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Objective: To describe a feasible surgical technique for patients with renal cell carcinoma associated with a supradiaphragmatic tumor thrombus that avoids cardiopulmonary bypass procedure., Materials and Methods: From 2004 to 2009, 4 patients with a right kidney tumor and tumor thrombus above the diaphragm (pT3c) underwent manual repositioning of the tumor thrombus out of the right atrium into the inferior vena cava on the beating heart. These patients were aged 65.8 years and had a body mass index of 25.5 kg/m(2). Median tumor size was 10.8 cm, and 3 patients had synchronous metastasis., Results: Manual repositioning of the tumor thrombus was safe and feasible in all patients. Mean operating time was 561 minutes (range, 302-613 minutes), and no perioperative death occurred. Auxiliary cardiopulmonary bypass procedure was applied in 1 patient to remove a preoperatively diagnosed pulmonary embolus. Three patients subsequently underwent systemic therapy for metastatic disease. Median survival was 16 months (range, 1.7-26 months)., Conclusion: Manual repositioning of a vena cava tumor thrombus without cardiopulmonary bypass is a safe and feasible approach. The risk of tumor thrombembolization seems to be low, and cardiopulmonary bypass can be avoided or at least reduced to a minimum time of intervention., (Copyright © 2013. Published by Elsevier Inc.)

Objective: The purpose of this study was to evaluate retrospectively the diagnostic value of MRI in the care of patients with suspected scrotal disorders., Materials and Methods: Testicle-containing scrotal compartments were evaluated by examiners blinded to all clinical information in an interdisciplinary consensus reading after MRI was performed with standardized T1-, T2-, and contrast-enhanced T1-weighted sequences. Image quality was evaluated on an increasing 4-point scale. Nineteen binary diagnostic parameters were allocated 1 point each if the diagnosis was correct and were summarized into categories in terms of localization, pattern, and characterization of the lesions. The results were compared with histopathologic results in 22 cases, with the surgical report in one case, and with a combined clinical reference comprising medical reports and scrotal ultrasound, follow-up, or laboratory results in 61 cases., Results: A total of 165 scrotal compartments containing testicles were analyzed in 84 patients; three patients underwent single-sided orchiectomy before MRI. The mean image quality score was 3.2 ± 0.7. Percentage of maximum diagnostic points, sensitivity, specificity, and positive and negative predictive values were 100% for localization of scrotal lesions and analysis of the pattern of testicular lesions. The values were 95%, 87%, 97%, 88%, and 97% for analysis of the pattern of nontesticular lesions and 95%, 92%, 97%, 91%, and 97% for classification of scrotal lesions., Conclusion: Scrotal lesions can be reliably detected, precisely localized, and characterized with MRI in everyday practice. The differential diagnosis was narrowed by use of MRI. This finding is of great clinical importance because more precise treatment strategies can be determined and surgical exploration or orchiectomy avoided by more patients.

Vascular endothelial growth factor seems to be a promoter of tumor progression for epithelial ovarian cancer. New drugs such as bevacizumab, either alone or in combination with metronomic chemotherapy, suppress tumor growth and have proved to be effective in various tumor types. We present a 60-year-old patient with heavily pretreated, recurrent epithelial ovarian cancer, who received bevacizumab (10 mg/m(2)) every 2 weeks in combination with metronomic administered low-dose cyclophosphamide (50 mg/day orally) after failing four explorative laparotomies and multiple chemotherapy regimes. At the time of writing, February 2011, she was being treated with this combination therapy for 24 months and the progression-free survival still continues. Treatment of advanced, refractory epithelial ovarian cancer with bevacizumab in combination with low-dose cyclophosphamide could be a very effective salvage treatment option in heavily pretreated patients.

