Introduction

NCR is a concept recognizer for annotating unstructured text with concepts from an ontology. In its core, NCR uses a deep neural network trained to classify input phrases with concepts in a given ontology, and is capable of generalizing to synonyms not explicitly available.

Requirements

• Python 3.5 or newer
• Tensorflow 1.13 or newer (>=2.0 currently not supported)
• fastText 0.9.1 or newer

Installation

Install the latest version of TensorFlow (NCR was developed using version 1.13). You can use pip for this:

$ pip3 install 'tensorflow-gpu>=1.13.0,<2.0.0' --force-reinstall

If you do not have access to GPUs, you can install the CPU version instead:

$ pip3 install 'tensorflow>=1.13.0,<2.0.0' --force-reinstall

Install fastText for python:

$ pip3 install fasttext

Install NCR by simply cloning this repository:

$ git clone https://github.com/ccmbioinfo/NeuralCR.git

To run NCR you need a trained NCR model. You can train the model on your own custom ontology as explained here. Alternatively, you can download a pre-trained NCR model from here, which is pre-trained on HPO, the Human Phenotype Ontology (release of 2019-06-03):

$ wget https://ncr.ccm.sickkids.ca/params/ncr_hpo_params.tar.gz
$ tar -xzvf ncr_hpo_params.tar.gz

To verify if the pre-trained NCR is working, you can use the interactive session (more details here) as follows:

$ python3 NeuralCR/interactive.py --params model_params/ --fasttext model_params/pmc_model_new.bin

Training

The following files are needed to start the training:

• The ontology file in .obo format.
• A file containing the word vectors prepared by the fasttext library
• [Optional] A corpus free of the ontology concepts to be used as a negative reference (to reduce concept recognition false positives)

The training can be performed using train.py.

The following arguments are mandatory:
  --obofile     location of the ontology .obo file
  --oboroot     the concept in the ontology to be used as root (only this concept and its descendants will be used)
  --fasttext    location of the fasttext word vector file
  --output      location of the directroy where the trained model will be stored
  
 The following arguments are optional:
  --neg_file    location of the negative corpus (text file)
  --epochs      Number of training epochs [80]
  --n_ensembles Number of ensembles [10]
  --flat        if this flag is passed, training will ignore the taxonomy information provided in the ontology

Example:

$ python3  train.py --obofile hp.obo --oboroot HP:0000118 --fasttext word_vectors.bin --neg_file wikipedia.txt --output model_params/

Using the trained model

Using in a python script

After training is finished, the model can be loaded inside a python script as follows:

import ncrmodel 
model = ncrmodel.NCR.loadfromfile(param_dir, word_model_file)

Where word_model_file is the addresss to the fasttext word vector file and param_dir is the address to the output directory of the training.

Then model can be used for matching a list of strings to the most similar concepts:

model.get_match(['retina cancer', 'kidney disease'], 5)

The first argument of the above function call is a list of phrases to be matched and the second argument is the number of top matches to be reported.

The model can be also used for concept recognition in a larger text:

model.annotate_text('The paitient was diagnosed with retina cancer', 0.8)

Where the first argument is the input text string and the second argument is the concept calling score threshold.

Concept recongition

Concept recognition can be also performed using annotate_text.py.

The following arguments are mandatory:
  --params      address to the directroy where the trained model parameters are stored
  --fasttext    address to the fasttext word vector file
  --input       address to the directory where the input text files are located
  --output      adresss to the directory where the output files will be stored
  
The following arguments are optional:
  --threshold   the score threshold for concept recognition [0.8]

Example:

$ python3 annotate_text.py --params model_params --fasttext word_vectors.bin --input documents/ --output annotations/

Interactive session

Concept recognition can be done in an interactive session through interactive.py. After the model is loaded, concept recognition will be performed on the standard input.

The following arguments are mandatory:
  --params      address to the directroy where the trained model parameters are stored
  --fasttext    address to the fasttext word vector file
  
The following arguments are optional:
  --threshold   the score threshold for concept recognition [0.8]

• Example: Run the script:

$ python3 interactive.py --params model_params --fasttext word_vectors.bin

Querry:

The patient was diagnosed with kidney cancer.

Output:

31	44	HP:0009726	Renal neoplasm	0.98976994

You can also link concepts to an isolated phrase by starting your query with >:

Querry:

>kidney cancer

Output:

HP:0009726 Renal neoplasm 0.98976994
HP:0005584 Renal cell carcinoma 0.0063989228
HP:0030409 Renal transitional cell carcinoma 0.0014158536
HP:0010786 Urinary tract neoplasm 0.00049688865
HP:0000077 Abnormality of the kidney 0.0003460226

Online Web App and API

A web app is available for NCR trained on HPO:

https://ncr.ccm.sickkids.ca/curr/

References

Please cite NCR if you have used it in your work.

@article{arbabi2019identifying,
  title={Identifying Clinical Terms in Medical Text Using Ontology-Guided Machine Learning},
  author={Arbabi, Aryan and Adams, David R and Fidler, Sanja and Brudno, Michael},
  journal={JMIR medical informatics},
  volume={7},
  number={2},
  pages={e12596},
  year={2019},
  publisher={JMIR Publications Inc., Toronto, Canada}
}