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Objective To investigate the value of computed tomography (CT)-magnetic resonance imaging (MRI) image fusion in target volume delineation of postoperative precise radiotherapy for gliomas.Methods Thirty-six patients newly diagnosed with gliomas were enrolled and received postoperative intensity-modulated radiotherapy.Landmark (L) combined with manual fusion (M) and maximization of mutual information (MI) was used for image fusion.Target volume and organs at risk were delineated based on CT images and fused images,respectively.Comparison of the volume was made by pairwise t test.The distance from a landmark on CT image to the corresponding one on MRI image was calculated.The volume method and geometric center method were used to calculate the degree of volume overlap and changes in central positions after image fusion.Results The L+M+MI method achieved a high registration accuracy in image fusion,with a registration error less than 2 mm.In patients with grade Ⅲ-V gliomas,the CT images yielded significantly smaller gross tumor volume (GTV) and clinical target volume (CTV) than the MRI images (74.62±46.91 vs.105.99±58.86 cm3,P=O.042;304.03± 130.05 vs.387.94± 150.12 cm3,P=0.040).After image fusion,the smallest change in central position occurred in the chiasma (1.32± 1.42 mm),and the largest change occurred in CTV (7.99± 11.06 mm),followed by GTV and the brain stem.Conclusions CT-MRI image fusion helps to reduce the uncertainty of target volume delineation in patients with gliomas,especially in those with edema and residual tumor after surgery.
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Objective To investigate the role of forehead dot marking in immobilization during radiotherapy for brain tumors.Methods A total of 84 patients with brain tumors were immobilized using the full-head mask from 2013 to 2014;among these patients, 36 received dot marking at the center of the forehead ( group A) , 27 received routine immobilization ( group B) , and 21 received dot marking at one side of the forehead ( group C) .Kilovoltage cone-beam computed tomography ( CBCT) was used to compare the deviation in spatial position.The t-test was used to compare the deviation of the first CBCT in group A with the errors of subsequent CBCT.Results The passing rates of 212 times of CBCT in group A and 158 times of CBCT in group B were 95.2%and 93.8%.The errors in x, y, and z directions in groups A and B were 0.868±0.618 mm vs.1.319±0.935 mm (P=0.005), 1.118±0.692 mm vs.1.149±0.807 mm (P=0.824) , and 0.868±0.790 mm vs.0.936±0.919 mm ( P=0.665) .In group C, the error in the x direction was 1.162±0.866 mm, similar to those in groups A and B ( P=0.070 and 0.430) .In group A, the error in the x direction showed a difference between the first time and the sixth time (0.790±0.656 mm vs.1.280± 0.724 mm, P=0.030) .Conclusions Compared with the routine technique, dot marking at the center of the forehead can improve the accuracy of positioning in the x direction and reduce rotation error, and provides a new method for immobilization in radiotherapy for brain tumors.
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Objective To investigate the clinical value of blood oxygen level-dependent functional magnetic resonance imaging (BOLD-FMRI) in guiding the dose reduction and functional protection of the motor cortex during postoperative radiotherapy for brain astrocytoma.Methods This study included 27 brain astrocytoma patients with tumors near the motor cortex,who underwent routine MRI and BOLD-FMRI before postoperative radiotherapy.The location and scope of the motor cortex,which were acquired based on BOLD-FMRI results,were marked on positioning CT images,so that the motor cortex would be dealt with as organs at risk.The dose to the motor cortex was reduced as much as possible while ensuring the therapeutic dose to the target area.Finally,the radiotherapy plan that would reduce the mean received dose of the motor cortex was formulated and compared with the routine plan that could not reduce the received dose.Results With the protective radiotherapy plan,the mean received dose of the motor cortex decreased 0.76％-59.20％ (mean 30.78％) on the affected side and 23.33％-68.30％ (mean 48.07％) on the unaffected side;the coefficients of variation were 71.41％ on the affected side and 36.71％ on the unaffected side.Conclusions BOLD-FMRI can help to reduce the received dose of the motor cortex while ensuring the therapeutic dose to the target area when formulating the postoperative radiotherapy plan for brain astrocytoma,thus protecting the motor function and improving patients' quality of life.
