Osirix Trial

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If you are an experienced cardiovascular KOLs, interested in learning more about the medical potential of this software, IMAGEENS is offering a free trial, for a limited time period and a selection of KOLs only.

ArtFun+ measure arterial stiffness and flow biomarkers that are commonly recognized as a major risk factor for CV diseases and significant predictors of mortality and hard cardiovascular events.

Redheuil A, Bluemke DA, Lima JAC et. al. Proximal aortic distensibility is an independent predictor of all-cause mortality and incident CV events: the MESA study. J Am Coll Cardiol. 2014 Dec.

Sylvian fissure (SF) is an important corridor in neurosurgery, and the end of sylvian fissure (eSF) represents the optimal target area to expose suitable recipient artery in STA-MCA bypass. Unfortunately little have been addressed concerning its relationship with external cranial surface.

SSs were all located below SF at 0 cm. At a distance of 0 to 1.5 cm, SSs were located above SF, then started to merge and went side by side from 2 cm anteriorly. Anterior sylvian point, the most anterior part of SF, was found at 4 cm from OM line. Inferior Rolandic point, which corresponds to the central sulcus inferior extent, was found to be at 2 cm from OM line. The eSF was identified at 0 cm anteriorly from OM, and perpendicularly 1.5 cm above SS. 50% patients had Chater's point (CP) above eSF. Average value for CP was 0.01 below eSF, giving a significantly closer value compared to the one of SS (p

The course of SF and its correlation to SS have been identified, and this is also the first study to investigate the relationship of SS and eSF using OSIRIX DICOM viewer. SS is also comparable to CP, therefore it is usable for a simple landmark of eSF.

Copyright: 2011 Rahmah et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Ribas et al.[8] studied the correlation of anterior sylvian point and external cranial surface. They found out that the anterior sylvian point was located underneath the 1.5-cm-diameter cranial area of the anterior aspect of the squamous suture (SS). Gibo et al. in their study of microsurgical anatomy of the middle cerebral artery mentioned a distance from external auditory meatus (EAM) to anterior part of the SF was 47 mm.[9] However, those studies were cadaveric studies and no studies have mentioned in details the correlation of SF and SS.

In this study, we are aiming at finding out the actual correlation between the two from patient's images. SS can be easily observed during surgery, therefore using SS as a surface landmark for SF will give advantages to surgeons without the need of using expensive technology.

This study was approved by the local Ethical Committee of Shinshu University School of Medicine under registration number of 1359 and written informed consent was obtained from all the patients who participated in the clinical trials.

Osirix 3.3.2-DICOM viewer for Mac OS X was used. Images were viewed using two-dimensional (2D) multi planar reconstruction (MPR) with sagittal view as the center of orientation. Horizontal and vertical lines were adjusted until the standard orbito meatal (OM) plane was observed; it was defined as the plane between the largest lens seen and EAM (Figure 1). Balance between axial, coronal and sagittal view was adjusted by examiner. To demonstrate clearly SS and SF, image brightness was adjusted using the available tool by dragging the mouse around the image. By using the sagittal view as the orientation, blue horizontal line and red vertical line were seen. It was rotatable 360 on its arm, and could be moved vertically or horizontally on its center. The horizontal line was placed along the OM line, and the vertical line was placed perpendicular to OM line just on the EAM.

Orbitomeatal (OM) line is drawn to define the base of measurement. Perpendicular line to EAM is drawn, and is regarded as horizontal 0 cm. Curved-black line is showing SF. White line is SS. Dotted lines are showing the measurement points, from 0 to 4 cm anteriorly.

The length of SS was created by drawing a perpendicular line from OM to the point of SS observed on coronal view. The length of SF was also created in a similar fashion. The length of both SS and SF was measured at 0, 1, 1.5, 2, 2.5, 3, 3.5, and 4 cm from EAM, respectively. Region of interest (ROI) was saved as distance value (in centimeter). Measurement was performed on right and left sides (Figure 2).

a) Coronal view of default window/width level, which can show better visualization of the brain and vessels. b) Coronal bone window view, which can show a better visualization of the SS. White triangle is showing the length of SS, and white dot is showing the length of SF. c) Overall view of 2-D MPR; Crossed lines on sagittal image are movable to desired locations.

