Prediction of radiosensitivity in primary central nervous system germ cell tumors using dynamic contrast-enhanced magnetic resonance imaging

Objective： To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging（DCEMRI） for predicting tumor response to radiotherapy in patients with suspected primary central nervous system（CNS） germ cell tumors（GCTs）.Methods： DCE-MRI parameters of 35 patients with suspected primary CNS GCTs were obtained prior to diagnostic radiation, using the Tofts and Kermode model. Radiosensitivity was determined in tumors diagnosed 2 weeks after radiation by observing changes in tumor size and markers as a response to MRI. Taking radiosensitivity as the gold standard, the cut-off value of DCE-MRI parameters was measured by receiver operating characteristic（ROC） curve. Diagnostic accuracy of DCE-MRI parameters for predicting radiosensitivity was evaluated by ROC curve.Results： A significant elevation in transfer constant（K^trans） and extravascular extracellular space（Ve）（P=0.000）, as well as a significant reduction in rate constant（Kep）（P=0.000） was observed in tumors. K^trans, relative K^trans, and relative Kep of the responsive group were significantly higher than non-responsive groups. No significant difference was found in Kep, Ve, and relative Ve between the two groups. Relative K^trans showed the best diagnostic value in predicting radiosensitivity with a sensitivity of 100%, specificity of 91.7%, positive predictive value（PPV） of 95.8%, and negative predictive value（NPV） of 100%.Conclusions： Relative K^trans appeared promising in predicting tumor response to radiation therapy（RT）. It is implied that DCE-MRI pre-treatment is a requisite step in diagnostic procedures and a novel and reliable approach to guide clinical choice of RT.

Assessment of Changes in the Cesarean Scar and Uterus Between One and Two Years after Cesarean Section Using 3D T2w SPACE MRI

Objective Io evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution,three dimensional T2-weighted sampling perfection with application optimized contrast using diflerent flip angle evolutions Magnetic Resonance Imaging(3DT2w SPACE MRI).Methods This prospective study was performed to investigate morphological changes in the cesarean scars and uterus from one to two years after cesarean section using high-resolution,3D T2w SPACE MRI.The healthy volunteers having no childbearing history were recruited as the controls.All data were measured by two experienced radiologists.All data with normal distribution between the one-year and two-year groups were compared using a paired-sample t test or independent t test.Results Finally,46 women took a pelvic MR examination one year after cesarean section,and a subset of 15 completed the same examination again after two years of cesarean section.Both the uterine length and the anterior wall thickness after two years of cesarean section(5.75±0.46 and 1.45±0.35 cm)were significantly greater than those measured at one year(5.33±0.59 and 1.25±0.27 cm)(t=-2.363 and-2.175,P=0.033 and 0.048).No significant difference was shown in myometrial thickness two years after cesarean section(1.45±0.35 cm)with respect to the control group(1.58±0.21 cm,P=0.170).Nine women who underwent MRI twice were considered to have scar diverticula one year after cesarean section,and still had diverticula two years after cesarean section.The thickness,height,and width of the uterine scar showed no significant change from one to two years(all P>0.05).Conclusions 3D T2w SPACE MRI provides overall morphologic details and shows dynamic changes in the scar and the uterus between one and two years after cesarean section.Scar morphology after cesarean section reached relatively stable one year after cesarean section,and uterine morphology was closer to normal two years after cesarean section.

Assessing Liver Function by T1 Maps on Gd-EOB-DTPA- Enhanced MRI for up to 50 Min in Rat Models of Liver Fibrosis: A Longer Hepatobiliary Time Period may Help

Objectives To investigate whether a longer time period of gadolinium ethoxybenzyl diethylenetriaminepen-taacetic add(Gd-EOB-DTPA)-enhanced T1 mapping scanning,as well as dynamic contrast-enhanced(DCE)and multiple hepatobiliary phase magnetic resonance imaging(MRI)have the potential to provide information about liver function in rats with liver fibrosis.Methods Forty rats were divided into the carbon tetrachloride-induced hepatic injury groups[carbon tetrachloride for four(n=14),eight(n=8),or twelve(n=8)weeks]and the control group(n=10).Gd-EOB-DTPA-enhanced MRI was performed including T1-mapping(delayed to 50 min),DCE,and multiple hepatobiliary phases.Indocyanine green retention rate at 15 min(ICG-R15)was determined.Parameters such as T1 reduction rate(△T1),elimination half-life of △T1(T_(△T1 1/2)),relative enhancement(RE),time to maximum RE(T_(max)),and perfusion parameters were calculated.Pearson correlation analysis was used for correlation analysis between ICG-R15 and each MRI indices.Results △T1 at 30,40,and 50 min showed significant positive correlations with ICG-R15(r=0.784,0.653,0.757,P=0.007,0.041,0.030).T_(△T1 1/2) showed a significant positive correlation with ICG-R15(r=0.685,P=0.029).showed a significant positive correlation with ICG-R15(r=0.532,P=0.019).Conclusions △T1 in the late hepatobiliary phase and T_(△T1 1/2) exhibited moderate correlations with liver function.The longer time period of Gd-EOB-DTPA-enhanced Tl mapping scanning,as well as DCE and multiple hepatobiliary phases,may be of some value for estimating liver function in rats with liver fibrosis.