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ObjectiveTo investigate whether the T1-weighted dynamic contrast-enhanced perfusion magnetic resonance imaging (DCEPMRI) technique can help to delineate the clinical target volume of brain glioma patients.MethodsThe DCE T1-weighted images from 28 glioma patients were collected after GdDTPA was injected.After the acquired images were processed and analyzed using modified Tofts-Kermode'two compartment analysis model and de-convolution method,the value and its pseudo mapping of quantitative parameter Ktrans related to microvascular permeability were obtained.The tumor size in the largest diameter slice measured both in routine enhanced MRI and Ktrans mapping of T1-weighted DCEPMRI were compared.ResultsThe vascular permeability and tumor infiltration was lower in low grade glioma,the difference of the tumor size between T1-weighted DCEPMRI and routine enhanced MRI reached 0.2％ -0.3％ there was significant difference of tumor size between T1 -weighted DCEPMRI and routine enhanced MRI ( grade Ⅰ and Ⅱ grade with 2.93 cm2∶2.46 cm2(t=6.90,P=0.000) and 4.18 cm2∶3.21 cm2(t=10.22,P=0.000) ).While in high grade glioma,the vascular permeability and the tumor infiltration were higher,the difference of the tumor size between T1-weighted DCEPMRI and routine enhanced MRI reached 25％ - 26％( the size of grade Ⅲ and Ⅳ were 6.46 cm2 vs 5.48 cm2 ( t =10.83,P =0.000) and 8.26 cm2 vs 6.52 cm2(t =18.53,P =0.000) ).ConclusionsThe pseudo mapping of quantitative parameter Ktrans related to microvascular permeability acquired by T1-weighted DCEPMRI reflect the infiltrating circumscription in glioma,T1-weighted DCEPMRI can provide more information in delineation the clinical target volume,and it can be used as a new method for tumor volume evaluation.
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Objective To evaluate the role of 11C-methionine positron emission tomographv(MET PET-CT)in differentiating tumor recurrence from radiation necrosis in brain slioma patients.Methods From June 2008 to September 2009,30 brain glioma patients with suspected tumor recurvence or radiation necrosis after radiotherapy were evaluated by MET PET-CT.The median time between initial radiotherapy and PET examination was 13.5 months.Tumor recurrence were confirmed by histological analysis while necrosis was based on histological analysis or the subsequent clinical follow-up.Results Eighteen out of 19 patients were histologically confirmed tumor recurrence among those tumor recurrence shown by MET PET-CT after surgery or stereotactic biopsy.11 patients were considered to have radiation necrosis because of stable neurological sympotoms and without massive enlargement of the lesion during the after follow-up.The sensitivity,specificity and accuracy of MET PET-CT for detecting tumor recurrence were 100%,91.7%and 96.7%respectively.Conclusion MET PET-CT is a powerful tool in differentiating brain tumor recurrence from radiation necrosis after radiotherapy.
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Objective To study the value of serum S-100B protein in the diagnosis of cerebral radi-ation injuries in patients with brain malignant tumor. Methods Serum S-100B protein level was deteetod by enzyme-linked immunosorbent assay in 56 patients with brain malignant tumor before, during and after radio-therapy. Effects of dose and method of radiotherapy, peritumoral edema degree and Karnofsky performance status on serum S-100B level were studied. Results The levels of serum S-100B protein in the patients be-fore radiotherapy and control group were 0. 039μg/L and 0.044 μg/L ( t = 1.48 ,P =0. 186). The levels of serum S-100B protein before, in the middle of (30-40 Gy) and after (60 -70 Gy) radiotherapy were 0.044 μ/L, 0.049 μ/L and 0.079 μg/L, respectively ( F = 67.26, P = 0.000). The differences after ra-diotherapy were also significant among patients with three methods of radiotherapy (F = 20.32, P = 0.000), different degree of pefitumoral edema ( F = 12.94, P =0. 000 ) and Karnofsky perforrnanee status ( t = 2.71, P =0.007). Conclusions High level of serum S-100B protein is associated with cerebral radiation injuries in patients with brain malignant tumor, which is influenced by the dose and method of radiotherapy, Karnof-sky performance stares and degree of peritumoral edema. High level of serum S-100B protein may serve as an early predictor of cerebral radiation injury.
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Objective To analyze the results of postoperative conventional radiotherapy supplemen- ted by stereotactic radiotherapy for glioma and with analysis of prognostic factors.Methods From Dec. 1998 to Dee.2004,143 patients with brain glioma were postoperatively treated with conventional radiotherapy supplemented by stereotactic radiotherapy.Steretactic radiotherapy of 5-7 Gy/fraction,to totally 5-7 fractions were added as boost to the GTV following the conventional radiotherapy.The conventional radiotherapy,ai- ming at the peri-tumoral subclinical micro-loci,was about 50 Gy.Results The KPS grades were 81?9, 71?9 in patients 3-6 month after treatment in contrast to that prior to operation (t=5.98,P＜0.01 ).CR 39 patients (27.3%) ,PR 70 patients(49.0% ) ,NC 25 patients(17.5%),PD 9 patients(6.3%),with an effi- ciency rate of 76%.The 1-,3-,and 5-year survival rate was 56.6%,36.0% and 21.7%,respectively. Prognostic factor analysis showed that patients with low grade glioma had better survival time.Age,tumor site and dose,etc were unrelated to prognosis.Conclusion Stereotactic radiotherapy supplementing conven- tional radiotherapy is effective for postoperative brain glioma,which method not only shows excellence in physical dose distribution but strictly in accordance with the principle of radiobiology also.