Content
Keywords
Clinical description
Age (see Table 17.2)
Height
Weight
BSA
Diagnosis
Previous surgeries
Imaging source
Segmentation method
Units of measure
Scale
Institution
Submitting author
3D Model File
The digital model (.stl file or other acceptable formats) should accurately represent source DICOM data. Segmentation techniques are categorized into one of the three methodology types as described below. Poorly rendered models that deviate too far from the source image will be rejected.
DICOM Data
De-identified image datasets in the Digital Imaging and Communications in Medicine (DICOM) format are required to be submitted with the model, both for the peer-review process as well as to provide a reference for segmentation analysis. A 3D imaging dataset which is free of artifact with resolution between 1 and 1.5 mm isovoxels is ideal. Datasets with resolution or artifacts that do not allow for accurate reproduction of anatomy will not be accepted due to the increased risk of false data transmission to the digital model.
Protecting Patient Information
Sharing case study details and raw medical image data is critical to the Library. Extra care must be taken to protect patient privacy when making clinical data available to the public. Concern for HIPAA compliance may create a barrier for clinicians who wish to submit their 3D case reports. We have extensively evaluated HIPAA requirements to ensure that contributions to the library do not violate patient privacy. If no Personal Health Information (PHI) is included in the data, then the data does not fall under the HIPAA Privacy Rule [15]. All content contributed to the Heart Library will not contain PHI. The submitting clinician is responsible for reviewing and removing any PHI prior to uploading data for peer review. Two methods to de-identify PHI are the “Safe Harbor” method and/or the use of a statistician to limit risk. The former requires removal of all 18 identifiers enumerated at section 164.514(b)(2) of the regulation (Table 17.2) and for the purposes of the Heart Library is the only acceptable method for submission.
Table 17.2
18 PHI identifiers of the HIPAA Privacy Rule
1. Names |
2. All geographic subdivisions smaller than a state, except for the initial three digits of the ZIP code if the geographic unit formed by combining all ZIP codes with the same three initial digits contains more than 20,000 people |
3. All elements of dates except year, and all ages over 89 or elements indicative of such age |
4. Telephone numbers |
5. Fax |
6. E-mail addresses |
7. Social security numbers |
8. Medical records numbers |
9. Health plan beneficiary numbers |
10. Account numbers |
11. Certificate or license numbers |
12. Vehicle identifiers and license plate numbers |
13. Device identifiers and serial numbers |
14. URLs |
15. IP addresses |
16. Biometric identifiers |
17. Full-face photographs and any comparable images |
18. Any other unique, identifying characteristic or code, except as permitted for re-identification in the Privacy Rule |
Utmost care must be taken by the submitting physician or organization in de-identifying DICOM data. The NIH 3D Print Exchange also has tools in place to automatically remove PHI that is named in the HIPAA Privacy Rule (see Table 17.2). Having redundancy in checking for privacy data will significantly minimize liability.
3D Rendering Quality, Methods, and Review
The peer-review aspect of the Library is essential to providing verification that a digital 3D model is a true representation of the source 2D medical image series. In the field of congenital heart disease, expertise in both congenital heart imaging and 3D model creation is not well-established. It is therefore difficult to define quality in an emerging field such as this. In collaboration with recognized leaders in 3D printing and modeling of cardiac anatomy, we established standards and methods for model creation and evaluation.
Defining “Quality”
The aim of this part of the process was to build a high-quality assessment method that would be reproducible and quantifiable, yet also adaptable. This difficult task involved defining the segmentation method and the assessment process itself. As has been described in previous chapters, the current postprocessing technology involves creating a “mask” over 2D images to identify the structures to be printed. Therefore, the current set of methodologies and peer-review processes are tied to visual interpretation of a 2D image in a 3D dataset and manual translation into the 3D form.
Methodologies
An expert panel identified the various methods of segmentation currently used to generate 3D cardiac models and created categorical definitions. The quality of the source image data is also evaluated. Color coding of anatomic models is recommended to follow the convention laid out by Frakes et al. [16] Based on current techniques, segmentation has been separated into 3 methods: (1) solid blood pool (2) blood pool/myocardial border, and (3) myocardium and vessel wall.