Imaging Tests for the Detection of Osteomyelitis: A Systematic Review

SLR - February 2021 - Laurel Yee

Level of Evidence: Level 3 

Scientific Literature Review

Reviewed By: Laurel Yee, DPM
Residency Program: NYU Langone Brooklyn, Brooklyn, NY 

Podiatric Relevance: Osteomyelitis is an extremely common pathology that we come across as podiatrists. MRI is commonly referred to as the “gold standard” for diagnosing osteomyelitis. This article reviews the efficacy of MRI vs SPECT vs PET for diagnosis of osteomyelitis, as well as other less common imaging modalities. 

Methods: A database search was performed including MEDLINE for systematic review of imaging test to diagnose osteomyelitis. They used a total of 81 different studies. They assessed the risk of bias within the study using QUADAS-2 (quality assessment of diagnostic accuracy studies version two), and diagnostic accuracy was assessed using bivariate regression models. 

Results:
• In adults, MRI: 95.6 percent sensitivity; 80.7 percent specificity
• PET: 85.1 percent sensitivity, 92.8 percent specificity
• SPECT: 95.1 percent sensitivity, 82.0 percent specificity 
• Cintigraphy: 83.6 percent sensitivity, 70.6 percent specificity
• Computed tomography 69.7 percent sensitivity, 90.2 percent specificity
• Radiography 70.4 percent sensitivity, 81.5 percent specificity
• Technetium-99m hexamethylpropyleneamine oxime white blood cell scintigraphy: 87.3 percent sensitivity, 94.7 percent specificity

Conclusions:
• The authors concluded that osteomyelitis is reliably diagnosed by MRI, PET and SPECT, so there is very little indication for preferring one test over the other. However, they prefer MRI due to the wider accessibility of MRI in most facilities, and the decreased risk of exposing patient to ionizing radiation found in the other two imaging modalities. 
• Most specific imaging modality: Tech-99m, most sensitive: MRI 
• No evidence that diagnostic accuracy changes based on scan location or the cause of osteomyelitis 
• Not enough results to draw conclusions regarding pediatric patients 
• MRI had acceptable inter-rater reliability (based on 11 of the studies reviewed)
• The sensitivity and specificity results can help tailor the imaging options for patients that may not qualify for MRI. Ex: patients with metal or a pacemaker in their body. Also, if contrast dye or  radiation is contraindicated in patients, what other modalities are there with a good specificity or sensitivity for diagnosing osteomyelitis 
• Interesting to find out that although plain radiography only has a 70.4 percent sensitivity and 81.5 percent specificity, the protocol for the first step when suspecting osteomyelitis in all major facilities is to get plain radiography, and the if there are further clinical indications such as active signs of infection and positive probe to bone/deep soft tissue, then we opt to get a MRI scan next.