Diagnostic accuracy of sequential angio-urography with the spot-camera in clinical practice

In this perspective study the authors examined 57 patients to evaluate diagnostic accuracy of sequential angiourography (AUS) using spot-camera and image subtraction for the visualization of the vascular phase of the renal arteries. All the subjects underwent surgery or follow-up with other clinical and radiological methods. The results obtained with this technique, of low cost and simple execution, were satisfactory: accuracy 98%, sensitivity 100%, specificity 98%.     

Equilibrium-phase MR angiography of the aortoiliac and renal arteries using a blood pool contrast agent

OBJECTIVE: The purpose of this study was to determine the diagnostic usefulness of a new blood pool contrast agent, NC100150, for assessing the aortoiliac and renal arteries. SUBJECTS AND METHODS: Twenty patients with hemodynamically significant stenosis (> or =50% of luminal diameter) of the iliac or renal arteries or an aortic aneurysm documented by digital subtraction angiography underwent MR angiography at 1.5 T after administration of NC100150. Three-dimensional MR angiographic data sets were collected ill the equilibrium phase. In a prospective analysis, each vascular segment (16 segments per arterial tree) was evaluated. RESULTS: All patients tolerated the NC100150 administration well. Mean contrast-to-noise ratios of the vascular data collected in the equilibrium phase of NC100150 was 3.3+/-15.9. Compared with digital subtraction angiography, the sensitivity and specificity of MR angiography for the renal arteries were 82% and 98%, respectively; for the common iliac arteries, 86% and 97%, respectively; for the external iliac arteries, 80% and 100%, respectively; and for the internal iliac arteries, 71% and 977, respectively. All 83 aneurysmal changes revealed by digital subtraction angiograpy of the aortoiliac arteries were well displayed on the MR angiographic data sets. CONCLUSION: Equilibrium-phase NC 00150-enhanced three-dimensional MR angiography shows high specificity when evaluating the abdominal and pelvic vascular systems, but the attendant venous overlap can limit the assessment of stenosis in renal and pelvic arterial segments.     

Intrarenal fat deposition does not interfere with the measurement of single-kidney perfusion in obese swine using multi-detector computed tomography

BackgroundAltered vascular structure or function in several diseases may impair renal perfusion. Multi-detector computed tomography (MDCT) is a non-invasive tool to assess single-kidney perfusion and function based on dynamic changes in tissue attenuation during contrast media transit. However, changes in basal tissue attenuation might hamper these assessments, despite background subtraction. Evaluation of iodine concentration using the dual-energy (DECT) MDCT mode allows excluding effects of basal values on dynamic changes in tissue attenuation. We tested whether decreased basal kidney attenuation secondary to intrarenal fat deposition in swine obesity interferes with assessment of renal perfusion using MDCT.MethodsDomestic pigs were fed a standard (lean) or a high-cholesterol/carbohydrate (obese) diet (n = 5 each) for 16 weeks, and both kidneys were then imaged using MDCT/DECT after iodinated contrast injection. DECT images were post-processed to generate iodine and virtual-non-contrast (VNC) datasets, and the MDCT kidney/aorta CT number (following background subtraction) and DECT iodine ratios calculated during the peak vascular phase as surrogates of renal perfusion. Intrarenal fat was subsequently assessed with Oil-Red-O staining.ResultsVNC maps in obese pigs revealed decreased basal cortical attenuation, and histology confirmed increased renal tissue fat deposition. Nevertheless, the kidney/aorta attenuation and iodine ratios remained similar, and unchanged compared to lean pigs.ConclusionsDespite decreased basal attenuation secondary to renal adiposity, background subtraction allows adequate assessment of kidney perfusion in obese pigs using MDCT. These observations support the feasibility of renal perfusion assessment in obese subjects using MDCT.     

Comparison of spiral CT angiography with conventional digital subtraction angiography in the evaluation of renal transplant donors: a pilot study

Conventional digital subtraction renal arteriography (IA-DSA) has been traditionally used as the preoperative imaging modality for assessment of renal vascular anatomy for renal transplant donors. This study evaluates the potential use of spiral CT angiography in replacing IA-DSA in the preoperative assessment of this group of patients. Seven patients underwent both spiral CT angiography and IA-DSA between October 1997 and April 1998. It is concluded that spiral CT angiography can demonstrate the number, length and location of renal arteries and it is suggested that spiral CT angiography can potentially replace IA-DSA in the preoperative assessment of renal donors.     

