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Biomedical subjects

W E Torres

Publications and source records attributed to W E Torres.

At least 19 recordsLinked to original sources
PubMed1996

Anatomic variation of extrahepatic biliary tree structures: importance in treatment planning for radiation therapy.

PURPOSE: To demonstrate the variable location of biliary tree components and to assess two treatment planning rules of thumb used for locating porta hepatic nodes for radiation therapy. MATERIALS AND METHODS: The distance of the common hepatic duct bifurcation and duodenal papilla from adjacent vertebral bodies was measured on 34 cholangiograms, and their relationships to particular vertebral body levels were recorded. Adequacy of treatment volume to encompass porta hepatic lymph nodes was evaluated in 30 of these cholangiograms by constructing radiation portals according to the two rules of thumb. RESULTS: Location of the common hepatic duct bifurcation and duodenal papilla varied widely. The treatment portal encompassed 13% (four of 30) of cases when the first rule of thumb was used and 80% (24 of 30) of cases when the second rule of thumb was used. CONCLUSION: The wide variability of location of extrahepatic biliary tree structures suggests the need for individualized treatment planning so that sensitive and dose-limiting healthy tissues can be optimally excluded from radiation treatment portals. Computed tomography and other imaging modalities enable precise location of biliary tree components for radiation treatment planning.

Ampulla of Vater↗
PubMed1996

Measurement of coronary artery calcium with dual-slice helical CT compared with coronary angiography: evaluation of CT scoring methods, interobserver variations, and reproducibility.

OBJECTIVE: This study was performed to evaluate new scoring methods for quantitating coronary artery calcifications with helical CT and to compare the results with those of quantitative coronary angiography in patients with suspected coronary artery disease. SUBJECTS AND METHODS: Unenhanced dual-slice helical CT and coronary angiography were performed within 24 hr of each other in 101 patients with symptoms of coronary artery disease. Coronary artery calcifications with a density above 90 H were identified on each slice and, with the same regions of interest, quantitative scoring was performed at thresholds of 90 H (new) 130 H (old). Two mathematical algorithms (one new and one old) were evaluated for both thresholds (yielding four scoring systems). By CT imaging, we defined disease as a score of greater than zero. By angiography, we defined disease as a 50% or greater reduction in the luminal diameter of any major vessel. Interobserver variations in calcification scoring were evaluated. Seventeen of our patients. also underwent a second, consecutive CT scan to determine reproducibility. RESULTS: With the new threshold and the new algorithm, the sensitivity, specificity, and accuracy of helical CT in predicting disease were 88%, 52%, and 76%, respectively. We found a moderate positive association between the total CT calcification score and the number of stenotic coronary arteries at angiography (Pearson's correlation coefficient, .43; p = .05 [analysis of variance]). The accuracy and the area under the receiver operating characteristic curve were higher with the new threshold and the new algorithm. Interobserver agreement in calcification scoring was high (intraclass correlation coefficient, .99 [n = 85]), as was reproducibility (intraclass correlation coefficient, .94 [n = 17]). Reproducibility was higher when scoring was based on the new threshold and the new algorithm. CONCLUSION: The quantity of coronary artery calcifications as measured by helical CT correlated positively with obstructive coronary artery disease as measured by angiography. Interobserver agreement and reproducibility were excellent. A new scoring method showed promise.

Adult↗
PubMed1996

Single lung transplantation followed by contralateral bullectomy for bullous emphysema.

BACKGROUND AND METHODS: Single lung transplantation for emphysema is now standard practice despite initial concerns, including the possibility that the compliant diseased lung would compress the transplanted lung as a result of hyperinflation. We describe a patient with severe bilateral bullous emphysema and alpha-1-antitrypsin deficiency who underwent single lung transplantation after which hyperinflation of the native lung led to significant compression of the pulmonary allograft. The patient subsequently underwent bullectomy of the contralateral lung with marked improvement in his functional status. RESULTS: After bullectomy, the patient's forced expiratory volume in 1 second increased from 1.77 to 2.82 L, his total lung capacity fell from 7.23 to 6.19 L, and his 6-minute walk increased from 724 to 1269 feet. However, 7 months after bullectomy, there was evidence that the bullous disease in the native lung was recurring. CONCLUSIONS: Significant hyperinflation of the native lung with compromise of the pulmonary allograft can occur after single lung transplantation for bullous emphysema. Bullectomy of the diseased lung after transplantation improved allograft function in our patient. Alternatively, bilateral lung transplantation for severe bilateral bullous emphysema may be considered.

