¹⁸F-NaF PET–CT Could Displace ⁹⁹mTc-MDP as Bone Imaging Radiopharmaceutical of Choice

By Leah Lawrence - Last Updated: November 15, 2022

Screening for bone metastases with 18F-sodium fluoride PET–CT (¹⁸F-NaF PET–CT) was more sensitive and accurate than 99mTc bone scintigraphy with SPECT (⁹⁹mTc-MDP SPECT) among patients with high-risk breast or prostate cancer, according to the results of the MITNEC-A1 study published in Lancet Oncology.

Based on these results, researchers wrote that ¹⁸F-NaF “has the potential to displace ⁹⁹mTc-MDP as the bone imaging radiopharmaceutical of choice” in these patient populations.

Currently, planar bone scintigraphy with ⁹⁹mTc-MDP with or without SPECT is the standard imaging modality used for detection of bone metastases.

“Recent technological improvements in PET–CT and recurrent issues with ⁹⁹mTc supply have sparked renewed interest in ¹⁸F-NaF PET–CT to detect bone metastasis,” the researchers wrote.

This multicenter, phase-3 trial enrolled 288 patients (64 with breast and 224 with prostate cancer) from 10 hospitals in Canada. Patients were aged 18 or older and diagnosed with breast or prostate cancer with a WHO performance status of 0-2 and high risk or clinical suspicion for bone metastasis.

Both imaging modalities were performed within 2 weeks of each other for each participant. Two independent reviewers interpreted each. In all, 261 participants underwent both modalities and completed required follow-up.

A little less than half (42%) of patients had bone metastases. ¹⁸F-NaF PET–CT was more accurate than ⁹⁹mTc-MDP SPECT (84.33% vs. 77.4%; P=.016). ¹⁸F-NaF PET–CT was more sensitive and had better negative predictive value than ⁹⁹mTc-MDP SPECT, and was equal on specificity and positive predictive value.

Consensus between the reviewers was reached for 89% of the ¹⁸F-NaF PET–CT images and 92% of the ⁹⁹mTc-MDP SPECT images. ¹⁸F-NaF PET–CT was found to have “good” interobserver agreement and ⁹⁹mTc-MDP SPECT found to have “excellent” interobserver agreement.

Additionally, ¹⁸F-NaF PET–CT detected a greater number of metastases in a lesion-based analysis than conventional bone scintigraphy with SPECT.

The researchers noted that “new radiopharmaceuticals targeting prostate-specific membrane antigen (PSMA) were not evaluated in this study and are attractive alternatives to ¹⁸F-NaF PET–CT imaging to detect bone metastases.”

“Considering all the advantages and the ability to detect bone metastasis with higher sensitivity and accuracy, ¹⁸F-NaF has the potential to displace ⁹⁹mTc-MDP as the bone imaging radiopharmaceutical of choice,” the researchers wrote, adding, “this conclusion might have been influenced by the higher than expected prevalence of patients with osseous metastases in the patient population we studied.



Intra-Individual Comparison of 18F-Sodium Fluoride PET–CT and 99mtc Bone Scintigraphy With SPECT in Patients With Prostate Cancer or Breast Cancer at High Risk For Skeletal Metastases (MITNEC-A1): A Multicentre, Phase 3 Trial