Disease Assessments in Patients with Glioblastoma

Evaluating the diagnostic ability of treatment response assessment maps (TRAMs)/contrast clearance analysis (CCA) in predicting the presence of active brain tumors

INTRODUCTION

Brain tumors pose significant diagnostic and therapeutic challenges due to their diverse treatment responses and complex imaging characteristics. Traditional MRI techniques often struggle to differentiate between tumor recurrence and post-treatment changes such as pseudoprogression and necrosis, highlighting the need for more accurate diagnostic tools.

MATERIAL AND METHODS

This retrospective study conducted at a single tertiary care center and evaluated the diagnostic efficacy of Treatment Response Assessment Maps (TRAMs), also known as Contrast Clearance Analysis (CCA), in distinguishing between tumor recurrence and post-treatment changes in patients who underwent initial treatment for brain tumors. Data from 27 patients were analyzed, including 10 who underwent surgical resection (Group 1) and 17 who had serial images and TRAMs/CCA assessment (Group 2).

RESULT

In Group 1, TRAMs/CCA demonstrated nine positive results, with 8 cases of tumor recurrence confirmed via biopsy. A biopsy also confirmed one negative result after a discussion with the patient. In Group 2, where patients did not undergo biopsy, TRAMs/CCA results varied but correlated with clinical outcomes, underscoring the potential utility of TRAMs/CCA in guiding treatment decisions. These findings suggest that TRAMs/CCA may have superior diagnostic performance compared to traditional MRI in differentiating between tumors.

CONCLUSION

TRAMs/CCA represents a promising advancement in the imaging assessment of brain tumor treatment response, offering higher sensitivity than conventional MRI methods. While implementing TRAMs/CCA could potentially improve diagnostic accuracy and optimize therapeutic strategies for patients with brain tumors, the final decision remains highly dependent on patient-centered discussions.

Measurable disease as baseline criterion for response assessment in glioblastoma: A comparison of PET -based (PET RANO 1.0) and MRI-based (RANO) assessments

BACKGROUND

Recently, criteria based on amino acid positron emission tomography (PET) have been proposed for response assessment in diffuse gliomas (PET RANO 1.0). In this study, we compare the prevalence of measurable disease according to PET RANO 1.0 with magnetic resonance imaging (MRI)-based Response Assessment in Neuro-Oncology (RANO) criteria in glioblastoma.

METHODS

We retrospectively identified patients with newly diagnosed IDH-wild-type glioblastoma who underwent [18F] Fluoroethyltyrosine (FET) PET and MRI after resection or biopsy and before radio-/radiochemotherapy. Two independent investigators analyzed measurable disease according to PET RANO 1.0 or MRI-RANO criteria. Additionally, lesion size, congruency patterns, and uptake intensity on [18F]FET PET images were assessed.

RESULTS

We evaluated 125 patients including 49 cases after primary resection and 76 cases after biopsy. Using PET criteria, 113 out of 125 patients (90.4%) had measurable disease, with a median PET-positive volume of 15.34 cm3 (8.83-38.03). With MRI, a significantly lower proportion of patients had measurable disease (57/125, 45.6%; P < .001) with a median sum of maximum cross-sectional diameters of 35.65 mm (26.18-45.98). None of the 12 patients without measurable disease on PET had measurable disease on MRI. Contrariwise, 56/68 patients (82.4%) without measurable disease on MRI exhibited measurable disease on PET. Clinical performance status correlated significantly with PET-positive volume and MRI-based sum of diameters (P < .0059, P < .0087, respectively).

CONCLUSIONS

[18F]FET PET identifies a higher number of patients with measurable disease compared to conventional MRI in newly diagnosed glioblastoma. PET-based assessment may serve as a novel baseline parameter for evaluating residual tumor burden and improving patient stratification in glioblastoma studies. Further validation in prospective trials is warranted.

MRI Treatment Response Assessment Maps (TRAMs) for differentiating recurrent glioblastoma from radiation necrosis

BACKGROUND

MRI treatment response assessment maps (TRAMs) were introduced to distinguish recurrent malignant glioma from therapy related changes. TRAMs are calculated with two contrast-enhanced T1-weighted sequences and reflect the "late" wash-out (or contrast clearance) and wash-in of gadolinium. Vital tumor cells are assumed to produce a wash-out because of their high turnover rate and the associated hypervascularization, whereas contrast medium slowly accumulates in scar tissue. To examine the real value of this method, we compared TRAMs with the pathology findings obtained after a second biopsy or surgery when recurrence was suspected.

METHODS

We retrospectively evaluated TRAMs in adult patients with histologically demonstrated glioblastoma, contrast-enhancing tissue and a pre-operative MRI between January 1, 2017, and December 31, 2022. Only patients with a second biopsy or surgery were evaluated. Volumes of the residual tumor, contrast clearance and contrast accumulation before the second surgery were analyzed.

RESULTS

Among 339 patients with mGBM who underwent MRI, we identified 29 repeated surgeries/biopsies in 27 patients 59 ± 12 (mean ± standard deviation) years of age. Twenty-eight biopsies were from patients with recurrent glioblastoma histology, and only one was from a patient with radiation necrosis. We volumetrically evaluated the 29 pre-surgery TRAMs. In recurrent glioblastoma, the ratio of wash-out volume to tumor volume was 36 ± 17% (range 1-73%), and the ratio of the wash-out volume to the sum of wash-out and wash-in volumes was 48 ± 21% (range 22-92%). For the one biopsy with radiation necrosis, the ratios were 42% and 54%, respectively.

CONCLUSIONS

Typical recurrent glioblastoma shows a > 20%ratio of the wash-out volume to the sum of wash-out and wash-in volumes. The one biopsy with radiation necrosis indicated that such necrosis can also produce high wash-out in individual cases. Nevertheless, the additional information provided by TRAMs increases the reliability of diagnosis.