8 min readSurviving a Bottleneck – Insights into Managing Exponential Growth of Digitized Medical Images

Medical image data are becoming an increasingly important aspect for effective patient diagnosis.  There is an increasing trend of medical images being viewed and stored in digital format as opposed to the traditional film based images.  On one side, imaging modalities such as MRI, CT, X-Ray and Ultrasound are technologically evolving and providing enhanced images so that physicians can qualitatively analyze a patient’s problem, while on the other end, there is an increasing number is aging population in the United States (US) and Europe who demand better healthcare.  Imaging procedures at hospitals are increasing at an exponential rate.  For example, the number of CT procedures performed alone accounted for over 35 million in 1997 and doubled to 70 million procedures in 2007.  Frost & Sullivan predicts that the CT procedures will reach 100 million by 2013.  The advent of modern imaging technology and increasing patient inflow in hospitals has paved the way for digital image archiving. 

There are many advantages to digital image archiving.  Some of them include

Cost-Effective Storage: Certain government norms require that medical image data be stored and maintained for over 60 years.  Film based medical images are prone to decay if they are not maintained at optimal temperature conditions.  Moreover, the accumulation of film based images would require increase in inventory space for hospitals, thereby increasing its operational costs.  Not only is digital image archiving a cheaper alternative in the long run, as the cost per megabyte (MB) is continuing to decrease.  The retrieval of digital images is also much faster than having a hospital staff go through the image inventory where they are stored in the film format. 

Storage upgrade depending on demand: Many Medical Archive Solutions (MAS) providers such as IBM, HP, EMC, Sun Microsystems, etc are offering what is referred to as pay-as-you-grow package.  The MAS module can constantly be upgraded with additional image storage drives, where each storage module ranges in upper hundreds of terabyte (TB) space.  Whenever the hospital requires additional storage capacity, modules of memory can be added as per the requirement.  The cost of these high capacity storage modules are decreasing. 

Image Backup and multiple workstation access: The MAS providers also provide a backup server in case the main image archive server ceases to function.  In case of film based images, none of them can be reproduced in the event of a disaster.  Apart from the vitality of having a back-up server, other parameters such as image size and compression rate, image retrieval speed, internet bandwidth, type of connectivity for transmission, etc play a significant role in image archiving.  An image archive system also allows access to the same image from multiple work stations.  An MRI image for example, can be viewed by a radiologist, a primary care physician, and a lab administrator simultaneously.  As a result, a lot of time is minimized that would otherwise be prolonged when the image gets passed individually between each diagnostician.  In the United States for example, it takes an average of 10 weeks to get an appointment with a radiologist.  Patients therefore can avail quicker results while the hospital also accelerates is productivity. 

As simple as the image archiving solution seems, the reality of implementing an archiving solution is burdened with challenges and complications.  Some of the challenges include: 

Interoperability issues between hardware and software: PACS (Picture Archives and Communication Systems) solution – that manages the storage, archiving and retrieval process of medical images – are developed as “silo” solutions and caters to only one institution.  Some PACS vendors provide solutions for individual departments in hospitals.  When a new PACS module is adopted by a hospital – depending on its complexity and customization – There are many complications encountered with its interoperability, especially when a new image modality is purchased.  PACS versatility is also affected when the archived images have to be shared between multiple hospitals.

Image Modality Average Exam Size (MB)
CR/DR 38
Ultrasound 20
Echo 350
CT 35
MRI 23
Angiogram 225
Interventional Radiology 22
Nuclear Medicine 2
Fluoroscopy 20

Table 1.1:  Digitized image file size from various modalities.Source: Frost & Sullivan

Image Retrieval Concerns: Medical image quality continues to increase thereby increasing the image size.  The size of a medical image averages 38 MB (megabyte) for digital radiography, 20 MB for fluoroscopy, 225 MB for angiography and as high as 350 MB for Echo.  Table 1.1 depicts the average file size generated by various imaging modalities and Chart 1.1 depicts the file-size storage in terms of percentage.  Digital pathology (DP) is an emerging trend in the digitized image archive sector.  DP images have high resolution and each image size can vary from 0.5 GB to 2 GB.  A 100 bedded hospital performs 40,000 to 45,000 radiological examinations each year, which amounts 2GB of storage space a day, or up to 1 terabytes (TB) a year.

