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Background Management of abdominal branches associated with Stanford type B aortic dissection is controversial without definite criteria for therapy after thoracic endovascular aortic repair (TEVAR). This is in part due to lack of data on natural history related to branch vessels and their relationship with the dissection flap, true lumen, and false lumen. Purpose To investigate the natural history of abdominal branches after TEVAR for type B aortic dissection and the relationship between renal artery anatomy and renal volume as a surrogate measure of perfusion. Materials and Methods This study included patients who underwent TEVAR for complicated type B dissection from January 2012 to March 2017 at 20 centers. Abdominal aortic branches were classified with following features: patency, branch vessel origin, and presence of extension of the aortic dissection into a branch (pattern 1, supplied by the true lumen without branch dissection; pattern 2, supplied by the true lumen with branch dissection, etc). The branch artery patterns before TEVAR were compared with those of the last follow-up CT (mean interval, 19.7 months) for spontaneous healing. Patients with one kidney supplied by pattern 1 and the other kidney by a different pattern were identified, and kidney volumes over the course were compared by using a simple linear regression model. Results Two hundred nine patients (mean age ± standard deviation, 66 years ± 13; 165 men and 44 women; median follow-up, 18 months) were included. Four hundred fifty-nine abdominal branches at the last follow-up were evaluable. Spontaneous healing of the dissected branch occurred in 63% (64 of 102) of pattern 2 branches. Regarding the other patterns, 6.5% (six of 93) of branches achieved spontaneous healing. In 79 patients, renal volumes decreased in kidneys with pattern 2 branches with more than 50% stenosis and branches supplied by the aortic false lumen (patterns 3 and 4) compared with contralateral kidneys supplied by pattern 1 (pattern 2 vs pattern 1: -16% ± 16 vs 0.10% ± 11, P = .002; patterns 3 and 4 vs pattern 1: -13% ± 14 vs 8.5% ± 14, P = .004). Conclusion Spontaneous healing occurs more frequently in dissected branches arising from the true lumen than in other branch patterns. Renal artery branches supplied by the aortic false lumen or a persistently dissected artery with greater than 50% stenosis are associated with significantly greater kidney volume loss. © RSNA, 2019 Online supplemental material is available for this article.

Purpose To develop and demonstrate in vitro and in vivo a single interventional magnetic resonance (MR)-active device that integrates the functions of precise identification of a tissue site with the delivery of radiofrequency (RF) energy for ablation, high-spatial-resolution thermal mapping to monitor thermal dose, and quantitative MR imaging relaxometry to document ablation-induced tissue changes for characterizing ablated tissue. Materials and Methods All animal studies were approved by the institutional animal care and use committee. A loopless MR imaging antenna composed of a tuned microcable either 0.8 or 2.2 mm in diameter with an extended central conductor was switched between a 3-T MR imaging unit and an RF power source to monitor and perform RF ablation in bovine muscle and human artery samples in vitro and in rabbits in vivo. High-spatial-resolution (250-300-μm) proton resonance frequency shift MR thermometry was interleaved with ablations. Quantitative spin-lattice (T1) and spin-spin (T2) relaxation time MR imaging mapping was performed before and after ablation. These maps were compared with findings from gross tissue examination of the region of ablated tissue after MR imaging. Results High-spatial-resolution MR imaging afforded temperature mapping in less than 8 seconds for monitoring ablation temperatures in excess of 85°C delivered by the same device. This produced irreversible thermal injury and necrosis. Quantitative MR imaging relaxation time maps demonstrated up to a twofold variation in mean regional T1 and T2 after ablation versus before ablation. Conclusion A simple, integrated, minimally invasive interventional probe that provides image-guided therapy delivery, thermal mapping of dose, and detection of ablation-associated MR imaging parametric changes was developed and demonstrated. With this single-device approach, coupling-related safety concerns associated with multiple conductor approaches were avoided.

Purpose To develop a computed tomographic (CT) angiographic postprocessing protocol with two- and three-dimensional measurements for follow-up of patients who underwent endovascular aortic repair. Materials and Methods This HIPAA-compliant institutional review board-approved retrospective study included 159 patients (129 men, 30 women; mean age ± standard deviation, 74.9 years ± 8.2) who underwent 824 CT examinations (median of five examinations per patient; range, two to 14) with unenhanced and arterial -phase imaging performed between September 2004 and March 2015. The largest diameter on the axial plane; coronal, sagittal, and maximal diameter perpendicular to the reconstructed centerline; volume of the abdominal aortic aneurysm sac; and volume from the lowest renal artery to the aortic bifurcation and to the common iliac artery bifurcation were measured. Endoleaks on contrast material-enhanced images were considered the reference standard, and the predictive value of diameter and volume changes was analyzed. Intraclass correlation was used to compare diameters and volumes. Results All diameters and volumes showed excellent correlation (intraclass coefficient, 0.95 and 0.94, respectively). Average interobserver difference for diameters and volumes was 2%-3% and 4%-12%, respectively. Endoleaks were observed in 80 (50%) of 159 patients (59 [74%] at initial and 21 [26%] at later CT angiography). New endo-leaks were associated with increased aneurysm size measured as the largest diameter on the axial plane (P = .04) and perpendicular to the centerline (P = .01), and volume was measured from the lowest renal artery to the aortic bifurcation (P = .03) and to the common iliac artery bifurcation (P = .01). With a 5% size threshold, sensitivity and specificity for detection of endoleaks was optimal for centerline diameter (64.3% and 81.7%, respectively) and volume from the lowest renal artery to the common iliac artery bifurcation (57.1% and 63.5%). Conclusion The maximal diameter and volume of an abdominal aortic aneurysm sac can be used for temporal monitoring after endovascular aortic repair, with excellent correlation and interobserver agreement. An increase in the centerline diameter and volume from the lowest renal artery to the iliac bifurcation were the most sensitive criteria for detecting endoleaks. © RSNA, 2017 Online supplemental material is available for this article.

To compare noninvasive transstenotic pressure gradient (TSPG) measurements derived from high-spatial- and temporal-resolution four-dimensional magnetic resonance (MR) flow measurements with invasive measurements obtained from endovascular pressure wires with digital subtraction angiographic guidance.After Animal Care and Use Committee approval, bilateral renal artery stenosis (RAS) was created surgically in 12 swine. Respiratory-gated phase-contrast vastly undersampled isotropic projection (VIPR) MR angiography of the renal arteries was performed with a 1.5-T clinical MR system (repetition time, 11.4 msec; echo time [first echo], 3.7 msec; 18,000 projection angles; imaging volume, 260 × 260 × 200 mm; acquired isotropic spatial resolution, 1.0 × 1.0 × 1.0 mm; velocity encoding, 150 cm/sec). Velocities measured with phase-contrast VIPR were used to calculate TSPGs by using Navier-Stokes equations. These were compared with endovascular pressure measurements (mean and peak) performed by using fluoroscopic guidance with regression analysis.In 19 renal arteries with an average stenosis of 62% (range, 0%-87%), there was excellent correlation between the noninvasive TSPG measurement with phase-contrast VIPR and invasive TSPG measurement for mean TSPG (R² = 95.4%) and strong correlation between noninvasive TSPG and invasive TSPG for the peak TSPG measures (R² = 82.6%). The phase-contrast VIPR-derived TSPG measures were slightly lower than the endovascular measurements. In four arteries with severe stenoses and one occlusion (mean, 86%; range, 75%-100%), the residual lumen within the stenosis was too small to determine TSPG with phase-contrast VIPR.The unenhanced MR angiographic technique with phase-contrast VIPR allows for accurate noninvasive assessment of hemodynamic significance in a porcine model of RAS with highly accurate TSPG measurements.

Phase-contrast renal MR angiography with isotropic high spatial resolution (1.25 mm3) is feasible in a reasonable imaging time (10 minutes) by using three-dimensional radial undersampling (phase-contrast vastly undersampled isotropic projection reconstruction).

