Association of Chemoradiotherapy Regimens and Survival Among Patients With Nasopharyngeal Carcinoma: A Systematic Review and Meta-analysis.

Importance: The role of induction chemotherapy (IC) or adjuvant chemotherapy (AC) in the treatment of locoregionally advanced nasopharyngeal carcinoma (NPC) remains controversial. Objectives: To update meta-analyses on the association of survival outcomes with IC and AC regimens in patients with locoregionally advanced NPC and assess whether the current evidence is conclusive by a trial sequential analysis (TSA) approach. Data Sources: PubMed, Embase, and Web of Science were searched for articles published from inception until June 1, 2019. Study Selection: Randomized clinical trials that assessed the efficacy of radiotherapy with or without chemotherapy among previously untreated patients and patients with nondistant metastatic NPC. Data Extraction and Synthesis: Data were extracted by 2 investigators from each trial independently and synthesized by the 2 investigators. All trial results were combined and analyzed by a fixed- or random-effects model. Main Outcomes and Measures: Overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional recurrence-free survival (LRFS). Results: A total of 8036 patients (median age, 46.5 years; 5872 [73.1%] male) from 28 randomized clinical trials were included in the analysis. Pooled analyses revealed that concurrent chemoradiotherapy (CCRT) was significantly associated with improved OS, PFS, DMFS, and LRFS compared with radiotherapy across all subgroups. The TSA confirmed the treatment outcomes of CCRT compared with radiotherapy. The additional IC regimen was associated with an improvement in OS (hazard ratio [HR], 0.84; 95% CI, 0.74-0.95), PFS (HR, 0.73; 95% CI, 0.64-0.84), DMFS (HR, 0.67; 95% CI, 0.59-0.78), and LRFS (HR, 0.74; 95% CI, 0.64-0.85). These findings were consistent in subgroup analyses of multicenter trials with sample sizes greater than 250, years of survival rate of 5 or greater, median follow-up longer than 5 years, or low risk of bias. However, the additional AC regimen was not associated with a survival benefit in OS (HR, 0.98; 95% CI, 0.78-1.23), PFS (HR, 0.86; 95% CI, 0.70-1.07), DMFS (HR, 0.84; 95% CI, 0.64-1.10), or LRFS (HR, 0.80, 95% CI, 0.59-1.09). The TSA provided sound evidence on the additional benefit of IC but not AC. Conclusions and Relevance: These data suggest a significant association of survival outcomes with CCRT in patients with locoregionally advanced NPC. The addition of IC instead of AC could achieve survival benefits. The potential therapeutic gain of AC should be explored in the future.

Endoscopic surgery for primary sinonasal malignancies: Treatment outcomes and prognostic factors.

We retrospectively reviewed the cases of 85 patients with primary sinonasal malignancies who had undergone endoscopic surgery with curative intent achieved by "regional resection." Our goal was to assess the efficacy of endoscopic surgical treatment vis-à-vis traditional open surgery. Kaplan-Meier data analysis revealed that the 1-, 3-, and 5-year disease-specific survival rates were 82, 60, and 49%, respectively. Multivariate Cox model survival analysis revealed that male sex, certain pathologic types of cancer (i.e., undifferentiated carcinoma, olfactory neuroblastoma, and rhabdomyosarcoma), and T3/T4 category negatively impacted survival (adjusted hazard ratios: 3.601, 0.012, 0.287, 0.068, and 0.339, respectively; p < 0.05 for all). We also performed a separate analysis of 47 patients who had category T3 or T4 cancer to determine if the type of surgical approach is a prognostic factor. For this, we identified 20 new patients who had undergone open resection, and we compared them to 27 of our endoscopically treated patients who had similar clinical characteristics. We found that the type of surgical approach did not appear to be a prognostic factor (p > 0.10), although those patients who had undergone endoscopic resection had significantly shorter hospital stays (p < 0.001). We conclude that patients with primary sinonasal malignancies who are treated with endoscopic surgery have acceptable survival rates and therefore endoscopic surgery is justified in the hands of highly experienced surgeons in selected cases.

