Clinical Research Of Dual-energy CT Diagnosis The Regional Lymph Nodes In Colorectal Cancer

Part ⅠIodine map and Spectrum curve in the diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancerObjective To explore the value of dual-source, dual-energy CT based spectral imaging technique and iodine mapping in the differential diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancer.Data and Methods 35 patients with pathologically confirmed as colorectal cancer underwent arterial and venous phase contrast-enhanced dual-energy CT scan. Then, the iodine contents of the primary lesions and regional lymph nodes were measured using "Liver VNC" software and dual-energy CT based spectral curve was also obtained for each case using MonoEnergetic software. The spectral curve and spectral curve slope were analyzed in "Mono Energetic" mode. Iodine contents and spectral curves in primary colorectal lesion, metastatic lymph nodes and reactive hyperplasia lymph nodes were compared.Results 35 colorectal cancer patients had 35 primary colorectal lesions and 105 regional lymph nodes including 56 metastastic lymph nodes and 49 inflammatory lymph nodes. The iodine contents of the primary colorectal lesions, the metastatic lymph nodes and the inflammatory lymph nodes were 1.67±0.82 mg/ml,1.55±0.99 mg/ml and 2.59±1.04 mg/ml in the arterial phase, and 2.39±0.38 mg/ml,3.70±1.31 mg/ml and 1.87±0.90 mg/ml in the venous phase, respectively. The spectral curve slope of the three lesions were 0.72±0.41,0.48±0.10,0.71±0.16 and 0.63±0.09, 0.88±0.20,0.61±0.05 in the arterial and venous pahses, respectively. The iodine content and the slope spectrum curve have statistical differences (p<0.000) in three kinds of lesions, however, there were no statistical differences (p>0.05) between the primary colorectal lesions and metastatic lymph nodes.Conclusion Dual-source, dual-energy CT can be helpful in the differential diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancer patients.Part ⅡIodine concentration and normalized iodine concentration in diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancerObjective To explore the value of iodine concentration and normalized iodine concentration in dual-energy CT in the differential diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancer.Data and Methods 35 patients had pathologically confirmed colorectal cancer underwent arterial and venous phase contrast-enhanced dual energy CT scan. Iodine concentration, normalized iodine concentration and enhanced CT value of the inflammatory and metastatic lymph nodes were measured in Liver VNC software And compared by using independent sample t-test. Sensitivity, specificity and receiver operating characteristic curve (ROC) was performed for diagnosing metastatic lymph nodes in colorectal cancer.Results 35 patients had 105 local lymph nodes, including 56 metastatic lymph nodes, 49 reactive hyperplasia lymph nodes. Contrast enhanced CT value of metastastic and of reactive hyperplasia lymph nodes in the arterial and venous phase were 32.67±11.99 HU,38.30±14.65 HU and 35.48±13.55 HU,37.08±15.57 HU, respectively. The responding iodine concentration were 1.58±0.81 mg/ml,3.17±1.07 mg/ml and 1.85±0.90 mg/ml,3.56±1.38 mg/ml; and normalized iodine concentration were 0.12±0.06,0.24±0.75 and 0.33±0.20,0.62±0.24; respectively. The arterial and venous phase iodine content and normalized iodine concentration and arterial phase enhanced CT value had statistical differences (p<0.000) in the two kinds of lymph nodes. There were no statistical differences (p>0.05) for the venous phase enhanced CT value. Normalized iodine concentration was the most valuable in the diagnosis of metastatic lymph nodes with sensitivity, specificity and AUC of 88.9%,73.2%,0.895 and 80.6%,82.1%,0.877.Conclusion Iodine concentration and normalized iodine concentration can be used in the differential diagnosis of the inflammatory and metastatic lymph nodes in colorectal cancer. The diagnostic value of the normalized iodine concentration was superior to enhanced CT value and iodine concentration to differentiate inflammatory from metastatic lymph nodes.Part ⅢComparison study on the accuracy of detecting colorectal cancer lymph nodes metastasis with arterial phase dual-energy CT spectral curve and the morphological findingsObjective To explore the accuracy of arterial phase dual-energy CT spectral curve and the morphological findings in detecting the metastatic lymph nodes in colorectal cancer.Data and Methods:35 patients with pathologically confirmed colorectal cancer had a total of 105 enlarged lymph nodes in the pelvic region underwent dual energy CT scan, We measured the size of the lymph nodes on CT images, and the CT value in non-enhanced and arterial phase CT scan; We also computed short-long diameter ratio and enhancement value of lymph node (lymph node CT value in arterial phase-CT value in plain scan). We observed the change trend of the spectrum curve and compared the diagnostic accuracy in detecting colorectal cancer lymph nodes metastasis.Results:In the 105 lymph nodes,56 lymph nodes were metastatic, while reactive hyperplasia was seen in 49 lymph nodes. Short-long diameter ratio and the enhancement CT value in the diagnosis of lymph node metastasis had weak consistency with the pathological results (Kappa value=0.426 and 0.131, repsectively). The sensitivity of 60.7%,87.5%, the specificity of 79.6%,34.7%, the area under the ROC curve were0.725,0.590 for short-long diameter ratio and the enhancement CT value in the diagnosis of lymph node metastasis, respectively. Dual-energy CT spectral curve had strong consistency with the pathological results (Kappa value=0.770) and higher sensitivity of 91.1%, the specificity of 83.7%, and area under the ROC curve (0.874) compared with morphological findings.Conclusion The spectrum curve of dual-energy CT had higher sensitivity and specificity than the conventional morphology findings in diagnosis of colorectal cancer lymph nodes metastasis.