Magnetic resonance myocardial perfusion imaging for evaluating myocardial viability after myocardial infarction / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the value of magnetic resonance (MR) myocardial perfusion imaging (MRMPI) in evaluating the myocardial viability in patients with myocardial infarction.</p><p><b>METHODS</b>MRMPI was performed in 51 patients with myocardial infarction using a 1.5 T MR scanner. All the patients were examined using IR-turbo FLASH sequence during the first-pass and delayed phase 5-30 min after injection of 0.1 mmol/kg Gd-DTPA at the rate of 4 ml/s. The short axis images were acquired during the first-pass, and both the short axis and long axis images were obtained during the delayed phase. The left ventricular wall on the short-axis slice was divided into 8 segments. A correlative study of the results of the rest and stress (99m)Tc single photon emission computed tomography (SPECT) was carried out in 21 patients.</p><p><b>RESULTS</b>In the 51 patients with myocardial infarction, 42(82.3%) showed hypoperfusion during the first-pass imaging and 50(98%) had delayed hyperenhancement. In the 21 patients receiving SPECT, 48 nonviable segments was detected among the 168 segments scanned by (99m)TcSPECT, and MRMPI showed delayed hyperenhancement in all the infracted areas. Of the 120 viable segments detected by rest and stress (99m)Tc SPECT, 97 segments (80.8%) were found to be free of delayed hyperenhancement by MRMPI. With the rest and stress (99m)Tc SPECT as the reference, the sensitivity and the specificity of MRMPI were 100.0% and 80.8%, respectively.</p><p><b>CONCLUSION</b>MRMPI allows effective identification of the myocardial viability and nonviability as well as the severity and extent of the myocardial infraction.</p>

Optimization of the scan delay time of 64-slice spiral CT portal venography / 南方医科大学学报

<p><b>OBJECTIVE</b>To optimize scan delay time of multi-slice spiral CT portal venography (MSCTP) using test bolus injection.</p><p><b>METHODS</b>Sixty individuals with no hepatic diseases were randomly divided into 4 groups (A, B, C and D). The time-density curves (TDC) of the portal vein (PV) were acquired by test bolus (15 ml, 5 ml/s) at the level of liver hilus. In the 4 groups, the MSCTP were delayed for 4, 6, 8 and 10 s according to the peak time of TDC, respectively. The maximum CT value of the portal vein and liver parenchyma were recorded. The maximum intensity projection (MIP) and volume rendering (VR) were employed for three-dimensional reconstruction and the image quality of the 4 groups was estimated.</p><p><b>RESULTS</b>The average peak time of healthy individuals ranged between 24 and 32 s (95% confidence interval) by means of the test bolus (15 ml). Group C (delay time of 8 s) had a much better image quality of the portal vain than the other groups, and the small branches of the portal vein (6th and 7th orders) were clearly visualized; the major portal vein branches (1st to 4th orders) were also enhanced with sharp edges. Although the hepatic vein was also observed in the portal venous phase in group D, the details of the portal vein on the hepatic edge were distinct and well defined.</p><p><b>CONCLUSION</b>At the injection rate of 5 ml/s, the optimum scan time delayed is 8 to 10 s in normal individuals according to the peak time of the test bolus.</p>

Preparation of VX2 rabbit hepatoma models and modification of the hepatic artery catheterization technique / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish New Zealand rabbit hepatoma models with VX2 cell line, and modify the hepatic artery catheterization technique.</p><p><b>METHODS</b>Forty New Zealand rabbit models bearing hepatoma were established by implanting VX2 cells into the left and right liver lobes. Two weeks after the tumor cell implantation, 26 rabbits in the experimental group underwent modified hepatic artery catheterization procedures using microsurgical technique, and 10 rabbits in the control group were catheterized with 3F micro-catheter using Seldinger technique. The VX2 hepatomas were observed before and after the catheterization with multi-slice spiral CT scan and digital subtractive angiography (DSA).</p><p><b>RESULTS</b>Tumor growth after the tumor cell implantation was confirmed in 36 rabbits by CT scans and open operations. The success rate of catheterization was 88% (23/26) in the experimental group, and 40% (4/10) in the control group. VX2 hepatomas appeared as hypointense or isointense nodules on multi-slice spiral CT, and hepatic artery angiography showed that VX2 hepatomas had homogeneous or nodular tumor staining.</p><p><b>CONCLUSION</b>The modified hepatic artery catheterization using microsurgical technique has higher success rate than catheterization with 3F micro-catheter by Seldinger technique, and significantly decreases X-ray exposure for the staff undertaking the operations.</p>

Study on the three dimensional hepatic virtual operation based on the data of 64-slice helical CT scanning / 中华外科杂志

