Thoracic Imaging

Preclinical medical imaging scanners have recently become more readily available. Using a flexiVent system to control these devices can reduce scan times and dramatically improve the quality of thoracic images.

Improved Thoracic Imaging

  • With its ability to provide precise mechanical ventilation and execute a wide variety of programmable recruitment and breath hold manoeuvres, the flexiVent is the ideal tool for obtaining better in-vivo thoracic images in less time. The flexiVent permits standardization of the lung condition and breath-holds at user-defined lung pressures or volumes while the imaging scanner is pulsatile gated in order to perform image acquisition. We offer a number of custom templates and cables for a range commercial imaging scanners.

Imaging Challenges

  • Over recent years, Micro-CT and Micro-MRI scanners have seen significant advances in image resolution and imaging throughput. For pulmonary applications, however, the resolution and signal-to-noise ratio (SNR) obtained from thoracic images is frequently limited by respiratory motion-artefacts.

  • Due to variabilities in breathing pattern and breath segmentation, conventional gating is often insufficient to offer substantially improved image quality. This is particularly problematic in small animals due to their high respiratory rates.

  • Another important consideration is the time required to obtain a complete thoracic image data sets. Using conventional gating, only fractions of the breath may be used for image acquisition, resulting in limited throughput and possibly compromised stability of the subject over the course of the scan.

flexiVent Advantages

  • The flexiVent was originally designed to obtain the most accurate possible measurements of respiratory mechanics possible. Because respiratory mechanics highly depend on the experimental conditions under which they are measured, control and standardization of experimental conditions was a key requirement for the flexiVent.

  • The resulting control over parameters such as respiratory rate, tidal volume and positive end-expiratory pressure (PEEP), along with the ability to maintain a reproducible volume history, are directly beneficial to the imaging application.

structure & function

  • Another key advantage of the flexiVent lies in its capabilities of measuring respiratory mechanics with great accuracy and detail, allowing scientists to compare and correlate structural information obtained from lung images with lung function data obtained directly from the flexiVent.

  • The combination of standardized conditions, respiratory mechanics measurements and the flexiVent's freely programmable digital output ports, used to trigger your high-resolution scanner, provides an ideal environment for thoracic imaging.

Imaging templates

  • The flexiVent is a fully computer-controlled experimentation platform that is entirely initialized, calibrated and operated through the software. Central to the flexiVent software is the concept of experiment templates that encapsulate the entire system configuration.

  • For imaging applications, we provide readily usable default templates that pre-configure the ventilation settings, breath hold manoeuvres and digital output ports used for gating, as well as their respective timing. These templates can then easily be customized as you become more familiar with the flexiVent and its uses.

  • As a result, you can expect to obtain better thoracic images literally from the day you install your flexiVent system.

SkyScan 1076 Integration Package

  • The SkyScan 1076 is a high performance in-vivo micro-CT scanner for pre-clinical research. Using a 10 megapixel x-ray camera, it offers an excellent resolution with pixel sizes of 9, 18 and 35?m. Using a flexiVent to control image acquisition allows you to take full advantage of the SkyScan's outstanding resolution for your thoracic imaging applications.

  • To integrate the SkyScan 1076 with your flexiVent, we offer a turn-key package that includes a custom gating cable, specialized accessories for connecting the subject through the scanner's instrument channels, as well as all other necessary connectors, adapters and flexiVent software templates.

Other Micro-CT Imaging Scanners

  • The application specialists of our Customer Service department will always be happy to assist you with integrating the flexiVent with your particular scanner.

Imaging setup

  • Included below are in-vivo murine thoracic cross-section images that were obtained using a SkyScan 1076 Micro-CT scanner in conjunction with a flexiVent system.

  • The images shown below are cross-sectional images shown from equivalent positions in the same mouse, as determined by vertebral morphology.

  • Left and right images were obtained from unsynchronized imaging and synchronized breath-hold imaging using the flexiVent, respectively.

    • Note that the images obtained with the flexiVent were acquired at a higher lung volume.

    Sample Images

    Anterior Lung
    This image shows the unsynchronized (left) and synchronized (right) Micro-CT image of the Anterior lung.
    Central Lung
    This image shows the unsynchronized (left) and synchronized (right) Micro-CT image of the central lung.
    Lower Lung
    This image shows the unsynchronized (left) and synchronized (right) Micro-CT image of the lower lung.

Controlled Mechanical Ventilation

Using the flexiVent to mechanically ventilate the subject and provide a synchronized gating signal is superior to conventional respiratory gating in a number of ways:

Reproducible ventilation - Unlike spontaneous breathing, the ventilatory pattern prescribed by the flexiVent is entirely reproducible from one breath to the next.

Accurate gating - The flexiVent can issue trigger signals for the scanner with milli-second precision. In contrast, conventional gating is subject to detection inaccuracies.

End-inspiratory pause - The flexiVent's ventilator functionality allows end-inspiratory pauses of user-specified duration to ensure complete stability during each image acquisition cycle.

Positive end-expiratory pressure (PEEP) - The flexiVent's adjustable PEEP offers users the ability to obtain images at different levels of lung inflation.

Recruitment & breath-hold Manoeuvres

The flexiVent can briefly interrupt mechanical ventilation to execute manoeuvres during which a pre-defined volume or pressure waveform is applied to the airway opening. The following manoeuvres are useful for micro-CT imaging applications:

Recruitment Manoeuvres - Also referred to as sighs or deep inflations, these manoeuvres recruit closed airways and "reset" the volume history.

Breath-hold Manoeuvres - The ability to maintain the subject's lungs at user-defined volumes or pressures provides extended image acquisition windows for accelerated scan times and reproducible operating points.

Combined Manoeuvres - Concatenating a recruitment manoeuvre and a breath-hold permits imaging data to be obtained immediately after the volume history was standardized, providing for the very best possible image quality.

High-frequency oscillation - Small amplitude oscillation manoeuvres similar to high-frequency ventilation can be used to prolong pauses in ventilation and rapidly obtain large portions of a scan in a single manoeuvre.

Gating options

  • The system is equipped with up to four flexibly programmable gating signals that can be pulsed to allow multiple triggers during a single breath or manoeuvre.

  • Gating signals can be synchronized with any phase of mechanical ventilation, inspiration, expiration, end-inspiratory breath-hold or any of the above manoeuvres.

  • Additional flexibility in adapting the flexiVent to your imaging protocol is provided by the flexiVent's scripting feature.