Clinical Value of Whole-body Magnetic Resonance Diffusion Weighted Imaging on Detection of Malignant Metastases

Objective To evaluate the value of whole-body diffusion weighted imaging （WB-DWI） on detection of malignant metastasis. Methods Forty-six patients with malignant tumors underwent WB-DWI examinations between April 2007 and August 2007 in our hospital. Before WB-DWI examination, the primary cancers of all the patients were confirmed by pathology, and the TNM-stage was assessed with conventional magnetic resonance imaging （MRI） or computed tomography （CT）. WB-DWI was performed using short TI inversion recovery echo-planar imaging （STIR-EPI） sequence. Abnormal high signal intensities on WB-DWI were considered as metastases. The results of WB-DWI were compared with other imaging modalities. For the assessment of the diagnostic capability of WB-DWI, WB-DWI were compared with CT for demonstrating mediastinal lymph node metastases and lung metastases, and with conventional MRI for demonstrating metastases in other locations. Results WB-DWI demonstrated 143 focuses, 14 routine imaging. The number of bone metastases depicted of which were diagnosed to be benign lesions in on WB-DWI and routine imaging was 85 and 86; lymph node metastases was 17 and 18; liver metastases was 14 and 14; lung metastases was 4 and 8; and brain metastases was 6 and 8, respectively. WB-DWI failed to detect 12 metastatic lesions including 3 osteoplastic bone metastases, 4 lung metastases, 3 mediastinal lymph node metastases, and 2 brain metastases Four metastatic lesions including 2 deltopectoral lymph nodes and 2 rib metastases were detected with WB-DWI alone, all of which evolved greatly during clinical follow-up for more than 6 months. WB-DWI had higher detection rates for metastatic lesions in liver, bone, and lymph nodes than those in lung and brain （ X^2=30, P〈0.001）. Conclusions WB-DWI could detect most of metastatic lesions that were diagnosed with conventional MRI and CT. The limitations of WB-DWI might be had high false-positive rate and low efficiency in detecting mecliastinal lymph node, brain, and lung metastases.

Dynamic contrast-enhanced magnetic resonance perfusion weighted imaging in astrocytomas: correlation with histopathology and immunohistochemistry

Objective:To investigate magnetic resonance perfusion weighted imaging and its relationship with the grading and the expression of vascular endothelial growth factor (VEGF) and angiogenesis in astrocytomas. Methods: A collection of 34 patients with astrocytomas proved by surgery and pathology were examined by magnetic resonance imaging(MRI), with 26 cases of gradeⅠ-Ⅱ(low-grade) and 8 cases of grade Ⅲ-Ⅳ(high-grade). MR perfusion images were obtained with spin-echo echo planar imaging (SE-EPI) techniques. Expression of VEGF was examined by immunohistochemical method of streptavidin-biotin-peroxidase(SP). The vascular development was measured by micro-vascular density (MVD) which was immunostained with anti-factor Ⅷ-related antigen monoclonal antibody. Results: Both of the expression of VEGF and the angiogenesis in 34 cases of astrocytomas were significantly correlated to the maximum relative cerebral blood volume (Max rCBV) (r=0.604, P<0.001;r=0.625, P<0.001, respectively). The Max rCBV and the expression of VEGF, MVD in high-grade astrocytomas were significantly higher than that of in low-grade astrocytomas (t= 3.0, P=0.017; t=7.08, P=0.01;t=3.37,P=(0.011,) respectively). Conclusion: MR perfusion weighted imaging might be a valuable method in in vivo study of the angiogenesis of astrocytomas and evaluating their malignant degree and prognosis.

