Extrahepatic abdominal imaging in patients with malignancy: comparison of MR imaging and helical CT, with subsequent surgical correlation.

PURPOSE: To compare state-of-the-art magnetic resonance (MR) imaging with single-phase helical computed tomography (CT) in abdominal screening for extrahepatic disease in patients with proved malignancy. MATERIALS AND METHODS: Fifty-seven patients with known malignancy underwent abdominal contrast material-enhanced helical CT and MR imaging from 1994 through 1997. Prospective interpretations of CT scans and MR images were used to assess each modality's sensitivity in depicting malignant extrahepatic tumor at 17 anatomic sites. Imaging findings were compared with surgical results in all patients. RESULTS: Helical CT depicted 101 (66%) of 154 surgically confirmed extrahepatic tumor sites; MR imaging depicted 139 (90%) (P < .001). MR imaging depicted tumor in more patients at 11 of the 17 anatomic sites; at six sites, MR imaging and helical CT were equivalent. MR imaging showed significantly greater depiction of extrahepatic tumor for the peritoneum (P < .05), bowel (P < .01), and mesentery (P < .05). False-negative interpretations would have altered patient care had the extrahepatic tumor remained undetected in 13 patients for helical CT and in six patients for MR imaging. CONCLUSION: State-of-the-art MR imaging can be used for effective abdominal screening for extrahepatic tumor in patients with malignancy. Compared with single-phase helical CT, MR imaging depicted more sites of extrahepatic tumor and was particularly advantageous for the peritoneum, mesentery, and bowel.

Peritoneal tumor: MR imaging with dilute oral barium and intravenous gadolinium-containing contrast agents compared with unenhanced MR imaging and CT.

PURPOSE: To compare fat-suppressed, gadolinium-enhanced, breath-hold magnetic resonance (MR) imaging after administration of dilute oral barium solution with unenhanced MR imaging and computed tomography (CT) in the detection of peritoneal tumors. MATERIALS AND METHODS: In 24 patients in whom peritoneal tumor was known or suspected, double-contrast MR imaging and CT were performed prospectively. MR imaging included T1-weighted, fast spin-echo T2-weighted, and immediate and delayed gadolinium-enhanced, breath-hold, fast multiplanar sequences with fat saturation. Helical and conventional dynamic CT were performed with intravenously and orally administered contrast media. MR images and CT scans were reviewed independently and prospectively by different pairs of radiologists for presence of peritoneal tumor in 17 anatomic sites. Imaging findings were compared with surgical and histopathologic results. RESULTS: Of the 24 patients, 18 had peritoneal tumor confirmed at surgery. Detection of tumor sites was superior with double-contrast MR images (mean sensitivity, specificity, and accuracy, 84%, 87%, and 86%, respectively) compared with CT scans (mean sensitivity, specificity, and accuracy, 54%, 91%, and 74%, respectively). Double-contrast MR imaging enabled better detection of carcinomatosis and tumors less than 1 cm in diameter (75%-80%) than CT (22%-33%; P < .0001). CONCLUSION: Double-contrast MR imaging demonstrated more peritoneal tumors than CT or unenhanced spin-echo MR imaging.

Dynamic contrast-enhanced breath-hold MR imaging of thoracic malignancy using cardiac compensation.

The purpose of this paper was to evaluate the use of dynamic gadopentetate dimeglumine-enhanced, breath-hold spoiled gradient-recalled (SPGR) MR imaging with cardiac compensation (CMON) compared to spin-echo MR imaging in patients with thoracic malignancy. We retrospectively reviewed MR images from 29 patients with thoracic tumors. MR imaging included axial electrocardiogram (ECG)-gated T1-weighted, fast spin echo (FSE) T2-weighted, and contrast-enhanced breath-hold fast multiplanar SPGR imaging with CMON, which selects the phase-encoding gradient based on the phase within the cardiac cycle. Images were reviewed for lung masses, mediastinal or hilar tumor, disease of the pleura, chest wall, and bones and vascular compression or occlusion. Contrast-enhanced fast multiplanar SPGR imaging with CMON produces images of the chest that are free of respiratory artifact and have diminished vascular pulsation artifact. ECG-gated T1-weighted images were preferred for depicting mediastinal and hilar tumor. The gadopentetate dimeglumine-enhanced fast multiplanar SPGR images were useful for depicting chest wall tumor, vascular compression or thrombosis, osseous metastases, and in distinguishing a central tumor mass from peripheral lung consolidation. Pleural tumor was depicted best on the FSE T2-weighted images and the contrast-enhanced SPGR images. As an adjunct to spin echo T1-weighted and T2-weighted imaging, contrast-enhanced fast multiplanar SPGR imaging with CMON is useful in the evaluation of thoracic malignancy.

