What is the recommended MRI protocol for diagnosing luxury perfusion?

MRI Protocol for Diagnosing Luxury Perfusion Syndrome

The recommended MRI protocol for diagnosing luxury perfusion should include perfusion-weighted imaging (PWI) combined with diffusion-weighted imaging (DWI) to identify the mismatch pattern characteristic of luxury perfusion, along with standard structural sequences. 1

Core MRI Sequences for Luxury Perfusion Assessment

Essential Sequences

• Perfusion-weighted imaging (PWI):

  • Contrast-enhanced dynamic susceptibility contrast (DSC) perfusion to assess cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) 1
  • Arterial spin labeling (ASL) as a non-contrast alternative 2

• Diffusion-weighted imaging (DWI):

  • To identify cytotoxic edema and core infarct tissue 1, 2
  • Essential for DWI-PWI mismatch assessment 1

• T2-weighted FLAIR:

  • For subacute infarct visualization and edema assessment 1, 2

• T2-weighted gradient echo (GRE) or susceptibility-weighted imaging (SWI)*:

  • To exclude hemorrhage 1, 2

Supplementary Sequences

• MR angiography (MRA):

  • To evaluate vascular patency and identify occlusions 1, 2
  • Can be performed without or with contrast 1

• T1-weighted imaging:

  • Pre- and post-contrast to assess blood-brain barrier disruption 1

Interpretation Parameters for Luxury Perfusion

Luxury perfusion is characterized by:

1. Increased regional cerebral blood flow (rCBF) relative to metabolic demand 1
2. Normal or elevated cerebral blood volume (CBV) in the affected area 1
3. Decreased mean transit time (MTT) 1
4. Mismatch between perfusion and diffusion imaging showing hyperperfusion in an area with restricted diffusion or adjacent to it 3, 4

Technical Considerations

• Timing: Luxury perfusion typically occurs in the subacute phase of ischemic stroke (2-7 days after onset) 5
• Positioning: Patient position may affect luxury perfusion visualization - supine position may enhance the phenomenon compared to sitting position 5
• Contrast administration: Single dose gadolinium (0.1 mmol/kg) with minimum 5-minute delay between injection and T1-weighted sequence acquisition 1
• Acquisition parameters:
  • Maximum slice thickness: 3 mm
  • In-plane spatial resolution: 1 × 1 mm 1

Clinical Applications and Pitfalls

Clinical Applications

• Identification of reperfusion after stroke treatment
• Assessment of collateral circulation
• Evaluation of tissue viability in ischemic penumbra
• Differentiation between hyperperfusion syndromes and ongoing ischemia 4, 5

Common Pitfalls

• Misinterpretation risk: Luxury perfusion can be misinterpreted as neovascularization or capillary hemangioma on conventional imaging 6
• Timing considerations: Luxury perfusion is a dynamic phenomenon that changes over time; imaging too early or too late may miss the phenomenon 5
• Contrast contraindications: In patients with renal impairment (eGFR <30 mL/min/1.73m²), non-contrast ASL perfusion should be used instead of gadolinium-based techniques 1, 2

Protocol Optimization

• Total acquisition time should be kept under 25-30 minutes 1
• For acute stroke evaluation where time is critical, prioritize DWI and perfusion sequences 2
• In cases where MRI is contraindicated, CT perfusion can be considered as an alternative 1

By implementing this comprehensive protocol, clinicians can accurately identify luxury perfusion syndrome, which is characterized by increased blood flow relative to metabolic demand in post-ischemic tissue, helping guide appropriate management decisions.