scholarly journals Stereotactic Radiotherapy for Brain Metastases: Imaging Tools and Dosimetric Predictive Factors for Radionecrosis

2020 ◽  
Vol 10 (3) ◽  
pp. 59
Author(s):  
Marco Lupattelli ◽  
Emanuele Alì ◽  
Gianluca Ingrosso ◽  
Simonetta Saldi ◽  
Christian Fulcheri ◽  
...  
Keyword(s):  
Blood Flow ◽  
Brain Metastases ◽  
Stereotactic Radiotherapy ◽  
Cerebral Blood Volume ◽  
Meta Analysis ◽  
Perfusion Magnetic Resonance Imaging ◽  
Diagnostic Tools ◽  
Normal Brain ◽  
Vessel Integrity ◽  
Peak Weight

Radionecrosis (RN) is the most important side effect after stereotactic radiotherapy (SRT) for brain metastases, with a reported incidence ranging from 3% to 24%. To date, there are no unanimously accepted criteria for iconographic diagnosis of RN, as well as no definitive dose-constraints correlated with the onset of this late effect. We reviewed the current literature and gave an overview report on imaging options for the diagnosis of RN and on dosimetric parameters correlated with the onset of RN. We performed a PubMed literature search according to the preferred reporting items and meta-analysis (PRISMA) guidelines, and identified articles published within the last ten years, up to 31 December 2019. When analyzing data on diagnostic tools, perfusion magnetic resonance imaging (MRI) seems to be very useful allowing evaluation of the blood flow in the lesion using the relative cerebral blood volume (rCBV) and blood vessel integrity using relative peak weight (rPH). It is necessary to combine morphological with functional imaging in order to match information about lesion morphology, metabolism and blood-flow. Eventually, serial imaging follow-up is needed. Regarding dosimetric parameters, in radiosurgery (SRS) V12 < 8 cm3 and V10 < 10.5 cm3 of normal brain are the most reliable prognostic factors, whereas in hypo-fractionated stereotactic radiotherapy (HSRT) V18 and V21 are considered the main predictive independent risk factors of RN.

The Study of Cerebral Blood Flow Variations Following Radiation Dose Gradients for Brain Metastasis Patients During Radiotherapy

2020 ◽  
Author(s):  
Chuanke Hou ◽  
Guanzhong Gong ◽  
Lizhen Wang ◽  
Ya Su ◽  
Jie Lu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Radiation Dose ◽  
Brain Metastases ◽  
Brain Tissue ◽  
Normal Brain ◽  
Peritumoral Edema ◽  
Sectional Area ◽  
Normal Brain Tissue ◽  
Cross Sectional

Abstract Brackground: Changes of cereberal blood flow in different brain regions of patients with brain metastases after radiotherapy are worth exploring. This study aims to investigate the radiation dose range of normal brain tissue and tumor target area by evaluating the cerebral blood flow(CBF) for brain metastases (BMs) patients applying with 3D arterial spin labeling (ASL).Methods: A total of 26 patients harboring 54 BMs treated with radiotherapy (RT) were imaged with magnetic resonance (MR) before and 30-40Gy post RT. The high signal area of BMs on enhanced T1-weighted images (T1WI), normal brain tissue, and peritumoral edema region were defined as regions of interest (ROIs). Changes and correlation of largest cross-sectional area and maximum CBF in BMs before and after RT were analyzed. Maximum CBF change in the three ROIs under different gradients created by thresholding the individual dose maps at 10 Gy steps were assessed.Results: In terms of 54 BMs, a significant decrease of CBF of 29.64% (P<0.05) compared to largest cross-sectional area of 26.46% (P<0.05). The decrease of CBF was more pronounced for 30-40 Gy (33.75%) than for 40-50Gy and >50Gy (24.61% and 27.55%). In normal brain tissue with dose gradients of 30-40Gy, CBF decreased to the maximum, 20.23% (P<0.05),which was similar to BMs. In contrast, the decrement rate of CBF in the peritumoral edema region increased as the dose gradients increased.Conclusions: CBF decreased significantly during the course of RT. According to CBF variations, the dose to the normal brain tissue should be controlled below 30 Gy as much as possible, whereas tumor with high perfusion and peritumoral edema region should be given a higher dose.

scholarly journals Cerebral Blood Flow, Blood Volume, and Mean Transit Time Responses to Propofol and Indomethacin in Peritumor and Contralateral Brain Regions

