Trade-off between pulse rate and radiation dose during modified barium swallow examination: what is the reality?

AIM: To evaluate the effect of modification of dose mode and frame rate on patient radiation dose during modified barium swallow (MBS) examinations. MATERIALS AND METHODS: A retrospective review was undertaken of consecutive MBS examinations performed over 6 months in the inpatient setting. Patients were divided into two cohorts: pre-implementation of the MBS Impairment Profile (MBSImP; low rate, normal dose) and post-implementation (high rate, low dose). Prior to implementation, pulse rate and dose testing were performed on multiple phantoms. RESULTS: Four hundred and forty-nine patients were included in the pre-implementation cohort and 378 in the post-implementation cohort. Phantom dose testing demonstrated no significant difference in dose on either phantom between low rate/normal dose and high rate/low dose modes. Prior to MBS standardisation, the mean radiation dose was 5.86 (±4.35) mGy. Following standardisation, the mean radiation dose was 4.72 (±3.77) mGy (p<0.0001). The mean fluoroscopy time for MBS prior to standardisation was 83.8 (±44.4) seconds and the mean fluoroscopy time for MBS after standardisation was 82.3 (±39.8) seconds (p=0.62). The dose rate for MBS prior to standardisation was 4.35 (±2.42) and the dose rate for MBS after standardisation was 3.55 (±2.41) mGy/s (p<0.0001). CONCLUSION: Adjustments made to lower the dose mode and the increase in fluoroscopy frame rate decreased the patient radiation dose and did not increase fluoroscopy time.

Tetrachlorodibenzodioxin: an accidental poisoning episode in horse arenas.

Tetrachlorodibenzodioxin was identified as the apparent cause of an outbreak of poisoning in humans, horses, and other animals. Exposure was related to the spraying of contaminated waste oil on riding arenas for dust control. The contamination resulted from improper disposal of a toxic industrial waste. The pathologic effects and chemical identification of tetrachlorodibenzodioxin are described.

Anti-reflux procedures: complications, radiologic findings, and surgical and gastroenterologic perspectives.

This article provides an overview of the current surgical anti-reflux procedures and their imaging findings, as well as the surgical complications. Accurate and timely clinical assessment requires an engaged radiologist fluoroscopist who understands the perspectives of their interdisciplinary colleagues, including the surgeon and gastroenterologist. The complex pathophysiology calls for an interdisciplinary approach, and the radiologist needs to tailor their evaluation to answer the specific questions posed by their clinical colleagues and by the presenting symptomatology.

Combined cholangiography and cholecystography using sodium iopanoate.

Cholangiography and cholecystography were performed in fasted dogs and human subjects using sodium iopanoate given intraduodenally in doses of 10 and 20 mg/kg. The same studies were performed after intraduodenal administration of fat or after intravenous administration of cholecystokinin (CCK) in dogs and after a fatty meal, to stimulate endogenous release of CCK, in human subjects. In both the animals and human subjects, peak blood iodine concentrations were reached by 30 minutes after iopanoate administration. At a dose of 10 mg/kg, radiographic visualization of both bile ducts and gallbladder was inconsistent. At 20 mg/kg (one-half the clinical dose for standard oral cholecystography,) the common bile duct was visualized within 60 minutes and the gallbladder within 90 minutes. Gallbladder density increased over the next 6 hours. Prior administration of fat or CCK led to earlier and denser gallbladder opacification. The common bile ducts opacified with the use of iopanoate were small in caliber, averaging only 3 mm. This probably reflects the fact that, unlike iodipamide, iopanoate has little or no choleretic effect. Therefore, because it would not increase the volume of bile in the duct, iopanoate would not increase duct size.

Computer facilitation of the resident selection process.

A personal computer software system has been designed and implemented to facilitate the numerous complex tasks involved in the resident selection process. The computer tracks the status of each candidate, monitors each application for incomplete documentation, generates personalized correspondence, computes and maintains a scoring system based on evaluation by each Resident Selection Committee member, and provides various data printouts (eg, list of candidates by medical school; persons granted an interview; and ranking lists). Developed with the intent to share with the academic community, the system improves organization and accuracy, and notably decreases time spent by administrative assistants and staff members in the resident selection process.

In vivo measurement of hepatic iodine concentration using fluorescent excitation analysis.

Hepatic iodine concentration was measured in the live dog by external use of fluorescent excitation analysis. The number of characteristic photons produced by interaction of exciting radiation from an americium-241 source with iodine within the tissue is proportional to the tissue iodine concentrations. A correction is made for absorption of radiation by the abdominal wall and other tissues lying between the volume of liver being assayed and the detector collimator. The technique is applicable to the in vivo measurement of iodine concentrations from 0.5 to 40 mg/g. Accuracy of the technique is approximately +/- 10%, which is within the range of variation in iodine concentration at various sites within the liver. Radiation dose is low, and radiolabeled tracer compounds need not be used.