Exploration and validation of radiomics signature as an independent prognostic biomarker in stage III-IVb nasopharyngeal carcinoma.

There is no consensus on specific prognostic biomarkers potentially improving survival of nasopharyngeal carcinoma (NPC), especially in advanced-stage disease. The prognostic value of MRI-based radiomics signature is unclear. A total of 970 quantitative features were extracted from the tumor of 100 untreated NPC patients (stage III-IVb) (discovery set: n = 70, validation set: n = 30). We then applied least absolute shrinkage and selection operator (lasso) regression to select features that were most associated with progression-free survival (PFS). Candidate prognostic biomarkers included age, gender, overall stage, hemoglobin, platelet counts and radiomics signature. We developed model 1 (without radiomics signature) and model 2 (with radiomics signature) in the discovery set and then tested in the validation set. Multivariable Cox regression analysis was used to yield hazard ratio (HR) of each potential biomarker. We found the radiomics signature stratified patients in the discovery set into a low or high risk group for PFS (HR = 5.14, p < 0.001) and was successfully validated for patients in the validation set (HR = 7.28, p = 0.015). However, the other risk factors showed no significantly prognostic value (all p-values for HR, > 0.05). Accordingly, pretreatment MRI-based radiomics signature is a non-invasive and cost-effective prognostic biomarker in advanced NPC patients, which would improve decision-support in cancer care.

To predict the radiosensitivity of nasopharyngeal carcinoma using intravoxel incoherent motion MRI at 3.0 T.

PURPOSE: To investigate intravoxel incoherent motion (IVIM) MRI for evaluating the sensitivity of radiotherapy on nasopharyngeal carcinoma (NPC). RESULTS: The reproducibility between intra-observer and inter-observer was relatively good. D (0.72×10-3 mm2/s±0.14 vs. 0.54×10-3 mm2/s±0.23; P < 0.001) and D* (157.92×10-3 mm2/s±15.21 vs. 120.36×10-3 mm2/s±10.22; P < 0.0001) were significantly higher in effective group than poor-effective group, whereas the difference of f (18.79%±2.51 vs. 16.47%±1.51) and ADC (1.21×10-3 mm2/s±0.11 vs. 1.33×10-3 mm2/s±0.23) could not reach statistical significant between the 2 groups (P > 0.05). CONCLUSIONS: IVIM may be potentially useful in assessing the radiosensitivity of NPC. The higher D value combining with higher D* value might indicate the more radiosensitive of NPC, and increased D* might reflect increased blood vessel generation and parenchymal perfusion in NPC. MATERIALS AND METHODS: Sixty consecutive patients (20 female, range, 27-83 years, mean age, 52 years) newly diagnosed NPC in the stage of T3 or T4 were enrolled. Forty-two of them were divided into effective group clinically after a standard radiotherapy according to the RECIST criteria. IVIM with 13 b-values (range, 0-800 s/mm2) and general MRI were performed at 3.0T MR scanner before and after radiotherapy. The parameters of IVIM including perfusion fraction (f), perfusion-related diffusion (D*), pure molecular diffusion (D) and apparent diffusion coefficient (ADC) were calculated. Two radiologists major in MRI diagnose analyzed all images independently and placed regions of interest (ROIs). Intra-class correlation coefficient (ICC) was used to evaluate intra-observer and inter-observer agreement. And Mann-Whitney test was used to assess the differences between the two groups.

Machine Learning Algorithms for Risk Prediction of Severe Hand-Foot-Mouth Disease in Children.

