Comprehensive MR imaging in the preoperative evaluation of living donor candidates for laparoscopic nephrectomy: initial experience

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging in the preoperative evaluation of potential living renal donors who are candidates for laparoscopic nephrectomy. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

多层螺旋CT肝脏兼容性血管造影在肝癌介入治疗中的应用价值

目的 探讨多层螺旋CT（MSCT）肝脏兼容性血管造影在肝癌介入治疗中的应用价值。方法 MSCT肝癌CT检查患者45例,于动脉期22s、门静脉期55s行肝脏双期增强扫描,采用MPVR、MIP、VR、SSD重建技术行肝动脉、门静脉兼容性血管成像。其中22例作了肝动脉DSA造影及介入治疗。结果 动脉期肝动脉血管造影（SCTA）显示肿瘤血管31例,肿瘤染色17例,动-门脉分流（APS）9例。门脉期门静脉造影（SCTP）检出肿瘤对门静脉的侵犯25例,门静脉癌栓16例。MSCT显示的肿瘤血管、肿瘤染色、供血动脉的来源分布、APS及门静脉癌栓与DSA图像基本一致。MPVR、VR有利于检出肝癌供血动脉、肿瘤血管、肿瘤染色、APS及门静脉癌栓。结论 MSCT肝脏兼容性SCTA、SCTP血管造影,可为临床及肝癌介入治疗方案的制定提供更多信息。     

肾上腺嗜铬细胞瘤的DSA诊断及危象处理

目的:探讨肾上腺嗜铬细胞瘤的血管造影表现及并发症。方法:收集6例疑诊右侧肾上腺嗜铬细胞瘤病人行腹主动脉及选择性肾上腺动脉造影检查及数字电影摄影。结果:瘤体均由右肾上腺动脉供血。血管造影显示动脉期肿瘤血管增多、增粗、纡曲。2例见静脉早显。实质期染色浓密、不均匀。静脉期仍可见瘤体较长时间染色。2例出现高血压危象,经对症处理,血压趋于稳定。结论:肾上腺嗜铬细胞瘤由肾上腺动脉供血,其富血管性及延长显影的血管造影特点,有助于区别其它腹腔及腹膜后肿块。术中应密切监测血压,出现危象应及时处理。     

Contrast-enhanced MR angiography in patients after kidney transplantation

The aim of this study was to investigate the value of a contrast-enhanced 3D MR angiography in detecting postoperative vascular complications after kidney transplantation in comparison with digital subtraction angiography (DSA). Forty-one patients who underwent a kidney transplantation were examined with MR angiography and DSA. Contrast-enhanced MR angiography was performed as a dynamic measurement with one precontrast and three postcontrast measurements. Maximum intensity projection reconstructions were performed for all postcontrast data sets after DSA. The results were evaluated by two independent observers who were unaware of the DSA results. Twenty-three hemodynamically significant arterial stenoses were identified with DSA in the iliac arteries ( n=7), the renal allograft arteries ( n=12), and in their first branches ( n=4). For a patient-based analysis the sensitivity and specificity, respectively, for observer 1 were 100 and 97%, and for observer 2, 100 and 93%. Respective data were 100 and 100% after a consensus evaluation by two observers. Complications involving the renal veins were detected in 2 cases and perfusion defects of the kidney parenchyma were detected in 4 cases. Contrast-enhanced MR angiography is a reliable method in identifying postoperative arterial stenoses after kidney transplantation. In addition, dynamic MR angiography can be helpful in detecting venous complications and perfusion defects in kidney allografts.     