To prospectively assess the diagnostic accuracy of 64-detector computed tomographic (CT) renal artery (RA) angiography for the evaluation of RA in-stent restenosis (ISR) by using selective catheter RA angiography as the reference standard.Institutional review board approval and written informed consent were obtained. Eighty-six patients (46 men, 40 women; mean age +/- standard deviation, 71 years +/- 9) with 95 RA stents were examined with 64-detector CT RA angiography by experienced radiologists 1 day before selective catheter RA angiography was performed by experienced cardiologists. Each group was blinded to the results of the other imaging method. For image reconstruction, a standard (B25f) and an edge-enhancing (B46f) kernel were chosen. An ISR of more than 50% was considered as hemodynamically significant. Sensitivity, specificity, and positive and negative predictive values for the detection of ISR by using CT RA angiography were calculated.At CT RA angiography, 93 (98%) of 95 stents were assessable for diagnosis. Two stents could not be evaluated owing to hardening artifacts affected by vessel calcifications. All nine cases of significant ISR seen at selective catheter RA angiography were correctly diagnosed by using CT RA angiography, giving a sensitivity of 100% and a negative predictive value of 100%. One case of nonsignificant ISR seen at selective catheter RA angiography was interpreted as significant by using CT RA angiography, giving a specificity of 99% and a positive predictive value of 90%. In four of 78 patients without ISR seen at selective catheter RA angiography, CT RA angiography showed nonsignificant ISR, giving a specificity of 95% and a positive predictive value of 56%.Sixty-four-detector CT RA angiography can provide an excellent noninvasive technique to help detect and evaluate ISR within the RA stents used in our study.

To assess the degree of renal necrosis and the leakage of absolute ethanol by using two methods: transcatheter renal artery embolization (TAE) and TAE performed with a closed renal circuit (CRC) (TAE/CRC), both performed by using ethanol and iodized oil, in a pig model.All animal experiments were conducted in accordance with our university guidelines for animal care and experimentation. Fourteen pigs were classified in two groups: standard TAE and TAE/CRC groups. In the TAE/CRC group, the renal artery and vein were occluded with balloon catheters; in the TAE group, only the renal artery was occluded. An emulsion of absolute ethanol (0.5 mL per kilogram of body weight) and iodized oil (emulsion ratio, 4:1) was injected in the renal artery in both groups. In the TAE/CRC group, we aspirated the blood containing the emulsion via the renal vein during arterial infusion. We measured the ethanol concentrations of the systemic circulation. Four days after embolization, the kidneys in both groups were removed and histopathologic examination was performed and results were compared.The mean systemic ethanol concentration was less than 0.1 mg/mL in the TAE/CRC group and 0.28 mg/mL +/- 0.15 (standard deviation) in the TAE group (P.002). In both groups, about 90% of the kidney was shown histopathologically to have undergone coagulation necrosis (no significant difference). The frequency of venous thrombus formation was significantly lower (P = .009) in the TAE/CRC group.TAE/CRC dramatically reduces ethanol leakage to the systemic circulation without a decrease in embolization effect in the normal swine kidney, and it also reduces the likelihood of venous thrombus formation.

The purpose of this study was to prospectively evaluate the diagnostic performance of contrast material-enhanced magnetic resonance (MR) angiography performed at 3 T for assessment of renal artery stenosis (RAS) by using parallel acquisition techniques with high acceleration factors and with digital subtraction angiography (DSA) as the reference standard. The study was institutional review board approved, and written informed consent was obtained from all patients. Twenty-nine patients (18 men, 11 women; mean age, 57.1 years +/- 14.3 [standard deviation]) suspected of having RAS underwent MR angiography. Images were evaluated qualitatively and quantitatively. The interobserver variability, sensitivity, specificity, and positive and negative predictive values of 3-T MR angiography, as compared with DSA (performed in 15 patients), were calculated. All examinations yielded good or excellent image quality. The sensitivity and specificity of MR angiography in grading significant (75%) stenosis were 94% and 96%, respectively. Owing to its high sensitivity, contrast-enhanced 3-T MR angiography can be used reliably to exclude RAS and can serve as a useful screening method in the diagnostic work-up of patients with arterial hypertension.

To prospectively evaluate the hypothesis that retrospectively electrocardiographically gated phase contrast with vastly undersampled isotropic projection reconstruction (VIPR) magnetic resonance (MR) angiography data sets can be used to measure transstenotic pressure gradients (TSPGs) in vivo.TSPGs were calculated by using phase-contrast VIPR MR angiography data sets; measurements obtained with a pair of endovascular pressure-sensing guidewires served as a reference standard. With institutional animal care and use committee approval, 12 swine underwent surgical creation of stenoses at the left common carotid, right renal, and left external iliac arteries. The percentage stenosis and reference diameter of the lesions were calculated from conventional digital subtraction angiograms. A pair of 0.014-inch pressure-sensing guidewires was placed in tandem; sensors 1 cm distal and 1 cm proximal to the lesions measured the mean TSPG. Phase-contrast VIPR phase difference images were analyzed with an iterative technique based on the Navier-Stokes equations to determine the mean TSPG. Pearson product correlation was calculated, and Bland-Altman plots were generated to determine the degree of agreement between the two methods.Twenty-one lesions (12 carotid, nine iliac; mean percentage stenosis, 52.4%; range, 29.8%-64.9%; mean reference diameter, 3.4 mm; range, 2.4-5.6 mm) were analyzed. For carotid and iliac lesions, phase-contrast VIPR and guidewire TSPG measurements were highly correlated (r = 0.952, P.001). Bland-Altman plots (bias, 0.86 mm Hg; limits of agreement: -6.17 to 7.88 mm Hg) showed good agreement. Measurements in renal lesions (n = 9) were poorly correlated (r = -0.081, P = .835) and were excluded because of image degradation secondary to respiratory motion.Phase-contrast MR angiography with VIPR enables reliable measurements of TSPG in carotid and iliac lesions that are comparable to those obtained with endovascular pressure-sensing guidewires. However, further work to compensate for respiratory motion is required to extend this technique to the renal arteries.

To prospectively compare the image quality, sensitivity, and specificity of three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography accelerated by parallel acquisition (ie, fast MR angiography) with MR angiography not accelerated by parallel acquisition (ie, conventional MR angiography) for assessment of aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the reference standard.The study was approved by the institutional review board; informed consent was obtained from all patients. Forty consecutive patients (33 men, seven women; mean age, 63 years) suspected of having aortoiliac and renal arterial stenoses and thus examined with DSA underwent both fast (mean imaging time, 17 seconds) and conventional (mean imaging time, 29 seconds) MR angiography. The arterial tree was divided into segments for image analysis. Two readers independently evaluated all MR angiograms for image quality, presence of arterial stenosis, and renal arterial variants. Image quality, sensitivity, and specificity were analyzed on per-patient and per-segment bases for multiple comparisons (with Bonferroni correction) and for dependencies between segments (with patient as the primary sample unit). Interobserver agreement was evaluated by using kappa statistics.Overall, the image quality with fast MR angiography was significantly better (P=.001) than that with conventional MR angiography. At per-segment analysis, the image quality of fast MR angiograms of the distal renal artery tended to be better than that of conventional MR angiograms of these vessels. Differences in sensitivity for the detection of arterial stenosis between the two MR angiography techniques were not significant for either reader. Interobserver agreement in the detection of variant renal artery anatomy was excellent with both conventional and fast MR angiography (kappa=1.00).Fast MR angiography and conventional MR angiography do not differ significantly in terms of arterial stenosis grading or renal arterial variant detection.