The identification of indicators for severe HFMD is critical for early prevention and control of the disease. With this goal in mind, 185 severe and 345 mild HFMD cases were assessed. Patient demographics, clinical features, MRI findings, and laboratory test results were collected. Gradient boosting tree (GBT) was then used to determine the relative importance (RI) and interaction effects of the variables. Results indicated that elevated white blood cell (WBC) count > 15 × 109/L (RI: 49.47, p < 0.001) was the top predictor of severe HFMD, followed by spinal cord involvement (RI: 26.62, p < 0.001), spinal nerve roots involvement (RI: 10.34, p < 0.001), hyperglycemia (RI: 3.40, p < 0.001), and brain or spinal meninges involvement (RI: 2.45, p = 0.003). Interactions between elevated WBC count and hyperglycemia (H statistic: 0.231, 95% CI: 0-0.262, p = 0.031), between spinal cord involvement and duration of fever ≥3 days (H statistic: 0.291, 95% CI: 0.035-0.326, p = 0.035), and between brainstem involvement and body temperature (H statistic: 0.313, 95% CI: 0-0.273, p = 0.017) were observed. Therefore, GBT is capable to identify the predictors for severe HFMD and their interaction effects, outperforming conventional regression methods.

CT and MRI findings in focal eosinophilic infiltration of the liver.

OBJECTIVES: To investigate the findings of computed tomography (CT) and magnetic resonance imaging (MRI) of focal eosinophilic infiltration (FEI) of the liver. METHODS: A retrospective study including 29 patients with confirmed FEI of the liver was performed. We evaluated the lesions' number, distribution, size, shape, margin, attenuation or signal intensity characteristics, the enhancement pattern, and some special features. Spearman correlation analysis was used to analyze the correlation between the number of lesions and the eosinophil counts in peripheral blood. RESULTS: In all, 108 lesions were detected in 29 cases, including two cases with single lesion and the remaining 27 cases with multiple lesions. The mean size of all lesions was 34 mm (range, from 3 to 61 mm). 95 (88%) lesions were located in subcapsular parenchyma or surrounding the portal vein. Most (66%) subcapsular lesions were wedge shaped and all lesions surrounding portal vein were round shaped. However, the hepatic parenchymal lesions were irregular or round shaped. All lesions showed ill-defined margins. On pre-contrast CT images, the lesions showed slightly low attenuation or iso-attenuating. On T1-weighted and T2-weighted images, the lesions were slightly iso-/hypointense and hyperintense, respectively. A total of 23 (79.3%) cases were gradually enhanced. Branches of portal vein went through the lesions in all cases; 12 had 'stripe sign' and 16 had 'halo ring sign.' Spearman analysis indicated a significant correlation between the number of lesions and the increased eosinophils in peripheral blood (r = 0.627, p = 0.0003). CONCLUSIONS: Special CT and MRI features and increased eosinophils may strongly suggest the diagnosis of FEI of the liver.

Neuro-Magnetic Resonance Imaging in Hand, Foot, and Mouth Disease: Finding in 412 Patients and Prognostic Features.

PURPOSE: The aims of this study were to describe the neuroimaging findings in hand, foot, and mouth disease and determine those who may provide prognosis. MATERIAL AND METHODS: Magnetic resonance imaging scans in 412 severe hand, foot, and mouth disease between 2009 and 2014 were retrospectively evaluated. The patients who had the neurological signs were followed for 6 months to 1 year. According to the good or poor prognosis, 2 groups were categorized. The incidence of lesions in different sites between the 2 groups was compared, and multivariate analysis was used to look for risk factors. RESULTS: The major sites of involvement for all patients with percentages were the medulla oblongata (16.1%), spinal anterior nerve roots (12.4%), thoracic segments (11.1%), brain or spinal meninges (8.3%), and so on. There were 347 patients (84.2%) with good prognosis and 65 (15.8%) with poor prognosis in the follow-up. There was a significantly higher rate of lesions involving the cerebral white substance, thalamus, medulla oblongata, pons, midbrain, and spinal cord in the group with poor prognosis. Multivariate analysis showed 2 independent risk factors associated with poor prognosis: lesions located in the medulla oblongata (P < 0.015) and spinal cord (P < 0.001) on magnetic resonance imaging; the latter was the most significant prognostic factor (odds ratio, 29.11; P < 0.001). CONCLUSIONS: We found that the distribution patterns for all patients mainly involved the medulla oblongata, spinal anterior nerve roots, thoracic segments, and brain or spinal meninges. Our findings suggested that patients with lesions located in the medulla oblongata and spinal cord may be closely monitored for early intervention and meticulous management. For children with the symptom of nervous system, they are strongly recommended for magnetic resonance examination.

