Contrast-enhanced Magnetic Resonance Perfusion Imaging Research Articles

Diagnostic efficacy of dynamic contrast-enhanced magnetic resonance perfusion imaging in detecting local tumor recurrence in patients with head and neck malignancies after definitive treatment.

Accurate interpretation of post-treatment imaging in head and neck malignancies poses a challenge due to treatment sequelae. Magnetic resonance (MR) perfusion helps in this scenario by evaluating the hemodynamic characteristics of lesions. This study aimed to elucidate the diagnostic efficacy of dynamic contrast-enhanced (DCE)-MR perfusion imaging in detecting recurrence in patients after they underwent definitive treatment for head and neck tumors. Thirty patients who had received definitive curative-intent treatment for histopathology-proven malignant head and neck tumors and in whom recurrent tumor was detected on precontrast MR imaging (MRI) were accrued in the study. Patients underwent DCE-MR perfusion imaging. Time to peak (TTP), relative maximum enhancement (RME), and relative washout (RWO) ratio were calculated by using time-intensity curve (TIC). The diagnostic accuracy was compared with histopathology. A cut-off value of ≥125.3 for RME showed a sensitivity of 76.2% and specificity of 66.7% for differentiating post-radiation changes and recurrence. The optimal cut-off for RWO ratio was ≥-6.24 with a sensitivity of 76.2% and specificity of 55.6%. The optimal cut-off of TTP was ≤45.8 s with a sensitivity of 61.9% and specificity of 77.8%. Diagnostic accuracies of RME, RWO, and TTP were 73.3%, 70%, and 66.7%, respectively. DCE-MRI had significant diagnostic accuracy in detecting and differentiating recurrences. TIC analysis of high-temporal resolution DCE-MRI can provide information regarding microcirculation of tumors, and hence can be considered as an imaging modality of choice for assessment of early local tumor recurrence in head and neck tumors.

Comparison of the Efficiency of Conventional Diffusion, Diffusion Tensor Imaging, and Dynamic Susceptibility Contrast-Enhanced Magnetic Resonance Perfusion Imaging in the Evaluation of Liver Fibrosis

Objective: Liver fibrosis is a dynamic, reversible process that can result in liver failure. There has been considerable interest in developing noninvasive methods for diagnosis and staging. To investigate the diffusion and perfusion changes of the fibrotic liver parenchyma with conventional diffusion-weighted imaging (CDI), diffusion tensor imaging (DTI), and T2*weighted dynamic susceptibility contrast-magnetic resonance perfusion imaging (DSC-MRPI) at 3Tesla MR scanner. Methods: Twenty-seven patients with chronic viral hepatitis and 24 volunteers were evaluated, prospectively. The standard MRI protocols of the abdomen, CDI, and DTI were performed. Apparent diffusion coefficient (ADC) maps were obtained, D and FA values were calculated for DTI. Signal Intensity(SI)-time curves were obtained and “blood volume”(BV), “blood flow” (BF), “time to peak”(TTP), “mean transit time”(MTT) were measured. All patients with hepatitis underwent liver biopsy. The efficacy of diffusion and perfusion parameters used in the diagnosis of fibrosis was analyzed with the receiver operating characteristic curve (ROC). Results: Patients had significantly lower liver ADC when compared to the control group, either with CDI and DTI. D values obtained from DTI were lower in patients than those of the normal volunteers, and the difference was statistically significant. On DSC-MRPI; BF, BV, MTT, and TTP of the liver were lower than those of the control group but only BV and MTT values showed statistical significance. Liver ADC, D, and BV values had a negative correlation with fibrosis. Conclusion: The results showed that the D values obtained from DTI, BV, and MTT values obtained from DSC-MRPI can be an efficient diagnostic tool for liver fibrosis in patients with chronic hepatitis.

Brain perfusion alterations in tick-borne encephalitis—preliminary report

BackgroundMagnetic resonance imaging (MRI) changes in tick-borne encephalitis (TBE) are non-specific and the pathophysiological mechanisms leading to their formation remain unclear. This study investigated brain perfusion in TBE patients using dynamic susceptibility-weighted contrast-enhanced magnetic resonance perfusion imaging (DSC-MRI perfusion). MethodsMRI scans were performed for 12 patients in the acute phase, 3–5days after the diagnosis of TBE. Conventional MRI and DSC-MRI perfusion studies were performed. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) parametric maps were created. The bilateral frontal, parietal, and temporal subcortical regions and thalamus were selected as regions of interest. Perfusion parameters of TBE patients were compared to those of a control group. ResultsThere was a slight increase in CBF and CBV, with significant prolongation of TTP in subcortical areas in the study subjects, while MTT values were comparable to those of the control group. A significant increase in thalamic CBF (p<0.001) and increased CBV (p<0.05) were observed. Increased TTP and a slight reduction in MTT were also observed within this area. ConclusionsThe DSC-MRI perfusion study showed that TBE patients had brain perfusion disturbances, expressed mainly in the thalami. These results suggest that DSC-MRI perfusion may provide important information regarding the areas affected in TBE patients.

Diagnosis of perfusion abnormality of the pulmonary artery in Takayasu’s arteritis using contrast-enhanced MR perfusion imaging

To determine the clinical efficacy of contrast-enhanced magnetic resonance (MR) perfusion imaging in the diagnosis of perfusion abnormality in the pulmonary artery (PA) in Takayasu's arteritis (TA). Twenty-one patients were evaluated. Pulmonary MR perfusion images were acquired using a 2-dimensional (2D) fast spoiled gradient echo sequence with single-slice technique (TR/TE, 5.3/1.3; flip angle, 30 degrees; receiver bandwidth, 31.2 kHz/pixel; acquisition time, 0.7 s; and total acquisition time, 49 s). Seventy continuous subtracted MR images were evaluated, and the presence of perfusion abnormality was determined in lobe-based (n=126) and patient-based (n=21) analyses. Sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) were calculated using perfusion scintigraphy as a standard reference. For lobe-based analysis, sensitivity was 91.7-95.8%, specificity was 92.2-93.7%, and PPV and NPV were 73.3-76.7% and 97.9-99.0%, respectively. For patient-based analyses, sensitivity was 100%, specificity was 72.7%, and PPV and NPV were 76.9% and 100%, respectively. Kappa values for each analysis were between 0.78-1.00. In conclusion, MR perfusion imaging appears to be a valuable, noninvasive method to estimate PA involvement in patients with TA.

Contrast media for MR imaging of the heart.

The role of contrast media for quantitative characterization of ischemic myocardial events with magnetic resonance (MR) imaging has advanced considerably in the past few years. Contrast material-enhanced MR imaging is useful for identifying and sizing myocardial infarcts and for distinguishing between occlusive and reperfused myocardial infarcts. Recent results suggest that contrast-enhanced MR imaging can also be used to identify areas of cell death in regions of reperfused myocardial infarction. With the aid of MR contrast media, fast MR imaging techniques may be useful in estimating regional myocardial perfusion. Although no simple relationship between signal intensity and concentration exists, contrast-enhanced MR perfusion imaging can demonstrate the presence and relative severity of hypoperfused myocardium. Combining myocardial perfusion imaging with the anatomic and functional information provided by other MR imaging techniques could make MR imaging a comprehensive noninvasive means of evaluating ischemic cardiac disease.