Background

To date, in most echocardiography laboratories, acquisition and archiving of diagnostic echocardiographic images is performed analog technology (recording on videotape). This technology, in use in the past 30 years, has advantages and drawbacks. Among the advantages are the low operative and archiving costs, and ease of use. Disadvantages are represented by an immediate loss of quality of archived images when compared to originals acquired by the ultrasound equipment, the progressive loss in time of videotaped image quality, the long time required to retrieve archived images, the difficulty to compare side by side studies obtained at different times with an ensuing negative impact on the diagnostic accuracy of the echo lab. Finally, the impossibility to manage fully digitally - in both administrative and scientific settings - the echo lab. Based on these considerations, the transformation of the echo lab from analog to digital technology has been advocated by many. Digital technology would obviate all problems related to the use of analog technology (1). But, in most echo labs, digital (online) technology is applied only to echo reporting, and usually only in text mode. However, the (technically simple) strategy of digitalizing only the echo report does not take into account that imaging and not reporting is central to the echocardiographic examination. Further, the echo examination – in that it is not only tomographic but also (mainly) dynamic – may be adequately reproduced only by archived dynamic image sequences. The main functions of the digital echocardiographic laboratory (DEL) may be summarized as:

  1. Digital aquisition, archiving and retrieval of still images and image sequences.
  2. Production and archiving of the echo report.
  3. Diagnostic, scientific, educational, and administrative digital management of the echo lab (random access to images; image reproduction without loss of original quality; simplified side by side comparison of online and archived images; remote retrieval of studies)
  4. The possibility to effectively introduce quality control in the echo laboratory.

The drawbacks related to the introduction of digital technology in the echo lab may be summarized as follows:

  1. High (or very high) initial costs, as related to the relatively low budget of an echo lab when compared to other imaging techniques (angiography, radionuclides, computed tomography). The minimum initial cost required to start digitalizing echo images with a single echocardiographic machine is approximately $25.000 for commercially avaliable equipments.
  2. Proprietary hardware and software, from different vendors, and thus difficult to interface.
  3. A highly "technicalized" environment, when compared to the analog echo lab.

And it is because of these drawbacks that the analog to digital transformation of the echo lab - though advocated by many - has been completed only in a very limited number of echo labs around the world.



Aims

The present project has the aim to realize the trasformation from analog to digital technology of the echo lab through the creation of a hardware / software system that stems from the joint efforts of a software engineer and a cardiologist echocardiographer. The original software program will be supported by an "off-the-shelf" hardware architecture. The software system will be dedicated to digital acquisition, and ensuing manipulation, reporting and archiving of images produced by any ultrasound machine equipped by a s-VHS video output. The integrated software/hardware system will address and solve each of the above mentioned problems related to digital echocardiography, so to offer a practical soution characterized by:

  1. Minimal initial costs
  2. Complete compatibility
  3. Simplicity of use


Project

The main characteristics of the project – given the phylosophy underlying the project - will be the possibility to provide the end user a complete system at a very low cost, accessible by a single professional:

  1. low cost of required hardware components (because not limited to the medical hardware environment)
  2. elimination of initial elevated project costs secondary minimized "engineering: costs (a single software engineer and a single cardiologist)

The system will be based on the utilization of a PC with a Windows 2000ä operating system. After the initial software engineering phase and its integration with a multimedia PC equipped with a digital analog (s-VHS) to digital acquisition board and a CD writer, the system will be tested in a Level III echocardiography laboratory, to optimize echocardiographic image acquisition, archival, retrieval and reporting protocols. Specifically, different acquired image compression algorythms will be analyzed, as related to the clinical quality of the images and the storage space utilized on the CD-Rs. The system provides long-term echo study archiving on non rewritable CDs, to preserve original image information (foreseeing probable legal implications of long-term clinical image information storage). A fundametal characteristic of the project is the acquisition of the echo study images through the s-VHS video output of the ultrasound equipment, thus providing total compatibility with any commercially available (and older) ultrasound machine, independent from any proprietary storage system provided with the machine. It is important to note that recent clinical studies have evidenced that the resolution provided by the s-VHS video signal is, in the diagnostic setting, sufficient (2, 3). Another advantage of the project is the creation, and thus online availability, of libraries of file names (for both acquired still frames and loops) and of standardized diagnostic comments and conclusions for echo reporting, following published recommendations of the American Society of Echocardiography and the Italian Society of Cardiovascular Echography (4). The different phases of the project are the following:

  1. Determination of the required hardware components necessary for the integration with the software of the project. A) Determination of the hardware necessary to digitalize in real time echocardiographic moving images, with the best cost/performance ratio, taking into account compatibility with the Windows 2000ä operating system. B) Determination of the most appropriate storage media, given the large quantity of data generated by digital acquisition of moving images.
  2. Construction of the software necessary to manage digital acquisition, archiving, and reporting of the echocardiographic examination, with a simple to use user interface. Initially, the software will function as a "stand-alone" system (not connected to the hospital network).
  3. Study of the best (optimal) compression ratio obtainable online during image digitalizzation, so to increase the image quality / storage volume ratio.
  4. Extension of digital technology to the entire echo lab, connecting the single hardware/software systems to the local net, thus providing the hospital network with the possibility to retrieve single studies through eventually a CD-R jukebox.


Published: August 1999