Absolute blood contrast concentration and blood signal saturation on myocardial perfusion MRI: Estimation from CT data

Purpose

To determine the optimal contrast injection rate and absolute blood gadolinium concentration for optimal first‐pass imaging.

Materials and Methods

The concentration of contrast medium in left ventricle (LV) was estimated from dynamic computed tomography (CT) by administering iodinated contrast medium of volume (0.2 mL/kg) equivalent to 0.1 mmol/kg of gadolinium injection in 50 subjects. A blood sample study was performed to determine the relationship between blood signal and gadolinium concentration on perfusion MRI.

Results

The mean peak gadolinium concentration in LV increased as the injection rate increased from 1 mL/sec (3.7 ± 1.2 mM), to 4 mL/sec (6.9 ± 2.7 mM) (P < 0.01). However, no significant improvement was found with an increase in the injection rate from 4 mL/sec to 5 mL/sec (6.8 ± 1.5 mM, P = 0.86). In a blood sample study the linear relationship between blood signal and gadolinium concentration was maintained in the range of ≤0.67 mM (r = 0.992), which corresponds to a peak blood concentration following a 0.01 mmol/kg gadolinium injection.

Conclusion

The optimal contrast injection rate for myocardial perfusion magnetic resonance imaging (MRI) appears to be 4 mL/sec. Saturation of arterial input signal is inevitable if the dose of gadolinium contrast medium exceeds 0.01 mmol/kg. These findings are essential for accurate quantification of myocardial blood flow from perfusion MRI. J. Magn. Reson. Imaging 2009;29:205–210. © 2008 Wiley‐Liss, Inc.     

Gadolinium‐enhanced magnetic resonance imaging for renovascular disease and nephrogenic systemic fibrosis: Critical review of the literature and UK experience

Purpose

To examine the positive reporting bias regarding the link with gadolinium (Gd) exposure and nephrogenic systemic fibrosis (NSF) in patients with renal impairment. This link has impacted strongly the international radiology safety guidelines. We believe that positive reporting bias has prevailed in the literature and that very few patients with a glomerular filtration rate (GFR) 15–29 mL/min (stage 4 chronic kidney disease [CKD]) should be regarded as high risk.

Materials and Methods

To examine this, we conducted the following steps: 1. A critical literature search on NSF. 2. An analysis of our centers magnetic resonance angiography (MRA) experience since 1999. 3. A survey of participating centers of the multicenter ASTRAL trial to assess whether any patients screened or enrolled into ASTRAL had developed NSF.

Results

The vast majority (90%) of NSF cases reported in the literature have occurred in patients with endstage renal disease treated with dialysis; very have had stable stage 4 or 5 (nondialysis) CKD. In all, 562 patients were followed up at our center: 30.4% were CKD4, 14.4% CKD5, 5.3% on dialysis, and 0.2% had renal transplants when imaged. No patients developed any symptoms or signs of NSF. In all, 347 patients were enrolled into ASTRAL on the basis of MRA (32% CKD4/5). One patient out of 45 centers (CKD5, received two Gd scans) developed NSF. Approximately 5 times as many patients were screened as were entered into ASTRAL.

Conclusion

No cases of NSF were observed at our center. By extrapolation, 1/1735 patients screened for the ASTRAL trial developed NSF, giving a crude incidence rate of 0.06%. We would argue that patients with CKD4 can safely undergo Gd‐MRA, albeit using a minimal dose of a macrocyclic agent and avoiding repeat doses. J. Magn. Reson. Imaging 2009;29:887–894. © 2009 Wiley‐Liss, Inc.     

Comparison of gadodiamide‐enhanced MR angiography to intraarterial digital subtraction angiography for evaluation of renal artery stenosis: Results of a phase III multicenter trial

Purpose:

To evaluate the efficacy and safety of 0.1 mmol/kg gadodiamide administration for contrast‐enhanced magnetic resonance angiography (MRA) in detecting hemodynamically relevant renal artery stenosis (RAS) when compared with intraarterial digital subtraction angiography (IA‐DSA) as the gold standard.

Materials and Methods:

In a multicenter, controlled study, 395 patients with suspected or known RAS were included. Three independent readers evaluated the MRA images. Two readers evaluated the IA‐DSA images and subsequently achieved consensus. The sensitivities and specificities of gadodiamide‐enhanced MRA were analyzed at the per‐patient and per‐vessel levels (exact 1‐sided binomial test at α = 0.025 with 95% confidence interval).