<p><b>OBJECTIVE</b>To study the surgery plan and simulation effect of the three dimensional (3D) hepatic virtual operation based on the data of 64-slice helical CT scanning and to probe the feasibility of the virtual operation based on the FreeForm Modeling System.</p><p><b>METHODS</b>The volunteer liver was scanned to collect two dimensional (2D) DICOM data of 64-slice helical CT scanning and the 3D hepatic and intrahepatic vessels model were reconstructed by MIMICS software. The reconstructed liver, the intrahepatic vessels model and the artificial tumor models were output into the FreeForm Modeling System in the STL format. The device PHANTOM with the characterization of dynamo-feedback was applied to make the operation on the 3D hepatic.</p><p><b>RESULTS</b>The spatial relationship between the tumour and the intrahepatic vessels were clearly observed by rotation and enlargement of the target. According to the operation principle, the left lobe of liver resection was simulated by manipulating the device PHANToM. Through the liver transparence surface, the intrahepatic vessels were easily distinguished. The operation procedure was accord with the clinic hepatic surgery. Meanwhile, during the operation, by adjusting the incision objective intensity, the dynamo-feedback intensity was definitely touched.</p><p><b>CONCLUSIONS</b>By using the FreeForm Modeling System,the hepatic operation procedure can be simulated ahead of time. The operation complication in the practical surgery can be anticipated and the individualization operation schema can be reasonable instituted.</p>

Image segmentation and three-dimensional reconstruction of the liver based on 64-slice spiral CT scanning data / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the segmentation methods of the liver CT images and the value of 3-dimensional (3D) reconstruction of the liver in the planning of hepatic surgery.</p><p><b>METHODS</b>The 2D Digital Imaging and Communications in Medicine (DICOM) format data of the liver obtained from healthy volunteers were transformed into bmp format image, and the liver image segmentation was performed using Photoshop software. The 3D model was reconstructed using MIMICS software.</p><p><b>RESULTS</b>The DICOM format data of the liver obtained by 64 slice spiral CT included totally 658 slice images. The segmented liver image showed clear profiles and complete intrahepatic duct data were reserved. The segmented liver images were free of discontinuation during continuous observation. The liver surface and internal ductal system, including the hepatic arteries and veins, and the hepatic portal system and their branches, were represented clearly. The reconstructed liver allowed clear identification of the anatomic landmark and matched the actual liver volume. The reconstructed ductal structure were distinct and continuous with natural texture. The reconstructed liver and the hepatic internal duct system were simultaneously displayed by adjusting the transparency of the liver, and the blood vessels were also represented.</p><p><b>CONCLUSION</b>Segmentation of the liver images in different phases using Photoshop can be feasible for liver reconstruction. The reconstructed liver and the intrahepatic ductal structure allow vivid 3D observation of the spatial relationship among the major tracts and accurate estimation of the liver volume.</p>

The value of three-dimensional 64-multi-slices helical computer tomography on the diagnosis of diseases of digestive system / 中华外科杂志

<p><b>OBJECTIVE</b>To study the value of three-dimensional 64-slice helical computer tomography (64-MSCT) in diagnosis and surgical treatment on diseases of digestive system.</p><p><b>METHODS</b>From November 2005 to August 2006, 64-MSCT was performed on 102 patients suspected of digestive diseases to display foci of infection, hepatic conduit, biliary-pancreatic duct and portal venous system, followed by three-dimensional reconstruction of those targets. The reconstructed images as well as the data obtained from the reconstruction were compared with the surgical results.</p><p><b>RESULTS</b>Twenty-five of 27 patients with portal hypertension (PHT) showed blur-free imaging of main portal vein (MPV) while the other 2 cases showed congenital cavernous transformation or thrombogenesis of MPV. Compensatory circulation of portal venous system was displayed satisfactorily in 27 cases. The three-dimensionally reconstructed images of 34 cases of hepatocellular carcinoma (HCC) demonstrated no invasion of tumors into the tissues and blood vessels of 23 cases, visible invasion into portal vein and hepatic veins of 9 cases, tumor embolus in portal veins of 1 case, and arterio-venous fistula in only one case. The 3D imaging of biliary passages displayed total concretion, tumor and constrictive or dilated biliary-pancreatic duct and bile duct around amphi-obstruction, which complied with the operations research of calculus of bile duct in 25 cases, cholangiocarcinoma in 5 cases, and cancer of pancreas in 5 cases. Operations research in accordance with the 3D reconstructed imaging accorded with imaging diagnosis in respect of PHT, HCC and diseases of biliary-pancreatic system at the rates of 100%, 97% and 100%, respectively.</p><p><b>CONCLUSIONS</b>Three-dimensional 64-MSCT displays foci of infection and constructions of biliary-pancreatic duct and hepatic conduit stereoscopically.</p>

