Determining Scanned Body Part from DICOM Study Description for Relevant

Prior Study Matching

Thusitha Mabotuwana, Yuechen QianPhilips Research North America21 August 2013

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Exam Protocoling

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Typical radiology workflow

Imaging order(fax/e-referral)

HL7

HL7

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DICOM

Exam Protocoling

Imaging order(fax/e-referral)

Typical radiology workflow

DICOM

HL7

HL7

HL7

Reporting

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Exam Protocoling

Imaging order(fax/e-referral)

Reporting

Typical radiology workflow

DICOM

HL7

HL7

HL7

DICOM

Background

• Radiologists need to understand the clinical context when reading a new study.

• Most relevant prior study is often used as the reference to compare current findings against.

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Current status

- Important to find the correct prior study for comparison. - Determining relevant prior study is not always straight-forward, especially

with complex patients having many (e.g., >20) studies for multiple conditions.

Current status – opportunity for improvement

- Typically, matching is done based on scanned body part (e.g., Head, Abdomen) corresponding to Body Part Examined field in DICOM (0018, 0015)

- Body part field of the DICOM header is fairly generic- e.g., Study done to exclude pancreatitis and another study done to

exclude renal stones will both have their body part field set to “abdomen”

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A typical DICOM header

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Our approach

Identified other DICOM attributes containing anatomy related information.

- DICOM Study Description (0008, 1030) field- e.g., CT CHEST ABD/PEL LIVER

- DICOM Protocol Name (0018, 1030) field- e.g., C/A/P W/ARTERIAL LIVER/Abdomen

- DICOM Series Description(0008, 103e) field- e.g., LUNGS, Coronal

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DICOM Study Description field

Narrative, free-text and institution-specific terms (i.e., non-standardized).- Abbreviations (e.g., UE – upper extremity)- Synonyms (e.g., neuro)- Procedure names (e.g., mammogram)

- Can an algorithm be developed to reliably extract the most specific anatomy information from DICOM Study Description field?

Modality Body Part Examined Study Description

CT ABDOMEN CT ABDOMEN WITH CONT SPLEENCT ABDOMEN CT NEEDLE BIOPSY LIVERRF ABDOMEN XR PERITONEOGRAMUS ABDOMEN US PORT RENAL LTDCT ABDOMEN CT ABDOMEN W/O KIDNEYSCT ABDOMEN CT ABDOMEN WO PANCREAS

MRI BONE MRI ANKLE/FOOT W RTRF BONE XR KNEE ARTHROGRAM RTCR BONE XR PORT ANKLE 2 VIEWS LTCT CARDIAC CT HEART W/WO GAIT 3D CNT FNC EVLCT CHEST CT ANGIO CARDIAC WWORF GI XR UGI W KUBXC GI GIEC COLON

MRI NEURO MRI P PITUITARY WOUS NEURO US PORT NECK THYROID/SOFT TISSUE

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System overview

Preprocessing (e.g., stop word removal)

Word normalization (e.g., global abbreviation replacement – ‘LT’)

Anatomy extraction using word combinations

Procedure-related anatomy extraction (e.g., mammogram)

Postprocessing of extracted anatomies

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Algorithm development – reference taxonomy

- 160 unique concepts were included in the taxonomy with an additional 87 terms included as synonyms or abbreviations

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Algorithm development – reference taxonomy features

1. Parent-child relationship between concepts. 2. Multiple abbreviations and/or synonyms.3. Child concepts inherit properties from parents (e.g., laterality)4. Concepts should be interpreted within the context of its ancestor (e.g.,

‘soft tissues’ may appear multiple times in the taxonomy, but MRI P FACE SOFT TISSUE W would match to ‘face soft tissues’).

5. The taxonomy is a representation of intention of procedure (e.g., a mammogram study description – MAM BILAT DIGITAL W/CAD does not explicitly mention ‘breast’).

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

20

Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

Regex based anatomy extraction:(?=.*\bank).*(?=.*\bfoo).*(?=.*\blef).*

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Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

22

Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

23

Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

24

Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

25

Input string

Remove stop words and special characters; convert to lower case

Empty or null string Return

Replace known global abbreviations (e.g., LT with left)

Determine word combinations for input string in descending order

Process next word combination

MRI ANKLE/FOOT WWO LT

mri ankle foot lt

mri ankle foot left

Determine modality and replaceankle foot left

left foot left ankle

Match found? Add matched term to list

All combinations for current iteration finished?

Replace matched terms from input string

Empty input string or all combinations processed

i) ankle foot leftii) ankle foot foot left ankle left

Yes Show children concepts?

No

Yes

Yes

Yes

No

No

Noleft foot

Intelligent filtering

Algorithm validation

- Extracted 1604 production study descriptions from an academic institution- Used 1200 (~80%) for algorithm development

- 404 used for testing

- Accuracy of system was 99.94%. - (XR SACRUM COCCYX 2 VIEWS MIN was the false-negative)

Body part extracted

Ground Truth (n=1200)

True False

True 1057 0

False 0 143

Body part extracted

Ground Truth (n=404)

True False

True 197 0

False 1 206

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Results

Study Description Extracted Body Part CategoryCT ABDOMEN WITH CONT SPLEEN Spleen Direct matchCT NEEDLE BIOPSY LIVER Liver Direct matchCT HEART W/WO GAIT 3D Heart Direct matchCT ABDOMEN W/O KIDNEYS Kidney Direct matchCT ABDOMEN W/O PANCREAS Pancreas Direct matchGIEC COLON Colon Direct matchMRI P PITUITARY WO Pituitary Direct matchMRI ANKLE/FOOT W RT Right ankle, right foot Direct match + lateralityXR KNEE ARTHROGRAM RT Right knee Direct match + lateralityXR PORT ANKLE 2 VIEWS LT Left ankle Direct match + lateralityUS PORT NECK THYROID/SOFT TISSUE Neck, thyroid soft tissue Direct match + post processingXR PERITONEOGRAM Peritoneum ProcedurePOSITRON EMISSION MAMMOGRAPHY Breast ProcedureUS PORT RENAL LTD Kidney SynonymXR UGI W KUB Upper gastrointestinal tract Abbreviation

Limitations

- Dataset is from one institution and therefore abbreviations and algorithms may need to be generalizable across institutions.

- The reference taxonomy is not complete and represents only concepts encountered in the training set, as well as those included based on authors’ domain experience

Key messages

- Knowing the most specific body part of an imaging study is important for relevant prior study matching.

- A regular expression based technique can be used to extract specific anatomy information from DICOM Study Description.

Questions?

Thusitha Mabotuwanathusitha.mabotuwana@philips.com

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