Objective: To evaluate clinical, quality-of-life (QoL) and dynamic magnetic resonance imaging (dMRI) results in patients with pelvic organ prolapse (POP) preoperatively, and 4 and 12 weeks after anterior and/or posterior mesh repair., Study Design: Thirty-six patients (mean age 65 years) with symptomatic pelvic floor descent underwent mesh repair. The prolapse was quantified using the POP-Q system. Before surgery as well as 4 and 12 weeks after surgery, the pelvic organ positions were measured on dynamic magnetic resonance imaging during Valsalva manoeuvre in relation to the pubococcygeal and mid-pubic lines to assess surgery outcome. Patients also completed the P-QOL questionnaire to evaluate subjective changes at each visit., Results: Four and 12 weeks after surgery patients showed improvement of the POP on clinical examination and on dynamic MRI. The latter demonstrated high significance (p<0.001) especially in bladder and vaginal cuff/cervix positions during maximal straining. All quality-of-life domains and some symptom questions of the P-QOL questionnaire significantly improved (p<0.05) 12 weeks after surgery., Conclusion: Significant anatomical and quality-of-life improvement was demonstrated after anterior and/or posterior mesh repair for POP using dynamic MRI and the P-QOL questionnaire., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objective: To identify risk factors for relevant haemorrhage after open nephron-sparing surgery (NSS) for renal cell carcinoma, and to evaluate its clinical management., Patients and Methods: We evaluated bleeding complications after open NSS in 196 consecutive cases (193 patients) at our institution. The median (range) age of the patients was 64 (3-91) years and the tumour diameter was 2.7 (0.5-11.8) cm. Sex, age, body mass index, imperative vs elective indication, year of surgery, multifocality, tumour diameter and malignant vs benign pathology were tested exploratively and significant variables entered in a multivariate model. The clinical management of haemorrhage after NSS was analysed., Results: Bleeding required conservative (six), interventional (six) or surgical (three) therapy in 15 of the 196 cases (8%). Imperative indication (P= 0.043) and multifocality (P= 0.039) were independent risk factors in a multivariate model. Compared with superselective percutaneous transarterial embolization (TAE), surgery as a primary therapeutic option was more likely within 24 h after NSS (P= 0.012). Bleeding was finally controlled in all patients, while the kidney was preserved in 11 patients. There was only a minor decline of renal function at the 3-month follow-up., Conclusions: We identified multifocal tumours and imperative indication as risk factors for haemorrhage after NSS. The management was very successful, relying on TAE as an effective and safe treatment for bleeding after NSS. In rare cases of severe bleeding surgical exploration is unavoidable, with a lower chance of kidney preservation., (© 2010 THE AUTHORS. JOURNAL COMPILATION © 2010 BJU INTERNATIONAL.)

In this study, we investigated whether assessment of the tumor perfusion by dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) enables to estimate the morphologic grading of renal cell carcinomas. A total of 21 patients with suspected renal cell cancer were examined using a Gadobutrol-enhanced, dynamic saturation-recovery, turbo-fast, low-angle shot sequence. Tumor perfusion and the tissue-blood ratio within the entire tumor and the most highly vascularized part of the tumor were calculated according to the model of Miles. Immediately after examination, patients underwent surgery, and the results from imaging were compared with the morphological analysis of the histologic grading. Fourteen patients had G2 tumors, and seven patients had G3 tumors. Significantly higher perfusion values (p<0.05) were obtained in G3 tumors than in G2 tumors when the entire tumor area was considered (1.59+/-0.44(ml/g/min) vs. 1.08+/-0.38(ml/g/min)) or its most highly vascularized part (2.14+/-0.89(ml/g/min) vs. 1.40+/-0.49(ml/g/min)). By contrast, the tissue-blood ratios did not differ significantly between the two groups. In conclusion, unlike tissue-blood ratio, surrogate parameters of the tumor perfusion determined by DCE MRI seem to allow an estimation of the grading of renal cell carcinoma. However, further studies with high case numbers and including patients with G1 tumors are required to evaluate the full potential and clinical impact., (Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.)

Because of progress in imaging, the incidence of renal tumours, especially small lesions, has been rising over the last years. Therefore, imaging must be done to decide how to proceed further. But which is the most effective modality: computed tomography (CT) or magnetic resonance imaging (MRI)? From the technical point of view, the two alternatives appear to be nearly equal. Multidetector CT remains the reference standard for staging and lesion characterisation, whereas MRI is the method of choice for determining caval extension of a tumour thrombus and infiltration of the renal vein. If an accurate diagnosis cannot be specified, the remaining modality should be used complementarily.

The present study proposes a catheter system with an expandable coil etched on a polyimide foil. The catheter system combines the advantages of a small insertion diameter when the coil is rolled up in a protective carrier sheath with an increased signal-to-noise ratio (SNR) and penetration depth when the coil is pushed out. After imaging, the coil can be retracted into the sheath and folded back into the initial rolled-up configuration due to the tapered geometry of the carrier foil. The catheter system was tested on two healthy anesthetized pigs, including tracking and high-resolution intravascular imaging. To reduce artifacts in high-resolution images induced by catheter motion in the pulsatile blood flow, a motion-gating method was implemented that combines a flow-compensated two-dimensional fast low angle shot (FLASH) imaging sequence with the acquisition of projection data for retrospective gating. Using the projection data for motion detection, image SNR was increased by up to 500% over uncorrected images, and anatomic structures of 150 microm size could be differentiated in the aorta.

