Magnetic resonance imaging overestimates patellar height compared with radiographs

Area of Science:

• Orthopedics
• Radiology
• Medical Imaging

Background:

• Accurate measurement of patellar height is crucial for diagnosing and managing knee conditions.
• Conventional radiography (CR) and magnetic resonance imaging (MRI) are commonly used imaging modalities.
• Assessing the reliability of patellar height measurements between CR and MRI is essential for clinical decision-making.

Purpose of the Study:

• To evaluate the inter-observer and inter-method reliability of patellar height measurements.
• To compare measurements obtained from conventional radiographs (CR) and magnetic resonance imaging (MRI) using one or two slices.
• To determine if MRI overestimates patellar height compared to CR.

Main Methods:

• A reliability study involving 60 patients (30 with patellar instability, 30 controls).
• Measurements of Insall-Salvati index (IS) and Caton-Deschamps index (CD) were taken using CR, one-slice MRI, and two-slice MRI.
• Inter-observer and inter-method reliability were assessed using intra-class correlation coefficients (ICC) and Bland-Altman analysis.

Main Results:

• High inter-observer reliability was found for both IS (ICCs 0.93-0.82) and CD (ICCs 0.76-0.75) across CR and MRI methods.
• Inter-method analysis showed good reliability between CR and MRI techniques (ICCs for IS 0.83-0.93, CD 0.72-0.83).
• MRI demonstrated an overestimation of patellar height compared to CR, with IS values increasing by 7-8% and CD values by up to 9%.

Conclusions:

• Magnetic resonance imaging (MRI) can overestimate patellar height measurements compared to conventional radiographs (CR).
• The overestimation can be significant, up to 8% for Insall-Salvati index and 9% for Caton-Deschamps index.
• Conventional radiography (CR) is recommended as the preferred method for accurate patellar height measurements.