Apparent diffusion coefficient and tumor volume measurements help stratify progression-free survival of bevacizumab-treated patients with recurrent glioblastoma multiforme

BACKGROUND

The aim of this study was to determine whether apparent diffusion coefficient (ADC) bi-component curve-fitting histogram analysis and volume percentage change (VPC) prior to bevacizumab treatment can stratify progression-free survival (PFS) and overall survival (OS) in patients with glioblastoma multiforme (GBM) on first recurrence.

METHODS

We retrospectively evaluated 17 patients with recurrent GBM who received bevacizumab and fotemustine (n = 13) or only bevacizumab (n = 4) on first recurrence at our institution between December 2009 and July 2015. Both T2/FLAIR abnormalities and enhancing tumor on T1 images were mapped to the ADC images. ADC-L and ADC-M values were obtained trough bi-Gaussian curve fitting histogram analysis. Furthermore, the study population was dichotomized into two subgroups: patients displaying a reduction in enhancing tumor volume of either >55% or <55% between the mean value calculated at baseline and first follow-up. Subsequently, a second dichotomization was performed according to a reduction in the T2 / FLAIR volume >41% or <41% at first check after treatment. OS and PFS were assessed using volume parameters in a Cox regression model adjusted for significant clinical parameters.

RESULTS

In univariate analysis, contrast-enhanced (CE)-ADC-L was significantly predictive of PFS (p = 0.01) and OS (p = 0.03). When we dichotomized our sample using the 55% cut-off for enhancing tumor volume, CE-VPC was able to predict PFS (p = 0.01) but not OS (p = 0.08). In multivariate analysis, only the CE-ADC-L was predictive of PFS (p = 0.01), albeit not predictive of OS (p = 0.14). CE-ADC-M, T2/FLAIR-ADC-L, T2/FLAIR-ADC, and T2/FLAIR VPC were not significantly predictive of PFS and OS (p > 0.05) in both univariate and multivariate analysis.

CONCLUSIONS

CE-ADC and CE-VPC can stratify PFS for patients with recurrent glioblastoma prior to bevacizumab treatment.

Evolution of epidermoid cyst into dermoid cyst: Embryological explanation and radiological-pathological correlation

Intracranial dermoid and epidermoid cysts are usually considered to be two different entities in the radiological and surgical literature. Epidermoid cysts are classically off midline in location, isointense to cerebrospinal fluid on T1 and T2-weighted images and have restricted diffusion, whereas dermoid cysts are classically midline in location, have T1-hyperintense regions due to the presence of fat and show facilitated diffusion. We report a case of radiological epidermoid cyst in baseline imaging, which evolved into a radiological dermoid cyst over time, and explain this unique occurrence with a review of the embryology and histopathogenesis of these cysts.

Reversible post-traumatic bilateral extensive restricted diffusion of the brain. A case study and review of the literature

PRIMARY OBJECTIVE

To increase the knowledge about diffuse traumatic brain injury (TBI) by reporting the magnetic resonance imaging (MRI) findings observed in a patient with reversible extensive restricted diffusion of the brain at diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps.

CASE STUDY

An 18-year-old patient was admitted after high-energy closed TBI. Glasgow Coma Scale score was 4. Head computed tomography showed small left frontal and temporal haemorrhagic contusions and a small haemorrhage in the left thalamus. Ten days later, brain MRI showed diffuse high-signal intensity on T2-weighted images and DWI and restricted diffusion in the subcortical white matter of both centri semiovali, genu and splenium of corpus callosum and parietal cortex bilaterally (mean ADC value = 0.434-0.811 x 10(-3) mm(2) s(-1)). Eleven days later, follow-up brain MRI showed gliotic changes in the left splenium of corpus callosum, a clearcut decrease of T2-weighted high-signal intensity and resolution of abnormalities at DWI and ADC maps in all other involved sites. This was confirmed 36 days later. Three months later, the patient did not show neurological, cognitive or neuropsychiatric deficits.

CONCLUSIONS

In the patient reported herein, closed TBI most likely induced diffuse excitotoxic injury of the brain which resulted in mainly reversible cytotoxic or intramyelinic oedema.