Biomedical subjects

S S Burton

Publications and source records attributed to S S Burton.

11 recordsLinked to original sources

PubMed1997

High-density oral barium sulfate in abdominal MRI: efficacy and tolerance in a clinical setting.

Bowel and anatomic delineation were evaluated on abdominal magnetic resonance imaging scans in patients who received high-density barium sulfate orally (n = 16, BA+ group) or underwent magnetic resonance imaging without oral contrast (n = 14, BA- group). On T1-weighted images, the BA+ group had better delineation of gastric fundus, duodenum, jejunum, and ileum (p < .005) and pancreatic head (p < .02) than did the BA- group. On T2-weighted images, gastric fundus (p < .005), jejunum (p < .02), and ileum (p < .02) were better delineated in the BA+ group than in the BA- group. Analysis of patients' prior CT scans, used to control for selection bias, showed no differences in anatomic or bowel delineation between BA+ and BA- groups that would account for the differences seen in magnetic resonance imaging. One-fourth of patients could tolerate only 150 cc of contrast. High-density oral barium sulfate is recommended in patients undergoing magnetic resonance imaging for pancreatic or gastrointestinal tract disease, although patient intolerance may limit its widespread use in abdominal magnetic resonance imaging.

Abdomen↗

PubMed1997

Low density barium and bentonite mixture versus high density barium: a comparative study to optimize negative gastrointestinal contrast agents for MRI.

The purpose of this study was to compare the patient tolerance and efficacy, as magnetic resonance imaging negative oral contrast agents, of a mixture of clay compound bentonite and low density barium sulfate suspension with that of higher density barium sulfate. Twenty patients were randomized into two groups: 10 patients receiving a mixture of low concentration 60% w/v barium sulfate plus 2.5% w/v bentonite, and 10 patients receiving 220% w/v barium sulfate Liuqid-HD (E-Z-EM, Westbury, NY). Post-contrast Spin-echo (SE) T1- and T2-weighted images (WI) were obtained on a 1.0T magnet. Two independent readers scored the overall intraluminal signal intensity and delineation of the gastrointestinal tract and adjacent organs. Patient acceptance was evaluated via a short questionnaire, by recording spontaneous comments and documenting the quantity of contrast agent ingested. There was greater intraluminal bowel signal reduction and organ delineation with 220% w/v barium than with the barium-bentonite mixture on both SE T1WI (p = 0.03) and SE T2WI (p = 0.42). With both agents there was greater signal reduction on SE T2WI than SE T1WI. Higher scores for organ delineation for both contrast agents were seen with SE T1WI. With 220% w/v barium, there was significantly better delineation of the pancreatic body (p = 0.02) and pancreatic tail (p = 0.02) on T1WI compared with SE T2WI. With the barium-bentonite mixture, SE T1WI showed improved delineation of jejunum compared with SE T2WI (p = 0.03). There were no statistically significant differences between the volume of contrast ingested in the two groups. Abdominal cramps were recorded for one patient in each group. These results suggest that barium-bentonite mixture, although useful as a negative gastro-intestinal contrast agent, is not as effective as 220% w/v barium. Further studies with a larger patient population and concentration optimization studies are needed.

Abdomen↗

PubMed1995

Diagnosis of renal artery stenosis: feasibility of combining MR angiography, MR renography, and gadopentetate-based measurements of glomerular filtration rate.

OBJECTIVE: Our aim was to evaluate the feasibility of combining in a single test (1) structural evaluation of renal arteries with MR angiography, (2) functional evaluation of global glomerular filtration rates calculated on the basis of plasma disappearance of gadopentetate dimeglumine, and (3) renographic analysis of individual kidneys based on the dynamic changes in signal intensity that occur after administration of gadopentetate dimeglumine. SUBJECTS AND METHODS: We used unenhanced MR angiography to measure patency of the renal arteries in 10 healthy volunteers and in 10 patients with renal artery stenosis. Calculations of global glomerular filtration rate were based on measurements of plasma disappearance of gadopentetate dimeglumine as shown by MR relaxometry. For renography with gadopentetate dimeglumine, we generated curves that showed changes in signal intensity in both kidneys over time; intrarenal kinetics were studied by measuring the time of arrival of gadopentetate dimeglumine in the cortex and outer medulla of the kidney. Conventional angiograms, measurements of global glomerular filtration rate based on plasma disappearance of 99mTc-DTPA, and 99mTc-DTPA renograms were used as reference standards. We compared the two different methods of determining global glomerular filtration rates by computing the correlation coefficient of the linear regression of rates derived from studies with gadopentetate dimeglumine versus rates derived from studies with 99mTc-DTPA. RESULTS: In all volunteers, renal arteries were well visualized, and global glomerular filtration rates based on plasma clearance of gadopentetate dimeglumine were normal. In nine of 10 patients, correlation was good between findings on MR angiograms and findings on conventional arteriograms. Finding were discordant in one patient because the patient moved during the MR angiography. For all six patients studied, correlation was good between measurements of global glomerular filtration rates based on plasma clearance of gadopentetate dimeglumine and those based on clearance of 99mTc-DTPA (r = 98%). CONCLUSION: Our results suggest the potential of magnetic resonance for a comprehensive approach for detection of renal artery stenosis. This novel approach provides structural evaluation of renal arteries with unenhanced MR angiography. MR renography is done and global glomerular filtration rates are determined by using MR relaxometry after injection of contrast material. Corticomedullary transit times can be determined on the basis of the dynamic changes in signal intensity that occur after administration of gadopentetate dimeglumine.

