Publications by authors named "Harald Groen"

Background And Objective: Image-guided surgical navigation (IGSN) can enhance surgical precision and safety. The expansion of minimally invasive surgery has increased the demand for integration of these navigation systems into robot-assisted surgery. Our objective was to evaluate the integration of electromagnetic tracking with IGSN in robot-assisted sentinel lymph node biopsy (SLNB).

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Purpose Of The Report: Localization techniques are needed to facilitate resection of nonpalpable lesions. In this study, the feasibility of radio-guided occult lesion localization (ROLL) with 99m Tc is investigated for the localization of nonpalpable, small, suspicious, or proven melanoma or soft tissue sarcoma lesions at various locations throughout the body.

Patients And Methods: Patients with nonpalpable, suspicious, or proven melanoma or soft tissue sarcoma lesions were selected for this study.

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Introduction: Anastomotic leakage after gastrointestinal surgery has a high impact on patient's quality of life and its origin is associated with inadequate perfusion. Imaging photoplethysmography (iPPG) is a noninvasive imaging technique that measures blood-volume changes in the microvascular tissue bed and detects changes in tissue perfusion.

Materials And Methods: Intraoperative iPPG imaging was performed in 29 patients undergoing an open segment resection of the small intestine or colon.

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Surgery for locally recurrent rectal cancer (LRRC) presents several challenges, which is why the percentage of inadequate resections of these tumors is high. In this exploratory study, we evaluate the use of image-guided surgical navigation during resection of LRRC. Patients who were scheduled to undergo surgical resection of LRRC who were deemed by the multidisciplinary team to be at a high risk of inadequate tumor resection were selected to undergo surgical navigation.

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Surgical excision is the golden standard for treatment of intestinal tumors. In this surgical procedure, inadequate perfusion of the anastomosis can lead to postoperative complications, such as anastomotic leakages. Imaging photoplethysmography (iPPG) can potentially provide objective and real-time feedback of the perfusion status of tissues.

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Background: This study assessed whether electromagnetic navigation can be of added value during resection of recurrent or post-therapy intra-abdominal/pelvic soft tissue sarcomas (STS) in challenging locations.

Materials And Methods: Patients were included in a prospective navigation study. A pre-operatively 3D roadmap was made and tracked using electromagnetic reference markers.

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Importance: The percentage of tumor-positive surgical resection margin rates in patients treated for locally advanced primary or recurrent rectal cancer is high. Image-guided navigation may improve complete resection rates.

Objective: To ascertain whether image-guided navigation during rectal cancer resection improves complete resection rates compared with surgical procedures without navigation.

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In the past decades, image-guided surgery has evolved rapidly. In procedures with a relatively fixed target area, like neurosurgery and orthopedics, this has led to improved patient outcomes. In cancer surgery, intraoperative guidance could be of great benefit to secure radical resection margins since residual disease is associated with local recurrence and poor survival.

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A dynamic Tc tracer experiment was performed to investigate the capabilities of combined preclinical single photon emission computed tomography (SPECT) and X-ray computed tomography (CT) for investigating transport in a heterogeneous porous medium. The experiment was conducted by continuously injecting a Tc solution into a column packed with eight layers (i.e.

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Introduction: Triamcinolone acetonide (TA) is used for osteoarthritis management to reduce pain, and pre-clinical studies have shown that TA limits osteophyte formation. Osteophyte formation is known to be facilitated by synovial macrophage activation. TA injections might influence macrophage activation and subsequently reduce osteophytosis.

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Radiolabeled somatostatin (SST) analogs, used to visualize and treat SST receptor (SSTR)-expressing neuroendocrine tumors, also accumulate in the spleen. There is a high interpatient variation and no significant radiation-induced splenic toxicity; however, an absorbed dose-related reduction in spleen size was detected. However, the exact localization of radioactivity and the role of SST receptors in splenic retention are unknown.

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Limited spatial resolution of preclinical positron emission tomography (PET) and single-photon emission computed tomography (SPECT) has slowed down applications of molecular imaging in small animals. Here we present the latest-generation U-SPECT system (U-SPECT⁺, MILabs, Utrecht, the Netherlands) enabling radionuclide imaging of mice with quarter-millimeter resolution. The system was equipped with the newest high-resolution collimator with 0.

