Publications by authors named "Rasmus H Hansen"

Article Synopsis
  • Tattoo pigment, particularly iron oxide, can migrate from the skin to regional lymph nodes and internal organs, raising concerns for MRI examinations.
  • In a study with tattooed mice, evaluations showed minimal systemic distribution of these pigments, with no significant impact on the liver, kidney, or brain, and no adverse skin reactions when exposed to a static magnetic field.
  • The research indicated that while tattoo pigments might cause image artefacts during MRI scans, they do not pose significant clinical health risks.
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Article Synopsis
  • Over the past 30 years, tattooed individuals have reported painful reactions during MRI scans, characterized by burning sensations, swelling, and redness, potentially linked to elements in tattoo inks.
  • A case study of a young man with a recent black tattoo showed recurring painful reactions during MRIs, even without magnetic components in the ink, but these reactions lessened over time.
  • The study suggests that the painful sensations may result from interactions between the tattoo's ink and dermal nerves, underlining the need for more research to understand these reactions and develop preventive strategies.
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Intertrochanteric femoral fractures are commonly treated with intramedullary nails (IMNs). A tip-apex distance (TAD) of more than 20-25 mm is associated with an increased risk of cut-out. The Stryker Adaptive Positioning System (ADAPT) is a computer-assisted navigation system designed to reduce TADs.

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Adverse reactions in tattooed skin during magnetic resonance imaging (MRI) are rare but well known. Previous reports describe sudden burning pain in tattooed skin, sometimes accompanied by mild erythema and oedema when entering MRI scanners. The pathophysiology remains unclear, but simple direct thermal heating can be excluded.

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Background: As magnetic resonance imaging (MRI) becomes increasingly integrated into radiotherapy (RT) for enhanced treatment planning and adaptation, the inherent geometric distortion in acquired MR images pose a potential challenge to treatment accuracy. This study aimed to evaluate the geometric distortion levels in the clinical MRI protocols used across Danish RT centers and discuss influence of specific sequence parameters. Based on the variety in geometric performance across centers, we assess if harmonization of MRI sequences is a relevant measure.

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Background: Persons with cosmetic tattoos occasionally experience severe pain and burning sensation on magnetic resonance imaging (MRI).

Objective: To explore the culprit magnetic substances in commonly used permanent makeup inks.

Material And Methods: 20 inks used for cosmetic tattooing of eyebrows, eyeliners, and lips were selected.

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Background And Purpose: With the introduction of hybrid magnetic resonance linacs (MR-linac), improved imaging has enabled daily treatment adaptation. However, the use of gadolinium based contrast agents (GBCAs) is desired to further improve MR image contrast. GBCAs are in the form of a non-toxic metalorganic gadolinium complex, but toxic un-chelated aqueous gadolinium(III), Gd(aq), can be released in patients if the organic ligand is degraded by the radiation.

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New treatments for cerebral small-vessel disease are needed to reduce the risk of small-vessel occlusion stroke and vascular cognitive impairment. We investigated an approach targeted to the signalling molecule cyclic guanosine monophosphate, using the phosphodiesterase 5 inhibitor tadalafil, to explore if it improves cerebral blood flow and endothelial function in patients with cerebral small-vessel disease and stroke. In a randomized, double-blinded, placebo-controlled, cross-over pilot trial (NCT02801032), we included patients who had a previous (>6 months) small-vessel occlusion stroke.

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Tattooed patients undergoing magnetic resonance imaging (MRI) can develop cutaneous complications during the procedure. Our aim was to review all published case reports on MRI-induced tattoo complications to identify a possible pattern. So far, 17 cases have been reported.

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 Electrochemotherapy is an anticancer treatment that uses electric pulses to facilitate uptake of chemotherapeutic drugs in tumor cells and has proven to have a high local cytotoxic effect with minimal adverse events. Electrochemotherapy has mostly been used in treatment of cutaneous metastases but development of a new endoscopic electrode device has made treatment of colorectal tumors possible. This first-in-man multicenter phase I study investigated safety and efficacy of electrochemotherapy using endoscopic electroporation in patients with colorectal tumors.

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Background And Purpose: In radiotherapy, treatment response is generally evaluated many weeks after end of the treatment course. If the treatment outcome could be predicted during radiotherapy better tumour control could be achieved through timely adaptation of the treatment strategy. In this study intra-treatment change based on the diffusion MRI outlined viable tumour volume (VTV) was assessed and compared to the standard GTV to study their outcome prediction capacity.

