Evaluation of bone metastases by whole-body MRI using a panoramic table and comparison of the findings with bone scintigraphy

Identification and prevalence of metastases in patients with malignancy is great importance in staging the tumor, determining the treatment protocol, treating the symptoms and improving the quality of life. Direct radiography, computed tomography (CT), bone scintigraphy (SG), bone marrow scintigraphy, positron emission tomography (PET), and magnetic resonance imaging (MRI) are the imaging modalities used for the purpose of detecting metastases, especially bone metastases. In the first four methods, the patient is exposed to excessive radiation.In order to detect bone metastases in direct X-ray, there should be more than 50% loss in bone mineral content. The screening of the whole body in CT is not performed due to the radiation received by the patient, the time of examination is long and the cost is high.Bone scintigraphy using Tc-99m-diphosphonate analogues is more sensitive than the first two techniques, but has low specificity, low anatomical detail, low spatial and contrast resolution. The origin of most lesions, including vertebral column, cannot be determined by scintigraphy. Radionuclide accumulation can also be seen in benign pathologies, it is difficult to distinguish these conditions from metastases.Whole-body MRI using STIR sequence is a imaging method with high sensitivity and specificity in the detection of metastases. In whole-body MRI, metastases to other organs can be detected in lymphadenopathies and primary tumors superior to scintigraphy. In this study, the presence of primary tumor or metastasis, regardless of the age of the tumor or the age of the patient, was determined by histological examination or imaging methods and 34 patients underwent whole-body MRI procedure between March 2001 and January 2002. Ten patients' full body MRI findings could not be included in the study because other radiological imaging methods were not confirmed by clinical and radiological follow-up. Whole body MRI findings were compared with scintigraphy findings in 18 of the remaining 24 patients. The presence or absence of metastases was determined in the light of CT, ultrasonography, regional MRI examinations and with clinical-radiological and pathological follow-up. The study was performed with 1.5 Tesla MRI device (Quantum Symphony; Siemens, Erlangen) with panoramic table feature. Investigations were performed using the turbo STIR sequence (TR / TE = 7040/74 ms; TI = 150 ms, TA = 5 minutes 46 seconds) in the coronal plane. Head-neck, phase-arrayed body, phase-aligned vertebrae and phase-aligned peripheral angio coils were used during the investigation. Matrix 241x512, section number 20, section thickness 6 mm and FOV 500 mm. The total examination period lasted 40-60 minutes. All patients were well tolerated. In the light of CT, ultrasonography and regional MRI examinations, metastasis was detected in 41 regions from 144 regions examined by clinical-radiological and pathological follow-up. Metastasis was detected in 35 of 144 regions examined in 18 patients in the whole body MRI (sensitivity 85%, specificity 99%, accuracy 95%, positive predictive value 97%, negative predictive value 94%). In the scintigraphy, metastasis was detected in 21 of the 144 regions examined in 18 patients (sensitivity 50%, specificity 87%, accuracy 76%, positive predictive value 61%, negative predictive value 80%). In 6 patients without scintigraphy, metastasis was detected in 6 regions and the presence of these metastases was confirmed by other imaging methods. In the light of this study, it was concluded that the whole body MRI performed using STIR sequence is a reliable imaging method which can be applied in a short time to determine the skeletal metastases.