Results:

A total of 335 patients who had available standard of truth and MRA tests were included in the all‐subjects efficacy population: 55.5% (186/335) men and 44.5% women with a mean age of 63 ± 13 years (range 17–85 years). The sensitivities and specificities ranged from 81% to 86% for all independent readers at the per‐patient analysis based on subjects with the diagnostic images. Similar results were achieved with per‐vessel level analysis. Fewer than 1% of patients had adverse event associated with gadodiamide administration. There were no cases of nephrogenic systemic fibrosis (NSF) reported.

Conclusion:

Gadodiamide administration at the labeled dose of 0.1 mmol/kg for contrast‐enhanced MRA achieved equivalent results compared to IA‐DSA in evaluation of RAS and was well tolerated. J. Magn. Reson. Imaging 2010; 31: 390–397. © 2010 Wiley‐Liss, Inc.     

Contrast agent dose effects in cerebral dynamic susceptibility contrast magnetic resonance perfusion imaging

Purpose

To study the contrast agent dose sensitivity of hemodynamic parameters derived from brain dynamic susceptibility contrast MRI (DSC‐MRI).

Materials and Methods

Sequential DSC‐MRI (1.5T gradient‐echo echo‐planar imaging using an echo time of 61–64 msec) was performed using contrast agent doses of 0.1 and 0.2 mmol/kg delivered at a fixed rate of 5.0 mL/second in 12 normal subjects and 12 stroke patients.

Results

1) Arterial signal showed the expected doubling in relaxation response (ΔR2*) to dose doubling. 2) The brain signal showed a less than doubled ΔR2* response to dose doubling. 3) The 0.2 mmol/kg dose studies subtly underestimated cerebral blood volume (CBV) and cerebral blood flow (CBF) relative to the 0.1 mmol/kg studies. 4) In the range of low CBV and CBF, the 0.2 mmol/kg studies overestimated the CBV and CBF compared with the 0.1 mmol/kg studies. 5) The 0.1 mmol/kg studies reported larger ischemic volumes in stroke.

Conclusion

Subtle but statistically significant dose sensitivities were found. Therefore, it is advisable to carefully control the contrast agent dose when DSC‐MRI is used in clinical trials. The study also suggests that a 0.1 mmol/kg dose is adequate for hemodynamic measurements. J. Magn. Reson. Imaging 2009;29:52–64. © 2008 Wiley‐Liss, Inc.     

Time-resolved MR angiography of renal artery stenosis in a swine model at 3 Tesla using gadobutrol with digital subtraction angiography correlation

Purpose:

To establish the minimum dose required for detection of renal artery stenosis using high temporal resolution, contrast enhanced MR angiography (MRA) in a porcine model.

Materials and Methods:

Surgically created renal artery stenoses were imaged with 3 Tesla MR and digital subtraction angiography (DSA) in 12 swine in this IACUC approved protocol. Gadobutrol was injected intravenously at doses of 0.5, 1, 2, and 4 mL for time‐resolved MRA (1.5 × 1.5 mm² spatial resolution). Region of interest analysis was performed together with stenosis assessment and qualitative evaluation by two blinded readers.

Results:

Mean signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were statistically significantly less with the 0.5‐mL protocol (P < 0.001). There were no statistically significant differences among the other evaluated doses. Both readers found 10/12 cases with the 0.5‐mL protocol to be of inadequate diagnostic quality (κ = 1.0). All other scans were found to be adequate for diagnosis. Accuracies in distinguishing between mild/insignificant (<50%) and higher grade stenoses (>50%) were comparable among the higher‐dose protocols (sensitivities 73–93%, specificities 62–100%).

Conclusion:

Renal artery stenosis can be assessed with very low doses (～0.025 mmol/kg bodyweight) of a high concentration, high relaxivity gadolinium chelate formulation in a swine model, results which are promising with respect to limiting exposure to gadolinium based contrast agents. J. Magn. Reson. Imaging 2012;36:704–713. © 2012 Wiley Periodicals, Inc.     

Improved vessel delineation in keyhole time‐resolved contrast‐enhanced MR angiography using a gadolinium doped flush

Purpose

To prospectively assess the influence of a gadolinium doped saline flush compared with a pure saline flush on the image quality of the supra‐aortic vessels using time‐resolved contrast‐enhanced MR angiography (4D CE‐MRA) in a randomized double blind clinical trial.

