Black blood magnetic resonance angiography with Dy-DTPA polymer: Effect on arterial intraluminal signal intensity,lumen diameter,and wall thickness

Four rabbits in which atherosclerotic disease was induced by diet and balloon angioplasty underwent conventional angiography and MR angiography (MRA) using a black blood pulse sequence before and 10 minutes after the iv injection of a macromolecular contrast agent, NC 100283 (1.0 mmol/kg), a dysprosium diethylenetriaminepentaacetic acid hexamethylenediamine copolymer (Dy-DTPA polymer). Intraluminal signal intensity, apparent wall thickness, and lumen size measurements of the aorta and proximal common iliac arteries on precontract MRA images were compared with postcontrast images. Aortic lumen diameter measurements on the precontrast and postcontrast MRA studies were compared with lumen diameters from conventional angiograms. Intraluminal signal intensity decreased on postcontrast MRA images compared with precontrast images, with an average loss of signal equal to 29% (P < .05). Apparent wall thickness decreased by 24% (P < .05). Lumen diameter and area were generally larger (average of 15% and 33%, respectively) on postcontrast MRA images than on precontrast images. Aortic lumen diameter measurements from postcontrast MRA agreed closely (95% confidence interval of the mean difference was ?.2 to .3 mm), and precontrast MRA images tended to underestimate aortic lumen diameter (95% confidence interval of the mean difference was .3 to .8 mm) compared with conventional angiography. Postcontrast MRA with NC 100283, a macromolecular Dy-DTPA contrast agent, provides more accurate assessment of aortic lumen diameter than precontrast MRA, using conventional angiography as the standard reference.     

Prospective evaluation of peripheral arterial occlusive disease by 2D MR subtraction angiography

The purpose of this study was to assess the diagnostic value of two-dimensional (2D) MR subtraction angiography of lower extremities in patients with symptomatic peripheral arterial occlusive disease with conventional angiography as the standard of reference. Twenty patients were prospectively included. 2D subtraction MR angiography (MRA) consisted of multisection gradient-recalled echo (GRE) acquisitions with the shortest TE available on our machine (4 msec), obtained in the coronal plane before and after intravenous bolus administration of gadolinium chelate. MR images were reconstructed after subtraction with a maximum-pixel-intensity-projection (MIP) algorithm. MRA was performed in all cases 1–4 days before diagnostic angiography. In a prospective blinded analysis, the number and location of significant (ie, >50%) stenoses and occlusions were evaluated for each vascular segment. Sensitivity and specificity were used to evaluate MRA data. Significant stenoses (38 of 46, 83%) and occlusions (66 of 67, 99%) seen at conventional angiography were identified with MRA. The sensitivity and specificity of MRA for determination of stenoses >50% or occlusions was 100% and 97%, respectively. The location and extent of stenoses and/or occlusions on MRA and angiograms were well correlated (kappa values, r = .73, P < .05). Contrast 2D MR subtraction angiography, by providing comparable information to that of conventional angiography, is well suited to evaluate the presence and severity of atherosclerotic lesions of the lower limbs.     

Contrast-enhanced 3D MRA with centric ordering in k space: A preliminary clinical experience in imaging the abdominal aorta and renal and peripheral arterial vasculature

The objective of this study was to determine the clinical utility of a contrast-enhanced, centric reordered, three-dimensional (3D) MR angiography (MRA) pulse sequence in imaging the abdominal aorta and renal and peripheral lower extremity arteries. Twenty-eight MRA studies were performed on 23 patients and four volunteers at 1.5 T using a 3D contrast-enhanced, centric reordered pulse sequence. In 20 patients, the abdominal aorta and renal arteries were imaged, and in seven patients, the lower extremity arteries were imaged. In 19 patients, a total of 51 renal vessels were evaluated (33 renal arteries using .1 mmol/kg of gadopentetate dimeglumine and 18 renal arteries using .2 mmol/kg of gadoteridol). A total of 70 peripheral arterial segments were assessed using .2 mmol/kg of gadoteridol. Correlation with conventional angiography was made for the following 14 cases: renal artery stenosis (four cases), abdominal aortic stenosis (one case), arteriovenous fistula in a transplant kidney (one case), renal arteriovenous malformation (one case), common iliac artery aneurysms (one case), and peripheral lower extremity (six cases). Of the 70 peripheral arterial segments evaluated, in 35, there was correlation with x-ray angiography. The mean percent of aortic signal enhancement was significantly higher in the .2 mmol/kg dose group (370.8 ± 190.3) than in the .1 mmol/kg dose group (184.5 ± 128.9) (P = .02). However, there was no apparent difference between the two doses for visualization of the renal and accessory renal arteries. There was concordance between the contrast-enhanced 3D MRA studies and conventional angiography in all cases of renal artery and peripheral arterial stenoses and occlusions, including visualization of reconstituted peripheral arterial segments. There was no evidence of spin dephasing effects at sites of stenoses on the 3D contrast-enhanced MRA studies. Contrast-enhanced, centric reordered, 3D MRA can rapidly image the abdominal aorta and renal and accessory renal arteries, as well as peripheral lower extremity arteries, with high resolution. Accurate depiction of the vascular lumen at sites of stenosis is made because of the lack of spin dephasing effects, even with hemody-namically significant stenoses. Additional larger clinical trials are required with this promising technique.     