Signal targeting with alternating radiofrequency (STAR) sequences: Application to MR angiography

We describe a time of flight subtraction method for cine MR angiography that provides nearly perfect suppression of background signal intensity with excellent flow contrast. The method consists of a preparation phase, during which the longitudinal magnetization of the target tissue is inverted on alternate acquisitions and the background tissue is presaturated, followed by a readout phase using a cine segmented turboFLASH sequence with a shared echo modification to improve temporal resolution. With appropriate alternation of the phases of the radiofrequency excitation pulses, there is cancellation of the background signal intensity but flow signal is optimized. By using a thick section (up to 25 mm), substantial portions of the vascular territory are encompassed in a single plane. This permits rapid, dynamic assessment of flow patterns in areas such as the circle of Willis, carotid bifurcation, or renal arteries. Applications of the method for bright and dark blood cine MR angiography are demonstrated.     

Sequential angio-urography (SAU) with photographic image subtraction

Urography was performed in 250 patients: the technique of bolus injection of a large quantity of contrast medium was used in every case. By means of rapid seriography the early vascular phase was shown and reproduced, when necessary, with image subtraction. The abdominal aorta and the renal arteries were demonstrated in 97.6% of cases. Altogether, in 34.4% of cases the existence of pathological conditions non demonstrable by conventional urography was ascertained; in 12.4% of cases extrarenal pathology was diagnosed. This technique is suggested to be used sistematically, as an alternative to DSA, where digital equipments are not available.     

活体肾移植供肾血管术前MRA评估的研究进展

术前评估供肾者血管解剖情况对于供肾筛选以及减少移植过程中潜在并发症的风险至关重要。目前多种磁共振血管成像(MRA),如对比增强MRA(CE-MRA)、时间飞跃法(TOF)、相位对比法(PC)及平衡稳态自由进动(SSFP)等技术已应用于供肾血管术前评估,可对肾动脉和肾静脉的复杂变异分型进行诊断。就肾血管解剖及各种MRA方法在供肾血管评估中的研究进展予以综述。     

Coil embolization for treatment of vascular complications after nephron-sparing surgery

Nephron-sparing surgery (NSS) is a standard surgical treatment for small renal tumors. We report four patients (aged 35-79 years) with vascular complications within 6 days to 3 months after open NSS. Three patients developed acute symptoms, whereas one was asymptomatic. Computed tomography (CT) in the arterial and venous phase of contrast enhancement was performed for diagnosis, followed by angiography. CT demonstrated a perirenal hematoma in three and an arterial pseudoaneurysm in two cases. Unlike CT, digital subtraction angiography confirmed an arterial pseudoaneurysm in all cases and additionally found an arteriovenous fistula in three. In all cases, angiography-guided coil embolization successfully treated the vascular pathology, while preserving renal function. Clinicians should understand the diagnosis and management of this complication of NSS.     

Results and experiences with digital subtraction angiography (DSA) in traumatic vascular lesions of the thoracic aorta and the supra-aortic branches

Numerous positive reports on the results obtained with digital subtraction angiography (DSA) in x-ray diagnostics in the visualisation of peripheral vascular areas, have been published ever since that method was introduced. From a surgical point of view it has therefore been suggested to extend the indication for vascular visualisation on account of the low invasiveness of venous DSA (vDSA). Only few reports have been published on the suitability of vDSA in traumatic vascular lesions. Whereas Starck and Rauber recommend vDS as a feasible method for the visualisation of traumatic vascular lesions, Galanski and Fiedler continue to postulate the need for arterial DSA (aDSA) in the clarification of degenerative diseases of the supraaortal branches. Conventional angiography has lost some of its importance in traumatic vascular lesions, as Traupe has stated. Our first experiences with vDSA in traumatic vascular lesions have been partly unsatisfactory. This, and the resulting consequences, are described in the present article.     

Current experience with digital subtraction angiography in the community medical center

At the community medical center, we have introduced and successfully applied digital subtraction angiography (DSA) to disease processes seen in 1,144 patients. Although there is a trade-off between increased contrast resolution and decreased spatial resolution with the DSA approach, nonetheless in many vascular beds it provides rapid, safe, and accurate disease diagnosis.     

