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Frequently Asked Questions

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Titolo

Frequently Asked Questions

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How do I define the time origin of a time-intensity curve?

VueBox® features an automatic contrast arrival detection to help determine the best time origin. However, it is important to note that

  • the time origin detected is a suggestion only and should be reviewed by the user before pressing the OK button
  • the time origin will affect mainly 1 perfusion parameter, i.e. the time-related parameter named TTP (Time To Peak), which expresses the time in seconds from the time origin to the peak of the fitted curve.

My ultrasound system does not appear in the list of compatible system, what should I do?

VueBox® can be made compatible with virtually any ultrasound system providing that a calibration file is available.

If an ultrasound system or a specific setting does not appear in the list, contact the Bracco customer support at vuebox@bracco.com.

What does VueBox® measure: brightness, pixel-density or else?

VueBox converts video data (pixel intensity in grey levels) into echo-power data (arbitrary units or [a.u.]), a quantity directly proportional to the instantaneous concentration of contrast agent at each location in the field of view.

This conversion process, called linearization, takes into account color or greyscale rendering, the dynamic range of log-compression used during the clip acquisition and compensates for contrast gain, as long as pixel intensity is not truncated or saturated.

However, echo-power values, either expressed in [a.u.] or in [dB], are absolute values and are tricky to compare as such with data acquired on different systems (and different manufacturers) or from different patients as

(1) the video data compression laws differ from one manufacturer to another. Thus, the comparison of absolute echo-power values, obtained after the decompression of video data using a dedicated calibration setting, is not recommended. Indeed, such values could differ by a factor, which changes according to the system, probe, dynamic range, and colormap used,

(2) and more importantly, the comparison of absolute echo-power values suffers from differences in morphology between patients (e.g. acoustic windows, input functions), which currently, cannot be compensated for.

Therefore, we strongly recommend, whenever possible, to use relative measurements, by selecting a reference ROI (such as an artery, or healthy surrounding tissue), see §4.13.2 and §4.14.1 of the instructions for use for more information. This way, the results obtained become independent of the system used as well as the patient's morphology.

What are the minimum or recommended system requirements?

  Minimum Proposed
CPU Intel® Pentium 4 520 Intel® Core2 Duo E8400 or better
RAM 1 GB 2 GB or more
Graphics Crd Nvidia GeForce 8500GT 512DDR
Minimum Resolution 1024x768
Nvidia GeForce 8800GT 1024DDR
Minimum Resolution 1280x1024 and higher
Monitor 17" SVGA(CRT) 19" TFT Flat Screen or higher

 

Additional Requirements
Operating System Microsoft® VISTA (SP1), 32 bit/64 bit
Microsoft® 7, 32 bit/64 bit
Microsoft® 8, 32 bit/64 bit
Microsoft®10, 32 bit/64 bit
Screen text size 96 dpi

What is the difference between Time To Peak (TTP) and Rise Time (RT)?

The time-related parameter named TTP (Time To Peak) expresses the time in seconds from the time origin to the peak of the fitted curve, while RT (Rise Time) expresses the time from TI (the instant at which the maximum slope tangent intersects the x-axis) to the peak of the fitted curve, and is thus independent of the time origin. More information can be found in the user manual (§4.12.5 Perfusion models).

Can I run VueBox® on a Mac OS?

VueBox can be run on Mac OS providing that a virtual machine application with Windows OS is installed (e.g. VMWare, Parallels, etc.).

What is the difference between the trial and the full versions?

The trial version allows you to test all features of VueBox™ beside the export and saving of results. Additionally, only a set of perfusion parameters is available and this version expires 30 days after activation.

VueBox® can display values in [dB] without selecting a reference ROI, what are these values relative to?

When a reference ROI is selected (checkbox next to ROI names in parameters table), values of amplitude parameters are displayed in [a.u.], [%] and [dB]. In this case, the [dB] column contains values that are relative to this reference and computed as follows:

value_dB = 10 * log10 ( value_au / value_ref_au)

When no reference ROI is selected, values of amplitude parameters are displayed in [a.u.] and [dB]. And in this case, the [dB] are relative to the value 1:

value_dB = 10 * log10 ( value_au / 1)

Thus, without reference ROI, the values expressed in [dB] are likely to vary between patients and US systems, just like [a.u.] ones.

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