Gd Contrast Medium Research Articles

Optimal Protocol for Contrast-enhanced Free-running 5D Whole-heart Coronary MR Angiography at 3T.

Free-running 5D whole-heart coronary MR angiography (MRA) is gaining in popularity because it reduces scanning complexity by removing the need for specific slice orientations, respiratory gating, or cardiac triggering. At 3T, a gradient echo (GRE) sequence is preferred in combination with contrast injection. However, neither the injection scheme of the gadolinium (Gd) contrast medium, the choice of the RF excitation angle, nor the dedicated image reconstruction parameters have been established for 3T GRE free-running 5D whole-heart coronary MRA. In this study, a Gd injection scheme, RF excitation angles of lipid-insensitive binominal off-resonance RF excitation (LIBRE) pulse for valid fat suppression and continuous data acquisition, and compressed-sensing reconstruction regularization parameters were optimized for contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence at 3T. Using this optimized protocol, contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence is feasible with good image quality at 3T.

Gadolinium as an Emerging Microcontaminant in Water Resources: Threats and Opportunities

As a result of high doses of paramagnetic gadolinium (Gd) chelates administered in magnetic resonance imaging (MRI) exams, their unmetabolized excretion, and insufficient removal in wastewater treatment plants (WWTPs), large amounts of anthropogenic Gd (Gdanth) are released into surface water. The upward trend of gadolinium-based contrast agent (Gd-CA) administrations is expected to continue growing and consequently higher and higher anthropogenic Gd concentrations are annually recorded in water resources, which can pose a great threat to aquatic organisms and human beings. In addition, the feasibility of Gd retention in patients administered with Gd-CAs repeatedly, and even potentially fatal diseases, including nephrogenic systemic fibrosis (NSF), due to trace amounts of Gd have recently arisen severe health concerns. Thus, there is a need to investigate probable adverse health effects of currently marketed Gd-CAs meticulously and to modify the actual approach in using Gd contrast media in daily practice in order to minimize unknown possible health risks. Furthermore, the employment of enhanced wastewater treatment processes that are capable of removing the stable contrast agents, and the evaluation of the ecotoxicity of Gd chelates and human exposure to these emerging contaminants through dermal and ingestion pathways deserve more attention. On the other hand, point source releases of anthropogenic Gd into the aquatic environment presents the opportunity to assess surface water—groundwater interactions and trace the fate of wastewater plume as a proxy for the potential presence of other microcontaminants associated with treated wastewater in freshwater and marine systems.

Possible usefulness of gadolinium-enhanced brain MRI for evaluating risk of perioperative hemorrhage: a case of infective endocarditis.

A 59-year-old woman visited a local hospital for fever and was diagnosed as having infective endocarditis (IE) on the basis of blood cultures and transthoracic echocardiography. Based on clinical episodes of subarachnoid hemorrhage after admission, it was judged that she was not a good candidate for urgent open heart surgery, and it was decided to treat her with conservative medical therapy for the acute phase. We explored the optimum timing for surgery by employing gadolinium (Gd) contrast medium-enhanced magnetic resonance imaging (MRI) T2* weighted image (black dots) due to her high risk of perioperative cerebral hemorrhage. After the disappearance of the contrast media enhancement effect around the black dots, open heart surgery was performed successfully on the 103rd hospitalization day. The patient was discharged 22 days after the surgery with no clinical complications. This case suggests that disappearance of the contrast media enhancement effect around the black dots may be a useful marker for optimal timing of surgery to minimize the risk of perioperative cerebral hemorrhage in patients with IE. Learning Objective. The MRI T2* weighted images including those with Gd contrast medium enhancement effect may be useful for evaluating the risk of perioperative intracranial hemorrhage in IE.

Effect of intravenous gadolinium-DTPA on diffusion-weighted imaging of brain tumors: a short temporal interval assessment.

To determine the effect of intravenous administration of gadolinium (Gd) contrast medium (Gd-DTPA) on diffusion-weighted imaging (DWI) for the evaluation of normal brain parenchyma vs. brain tumor following a short temporal interval. Forty-four DWI studies using b values of 0 and 1000 s/mm(2) were performed before, immediately after, 1 min after, 3 min after, and 5 min after the administration of Gd-DTPA on 62 separate lesions including 15 meningioma, 17 glioma and 30 metastatic lesions. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) values of the brain tumor lesions and normal brain tissues were measured on pre- and postcontrast images. Statistical analysis using paired t-test between precontrast and postcontrast data were obtained on three brain tumors and normal brain tissue. The SNR and CNR of brain tumors and the SNR of normal brain tissue showed no statistical differences between pre- and postcontrast (P > 0.05). The ADC values on the three cases of brain tumors demonstrated significant initial increase on the immediate time point (P < 0.01) and decrease on following the 1 min time point (P < 0.01) after contrast. Significant decrease of ADC value was still found at 3min and 5min time point in the meningioma group (P < 0.01) with gradual normalization over time. The ADC values of normal brain tissues demonstrated significant initial elevation on the immediately postcontrast DWI sequence (P < 0.01). Contrast medium can cause a slight but statistically significant change on the ADC value within a short temporal interval after the contrast administration. The effect is both time and lesion-type dependent.

