Feasibility of Multimodal MRI-Based Deep Learning Prediction of High Amino Acid Uptake Regions and Survival in Patients With Glioblastoma.

Amino acid PET has shown high accuracy for the diagnosis and prognostication of malignant gliomas, however, this imaging modality is not widely available in clinical practice. This study explores a novel end-to-end deep learning framework ("U-Net") for its feasibility to detect high amino acid uptake glioblastoma regions (i.e.

Multimodal Imaging of Nonenhancing Glioblastoma Regions.

Background: Clinical glioblastoma treatment mostly focuses on the contrast-enhancing tumor mass. Amino acid positron emission tomography (PET) can detect additional, nonenhancing glioblastoma-infiltrated brain regions that are difficult to distinguish on conventional magnetic resonance imaging (MRI). We combined MRI with perfusion imaging and amino acid PET to evaluate such nonenhancing glioblastoma regions.

Multimodal imaging-defined subregions in newly diagnosed glioblastoma: impact on overall survival.

Background: Although glioblastomas are heterogeneous brain-infiltrating tumors, their treatment is mostly focused on the contrast-enhancing tumor mass. In this study, we combined conventional MRI, diffusion-weighted imaging (DWI), and amino acid PET to explore imaging-defined glioblastoma subregions and evaluate their potential prognostic value.

Methods: Contrast-enhanced T1, T2/fluid attenuated inversion recovery (FLAIR) MR images, apparent diffusion coefficient (ADC) maps from DWI, and alpha-[11C]-methyl-L-tryptophan (AMT)-PET images were analyzed in 30 patients with newly diagnosed glioblastoma.

Amino Acid PET Imaging of the Early Metabolic Response During Tumor-Treating Fields (TTFields) Therapy in Recurrent Glioblastoma.

Tumor-treating fields (TTFields) therapy is a relatively new treatment approach for malignant gliomas. We evaluated if amino acid PET can detect an objective metabolic response to TTFields therapy in recurrent glioblastomas. PET scanning with alpha[C-11]-methyl-L-tryptophan (AMT) before and 2 to 3 months after the start of TTFields treatment showed an interval decrease of tryptophan uptake in the whole tumor (2 patients) or in a portion of the tumor (1 patient).

Tryptophan PET predicts spatial and temporal patterns of post-treatment glioblastoma progression detected by contrast-enhanced MRI.

Amino acid PET is increasingly utilized for the detection of recurrent gliomas. Increased amino acid uptake is often observed outside the contrast-enhancing brain tumor mass. In this study, we evaluated if non-enhancing PET+ regions could predict spatial and temporal patterns of subsequent MRI progression in previously treated glioblastomas.

Multi-modal imaging of tumor cellularity and Tryptophan metabolism in human Gliomas.

Background: To assess gliomas using image-based estimation of cellularity, we utilized isotropic diffusion spectrum imaging (IDSI) on clinically feasible diffusion tensor imaging (DTI) and compared it with amino acid uptake measured by α[(11)C]methyl-L-tryptophan positron emission tomography (AMT-PET).

Methods: In 10 patients with a newly-diagnosed glioma, metabolically active tumor regions were defined in both FLAIR hyperintense areas and based on increased uptake on AMT-PET. A recently developed independent component analysis with a ball and stick model was extended to perform IDSI in clinical DTI data.

Molecular imaging correlates of tryptophan metabolism via the kynurenine pathway in human meningiomas.

Background: Increased tryptophan metabolism via the kynurenine pathway (KP) is a key mechanism of tumoral immune suppression in gliomas. However, details of tryptophan metabolism in meningiomas have not been elucidated. In this study, we evaluated in vivo tryptophan metabolism in meningiomas and compared it with gliomas using α-[(11)C]-methyl-L-tryptophan (AMT)-PET.

Trauma patterns, symptoms, and complications associated with external auditory canal fractures.

Objectives/hypothesis: External auditory canal (EAC) trauma, although rare, can have significant long-term adverse outcomes. This study aims to investigate the frequency, treatment, and complications of external ear canal injury in association with mandibular and temporal bone trauma.

Study Design: Retrospective chart review.

Tryptophan PET-defined gross tumor volume offers better coverage of initial progression than standard MRI-based planning in glioblastoma patients.

Objective: Glioblastoma is an infiltrative malignancy that tends to extend beyond the MRI-defined tumor volume. We utilized positron emission tomography (PET) imaging with the radiotracer alpha-[C]methyl-L -tryptophan (AMT) to develop a reliable high-risk gross tumor volume (HR-GTV) method for delineation of glioblastoma. AMT can detect solid tumor mass and tumoral brain infiltration by increased tumoral tryptophan transport and metabolism via the immunosuppressive kynurenine pathway.

Clinical significance of tryptophan metabolism in the nontumoral hemisphere in patients with malignant glioma.

Unlabelled: α-(11)C-methyl-L-tryptophan (AMT) PET allows evaluation of brain serotonin synthesis and can also track upregulation of the immunosuppressive kynurenine pathway in tumor tissue. Increased AMT uptake is a hallmark of World Health Organization grade III-IV gliomas. Our recent study also suggested decreased frontal cortical AMT uptake in glioma patients contralateral to the tumor.

Increased tryptophan uptake on PET has strong independent prognostic value in patients with a previously treated high-grade glioma.

Background: Previously, we demonstrated the high accuracy of alpha-[(11)C]methyl-L-tryptophan (AMT) PET for differentiating recurrent gliomas from radiation injury. The present study evaluated the prognostic value of increased AMT uptake in patients with previously treated high-grade glioma.

Methods: AMT-PET was performed in 39 patients with suspected recurrence of World Health Organization grades III-IV glioma following surgical resection, radiation, and chemotherapy.

Differentiation of glioblastomas from metastatic brain tumors by tryptophan uptake and kinetic analysis: a positron emission tomographic study with magnetic resonance imaging comparison.

Differentiating high-grade gliomas from solitary brain metastases is often difficult by conventional magnetic resonance imaging (MRI); molecular imaging may facilitate such discrimination. We tested the accuracy of α[11C]methyl-l-tryptophan (AMT)-positron emission tomography (PET) to differentiate newly diagnosed glioblastomas from brain metastases. AMT-PET was performed in 36 adults with suspected brain malignancy.

Accurate differentiation of recurrent gliomas from radiation injury by kinetic analysis of α-11C-methyl-L-tryptophan PET.

Unlabelled: PET of amino acid transport and metabolism may be more accurate than conventional neuroimaging in differentiating recurrent gliomas from radiation-induced tissue changes. α-(11)C-methyl-l-tryptophan ((11)C-AMT) is an amino acid PET tracer that is not incorporated into proteins but accumulates in gliomas, mainly because of tumoral transport and metabolism via the immunomodulatory kynurenine pathway. The aim of this study was to evaluate the usefulness of (11)C-AMT PET supplemented by tracer kinetic analysis for distinguishing recurrent gliomas from radiation injury.