UNASSIGNED: Radiation-induced changes (RICs) post-stereotactic radiosurgery (SRS) critically influence outcomes in arteriovenous malformation (AVM) treatments. This study aimed to identify predictors of RICs, described the types and severity of RICs, and assessed their impact on patient\'s functional outcomes to enhance risk assessment and treatment planning for AVM patients.
UNASSIGNED: This retrospective study analyzed 87 AVM patients who underwent SRS at Hospital Kuala Lumpur between January 2015 and December 2020. RICs were identified through detailed magnetic resonance imaging evaluations, and predictive factors were determined using multiple logistic regression. Functional outcomes were assessed with the modified Rankin scale (mRS).
UNASSIGNED: Among the cohort, 40.2% developed RICs, with radiological RICs in 33.3%, symptomatic RICs in 5.7%, and permanent RICs in 1.1%. Severity categorization revealed 25.3% as Grade I, 13.8% as Grade II, and 1.1% as Grade III. Notably, higher Pollock-Flickinger scores and eloquence location were significant predictors of RIC occurrence. There was a significant improvement in functional outcomes post-SRS, with a marked decrease in non-favorable mRS scores from 8.0% pre-SRS to 1.1% post-SRS (P = 0.031).
UNASSIGNED: The study identified the eloquence location and Pollock-Flickinger scores as predictors of RICs post-SRS. The significant reduction in non-favorable mRS scores post-SRS underscores the efficacy of SRS in improving patient outcomes. Their results highlighted the importance of personalized treatment planning, focusing on precise strategies to optimize patient outcomes in AVM management, reducing adverse effects while improving functional outcomes.

Brain metastases in patients with extracranial cancer are typically associated with increased morbidity and mortality. Stereotactic radiotherapy and immunotherapy using checkpoint inhibitors currently are essential in brain metastases treatment. Since conventional contrast-enhanced MRI alone cannot reliably differentiate between treatment-induced changes and brain metastasis relapse, several studies investigated the role of PET imaging and, more recently, radiomics, based on routinely acquired PET images, to overcome this clinically relevant challenge.
The current literature on PET imaging, including radiomics, in patients with brain metastases, focusing on the diagnosis and assessment of post-treatment relapse, is summarized.
Available data suggest that imaging parameters, including radiomics features, mainly derived from amino acid PET, are helpful for diagnosis and assessment of post-treatment relapse in patients with brain metastases.

OBJECTIVE: Dosimetric radiosurgery incidents are rare and probably insufficiently reported in scientific publications. After a long follow-up (FU), the authors studied the outcomes of patients treated with overexposure radiation for arteriovenous malformation (AVM) administered via stereotactic radiosurgery (SRS) at their department.
METHODS: Between May 2006 and June 2007, 22 patients were treated for AVM with SRS. The mean (range) patient age was 43.5 (11.8-78) years. Previous treatments were embolization (n = 10), SRS (1), and surgery (1). The average (range) volume was 2.1 (0.2-6.4) cm3. The median prescribed minimal dose was 18.0 Gy. An initial error in the estimation of scatter factors led to overexposure to radiation. Due to this incident, the median delivered minimum dose was 25.0 Gy. All patients were prospectively followed with clinical examination and imaging.
RESULTS: The mean (range) clinical FU was 14.5 (12.0-15.2) years. AVM obliteration after SRS was completed in 90.9% of patients at a mean (range) of 39.4 (24.4-70.4) months. No patient had post-SRS AVM bleeding. Three patients (13.6%) had new permanent deficits due to radiation-induced changes (RICs). Obliteration without new deficits was achieved in 18 patients (81.8%). Two patients had new epilepsy that was probably due to RIC but well controlled. The median (range) MRI FU was 13.8 (2.5-14.9) years. During MRI FU, two RIC periods were observed: one classic period during the first 3 years showed T1-weighted annular irregular enhancement (13%), and the other period between 5 and 15 years after SRS showed the occurrence of cystic and hemorrhagic lesions (22.7%). There were no cases of radiation-induced tumor.
CONCLUSIONS: The present long-term report showed that this overexposure incident probably increased the AVM obliteration rate. This overexposure seems to have induced RIC and in particular a higher rate of cystic and hemorrhagic late lesions with nevertheless moderate clinical consequences. Long-term FU for AVM is mandatory due to the risk of late RIC.

