WHOLE BODY MRI VERSUS 99M TC-METHYLENE DIPHOSPHONATE SCINTIGRAPHY IN DETECTION OF SKELETAL METASTASES RASLAN, O. MD(1)., OMAR, W. MD(2)., EL BADAWI, M. MD(1). and SHAFIK, M. MD(3). (1) Radiology Department National Cancer Institute, Egypt, (2) Nuclear Medicine Department National Cancer Institute, Egypt and (3) Radiology Department Cairo University, Egypt.

Background: Skeletal metastases have a drastic impact on the staging, treatment and quality of life of cancer patients; Being the most common malignant bone tumor, affecting at least two thirds of the cancer patients
The aim of this study is to compare ability of whole body MRI, with routine 99mTc-phosphonate scintigraphy to detect skeletal metastases in cancer patients.
Patients and methods: 23 patients with pathologically proven primary malignant tumors were examined in the Radiology Department, National Cancer Institute, Cairo University. The patients were subjected to both Whole-Body MRI (WB-MRI) and 99m Methylene Diphosphonate bone scintigraphy (BS).
WB-MRI was mainly obtained using 4 contiguous coronal stations for body coverage using the body coil, and 2 contiguous sagittal stations for the spine with the CTL Coil, using both Fast Spin Echo Inversion Recovery (FSE-IR) and T1-Weighted Fast Spine Echo (T1w-FSE) sequences for each station, in a total acquision time of ~28 min, and In-Out time of ~40 min. Bone Scan (BS) imaging was completed in 20 min after 2 hours of tracer administration using dual headed gamma camera with low energy general purpose collimator (LEGP).
Results: 15 out of 23 cases had skeletal metastases, while 8 cases were free from metastases. Comparison between the results obtained by each modality was done.
An excellent overview of the skeletal system was obtained in all cases and the results showed that WB-MRI had higher overall sensitivity, specificity, positive predictive value, negative predictive value, accuracy than bone scan, as it could detect all of the 15 metastatic cases, while bone scan characterized only 11 cases.
Although BS showed higher lesion detection in the ribs and the shoulders, but WB-MRI was superior in the spine, pelvis and extremities, and both were equal in the skull. In addition WB-MRI can also detect the extra-skeletal tumor complications (e.g. lung metastases), which gives the clinician an idea about the total tumor burden, aiding in earlier staging and treatment of the patients.
Conclusion: WB-MRI is powerful and effective tool that showed higher sensitivity, specificity and accuracy than BS in various types of primary tumors and in various situations including solitary metastatic focus, diffuse extensive metastases and skeletal metastases from a second primary. Although WB-MRI showed better results, but we believe that BS would remain the standard procedure for evaluation of bone metastases for quite sometime due to its easiness, simplicity, much lower cost and better tolerance by patients.