2010 ◽  
Vol 112 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Mads Rasmussen ◽  
Niels Juul ◽  
Søren M. Christensen ◽  
Kristjana Y. Jónsdóttir ◽  
Carsten Gyldensted ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Tumors ◽  
Blood Volume ◽  
Transit Time ◽  
Gray Matter ◽  
Cerebral Blood Volume ◽  
Mean Transit Time ◽  
Brain Regions ◽  
Normal Brain

Background The regional cerebral blood flow (CBF) response to propofol and indomethacin may be abnormal in patients with brain tumors. First, the authors tested the hypothesis that during propofol anesthesia alone and combined with indomethacin, changes in CBF, cerebral blood volume (CBV), and plasma mean transit time (MTT) differ in the peritumoral tissue compared with the contralateral normal brain region. Second, the authors tested the hypothesis that CBF and CBV are reduced and MTT is prolonged, in both regions during propofol anesthesia and indomethacin administration compared with propofol alone. Methods The authors studied eight patients subjected to craniotomy under propofol-fentanyl anesthesia for supratentorial brain tumors. Magnetic resonance imaging, including perfusion- and diffusion-weighted and structural sequences, was performed (1) on the day before surgery, (2) before and (3) after administration of indomethacin in the propofol-fentanyl anesthetized patient, and (4) 2 days after surgery. Maps of CBF, CBV, and MTT were calculated. The regions of interest were peritumoral gray matter and opposite contralateral gray matter. Analysis of variance was used to analyze flow data. Results Propofol anesthesia was associated with a median 32% (range, 3-61%) and 47% (range, 17-67%) reduction in CBF in the peritumoral and contralateral regions, respectively.The interaction between intervention with propofol and indomethacin and region of interest was not significant for any flow modalities. Neither intervention nor region was significant for MTT, CBF, and CBV (P &gt; 0.05). Conclusion The CBF, CBV, and MTT responses to propofol and indomethacin are not different in the peritumoral region compared with contralateral brain tissue. Indomethacin did not further influence regional CBF, CBV, and MTT during propofol anesthesia.

scholarly journals Responses in the diffusivity and vascular function of the irradiated normal brain are seen up until 18 months following SRS of brain metastases

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Line Brennhaug Nilsen ◽  
Ingrid Digernes ◽  
Endre Grøvik ◽  
Cathrine Saxhaug ◽  
Anna Latysheva ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Vascular Function ◽  
Cerebral Blood Volume ◽  
Performance Status ◽  
Eastern Cooperative Oncology Group ◽  
Normal Brain ◽  
Ecog Performance Status ◽  
Vascular Responses ◽  
Longitudinal Mri

Abstract Background MRI may provide insights into longitudinal responses in the diffusivity and vascular function of the irradiated normal-appearing brain following stereotactic radiosurgery (SRS) of brain metastases. Methods Forty patients with brain metastases from non-small cell lung cancer (N = 26) and malignant melanoma (N = 14) received SRS (15–25 Gy). Longitudinal MRI was performed pre-SRS and at 3, 6, 9, 12, and 18 months post-SRS. Measures of tissue diffusivity and vascularity were assessed by diffusion-weighted and perfusion MRI, respectively. All maps were normalized to white matter receiving less than 1 Gy. Longitudinal responses were assessed in normal-appearing brain, excluding tumor and edema, in the LowDose (1–10 Gy) and HighDose (&gt;10 Gy) regions. The Eastern Cooperative Oncology Group (ECOG) performance status was recorded pre-SRS. Results Following SRS, the diffusivity in the LowDose region increased continuously for 1 year (105.1% ± 6.2%; P &lt; .001), before reversing toward pre-SRS levels at 18 months. Transient reductions in microvascular cerebral blood volume (P &lt; .05), blood flow (P &lt; .05), and vessel densities (P &lt; .05) were observed in LowDose at 6–9 months post-SRS. Correspondingly, vessel calibers in LowDose transiently increased at 3–9 months (P &lt; .01). The responses in HighDose displayed similar trends as in LowDose, but with larger interpatient variations. Vascular responses followed pre-SRS ECOG status. Conclusions Our results imply that even low doses of radiation to normal-appearing brain following cerebral SRS induce increased diffusivity and reduced vascular function for up until 18 months. In particular, the vascular responses indicate the reduced ability of the normal-appearing brain tissue to form new capillaries. Assessing the potential long-term neurologic effects of SRS on the normal-appearing brain is warranted.

