Study Of The Application Of Whole Body Diffusion Weighted Magnetic Resonance Imaging In The Diagnosis Of Oncology

Objective:To discuss the diagnostic and differential diagnostic value of MR whole body diffusion weighted imaging(DWI)in tumors and metastases,and to compare the detection rate of whole body DWI and single photon emission computed tomography(SPECT)in detecting spinal metastases.Methods:Six healthy volunteers were randomly selected, whole body magnetic resonance DWI scans were performed to analyze the signal characteristics of normal body DWI. Twenty three patients who have suspected malignant lesions were selected to have the whole body magnetic resonance DWI scan and then the DWI signal characteristics of the body were analyzed. The lesions were confirmed with clinical routine enhanced CT, MRI scans and pathology. Add / Sub software to superimpose the original axial images, with segment and the seamless connection between paragraphs and 3 dimension maximum intensity projection (3D-MIP) reconstruction and black-white flip technology were used. Image analysis was done on the ADW4.4 diagnostic workstation,using Functool software to make the original axial images into DWI maps. Two experienced radiologist analyzed all the images. For the five 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:⑴Six healthy volunteers showed that WB-DWI had low to moderate signal in skeletal system; lungs, mediastinum,and liver showed low signal; brain, spinal fluid, joint cavity fluid, kidneys, superficial lymph nodes and uterus , prostate, seminal vesicles, penis, testis showed high signal, while the gall bladder, spleen, intestines and bladder larger showed different signals in different individuals.⑵Comparing the positive detection rates of lesions in different organs on WBDWI, we can find that the rates are not at equal pace. The sensitivity and specificity of non-osteoblastic bone metastases are the highest .In this group of cases,there were total of fifty-three non-osteoblastic bone metastases. WBDWI selected fifty-one lesions, with the sensitivity up to 96%. Out of five non-lesion cases,WBDWI recorded one false positive,thus,the specificity is 80%. Sensitivity and specificity for skull and liver were respectively 90%, 78% and 93%, 75%. The sensitivity of osteoblastic metastases on WBDWI is the least. In this group of cases,there was one patient with lung cancer, and his manifestations is osteoblastic metastases on spinal bone.⑶The lymph node metastasis of the neck, armpits and groin lesions were found most easily, followed by retroperitoneal and pelvic lymph nodes. The small lymph nodes in the mediastinal and the hilar lymph nodes which were around the blood vessels were hardest to find, because of flow of blood in blood vessels and respiratory motion artifact interference. Pelvic lymph node detection rate was relatively low, mainly because of some high signals of the organs in the pelvic cavity.⑷In the five patients who accepted whole body DWI and SPECT examinations simultaneously, there are forty-three lesions confirmed by CT,MRI and pathological study. After performing WBDWI and SPECT,following defection rates were seen:①WBDWI detected thirty-nine lesions out of forty-three with the detection rate of 90.69% ( 39/43);②SPECT detected only thirty-three lesions out of forty-three, thus, with the detection rate of 76.74% (33/43).We can find that the two methods have significant differences (P <0.01).⑸The possible signs of malignanc lymph nodes on WBDWI:①enlarged lymph nodes showed higher signal than the spleen signal;②asymmetric enlargement of superficial lymph nodes;③the long and short diameter ratio of lymph nodes <2; ④When the cancer patients had WBDWI review, the existing malignant lymph nodes increased in size and some new malignant nodes were also detected.Conclusion:1,WB-DWI had low signal in skeletal system,lungs, mediastinum,and liver ; brain, spinal fluid, joint cavity fluid, kidneys, superficial lymph nodes and uterus , prostate, seminal vesicles, spleen,penis, testis showed high signal.2,The sensitivity and specificity of tumors and metastases on WBDWI are high, but the rates are different in different organs.3,The positive detection rate of WBDWI is higher than that of SPECT in detecting spinal metastases. Therefore, WBDWI is expected to be the first choice to detect bone metastases in patients with malignant tumors.