Using lacerated livers for liver transplantation (LTx) can add an option to the extended donor criteria. We present an LTx case using a severely lacerated liver and review of the literature for reported cases. We used a high-grade lacerated liver from a 19-yr-old brain-dead patient caused by traffic accident. The liver had grade IV and II lacerations in the right and left lobe, respectively. Lacerations were managed by sealants, stitching and perihepatic packing. The liver was transplanted to a 49-yr-old man suffering from hepatocellular carcinoma on hepatitis C-induced liver cirrhosis. The two-yr follow-up was uneventful. All published LTx cases using traumatized livers (n = 18) were analyzed. The liver injury ranged from subcapsular hematoma to deep ruptures. Most reported lacerations were in the right lobe, which were managed by digital compression, suturing, electrocautery, and perihepatic packing. The reported complications were primary non- (18%), or poor function, liver abscess, bilioma, and subhepatic hematoma each in one case (5.5%). Six-month graft and patient survival were 71% and 88%, respectively. With meticulous management lacerated livers can be transplanted successfully. Because of complexity of the management, procurement and transplantation should be done by experienced liver surgeons. These organs are marginal grafts and should be offered to selected patients.

High-frequency volumetric Power Doppler ultrasound (HF-VPDU) captures flow-dependent signals in blood vessels and can be used to assess antiangiogenic therapy effects in rodent tumors. However, the sensitivity is limited to vessels larger than capillaries. Contrast-enhanced HF-VPDU reveals all perfused vessels by assessing stimulated acoustic emissions from disintegrating microbubbles. Thus, we investigated whether flow-sensitive and contrast-enhanced HF-VPDU can depict different vessel fractions and assess their early response to antiangiogenic therapy. Mice with A431 tumors were scanned before and after administration of polybutylcyanoacrylate microbubbles by HF-VPDU. Animals received either antiangiogenic treatment (SU11248) or a control substance and were imaged repeatedly over 9 days. At each time point, tumors were removed for immunohistochemical analysis. During growth of untreated tumors, vascularization decreased correspondingly on flow-sensitive and contrast-enhanced scans. Treated tumors showed a significantly (P < 0.05) stronger decline in vascularization than controls, which was more pronounced in contrast-enhanced scans. Surprisingly, whereas vascularization remained low in contrast-enhanced scans, flow-sensitive ultrasound indicated a reincrease after day 6 with a higher vascularization than the controls at day 9. Histologic evaluation indicated that immature vessels degraded markedly on therapy, whereas large mature vessels on the tumor periphery were more therapy resistant and drew closer due to tumor shrinkage. In conclusion, contrast-enhanced HF-VPDU and flow-sensitive HF-VPDU are both capable of assessing the effects of antiangiogenic therapy. Because contrast-sensitive ultrasound is more sensitive for small immature vessels and flow-sensitive ultrasound mostly captures large vessels at the tumor periphery, the combination of both methods can provide evidence of vascular maturity in tumors.

Through the large numbers of ultrasound studies and computed tomography (CT) and magnetic resonance imaging (MRI) scans being done, many symptomless renal tumors are detected. The radiologist has a duty to differentiate renal lesions and diagnose malignant tumours in adults. Modern imaging modalities such as CT and MRI have the capability to further differentiate renal tumours by specific attributes. In this article, the most common renal tumours are presented, and typical findings are discussed.

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.

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.

Acute gastrointestinal bleeding in patients with liver cirrhosis is associated with a high mortality. Ileal varices and collaterals from ectopic vessels are extremely rare, encountered in less than 5% of the cirrhotic patients. The diagnosis is frequently delayed because the regular diagnostic methods such as gastroscopy or colonoscopy are unsuccessful in accurate the source of bleeding in the majority of the cases. We report an unusual case of massive and uncontrollable lower intestinal bleeding from ileal varices with right ovarian vein anastomosis in a 56 year-old female patient with liver cirrhosis and previous history of abdominal and pelvic surgery. The accurate angiographic and computed tomography diagnosis allowed fast decompression of the portal venous system using a transjugular intrahepatic portosystemic shunt.

Objective: The aim of this prospective study is to determine the diagnostic accuracy of multidetector-row computed tomography (CT) compared to histopathologic findings in tumor staging of renal cell carcinoma, with the focus on tumor stage, vein and artery infiltration, and infiltration of the renal pelvis., Materials and Methods: In a prospective study, a total of 76 consecutive patients with suspected renal cell carcinoma were preoperatively assessed for tumor staging using multidetector-row CT. Triphasic CT imaging (i.e., noncontrast, arterial, and parenchymal phase) was performed using multidetector-row CT with reconstructed slice thicknesses of 2 and 5 mm. Two blinded readers evaluated the CT scans independently; the results were then correlated with the histopathologic results., Results: A total of 56 renal cell carcinomas were proven on histopathology. Readers 1 and 2 reached a sensitivity of 1.0 and 1.0 and a specificity of 0.41 and 0.42 for arterial infiltration, a sensitivity of 1.0 and 0.86 and a specificity of 0.58 and 0.5 for venous infiltration, and a sensitivity of 0.75 and 1.0 and a specificity of 0.5 and 0.44 for infiltration of the renal pelvis. The correlation between both readers was 0.7 for all modalities., Conclusions: The multiplanar reconstruction capability of multidetector-row CT allowed good sensitivity in predicting arterial infiltration. The lowest specificity was reached in excluding infiltration of the renal pelvis. Despite its high temporal and spatial resolution, the capacity of multidetector CT to predict intrarenal infiltrations is still limited.

