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Comparison of the Timing of Hepatic Arterial Phase and Image Quality Using Test-Bolus and Bolus-Tracking Techniques in Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid-Enhanced Hepatic Dynamic Magnetic Resonance Imaging.
Iyama, Y, Nakaura, T, Yokoyama, K, Kidoh, M, Utsunomiya, D, Oda, S, Namimoto, T, Yamashita, Y
Journal of computer assisted tomography. 2017;(4):638-643
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Abstract
OBJECTIVES The aim of this study was to compare the image quality, the degree of artifacts and the percentage of timing of the optimal hepatic arterial phase (HAP) between test-bolus and bolus-tracking methods on gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI). METHODS In this prospective study, 60 patients who underwent 3-dimensional dynamic Gd-EOB-DTPA-enhanced hepatic 3-T MRI were enrolled in this study. We randomly assigned the 30 patients to the bolus-tracking method, and another 30 patients to the test-bolus method. Signal-to-noise ratios of the liver and spleen in HAP were compared in the 2 groups. Two radiologists independently assessed the ratio of optimal timing of HAP and the degree of ringing and motion artifacts of the 2 protocols. RESULTS The signal-to-noise ratios of the liver (24.0 [SD, 6.4] vs 20.4 [SD, 4.0]) and spleen (30.0 [SD, 13.3] vs 23.6 [SD, 9.9]) were significantly higher in the test-bolus protocol than in the bolus-tracking protocol. The ratio of optimal timing was also significantly higher with the test-bolus protocol than with the bolus-tracking protocol (76.7% vs 40.0%). The degree of ringing and motion artifacts of test-bolus protocol was significantly lower than that of the bolus-tracking protocol (P < 0.01). CONCLUSIONS The test-bolus protocol in dynamic 3-T MRI can yield better qualitative image quality and more optimal timing of HAP images, while reducing the degree of artifacts compared with the bolus-tracking protocol.
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Efficacy of simethicone and N-acetylcysteine as premedication in improving visibility during upper endoscopy.
Chang, WK, Yeh, MK, Hsu, HC, Chen, HW, Hu, MK
Journal of gastroenterology and hepatology. 2014;(4):769-74
Abstract
BACKGROUND Simethicone and N-acetylcysteine have been widely used in improving endoscopic visibility. However, the optimal dose, volume, and dosing time for the premedication regimen are still unclear. AIM: Our aim was to assess the efficacy of premedication in improving endoscopic visibility and determine the contributions of dose, volume, and premedication time. METHODS A total of 1849 patients were prospectively treated in three groups: group A: 100-mg simethicone suspension in 5 mL water; group B: 100-mg simethicone suspension in 100 mL water; and group C: 100-mg simethicone suspension in 100 mL water containing 200 mg N-acetylcysteine. Mucosa visibility was assessed at seven sites of upper gastrointestinal tract. The sum of scores was considered as total mucosal visibility score (TMVS). RESULTS The upper body of stomach had the worst visibility score for all groups. TMVS of groups B and C were significantly lower than those of group A. Group C had a significantly fewer patients requiring endoscopic flushing than groups A and B. The TMVS for groups B and C were significantly lower than for group A within 30 min of beginning premedication. Beyond 30 min of premedication, there was no significant difference in the TMVS among groups. CONCLUSIONS Premedication using 100 mg simethicone in 100 mL of water improves endoscopic visibility. Addition of N-acetylcysteine to simethicone in 100 mL of water reduces the need for endoscopic flushing. For patients unable to tolerate a large fluid volume, a 5-mL simethicone suspension administered more than 30 min prior to upper endoscopy is suggested.
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Clinical investigation on application of water swallowing to MR esophagography.