Using intravoxel incoherent motion MR imaging to study the renal pathophysiological process of contrast-induced acute kidney injury in rats: Comparison with conventional DWI and arterial spin labelling.

OBJECTIVES: To investigate the potential of intravoxel incoherent motion (IVIM) to assess the renal pathophysiological process in contrast-induced acute kidney injury (CIAKI). METHODS: Twenty-seven rats were induced with CIAKI model, six rats were imaged longitudinally at 24 h prior to and 30 min, 12, 24, 48, 72 and 96 h after administration; three rats were randomly chosen from the rest for serum creatinine and histological studies. D, f, D* and ADC were calculated from IVIM, and renal blood flow (RBF) was obtained from arterial spin labelling (ASL). RESULTS: A progressive reduction in D and ADC was observed in cortex (CO) by 3.07 and 8.62 % at 30 min, and by 25.77 and 28.16 % at 48 h, respectively. A similar change in outer medulla (OM) and inner medulla (IM) was observed at a later time point (12-72 h). D values were strongly correlated with ADC (r = 0.885). As perfusion measurement, a significant decrease was shown for f in 12-48 h and an increase in 72-96 h. A slightly different trend was found for D*, which was decreased by 26.02, 21.78 and 10.19 % in CO, OM and IM, respectively, at 30 min. f and D* were strongly correlated with RBF in the cortex (r = 0.768, r = 0.67), but not in the medulla. CONCLUSIONS: IVIM is an effective imaging tool for monitoring progress in renal pathophysiology undergoing CIAKI. KEY POINTS: • IVIM analysis permits separate quantification of diffusion and perfusion. • IVIM can provide useful biomarkers ifor changes in renal pathophysiology. • IVIM can be useful for monitoring progress in renal pathophysiology undergoing CIAKI.

Imaging Anatomy of Waldeyer's Ring and PET/CT and MRI Findings of Oropharyngeal Non-Hodgkin's Lymphoma.

BACKGROUND: This study was conducted to analyze positron emission tomography (PET) / computed tomography (CT) and magnetic resonance imaging (MRI) performance with oropharyngeal non-Hodgkin's lymphoma (ONHL). MATERIALS AND METHODS: The complete image data of 30 ONHL cases were analyzed, all patients were performed PET / CT and MRI examination before the treatment, with the time interval of these two inspections not exceeding 14 days. The distribution, morphology, MRI signal characteristics, enhancement feature, standardized uptake value (SUV) max value and lymph node metastasis way of the lesions were analyzed. RESULTS: Among the 30 cases, 23 cases were derived from the B-cell (76.7%), 5 cases were derived from the peripheral T cells (16.7%) and 2 cases were derived from the NK/T cells (6.7%). 19 cases exhibited the palatine tonsil involvement (63.3%). As for the lesion appearance, 10 cases appeared as mass, 8 cases were the diffused type and 12 cases were the mixed type. 25 cases exhibited the SUVmax value of PET / CT primary lesions as 11 or more (83.3%). MRI showed that all patients exhibited various degrees of parapharyngeal side-compressed narrowing, but MRI still exhibited the high-signal fat, and the oropharyngeal mucosa was intact. 25 cases were associated with the neck lymph node metastasis, among who 22 cases had no necrosis in the metastatic lymph nodes, while the rest 3 cases exhibited the central necrosis in the metastatic lymph nodes. CONCLUSIONS: PET / CT and MRI have important value in diagnosing and determining the lesion extent of ONHL.

