Gadolinium zeolite as an oral contrast agent for magnetic resonance imaging

The purpose of thls study was to evaluate efficacy and safety of a gadolinium (Gd) zeolite suspension aa an oral MRI contrast agent. Serial dilution of GADO- LITE@ orpl Suspdon 1.2500 pg of GdO/mL) were prepared. MRI (T1 and T2 welghted) of standards and dogs (precontrast and postcontraat) were performed. Toxicity and Gd absorption were also asmaued. Subsequently, 30 nod male adult volunteers were divided into six group of five subjects each. Gd zeolite po suspension waa adminlstered before and after MRI in volumes and concentrations ranging from 250 to 1600 mL; 6 to 80 pg of Gd⁺³/mL. The images were rated (efficacy score) by a bllnded reader. Vital signs, blood chemistries and urlnalysia were recorded. Gadollte Oral Suspension produced excellent enhancement of the dog gastrointestinal (GI) tract. No todclty or absorption of Gd wan obsenred in dogs receiving doses up to 4 times the anticipated human dose My for 14 consecutive days. In clinical tri.lr. Gd zeollte slgnlficantly lmproved the efficacy scores for all groups and all pulrina sequences (all P values <.05). Efflcacy scores and slgnal intendtics generally increased with concentration and volume. No Gd waa detected in blood or urine specimens. No signiftcant adverse events were reported. Gd zeolite 1s a promlsing contrast medium for enhancement of the GI tract in MRI.     

A multisite phase III study of the safety and efficacy of a new manganese chloride-based gastrointestinal contrast agent for MRI of the abdomen and pelvis.

The purpose of this study was to evaluate the safety and efficacy of a manganese chloride-based oral magnetic resonance (MR) contrast agent during a Phase III multisite clinical trial. Two hundred seventeen patients were enrolled who were already scheduled for MRI of the abdomen and/or pelvis. In this group of patients, it was postulated that the use of an oral agent would better allow discrimination of pathology from bowel. Patients with known gastrointestinal pathology including peptic ulcer disease, inflammatory bowel disease, obstruction, or perforation were excluded to minimize confounding variables that could affect the safety assessment. Of these 217 patients, 18 received up to 900 mL of placebo, and 199 patients were given up to 900 mL of a manganese chloride-based oral contrast agent, LumenHance (Bracco Diagnostics, Inc.). Safety was determined by comparing pre- and post-dose physical examinations, vital signs, and laboratory examinations and by documenting adverse events. Efficacy was assessed by unblinded site investigators and two blinded reviewers who compared pre- and post-dose T1- and T2-weighted MRI scans of the abdomen and/or pelvis. In 111 (57%) of the 195 cases evaluated for efficacy by site investigators (unblinded readers), MRI after LumenHance provided additional diagnostic information. Increased information was found by two blinded readers in 52% and 51% of patients, respectively. In 44/195 cases (23%) unblinded readers felt the additional information would have changed patient diagnosis and in 50 patients (26%), it would have changed management and/or therapy. Potential changes in patient diagnosis or management/therapy were seen by the two blinded readers in 8-20% of patients. No clinically significant post-dose laboratory changes were seen. Forty-eight patients (24%) receiving LumenHance and four patients (22%) receiving placebo experienced one or more adverse events. Gastrointestinal tract side effects were most common, seen in 29 (15%) of LumenHance patients and in 3 (17%) of the placebo patients. LumenHance is a safe and efficacious oral gastrointestinal contrast agent for MRI of the abdomen and pelvis.     

