Gadolinium-enhanced magnitude contrast MR angiography of popliteal and tibial arteries.

To evaluate the efficacy of gadopentetate dimeglumine in MR angiography of the lower extremities, a flow phantom, seven healthy volunteers, and seven patients with peripheral vascular disease were studied with a magnitude contrast (MC) technique. The combination of an MC rephase-dephase gradient-refocused-echo pulse sequence, a 40-cm-long transmit-receive coil, and intravenous administration of a bolus of gadopentetate dimeglumine improved MR angiographic quality in the phantom, volunteers, and patients. Gadolinium enhancement decreased deleterious saturation effects and improved images of the popliteal and tibioperoneal arteries in the volunteers and patients. However, in some cases, venous overlap, imaging artifacts, and suboptimal visualization of subtle lesions limited interpretation. The authors conclude that gadolinium enhancement combined with an MC subtraction pulse sequence appreciably improves MR angiography of lower extremity arteries.     

MR imaging of Hippel-Lindau disease: value of gadopentetate dimeglumine.

Hippel-Lindau disease is an autosomal dominant disorder characterized by tumors of the central nervous system and abdominal viscera. Frequent multisystem radiologic evaluation of persons at risk is desirable. Twenty-seven patients with Hippel-Lindau disease or a family history of the disease were examined with both unenhanced and gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging to study the usefulness of the contrast medium in the evaluation of these patients. The MR studies were correlated with computed tomographic (CT) scans in seven patients and cerebral angiograms in five. Twelve patients had hemangioblastomas in the brain, and eight of these patients also had spinal cord lesions (most were multiple), well demonstrated with gadopentetate dimeglumine. Contrast-enhanced MR imaging enabled detection of more central nervous system lesions and provided better delineation than unenhanced MR imaging, CT, or angiography. In addition, four patients with multiple renal cysts seen on CT scans and unenhanced MR images had enhancing lesions that were later proved to be renal cell carcinoma at angiography and/or surgery. Four patients had cystic lesions in the pancreas that did not enhance and were later proved to be pancreatic cysts. The authors conclude that gadopentetate dimeglumine-enhanced MR imaging appears to be a useful method for evaluating and following up patients with Hippel-Lindau disease.     

Contrast-enhanced three-dimensional MR portography.

Three-dimensional (3D) magnetic resonance (MR) portography with contrast material enhancement is a fast means of evaluating the portal venous system that has some advantages over currently used modalities, such as digital subtraction angiography, helical computed tomography, ultrasonography, and nonenhanced MR angiography with time-of-flight and phase-contrast techniques. With contrast-enhanced 3D MR portography, a first-pass study of the mesenteric vasculature is performed after rapid bolus injection of gadopentetate dimeglumine; a 3D fast field echo sequence is used, which can demonstrate the intrahepatic and extrahepatic portal venous system clearly. Repeated sequences after administration of gadopentetate dimeglumine allow separate demonstration of the splanchnic arteries and portomesenteric veins. The images are reconstructed by means of maximum-intensity projection postprocessing, and a subtraction technique can be used to eliminate arterial enhancement and demonstrate portosystemic shunts. The coronal source images simultaneously demonstrate parenchymal lesions of the liver, pancreas, biliary tract, and spleen. This technique is clinically indicated in portosystemic shunt, portal vein thrombosis, hepatocellular carcinoma, pancreatobiliary tumor, hepatic vein obstruction, differentiation of splanchnic arterial from portal venous disease, and gastrointestinal hemorrhage. Its limitations include allergic reactions to contrast media, inappropriate positioning of the 3D acquisition slab, respiratory motion artifacts, and pseudodissection.     

