I've been trying to find out a way to retrieve the Objective Power (or Magnification) of a Whole Slide Image file without downloading it first. I've seen that some WSI's Objective power might be 40x and others 20x, and I need a way to filter the ones I want to retrieve according with this parameter. However, I cannot figure out the query I need for this. Can anyone help me

Some details:

I'm using the GDC API (https://gdc.cancer.gov/developers/gdc-application-programming-interface-api) to retrieve Whole Slide Image files (in this case .svs files).

I want to retrieve this files according with its Objective Power, since images in the TCGA dataset (https://www.genome.gov/Funded-Programs-Projects/Cancer-Genome-Atlas) might have 20x or 40x of objective power.

One way to do this is to retrieve the whole image using the data endpoint of the GDC API and then use a library like Openslide to check the objective power:

import requests
from io import BytesIO
import openslide

# Set up the GDC API endpoint
endpoint = 'https://api.gdc.cancer.gov/data'

# Set up the query parameters
query = {
    'ids': ['my_file_id'],

# Send the request to the GDC API
response = requests.get(endpoint, params=query)

# Retrieve the binary data from the response
binary_data = BytesIO(response.content)

# Open the WSI file using the Openslide library
slide = openslide.open_slide(binary_data)

# Retrieve the Objective Power of the WSI
objective_power = slide.properties.get(openslide.PROPERTY_NAME_OBJECTIVE_POWER)

print('Objective Power:', objective_power)

However, retrieving the whole file takes too much time, so I would like to know if anybody knows of a field in the GDC API that allows me to check the objective power of a WSI without retrieving the file itself.



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