The clinical value of ferric ammonium citrate: a positive oral contrast agent for T1-weighted MR imaging of the upper abdomen

This study was undertaken to determine whether ferric ammonium citrate (FAC), a positive magnetic resonance (MR) contrast agent, is of clinical value in demonstrating or excluding pathology of the upper gastrointestinal tract. A retrospective review was performed of pre- and post-FAC studies of MR examinations in 203 patients from phase II and III clinical trials in whom final diagnoses had been established based on the results of biopsy, surgery, or independent imaging procedures. Two independent reviewers made randomized and blinded assessments of the stomach, duodenum, and pancreas. FAC significantly increased the certainty of diagnosis for normal studies of the stomach and duodenum for both readers (P < 0.001) and for abnormal studies of the stomach for one reader (P = 0.004). FAC also significantly increased the certainty of diagnosis for normal pancreas for one reader (P < 0.001). FAC significantly (P < 0.001) increased accuracy and specificity for diagnoses involving the stomach and duodenum for both readers and for one reader for the pancreas. There was significant improvement in sensitivity for gastric diagnoses (P = 0.013) for one reader but not for the duodenum or pancreas. We conclude that FAC is helpful in demonstrating and excluding upper gastrointestinal pathology on MR.     

Efficacy evaluation of gadoteridol for MR angiography of intracranial vascular lesions

A phase III multicenter study was conducted in 89 patients with known intracranial vascular lesions to evaluate an extracellular gadolinium contrast agent, gadoteridol, for intracranial magnetic resonance (MR) angiography. The pre- and postcontrast MR angiograms of 82 patients were evaluated by the unblinded investigators and by two blinded readers (A and B) for visualization of lesions; arterial and venous anatomy; extent, size, and number of lesions; and disease classification. The unblinded readers indicated that lesions were visualized better on postcontrast images in the following categories: venous anatomy, 87 (81%) of 107 lesions; arterial anatomy, 43 lesions (40%); and extent or size of lesions, 38 lesions (36%). In 29 (35%) of 82 patients, the unblinded readers determined that enhanced MR angiography provided more diagnostic information than unenhanced MR angiography. The blinded readers determined that enhanced MR angiography provided more information for visualization of vascular anatomy in more than 60% of cases. The additional information provided with gadoteridol would have changed the diagnosis in nine (8%) of 107 lesions seen by the unblinded readers, 11 (12%) of 90 lesions seen by reader A, and three (3%) of 93 lesions seen by reader B. The results confirm that the use of gadoteridol improves the visualization of intracranial vascular lesions with MR angiography. The authors conclude that development of new postprocessing algorithms will improve the utility of contrast-enhanced MR angiography.     

Clinical safety and efficacy of gadoteridol: a study in 411 patients with suspected intracranial and spinal disease

In this phase III study, 411 adult patients with suspected intracranial or spinal disease underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol (gadolinium 1,4,7-tris [carboxymethyl]-10-[2'-hydroxypropyl]-1,4,7,10-tetraazacyclododecane+ ++). MR images were evaluated by a single unblinded reader at each of 27 sites; the diagnosis was confirmed with one of nine imaging or surgical procedures within 8 weeks before or after MR imaging. After injection, no clinically significant changes were noted in laboratory values, physical examination, or vital signs. Adverse clinical events possibly or probably associated with injection of gadoteridol were seen in 18 of 411 patients (4.4%); the most common were dysgeusia and mild nausea, and all abated without residual effects. MR images enhanced with gadoteridol in patients with confirmed disease provided more diagnostic information than unenhanced images in 128 of 175 brain examinations (73.1%) and 93 of 137 spinal examinations (67.9%). A change in diagnosis because of additional information from contrast-enhanced images was considered likely in 63 of 214 cranial and 54 of 161 spinal studies.     

MR angiography with gadofosveset trisodium for peripheral vascular disease: phase II trial