Changes in endolymphatic hydrops after sac surgery examined by Gd-enhanced MRI

Conclusion: Endolymphatic hydrops could be a reversible inner ear pathological condition. After sac surgery, hydrops was reduced and symptoms went into remission in some cases, although vertigo suppression was not always a result of the reduced hydrops. Objective: To examine the changes in endolymphatic hydrops detected by gadolinium (Gd) contrast-enhanced magnetic resonance imaging (MRI) before and 6 months after endolymphatic sac surgery in patients with unilateral Ménière's disease. Methods: Fluid-attenuated inversion recovery MRI was obtained 4 h after intravenous administration or 24 h after intratympanic administration of Gd contrast medium. An enlarged negative stain corresponding to the cochlear duct and endolymphatic space of the vestibule was assessed as hydrops. Results: Of seven patients with hydrops confirmed by MRI before surgery, both cochlear and vestibular hydrops became negative in two, cochlear hydrops became negative in one, both hydrops were present, but reduced, in one, and there was no change in three patients. The number of vertigo spells was reduced in all cases at 6–12 months after surgery. As for the three cases of negative hydrops, vertigo was completely suppressed. In two cases in which hearing level improved, hydrops became negative after surgery.

The diagnostic accuracy of unenhanced MRI in the assessment of joint abnormalities in juvenile idiopathic arthritis

To assess the diagnostic accuracy and reliability of MRI without contrast enhancement in the evaluation of JIA knee joint abnormalities. JIA patients with clinically active knee involvement were prospectively studied using an 1-T open-bore magnet. MRI features were independently evaluated by two readers using the JAMRIS system. The first reading included unenhanced images, whereas complete image sets were available for the second reading. Imaging findings from 73 patients were analysed. Agreement between Gd-enhanced (+Gd) and Gd-unenhanced (-Gd) MRI scores of bone marrow changes, cartilage lesions and bone erosions was good concerning sensitivity, specificity, negative predictive value and positive predictive value. Inter-observer agreement was good for both -Gd and +Gd scores (ICC = 0.91-1.00, 0.93-1.00, respectively). Regarding the assessment of synovial hypertrophy, specificity of -Gd was high (0.97), but the sensitivity of unenhanced MRI was only 0.62. Inter-reader agreement for +Gd MRI was ICC = 0.94; however, omitting post-Gd acquisitions increased inter-reader variation (ICC = 0.86). If Gd-enhanced MRI is the reference standard, omitting Gd contrast medium is irrelevant for the assessment of bone marrow changes, cartilage lesions and bone erosions as joint abnormalities in JIA. Omitting intravenous Gd in the MRI assessment of joints in JIA is inadvisable, because it decreases the reliability of detecting synovial disease. • Magnetic resonance imaging is increasingly used to assess juvenile idiopathic arthritis. • Synovial hypertrophy, a marker of JIA activity, is well shown by MRI. • Omitting intravenous contrast medium decreases the reliability of synovial hypertrophy scores. • Bone marrow, cartilage and erosions can be reliably evaluated without contrast enhancement. • In the evaluation of JIA disease activity, unenhanced MRI is inadvisable.

Iodine contrast iso-attenuating with diagnostic gadolinium doses in CTA and angiography results in ultra-low iodine doses. A way to avoid both CIN and NSF in azotemic patients?

To establish iodine (I) contrast medium (CM) doses iso-attenuating with gadolinium (Gd) CM doses regarded diagnostic in CTA and percutaneous catheter-angiography/vascular interventions (PCA/PVI) in azotemic patients. CT Hounsfield units (HU) were measured in 20-mL syringes containing 0.01/0.02,/0.05/0.1 mmol/mL of iodine or gadolinium atoms and placed in phantoms. Relative contrast were measured in 20-mL syringes filled with iohexol at 35/50/70/90/110/140 mg I/mL and 0.5 M gadodiamide using radiofluoroscopy (RF), digital radiography (DX) and x-ray angiography (XA) systems. Clinical doses of Gd-CM at CTA/PCA/PVI were reviewed. At CT 91-116 and 104-125 mg I/mL in the chest and abdominal phantoms, respectively, were iso-attenuating with 0.5 M Gd at 80-140 kVp. At RF/DX/XA systems 35-90 mg I/mL were iso-attenuating with 0.5 M gadodiamide at 60-115 kVp. Clinically, 60 mL 91-125 mg I/mL (5.5-7.5 gram-iodine) at 80-140 kVp CTA and 60 mL of 35-90 mg I/mL (2.1-5.4 gram-iodine) at 60-115 kVp PCA/PVI would be iso-attenuating with 60 mL 0.5 M Gd-CM (=0.4 mmol Gd/kg in a 75-kg person). Meticulous examination technique and judicious use of ultra-low I-CM doses iso-attenuating with diagnostic Gd-CM doses in CTA and PCA/PVI may minimise the risk of nephrotoxicity in azotemic patients, while there is no risk of NSF.

