The Clinical And Experimental Studies Of HCC Treated With 3D-CRT By MRI

1. Objective:Primary hepatocellular carcinoma (HCC) was one of the most common malignant tumors met in our daily clinical in china. Due to its unobvious symptom and the other cause of the whole body, there are great majority HCC patients lost the chance of radical hepatectomy when the disease was found. Three-dimensional conformal radiotherapy (3D-CRT) is a term that embodies a general strategy for conforming the high-dose region to the target volume while minimizing dose to all the normal tissue, the key to conformal therapy is the accuracy and precision with target and tissue are defined, planning is performed, and treatments are delivered, so any technical improvement that can enhance any of those capabilities will potentially improve the outcome of the therapy. 3D-CRT was welcome by both the physicians and patents because of its satisfactory outcome of HCC and the minimal side affect. With the extensive application of 3D-CRT in HCC, radiation induced liver injuries became more common, moreover, how to evaluate the therapeutic effect of 3D-CRT in HCC, what to do with the leftover of HCC post 3D-CRT, how can we detect the intrahepatic recurrent HCC in earlier stage. All these issues remain to be tackled to oncology radiotherapists and radiologists.In recently years, with the development of many new techniques and application of fast scanning methods, MRI manifested great superiority in imaging the hepatic ailment. Due to its excellent tissue resolution, MRI can reflect the pathologic and physiological alteration and the involved coverage earlier and precisely compared to the computer tomography. Combined with three phase dynamic enhancement, MRI also has the greater sensitivity to in detecting micro and small lesion in the liver.In this study, we study the subjects in the follow-up of MRI in HCC post 3D-CRT:①To analyzes magnetic resonance imaging findings of radiation-induced liver injury。②To analyzes magnetic resonance imaging representations of hepatocellular carcinomas shortly (from 1 to 2 months) after 3D-CRT.③To describe MRI manifestation as well as to discuss the MRI differentiation of residual corpse and intrahepatic recurrent hepatocellular carcinomas of HCC post 3D-CRT.④To construct the liver neoplasm model in rabbits with VX-2 tumor cells, then the rabbits underwent 3D-CRT, MRI of the rabbit liver were performed 12 weeks after radiotherapy, The MRI features of the VX-2 tumor post 3D-CRT was analyzed and correlate to the pathologic findings. Discuss its clinical instructional meaning;⑤Meanwhile, we discuss the MRI application value in the follow-up of HCC post 3D-CRT as well.2. Materials and MethodsIn study of the RILl, MR imaging of 20 patients who had suffered RILI were reviewed. All the patients received 1 or 2 course of 3D-CRT during September 2000 to October 2005 because of the liver neoplasm. 2 patents who were suspected recurrence HCC in MRI but were confirmed RILI after needle punctured and patho-histologily.In the analysis of HCC shortly after 3D-CRT, we study the MRI of 28 patents who had been histologically diagnosed as HCC patients and treated by 3D-CRT were enrolled in this study from September 2000 to October 2005. DT: 52-68Gy/9-34f/20-49d with the median dose of 62Gy. MRI scanning was performed 1 to 3 months after completion of radiotherapy. 12 of these patients have the MRI checkup before 3D-CRT. Sonography was conducted in 9 of these patents in the same period.To study the MRI features of residual corpse and intrahepatic recurrent HCC, we study 36 patients of HCC post 3D-CRT, all the radiotherapy were conducted in the oncology radiotherapy department of Nanfang Hospital, and MRI conducted in the medical imaging center of Nanfang Hospital. The iso-effect biological dosages of the targets were from 62 to 72 Gy in the clinical target volume. The follow-up time was from 15 months to 6 years. In these 36 patients, 15 of them have the MRI check-ups before 3D-CRT, and 3 of them have 6 MRI fellow-up check-ups, 2 have 5times, 3 have 4 times, 8 have 3 times, 12 patents have 2 times, and 8 patents have only one times. Still sonography and CT were conducted at least one time in all these patents.The residual corpse refer to the right site leftovers of the primary HCC post 3D-CRT, and the lesions will never became a neoplasm because its have lost its infinite proliferation ability。Its sizes remained unchanged in the imaging follow-up. To those patents with many times MRI, the first MRI was enrolled in this study.The intrahepatic recurrent hepatocellular carcinomas refer to the lesion newly found within the liver, or the right lesion of the primary HCC post 3D-CRT that keep on multiplicative growing. To those patents with many times MRI, we chose the first MRI for the study.The MRI features of the residual corpse and intrahepatic recurrent HCC were analyzed, their signal-to-noise rate in plain T1WI and T2WI correlated. Enhanced ratio of each stage post Gd-DTPA was compared with each other. All these were test by independent-samples T test, when P≤0.05 the difference has the significances.In the animal experiment, 12 healthy grown-up New Zealand rabbits were used to construct liver VX-2 tumor model, 6 rabbits with relative regular tumor edge and morphous were selected to 3D-CRT. CT scanning was delivered before radiotherapy, and the CT information were transmitted to the FISHER 3D Workstation (three dimensional treatment plan system). The contours of the tumors are defined in the computed tomography (CT). The treatment target volume was defined 1.5cm outside gross tumor volumes. The radiotherapy plan was formulated by physician, with 5 irradiation fields conforms to the desired targets, and with the dose of 30 Gy in single fraction. 