Another aspect that we would like to find out is comparison between our method using SS and the standard Chater's point (CP). In 1976, Chater et al. mentioned a point of 6 cm above the EAM perpendicular to skull base line as a surface landmark for the end of sylvian fissure (eSF), which was used for identifying the vessels around angular gyrus in bypass surgery.[9],[10]. CP was then created by drawing 6 cm perpendicular line on coronal view which synchronized the position generated on sagittal view. A point on the bone was connected to a point on SF, and region of interest (ROI) was saved as distance value (in centimeter). Another line for comparison was drawn from SS seen on the same coronal view to the exact point on SF measured before (Figure 3). Again, ROI was saved and used for analysis later.

Orbitomeatal (OM) line is drawn to define the base of measurement. Perpendicular line to EAM is drawn, and is regarded as horizontal 0 cm. Small-dotted line is showing the sylvian fissure. Curved-black line is SS. Bigger dotted line is showing the presumed position of CP, 6 cm from EAM.

Statistical analysis was performed using SPSS 14 for windows. T test was used to compare means between two independent variables. The level of significance (p) was set at a probability value of less than 0.05.

Patients who underwent the 3D-CTA examination were mostly aneurismal patients (33), followed by infarctions, cerebral arteriovenous malformation, tumors, and subarachnoid hemorrhage (SAH; 6, 4, 4, and 3 patients, respectively). No significant mass effect was found in the series. Patients with obvious widening of SF (caused by age-related atrophy, tumor or SAH) were excluded. 3 SAH patients in our series were minor SAH and they did not cause obvious changes of SF size. All patients' data in a form of DICOM files were easily opened using Osirix DICOM viewer. SS and SF could be viewed in all 50 patients.

Distance of SS and the standard CP from SF showed interesting results. On the right side, SSs were all located below SF in 50 patients, with an average of 1.52 cm below the SF at the EAM level perpendicular to OM line. 25 (50%) patients had CP above SF. Average value for CP was 0.01 below SF, which was significantly closer compared to SS on the same coronal plane (p

a) Skin marking of the OM line (black line), the donor artery (STA, red line) and Chater's Point (CP, blue star). b) Bone marking using SS as the center of the craniotomy, the adjacent STA is also visible; blue star is showing the CP. c) The clearly viewed SF with its correlated arties and veins at the center of the operative field after craniotomy. d) Illustration of the running SS (dotted red line), SF (dotted black line), CP (blue star) and start point of SS at 0 cm perpendicular to OM line (red circle).

Another study by Kadri et al. in attempt to find the more proximal segment of the STA found a surface landmark of a perpendicular line measuring 5 cm in length drawn from a point two-thirds the distance from the lateral canthus to tragus would expose the eSF. In their study, the M4 branch larger than 1 mm was found in 93% of the specimens.[20] However, the study used a skin marking in cadaver, thus, raising a concern during actual surgery where a skin is usually flapped to one side before opening the skull, and the marking position could be changed from the previously planned position. Pena-Tapia et al. tried to answer this question. They designed a marking template made of stiff, transparent plastic material with two intersecting lines representing the OM line and the 6 cm perpendicular line. The template was then employed together with MRI during presurgical planning.[21] This procedure did give a proper location of eSF, however, the use of template was not an affordable method in all centers.

Anterior sylvian point (ASP), which divides SF in its main anterior and posterior rami, was considered as a good microsurgical starting point for anatomical orientation for SF opening.[8] Ribas et al. in their cadaveric study found out that ASP was located at the anterior aspect of SS just behind the pterion, was located 0.180.41 cm superior to anterior squamous point and 0.020.53 cm posterior to anterior squamous point.[8] Gibo et al. in their middle cerebral artery study found out that a distance between EAM and ASP was 47 mm.[23].

Another interesting point is a landmark for the inferior rolandic point, which corresponds to the central sulcus inferior extent projection to SF. Ribas et al. studied its position relative to the external cranial surface, and they found out that the superior squamous point was situated along the most superior segment of the SS, with an average height of 4.020.49 cm measured from preauricular depression point.[24] Our result showed that highest value of SS was located at 2 cm on the right side (averaged 4.92 cm) and 1.5 cm on the left side (averaged 4.97 cm) measured from a perpendicular line to OM line. The highest point of SS in our result showed no significant difference to its correspondent SF, demonstrating the start point of intersection between SF and SS. Thus, it confirmed the result mentioned by Ribas et al. where the superior squamous point was found superior to SF in 5 specimens (16%), at SF level in 20 specimen (65%), and inferior to SF in six (19%).[24]

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