Grading of Inflammatory Disease Activity in the Sacroiliac Joints with Magnetic Resonance Imaging: Comparison Between Short-tau Inversion Recovery and Gadolinium Contrast-enhanced Sequences

We investigated the potential concordance of 2 different magnetic resonance (MR) sequences - short-tau inversion recovery (STIR) and fat-saturated T1-weighted spin-echo after application of gadolinium (Gd) contrast medium to detect active bone marrow abnormalities at the sacroiliac joints (SIJ) in patients with spondyloarthritis (SpA). Blinded and using the Danish scoring method, we evaluated transaxial MR images of the 2 sequences in 40 patients with SpA with disease duration of 3-14 years. Both the cartilaginous and ligamentous portions of the SIJ were analyzed. There was a significant positive correlation between the activity scores obtained by STIR and Gd-enhanced sequences (p < 0.0001). Agreement in the detection of bone marrow abnormalities occurred in 60 of the 80 joints, 35 with and 25 without signs of active disease. Discordance with STIR-positive marrow activity scores occurred in only 11 joints; Gd-enhanced positive scores in 9 joints. The STIR sequence detected remnants of marrow activity in the periphery of chronic fatty replacement not seen or partly obscured on the Gd sequence. Small subchondral enhancing lesions may not be scored on the STIR sequence, mostly because of reduced image resolution. Active bone marrow abnormalities were detected nearly equally well with STIR and Gd-enhanced fat-suppressed T1 sequences in patients with SpA, with STIR being most sensitive to visualize active abnormalities in the periphery of chronic changes.

The Effect of Susceptibility of Gadolinium Contrast Media on Diffusion-weighted Imaging and the Apparent Diffusion Coefficient

The development of parallel magnetic resonance imaging has resulted in the frequent use of diffusion-weighted imaging (DWI) in clinical medicine, which usually involves the use of contrast medium. However, gadolinium (Gd) contrast medium may have some effect on DWI and the apparent diffusion coefficient (ADC). The present study was performed to determine whether the magnetic susceptibility of contrast medium alters the DWI signal and the value of ADC in some imaging techniques. Nonfat suppression DWI, short-time inversion recovery (STIR) combination, and chemical shift selective (CHESS) combination DWI were performed to examine 10 phantoms with gadolinium-meglumine gadopentetate (Gd-DTPA) dissolved at concentrations from 0.0005 to 0.1 mmol in physiologic saline as a contrast medium. The average pixel value and ADC of each method were determined. ADC showed no differences between before and after treatment with contrast medium for all imaging techniques with Gd considered distributed over the whole tumor. The signal intensity did not change on nonfat suppression or CHESS combination DWI, but deteriorated on STIR. ADC was not influenced by the magnetic susceptibility of contrast medium. In addition, it was suggested that the ability of tumor detection may be reduced if STIR is used as fat suppression.

ガドリニウム造影剤を用いた冠動脈造影

To investigate the clinical usefulness of coronary arteriography using a gadolinium contrast medium (hereinafter referred to as Gd contrast medium) in patients with iodine allergy, images obtained using an iodinated contrast medium and a Gd contrast medium were compared using respective phantoms. Within the range of the effective energy (34.8 to 41.0 keV) in clinical use, the tube-voltage dependency of the Gd contrast medium was lower than that of the iodinated contrast medium. The contrast ratios were found to be comparable for the images obtained by a 4-fold-diluted iodinated contrast medium and the undiluted Gd contrast medium. Although the assessment of stenotic ratio was difficult to obtain by visual evaluation of the clinical images, due to unclear borders of the blood vessels, the presence or absence of significant stenosis was discriminative by arteriography using the Gd contrast medium. Based on these findings, it was considered necessary to make a confirmed diagnosis using a Gd contrast medium with concurrent diagnosis by intravascular echography. In conclusion, coronary arteriography and PCI using a Gd contrast medium are considered to offer benefit to the diagnosis and treatment of patients with iodine allergy.

