Managing Dynamic Images in the Echo Lab
There is one thing to keep in mind when digitizing an echocardiography lab - there is no one way to go about it. Managing dynamic images such as digital echocardiograms is a complex task, coupled with multiple questions. Will we still produce videotapes? Will every echo exam be digital? Will other departments have access to our image repository? Aside from learning how other hospitals have done it, the answers boil down to finances, personal preference and the image and information management system itself.
A GROWING TREND
Digitizing echo labs is on the rise - and it has a long way to go as only 10 percent of U.S. labs are currently digital, so says the American Society of Echocardiography. ASE surveyed to find out how echocardiography programs utilize digital information management techniques to supply cardiologists with digitized loops of echo images for review on a computer monitor, as opposed to the conventional approach of reviewing videotaped images on a VCR/TV monitor system.
| Peace of Mind: There is plenty to keep in mind when digitizing an echo lab |
| Do an on-site visit See it before you buy it, recommends Geoffrey Rose, MD, director of the cardiac ultrasound laboratory at the Sanger Clinic, part of the Carolinas Heart Institute at the Carolinas Medical Center, N.C. "First thing you do is go to a place that has already done it. It's a small world and people will tell you what worked for them and what didn't." How to acquire the image "One has to make a decision on how to acquire the digital images," says Alan Katz, MD, director of medical information technology at St. Francis Hospital. "We believe there is an advantage to gating the imaging - to acquire it by two second intervals or even better, by gating it to the EKG, so you see one or two cardiac cycles over and over again." Read digitally Physicians must be comfortable reading images in digital loops as opposed to videotapes. "This is related to the criticism generated in the field that digital echocardiography is so sonographer dependent," poses Katz. "I maintain that the study is extremely sonographer-dependent from the beginning." IT Support "You need a reliable IT resource to help you with networking because there will be glitches such as ports that close and IT conflicts," explains Katz. "It is not reasonable to assume that everything will work 100 percent." Take your time "You have to be careful and not set the bar too high," relays Rose. "When somebody is still reading echo off a videotape on a television and dictating it into a telephone, don't start talking about comprehensive reading stations that allow you to read nuclear images simultaneously." |
"Videotape is not a medium that is designed forever and ever," says Geoffrey Rose, MD, director of the cardiac ultrasound laboratory at the Sanger Clinic, part of the Carolinas Heart Institute at the Carolinas Medical Center, N.C. "It's true they will last several years and that's the general standard that people will hold on to data. But they are bulky and expensive to store. And again, when you want to look at an old study, it's probably not accessible to you because it is in remote storage somewhere. When you have things digitally stored, they are potentially more retrievable."
The advantages of going digital in echo outweigh conventional methods: digital echos have greater image quality; allow clinicians simultaneous access to the same study; facilitate easy comparison with prior studies; and allow non-linear study review and post-acquisition image processing.
So with a healthy list of advantages, why have so few echocardiography laboratories taken on this endeavor? "In radiology you can make a financial case from day one: if you go digital, you don't have to develop film," says Alan Katz, MD, director of medical information technology at St. Francis Hospital, a 431-bed heart center in Roslyn, N.Y. "In echocardiography, we are competing with videotapes, which are as cheap as can be at this point. So the financial argument is not easily made. As media has gotten less expensive - CDs, DVDs, RAID drives - the financial case has become much more clear," explains Katz.
Katz knows first hand about the financial benefits of a digital echo program. St. Francis Hospital recently installed an Encompass cardiology image and information management system from Heartlab Cardiac Solutions of Westerly, R.I.
"There are a couple of reasons why we have saved money," suggests Katz. "We are a very busy heart center, our transcription costs have reduced dramatically and we have saved by eliminating repeat studies. The biggest gain, although hard to quantify, is in the efficiency of the echocardiographers."
EFFICIENCY IN NUMBERS
Physicians at St. Francis now read 15 percent more echo exams in a digital environment as compared with an analog environment, Katz says, mainly because they have immediate access to the echo studies. In addition to faster retrieval and report turn-around, Heartlab's Encompass utilizes a DVD jukebox archive so that St. Francis can create an image repository for the echocardiography lab and the cardiac catheterization lab. In addition, St. Francis shares the echo lab's image repository with an affiliated remote outpatient clinic.
"What initially was put in was the ability to capture digitally from all the existing cardiac cath labs and store images on a server with a deep archive for near-line [storage] capability using a DVD jukebox," says Katz. "Following that, we brought in a separate server with a separate DVD jukebox [for echocardiography], which we currently have today. Eventually, we will migrate to a single server. We also installed an additional Web server that allows us to view images offsite over a secure Internet connection."