Zhang, J, Hu, W, Zang, L, Yao, Y, Tang, Y, Qian, Z, Gao, P, Wu, X, Li, S, Xie, Z, et al
European journal of radiology. 2012;(9):1980-5
Abstract
OBJECTIVE To verify the clinical outcomes of applying water swallowing to MR esophagography. METHODS Thirty patients confirmed postoperatively or histopathologically with thoracic esophageal carcinoma by endoscopic biopsy and 10 healthy volunteers with normal esophagus underwent respectively conventional magnetic resonance imaging (MRI) detection and water swallowing MR esophagography. Of those patients, 4 underwent second examination after radiotherapy. Assessment on imaging effects of MR esophagography was performed. Assessment on definition on MR esophagography of the tumor in both upper and lower ends, specific localization, tumor size finally measured, coincidence with the gross pathologic types and tumor staging were respectively performed by comparison with conventional MRI. Additionally, we evaluated the outcomes of radiotherapy by comparing the previous MR esophagography with the second one with interventional technique. RESULTS Of the total 44 images of MR esophagography, 97.7% (43/44) were in high resolution by sagittal view and 81.8% (36/44) by cross-section. 93.3% (56/60) of the MR esophagography were clearly defined with the neoplastic lesion ends in the 30 patients with thoracic esophageal carcinoma, compared with 11.7% (7/60) by conventional MRI. The results were totally different in statistics (P<0.005). Preoperative conventional MRI detection of the 22 cases in 25 undergone radical resection suggested vague diameter of the primary tumor and impossibly identified it at middle-lower thoracic esophagus in 5, and even failed to confirm gross pathologic types in 19 cases. Yet, MR esophagography with water swallowing represented accurate tumor length (graded as excellent) in 88% (22/25), localization in 100% (25/25), exact gross pathologic types in 88% (22/25), and accuracy for tumor staging in 80.8% (21/26) compared to 92.3% (24/26) by conventional MRI. Therapeutic effects achieved in 4 patients with radiotherapy. CONCLUSIONS MR esophagography with water swallowing makes optimal esophagram and is of great value in the preoperative diagnosis of thoracic esophageal cancer and assessment of the radiotherapy effects for patients with such neoplasm, which may serve as an alternative for conventional MRI.
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Biphasic contrast medium injection in cardiac CT: moderate versus high concentration contrast material at identical iodine flux and iodine dose.
Rutten, A, Meijs, MF, de Vos, AM, Seidensticker, PR, Prokop, M
European radiology. 2010;(8):1917-25
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Abstract
OBJECTIVE To prospectively investigate the influence of contrast material concentration on enhancement in cardiac CT by using a biphasic single-injection protocol. METHODS Sixty-four-row multidetector cardiac CT angiography was performed in 159 patients randomised to a moderate or high contrast medium concentration. Contrast material injection included a first phase for enhancement of the coronary arteries and a second phase, at half the iodine flux, targeted at enhancement of the right ventricle. Contrast medium injection was followed by a saline flush. For both concentrations, injection duration (and thus total iodine dose) was adapted to the duration of the CT data acquisition and iodine flux was adjusted to patient weight. Attenuation was measured at various levels in the heart and vessels and the two concentrations compared, overall and per weight group. RESULTS Enhancement of the aorta and left ventricle was significantly greater with the moderate than with the high concentration contrast medium. This remained true for the two higher weight groups. No difference was found in the lowest weight group or in the right ventricle and pulmonary outflow tract. CONCLUSION With a biphasic injection protocol, enhancement of the aorta and left ventricle was weaker with the higher concentration of contrast material.
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Full-laxative versus minimum-laxative fecal-tagging CT colonography using 64-detector row CT: prospective blinded comparison of diagnostic performance, tagging quality, and patient acceptance.
