Computer-aided simple triage (CAST) are computerized methods or systems that assist physicians in initial interpretation and classification of medical images. CAST is a sub-class of
computer-aided diagnosis (CAD). CAST
software systems perform a fully automatic initial
triage (classification) of diagnostic
medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
studies. CAST is primarily intended for
emergency diagnostic imaging, where a prompt
diagnosis of critical, life-threatening condition is required.
Overview
Computer-aided simple triage (CAST) is a combination of
computer-aided diagnosis (CAD) and
simple triage and rapid treatment
Simple triage and rapid treatment (START) is a triage method used by first responders to quickly classify victims during a mass casualty incident (MCI) based on the severity of their injury. The method was developed in 1983 by the staff members of ...
(START).
CAST performs a fully automatic initial interpretation of a study – a "wet read". Studies are automatically classified into some meaningful categories, e.g. positive/negative, critical/minor/normal, difficult/simple/non-diagnostic, etc.
CAST is primarily intended for
emergency diagnostic imaging. Unlike traditional CAD, mainly used to detect malignant lesions, CAST deals with acute, life-threatening conditions, when a prompt diagnosis is time
critical. While the primary goal of the traditional
CAD
Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve co ...
is improving the diagnostic accuracy of a human reader, the CAST addresses two other problems:
* Low availability of image interpreters – no reader immediately available to read an urgent study – off hours, rural places, under-staffing
* Reading sequence prioritization – given a large number of studies to read, establish the optimal reading sequence, e.g. urgent cases first; or, given several available readers, distribute the workload in the optimal way, e.g. simple cases to trainees, difficult to experts.
Use case scenario
As with the traditional CAD, CAST does not substitute the physician. It only alerts about the possibility of acute, critical condition, or suggests that the study is free of severe disease. In both cases, the diagnosis should be verified by a trained physician.
The clinical benefit is achieved:
* for positive cases – by bringing expert's attention to critical cases faster than it would happen without CAST
* for negative cases – by letting less experienced staff be the first to deal with simple negative cases, thus releasing pressure from less available experts.
Traditional CAD system usually plays the role of a "second reader" and is used ''after or during'' the interpretation
performed by physician. CAST, on the other hand, analyzes the study ''before'' the physician, in a background, fully automatic mode. By the time physician comes to read the study, the initial triage or "wet read" prepared by CAST is already available. CAST system can send a message to a physician to report an urgent case requiring immediate attention.
Sensitivity and specificity
Like any CAD system, CAST, in general, cannot guarantee 100% diagnostic accuracy.
Since CAST operates in a fully automated mode, the system is expected to exhibit very high
sensitivity – usually above 90%. Moreover, the need to provide a diagnosis at "per study" level dictates stringent requirements for CAST
specificity as well. The average of one or more
false alarms
A false alarm, also called a nuisance alarm, is the deceptive or erroneous report of an emergency, causing unnecessary panic and/or bringing resources (such as emergency services) to a place where they are not needed. False alarms may occur with ...
per study, tolerable for a traditional CAD, is not acceptable for CAST, as almost every study would be reported as positive. Therefore, for most clinical applications, CAST specificity should be higher than 60-70% to make it useful.
Reliability and quality control
Since CAST operates in a fully automatic mode, it should be able to deal with any study, regardless of image quality, patient anatomy, etc. Therefore, CAST systems should implement a quality control mechanism to ensure the high confidence level of the diagnosis. If the system decides (based on the evaluated image quality, detected
artifacts, anatomical anomalies, etc.) that no reliable diagnosis can be automatically achieved, it reports a failure.
Clinical applications
CAST approach is applicable for the automatic detection of acute, life-threatening conditions from diagnostic medical images, such as:
*
Pulmonary embolism (PE)
*
Aortic dissection
*
Coronary artery disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...
*
Stroke
A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...
*
Bone fractures
*
Internal bleeding
*
Pneumoperitoneum
*
Idiopathic intracranial hypertension
CAST system can analyze images acquired with various modalities, including
x-ray,
CT,
MRI,
ultrasound and others.
Examples
CAST for coronary artery disease
CAST system is available for the detection of significant (>50%)
coronary stenosis
A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture).
''Stricture'' ...
in coronary
CT angiography (cCTA) studies. The system exhibits "per study"
specificity of 60–70%, while keeping the
sensitivity above 90%.
It can be used for chest pain patient triage in emergency room.
CAST for Intracranial Hemorrhages
A deep learning system is available for automatic detection of
Intracranial Hemorrhages
Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds (intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural bleeds. Mor ...
in acute care settings.
[Zebra Medical Vision Announces CE Approval of Its Newest AI Imaging Algorithm - Automatic Identification of Brain Bleed]
/ref>
See also
*Aidoc
Aidoc Medical is an Israeli technology company that develops computer-aided simple triage and notification systems. Aidoc has obtained FDA and CE mark approval for its stroke, pulmonary embolism, cervical fracture, intracranial hemorrhage, Pneumo ...
References
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