A phantom was made by 7 cylinders filled with Gd-DTPA (MW= 938 Da; Bayer Healthcare) in 500 ml of regular water with the following amounts of Gd-DTPA: 8.0, 4.0, 1.6, 0.8, 0.4, 0.2, and 0.0 ml. These values were calculated to mimic the following doses of Gd-DTPA for the human experiment; 0.5, 0.25, 0.1, 0.05, 0.025, 0.0125, and 0.0 mmol/kg, respectively. Phantom data were acquired with the same imaging protocol that was used to acquire human data.
Gd dtpa
Manufactured by Bayer
Sourced in Germany
Gd-DTPA is a paramagnetic contrast agent used in magnetic resonance imaging (MRI) procedures. It contains the element gadolinium (Gd) chelated with the organic compound diethylenetriaminepentaacetic acid (DTPA). Gd-DTPA enhances the contrast of images in MRI scans by altering the magnetic properties of nearby water molecules, allowing for improved visualization of tissues and structures within the body.
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Lab products found in correlation
Magnevist, by Bayer (3 mentions)
Signa excite hd, by GE Healthcare (2 mentions)
Dedicated small animal 7 t mri system, by Bruker (2 mentions)
Discovery mr750, by GE Healthcare (2 mentions)
Ingenia, by Philips (2 mentions)
Echo speed, by GE Healthcare (1 mentions)
Discovery 750w, by GE Healthcare (1 mentions)
Verio 3.0t, by Siemens (1 mentions)
Signa hdxt, by GE Healthcare (1 mentions)
Gyroscanachieva 1.5 t, by Philips (1 mentions)
Fomblin, by Solvay (1 mentions)
Mr prisma 3, by Siemens (1 mentions)
Signa excite hdx 3.0t, by GE Healthcare (1 mentions)
Optima mr360, by GE Healthcare (1 mentions)
Dotarem, by Guerbet (1 mentions)
Gd dota, by Guerbet (1 mentions)
Biospin magnet, by Bruker (1 mentions)
Signa hdx 3.0t scanner, by GE Healthcare (1 mentions)
Pharmascan 70 16 us, by Bruker (1 mentions)
Magnetom aera 1.5t scanner, by Siemens (1 mentions)
34 protocols using gd dtpa
1
Gd-DTPA Phantom for MRI Calibration
2
MRI Imaging of Tumor Necrosis
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MRI was performed using a clinical 1.5T MR magnet (Echo speed; GE Co., NY) with a rat coil for rat studies. Under isoflurane gas anesthesia, T1-weighted (T1W) and T2-weighted (T2W) spin-echo multi-slice coronal images were acquired. Then contrast enhanced T1-weighted (CE-T1W) images were obtained immediately after i.v. administration of Gd-DTPA (Bayer Schering Pharma AG, Berlin, Germany) at 0.2 mmol/kg. The related parameters are described below: Field of view (FOV) = 100 mm × 100 mm; T1W: Sequence SE, TR/TE = 550 ms/24 ms; T2W: Sequence FSE, TR/TE = 2920 ms/88 ms; CE-T1W: Sequence SE, TR/TE = 550 ms/60 ms.
Quantifications of tumor area were done by manually delineating the outline of the tumor mass on each T2W MRI slice covering the whole tumor. Tumor volume was calculated using the equation: tumor volume = Σ [tumor area on each slice × (slice thickness)]. The area of central nonenhancing region was delineated from CE-T1W images to estimate necrosis. The ratios of necrosis were defined as the volume of necrosis over that of entire tumor, i.e. necrosis ratio = Σ (area of necrosis × slice thickness)/(area of whole tumor × slice thickness) × 100%.
Quantifications of tumor area were done by manually delineating the outline of the tumor mass on each T2W MRI slice covering the whole tumor. Tumor volume was calculated using the equation: tumor volume = Σ [tumor area on each slice × (slice thickness)]. The area of central nonenhancing region was delineated from CE-T1W images to estimate necrosis. The ratios of necrosis were defined as the volume of necrosis over that of entire tumor, i.e. necrosis ratio = Σ (area of necrosis × slice thickness)/(area of whole tumor × slice thickness) × 100%.
3
Standardized Liver MRI Imaging Protocol
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A uniform MRI scanner and scanning protocol were applied for all patients across both institutions. The MRI procedures were conducted using a 3.0 T system (Discovery 750w, GE Healthcare). Standard liver protocols included axial breath-hold IDEAL IQ, axial T2-weighted fast spin-echo sequence, and axial breath-hold T1-weighted three-dimension fat-suppressed spoiled gradient-echo sequence with liver acquisition and volume acceleration. Following this, Gd-diethylenetriamine pentaacetic acid (Gd-DTPA, Bayer Schering Pharma, Germany) contrast agent was administered via the cubital vein at 1.0 ml/s and 0.025 mmol/kg. Subsequently, the T1-weighted three-dimension fat-suppressed spoiled gradient-echo sequence was repeated. The dynamic contrast-enhanced scanning process included arterial phase (AP, 20-45 s), portal vein phase (PVP, 50-75 s), and delayed phase (DP, 90 s) images. Table 1
4
Targeted Glioblastoma Treatment Protocol
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Five days after the implantation, the 40 rats were evenly divided into five groups and injected with PBS, TMZ-FaPEC@siRNA, TMZ-PEC@siRNA, TMZ-FaPEC@SCR, and FaPEC@siRNA, respectively. Treatments were given every four days at the doses of 120 μg/kg TMZ and 1.6 μg/kg siRNA. The five injection points for each treatment were 4, 4.5, 5, 5.5, and 6 mm away from the dura, respectively, and the needle was kept still for 5 min before retraction. Twenty-five days after the first injection, Gd-DTPA (Bayer Schering Pharma AG, Berlin, Germany) was intravenously administered at a dose of 150 μL/kg, and then the rats were subjected to magnetic resonance imaging (MRI) for the measurement of tumor volume. T1-weighted sequence was employed to acquire images as reported.19 (link) The mean tumor volume (mm3) was calculated as π×a×b×c/2, in which a, b, and c represented coronal long diameter, coronal short diameter, and sagittal long diameter, respectively.