Hemobilia is a rare cause of acute upper gastrointestinal bleeding and is often associated with a history of hepatic or biliary tract injury, tumor growth, hepatic artery aneurysm, cholecystitis, or hepatic abscess. We report a case of a 76-year-old patient with massive hemobilia due to intrahepatic bleeding from the segment 8 hepatic artery without evidence of a true aneurysm, abscess, or metastatic disease 4 weeks following pylorus-preserving total pancreatectomy for pancreatic cancer. Gastroduodenoscopy suggested hemorrhage from the duodenojejunostomy but failed to achieve hemostasis, and the patient underwent exploratory laparotomy. It was realized intraoperatively that the bleeding originated from the intrahepatic biliary tract. Bleeding was controlled by blocking the right hepatic bile duct with a Fogarty catheter and subsequent transarterial embolization. Computed tomography did not reveal any local liver or vascular pathology. Retrospectively, the cause of delayed profuse hemobilia was most likely a traumatic intrahepatic pseudoaneurysm following endoscopic bile duct stenting 3 weeks before the pancreatectomy. The reported case is exceptional and of particular interest because of the absence of a typical history or cause of hemobilia, preoperative misleading diagnostic results in an altered anatomic situation, and the operative management to achieve bleeding control in this emergency setting.

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.

In this work active MR catheter tracking with automatic slice alignment was combined with an autocalibrated parallel imaging technique. Using an optimized generalized autocalibrating partially parallel acquisitions (GRAPPA) algorithm with an acceleration factor of 2, we were able to reduce the acquisition time per image by 34%. To accelerate real-time GRAPPA image reconstruction, the coil sensitivities were updated only after slice reorientation. For a 2D trueFISP acquisition (160 x 256 matrix, 80% phase matrix, half Fourier acquisition, TR = 3.7 ms, GRAPPA factor = 2) real-time image reconstruction was achieved with up to six imaging coils. In a single animal experiment the method was used to steer a catheter from the vena cava through the beating heart into the pulmonary vasculature at an image update rate of about five images per second. Under all slice orientations, parallel image reconstruction was accomplished with only minor image artifacts, and the increased temporal resolution provided a sharp delineation of intracardial structures, such as the papillary muscle., (Copyright 2006 Wiley-Liss, Inc.)

Purpose: To evaluate the influence of preoperative and palliative embolization of renal cell carcinomas on survival, intra- and post-operative procedures, and symptom control for palliative and preoperative indications., Materials and Methods: 56 patients who underwent renal cell carcinoma embolization from 1981 to 1999 were included in this retrospective study., Results: 24 women and 32 men were included (mean age 59.4 years). Complete follow-up data was available for 49 patients. 42 patients underwent preoperative embolization at different tumor stages (pT1: 1 patient, pT2: 6, pT3 a: 4, pT3 b: 19, pT3 c: 2, pT4: 5). 14 patients underwent palliative embolization (T1: 0 patients, T2: 5, T3: 4, T4: 4). Indications for preoperative embolization were bleeding of the renal tumor in 6 cases -- non-recurrent bleeding reported, flank pain in 4 patients -- 3 of 4 patients had no further symptoms, recurrent tumor embolization in 1 patient, and 2 patients who wanted to be treated without symptoms. The mean survival time of preoperative embolized patients was 3.1 +/- 5.11 years with a 5-year survival rate of 50 %. The mean survival time of palliative embolized patients was 0.67 +/- 0.76 years with initial metastases (n = 7) and 2.33 +/- 2.40 without metastases (n = 6)., Conclusion: Palliative embolization of renal cell carcinomas is a safe therapeutic method to treat advanced renal cell carcinomas allowing control of symptoms such as hematuria and flank pain in more than 90 % of our cases. Preoperative embolization yields a patient survival time comparable to that of patients at earlier tumor stages and is dependent on the metastases.

Percutaneous transcatheteral embolizations of primary and secondary bone tumors are important minimal invasive angiographic interventions of the skeletal system. In most of the cases embolization is performed for preoperative devascularization or as a palliative measure to treat tumor-associated pain or other tumor bulk symptoms. The transarterial embolization of primary and secondary tumors of the skeletal system has been developed to a safe and very effective method. Indications, techniques, results and complications of this minimal invasive interventional therapy for treatment of primary and secondary bone tumors are described and discussed and compared with the newer literature and our own results.