Materials and Methods

Twenty‐two patients scheduled for contrast‐enhanced craniocerebral MRI underwent a supplemental 4D CE‐MRA covering the carotids to the superior sinus consisting of 30 dynamics of a T1‐weighted 3D gradient‐echo sequence (FFE) in sagittal direction. The temporal resolution of 1.1 s per dataset was achieved using the keyhole technique with the reference scan acquired at the end. Immediately after the intravenous (IV) injection of 0.1 mmol Gd/kg body weight of gadoterate, our patients received a 50‐mL flush consisting either of a 0.9% saline solution (n = 11) or doped with 50 mM gadolinium (n = 11; total Gd: 0.11 mmol/kg) at a flow‐rate of 2 mL/s. Vessel delineation, image quality, signal‐to‐noise‐ (SNR) and contrast‐to‐noise (CNR) ratios over time were compared.

Results

Both vessel delineation (internal carotid artery [ICA]: slope_saline = 308.5; slope_Gd = 528.9; P = 0.006; superior sagittal sinus [SSS]: slope_saline = 505.3; slope_Gd = 674.9; P = 0.007) and CNR (ICA: CNR_saline = 57.3; CNR_Gd = 80.55; P = 0.0417; SSS: CNR_saline = 74.15; CNR_Gd = 117.4; P = 0.0331) of the ICA and SSS were significantly increased using the gadolinium doped flush.

Conclusion

A low concentrated gadolinium flush in comparison to a pure saline flush improves significantly vessel contrast and their delineation in time‐resolved CE‐MRA using the keyhole technique. J. Magn. Reson. Imaging 2009;29:1147–1153. © 2009 Wiley‐Liss, Inc.     

Comparison of 0.5M gadoterate and 1.0M gadobutrol in peripheral MRA: A prospective,single‐center,randomized, crossover,double‐blind study

Purpose:

To evaluate the diagnostic efficacy of macrocyclic paramagnetic gadolinium (Gd) chelates gadoterate (0.5 mmol/mL) and gadobutrol (1.0 mmol/mL) for the diagnosis of clinically significant abdominal/lower limb arterial diseases at 3.0T.

Materials and Methods:

This study was conducted as a prospective, single‐center, randomized, double‐blind, intraindividual study comparing single dose (0.1 mmol/kg) gadoterate enhanced‐MRA (magnetic resonance angiography) with gadobutrol enhanced‐MRA at 3.0T for their diagnostic potential in patients with peripheral artery disease. A total of 20 patients were included in this trial.

Results:

Fourteen patients were eligible for the final efficacy analysis. The overall image quality (excellent/more than adequate) was better rated with gadoterate than with gadobutrol (100% vs. 78.6%, 100% vs. 92.9%, 100% vs. 85.7%, 100% vs. 85.7% for readers 1, 2, 3, 4, respectively). Diagnostic confidence was rated high/excellent in 100% (readers 1, 2, and 3) and 92.9% (reader 4) with gadoterate compared to 92.9% (readers 1 and 2) and 85.7% (readers 3 and 4) with gadobutrol. Higher signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) values were obtained for gadobutrol compared to gadoterate (26.1/23.4, P = 0.01, and 22.7/20.2, P = 0.01). For the secondary criteria, no differences between groups were reported. No adverse events were reported.

Conclusion:

Gadobutrol yielded significantly higher SNR/CNR while gadoterate was better rated in terms of overall image quality and diagnostic confidence (P > 0.05). J. Magn. Reson. Imaging 2012;36:1213–1221. © 2012 Wiley Periodicals, Inc.     

Optimized high-resolution contrast-enhanced hepatobiliary imaging at 3 tesla: a cross-over comparison of gadobenate dimeglumine and gadoxetic acid

Purpose:

To evaluate the signal to noise ratio (SNR) and contrast to noise ratio (CNR) performance of 0.05 mmol/kg gadoxetic acid and 0.1 mmol/kg gadobenate dimeglumine for dynamic and hepatobiliary phase imaging. In addition, flip angles (FA) that maximize relative contrast‐to‐noise performance for hepatobiliary phase imaging were determined.