To evaluate the damage of renal function in CIAKI rats at 3T: using ASL and BOLD MRI.

PURPOSE: To investigate noninvasive arterial spin-labeling (ASL) and blood oxygen level-dependent imaging (BOLD) sequences for measuring renal hemodynamics and oxygenation in contrast induced acute kidney injury (CIAKI) rat. MATERIALS AND METHODS: Thirteen SD rats were randomly grouped into CIAKI group and control group. Both ASL and BOLD sequences were performed at 24 h preinjection and at intervals of 0.5, 12, 24, 48, 72, and 96 h postinjection to assess renal blood flow (RBF) and relative spin-spin relaxation rate (R2(*)), respectively. RESULTS: For the CIAKI group, the value of RBF in the cortex (CO) and outer medulla (OM) of the kidney was significantly decreased (P < 0.05) at 12-48 h and regressed to baseline level (P = NS) at 72-96 h. In OM, the value of R2(*) was increased at 0.5-48 h (P < 0.05) and not statistically significant (P = NS) at 72 and 96 h. CONCLUSIONS: RBF in OM and CO and oxygen level in OM were decreased postinjection of CM. ASL combining BOLD can further identify the primary cause of the decrease of renal oxygenation in CIAKI. This approach provides means for noninvasive monitoring renal function during the first 4 days of CIAKI in clinical routine work.

Initial experience of correlating parameters of intravoxel incoherent motion and dynamic contrast-enhanced magnetic resonance imaging at 3.0 T in nasopharyngeal carcinoma.

PURPOSE: To determine the correlation between intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) parameters. METHODS: Thirty-eight newly diagnosed NPC patients were prospectively enrolled. Diffusion-weighted images (DWI) at 13 b-values were acquired using a 3.0-T MRI system. IVIM parameters including the pure molecular diffusion (D), perfusion-related diffusion (D*), perfusion fraction (f), DCE-MRI parameters including maximum slope of increase (MSI), enhancement amplitude (EA) and enhancement ratio (ER) were calculated by two investigators independently. Intra- and interobserver agreement were evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. Relationships between IVIM and DCE-MRI parameters were evaluated by calculation of Spearman's correlation coefficient. RESULTS: Intra- and interobserver reproducibility were excellent to relatively good (ICC = 0.887-0.997; narrow width of 95 % limits of agreement). The highest correlation was observed between f and EA (r = 0.633, P < 0.001), with a strong correlation between f and MSI (r = 0.598, P = 0.001). No correlation was observed between f and ER (r = -0.162; P = 0.421) or D* and DCE parameters (r = 0.125-0.307; P > 0.119). CONCLUSION: This study suggests IVIM perfusion imaging using 3.0-T MRI is feasible in NPC, and f correlates significantly with EA and MSI. KEY POINTS: Assessment of tumour perfusion is important in nasopharyngeal carcinoma. DCE-MRI provided perfusion information with the use of intravenous contrast media. Perfusion information could be provided by non-invasive IVIM MRI. IVIM parameter f correlated with DCE-MRI parameters.

Celecoxib enhances radiosensitivity via induction of G2-M phase arrest and apoptosis in nasopharyngeal carcinoma.