Single-dose breath-hold gadolinium-enhanced three-dimensional MR angiography of the renal arteries

PURPOSE: To evaluate the quality of single-dose breath-hold three-dimensional (3D) magnetic resonance (MR) angiography of the renal arteries optimized with a 1-mL test bolus timing examination. MATERIALS AND METHODS: Three-dimensional spoiled gradient-echo imaging (3.8-4.2/1.3-1.7 [repetition time msec/echo time msec], 25 degrees-40 degrees flip angle) was performed in 60 patients after administration of gadopentetate dimeglumine (average dose, 0.11 mmol/kg). Synchronization of contrast material administration with data acquisition was achieved with a 1-mL test dose of contrast material to estimate patient circulation parameters. Image quality was assessed by using contrast-to-noise (CNR), relative vascular enhancement, and venous-to-arterial enhancement ratios and subjective scoring of arterial and venous enhancement. The effect of the contrast material injection rate and the influence of breath holding during the timing examination also were examined. RESULTS: Overall, of 60 studies, 58 were diagnostic and 56 demonstrated excellent arterial enhancement. Venous enhancement was seen in eight studies. The average aortic relative vascular enhancement (+/- SD) was 14.6 +/- 5.9, with an aorta-to-inferior vena cava (IVC) CNR of 69.7 +/- 43.9. The IVC-to-aorta venous-to-arterial enhancement ratio averaged 0.08 +/- 0.16. There was no significant difference in image quality based on injection rates or the performance of breath holding during the timing examination (P > .1). CONCLUSION: Breath-hold gadolinium-enhanced renal MR angiography free of venous enhancement can be performed consistently and reliably with 20 mL of contrast material when studies are synchronized to patient circulation time by using a timing examination.     

Dynamic contrast-enhanced three-dimensional MR imaging of liver parenchyma: source images and angiographic reconstructions to define hepatic arterial anatomy

PURPOSE: To assess the accuracy of an interpolated breath-hold T1-weighted three-dimensional (3D) gradient-echo (GRE) magnetic resonance (MR) imaging sequence with near-isotropic pixel size (相似文献   

Gadobenate dimeglumine (Gd-DTPA) vs gadopentetate dimeglumine (Gd-BOPTA) for contrast-enhanced magnetic resonance angiography (MRA): improvement in intravascular signal intensity and contrast to noise ratio

PURPOSE: The purpose of this study was to compare contrast enhanced MR angiography (MRA) with gadopentetate dimeglumine (Gd-DTPA) to MRA with gadobenate dimeglumine (Gd-BOPTA), a high relaxivity paramagnetic contrast agent. MATERIALS AND METHODS: Twelve patients referred for carotid artery stenosis were examined with MR angiography using a fast spoiled gradient echo sequence. Gd-DTPA and Gd-BOPTA enhanced MR angiography were performed within 48-72 hours using a dose of 0.1 mmol/kg for Gd-BOPTA and 0.2 mmol/kg for Gd-DTPA, at a flow rate of 2 ml/s. Images were evaluated by two blinded radiologists. Qualitative and quantitative evaluations were performed comparing the sets of images from the two examinations. RESULTS: Qualitative evaluation demonstrated superior arterial contrast enhancement and vessel conspicuity with Gd-BOPTA compared with Gd-DTPA. Quantita-tive evaluation showed an improvement in both signal intensity and contrast to noise ratio with Gd-BOPTA. CONCLUSION: The greater relaxivity of Gd-BOPTA, at lower doses, compared with Gd-DTPA, provides higher intravascular signal and signal to noise ratio. Gd-BOPTA appears to be an optimal contrast agent for contrast enhanced MRA.     

Efficacy evaluation of gadoteridol for MR angiography of intracranial vascular lesions

A phase III multicenter study was conducted in 89 patients with known intracranial vascular lesions to evaluate an extracellular gadolinium contrast agent, gadoteridol, for intracranial magnetic resonance (MR) angiography. The pre- and postcontrast MR angiograms of 82 patients were evaluated by the unblinded investigators and by two blinded readers (A and B) for visualization of lesions; arterial and venous anatomy; extent, size, and number of lesions; and disease classification. The unblinded readers indicated that lesions were visualized better on postcontrast images in the following categories: venous anatomy, 87 (81%) of 107 lesions; arterial anatomy, 43 lesions (40%); and extent or size of lesions, 38 lesions (36%). In 29 (35%) of 82 patients, the unblinded readers determined that enhanced MR angiography provided more diagnostic information than unenhanced MR angiography. The blinded readers determined that enhanced MR angiography provided more information for visualization of vascular anatomy in more than 60% of cases. The additional information provided with gadoteridol would have changed the diagnosis in nine (8%) of 107 lesions seen by the unblinded readers, 11 (12%) of 90 lesions seen by reader A, and three (3%) of 93 lesions seen by reader B. The results confirm that the use of gadoteridol improves the visualization of intracranial vascular lesions with MR angiography. The authors conclude that development of new postprocessing algorithms will improve the utility of contrast-enhanced MR angiography.     