Contrast-enhanced magnetic resonance angiography: evaluation of renal arteries in living renal transplant donors

One of the most important steps before living-donor nephrectomy is assessment of renal vascular anatomy. The number, origins and lengths of the renal arteries and variations of renal veins must be determined in order to identify the kidney that is most suitable for transplantation. Digital subtraction angiography was long considered the standard procedure for this purpose, but this method has been replaced by non-invasive techniques. Contrast-enhanced magnetic resonance angiography is an accurate, safe and reliable method for imaging vasculature. This article reviews the technique and the clinical features of this method in the evaluation of living renal transplant donors.     

Digital radiology of the kidney

Intravenous and intra-arterial digital subtraction angiographic techniques are suitable for application to nearly all renal vascular imaging indications. These methods are advantageous in comparison with conventional angiography. Digital imaging of the renal parenchyma and collecting systems is also feasible.     

Study of the liver and the portal venous system with digital rotational angiography

PURPOSE: Digital subtraction angiography is of common clinical use for the evaluation of vascular disease. The rotation of the X-ray tube around the patient's body during contrast medium injection was first proposed in the early seventies in the neuroradiologic field; only recently it has been applied to the evaluation of vascular structures and abdominal parenchymatous organs. We investigated the potential clinical value of digital rotational subtraction angiography in the evaluation of the hepatic arteries and of the portal venous system. MATERIALS AND METHODS: Digital rotational subtraction angiography was performed in 46 patients (34 males and 12 females), mean age 59.3 years (range: 43-72). All the patients underwent digital rotational subtraction angiography after ultrasonographic, CT and/or MRI imaging for evaluation of hepatocellular carcinoma (31 patients) prior to trans-arterial chemoembolization, hepatic metastases from gastrointestinal cancer (9 patients) and pre-surgical study in portal hypertension (6 patients). Digital rotational subtraction angiography was performed using the following technical parameters: a maximum frame rate of 10 views per second, a 1024 x 1024 matrix, a rotation time of 5 seconds, a rotational arch of 90 degrees with a speed of 30 degrees/second. Digital rotational subtraction angiography of the liver was carried out after positioning of a Cobra angiographic catheter in the proper hepatic artery or in the left or right hepatic artery, and subsequent injection of 20-30 ml on contrast medium at a flow rate of 4-7 ml/sec. Conversely, in the portal study the catheter was placed in the splenic or superior mesenteric artery and contrast was administered at 10 ml/sec for an amount of 40-60 ml. Conventional, non-rotational angiography was always obtained with the same catheter and less contrast medium (15-25 at 4-7 ml/sec in the hepatic study, 25-40 ml at 5-7 ml/sec in the portal study). We have evaluated the diagnostic quality (rated as equal, superior or inferior) and the presence of image noise of digital rotational subtraction angiography when compared to digital non-rotational subtraction angiography. We also evaluated the tolerability and the mean time to perform the examination. RESULTS: Compared to non-rotational digital subtraction angiography, the diagnostic quality of digital rotational subtraction angiography was superior in 26 cases, equal in 20 and never inferior: these results are particularly evident in cine-mode. Diagnostic efficacy was similar in the arterial phase and generally better in the venous phase. Image noise was always perceptible, mostly in lateral and oblique views and is related to the patient's size. Noise especially hindered evaluation of the portal venous phase. Digital rotational subtraction angiography was well tolerated by all patients, although its most significative drawback was the prolonged apnea time required (about 8 seconds per single rotation) which can sometimes be difficult for elderly patients. Examination duration is about 5 to 10 minutes. Contrast medium doses required never exceeded 20-60 ml. DISCUSSION: Current evaluation of an hepatic lesion requires injections and multiple views to fully delineate arterial anatomy. This requires the radiologist to create a mental 3-D rendering based upon a 2-D view, obtained on the basis of the radiologist's experience. Rotational angiography, when reviewed in cine-loop, allows a better 3-D rendering than conventional angiography, increasing the advantages of the multiple views obtained from a single angiographic run and allowing an exact imaging of the course and direction of the hepatic arterial branching, making selective catheterization during trans-arterial chemoembolization or other interventional procedures easier. Magnification further improves the evaluation of a mass and of the arterial tree. In hepatic surgery, the most important problem is the precise knowledge of the segment involved and the position of the lesion inside the segment, since a mass in the middle of the segment requires a segmentectomy while a mass near the borders is treated by a larger resection. Digital rotational subtraction angiography improves the visibility of vascular anatomy, allows a better knowledge of hepatic artery branches and improves the angiographic investigation of the liver, permitting a correct spatial assessment. CONCLUSION: Digital rotational subtraction angiography is a useful tool for the evaluation of the liver as well as for transarterial chemoembolization or other interventional procedures. Images are obtained during a single contrast injection, with a better 3-D rendering of the hepatic artery and the portal venous system: no other method provides as complete a visualization of liver vascular anatomy after a single injection of contrast medium in one examination series. (ABSTRACT TRUNCATED)     