BACKGROUND: Previous work has proposed that celecoxib may be able to enhance the effects of radiotherapy. However, the underlying mechanism of this activity has not yet been determined. METHODS: The cell colony formation assay after the combination of celecoxib and radiation treatment was done on C666-1, CNE-1 and CNE-2 nasopharyngeal carcinoma cells, which expressed different COX-2 levels. Moreover, COX-2 knocked down or overexpressed cells were developed, and apoptosis and cell cycle analysis were performed. RESULTS: Celecoxib enhances radiation cytotoxicity in C666-1 and CNE-1 nasopharyngeal carcinoma cells that expressed high COX-2 but not in CNE-2 cells that expressed low COX-2. The radiosensitization of celecoxib in C666-1 cells disappeared after the COX-2 knocked down, while the CNE-2 cells were radiosensitized by celecoxib after the transfection of COX-2. Moreover, celecoxib enhanced radiation-induced G2-M phase arrest was observed in some of the tested cells. Furthermore, we found that the radiosensitivity of celecoxib in nasopharyngeal carcinoma was correlated with the apoptosis induction. Additionally, the combination of celecoxib (25 mg/kg) and radiation (6 Gy) treatment significantly reduced tumor volume in C666-1 and CNE-2 nasopharyngeal carcinoma xenograft models. CONCLUSION: These results indicate that the combination of celecoxib and radiation treatment has potential application in radiotherapy, and these effects may be attributable to the G2-M cell phase arrest and enhancement of cell apoptosis.

Evaluation of the applicability of Resovist in DSC-MR perfusion-weighted imaging of rat hyperacute cerebral infarction.

AIM: The aim of this study was to evaluate the use of Resovist in perfusion-weighted imaging (PWI) of rat hyperacute cerebral infarction. MATERIAL AND METHODS: 30 Wistar rats were randomly divided into 2 groups. Group A was intravenously injected with 8 µmol Fe/kg body weight of Resovist, whilst Group B was injected with 0.2 mmol/kg body weight of Gd-DTPA. These dosages were chosen to provide comparable maximum signal changes in normally perfused brain. CBV, CBF and MTT parameter profiles were obtained for the core diseased region and the penumbra of brain ischemia and compared between the two groups. These results were then correlated with pathological findings and TTC staining. RESULTS: In our rat stroke model, signal-time curves were similar between Gd-DTPA and Resovist, both in the core area with severe ischemia and in the penumbra area with moderate ischemia. The CBV, MTT, and TTP values of PWI for ischemic penumbra in Groups A and B showed no statistical disparity. CONCLUSION: The efficacy of Resovist in MR PWI is similar to Gd-DTPA in the diagnosis of perfusion reduction in the rat stroke model.

Intravoxel incoherent motion MRI: emerging applications for nasopharyngeal carcinoma at the primary site.

OBJECTIVES: We compared pure molecular diffusion (D), perfusion-related diffusion (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) based on intravoxel incoherent motion (IVIM) theory in patients with nasopharyngeal carcinoma (NPC). METHODS: Sixty-five consecutive patients (48 men) with suspected NPC were examined using a 3.0-T MR system. Diffusion-weighted imaging (DWI) was performed with 13 b values (range, 0-800 s/mm(2)). We regarded the result of endoscopy and biopsy as the gold standard for detection. D, D* and f were compared between patients with primary NPC and enlarged adenoids. RESULTS: IVIM DWI was successful in 37 of 40 NPC and 23 of 25 enlarged adenoids cases. D (P = 0.001) and f (P < 0.0001) were significantly lower in patients with NPC than in patients with enlarged adenoids, whereas D* was significantly higher (P < 0.0001). However, the ADC was not significantly different between the two groups (P > 0.05). The area under the ROC curve (AUC) for D was 0.849 and was significantly larger than that for ADC (P < 0.05). CONCLUSIONS: IVIM DWI is a feasible technique for investigating primary NPC. D was significantly decreased in primary NPC, and increased D* reflected increased blood vessel generation and parenchymal perfusion in primary NPC. KEY POINTS: • Intravoxel incoherent motion (IVIM) analysis permits separate quantification of diffusion and perfusion. • IVIM DWI is a feasible technique for investigating primary NPC. • IVIM suggests that primary NPC tissue voxels exhibit both perfusion and diffusion.

Safety and diagnostic image quality of iopromide: results of a large non-interventional observational study of European and Asian patients (IMAGE).