Adult↗

PubMed1994

Bubbles in the belly: imaging of cystic mesenteric or omental masses.

The purpose of this article is to familiarize radiologists with the spectrum of "bubbles in the belly," including the current histologic classification of mesenteric or omental cysts. Although mesenteric and omental cystic masses are uncommon lesions, radiologists should be familiar with them as well as with other anomalies that can manifest as these cysts. The first step in diagnosing a cystic abdominal mass is to determine the organ from which the mass originates. The most common type of mesenteric or omental cyst is lymphangioma, but other types encountered include the enteric duplication cyst, the enteric cyst, the mesothelial cyst, and the nonpancreatic pseudocyst. Other cystic lesions that may be located in the mesentery or omentum include cystic mesothelioma, cystic spindle cell tumor, and cystic teratoma. Because of the overlap in imaging features of mesenteric or omental cysts and other cystic masses, histologic analysis is usually necessary to establish a diagnosis. The major role of the radiologist is to document the cystic nature of these abdominal masses and their mesenteric or omental origin.

Cysts↗

PubMed1992

Cystic masses of the pancreas.

Although the pseudocyst is the most common cystic mass of the pancreas found at imaging studies, radiologists should be aware of the multiple disease processes that can manifest in a similar manner. This article reviews these other entities by category of the origin of the mass, including congenital, inflammatory, and neoplastic. Computed tomography, ultrasound, and magnetic resonance imaging studies are presented, and, although the considerable overlap of imaging features makes it generally impossible to render a specific diagnosis, combining the findings from these modalities is helpful in formulating a differential diagnosis. Because a cystic mass of the pancreas is not always a pseudocyst, percutaneous drainage should be followed by cytologic analysis of the aspirate. A biopsy of the wall of the cystic mass may also be necessary.

Abscess↗

PubMed1991

Preliminary results of MR imaging with superparamagnetic iron oxide in pancreatic and retroperitoneal disorders.

The authors conducted a preliminary evaluation of the potential of superparamagnetic iron oxide as contrast material for delineation of the bowel. Ten patients with various pancreatic diseases and 18 patients with suspected retroperitoneal disease underwent T1- and T2-weighted MR imaging before and after contrast material was administered. Two radiologists reviewed randomized images and scored them for depiction of anatomic structures and abnormalities. In most patients, postcontrast T1-weighted images showed improved delineation of the retroperitoneal small bowel (duodenum), stomach, and pancreas. Postcontrast T2-weighted images showed improved delineation of retroperitoneal small bowel, para-aortic region, peripancreatic fat, and renal veins. There was no improvement in delineation of retroperitoneal diseases, except for lymphadenopathy, which was better seen on both T1- and T2-weighted postcontrast images. Preliminary results suggest that superparamagnetic iron oxide is a useful contrast agent for delineating some normal retroperitoneal structures, lymphadenopathy, and pancreatic disease and that it is less useful in evaluating other retroperitoneal masses.

Adipose Tissue↗

PubMed1991

The value of barium as a gastrointestinal contrast agent in MR imaging: a comparison study in normal volunteers.

Preliminary data suggest that barium sulfate suspension is a potentially useful negative gastrointestinal contrast agent for MR imaging. To evaluate this hypothesis in a controlled fashion, abdominal and pelvic MR studies of 10 normal volunteers were performed before and after both oral (600-900 ml) and rectal (400 ml) administration of barium. Standard spin-echo coronal T1-, axial T1-, proton density-, and T2-weighted images were obtained at 1.5 T. Images obtained were randomized and interpreted by three observers, who evaluated bowel visualization and delineation of normal anatomy. Bowel segments evaluated were stomach, duodenum, proximal small bowel, proximal colon, distal colon, and rectum. Anatomic structures examined were pancreatic head, pancreatic body, pancreatic tail, retroperitoneum, spleen, liver, pelvic side walls, uterus, vagina, bladder, prostate, and seminal vesicles. Data concerning barium tolerance and safety were recorded. Descriptive, percent change, and kappa statistics were analyzed. Pairwise agreement techniques and repeated measures analysis of variance were performed. This statistical assessment showed a significant improvement in both bowel visualization (59-123% improvement, depending on the segment) and delineation of normal anatomy (23-68% improvement, depending on the structure) after barium administration, particularly on T1-weighted images. In addition, barium was a well-tolerated and safe contrast agent that did not produce artifacts. Our results show that barium sulfate is a useful negative gastrointestinal contrast agent for MR because it improves bowel visualization and delineation of abdominal anatomy, particularly on T1-weighted sequences.

