Baseline and early digital [ 18 F]FDG PET/CT and multiparametric MRI contain promising features to predict response to neoadjuvant therapy in locally advanced rectal cancer patients: a pilot study.

Objective: In this pilot study, we investigated the feasibility of response prediction using digital [ 18 F]FDG PET/computed tomography (CT) and multiparametric MRI before, during, and after neoadjuvant chemoradiation therapy in locally advanced rectal cancer (LARC) patients and aimed to select the most promising imaging modalities and timepoints for further investigation in a larger trial.

Methods: Rectal cancer patients scheduled to undergo neoadjuvant chemoradiation therapy were prospectively included in this trial, and underwent multiparametric MRI and [ 18 F]FDG PET/CT before, 2 weeks into, and 6-8 weeks after chemoradiation therapy. Two groups were created based on pathological tumor regression grade, that is, good responders (TRG1-2) and poor responders (TRG3-5).

Implementation of functional imaging using C-methionine PET-CT co-registered with MRI for advanced surgical planning and decision making in prolactinoma surgery.

Purpose: To report the first experience of our multidisciplinary team with functional imaging using C-methionine positron emission tomography-computed tomography (C-methionine PET-CT) co-registered with MRI (Met-PET/MRI) in clinical decision making and surgical planning of patients with difficult to treat prolactinoma.

Methods: In eighteen patients with prolactinoma, referred to our tertiary referral centre because of intolerance or resistance for dopamine agonists (DA), Met-PET/MRI was used to aid decision-making regarding therapy.

Results: Met-PET/MRI was positive in 94% of the patients.

Cerebrovascular reactivity in retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations.

Retinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic manifestations (RVCL-S) is a small vessel disease caused by mutations. RVCL-S is characterized by retinal vasculopathy and brain white matter lesions with and without contrast enhancement. We aimed to investigate cerebrovascular reactivity (CVR) in RVCL-S.

Variability of physiological brain perfusion in healthy subjects - A systematic review of modifiers. Considerations for multi-center ASL studies.

Quantitative measurements of brain perfusion are influenced by perfusion-modifiers. Standardization of measurement conditions and correction for important modifiers is essential to improve accuracy and to facilitate the interpretation of perfusion-derived parameters. An extensive literature search was carried out for factors influencing quantitative measurements of perfusion in the human brain unrelated to medication use.

Cerebral magnetic resonance imaging in quiescent Crohn's disease patients with fatigue.

Aim: To evaluate brain involvement in quiescent Crohn's disease (CD) patients with fatigue using quantitative magnetic resonance imaging (MRI).

Methods: Multiple MRI techniques were used to assess cerebral changes in 20 quiescent CD patients with fatigue (defined with at least 6 points out of an 11-point numeric rating scale compared with 17 healthy age and gender matched controls without fatigue. Furthermore, mental status was assessed by cognitive functioning, based on the neuropsychological inventory including the different domains global cognitive functioning, memory and executive functioning and in addition mood and quality of life scores.

Cerebrovascular function in presymptomatic and symptomatic individuals with hereditary cerebral amyloid angiopathy: a case-control study.

Background: Previous work suggests that impairments of cerebrovascular flow or reactivity might be early markers of cerebral amyloid angiopathy (CAA). Hereditary cerebral haemorrhage with amyloidosis-Dutch type (HCHWA-D) is a genetic form of CAA that can be diagnosed before the onset of clinical symptoms by DNA testing. We aimed to investigate whether haemodynamic measures are decreased in presymptomatic and symptomatic HCHWA-D mutation carriers compared with healthy controls.

Decreased cerebral perfusion in Duchenne muscular dystrophy patients.

Duchenne muscular dystrophy is caused by dystrophin gene mutations which lead to the absence of the protein dystrophin. A significant proportion of patients suffer from learning and behavioural disabilities, in addition to muscle weakness. We have previously shown that these patients have a smaller total brain and grey matter volume, and altered white matter microstructure compared to healthy controls.

Cerebral blood flow in presymptomatic MAPT and GRN mutation carriers: A longitudinal arterial spin labeling study.

Objective: Frontotemporal dementia (FTD) is characterized by behavioral disturbances and language problems. Familial forms can be caused by genetic defects in microtubule-associated protein tau (MAPT), progranulin (GRN), and C9orf72. In light of upcoming clinical trials with potential disease-modifying agents, the development of sensitive biomarkers to evaluate such agents in the earliest stage of FTD is crucial.