Subclavian MR arteriography: reduction of susceptibility artifact with short echo time and dilute gadopentetate dimeglumine

At arterial phase gadolinium-enhanced magnetic resonance (MR) angiography, artifactual stenosis of the subclavian artery is sometimes seen adjacent to the subclavian vein on the side of the contrast material injection. Experiments in phantoms and in 19 patients showed increased artifact with longer echo time and higher concentration of injected contrast material. An effective method to substantially decrease this susceptibility artifact was threefold dilution of gadopentetate dimeglumine and use of a short echo time (1 msec).     

Gadopentetate dimeglumine as a bowel contrast agent: safety and efficacy

To determine the safety and efficacy of gadopentetate dimeglumine as a bowel contrast agent, magnetic resonance (MR) imaging (0.5 T) was performed with a formulation of gadopentetate dimeglumine (1.0 mmol/L of gadopentetate dimeglumine, 15 g/L of mannitol, 6-17 mL/kg) in 133 patients with intraabdominal mass lesions. Mostly short-lived gastrointestinal side effects were noted in 32% of patients. Gadopentetate dimeglumine provided uniform hyperintense marking of the bowel and contrast enhancement in the region of interest in 81% of patients. Among 78 patients with images obtained both before and after administration of contrast material, post-contrast improvement of lesion delineation was found in 62%. Among 55 patients with only postcontrast images, gadopentetate dimeglumine proved useful in 65%. Intravenous injection of scopolamine or glucagon effectively eliminated "ghost" images of the opacified bowel in 105 of 109 cases. The authors conclude that gadopentetate dimeglumine is a safe and effective bowel contrast agent for MR imaging.     

Renal time-resolved MR angiography: quantitative comparison of gadobenate dimeglumine and gadopentetate dimeglumine with different doses

PURPOSE: Results with different doses of gadobenate dimeglumine and gadopentetate dimeglumine were compared at magnetic resonance (MR) angiography of the renal arteries. The signal-to-noise ratio (SNR) was evaluated as a quantitative measure of image quality. MATERIALS AND METHODS: Sixty consecutive patients (age range, 24-81 years; mean age, 65 years) underwent intraarterial digital subtraction angiography (DSA) and contrast material-enhanced time-resolved MR angiography. DSA was the standard of reference. Fifteen patients received gadopentetate dimeglumine at doses of 0.2 or 0.1 mmol per kilogram of body weight. Fifteen patients received gadobenate dimeglumine at doses of 0.05 or 0.1 mmol/kg. The SNR was calculated in the aorta and both main renal arteries. The number and degree of stenoses of the renal arteries and accessory vessels were evaluated by four observers. RESULTS: SNRs with gadobenate dimeglumine at a dose of 0.1 mmol/kg were significantly superior to those with gadopentetate dimeglumine at a dose of 0.1 mmol/kg. Differences were not statistically significant between the SNRs in the other groups. Eleven (85%) of 13 hemodynamically significant renal artery stenoses were detected correctly with MR angiography as were 22 (85%) of 26 accessory renal arteries. CONCLUSION: SNRs with gadobenate dimeglumine were higher than those with gadopentetate dimeglumine, but in most cases the differences in SNRs were not statistically significant.     

Bolus injection of MR contrast agents: hemodynamic effects evaluated by intracerebral laser Doppler flowmetry in rats.

