Dynamic Contrast-enhanced Material-enhanced Magnetic Resonance Imaging Research Articles

Effect of Radiofrequency Transmit Field Correction on Quantitative Dynamic Contrast-enhanced MR Imaging of the Breast at 3.0 T.

To investigate the effects of radiofrequency transmit field (B1(+)) correction on (a) the measured T1 relaxation times of normal breast tissue and malignant lesions and (b) the pharmacokinetically derived parameters of malignant breast lesions at 3 T. Ethics approval and informed consent were obtained. Between May 2013 and January 2014, 30 women (median age, 58 years; range, 32-83 years) with invasive ductal carcinoma of at least 10 mm were recruited to undergo dynamic contrast material-enhanced magnetic resonance (MR) imaging before surgery. B1(+) and T1 mapping sequences were performed to determine the effect of B1(+) correction on the native tissue relaxation time (T10) of fat, parenchyma, and malignant lesions in both breasts. Pharmacokinetic parameters were calculated before and after correction for B1(+) variations. Results were correlated with histologic grade by using the Kruskal-Wallis test. Measurements showed a mean 37% flip angle difference between the right and left breast, which resulted in a 61% T10 difference in fat and a 41.5% difference in parenchyma between the two breasts. The T1 of lesions in the right breast increased by 58%, whereas that of lesions in the left breast decreased by 30% after B1(+) correction. The whole-tumor transendothelial permeability across the vascular compartment(K(trans)) of lesions in the right breast decreased by 41%, and that of lesions in the left breast increased by 46% after correction. A systematic increase in K(trans) was observed, with significant differences found across the histologic grades (P < .001). The effect size of B1(+) correction on K(trans) calculation was large for lesions in the right breast and moderate for lesions in the left breast (Cohen effect size, d = 0.86 and d = 0.59, respectively). B1(+) correction demonstrates a substantial effect on the results of quantitative dynamic contrast-enhanced analysis of breast tissue at 3 T, which propagates into the pharmacokinetic analysis of tumors that is dependent on whether the tumor is located in the right or left breast.

Improving the Accuracy of Computer-aided Diagnosis for Breast MR Imaging by Differentiating between Mass and Nonmass Lesions.

To determine suitable features and optimal classifier design for a computer-aided diagnosis (CAD) system to differentiate among mass and nonmass enhancements during dynamic contrast material-enhanced magnetic resonance (MR) imaging of the breast. Two hundred eighty histologically proved mass lesions and 129 histologically proved nonmass lesions from MR imaging studies were retrospectively collected. The institutional research ethics board approved this study and waived informed consent. Breast Imaging Reporting and Data System classification of mass and nonmass enhancement was obtained from radiologic reports. Image data from dynamic contrast-enhanced MR imaging were extracted and analyzed by using feature selection techniques and binary, multiclass, and cascade classifiers. Performance was assessed by measuring the area under the receiver operating characteristics curve (AUC), sensitivity, and specificity. Bootstrap cross validation was used to predict the best classifier for the classification task of mass and nonmass benign and malignant breast lesions. A total of 176 features were extracted. Feature relevance ranking indicated unequal importance of kinetic, texture, and morphologic features for mass and nonmass lesions. The best classifier performance was a two-stage cascade classifier (mass vs nonmass followed by malignant vs benign classification) (AUC, 0.91; 95% confidence interval (CI): 0.88, 0.94) compared with one-shot classifier (ie, all benign vs malignant classification) (AUC, 0.89; 95% CI: 0.85, 0.92). The AUC was 2% higher for cascade (median percent difference obtained by using paired bootstrapped samples) and was significant (P = .0027). Our proposed two-stage cascade classifier decreases the overall misclassification rate by 12%, with 72 of 409 missed diagnoses with cascade versus 82 of 409 missed diagnoses with one-shot classifier. Separately optimizing feature selection and training classifiers for mass and nonmass lesions improves the accuracy of CAD for breast MR imaging. By cascading classifiers, we achieved a significant improvement in performance with respect to the use of a one-shot classifier. Our cascaded classifier may provide an advantage for screening women at high risk for breast cancer, in whom the ability to diagnose cancers at an early stage is of primary importance.

The Diagnostic Performance of Dynamic Contrast-enhanced MR Imaging for Detection of Small Hepatocellular Carcinoma Measuring Up to 2 cm: A Meta-Analysis.

