Gladys M. Torres

Superparamagnetic iron oxide (SPIO) as an oral contrast agent in gastrointestinal (GI) magnetic resonance imaging (MRI): Comparison with state-of-the-art computed tomography (CT)

This study was conducted to compare the sensitivity and specificity of abdominal magnetic resonance imaging using oral superparamagnetic iron oxide with oral contrast-enhanced computed tomography in the detection of GI pathology. Overall sensitivity was calculated to be 83% for OECT compared to 67% by SPIO MRI. Specificity for OECT was 68% compared to 89% for SPIO MRI. The results from imaging with superparamagnetic iron oxide and imaging with oral contrast-enhanced computed tomography were in agreement in 14 subjects who had normal gastrointestinal tracts. In the remaining 16 patients, eight pathologic entities were detected by both modalities whereas 15 abnormalities were seen by only one modality. Superparamagnetic iron oxide magnetic resonance imaging was helpful in discriminating normal bowel from solid lesions and in detecting subtle gastrointestinal tract mass effect. In 30 consecutively studied patients suspected of having GI pathology, OECT was more sensitive than SPIO MRI in detecting abdominal pathology. Conversely, SPIO MRI was more specific than OECT.

Correlation of lymphangiography, computed tomography, and laparotomy in the staging of Hodgkin's disease

PURPOSE To determine the predictive value of lymphangiography and computed tomography of the abdomen and pelvis for infradiaphragmatic involvement of Hodgkins disease. METHODS AND METHODS We retrospectively reviewed the findings on 125 patients with Hodgkins disease treated at the University of Florida who underwent lymphangiography and staging laparotomy; 33 patients also underwent computed tomography of the abdomen and pelvis. The positive predictive value and negative predictive value were calculated for both studies. RESULTS The positive predictive value of lymphangiography for paraaortic or pelvic disease was 35%, while the negative predictive value was 95%. The positive predictive value of computed tomography of the abdomen and pelvis for paraaortic or pelvic disease was 20%; the negative predictive value was 93%. There was no advantage in predicting paraaortic or pelvic disease when both studies were obtained as compared to either study alone. For splenic disease, the positive predictive value of computed tomography was 43%; the negative predictive value was 77%. Of the patients with a positive lymphangiography, 57% were found at laparotomy to have either no abdominal disease or upper abdominal disease only, with or without minimal splenic disease, making them reasonable candidates for radiotherapy alone. Of the patients with a negative lymphangiogram, 14% were found at laparotomy to have either lower abdominal disease or extensive splenic disease, and so were not good candidates for radiotherapy alone. CONCLUSION We recommend laparotomy for patients who may be candidates for radiotherapy alone or combined modality therapy with limited chemotherapy.

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.

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.

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.

Magnetic resonance imaging evaluation of a case of von Hippel-Lindau disease

Abstract We present a case of von Hippel-Lindau disease with special reference to the findings in MR imaging of visceral abdominal manifestations.

CT of abdominal barium intravasation.

We report a case of barium intravasation due to misplacement of the catheter tip during a barium enema examination, leading to vaginal laceration and barium sequestration within the reticuloendothelial system of a 57-year-old woman who survived this potentially fatal event. The radiologic appearance on CT, sonography, MR, and plain radiography is presented. Computed tomography demonstrated barium sequestered by the liver, spleen, and renal cortex. The portal veins were seen as branching radiolucent densities superimposed on a dense parenchymal background.

Dose optimization of nonionic contrast agent in dynamic computed tomography scanning of the abdomen and pelvis

A prospective, randomized study was performed to examine the image quality of varying reduced doses of an intravenous (IV) nonionic contrast agent (ioversol, 320 mg/ml organically bound iodine) compared with the quality obtained using the maximum permissible dose (150 ml) of the same agent. Forty-five patients referred for abdominal-pelvic computed tomography (CT) scan were randomized into five groups to receive contrast doses equivalent to 100, 75, 65, 50, or 30% of 150 ml of contrast agent. The images were scored for diagnostic image quality in eight anatomical regions of interest and, in addition, quantitative analysis of density measurements were performed in the abdominal aorta and inferior vena cava. There was no statistically significant difference in either image quality, in any anatomical region, or in vascular density measurements between the group receiving 100% and the group receiving 75% of 150 ml of nonionic contrast agent. Patients receiving 65% and lower doses demonstrated a statistically significant decrease in enhancement, although all scans were diagnostically adequate. This study demonstrates that dynamic abdominal and pelvic CT scans obtained using a reduced dose of nonionic IV contrast agent are equivalent in diagnostic image quality compared with those scans obtained with the higher permissible dose of the same agent.