Dynamic Bone Imaging with^99mTc-Labeled Diphosphonates and¹⁸F-NaF: Mechanisms and Applications

Abstract

Learning Objectives: On successful completion of this activity, participants should be able to (1) appreciate the physiologic mechanisms underlying uptake of bone-seeking radiopharmaceuticals used to assess bone perfusion and turnover and note the differences between 18 F-NaF and 99m Tc-labeled diphosphonates; (2) discuss the use of bone scintigraphy for evaluation of bone viability and metabolic bone disorders and appreciate the potential role of quantitative dynamic 18 F-NaF PET for evaluation of response to therapy; and (3) discuss indications for 99m Tc-labeled diphosphonate bone scans and 18 F-NaF PET/CT for oncologic staging and appreciate quantitative methods on static and dynamic bone imaging as imaging biomarkers of treatment response using novel systemic therapies for metastatic castrate-resistant prostate cancer as a model.Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, participants can access this activity through the SNMMI Web site (http:// www.snmmi.org/ce_online) through April 2016.Dynamic bone scanning with 99m Tc-labeled diphosphonates and 18 F-labeled sodium fluoride provides functional information sensitive for subtle changes in bone turnover and perfusion, which assists the clinical management of numerous osseous pathologies. This article reviews the mechanisms of uptake of 99m Tc-labeled diphosphonates and 18 F-sodium fluoride and discusses and compares the performance of these bone-seeking radiotracers for clinical and research applications, using dynamic and multiple-time-point imaging protocols and quantitative techniques.

Factors Affecting Uptake of NaF-18 by the Normal Skeleton

“…Renal fluoride clearance is related to the GFR, and NaF-18 PET/CT was used to assess renal function in rats [21]. Fluoride ions are freely filtered in the glomeruli but they also undergo tubular reabsorption [22]. Tubular reabsorption of fluoride increases with decreasing GFR [22].…”

“…Fluoride ions are freely filtered in the glomeruli but they also undergo tubular reabsorption [22]. Tubular reabsorption of fluoride increases with decreasing GFR [22]. Therefore, a negative relationship is expected between fluoride ions (SUV) and creatinine.…”

Normal SUV Values Measured from NaF18- PET/CT Bone Scan Studies

“…It typically occupies the interior region of bones, is highly vascular and frequently contains bone marrow [9]. Cancellous bone forms only 20% of the bone mass but accounts for 80% of the bone turnover associated with remodeling [10]. Thus, cancellous bone can have more SUV uptake than cortical bone.…”

Dosimetric evaluation of 153Sm-EDTMP, 177Lu-EDTMP and 166Ho-EDTMP for systemic radiation therapy: Influence of type and energy of radiation and half-life of radionuclides

“…Bone is a composite material of inorganic crystals bound to protein. The mineral phase, built of crystals containing mainly calcium and phosphate, is called hydroxyapatite (Wong and Piert, 2013). Bone-seeking radiopharmaceuticals accumulate in the skeletal tissue as it undergoes adsorption on the surface of the newly formed hydroxyapatite crystals (Orsini et al, 2013).…”