DVD has been adopted in cardiac imaging as the standard for long-term image archiving since it provides reliable, secure data storage with a shelf life of more than 100 years. One DVD can store approximately 130 DICOM standard echocardiograms and each Encompass DVD jukebox manages several hundred DVDs.
Echo review stations that run Encompass are distributed throughout the hospital. "There is another thin client that we can run on any other computer that is hooked up to the network which has a little bit less functionality than the workstations," says Katz. Since the radiology department uses Fujifilm Medical Systems' Synapse PACS, physicians at the echo review stations also can open up a separate window to examine radiology exams.
"Eventually Synapse will be available through Heartlab's Encompass, moving toward a single program for images from both radiology and cardiology," says Katz. Heartlab partners with a number of PACS companies, including Fujifilm and Agfa Healthcare, so that the companies can provide facilities with the tools they need to view and share radiology and cardiology data, from multiple modalities, with centralized storage and hardware.
DIGITAL LOOPS
The digital loops are JPEG compressed on the ultrasound systems at St. Francis, making them smaller files. "We are dealing with cine images which are fairly large images," says Katz. "There have been a number of studies done that show compressing echocardiograms at least 10:1 loses no clinical information. With compression, an average echocardiogram is 50 Mb now. Compression can be set to none, minimal, moderate or large. We currently use moderate compression, which translates to about 10:1 depending on the image type."
The echo lab at Sanger Clinic deals with this issue differently. "If you capture the raw digital signal and store it for processing, you will have more capability to manipulate that data down the road - but that comes at the expense of a larger file," says Rose.
In early stages of a soft-copy transition, sonographers produce digitized loops of echo images and concurrently store the exam in its entirety on videotape. For one reason, says Rose, videotape is a safety net. "I think people still do videotape to some extent because that is how the study has been done since echocardiography has been around," contends Rose. "But there is also the practical issue. If you are in a patient's room doing a study and someone kicks the plug out of your machine, your study is lost but what you did on videotape is still there."
Physicians do adjust quickly to reading on monitors - waning their dependency on videotapes - as they realize their time spent reading exams is significantly reduced. Each digital loop is 2 to 3 seconds long so that it captures one or two complete heartbeats. Exceptions include pediatric cases or adults who have an abnormal heartbeat, in which case the sonographer has to produce longer loops. While the amount of loops required for each exam depends on the experience level and confidence of the sonographer, the average is between 40 and 50 loops per exam. Different imaging protocols do exist for transthoracic, stress and transesophageal (TEE) exams.
CUTTING TO THE DIGITAL CHASE
Digitizing an echocardiography lab is a subjective undertaking; what works for some may not work for others. While Cedars-Sinai Medical Center in Los Angeles, Calif., decided to install Camtronics Medical Systems' Vericis to ensure that every echo exam was obtained and stored digitally, Johns Hopkins Medical Center uses Philips Medical Systems' Enconcert echocardiography information management system for transthoracic and stress exams.
"Transesophageal studies still use videotape and they are not digital," says Lili Barouch, MD, assistant professor of medicine, division of cardiology at Johns Hopkins. "The way the study is performed makes it more difficult to capture that efficiently on a digital system. We often look for details that cannot be captured in one or two beats. The feeling is that we would be losing a lot more information putting that on a digital study rather than a transthoracic echo where the views are more standardized."
On the other hand, every echo exam the physicians read at Cedars-Sinai is in a digital format, even three-dimensional images. "It took one day to convert tapes to digital reading and everybody loves it," says Robert Siegel, MD, director of the cardiac non-invasive lab at the facility and professor of medicine at UCLA School of Medicine. "There was essentially no transition time. Everything is digital, from the operating room, inpatient, outpatient, TEE. Otherwise, you would not have access to all the echo studies. The beauty of the system is that you can compare studies side by side."
Camtronics' Vericis is compatible with echo systems from every major manufacturer since studies can be acquired using the company's cardiac acquisition (CA-E) unit or through the machine's DICOM output. The CA-E technology allows the sonographer to acquire complete studies and is not limited to clips or a set number of heartbeats or seconds.
Enterprise access to information and images is one of the benefits echocardiography labs will experience, as long as each modality can integrate with the information system. Under the sponsorship of the American College of Cardiology, a cardiology initiative has begun for an IHE (Integrating the Healthcare Enterprise) Cardiology Committee. This will ensure that standards exist to improve the way computer systems in cardiology share information.