Preliminary quantitative study of dynamic magnetic resonance diffusion tensor imaging in rabbit models implanted with hepatic tumor grafts from VX2 / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the feasibility of dynamic magnetic resonance diffusion tensor imaging (DTI) in rabbit models with implanted VX2 hepatic tumor grafts.</p><p><b>METHODS</b>MRI and DTI images were obtained from 16 rabbit models with implanted VX2 hepatic tumor grafts (14, 18, 22, and 26 days after tumor implantation, respectively) and 4 normal rabbits. The average diffusion coefficient (ADC) and exponential ADC (eADC) were estimated and compared against pathological findings.</p><p><b>RESULTS</b>The ADC values increased after tumor implantation but then decreased in the rabbit models, whereas eADC exhibited a pattern of reverse changes. These changes significantly differed from those in the control group. Coagulation necrosis and fibrous hyperplasia showed obvious increase as found by pathological examination.</p><p><b>CONCLUSION</b>Dynamic MR DTI quantitative analysis of rabbit models of implanted VX2 hepatic tumor can partially describe the growth behaviors of implanted liver cancer.</p>

Quantitative study of dynamic magnetic resonance perfusion-weighted imaging in rabbit models of implanted hepatic VX2 tumor / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the possibility of dynamic magnetic resonance (MR) perfusion-weighted imaging (PWI) in rabbit models of implanted hepatic VX2 tumor.</p><p><b>METHODS</b>MRI and PWI images were obtained from 16 rabbit models of implanted hepatic VX2 tumor and 4 normal rabbits at 14, 18, 22, and 26 days after tumor implantation, respectively, and the mean time to enhancement (MTE) and maximum slope of increase (MSI) were estimated and compared with pathological changes.</p><p><b>RESULTS</b>In the rabbit models of implanted hepatic tumor the MTE tended to increase and MSI to descend 14, 18, 22, and 26 days after tumor implantation, showing significant differences from the control group. Coagulation necrosis and fibrous hyperplasia in the tumors appeared to progress with time as found pathologically.</p><p><b>CONCLUSION</b>Dynamic MR PWI quantitative analysis of rabbit models of implanted hepatic VX2 tumor provides valuable means for observing the growth behaviors of VX2 tumor and may be clinically applicable in the evaluation of hepatic diseases.</p>

Modification of the method for preparing rabbit liver VX2 tumor model and its MRI findings / 南方医科大学学报

<p><b>OBJECTIVE</b>To improve the method for preparing rabbit VX2 liver tumor model and observe the magnetic resonance imaging (MRI) features of the implanted tumors.</p><p><b>METHODS</b>Sixteen adult New Zealand white rabbits were assigned randomly into 4 equal groups, and VX2 tumor tissues were implanted into the right and left liver lobes with spiral CT guidance. Plain and contrast-enhanced MR scan and pathological analysis were performed in different stages (14, 18, 22 and 26 days) after tumor implantation.</p><p><b>RESULTS</b>Tumor implantation was successful in all the rabbits, and 18 to 22 days after tumor implantation, the diameters of the tumor ranged from 1 to 2 cm, which allowed observation and study. In plain MR scans, lower or equivalent tumor signal in comparison with hepatic parenchyma was observed, and contrast-enhanced scans produced obvious enhancement of the tumor edges. At 22 days after tumor implantation, obvious necrosis was observed in the center of the tumor.</p><p><b>CONCLUSION</b>This method of preparing rabbit VX2 liver tumor model with spiral CT guidance is simple and convenient, and the tumors can be observed effectively with dynamic plain and contrast-enhanced MR scans.</p>

Quantitative study of diffusion weighted imaging on magnetic resonance imaging in focal hepatic lesions less than 3 cm / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the characteristics of MR imaging of hepatic lesions using measurement of apparent diffusion coefficient (ADC) value of hepatic lesions on diffusion weighted imaging.</p><p><b>METHODS</b>MR diffusion weighted images were obtained in patients with 97 hepatic lesions (22 hepatocellular carcinomas, 21 metastatic tumors, 28 hemangiomas, 26 cysts). ADC values were evaluated with different sequences. The ADC ratio of lesion/liver was estimated.</p><p><b>RESULTS</b>Average ADC values of hepatic lesions were as follows: carcinomas (0.91 +/- 0.07) x 10(-3) mm(2)/s, metastatic tumors (1.13 +/- 0.27) x 10(-3) mm(2)/s, cavernous hemangiomas (1.94 +/- 0.37) x 10(-3) mm(2)/s, cysts (3.26 +/- 0.30) x 10(-3) mm(2)/s. The ADC ratio of lesion/liver was significantly different between primary carcinomas and metastatic tumors (P < 0.05).</p><p><b>CONCLUSION</b>Quantitative study in hepatic lesions using ADC values and the ADC ratio of lesion/liver, would improve the accuracy in diagnosing hepatic lesions.</p>