BACKGROUND: Iodine-based contrast agents such as iopromide play a central role in improving the diagnostic quality of imaging modalities using ionizing radiation. PURPOSE: To investigate the safety and diagnostic image quality of iopromide in the routine clinical setting. MATERIAL AND METHODS: This was an international, multicenter, prospective, single-arm, non-interventional study (NIS). The study was performed in out- and inpatients in 738 study centers in 21 countries in Europe and Asia. Iopromide was administered in a routine manner, in compliance with the local package insert. The use of premedication was at the discretion of the attending physician. Case report forms for 44,835 patients were analyzed (57.4% men). The median age of the patients was 55 years. RESULTS: For the vast majority of patients (94.8%), the contrast quality was rated as 'good' (55.8%) or 'excellent' (39.0%). For 1265 (2.8%) patients, there were reports of adverse drug reactions (ADRs) excluding tolerance indicators (TIs) (i.e. injection site warmth, feeling hot, or injection site pain of mild intensity). At least one ADR including TIs was reported in 2415 (5.4%) patients. There were 11 (0.02%) patients with serious ADRs, and no drug-related deaths. Events of injection site warmth and/or feeling hot were reported by 3.5%, nausea and/or vomiting by 0.96%, and urticaria, erythema, and/or rash by 0.54% of patients. Patients at risk for an acute idiosyncratic reaction (i.e. patients with a history of bronchial asthma, allergies, and/or contrast media reaction) had a higher incidence of ADRs compared with the overall study population. At-risk patients who did not receive premedication reported distinctly more ADRs compared with those who received premedication (12.0% versus 5.9%). CONCLUSION: Iopromide was shown to be a well-tolerated contrast agent whose usage resulted in high image quality. No unknown ADRs were observed. Premedication with antiallergy drugs should be considered in at-risk patients.

Low-dose contrast-enhanced magnetic resonance imaging of brain metastases at 3.0 T using high-relaxivity contrast agents.

BACKGROUND: Lesion-to-brain contrast after gadolinium administration is significantly higher at 3.0 Tesla (T) compared to 1.5 T. The high in vivo relaxivity of gadobenate dimeglumine (Gd-BOPTA) may permit the use of lower-dose contrast agents. PURPOSE: To investigate whether low-dose contrast-enhanced MRI at 3.0 T using a high-relaxivity contrast agent (Gd-BOPTA) can achieve a comparable or improved contrast-to-noise ratio (CNR) for the detection of brain metastases compared with examination of the same patient at 1.5 T using a standard dose of gadopentetate dimeglumine (Gd-DTPA). MATERIAL AND METHODS: A total of 18 patients with known brain metastases were first imaged at 1.5 T with 0.1 mmol/kg Gd-DTPA. Patients returned at least 24 hours later for imaging at 3.0 T with Gd-BOPTA at cumulative doses of 0.025 mmol/kg, 0.05 mmol/kg, 0.075 mmol/kg, and 0.1 mmol/kg (0.1 mmol/kg body weight overall). The CNR of enhancing brain lesions compared to the normal contralateral white matter was calculated. For the 3.0 T study using different cumulative doses of Gd-BOPTA, the CNR of lesions was compared with CNR of the same lesions imaged at 1.5 T using 0.1 mmol/kg Gd-DTPA, by using the Wilcoxon matched-pairs signed-rank test. RESULTS: At 1.5 T with 0.1 mmol/kg Gd-DTPA, the mean CNR between enhanced lesions and cerebral white matter was 12.01 +/- 2.53. With 3.0 T imaging using different cumulative doses of Gd-BOPTA, the mean CNRs were 7.19 +/- 4.06, 15.31 +/- 6.37, 25.44 +/- 11.02, and 31.88 +/- 13.21. At 3.0 T with 0.05 mmol/kg Gd-BOPTA, CNR was 1.34-fold higher compared to CNR at 1.5 T with 0.1 mmol/kg Gd-DTPA (P <0.01). CONCLUSION: Comparable contrast enhancement of brain metastases can be achieved with a 0.05-mmol/kg dose of Gd-BOPTA at 3.0 T compared to imaging at 1.5 T using 0.1 mmol/kg Gd-DTPA.