To determine the performance of dynamic contrast material-enhanced magnetic resonance (MR) imaging in the diagnosis of small (≤2-cm) hepatocellular carcinoma (HCC) and to identify factors that influence this performance. Medline and Embase databases were searched for studies performed from January 2000 to March 2014 in which the performance of MR imaging was reported for the detection of HCC up to 2 cm on either a lesion- or patient-based level, with sufficient data to construct 2 × 2 contingency tables. Diagnostic performance was quantitatively pooled for all studies by using a bivariate random-effects model with exploration involving subgroup analysis, meta-regression, and determination of study heterogeneity. Twenty-two studies with 1387 small HCC lesions in 1908 patients met inclusion criteria. Heterogeneity was higher for sensitivity (range, 30%-99%) than specificity (range, 61%-100%). Overall sensitivity was 78% (95% confidence interval [CI]: 68%, 85%; I(2) = 89%), and overall specificity was 92% (95% CI: 88%, 95%; I(2) = 69%). The primary potential source of bias was use of explant as the reference standard in only 13% of studies, although lower sensitivity in such studies was not significant (59% vs 80%, P = .165). Sensitivities were significantly higher for studies that originated from Asia compared with those that originated elsewhere (89% vs 71%, P = .028), those performed with hepatobiliary phase imaging compared with those without (87% vs 65%, respectively; P = .004), and those in which gadoxetate disodium was used versus an extracellular agent (92% vs 67%, P ≤ .001). Specificity was not significantly different between subgroups (P ≥ .122). At pairwise meta-regression analysis with either study origin from Asia or performance of hepatobiliary phase imaging, only gadoxetate disodium contrast agent showed significant independent association with higher sensitivity (P = .002-.007). Results of this meta-analysis suggest that dynamic contrast-enhanced MR imaging has moderate sensitivity and excellent specificity in the detection of HCC up to 2 cm. Gadoxetate disodium contrast agent showed the strongest association with increased sensitivity.

Association between Parenchymal Enhancement of the Contralateral Breast in Dynamic Contrast-enhanced MR Imaging and Outcome of Patients with Unilateral Invasive Breast Cancer.

To retrospectively investigate whether parenchymal enhancement in dynamic contrast material-enhanced magnetic resonance (MR) imaging of the contralateral breast in patients with unilateral invasive breast cancer is associated with therapy outcome. After obtaining approval of the institutional review board and patients' written informed consent, 531 women with unilateral invasive breast cancer underwent dynamic contrast-enhanced MR imaging between 2000 and 2008. The contralateral parenchyma was segmented automatically, in which the mean of the top 10% late enhancement was calculated. Cox regression was used to test associations between parenchymal enhancement, patient and tumor characteristics, and overall survival and invasive disease-free survival. Subset analyses were performed and stratified according to immunohistochemical subtypes and type of adjuvant treatment received. Median follow-up was 86 months. Age (P < .001) and immunohistochemical subtype (P = .042) retained significance in multivariate analysis for overall survival. In patients with estrogen receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer (n = 398), age (P < .001), largest diameter on MR images (P = .049), and parenchymal enhancement (P = .011) were significant. In patients who underwent endocrine therapy (n = 174), parenchymal enhancement was the only significant covariate for overall survival and invasive disease-free survival (P < .001). Results suggest that parenchymal enhancement in the contralateral breast of patients with invasive unilateral breast cancer is significantly associated with long-term outcome, particularly in patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Lower value of the mean top 10% enhancement of the parenchyma shows potential as a predictive biomarker for relatively poor outcome in patients who undergo endocrine therapy. These results should, however, be validated in a larger study.

Pattern Analysis of Dynamic Susceptibility Contrast-enhanced MR Imaging Demonstrates Peritumoral Tissue Heterogeneity

To augment the analysis of dynamic susceptibility contrast material-enhanced magnetic resonance (MR) images to uncover unique tissue characteristics that could potentially facilitate treatment planning through a better understanding of the peritumoral region in patients with glioblastoma. Institutional review board approval was obtained for this study, with waiver of informed consent for retrospective review of medical records. Dynamic susceptibility contrast-enhanced MR imaging data were obtained for 79 patients, and principal component analysis was applied to the perfusion signal intensity. The first six principal components were sufficient to characterize more than 99% of variance in the temporal dynamics of blood perfusion in all regions of interest. The principal components were subsequently used in conjunction with a support vector machine classifier to create a map of heterogeneity within the peritumoral region, and the variance of this map served as the heterogeneity score. The calculated principal components allowed near-perfect separability of tissue that was likely highly infiltrated with tumor and tissue that was unlikely infiltrated with tumor. The heterogeneity map created by using the principal components showed a clear relationship between voxels judged by the support vector machine to be highly infiltrated and subsequent recurrence. The results demonstrated a significant correlation (r = 0.46, P < .0001) between the heterogeneity score and patient survival. The hazard ratio was 2.23 (95% confidence interval: 1.4, 3.6; P < .01) between patients with high and low heterogeneity scores on the basis of the median heterogeneity score. Analysis of dynamic susceptibility contrast-enhanced MR imaging data by using principal component analysis can help identify imaging variables that can be subsequently used to evaluate the peritumoral region in glioblastoma. These variables are potentially indicative of tumor infiltration and may become useful tools in guiding therapy, as well as individualized prognostication.

