The Study And Application Of Spinal Malignancy Using MR Whole Body Diffusion Weighted Imaging

Objective: To discuss the diagnostic and differential diagnostic value of MR whole body diffusion weighted imaging (DWI) in spinal metastases and multiple myeloma, and compare the detection rate of whole body DWI and single photon emission computed tomography (SPECT) in detecting spinal metastases.Methods: 20 healthy volunteers were selected randomly and scanned with whole body DWI. The signal features of normal spine on whole body DWI were analyzed. 96 patients who were suspected spinal malignancies in clinic and had accepted CT, MRI or SPECT were collected and scanned with whole body DWI. Combined with pathology and clinical information, we brought 60 cases of definite spinal metastases and 16 cases of multiple myeloma into our study, and analyzed the signal features of the spinal lesions. Apparent diffusion coefficient (ADC) values of vertebral bodies of volunteers, spinal lesions and adjacent normal vertebral bodies of both metastases and multiple myeloma patients were measured on Functool software, respectively. The differences of ADCs between spinal lesions and normal vertebral bodies, spinal metastases and multiple myeloma were analyzed to find whether they were statistically significant or not. For the 20 patients of spinal metastases who accepted whole body DWI and SPECT examinations simultaneously, the numbers of lesions detected on both methods were calculated, respectively, and the positive detection rates were compared.Results:①On whole body DWI, the vertebral bodies of volunteers appeared low signal or homogeneously and slightly high signal, and the spinal lesions of metastases and multiple myeloma appeared significantly high signal intensity. On ADC maps, the signal intensities of both spinal lesions were higher than normal vertebral bodies.②The average ADC value of vertebral bodies of volunteers was (0.524±0.034)×10-3 mm2/s, and the differences of ADCs between thoracic and lumbar spines, male and female spines were not statistically significant (P>0.05).③The average ADC value of spinal metastases was (1.008±0.127)×10-3 mm2/s, which was markedly higher than that of adjacent normal vertebral bodies (0.569×10-3 mm2/s), and the difference between them was statistically significant (P<0.01). The average ADC value of multiple myeloma was (1.008±0.127)×10-3 mm2/s, which was markedly higher than that of adjacent normal vertebral bodies (0.534×10-3 mm2/s), and the difference between them was statistically significant (P<0.01).④The average ADC value of spinal metastases was higher than that of multiple myeloma, and the difference between them was statistically significant (P<0.01).⑤For the 20 patients of spinal metastases who accepted whole body DWI and SPECT examinations simultaneously, 90 lesions total were identified by multiple imaging methods and clinical information. Whole body DWI detected 87 lesions in 19 cases, whose detection rate was 96.67% (87/90); while SPECT detected 74 lesions in 17 cases, whose detection rate was 82.22% (74/90). By statistical analysis with -test, the difference between them was statistically significant (P<0.01).Conclusions: The sensitivity of whole body DWI in detecting spinal malignancies is high. Spinal metastases and multiple myeloma can be differentiated by quantitative analysis with ADC value, which helps to qualitative diagnosis of both lesions. The positive detection rate of whole body DWI is higher than that of SPECT in detecting spinal metastases.