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  • 1
    Keywords: Germany ; PERFUSION ; imaging ; VISUALIZATION ; TISSUE ; radiation ; kidney ; QUALITY ; renal ; animals ; CONTRAST ; INTERVENTION ; CONTRAST AGENT ; MR ; MAGNETIC-RESONANCE ; arteries ; TRACKING ; CELL CARCINOMA ; INTERVENTIONAL DEVICES ; ANGIOPLASTY ; ARTERY STENT PLACEMENT ; ENDOVASCULAR PROCEDURES ; ENHANCED MR-ANGIOGRAPHY ; FLUOROSCOPY ; magnetic resonance imaging,renal cancer,embolization,interventional radiology ; PIG MODEL
    Abstract: Rationale and Objectives: Magnetic resonance (MR)-guidance of endovascular interventions offers various advantages, including the absence of ionizing radiation, excellent soft tissue contrast, and multiplanar and functional imaging capabilities. The objective of this study was to assess the feasibility of MR-guided renal embolization using active catheter tracking with automatic slice positioning and intraarterial contrast-enhanced MR angiography (MRA).Materials and Methods: MR-guided embolization of 16 kidneys was attempted in 15 pigs using real-time tracking of active 5-Fr. catheters, Embolization was monitored by selective intraarterial projection MRA. Intraarterial three-dimensional (3D) MRA was used for the assessment of embolization results. Additional pathologic correlation was available in 2 animals. The image quality of intraarterial 3D contrast-enhanced-MRA was rated by an independent radiologist who was not involved in the animal experiments.Results: Active catheter tracking with automatic slice positioning allowed reliable catheter guidance and catheterization of the renal artery in all animals. Embolization was successful in all kidneys (11 left, 5 right), as verified by intraarterial 3D contrast-enhanced MRA (ce-MRA) and/or pathology. The image quality of intraarterial 3D ce-MRA was rated excellent in 10 animals, moderate in 4 animals, and poor in 1 animal.Conclusion: Renal embolization using active catheter tracking and intraarterial ce-MRA is feasible. Selective intraarterial ce-MRA allows the assessment of blood supply and organ perfusion before, during, and after therapeutic interventions, thereby complementing MR-guided endovascular interventions
    Type of Publication: Journal article published
    PubMed ID: 14734926
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  • 2
    Keywords: Germany ; MODEL ; CT ; segmentation ; ACCURACY ; RESOLUTION ; kidney ; pig ; MR ; MRI ; NUMBER ; arteries ; HEAD ; COMPUTED-TOMOGRAPHY ; MAGNETIC-RESONANCE ANGIOGRAPHY ; MR-ANGIOGRAPHY ; DIGITAL SUBTRACTION ANGIOGRAPHY ; ANGIOGRAPHY ; MR angiography ; LEVEL ; PHASE ; SIZE ; branching ; SPECIMENS ; CATHETER ; high-field MRI ; WILMS-TUMOR
    Abstract: Background: MRI at 3.0 T enables high-spatial resolution for renal MR angiography. Objective: Evaluation of an arterial tree model in animal kidney specimens with comparison of digital subtraction angiography (DSA) and high-field MRI to find out the maximum spatial resolution of intrarenal vessels. It was considered that objective quantitation of angiogram quality could be achieved. Materials and methods: A total of 27 pig kidney specimens were examined by MR angiography (flash 3D) using a 3.0-T scanner (TRIO; Siemens, Erlangen, Germany) with an eight-channel head coil and a voxel size of 0.9x0.9x1.1 mm in the early arterial phase after implantation of a 4F catheter in the renal artery. DSA (Integris, Philips, Best, The Netherlands) was performed immediately after the MRI. With the help of semiautomated segmentation, all vessels were marked for comparison of the vessel trees. The Wilcoxon rank test was used for statistical evaluation of vessel numbers and branching depths. Results: Objective comparison between DSA and MR angiography was achieved. High-field MR angiography had the ability to depict vessels up to the seventh branching on average. Significant differences in vessel delineation and counts were found from the fifth level of intrarenal branching onwards with DSA showing an advantage. Conclusion: High-field MRI has great potential in the detection of intrarenal arteries and is comparable to DSA in visualization of the central intrarenal vessel tree
    Type of Publication: Journal article published
    PubMed ID: 16896692
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  • 3
    Keywords: tumor ; Germany ; THERAPY ; ALGORITHM ; imaging ; segmentation ; SYSTEM ; TOOL ; VOLUME ; RESOLUTION ; PATIENT ; kidney ; CONTRAST ; REGION ; arteries ; BEAM ; tomography ; contrast media ; VESSELS ; ARCHITECTURE ; REPRESENTATION ; SOFTWARE TOOL ; radiology ; MATRIX ; THERAPIES ; HIGH-RESOLUTION ; SOFTWARE ; interaction ; antiangiogenic therapy ; RENAL-ARTERIES ; SCAN ; interventional radiology
    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.