Background Parenchymal Signal Enhancement Ratio at Preoperative MR Imaging: Association with Subsequent Local Recurrence in Patients with Ductal Carcinoma in Situ after Breast Conservation Surgery

To retrospectively investigate whether the background parenchymal features around a tumor at preoperative dynamic contrast material-enhanced magnetic resonance (MR) imaging are associated with ipsilateral breast tumor recurrence (IBTR)-free survival in patients with ductal carcinoma in situ (DCIS) after breast conservation surgery. The institutional review board approved this study, and the requirement for informed consent was waived. Between 2004 and 2009, 215 consecutive women with pure DCIS who had undergone preoperative dynamic contrast-enhanced MR imaging and curative breast conservation surgery were identified. Clinical-pathologic features (age, menopausal status, presentation of clinical findings, biopsy method, tumor size, nuclear grade, hormonal receptor status, margin status, and adjuvant therapy) and MR imaging features (lesion size, background parenchymal enhancement grade, fibroglandular density, parenchymal signal enhancement ratio [SER] around the tumor, lesion type, and lesion kinetics) were analyzed. A Cox proportional hazards model was used to determine the association between MR imaging variables and IBTR-free survival after controlling for clinical-pathologic variables. Reproducibility of SER measurements was evaluated by using the intraclass correlation coefficient. There were 15 of 215 (7.0%) IBTR cases (nine DCIS cases and six invasive cases) at a median of 36 months (range, 11-61 months). Multivariate analysis showed that higher parenchymal SER (hazard ratio [HR] = 2.028, P < .001 for reader 1; HR = 1.652, P < .001 for reader 2) and larger histologic tumor size (HR = 1.360, P = .009 for reader 1; HR = 1.402, P = .006 for reader 2) were independent factors associated with worse IBTR-free survival. The intraclass correlation coefficient of SER measurements between two readers was 0.852 (95% confidence interval: 0.811, 0.885). Higher parenchymal SER around the tumor at preoperative dynamic contrast-enhanced MR imaging and larger histologic tumor size were independent factors associated with worse IBTR-free survival in patients with DCIS after breast conservation surgery.

Recurrent Glioblastoma: Optimum Area under the Curve Method Derived from Dynamic Contrast-enhanced T1-weighted Perfusion MR Imaging

To determine whether the ratio of the initial area under the time-signal intensity curve (AUC) (IAUC) to the final AUC--or AUCR--derived from dynamic contrast material-enhanced magnetic resonance (MR) imaging can be an imaging biomarker for distinguishing recurrent glioblastoma multiforme (GBM) from radiation necrosis and to compare the diagnostic accuracy of the AUCR with commonly used model-free dynamic contrast-enhanced MR imaging parameters. The institutional review board approved this retrospective study and waived the informed consent requirement. Fifty-seven consecutive patients with pathologically confirmed recurrent GBM (n = 32) or radiation necrosis (n = 25) underwent dynamic contrast-enhanced MR imaging. Histogram parameters of the IAUC at 30, 60, and 120 seconds and the AUCR, which included the mean value at the higher curve of the bimodal histogram (mAUCR(H)), as well as 90th percentile cumulative histogram cutoffs, were calculated and were correlated with final pathologic findings. The best predictor for differentiating recurrent GBM from radiation necrosis was determined by means of receiver operating characteristic (ROC) curve analysis. The demographic data were not significantly different between the two patient groups. There were statistically significant differences in all of the IAUC and AUCR parameters between the recurrent GBM and the radiation necrosis patient groups (P < .05 for each). ROC curve analyses showed mAUCR(H) to be the best single predictor of recurrent GBM (mAUCR(H) for recurrent GBM = 0.35 ± 0.11 [standard deviation], vs 0.19 ± 0.17 for radiation necrosis; P < .0001; optimum cutoff, 0.23), with a sensitivity of 93.8% and a specificity of 88.0%. A bimodal histogram analysis of AUCR derived from dynamic contrast-enhanced MR imaging can be a potential noninvasive imaging biomarker for differentiating recurrent GBM from radiation necrosis. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130016/-/DC1.

Dynamic Contrast-enhanced MR Imaging of Carotid Atherosclerotic Plaque: Model Selection, Reproducibility, and Validation