Materials and Methods:

A cross‐over study in 10 volunteers was performed using each agent. Imaging was performed at 3 Tesla (T) with a 32‐channel phased‐array coil using breathheld 3D spoiled gradient echo sequences for SNR and CNR analysis, and for FA optimization of hepatobiliary phase imaging.

Results:

Gadobenate dimeglumine (0.1 mmol/kg) had superior SNR performance during the dynamic phase, statistically significant for portal vein and hepatic vein in the portal venous and venous phase (for all, P < 0.05) despite twice the approved dose of gadoxetic acid (0.05 mmol/kg), while gadoxetic acid had superior SNR performance during the hepatobiliary phase. Optimal FAs for hepatobiliary phase imaging using gadoxetic acid and gadobenate dimeglumine were 25–30° and 20–30° for relative contrast liver versus muscle (surrogate for nonhepatocellular tissues), and 45° and 20° (relative contrast liver versus biliary structures), respectively.

Conclusion:

Gadobenate dimeglumine may be preferable for applications that require dynamic phase imaging only, while gadoxetic acid may be preferable when the hepatobiliary phase is clinically important. Hepatobiliary phase imaging with both agents benefits from flip angle optimization. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Safety of gadoversetamide in patients with acute and chronic myocardial infarction

Purpose

To assess the safety data from two large, multicenter, phase 2 trials on the use of gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO) as a contrast agent in delayed hyperenhancement magnetic resonance imaging (DE‐MRI) in patients with acute and chronic myocardial infarction (MI).

Materials and Methods

The study population from both trials comprised 577 patients who were randomly assigned to one of four dose groups (0.05, 0.1, 0.2, or 0.3 mmol/kg) before undergoing DE‐MRI. Safety evaluations included physical and electrocardiographic (ECG) examinations. Vital signs, laboratory values, adverse events (AE), and serious adverse events (SAE) were monitored before and after contrast administration.

Results

Of the 577 patients who received gadoversetamide, 124 (21.5%) reported a total of 164 AEs; most were mild (139 AEs; 84.8%) or moderate (25 AEs; 15.2%). ECG‐related changes were the most frequent AE. Site investigators judged only eight AEs as likely related to gadoversetamide and only two of the eight as clinically relevant. Further evaluation suggested neither AE was related to gadoversetamide. Two SAEs were reported, but none was judged related to gadoversetamide by the site investigators.

Conclusion

Gadoversetamide is safe for use in patients with acute or chronic MI up to a dose of 0.3 mmol/kg. J. Magn. Reson. Imaging 2008;28:1368–1378. © 2008 Wiley‐Liss, Inc.     

Comparison of contrast‐enhanced multi‐station MR angiography and digital subtraction angiography of the lower extremity arterial disease

Purpose:

To compare diagnostic accuracy of multi‐station, high‐spatial resolution contrast‐enhanced MR angiography (CE‐MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease.

Materials and Methods:

Of 485 consecutive patients undergoing a run‐off CE‐MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived.

Results:

Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy.

Conclusion:

Contrast‐enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter‐observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast‐enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast‐enhanced MRA as an alternative to intra‐arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified. J. Magn. Reson. Imaging 2013;37:1427–1435. © 2012 Wiley Periodicals, Inc.     

In an animal model nephrogenic systemic fibrosis cannot be induced by intraperitoneal injection of high-dose gadolinium based contrast agents

Aim and objective

Nephrogenic systemic fibrosis (NSF) has been reported in humans to be most likely induced by gadolinium based contrast agents (GBCA), namely by gadodiamide, gadopentetate dimeglumine, and gadoversetamide, rarely by other GBCA. The pathogenesis of NSF remains unclear; different hypotheses are under discussion. The objective of the study is to assess if in the animal model human-like NSF changes can be induced by high-dose, intraperitoneal GBCA injections over four weeks.

Materials and methods

After approval by the institutional animal ethics committee, six rats each were randomly assigned to groups, and treated with seven different GBCA. Intraperitoneal (IP) injections – proven in the animal model to be effective – were chosen to prolong the animals’ exposure to the respective GBCA. GBCA doses of previous intravenous (IV) animal studies were applied. After five weeks all rats were sacrificed. Sham controls were treated with IP saline injections, employing the same regimen.

Results

No findings comparable with human NSF were observed in all animals after IP treatment with all seven GBCA at daily doses of 2.5 and 5.0 mmol/kg body weight (BW). No histopathological abnormalities of all examined organs were noted. Weight loss was stated in weeks three and four with GBCA injections at doses of 5.0 mmol/kg BW, but rats regained weight after cessation of GBCA treatment.