CT Angiography for Living Kidney Donors: Accuracy, Cause of Misinterpretation and Prevalence of Variation

OBJECTIVE: To determine the accuracy of the use of multi-detector row CT (MDCT) to predict vascular anatomy in living kidney donors and to reveal the prevalence of vascular variations in a Korean population. MATERIALS AND METHODS: A total of 153 living kidney donors that had undergone preoperative CT and nephrectomy, either with open or laparoscopic surgery, were selected retrospectively. The initial CT results were compared with the surgical findings and repeated review sessions of CT scans were performed to determine the causes of mismatches in discordant cases. RESULTS: The accuracy of CT angiography was 95% to predict the number of renal vessels. Four arteries and two veins were missed during the initial CT interpretation due to perception errors (for two arteries and two veins) and technical limitations (two arteries). The prevalence of multiple renal arteries and veins, early branching of a renal artery and late confluence of a renal vein were 31%, 5%, 12%, 17%, respectively. The circumaortic renal vein and the bilateral inferior vena cava were found in two cases each (1.3%). One case (0.7%) each of a retroaortic renal vein and a supradiaphragmatic originated renal artery were found. CONCLUSION: MDCT provides a reliable method to evaluate the vascular anatomy and variations of living kidney donors.     

Preoperative assessment of intracranial tumors with perfusion MR and a volumetric interpolated examination: a comparative study with DSA

BACKGROUND AND PURPOSE: In evaluating intracranial tumors, a safe low-cost alternative that provides information similar to that of digital subtraction angiography (DSA) may be of interest. Our purpose was to determine the utility and limitations of a combined MR protocol in assessing (neo-) vascularity in intracranial tumors and their relation to adjacent vessels and to compare the results with those of DSA. METHODS: Twenty-two consecutive patients with an intracranial tumor who underwent preoperative stereoscopic DSA were examined with contrast-enhanced dynamic T2*-weighted perfusion MR imaging followed by a T1-weighted three-dimensional (3D) MR study (volumetric interpolated brain examination [VIBE]). The maximum relative cerebral blood volume (rCBV) of the tumor was compared with tumor vascularity at DSA. Critical vessel structures were defined in each patient, and VIBE images of these structures were compared with DSA findings. For full exploitation of the 3D data sets, maximum-intensity projection algorithms reconstructed in real time with any desired volume and orientation were used. RESULTS: Tumor blush scores at DSA were significantly correlated with the rCBV measurements (r = 0.75; P <.01, Spearman rank correlation coefficient). In 17 (77%) patients, VIBE provided all relevant information about the venous system, whereas information about critical arteries were partial in 50% of the cases and not relevant in the other 50%. CONCLUSION: A fast imaging protocol consisting of perfusion MR imaging and a volumetric MR acquisition provides some of the information about tumor (neo-) vascularity and adjacent vascular anatomy that can be obtained with conventional angiography. However, the MR protocol provides insufficient visualization of distal cerebral arteries.     

Tumor vascular signals in renal masses: detection with Doppler US

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.     

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.     

MSCT肾动脉成像在肾脏占位性病变诊断和术前评估中的价值

目的探讨MSCT肾动脉成像（CTRA）在肾脏占位性病变诊断和术前评估中的价值。方法回顾分析我院经PhilipsBrilliance40层螺旋CT扫描发现肾脏占位性病变的患者42例,用后处理工作站重建肾动脉,观察病变对邻近肾动脉分支的影响、肿瘤血管及类似肿瘤染色等方面的情况,同时观察肾动脉有无变异及其它病变。结果肾细胞癌（RCC）25例,其中14例可见邻近肾动脉分支受压,10例可见肾动脉受侵,6例可见1支或多支肿瘤供血动脉;’肾血管平滑肌脂肪瘤（AML）6例,其中2例可见肾动脉分支受压,1例见供血动脉;肾囊肿患者11例,1例较大者压迫邻近肾动脉及其分支,无供血动脉及肿瘤血管显示。结论CTRA不仅有助于。肾脏占位性病变的定性诊断,还能在显示肾动脉解剖及变异、健侧。肾动脉有无病变等方面提供有价值的补充信息,是安全、可靠、行之有效的影像学检查方法。     

Magnetic resonance angiography and colour-Doppler sonography in the evaluation of abdominal aortic aneurysms