Ovarian cancer: comparison of findings with perfluorocarbon-enhanced MR imaging, In-111-CYT-103 immunoscintigraphy, and CT.

PURPOSE: To determine the accuracy of breath-hold gadolinium- and perflubron-enhanced magnetic resonance (MR) imaging, immunoscintigraphy with indium-111-CYT-103 (planar and single photon emission computed tomography [CT]), and contrast material-enhanced CT for the detection of ovarian cancer prior to laparotomy. MATERIALS AND METHODS: Sixteen patients with primary (n = 3) or treated (n = 13) ovarian cancer underwent imaging of the abdomen and pelvis with each modality. All images were reviewed prospectively for tumor location, and results were compared with findings at surgery. RESULTS: With CT or MR imaging, tumor was detected in 11 of 13 (85%) patients compared with 11 of 12 patients (92%) with immunoscintigraphy. Per patient accuracy for CT was 81% compared with 75% for MR imaging and 86% for immunoscintigraphy. For detection of individual sites of tumor, the sensitivity of MR imaging was highest (81%) compared with CT (51%, P < .001) and immunoscintigraphy (50%, P < .01). The combination of MR imaging and immunoscintigraphy depicted 89% of sites of tumor involvement confirmed at laparotomy. CONCLUSION: MR imaging and immunoscintigraphy show promise for the evaluation of patients with ovarian cancer.

MR imaging of peritoneal disease: comparison of contrast-enhanced fast multiplanar spoiled gradient-recalled and spin-echo imaging.

OBJECTIVE: We performed this study to compare contrast-enhanced fast multiplanar spoiled gradient-recalled (SPGR) MR imaging with unenhanced spin-echo imaging for the detection of benign and malignant peritoneal abnormalities. MATERIALS AND METHODS: We retrospectively reviewed abdominal MR images of 34 patients with proved peritoneal abnormalities, including 21 patients with malignant and 13 patients with benign peritoneal disease. Six additional patients had false-positive interpretations of their MR examinations because of diaphragmatic thickening and enhancement. Unenhanced T1-weighted images, fast spin-echo T2-weighted images, and breath-hold fast multiplanar SPGR images obtained immediately and 10-15 min after IV injection of gadopentetate dimeglumine were available. Images were reviewed for evidence of peritoneal disease by two observers who had no knowledge of the clinical findings. The four types of images were separately evaluated for peritoneal thickening, masses, and abnormal enhancement. The anatomic location, thickness, and pattern of thickening of the peritoneum were noted. Results were correlated with surgical findings or results of percutaneous biopsy. RESULTS: Immediate and delayed contrast-enhanced fast multiplanar SPGR images showed malignant peritoneal tumor in all 21 cases, compared with T1-weighted images, which showed tumor in 11 cases (p < .01), and fast spin-echo T2-weighted images, which showed tumor in 13 cases (p < .01). Enhancement of the peritoneal tumor increased the tumor's conspicuity, particularly on delayed fast multiplanar SPGR images, which were selected as the best sequence for detection of peritoneal tumor in 18 of the 21 cases. The MR findings varied widely from moderately and regularly thickened, enhancing peritoneum to very thick (> 1 cm) and lobular or masslike peritoneal thickening with enhancement. Delayed fast multiplanar SPGR images showed evidence of benign peritoneal disease in all 13 cases compared with immediate fast multiplanar SPGR images, which showed disease in 12 cases (p > .05); T1-weighted images, which showed disease in four cases (p < .05); and fast spin-echo T2-weighted images, which showed disease in only one case (p < .01). In the benign forms of peritoneal disease, the peritoneum was often regular in contour and tended to be thinner than in the cases of malignant peritoneal tumor, in which the peritoneum was generally thicker and more lobular or masslike. However, significant overlap was seen between the MR findings in benign and malignant forms of peritoneal disease. CONCLUSION: Detection of peritoneal abnormalities with MR imaging can be improved by using contrast-enhanced fast multiplanar SPGR imaging. The findings of peritoneal thickening and enhancement are best depicted on delayed images.