With an ever increasing aged population and image diagnostic procedures increasing at a average of 10 per cent a year, there will be an exponential increase in digitized image volumes.  The accumulation of images makes it harder and slower to retrieve them.  In the case of complex cardiology examination, the image size can exceed 2 gigabytes (GB).

Chart 1.1:  File-size storage expressed as percentage. Source: Frost & Sullivan.

There is no simple solution to the variation in image retrieval time.  It depends upon many factors such as image size, transmission speed supported by the network cable, internet bandwidth, and compression rate of the image.  Therefore, the image retrieval can vary between a few seconds to more than 15 minutes.  In most hospitals, there are also concerns for the amount of storage space allocation for radiology and cardiology purposes.  Another important factor is that the image needs to be matched with its respected patient data.  There are cases where the image the patient data gets mismatched as they are stored as separate entities.  A mismatched data and image can prompt wrong treatment to the patient.  The image and patient data are mutually coexistent and no useful information can be derived if either one of them is lost.   Although vendors providing PACS software perform multiple tests to avoid the patient data and image mismatch, concerns over this issue exists nonetheless.

DICOM non-compatibility:
DICOM (Digital Imaging and Communication in Medicine) standards are not compatible with all types of images.  The pace at which modern imaging modality evolve is faster compared to the DICOM upgrades.  Therefore, there are other service oriented approaches to better accommodate images without DICOM compatibility.  This service oriented approach also supports more than one tier of image viewing.  Although DICOM is not the best choice for all images, the service oriented approach to store and retrieve certain images are not governed by any specialized standards such as DICOM.  The lack of standards for service oriented approach poses interoperability concerns between information technology (IT) enabled ancillary systems in hospitals. 

Hospital budget constraints and user acceptability: Although employing an MAS can be cost-effective for hospitals in the long run, they can be very expensive during the initial phase of installation.  Most hospitals are budget constrained and a decision to install an MAS module in itself will take a long time.  An MAS is most effective when the hospitals also have an EPR (electronic patient record) installed, which allows for exchange of patient information between multiple hospitals.  So hospitals have budget concerns while installing a MAS because they would also have to invest in an EPR for effective productivity.  Finally, the user-acceptability to installing MAS module depends entirely on the user friendliness of the PACS module.  The more complicated the PACS user-interface, less likely are the hospital staff are towards upgrading their IT facility. 

Hospitals and private diagnostic centres can consider the following recommendations to ensure effective management of high growth digitized images:

Choose an appropriate Vendor: Vendors for both PACS (McKesson, Siemens, Philips Medical, GE Healthcare, AGFA) and medical archives solution (IBM, HP, EMC) are plenty.  Although the principle logic behind digitized image archiving may remain the same, each vendor will have their own style of execution and post-installation services.  Hospitals should consider proposals from at least 3 vendors before a new archiving solution is installed.  They must ensure that the proposal from vendors not only include upgrade costs for hardware and software (depending upon the hospital productivity), but also accounts training costs for a specified period of time.  Sometimes, hidden costs for extension of training and service response for non-working hours are not included in the proposal.  The consulting period – that usually lasts between 2 to 3 months – where the vendor would interact with the hospital staff before the archiving solution is installed will also vary.  Most importantly, hospitals must ensure that the proposal also includes a disaster recovery process that does not limit productivity.  Hospitals need to draw a line between how advanced of an archiving technology they need and what imaging equipment they currently have or plan to buy.  An archiving solution is available at multiple technology levels, depending whether or not a hospital has already installed ancillary systems such as EMR (Electronic Medical Record), HIS (Hospital Information System), RIS (Radiology Information Systems), etc.  Hospitals must prioritize storage upgrade features and ensure that the vendor consistently meets the evolving standards.  A vendor offering multiple plans for long term post-installation service and upgrades is a worthy proposition for hospitals. 