PURPOSE: To evaluate the dose response and safety of gadofosveset trisodium-enhanced magnetic resonance (MR) angiography compared with nonenhanced two-dimensional time-of-flight MR angiography and with x-ray angiography as the standard. MATERIALS AND METHODS: In this randomized, 20-center, double-blind study, 238 men and women who had peripheral vascular disease or were suspected of having it received intravenous injection of placebo or gadofosveset (0.005, 0.01, 0.03, 0.05, or 0.07 mmol per kilogram of body weight). MR angiographic images were evaluated by three blinded readers, and x-ray angiographic images were evaluated by two readers. Hypothesis testing for the presence of a dose response was based on a linear test for trend for increase in area under the receiver operating characteristic curve as a function of dose for each reader of MR angiographic images independently. RESULTS: Gadofosveset administration resulted in a dose-dependent increase in diagnostic accuracy for detection of aortoiliac occlusive disease as reflected in the area under the receiver operating characteristic curve for each reader (P <.001). The plateau in effectiveness improvement began at the 0.03 mmol/kg dose. At doses of 0.03 mmol/kg and higher, gadofosveset-enhanced MR angiography provided an approximate 20% increase in accuracy over nonenhanced MR angiography for diagnosis of clinically significant aortoiliac occlusive disease. Gadofosveset exhibited a good safety profile in all dose groups. Three serious adverse events were possibly or probably related to gadofosveset administration. There were no dose-related trends in severe or serious adverse events in patients receiving gadofosveset. CONCLUSION: A dose of 0.03 mmol/kg of gadofosveset was safe and effective for evaluation of aortoiliac occlusive disease with MR angiography.     

Safety and pharmacokinetics of p792, a new blood-pool agent: results of clinical testing in nonpatient volunteers

RATIONALE AND OBJECTIVES: To evaluate the safety and pharmacokinetics of P792, a new macromolecular blood-pool agent for magnetic resonance imaging (MRI), in nonpatient volunteers. METHODS: This was a single blind, placebo-controlled, ascending-dose study in 32 healthy male volunteers, randomized to receive a single intravenous dose of P792 (0.0065, 0.013, 0.026, and 0.039 mmol/kg). The safety controls consisted of complete pre- and postdose physical examinations, measurement of vital signs, clinical laboratory investigations, and monitoring of adverse events (up to 22 days after injection). For pharmacokinetic analysis, the determination of P792 was performed using the ICP-MS technique for blood and urine samples up to 22 days. RESULTS: No serious adverse events occurred during the study. There were no clinically significant changes in vital signs, or clinical laboratory findings. P792 blood half-life, distribution volume, and renal clearance are consistent with the definition of a rapid clearance blood-pool agent (RCBPA) as defined previously. CONCLUSION: P792 appeared to be a safe and well-tolerated RCBPA in nonpatient subjects. Phase II studies will be conducted to evaluate the efficacy of the blood-pool agent for vascular, perfusion, and permeability imaging in MRI.     

Thioguanin-induced nodular regenerative hyperplasia of the liver-ROC analysis of different MR techniques

The aim of this study was to evaluate the diagnostic value of different magnetic resonance (MR) techniques for the diagnosis of nodular regenerative hyperplasia (NRH). Thirty-one patients with inflammatory bowel disease, who received 6-thioguanin, underwent liver biopsy and liver MRI on a 1.5-T MR system, with gadolinium and superparamagnetic iron oxide particles (SPIO). MR imaging (MRI) was evaluated independently as well as in consensus by two blinded readers, who received the following image sets: pre-contrast; pre-contrast and gadolinium-enhanced; pre-contrast and SPIO-enhanced and all images. The results were correlated with histopathology and diagnostic efficacy parameters were calculated. NRH was found in 13/31 patients. The set “all images“ showed the highest sensitivity (84.6%), accuracy (77.4%) and negative predictive value (86.7%). However, results for gadolinium were only slightly inferior. The highest specificity (76.5%) was found for SPIO. The A_z values of both readers were highest for gadolinium (mean A_z = 0.824). It can be concluded that gadolinium-enhanced and SPIO-enhanced MRI enable an accurate diagnosis of NRH. Since gadolinium-enhanced MRI is very sensitive, it should be used for screening high-risk patients. SPIO-enhanced MRI is less sensitive, but more specific. The combination of both guarantees a high sensitivity and specificity and, therefore, is the diagnostic procedure of choice.     