To compare four known pharmacokinetic models for their ability to describe dynamic contrast material-enhanced magnetic resonance (MR) imaging of carotid atherosclerotic plaques, to determine reproducibility, and to validate the results with histologic findings. The study was approved by the institutional medical ethics committee. Written informed consent was obtained from all patients. Forty-five patients with 30%-99% carotid stenosis underwent dynamic contrast-enhanced MR imaging. Plaque enhancement was measured at 16 time points at approximately 25-second image intervals by using a gadolinium-based contrast material. Pharmacokinetic parameters (volume transfer constant, K(trans); extracellular extravascular volume fraction, v(e); and blood plasma fraction, v(p)) were determined by fitting a two-compartment model to plaque and blood gadolinium concentration curves. The relative fit errors and parameter uncertainties were determined to find the most suitable model. Sixteen patients underwent imaging twice to determine reproducibility. Carotid endarterectomy specimens from 16 patients who were scheduled for surgery were collected for histologic validation. Parameter uncertainties were compared with the Wilcoxon signed rank test. Reproducibility was assessed by using the coefficient of variation. Correlation with histologic findings was evaluated with the Pearson correlation coefficient. The mean relative fit uncertainty (±standard error) for K(trans) was 10% ± 1 with the Patlak model, which was significantly lower than that with the Tofts (20% ± 1), extended Tofts (33% ± 3), and extended graphical (29% ± 3) models (P < .001). The relative uncertainty for v(p) was 20% ± 2 with the Patlak model and was significantly higher with the extended Tofts (46% ± 9) and extended graphical (35% ± 5) models (P < .001). The reproducibility (coefficient of variation) for the Patlak model was 16% for K(trans) and 26% for v(p). Significant positive correlations were found between K(trans) and the endothelial microvessel content determined on histologic slices (Pearson ρ = 0.72, P = .005). The Patlak model is most suited for describing carotid plaque enhancement. Correlation with histologic findings validated K(trans) as an indicator of plaque microvasculature, and the reproducibility of K(trans) was good.

Use of Dynamic Contrast-enhanced MR Imaging to Predict Survival in Patients with Primary Breast Cancer Undergoing Neoadjuvant Chemotherapy

To investigate whether early changes in vascular parameters determined with dynamic contrast material-enhanced magnetic resonance (MR) imaging after two cycles of neoadjuvant chemotherapy (NAC) are predictive of disease-free and overall survival in primary breast cancer. Institutional ethics approval and informed consent were obtained. Patients with primary breast cancer (median age, 45 years; age range, 22-70 years) recruited from January 2001 to September 2008 underwent dynamic contrast-enhanced MR imaging before and after two cycles of NAC. Quantitative and semiquantitative kinetic parameters were calculated, including the volume transfer constant (K(trans)) and the initial area under the gadolinium concentration-time curve over 60 seconds (IAUGC(60)). Cut points optimized to the receiver operating characteristic curve were used to dichotomize MR imaging data for Kaplan-Meier survival analysis. MR imaging parameters and known prognostic indicators in primary breast cancer were correlated with disease-free and overall survival by using the Cox proportional hazards model for univariate and multivariate analyses. MR imaging was performed before (n = 62) and after (n = 58) two cycles of NAC. The median follow-up time was 43.9 months for disease-free survival and 60.3 months for overall survival. There were 28 recurrences; 26 patients had distant metastases (two had additional local recurrence) and two had local recurrence only. There were 20 deaths, all of which were related to breast cancer. At univariate analysis, progesterone receptor status, the type of surgery performed, higher posttreatment K(trans) (P = .048), and larger posttreatment IAUGC(60) (P = .035) were significant predictors of worse disease-free survival. At multivariate analysis, progesterone receptor status (P = .002) and mean transit time (P = .025) were significant predictors of disease-free survival. Univariate analysis showed that clinical tumor stage (P = .005), progesterone receptor status (P = .025), and type of surgery performed (P = .017) were significant predictors of overall survival. Higher posttreatment K(trans) (P = .043), larger IAUGC(60) (P = .029), and larger tumor size at posttreatment MR imaging were predictive of worse overall survival (P = .018). Of these variables, K(trans) remained an independent indicator of overall survival (P = .038). Higher posttreatment tumor vascularization as depicted with dynamic contrast-enhanced MR imaging may be associated with higher recurrence and lower survival rates. Dynamic contrast-enhanced MR imaging parameters, in conjunction with traditional prognostic factors, have the potential to be prognostic biomarkers for disease-free and overall survival in primary breast cancer.

Celiac Disease: Evaluation with Dynamic Contrast-enhanced MR Imaging

To prospectively determine mural perfusion dynamics in patients with untreated celiac disease by using dynamic contrast material-enhanced magnetic resonance (MR) imaging and to compare these dynamics with those in a control population and in patients with celiac disease treated with a gluten-free diet. Institutional review board approval and informed consent from all participants were obtained. Sixty consecutive patients with untreated celiac disease, 45 patients with celiac disease treated with a gluten-free diet for at least 1 year, and 30 control subjects were enrolled in this study. Dynamic contrast-enhanced MR imaging was performed by using a 1.5-T MR unit. For each MR imaging examination, maximum enhancement, slope of enhancement, and time-signal intensity curves were calculated at the level of the descending duodenal wall. Duodenal wall thickness was also evaluated. Statistical evaluation was performed by using one-way analysis of variance, and the results were confirmed by using the Bartlett test for equal variances and complemented by using Bonferroni multiple comparison, linear correlation, and the Student t test for paired data. Mean maximum enhancement of the duodenal wall was significantly higher in patients with untreated celiac disease (229.1 +/- 46.4 [standard deviation]) than in patients with treated celiac disease (109.8 +/- 27.8) and control subjects (94.7 +/- 17.9) (P < .001 for each comparison). All 60 untreated patients showed a curve characterized by fast enhancement and washout (type 4), while all 45 treated patients and the 30 control subjects showed a curve characterized by slow constant enhancement (type 2). Mean duodenal wall thickness was not significantly different between untreated patients (2.2 mm +/- 0.4), treated patients (2.0 mm +/- 0.3), and control subjects (2.0 mm +/- 0.4) (one-way analysis of variance, P = .4177; Bartlett test, P = .6951). The results of this study suggest that dynamic evaluation of the bowel wall by using contrast-enhanced MR imaging can be an effective and reproducible way to show the inflammation state in celiac disease.