Nagata, K, Okawa, T, Honma, A, Endo, S, Kudo, SE, Yoshida, H
Academic radiology. 2009;(7):780-9
Abstract
RATIONALE AND OBJECTIVES To compare prospectively 64-detector-row computed tomographic colonography (CTC) after a full-laxative tagging-based preparation (full preparation) with a minimum-laxative tagging-based preparation (minimum preparation) with respect to diagnostic performance in the detection of polyps, tagging quality, and patient acceptance. MATERIALS AND METHODS Consecutive 101 patients at high risk for developing colorectal cancer were alternately assigned to either a full preparation group (n = 51) or a minimum preparation group (n = 50) for fecal-tagging CTC. The full preparation consisted of administration of 2-L polyethylene glycol solution with 20 mL of sodium diatrizoate for fecal tagging. The minimum preparation consisted of ingestion of a total of 45 mL of sodium diatrizoate during the 3 days before and 10 mL of sodium picosulfate solution the night before CT. Colonoscopy was used as the reference standard. We assessed the accuracy of polyp detection and the tagging quality for each preparation. All patients were given questionnaires related to their acceptance. RESULTS Per-patient sensitivity, specificity, and positive and negative predictive values for polyps > or = 6 mm were as follows: full preparation group, 97%, 92%, 88%, and 98%, respectively; minimum preparation group, 88%, 68%, 56%, and 92%, respectively. Average visual subjective tagging scores for the full and minimum preparation groups were 94.6% and 76.1%, respectively (P < .0001). Minimum preparation was better tolerated than full preparation. CONCLUSION Although full-laxative and minimum-laxative fecal-tagging CTC yielded an equally high sensitivity in the detection of polyps > or = 6 mm, the full-laxative fecal-tagging CTC yielded a better specificity than did the minimum-laxative fecal-tagging CTC. Thus, it is desirable to offer patients an option of either full-laxative fecal-tagging CTC for highest diagnostic accuracy and ability to perform a same-day therapeutic colonoscopy without additional bowel preparation, or minimum-laxative fecal-tagging CTC for those unwilling to undergo full preparation but willing to accept moderate decrease in specificity.
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Performance of delayed-enhancement magnetic resonance imaging with gadoversetamide contrast for the detection and assessment of myocardial infarction: an international, multicenter, double-blinded, randomized trial.
Kim, RJ, Albert, TS, Wible, JH, Elliott, MD, Allen, JC, Lee, JC, Parker, M, Napoli, A, Judd, RM, ,
Circulation. 2008;(5):629-37
Abstract
BACKGROUND The identification and assessment of myocardial infarction (MI) are important for therapeutic and prognostic purposes, yet current recommended diagnostic strategies have significant limitations. We prospectively tested the performance of delayed-enhancement magnetic resonance imaging (MRI) with gadolinium-based contrast for the detection of MI in an international, multicenter trial. METHODS AND RESULTS Patients with their first MI were enrolled in an acute (< or = 16 days after MI; n=282) or chronic (17 days to 6 months; n=284) arm and then randomized to 1 of 4 doses of gadoversetamide: 0.05, 0.1, 0.2, or 0.3 mmol/kg. Standard delayed-enhancement MRI was performed before contrast (control) and 10 and 30 minutes after gadoversetamide. For blinded analysis, precontrast and postcontrast MRIs were randomized and then scored for enhanced regions by 3 independent readers not associated with the study. The infarct-related artery perfusion territory was scored from x-ray angiograms separately. In total, 566 scans were performed in 26 centers using commercially available scanners from all major US/European vendors. All scans were included in the analysis. The sensitivity of MRI for detecting MI increased with rising dose of gadoversetamide (P<0.0001), reaching 99% (acute) and 94% (chronic) after contrast compared with 11% before contrast. Likewise, the accuracy of MRI for identifying MI location (compared with infarct-related artery perfusion territory) increased with rising dose of gadoversetamide (P<0.0001), reaching 99% (acute) and 91% (chronic) after contrast compared with 9% before contrast. For gadoversetamide doses > or = 0.2 mmol/kg, 10- and 30-minute images provided equal performance, and peak creatine kinase-MB levels correlated with MRI infarct size (P<0.0001). CONCLUSIONS Gadoversetamide-enhanced MRI using doses of > or = 0.2 mmol/kg is effective in the detection and assessment of both acute and chronic MI. This study represents the first multicenter trial designed to evaluate an imaging approach for detecting MI.
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Optimized contrast-enhanced CT protocols for diagnostic whole-body 18F-FDG PET/CT: technical aspects of single-phase versus multiphase CT imaging.