The case for radioprotective eyewear/facewear. Practical implications and suggestions.

Numerous eyeglass lens materials have been recommended for protection of radiologists' eyes from the cataractogenic effect of radiation during fluoroscopic procedures. For the most part, these lenses coincidentally attenuate x-ray beams because they contain elements of high atomic number that are added to increase refractive index. With a bean hardened to simulate scatter, direct transmission ratios were measured for 32 commercially available lens materials. Scatter to the eye, both through and around the glass lenses and secondary scatter to the eye from the radiologist's head, was determined with lenses mounted on a head phantom and a 1-cm3 ion chamber in the position of the eye. Transmission ratios for the various lenses ranged from 3% to 98% for an 80 kVp x-ray beam (HVL = 4.5 mm Al). Measurements with the head phantom in place show that secondarily scattered radiation from the fluoroscopist's head contributes significantly to ocular exposure. Optimal radiation protection of the eyes during fluoroscopy depends not only on eyeglasses with leaded glass, but also on shielding of sufficient size and shape to reduce exposure to the surrounding head.

Magnetic resonance imaging of the internal anatomy of the prostate gland.

Previous reports on the value of magnetic resonance imaging of the prostate have been conflicting and frequently pessimistic, in part because of inability to visualize internal prostatic anatomy. Multiple spin-echo sequences were used to determine a sequence that clearly delineated the internal prostatic anatomy in normal volunteers. A thin section, T2-weighted, spin-echo technique displayed the internal prostatic anatomy in great detail, including the central and peripheral zones, the prostatic urethra, and the periprostatic venous plexus. Accurate depiction of the zonal anatomy of the prostate is important in characterizing focal prostatic disease because the vast majority of carcinomas begin within the peripheral zone, whereas benign hypertrophy originates centrally.

Gastric bypass: analysis of weight loss and factors determining success.

Sixty-nine carefully selected patients underwent extensive behavioral modification training and a standard loop gastric bypass procedure. Patients were followed up at frequent intervals postoperatively to ensure their compliance with dietary requirements: (1) three small, solid meals a day, (2) slowly eaten meals with 5 minutes between bites, (3) no liquids with meals, and (4) cessation of eating immediately after hunger ceased. Analysis of weight loss data at a mean of 20 months postoperatively revealed that 90% of patients lost more than 50% of their excess weight, but that weight loss was inversely related to weight at operation (P less than 0.02) and to estimated pouch size (by upper gastrointestinal series) late postoperatively (P less than 0.01). Patients who failed to maintain regular follow-up visits postoperatively lost significantly less weight (P less than 0.01) than those who were seen regularly. Although fewer than half of the patients lost weight beyond the twelfth postoperative month, significant weight loss was seen in about one fourth of the patients as late as 2 years postoperatively when office follow-up was frequent and compliance with dietary measures complete. Abdominal pain and emesis occurred only when the patient failed to comply with the postoperative dietary regimen. Similarly, inadequate weight loss (premature plateau) was also associated with failure of patients to eat slowly and to stop eating when hunger ceased.

Radiologic diagnosis of disordered esophageal motility: a unified physiologic approach.

Fluoroscopy and cineradiography of the esophagus with swallowed contrast media are indispensable in the study of normal and abnormal contractions of the esophagus, and when performed by experienced radiologists they are believed to be superior and easier on patients than motility studies with pressure recordings.

A breast cancer clone selected by tamoxifen has increased growth rate and reduced sensitivity to doxorubicin.

The in vivo growth rate and the chemosensitivity patterns of a cell clone selected by tamoxifen from the estrogen receptor-negative human breast cancer cell line MDA-MB-231 was studied in the nude mouse model and with flow cytometry. To investigate the growth rate of the wild-type and clone cells in vivo, the cells were inoculated into the opposite flanks of 5 male nude mice. Drug sensitivity to doxorubicin (10 ng/mL), vinblastine (1 ng/mL), and paclitaxel (1 ng/mL) was examined in wild-type/clone cell mixture using flow cytometry. Northern blot technique was used to study the expression of mdr-1 messenger RNA in both the wild-type and the clone cells. The tumors derived from the clone and wild-type cells were, following a 3-week growth period, 260.2 +/- 78.8 mm2 vs. 68.3 +/- 50.8 mm2 in size, respectively (P < 0.001). Following a 28-day continuous exposure, doxorubicin was selectively, toxic to the wild-type cells, while having no apparent effect on the clone population. However, paclitaxel- and vinblastine-treated wild-type/clone cell mixtures did not exhibit a differential cytotoxic effect on either cell population. It was concluded that the clone selected by tamoxifen shows an aggressive growth rate in vivo and an altered chemosensitivity pattern to doxorubicin in vitro.