Magnetic resonance diffusion-weighted imaging in the diagnosis of diffuse liver diseases in rats

Background The diagnosis of diffuse hepatic lesions in early stage is a tough task at any time for clinical conventional imaging. Magnetic resonance diffusion-weighted imaging (MR DWI) can detect the changes of tissue structure at molecular level. This study was designed to determine the value of DWI in the diagnosis of diffuse liver lesions in early stage. Methods Diffuse liver lesions were induced by diethylnitrosamine in 42 rats of test group. Fourteen rats in control group were fed with pure water. Dynamic changes of MR DWI were observed every week in both groups during the early stage of diffuse liver lesions (1 to 12 weeks after drug administration in the test group). Apparent diffusion coefficient (ADC) values of liver parenchyma in different stages and pathologic changes were analyzed. Results The process of diffuse hepatic lesions in the test group was classified into three stages according to pathological changes, namely hepatitis, hepatic fibrosis and cirrhosis. No obvious morphological changes were shown by conventional imaging in both groups during this stage. But MR DWI demonstrated heterogeneous signal changes in early stage of hepatic cirrhosis in the test group. No significant change of ADC values was found in the control group between different weeks ( P >0.05). The ADC values of the test group declined from the fifth week, and after the tenth week the ADC values were significantly different between the test and control groups at gradient factor (b) value 300 sec/mm 2 ( P <0.05). At b value 600 and 1000 sec/mm 2, significant difference was seen between the two groups from the sixth week onward. The range of ADC value of the groups was (1.7-0.9)±(0.40-0.04) mm 2/sec (b=600) and (1.38-0.75)±(0.07-0.35) mm 2/sec (b=1000), respectively. Dominant pathological changes included swelled hepatocytes within 1 to 4 weeks after the administration of diethylnitrosamine in the test group, hyperplasia of fibrous tissues in 5-8 weeks and formation of cirrhotic nodules in 9-12 weeks. Conclusions MR functional DWI could detect diffuse liver lesions earlier than conventional morphological imaging. ADC value as a marker for early diagnosis of diffuse liver lesions could also be used to inspect changes of the lesions

Diffusion-weighted MRI in abdominal oncology:Clinical applications

Diffusion-weighted magnetic resonance imaging(DWI) provides image contrast that is different from that obtained by conventional magnetic resonance techniques.Although previously,DWI has been used to evaluate various diseases of the central nervous system,several technical advances have expanded the clinical applications of DWI beyond the central nervous system.As a result,many reports have been published on the use of DWI in abdominal diseases.Particularly,abdominal DWI has now being focused on evaluation of patients with abdominal cancer.DWI can be used for pretreatment tumor detection,characterization including predicting tumor response to therapy,monitoring tumor response during therapy,and follow-up study after treatment to detect possible tumor recurrence.

Role of MR-DWI and MR-PWI in the radiotherapy of implanted pulmonary VX-2 carcinoma in rabbits