Standardize a compression ratio for different images and ensure its backup: An original image is compressed at a 2:1 ratio and it is still considered to be a lossless image.  In addition to having one backed-up image, hospitals may also choose to have multiple image replications at ratio of 20:1, 50:1 and so on for high resolution images so that general physicians can retrieve these images faster.  All vendors give hospitals the flexibility to choose any compression ratio for additional image replication.  Therefore, hospital staff – radiologists and image modality operations specialist – need to decide the level of compression they want from the image generated by the modality.  For example, depending on the radiological examination at hand, if a radiologist can infer the same amount of information from 4:1 and 2:1 compression image, then for the same procedure, they might as well employ the 4:1 compression and save storage space for hospitals.  However, procedures such as a mammography are strictly regulated, especially in Europe where compression is not allowed.  Hospitals must strategically work with vendors during the consultation phase to streamline and standardize various compression ratios for all diagnostic procedures.

It is imperative that every hospital store one original copy of the digitized image and another replicated image as back-up.  Medical archives solution vendors recommend that ideally two back-up copies of the original image be stored.  Digitized medical images have to be stored for longer periods for two reasons.  First, a hospital needs to retain images for legal purposes and the duration time for retaining these images vary according to the government regulations in each country.  Second, some diagnostic procedures (such as detection of cancer) are repeated for a particular patient in order to track the physiological changes over time.  No medical archives solution technology is 100 per cent fail proof.  Therefore, it is essential that hospitals replicate at least one back-up copy of the original image. 

Ensure images from all departments are centrally archived, under a common module: Radiological diagnostic procedures used to dominate the overall imaging procedures performed in a hospital.  However, within the last three to five years, cardiology imaging procedures have gained an equal importance due to an increasing number of heart examinations conducted at hospitals.  Due to the enormous image volumes generated by these departments, they have had a tendency to store these images in their own individual storage modules.  The management of individual storage units has posed problems when old image data need to be migrated to upgraded storage modules.  Since high storage capacity drives are available as single modules, archives solution vendors have started to convince the radiology and cardiology departments that it is practical and more efficient to store images generated from both departments on a common storage unit.  Other departments such as neurology and digital pathology are also finding potentials from digitized imaged.  Therefore, scaling up and managing all archived images from a central location would ensure un-interrupted productivity for the hospitals in the long run. 

Partner with vendors for enhancing collaboration among clinicians at remote sites: The image archives solution is a centralized network where all the images and patient data are capable of being accessed from remote sites. As patients come to hospitals to undergo diagnosis, the concerned physician may not necessarily be available at the hospital premises. The archive solution providers, apart from providing a robust solution that helps to retrieve data faster, also allow for easy accessibility to images by the clinician from the remote site. This concept becomes even more important when more than one clinician is involved from a remote location for screening medical images. The number of clinicians who access the centrally archived images from remote sites will continue to increase because the increase in the number of diagnostic procedures has surpassed the availability of clinicians to address the same.  Hospitals can therefore help vendors in such a scenario.  Apart from ensuring productivity, hospitals may also be able to avail part-time workers at different locations and help speed up patient appointment times. 

Conclusion
It is clear that medical archive solution is here to stay and it will be subjected to continuous upgrades in the years to come.  Not only does it improve the operational efficiency of the hospital, but it is also a cheaper alternative in the long run as opposed to images stored in films.  Although challenges associated with MAS interoperability, image retrieval, hospital budgets and DICOM non-compatibility exist at this point, the MAS technology will slowly evolve by addressing all these challenges.  A successful image archives solution will depending upon effective collaboration between four major players, namely, the PACS vendors, the MAS providers, hospitals, and imaging modality manufacturers.  Managing enormous volumes of digitized images is definitely a bottleneck, but it is definitely addressable, provided the hospitals and diagnostic centres really understand its complexity and collaborate to improve productivity.

Healthcare IT

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