To prospectively compare three-dimensional (3D) contrast material-enhanced abdominal magnetic resonance (MR) angiography at 1.5 and 3.0 T intraindividually in healthy volunteers.After institutional review board approval and informed consent were obtained, 15 healthy male volunteers (age range, 24-41 years) underwent one abdominal 3D contrast-enhanced MR angiographic examination each at 1.5 and 3.0 T in random order. Fast 3D gradient-echo sequence with parallel imaging acceleration factor of three was used for MR angiography; acquired spatial resolutions were 1x0.8x1 mm3 (imaging time, 19 seconds) at 1.5 T and 0.9x0.8x0.9 mm3 (imaging time, 18 seconds) at 3.0 T. With the latter, volume of the 3D slab was 8% larger. At 1.5 T, 20-mL bolus of gadobenate dimeglumine was delivered at 2 mL/sec; at 3.0 T, 15-mL bolus was delivered at 2.5 mL/sec. Two blinded radiologists rated image quality of aorta and proximal renal arteries in consensus with five-point scale (4=very good, 0=nondiagnostic) according to sequence and in direct intraindividual comparison. Visibility of proximal and segmental renal arteries was rated with three-point scale (3=completely visible, 1=nonvisible). Signal-to-noise ratio (SNR) was determined with phantoms. For statistical analysis of the SNRs, t tests were used.All MR angiographic measurements were diagnostic. Median score for image quality at both field strengths was 4. Depiction of proximal renal arteries was rated 3 at both field strengths. The visibility of the distal renal arteries was better at 3.0 T (median score, 3) than at 1.5 T (median score, 2). With direct comparison, 3.0-T MR angiography was better in 14 of 15 cases; no field strength was preferred in the other case. Mean SNR was significantly (P.001) higher at 3.0 T (17.8+/-0.09 [standard deviation]) than at 1.5 T (11.9+/-0.10).MR angiography at 3.0 T provided better vessel visibility and SNR than did that at 1.5 T, although voxel size and imaging time were reduced.

The aim of this study was to prospectively assess the accuracy of three-dimensional magnetic resonance (MR) angiography for evaluation of stenosis in the peripheral arterial system with a continuous moving table technique, with conventional MR angiography as reference. This study was approved by the local institutional review board; informed consent was obtained. Five healthy male volunteers (mean age, 27 years; range, 24-35 years) and four men and one woman (mean age, 63 years; range, 46-78 years) with peripheral arterial occlusive disease were examined. Images obtained with both techniques showed excellent concordance (Cohen kappa = 0.75). Images obtained with a conventional protocol had higher quality compared with those obtained with the continuous technique (mean, 1.07 +/- 0.25 [standard deviation] vs 1.58 +/- 0.6; P.05); small vessels appeared sharper on them. For detection of significant stenosis and occlusion, accuracy, sensitivity, and specificity of the continuous technique were 92.8%, 100%, and 89.2%, respectively.

To use a decision analytic model to determine the cost-effectiveness of performing diagnostic digital subtraction angiography (DSA), computed tomographic (CT) angiography, or magnetic resonance (MR) angiography or proceeding immediately to tentative percutaneous revascularization in patients suspected of having renovascular hypertension.With use of a Markov-Monte Carlo decision model, cost-effectiveness analysis was performed from a societal perspective. Data were derived from the Renal Artery Diagnostic Imaging Study in Hypertension and from published literature. The base-case analyses were used to evaluate a 50-year-old patient with a diastolic blood pressure higher than 95 mm Hg and one or more clinical clues suggestive of renovascular hypertension. Outcome measures were quality-adjusted life-year (QALY), lifetime costs, and incremental cost-effectiveness.For a 50-year-old male patient, immediate tentative revascularization was the least costly (euro54 415) and most effective (12.265 QALYs) strategy. For the other strategies, costs and QALYs, respectively, were euro55 570 and 12.195 for DSA, euro55 191 and 12.163 for CT angiography, and euro56 890 and 12.088 for MR angiography. For a 50-year-old female patient, costs and QALYs, respectively, were euro66 731 and 13.731 for MR angiography, euro63 970 and 13.749 for CT angiography, and euro63 079 and 13.902 for DSA. Immediate tentative revascularization yielded more QALYs (13.937) and was more costly (euro63 329) than DSA. The incremental cost-effectiveness ratio was euro7143 per QALY. As the prior probability increased, use of a more invasive diagnostic imaging strategy became justified. Also, the sensitivities of CT angiography and MR angiography and the costs of DSA influenced the results.Given currently accepted incremental cost-effectiveness ratios, immediate tentative percutaneous revascularization is a cost-effective strategy for the diagnosis of renal artery stenosis. Management decisions should be conditional on the prior probability.

To evaluate the safety and effectiveness of transcatheter arterial embolization (TAE) with ethanol in symptomatic patients with enlarged polycystic kidney disease.This prospective study was institutional review board approved and was planned for patients with symptoms related to enlarged polycystic kidney disease, such as a markedly distended abdomen, gastroesophageal reflux, and abdominal pain. At the time of TAE, all patients were undergoing dialysis therapy for chronic renal failure, and their urinary volume had decreased to less than 500 mL per day. Bilateral renal TAE with absolute ethanol was performed, and changes in kidney volume, clinical symptoms, laboratory data, and complications were evaluated after TAE. The differences in patients' kidney volumes, clinical symptoms, abdominal circumference, and dry weights before and after TAE were analyzed with a mixed effect model.Fifteen patients (seven men and eight women; mean age, 57.7 years ± 5.3 [standard deviation]) were treated. Among the 15 patients, the follow-up period was 24 months in 13 patients, 6 months in one patient, and 3 months in one patient. The mean kidney volume was 3380 mL before renal TAE, and at 3, 12, and 24 months after TAE, it significantly decreased to 60.9%, 39.8%, and 32.1% of the pretherapeutic value, respectively (P.001). All patients reported improved clinical symptoms within 3 months after TAE (P.001). Abdominal circumferences were significantly decreased after TAE (P.001). The dry weights also continued to significantly decreased until 6 months after TAE (P.001), at which point they began to slightly increase until 24 months after TAE. Abdominal pain, nausea, and inflammatory response developed in all patients after TAE, but these symptoms improved with conservative treatment. Abscess formation was found in one kidney, and drainage catheter placement was performed. No major complications related to TAE occurred in the remaining patients.Renal contraction therapy by TAE with ethanol injection appears to be a safe and effective treatment in patients with symptomatic enlarged polycystic kidney disease.

The purpose of this study was to prospectively evaluate an arterial spin-labeling technique, flow-sensitive alternating inversion-recovery (FAIR) true fast imaging with steady-state precession (FISP), for noninvasive quantification of renal perfusion in patients without a history of renal artery stenosis (RAS) and in patients with proved RAS. The study was approved by the local ethics committee, and all participants provided written informed consent. Six patients with hypertension but no history of renal artery disease and 12 patients with RAS underwent FAIR true FISP magnetic resonance (MR) imaging in a whole-body 1.5-T unit. RAS grade and scintigraphic perfusion data served as the reference standards. On the FAIR true FISP perfusion images, severe RAS (70% luminal narrowing) could be clearly distinguished from no or mild RAS and moderate RAS (or =70% luminal narrowing) (P.005). Significant correlations between FAIR perfusion data and stenosis grade (r = -0.76) and between FAIR and single photon emission computed tomographic perfusion values (r = 0.83) were observed. FAIR true FISP was found to be suitable for quantitative perfusion imaging of the kidneys in patients with RAS.

To test the hypothesis that the technical success rates, complication rates, and procedural times for magnetic resonance (MR) imaging-guided percutaneous transluminal angioplasty (PTA) and conventional (x-ray) fluoroscopy-guided PTA for treatment of renal artery stenosis are similar.The study was animal care and use committee approved. After surgically inducing bilateral renal artery stenosis in 11 swine, the authors performed baseline digital subtraction angiography. They transferred each animal to a 1.5-T MR imaging unit and randomly decided which artery would be treated with MR-guided PTA. With MR imaging guidance, angioplastic devices were tracked by using active and passive techniques. Vascular depiction was achieved by using catheter-directed MR angiography. Stenotic vessels were dilated by using 5-6-mm-diameter balloon catheters. PTA was then performed in the contralateral artery by using conventional fluoroscopy-guided techniques. With the intention to treat, the authors compared the technical success (residual stenosis50%) rates, complication rates, and procedural times for each guidance method. They compared technical successes and complications by using the McNemar test and procedural times by using a paired t test, with P.05 indicating a significant difference.The authors successfully dilated nine (82%) of 11 renal arteries with MR guidance and all 11 arteries (100%) with conventional fluoroscopic guidance. The difference was not significant (P = .5). Complications occurred in three (27%) arteries with MR guidance and in one (9%) artery with fluoroscopic guidance, with no significant differences (P = .5). The mean MR-guided PTA procedural time was 46 minutes longer than the fluoroscopy-guided PTA procedural time; this difference was significant (P = .01).In a small cohort of swine, the authors did not observe a significant difference between MR imaging- and conventional fluoroscopy-guided renal artery PTA in terms of success and complication rates. However, no evidence of similarity between the techniques should be assumed. Procedural times differed significantly.

