64-slice Spiral Ct Stage-4 Enhanced And Perfusion Scans In The Diagnosis Of Small Hepatocellular Carcinoma

Background and objectiveHepatocellular carcinoma is a common malignant tumor of liver with poor prognosis. Short survival time of patients and without treatment for advanced liver cancer, the survival period is only 0.7-3 months. But the survival time of Small Hepato-Cellular Carcinoma (SHCC) patients increases significantly following early detection and diagnosis. As reported by a 5-year survival rate of up to 60% after early operation in our nation. Therefore early detection and diagnosis of SHCC has become a hot topic of research. In this study, we applied 64-slice volume CT via the following aspects in order to get more imaging information of SHCC, thereby enhancing the diagnostic accuracy and to guide the clinical treatment. Aims:①To explore the value, scanning method and announcements of 64-slice spiral CT stage-4 enhanced and perfusion imaging in the diagnosis of SHCC.②To calculate perfusion parameters of SHCC, tumor-free hepatic parenchyma and the contrast liver tissues and compare their differences.③To explore the differences among the perfusion parameters and CT images of SHCC's different pathological stages.Materials and methods1. Clinical dataSuspected 30 cases (34 lesions) of SHCC from May 2008 to March 2009, including 28 males and 2 females, with a mean age of 53 years (range 32 - 76 years), and two of them with local recurrence cases, were selected. The diagnosis had been confirmed of SHCC by Pathology or General Clinical Examination. All patients underwent 64-slice spiral stage-4 enhanced CT scan and CT perfusion imaging (CTP). Two of the cases that had undergone Radiofrequency Catheter Ablation (RFCA) before doing a CTP imaging were also collected.2. Scanning method2.1 Scanning method of stage-4 enhanced CT scan of liverPatients with fasting, were asked to drink water 800-1000ml before scanning, conventionally taking abdominal belt and using the GE 64-ranked light-speed VCT for scanning. SmartPrep software was used to control the scan at real time, after injecting 100ml of non-ionic contrast agent (Iohexol 350mgI/ml) at 3ml/s in the vein of forearm. When the concentration of contrast agent in the abdominal aorta had reached to the threshold (150Hu), the scanning was started. This scan included four phases: Early Artery Phase (delay about 20s), Late Artery Phase (delay about 30s), Portal Vein Phase (delay about 60s) and Delayed phase (delay about 120s).2.2 CTP scanning methodFasting patients, were asked to drink water 800-1000ml before scanning, conventionally taking abdominal belt and using the GE 64-ranked light-speed VCT for scanning. They were injected 45 ml of non-ionic contrast agent (Iohexol 300mgI/ml) fast at 4ml / s in the vein of forearm. The patients were asked to take small breath or, even hold their breath while scanning for locations where breathing had a great impact with the combination of patient's physical condition. At the first scan, whole liver was imaged for any tumors or mass using plain CT film. Then the tumor level (including the abdominal aorta, portal vein and its branches as far as possible) were selected and multi-layer dynamic perfusion scan in accordance with the protocol of liver tumor perfusion was carried out. Five cases using Movies Scan Mode (Cine full 1.0sec), the remaining cases using axial mode were used. Scan thickness 5mm/4i (later reconstructed to 10mm/2i), field scanning- Large voltage (Kv): 120KVp, current (mA): 60mA delayed 5s, scan time: 40-50s, sweep axis to be 200 layer 5mm image (Film scan layer images). After the scan, the data was transmitted to the workstation AW4.3 (Sun Micro-system Advantage Windows 4.3GE Medical Systems). 3. Data Processing3.1 The data processing of stage-4 enhanced CTFirstly, the size and feature of the tumor were registered. Secondly, using Volume Rendering (VR) and Maximum Intensity Projection (MIP), localized the feeding arteries of the SHCC.3.2 The data processing of CTP imageThe data was calculated, mapped and analyzed using GE's liver tumor perfusion of CT perfusion-3.0 perfusion package to generate specific types of quantitative function images and perfusion parameters. The abdominal aorta and portal vein or its branches in the series as supplying vessels were marked, size placed by 2-6 pixels in order to avoid partial volume effects. In order to wipe off the effects of the bone, fat tissue and air, the leak points (0-200Hu) were defined. Then regions of interest (ROI) was selected and read the following perfusion parameters: blood flow (BF), blood volume (BV), mean transit time (MTT), permeability of surface (PS), hepatic arterial fraction (HAF). The parametric figure and time density curve (TDC) of ROI was obtained. Based on the data obtained, the hepatic artery perfusion (HAP): HAP= HBF×HAF was calculated. All measurements were repeated during the study period, and got