6 MV x-ray were adopt. Then the plan was carried out in Varrian 2100 accelerator.There were 4 rabbits surviving for 12 weeks after 3D-CRY, MRI plain scan as well as three phage dynamic enhance scans were carried through on these rabbits. Once the imaging completed, the animals were executed, the liver with the VX-2 tumor was harvested, and then putted into formalin solution to be fixed. After the specimen fixed in the sacrificial, the slices were made and then stained by HE and sliver solution. 2 senior MRI Doctors analyzed the MRI features on both plain and enhanced MRI, and correlated to the pathologic findings.3. ResultsAcute RILI shows as large patch liver edema, with the form similar to the irradiated volume, which was low signal intensity(SI) on T1WI and high intensity on T2WI, no much enhanced during artery and portal-venous phase while administrated by Gd-DTPA, there are exceptional perfusion zone appears in 8 patients during artery phase.Delayed RILI manifested as slightly-low SI on plain T1WI scanning and slightly-high-intensity or iso-intensity signal on T2WI. They were enhanced slowly after administrated by Gd-DTPA, no enhanced or moderate enhanced during artery phase, were enhanced markedly during portal-venous phase and delay phase. The MR signal in the focus was of relative homogeneity, without the exceptionally strengthened area or necrosis inside.The indirect sign of RILI was fluid accumulated under hepatic membrane or ascites in peritoneal cavity. The line of the hepatic contour was not smoothly or even broken in most delayed RILI patients.The MRI changes of the HCC lesions shortly after 3D-CRT include:①.changes of the sizes, according WTO tumor curative effect to measurable focus: there are 6 complete response, composed of 21.4% in this study, 13 partial response (46.4%), 6 no change (21.4%)and 3 progressing (10.8%). The 3 patients with progressing have new HCC foci in the liver.②. On plain MRI images, the lesions were low SI on T1WI and high SI on T2WI, compared to the pre-radiotherapy ones, the intensity decrease on T2WI and ascend on T1WI.③. In contrast enhanced dynamic studies, no or slightly enhancement in arterial and portal vein phase was 9 cases, slight enhancement in arterial phase was 14 cases, markedly enhancement in arterial and portal phase was 5 cases. The degree of enhancement decreased compared to the pre-radiotherapy ones.According to the MRI, the therapy effectiveness was 82.1% in the short-term, while based on the volume evaluation, the therapy effectiveness was 67.8%.In long-term follow-up of MRI in 36 HCC patients post 3D-CRT, MRI reveal there are 8 complete remissions, composed of 22.2% in this study, 22 partial remission (61.1%), 6 no change in volume (16.7%)and 13 progressing (36.1%) on MRI. There were 28 residual corpse in these patients, comparing to the primary volume of the HCC, the decrease in diameter of these HCC varied widely. The residual corpse were of low or slightly low SI on TIWI, and iso-to-high intensity on T2WI, after administrated by Gd-DTPA, 22 residual corpse show no much enhanced during artery and portal-venous phase while 6 lesions were slightly enhanced. In portal-venous phase the lesions were of even lower SI in contract with the normal hepatic tissue. In delayed phase, the normal hepatic tissue enhancement retracted, the residual corpse was reinforcement continuously.There were 15 intrahepatic recurrent HCC, 2 located in the right site where the original HCC located, the volume of the HCC increases continually in long-term follow-up, while the volume decreased in short-term MRI follow-up, the quantity of the intrahepatic recurrent HCC was solitary in 7 patients, with 2 foci located in the right site of the original HCC. The distance between the intrahepatic recurrent HCC and the original lesion was less than 2cm in 2 patients, and in other 3 patients the distance was longer than 3 cm. There are multi- intrahepatic recurrent HCC in 8 patients, 2 lesions in 2 patients, and in the other 5 patients, the intrahepatic recurrent HCC manifested as diffused, widespread nodule range in sizes.The intrahepatic recurrent HCC was of low SI on T1WI, and slightly-to-high SI on T2WI, the T2 signal will be even higher when there is degeneration and necrosis within the lesions. In contrast MRI, the SI rise more quickly in the intrahepatic recurrent HCC than it does in the residual corpse and the normal hepatic tissue. It was markedly enhanced during artery phase and the signal descends slightly in portal-venous phase, then became ios-signal-intensity in delayed phase, which was call 'fast in and fast out' contrast mode.In plain T1WI, the signal-to-noise rate has not significance difference (t=0.514, P=0.005), but in plain T2WI, the signal-to-noise rate has remarkable difference. ( t=2.95, P=0.610). The enhanced ratio has significance difference in artery phase (t=9.77, P＜0.001) and delayed phases(t=3.671, P=0.001), and no significance difference in both portal-venous phase( t=1.184, P=0.243).In the study of rabbit liver VX-2 tumor post 3D-CRT, the VX-2 tumors were