Dosimetric comparison of fractionated radiosurgery plans using frameless Gamma Knife ICON and CyberKnife systems with linear accelerator–based radiosurgery plans for multiple large brain metastases

2020 ◽  
Vol 132 (5) ◽  
pp. 1473-1479 ◽  
Author(s):  
Eun Young Han ◽  
He Wang ◽  
Dershan Luo ◽  
Jing Li ◽  
Xin Wang
Keyword(s):  
Brain Metastases ◽  
Gamma Knife ◽  
Linear Accelerator ◽  
Treatment Time ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Normal Brain ◽  
Large Brain ◽  
The Mean

OBJECTIVEFor patients with multiple large brain metastases with at least 1 target volume larger than 10 cm3, multifractionated stereotactic radiosurgery (MF-SRS) has commonly been delivered with a linear accelerator (LINAC). Recent advances of Gamma Knife (GK) units with kilovolt cone-beam CT and CyberKnife (CK) units with multileaf collimators also make them attractive choices. The purpose of this study was to compare the dosimetry of MF-SRS plans deliverable on GK, CK, and LINAC and to discuss related clinical issues.METHODSTen patients with 2 or more large brain metastases who had been treated with MF-SRS on LINAC were identified. The median planning target volume was 18.31 cm3 (mean 21.31 cm3, range 3.42–49.97 cm3), and the median prescribed dose was 27.0 Gy (mean 26.7 Gy, range 21–30 Gy), administered in 3 to 5 fractions. Clinical LINAC treatment plans were generated using inverse planning with intensity modulation on a Pinnacle treatment planning system (version 9.10) for the Varian TrueBeam STx system. GK and CK planning were retrospectively performed using Leksell GammaPlan version 10.1 and Accuray Precision version 1.1.0.0 for the CK M6 system. Tumor coverage, Paddick conformity index (CI), gradient index (GI), and normal brain tissue receiving 4, 12, and 20 Gy were used to compare plan quality. Net beam-on time and approximate planning time were also collected for all cases.RESULTSPlans from all 3 modalities satisfied clinical requirements in target coverage and normal tissue sparing. The mean CI was comparable (0.79, 0.78, and 0.76) for the GK, CK, and LINAC plans. The mean GI was 3.1 for both the GK and the CK plans, whereas the mean GI of the LINAC plans was 4.1. The lower GI of the GK and CK plans would have resulted in significantly lower normal brain volumes receiving a medium or high dose. On average, GK and CK plans spared the normal brain volume receiving at least 12 Gy and 20 Gy by approximately 20% in comparison with the LINAC plans. However, the mean beam-on time of GK (∼ 64 minutes assuming a dose rate of 2.5 Gy/minute) plans was significantly longer than that of CK (∼ 31 minutes) or LINAC (∼ 4 minutes) plans.CONCLUSIONSAll 3 modalities are capable of treating multiple large brain lesions with MF-SRS. GK has the most flexible workflow and excellent dosimetry, but could be limited by the treatment time. CK has dosimetry comparable to that of GK with a consistent treatment time of approximately 30 minutes. LINAC has a much shorter treatment time, but residual rotational error could be a concern.

The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis

2021 ◽  
pp. 026921552110034
Author(s):  
Nico Nitzsche ◽  
Alexander Stäuber ◽  
Samuel Tiede ◽  
Henry Schulz
Keyword(s):  
Blood Flow ◽  
Resistance Training ◽  
Muscle Strength ◽  
Lower Limb ◽  
Meta Analysis ◽  
Load Resistance ◽  
Muscle Volume ◽  
Low Load ◽  
Study Characteristics ◽  
Musculoskeletal Rehabilitation

Objective: This meta-analysis aimed to evaluate the effectiveness of low-load Resistance Training (RT) with or without Blood Flow Restriction (BFR) compared with conventional RT on muscle strength in open and closed kinetic chains, muscle volume and pain in individuals with orthopaedic impairments. Data sources: Searches were conducted in the PubMed, Web of Science, Scopus and Cochrane databases, including the reference lists of randomised controlled trials (RCT’s) up to January 2021. Review method: An independent reviewer extracted study characteristics, orthopaedic indications, exercise data and outcome measures. The primary outcome was muscle strength of the lower limb. Secondary outcomes were muscle volume and pain. Study quality and reporting was assessed using the TESTEX scale. Results: A total of 10 RCTs with 386 subjects (39.2 ± 17.1 years) were included in the analysis to compare low-load RT with BFR and high or low-load RT without BFR. The meta-analysis showed no significant superior effects of low-load resistance training with BFR regarding leg muscle strength in open and closed kinetic chains, muscle volume or pain compared with high or low-load RT without BFR in subjects with lower limb impairments. Conclusion: Low-load RT with BFR leads to changes in muscle strength, muscle volume and pain in musculoskeletal rehabilitation that are comparable to conventional RT. This appears to be independent of strength testing in open or closed kinetic chains.

Sign in / Sign up

Export Citation Format

Share Document