5
Multiparametric MRI for Tumor Evaluation
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In this study, the Siemens Verio 3.0 T superconducting MR scanner (Germany) was used, and 112 patients underwent T1WI, T2WI, DWI, and contrast-enhance MRI before surgery. The parameters for MRI included the following: T1WI (TR/TE = 550/11 ms), slice thickness = 5.0 mm, layer spacing 1.5 mm, matrix = 256 × 256, field of view (FOV) = 260 mm × 260 mm; T2WI (TR/TE = 2200/96 ms), echo chain length = 8, and number of excitation (NEX) = 2. The parameters for DWI (SEEPI sequence) were as follows: frequency selection fat suppression technology, (TR/TE = 4000/100 ms), slice thickness = 5 mm, layer spacing 1.5 mm, matrix = 256 × 192, FOV = 260 mm × 260 mm, and diffusion gradients applied in three orthogonal directions (b value = 0, 1000 s/mm2). Axial, sagittal, and coronary enhanced T1WI were obtained using Gd-DTPA (Bayer Schering Pharma AG) at 0.1 mmol/kg at a rate of 3.0 mL/s.
6
Multimodal MRI Acquisition Protocol
7
Standardized MRI Examination for HCC
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MRI examination was performed using 1.5 T or 3.0 T MR systems (Signa, HDXT, GE Healthcare) with an eight-channel phased array body coil. MR scan sequences included in- and opposed-phase fast-spoiled gradient-recalled echo T1-weighted (T1W) sequence, fat-suppressed fast spin-echo T2-weighted (T2W) sequence, and contrast-enhanced imaging with fat-suppressed T1-weighted three-dimensional (3D) fast-spoiled gradient-recalled echo sequence. The images in arterial phase (AP), portal venous phase (PVP), and delayed phase (DP) were acquired during suspended respiration at 40 s, 70 s, and 90 s, respectively, after initiation of the injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) (Bayer Schering Pharma AG) at a patient weight-dependent dose of 0.1 mmol/kg with an injection rate of 2.5 ml/s through median cubital vein. Of the 122 HCC patients described above, 100 patients were examined with the 1.5 T system, and the other 22 patients with the 3.0 T system. The detailed parameters of each scan sequence are listed in Supplementary Data S1
8
MRI Imaging Protocol for Brain Assessment
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1.5T MRI (GyroscanAchieva 1.5 T, Philips Healthcare, Best, Netherlands) equipped with an 8-channel head coil was used to performed the scan. The acquisition parameters were as follows: pre-contrast T1-weighted (T1-w) images (TR/TE = 593/15 ms, FOV = 18 × 18 cm, matrix = 256 × 256, slice thickness = 5 mm, spacing = 1.0 mm); T2-weighted (T2-w) images (TR/TE = 3720/100 ms, FOV = 18 × 18 cm, matrix = 256 × 256, slice thickness = 5 mm, spacing = 1.0 mm); T2/fluid-attenuated inversion-recovery (T2/FLAIR) images (TR/TE: 11000/140 ms, range of inversion time = 2400 ms, FOV = 18 × 18 cm, matrix = 256 × 256, slice thickness = 5 mm, spacing = 1.0 mm); and contrast-enhanced T1-w images (TR/TE: 488/15 ms, FOV = 18 × 18 cm, matrix = 256 × 256, slice thickness = 5 mm, spacing = 1.0 mm). Contrast MRI was performed using GD-DTPA (Bayer, Germany) at a dose of 0.1 mmol/kg.
9
Measuring Brain Tumor Volumes in Rats
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To measure the volume of brain tumors, rats were examined every 7 days using a 7T magnetic resonance imaging (MRI) system (Magnet: Kobelco and JASTEC, Kobe, Japan; Console: Bruker Biospin, Ettingen, Germany) after intraperitoneal injection of 0.4 ml of Gd-DTPA (Meglumine gadpentate, Bayer, Leverkusen, Germany) 15 min before imaging. Multislice trans-axial T1-weighted MR images covering the entire brain (T1WI; multi-slice spin echo, TR/TE = 400/9.57 ms, 256 × 256, field of view = 25.6 × 25.6 mm2, average = 4) were acquired. In order to measure the tumor volume, MRI images were analyzed by OsiriX.
10
Nasopharyngeal MRI Imaging Protocol
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MR imaging examinations of the whole nasopharynx were performed using a 3.0-T whole-body system (Signa Excite HD, GE Healthcare, Milwaukee, WI) with a 40-mT/m maximum gradient capability and a standard receive-only head and neck coil. The imaging protocol included axial T1-weighted spin-echo images (repetition time (TR)/echo time (TE) 600/23 ms, 4 mm section thickness with a 1-mm intersection gap and number of excitations (NEX) equal to 2), contrast-enhanced axial and coronal T1-weighted spin-echo images following a bolus injection of 0.1 mmol/kg of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA; Bayer Healthcare, Berlin, Germany), and axial T2-weighted turbo spin-echo images with fat suppression (TR/TE 5,200/137 ms; 4 mm section thickness, with 1 mm intersection gap and NEX = 2) using a 512 × 288 imaging matrix.
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