Alternatively, use a slide scanner that will scan the specimens onto an optical disc. For these systems, the software program usually allows viewing the specimen on the computer, taking pictures and adjusts scale magnification automatically.

Most image analysis software can perform this task, one of the most common measuring softwares is Image J (available free from the NIH).

Open Image J and drag and drop image onto the Image J tool bar.

Adjust and measure scale bar, by drawing a line across the scale. Subsequently, go to edit option on the toolbar 6 adjust scale bar 6 and write down the length of the scale bar (2–3 cm) corresponding with the pixel dimensions.

Click on the free-style line icon, and draw along the lumen of the artery under high magnification. An alternative method would be utilizing the magic tool, which automatically selects the lumen area accurately, if enough contrast is seen in the image.

Alternatively, the perimeter is calculated initially in a similar fashion to the measurement of area. The area of the artery and its radius (area  =  πr ², where r  =  radius) are calculated from the perimeter value (2πr) that are measured with image J. This alternative method provides an accurate approximation of the lumen areas as it would correct for potential errors in vessel deformity. If the artery is not sectioned perpendicular to its long axis, however, errors could occur.

Click Ctrl  +  M, and a new window will open up with the measurements of the lumen area/perimeter in microns (Fig. 2, one can repeat the step three times and take the average for an accurate assessment).

To measure the thickness of the wall, select the straight line icon and draw a line from the endothelial layer 6 tunica media and usually not the adventitial layer (which could be irregular and not accurately sectioned due to the fragility and variability of the connective tissue). Repeat in four different regions, adjacent to each other (90°) (Fig. 2).

Select all the data in the data viewer, copy and paste into a spreadsheet. Perform analysis, by measuring the mean of the lumen area in all samples—the standard deviation or standard error and the average of all four measurements of the wall thickness.

Data can be expressed as separate graphs or one graph depending on what the researcher wishes to convey. Two separate graphs can be used to depict lumen diameter or cross-sectional area and another as wall thickness. If there are appropriate controls, this would demonstrate vasoconstriction/vasodilation as well as wall remodeling. Another way to show the data would be wall thickness/lumen diameter which increases with increasingly severe vasospasm.

Advantages of assessment of vasospasm based on cross-section measurements of fixed arteries are that it is simple and commonly used. Thickness and cross-section area of different layers of the artery wall can be obtained and other immunohistochemical studies carried out. A wide range of arteries based on the location of hemorrhage can be measured.