idc-index Command Line Interface Guide

idc-index Command Line Interface Guide

The idc-index package provides command-line tools for downloading DICOM data from the NCI Imaging Data Commons without writing Python code.

Installation

pip install --upgrade idc-index

After installation, the idc command is available in your terminal.

Available Commands

idc download

General-purpose download command that intelligently interprets input. It determines whether the input corresponds to a manifest file path or a list of identifiers (collection_id, PatientID, StudyInstanceUID, SeriesInstanceUID, crdc_series_uuid).

Usage

# Download entire collection
idc download rider_pilot --download-dir ./data

# Download specific series by UID
idc download "1.3.6.1.4.1.9328.50.1.69736" --download-dir ./data

# Download multiple items (comma-separated)
idc download "tcga_luad,tcga_lusc" --download-dir ./data

# Download from manifest file (auto-detected by file extension)
idc download manifest.txt --download-dir ./data

Options

Directory Template Variables

Use these variables in --dir-template to organize downloads:

• %collection_id - Collection identifier
• %PatientID - Patient identifier
• %StudyInstanceUID - Study UID
• %SeriesInstanceUID - Series UID
• %Modality - Imaging modality (CT, MR, PT, etc.)

Examples:

# Flat structure (all files in one directory)
idc download rider_pilot --download-dir ./data --dir-template ""

# Simplified hierarchy
idc download rider_pilot --download-dir ./data --dir-template "%collection_id/%PatientID/%Modality"

idc download-from-manifest

Specialized for downloading from manifest files with built-in validation, progress tracking, and resume capability.

Usage

# Basic download from manifest
idc download-from-manifest --manifest-file cohort.txt --download-dir ./data

# With progress bar and validation
idc download-from-manifest --manifest-file cohort.txt --download-dir ./data --show-progress-bar

# Resume interrupted download with s5cmd sync
idc download-from-manifest --manifest-file cohort.txt --download-dir ./data --use-s5cmd-sync

Options

Manifest File Format

Manifest files contain S3 URLs, one per line:

s3://idc-open-data/cb09464a-c5cc-4428-9339-d7fa87cfe837/*
s3://idc-open-data/88f3990d-bdef-49cd-9b2b-4787767240f2/*

How to get a manifest file:

1. IDC Portal: Export cohort selection as manifest
2. Python query: Generate from SQL results

from idc_index import IDCClient

client = IDCClient()
results = client.sql_query("""
    SELECT series_aws_url
    FROM index
    WHERE collection_id = 'rider_pilot' AND Modality = 'CT'
""")

with open('ct_manifest.txt', 'w') as f:
    for url in results['series_aws_url']:
        f.write(url + '\n')

idc download-from-selection

Download data using filter criteria. Filters are applied sequentially.

Usage

# Download by collection
idc download-from-selection --collection-id rider_pilot --download-dir ./data

# Download specific series
idc download-from-selection --series-instance-uid "1.3.6.1.4.1.9328.50.1.69736" --download-dir ./data

# Multiple filters
idc download-from-selection --collection-id nlst --patient-id "100004" --download-dir ./data

# Dry run - see what would be downloaded without actually downloading
idc download-from-selection --collection-id tcga_luad --dry-run --download-dir ./data

Options

Dry Run for Size Estimation

Use --dry-run to estimate download size before committing:

idc download-from-selection --collection-id nlst --dry-run --download-dir ./data

This shows:

• Number of series matching filters
• Total download size
• No files are downloaded

Common Workflows

1. Download Small Collection for Testing

# rider_pilot is ~1GB - good for testing
idc download rider_pilot --download-dir ./test_data

2. Large Dataset with Progress and Resume

# Use s5cmd sync for large downloads - can resume if interrupted
idc download-from-selection \
    --collection-id nlst \
    --download-dir ./nlst_data \
    --show-progress-bar \
    --use-s5cmd-sync

3. Estimate Size Before Download

# Check size first
idc download-from-selection --collection-id tcga_luad --dry-run --download-dir ./data

# Then download if size is acceptable
idc download-from-selection --collection-id tcga_luad --download-dir ./data

4. Download Specific Modality via Python + CLI

# First, query for series UIDs in Python
from idc_index import IDCClient

client = IDCClient()
results = client.sql_query("""
    SELECT SeriesInstanceUID
    FROM index
    WHERE collection_id = 'nlst'
      AND Modality = 'CT'
      AND BodyPartExamined = 'CHEST'
    LIMIT 50
""")

# Save to manifest
results['SeriesInstanceUID'].to_csv('my_series.csv', index=False, header=False)

# Then download via CLI
idc download my_series.csv --download-dir ./lung_ct

Built-in Safety Features

The CLI includes several safety features:

• Disk space checking: Verifies sufficient space before starting downloads
• Manifest validation: Validates manifest file format by default
• Progress tracking: Optional progress bar for monitoring large downloads
• Resume capability: Use --use-s5cmd-sync to continue interrupted downloads

Troubleshooting

Download Interrupted

Use --use-s5cmd-sync to resume:

idc download-from-manifest --manifest-file cohort.txt --download-dir ./data --use-s5cmd-sync

Connection Timeout

For unstable networks, download in smaller batches using Python to generate multiple manifests, then download sequentially.

See Also

• idc-index Documentation
• IDC Portal - Interactive cohort building
• IDC Tutorials