Pancreatic Cancer: Utility of Dynamic Contrast-enhanced MR Imaging in Assessment of Antiangiogenic Therapy

To prospectively evaluate the utility of dynamic contrast material-enhanced magnetic resonance (MR) imaging in predicting the response of locally advanced pancreatic cancer to combined chemotherapy and antiangiogenic therapy. This prospective, institutional review board-approved, HIPAA-compliant study with informed consent assessed dynamic contrast-enhanced MR imaging in 11 patients (mean age, 54.3 years; six men and five women) with locally invasive pancreatic cancer before and 28 days after combined chemotherapy and antiangiogenic therapy. Axial perfusion images were obtained after injection of 0.1 mmol gadopentetate dimeglumine per kilogram of body weight. Sagittal images of the upper abdominal aorta were obtained for arterial input function calculation. A two-compartment kinetic model was used to calculate the perfusion parameters K(trans) (the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space), K(ep) (the rate constant that represents transfer of contrast agent from the extravascular extracellular space to the blood plasma), and volume of distribution (v(e)). Semiquantitative measurements, peak tissue gadolinium concentration (C(peak)), maximum slope of gadolinium increase (slope), and area under the gadolinium curve at 60 seconds (AUC(60)) were also calculated. Perfusion parameters and tumor size changes were correlated with carbohydrate antigen 19-9 levels. Comparisons between pre- and posttreatment studies were performed by using the Wilcoxon signed rank test, and comparisons between responders and nonresponders were performed by using the Mann-Whitney test. After therapy, K(trans), v(e), C(peak), slope, and AUC(60) decreased significantly (P = .02, .001, .002, .007, and .01, respectively). Tumor size and K(ep) were not significantly changed. Pretreatment K(trans) and K(ep) were significantly higher (P = .02 and .006, respectively) in tumors that showed marker response than in those that did not. A pretreatment K(trans) value (milliliters of blood per milliliter of tissue times minutes) of more than 0.78 mL/mL . min was 100% sensitive and 71% specific for subsequent tumor response. Semiquantative parameters and tumor size were not different between the groups. Pretreatment K(trans) measurement in pancreatic tumors can predict response to antiangiogenic therapy. All perfusion parameters showed substantial reduction after 28 days of combined chemotherapy and antiangiogenic therapy.

Multiple Myeloma Treatment Response Assessment with Whole-Body Dynamic Contrast-enhanced MR Imaging

To compare posttreatment bone marrow changes at whole-body dynamic contrast material-enhanced magnetic resonance (MR) imaging with clinical response in patients with multiple myeloma (MM) and to determine if this technique can be used to assess treatment response in patients with MM. This study was approved by an institutional review board; all patients gave informed written consent. Thirty patients (21 men, nine women; mean age, 58 years +/- 10 [standard deviation]) underwent whole-body dynamic contrast-enhanced MR imaging before treatment, after induction chemotherapy (n = 30), and after autologous stem cell transplantation (ASCT) (n = 20). Maximal percentages of bone marrow (BME(max)) and focal lesion (FLE(max)) enhancement were assessed at each MR imaging examination. Clinical responses were determined on the basis of international uniform response criteria. Posttreatment changes in BME(max)and FLE(max)were compared with clinical response to therapy by using the Mann-Whitney U test. Receiver operating characteristic (ROC) analysis of posttreatment BME(max)was used to identify poor responders. Eleven of 30 patients were good responders to induction chemotherapy; 16 of 20 patients were good responders to ASCT. After induction chemotherapy, mean BME(max)differed between good and poor responders (94.3% vs 138.4%, respectively; P = .02). With the exclusion of results from six examinations with focal lesions in which a poor clinical response was classified but BME(max)had normalized, a posttreatment BME(max)of more than 96.8% had 100% sensitivity for the identification of poor responders (specificity, 76.9%; area under the ROC curve, 0.90; P = .0001). Mean FLE(max)after induction chemotherapy did not differ between good and poor responders. Mean timing (ie, the number of postcontrast dynamic acquisitions where FLE(max)was observed) was significantly delayed in good responders compared with poor responders (4.7 vs 2.9, P < .0001). Post-ASCT MR imaging results correctly depicted all four clinically good responders whose disease subsequently progressed. With quantitative analysis of BME(max)and the timing of FLE(max), whole-body dynamic contrast-enhanced MR imaging can be used to assess treatment response in patients with MM.