Improvement of Signal-to-Noise Ratio Using a Genetic Algorithm for Low-Density DSA Images

Iodine contrast medium is used in Digital Subtraction Angiography (DSA) examination, in which the contrast medium is injected into a blood vessel, and images are collected in real time. However, when iodine contrast medium is used for a patient having iodine contraindication or an iodine allergy, critical side effects may occur. We compared the DSA image of Gadolinium (Gd) contrast medium and iodine contrast medium in order to investigate DSA examination using Gd contrast medium. As a result, the contrast provided by Gd contrast medium decreased due to the absorption of X-rays. When the gradation processing (linear gray scale transformation) built into DSA equipment is applied to the image in which the contrast has decreased, there is also the possibility that the image will become unusable for diagnosis due to increased noise. The present study devised a nonlinear gray scale transformation process using Gd contrast medium by which noise to the DSA image is not increased. As main techniques, the genetic algorithm which can perform optimization and search was applied to image processing. As a result of calculating the optimal gray scale transformation function using a genetic algorithm, and applying this function to a DSA image using Gd contrast medium, the obtained image contained information required for diagnosis.

Imaging of sacroiliitis in early seronegative spondylarthropathy. Assessment of abnormalities by MR in comparison with radiography and CT

To analyze the type and frequency of abnormalities of the sacroiliac joint (SIJ) in early seronegative spondylarthropathy (SpA) by MR in comparison with CT and radiography, assess the most appropriate MR sequences to be used, and introduce a new way of grading MR abnormalities of the SIJ. The SIJs of 41 patients with early SpA (median duration of inflammatory low back pain of 19 months) were evaluated by MR imaging using STIR, T1, T2, and T1 fat saturated (FS) sequences before and after i.v. Gd contrast medium followed by staging of abnormalities. The findings were compared with those obtained by CT and radiography. MR and CT had equal efficacy superior to radiography in staging of erosions and osseous sclerosis. Only MR allowed visualization and grading of active inflammatory changes in the subchondral bone and surrounding ligaments in addition to bone marrow fatty accumulations. T2-weighted sequences did not contribute to assessment of sacroiliitis. MR of the SIJs is reliable in its visualization of joint erosions in early SpA and allows differentiation between active and chronic sacroiliitis. We recommend the following sequences: semicoronal T1 and both semicoronal and semiaxial STIR. If these images are normal, the examination can be finished; otherwise additional semicoronal T1 FS before and after i.v. contrast has to be performed as well as semiaxial post-contrast T1 FS.

Arterial first pass gadolinium-CM dynamics as a function of several intravenous saline flush and Gd volumes.

This study was performed to evaluate the dynamics of an arterial first pass gadolinium (Gd) contrast medium (CM) bolus at the descending aorta (DAo), depending on various saline flush and Gd volumes. Using an ultra-fast two- dimensional GE-sequence (Siemens Vision, 1.5-T), 200 sequential cross-sectional images of the addressed vessel (1 slice/s) were obtained. Several saline flush volumes (15 mL, 30 mL, and 60 mL) were applied following the administration of 10 mL Gd (single dose) to a group of 4 normal volunteers (body weight 50-55 kg) using a mechanical MR injector (injection rate = 3.0 mL/s). Additionally, when performing a second test series, the saline volume remained constant, while the Gd volumes were varied from half doses to triple doses (5, 10, 20, and 30 mL Gd were given to every volunteer of the group). The signal intensity versus time (SI/T) curve at a measured region of interest (ROI) within the DAo was calculated. The bolus arrival time (BAT), the maximal signal-to-noise ratio (SNR(max)), the bolus time length (BL; 75% and 80% maximum intensity duration), the slope of the SI/T curve, and the areas below the SI/T curve for both the 80% and 75% maximum intensity duration level (INT(80%) and INT(75%)) were calculated. The increase of saline flush volume from 30 to 60 mL caused significant bolus lengthening of approximately 50% (mean BL = 9.5 s, 10.3 s, and 15.4 s for 15 mL, 30 mL, and 60 mL saline flush volumes, respectively, measured as SI/T duration at the 75% SNR(max) level). Using saline flush volumes equal to or higher than 30 mL increased the slope of the SI/T curve. A continuous increase of INT(75%/80%) by using higher saline flush volumes was found. Different saline and Gd volumes did not affect the SNR(max) and the BAT. Only the low dose (0.05 mmol/kg Gd) showed a 17%-21.6% significantly lower SNR(max). The BL and the INT increased mainly by enlarging of applied Gd volume from single to double dose (BL(75%) and INT(75%) were 9.6 s and 1305, 12.3 s and 2121, 38.5 s and 6181, 37.8 s and 6613 for 5, 10, 20, and 30 mL applied Gd volume, respectively). The arterial bolus length benefits from increasing Gd and saline flush volumes due to increased venous bolus length and wash out effects of Gd within the injection site of the vein. Doses larger than a single dose are not needed to increase the SNR in contrast-enhanced magnetic resonance angiography images of the thoracic aorta.