Send Orders of Reprints at reprints@benthamscience.net Current Radiopharmaceuticals, 2013, 6, 41-47 41 Bone Metastases Radiopharmaceuticals: An Overview Vincenzo Cuccurullo 1 , Giuseppe Lucio Cascini 2 , Oscar Tamburrini 2 , Antonio Rotondo 1 and Luigi Mansi 1,* 1 Department of Radiological Sciences - Second University of Naples, Naples, Italy 2 Department of Radiological Sciences - University of Catanzaro, Catanzaro, Italy Abstract: The skeleton is one of the preferential sites for metastases of solid tumors, and metastatic disease is the most common malignancy of the bone. Diagnosis and evaluation of skeletal metastases require more frequently a combined ap- proach of different diagnostic methods. Between the currently available imaging modalities, a major role is devoted to two radionuclide functional techniques namely scintigraphy and positron emission tomography (PET) imaging. Both these techniques require the use of different radiopharmaceuticals. The aim of this paper is to review the most important radio- compounds that can be successfully used to detect and/or characterize bone metastases. Keywords: Bone metastases, Bone scintigraphy, Tc-99m diphosphonates, F-18 fluoride, F-18 Fluoro-deoxyglucose, Onco- tropic radio-agents. INTRODUCTION The skeleton is one of the preferential sites for metastases of solid tumors, being surpassed only by the lungs and liver for incidence of metastatic disease; furthermore secondary neoplasms are the most common malignancy of the bone [1]. In general, skeletal metastases occur during the late stages of cancer progression via a multi-step sequence of molecular events [2]. The effects of bone metastases include pain, pathological fractures, hypercalcemia, myelosuppression, spinal cord compression and nerve root lesions. Generally the pain may more frequently result from the increment in size of neoplastic mass and/or from the destruc- tion of skeletal tissue caused by osteoclasts [3]. Presentation of patients with bone metastases takes many forms, includ- ing detection in routine staging studies, as bone scan. They typically become clinically evident as a result of pain and dysfunction [4]. For these reasons, diagnosis and evaluation of bone me- tastases require more frequently a combined approach of different methods, including both radionuclide and radio- logical techniques as X-rays, computed tomography (CT) and magnetic resonance imaging (MRI) [5]. Diagnosis of bone metastases by imaging modalities is based on either direct visualization of cancer spread or on detection of the reaction of normal bone to the malignant process [6]. The sensitivity of traditional Radiology to detect metastatic le- sions is low. Studies have shown that more than 50% to 70% of bone must be destroyed to be reliably detected by plain radiographs [7]. Computed tomography (CT) is mainly useful as an ad- junct to other imaging modalities in the loco-regional deep- ening of suspicious metastases. Conversely whole body CT scan is negatively affected by the high radiation dose admin- * Address correspondence to this author at the Medicina Nucleare, Seconda Università di Napoli, P.zza Miraglia, 2-80138 Napoli, Italy; E-mail: luigi.mansi@unina2.it istered to the patient, being therefore not indicated as a stan- dard procedure. A great revolution has been introduced by the availability of hybrid machines comprising together a CT with a PET or SPECT (single photon emission computed tomography) scanner, allowing the simultaneous acquisition of the two studies with the patient on the same bed [8]. In this way, the contribution of CT, generally performed at low dose, becomes very relevant in significantly improving the diagnostic accuracy of PET and SPECT, through a consider- able increase in specificity. The other technique magnetic resonance (MR) imaging is most often used to evaluate metastatic disease of the spine where, for some neoplasm, it has been proven superior to CT imaging, also having almost completely replaced myelogra- phy. MRI analyzes skeletal content more than bone per se. Starting the onset of neoplastic involvement from bone mar- row, MRI is able to reach a very high sensitivity in detecting skeletal lesions owing of its capability to visualize bone mar- row’s invasion [9]. A further improvement in the diagnosis of skeletal metas- tases may be obtained utilizing functional advanced methods with these more performing MR scanners. This approach has also been demonstrated in animal studies [10]. Furthermore, a very fascinating perspective has been recently opened by the availability of the hybrid PET-MRI scanners to be able compliment each other during the imaging process. The highest potential is reached when the MR’s information is related to that obtained by osteotropic radio-compounds, giving a complementary contribution because of their capa- bility to early detect an increased osteoblastic cortical activ- ity. In this scenario Nuclear Medicine, both alone and as primary component of hybrid machines, provides a signifi- cant contribution towards evaluation of skeletal metastases [11]. In this article we will analyze the most important pro- cedures to allow imaging of skeletal metastases. 1874-4729/13 $58.00+.00 © 2013 Bentham Science Publishers