Angiosarcoma is a rare primary malignant neoplasm of the liver with a poor prognosis. Here, we report a case of a patient with a ruptured hepatic angiosarcoma which was treated by emergency catheter-directed embolization, followed by left-sided hemihepatectomy.

Renal transplantation is accepted as the preferred treatment for most cases of end-stage renal disease. Postoperative vascular complications include stenosis or thrombosis of the transplant renal artery or arteriovenous fistulas after biopsy. Impaired arterial perfusion of the transplant may be the leading cause for graft dysfunction or refractory hypertension. Therefore, non-invasive imaging modalities are required to detect and locate vascular complications with high accuracy. Doppler ultrasound is suited as a screening method for the detection of impaired graft perfusion. Magnetic resonance imaging (MRI) is used for an accurate diagnosis of vascular complications and to support decision for appropriate surgical or interventional treatment. Minimal invasive techniques like percutaneous transluminal angioplasty and stent placement have evolved as safe procedures with a high technical success rate reducing substantial morbidity. They can be considered as an alternative to surgical treatment of transplant renal artery stenosis (TRAS). Embolization of severe arteriovenous fistulas is the method of choice if the feeding artery can be occluded through a microcatheter. In selected cases, even catheter-guided fibrinolytic treatment of arterial thrombosis might be considered, if instantaneous surgery is considered a high-risk procedure. This article reviews the imaging features of common vascular complications after renal transplantation with focus on MRI. In addition, interventional radiological techniques are described for the treatment of TRAS, acute thrombotic occlusion, and arteriovenous fistulas.

This paper gives an overview of experience and success of percutaneous transhepatic interventions in malignant biliary obstruction. Even after exhaustion of surgical and endoscopic therapy options, the percutaneously inserted stents provide effective palliation. The palliative treatment of malignant jaundice using a stent is an established procedure in clinical practice, particularly whenever the endoscopic, transpapillary approach is not possible due to high obstructions or previous surgery. The technical success rate is very high (about 95-100%), and the complication rate is about 10-30%. Since the patency rate of stents is higher than that of plastic endoprostheses, their primary use is justified despite higher costs, provided the patients are adequately selected.

Flow measurements can be used to quantify blood flow during MR-guided intravascular interventional procedures. In this study, a fast flow measurement technique is proposed that quantifies flow velocities in the vicinity of a small RF coil attached to an intravascular catheter. Since the small RF coil receives signal from only a limited volume around the catheter, a spatially nonselective signal reception is employed. To enhance signal from flowing blood, and suppress unwanted signal contributions from static material, a slice-selective RF excitation is used. At a velocity sensitivity of 150 cm/s, a temporal resolution of 2 x TR = 10.2 ms can be achieved. The flow measurement is combined with an automatic slice positioning to facilitate measurements during interventional procedures. The influence of the catheter position in the blood vessel on the velocity measurement was analyzed in simulations. For blood vessels with laminar flow, the simulation showed a systematic deviation between catheter measurement and true flow between -15% and 80%. In four animal experiments, the catheter velocity measurement was compared with results from a conventional ECG-triggered 2D phase-contrast (PC) technique. The shapes of the velocity time curves in the abdominal aorta were nearly identical to the conventional measurements. A relative scaling factor of 0.69-1.19 was found between the catheter velocity measurement and the reference measurement, which could be partly explained by the simulation results., (Copyright 2004 Wiley-Liss, Inc.)

In active catheter tracking, small RF coils are attached to the catheter for localization. For interactive catheter steering at vessel branchings, it is necessary to visualize not only a single point near the catheter tip but also the entire shape and orientation of the catheter's distal end. Therefore, a 35-mm-long twisted-pair RF coil was added to a 5 French intravascular catheter with a single tip-tracking coil. With the use of small nonmagnetic electronic components at the catheter tip, and a special switching circuitry outside the catheter, the coil assembly could be operated in two different modes. During MRI, the tip-tracking coil was detuned so that the MR signal was received by the visualization coil only. During tracking, detuning was switched off and the MR signal was predominantly received by the more sensitive tracking coil. The catheter was used in combination with a MR pulse sequence with automatic slice positioning so that the current imaging slice was always placed at the position of the catheter tip. Phantom and animal experiments showed that the catheter tip is better visualized with the combined approach than with a tracking coil alone., (Copyright 2004 Wiley-Liss, Inc.)