To retrospectively assess the accuracy of four-section multi-detector row computed tomography (CT) in the evaluation of renal transplant donors when scans are read by one of multiple readers with varied levels of expertise, by using surgery as the reference standard.This retrospective study was approved by the institutional review board and complied with the Health Insurance Portability and Accountability Act. Informed consent was waived. Between October 1999 and March 2003, 94 renal donors (42 men, 52 women; mean age, 44 years) underwent four-section multi-detector row CT. Unenhanced scanning of the abdomen was performed with 5-mm section thickness and table speed of 15 mm per rotation. Next, 135-150 mL of nonionic iodinated (300 mg/mL) contrast material was injected intravenously at a rate of 4-5 mL/sec. Contrast material-enhanced CT was initiated 20-25 seconds, 65-70 seconds, and 10 minutes after start of injection. Arterial phase scanning was performed with 1.25-mm section thickness and 7.5-mm table speed. Venous and excretory phase scanning was performed with 2.5-mm section thickness and 15-mm table speed. Each scan was evaluated independently by one of 11 readers for renal vascular and ureteral anatomic variants. Findings at CT were compared with those at surgery. Sensitivity and specificity (with 95% confidence intervals) and accuracy of CT were calculated on the basis of presence or absence of variant anatomy at surgery.CT depicted 107 of 114 renal arteries confirmed at surgery; seven accessory arteries were missed in six donor kidneys. CT depicted 95 of 98 renal veins confirmed at surgery. Sensitivity and specificity of CT were 66% and 100%, 75% and 100%, and 50% and 100%, and overall accuracy was 94%, 97%, and 99%, for identification of variant anatomy of renal arteries, veins, and ureters, respectively.Multi-detector row CT as the sole imaging technique in the preoperative evaluation of living renal donors is accurate even when images are read by multiple readers with varied levels of expertise.

To determine the temporal histopathologic findings associated with selective arterial injection of a 1:1 ethiodized oil-ethanol mixture (EEM) in normal rabbit kidney followed by administration of pure ethanol into the main renal artery.In five rabbits, the EEM was injected sequentially into each segmental renal artery of the right kidney until capillary stasis occurred. Pure ethanol was then injected into the main renal artery to achieve complete arterial stasis. Before sacrifice, the left kidney in each animal was acutely (ie, with a short follow-up period) embolized by using the same technique. The 10 kidneys of the five rabbits were evaluated microscopically at 1 (n = 3), 1(1/2) (n = 1), and 3 hours (n = 1) and 1 (n = 1), 3 (n = 1), 5 (n = 1), 7 (n = 1), and 14 days (n = 1) after embolization.Injection of the EEM (mean volume, 0.46 mL +/- 0.14 [SD]) followed by ethanol alone (mean volume, 0.25 mL +/- 0.09) led to complete stasis in all kidneys. There was no recanalization in the chronically (ie, with a longer follow-up period) embolized kidneys. Microscopically, uniform distribution of the EEM was evident in all slices at all time points. From 1 to 3 hours, sloughing of endothelium, formation of thrombi, and deposition of eosinophilic material along the renal, interlobar, and arcuate arteries were observed, without evidence of parenchymal damage. Within 24 hours, complete coagulative necrosis of the entire kidney occurred as a result of an occluding thrombus in the main renal artery. Analysis at subsequent time points revealed liquefaction of necrotic tissue and replacement with granulation tissue.In the rabbit, selective renal arterial injection of EEM followed by administration of ethanol produces vascular endothelial damage initiating thrombosis that results in renal infarction and ablation within 24 hours.

To evaluate the appearance of lithium nephropathy at magnetic resonance (MR) imaging.Sixteen patients with renal insufficiency and clinical and laboratory evidence of nephropathy secondary to therapy with lithium salts were examined with a 1.5-T MR imaging unit with T1-weighted, T2-weighted fast imaging with steady-state precession (true FISP), rapid acquisition with relaxation enhancement, half-Fourier turbo spin-echo, and gadolinium-enhanced (FISP three-dimensional MR angiographic) sequences. Renal size and the presence, number, location and size of parenchymal cysts were analyzed. The cysts in each kidney were defined as rare (fewer than 10 cysts), sparse (between 10 and 30 cysts), abundant (30-60 cysts), or very abundant (more than 60 cysts).The mean length of both kidneys was 104 mm +/- 9 in seven cases, and one or both kidneys were less than 90 mm in length in nine cases. Renal microcysts measuring from 1 to 2 mm were detected in all patients. They were either very abundant (n = 12), abundant (n = 2), or sparse (n = 2). The cysts were located with equal abundance in both the cortex and the medulla in 11 cases and were predominantly located in the renal cortex in five cases. No renal artery stenosis was present.Microcysts secondary to long-term lithium therapy can be detected with MR imaging.

To determine the prevalence of isolated hemodynamically significant stenoses of accessory renal arteries when the main renal arteries are patent.In 68 adults (24 men, mean age, 67 years +/- 10; 44 women, mean age, 67 years +/- 12), angiograms that fulfilled the following criteria were studied: (a) technically adequate renal angiograms obtained to evaluate suspected renovascular hypertension and (b) angiographically documented hemodynamically significant stenosis of any renal artery. The percentage of kidneys and the percentage of patients with hemodynamically significant isolated stenoses of accessory renal arteries were calculated.Eighty-seven kidneys in 68 patients had hemodynamically significant renal artery stenoses. Fifteen kidneys had 16 accessory renal arteries. Four accessory arteries in three patients had hemodynamically significant stenoses. Only one of 68 patients (1.5%) had an accessory artery stenosis unaccompanied by a main renal artery stenosis in either kidney; this patient had bilateral hemodynamically significant accessory artery stenoses. Two patients had coexistent hemodynamically significant stenoses of accessory and main renal arteries.The prevalence of a hemodynamically significant stenosis isolated to an accessory renal artery was 1.5% in our study. Thus, failure to detect accessory renal arteries should not unduly affect the utility of a noninvasive test for detecting renovascular hypertension.

A cardiac-triggered free-breathing three-dimensional balanced fast field-echo projection magnetic resonance (MR) angiographic sequence with a two-dimensional pencil-beam aortic labeling pulse was developed for the renal arteries. For data acquisition during free breathing in eight healthy adults and seven consecutive patients with renal artery disease, real-time navigator technology was implemented. This technique allows high-spatial-resolution and high-contrast renal MR angiography and visualization of renal artery stenosis without exogenous contrast agent or breath hold. Initial promising results warrant larger clinical studies. © RSNA, 2002