Brechtel, K, Klein, M, Vogel, M, Mueller, M, Aschoff, P, Beyer, T, Eschmann, SM, Bares, R, Claussen, CD, Pfannenberg, AC
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2006;(3):470-6
Abstract
UNLABELLED The purpose of this study was to compare various PET/CT examination protocols that use contrast-enhanced single-phase or contrast-enhanced multiphase CT scans under different breathing conditions. METHODS Sixty patients with different malignant tumors were randomized into 4 different PET/CT protocols. Single-phase protocols included an intravenous contrast-enhanced (Ultravist 370; iodine at 370 mg/mL) single-phase whole-body CT scan (90 mL at 1.8 mL/min; delay, 90 s) during shallow breathing (protocol A) or during normal expiration (NormExp; protocol B). Multiphase protocols included 2 separate CT scans in the arterial contrast enhancement phase (90 mL at 2.5-2.8 mL/min; bolus tracking; scan range, base of the skull to the kidneys) and the portal-venous contrast enhancement phase (delay, 90 s; scan range, base of the lungs to the proximal thighs) during shallow breathing (protocol C) or during NormExp (protocol D) followed by a low-dose CT scan during shallow breathing for attenuation correction and whole-body PET. Feasibility was assessed by comparing the misalignment of the upper abdominal organs quantitatively by means of the craniocaudal, lateral, and anterior-posterior differences on coregistered PET/CT images. For image quality, the occurrence of CT artifacts and mismatching of rigid body points were evaluated qualitatively. RESULTS Misalignment was significantly lower for protocol B in almost all organs and represented the best coregistration quality. Surprisingly, protocol A showed significantly better alignment than the multiphase CT scans during NormExp. Misalignment values between the multiphase protocols were not significantly different, with a trend toward lower values for protocol D. The best CT image quality, with a significantly lower occurrence of artifacts, was found for protocols B and D (NormExp). The levels of mismatching of rigid body points because of patient movement in between the transmission and emission scans were similar for all protocols. CONCLUSION Multiphase CT protocols presented a technical disadvantage represented by suboptimal image coregistration compared with single-phase protocols. Nevertheless, multiphase protocols are technically feasible and should be considered for patients who will benefit from a contrast-enhanced multiphase CT examination for diagnosis.
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Automatic repositioning of single voxels in longitudinal 1H MRS studies.
Hancu, I, Blezek, DJ, Dumoulin, MC
NMR in biomedicine. 2005;(6):352-61
Abstract
An automatic procedure, allowing the prospective registration of brain MRI images and the acquisition of nearly identical brain volumes (coverage and orientation) in longitudinal exams, is presented. This procedure, based on a fast registration algorithm and a tailored pulse sequence, is used to reposition single voxels for 1H MRS data acquired in vivo. The impact of the repositioning method on the extent of voxel overlap and on the reproducibility of metabolite concentration measurements is studied. A statistically significant increase in voxel overlap and generally decreased short-term measurement variability (decreased coefficients of variation and increased reproducibility coefficients) are observed. Differences in the long-term variances of metabolite concentrations and concentration ratios measured using the eye and automatic repositioning scheme, however, do not reach statistical significance. The improved workflow associated with the use of the automatic repositioning process, which obviates the need for skilled operator intervention for voxel repositioning, suggests that approaches similar to the one presented here may be a standard element in tomorrow's longitudinal MRI and MRS exams.
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Optimizing scan delays of fixed duration contrast injection in contrast-enhanced biphasic multidetector-row CT for the liver and the detection of hypervascular hepatocellular carcinoma.