Humans↗
PubMed1992

Optimizing gallbladder stone lithotripsy: an international survey.

Rates of stone clearance with extracorporeal shock wave cholecystolithotripsy (biliary lithotripsy [BL]) initially reported by European groups were encouraging. An American multicenter BL study (the Dornier National Biliary Lithotripsy Study [DNBLS]) did not reproduce these results. The BL treatment strategies and 6-month stone clearance rates of six leading European and Japanese centers were compared with those of DNBLS. All foreign centers used adjuvant oral chemolitholysis and greater shock wave energies from the same lithotriptor as that in DNBLS. Six months after BL, the stone clearance rates at all six centers were higher than those of DNBLS. There were no significant differences in complication rates between centers. These findings suggest that the poor results of DNBLS were chiefly due to the use of low kilovoltage and few BL sessions. Increased energy levels and a fragment size end point of less than 5 mm optimize BL. Despite the popularity of laparoscopic cholecystectomy, BL can be recognized as a successful treatment alternative for patients with a low burden of radiolucent stones.

Cholelithiasis↗
PubMed1992

Abnormalities of the gallbladder after extracorporeal shock-wave lithotripsy: imaging findings.

To qualify for treatment with biliary extracorporeal shock-wave lithotripsy (ESWL), patients must have sonograms that show gallstones and oral cholecystograms (OCGs) that show normal opacification (indicating normal function) of the gallbladder. We have noted that sonograms and OCGs made 6 weeks to 6 months after ESWL sometimes show abnormalities that were not visible on these images before ESWL. In these cases, the gallbladder appears contracted on sonograms and is poorly visualized on OCGs. To determine how often this occurs and to study its significance, we analyzed the posttreatment sonograms and OCGs in 174 patients who underwent ESWL. After ESWL, sonograms showed a contracted gallbladder and OCGs showed poor function in 25 (14%) of the 174 patients. One patient (4%) was lost to follow-up. In 17 (68%) of the 25 patients, the abnormalities were transient (findings on sonograms and OCGs returned to normal by 12 months after ESWL). In the other seven patients (28%), the abnormalities persisted (all seven subsequently had a cholecystectomy); this is a cholecystectomy rate twice that in the patients with normal findings on sonograms and OCGs after ESWL (20/149 or 13%). All 25 patients with abnormalities after ESWL had gallstone fragments at 6 weeks, as did 146 of the 149 patients with normal-appearing gallbladders after ESWL. When these abnormalities persist (in approximately one third of patients), cholecystectomy is often required. The cause of the abnormalities is unknown, although chronic cholecystitis, a process that is not detectable by pre-ESWL imaging techniques, seems likely.

Adolescent↗
PubMed1991

Comparison of ultrasonography and oral cholecystography in biliary lithotripsy. I. Screening patients.

Ultrasound and oral cholecystography (OCG) are both used to evaluate candidates for biliary lithotripsy. Some investigators have suggested abandoning the OCG, believing that sufficient screening information can be obtained from ultrasound. This study compares ultrasound and OCG in assessing the size and number of gallstones, both in vitro and in vivo. In the in vitro model, 35 gallstones, divided into 20 groups, were separately suspended in dilute contrast media in a phantom, and examined by ultrasound and simulated OCG by each of three gastrointestinal radiologists. In the in vivo study, the ultrasound and OCG examinations from 53 patients were independently reviewed by three radiologists. The number and size of the stones were recorded in both studies. In the in vitro study, the stone size was measured within 2 mm of the actual size by OCG in 23/35 stones (66%) and by ultrasound in 4/35 stones (11%). The correct number of stones was determined by OCG in 19/20 groups (95%), and by ultrasound in 14/20 (70%). In the in vivo study, all readers saw the same number of stones in 40/50 (80%) patients by OCG and 33/49 (67%) patients by ultrasound. Statistical analyses revealed correlation coefficients for OCG greater than those for ultrasound in each comparison. The size of the largest stone was within 2 mm by all readers in 26/51 (51%) of patients by OCG and 20/47 (43%) patients by ultrasound. Oral cholecystography is more reliable than ultrasound for the determination of size and number of stones in patients being screened for biliary lithotripsy.

Adult↗
PubMed1991

Comparison of ultrasonography and oral cholecystography in lithotripsy. II. Determining retreatment.