硫酸钡混悬剂用作MRI胃肠腔造影剂的研究——Ⅱ、临床试用观察

目的：通过临床志愿者试用观察自行研制的MRI胃肠腔造影用硫酸钡混悬液的安全性和有效性．材料和方法：使用自制MRI胃肠腔造影用硫酸钡混悬液对：100例次的腹部MRI检查进行了胃肠造影，观察该混悬液的造影效果，分布情况，对腹部脏器轮廓显示的影响及副反应。结果：临床试用表明自制硫酸钡混悬液以180%（W／V)浓度口服后使胃肠腔显示明确低信号．有利于腹部器官轮廓的显示，提高了腹部MRI诊断价值，口服后所有病人未出现需对症处理的副反应。结论：我们自行研制的MRI胃肠腔造影用硫酸钡混悬液安全有效，适于临床使用。     

Low-dose gadobenate dimeglumine versus standard dose gadopentetate dimeglumine for contrast-enhanced magnetic resonance imaging of the liver: an intra-individual crossover comparison

RATIONALE AND OBJECTIVES: Gadobenate dimeglumine (Gd-BOPTA) has a two-fold higher T1 relaxivity compared with gadopentetate dimeglumine (Gd-DTPA) and can be used for both dynamic and delayed liver MRI. This intraindividual, crossover study was conducted to compare 0.05 mmol/kg Gd-BOPTA with 0.1 mmol/kg Gd-DTPA for liver MRI. MATERIALS AND METHODS: Forty-one patients underwent two identical MR examinations separated by >or= 72 hours. Precontrast T1-FLASH-2D and T2-TSE sequences and postcontrast T1-FLASH-2D sequences were acquired during the dynamic and delayed (1-2 hours) phases after each contrast injection. Images were evaluated on-site by two independent, blinded off-site readers in terms of confidence for lesion detection, lesion number, character and diagnosis, enhancement pattern, lesion-to-liver contrast, and benefit of dynamic and delayed scans. Additional on-site evaluation was performed of the overall diagnostic value of each agent. RESULTS: Superior diagnostic confidence was noted by on-site investigators and off-site assessors 1 and 2 for 6, 4 and 2 patients with Gd-BOPTA, and for 3, 1 and 2 patients with Gd-DTPA, respectively. No consistent differences were noted for other parameters on dynamic phase images whereas greater lesion-to-liver contrast was noted for more patients on delayed images after Gd-BOPTA. More correct diagnoses of histologically confirmed lesions (n = 26) were made with the complete Gd-BOPTA image set than with the complete Gd-DTPA set (reader 1: 68% vs. 59%; reader 2: 78% vs. 68%). The overall diagnostic value was considered superior after Gd-BOPTA in seven patients and after Gd-DTPA in one patient. CONCLUSION: The additional diagnostic information on delayed imaging, combined with the possibility to use a lower overall dose to obtain similar diagnostic information on dynamic imaging, offers a distinct clinical advantage for Gd-BOPTA for liver MRI.     

Multicentre dose-ranging study on the efficacy of USPIO ferumoxtran-10 for liver MR imaging

AIM: A dose ranging multicentre phase-II clinical trial was conducted to evaluate the efficacy of ultrasmall superparamagnetic iron oxide (USPIO) ferumoxtran-10 for magnetic resonance (MR) imaging of focal hepatic lesions. MATERIAL AND METHODS: Ninety-nine patients with focal liver lesions received USPIO at a dose of 0.8 (n = 35), 1.1 (n = 32), or 1.7 (n = 32) mg Fe/kg. Liver MR imaging was performed before and after USPIO with T1-weighted and T2-weighted pulse sequences. Images were analysed by two independent readers for additional information (lesion detection, exclusion, characterization and patient management). Signal intensity (SI) based quantitative measurements were also taken. RESULTS: Post-contrast medium MR imaging showed additional information in 71/97 patients (73%) for reader one and 83/96 patients (86%) for reader two. The results with all three doses were statistically significant (P < 0.05). Signal intensity analysis revealed that all three doses increased liver SI on T1-weighted images and decreased liver SI on T2-weighted images. On T2-weighted images metastases increased in contrast relative to normal hepatic parenchyma whereas haemangiomas decreased in contrast. On T2-weighted images there was statistically improved efficacy at the intermediate dose, which did not improve at the highest dose. CONCLUSION: Ultrasmall superparamagnetic iron oxide was an effective contrast agent for liver MR imaging at all doses and a dose of 1.1 mg Fe/kg was recommended for future clinical trials.     