暂无摘要。

UNASSIGNED: Previous MRI studies have shown a substantial decrease in normal-tissue uptake of a hepatobiliary-directed contrast agent 6-9 weeks after liver irradiation. In this prospective clinical study, we investigated whether this effect is detectable during the course of proton therapy.
UNASSIGNED: Gd-EOB-DTPA enhanced MRI was performed twice during hypo-fractionated proton therapy of liver lesions in 9 patients (plus two patients with only one scan available). Dose-correlated signal changes were qualitatively scored based on difference images from the two scans. We evaluated the correlation between the MRI signal change with the planned dose map. The GTV was excluded from all analyses. In addition, were examined timing, irradiated liver volume, changes in liver function parameters as well as circulating biomarkers of inflammation.
UNASSIGNED: Strong, moderate or no dose-correlated signal changes were detected for 2, 3 and 5 patients, respectively. Qualitative scoring was consistent with the quantitative dose to signal change correlation. In an exploratory analysis, the strongest correlation was found between the qualitative scoring and pretreatment IL-6 concentration. For all patients, a clear dose-correlated signal decrease was seen in late follow-up scans.
UNASSIGNED: Radiation-induced effects can be detected with Gd-EOB-DTPA enhanced MRI in a subgroup of patients within a few days after proton irradiation. The reason for the large inter-patient variations is not yet understood and will require validation in larger studies.

BACKGROUND: Arteriovenous malformations (AVMs) are potentially dangerous vascular anomalies of the brain that can cause seizures or intracranial hemorrhage in patients if left untreated. Because full excision of these lesions is not always possible in deep or eloquent areas of the brain, radiosurgical advances have gone a long way in the control and treatment of AVMs. Postradiosurgery AVMs are followed closely via outpatient clinics with serial imaging every few months to assess AVM obliteration. Post X-knife treatment AVMs still carry with them some risk of rebleeding and even a chance of malignant transformation.
METHODS: In this article, we report a case of a post X-knife-treated arteriovenous malformation with the appearance of malignant change on magnetic resonance imaging and thallium-201 on follow-up 30 years after treatment. Imaging with magnetic resonance angiography showed obliteration of the lesion but progressive change in size with new soft tissue components, which suggests radiation-related secondary malignancy.
CONCLUSIONS: Surgery was arranged, and pathology results indicate no malignant change.

To assess the sensitivity and specificity of arteriovenous malformation (AVM) nidal component identification and quantification using an unsupervised machine learning algorithm and to evaluate the association between intervening nidal brain parenchyma and radiation-induced changes (RICs) after stereotactic radiosurgery.
Fully automated segmentation via unsupervised classification with fuzzy c-means clustering was used to analyze the AVM nidus on T2-weighted magnetic resonance imaging studies. The proportions of vasculature, brain parenchyma, and cerebrospinal fluid were quantified. These were compared with the results from manual segmentation. The association between the brain parenchyma component and RIC development was assessed.
The proposed algorithm was applied to 39 unruptured AVMs in 39 patients (17 female and 22 male patients), with a median age of 27 years. The median proportion of the constituents was as follows: vasculature, 31.3%; brain parenchyma, 48.4%; and cerebrospinal fluid, 16.8%. RICs were identified in 17 of the 39 patients (43.6%). Compared with manual segmentation, the automated algorithm was able to achieve a Dice similarity index of 79.5% (sensitivity, 73.5%; specificity, 85.5%). RICs were associated with a greater proportion of intervening nidal brain parenchyma (52.0% vs. 45.3%; P = 0.015). Obliteration was not associated with greater proportions of nidal vasculature (36.0% vs. 31.2%; P = 0.152).
The automated segmentation algorithm was able to achieve classification of the AVM nidus components with relative accuracy. Greater proportions of intervening nidal brain parenchyma were associated with RICs.

