Diagnostic value of whole body diffusion weighted imaging for screening primary tumors of patients with metastases / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the values of whole body diffusion weighted imaging (DWI) in screening primary unknown tumor in patients with metastases.</p><p><b>METHODS</b>Totally, 34 patients with metastases of primary unknown tumors were scanned with whole body DWI, and conventional magnetic resonance (MR) imaging was performed if suspected lesions were detected. All the metastases including 27 cases of osseous metastases, 2 brain metastases, 2 liver metastases, 1 pulmonary multiple metastasis, 1 neck metastasis and 1 malignant ascites, were diagnosed by computed tomography, single photon emission computed tomography, or MR imaging. For the proven primary tumors diagnosed by biopsy or pathology of surgical specimens, apparent diffusion coefficient (ADC) values of the primary and metastatic lesions were measured respectively. The sensitivity and specificity of this technique for screening primary tumors were evaluated.</p><p><b>RESULTS</b>We found 24 cases with suspected primary lesions, in which 23 lesions were proved to be primary tumors, and 1 was proved to be benign lesion. And no definite primary lesion was found in 10 cases on whole body DWI, but in which 1 case was diagnosed with primary tumor by biopsy later, and the other 9 cases remained unknown within follow-up of over half a year. The difference was not significant in ADC values between primary and metastatic lesions (P>0.05). The sensitivity and specificity of whole body DWI for searching primary tumors was 95.8% and 90.0%, respectively.</p><p><b>CONCLUSION</b>Combined with conventional MR scanning, whole body DWI can help to search primary lesions of patients with metastases.</p>

Optic radiation in normal adults: a study using magnetic resonance diffusion tensor imaging and diffusion tensor tractography / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the fractional anisotropy (FA) and the architecture of the optic radiation fiber tracts of normal adults with magnetic resonance (MR) diffusion tensor imaging (DTI).</p><p><b>METHODS</b>Diffusion tensor images were obtained from 30 healthy volunteers without any cerebral abnormalities on conventional MRI. FA and the mean diffusivity (MD) of the optic radiation were measured in the directional encoded color (DEC) maps. The architecture of the optic radiation fiber tracts were displayed with the software of diffusion tensor fiber tracking.</p><p><b>RESULTS</b>In all subjects, the optic radiation could be readily identified in the DEC maps. The FA value was 0.509-/+0.029 in the left and 0.502-/+0.026 in the right, with the MD value of (0.763-/+0.050) x10(-3) and 0.748-/+0.052)x10(-3) mm2/s, respectively. No significant differences were found in the FA or MD value of the bilateral optic radiation (P>0.05). Diffusion tensor tractography (DTT) demonstrated that the 3 bundles of the optic radiation fibers were located in the lateral sagittal stratum, passing from the lateral geniculate body of the thalamus to the primary visual cortex. The dorsal and lateral bundles passed posteriorly to the superior bank of the calcarine cortex, while the ventral bundle passed anteriorly before making a sharp turn, known as the Meyer loop, and subsequently coursed posteriorly to terminate in the inferior margin of the calcarine cortex, which was consistent with the results of classic anatomical studies.</p><p><b>CONCLUSION</b>As a novel method to study the relationship between visual function and optic pathway, DTI and DTT can show the FA and architecture of the optic radiation.</p>

The predictive value of MR diffusion weighted imaging on the delayed encephalopathy after carbon monoxide poisoning / 中华放射学杂志

Objective To investigate the value of diffusion weighted imaging(DWI)in predicting delayed encephalopathy of the rabbits brain after carbon monoxide(CO)poisoning.Methods Sixty healthy rabbits were put into self-made poisoning cabinet and were poisoned by inhalation of CO.Aeration of CO was stopped when the rabbits became comatous,and the cabinet was kept airpoof for 6 h.The rabbits underwent MRI before poisoning,at 1 h,3 d,5 d,7 d,15 d,30 d,45 d,and 60 d after poisoning respectively. Axial and sagittal T_2WI,axial T_1WI and DWI were performed.In the rabbits that did not show symptoms of delayed encephalopathy,the observation was discontinued on the 60~(th)day.In the rabbit that showed the symptoms,the observation was discontinued on the 30~(th)——45~(th)day.The changing pattern of cortical ADC values before and after CO poisoning was observed and its relationship with delayed encephalopathy was investigated.Results In the group without delayed encephalopathy(15 rabbits),the ADC value at 1 h after poisoning[(7.58?0.36)?10~(-4)mm~2/s]decreased significantly compared with the pre-poisoning value[(8.02?0.35)?10~(-4)mm~2/s](q=0.4441,P0.05).In the group with delayed encephalopathy(15 rabbits),the ADC value at 1 h after poisoning [(7.40?0.32)?10~(-4)mm~2/s]decreased significantly compared with the pre-poisoning value[(8.08? 0.32)?10~(-4)mm~2/s](q=0.6728,P