Image fusion of thallium-201 SPECT and MR imaging for the assessment of recurrent head and neck tumors following flap reconstructive surgery

The aim of this study was to assess the value of fused MR and Tl-201 single photon emission computed tomography (SPECT) images in the diagnosis of recurrent head and neck tumors in patients after flap reconstruction surgery. Twenty-four patients after resection of primary head and neck tumors with flap reconstruction were suspected of having recurrent tumor by follow-up MR examination. Both MR examination and Tl-201 SPECT were prospectively performed to produce fused images. For qualitative analysis, two independent readers separately evaluated the existence of tumor recurrence in the fused images. The Tl-201 uptake of the lesion (Tl index) was also quantitatively compared with that of the normal nuchal muscles. Eighteen patients were histologically proved as having recurrence. The remaining 6 patients, false positive on MRI alone, had non-recurrence. Using the fused images, false positive was found in 1 case for one reader and 2 cases for the other reader. The Tl index of recurrent tumors was significantly higher (p<0.001) than that of non-recurrent mass lesions. In the assessment of recurrent tumors following flap reconstruction surgery in the head and neck, the use of fused MRI and Tl-201 SPECT images can reduce the number of false positives.     

MR angiography of aortoiliac occlusive disease: a phase III study of the safety and effectiveness of the blood-pool contrast agent MS-325

PURPOSE: To evaluate prospectively the safety and effectiveness of aortoiliac magnetic resonance (MR) angiography enhanced with MS-325 (gadofosveset trisodium) at a dose of 0.03 mmol/kg; effectiveness was defined as accuracy relative to the reference standard, conventional angiography. MATERIALS AND METHODS: Study was approved by institutional review boards of participating institutions, and required national approvals were obtained. Study protocol conformed to Good Clinical Practice guidelines, and informed patient consent was obtained. Patients with known or suspected peripheral vascular disease received 0.03 mmol/kg MS-325 for aortoiliac MR angiography. They were also examined with conventional angiography. MS-325-enhanced MR was evaluated for safety and effectiveness. Along with unenhanced two-dimensional time-of-flight MR angiography, it was compared with conventional angiography for presence of vascular stenosis. Student t tests were used to identify significant improvement in diagnostic sensitivity, specificity, and accuracy, as well as quantitative characterization of stenoses by three blinded readers. Correlations between readers of conventional angiograms were calculated and compared with MR results. RESULTS: In 174 patients, MS-325-enhanced MR angiography showed significant improvement (P < or = .001) in sensitivity, specificity, and accuracy for diagnosis of clinically significant (> or =50%) stenosis, compared with unenhanced MR. For all readers, areas under the receiver operating characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for MS-325-enhanced MR compared with time-of-flight MR. All readers also expressed higher confidence in diagnosis (P < .001) and found fewer images uninterpretable with MS-325 enhancement. All measures of interpretation accuracy approached corresponding measures of correlation between readers of conventional angiograms. Incidence of severe and serious adverse events with MS-325 was low. No patients were withdrawn from study due to adverse events or abnormalities in laboratory results. There were no clinically important trends in findings at hematology, blood chemistry, urinalysis, electrocardiography, or physical examination. CONCLUSION: MR angiography with MS-325 provides significant improvement in effectiveness over unenhanced MR (and minimal and transient side effects) at a dose of 0.03 mmol/kg and was safe and effective for MR evaluation of patients with aortoiliac occlusive disease.     

