Metavol
  • helps analyze PET-CT images and measure metabolic tumor volume (MTV), total lesion glycolysis (TLG), as well as SUVmax or SUVpeak.
  • is implemented with new algorithms making volume measurement process easy, quick, reproducible, and even fun.
  • is open-source software and can be used by everyone at no fee.
  • is an application tool running on Windows 7/8/10, but not on Mac or Linux (Sorry!).
  • has been successfully used by scientists and physicians (see scientific papers) since 2014.

The DICOM files of this case come from OsiriX website.
We are sorry but the files cannot be read directly by Metavol
because they are compressed with JPEG2000 encoding.

The latest version is released on Feb 24, 2015.


System requirement
Windows XP, Vista, 7, 8.x, 10 with .NET Framework 4.0 or later.
Sorry, Metavol currently does not work on Mac OS or Linux.
Metavol is light software and does not require a high-spec computer.

Metavol can be used at no fee.
The entire source code of Metavol is available at http://sourceforge.net/projects/metavol/.


FEATURES

Metavol can be used either as a simple PET-CT viewer or as an advanced PET-CT image analyzer.
  • As a simple viewer. You can use it as a basic and simple PET-CT viewer: transaxial, coronal, sagittal, and maximum intensity projection (MIP) views for PET, CT, and PET-CT fused images. Place a volume-of-interest (spherical, ellipsoidal, cuboid, or sylindrical) to measure SUVmax, SUVpeak, and SUVmean. MIP can be rotated. Panning, zooming, and paging are easy with simple mouse operations. All the functions you need for daily diagnosis of oncology FDG PET-CT are here.

  • As a tool for metabolic volume measurement. In order to reduce time and inter-operator variability, this application has 3 convenient functions.
    1. Automated mass detection first. In most conventional environments, you need to enclose the tumor first (using spherical or irregular volume of interest (VOI)), followed by the computer pick up volumes higher than a certain threshold. Creating VOI needs to be carefully done with long time and labor required. In Metavol, the computer first search the entire body PET images to mark up the mass higher than a certain threshold. Then, the operator is requested to determine whether each mass is tumor or non-tumor.
    2. Semi-automated liver VOI determination. According to PERCIST criteria (Wahl et al., J Nucl Med 2009), the tumor boundary on FDG PET-CT is recommended to be determined using the threshold derived from liver (mean + 3 SD, or 1.5 mean + 2 SD). By doing that, inter-study variability of SUV (or SUL) can be minimized. However, if the liver VOI is placed manually, this again causes inter-operator variability due to heterogeneity of liver uptake. In this context, we proposed a new semi-automated algorithm to consistently define the liver VOI. The details of the algorithm and the data about reliability are published in PLOS ONE and were presented at the Annual Meeting of Society of Nuclear Medicine 2014 in St. Louis, MO (Jun 7-11, 2014).
    3. Semi-automated separation between tumor and non-tumor. In many cases, the tumor exists close enough to non-tumor FDG uptake, which requires manual interaction to extract just the tumor. This is another cause of inter-operator variability of tumor volume measurement. This algorithm is proposed to try to conquer this issue. Although this does not work for all the cases, significant reduction of time and labor is expected in many cases. The details of the algorithm were presented at the Annual Meeting of Society of Nuclear Medicine 2014 in St. Louis, MO (Jun 7-11, 2014).



Why we started this project
    I, Kenji Hirata, have been working as a nuclear medicine physician in Japan. Since I started working in 2002, the de facto standard to quantify the intensity of FDG uptake in the tumor has been no doubt SUVmax due to its high inter-operator reproducibility and easy-to-implement feature. Recently, in clinical oncology, increasing lines of evidence have been accumulated to demonstrate the importance of metabolic tumor volume (MTV) for patient care such as treatment response evaluation and prognosis prediction. MTV is a total volume within a boundary determined with a particular threshold (e.g., SUV > 3, SUV > reference tissue, or SUV > 40% of SUVmax). Total lesion glycolysis (TLG) is a product of MTV and SUVmean within the boundary.
    However, in clinical settings, the use of MTV or TLG is quite limited. As far as I know, there are few institutes or hospitals that regularly measure these parameters and write them on diagnostic reports. I think there are at least two reasons: 1) measuring them requires time and labor of experts; 2) the measured parameters have variability between observers because of manual interaction.
    Therefore, I tried to conquer these limitations by developing a software tool that has new techniques. Fortunately, I have used the programming language C# for years. I got started with this project in May 2013. It took time, but it has been fun for me. I would be happy if the tool is used by many people, especially busy physicians, to extract 100% information from FDG PET-CT by measuring tumor volume without spending long time.



Known Problems
  1. DICOM related problems - We admit that this software has still a lot of problem regarding DICOM, although our current version has been tested using PET-CT images from several scanners of GE, Siemens, and Philips.
  2. Legal issue - This software tool has not been approved by any governments of any nations. If clinical diagnosis or treatment planing is done based on this software, that may cause some legal issues. You may ask what purpose to use this software for? For now, this can be used only for research, education, experiment, or demonstration purposes.

Future Perspective
    Possible functions the future version of this software will be
    • Texture analysis
    • Computer aided diagnosis (CAD)
    • Partial volume correction

    Question?
    Ask Kenji Hirata, MD, PhD (Currently, Hokkaido University, Sapporo, Japan; Previously, University of California, Los Angeles)
    Email to metavol.info@gmail.com