Kidney Stone Detection on CT

Purpose

To detect kidney, ureteral, or bladder stones on CT

Tag(s)

 

Panel

Abdominal

Define-AI ID

20020006

Originator

Luther B. Adair, II
Lead Luther B. Adair, II

Panel Chair

Arun Krishnaraj

Panel Reviewers

Abdominal Panel

License

Creative Commons 4.0 
Status Public Comment
RadElement Set RDES157 
                               

Clinical Implementation


Value Proposition


Ureterolithiasis and nephrolithiasis, collectively known as kidney stones, are debilitating illnesses and common causes of emergency visits. AI meeting this use case would help in detecting, quantitating, comparing, and alerting both nonspecialists and radiologists to these abnormalities. In clinical settings where a radiologist is not readily available, such detection would be of value to non-radiologists such as technologists who would perform a CT for this disease entity. In clinical settings where radiologists are available, such detection could be used to alert the radiologist and prioritize its reporting and notification to the treating physicians.

Narrative(s)


A 28-year old patient presents to an emergency room with radiating left flank pain at which time a CT scan is ordered.

Workflow Description


The relevant images are obtained from the modality and sent to PACS and the AI engine based on anatomic landmarks. The images are analyzed by the engine. The system then detects the relevant outputs providing associated categorical data or measurements. An alert message is sent it back to the engine with information, identification, and graphics highlighting the presence of a renal calcification, ureteral calcification, urinary bladder calcification, hydronephrosis, hydroureter, perinephric collection, or whether air is present in the anatomic region of concern.

An algorithm evaluates the CT scan and assesses whether renal calculi are present, absent, or undetermined. If present, it then counts the number of calculi in each kidney and measures the largest on each side. It also assesses whether a ureteral calculus is present, absent, or undetermined. If present, it then measures the maximal size of the calcification. Assesses whether a bladder calculus is present, absent, or undetermined. If present, it then measures the maximal size of the calcification. Assesses whether hydronephrosis is present, absent, or undetermined. The algorithm assesses whether hydroureter is present, absent, or undetermined and which side. Assesses whether a perinephric collection is present, absent, or undetermined and which side. The algorithm assesses whether air is present in the urinary tract, not present, or undetermined. For cases returned where the algorithm returns air is present within the region of concern or undetermined, hydronephrosis is present or undetermined, or if there is a stone in the ureter measuring greater than 5 mm, the exam is prioritized in the radiologist’s worklist for urgent interpretation and reporting.

Considerations for Dataset Development



Procedures

{CT Abdomen, CT Abdomen and pelvis, with contrast, without contrast}

View(s)

{sagittal, axial, coronal}

Age

[0,90]

Sex at Birth

{Male, Female}

Abdominal pain


{left flank pain, right flank pain}

Other

{hydroureter, hydronephrosis, perinephric fluid collection, air within the region of concern, bladder stone}

Confounding variables

{vascular calcifications (i.e. abdominal and pelvic phleboliths) , percutaneous nephrostomy, ureteral catheter, excreted contrast, soft tissue mass anywhere in the urinary tract with or without calcifications, clot/hemorrhage in the ureter or bladder, congenital anomalies (e.g. horseshoe kidney, cross-fused ectopia, ureteral duplications, ectopic ureters, ureterocele, etc), any prior urinary tract surgery and resulting altered anatomy (e.g. nephrectomy, partial nephrectomy, ileal conduit, neobladder, etc), metallic streak artifact (e.g. lumbar fusion)}

Technical Specifications


Inputs

DICOM Study

Procedure

CT Abdomen with contrast, CT Abdomen without contrast, CT Abdomen and Pelvis with contrast, CT Abdomen and Pelvis without contrast, CT Urography, CT Pelvis

Views

Axial, coronal, and sagittal

Data Type

DICOM

Modality

CT

Body Region

Abdomen and pelvis

Anatomic Focus

Kidneys, ureters, urinary bladder


Primary Outputs


Renal Caculi  Detection

RadElement ID

RDE1093

Definition

Detection of renal calcification

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Indeterminate

Units

N/A


Number of Renal Caculi 

RadElement ID

RDE1089

Definition

If renal caculi present, express the number of calculi present

Data Type

Numeric

Value Set

N/A

Units

N/A



Renal Calcification Measurement

RadElement ID

RDE1090

Definition

Measurement of renal calcification

Data Type

Numeric

Value Set

N/A

Units

millimeters


Ureteral Calcification Detection

RadElement ID

RDE1094

Definition

Detection of ureteral calcification

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Indeterminate

Units

N/A


Ureteral Calcification Measurement

RadElement ID

RDE1091

Definition

Measurement of ureteral calcification

Data Type

Numeric

Value Set

N/A

Units

millimeters


Bladder Calcification Detection

RadElement ID

RDE1095

Definition

Detection of bladder calcification

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Indeterminate

Units

N/A


Bladder Calcification Measurement

RadElement ID

RDE1092

Definition

Measurement of bladder calcification

Data Type

Measurement

Value Set

N/A

Units

millimeters





Secondary Outputs


Hydronephrosis Detection


RadElement ID

RDE1096

Definition

Detection of hydronephrosis as a function of laterality

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Unknown

Units

N/A


Hydronephrosis Kidney Laterality


RadElement ID

RDE1097

Definition

If Hydronephrosis is present, identify which kidney demonstrates this feature

Data Type

Categorical

Value Set

  • Left

  • Right

  • Unknown

Units

N/A



Hydroureter Detection


RadElement ID

RDE1098

Definition

Detection of hydroureter as a function of laterality

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Unknown

Units

N/A


Hydroureter Kidney Laterality 


RadElement ID

RDE1099

Definition

If Hydroureter is present,identify which kidney demonstrates this feature

Data Type

Categorical

Value Set

  • Left

  • Right

  • Unknown

Units

N/A



Perinephric Fluid Detection


RadElement ID

RDE1100

Definition

Detection of perinephric fluid as a function of laterality

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Unknown

Units

N/A


Perinephric Fluid Kidney Laterality


RadElement ID

RDE1101

Definition

If perinephric fluid is present, identify which kidney demonstrates this feature

Data Type

Categorical

Value Set

  • Left

  • Right

  • Unknown

Units

N/A



Air in the Urinary Tract


RadElement ID

RDE1102

Definition

Detection of air anywhere in the urinary tract

Data Type

Categorical

Value Set

  • Absent

  • Present

  • Unknown

Units

N/A

Future Development Ideas


  • In the case of renal calculus, the type of calculus could be further characterized by noting the density of the stone in Hounsfield units. Future consideration for characterizing hydronephrosis as mild, moderate, and severe based on how specific the algorithm can identify the value of hydronephrosis and distinguish this stratification.   

  • One possible extension to this use case is to detect nephrolithiasis and ureteral lithiasis on CT and assess the need for further treatment based on the absence or presence of complications.