ABSTRACT
PURPOSE: New methods of noninvasive high resolution imaging may improve the delineation of tumor microvessels and, thus, be of significant help in surgical planning and cost-effective monitoring of novel anti-angiogenic therapy. We determined the maximum delineation of intrarenal microvessels with a novel flat panel based volume computerized tomography system in an experimental setting. MATERIALS AND METHODS: We prospectively evaluated 13 porcine renal specimens for intrarenal vessel delineation using a prototype gantry based, flat panel, cone beam computerized tomography system. The gantry incorporates an array of a 40 x 30 cm(2) CsI amorphous silicon flat panel detector consisting of a 2,048 x 1,536 matrix. After catheterizing the renal artery with a 5Fr end hole catheter a contrast enhanced scan was performed using BaS as contrast medium at a dilution of 200 mg/ml. The diameter of all definable arterial branches was determined using a software tool based on Medical Imaging and Interaction Toolkit, allowing semi-automatic segmentation of the vessel tree. In step 1 the vessel tree is segmented by a 3-dimensional region growing algorithm. Following its medial axis the vessel tree is extracted and converted to a representation, including the diameter of the vessels. RESULTS: In each kidney an average +/- SD of 47,454 +/- 22,382 arterial branches could be delineated. The diameter of the branches was 0.029 (mean 0.032 +/- 0.0025) to 3.444 mm (mean 1.813 +/- 0.6139) with a median of 0.263 mm. Of visible intrarenal arteries 2.7% had a vessel diameter of 0.029 mm. CONCLUSIONS: Flat panel based volume computerized tomography can visualize intrarenal microvessels down to a diameter of 0.03 mm. It may improve the assessment of renal microvessel architecture in healthy patients and in those with pathological conditions.
Subject(s)
Renal Artery/diagnostic imaging , Tomography, X-Ray Computed , Animals , Imaging, Three-Dimensional , Microvessels/diagnostic imaging , Swine , Tomography, X-Ray Computed/methodsABSTRACT
We report a rare case of late transjugular intrahepatic portosystemic stent shunt (TIPSS) occlusion due to progressive stent protrusion into the periportal liver parenchyma, which was a result of delayed liver shrinkage 2 years after TIPSS. The initial TIPSS procedure had been carried out in a 52-year-old man as a bridge for liver transplantation because of post-alcoholic liver cirrhosis. We describe the applied TIPSS recanalization and revision technique. Immediately after TIPSS revision acute liver failure developed, which required emergency liver transplantation.
Subject(s)
Liver Failure, Acute/etiology , Portasystemic Shunt, Transjugular Intrahepatic/adverse effects , Postoperative Complications/etiology , Bilirubin/blood , Emergency Treatment/methods , Fatal Outcome , Humans , Hyperbilirubinemia/complications , Hyperbilirubinemia/diagnosis , Liver/diagnostic imaging , Liver/injuries , Liver/surgery , Liver Cirrhosis, Alcoholic/surgery , Liver Failure, Acute/diagnosis , Liver Failure, Acute/surgery , Liver Transplantation/adverse effects , Liver Transplantation/methods , Male , Mesenteric Artery, Superior/diagnostic imaging , Middle Aged , Organ Size , Portal Vein/diagnostic imaging , Portography , Postoperative Complications/diagnosis , Postoperative Complications/surgery , Prosthesis Failure , Pulmonary Embolism/etiology , Reoperation , Thrombosis/complications , Thrombosis/diagnosis , Time , Transaminases/blood , UltrasonographyABSTRACT
Computed tomography (CT)-guided percutaneous radiofrequency ablation (RFA) has become a commonly used procedure in the treatment of liver tumors. One of the main challenges related to the method is the exact placement of the instrument within the lesion. To address this issue, a system was developed for computer-assisted needle placement which uses a set of fiducial needles to compensate for organ motion in real time. The purpose of this study was to assess the accuracy of the system in vivo. Two medical experts with experience in CT-guided interventions and two nonexperts used the navigation system to perform 32 needle insertions into contrasted agar nodules injected into the livers of two ventilated swine. Skin-to-target path planning and real-time needle guidance were based on preinterventional 1 mm CT data slices. The lesions were hit in 97% of all trials with a mean user error of 2.4 +/- 2.1 mm, a mean target registration error (TRE) of 2.1 +/- 1.1 mm, and a mean overall targeting error of 3.7 +/- 2.3 mm. The nonexperts achieved significantly better results than the experts with an overall error of 2.8 +/- 1.4 mm (n=16) compared to 4.5 +/- 2.7 mm (n=16). The mean time for performing four needle insertions based on one preinterventional planning CT was 57 +/- 19 min with a mean setup time of 27 min, which includes the steps fiducial insertion (24 +/- 15 min), planning CT acquisition (1 +/- 0 min), and registration (2 +/- 1 min). The mean time for path planning and targeting was 5 +/- 4 and 2 +/- 1 min, respectively. Apart from the fiducial insertion step, experts and nonexperts performed comparably fast. It is concluded that the system allows for accurate needle placement into hepatic tumors based on one planning CT and could thus enable considerable improvement to the clinical treatment standard for RFA procedures and other CT-guided interventions in the liver. To support clinical application of the method, optimization of individual system modules to reduce intervention time is proposed.