Conclusions

NSF-comparable pathological findings could not be induced by high dose intraperitoneal injection of seven GBCA.     

Prospective comparison of image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast-enhanced run-off magnetic resonance angiography of the lower extremities

Purpose

To compare image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast‐enhanced (CE) magnetic resonance angiography (MRA) of the lower extremities interindividually.

Materials and Methods

The study was approved by our Institutional Review Board. Written informed consent was obtained from all patients before enrollment in the study. We prospectively included 74 patients (21 women, 53 men; mean age ± SD: 67.9 ± 11.0 years) with suspected peripheral occlusive vascular disease. All patients underwent a contrast‐enhanced MRA of both lower extremities with either 0.1 mL/kg body weight gadobutrol or gadobenate dimeglumine. Image quality, stenosis grade, and artifacts were assessed by two blinded, independent investigators. Signal intensity (SI), signal‐to‐noise ratio (SNR), and contrast‐to‐noise ratio (CNR) were measured by a third investigator. Contrast agent groups were compared to each other using a two‐sided Student's t‐test.

Results

The results did not show significant differences for SI, SNR, or CNR. Both investigators were in significant accordance (P < 0.05) with regard to stenosis detection.

Conclusion

We conclude that application of standard clinical doses (0.1 mL/kg body weight) of both contrast agents provides similar diagnostic results and gadolinium dose could be reduced by the application of a single dose of gadobenate dimeglumine for CE run‐off MRA. J. Magn. Reson. Imaging 2010;32:1166–1171. © 2010 Wiley‐Liss, Inc.     

Retrospective assessment of prevalence of nephrogenic systemic fibrosis (NSF) after implementation of a new guideline for the use of gadobenate dimeglumine as a sole contrast agent for magnetic resonance examination in renally impaired patients

From May 2007 to January 2008, patients with Stage 3‐5 chronic kidney disease (CKD) undergoing gadobenate dimeglumine (GBD)‐enhanced magnetic resonance (MR) examinations were included in the retrospective investigation. The electronic medical records were reviewed to assess the prevalence of nephrogenic systemic fibrosis (NSF) in renally impaired patients underwent GBD‐enhanced MR examinations. In all, 250 patients (98 men, mean age 72.6 years) were included: 97% of the patients had Stage 3 CKD (estimated GFR 30–59 mL/min/1.73 m²); 37% had been exclusively exposed to GBD. The remaining were exposed to GBD and other gadolinium‐based contrast agents (GBCAs). The mean dose of GBD was 22 mL (standard deviation [SD], 11.2). Including exposure to other GBCAs, the mean cumulative dose of gadolinium was 61 mL (SD, 62.3). A total of 206 patients (82%) had skin examinations following the last GBD administration (mean duration, 108 days). No evidence of suspected or diagnosed NSF was found. In conclusion, on the basis of a retrospective chart review there was no skin evidence of NSF in predominantly Stage 3 CKD patients who were exposed to GBD at an average follow‐up of 108 days, either solely or in combination with other GBCAs. J. Magn. Reson. Imaging 2009;30:1335–1340. © 2009 Wiley‐Liss, Inc.     

MR Imaging detection of cerebral metastases with a single injection of high-dose gadoteridol

The utility of a single high-dose (0.3 mmol/kg) injection of gadoteridol, a gadolinium chelate, in the detection of brain metastases on magnetic resonance images was studied. Patients (n = 29) with a high suspicion for brain metastases at clinical examination and by history were imaged on two occasions–separated by more than 24 hours and less than 7 days–with a 0.1 mmol/kg contrast agent dose used for the first study and a 0.3 mmol/kg dose for the second. In patients (n = 15) with confirmed brain metastases by clinical, radiologic, and/or histologic criteria, 40 lesions were detected at the 0.3 mmol/kg dose by a single reader blinded to contrast agent dose, compared with 33 lesions at 0.1 mmol/kg, a 21% increase. Three of 15 patients (20%) demonstrated an increase in the number of lesions detected at the higher dose. Region-of-interest analysis of signal intensity measurements showed that lesion contrast (relative to normal brain) improved from 54% at 0.1 mmol/kg to 92% at 0.3 mmol/kg. A 0.3 mmol/kg dose of gadoteridol, administered in a single injection, permits identification of brain metastases not detected at 0.1 mmol/kg. Such information can influence the choice of therapy.     