Purpose: To implement and optimize a real-time pulse sequence and user interface to perform intravascular interventions using active catheter tracking., Materials and Methods: In magnetic resonance (MR)-guided interventions, small radio-frequency coils can be used to rapidly determine the device position (active tracking). In this work, active catheter tracking was combined with a dedicated real-time pulse sequence and user interface. The pulse sequence offered the imaging contrasts fast low angle shot (FLASH), true Fast imaging with steady state precession (TrueFISP), and projection MR digital subtraction angiography (MR-DSA), which could be selected by the radiologist from within the scanner room at any time during the intervention. Automatic slice positioning was added to the real-time pulse sequence so that the location of the tracking coils defined the image slice position and orientation. The technique was assessed in phantoms and animal experiments., Results: At a reaction time of 24 msec and a frame rate of three images per second, the movement of an active intravascular catheter could be monitored in the aorta and the renal arteries of a pig. With interactive contrast and orientation changes, the renal vasculature could be assessed by a fully MR-guided catheterization in less than 10 minutes., Conclusion: With carefully designed active catheters, a dedicated user interface, and an optimized pulse sequence intravascular interventions can successfully be performed by a single operator from within the MR scanner room., (Copyright 2004 Wiley-Liss, Inc.)

The aim of this study was to assess the value of contrast-enhanced three-dimensional MR angiography (CE 3D MRA) in the preoperative assessment of potential living renal donors, and to compare the accuracy for the depiction of the vascular anatomy using three different rendering algorithms. Twenty-three potential living renal donors were examined with CE 3D MRA (TE/TR=1.3 ms/3.7 ms, field of view 260-320x350 mm, 384-448x512 matrix, slab thickness 9.4 cm, 72 partitions, section thickness 1.3 mm, scan time 24 s, 0.1 mmol/kg body weight gadobenate dimeglumine). Magnetic resonance angiography data sets were processed with maximum intensity projection (MIP), volume rendering (VR), and shaded-surface display (SSD) algorithms. The image analysis was performed independently by three MR-experienced radiologists recording the number of renal arteries, the presence of early branching or vascular pathology. The combination of digital subtraction angiography (DSA) and intraoperative findings served as the gold standard for the image analysis. In total, 52 renal arteries were correspondingly observed in 23 patients at DSA and surgery. Other findings were 3 cases of early branching of the renal arteries, 4 cases of arterial stenosis and 1 case of bilateral fibromuscular dysplasia. With MRA source data all 52 renal arteries were correctly identified by all readers, compared with 51 (98.1%), 51-52 (98.1-100%) and 49-50 renal arteries (94.2-96.2%) with the MIP, VR and SSD projections, respectively. Similarly, the sensitivity, specificity and accuracy was highest with the MRA source data followed by MIP, VR and SSD. Time requirements were lowest for the MIP reconstructions and highest for the VR reconstructions. Contrast-enhanced 3D MRA is a reliable, non-invasive tool for the preoperative evaluation of potential living renal donors. Maximum intensity projection is favourable for the processing of 3D MRA data, as it has minimal time and computational requirements, while having similar or superior accuracy for the depiction of vessel anomalies or pathology compared with VR and SSD, respectively.

Magnetic resonance imaging (MRI) is ideally suited to monitor minimally invasive operations with catheters or needles, since it offers both a superior soft-tissue contrast and the possibility to perform functional tests. In the present study, small radio-frequency coils were attached to the instruments in order to localize the MR-invisible instruments. The implementation of active instrument tracking is described on the basis of the example of active catheter tracking. In this case, the current position information of the instrument is used to automatically position the MRI slice at the catheter location. In combination with a user interface, the interventional radiologist is offered the possibility to perform vascular interventions from within the MR scanner room. At image update rates of approximately 3 Hz, tracking and placement of catheters in vascular structures are possible with interactive switching of slice orientation and image contrast. In an animal model, the technique was successfully used to selectively visualize the abdominal vessels and their branches under MRI guidance.

Xanthogranulomatous pyelonephritis (XGP) is a rare chronic infection of the kidney. In this overview article we reevaluated the magnetic resonance imaging (MRI) findings of our four patients with histologically proven XGP and correlated them with the CT and ultrasound findings described in the literature. Additionally, we give an overview of the pathogenesis and epidemiology. The following criteria were found in MRI: hydronephrosis and/or urethral stricture, vesicoureteral reflux or neurogenic bladder depletion disorders, and calculus as the origin of urinary obstruction. Moreover, in contrast to normal pyelonephritis, XGP is accompanied by fatty deposits in the peripelvic parenchyma, which demonstrate contrast enhancement and form the typical so-called bear paw sign. As XGP is often accompanied by severe kidney failure, contrast-enhanced CT with nephrotoxic contrast agents should be avoided and MRI should be performed instead. Because of proven reduced nephrotoxicity of gadolinium chelates, MRI seems to be superior to CT in patients with suspected XGP. Essential for the correct diagnosis is consideration of the complete medical history including recurrent pyelonephritis to avoid malpractice.