To evaluate the accuracy of magnetic resonance (MR) imaging in the preoperative evaluation of potential living renal donors who are candidates for laparoscopic nephrectomy.Twenty-eight donor candidates who underwent subsequent laparoscopic nephrectomy were examined by using a torso phased-array coil at 1.5 T. Gadolinium-enhanced MR angiograms, MR venograms, and MR urograms were obtained in all patients by using an interpolated three-dimensional T1-weighted spoiled gradient-echo sequence (3.4-6.8/1.2-2.3 [repetition time msec/echo time msec], 25 degrees -40 degrees flip angle). Interpretation of the MR images was used to assess the arterial, venous, and ureteral anatomy, as well as parenchymal masses and scarring, and findings were compared with the surgical findings in all patients. Statistical evaluation was performed, with the surgical findings as the reference standard.At MR imaging, 31 of 32 renal arteries and one of three early-branching arteries were identified correctly. The correct venous anatomy was identified in 23 of 28 patients, including a single left renal vein anterior to the aorta (n = 16), retroaortic left renal vein (n = 2), circumaortic left renal vein (n = 2), and single right renal vein (n = 3). A single collecting system in all harvested kidneys was identified correctly with MR urography. Overall, MR imaging correctly depicted vascular, ureteral, and parenchymal anatomy in 21 of 28 patients. Twenty-seven of 28 patients underwent successful laparoscopic donor nephrectomy on the basis of the MR findings. One procedure was converted to open nephrectomy on the basis of complex venous anatomy not prospectively identified on the MR images. The sensitivity and positive predictive value of MR imaging in correctly determining the combined vascular, ureteral, and parenchymal anatomy in the harvested kidney were 75% (21 of 28) and 95% (21 of 22), respectively.Comprehensive gadolinium-enhanced MR imaging can depict the vascular anatomy, collecting system, and renal parenchyma preoperatively in patients who are candidates for laparoscopic living-donor nephrectomy.

To compare volume rendering (VR) and maximum intensity projection (MIP) as postprocessing techniques of magnetic resonance (MR) angiography for detection and quantification of renal artery stenosis.Twenty-seven patients underwent three-dimensional contrast material-enhanced MR angiography of the renal arteries with a 1.5-T imager. For each renal artery, targeted MIP and VR images were reconstructed in oblique coronal and transverse orientations. For each modality, image generation and evaluation were performed interactively by two independent radiologists blinded to angiographic results. In comparison with digital subtraction angiography (DSA) findings, stenosis quantification and detection by using MIP and VR were evaluated with the use of 50% and 70% cutoff points by using linear regression analysis and 2 x 2 tables. Overall image quality and vascular delineation on MIP and VR images were also compared.All main and accessory renal arteries depicted at DSA were also demonstrated on MIP and VR images. VR performed slightly better than MIP for quantification of stenoses greater than 50% (VR: r(2) = 0.84, P.001; MIP: r(2) = 0.38, P =.001) and significantly better for severe stenoses (VR: r(2) = 0.83, P.001; MIP: r(2) = 0.21, P =.1). For detection of stenosis, VR yielded a substantial improvement in positive predictive value (VR: 95% and 90%; MIP: 86% and 68% for stenoses greater than 50% and 70%, respectively). Image quality obtained with VR was not significantly better than that with MIP; however, vascular delineation on VR images was significantly better.The VR technique of renal MR angiography enabled more accurate detection and quantification of renal artery stenosis than did MIP, with significantly improved vascular delineation.

To determine the hemodynamic significance of arteriographically detected renal arterial stenosis by obtaining pressure gradients with a miniaturized pressure guide wire.Forty-six renal arterial stenoses in 38 patients were assessed in terms of severity and then subjected to gradient determination before and after angioplasty. The patients (mean age, 63 years) had a mean serum creatinine value of 1.3 mg/dL +/- 0.4 (114.9 micromol/L +/- 35.4 [SD]) and required on average three medications for blood pressure control. The mean degree of stenosis diameter was 51% +/- 17 (range, 12%-85%).The systolic and mean arterial pressure gradients with and those without vasodilatation were highly correlated with stenosis severity, systolic blood pressure, and serum creatinine as a curvilinear fit (r = 0.9, P.01). At 50% stenosis severity, the mean pressure gradient was 22 mm Hg.Patients with a pressure gradient greater than 20 mm Hg should be good candidates for renal arterial dilatation, and use of the pressure guide wire will facilitate interventional decisions.

To evaluate the hemodynamic outcome of technically successful percutaneous transluminal renal artery angioplasty and stent placement (PTRAS) with duplex ultrasonography (US).Eighteen patients who underwent PTRAS in 22 renal arteries were prospectively examined. All had abnormal preprocedural duplex US findings. Those who had significant renal artery stenosis (70%) at angiography and underwent technically successful percutaneous interventions were enrolled. Standard intrarenal duplex US parameters (acceleration index [AI], acceleration time, waveform morphology grade, and resistive index) were compared before and after interventions.A significant AI increase occurred after PTRAS (9.02 m/sec(2) +/- 4.85 [SD]), as compared with before intervention (2.34 m/sec(2) +/- 2.03; P.001). Acceleration time significantly decreased from 0.084 second +/- 0.049 to 0.032 second +/- 0.008 (P.01). There was also a significant resistive index increase from 0.69 +/- 0.12 to 0.79 +/- 0.12 (P.01). Abnormal waveform morphology (modified Halpern waveform grade 3-6) was present in 19 (86%) of 22 intrarenal arteries prior to intervention, as compared with one (5%) after PTRAS (P.001). In the instance in which an abnormal waveform persisted after intervention, waveform morphology improved from grade 6 to grade 3, with a concomitant AI increase from 0.96 to 5.1 m/sec(2).The findings suggest an important potential role for duplex US in noninvasive assessment of the immediate hemodynamic outcome and long-term follow-up of PTRAS.

To evaluate the frequency of increased renovascular impedance and its relationship with the presence of esophageal varices in patients with Child-Pugh class A cirrhosis without ascites.The intraparenchymal renal resistive index (RI) (reference value,0.7) and portal congestive index (ie, the ratio between the portal cross-sectional area and mean flow velocity; reference value,0.07) were measured by using duplex Doppler ultrasonography in 50 consecutive patients. The frequency of varices was assessed endoscopically. The data were analyzed with the Fisher exact test.The renal RI was consistent with increased impedance (ie,0.7) in 18 (36%) patients and was normal in 32 (64%). The proportion of patients with varices was significantly higher in the former group: 14 (78%) versus 10 (31%) (P =.002). In detection of the presence of varices, the renal RI was uniformly better than the portal congestive index in terms of sensitivity (58% vs. 48%), specificity (84% vs 54%), and positive (3.60 vs 1.04) and negative (0.50 vs. 0.96) likelihood ratios. RI determination improved the ability to exclude the presence of varices from a basal pretest probability of 52% (26 of 50 patients) to a final one of 69% (22 of 32 patients) and that of predicting the presence of varices from 48% (24 of 50 patients) to 78% (14 of 18 patients).A substantial proportion of patients with Child-Pugh class A cirrhosis without ascites have increased renovascular impedance; this significantly correlates with the presence of varices.

A partially parallel image acquisition technique, simultaneous acquisition of spatial harmonics, or SMASH, was used to increase the spatial and/or temporal resolution in contrast material-enhanced three-dimensional magnetic resonance angiography of the abdominal aorta and renal arteries. In eight healthy subjects, the breath-hold duration was halved at constant spatial resolution, or the spatial resolution was doubled at fixed breath-hold duration, with a 30%-55% reduction in the signal-to-noise ratio but otherwise preserved or improved image quality.

To compare the results of balloon percutaneous transluminal renal angioplasty (PTRA) and stent placement in atherosclerotic ostial, proximal, and isolated truncal stenoses.Between January 1994 and April 1998 the authors prospectively followed up 163 consecutive patients with 200 atherosclerotic renal arterial lesions after primary PTRA or primary stent placement. Duplex ultrasonography was performed 1 day and 3, 6, and 12 months later.The primary 12-month PTRA patency rates were 34% (21 of 33 atherosclerotic lesions) for ostial stenoses, 65% (20 of 60) for proximal stenoses, and 83% (five of 30) for truncal stenoses (chi(2) value, 15.63; P.001). The corresponding stent patency rates were 80% (four of 21), 72% (nine of 34), and 66% (five of nine), respectively (chi(2) value, 4.11; not significant). Significant stent-related reduction in risk of restenosis was limited to the ostial stenoses (P =.002).Renal arterial stent placement considerably improves patency in ostial stenoses, but compared with the technically successful PTRA, it does not significantly improve primary patency in proximal and isolated truncal renal arterial stenoses.