the average value. Regions of interest were selected, to measure the relevant parameters of SHCC, tumor-free hepatic parenchyma (1cm from the edge of tumor ) and the non-tumor liver tissues (2-5cm from the edge of tumor) and SHCC to select the largest blood volume area.4. Pathological examination of the Collected SpecimenThe specimen from the tumor were collected and sent for histopathological examination. Histopathologically, the lesions were divided into two groups: High-and mid-differentiated SHCC. Among the collected lesions no low-differentiated SHCC was seen.5. Statistical MethodsAll data were handled by SPSS statistical package. Measurement data demonstrated in X|-±s, and the reference range 95% confidence interval used. Comparison between two groups was done using independent sample t-test. The three groups were compared using one-way ANOVA. Multiple comparisons between mean was done with LSD if variance was regular and using Games-Howell method if variance was irregular. The correlation of parameters were analyzed by Pearson's method (enumeration) or Spearman's method (ranked data), P<0.05 represented statistical difference, P<0.01 represented a very significant statistical difference.Results1. Out of the 34 lesions, 9 cases were located in the left lobe and 25 cases in the right lobe. 14 of 34 lesions showed high-density in early arterial phase ,with the average CT value (75.6±23.1) HU, and the detection rate was 41.2% ; 28 lesions showed high-density in advanced arterial phase, with the average CT value (92.9±16.5) HU, and the detection rate was 82.4% ; 31 lesions showed high-density in dual-arterial phase, with a detection rate of 91.2% ; 29 lesions showed low-density in portal venous phase (the other five lesions, showed the same or high density), and the detection rate was 85.3% ; 32 lesions showed low-density in the delayed phase with a detection rate of 94.1% (the other two, still showed the same density, and their diagnosis were SHCC by comprehensive clinical data, later they were confirmed by DSA to be SHCC having a rich blood supply.). 4 cases in 7 lesions which showed high-density in early arterial phase showed the same or low-density performance in advanced arterial phase. Other two lesions showed low-density in both arterial and portal venous phase, later they were confirmed by DSA to be SHCC having poor blood supply. The characteristics of the lesions from stage-4 enhanced scan and TDC performances by perfusion had a better consistency, and using early-arterial-phase images SHCC's arterial blood supply could be reconstructed in 18 cases.2. The characteristics of CT stage-4 enhanced scan and TDC performances by perfusion of SHCC had a good consistency. The size, edge, enhancement peak and strengthening degree of SHCC, the perfusion parameters of lesions and pathological types were correlated. 3. Perfusion parameters derived from different scan mode (movie-scanning and sweep axis) had no statistical differences. It comes to be an advantage of axial scan mode to be effective to reduce the radiation dose.4. The differences of BF, BV, HAF and HAP between SHCC and the contrast liver tissues were significant (p<0.05), and the above-mentioned parameters of SHCC was significantly higher. The differences of the above-mentioned parameters were statistically significant between SHCC with clear boundaries and tumor-free hepatic parenchyma (p<0.05). The above-mentioned parameters had no statistical differences between SHCC with unclear boundaries and tumor-free hepatic parenchyma.5. The enhanced original images and perfusion images had a statistical difference in the measurement of tumor size of SHCC (P<0.05), and perfusion imaging showed a larger tumor size.6. The perfusion parameters had statistical differences in different pathological types of SHCC. HAF and HAP of moderately differentiated group were higher than the well differentiated group.Conclusions1. The application of 64-slice VCT to do stage-4 enhanced scan not only can improve the detection rate of SHCC, but also provide richer, visualized imaging information.2. Axial scan mode not only can obtain more accurate perfusion parameters, and compared with the film scanning mode, can effectively reduce the radiation dose with well applying prospects.3. By calculating SHCC's blood perfusion parameters, we can quantitatively analyze its blood supply. This contributes to its diagnosis and treatment protocol options. Moreover, perfusion images can be more accurate to detect the size of the lesions in order to guide, choosing the right clinical hepatic resection or embolization and the scope of radiofrequency catheter ablation and to avoid recurrence or metastasis with too small extent of treatment. 4. We can infer the degree of malignancy via CT imaging performances and the change of CT perfusion parameters of SHCC. This will help to enact clinical therapeutic measures and judge therapeutic efficacy and prognosis.