Objective: For nephron sparing surgery of renal cell carcinoma knowledge of the intrarenal extension of the tumor and infiltration of the renal pelvis, the intrarenal vessels and the perinephric fat is essential. This question is much more difficult to answer compared to the description of staging parameters. Aim of this study is to evaluate the value of multi-slice CT in planning of nephron sparing surgery., Material and Methods: In a prospective study 46 patients with suspected renal cell carcinoma underwent a triphasic multi-slice CT (unenhanced, delay 30 s and 120 s). A reconstructed slice thickness of 2 mm in the arterial and parenchymal phase was used to create volume rendered 3D-reconstructions. Based on the source data and multiplanar reconstructed images the extent of the renal cell carcinoma was assessed in terms of size, hilar infiltration, arterial and venous invasions, capsula infiltration and perirenal growth. The results of two blinded readers were correlated with histopathological staging and intraoperative findings., Results: 36 carcinomas were evaluated histopathologically. 10 patients showed no renal cell carcinoma histopathologically. Multi-slice CT allowed us to diagnose the localization and size of all tumors correctly. Infiltration into perinephric fat was correctly excluded in 24/30 and 8/30 cases. Infiltration of the renal pelvis could be excluded in 17/24 and 12/24 cases. The state of venous infiltration could be correctly diagnosed in 29/30 and 27 /30 carcinomas., Conclusion: Despite of the high temporal and spatial resolution of multi-slice CT, which allows the delineation of intrarenal arteries as well as renal hilus and the veins, the evaluation of tumor infiltration into the renal hilus, the intrarenal vessels and the perinephric fat remains a diagnostic problem. For planning of nephron sparing surgery, a knowledge of the infiltration in these structures is essential.

Nephron-sparing surgery of renal cell carcinoma in the 1970's and 1980's in patients with bilateral renal tumors or reduced renal function (imperative indication) has shown a very low risk of recurrent cancer. Today, nephron-sparing surgery in renal cell carcinoma is considered in an increasing number of patients with expected sufficient renal function after nephrectomy (elective indication). Resection technique, the use of Tabotamp(R) to reduce bleeding, and pseudotumors do complicate the interpretation of the images. It has been not yet defined which diagnostic modality is best suited for follow-up after renal cell carcinoma resection. Follow-up protocols in different institutions show a wide variety. The follow-up of patients after nephron-sparing surgery is performed by annual sonography or MRI every three months. Up to now, CT and ultrasound are the standard methods. MRI with its multiplanar imaging and improved soft tissue contrast seems to have an equal diagnostic value. Additionally, MRI seems to be suited for patients with reduced renal function. The aim of this paper is to give guidelines for the radiologist to understand the different surgical procedures and to evaluate the postoperative findings. Different imaging modalities in the follow-up of patients and special radiological phenomena are discussed.

To evaluate whether MRI is usefull in staging renal cell carcinomas with caval thrombus the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in staging renal tumors with caval thrombus were preoperatively examined. Tumor staging by CT and MR imaging were correlated with histopathological tumor stadium. In MRI 4 out of 7 thrombi were correctly diagnosed with high accuracy, in CT none. In advanced renal carcinoma MRI with Gadolinium was superior to CT imaging, especially in diagnosing tumor thrombus. Consequently the extent of tumor thrombus may be assessed by MRI which therefore may replace conventional cavography.

Bile duct cysts are rare abnormalities of the biliary tract. Surgical therapy has been recommended because of possible complications such as cholestasis with jaundice and the risk of bile duct carcinoma. Accurate preoperative radiological imaging is available for surgical planning. In addition to direct imaging of the biliary system in ERCP, high-resolution axial computerized imaging techniques are necessary. The use of MRCP is becoming more frequent in diagnostic imaging of the biliary tract. Similar to the diagnosis of pancreatic tumors with hydro-spiral CT technique, we demonstrate the benefits of hydro-CT in imaging of a distal choledochal cyst, the problems of differential diagnosis and the classification in the generally accepted Todani system in a case in which accurate clarification with MRCP and ERCP was not possible.

Today the relevance of renal tumor embolization is not determined only by the technical and clinical success of the method. Progress in diagnosis of early stages of renal carcinomas as well as the improvement of both surgical techniques and anesthetic procedures have lead to a change in the selection of patients for embolization. Preoperative embolization of advanced renal cell carcinomas with tumor thrombus into the vena cava or of T4 tumors is now an established clinical procedure. The complete occlusion of the vascular bed of the tumors leads to a considerable reduction in intraoperative blood loss and to simplification of the surgical preparation. By using Ethibloc for embolization, palliation of a hemorrhage or of tumor-related pain in inoperable patients is usually successful. Although local control of the tumor disease, including complete tumor ablation, is achieved by embolization, the median survival rate of our palliatively embolized patients is only 3.5 months. This short life expectancy in the group of inoperable patients has to be acknowledged individually in patients considered for palliative embolization who are free of symptoms related the tumor.