Intraarterial digital subtraction arteriography in the management of renal tumors

Nine patients with renal tumors were studied by intraarterial digital subtraction arteriography (IADSA). Embolization was performed in six patients. IADSA was evaluated on the following practical points: vascular mapping, renal vein visualization, and embolization. Vascular mapping by IADSA was satisfactory in eight patients. The limitation of the field of view was the major restricting factor, and a second opacification was necessary in two cases. One case with multiple renal arteries was unacceptable as the lowest renal artery was missed. Renal vein visualization by IADSA with renal artery injection was not reliable due to misregistration artifacts caused by bowel gas. Embolization with IADSA was satisfactory. Significant reductions in contrast load and procedure time were achieved. IADSA was found to be an effective tool in vascular mapping and embolization of renal tumors. Selective renal arteriography to visualize renal veins was better performed with conventional techniques.     

Contrast-enhanced three-dimensional fast-spoiled gradient magnetic resonance angiography of the renal arteries for potential living renal transplant donors: a comparative study with digital subtraction angiography

Preoperative assessment of the arterial anatomy of prospective renal donors is essential. Various non-invasive techniques are used for such evaluation. We conducted this study using contrast-enhanced 3-D fast-spoiled gradient (CE 3-D FSPGR) magnetic resonance angiography (MRA) on a 1.0 Tesla magnet, for preoperative definition of the renal arteries. Forty-five preoperative living renal donors underwent CE 3-D FSPGR MRA of the renal vessels and the results were compared with conventional digital subtraction angiography (DSA). The renal vascular anatomy, both normal and with variations, was satisfactorily defined in all 45 cases with CE 3-D FSPGR MRA. Fifteen cases showed an accessory or aberrant arterial supply. A small aneurysm was shown in one case. All cases compared well with conventional DSA. Our study revealed that CE 3-D FSPGR MRA on a lower field strength magnet is accurate in defining the renal vascular anatomy and its variations.     

Value of image subtraction in 3D gadolinium-enhanced MR angiography of the renal arteries

The objective of this study was to evaluate quantitatively and qualitatively the effect of image subtraction on the image quality of three-dimensional (3D) gadolinium-enhanced MR angiograms of the renal arteries. Breath-hold 3D gadolinium MR angiography (MRA) as well as conventional contrast angiography of the renal arteries was performed on 20 patients with suspected renovascular hypertension. MR angiograms were acquired before and during dynamic infusion of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). Contrast-enhanced images were compared with images that had undergone voxel-by-voxel signal intensity subtraction of contrast-enhanced data from precontrast data. One false positive finding for significant renal artery stenosis was recorded with MRA using conventional angiography as the gold standard. Image subtraction did not alter the diagnosis at MRA in any case. The mean contrast-to-noise ratio (CNR) was significantly higher (P < .05) on the subtraction MR angiograms compared to the nonsubtracted MR angiograms. There was no significant difference in the signal-to-noise ratio (SNR). Qualitative analysis revealed a significant improvement in image quality after image subtraction with respect to visualization of the distal renal arteries. In conclusion, image subtraction improves the quality of renal MRA in terms of both CNR and visualization of the distal renal arteries.     

