Intrarenal artery delineation with ultra high resolution, flat panel based, volume computerized tomography: outer limits of spatial resolution.

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.

The practical clinical value of three-dimensional models of complex congenitally malformed hearts.

OBJECTIVE: Detailed 3-dimensional anatomic information is essential when planning strategies of surgical treatment for patients with complex congenitally malformed hearts. Current imaging techniques, however, do not always provide all the necessary anatomic information in a user-friendly fashion. We sought to assess the practical clinical value of realistic 3-dimensional models of complex congenitally malformed hearts. METHODS: In 11 patients, aged from 0.8 to 27 years, all with complex congenitally malformed hearts, an unequivocal decision regarding the optimum surgical strategy had not been reached when using standard diagnostic tools. Therefore, we constructed 3-dimensional virtual computer and printed cast models of the heart on the basis of high-resolution whole-heart or cine magnetic resonance imaging or computed tomography. Anatomic descriptions were compared with intraoperative findings when surgery was performed. RESULTS: Independently of age-related factors, images acquired in all patients using magnetic resonance imaging and computed tomography proved to be of sufficient quality for producing the models without major differences in the postprocessing and revealing the anatomy in an unequivocal 3-dimensional context. Examination of the models provided invaluable additional information that supported the surgical decision-making. The anatomy as shown in the models was confirmed during surgery. Biventricular corrective surgery was achieved in 5 patients, palliative surgery was achieved in 3 patients, and lack of suitable surgical options was confirmed in the remaining 3 patients. CONCLUSION: Realistic 3-dimensional modeling of the heart provides a new means for the assessment of complex intracardiac anatomy. We expect this method to change current diagnostic approaches and facilitate preoperative planning.

Physical models aiding in complex congenital heart surgery.

PURPOSE: Our aim was to improve spatial imagination of complex congenital cardiac abnormalities for subsequent surgical intervention. DESCRIPTION: Magnetic resonance imaging data of a patient with complex congenital heart malformations was post-processed with software developed at our institution. The resulting virtual surface data sets were printed out three-dimensionally by rapid prototyping techniques. EVALUATION: We present the first patient operated on with intraoperative use of physical models representing the intracardiac volumes (RepliCast) or muscle and vessel walls (RepliCardio). The courses of the coronary arteries were visible on the RepliCast, whereas the RepliCardio showed intracardiac views a surgeon could never obtain intraoperatively in the relaxed heart. Other than on virtual reconstructions presented on computer screens, physical models vastly improve the spatial imagination and give precise information regarding localization and actual size of abnormal structures. The self-explanatory utility of these models shortened preparation and expedited orientation on the open heart. CONCLUSIONS: The additional spatial information provided by RepliCast and RepliCardio models may enable even high-risk correction procedures in patients with complex congenital heart disease.