Comparison of ultrasound, CT, and MR imaging in the evaluation of candidates for TIPS.

To compare ultrasound (US), CT, and MRI in the evaluation of hepatic vascular anatomy, portal and splenic venous flow, and collateral pathways (varices and spontaneous shunts) in candidates for transjugular intrahepatic portosystemic shunting (TIPS), 17 patients with history of refractory variceal bleeding or intractable ascites underwent duplex US, contrast-enhanced CT, and MRI before TIPS. The appearance of portal and hepatic anatomy was graded from 1 (not visible) to 4 (excellent visualization) independently by four radiologists. Presence and direction of portal and splenic venous flow, and presence and location of varices and spontaneous portosystemic shunts were also assessed. Results and effects of interobserver variation were assessed for significance using Friedman's ANOVA and Wilcoxon's signed-rank test. MRI yielded higher scores than CT or US for hepatic veins (P < .0001) and inferior vena cava (P < .0001). MRI and CT scored better than US for portal vein branches (P = .012) and splenic vein (P = .0038). All tests demonstrated the main portal vein well, with no statistically significant difference. US and MRI were more sensitive than CT for detecting portal vein flow and direction (US 76%, CT 0%, MRI 82%). MRI was most sensitive for splenic vein flow and direction (US 41%, CT 0%, MRI 76%). CT and MRI were more sensitive than US in detecting varices (US 5%, CT 50%, MRI 58%) and spontaneous shunts (US 13%, CT 75%, MRI 75%). Interobserver variation did not influence results significantly P = .3691). MRI provides the most useful information and may be the preferred single imaging test prior to TIPS.

Evaluation of oral contrast agents for abdominal magnetic resonance imaging.

We evaluated the efficacy of six available oral contrast agents in improving visualization of bowel and surrounding structures on magnetic resonance imaging of the abdomen and pelvis. Five volunteers were examined without oral contrast (baseline) and, on separate occasions, after ingestion of 600-900 cc of two positive contrasts [12.5% weight-to-volume (w/v) corn oil emulsion (COE), Redi Cat (EZ-Em Corp., Westbury, NY) mixed with 1% ferric ammonium citrate (FAC)] and four negative contrasts [220%, 105%, 85%, 60% w/v barium sulfate (Liquid HD, Liquid Polybar Plus, HD 85, reconstituted EZ Pake; EZ-Em Corp., Westbury, NY)]. Spin-echo axial and coronal T1-weighted and axial T2-weighted images were obtained in the abdomen and pelvis. Three radiologists blindly graded the images for improved visualization of bowel and surrounding structures. Data were analyzed for statistical significance using the General Linear Models algorithm. In the upper abdomen (stomach, duodenum, liver, and pancreas), COE yielded the highest mean scores (p < .0001), followed by 220% w/v barium. For the lower abdomen (ileum, colon), 220% w/v barium yielded the highest scores (p < .0001) and COE was much worse. The higher density barium preparations (220% and 105% w/v) yielded higher scores than their lower density counterparts (85% and 60%). All contrasts improved visualization of the retroperitoneum and spleen, but no one agent was best. All agents tested are superior to no agent at all. For visualization of the upper abdomen, 12.5% COE performed best. For visualization of the lower abdomen, 220% w/v barium performed best. For concurrent evaluation of both areas with one agent, 220% w/v barium performed best.

Continuous versus intermittent acid exposure in production of esophagitis in feline model.

Our morphometric feline model of acid-induced esophageal damage histologically resembles human reflux esophagitis. The histologic scoring system includes intensity and linear extent of basal cell hyperplasia, intraepithelial and subepithelial segmented leukocytes, and ulcers. Each of these four categories is scored from 0 to 4, for a potential total score of 16. Some reports have indicated that the long-duration acid exposure episodes during recumbent nighttime reflux are apt to be associated with greater injury than shorter episodes during daytime upright exposure. We tested the hypothesis that longer single exposures to acid would incite greater morphologic damage in the cat than would multiple, shorter acid exposures. To study the influence of continuous versus intermittent hydrochloric acid exposure, groups of six cats each were infused continuously (single infusion) for 15, 20, or 30 min, and compared with cats infused for 2-min acid infusion times. Our studies indicate that total acid exposure and mucosal damage are more likely to be greater after multiple episodes of the same total duration with adequate clearing (ie, awake upright reflux) than after single long episodes of acid exposure that are poorly cleared (ie, sleeping).