This prospective study was aimed at comparing the diagnostic accuracy of magnetic resonance angiography (MRA) with colour-Doppler ultrasonography (colour-Doppler US) in the assessment of abdominal aortic aneurysms (AAA). Twenty patients with abdominal aortic aneurysms underwent MRA, colour-Doppler US, digital subtraction angiography (DSA) and CT. The MRA technique and colour-Doppler findings were compared with DSA as well as surgical and pathological findings, which were considered as the gold standard. In 6 patients who refused surgery, CT and DSA were considered as the gold standard. The MRA technique always correctly assessed the size and site of the aneurysms, the involvement of the renal and common iliac arteries, the course of the left renal vein, the thrombotic component and the calcifications. Colour-Doppler US always correctly assessed the size and site of the aneurysms, the thrombotic component and calcifications and the involvement of the iliac arteries. Our preliminary results suggest that MRA together with colour-Doppler US represents a valid alternative to invasive imaging in the assessment of AAA. Received 18 July 1996; Revision received 4 December 1996; Accepted 11 February 1997     

16层螺旋CT肾脏皮质早期扫描及CTA在肾癌诊断和术前评估中的价值

目的:探讨16层螺旋CT肾脏皮质早期扫描及血管成像在肾癌定性诊断及术前评估中的价值。材料和方法:采用Siemens16层螺旋CT机,对超声提示有肾占位性病变的46例病人进行扫描,利用获得的皮质早期容积数据,显示肾占位性病变对邻近肾内动脉分支的影响、肿瘤血管及类似肿瘤染色等方面的情况,同时显示肾动脉有无变异和其他病变。结果:28例肾癌中23例(82.1%)在皮质早期病灶即呈明显强化,实质期强化程度迅速下降;25例(89.3%)可见邻近动脉分支的受侵改变;21例(75.0%)可见确切的一支或多支粗大的供血动脉,以及瘤体内可见明显的肿瘤血管影或血池影;23例(82.1%)出现类似血管造影的肿瘤染色表现;2例(7.1%)患肾出现静脉早显;3例(10.7%)病人中患肾出现副肾动脉,其中1例为两支;1例(3.6%)病人患侧肾动脉重度狭窄,健侧肾动脉中度狭窄。8例血管平滑肌脂肪瘤中,仅2例(25%)见供血动脉影,其中1例供血动脉增粗,均未见相邻动脉分支破坏、明显肿瘤血管、血池及肿瘤染色改变。10例囊肿,仅表现为相邻肾动脉分支受压移位、拉直变细。结论:应用优化方案扫描进行皮质早期扫描及CTA重建,不仅为肾癌的定性诊断提供了重要的信息,对肾癌的术前评估也具有重要的补充价值。     

保留肾单位手术术前MSCT三种后处理技术的探讨

目的：探讨多层螺旋CT三种后处理技术对术前评价保留肾单位手术（NSS）的价值。方法：对30例拟行NSS的患者进行多层螺旋CT（MSCT）扫描及三种后处理成像,观察肾脏位置、肿瘤的部位、范围及与肾动静脉、集合系统的关系,并与术中对照。结果：MSCT及后处理成像清楚显示了30例患者共40个肿块。三维CT成像共显示了58条肾动脉中的55条（94．8％）,显示了56条肾静脉中的53条（94．6％）。三种技术对NSS术前评判效果良好,但不尽相同,VR优于MIP和SSD（P〈0．05）,MIP优于SSD（P〈0．01）。结论：MSCT三种后处理技术的综合应用对NSS术前评价具有较高的价值。     

Multidetector–row CT angiography of renal artery stenosis in 50 consecutive patients: prospective interobserver comparison with DSA