Retrospective analysis of patients for development of nephrogenic systemic fibrosis following conventional angiography using gadolinium-based contrast agents

Purpose

The purpose was to retrospectively review the data of 27 patients with renal insufficiency who underwent conventional angiography with gadolinium-based contrast agents (GDBCA) as alternative contrast agents and assess the occurrence of nephrogenic systemic fibrosis (NSF) together with associated potential risk factors.

Methods

This HIPAA-compliant study had institutional review board approval, and informed consent was waived. Statistical analysis was performed for all available laboratory and clinical data, including dermatology reports. Type and amount of the GDBCA used were recorded for angiography and additional MRI studies, if applicable. Serum creatinine levels (SCr) pre- and post-angiography were recorded, and estimated glomerular filtration rates (eGFR) were calculated.

Results

Ten female and 17 male patients who underwent angiography with GDBCA were included. The mean amount of GDBCA administered was 44?±?15.5 ml (range 15–60 ml) or 0.24?+?0.12 mmol/kg (range 0.1–0.53 mmol/kg). At the time of angiography all patients had renal insufficiency (eGFR <60 ml/min/1.73 m²). Mean eGFR pre-angiography was 26 ml/min/1.73 m² and 33 ml/min/1.73 m² post-angiography. The mean follow-up period covers 28 months, range 1–84 months. Additional MRI studies with GDBCA administration were performed in 15 patients. One patient with typical skin lesions had developed biopsy-confirmed NSF.

Conclusion

Conventional arterial angiography with GDBCA may play a role in the development of NSF in patients with renal insufficiency. Alternative contrast agents, such as CO₂ angiography or rather the use of low doses of iodinated contrast agents, should be considered in these patients.     

Dynamic contrast‐enhanced magnetic resonance imaging of abdominal solid organ and major vessel: Comparison of enhancement effect between Gd‐EOB‐DTPA and Gd‐DTPA

Purpose

To evaluate the differences in enhancement of the abdominal solid organ and the major vessel on dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) obtained with gadolinium ethoxybenzyldiethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA: EOB) and gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) in the same patients.

Materials and Methods

A total of 13 healthy volunteers underwent repeat assessments of abdominal MR examinations with DCE‐MRI using either Gd‐DTPA at a dose of 0.1 mmol/kg body weight or EOB at a dose of 0.025 mmol/kg body weight. DCE images were obtained at precontrast injection and in the arterial phase (AP: 25 seconds), portal phase (PP: 70 seconds), and equilibrium phase (EP: 3 minutes). The signal intensities (SIs) of liver at AP, PP, and EP; the SIs of spleen, renal cortex, renal medulla, pancreas, adrenal gland, aorta at AP; and the SIs of portal vein and inferior vena cava (IVC) at PP were defined using region‐of‐interest measurements, and were used for calculation of signal intensity ratio (SIR).

Results

The mean SIRs of liver (0.195 ± 0.140), spleen (1.35 ± 0.353), renal cortex (1.58 ± 0.517), renal medulla (0.548 ± 0.259), pancreas (0.540 ± 0.183), adrenal gland (1.04 ± 0.405), and aorta (2.44 ± 0.648) at AP as well as the mean SIRs of portal vein (1.85 ± 0.477) and IVC (1.16 ± 0.187) at PP in the EOB images were significantly lower than those (0.337 ± 0.200, 1.99 ± 0.443, 2.01 ± 0.474, 0.742 ± 0.336, 0.771 ± 0.227, 1.26 ± 0.442, 3.22 ± 1.20, 2.73 ± 0.429, and 1.68 ± 0.366, respectively) in the Gd‐DTPA images (P < 0.05 each). There was no significant difference in mean SIR of liver at PP between EOB (0.529 ± 0.124) and Gd‐DTPA (0.564 ± 0.139). Conversely, the mean SIR of liver at EP was significantly higher with EOB (0.576 ± 0.167) than with Gd‐DTPA (0.396 ± 0.093) (P < 0.001).

Conclusion

Lower arterial vascular and parenchymal enhancement with Gd‐EOB, as compared with Gd‐DTPA, may require reassessment of its dose, despite the higher late venous phase liver parenchymal enhancement. J. Magn. Reson. Imaging 2009;29:636–640. © 2009 Wiley‐Liss, Inc.     