Balloon occlusion femoral angiography prior to in-situ saphenous vein bypass

The advent of thein situ saphenous vein bypass procedure for peripheral lower extremity ischemic disease has placed new demands on the angiographer. It is imperative that the small runoff arteries of the calf be seen beyond the level of the ankle to include evaluation of the patency of the plantar arch. Balloon occlusion femoral angiography (BOFA) has been used in 45 consecutive lower extremities in 40 patients referred for proposedin situ saphenous vein bypass; excellent visualization of the plantar arch on the first run was obtained in 40 of 45 extremities (88.9%). The patients included 35 (87.5%) insulin-dependent diabetics with severe proximal arterial disease. Initially,in situ candidates were studied using conventional “runoff” methods; it was rarely possible to visualize the upper trifurcation vessels let alone the plantar arch by this conventional method. The BOFA method was used to provide excellent visualization of the plantar arch and foot arteries. It permits use of smaller contrast medium volumes, provides all the arteriographic anatomy on one 51 inch long film, and is safe.     

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.     

Contrast-enhanced MR angiography of abdominal vessels: Is there still a role for angiography?

The purpose of this review article is to describe recent advantages in contrast-enhanced (CE) three-dimensional (3D) magnetic resonance angiography (MRA) in comparison with other vascular imaging techniques, and to discuss their current clinical applications for the imaging of abdominal vessels. Principles and technical considerations are presented and clinical applications are reviewed for different vascular diseases. In ruptured aortic aneurysms and acute dissections CT is the method of first choice. Contrast-enhanced 3D MRA can be well used for therapeutic planning and follow-up in patients with stable disease. A comprehensive MR examination including CE 3D MRA, MR urography and MR nephrogram has the potential to replace the conventional studies for the evaluation of renal vascular disease. It is an accurate method for imaging the origins of coeliac and superior mesenteric arteries, although the image resolution is too low for reliable assessment of the inferior mesenteric artery. Contrast-enhanced 3D MRA has emerged as the method of choice for studying the portal venous system in liver transplant recipients, in patients with portal hypertension and in cases with abdominal tumours for preoperative evaluation. Additional non-invasive flow measurements are useful in monitoring portal hypertension. The abdominal veins can be well imaged using unenhanced MR techniques. Imaging may be facilitated with intravascular contrast media. Contrast-enhanced 3D MRA can replace intra-arterial DSA for diagnosis, therapy planning and follow-up in patients with abdominal vascular disease. Catheter-based arteriography will still be used for interventional procedures such as percutaneous transluminal angioplasty, stent placement and embolisation.     

Evaluation of the iliac arteries: Comparison of two-dimensional time of flight magnetic resonance angiography with cardiac compensated fast gradient recalled echo and contrast-enhanced three-dimensional time of flight magnetic resonance angiography