Both ultrasonography (US) and oral cholecystography (OCG) are being used to evaluate patients after extracorporeal shock wave lithotripsy (ESWL) for gallstones. Criteria for retreatment after the initial ESWL are usually related to the size of the residual fragments. This study examines the efficacy of ultrasound and OCG for determining both the size and number of stone fragments in the gallbladder in an in vitro model and in patients. Ultrasonography and OCG examinations using an in vitro ESWL phantom with ten groups of stones, and on 39 patients, were reviewed independently by three radiologists to determine both the size and number of stone fragments. For the in vitro study, the three readers estimated the correct number of fragments, or the next closest range, in 87% of observations by OCG and in 43% by US. The size of the largest fragment was measured within 1 mm of its actual size in 87% of observations by OCG and 20% by US. Correlation coefficients for the mean measurements of the three readers versus the actual fragment size and number were greater for OCG than for US. For the in vivo study, the three readers agreed in 47% of the OCG versus 32% of US examinations with respect to the number of fragments, and in 65% of OCG compared to 40% of US studies with respect to size of the largest fragment. Multiple statistical analyses demonstrate that these differences are statistically significant. A discrepancy among the readers concerning whether a patient was eligible for retreatment occurred in 15% of OCG as compared to 45% of US studies. Both the in vivo and in vitro studies indicate that there is more interobserver reproducibility for OCG than for US, and that OCG is more reliable in making the decision concerning patient eligibility for retreatment following lithotripsy.

Adult↗
PubMed1991

Oral cholecystography in contemporary gallstone imaging: a review.

The introduction of nonoperative alternatives to elective cholecystectomy in the management of gallstones has resurrected use of oral cholecystography (OCG). This article reviews basic principles involved in the proper performance of OCG and interpretation of the resulting images. The role of OCG in the current management of gallstones is discussed.

Bile↗
PubMed1991

Extracorporeal shock wave lithotripsy of gallstones: results and 6-month follow-up in 141 patients.

A study of biliary shock wave lithotripsy of gallstones sponsored by Dornier Medical Systems, Munich, began in the United States in May 1988 to evaluate the efficacy and safety of extracorporeal shock wave lithotripsy (ESWL) and the need for adjunctive therapy with ursodeoxycholic acid (UDCA). One hundred forty-one symptomatic patients with one to three gallstones 5-30 mm in diameter were randomized to treatment. One week before ESWL, patients were given either UDCA or placebo. This treatment was continued for 6 months. All patients underwent follow-up at predetermined intervals. According to the protocol, re-treatment for fragments larger than 5 mm in diameter could be performed only at 6 weeks; 26 (18%) of the 141 patients were retreated. At 6 months, the stone-free rates for single stones were as follows: patients with noncalcified stones receiving UDCA, 29%; patients with noncalcified stones receiving placebo, 24%; and patients with partially calcified stones receiving either UDCA or placebo, 6%. No significant difference was noted between the UDCA and placebo groups. At 6 months, the stone-free rates in patients with single, noncalcified stones 20 mm or less in diameter were 40% (UDCA) and 32% (placebo), which is superior to rates for those with solitary, noncalcified gallstones 21-30 mm in diameter and those with two or three stones.

Adult↗
PubMed1991

Shock wave lithotripsy of gallstones: results and 12-month follow-up in 174 patients.

At the authors' institution, as part of the on-going Dornier National Biliary Lithotripsy Study, 174 patients with gallstones were randomly assigned to receive either ursodeoxycholic acid (UDCA) or placebo for 6 months after undergoing extracorporeal shock wave lithotripsy (ESWL). Six weeks after ESWL, 40 (23%) patients were re-treated for gallstone fragments larger than 5 mm in diameter. No significant difference in the UDCA- and placebo-treated patients was noted. The overall 6- and 12-month stone-free rates for all patients with initially noncalcified stones were as follows: UDCA patients, 31% and 36%, respectively, and placebo patients, 21% and 23%, respectively (P less than .05). In patients with a single, noncalcified gallstone that was at most 20 mm in diameter, the 12-month stone-free rates were as follows: UDCA patients, 60%, and placebo patients, 33% (P less than .01). Patients with noncalcified stones that were 11-20 mm in diameter who were treated with UDCA had a higher rate of stone clearance than placebo patients. At 6 months, the authors' previous study demonstrated no significant difference in the two groups of patients. However, the stone-free rate at 12 months was noted to be significantly higher for patients with a single, noncalcified stone that was at most 20 mm in diameter begun on UDCA than for all other groups of patients.