Low-dose 3D time-resolved magnetic resonance angiography (MRA) of the supraaortic arteries: correlation with high spatial resolution 3D contrast-enhanced MRA

Purpose

To evaluate the feasibility of low‐dose, 3D time‐resolved contrast‐enhanced magnetic resonance angiography (TR‐CEMRA) in the assessment of the supraaortic vessel, and to compare the results with high‐resolution contrast‐enhanced MRA (HR‐CEMRA).

Materials and Methods

This was an Institutional Review Board‐approved retrospective study. Forty‐five consecutive patients underwent contrast‐enhanced 3D TR‐CEMRA and 3D HR‐CEMRA for evaluation of neurovascular disease at 3.0 T. Gadobutrol was administered at a constant dose of 1 mL for TR‐CEMRA (independent of patient weight), and 0.1 mmol/kg for HR‐CEMRA. Two readers evaluated image quality using a four‐point scale (from 0 = excellent to 3 = nondiagnostic), and subsequently graded each stenosis into clinically relevant categories: normal (0%), mild stenosis (<50%), moderate to severe (>50%), and occlusion.

Results

The overall image quality for low‐dose TR‐CEMRA was in the diagnostic range (median 0, range 0–3). On the grading of stenosis, TR‐CEMRA using the TWIST sequence correlated with HR‐CEMRA (r = 0.668, P < 0.001). In terms of the comparison of TR‐CEMRA with HR‐CEMRA, of the 675 supraaortic arterial segments evaluated for stenosis or occlusion, agreement occurred in 611 of 675 (90.5%), overestimation in 41 of 675 (6.1%), and underestimation 23 of 675 (3.4%).

Conclusion

TR‐CEMRA achieved by administration of a small contrast dose (1 cc) yields rapid and important functional and anatomical information in the evaluation of supraaortic arteries. Due to limited spatial resolution, TR‐CEMRA at the current parameters has a tendency to overestimate the stenosis of smaller intracranial arteries compared to HR‐CEMRA. J. Magn. Reson. Imaging 2011;33:71–76. © 2010 Wiley‐Liss, Inc.     

Removal of gadolinium by dialysis: Review of different strategies and techniques

Nephrogenic systemic fibrosis (NSF) has been related to the administration of gadolinium‐based contrast agents for magnetic resonance imaging studies in patients with kidney disease. After reviewing the pathophysiology of NSF, we discuss the possible factors contributing to the toxicity of gadolinium in susceptible patients, including the excessive amounts of intravenous iron and erythropoietin as well as the inflammatory states commonly seen in patients treated with hemodialysis. Since free gadolinium is the most accepted risk factor for NSF, we provide some suggestions to improve clearance of both free and chelated gadolinium using different dialysis strategies and techniques. J. Magn. Reson. Imaging 2009;30:1347–1349. © 2009 Wiley‐Liss, Inc.     

Effect of Gd‐EOB‐DTPA on T2‐weighted and diffusion‐weighted images for the diagnosis of hepatocellular carcinoma

Purpose:

To evaluate the effect of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA) on T2‐weighted imaging (T2WI) and diffusion‐weighted imaging (DWI) for the diagnosis of hepatocellular carcinoma (HCC).

Materials and Methods:

The phantom signal intensity was measured. We also evaluated 72 patients including 30 patients with HCC. T2WI and DWI were obtained before and then 4 and 20 min after injecting the contrast medium. The signal to noise ratio (SNR), contrast to noise ratio (CNR), and apparent diffusion coefficient (ADC) were calculated in the tumor and liver parenchyma.

Results:

The phantom signal intensity increased on T2WI at a concentration of contrast medium less than 0.2 mmol/L but decreased when the concentration exceeded 0.4 mmol/L. SNR of the liver parenchyma on T2WI was significantly different between before and 4 min after injecting the contrast medium, while there were no significant differences between before and 4 and 20 min after injection. On T2WI, SNR, and CNR of HCC showed no significant differences at any time. SNR, CNR, and ADC of the liver parenchyma and tumor on DWI also showed no significant differences at any time.

Conclusion:

It is acceptable to perform T2WI and DWI after injection of Gd‐EOB‐DTPA for the diagnosis of HCC. J. Magn. Reson. Imaging 2010;32:229–234. © 2010 Wiley‐Liss, Inc.