Evaluation of malignant biliary obstruction: efficacy of fast multiplanar spoiled gradient-recalled MR imaging vs spin-echo MR imaging, CT, and cholangiography.

OBJECTIVE: Although CT and cholangiography have proven value in the detection of biliary obstruction, determining the extent of biliary tumors and imaging small pancreatic or ampullar tumors remain problematic. We hypothesized that the superior contrast resolution of MR, coupled with contrast-enhanced breath-hold imaging, might increase the sensitivity for tumor detection and improve the depiction of the point of obstruction in patients with malignant biliary disease. SUBJECTS AND METHODS: Twenty-one MRI studies were performed prospectively in patients with malignant biliary obstruction by obtaining breath-hold contrast-enhanced fast multiplanar spoiled gradient-recalled (FMPSPGR) images at 0 and 10 min, conventional spin-echo T1-weighted images, and fast spin-echo T2-weighted images. Findings on MR images were correlated with findings on CT scans (15 cases) and/or cholangiograms (14 cases) by two observers. All MR images, CT scans, and cholangiograms were reviewed to evaluate tumor detection, visualization of dilated bile ducts, and conspicuity of the obstructing tumor. A four-point scale (1 = excellent tumor depiction and conspicuity, 4 = tumor not detected) was used for evaluation. Contrast-to-noise ratios for tumor and bile were calculated for the three MR pulse sequences. RESULTS: The contrast-enhanced FMPSPGR images and CT scans provided excellent depiction of the dilated biliary tree in 95% and 93% of examinations, respectively, with both techniques superior to fast spin-echo and T1-weighted images (p < .005). Tumor detection was best with the immediate FMPSPGR MR images (20/21), compared with fast spin-echo MR images (16/21) (p = .04), T1-weighted MR images (16/21) (p = .04), CT scans (12/15) (p > .05), and cholangiograms (13/14) (p > .05). Of 13 examinations showing proximal biliary obstruction, the mean score for tumor conspicuity was best with the immediate enhanced FMPSPGR MR images (1.38 +/- .65), compared with T1-weighted MR images (2.38 +/- 1.3) and fast spin-echo MR images (2.08 +/- 1.0) (p < .05), but it was not different from the delayed FMPSPGR MR images (1.75 +/- 1.1) or CT scans (1.9 +/- 0.99) (p > .05). For five of six cholangiocarcinomas, the immediate and delayed enhanced FMPSPGR MR images showed excellent tumor conspicuity owing to their enhancement with gadopentetate dimeglumine. Data for contrast-to-noise ratios of tumor showed that the immediate FMPSPGR MR images (15.8 +/- 10.2) were superior to T1-weighted images (6.3 +/- 3.5, p < .01), but were not different from fast spin-echo images (13.5 +/- 6.7) or delayed FMPSGR images (11.5 +/- 8.9). For eight examinations in patients with distal biliary obstruction, the mean score for tumor conspicuity was greater with the immediate FMPSPGR MR images (1.38 +/- 0.52), compared with fast spin-echo images (3.25 +/- 0.71, p < .005), T1-weighted images (2.63 +/- 1.06, p < .05), and delayed FMPSPGR MR images (2.60 +/- 1.5, p < .05), but was similar to that with CT scans (1.40 +/- 0.89, p > .05). Data for contrast-to-noise ratios of tumor showed an advantage for the immediate FMPSPGR MR images (12.0 +/- 7.7) over T1-weighted images (4.0 +/- 2.6, p < .01) and delayed FMPSPGR images (4.3 +/- 2.6, p < .025), but no difference from fast spin echo images (6.6 +/- 8.8, p = .05). CONCLUSION: Contrast-enhanced FMPSPGR MR imaging is sensitive for the detection of tumors causing biliary obstruction. For proximal obstruction, it may be particularly effective for detecting and defining tumor extent of hilar cholangiocarcinomas because of their enhancement with gadopentetate dimeglumine. For cases of distal obstruction, this technique showed improved tumor detection and conspicuity compared with T1- and fast spin-echo T2-weighted images, but showed no advantage over CT.

