Types of Imaging Workflows

POCUS Workflow: Simplified Explanation

The goal of any imaging workflow is to have images with an associated report visible in the patient's chart. In order to do this, three things need to occur:

1. Link the imaging exam to the correct patient 

2. Link the imaging exam to the correct patient encounter

3. Link the exam images to a finalized imaging report

In order to make all of this happen, we need two different systems: the electronic health record (EHR) and a DICOM imaging management system (e.g., PACS).

To accomplish these requirements, we can use two different workflows. One that requires an order to occur BEFORE the images are obtained (Order-based workflow) and one that does not (Encounter-based workflow). 

The two figures below are simplified versions of the two types of workflow used for POCUS. They focus on the steps that a user needs to complete in order for the POCUS exam to be saved and visible in the patient's chart.

In both workflows, the patient must first be registered within the electronic health record (EHR) in order to link the ultrasound exam to the correct patient. In an order-based imaging workflow, an order must first be placed in the EHR. The order specifies which ultrasound exam (e.g., Lung POCUS exam) is to be completed for which specific patient (e.g., Rob Ferre) for which specific encounter (e.g., Emergency Department visit on January 1st). After receiving the order, the EHR sends a message to the pictures archiving and communication system (PACS) that an ultrasound exam needs to be completed on the specified patient in the specific location where the patient is registered. After receiving the order, the PACS system populates those details within the DICOM Modality Worklist (MWL). After turning on the ultrasound machine, the clinician (or technician) performing the ultrasound exam queries the MWL through the patient information screen before beginning the exam. Once the patient's information is pulled from the MWL, the ultrasound exam can begin. Once images are acquired and the exam is ended, the PACS system recieves those images and reports back to the EHR that the order has been fulfilled. The PACS system then removes the patient from the MWL. This keeps the system orderly and allows those tasked with completing the order (e.g., an ultrasond tech in radiology) to ensure that they are completing all of the exams they have been asked to perform. 

In contrast, in an encounter-based imaging workflow, an order does not need to be placed before an ultrasound exam can begin. This is because a much different MWL is used for this type of workflow. The reason the workflow is called "encounter-based" is because the worklist is created, not based on an order, but simply based on a patient being registered for an encounter. As a result, this MWL is much larger and lacks information about the ultrasound exam that needs to be completed. This MWL needs a very different PACS system, one that is specific to POCUS. We call this POCUS PACS system a POCUS Workflow Manager. It uses an Admission, Discharge and Transfer feed from the EHR to populate its own worklist; one that is separate and distinct from the MWL created by the radiology PACS. 

Correct Patient Verification Process:

When a patient arrives for an encounter with the healthcare system, they must be registered in the EMR. This ensures that the patient presenting for a visit, is indeed the same one that is registered in the EMR. Once this is done, other software systems (like the PACS system that uses a different computer language) gain access to the patient demographic information via an Admission, Discharge, Transfer (ADT) HL7 message (remember HL7 is the language of the EMR). In an order based workflow, when an order is placed, the EMR sends an HL7 Order Message (ORM) to the PACS system. The PACS system takes the order (e.g. order for a comprehensive thyroid ultrasond) and the ADT data from the HL7 message and converts it into DICOM language. The PACS system then sends a notification to a modality worklist (MWL). This MWL can be queried on the ultrasound machine and lets the ultrasound technician know that "patient x" needs a thyroid ultrasond. When the ultrasound technician finds the patient, the technician verifies that the patient in front of them is the same patient displayed on the ultrasound machine by verifying that the MRN, patient name and date of birth are correct. The ultrasound exam is then performed. 

In an encounter-based workflow, there are several different places where the ultrasound exam can be linked with the ADT data, however, it needs to occur at some point before it can be sent to the PACS or the EMR. The earlier this can be done in the process, ensures errors are not made. Within the Emergency Department (ED), one way this can be done is to have a dedicated MWL just for POCUS exams. This MWL is populated, not by an HL7 ORM (as in the order-based workflow), but occurs for all patients once registered in the ED. Most ultrasound machines can perform an autoquery of the MWL when the medical record number (MRN) is scanned. This then populates all of the patient demographic information to be displayed on the patient information screen. This is verified by the the physician an the ultrasound exam begins.