Kanematsu, M, Goshima, S, Kondo, H, Nishibori, H, Kato, H, Yokoyama, R, Miyoshi, T, Hoshi, H, Onozuka, M, Moriyama, N
Journal of computer assisted tomography. 2005;(2):195-201
Abstract
OBJECTIVE To determine the optimal scan delay required for fixed duration contrast injection in contrast-enhanced biphasic multidetector-row CT for the liver and the detection of hypervascular hepatocellular carcinoma (HCC). METHODS CT images (2.5-mm collimation, 5-mm thickness with no intersectional gap) were obtained after an intravenous bolus injection of 2 mL/kg of nonionic iodine contrast material (300 mg I/mL) for a fixed 30-second injection in 206 patients, who were prospectively randomized into four groups, for which scans were initiated at -5, 15, and 35 seconds; at 0, 20, and 40 seconds; at 5, 25, and 45 seconds; or at 10, 30, and 50 seconds for the first (acquisition time: 4.3 seconds), second (4.3 seconds), and third (9.1 seconds) phases, respectively, after the completion of contrast injection. Mean CT values (HU) of the abdominal aorta, spleen, main portal veins, liver parenchyma, and hepatic veins were measured. Increases in CT values between pre- and post-contrast CTs (DeltaHU) for the organs, and spleen-to-liver and HCC-to-liver contrast differences (deltaHU) were assessed. RESULTS Abdominal aorta reached 273-301 DeltaHU at -5 to 10 seconds with a peak (301 DeltaHU) at 5 seconds. Spleen peaked (115 DeltaHU) at 10 seconds. Liver parenchyma were enhanced weakly (11-34 DeltaHU) at -5 to 10 seconds, exceeded 50 DeltaHU at 20 seconds, peaked (61 DeltaHU) at 30 seconds, and then plateaued (54-58 DeltaHU) at 35-50 seconds. Hepatic veins were enhanced weakly (14-37 DeltaHU) at -5 to 10 seconds, and reached 67 DeltaHU at 15 seconds. Spleen-to-liver (65-69 deltaHU) and HCC-to-liver (31-34 deltaHU) contrast differences were highest at 5-10 seconds. Qualitative results corresponded well with quantitative results. CONCLUSIONS For the detection of hypervascular HCCs, the optimal scan delay after a 30-second contrast injection of the hepatic arterial phase, was found to range from 5 to 10 seconds, and that of the portal venous phase was 35 seconds or somewhat longer.
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Focal hepatic lesions: detection and characterization with combination gadolinium- and superparamagnetic iron oxide-enhanced MR imaging.
Kim, MJ, Kim, JH, Chung, JJ, Park, MS, Lim, JS, Oh, YT
Radiology. 2003;(3):719-26
Abstract
PURPOSE To compare gadolinium- and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for detection and characterization of focal hepatic lesions when different contrast agent administration sequences are used. MATERIALS AND METHODS Unenhanced, dynamic gadolinium-enhanced, and SPIO-enhanced hepatic MR images were obtained in 134 patients. SPIO-enhanced MR imaging was performed immediately after gadolinium-enhanced dynamic MR imaging in 50 patients, 1 day after gadolinium-enhanced dynamic MR imaging in 40 patients, and before gadolinium-enhanced dynamic MR imaging in 44 patients. Two radiologists independently reviewed the gadolinium image set (unenhanced and gadolinium-enhanced dynamic MR images) and the SPIO image set (unenhanced and SPIO-enhanced MR images) in random order. Lesion detection sensitivity and lesion characterization accuracy were compared by analyzing the area under the receiver operating characteristic curve (Az). RESULTS Overall lesion detection accuracy for pooled data was significantly higher with the SPIO set (Az = 0.903) than with the gadolinium set (Az = 0.857) (P <.05). When hypovascular lesions were excluded, the detection rate was similar with the two sets. When hepatocellular carcinomas were excluded, the detection rate was significantly higher with the SPIO set (P <.01). Readers were more accurate in differentiating benign from malignant lesions with the gadolinium set (Az = 0.915) than with the SPIO set (Az = 0.847) (P <.01). Detection accuracy tended to be better with the images obtained after the second contrast agent was used. CONCLUSION Hypovascular lesion detection was better with SPIO-enhanced MR images than with gadolinium-enhanced MR images. Detection and characterization of hypervascular lesions were improved with gadolinium-enhanced MR images.