Assessment of patients with failed gastric operations for morbid obesity.

The success of gastric restriction procedures for morbid obesity depends on a persistently small gastric pouch and stoma, an intact staple line, and, of equal importance, dietary compliance. Evaluation of patients with either excessive or inadequate weight loss should be directed at determining both the technical adequacy of the operation and the depth of understanding the patient has of his or her role in the success of the procedure. Because of the poor prognosis for weight loss, patients who are not likely to be complaint or who demonstrate a lack of understanding of the behavioral modification required to ensure the success of the procedure should not have reoperation, even if a large pouch or stoma or a disrupted staple line is seen on an upper gastrointestinal series.

Cholecystosonography: accuracy, pitfalls and unusual findings.

Gray scale cholecystosonograms in 200 patients were reviewed. The findings in 133 of the patients were proved correct at surgery or autopsy. The overall accuracy for the detection of gallstones was 92 percent, with a false-negative rate of 4 percent. A false-positive diagnosis of cholelithiasis was made in three patients, two of whom proved to have extensive cholesterolosis. Causes of false-negative studies were the presence of a single small calculus, obseity and a large distended gallbladder. Ultrasound was specific but insensitive in the detection of a thickened gallbladder wall. The significance of a nonvisualized gallbladder by ultrasound and the role of ultrasound in the diagnosis of gallbladder disease are discussed.

Hysterosalpingography with videofluoroscopy: effect on radiologic practice in an academic medical center.

RATIONALE AND OBJECTIVES: The authors attempted to determine whether videotaping the fluoroscopic portion of hysterosalpingography would result in changed diagnoses or an increase in diagnostic confidence. MATERIALS AND METHODS: Ninety-nine consecutive outpatients underwent routine hysterosalpingography. The fluoroscopic portion of the examination was captured on videotape. Two consecutive interpretations of each hysterosalpingogram were made by attending radiologists. First, spot radiographs were interpreted alone. Second, these images were viewed along with videofluoroscopy. Concordance of and confidence in findings for the two interpretations were assessed with the two-tailed Fisher exact test. RESULTS: Interpretations of spot radiographs alone and with videofluoroscopy were in agreement in 92 of 99 uterine examinations and 164 of 198 tubal examinations. For uterine examinations classified as normal, interpretations of spot radiographs and videofluoroscopy were in agreement in 56 of 57 cases; there was no change in confidence with review of videofluoroscopic images. For uterine examinations interpreted as abnormal, agreement was noted in 36 of 42 cases (P = .04), and confidence increased with videofluoroscopy in 10 of 42 cases (P = .00001). With normal tubal findings, interpretations agreed in 94 of 118 cases, and confidence increased in 56 of 118 cases (P = .002). With abnormal tubal findings, interpretations agreed in 70 of 80 cases, and confidence increased in 20 of 80 cases (P = .002). When findings with and without videofluoroscopy were discordant, confidence was always higher after review of video-fluoroscopic images. CONCLUSION: Review of videofluoroscopic images obtained during hysterosalpingography increases the accuracy and confidence of diagnoses compared with review of spot radiographs alone.

Radiographic abnormalities after gastric bypass.

Postoperative radiographic findings in the gastrointestinal tract were analyzed in 43 of 72 patients with gastric bypass for morbid obesity. In 15 patients studied because of early postoperative vomiting or abdominal pain, two showed leak from the proximal gastric pouch and six showed impairment of proximal pouch emptying at the anastomosis or proximal efferent loop. In four of the six, the impaired emptying was due to transient postoperative edema and improved spontaneously. Three patients had impairment of distal gastric pouch emptying due to pylorospasm. Five patients studied in the late postoperative period showed dehiscence of the gastric staple line, which can be difficult to demonstrate radiographically. Familiarity with the normal and the abnormal radiographic appearance after gastric bypass is important in elucidating the nature of the problems that can arise after this operation.

Thrombophlebitis of the internal jugular vein: noninvasive imaging.

Internal jugular thrombophlebitis usually results from contiguous infection or central catheterization. Ultrasonography and CT allow rapid, noninvasive methods of confirming the diagnosis of this condition. Although the choice of modality has not been systematically examined, where local expertise exists for both, ultrasonography is less expensive and should provide adequate images.

Early radiographic manifestations of carcinoma of the esophagus.

The survival of patients with esophageal carcinoma is greatest if treatment is begun when the tumor is small and confined to the esophagus. To better define the early radiographic manifestations of this disease, we analyzed the clinical and pathological information and the radiographs from 9 patients with esophageal carcinomas 3.5 cm or less in diameter. All tumors involved one wall of the esophagus and most appeared as plaques or flat sessile polyps, occasionally with central ulceration. Air-contrast views of the distended esophagus demonstrated the tumors to best advantage and should facilitate early detection.