Imaging Center, Nanfang Hospital, First Military Medical University, Guangzhou 510515, Guangdong Province, China
Correspondence to Xue-Lin Zhang, Imaging Center, Nanfang Hospital, First Military Medical University, Guangzhou 510515,Guangdong Province, China
Received 1997-12-05 Revised 1998-03-01
Abstract
AIM To compare the enhanced effects of computed tomography during percutaneous spleonoportography (CTSP) and computed tomography arterial portography (CTAP) on liver.
METHODS Ten dogs were examined by CTSP through percutaneous spleen puncture and by CTAP using a catheter inserted from the left femoral artery to mesenteric cranial artery. The two CT values were compared.
RESULTS The liver CT values of plain scan, CATP and CTSP was 70.5Hu±8.7Hu, 209Hu±23.9Hu and 212Hu±28.2Hu, respectively, and that of the portal vein was 35Hu±3.5Hu, 468Hu±65.1Hu and 485Hu±61.2Hu, respectively.
CONCLUSION Both CTAP and CTSP could obviously enhance the liver CT image (P<0.01), showing no statistical difference (P>0.05). CTAP and CTSP could significantly enhance the portal vein CT image.
Subject headings liver/radiography; tomography, emission-computed, single-photon; portography
INTRODUCTION
CT during splenoportography (CTSP) is an examination we established to show the occupant disorders in livers[1], in which, the spleen was punctured percutaneously and the contrast medium was injected into the veins or substance of the spleen. Then the liver was infused with the contrast medium to show the occupant lesions. In 1980, Hisa et al created computed tomography arterial portography (CTAP). Through long-term clinical application, CTAP is thought to be the most sensitive method to examine the occupant disorders in the liver at present[2,3]. Unfortunately, to get a CT image by this method, the contrast medium must be injected through a catheter from the femoral artery to the superior mesenteric artery under X-ray. The examination can not be made in the CT room independently, for many instrucments were needed and the operation was complex. Therefore, the application of CTAP was limited.
Based on the CTAP examination, we established CTSP to show the occupant disorders in the liver, with satisfactory results. To compare the enhancing effects of CTSP and CTAP on the liver CT image, animal experiment was conducted and the results are reported below.
MATERIALS AND METHODS
Experimental animals
Ten Mongrel dogs were purchased from Guangdong area, Including four males and six females, with an average weight of 16.45kg (ranging from 14kg-18kg). They were all normal in routine blood test, liver function test and bleeding and clotting time. They were raised in our animal breeding unit.
Instruments5F Cobna catheter 800mA remote control gastrointestinal machine (Daojin, Japan) was used for the CTAP examination; Somaton Plus systemic CT machine (Simens Company, Germany) was used for CT examination; and MCT 310-2 model CT syringe(Medrad Company, USA) and 20G puncture trocar (Teruno Company, Italy) were used for CTSP examination.
Procedures
CT plain scan. The dogs were anesthetized with 3% sodium pentobarbital (30mg/kg body weight). The dogs were placed in right prone position and their heads were sent into the CT machine first. They were scanned from the tops of diaphragms to the inferior margin of the livers. Each layer was 10mm thick and the distance between two neighboring layers was 10mm. Ten to thirteen pictures were obtained from each dog.CTAP examination. It was made after the CT plain scan. A catheter was inserted from the left femoral artery to the mesenteric cranial artery by Seldinger method. The catheter was proved to be in the right place by angiography. Six hours later, 76% meglucamine diatrizoate was injected at a rate of 1.5ml/sec through the catheter into the dogs with a CT syringe (1.5ml/kg body weight). The dogs were scanned by the continuous dynamic method in the same position and the same range as CT plain scan. After the operation, the catheter was pulled out and the wound was pressed to stop bleeding, and the animals were observed in the animal breeding unit.
CTSP examination. Seven days after the CTAP examination, CTSP was performed. According to the position of the spleen shown by the CT image, a 20G puncture trocar was pricked into the spleen till the tip of the trocar reached the wide veins or the substance in the hilus of the spleen. When the needle point was proved to be in the proper place by the CT image, the CT syringe was linked to the trocar and the contrast medium was injected as mentioned in the CTAP examination. The animals were scanned in the same way as CTAP examination.
RESULTS
The CT value of the liver in CT plain scan was 70.5Hu±8.7Hu. Both CTAP and CTSP examinations could obviously enhance the value (P<0.01), showing no statistical difference (P>0.05), Figures 2-4). They could also significantly enhance the CT value of the portal vein (Figures 5-6). The CT values of the liver and the portal vein determined by CT plain scan, CTAP and CTSP are listed in Tables 1 and 2.
Table 1 The CT values of liver determined by the three methods (Hu) | CT plain scan | CTAP | CTSP | | Left external lobe | 71 ±10.5 | 214±25.1 | 223±29.1 | | Right external lobe | 68 ±9.1 | 198±28.1 | 201±31.1 | | Caudal lobe | 76 ±7.0 | 221±21.4 | 214±24.5 | | Average | 70.5±8.7 | 209±23.9 | 212±28.2 |
Table 2 The CT values of portal vein determined by the three methods (Hu) | CT plain scan | CTAP | CTSP | | Stem | 35±3.5 | 638±86.4 | 713±69.1 | | Left ramus | 32±2.6 | 374±52.1 | 362±68.3 | | Right ramus | 30±3.1 | 414±61.3 | 421±53.4 | | Average | 32±3.1 | 468±65.1 | 495±61.2 |
Figure 1 Cranial mesenteric arteriograph. The tip of the catheter was clearly demonstrated to be placed in the stem of the cranial mesenteric artery.
Figures 2-4 The CT images of D4 liver, showing that both CTAP and CTSP significantly enhanced the liver density. Figure 2, CT plain scan image; Figure 3, CTAP image; Figure 4, CTSP image.
Figures 5-6 The CT images of D1 liver. Figure 5, CTAP image; Figure 6, CTSP image. The portal vein was clearly demonstrated by both CTAP and CTSP.
DISCUSSION
The blood of the liver is supplied by both the portal vein and the hepatic arteries, accounting for about 80% and 20% of the total blood the liver needs. In CTAP examination, the catheter was inserted from one femoral artery to the mesenteric cranial artery and the contrast medium refluxed to the liver through the portal vein so that the density of the liver was greatly enhanced. In CTSP examination, the contrast medium was directly injected into the spleen or its veins and then refluxed to the liver. The contrast medium refluxed to the liver through different circulation paths in the two examinations (Figure 7).
Figure 7 The different circulation paths of CTAP and CTSP. A:artery; V:vein
This experimental study showed that CTSP had a similar enhancement effect on liver with CTAP which provided good imaging basis for CTSP to show hepatic disorders. When the needle tip was pricked to the wide veins of the spleen, no contrast medium was found by the CT scan, while when the needle tip was pricked to the lienal substance, the contrast medium could be found to stay in the spleen for a very short time by CT scan. However, there was no statistical difference between the two conditions in term of their enhancement effects on the liver. Therefore, good enhancement effects on the liver could be achieved by injecting the contrast medium into the lienal veins or the lienal substance.
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(Xue-Lin Zhang and Shi-Jun
Qiu)
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