patient_bedFoot pain, an ailment that orthopedic surgeons encounter in their daily practice, can be a clinical symptom of many different issues, from stress fractures to tumors. While a number of imaging modalities can help in diagnosing specific types of foot pain, no one modality is useful for effectively diagnosing a wide range of causes.

However, researchers recently found that one particular scan, combining two modalities, could diagnose the cause of unclear foot pain better and with less radiation exposure to the patient than other methods. According to a study in the March 2015 issue of The Journal of Nuclear Medicine, PET/MR offers more diagnostic information with higher diagnostic certainty than PET/CT.

The article, “Evaluation of 18F-Fluoride PET/MR and PET/CT in Patients with Foot Pain of Unclear Cause,” compared the quality and diagnostic performance of 18F-fluoride PET/MR to those of 18F-fluoride PET/CT in 22 patients presenting with foot pain with an inconclusive diagnosis after clinical examination and radiography. Results showed that PET/MR was significantly superior to PET/CT in terms of overall image quality. PET/MR had an image quality score of 3.0 out of 3 possible points, while PET/CT achieved 2.3 out of 3.

Study authors described how imaging with 18F-fluoride PET is a highly sensitive tool, yet it has low specificity for detection of metabolically active benign bone disease. On the other hand, MR imaging provides excellent soft-tissue contrast and high resolution, which helps in specifying a diagnosis. Therefore, when combined, PET/MR can provide an important tool for the sensitive diagnosis of foot pathologies, according to researchers.

Additionally, because MR does not use radiation, as well as allows for a longer PET acquisition time, the patient’s exposure is lower than with CT.

“Besides information on bone metabolism, [PET/MR] provides additional diagnostic relevant findings from soft-tissue and bone marrow pathology, for example, bone marrow edema, ganglion cysts or tenosynovitis, compared to PET/CT,” said Isabel Rauscher, corresponding author of the study.

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