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Background: The effects of physical exercise in patients with lacunar stroke, seem promising in secondary prevention and only few studies have investigated the effect of high-intensity interval training in patients with lacunar stroke. This study will be investigating whether high-intensity interval training improves cardiovascular fitness as well as cognitive- and endothelial function and potentially attenuating the risk of recurrent stroke.

Methods: A randomized controlled trial evaluating 12 weeks of home-based, high-intensity interval training compared with usual care.

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Background: Electrochemotherapy is an established treatment for cutaneous tumors. This study aimed at determining efficacy of electrochemotherapy in recurrent head and neck cancer.

Methods: Phase II clinical trial in patients with recurrent head and neck carcinomas with no curative treatment options.

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Background: Gene electrotrotransfer describes the use of electric pulses to transfer DNA to cells. Particularly skeletal muscle has potential for systemic secretion of therapeutic proteins. Gene electrotransfer to muscle using the integrin inhibitor plasmid AMEP (Antiangiogenic MEtargidin Peptide) was investigated in a phase I dose escalation study.

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An imaging biomarker for early prediction of treatment response potentially provides a non-invasive tool for better prognostics and individualized management of the disease. Radiotherapy (RT) response is generally related to changes in gross tumor volume manifesting months later. In this prospective study we investigated the apparent diffusion coefficient (ADC), perfusion fraction and pseudo diffusion coefficient derived from diffusion weighted MRI as potential early biomarkers for radiotherapy response of brain metastases.

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Purpose: To evaluate the effect of capecitabine and oxaliplatin before, during, and after radiotherapy for high-risk rectal cancer.

Patients And Methods: Patients with rectum cancer T4 or T3 involving the mesorectal fascia was included in a prospective phase 2 trial. Liver or lung metastases were accepted if the surgeons found them resectable.

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Background: Since multiparametric magnetic resonance imaging (mp-MRI) of the prostate exceeds 30 min, minimizing the evaluation time of significant (Gleason scores > 6) prostate cancer (PCa) would be beneficial. A reduced protocol might be sufficient for the diagnosis.

Purpose: To study whether a short unenhanced biparametric MRI (bp-MRI) matches mp-MRI in detecting significant PCa.

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Regular exercise reduces the risk of cancer and disease recurrence. Yet the mechanisms behind this protection remain to be elucidated. In this study, tumor-bearing mice randomized to voluntary wheel running showed over 60% reduction in tumor incidence and growth across five different tumor models.

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Background: Although diffusion-weighted magnetic resonance imaging (DW-MRI) is widely used in radiation therapy (RT) response studies, no standard of delineating the region of interest (ROI) exists. In this retrospective study, we evaluate the effect of four ROI strategies on the apparent diffusion coefficients (ADC) in patients receiving palliative RT to brain metastases.

Material And Methods: Twenty-two metastases from nine patients, treated with whole-brain irradiation (30 Gy in 10 fractions) were analyzed.

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Purpose: In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to electron density. To solve the task, voxel-based or atlas-based models have typically been used.

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Background: Tissue permeabilization by electroporation (EP) is a promising technique to treat certain cancers. Non-invasive methods for verification of induced permeabilization are important, especially in deep-seated cancers. In this study we evaluated diffusion-weighted magnetic resonance imaging (DW-MRI) as a quantitative method for detecting EP-induced membrane permeabilization of brain tissue using a rat brain model.

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Objective: Follistatin-like 3 (fstl3), a natural inhibitor of members of the TGF-β family, increases during resistance training in human plasma. Fstl3 primarily binds myostatin and activin A, and thereby inhibits their functions. We hypothesize that blocking myostatin and activin A signalling through systemic fstl3 over-expression protects against diet-induced obesity and insulin resistance.

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Radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, so-called MRI-only RT, would remove the systematic registration error between MR and computed tomography (CT), and provide co-registered MRI for assessment of treatment response and adaptive RT. Electron densities, however, need to be assigned to the MRI images for dose calculation and patient setup based on digitally reconstructed radiographs (DRRs). Here, we investigate the geometric and dosimetric performance for a number of popular voxel-based methods to generate a so-called pseudo CT (pCT).

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Background: Computed tomography (CT) urography is now used in the work-up of patients with hematuria. The dose of contrast medium and radiation varies considerably between the different CT protocols.

Purpose: To study the disease prevalence in a consecutive group of patients with hematuria undergoing CT urography with a low dose of contrast medium and radiation.

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