Overcoming bandwidth limitations with DICOM compression


Overcoming bandwidth limitations with DICOM compression

A problem faced by all radiology and teleradiology operations is coping with the ever-increasing volume of imaging data being produced by an imaging department. With the development of new imaging techniques and technologies, we are seeing ever-increasing image sizes and volumes that are putting our networks and infrastructure to the test. With studies being anywhere from a few megabytes for a simple x-ray, to multiple gigabytes for breast tomosynthesis, congestion on our local and wide area networks can quickly become a problem. 

In a teleradiology operation, the time it takes for a study to transmit can be critical in cases such as trauma where an immediate decision needs to be made about a patient. These studies also tend to be on the complex end of the spectrum, usually CT and depending on the trauma can cover a large area of the body. Ultimately this results in a large dataset to transmit to a remote Radiologist. Compression can greatly speed up the transmission time of a study leading to that study being available to a radiologist in a markedly reduced timeframe. These same benefits can also be enjoyed when cases are routine. In receiving the imaging faster, you have the flexibility to pull as many prior studies as your Radiologists require, without delaying your turn around times.

For radiology, compression is a crucial tool for ensuring you can store your imaging data on your PACS system for the legally required duration while remaining cost-effective. In a busy imaging department, compression can reduce the load on the overall network and allow a Radiologist to enjoy faster viewing of images when retrieving them to their diagnostic workstation.

What is DICOM compression?

DICOM compression is the process of taking, raw, uncompressed DICOM image data and compressing it using an algorithm in order to reduce the size of the file. The DICOM standard defines a number of compression formats, such as JPEG, JPEG-LS and JPEG 2000, ensuring that devices can exchange and display compressed data reliably.

DICOM compression can be separated into two basic types, lossy and lossless. Lossy compression causes irreversible loss of imaging data, meaning that it can not later be uncompressed back into its original pre-compression state. Because of its aggressiveness, it can achieve very high compression ratios. Lossless compression is compression that maintains the original level of detail of the image and can also be reversed at a later date. Because of this, lossless compression results in lower compression ratios, however, the compression can still be significant and can reduce a file by 2 to 10 times in size.

Which DICOM compression should I choose?

The decision on what DICOM compression to use is going to differ in each situation. It is a balance between the clinical needs of the Radiologist, legal requirements in the regulatory environment you operate within and other constraints such as bandwidth and storage limitations that will dictate your options.

Ultimately there is no one solution applicable across all modalities, and clinical settings and consultation with all affected parties should be undertaken to decide on a compression strategy and implementation that achieves the requirements given the constraints.

Generally, lossless compression and its associated transfer syntaxes, such as JPEG-LS or JPEG2000 are safe choices. However in certain situations, lossy compression can be appropriate, but care should be taken. One application of lossy compression is as part of image lifecycle management. Many PACS systems support image lifecycle management in that they can progressively compress an image with reducing quality as it ages and then possibly delete the image at the end of its legally or otherwise required retention period.

How AdvaGateway can help

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AdvaGateway is a high-performance DICOM router providing a number of other features to enable an imaging enterprise to enhance their imaging workflows.

AdvaGateway supports the creation of flexible compression rules to cater to any compression requirement you may have.

An example scenario would be an imaging department in which after-hours studies are reported by an off-site radiologist or a teleradiology company. Generally, only acute cases such as trauma are reported in such circumstances. In this case, it is critical to get the images to the Radiologist as fast as possible. To ensure the Radiologist receives the imaging as fast as possible the AdvaGateway could be configured with the following rules;

Compression Rule: upon receiving an instance matching the following DICOM tags:

  • Department: ED
  • Modality: CT

and “Time of day: after 6pm”, compress to JPEG 2000 lossless, then route to the required destination.

Additionally, AdvaGateway could be configured to send thin slices on a lower priority queue, ensuring the Radiologist is able to receive the thick slices as soon as possible.

If you would be interested in learning more about how AdvaGateway could solve your problem, please contact us.