PURPOSETo determine the effects on arterial blood pressure and cerebral blood flow of intravenous bolus injection of three MR contrast agents: gadopentetate dimeglumine, polylysine-Gd-DTPA, and superparamagnetic iron particles (SPIO).METHODSA single-fiber laser Doppler flowmetry probe was placed intracerebrally in 56 anesthetized rats. Cerebral blood flow and mean arterial blood pressure were measured before (baseline), during, and up to 30 minutes after intravenous bolus administration of the three contrast agents: 0.1 mmol/kg and 0.3 mmol/kg gadopentetate dimeglumine (n = 18 per group), 0.3 mmol/kg polylysine-Gd-DTPA (n = 10), and 0.03 mmol/kg SPIO (n = 10).RESULTSNeither the higher nor lower dose of gadopentetate dimeglumine had any statistically significant effect on cerebral blood flow, and there was no change in blood pressure during administration of either dose of gadopentetate dimeglumine. Administration of polylysine-Gd-DTPA caused a transient drop in blood pressure in two animals, marked in one (decrease to 21% of baseline values) and mild in the other (84% of baseline). After administration of SPIO, a significant decrease in blood pressure occurred in one animal (41% of baseline). Despite this decrease in mean arterial blood pressure, there were no statistically significant changes in cerebral blood flow after administration of polylysine-Gd-DTPA or SPIO.CONCLUSIONOur results suggest that bolus injection of these contrast agents at clinically relevant doses causes no significant alteration in cerebral blood flow. We conclude that gadopentetate dimeglumine is well suited for cerebral MR perfusion imaging without inherent influence on cerebral blood flow and that the same is probably true for polylysine-Gd-DTPA and SPIO.     

Benign lumbar arachnoiditis: MR imaging with gadopentetate dimeglumine

MR imaging was performed in 13 patients with benign lumbar arachnoiditis both before and after IV injection of gadopentetate dimeglumine. The arachnoiditis was proved by previous myelography in 12 patients and by noncontrast MR imaging in one patient. The disease was presumably the result of previous myelography and/or surgery. It was characterized as mild in two patients, moderate in two patients, and severe in nine patients. Imaging was performed on a 1.5-T unit, and both short and long TR images were obtained before and after contrast administration. Noncontrast MR images demonstrated changes consistent with arachnoiditis in all patients. After contrast, three patients had no enhancement, three patients had minimal enhancement, three patients had mild enhancement, and four patients had moderate enhancement. In no case did contrast enhancement alter the diagnosis or reveal additional findings that could not be seen on the noncontrast images. Gadopentetate dimeglumine enhancement plays little role in the diagnosis of lumbar arachnoiditis. If used for another reason, however, short TR scans may show enhancement of adherent roots in some cases. In addition, administration of gadopentetate dimeglumine will not cause sufficient enhancement to hinder the detection of arachnoiditis on long TR images and may aid in recognition of adherent roots on short TR images.     

Benign lumbar arachnoiditis: MR imaging with gadopentetate dimeglumine

MR imaging was performed in 13 patients with benign lumbar arachnoiditis both before and after IV injection of gadopentetate dimeglumine. The arachnoiditis was proved by previous myelography in 12 patients and by noncontrast MR imaging in one patient. The disease was presumably the result of previous myelography and/or surgery. It was characterized as mild in two patients, moderate in two patients, and severe in nine patients. Imaging was performed on a 1.5-T unit, and both short and long TR images were obtained before and after contrast administration. Noncontrast MR images demonstrated changes consistent with arachnoiditis in all patients. After contrast, three patients had no enhancement, three patients had minimal enhancement, three patients had mild enhancement, and four patients had moderate enhancement. In no case did contrast enhancement alter the diagnosis or reveal additional findings that could not be seen on the noncontrast images. Gadopentetate dimeglumine enhancement plays little role in the diagnosis of lumbar arachnoiditis. If used for another reason, however, short TR scans may show enhancement of adherent roots in some cases. In addition, administration of gadopentetate dimeglumine will not cause sufficient enhancement to hinder the detection of arachnoiditis on long TR images and may aid in recognition of adherent roots on short TR images.     