implanted in 9 rabbits, with the success rate of 75%. The VX-2 tumor manifested low SI on T1WI and slightly-to-high SI on T2WI before radiotherapy. The VX-2 tumor focus look like nodular, round and ellipse and the other irregular infiltrating form in shape, without clear boundary, and the maximum diameter range from 1.0 to 2.5cm, with the average of 1.5cm.12 weeks post radiotherapy, the leftover of the tumour was of non-uniform high SI on T2WI, there was slightly high signal ribbon between the leftover and normal liver parenchyma, which called as the 'halo' or the 'annular' sign. On the T1WI, the leftover mainly demonstrated as heterogeneity low SI.In contrast MRI, the leftover did not enhanced much in artery phase, during portal vein phase, the leftover enhanced slightly, in the delayed phase, the essence inside the left did not reinforced still, but the peripheral of the leftover was obviously strengthened. The RILI around the leftover was manifested slightly high SI in T2WI, low in T1WI, not enhanced in artery phase, slightly enhanced in portal vein phase, mildly enhanced continuously in delayed phase. The contrast mode was coincident with most residual corpse in human.In the microscope the HE sections of VX-2 tumor have little interstitial constitution, the hepatic cord structure was infiltrated with tumor cell distributed around the neoplasm nidus, the tumor cell disseminated disorderly, fiber textile septa and newly born blood capillary were seen obviously. The cell volume is big with morphous irregular, has rich pale red cytoplasm. The nucleus is big with obviously heteromorphy, stained unevenly. The caryocinesis can be seen frequently.In the HE slices the VX-2 tumor that 12 weeks post 3D-CRT manifested as homogen-erythro-stained region. Some degenerated tumor cell distributed individually in the peripheral compartment, with the various size nucleus inside. The hepatic cells around the tumor were degenerated and necrosis, some liver cells swelling, the lobula structure is disorganized, the blood sinus around the central vein dialated and hyperemia, inflammatory cell infiltrate widespread, in silver staining sections, massive fibrous tissue proliferated and fat drop disperses everywhere.4. Conclusions4.1Acute RILI shows as large patch liver edema, with the form similar to the irradiated volume, was low SI on T1WI and high intensity on T2WI, the SI was low compare to liver parenchyma during artery and portal-venous phase while administrated by Gd-DTPA.Delayed RILI manifested as slightly-low-intensity signal on plain T1WI scanning and slightly-high-intensity iso-intensity signal on T2WI; They were enhanced slowly after administrated by Gd-DTPA, no enhanced or moderate enhanced during artery phase, were enhanced markedly during portal-venous phase and delay phase. The MR signal inside the focus was of relative homogeneity, without the exceptionally strengthened area or necrosis inside.4.2MRI reveal the changes of volume of the HCC lesions shortly after 3D-CRT include complete remissions (21.4%), partial remission (46.4%), no change (21.4%) and progressing (10.8%). The lesions were low SI on T1WI and high intensity on T2WI, compared to the pre-radiotherapy ones, the intensity decrease on T2WI and ascend on T1WI. In contrast enhanced dynamic studies, the enhanced rate descend in arterial phase.According to the MRI, the therapy effectiveness was 82.1% in the short-term follow-up, larger than 67.8% which was basis on the volume measurement.4.3 In long-term follow-up, MRI reveal there are 8 complete remissions(22.2%), 22 partial remission (61.1%), 6 no change (16.7%) and 13 progressing(36.1%) on MRI, compare to the primary volume of the HCC, the contract rate of these HCC was various widely. The residual corpse were of low or slightly low SI on T1WI, and iso-to-high intensity on T2WI, after administrated by Gd-DTPA, these residual corpse manifested as 'slow in and slow out' contrast mode.The intrahepatic recurrent HCC can be the recurrent in situ, recurrent in sub-clinical region, multicentre occurrence and diffused nodule metastasis, the enhanced mode of intrahepatic recurrent HCC was 'fast in and fast out' which coincide with the primary HCC.In plain T1WI, the signal-to-noise ratio has not significance difference (P=0.610), in plain T2WI, the signal-to-noise ratio has remarkable difference (P=0.005).4.4 VX-2 tumors were constructed successfully in rabbit liver with tumor tissue block. It was of low SI in plain T1WI before radiotherapy, high signal in T2WI. 12 weeks after 3D-CRT, it was low in T1WI signal and high signal in T2WI as well, after administrated by Gd-DTPA, the leftover did not enhanced in artery phase, slightly enhanced in portal-venous during, which was consistent to little bloody focus, there was RILI around the leftover. The contrast mode of VX-2 tumor in rabbit post radiotherapy was similar to that of HCC in human.MRI can identify acute and delayed RILI, in short-term follow-up, to those the volumes remain unchanged, MRI reveal efficacy of radiotherapy through the change of SI. In long-term follow-up, MRI discerns the decrease of enhanced ratio. To the intrahepatic recurrent patients, MRI can find the newly recurrences easily. MRI indicated that 3D-CRT can rise local control rate and prolong life expectancy of those patients with HCC, was an effective method in the treatment of these patients. A word in brief, MRI is of great value in HCC post 3D-CRT.