Technical reliability was determined for triggering three-dimensional (3D) contrast material-enhanced magnetic resonance (MR) angiography with MR fluoroscopy. Technical requirements for high reliability were also identified. Reliability was evaluated in 330 consecutive patient studies of the neck, thorax, abdomen, and pelvis. Contrast material arrival was detected fluoroscopically in 325 of the 330 studies (98.5%), and the 3D sequence was successfully triggered in 321 of 330 studies (97.3%). Fluoroscopic triggering of centrically encoded 3D MR angiographic acquisitions is a highly reliable means of obtaining 3D MR angiograms with high spatial resolution.

PURPOSE: To assess SH U 508A in the diagnosis of suspected renal arterial stenosis by means of ultrasonography (US) and to confirm the safety of SH U 508A in a clinical setting. MATERIALS AND METHODS: A randomized crossover study was performed in 198 patients from 14 European centers who were referred for renal arterial angiography because they were suspected of having renal arterial stenosis. All patients underwent nonenhanced and SH U 508A–enhanced Doppler US of the renal arteries. Doppler criteria included measurement of renal arterial peak systolic velocity (threshold, 1.4–2.0 m/sec) in all centers and renoaortic ratio (threshold, 3.0–3.5) in nine. RESULTS: The number of examinations with successful results increased following enhanced Doppler US examination—160 (83.8%) compared with 122 (63.9%) with nonenhanced Doppler US (P = .001), including patients with obesity or renal dysfunction. Renal arterial stenosis (≥50%) was detected at angiography in 72 patients. Results at enhanced Doppler US were in a...

To evaluate a technique for time-resolved breath-hold contrast material-enhanced three-dimensional magnetic resonance (MR) angiography of the abdomen.In a prospective study, 43 patients underwent time-resolved MR angiography (acquisition time per data set, 7 seconds). The patients also underwent single-phase high-spatial-resolution MR angiography (acquisition time, 27 seconds) (n = 6), conventional angiography (n = 7), or both (n = 30). No bolus timing study was performed for time-resolved MR angiography. Image quality (presence of artifacts, ability to prevent venous overlap on arterial phase images, contrast enhancement) and demonstration of anatomic variants (renal arterial and venous variants, vena caval anomaly, visceral arterial variants) and vascular diseases were assessed.Time-resolved MR angiographic images were characterized by fewer and less severe artifacts, less overlap of enhancing veins, and better contrast enhancement than were single-phase MR angiographic images (P.05). The mean sensitivity and specificity were 90% (nine of 10) and 100% (1 73 of 1 73), respectively, for detection of arterial anatomic variants and 93% (28 of 30) and 100% (324 of 325), respectively, for detection of disease. The technique also proved to be reliable for demonstration of venous disease.In comparison with current non-time-resolved MR angiographic techniques, time-resolved MR angiography is more robust and easier to perform and allows simultaneous evaluation of arterial and venous disease.

To determine and compare the diagnostic performance of fetal middle cerebral (MCA), renal (RA), and umbilical (UA) arterial Doppler ultrasonography (US) for prediction of adverse perinatal outcome in suspected intrauterine growth restriction (IUGR).Two hundred ninety-three small-for-gestational age fetuses (24-39 weeks at recruitment and US-estimated weight or abdominal circumference below 10th percentile) were prospectively examined with Doppler US of the UA, MCA, and RA. Clinicians were blinded to MCA and RA Doppler measurements.Seventy-six fetuses (25.9%) had at least one major or minor adverse perinatal outcome. Major outcomes included stillbirth, neonatal death, neurologic complication, and necrotizing enterocolitis. The MCA pulsatility index (PI), compared with the UA PI and RA PI, was more sensitive (72.4% vs 44.7% and 8.3%) but less specific (58.1% vs 86.6% and 92.6%) in predicting adverse outcome. The UA PI had the highest positive likelihood ratio (ratio, 3.3); the MCA PI had the lowest negative likelihood ratio (ratio, 0.48). When gestational age at the first Doppler US examination was less than 32 weeks, the MCA PI had a sensitivity of 95.5% and negative predictive value of 97.7% for major adverse outcome (negative likelihood ratio, 0.10).In suspected IUGR, while an abnormal UA PI is a better predictor of adverse perinatal outcome than an abnormal MCA or RA PI, a normal MCA PI may help to identify fetuses without major adverse perinatal outcome, especially before 32 weeks gestational age.

To evaluate whether Doppler ultrasonographic (US) velocimetry in renal interlobar arteries is altered in women with pregnancy-induced hypertension (PIH) compared with that in healthy pregnant and nonpregnant women.Flow waveform measurements in renal interlobar arteries were obtained in 39 nonpregnant women, 77 healthy pregnant women at 16-40 weeks gestation, and 15 women with PIH at 28-39 weeks gestation by using color and pulsed Doppler US.In the nonpregnant group, the mean (+/- SD) peak systolic velocity, end-diastolic blood flow velocity, resistive index, and acceleration time were 0.34 m/sec +/- 0.08, 0.14 m/sec +/- 0.03, 0.62 m/sec +/- 0.07, and 52.3 m/sec +/- 13.7, respectively. In the healthy pregnant group, the peak systolic and end-diastolic blood flow velocities at 16 weeks gestation had decreased greatly by 40 weeks gestation. However, the values of other indexes in this group did not change with gestational age. In the PIH group, the acceleration time values were greatly prolonged compared with those in the other groups.Acceleration time is one of the hemodynamic parameters of substantial upstream stenosis. These findings suggest that severe stenosis or continuous vasospasm in the proximal arteries, such as the main renal artery and segmental artery, might be implicated in the pathogenesis of PIH.

To compare the outcomes and costs of percutaneous transluminal renal angioplasty (PTRA), percutaneous transluminal stent placement (PTSP) of renal arteries, and renal arterial bypass grafting (RABG) in treatment of renovascular hypertension.Medical records and angiograms of 130 patients who underwent PTRA, PTSP, or RABG were retrospectively studied to determine success and complication rates, angiographic stenoses, blood pressures, antihypertensive medications, and serum creatinine levels. Actual costs were analyzed in detail.Technical success rates for PTRA, PTSP, and RABG were 91%, 98%, and 92%, respectively. Complication rates were 13%, 16%, and 38%, respectively. The mean arterial pressure was initially lowered by 29.2 mm Hg, 30.3 mm Hg, and 27.3 mm Hg, respectively, and maintained at 21.0 mm Hg, 19.8 mm Hg, and 20.2 mm Hg below baseline at 12 months. The number of antihypertensive medications was initially reduced on average by 0.63, 0.72, and 0.58, respectively, but returned to baseline in all patients by 12 months. The serum creatinine level did not change substantially with any treatment. Initial treatment costs were $1,402, $2,573, and $15,393, respectively.PTRA, PTSP, and RABG were equally efficacious for control of renovascular hypertension. The initial treatment cost for bypass grafting was substantially higher than that for PTRA and PTSP of renal arteries.

PURPOSE: To test the hypothesis that increased end-organ vascular resistance reduces blood flow to the kidney, thus reducing the mean velocity in the renal artery and secondarily lowering the peak systolic velocity (PSV). MATERIALS AND METHODS: An in vitro hydraulic model with a pulsatile pump, blood-mimicking fluid, interchangeable stenoses, and variable compliance and resistance was used to investigate the relationship between end-organ vascular resistance and poststenotic PSV. RESULTS: Poststenotic PSV was mildly dependent on end-organ vascular resistance and decreased with increasing resistance. CONCLUSION: The results help explain some of the reported variability from using poststenotic PSV to detect hemodynamically significant renal arterial stenoses, but the effect is not great enough to completely explain the variability. Other factors not investigated in this study must be at work as well.