PURPOSE: The purpose of this study was to establish the diagnostic value of multidetector-row computed tomography (MDCT) angiography compared with digital subtraction angiography (DSA) for detection and quantification of both main and accessory renal artery stenosis in patients with secondary hypertension. MATERIALS AND METHODS: Fifty consecutive patients scheduled for DSA were considered candidates for MDCT angiography. In all patients, MDCT angiography of the abdominal aorta was performed before DSA. For the purpose of interpretation, the arteries were separately interpreted either with DSA or MDCT angiography in order to provide qualitative and quantitative information. For qualitative evaluation, one experienced reader graded the opacification of renal arteries as excellent, good or poor; for quantitative evaluation, MDCT and DSA were independently evaluated for the number of renal arteries and the presence, location and degree of stenosis in random order by three readers. On the basis of consensus readings, calculations of sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for detection of degree of stenosis were made by using DSA findings as the standard of reference. Interobserver variability was also assessed. RESULTS: With regard to qualitative analysis, arterial enhancement was considered excellent in 39 patients and good in 11. For quantitative analysis, 73 arteries were classified as normal with DSA. Although 72 of these were also classified as normal with CT angiography, one was overestimated by one grade; at DSA, 16 arteries were classified as moderately stenotic; in two arteries, there was an overestimation of one grade. Perfect correlation was achieved for the diagnosis of occlusion. In two patients, all three readers detected multiple severe stenoses on both modalities, with a "string-of-beads" appearance typical of fibromuscular dysplasia. Accessory arteries were correctly identified as such by all three readers on either DSA or MDCT. Levels of sensitivity, specificity and accuracy regarding degree of stenosis were 100%, 98.6% and 96.9%, respectively, with PPV and NPV of 97.6% and 100%, respectively. When we considered significant arterial stenosis (50%-100% luminal narrowing), sensitivity, specificity and accuracy were 100%, 97.3% and 97.8%, respectively, with a PPV and NPV of 98.2% and 97.8%, respectively. For all observers, interobserver agreement was almost perfect (k=0.81-1) for both MDCT and DSA, with a k value between 0.82 and 0.95. CONCLUSIONS: MDCT angiography is very accurate and robust, even for the assessment of renal artery stenosis, and has the potential to become a viable substitute, in most cases, for diagnostic catheter-based DSA.     

Abdominal venous system: assessment using MR

Twenty-five patients with known or suspected evidence of venous disease based on results of computed tomography, angiography, or ultrasound were imaged with magnetic resonance (MR) to determine the MR characterization of venous abnormalities. MR findings were proved by laparotomy or autopsy in 18 of 25 cases. In seven of 25 patients in whom only biopsy was performed, the MR findings were correlated with findings from other radiologic tests. On MR, the inferior vena cava (IVC), portal vein, and their major tributaries were seen in all but two cases. In those two, identification of collaterals led to the correct diagnosis of splenic vein thrombosis in one case and left renal vein thrombosis in another. MR imaging helped identify intraluminal thrombi in the IVC (12 of 12 cases), portal vein (two of two cases), renal veins (seven of seven cases), superior mesenteric vein (one case), and iliac veins (seven of seven cases). Intraluminal signal intensity secondary to slow blood flow seen in five patients was always differentiated from the thrombus. MR imaging helped identify correctly the nature of the thrombus in 11 of 16 patients. In five patients, the differentiation between tumor thrombus and blood clot thrombus was not possible. Involvement of the IVC wall by tumor was seen in four cases. MR imaging also accurately depicted slow flow in obstructed or constricted veins; encasement, compression, or displacement of veins without intraluminal occlusions; and the presence of venous collaterals. The MR imaging evaluation of venous abnormalities is accurate, easily performed, and will probably become an important application.     

Preoperative evaluation of potential living related kidney donors with high-spatial-resolution magnetic resonance (MR) angiography at 3 Tesla: comparison with intraoperative findings

PURPOSE: The purpose of this prospective study was to determine the feasibility and accuracy of high-spatial-resolution MR imaging at 3 Tesla (T) in the preoperative evaluation of potential living related kidney donors. MATERIALS AND METHODS: Eighteen potential donors (8 men, 10 women; mean age, 50.1 +/- 14.2 years) for renal transplantation were evaluated with 3 T MR imaging. A high-spatial-resolution 3-dimensional (3D) gradient-echo MR angiography (repetition time/echo time, 3.0/1.14 ms; flip, 19-23 degrees; matrix, 512; slice thickness, 1.0 mm) using parallel acquisition technique (GRAPPA) with an acceleration factor of 3 was performed on a whole body scanner. Images were evaluated in a prospective and blinded fashion by 2 MR radiologists. The number of renal arteries, presence of early branches (defined as a branch arising within 2 cm of the main renal ostium), and renal artery stenosis were analyzed. The renal parenchyma, collecting system and ureters, were evaluated on the MR urograms. Interpretation of MR images were compared with surgical findings. RESULTS: Based on MR angiography data sets, a total of 36 main and 9 accessory renal arteries was found. There were 5 renal arteries presenting an early branching (相似文献   

