| Part I:Renal tumors:diffusion weighted imaging research at 3. OT Objective:To assess the value of diffusion weighted imaging in di fferentiating between benign from mal ignant renal tumors, differentiating among various pathologic subgroups of renal tumors, and various grade of clear cell carcinoma.Materials and methods:171 (110 men,61 women.) patients with 175 clinical suspected renal masses underwent 3. OT routine MR scan and diffusion weighted MR scan before operation. All patients were histopathologically diagnosed. The b value of DWI sequence was 800s/mm". Apparent diffusion coefficient values of both tumor and renal parenchyma were measured with an AW4.4 workstation and were compared by means of different characters, pathologic subgroups and various grade of clear cell carcinoma.Results:there were 30 benign and 145 malignant renal tumors. Benign tumors included 21 angiomyolipoma,5 oncocytoma and 4 other types, while malignant tumors included 110 clear cell RCC,12 papillary RCC,16 chromophobic RCC, and 7 other types. In the 110 clear cell carcinoma, there were 44 for gradeI,44 for grade II,16 for grade III, and 5 for grand IV,1 unclassified. The mean ADC value of benign tumors (1.29×10-3mm2/s)were lower than that of malignant tumors (1.56X 10-3mm2/s), with the area under the ROC curve 0.696. For the different pathologic subgroups of renal tumors, clear cell RCC showed the significant higher ADC value of 1.70×10-3mm2/s, oncocytoma showed the second higher ADC value of 1.16×10-3mm2/s, papillary RCC, chromophobic RCC, and angiomyolipoma got almost equaled ADC value. To differentiate clear cell RCC from other tumors, a cut value of 1.355×10-3mm2/s should be made (area under the curve were 0.854, and sensitivity were 80%, specificity were 78.5%). The analysis of mean ADC value showed an inverse linear correlation with different grade of clear cell RCC.Conclusion:diffusion weighted imaging is useful in differentiating between benign from malignant renal tumors, differentiating among various pathologic subgroups of renal tumors, and various grade of clear cell carcinoma. And the performance of diagnosis can be improved performed together with conventional MR.Part II:Timing of MR multi-phase contrast enhancement for normal kidney-Objective:To investigate the appropriate timing of MR multi-phase contrast enhancement for normal kidney.Materials and methods:30 patients with normal kidney function underwent MR multi-phase contrast enhancement. There are 20 men,10 women, the mean age was 52. MR imaging was performed with a 3.0T scanner by using fat suppressed breath-hold LAVA sequence. The mask images were obtained before contrast agent injection, and the post contrast acquisitions was first performed at 15s, then every 30s take once. Except for the first acquisitions got 2 phases of images during one breath hold, the rest acquisitions got only 1 phase for one breath hold. Each phase took 9-10s, and gained 20-24 slices, all 10 phases were performed including the mask images. A delayed phase was performed 4 min after injection. The signal intensity of aorta, cortex, and medulla of kidney of multi-phase was measured and recorded with an AW4.4 workstation, and then analyzed with SPSS 13.0 software.Results:the aorta got the earliest enhancement, and had obviously high signal intensity at the 2nd phase (15s), reached the peak at the 3rd phase (25s), and kept the peak value to the 4th phase (45s), then began to reduce.The cortex was slightly enhanced at the 2nd phase, and increased sharply during the 3rd phase, till the 4th phase reached the peak, and then began to reduce. The medulla got the latest enhancement and reached the peak at the 6th phase (105s), and kept the status till the 10th phase. The difference between the cortex and medulla were obvious at 2nd and 3rd phase, and began to reduce at 4th phase, then kept constant from 6th to the 10th phases. Then we established the 2nd phase to be the artery phase, the 3rd phase to be early corticomedullary phase, the 4th phase to be late corticomedullary phase, the 6the phase to be nephrographic phase.Conclusion:the appropriate timing of MR multi-phase contrast enhancement of kidney should the mask phase, artery phase (2nd phase), early corticomedullary phase (3rd phase), late corticomedullary phase (4th phase), nephrographic phase (6th phase), and a delayed phase.Partlll:Renal tumors:multi-phase contrast enhancement research at 3.0T Objective:To assess the value of multi-phase contrast enhancement in differentiating between benign from malignant renal tumors, differentiating among various pathologic subgroups of renal tumors, and various grade of clear cell carcinoma.Materials and methods:157(100 men,57 women) patients with 161 clinical suspected renal masses underwent 3.0T routine plain MR scan and multi-phase contrast enhancement MR scan before operation. All patients were histopathologically diagnosed. MR imaging was performed with a 3.0T scanner by using fat suppressed breath-hold LAVA sequence. The mask images were obtained before contrast agent injection, and the post contrast acquisitions was first performed at 15s, then every 30s take once. Except for the first acquisitions got 2 phases of images during one breath hold, the rest acquisitions got only 1 phase for one breath hold. Each phase took 9-10s, and gained 20-24 slices, all 6 phases were performed including the mask images, a delayed phase was performed 4 min after injection. The signal intensity of renal cortex and tumor of multi-phase was measured and recorded with an AW4.4 workstation, and then signal intensity enhancement percentage, cortex-tumor enhancement ratio, peak enhancement percentage, peak phase, flow-out rate, and shape of enhancement curve were calculated and analyzed with SPSS 13.0 software.Results:there were 28 benign and 133 malignant renal tumors. Benign tumors included 20 angiomyolipomas,4 oncocytomas and 4 other types of benign tumors, while malignant tumors included 100 clear cell RCC,10 papillary RCC,13 chromophobic RCC, and 5 other types of malignant tumors. In the 110 clear cell carcinoma, there were 44 for grade I,42 for grade II,14 for grade III, and 5 for grand IV. The signal intensity enhancement percentage and cortex-tumor enhancement ratio of benign tumors were lower than that of malignant tumors, but these difference did not show any statistical significance. For the different pathologic subgroups of renal tumors, clear cell RCC showed the significant higher signal intensity enhancement percentage and cortex-tumor enhancement ratio; oncocytoma, angiomyolipoma and chromophobic RCC showed a similary lower enhancement degree, and got in the moderate enhancement group; papillary RCC, other types of benign tumors, and other types of malignant tumors showed the lowest enhancement degree. This grouping trend was most obvious at the 3rd phase (early corticomedullary phase). Clear cell RCC, oncocytoma, angiomyolipoma and chromophobic RCC showed a wash-out feature of enhancement curve, and the other types of renal tumors showed a gradually filling feature. The enhancement degree and form of different cell grade of clear cell RCC showed no statistical significance.Conclusion:Multi-phase contrast enhancement is of no use in differentiating between benign from malignant renal tumors, differentiating among various grade of clear cell carcinoma. But different pathologic subgroups of renal tumors did show different enhancement features. By using multi-phase contrast enhancement renal tumors can be classified into groups, and together with other sequence, the performance of diagnosis can be when improved. |
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