Lesion Detection on Diffusion Weighted Imaging


Early detection of DWI restricted lesions and notification





Define-AI ID



John Tsiouris
Lead John Tsiouris

Panel Chair

Alex Norbash

Panel Reviewers

Neuroradiology Panel


Creative Commons 4.0 
Status Public Commenting
RadElement Set RDES95 

Clinical Implementation

Value Proposition

Diffusion weighted imaging is a quick, routine, standard of care MR sequence performed on almost all brain MRI scans in clinical practice, which has immense clinical utility. It detects acute infarctions with 95-99% accuracy. It is also extremely valuable for identifying and diagnosing intracranial abscesses, hypercellular tumors, subacute hemorrhages, and epidermoid lesions. Many lesions that demonstrate restricted water motion on DWI require urgent attention. A rapid automated AI driven protocol would provide value to specialists and non-specialists who perform brain MRI with DWI to detect and prioritize scans performed at non-monitored inpatient and outpatient centers for urgent interpretation by a radiologist.


A 54-year-old man with hypertension, hyperlipidemia, and coronary artery disease presents to his internist on Wednesday morning with new onset dizziness and vertigo. His internist believes the patient’s symptoms are most compatible with benign positional vertigo but decides to order an outpatient brain MRI to exclude a cerebellar stroke as the cause of the new onset symptoms, given the patient’s vascular risk factors. The first available outpatient brain MRI appointment at the local imaging center is at 7 pm on Friday evening; the MRI is completed at 8 pm on Friday evening and demonstrates a large left posterior inferior cerebellar artery infarction causing fourth ventricular compression. No radiologist is available until Monday morning to review or interpret the examination, creating a dangerous delay in treatment for the patient over the weekend.

Workflow Description

Patient receives an MRI scan of their brain that includes the DWI sequence for various clinical indications, either at an inpatient or outpatient imaging site. Algorithm receives the DWI dataset immediately upon completion of the sequence. If the algorithm can determine a result, return: the presence of any brain regions that demonstrate restricted water motion on the DWI sequence. The MRI scan would then be prioritized on the radiology information system (RIS) worklist and an urgent notification will be sent to the covering/on-call radiologist to review the MRI.

Calculating DWI Water Motion Restriction

A reliability AI algorithm that can analyze the apparent diffusion coefficient (ADC) map that is generated from the diffusion weighted image (DWI) and determine regions of absolute restricted water motion within the brain, with assessment of the accuracy of the measurement, would also be very helpful. The apparent diffusion coefficient in tissue is expressed in units of mm2/s. ADC values less than 1000-1100 x 10-6 mm2/s) in the brain indicate restriction, although this is somewhat dependent upon the MRI hardware and software, imaging parameters, and pathology. Approximate normal ADC values in the brain are: white matter, 670-800; cortical grey matter, 800-1000; deep grey matter, 700-850; CSF, 3000-3400. Additional considerations are as follows: Algorithm executes before the exam is verified on PACS, when the MRI technologist or magnet pushes the DWI sequence with ADC map to a server as soon as it is completed. The indicator image and result may save to PACS as part of the medical record. Also, the algorithm must learn from prior results as to what constitutes true “restricted water diffusion” on the ADC map for each imaging center’s equipment and DWI parameters.

Considerations for Dataset Development



Sex at birth

Male, Female

ADC value

Continuous numeric


Acute ischemic infarction, anoxic brain injury, brain tumor, cerebral infection, epidermoid, seizure, traumatic brain injury


Left, right

Technical Specifications





Image DWI/ADC data for the study



Data Type



MRI Brain, diffusion weighted image with ADC map

Body Region


Anatomic Focus


Primary Outputs

DWI “Positive” Lesion

RadElement ID



Regions within the brain that demonstrate restricted water motion.

Data Type


Value Set






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