We compared dynamic contrast-enhanced three-dimensional time of flight (3DTOF) magnetic resonance angiography (MRA) with two-dimensional time of flight (2DTOF) MRA with cardiac compensated fast gradient recalled echo (C-MON) and conventional angiography (CA) when it was available. C-MON re-orders the normal data acquisition to minimize ghosting artifacts generated by pulsatile flow. The initial phase of the study involved optimization of parameters and comparison C-MON with no C=MON in eight patients and volunteers. The final phase of the study involved 53 patients who were imaged with contrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON. Thirty of these patients also had CA. In the initial phase, 2DTOF MRA with C-MON was found to be equal (n = 3) or superior (n = 5) to 2DTOF without C-MON. In the final phase, the agreement among all imaging modalities varied from substantial to almost perfect (Cohen's _K = .6-.83). The lowest agreement was using 2DTOF to evaluate the external iliac segments. The among suggested treatments varied from substantial to almost perfect for all imaging modalities (Cohen's _K = .73–93). The diagnostic efficacies of 2DTOF with C-MON and contrast-enhanced 3DTOF were high overall, with the lowest value being a specificity of 63% for one reader in the evaluation of an external iliac segment using 2DTOF. In summary, 2DTOF with C-MON helped to eliminate artifacts due to pulsatility in the iliac arterial segments. In our experience, both dynamic constrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON performed well in the evaluation of the iliac arteries. Both studies have high interobserver agreement and high diagnostic efficacy. Contrast-enhanced 3DTOF MRA should be reserved for situations in which the iliac vessels are extremely tortuous or occluded or the external iliac segments are poorly seen.     

肾动脉高分辨力三维增强磁共振血管成像术:透视触发和并行采集技术使用初探

目的:评估透视触发和并行采集技术用于肾动脉高分辨力三维增强磁共振血管成像术的可行性和对肾动脉的显影诊断效果。方法:90例临床诊断或怀疑肾动脉或腹主动脉病变的患者行高分辨力肾动脉三维增强磁共振血管成像(3D CE MRA)。使用透视触发软件启动肾动脉3D CE MRA扫描,扫描采用K空间中心填充法和加速因子为2的并行采集技术。分析图象质量和病变显示情况,并与其它检查结果对照。结果:肾动脉3D CE MRA显示了90例患者共810支动脉段(100%显示率),平均显示等级为3.88。3D CE MRA显示8例11支副肾动脉,显示等级均为4.0。肾动脉段级分支的显示率为73%(66/90例)。所有病例在动脉显示区静脉均未显影或显影很淡,平均等级为0.20。3D CE MRA发现639支动脉段正常;66支动脉段管壁不规则;55支动脉段轻度狭窄;37支动脉段严重狭窄;2支动脉段闭塞;11支动脉段动脉瘤形成。其中96支肾动脉存在狭窄,11支副肾动脉均正常。共有43例病例,肾动脉3D CE MRA与其它血管成像技术作了比较,3D CE MRA的检查结果与之完全符合。结论:透视触发并行采集肾动脉高分辨力3D CE MRA简单可行,成像时间短,空间分辨力高,能清楚显示肾动脉且无静脉污染。     

Contrast-enhanced,k-space-centered,breath-hold MR angiography of the renal arteries and the abdominal aorta

The purpose of this study was to evaluate the capability of contrast-enhanced breath-hold fast imaging with steady-state precession (FISP) three-dimensional MR angiography (MRA) to detect stenotic lesions of the abdominal aorta, the renal arteries, and the iliac arteries by using a k-space-centered 20-ml gadolinium-diethylene pentaacetic acid (Gd-DTPA) bolus. Fifty patients were studied before conventional x-ray angiography. Contrast-enhanced breath-hold FISP three-dimensional MRA was applied in the coronal view, centered at the renal arteries. Twenty ml of Gd-DTPA was used in all subjects. A test bolus was applied to determine the injection time for the k-space-centered bolus injection. Of 300 segments, 284 segments were classified correctly, 11 were overestimated, and five were underestimated. Sensitivity was 98%, specificity was 96%, positive predictive value was 96%, negative predictive value was 98%, and accuracy was 97%. Of the 50 patients studied, 43 were staged correctly. No venous overlay was seen in 31 patients; partial overlay was seen in 16 patients, and venous structure overlay obscuring arterial anatomy was found in two patients. Six of nine accessory renal arteries could be identified by MRA. Intraobserver variability was .94. This study has shown the ability of contrast-enhanced breath-hold FISP three-dimensional MRA to detect and grade vascular lesions in the abdominal aorta and the renal arteries. The method may serve as a screening tool in the future.     

