Although bone scintigraphy has traditionally been accepted as the diagnostic modality of choice to assess bone metastasis, it has the disadvantage of missing early bone marrow metastasis due to absence or minimal reactive bone formation. For example in one recent study, 20% of patients with NSCLC had absolutely normal Tc-99m bone scintigraphy while PET/CT showed involvement. In addition, lytic lesions are not detected by bone scintigraphy due to the absence of osteoblastic reaction in some solid tumors . Attempts to overcome this problem have resulted in the utilization of bone marrow scintigraphy in addition to bone scanning has not also been gained popularity because of relatively high false positive  and false negative  results. CT has also a similar drawback with bone scintigraphy in delineating bone marrow metastases because of the absence of reactive bone formation or cortical destruction in lesions confined to bone marrow. MRI has recently been regarded as a very sensitive modality in detecting BM metastasis compared to bone scintigraphy due to fact that it has the ability to show malignant deposits directly before reactive changes have occurred . Daldrup-Link et al demonstrated that whole-body MRI, FDG PET and skeletal scintigraphy has a sensitivity of 82%, 90% and 71%, respectively in detecting skeletal metastases . On the other hand, MRI has been considered to be not specific enough in delineating bone marrow metastases due to some benign entities such as hemangiomas, inflammatory processes, and post-therapy changes and also impractical for various reasons such as absence of widespread availability or claustrophobia of the patients [16, 17]. The superiority of FDG-PET/CT lies in the fact that it has the ability to evaluate not only the entire skeleton but also the other organs in a single examination. Many studies have confirmed that FDG-PET/CT has comparable sensitivities in the ability of detecting bone marrow metastases in solid tumors [18, 19]. It has also shown efficacy for the detection of BM metastases from lung and breast carcinoma [20, 21]. The diagnostic accuracy, sensitivity and specificity of FDG-PET in detecting bone marrow metastasis in lung cancer were 94%, 91% and 96%, respectively, compared to bone scintigraphy in one study . FDG-PET is also superior to other modalities in identifying unsuspected disease involving the bone at an earlier stage when only the bone marrow has been involved before bone remodeling has occurred. This might pose many clinical implications. Some solid tumors such as prostate and breast have predilection to metastasize to bone relatively early to their course of disease. Early detection of bone and BM metastasis may change the treatment plan dramatically both for bone directed therapies such as zoledronic acid or denosumab and radiotherapy and for systemic therapies. For example, detecting bone and BM metastasis in otherwise early stage hormone positive breast cancer may obviate the need for combination chemotherapy or establishing osteoclast inhibiting (zoledronic acid, ibandronic acid) or RANK ligand inhibiting (donesumab) therapies earlier than overt metastases. Instead, we can put the patient on hormonotherapy which is far less toxic than chemotherapy. In our patients, after ordering PET/CT for other reasons bone and bone marrow metastases were detected unexpectedly, despite normal complete blood count indices in 5 patients (patient 4, 7, 8, 9, and 10). This prompted us to modify the management plan as follows: In patient 4, 7 and 10, finding of bone marrow metastasis led to a decrease in the initial chemotherapy doses to avoid severe bone marrow toxicity. In patient 8 and 9, detecting bone and bone marrow metastasis obviated the need of local therapy. Instead, we planned bisphosphonate and tailored chemotherapy for this patient.