Rheumatoid Synovial Inflammation: Pixel-by-Pixel Dynamic Contrast-enhanced MR Imaging Time-Intensity Curve Shape Analysis—A Feasibility Study

To analyze the distribution of different shapes of time-intensity curves (TICs) in synovial tissue of patients with rheumatoid arthritis (RA) and to compare relative numbers of TIC shapes between patients with RA and healthy control subjects. This prospective study was approved by the institutional review board; patients and control subjects gave written informed consent. Dynamic contrast material-enhanced magnetic resonance (MR) imaging of the knee joint in five patients with early RA and in five control subjects was performed. Parametric maps showing seven TIC shape types were created. Spatial information of the synovial TIC shape distribution pattern and relative number of TIC shapes were calculated on a three-dimensional region of interest. Relative TIC shape numbers were compared by using a nonparametric Mann-Whitney U test. Synovial enhancement in patients with RA consisted of type 2 TIC shapes (slow enhancement) with heterogeneous zones of types 3 (fast enhancement followed by plateau phase), 4 (fast enhancement followed by early washout phase), and 5 (fast enhancement followed by slow enhancement increase) TIC shapes, compared with almost only type 2 TIC shapes in control subjects. The heterogeneous zones were seen in the lateral and medial knee compartments and around the cruciate ligaments. A significantly higher relative number of type 4 TIC shapes was observed in the patient group compared with the control group (16.5% vs 6.9%, P = .008). The pixel-by-pixel dynamic contrast-enhanced MR imaging TIC shape analysis may help distinguish patients with RA from control subjects on the basis of the relative number of type 4 TIC shapes. This study provides the rationale for future research to evaluate the utility of this approach in clinical practice.

Patients with Plasma Cell Disorders Examined at Whole-Body Dynamic Contrast-enhanced MR Imaging: Initial Experience

This study was approved by the institutional review board, and informed consent was obtained from all subjects. The authors prospectively evaluated the feasibility of multistation whole-body dynamic contrast material-enhanced magnetic resonance (MR) imaging performed in patients with plasma cell disorders to assess disease extension and the time-signal intensity curves of diffuse and focal bone marrow infiltration. Three healthy adult male volunteers (age range, 29-31 years) and 21 patients (12 men, nine women; age range, 34-79 years) underwent whole-body dynamic unenhanced (volunteers) and contrast-enhanced MR imaging, which was performed by using an 18-channel 1.5-T MR system. A five-station (three sagittal and two coronal planes) fat-saturated three-dimensional gradient-echo sequence (3.3-3.6/1.3 [repetition time msec/echo time msec], 20 degrees flip angle, voxel size of 2 x 2.6 x [3-5] mm) was performed seven times. The temporal resolution of the five-station dynamic contrast-enhanced examination was 60 seconds with use of parallel imaging. Time-signal intensity curves for the bone marrow and the focal lesions were successfully obtained in all patients. http://radiology.rsnajnls.org/cgi/content/full/250/3/905/DC1http://radiology.rsnajnls.org/cgi/content/full/250/3/905/DC2http://radiology.rsnajnls.org/cgi/content/full/250/3/905/DC3.

Hepatic Metastases: In Vivo Assessment of Perfusion Parameters at Dynamic Contrast-enhanced MR Imaging with Dual-Input Two-Compartment Tracer Kinetics Model

This study was institutional review board approved, with waived patient consent for retrospective analysis of the data. The hepatic perfusion at dynamic contrast material-enhanced magnetic resonance (MR) imaging was commonly described and assessed by using a dual-input one-compartment tracer kinetics model. Although the tracer kinetics in normal liver parenchyma can be described by using a single compartment, functional changes in the tumor microenvironment can result in distinctly different tracer behavior that entails a second tissue compartment. A dual-input two-compartment model is proposed to describe the tracer behavior in hepatic metastases. The authors applied this model to the dynamic MR imaging data obtained in three patients. Perfusion parameter maps and region-of-interest analysis revealed that tracer behavior in hepatic metastases-in contrast to that in surrounding normal liver tissue, which effectively involves one compartment-can be described by using two compartments.