Disentangling rectangularization and life span extension with the moving rectangle method.

Purpose: The moving rectangle method is used to disentangle the contributions of rectangularization and life span extension to the increase in life expectancy. It requires the choice of an endpoint of the survival curve that approaches the maximum age at death. We examined the effect of choosing different end points on the outcomes of this method.

Fast cerebral flow territory mapping using vessel encoded dynamic arterial spin labeling (VE-DASL).

Purpose: Whole-brain territory mapping using planning-free vessel-encoded pseudocontinuous arterial-spin-labeling (VE-pCASL) takes approximately 5 min, which is frequently considered too long for standard clinical protocols. In this study, vessel-encoded dynamic-ASL (VE-DASL) is optimized to achieve fast (< 30 s) cerebral flow territory mapping, especially aimed for the acute setting.

Methods: VE-DASL is based on the creation of a continuous stream of magnetically labeled or unlabeled blood with different encoding patterns for each feeding artery, whose inflow into the brain tissue is monitored continuously.

Effects of background suppression on the sensitivity of dual-echo arterial spin labeling MRI for BOLD and CBF signal changes.

Dual-echo arterial spin labeling (DE-ASL) enables the simultaneous acquisition of BOLD and CBF fMRI data and is often used for calibrated BOLD and cerebrovascular CO2 reactivity measurements. DE-ASL, like all ASL techniques, suffers from a low intrinsic CBF SNR, which can be improved by suppressing the background signal via the inclusion of additional inversion pulses. However, until now this approach has been considered to be undesirable for DE-ASL, because the BOLD signal is extracted from the background signal and attenuating the background signal could decrease the sensitivity of DE-ASL scans for BOLD changes.

Assessment of middle cerebral artery diameter during hypocapnia and hypercapnia in humans using ultra-high-field MRI.

In the evaluation of cerebrovascular CO2 reactivity measurements, it is often assumed that the diameter of the large intracranial arteries insonated by transcranial Doppler remains unaffected by changes in arterial CO2 partial pressure. However, the strong cerebral vasodilatory capacity of CO2 challenges this assumption, suggesting that there should be some changes in diameter, even if very small. Data from previous studies on effects of CO2 on cerebral artery diameter [middle cerebral artery (MCA)] have been inconsistent.

Total bolus extraction method improves arterial image quality in dynamic CTAs derived from whole-brain CTP data.

Background and Purposes. The 320-detector row CT scanner enables visualization of whole-brain hemodynamic information (dynamic CT angiography (CTA) derived from CT perfusion scans). However, arterial image quality in dynamic CTA (dCTA) is inferior to arterial image quality in standard CTA.

Time-encoded pseudocontinuous arterial spin labeling: basic properties and timing strategies for human applications.

Purpose: In this study, the basic properties and requirements of time-encoded pseudocontinuous arterial spin labeling (te-pCASL) are investigated. Also, the extra degree of freedom delivered by changing block durations is explored.

Methods: First, the minimal duration of encoding blocks, the influence of cardiac triggering, and the effect of dividing the labeling period into blocks are evaluated.

Acceleration-selective arterial spin labeling.

In this study, a new arterial spin labeling (ASL) method with spatially nonselective labeling is introduced, based on the acceleration of flowing spins, which is able to image brain perfusion with minimal contamination from venous signal. This method is termed acceleration-selective ASL (AccASL) and resembles velocity-selective ASL (VSASL), with the difference that AccASL is able to discriminate between arterial and venous components in a single preparation module due to the higher acceleration on the arterial side of the microvasculature, whereas VSASL cannot make this distinction unless a second labeling module is used. A difference between AccASL and VSASL is that AccASL is mainly cerebral blood volume weighted, whereas VSASL is cerebral blood flow weighted.

Feasibility of pseudocontinuous arterial spin labeling at 7 T with whole-brain coverage.

Object: We studied the feasibility of pseudocontinuous arterial spin labeling (pCASL) at 7 T.

Materials And Methods: Simulations were performed to find the optimal labeling parameters for pCASL, with particular attention to the maximum-allowed specific absorption rate (SAR). Subsequently, pCASL experiments (four volunteers) were performed to find the B1 efficiency at the labeling position with and without high-permittivity pads placed around the head, and to study the optimal labeling duration (four separate volunteers).