What is the recommended MRI brain protocol with or without contrast for monitoring a Ventriculoperitoneal (VP) shunt?

From the Guidelines

The recommended MRI brain protocol for monitoring a Ventriculoperitoneal (VP) shunt should prioritize non-contrast sequences, with contrast administration reserved for cases with strong clinical suspicion of complications such as infection, inflammation, or tumor recurrence, as the use of contrast may not be necessary for routine follow-up of uncomplicated shunts. When monitoring a VP shunt, the primary goal is to assess ventricular size and detect potential shunt malfunction, which can be achieved through non-contrast MRI sequences such as T1-weighted images, T2-weighted images, FLAIR, DWI, and gradient echo sequences 1. The protocol should include thin-slice high-resolution images through the ventricular system to evaluate ventricular size and shunt catheter position, with special attention to the ventricular system in sagittal, axial, and coronal planes. Key considerations in the imaging protocol include:

• The use of fast imaging techniques like SSFP to visualize the catheter itself
• The importance of comparing current imaging with prior studies to detect subtle changes in ventricular size, as emphasized in the policy statement on optimizing advanced imaging of the pediatric patient in the emergency department 1
• The potential to defer imaging if there is strong clinical suspicion of shunt malfunction without baseline imaging available, and instead perform it where definitive treatment can be delivered 1. In terms of specific sequences, a comprehensive protocol may include:
• T1-weighted images without contrast to evaluate ventricular size and shunt catheter position
• T2-weighted images and FLAIR to assess surrounding brain parenchyma
• DWI to detect potential complications such as infection or hemorrhage
• Gradient echo sequences to evaluate shunt catheter patency
• Post-gadolinium T1-weighted images with contrast when indicated, such as in cases of suspected infection, inflammation, or tumor recurrence.

From the FDA Drug Label

1.1 MRI of the Central Nervous System (CNS) Gadoteridol Injection is indicated for magnetic resonance imaging (MRI) in adults and pediatric patients including term neonates to visualize lesions with disrupted blood brain barrier and/or abnormal vascularity in the brain (intracranial lesions), spine and associated tissues.

The recommended MRI brain protocol with or without contrast for monitoring a Ventriculoperitoneal (VP) shunt is not explicitly stated in the provided drug labels. However, Gadoteridol Injection is indicated for MRI of the CNS to visualize lesions with disrupted blood brain barrier and/or abnormal vascularity in the brain.

• The recommended dose for adult and pediatric patients is 0.2 mL/kg (0.1 mmol/kg) administered as a rapid intravenous infusion or bolus.
• A supplementary dose of 0.4 mL/kg (0.2 mmol/kg) may be given up to 30 minutes after the first dose in adult patients with normal renal function suspected of having poorly visualized CNS lesions. 2

From the Research

MRI Brain Protocol for Monitoring VP Shunt

• The recommended MRI brain protocol for monitoring a Ventriculoperitoneal (VP) shunt is not explicitly stated in the provided studies, but some studies suggest the use of specific MRI techniques to evaluate shunt malfunction 3, 4.
• Phase-contrast cine magnetic resonance imaging (PC cine MRI) can be used to evaluate the cerebrospinal fluid (CSF) flow dynamics of VP shunt and improve the diagnosis of shunt malfunction 4.
• The use of Gadolinium-Based Contrast agents (GBCAs) in MRI examinations is associated with an excellent safety profile, but recent advances in MRI technology have made GBCA injection avoidable in many indications 5.
• There is no specific recommendation for the use of contrast agents in MRI brain protocol for monitoring VP shunt, but the French Society of Neuroradiology (SFNR) provides consensus guidelines on the use of GBCAs and related MRI protocols in Neuroradiology 5.

Diagnostic Value of MRI in VP Shunt Complications

• MRI has a sensitivity of 57% and specificity of 93% in evaluating shunt malfunction, with a likelihood ratio (LR+) of 7.66 and LR- of 0.49 3.
• A positive MRI result has a post-test probability of 83%, while a negative result has a post-test probability of 7-31% 3.
• Low-dose computed tomography (LD-CT) has a higher sensitivity (0.97) and diagnostic confidence compared to radiographic shunt series (SS), with lower radiation exposure 6.

Nursing Care and Complications

• Nurses may care for patients who have undergone shunt placement or revision, and should be aware of possible complications and nursing care for patients following a shunt placement procedure 7.
• The diagnosis of VP shunt malfunction is an emergency, and timely diagnosis can be challenging due to symptoms mimicking other common conditions 3.