Comparison of lower esophageal sphincter manometrics and gastroesophageal reflux measured by 24-hour pH recording.

We compared lower esophageal sphincter (LES) pressures to parameters of acid reflux measured during 24-h pH monitoring in 81 patients being evaluated for possible reflux disease. Mid-respiratory LES pressures were significantly higher (p less than 0.05) in patients with normal amounts of reflux than in those with abnormal reflux. This difference did not occur with LES pressure measured by end-expiratory station pull-through (SPT) or rapid pull-through (RPT). There was no significant difference in total length or intra-abdominal portion of LES between the two groups. However, the product of LES pressure and total LES length was greater (p less than 0.05) for patients with normal reflux than for these with abnormal reflux. No difference was noted in the percentage of abnormal contractions in the distal esophagus between groups. These studies support the following conclusions: 1) LES pressure may be a more important protective mechanism against reflux than LES length. 2) Mid-respiratory SPT technique appears to identify the LES antireflux barrier better than either end-expiratory SPT or RPT techniques. 3) Acid exposure time seems to be a better measure of gastroesophageal reflux than the number of reflux episodes.

Gastroesophageal reflux in runners. Characteristics and treatment.

STUDY OBJECTIVE: To test the potential of distance running to induce reflux in healthy subjects and the ability of ranitidine to decrease esophageal acid exposure. DESIGN: A randomized, single-blind, crossover study. Objective assessment of reflux was done using an ambulatory intra-esophageal pH monitor during both a baseline hour and 1 hour of running on 2 days of testing. SUBJECTS: Fourteen normal volunteers (10 men, four women) between 22 and 37 years of age were studied. All volunteers ran regularly, completing an average of 20 miles weekly for at least 6 months. INTERVENTIONS: Ranitidine, 300 mg orally, or an identical placebo was administered after a low-fat breakfast just before the baseline hour of pH recording. SETTING: Esophageal motility and pH probe placement was done in the gastroenterology unit at Bowman Gray Medical Center. Running was done on local jogging trials. MEASUREMENTS AND MAIN RESULTS: There was more gastroesophageal reflux during running than during the baseline hour when reflux was measured at a pH threshold of 3.0, 4.0, or 5.0 (P less than 0.05). Reflux episodes were usually associated with belching. Ranitidine, 300 mg administered orally 1 hour before running, significantly (P less than 0.05) reduced the amount of esophageal acid exposure during running. CONCLUSIONS: Gastroesophageal reflux occurs during running in healthy volunteers. It is usually associated with belching. Acid suppression with ranitidine decreases intraesophageal acid exposure during running (P less than 0.05).

Gastroesophageal reflux induced by exercise in healthy volunteers.

The effects of different types of exercise on gastroesophageal reflux were evaluated during fasting and postprandially in 12 asymptomatic volunteers (7 men and 5 women; mean age, 28 years) using an ambulatory intraesophageal pH monitor. The 1-hour exercise period included stationary bicycling (aerobic exercise with little agitation of the body), running (aerobic exercise with a high degree of agitation of the body), and a weight routine (nonaerobic exercise). Each exercise was performed for 15 minutes with 5 minutes of rest between exercises. The weight routine consisted of five different exercises (sit-ups, bench press, sitting arm press, prone leg curls, and sitting leg press) chosen to compare upper-body vs lower-body exercise and supine vs upright position. Each exercise hour was preceded by a 1-hour baseline period on 2 days (fasting and postprandial). The results indicate that vigorous exercise can induce gastroesophageal reflux in normal subjects. Running induced the most reflux, and aerobic exercises with less bodily agitation (bicycle) produced less reflux and may offer an alternate form of exercise for patients with reflux. The weight routine induced gastroesophageal reflux in some subjects, although no particular exercise was associated with more reflux. Postprandial exercise showed a similar pattern of induced gastroesophageal reflux, although of greater amount.