Determination of Programmable Shunt Setting Using CT: Feasibility Study.

Area of Science:

• Neurosurgery
• Medical Imaging
• Biomedical Engineering

Background:

• Programmable shunts optimize cerebrospinal fluid (CSF) diversion in hydrocephalus patients, adjustable without re-operation.
• Current shunts use radiopaque markers for setting determination via skull X-rays.
• Head CT scans are common for VP shunt patients presenting with symptoms, offering a potential imaging alternative.

Purpose of the Study:

• To evaluate the feasibility of determining programmable shunt settings ex vivo and in vivo using standard head CT scan data.
• To assess if CT scan data can replace X-rays for shunt setting verification.

Main Methods:

• Four programmable shunts (Certas Plus, Polaris, proGAV 2.0, Hakim) were scanned on a dried skull using various CT techniques (kVp, mAs, CTDIvol).
• Image reconstruction with and without CT metal suppression software was performed, generating volume-rendered images.
• Ten observers predicted shunt settings from volume-rendered images, with one clinical case evaluated.

Main Results:

• Polaris shunt settings were predicted with 100% accuracy; Certas Plus with 90% accuracy.
• Hakim and proGAV 2.0 shunts showed 0% and 10% prediction accuracy, respectively.
• A programmable valve setting was successfully determined from a clinical CT scan.

Conclusions:

• Shunt valve settings for at least two programmable shunts can be determined from CT-generated volume-rendered images.
• Metal suppression software improved image quality and may be essential for certain valve designs.
• CT-based shunt setting determination offers a potential non-invasive alternative to X-rays.