For imaging of renal pathology a broad spectrum of radiologic diagnostic procedures are available which are, sometimes and particularly more recently, competing among each other in their diagnostic yield and relevance. For tumorous lesions ultrasound, computed tomography and magnetic resonance imaging are performed predominantly. Angiography is no longer required with the exception of highly selected cases and in some specific preoperative workup requirements. Until recently, catheter based digital subtraction angiography has been considered as gold standard. However, non-invasive techniques such as CT-angiography and MR-angiography are evolving parallel to their quantum leap of resolutions and readiness to use. Nevertheless, well accepted criteria for quality assessement of these new modalities are still lacking. More comparison studies are urgently warranted. Despite the availability of ultrashort pulse sequences applying the T1 relaxation reduction effect of gadolinium enhanced MR techniques overestimation of renal artery stenosis still poses a substantial problem. Renal intervention implies a variety of procedures such as plain angioplasty, stent placement, embolization of traumatic and both benign and malignant tumors. These methods have emerged over the last two decades from a more experimental nature to a fully accepted treatment option. When renal artery angioplasty is embedded in an aggressive approach including stenting as an adjunct for more complex cases, renal ostial lesions and a well organized follow-up regimen its therapeutic potential for treatment of renal insufficiency, malignant hypertension, for organ preservation bears a very high potential. Provided adequat periinterventional drug regimen restenosis rates may be as low as 10%. In highly selected cases capillary embolization might be used as an alternative to nephrectomy with a similar clinical outcome. Particularly the development of superselective small caliber embolization catheters parallel to further refinement of embolization material has aided to use superselective occlusion techniques in benign vascular lesions and renal trauma.

Diagnostic imaging after renal transplantation is of high importance in the differential diagnosis of peri- and postoperative complications. Sonography with color duplex imaging is the method of choice in the diagnosis of acute transplant rejection. MRI is an additional method in the diagnosis of transplant dysfunction especially in diagnosis of perirenal fluid collections. MR angiography and MR urography are noninvasive diagnostic modalities with the potential to replace angiography and pyelography. Angiography, complemented by carbon dioxide angiography, still is the gold standard in the diagnosis of transplant artery stenosis.

Purpose: Evaluation by hydro-CT in diagnosing and staging of primary non-Hodgkin lymphoma of the stomach (MALT)., Material and Methods: 15 patients with MALT lymphoma underwent imaging by hydro-CT (helical CT scanning optimised for parenchymal and vessel contrast with distension of the gastric wall by water). The CT scans were evaluated for the site, morphology, extent and contrast enhancement of gastric lymphoma; in addition, the number and location of abdominal lymph nodes were examined. The results of CT imaging were compared with the findings at endoscopy + biopsy and endosonography and in case of gastrectomy also with the histopathological results., Results: All lymphomas were correctly diagnosed and were mostly located in the distal parts of the stomach. MALT lymphoma typically grew submucosally, infiltration of the mucosa was rare. Most tumours showed marked contrast enhancement of the mucosa and poor enhancement of the submucosa. Hydro-CT and endosonography had similar accuracies in respect of staging of compartment I and II lymph nodes. Staging of distant nodal groups was more accurate by hydro-CT., Conclusion: Hydro-CT is non-invasive and may be used for diagnosis and staging of primary gastric lymphoma with a typical morphology of gastric lymphoma. Hydro-CT may be regarded as complementary to endosonography and is well suited for the initial diagnosis of gastric lymphoma as well as for the diagnosis of recurrent tumour.

Purpose: To evaluate the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in staging renal carcinoma., Material and Methods: 33 renal carcinomas were preoperatively examined for tumour staging by CT and MR imaging and correlated with histopathological staging. CT imaging was performed at first as a non-contrast scan. Finally incremental images (10 mm) after intravenous contrast injection were obtained. In MR imaging we performed a transversal T1-weighted GE sequence (112/5) with and without GDTPA, a transversal fat-suppressed double-echo sequence (3900/22/90), a coronal T1-weighted GE sequence with and without GDTPA and a coronal T2-weighted TSE sequence (2800/128). In addition, dynamic T1-weighted GE imaging after GDTPA injection as well as TOF angiography in coronal direction were performed. Finally CT and MRI findings were correlated with surgical and histopathological staging results., Results: CT and MRI staging was correct in 27 and 28 of 33 tumours. Sensitivity and specificity for tumour stage T3b to T4 was for MRI and CT 88.9% and 95.8%. With MRI 4 out of 7 thrombi were correctly diagnosed with high accuracy, but via CT none., Conclusion: In early stage renal carcinoma CT and MR imaging yielded similar staging accuracies. In advanced renal carcinoma MRI was superior to CT imaging, especially in diagnosing tumour thrombus. Consequently the extent of tumour thrombus may be assessed by MRI which may therefore replace conventional cavography.