Abdomen↗

PubMed1980

A sensitive radioimmunoassay for vincristine and vinblastine.

A rapid, sensitive and highly reproducible radioimmunoassay (RIA) has been devised for vincristine and vinblastine. These alkaloids bind to the antiserum very tightly with an association constant (Ka) of 5 x 10(9) M-1 as determined by Scatchard analysis. The kinetic association constant of the alkaloids, as determined by the 'on' and 'off' rates at 4 degrees C, is 30-fold higher than the Scatchard analysis value. At 4 degrees C, 80% of the alkaloid is bound to the antiserum within 20 min, and the remaining 20% reaches an equilibrium within 48-72 h. In the RIA procedure the amount of the alkaloid (1-2 ng) needed to compete for 50% binding remains unchanged when the reaction mixtures are incubated for 2, 4, or 20 h. By a modification of the RIA procedure, where the antiserum is first allowed to react with the unlabeled alkaloid followed by addition of the radiolabeled alkaloid, sensitivity of the assay has been increased five- to tenfold. Other drugs, such as adriamycin, CCNU, methyl CCNU, cyclophosphamide, 5-fluorouracil, heparin, hydrocortisone, prednisone, and nitrogen mustard do not interfere with the assay. This assay can thus be used to determine vincristine or vinblastine levels in 5 x 10(-10)--10(-9) M concentrations in biological fluids.

Antibodies↗

PubMedDate not supplied

Rectal barium in pelvic MR imaging: initial results.

Pelvic magnetic resonance (MR) imaging is limited by lack of an effective bowel contrast agent. This study was performed to evaluate the efficacy of rectally administered barium sulfate as a contrast agent in pelvic MR imaging. Thirty-two patients were studied retrospectively to evaluate anatomic definition of the rectosigmoid colon. A commercially available barium sulfate suspension was administered rectally in 19 patients. Thirteen patients were imaged without barium. In the latter patients, anatomic definition of the rectum and sigmoid colon was poor to fair with all pulse sequences. Delineation of the rectum and sigmoid colon improved in patients who received rectal barium, owing to distention and marking of the bowel by the predominantly low-signal-intensity barium. Barium is a safe, inexpensive negative contrast agent for bowel that may improve pelvic MR imaging.

Adolescent↗

PubMedDate not supplied

MR imaging of colonic lipoma.

Colonic lipomas may present with symptoms similar to colonic malignancies but require a much less aggressive surgical approach to control the symptoms and provide a cure. This case illustrates the efficacy and advantages of MR, using a barium sulfate enema in noninvasive, preoperative diagnosis of a colonic lipoma, thus facilitating appropriate management of the patient.

Barium Sulfate↗

PubMedDate not supplied

Improved technique for pancreatic MRI: value of oblique fat suppression imaging with oral barium administration.

PURPOSE: Our goal was to determine the efficacy of a dedicated protocol for pancreatic MRI using fat suppression, oblique plane orientation, and barium as an oral contrast agent. METHOD: Fifty-two patients were enrolled in our study. In each patient, the stomach and duodenum were opacified with 300 ml oral barium. In all patients conventional SE T1- and T2-weighted images and fat-suppressed axial and oblique T1-weighted images of the upper abdomen and the pancreas, respectively, were obtained. The different T1-weighted sequences were compared for visualization of the pancreas and for lesion conspicuity. Oblique images were obtained in a plane parallel to the overall axis of the pancreas. All sequences were qualitatively assessed by two independent blinded readers and statistically compared. RESULTS: The combination of fat suppression and oblique imaging significantly improved the visualization of the different anatomic portions of the normal pancreas as well as pathologic findings in the pancreas in 70-92% of the cases compared with conventional axial T1-weighted imaging (p < 0.001) and in 52-75% of the cases compared with axial fat-suppressed T1-weighted imaging (p < 0.001), respectively. Increased image noise and blurring artifacts resulted in slight image degradation after Gd-DTPA administration. Barium as a duodenal contrast agent was beneficial for delineation of the pancreatic head from the adjacent bowel structures. CONCLUSION: In pancreatic imaging, fat-suppressed T1-weighted imaging is superior to conventional T1-weighted imaging, and oblique imaging is superior to axial imaging. Intravenous Gd-DTPA administration was useful only in selected cases.

Adipose Tissue↗