MR digital subtraction angiography in the diagnosis of meningiomas

OBJECTIVE: MR digital subtraction angiography (DSA) is a technique for demonstrating the vasculature combining a rapid two-dimensional T1-weighted sequence with a bolus injection of gadolinium. We attempted to determine its contribution to the diagnosis of intracranial meningiomas. METHODS AND PATIENTS: MR DSA was performed in 18 patients with meningioma as well as in 28 patients with other tumors. The findings were analyzed regarding demonstration of tumor stain and tumor-related vessels. RESULTS: All meningiomas except one were visualized as a homogeneous and intense stain. Feeding arteries were visualized in 2 patients, and draining or abnormal veins in three. In 21 of the 28 patients with other tumors, tumor stains of varying degrees were demonstrated. CONCLUSION: MR DSA can serve as an adjunct to routine MR imaging, because it enables assessment of the hemodynamics of meningiomas and facilitates its differential diagnosis from other tumors.     

Sarcoma of the kidney: angiographic features.

Sarcomas of the kidney are highly malignant neoplasms. Abnormal vascularity can be detected in almost all types of sarcomas, but arteriovenous shunting, pooling of contrast material, and tumor staining are seldom present. Extension to renal vein and inferior vena cava may occur. While angiographic findings in our seven cases of renal sarcomas were nonspecific, this diagnosis should be considered in a relatively hypovascular neoplasm especially when the capsular arteries contribute considerably to the vascular supply. Nevertheless, statistically the most likely diagnosis of a hypovascular mass is renal cell carcinoma. Angiographic studies do not alter the management of the patient but merely suggest the diagnostic possibility of sarcoma. Angiographic diagnosis of different histologic types of sarcomas is not possible.     

Renal digital subtraction angiography

Digital subtraction angiography (DSA), a new computer-assisted radiographic procedure, has recently been applied to the evaluation of the kidney and in the screening of patients with renal vascular hypertension. The efficacy of the method in the evaluation of the anatomy of proximal renal arteries is in the 80–90% range; however, DSA is less effective in the evaluation of renal mass lesion. In the present state of DSA development, the method has a place in screening for renal artery stenosis (RAS). Further development, particularly improvement in spatial resolution, will be necessary before this procedure can substitute for renal angiography, in the evaluation of renal masses or in some cases of RAS.     

螺旋CT肾动脉成像与数字减影血管造影的对比分析

目的:客观评价螺旋CT肾动脉成像的临床应用价值.材料和方法:从本院螺旋CT肾动脉成像(CTRA)资料中选取31例曾做过DSA肾动脉造影(含动脉成形和支架放置术)者,CTRA和DSA图像分别先由两位医师独立观察.分析内容包括解剖变异、有无狭窄及进行狭窄程度分级.最后将结果进行对比分析.结果:CTRA发现狭窄血管33支,其中31支经DSA证实(2支假阳性).符合率为94%.清楚显示5支副肾动脉(经DSA证实).结论:CTRA是肾性高血压筛选的可靠方法并可取代DSA作为首选检查方法.     

Digital subtraction angiography in the diagnosis of arterial complications after renal transplantation

Digital subtraction angiography (DSA) was used to study arterial complications following renal transplantation in 33 patients. The results were compared with clinical follow-up and in three cases with conventional angiography. In 9 per cent using DSA (3 cases) we experienced inadequate visualization of the renal arteries of the graft; in 91 per cent, the visualization was diagnostically sufficient. In 53 per cent, we discovered an arterial stenosis of the main artery or segmental artery and in one case an AV-fistula. No morbidity resulted during the procedure. We consider DSA to be the best non-invasive method in the evaluation of patients with suspected renal artery stenosis following kidney transplantation.