Transhepatic intravascular ultrasound for evaluation of portal venous involvement in patients with cancer of the pancreatic head region.

The aim of this study was to evaluate the ability of intravascular ultrasound to diagnose tumor involvement of the portal and the superior mesenteric veins using the preoperative percutaneous, transhepatic approach, and to compare the findings with those made at concomitant direct portography, surgery, and histopathological examination. Ten patients with a preoperative diagnosis of a resectable tumor in the pancreatic head region were examined with percutaneous transhepatic portography (PTP) and intravascular ultrasound (IVUS). The surgeon's intraoperative evaluation and the histopathological examination in combination revealed tumor involvement of the portal or superior mesenteric veins in six of the ten patients. Percutaneous transhepatic portography suggested tumor involvement of the veins in six patients but two of the examinations were false positive and another two were false negative. Intravascular ultrasound showed signs of tumor involvement in eight patients. The examination was, however, false positive in two patients, but there were no false negatives. Complications of the percutaneous transhepatic procedure occurred in six patients including severe pain, bleeding, and related death. Percutaneous transhepatic IVUS of the portal vein may be a useful tool in the preoperative selection of the subgroup of patients with tumor of the pancreatic head region that could benefit from surgery. There is a need for technical improvement as well as studies with larger patient series to definitely decide the role of the technique.

Interstitial laser thermotherapy in pig liver: effect of inflow occlusion on extent of necrosis and ultrasound image.

BACKGROUND/AIMS: The aim was to investigate the effect of blood inflow occlusion on lesion size and ultrasonographic findings during interstitial laser thermotherapy of normal liver. METHODOLOGY: Pigs were treated with or without hepatic inflow occlusion at a laser power of 3W or without inflow occlusion at 5 W (target temperature 43 degrees C). The thermotherapy system consisted of an Nd:YAG laser and a temperature feedback circuit. Ultrasonography was performed immediately after treatment. Lesion size was determined using light microscopy including immunohistochemistry with bromodeoxyuridine. RESULTS: Hyperechoic ultrasonographic changes were observed after treatment with inflow occlusion or when there was carbonization. If carbonization did not occur, unoccluded blood flow was associated with hypoechoic lesions. Following inflow occlusion, maximum lesion width 2 and 6 days after thermotherapy averaged 21.9 +/- 1.3 and 20.2 +/- 0.8 (means +/- SEM) mm, respectively. This was larger than the corresponding values of 10.8 +/- 0.8 and 11.1 +/- 2.0 observed after treatment without inflow occlusion at 3W (p < 0.01). Increase in laser power from 3 to 5W in experiments without inflow occlusion produced early carbonization and a slight increase in lesion size that did not match that produced by inflow occlusion. Ultrasound gave a correct prediction of necrosis size after treatment with inflow occlusion but overestimated the necrosis when inflow occlusion was not used. Ultrasound was furthermore unable to predict size of necrosis in individual experiments. CONCLUSION: Blood flow has a major influence on lesion size in interstitial laser thermotherapy of the liver and affects ultrasonographic images. Also, it appears that intraoperative ultrasonography cannot monitor lesion size with an accuracy that is sufficient for clinical use.

Intravascular ultrasound for evaluation of portal venous involvement in pancreatic cancer.

The aim of this study was to evaluate the accuracy of intravascular ultrasound (IVUS) in diagnosing tumour involvement of the portal vein in patients with exocrine cancer of the head of the pancreas. Seven consecutive patients with a preoperative diagnosis of carcinoma, preoperatively deemed to be resectable, were examined with IVUS of the portal vein during surgery. The IVUS catheters were 6.2 F (2.0 mm) in diameter with a 20-MHz transducer and were introduced into the portal vasculature through the mesenteric superior vein. All patients had tumour extending to the portal vein as demonstrated at histopathological examinations in six cases and at surgical dissection in one case. The IVUS technique correctly identified all these patients, whereas five patients were incorrectly deemed at surgery not to have tumour involvement of the portal vein. These results indicate that IVUS is a very sensitive method for the evaluation of tumour involvement of the portal vein.

Intravascular ultrasound of the portal vein--normal anatomy.

The purpose of this study was to evaluate the appearance of the normal portal vein with intravascular ultrasound. The portal vein was studied in 10 patients with colorectal carcinoma without known liver or pancreatic disease. For the intravascular portovenous examination, a 2.0-mm, 20-MHz ultrasound catheter was used. The field of view was 30 mm. The wall of the portal vein appeared as a single hyperechoic layer 0.5 to 0.8 mm in thickness. Normal structures adjacent to the portal vein, such as the common bile duct, the hepatic artery or small lymph nodes, were clearly separated from the lumen of the portal vein by the wall of the vein together with some periportal fat. In most cases the parenchyma of the pancreas could be separated from the wall of the vein.

[Medical imaging and the future.].

This article addresses the topic of medical imaging and the future, the effect of organisation and new technology. Examples of new and future technology such as computed radiology, three dimensional imaging, new intervention techniques and mixture of imaging modalities are discussed.