Abdominal MR imaging: comparison of T2-weighted fast and conventional spin-echo, and contrast-enhanced fast multiplanar spoiled gradient-recalled imaging.

T2-weighted fast and conventional spin-echo (SE) and dynamic gadolinium-enhanced fast multiplanar spoiled gradient-recalled (FMPSPGR) images in 26 patients (18 with hepatic masses and eight with no detected abnormality) were compared to determine the efficacy of the newer pulse sequences (fast SE and FMPSPGR) in abdominal imaging. FMPSPGR allows for breath-hold magnetic resonance imaging of the liver. The contrast-to-noise ratio (C/N) of the hepatic lesions was calculated for each sequence and was superior in fast SE compared with that in conventional SE in 16 of 18 patients. Lesion detection was 90% with fast SE and was 85% and 80% for conventional SE and contrast material-enhanced FMPSPGR sequences, respectively. Of the T2-weighted sequences, fast SE showed consistently sharper anatomic structures and less respiratory and cardiac motion artifact. Thus, fast SE (with its superior C/N and shorter imaging time) and gadolinium-enhanced FMPSPGR images, when combined, demonstrate potential value as routine sequences in abdominal imaging.

Evaluation of ultrafast CT scanning of the adult abdomen.

Various measures of image quality were compared from adult abdomen scans obtained with a subsecond computed tomographic (CT) scanner (Imatron Ultrafast C-100) and a conventional third-generation whole-body scanner (GE9800). Forty images from 13 patients scanned within 2 hours of each other on both scanners were evaluated with techniques standardized as much as possible for CT exposure factors and contrast enhancement. Two observers in consensus evaluated matched anatomic levels using standard window width and level settings. Each image was graded on a scale of 1 (worst) to 5 (best) for spatial resolution, image noise, and presence and type of artifacts. Overall image quality also was graded. Averaged scores were compared between the two scanners. In all categories, scores were slightly higher for the GE9800. However, the differences in spatial resolution, presence of artifacts, overall image quality were not significant using the sign test. There was a significant difference, in favor of the GE9800, in image noise. The types of artifacts differed; the GE9800 produced more motion artifacts from bowel and surgical clips and the Imatron C-100 produced more rib shadow artifacts projecting on the liver and spleen. While the GE9800 produced abdominal images of slightly superior quality in adults, the Imatron Ultrafast C-100 was shown to produce images suitable for routine abdominal imaging in adults.

Mechanism of action of metronidazole on Bacteroides fragilis.

Metronidazole (10 micrograms/ml) was rapidly bactericidal when added to log-phase cultures of Bacteroides fragilis strain 2624. DNA synthesis stopped immediately after addition of metronidazole, whereas synthesis of RNA and protein continued at linear rates for at least 60 min. Gel electrophoresis of DNA extracted from metronidazole-treated cells revealed no nicking or strand breakage in either the 2.9- or 2.0-megadalton plasmid of strain 2624. Also, no degradation of chromosomal DNA was seen. DNA polymerase activity, measured in vitro, was not diminished by prior treatment of the cells with metronidazole. Thus, the primary action of metronidazole is a rapid inhibition of DNA replication. The DNA remains structurally intact, DNA polymerase activity is not directly affected, and cells retain metabolic activity, synthesizing RNA and protein at unaltered rates.