Comprehensive MR angiography of the lower limbs: a hybrid dual-bolus approach including the pedal arteries

The purpose of this study was to include the pedal vasculature into the coverage of peripheral multistation magnetic resonance angiography (3DceMRA). A total of 216 patients suffering from peripheral vascular disease were examined with a modified hybrid dual-bolus technique. The cruropedal arteries were acquired first with two sagittal slabs and time-resolved 3D sequences. Then the aortofemoral vessels were visualized using the bolus-chase technique and a second contrast injection. Interventional procedures were performed in 104 patients, and in 69 of those, the cruropedal vessels were also examined with digital subtraction angiography (iaDSA). Using 3DceMRA, the cruropedal arteries were displayed with both excellent and good quality in 95% (205/216 cases), and without any venous overlay in 94% (203/216 cases). The aortofemoral vessels were not jeopardized by the first contrast injection. With iaDSA as the standard of reference, observed sensitivity of 3DceMRA was found in ranges from 80% (29%, 99%) to 100% (86%, 100%) for assessing significant stenoses, and observed specificity ranged between 93% [80%, 98%] and 100% (82%, 100%). In conclusion, hybrid dual-bolus 3DceMRA significantly reduces the limitations of standard single-bolus 3DceMRA in anatomic coverage and temporal resolution of the cruropedal arteries, thus providing high-quality images of the entire peripheral vasculature.     

Peripheral arterial disease. Contrast-enhanced 3D MR angiography of the lower leg and foot compared with conventional angiography

PURPOSE: To determine whether contrast-enhanced 3D MR angiography (CE MRA) could replace digital subtraction angiography (DSA) for the evaluation of atherosclerotic peripheral vascular disease of the lower leg and foot. MATERIAL AND METHODS: Thirty-five patients with symptoms of atherosclerotic disease of the leg were examined prospectively with CE MRA of the foot and the lower legs as well as with DSA from the aorta to the pedal arches. The MRA technique was focused on optimal imaging of the arteries of the foot. RESULTS: The agreement between CE MRA and DSA for grading of stenosis was moderate to good (weighted kappa-values 0.48-0.80). The sensitivity of CE MRA for detection of significant stenosis (> or = 50%) was 92% and the specificity was 64% with DSA as gold standard. CONCLUSION: CE MRA is a fairly accurate method for the demonstration of atherosclerotic disease below the knee including the pedal arches. It can replace DSA for the assessment of distal arteries in patients with impaired renal function. However, image quality and resolution still needs to be improved before CE MRA can become the method of choice in all patients.     

Contrast-enhanced subtraction MR angiography in occlusive disease of the pelvic and lower limb arteries: results of a prospective intraindividual comparative study with digital subtraction angiography in 76 patients.

PURPOSE: The purpose of this work was to evaluate the feasibility and clinical use of MR angiography (MRA) for examining the pelvic and lower limb arteries in patients with arterial occlusive disease. METHOD: Seventy-six patients with clinical signs of peripheral arterial occlusive disease were included in the study. MRA was performed using a fast contrast-enhanced high-resolution 3D technique that covered the area from the distal abdominal aorta to the distal lower limbs in two examination steps. RESULTS: In all patients, diagnostic images comparable with those of conventional intraarterial digital subtraction angiography (DSA) could be obtained. No false-negative findings were seen in the iliac, femoral, or popliteal arteries. Ten to 16% of the mild stenoses and 6-14% of the severe stenoses, mainly in the crural vessels, were overgraded compared with intraarterial DSA. Particularly in patients with proximal severe obstructions or occlusions, the crural segments could be depicted more clearly due to decreased arterial runoff in conventional angiography. CONCLUSION: The consistency of the excellent depiction of the vascular territories of the distal aorta and the pelvic and lower limb arteries in a standardized setting suggests great potential for the use of MRA in the primary diagnosis of peripheral arterial occlusive disease.     

Gadolinium-enhanced breath-hold three-dimensional time-of-flight MR angiography of the abdominal and pelvic vessels: The value of ultrafast MP-RAGE sequences

MR angiography (MRA) was performed in 50 consecutive subjects (mean age, 59 years), who had been referred for abdominal MRA, on a 1.5-T superconductive unit that used a body phased-array coil. Three breath-hold three-dimensional sequences were evaluated both in phantom and clinical studies: (a) standard fast three-dimensional gradient-echo sequence (TR = 15, TE = 6; imaging time, 32 seconds), (b) ultrafast three-dimensional gradient-echo sequence (TR = 8.2, TE = 3; imaging time, 18 seconds), and (c) ultrafast magnetization-prepared (MP) rapid acquisition gradient echo (RAGE) (TR = 5.8, TE = 2.9, inversion time [TI] = 20; imaging time, 15 seconds). The initial 30 patients were randomized into three groups by three separate sequences. For the remaining 20 patients, ultrafast-gradient-echo and ultrafast MP-RAGE sequences were performed. Conventional angiography was performed on 36 patients. Signal measurements of the phantom and clinical images of the aorta, visceral branches of the aorta, iliac arteries, inferior vena cavae, and portal veins were performed. The overall image quality and background fatty tissue contrast of the vessels were rated subjectively. Comparison of images between MRA and conventional angiography also was performed. The contrast between the vessels and background fatty tissue was significantly higher in the ultrafast MP-RAGE sequence in both quantitative and qualitative analysis, and image-quality ultrafast MP-RAGE was superior to the other two sequences (P < .01). The aorta and iliac arteries could be visualized in all pulse sequences, and abnormalities of these vessels were diagnosed correctly. The renal artery was visualized more clearly with the two ultrafast sequences.     

