MRI: observer performance versus quantitative measurements of T2 relaxation times.

PURPOSE: The purpose of this work was to evaluate the ability of expert readers to differentiate benign from malignant liver lesions based on visual assessment of lesion signal intensity on double echo T2-weighted conventional spin echo (CSE) MR images and to compare reader performance with quantitative measurements of T2 relaxation times. METHOD: Sixty-seven MR examinations demonstrating 85 liver lesions (37 hemangiomas, 32 malignancies, 15 cysts, and 1 focal nodular hyperplasia) on double echo T2-weighted CSE sequences (TR 3,600 ms/TE 50, 160 ms) were qualitatively reviewed by three independent readers. T2 relaxation times were calculated for each lesion. Receiver operating characteristic (ROC) analyses of expert readers were compared with calculated T2 relaxation times. RESULTS: T2 values performed significantly better than subjective reader analysis for liver lesion characterization (area under ROC = 0.93 vs. 0.81, 0.78, and 0.75; p < 0.0001). With use of a T2 threshold of 125 ms, the sensitivity of T2 values for malignant lesions was 100%, specificity 71%, and accuracy 84%. By comparison, the sensitivity of the three readers for malignant lesions was 76-83%, with a specificity of 61-72% and an overall accuracy of 71-80%. CONCLUSION: Despite expert reader analyses, subjective evaluations of liver lesion signal characteristics are prone to inaccuracy and lack certainty and consistency when intermediate TEs (50/160 ms) are used. Quantitative measurements of T2 relaxation times should be performed to accurately and confidently differentiate benign from malignant liver lesions. Use of a higher T2 threshold than previously recommended is required to avoid misclassification of malignancies.

Adult↗