Determining Scanned Body Part from DICOM Study Description

Determining Scanned Body Part from DICOM Study Description for Relevant Prior Study Matching Thusitha Mabotuwana, Yuechen Qian Philips Research North America 21 August 2013

Typical radiology workflow Imaging order (fax/e-referral) HL 7 Exam Protocoling 2

Typical radiology workflow Imaging order (fax/e-referral) DICOM HL 7 Reporting DICOM HL 7 Exam Protocoling 3

Typical radiology workflow Imaging order (fax/e-referral) DICOM HL 7 Reporting DICOM HL 7 Exam Protocoling 4

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.

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. 6

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” 8

A typical DICOM header 9

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, 103 e) field - e. g. , LUNGS, Coronal 10

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) Modality Body Part Examined CT CT RF US CT CT MRI RF CR CT CT RF XC ABDOMEN ABDOMEN BONE CARDIAC CHEST GI GI MRI US NEURO Study Description CT ABDOMEN WITH CONT SPLEEN CT NEEDLE BIOPSY LIVER XR PERITONEOGRAM US PORT RENAL LTD CT ABDOMEN W/O KIDNEYS CT ABDOMEN WO PANCREAS MRI ANKLE/FOOT W RT XR KNEE ARTHROGRAM RT XR PORT ANKLE 2 VIEWS LT CT HEART W/WO GAIT 3 D CNT FNC EVL CT ANGIO CARDIAC WWO XR UGI W KUB GIEC COLON MRI P PITUITARY WO US PORT NECK THYROID/SOFT TISSUE - Can an algorithm be developed to reliably extract the most specific anatomy 11 information from DICOM Study Description field?

System overview Preprocessing (e. g. , stop word removal) Word normalization (e. g. , global abbreviation replacement – ‘LT’) Procedure-related anatomy extraction (e. g. , mammogram) Anatomy extraction using word combinations Postprocessing of extracted anatomies 12

Algorithm development – reference taxonomy - 160 unique concepts were included in the taxonomy with an additional 87 terms included as synonyms or abbreviations 13

Algorithm development – reference taxonomy features 1. 2. 3. 4. Parent-child relationship between concepts. Multiple abbreviations and/or synonyms. Child concepts inherit properties from parents (e. g. , laterality) 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’). 14

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 15

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 16

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 17

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 18

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 19

MRI ANKLE/FOOT WWO LT mri ankle foot lt mri ankle foot left Input string Empty or null string Return Remove stop words and special characters; convert to lower case Regex based anatomy extraction: (? =. *bank). *(? =. *bfoo). *(? =. *blef). * Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 20

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 21

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 22

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 23

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 24

MRI ANKLE/FOOT WWO LT Input string Empty or null string mri ankle foot lt Remove stop words and special characters; convert to lower case mri ankle foot left Replace known global abbreviations (e. g. , LT with left) ankle foot left Determine modality and replace i) ankle foot left ii) ankle foot left ankle left Determine word combinations for input string in descending order Empty input string or all combinations processed Return Yes Intelligent filtering Show children concepts? left foot left ankle No left foot No Process next word combination Yes Match found? Add matched term to list No All combinations for current iteration finished? No Yes Replace matched terms from input string 25

Algorithm validation - Extracted 1604 production study descriptions from an academic institution - Used 1200 (~80%) for algorithm development Body part extracted Ground Truth (n=1200) True False True 1057 0 False 0 143 - 404 used for testing Body part extracted True False True 197 0 False 1 206 - Accuracy of system was 99. 94%. - Ground Truth (n=404) (XR SACRUM COCCYX 2 VIEWS MIN was the false-negative)

Results Study Description CT ABDOMEN WITH CONT SPLEEN CT NEEDLE BIOPSY LIVER CT HEART W/WO GAIT 3 D CT ABDOMEN W/O KIDNEYS CT ABDOMEN W/O PANCREAS GIEC COLON MRI P PITUITARY WO MRI ANKLE/FOOT W RT XR KNEE ARTHROGRAM RT XR PORT ANKLE 2 VIEWS LT US PORT NECK THYROID/SOFT TISSUE XR PERITONEOGRAM POSITRON EMISSION MAMMOGRAPHY US PORT RENAL LTD XR UGI W KUB Extracted Body Part Category Spleen Liver Heart Kidney Pancreas Colon Pituitary Right ankle, right foot Right knee Left ankle Neck, thyroid soft tissue Peritoneum Breast Kidney Upper gastrointestinal tract Direct match Direct match + laterality Direct match + post processing Procedure Synonym Abbreviation 27

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 Mabotuwana thusitha. mabotuwana@philips. com 30