Total-body 3D magnetic resonance angiography influences the management of patients with peripheral arterial occlusive disease

High-resolution total-body 3D MR angiography (MRA) has recently become available, revealing additional clinically relevant disease in patients with peripheral arterial occlusive disease (PAOD). However, the actual impact of total-body MRA on patient management in patients with PAOD has not been investigated so far. Two hundred forty-nine consecutive patients with angiographically proven PAOD were prospectively examined by means of contrast-enhanced total-body 3D MRA on a 1.5-T MR scanner. All correlative imaging studies performed within 60 days of total-body MRA were included in the efficacy analysis. Additional clinically relevant disease (luminal narrowing >50%, aneurysmal changes or dissections) was found in 73 segments (52 patients), including the renal arteries (36 segments), carotid arteries (28 segments), subclavian arteries (four segments) and abdominal aortic aneurysms (AAA) (five segments). Of the 73 segments, 36 were deemed necessary for further investigation by means of focused MRA examinations; the diagnosis was confirmed in all cases. Within the 60-day follow-up period, interventional or surgical therapy outside the peripheral arterial tree was performed in nine patients (11 segments), including carotid endatherectomy and renal artery angioplasty. The outlined total-body 3D MRA approach permits a comprehensive evaluation of the arterial system in patients with atherosclerosis and does indeed have an impact on patient management in patients with PAOD.     

Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA.

Introduction/objectives: Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol. Methods and patients: Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%). Results: Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%. Discussions and conclusions: Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.     

First-pass contrast-enhanced magnetic resonance angiography in humans using ferumoxytol, a novel ultrasmall superparamagnetic iron oxide (USPIO)-based blood pool agent

PURPOSE: To evaluate the feasibility of first-pass contrast-enhanced magnetic resonance angiography (MRA) using ferumoxytol in humans. MATERIALS AND METHODS: First-pass and equilibrium phase MRA were performed using ferumoxytol in one healthy volunteer and 11 patients with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence. The examined vessels included carotid arteries, thoracic aorta, abdominal aorta, and peripheral arteries. A dose of either 71.6 micromol Fe/kg (n = 9), or 35.8 micromol Fe/kg (n = 3) was used. Based on a phantom study, the agent with initial concentration of 537.2 micromol Fe/mL was diluted by either four-fold (134.3 micromol Fe/mL) or eight-fold (67.1 micromol Fe/mL) for first-pass MRA. RESULTS: All subjects completed their studies without adverse events. First-pass MRA showed selective arterial enhancement, with both arterial and venous enhancement on delayed acquisitions. Selective venous enhancement could be obtained by subtraction of arterial phase images from equilibrium phase images. The findings in ferumoxytol MRA were consistent with the results of original vascular tests. CONCLUSION: Our preliminary experience supports the feasibility of first-pass MRA with ferumoxytol. Satisfactory arterial enhancement during first-pass imaging is obtained with injection of diluted contrast agent. With ferumoxytol, arteries and veins can be selectively depicted in a single exam.     

Proximal coronary artery stenosis: Three-dimensional MRI with fat saturation and navigator echo

The purpose of this study was to compare the diagnostic value of MR angiography (MRA) with conventional contrast angiography in coronary artery disease. Thirty-five patients underwent MRA and coronary angiography within 4 hours. Of these, three patients were investigated twice: once before and once after balloon angioplasty. The pulse sequence was a cardiac-triggered, single-slab, three-dimensional gradient-echo sequence, employing a spin-echo navigator echo measurement to track the variation of the diaphragm during the scan. The following segments of the coronary arteries were included in this prospective study: left main coronary artery, proximal and middle left anterior descending, proximal and middle left circumflex, proximal and middle right coronary artery, and intermediate branch, if present. In total, 176 segments were classified as normal or having a stenosis of less than 50% and as having a stenosis of more than 50%. Five patients were excluded because of lack of cooperation. Over all, 45 of 54 stenoses were detected and interpretable by MRA. Sensitivity, specificity, and positive and negative predictive values of MRA for detecting significant stenoses were 83%, 94%, 87%, and 93%, respectively. MRA identified significant stenoses within the major coronary arteries with a high degree of accuracy. Sensitivity and specificity are higher compared with exercise tests or scintigraphy or top of the precise localization.     