The aim of this study was to investigate the potential of combined textural feature analysis of contrast-enhanced MRI (CE-MRI) and static O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET for the differentiation between local recurrent brain metastasis and radiation injury since CE-MRI often remains inconclusive.
Fifty-two patients with new or progressive contrast-enhancing brain lesions on MRI after radiotherapy (predominantly stereotactic radiosurgery) of brain metastases were additionally investigated using FET PET. Based on histology (n = 19) or clinicoradiological follow-up (n = 33), local recurrent brain metastases were diagnosed in 21 patients (40%) and radiation injury in 31 patients (60%). Forty-two textural features were calculated on both unfiltered and filtered CE-MRI and summed FET PET images (20-40 min p.i.), using the software LIFEx. After feature selection, logistic regression models using a maximum of five features to avoid overfitting were calculated for each imaging modality separately and for the combined FET PET/MRI features. The resulting models were validated using cross-validation. Diagnostic accuracies were calculated for each imaging modality separately as well as for the combined model.
For the differentiation between radiation injury and recurrence of brain metastasis, textural features extracted from CE-MRI had a diagnostic accuracy of 81% (sensitivity, 67%; specificity, 90%). FET PET textural features revealed a slightly higher diagnostic accuracy of 83% (sensitivity, 88%; specificity, 75%). However, the highest diagnostic accuracy was obtained when combining CE-MRI and FET PET features (accuracy, 89%; sensitivity, 85%; specificity, 96%).
Our findings suggest that combined FET PET/CE-MRI radiomics using textural feature analysis offers a great potential to contribute significantly to the management of patients with brain metastases.

BACKGROUND: The aim of this study was assess acute and early delayed radiation-induced changes in normal-appearing brain tissue perfusion as measured with perfusion magnetic resonance imaging (MRI) and the dependence of these changes on the fractionated radiotherapy (FRT) dose level.
METHODS: Seventeen patients with glioma WHO grade III-IV treated with FRT were included in this prospective study, seven were excluded because of inconsistent FRT protocol or missing examinations. Dynamic susceptibility contrast MRI and contrast-enhanced 3D-T1-weighted (3D-T1w) images were acquired prior to and in average (standard deviation): 3.1 (3.3), 34.4 (9.5) and 103.3 (12.9) days after FRT. Pre-FRT 3D-T1w images were segmented into white- and grey matter. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were calculated and co-registered patient-wise to pre-FRT 3D-T1w images. Seven radiation dose regions were created for each tissue type: 0-5 Gy, 5-10 Gy, 10-20 Gy, 20-30 Gy, 30-40 Gy, 40-50 Gy and 50-60 Gy. Mean CBV and CBF were calculated in each dose region and normalised (nCBV and nCBF) to the mean CBV and CBF in 0-5 Gy white- and grey matter reference regions, respectively.
RESULTS: Regional and global nCBV and nCBF in white- and grey matter decreased after FRT, followed by a tendency to recover. The response of nCBV and nCBF was dose-dependent in white matter but not in grey matter.
CONCLUSIONS: Our data suggest that radiation-induced perfusion changes occur in normal-appearing brain tissue after FRT. This can cause an overestimation of relative tumour perfusion using dynamic susceptibility contrast MRI, and can thus confound tumour treatment evaluation.

The aim of this study was investigate whether histopathological changes in the neurogenic region correlate with appropriate cognitive impairment in the experimental model of radiation-induced brain injury.
Adult male Wistar rats randomized into sham (0 Gy) and two experimental groups (survived 30 and 100 days after treatment) received fractionated whole-brain irradiation (one 5 Gy fraction/week for four weeks) with a total dose of 20 Gy of gamma rays. Morris water maze cognitive testing, histochemistry, immunohistochemistry and confocal microscopy were used to determine whether the cognitive changes are associated with the alteration of neurogenesis, astrocytic response and activation of microglia along and/or adjacent to well-defined pathway, subventricular zone-olfactory bulb axis (SVZ-OB axis).
Irradiation revealed altered cognitive functions usually at 100 days after treatment. Neurodegenerative changes were characterized by a significant increase of Fluoro-Jade-positive cells 30 days after irradiation accompanied by a steep decline of neurogenesis 100 days after treatment. A strong astrocytic response and upregulation of the activated microglia were seen in both of experimental groups.
Results shows that fractionated irradiation led to cognitive impairment closely associated with accerelation of neuronal cell death, inhibition of neurogenesis, activation of astrocytes and microglia indicate early delayed radiation-induced changes.