Normal and abnormal pituitary glands: gadopentetate dimeglumine-enhanced MR imaging

Dynamic magnetic resonance (MR) imaging with a 1.5-T superconductive unit was used in the evaluation of nine normal pituitary glands and 10 pituitary adenomas, including four microadenomas and six macroadenomas. Seven to 10 images were obtained every 20-30 seconds with use of the spin-echo technique after rapid injection of gadopentetate dimeglumine. The earliest contrast material enhancement of normal structures was seen in the infundibulum and posterior lobe of the pituitary gland at 20 seconds, followed by gradual contrast material enhancement of the anterior lobe of the pituitary gland from the junction of the infundibulum to the peripheral portion of the anterior lobe of the pituitary gland within 80 seconds after gadopentetate dimeglumine injection. The peak enhancement of pituitary adenomas occurred at 60-200 seconds, usually after the most marked enhancement of the normal pituitary gland. Microadenomas are best visualized at earlier phases of gadopentetate dimeglumine-enhanced dynamic imaging, with signal intensity lower than that seen on images of normal pituitary glands.     

Spleen: dynamic enhancement patterns on gradient-echo MR images enhanced with gadopentetate dimeglumine.

To examine the pattern of immediate enhancement with gadopentetate dimeglumine on dynamic magnetic resonance (MR) images of the spleen, this study was divided into two parts: In the first part, the authors retrospectively reviewed the dynamic MR images obtained with a fast low-angle shot (FLASH) sequence in the abdomen immediately after injection of gadopentetate dimeglumine in 137 patients. In the second part, dynamic gadolinium-enhanced FLASH images were prospectively compared with contrast material-enhanced computed tomographic (CT) scans in 17 patients with focal splenic lesions discovered on CT scans. In the first part, 108 patients (79%) had an arciform pattern of contrast enhancement; 22 patients (16%), a uniform pattern of high signal intensity; and seven patients (5%), a uniform pattern of low signal intensity. Most patients had arciform enhancement of the spleen; uniform enhancement occurred in some patients with underlying malignant or inflammatory disease. In the second part, all focal lesions seen on CT scans were seen on dynamic MR images (75 lesions), significantly more than were seen on FLASH images (15 lesions) (P < .001).     

Cavernous sinus: correlation between anatomic and dynamic gadolinium- enhanced MR imaging findings

Dynamic magnetic resonance (MR) images were evaluated and compared with conventional T1-weighted spin-echo (SE) images obtained before and after administration of gadopentetate dimeglumine in 20 patients with normal cavernous sinuses. Starting 10 seconds after rapid injection of gadopentetate dimeglumine (0.1 mmol/kg), six to eight serial images were obtained every 30 seconds for 3-5 minutes. The venous spaces of the cavernous sinus were markedly enhanced 30 seconds after injection. Cranial nerves III and IV, V1 and VI, and V2 were seen on 75% of dynamic images each; they were seen, respectively, on 62%, 30%, and 28% of conventional postcontrast images. The medial wall was demarcated on 90% of dynamic, 15% of precontrast, and 55% of postcontrast images. A small area of connective tissue was identified within the cavernous sinus on dynamic images showing gradual enhancement. It is concluded that dynamic MR images proved useful in delineating and distinguishing abnormal tissue from normal structures.     

Enhancement of intervertebral disks with gadolinium complexes: comparison of an ionic and a nonionic medium in an animal model.

PURPOSETo compare MR contrast enhancement of intervertebral disk tissue after intravenous administration of equimolar doses of an ionic and of a nonionic gadolinium complex.METHODSContrast enhancement was measured on MR in lumbar intervertebral disks for 120 minutes after intravenous injection of gadoteridol or gadopentetate dimeglumine, 0.3 mmol/kg. MR studies were performed with each contrast medium in four rabbits. Contrast enhancement was measured in intervertebral disks as a function of time and contrast medium.RESULTSWith both contrast media, enhancement of normal intervertebral disks was detected. Enhancement of disks was significantly greater with gadoteridol than with gadopentetate dimeglumine.CONCLUSIONThe enhancement of cartilage is influenced by the molecular structure of the gadolinium complex. The negative charge of gadopentetate dimeglumine may give it a slower rate of diffusion into disk cartilage than a nonionic complex.     