    Type of Publication: Journal article published
    PubMed ID: 19846147
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  • 4
    Keywords: tumor ; MODEL ; PERFUSION ; DIFFERENTIATION ; kidney ; DIFFUSION ; MASSES ; CELL CARCINOMA ; COEFFICIENT ; IVIM ; ADC ; TRANSPLANTED KIDNEYS
    Abstract: Purpose: Usefulness of biexponentially fitted signal attenuation at different b-values for differentiating the histological characteristics of renal tumors. Materials and methods: A total of 26 patients with 28 renal masses (histologically proven: 20 clear cell renal cell carcinomas [ccRCC], three transitional cell carcinomas, two oncocytomas, and one papillary RCC) and 30 volunteers with healthy kidneys were examined at 1.5 Tesla using an echo-planar DWI sequence. Using the IVIM model, we calculated the perfusion fraction f and the diffusion coefficient D. Furthermore, the ADC was obtained. These tumor parameters were compared to healthy renal tissue nonparametrically, and a receiver operating characteristic (ROC) analysis was performed. Results: Healthy renal parenchyma showed higher ADC and D values (p 〈 0.001) than ccRCC (ADC 1.95 +/- 0.10 [SD] mu m(2)/ms, f 18.32 +/- 2.52%, and D 1.88 +/- 0.11 mu m(2)/ms versus ADC 1.45 +/- 0.38 mu m(2)/ms, f 18.59 +/- 6.16%, and D 1.34 +/- 0.38 mu m(2)/ms). When detecting malignancies the area under the curve for D was higher than for ADC. The f values for ccRCC were higher (p 〈 0.001) than for non-ccRCC (ADC 1.52 +/- 0.47 mu m(2)/ms, f 8.44 +/- 1.24%, and D 1.30 +/- 0.18 mu m(2)/ms). Both f and D correlated with ccRCC grading. Conclusion: IVIM imaging is able to provide reliable diffusion values in the human kidney and may enhance the accuracy of tumor diagnosis. The D value was the best parameter to distinguish renal tumors from healthy renal tissue. The f value is promising for determining the histological subgroups.
    Type of Publication: Journal article published
    PubMed ID: 22104090
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  • 5
    Keywords: GROWTH ; INVASION ; tumor ; carcinoma ; CELL ; Germany ; CT ; FOLLOW-UP ; imaging ; SUPPORT ; SYSTEM ; VISUALIZATION ; TUMORS ; computed tomography ; RESOLUTION ; SURGERY ; NUCLEAR-MEDICINE ; kidney ; MRI ; treatment ; magnetic resonance ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; PERFORMANCE ; tomography ; PROGNOSTIC-SIGNIFICANCE ; FAT ; COMPUTED-TOMOGRAPHY ; nuclear medicine ; MR imaging ; staging ; HELICAL CT ; radiology ; CELL CARCINOMA ; renal cell carcinoma ; INFILTRATION ; review ; TUMOR-GROWTH ; EXTENSION ; HIGH-RESOLUTION ; methods ; NUCLEAR ; COMPUTERIZED-TOMOGRAPHY ; multidetector CT ; abdomen ; CT high resolution ; MEDICINE ; imaging modalities ; RESONANCE ; 1997 TNM CLASSIFICATION ; FAT INVASION ; NEPHRON-SPARING SURGERY ; therapy planning ; TUMOR THROMBUS EXTENSION
    Abstract: Modern imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) allow high-resolution imaging of the abdomen. Modern scanners made high temporal as well as high spatial resolution available. Therapeutic approaches to the treatment of renal cell carcinoma have been improved over the recent years. Besides conventional and open laparoscopic tumor nephrectomy and nephron sparing, surgical approaches such as local tumor cryotherapy and radiofrequency ablation (RF) are ablative modalities and are used increasingly. Improved anesthesiological methods and new surgical approaches also allow curative treatment in extended tumors. Prerequisites for preoperative imaging modalities include visualization of the kidney tumor as well as its staging. Tumor-related infiltration of the renal pelvis or invasion of the perinephric fat and the renal hilus has to be excluded prior to nephron sparing surgery. In cases with extended tumors with infiltration of the inferior vena cava, it is necessary to visualize the exact extension of the tumor growth towards the right atrium in the vena cava. The radiologist should be informed about the diagnostic possibilities and limitations of the imaging modalities of CT and MRI in order to support the urologist in the planning and performance Of Surgical therapeutical approaches
    Type of Publication: Journal article published
    PubMed ID: 18004691
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  • 6
    Keywords: tumor ; carcinoma ; CELL ; Germany ; imaging ; SYSTEM ; SYSTEMS ; NEW-YORK ; SURGERY ; NUCLEAR-MEDICINE ; PATIENT ; COMPLEX ; COMPLEXES ; kidney ; arteries ; Jun ; COMPUTED-TOMOGRAPHY ; VESSELS ; nuclear medicine ; COMPLICATIONS ; DISSECTION ; radiology ; CELL CARCINOMA ; renal cell carcinoma ; NUCLEAR ; USA ; RARE ; RENAL-CELL CARCINOMAS ; Aorta ; MEDICINE ; embolization ; cardiovascular ; aortic dissection ; horseshoe kidney
    Abstract: Renal cell carcinoma arising in a horseshoe kidney is a rare entity. Preoperative tumor embolization can be performed to prevent massive bleeding complications during organ-preserving surgery. We report the first case of a patient with a tumor-bearing horseshoe-kidney in whom the preoperative embolization, already complex because of the abnormal vascular supply, was additionally complicated by an aortic dissection. An aberrant, horseshoe-kidney-supplying artery originated from the false dissection channel of the aorta, and thus had to be catheterized separately while the other tumor-supplying vessels could be reached via the true aortic lumen. After devascularization of the tumor, organ-preserving surgery was performed without bleeding complications
    Type of Publication: Journal article published
    PubMed ID: 17206388
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