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Background: Previously, we reported on the unexpected development of distant metastases in the subcutaneous rat pancreas CA20948 tumor model after 4.5 weeks of treatment with RAD001-only or in combination with [(177)Lu-DOTA(0),Tyr(3)]octreotate ((177)Lu-DOTATATE) (Cancer Res. 73:12-8, 2013).

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Atherosclerotic plaque composition can indicate plaque vulnerability. We segment atherosclerotic plaque components from the carotid artery on a combination of in vivo MRI and CT-angiography (CTA) data using supervised voxelwise classification. In contrast to previous studies the ground truth for training is directly obtained from 3D registration with histology for fibrous and lipid-rich necrotic tissue, and with μCT for calcification.

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The need for noninvasive imaging to distinguish stable from vulnerable atherosclerotic plaques is evident. Activated macrophages play a role in atherosclerosis and express folate receptor folate receptor β (FR-β). The feasibility of folate targeting to detect atherosclerosis was demonstrated in human and mouse plaques, and it was suggested that molecular imaging of FR-β through folate conjugates might be a specific marker for plaque vulnerability.

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Introduction: Articular cartilage needs sulfated-glycosaminoglycans (sGAGs) to withstand high pressures while mechanically loaded. Chondrocyte sGAG synthesis is regulated by exposure to compressive forces. Moderate physical exercise is known to improve cartilage sGAG content and might protect against osteoarthritis (OA).

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Although efficient delivery and distribution of treatment agents over the whole tumor is essential for successful tumor treatment, the distribution of most of these agents cannot be visualized. However, with single-photon emission computed tomography (SPECT), both delivery and uptake of radiolabeled peptides can be visualized in a neuroendocrine tumor model overexpressing somatostatin receptors. A heterogeneous peptide uptake is often observed in these tumors.

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Background: Histology sections provide accurate information on atherosclerotic plaque composition, and are used in various applications. To our knowledge, no automated systems for plaque component segmentation in histology sections currently exist.

Materials And Methods: We perform pixel-wise classification of fibrous, lipid, and necrotic tissue in Elastica Von Gieson-stained histology sections, using features based on color channel intensity and local image texture and structure.

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Objective: Although articular cartilage has evolved to facilitate joint mobilization, severe loading can induce chondrocyte apoptosis, which is related to the progression of osteoarthritis (OA). To avoid apoptosis, chondrocytes synthesize heat-shock proteins (HSPs). This study was undertaken to examine the roles of Hsp70 and Hsp90 in biomechanically induced OA, and the possibility of using Hsp90 inhibition as an intervention strategy for OA management.

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Aims: Atherosclerotic plaques develop at low shear stress locations in the arterial tree. However, at a certain moment, plaques encroach into the lumen causing local wall shear stress (WSS) increase. Minimal information is available on the relationship between WSS and plaque composition.

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Whole-body SPECT small animal imaging is used to study cancer, and plays an important role in the development of new drugs. Comparing and exploring whole-body datasets can be a difficult and time-consuming task due to the inherent heterogeneity of the data (high volume/throughput, multi-modality, postural and positioning variability). The goal of this study was to provide a method to align and compare side-by-side multiple whole-body skeleton SPECT datasets in a common reference, thus eliminating acquisition variability that exists between the subjects in cross-sectional and multi-modal studies.

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Objective: Atherosclerosis preferentially develops at sites of disturbed blood flow. We tested the hypothesis that transglutaminase activity plays a role in plaque development at these locations.

Methods And Results: Exposure of endothelial cells to steady flow (7 dynes/cm(2)) was associated with relatively low transglutaminase activity, whereas under low oscillatory flow (1.

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We present a new method for automated characterization of atherosclerotic plaque composition in ex vivo MRI. It uses MRI intensities as well as four other types of features: smoothed, gradient magnitude and Laplacian images at several scales, and the distances to the lumen and outer vessel wall. The ground truth for fibrous, necrotic and calcified tissue was provided by histology and μCT in 12 carotid plaque specimens.

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Patient specific geometrical data on human coronary arteries can be reliably obtained multislice computer tomography (MSCT) imaging. MSCT cannot provide hemodynamic variables, and the outflow through the side branches must be estimated. The impact of two different models to determine flow through the side branches on the wall shear stress (WSS) distribution in patient specific geometries is evaluated.

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