Whole-body MR angiography using a novel 32-receiving-channel MR system with surface coil technology: first clinical experience

PURPOSE: To demonstrate the feasibility of detecting atherosclerotic vascular disease using an innovative magnetic resonance angiography (MRA) protocol in combination with a dedicated whole-body MR scanner with new surface coil technology. MATERIALS AND METHODS: A total of 10 volunteers and eight patients with peripheral arterial occlusive disease (PAOD) were examined at 1.5 T. Conventional digital subtraction angiography (DSA) of the symptomatic region was available as a reference standard in all eight patients. Depending on subjects' size, four to five three-dimensional data sets were acquired using an adapted injection protocol. Images were assessed independently by two readers for vascular pathology. Additionally, signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured. RESULTS: Whole-body MRA yielded excellent sensitivity and specificity of more than 95% for both readers with high interobserver agreement (k = 0.93). Surface coil signal reception rendered a high SNR (mean 151.28 +/- 54.04) and CNR (mean 120.75 +/- 46.47). Despite lower SNR and CNR of the cranial and cervical vessels, a two-step injection protocol exhibited less venous superposition and therefore proved to be superior compared to single-bolus injection. CONCLUSION: Our approach provides accurate noninvasive high-resolution imaging of systemic atherosclerotic disease, covering the arterial vasculature from intracranial arteries to distal runoff vessels. The recently introduced MR scanner and coil technology is feasible to significantly increase the performance of whole-body MRA.     

Pancreatic adenocarcinoma: combination of MR imaging, MR angiography and MR cholangiopancreatography for the diagnosis and assessment of resectability

The purpose of this study was to determine the possibility of integrating MR cholangiopancreatography (MRCP) and MR angiography (MRA) to conventional MR images in the diagnosis and assessment of resectability of pancreatic adenocarcinoma. Twenty-three patients with pancreatic adenocarcinoma were prospectively examined with MR. Conventional MR images were acquired in all patients. Three-dimensional MRCP and MRA images were acquired in all patients with suspected biliary and vascular involvement. Acquisition time was less than 45 min in all cases. Images were independently evaluated by two radiologists, with final reading decided by consensus among readers. Diagnosis was confirmed with surgery in 16 patients and with percutaneous biopsy in 7. Concordance among readers was high with a kappa value of 0.83. Pancreatic adenocarcinoma was observed in all patients. Correct assessment of unresectability due to vascular involvement was found in 22 of 23 patients. Biliary obstruction was evident in 13 patients, involving the biliary and pancreatic ducts in 9 and the biliary ducts only in 4. Technical advances permit extensive use of MRI in the evaluation of abdominal pathologies. The combination of MR imaging, MRCP, and MRA can provide sufficient information for the diagnosis and assessment of resectability of pancreatic adenocarcinoma, which otherwise would require three different exams. Received 22 August 1996; Revision received 3 June 1997; Accepted 19 August 1997     

三维增强磁共振血管成像在糖尿病足病外周动脉病变中的应用

目的:探讨3D CE MRA在糖尿病足病外周动脉病变检查中的成像方法及应用价值。方法:对17例临床怀疑外周动脉病变的糖尿病足病患者,运用MR 3D FLASH自减影序列行CE MRA检查,检查范围自腹主动脉下段至足背动脉,对靶血管作最大强度投影(MIP)重组。另对其中4例小腿及足部动脉单独行二次增强扫描(Gd-DTPA 15ml,2.5ml/s)。对外周动脉进行观察,分析其狭窄情况并分级。结果:所有患者显示目标动脉基本满意,血管解剖形态较清晰,病变显示较明确。正常或轻度狭窄169个节段,中度狭窄94个节段,重度狭窄45个节段,闭塞49个节段。结论:3D CEMRA在糖尿病足病外周动脉病变检查中具有重要意义,但尚有一定局限性。