Primary and secondary brain tumors at MR imaging: bicentric intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine

PURPOSE: To evaluate the safety of and compare the enhancement characteristics of gadobenate dimeglumine (MultiHance; Bracco Imaging, Milan, Italy) with those of a standard gadolinium chelate (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) in primary and secondary brain tumors on the basis of qualitative and quantitative parameters, on an intraindiviual basis. MATERIALS AND METHODS: Twenty-seven patients with either high-grade glioma or metastases were enrolled in a bicentric intraindividual crossover study to compare lesion enhancement with doses of 0.1 mmol per kilogram of body weight of 0.5 mol/L gadopentetate dimeglumine and 0.5 mol/L gadobenate dimeglumine. MR imaging was performed before injection (T1-weighted spin-echo [SE] and T2-weighted fast SE acquisitions) and at 1, 3, 5, 7, 9, and 16 minutes after injection (T1-weighted SE acquisitions). Qualitative assessment was performed by blinded off-site readers (for 22 patients) and on-site investigators (for 24 patients) in terms of global contrast enhancement, lesion-to-brain contrast, lesion delineation, internal lesion morphology and structure, tumor vascularization, and global image preference. Additional quantitative assessment with region-of-interest analysis was performed by off-site readers alone. Statistical analysis of qualitative data was performed with the Wilcoxon signed rank test, whereas a nonparametric approach was adopted for analysis of quantitative data. RESULTS: Significant (P <.05) preference for gadobenate dimeglumine over gadopentetate dimeglumine was noted both off-site and on-site for the global assessment of contrast enhancement. For off-site readers 1 and 2 and the on-site investigators, respectively, gadobenate dimeglumine was preferred in 13, 17, and 16 patients; gadopentetate dimeglumine was preferred in four, four, and four patients; and equality was found in five, one, and four patients). Similar preference for gadobenate dimeglumine was noted by off-site readers and on-site investigators for lesion-to-brain contrast and all other qualitative parameters. Off-site quantitative evaluation revealed significantly (P <.05) superior enhancement for gadobenate dimeglumine compared with that for gadopentetate dimeglumine at all time points from 3 minutes after injection. CONCLUSION: Significantly superior contrast enhancement of intraaxial enhancing brain tumors was achieved with 0.1 mmol/kg gadobenate dimeglumine compared with that with 0.1 mmol/kg gadopentetate dimeglumine.     

MR 'hot nose sign' and 'intravascular enhancement sign' in brain death.

Three cases of MR with gadopentetate dimeglumine in patients diagnosed with cerebral death are presented. Observation of an MR "hot nose sign" and an "intravascular enhancement sign" provided additional imaging support in the clinical diagnosis of brain death. The MR findings in brain death include: 1) transtentorial and foramen magnum herniation, 2) absent intracranial vascular flow void, 3) poor gray matter/white matter differentiation, 4) no intracranial contrast enhancement, 5) carotid artery enhancement (intravascular enhancement sign), and 6) prominent nasal and scalp enhancement (MR hot nose sign). Additional modalities for confirming brain death are discussed.     

Idiopathic,herpetic, and HIV-associated facial nerve palsies: abnormal MR enhancement patterns.

PURPOSETo determine specific criteria that can be used to define normal versus abnormal MR contrast enhancement of the facial nerve.METHODSTwenty-three patients with acute unilateral inflammatory peripheral facial nerve palsy were examined on a 1.5-T MR using multiplanar T1-weighted spin-echo sequences before and after injection of gadopentetate dimeglumine. These MR patterns were compared with those of healthy control subjects.RESULTSThe normal facial nerve usually showed a mild to moderate enhancement of the geniculate ganglion and the tympanic-mastoid segment. The intracanalicular-labyrinthine segment did not enhance. All patients showed abnormal enhancement of the distal intracanalicular and the labyrinthine segment. An intense enhancement could be observed in the geniculate ganglion and the proximal tympanic segment, especially in herpetic palsy. Associated enhancement of the vestibulocochlear nerve was seen in herpetic and idiopathic palsy. Enhancement of the inner ear structures was detected only in herpetic palsy.CONCLUSIONSAbnormal contrast enhancement of the distal intracanalicular and the labyrinthine facial nerve segment is observed in all patients and is the only diagnostically reliable MR feature proving an inflammatory facial nerve lesion. The intense enhancement of the geniculate ganglion and the proximal tympanic segment is possibly correlated with the reactivation of the latent infection in the sensory ganglion. The abnormal enhancement results from breakdown of the blood-peripheral nerve barrier and/or from venous congestion in the venous plexuses of the epi- and perineurium.