To investigate the feasibility of imaging crossing vessels at the ureteropelvic junction (UPJ) preoperatively by means of contrast agent-enhanced color Doppler imaging (CDI).Twenty-nine patients (13 female patients, 16 male patients; age range, 17-76 years; mean age, 45 years) with symptomatic UPJ obstruction were examined with CDI before and after intravenous infusion of the contrast agent. The type (i.e., arterial or venous) and position of the vessel relative to the UPJ (i.e., anterior or posterior) were assessed. The CDI findings were correlated with the surgical findings at laparoscopic pyeloplasty.Among the 29 patients, crossing vessels were detected with nonenhanced CDI in 15 patients, with enhanced CDI in 22 patients, and with laparoscopy in 23 patients. Enhanced CDI depicted crossing vessels in 22 (96%) of the 23 laparoscopically confirmed cases compared with nonenhanced CDI, which depicted 15 (65%) of the 23 cases. The rate of detecting crossing vessels increased significantly with use of the contrast agent (P.016, McNemar test).Compared with nonenhanced CDI, contrast-enhanced CDI significantly improves the detection of crossing vessels at the UPJ and is useful in the presurgical evaluation of UPJ obstruction.

To determine whether gadodiamide is a safe and useful angiographic contrast agent for help in diagnosis and percutaneous treatment of renal artery stenosis in patients with renal insufficiency.Diagnostic renal angiography and percutaneous renal interventions were performed by using gadodiamide (total dose, 0.3 mmol/kg) and CO2 as intraarterial contrast agents in 25 procedures in 24 patients with renal insufficiency. Serum creatinine levels were obtained within 24 hours before and at 24 and 48 hours after the procedure. Increases in serum creatinine of more than 44 mumol/L were considered clinically important. Gadodiamide-enhanced angiograms were compared with CO2-enhanced angiograms.In 23 (92%) of 25 procedures, there was no increase in serum creatinine level at 48 hours. One patient with acute and chronic rejection of a renal transplant and one with evidence of cholesterol embolization had a clinically important increase in serum creatinine level at 48 hours. No marked increase in creatinine level was observed in patients with relatively low baseline levels (n = 19). Gadodiamide-enhanced angiograms appeared to be better than CO2-enhanced angiograms for help in identifying renal artery occlusions, visualizing renal vessels incompletely filled with CO2, and determining the progress of intervention.Gadodiamide appears to be a safe and useful intraarterial contrast agent in patients with renal insufficiency and can be used to supplement or confirm CO2-enhanced angiographic findings.

To evaluate the usefulness of Doppler ultrasonography (US) in the diagnosis of hyperfiltration in patients with insulin-dependent diabetes mellitus (IDDM).Eighty-one consecutive patients with IDDM were studied. All patients were normotensive and had normal creatinine and blood urea nitrogen levels. The glomerular filtration rate (GFR) was evaluated by means of plasma clearance of chromium-51 ethylenediaminetetraacetic acid, urinary albumin excretion, US evaluation of renal volume, and Doppler evaluation of resistance index (RI) in the renal interlobar arteries. The patients were divided according to GFR into the following groups: those with hyperfiltering kidneys (group 1, n = 40) and those with normofiltering kidneys (group 2, n = 41).The median renal volume was 351 mL (95% CI = 337 mL, 379 mL) in group 1 and 318 mL (95% CI = 300 mL, 335 mL) in group 2 (P = .005). The number of patients with microalbuminuria was significantly lower in group 1 than in group 2 (P = .02). The median RI was significantly lower in group 1 (0.55; 95% CI = 0.53, 0.57) than in group 2 (0.57; 95% CI = 0.56, 0.59) (P = .04). An RI of less than 0.5, a renal volume greater than 410 mL/m2, and the absence of microalbuminuria were independent predictors of hyperfiltration. An RI of less than 0.5 and a renal volume greater than 410 mL/m2 showed high specificity (98% and 95%, respectively) and poor sensitivity (25% and 23%, respectively) in the diagnosis of hyperfiltration in IDDM patients.Both RI and renal volume showed correlation with GFR, but neither parameter is sufficiently sensitive in screening for hyperfiltration in IDDM patients.

To evaluate the use of dual-phase three-dimensional magnetic resonance (MR) angiography in the preoperative staging of renal cancer.MR angiography was performed in 18 patients before performance of partial (n = 7), radical (n = 10), or laparoscopic (n = 1) nephrectomy to treat renal cancer. Dynamic, three-dimensional MR angiograms were obtained with gadoteridol enhancement, breath holding, and a three-dimensional spoiled gradient-echo sequence. Images were obtained at 15-second intervals to achieve opacification of arteries and veins. Source, maximum intensity projection, and multiplanar reconstruction images were evaluated. Imaging results were compared with surgical findings.Renal arterial phase MR angiograms depicted 30 of 31 (97%) surgically confirmed renal arteries, with one false-positive result (an artery that arose from an early-branching single main renal artery, interpreted as a separate accessory artery). Renal venous phase MR angiograms depicted all seven instances of renal vein involvement, including extension to the inferior vena cava in two patients. Collateral vessels around the tumor, including prominent gonadal veins in three patients, were demonstrated. Additional findings included adenopathy and adrenal and pulmonary metastases.Dual-phase MR angiography of the kidney may be a useful technique in depicting renal vessels before nephrectomy.

To determine whether magnetic resonance (MR) angiography can be used alone to evaluate abdominal aortic aneurysms (AAAs) for endovascular placement of stent grafts.Sixty-one patients with AAAs underwent gadolinium-enhanced MR angiography of the abdominal aorta and pelvic arteries. Measurements of the size and extent of the AAAs were compared with helical computed tomographic (CT) and digital subtraction angiographic measurements; 95% confidence intervals for the differences in the means were determined.Because of the larger field of view, MR angiography was superior to CT angiography in assessing visceral iliac artery disease. Both modalities were equal in evaluating the proximal extent of the AAA (mean difference, -0.16 mm; 95% CI, -0.31, 0.64) and in measuring all aortic dimensions (e.g., mean difference in the proximal neck diameter, -0.74 mm; 95% CI, -0.98, -0.49). MR angiography was inferior to CT angiography in depicting accessory renal arteries (seven of 12) and in grading renal artery stenoses (sensitivity, 100% [95% CI, 0.90, 1.00]; specificity, 84% [95% CI, 0.74, 0.91]).Gadolinium-enhanced MR angiography is a fast, reliable means of providing all the information relevant to the preoperative assessment of endovascular aortic stent-graft placement.

To evaluate the ability of a phase shift contrast agent to improve Doppler sonographic imaging of the main renal arteries in cases of suspected renal artery stenosis.In 25 patients in whom renal artery stenosis was suspected, baseline Doppler sonography was performed followed by two studies performed after blinded administration of contrast material or placebo (saline). Each kidney (n = 45) was evaluated for (a) visualization of the main renal artery on a scale of 0-4, (b) presence of accessory renal arteries, and (c) direct Doppler sonographic findings suggestive of renal artery stenosis. Correlative magnetic resonance angiography was performed in 24 patients, and angiograms were obtained in eight kidneys with stenosis at one or both imaging studies.Contrast enhancement was observed in 23 patients. Enhancement was 8-20 minutes. Renal artery visualization scores improved from a mean of 2.56 and 2.71 on baseline and noncontrast scans, respectively, to 3.69 after administration of contrast material. Contrast-enhanced images depicted seven kidneys with accessory renal arteries not seen at other studies. Two of eight cases of stenosis were seen only with contrast-enhanced sonography.Use of the phase shift contrast agent appears to enable a reduction in the number of equivocal findings of renal artery stenosis.

Pulsatility index and resistive index were mapped with color Doppler ultrasound (US) and compared with spectral Doppler US findings. In the carotid arteries and/or kidneys in 12 healthy subjects, the pulsatility index and resistive index were estimated from mean frequency shifts and mapped into "cool-warm" or "rainbow" color scales. Surveys that depicted intervessel variations in a complex vascular field were useful in deciding where to perform spectral Doppler US. Intravessel variations were consistent with fluid dynamic theory.