Efficacy and safety of MR imaging with liver-specific contrast agent: U.S. multicenter phase III study

PURPOSE: To assess prospectively the efficacy and safety of postcontrast magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) compared with that of precontrast MR imaging in patients who are known to have or are suspected of having liver lesions and who are scheduled for hepatic surgery. MATERIALS AND METHODS: Investigational review board approval and written informed consent were obtained. HIPAA went into effect after data collection. A total of 172 patients were enrolled. After precontrast MR imaging, 169 patients (94 men, 75 women; mean age, 61 years; age range, 19-84 years) received an intravenous bolus of 25 micromol/kg Gd-EOB-DTPA and underwent dynamic gradient-recalled-echo and delayed MR imaging 20 minutes after injection. Arterial and portal phase computed tomography (CT) were performed within 6 weeks of MR imaging. The standard of reference was surgery with intraoperative ultrasonography (US) and biopsy and/or pathologic evaluation of resected liver segments and/or 3-month follow-up of nonresected segments if intraoperative US was not available. Three blinded reviewers and unblinded site investigators identified liver lesions on segment maps. The Wilcoxon signed rank test was used to compare differences in per-patient sensitivity of precontrast and postcontrast MR images. Adverse events were recorded, and patient monitoring and laboratory assay were performed at time of injection and up to 24 hours after contrast material administration. RESULTS: At MR imaging, 316 lesions were identified in 131 patients. In 77% (P = .012), 72% (P = .15), and 71% (P = .027) of patients for readers 1, 2, and 3, respectively, more lesions were seen at precontrast and postcontrast MR imaging combined than at precontrast MR imaging alone. Sensitivity values for blinded readings were significantly greater at postcontrast MR imaging than at precontrast MR imaging for two of three blinded readers. For all blinded readers, combined precontrast and postcontrast MR images showed no difference in sensitivity compared with helical CT scans. The use of MR imaging, however, yielded fewer patients with at least one false-positive lesion (37%, 31%, and 34% of patients for readers 1, 2, and 3, respectively) than did helical CT (45%, 36%, and 43% of patients for readers 1, 2, and 3, respectively). CONCLUSION: Compared with precontrast MR imaging, postcontrast MR imaging with Gd-EOB-DTPA demonstrated improved sensitivity for lesion detection in the majority of blinded readers, with no substantial adverse events.     

Detection of extracapsular extension of prostate cancer: role of fat suppression endorectal MRI

PURPOSE: The purpose of this work was to compare the efficacy of fat-suppressed and non-fat-suppressed fast spin echo (FSE) endorectal MRI in the detection of extracapsular extension (ECE) of prostate cancer by experienced and inexperienced readers. METHOD: Seventy-nine patients with biopsy-proven prostate cancer underwent axial FSE T2-weighted endorectal MRI of the prostate prior to radical prostatectomy. Twenty-one patients were imaged with frequency-selective fat suppression, and 58 were imaged without fat suppression. All images were retrospectively and independently reviewed by two readers of different experience levels who were blinded to clinical and pathological findings. Readers assessed the presence or absence of ECE on a 5 point scale for each side of the prostate, and step-section pathology was used as the standard of reference in all patients. Receiver operating characteristics analysis was used to compare the performance of fat-suppressed and non-fat-suppressed images by both readers. RESULTS: ECE was present in 33 of 79 (42%) patients. The more experienced reader demonstrated better diagnostic performance (p < 0.05) than the less experienced reader in terms of sensitivity and area under the ROC curve (Az) for MRI without fat suppression. Use of frequency-selective fat suppression did not result in any significant improvement in diagnosis of ECE compared with MRI without fat suppression for either the experienced (Az 0.81 vs. 0.79) or the inexperienced (Az 0.76 vs. 0.68) reader. CONCLUSION: Even when reader experience is considered, use of frequency-selective fat suppression did not significantly improve the diagnosis of ECE by MRI. The decision to use fat suppression and the selection of a fat suppression technique can be left to the discretion of the individual reader.     