Adolescent↗
PubMed1990

Biliary lithotripsy: in vitro analysis of gallstone fragmentation for equivalent stone volumes.

The relationship between gallstone fragmentation during extracorporeal shock wave lithotripsy (ESWL) and gallstone volume is poorly understood. Clinical results of ESWL show that the highest stone-free rate at 6 months occurs with radiolucent single gallstones 20 mm or less in diameter. In an in vitro study, individual gallstones from cholecystectomy specimens were divided by size and composition into nine single- and nine multiple-stone groups; the stones were then paired on the basis of similar volume. ESWL was performed in a phantom and the size of the largest fragment was measured at 500, 1,000, and 1,500 shock waves. At 1,500 shock waves, sandlike particles were present in six of nine single stones versus two of nine multiple stone groups; the mean size of the largest fragment at 1,500 shock waves was 2.1 mm (single) and 4.4 mm (multiple) in diameter. When corrected for volume, the authors' data suggest that single stones are more easily broken into fragments smaller than 5 mm in diameter than multiple gallstones. The implication, especially when spark-gap technology is used, is that more shock wave energy (ie, an increased number of shock waves at a higher kilovoltage) will be necessary to achieve the same results when treating patients with multiple stones versus a single gallstone with a similar stone volume.

Cholelithiasis↗
PubMed1990

Gallstone extracorporeal shock-wave lithotripsy: time and treatment considerations.

We evaluated 30 gallstone lithotripsy procedures performed on 27 patients with the Dornier MPL-9000 Lithotripter to determine how time was spent in the lithotripsy suite and to evaluate the various technical reasons for interrupting the administration of shock waves during the treatment. The procedure averaged 98 +/- 32 min total time in the lithotripsy suite. This included an average of 22 +/- 6 min before the treatment, 70 +/- 28 min for administration of shock waves, and 6 +/- 2 min after the treatment. The time required to deliver the shock waves did not correlate with patient age, sex, or weight; the number of gallstones; or the number or date of the treatment. However, a trend was seen toward an association between shorter treatment times and larger stone volumes. On the average, the administration of shock waves was interrupted every 48 shock waves for various reasons. Electronically changing the imaging plane of the in-line sonographic transducer to retarget the stone in the focal zone was by far the most frequent reason for interrupting shock-wave delivery, averaging 56 shock waves between changes. We conclude that extracorporeal shock-wave lithotripsy of gallstones is a time consuming and technically demanding procedure that requires continuous monitoring and frequent interruption in order to optimize targeting and fragmentation of the stone(s) while maintaining the patient's comfort.

Adult↗
PubMed1990

Technical aspects of biliary extracorporeal shock wave lithotripsy.

Radiologic imaging procedures play a major role in the evaluation of the potential patient for biliary extracorporeal shock wave lithotripsy, both during the procedure and in follow-up evaluation. The treating physician must have a thorough knowledge of ultrasonography techniques. Lithotripsy requires continual monitoring and frequent reassessment to optimize targeting and fragmentation of the gallstones while maintaining patient comfort.

Cholecystography↗
PubMed1990

A directed approach to MRI of the athletic knee.

Surface coil MRI is now frequently utilized to assess acutely injured knees. In dedicated athletes, unique considerations exist which modify standard diagnosis and therapy. Concrete clinical findings must justify the potential loss of livelihood from even a "negative" arthroscopy. Seventeen injured athletes were evaluated by an orthopedic surgeon experienced in sports injuries and a preliminary localizing diagnosis was rendered, followed by knee MRI. Of 17 patients with significant injuries, MRI agreed with operative findings or clinical follow-up in 15 cases. Knee MRI prompted early intervention in those patients with conflicting subjective and/or objective findings. Furthermore, it helped direct the arthroscopist's surgical approach and encouraged close examination of areas less optimally visualized arthroscopically. MR and arthroscopy were complementary modalities in diagnosing certain ligamentous and cartilaginous lesions. MR effectively evaluated the cruciate ligaments often difficult to visualize by arthroscopy; arthroscopy better assessed articular surfaces. A cooperative effort existed between orthopedic surgeon and radiologist in directing both the MR study and arthroscopy. This was of particular benefit in maximizing scan efficiency in these large individuals who often filled the gantry. The team directed approach between orthopedic surgeon and radiologist affords deliberate and efficient diagnosis and therapy in this select population.

Athletic Injuries↗