Epithelial Ovarian Tumors: Value of Dynamic Contrast-enhanced MR Imaging and Correlation with Tumor Angiogenesis

To retrospectively evaluate the diagnostic performance of dynamic contrast material-enhanced magnetic resonance (MR) imaging for the characterization of ovarian epithelial tumors, by using histologic findings as the reference standard, and to correlate dynamic contrast-enhanced MR imaging findings with angiogenesis biomarkers. Ethics committee approval was obtained, with waiver of informed consent. Patients consented to having their data used for future retrospective research. Forty-one women (age range, 22-73 years) with 48 epithelial ovarian tumors underwent dynamic contrast-enhanced MR imaging before surgical excision. In case of bilateral tumors (n = 7), only the most complex tumor was analyzed. Thus, 41 tumors (12 benign, 13 borderline, and 16 invasive) were examined with dynamic contrast-enhanced MR imaging and immunohistochemical methods. Dynamic contrast-enhanced MR imaging parameters (enhancement amplitude [EA], time of half rising [T(max)], and maximal slope [MS]) were analyzed according to histopathologic findings, microvessel density, pericyte coverage index (PCI), and vascular endothelial growth factor receptor 2 (VEGFR-2) expression. Statistical analyses were performed by using Kruskal-Wallis, Fisher exact, and Spearman tests and receiver operating curve analysis. EA was higher for invasive tumors than for benign (P < .001) and borderline (P < .05) tumors. T(max) was longer for benign tumors than for borderline (P < .05) and invasive (P < .01) tumors. MS was steeper for invasive tumors than for benign (P < .001) and borderline (P < .001) tumors. PCI was lower in invasive tumors than in borderline (P < .05) and benign (P < .05) tumors. Microvessels showed stronger immunohistochemical VEGFR-2 expression in invasive tumors than in benign or borderline tumors (P < .05). MS correlated with a lower PCI (r = -0.34, P = .04) and stronger VEGFR-2 expression by using both epithelial (r = 0.41, P < .01) and endothelial (r = 0.66, P < .001) cells. The early enhancement patterns of ovarian epithelial tumors on dynamic contrast-enhanced MR images can help distinguish among benign, borderline, and invasive tumors and were found to correlate with tumoral angiogenic status.

Pancreatic Perfusion: Noninvasive Quantitative Assessment with Dynamic Contrast-enhanced MR Imaging without and with Secretin Stimulation in Healthy Volunteers—Initial Results

To prospectively quantify pancreatic regional perfusion with dynamic contrast material-enhanced magnetic resonance (MR) imaging by using a one-compartment model and to assess perfusion changes during secretin stimulation in healthy volunteers. The study had institutional review board approval, and written informed consent was obtained. Ten healthy volunteers (five men, five women; mean age, 24.7 years +/- 1.9 [standard deviation]; range, 22-29 years) underwent MR imaging pancreatic perfusion studies performed twice without secretin and twice during secretin stimulation. Dynamic contrast-enhanced MR imaging consisted of saturation-recovery T1-weighted turbo-field-echo imaging with peripheral pulse triggering and respiratory tracking. A dose of 0.05 mmol gadodiamide per kilogram of body weight was injected at a rate of 3.5 mL/sec. Regional perfusion parameters were fitted with a one-compartment model. The analysis of variance test for repeated measurements was used to assess differences in pancreatic perfusion without and that with secretin administration. Significant differences in perfusion parameters between the three pancreatic regions were observed (P < .05). During secretin stimulation, a significant difference was observed only between the body and the tail of the pancreas (P = .02). A significant increase (P = .003) in pancreatic perfusion was observed after secretin administration. Mean pancreatic perfusion was 184 mL/min/100 g of tissue +/- 71, 207 mL/min/100 g +/- 77, and 230 mL/min/100 g +/- 87 without secretin and 342 mL/min/100 g +/- 154, 338 mL/min/100 g +/- 156, and 373 mL/min/100 g +/- 176 after secretin stimulation in the head, body, and tail of the pancreas, respectively. Intraindividual variability was 21% without secretin stimulation and 46% with secretin stimulation. Dynamic contrast-enhanced MR imaging enables noninvasive quantification of regional pancreatic perfusion in resting conditions and demonstrates the increase in pancreatic perfusion during secretin stimulation in healthy subjects.

Glandular Function in Sjögren Syndrome: Assessment with Dynamic Contrast-enhanced MR Imaging and Tracer Kinetic Modeling—Initial Experience

To prospectively use dynamic contrast material-enhanced magnetic resonance (MR) imaging and a tracer kinetic model to compare parotid gland microvascular characteristics in patients who have Sjögren syndrome (SS) with those in healthy volunteers. The local research ethics committee approved the study, and written informed consent was obtained from all participants. Twenty-one patients (19 women, two men; age range, 31-73 years) with a diagnosis of SS and 11 healthy volunteers (10 women, one man; age range, 41-68 years) underwent three-dimensional T1-weighted dynamic contrast-enhanced MR imaging of the parotid gland at 1.5 T. A voxel-wise tracer kinetic model and a model-free analysis were applied to the dynamic MR data. Parameter medians and standard deviations were computed to summarize gland microvascular characteristics and gland heterogeneity, respectively. Differences were investigated by using multivariate analysis of variance, t, or U tests. Further investigation was performed by using linear discriminant and receiver operating characteristic analyses. Compared with the healthy volunteers, the patients with SS had highly significant elevations (P << .001) in the model-free parameter initial area under the curve and in tracer kinetic model parameters, including transcapillary contrast agent transfer constant (P < .001) and extracellular extravascular volume (P < .001). Gland heterogeneity was significantly greater (P < .001) in the patients with SS. Parameter medians and standard deviations enabled excellent differentiation (areas under receiver operating characteristic curve, 0.96 and 1.00, respectively) between the patients with SS and the healthy volunteers. Dynamic contrast-enhanced MR imaging has the potential to be used in clinical settings to quantify microvascular function in SS and to differentiate between patients with and those without SS.