Objective： To detect the activity of tumor cells and tumor blood flow before and after the radiotherapy of implanted pulmonary VX-2 carcinoma in rabbit models by using magnetic resonance diffusion-weighted imaging（MR-DWI） and magnetic resonance perfusion weighted imaging（MR-PWI）, and to evaluate the effectiveness and safety of the radiotherapy based on the changes in the MR-DWI and MR-PWI parameters at different treatment stages.Methods： A total of 56 rabbit models with implanted pulmonary VX-2 carcinoma were established, and then equally divided into treatment group and control group. MR-DWI and MR-PWI were separately performed using a Philips Acheiva 1.5T MRI machine（Philips, Netherland）. MRI image processing was performed using special perfusion software and the WORKSPACE advanced workstation for MRI. MRDWI was applied for the observation of tumor signals and the measurement of apparent diffusion coefficient（ADC） values; whereas MR-PWI was used for the measurement of wash in rate（WIR）, wash out rate（WOR）, and maximum enhancement rate（MER）. The radiation treatment was performed using Siemens PRIMUS linear accelerator. In the treatment group, the radiotherapy was performed 21 days later on a once weekly dosage of 1,000 c Gy to yield a total dosage of 5,000 c Gy.Results： The ADC parameters in the region of interest on DWI were as follows： on the treatment day for the implanted pulmonary VX-2 carcinoma, the t values at the center and the edge of the lesions were 1.352 and 1.461 in the treatment group and control group（P〉0.05）. During weeks 0-1 after treatment, the t values at the center and the edge of the lesions were 1.336 and 1.137（P〉0.05）. During weeks 1-2, the t values were 1.731 and 1.736（P〈0.05）. During weeks 2-3, the t values were 1.742 and 1.749（P〈0.05）. During weeks 3-4, the t values were 2.050 and 2.127（P〈0.05）. During weeks 4-5, the t values were 2.764 and 2.985（P〈0.05）. The ADC values in the treatment group were significantly higher than in the control group. After the radiotherapy（5,000 c Gy）, the tumors remarkably shrank, along with low signal on DWI, decreased signal on ADC map, and remarkably increased ADC values. As shown on PWI, on the treatment day for the implanted pulmonary VX-2 carcinoma, the t values of the WIR, WOR, and MER at the center of the lesions were 1.05, 1.31, and 1.33 in the treatment group and control group（P〉0.05）; in addition, the t values of the WIR, WOR, and MER at the edge of the lesions were 1.35, 1.07, and 1.51（P〉0.05）. During weeks 0-1 after treatment, the t values of the WIR, WOR, and MER at the center of the lesions were 1.821, 1.856, and 1.931（P〈0.05）; in addition, the t values of the WIR, WOR, and MER at the edge of the lesions were 1.799, 2.016, and 2.137（P〈0.05）. During weeks 1-1 after treatment, the t values of the WIR, WOR, and MER at the center of the lesions were 2.574, 2.156, and 2.059（P〈0.05） and the t values of the WIR, WOR, and MER at the edge of the lesions were 1.869, 2.058, and 2.057（P〈0.05）. During weeks 2-3 after treatment, the t values of the WIR, WOR, and MER at the center of the lesions were 2.461, 2.098, and 2.739（P〈0.05） and the t values of the WIR, WOR, and MER at the edge of the lesions were 2.951, 2.625, and 2.154（P〈0.05）. During weeks 3-4 after treatment, the t values of the WIR, WOR, and MER at the center of the lesions were 2.584, 2.107, and 2.869（P〈0.05） and the t values of the WIR, WOR, and MER at the edge of the lesions were 2.057, 2.637, and 2.951（P〈0.05）. During weeks 4-5 after treatment, the t values of the WIR, WOR, and MER at the center of the lesions were 2.894, 2.827, and 3.285（P〈0.05） and the t values of the WIR, WOR, andMER at the edge of the lesions were 3.45, 3.246, and 3.614（P〈0.05）. After the radiotherapy（500 c Gy）, the tumors shrank on the T1 WI, WIR, WOR, and MER; meanwhile, the PWI parameter gradually decreased and reached its minimum value.Conclusions： MR-DWI and MR-PWI can accurately and directly reflect the inactivation of tumor cells and the tumor hemodynamics in rabbit models with implanted pulmonary VX-2 carcinoma, and thus provide theoretical evidences for judging the clinical effectiveness of radiotherapy for the squamous cell carcinoma of the lung.

Perfusion MR imaging and proton MR spectroscopy in a case of dysembryroplastic neuroepithelial tumor

Dysembryoplastic neuroepithelial tumors ( DNTs ), which were first describedby Daumas-Duport in 1988, are one of rare benign tumors usually associated with medicallyintractable seizures which date from childhood. The clinical, pathologic and neuroradiologicfindings of DNT have been described. Recent advances in magnetic resonance imaging ( MRI) technologyallow the acquisition of cerebral microcirculation parameters by perfusion weighted imaging ( PWI)and brain metabolic indices by MR spectroscopy (MRS) . Several studies have shown the utility of PWIand MRS can improve the diagnostic accuracy of brain tumor, we combine the two techniques toevaluate a case with DNT and suggest that wider application of these techniques is warranted.