Images of a 43-year-old male with a grade II astrocytoma.

<p>(A) T2-weighted image, (B) T2 FLAIR image, (C) T1-weighted image, (D) contrast-enhanced T1-weighted image, (E) ADC map with ROI placement, with the corresponding (E) 3-D height map of the ADC signal intensity, (G) histogram of ADC and (F) cumulative ADC histogram. The entropy value of ADC was 6.168.</p

ADC texture and histogram parameters of low- and high-grade gliomas.

<p>Note.–Values are the means ± standard deviation.</p><p>*Significant difference between two groups (<i>P<</i>.05), The difference between two groups was evaluated using the unpaired student’s t-test.</p><p>ADC texture and histogram parameters of low- and high-grade gliomas.</p

ROC results for Entropy and the Fifth percentile of the ADC histogram for glioma grading (low- vs. high-grade).

<p>Note.–*The data in parentheses are 95% confidence intervals.</p>†<p>Sensitivity and specificity for identifying high-grade tumors. The data in parentheses are the numbers used to calculate the percentages.</p><p>ROC results for Entropy and the Fifth percentile of the ADC histogram for glioma grading (low- vs. high-grade).</p

ROC result for Entropy of ADC for glioma grading (Grade III vs. IV).

<p>Note.–*The data in parentheses are 95% confidence intervals.</p>†<p>Sensitivity and specificity for identifying grade IV gliomas. The data in parentheses are the numbers used to calculate the percentages.</p><p>ROC result for Entropy of ADC for glioma grading (Grade III vs. IV).</p

ADC texture and histogram parameters of the grade II, III and IV gliomas.

<p>Note.–Values are the means ± standard deviation.</p><p>*Significant difference between three groups (<i>P<</i>.05); P-values were calculated using a one-way analysis of variance with a post-hoc test.</p><p>**P values were calculated using a one-way analysis of variance, and a post-hoc test was not performed.</p><p>ADC texture and histogram parameters of the grade II, III and IV gliomas.</p

The correlation study of the Ki-67 labeling index (A) with the entropy and (B) with the fifth percentile of ADC using a linear regression model.

<p>The relationships were significant. (R2 = 0.1072, <i>P</i> = 0.039; R2 = 0.2150, <i>P</i> = 0.003, respectively). The tumor grades of the tissue specimens were marked as colored dots (blue = grade II, orange = grade III, red = grade IV).</p

Images of a 62-year-old male with a grade IV glioblastoma.

<p>(A) T2-weighted image, (B) T2 FLAIR image, (C) T1-weighted image, (D) contrast-enhanced T1-weighted image, (E) ADC map with ROI placement, with the corresponding (E) 3-D height map of the ADC signal intensity, (G) histogram of ADC and (F) cumulative ADC histogram. The entropy value of ADC was 7.05.</p

Definition of Area_H and Area_L.

<p>A 58-year-old female patient underwent radiotherapy for the treatment of GBM located in the right frontal lobe. The radiotherapy plan map was obtained from the electronic medical records system (EMR) and was composed of representative <b>(a)</b> axial, <b>(b)</b> coronal, and sagittal (not presented) CT images (note; arrows represent the iso-dose line of 3600 cGy). In this patient, <b>(c)</b> the right thalamus (dashed circle) was designated as a Area_H, whereas <b>(d)</b> the left frontal white matter (dashed circle) was considered a Area_L (presented images: pre-contrast T1WI).</p

Does radiation therapy increase gadolinium accumulation in the brain?: Quantitative analysis of T1 shortening using R1 relaxometry in glioblastoma multiforme patients

<div><p>Objective</p><p>This study evaluated the possibility of accelerated gadolinium accumulation in irradiated brain parenchyma where the blood-brain barrier was weakened.</p><p>Methods</p><p>From January 2010 to June 2015, 44 patients with supratentorial glioblastoma were retrospectively identified who underwent pre- and post-radiation brain MR imaging, including R1 mapping. The mean dose of administered gadobutrol (Gadovist, Bayer, Germany) was 5.1 vials. Regions of interest (ROIs) were drawn around tumors that were located within 50–100% iso-dose lines of maximum radiation dose. ROIs were also drawn at globus pallidus, thalamus, and cerebral white matter. Averages of R1 values (unit: s^-1) before and after radiation and those of R1 ratio (post-radiation R1 / pre-radiation R1) were compared by t-test or rank sum test as appropriate. Multiple linear regression analysis was performed to evaluate independent association factors for R1 value increase at irradiated parenchyma.</p><p>Results</p><p>The mean R1 values in peri-tumoral areas were significantly increased after radiotherapy (0.7901±0.0977 [mean±SD] vs. 0.8146±0.1064; P <.01). The mean R1 ratio of high radiation dose areas was significantly higher than that of low dose areas (1.0055±0.0654 vs. 0.9882±0.0642; P <.01). The mean R1 ratio was lower in those who underwent hypofractionated radiotherapy (mean dose, 45.0 Gy) than those who underwent routine radiotherapy (mean dose, 61.1 Gy) (0.9913±0.0740 vs. 1.0463±0.0633; P = .08). Multiple linear regression analysis revealed that only radiotherapy type was significantly associated with increased R1 (P = .02) around tumors.</p><p>Conclusions</p><p>Radiotherapy can induce R1 value increase in the brain parenchyma, which might suggest accelerated gadolinium accumulation due to damage to the blood-brain barrier.</p></div

Timeline of patient treatment and the imaging study.

<p>The standard treatment for newly diagnosed GBM includes gross total removal of the tumor and concurrent chemoradiotherapy with temozolomide, followed by adjuvant temozolomide. In this study, we enrolled patients who underwent pre- and post-radiation brain MRI including R1 map source images. Pre-radiation MRI included MRI performed either before or after tumor removal. The mean time interval between pre- and post-radiation MRI session was 4.2 ± 2.1 months. Further follow-up brain MRI with R1 mapping was available for 10 patients.</p