Publications by authors named "Marnix Maas"

Objectives: Accurate lymph node (LN) staging is crucial for managing upper abdominal cancers. Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging effectively distinguishes healthy and metastatic LNs through fat/water and -weighted imaging. However, respiratory motion artifacts complicate detection of abdominal LNs.

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Objectives: To assess 3-Tesla (3-T) ultra-small superparamagnetic iron oxide (USPIO)-enhanced MRI in detecting lymph node (LN) metastases for resectable adenocarcinomas of the pancreas, duodenum, or periampullary region in a node-to-node validation against histopathology.

Methods: Twenty-seven consecutive patients with a resectable pancreatic, duodenal, or periampullary adenocarcinoma were enrolled in this prospective single expert centre study. Ferumoxtran-10-enhanced 3-T MRI was performed pre-surgery.

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Ultrahigh field magnetic resonance imaging (MRI) (≥ 7 T) has the potential to provide superior spatial resolution and unique image contrast. Apart from radiofrequency transmit inhomogeneities in the body at this field strength, imaging of the upper abdomen faces additional challenges associated with motion-induced ghosting artifacts. To address these challenges, the goal of this work was to develop a technique for high-resolution free-breathing upper abdominal MRI at 7 T with a large field of view.

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This study evaluated the relationship between apparent diffusion coefficient (ADC) values in pancreatic ductal adenocarcinoma (PDAC) and tumor grades based on WHO, Adsay, and Kalimuthu classifications, using whole-mount pancreatectomy specimens. If glandular formation plays a key role in the degree of diffusion restriction, diffusion-weighted imaging could facilitate non-invasive grading of PDAC. A freehand region of interest (ROI) was drawn along tumor borders on the preoperative ADC map in each tumor-containing slice.

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Introduction: The INflammation and Small Vessel Disease (INSVD) study aims to investigate whether peripheral inflammation, immune (dys)regulation and blood-brain barrier (BBB) permeability relate to disease progression in cerebral small vessel disease (SVD). This research aims to pinpoint specific components of the immune response in SVD relating to disease progression. This could identify biomarkers of SVD progression, as well as potential therapeutic targets to inform the development and repurposing of drugs to reduce or prevent SVD, cognitive decline and vascular dementia.

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Background: Accurate detection of lymph node (LN) metastases in prostate cancer (PCa) is a challenging but crucial step for disease staging. Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) enables distinction between healthy LNs and nodes suspicious for harboring metastases. When combined with MRI at an ultra-high magnetic field, an unprecedented spatial resolution can be exploited to visualize these LNs.

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Purpose: To increase the effectiveness of respiratory gating in radial stack-of-stars MRI, particularly when imaging at high spatial resolutions or with multiple echoes.

Methods: Free induction decay (FID) navigators were integrated into a three-dimensional gradient echo radial stack-of-stars pulse sequence. These navigators provided a motion signal with a high temporal resolution, which allowed single-spoke binning (SSB): each spoke at each phase encode step was sorted individually to the corresponding motion state of the respiratory signal.

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Article Synopsis
  • * The study involves 50 participants who will temporarily stop their antihypertensive medication to observe changes in blood pressure and its impact on brain health using various MRI techniques and clinical assessments.
  • * Findings from the study aim to shed light on how hypertension might lead to SVD, potentially leading to new treatment strategies to prevent or slow down this disease in the future.
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Rationale And Objectives: To assess the acquisition time and image quality of simultaneous multislice-accelerated diffusion-weighted imaging (SMS-DWI) versus conventional DWI (C-DWI) of the rectum.

Materials And Methods: In patients scheduled for a magnetic resonance imaging of the rectum, both SMS-DWI and C-DWI were performed on a 3T whole body magnetic resonance scanner. Image quality of the DWI sequences was reviewed by two independent radiologists who were blinded to the method of imaging using a five-point Likert scale: (score ranging from 1 (non-diagnostic) to 5 (excellent).

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Introduction: In order to augment the certainty of the radiological interpretation of "possible microbleeds" after traumatic brain injury (TBI), we assessed their longitudinal evolution on 3-T SWI in patients with moderate/severe TBI.

Methods: Standardized 3-T SWI and T1-weighted imaging were obtained 3 and 26 weeks after TBI in 31 patients. Their microbleeds were computer-aided detected and classified by a neuroradiologist as no, possible, or definite at baseline and follow-up, separately (single-scan evaluation).

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T-weighted (TW) MRI provides high spatial resolution and tissue-specific contrast, but it is predominantly used for qualitative evaluation of prostate anatomy and anomalies. This retrospective multicenter study evaluated the potential of TW image-derived textural features for quantitative assessment of peripheral zone prostate cancer (PCa) aggressiveness. A standardized preoperative multiparametric MRI was performed on 87 PCa patients across 6 institutions.

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Key Points: The post-exercise recovery of phosphocreatine, a measure of the oxidative capacity of muscles, as assessed by P MR spectroscopy, shows a striking increase from distal to proximal along the human tibialis anterior muscle. To investigate why this muscle exhibits a greater oxidative capacity proximally, we tested whether the spatial variation in phosphocreatine recovery rate is related to oxygen supply, muscle fibre type or type of exercise. We revealed that oxygen supply also increases from distal to proximal along the tibialis anterior, and that it strongly correlated with phosphocreatine recovery.