Multicenter study of gadodiamide injection as a contrast agent in MR imaging of the brain and spine

To evaluate the safety and efficacy of gadodiamide injection, a nonionic gadolinium chelate complex, in magnetic resonance (MR) imaging of the head and spine, a phase II-III trial was conducted in 439 patients with known or suspected lesions in the central nervous system. All patients received gadodiamide injection in a dosage of 0.1 mmol/kg and were monitored; MR images were evaluated for contrast material enhancement. No serious adverse events or clinically important trends in vital signs, laboratory values, or neurologic status were observed. Gadodiamide injection enhanced or facilitated the visualization of lesions in 266 or 353 patients (75.4%) in whom lesions were shown on unenhanced images, enhanced images, or both; in these 266 patients, the diagnosis was changed in 76 patients (28.6%) and facilitated in 190 patients (71.4%). It is concluded that gadodiamide injection is safe and effective for MR imaging of the head and spine in patients with suspected abnormalities of the central nervous system.     

Magnetic resonance imaging contrast enhancement of brain tumors at 3 tesla versus 1.5 tesla

RATIONALE AND OBJECTIVES: To compare the diagnostic efficacy of a standard dose of MRI contrast agent in the evaluation of primary brain tumors and metastases using a high-field 3 tesla MR unit versus a 1.5 tesla MR unit. METHODS: Sixteen patients with brain tumors were examined at both field strengths using identical axial T1-SE protocols pre- and postcontrast (0.1 mmol/kg gadolinium), and postcontrast coronal 3D GRE with magnetization preparation (MP-RAGE), which was adjusted separately for each field strength. Evaluation of the images was performed quantitatively and, in the case of T1-SE images, also by visual assessment. RESULTS: Tumor-to-brain-contrast after gadolinium administration using statistical evaluation of MP-RAGE scans was significantly higher at 3 tesla (97.5) than at 1.5 tesla (46.3). The same was true for T1-SE sequences (93.0 vs. 72.1). Signal enhancement of the lesions in T1-SE sequences was not significantly different between both field strengths. CONCLUSIONS: Administration of a gadolinium contrast agent produces higher contrast between tumor and normal brain at 3 tesla than at 1.5 tesla.     

Intra- and interreader reproducibility of magnetic resonance imaging for quantifying the lipid-rich necrotic core is improved with gadolinium contrast enhancement

PURPOSE: To test the hypothesis that intra- and interreader reproducibility for measuring the lipid-rich necrotic core (LR-NC) size is significantly improved with gadolinium (Gd) contrast-enhanced magnetic resonance imaging (CEMRI) compared to non-CEMRI. MATERIALS AND METHODS: Thirty-seven individuals with >50% carotid artery stenosis underwent carotid MRI at 1.5T (pre- and postcontrast T1-weighted (T1W), T2-weighted (T2W), proton density-weighted (PDW), and three-dimensional time-of-flight (TOF) sequences). Two independent readers measured the mean area of the LR-NC from the precontrast images only, followed by a second measurement using the additional postcontrast images. One reader repeated the measurements after an interval of five months. Intra- and interreader reproducibility was analyzed by means of the intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard deviation (SD). RESULTS: The CV decreased from 33.7% to 8.8% for intrareader measurements of the LR-NC, and from 33.5% to 17.6% for interreader measurements. The SD was significantly smaller with CEMRI than with non-CEMRI (P = 0.003 and P = 0.006, respectively). The ICC increased from 0.94 to 0.99 and from 0.85 to 0.93 for the intra- and interreader measurements, respectively. CONCLUSION: Reader reproducibility for in vivo MRI quantification of LR-NC size is significantly improved by the addition of Gd contrast in individuals with >50% carotid stenosis.     

口服红氧化铁混悬液用于胃部MRI的研究

目的评价红氧化铁超顺磁性口服磁共振对比剂在胃部MR I诊断中的应用价值。方法采用扫描前口服红氧化铁对比剂,对36例年龄21~60岁受检者行胃部MR检查,对图像进行影像学分析。结果36例受检者服用对比剂后,胃充盈达100%。在各序列扫描中,均呈阴性对比,胃部病变及毗邻关系显示清晰。行MRCP时,可有效抑制胃肠道高信号伪影。结论在胃部MR检查中,口服红氧化铁对比剂易于接受,安全性好,性能稳定,成像浓度范围宽,是一种优良的胃肠阴性对比剂。