DSA外周血管造影在婴幼儿中应用

目的 介绍婴幼儿血管造影方法,分析血管造影在婴幼儿疾病诊冶中的应用价值和安全性。方法 临床、CT、MRI诊断为血管瘤,肝肾肿瘤及脑血管疾病共18例,行DSA血管造影术。结果 蔓状血管瘤3例,毛细血管瘤1例,1例为深静脉的先天性回流障碍。肝母细胞瘤3例,肾胚胎瘤1例,肾横纹肌肉瘤1例,1例肝动静脉瘘。2例考虑为原始神经外胚层瘤（PNET）术前脑血管造影,1例为Galen静脉瘤,1例为Sturge—Weber综合征,2例为颅面部的动静脉瘘及动静脉畸形。结论 婴幼儿血管造影是安全可靠的,有着广泛的临床应用价值。     

Digital subtraction angiography of the renal arteries. Prospective comparison with conventional arteriography

Intravenous digital subtraction angiography (IV-DSA) of the aorta and renal arteries was compared with conventional arteriography of 40 patients with 92 renal arteries. Inadequate visualization of the vessel occurred in six renal arteries (6.5%). In arteries adequately imaged, for the evaluation of renal artery stenosis, the sensitivity of IV-DSA was 87.5% (28/32), the specificity 100% (54/54), and the accuracy 95.3% (82/86). Overall, accurate IV-DSA was obtained in 89.1% (82/92) of renal arteries and 85% (34/40) of the patients. IV-DSA is an accurate screening procedure for renal artery stenosis.     

Digital subtraction angiography in the preoperative evaluation of patients with a renal tumor

Inguinal intravenous digital subtraction angiography (DSA) was performed in 14 patients referred for preoperative evaluation of a renal tumor previously diagnosed by CT and ultrasound. Conventional cavography and aortography were used as reference methods for comparison. Both DSA and conventional angiography were carried out following selective arterial injection to the abnormal kidney. The diagnostic value of DSA in examination of the inferior vena cava was generally comparable to that of conventional cavography. Intravenous aortography was unsuccessful in 2 patients due to motion artifacts. In all other patients, the information provided by DSA regarding the aorta, renal arteries and renal veins was similar to that of conventional aortography. Intrarenal vascular detail, however, was far superior on conventional films and was only useful with DSA when intra-arterial injection was implemented. In one of the 12 diagnostic examinations, localization of the renal mass could not be established by intravenous DSA, but was possible in all others. The inguinal approach advocated permits simultaneous inferior vena cavography and intravenous aortography with one single injection of contrast medium; the method is less traumatic than aortography , and does not require hospitalization of the patient. DSA may also be of value in those cases still requiring selective catheterization of the renal arteries, i.e. for angiotherapy . Intra-arterial DSA then allows reduction of the amount of contrast medium and a rapid processing of the images without detriment to the quality of the examination.     

Triphasic helical CT of the kidneys: contribution of vascular phase scanning in patients before urologic surgery.

OBJECTIVE: The purpose of this study was to evaluate the potential benefits of performing vascular phase scanning of the kidneys in addition to unenhanced and parenchymal phase contrast-enhanced CT in patients being examined for urologic surgery. MATERIALS AND METHODS: Parenchymal and vascular phase images from triphasic renal helical CT of 50 patients were sequentially evaluated in a randomized, retrospective fashion by two independent observers. The number of renal arteries and veins and the presence of vein or collecting system anomalies were recorded for each scan phase along with a subjective 10-point-scale score of the visibility of the vasculature and collecting system. Correlation of these findings was made with surgical or angiographic findings in 67 of the 87 kidneys and was made by consensus review in the remaining 20 kidneys. RESULTS: Accessory renal arteries were seen significantly more often (p < .05, chi-square test) on the vascular phase scans. The subjective scores for the visibility of the renal arteries and renal veins were significantly higher on the vascular phase scans (p < .0001, Wilcoxon's rank sum test). The subjective scores for the visibility of the filling of the collecting system and renal pelvis were significantly higher for the parenchymal phase scans, despite the use of a small contrast bolus before each scan (p < .0001, Wilcoxon's rank sum test). CONCLUSION; Triphasic renal CT better reveals the artery and vein anatomy of the kidney than does parenchymal phase imaging only. Triphasic helical CT is indicated in patients undergoing planning for urologic surgery when vascular anatomy is clinically important.