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  • A study aimed to define a baseline for pelvic lymph nodes using advanced 7 Tesla MRI to improve validation and assessment of lymph node dissections in pelvic cancers.
  • The research involved imaging 11 healthy volunteers, resulting in the detection of 564 lymph nodes, with an average of 51.3 nodes per person and a significant portion being small (≤2 mm in diameter).
  • Findings indicate substantial variation in the number of visible lymph nodes among individuals, but a consistent size distribution, suggesting that the many small nodes pose challenges for effective surgical removal and detection of metastases.
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Background: Current intraoperative methods of visual inspection and tissue palpation by the surgeon, and frozen section analysis cannot reliably prevent inadequate surgical margins in patients treated for oral squamous-cell carcinoma (OSCC). This study assessed feasibility of MRI for the assessment of surgical resection margins in fresh OSCC specimens.

Methods: Ten consecutive tongue specimens containing OSCC were scanned using 3 T clinical whole-body MRI.

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Purpose: To evaluate the technical feasibility of high-resolution USPIO-enhanced magnetic resonance imaging of pelvic lymph nodes (LNs) at ultrahigh magnetic field strength.

Materials And Methods: The ethics review board approved this study and written informed consent was obtained from all patients. Three patients with rectal cancer and three selected patients with (recurrent) prostate cancer were examined at 7-T 24-36 h after intravenous ferumoxtran-10 administration; rectal cancer patients also received a 3-T MRI.

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Objectives: The aims of this study were to assess the discriminative performance of quantitative multiparametric magnetic resonance imaging (mpMRI) between prostate cancer and noncancer tissues and between tumor grade groups (GGs) in a multicenter, single-vendor study, and to investigate to what extent site-specific differences affect variations in mpMRI parameters.

Materials And Methods: Fifty patients with biopsy-proven prostate cancer from 5 institutions underwent a standardized preoperative mpMRI protocol. Based on the evaluation of whole-mount histopathology sections, regions of interest were placed on axial T2-weighed MRI scans in cancer and noncancer peripheral zone (PZ) and transition zone (TZ) tissue.

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Phosphorus magnetic resonance spectroscopy (P MRS) has been employed before to assess phosphocreatine (PCr) and other high-energy phosphates in the visual cortex during visual stimulation with inconsistent results. We performed functional P MRS imaging in the visual cortex and control regions during a visual stimulation paradigm at an unprecedented sensitivity, exploiting a dedicated RF coil design at a 7 T MR system. Visual stimulation in a 3 min 24 s on-off paradigm in eight young healthy adults generated a clear BOLD effect with traditional H functional MRI in the visual cortex (average z score 9.

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Objectives: Inclusion of 3-dimensional H magnetic resonance spectroscopic imaging (3D-H-MRSI) in routine multiparametric MRI of the prostate requires good quality spectra and easy interpretable metabolite maps of the whole organ obtained without endorectal coil in clinically feasible acquisition times. We evaluated if a semi-LASER pulse sequence with gradient offset independent adiabaticity refocusing pulses (GOIA-sLASER) for volume selection can meet these requirements.

Materials And Methods: Thirteen patients with suspicion of prostate cancer and 1 patient known to have prostate cancer were examined at 3 T with a multichannel body-receive coil.

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Objective: Ultrafast dynamic contrast-enhanced magnetic resonance imaging of the breast enables assessment of the contrast inflow dynamics while providing images with diagnostic spatial resolution. However, the slice thickness of common ultrafast techniques still prevents multiplanar reconstruction. In addition, some temporal blurring of the enhancement characteristics occurs in case view-sharing is used.

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Objectives: The aim of this study was to evaluate the technical feasibility of prostate multiparametric magnetic resonance imaging (mpMRI) at a magnetic field strength of 7 T.

Materials And Methods: In this prospective institutional review board-approved study, 14 patients with biopsy-proven prostate cancer (mean age, 65.2 years; median prostate-specific antigen [PSA], 6.

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Article Synopsis
  • A new method using ultrahigh-field MRI enables improved imaging of pelvic lymph node (PLN) metastases, which are often very small and difficult to detect.
  • Researchers tested a specific multi-gradient echo and gradient echo sequence on a 7 Tesla MRI system with six healthy volunteers, aiming to enhance image quality.
  • The results showed successful detection of lymph nodes as small as 1.5 mm, demonstrating high-resolution imaging capabilities that may aid in identifying small PLN metastases in the future.
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An often-employed strategy to enhance signals in (31) P MRS is the generation of the nuclear Overhauser effect (NOE) by saturation of the water resonance. However, NOE allegedly increases the variability of the (31) P data, because variation is reported in NOE enhancements. This would negate the signal-to-noise (SNR) gain it generates.

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Article Synopsis
  • The study aimed to link metabolite levels from MR spectroscopic imaging with prostate tissue composition analyzed through digital imaging of histologic sections in prostate cancer patients.
  • It involved 57 cancer patients who had MR exams followed by prostate removal, with tissue sections analyzed for nuclei, lumen, and cytoplasm/stroma ratios, correlating these with imaging data.
  • Results indicated that certain metabolite ratios and apparent diffusion coefficients (ADCs) were significantly associated with tissue composition, showing key differences between benign and tumor tissue in the prostate.
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  • The study aimed to evaluate the use of low-power spectral-spatial (SPSP) pulses for prostate MRI spectroscopic imaging (MRSI) at 7T, focusing on optimizing spectral and spatial selectivity simultaneously.
  • Using a specialized double spin-echo sequence, researchers successfully conducted 3D (1)H-MRSI on prostate cancer patients and a healthy subject, without needing additional water or lipid suppression.
  • The results showed that MRSI could be carried out safely within SAR limits in about 10 minutes, revealing distinctive prostate spectral signals while highlighting some limitations in suppressing edge lipid signals.
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