To determine the diagnostic accuracy of breath-hold, contrast material-enhanced, three-dimensional (3D) magnetic resonance (MR) angiography in the assessment of the aortoiliac inflow tract and renal arteries with conventional catheter angiography as the standard of reference.In 39 patients with symptomatic peripheral vascular disease, both catheter and contrast-enhanced, 3D MR angiography were performed. In a prospective blinded analysis, each vascular segment (23 segments per arterial tree) was evaluated for the presence of obstructive stenosis, graded as mild (50%), severe (50%-99%), or occlusion (100%), as well as for aneurysmal disease.Obstructive (n = 2) and aneurysmatic aortic (n = 6) lesions and 10 of 11 accessory renal arteries were identified and graded correctly with MR angiography. For detection of hemodynamically significant stenotic lesions (50%) or occlusions with MR angiography, sensitivity and specificity, respectively, were 93% and 98% for the renal arteries, 96% and 100% for the common iliac arteries, 93% and 93% for the external iliac arteries, and 96% and 94% for the internal iliac arteries.The diagnostic performance of contrast-enhanced 3D MR angiography is comparable with that of catheter angiography and thus may contribute to assessment of the aorta, the renal arteries, and the pelvic arterial system in patients with peripheral vascular disease before they undergo therapy.

To evaluate the influence of various parameters on peak systolic velocity in the transplanted renal artery and to define the normal range of peak systolic velocity.Color Doppler ultrasonographic (US) findings in 105 patients were reviewed. There were no clinical or biologic findings suggestive of a stenosis in the transplanted renal artery in these patients. The peak systolic velocity in the transplanted renal and external iliac arteries and the renal resistive index were measured.A large range of peak systolic velocities was noted in the transplanted renal artery. Peak systolic velocity in the renal artery was statistically significantly correlated with that in the external iliac artery when there was no pronounced vessel curvature. There was no relationship between peak systolic velocity and resistive index or time between transplantation and US. High peak systolic velocity was associated with a pronounced vessel curvature.The normal range of peak systolic velocity in the transplanted renal artery has considerable variability. Because of the strong correlation, the ratio of velocity in the renal artery to that in the external iliac artery may be useful in detection of stenosis.

To determine the in situ location and distribution of the renal artery origins in the transverse plane with computed tomography (CT).CT scans of the paired main renal arteries in 200 patients (89 men, 111 women) were retrospectively reviewed. The locations of the renal artery origins, defined on the basis of their optimal profile angles, and the angle between them were measured. The degree of aortic atherosclerosis was graded in 119 of the 200 patients.The origins of 400 paired main renal arteries were identified. A statistically significant difference was found between the average best profile angle on the right (24 degrees [range, 26 degrees-70 degrees]) and that on the left (5 degrees [range, -75 degrees to 38 degrees]) (P.001). Truly laterally located renal arteries were seen on the right in 11 (5%) of 200 right renal arteries and on the left in 56 (28%) of 200 left renal arteries. One hundred eighty-six (93%) of 200 right ostia and only 40 (20%) of 200 left ostia were in an anterolateral location. One hundred four (52%) of 200 left ostia and three (2%) of 200 right ostia were in a posterolateral location. The prevalence of truly opposite renal arteries was 17%. The average profile angle between the renal artery origins was 161 degrees (range, 72 degrees-225 degrees) and was significantly larger in women (P = .001). No relationship was found between ostial location and patient age or atherosclerotic grade.In the transverse plane, the location of the origin of the right renal artery tended to be anterolateral and of the left renal artery tended to be posterolateral or lateral. The variation in location and distribution width was great.

To compare digital subtraction angiography with three-dimensional phase-contrast magnetic resonance (MR) angiography in detection of significant renal artery stenosis.Sixteen patients underwent digital subtraction angiography and systolically gated three-dimensional phase-contrast MR angiography within 1 week. Scoring of stenosis on MR angiograms was based on presence and length of a flow void and quality of flow signal intensity in the distal part of the artery. Intraarterial pressure measurement was the reference standard for hemodynamically significant renal artery stenosis.MR angiography depicted two of five patent accessory arteries. Comparison of digital subtraction angiography and MR angiography with intraarterial pressure measurements was possible in 25 main renal arteries. In 13 arteries, a pressure gradient of more than 15 mm Hg was found. Digital subtraction angiography depicted 10 of these stenoses (sensitivity, 77%; specificity, 92%). A flow void was present at MR angiography in eight stenoses (sensitivity, 62%; specificity, 83%). In 12 of the stenosed vessels, distal flow signal intensity was impaired at MR angiography (sensitivity, 92%; specificity, 75%). There was no difference between the two modalities (P.05) in grading hemodynamic significance of renal artery stenosis.Systolically gated MR angiography and digital subtraction angiography are equally effective in depicting hemodynamically significant stenoses in the main renal arteries. MR angiography, however, is not adequate in depiction of accessory renal arteries.

To evaluate the feasibility and safety of Guglielmi detachable coils for endovascular treatment of extracranial aneurysm and arteriovenous fistula.Embolization with Guglielmi detachable coils delivered through Tracker-18 microcatheters was performed in 16 patients. This patient group had eight renal artery aneurysms and 11 arteriovenous fistulas (three cases of patent ductus arteriosus, one associated with aneurysm; one fistula between the maxillary artery and jugular vein; two fistulas between the subclavian and pulmonary arteries; four fistulas between the pulmonary artery and vein; and one fistula between the anterior tibial artery and vein). Efficacy of the procedure was assessed by means of short-term follow-up (clinical examination, angiography, and/or Doppler sonography) 3 and 6 months later.No complications were encountered. Embolization was technically and clinically successfully in all eight aneurysms (100%) and in nine arteriovenous fistulas (82%). In two cases (fistula between the subclavian and pulmonary arteries and fistula between the anterior tibial artery and vein) endovascular placement of Guglielmi detachable coils failed to occlude the vessel. Results of short-term follow-up examinations confirmed the initial results in all cases.Guglielmi detachable coils are feasible, safe, and effective for endovascular treatment of extracranial aneurysm and arteriovenous fistula.

PURPOSE: To evaluate a discrepancy between the location of renal artery stenoses on intraarterial digital subtraction angiographic (DSA) images and that on spiral computed tomographic (CT) angiograms. MATERIALS AND METHODS: The spiral CT angiograms and intraarterial DSA images of 40 consecutive patients with atherosclerotic renal artery stenoses were examined retrospectively. Stenoses were classified as truncal or ostial. The atherosclerotic changes in the abdominal aorta were graded. RESULTS: Fifty-eight stenoses were demonstrated. In 48 ostial stenoses, there was no discrepancy in the location of the stenoses on spiral CT angiograms and DSA images. In 10 patients, spiral CT angiography showed an ostial lesion, whereas DSA demonstrated an apparent truncal lesion. Most of these stenoses ("pseudotruncal" ostial stenoses) were in patients with severe aortic atherosclerotic disease. CONCLUSION: A renal artery stenosis at or within 10 mm of an atherosclerotic aorta at DSA may be diagnosed as an ostial stenosis.

To assess the contribution of thin-section spiral computed tomography (CT) to the preoperative radiologic evaluation of juxta- and suprarenal abdominal aortic aneurysms.Thirty-eight patients (26 men, 12 women; age range, 60-81 years) with infrarenal (n = 23), juxtarenal (n = 8), and suprarenal (n = 7) aneurysms underwent digital subtraction angiography (DSA) and 2-mm-collimation spiral CT. Cine-interactive display of overlapping axial, reformatted, and maximum intensity projection images were used for CT image analysis. CT findings were compared with angiographic and surgical findings.The proximal extent of the juxta- and suprarenal aneurysms (n = 15) could be correctly predicted in 12 cases (80%) with DSA and was exactly determined in 14 (93%) with CT. All renal arteries except three accessory renal arteries were correctly depicted with spiral CT (83 of 86 [96%]). With DSA as the standard of reference, renal artery stenoses of at least 70% were accurately assessed in 95% of cases.Thin-section spiral CT can provide additional information in the preoperative diagnosis of juxta- and suprarenal aneurysms.