Epicardial adipose tissue imaged by magnetic resonance imaging: an important risk marker of cardiovascular disease.
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Adipose Tissue↗
Biomedical subjects
B Velthuis
Publications and source records attributed to B Velthuis.
Influence of partial volume on venous output and arterial input function.
BACKGROUND: CT perfusion (CTP) is an important diagnostic tool for the imaging of cerebral hemodynamics. To obtain quantitative values of cerebral blood volume (CBV), blood flow (CBF), and mean transit time (MTT), measurement of the arterial input function (AIF) is required. To correct for partial volume effects (PVEs), it is common to normalize the AIF with respect to the venous output function (VOF). This correction assumes that measurement of the VOF is unhampered by PVEs. The purpose of this study was to evaluate the effect of PVE on the measurement of the AIF and VOF and, consequently, on the absolute perfusion parameters. METHODS: In 10 patients the mean area under the curve (AUC) of the AIF and VOF were quantified for 3-, 6-, and 12-mm-thick sections. Differences in the mean (1) AUC of the VOF, (2) AUC of the AIF, and (3) width of the AIF were compared for the 3 section thicknesses, and the influence on the absolute values of CBV, CBF, and MTT were studied. RESULTS: With thinner sections, the AUC of the VOF and the AIF increased significantly and the width of the AIF decreased slightly. Differences in AUC between the 3 section thicknesses were larger for the AIF than for the VOF. CONCLUSION: PVEs affect not only the AIF, but also the VOF. This results in an overestimation of CBV and CBF when a thicker section is used. To avoid PVE, VOF measurements should be performed at lower section thicknesses.
Area Under Curve↗
Minimizing clip artifacts in multi CT angiography of clipped patients.
PURPOSE: To optimize the multi CTA (MSCTA) protocol, the influence of pitch, kilovoltage peak (kVp), reconstruction algorithm, type, and orientation of the clip on clip-induced artifacts was investigated in a phantom study. Also, the influence of kVp, concentration of contrast material, and clip orientation in clipped patients was studied. METHODS: A phantom containing a clip was scanned with varying parameters. Artifact was quantified with 3D volumetry. Artifact volumes were compared for the different parameters. In addition, the number of artifact streaks was presented as a function of the pitch. Five clipped patients were scanned with 90 kVp and 120 kVp and 5 with 120 kVp and 140 kVp. The artifact area was compared. The visualization at the clip site was evaluated for different clip orientations in 50 patients, and for 140 kVp with 370 mg iodine/mL contrast (I/mL) compared with 120 kVp/300 mg I/mL in 7 patients. RESULTS: Up to a pitch of 0.6, there was hardly an increase in artifact. Higher kVp and linear interpolation resulted in fewer artifacts. Alloy clips containing cobalt produced more artifact than did titanium clips. Clips positioned perpendicular to the scan plane led to significantly less artifact. In patients with clips, scanning with 140 kVp/370 mgI/mL led to a decrease of artifact area and a better visualization of the clip site. The visualization at the clip site was also better for clips perpendicular to the scan plane. CONCLUSIONS: If clip artifacts are to be minimized, we suggest scanning with a pitch of 0.6, by using 140 kVp and 370 mgI/mL contrast.
Artifacts↗
Psychosocial problems arising from home ventilation.
OBJECTIVE: To study psychosocial questions and problems of patients, who are chronically dependent on artificial ventilation, and their families. DESIGN: A total of 38 patients and family members (n = 43) were randomly selected. Several patients (n = 12) received respiratory support by nasal mask; the majority (n = 26) received respiratory support via a tracheotomy tube. Semistructured interviews were conducted. The Visual Analog Scale was also used. The extent to which the illness and chronic respiratory support were experienced as emotionally stressful, both by the patients and family members, was marked, on a scale ranging from 0 (light) to 10 (severe). RESULTS: Differences and similarities in the problems experienced were found among the patients and their families. Particularly in the case of patients receiving respiratory support by tracheostomy ventilation 24 hr/day, emotional stress on the family caregivers increased during the course of years. That the patient should urgently require bronchial suctioning at any moment made caregivers very anxious. However, several patients demonstrated increased skills in survival coping strategies. Despite diverse problems, the patients and their caregivers would elect to receive respiratory support, if the opportunity arose. CONCLUSIONS: In the case of chronically ill patients who receive continuous respiratory support via a tracheotomy tube, there is greater need for psychosocial support. Family members, who must be available 24 hr a day, need psychosocial support, professional home care, and voluntary assistance that have not been previously offered.
Adult↗