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:
The drawbacks related to the introduction of digital technology in the echo lab may be summarized as follows:
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.
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:
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:
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:
Published: August 1999