Prostate Cancer: Accurate Determination of Extracapsular Extension with High-Spatial-Resolution Dynamic Contrast-enhanced and T2-weighted MR Imaging—Initial Results

To prospectively compare the sensitivity and specificity of high-spatial-resolution dynamic contrast material-enhanced magnetic resonance (MR) imaging with those of high-spatial-resolution T2-weighted MR imaging, performed with an endorectal coil (ERC), for assessment of extracapsular extension (ECE) and staging in patients with prostate cancer, with histopathologic findings as reference. The study was approved by the institutional internal review board; a signed informed consent was obtained. MR imaging of the prostate at 1.5 T was performed with combined surface coils and ERCs in 32 patients (mean age, 65 years; range, 42-78 years) before radical prostatectomy. High-spatial-resolution T2-weighted fast spin-echo and high-spatial-resolution dynamic contrast-enhanced three-dimensional gradient-echo images were acquired with gadopentetate dimeglumine. Dynamic contrast-enhanced MR images were analyzed with a computer-generated color-coded scheme. Two experienced readers independently assessed ECE and tumor stage. MR imaging-based staging results were compared with histopathologic results. For the prediction of ECE, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Staging accuracy was determined with the area under the receiver operating characteristic curve (AUC) by using the Wilcoxon-Mann-Whitney index of diagnostic accuracy. The mean sensitivity, specificity, PPV, and NPV for assessment of ECE with the combined data sets for both readers were 86%, 95%, 90%, and 93%, respectively. The sensitivity of MR images for determination of ECE was significantly improved for both readers (>25%) with combined data sets compared with T2-weighted MR images alone. The combined data sets had a mean overall staging accuracy for both readers of 95%, as determined with AUC. Staging results for both readers were significantly improved (P<.05) with the combined data sets compared with T2-weighted MR images alone. The combination of high-spatial-resolution dynamic contrast-enhanced MR imaging and T2-weighted MR imaging yields improved assessment of ECE and better results for prostate cancer staging compared with either technique independently.

Gadopentetate Dimeglumine and FDG Uptake in Liver Metastases of Colorectal Carcinoma as Determined with MR Imaging and PET

To examine the in vivo relationship between fluorine 18 fluorodeoxyglucose (FDG) uptake, as measured with positron emission tomography (PET), and functional tumor vasculature, as measured with dynamic contrast material-enhanced magnetic resonance (MR) imaging, in patients with liver metastases of colorectal cancer. All patients provided written informed consent, and the study was approved by the institutional review board. A total of 26 patients (12 men and 14 women; mean age, 59 years) who were suspected of having liver metastases of histologically proved colorectal cancer and underwent work-up for liver metastasectomy were included. Patients underwent whole-body FDG PET, and tumor-to-nontumor ratio of FDG uptake in metastases was calculated. Dynamic contrast-enhanced MR imaging was performed, and the rate constant k(ep) (s(-1)) of gadopentetate dimeglumine uptake in metastases was determined. Pimonidazole was used to determine tumor hypoxia and vascular density of metastases. To assess the relationship between FDG uptake, rate constant k(ep) of gadopentetate dimeglumine uptake, hypoxic fraction, and vascular density, the Pearson correlation coefficient was calculated. Negative correlation between tumor-to-nontumor ratio of FDG uptake and rate constant k(ep) was observed (r = -0.421, P = .082). No correlation between tumor hypoxia and tumor-to-nontumor ratio of FDG uptake or rate constant k(ep) was found. A positive correlation was observed between vascular density and rate constant k(ep) (r = 0.458, P = .034) but not between tumor-to-nontumor ratio of FDG uptake. Negative correlation between tumor-to-nontumor ratio of FDG uptake and rate constant k(ep) suggests that lower values of gadopentetate dimeglumine uptake imply an acutely reduced supply of oxygen, which necessitates a higher uptake of glucose to maintain tumor energy levels. The positive correlation of vascular density with rate constant k(ep), but not with tumor-to-nontumor ratio of FDG uptake, emphasizes the potential of dynamic contrast-enhanced MR imaging to enable measurement of tumor vascularity in vivo and its additional value compared with ex vivo methods.