Effect of $$ T_{2}^{*} $$ correction on contrast kinetic model analysis using a reference tissue arterial input function at 7 T

Abstract

Object To investigate the effect of T2* correction on estimation of kinetic parameters from T1-weighted dynamic contrast enhanced (DCE) MRI data when a reference-tissue arterial input function (AIF) is used. Materials and Methods DCE-MRI data were acquired from 7 mice with 4T1 mouse mammary tumors using a double gradient echo sequence at 7T. The AIF was estimated from a region of interest in the muscle. The extended Tofts model was used to estimate pharmacokinetic parameters in the enhancing part of the tumor, with and without T2* correction of the lesion and AIF. The parameters estimated with T2* correction of both the AIF and lesion time-intensity curve were assumed to be the reference standard. Results For the whole population, there was significant difference (p<0.05) in transfer constant (Ktrans) between T2* corrected and not corrected methods, but not in interstitial volume fraction (ve). Individually, no significant differences were found in Ktrans and ve of four and six tumors, respectively, between the T2* corrected and not corrected methods. In contrast, Ktrans was significantly underestimated, if the T2* correction was not used, in other tumors of which median Ktrans was larger than 0.4 min−1. Conclusion T2* effect on tumors with high Ktrans may not be negligible in kinetic model analysis, even if AIF is estimated from reference tissue where the concentration of contrast agent is relatively low.

Quantifying myofiber integrity using diffusion MRI and random permeable barrier modeling in skeletal muscle growth and Duchenne muscular dystrophy model in mice

“…In vivo and ex vivo MRI exams were performed on a 7T Biospec micro‐MRI system (Bruker Biospin MRI, Ettlingen, Germany) equipped with a Bruker BGA‐9S 750‐mT/m gradient coil. Mice were mounted on a custom 3D‐printed mouse holder after general anesthesia was induced using 3% isoflurane in air and placed into a home‐built quadrature volume coil . During the scan, the general anesthesia was lowered to 1.5% isoflurane in air to maintain a respiration rate of approximately 30 breaths/minute.…”

Measurement of blood‐brain barrier permeability using dynamic contrast‐enhanced magnetic resonance imaging with reduced scan time

“…All MR studies were conducted on a 9.4T scanner (Bruker BioSpin MRI, Ettlingen, Germany). A 3D spoiled gradient echo sequence was used for dynamic scans with dual echoes to correct for the effect . The scan parameters were TR = 14 ms, TE1/2 = 2.2/4.6 ms, FA = 12°, FOV = 20 mm × 25 mm × 8 mm, acquisition matrix = 64 × 128 × 8, temporal resolution = 5.37 s/frame, and the total scan time = 967.8 s. A bolus of gadopentetate in saline at the standard dose of 0.1 mmol/kg was injected through a tail vein catheter, starting 1 min after the acquisition of pre‐contrast images.…”

“… values of individual voxels at each time point were estimated from the double‐echo data . Then the ‐corrected time–intensity curves were converted to the concentration curves using Eqs.…”

Estimation of cellular‐interstitial water exchange in dynamic contrast enhanced MRI using two flip angles

“…Furthermore, the UTEbased approach minimized the T 2 * effect, which could be a critical confounding factor, particularly at high fields. 30,60 All these imaging conditions carefully selected in this study may have made it possible to estimate τ i successfully, by minimizing any possible confounding factors that could bias the signal intensities with the two different flip angles used in this study. Further studies are warranted to investigate whether the proposed DFA protocol can be successfully used to measure τ i with conventional imaging pulse sequences and coils.…”

“…Instead, the baseline values above were selected based on several previous studies. 17,24,30 These baseline parameters were used to generate a range of parameters around them (Table 1) for the numerical simulation studies. A populationbased AIF measured in a study with a standard Gd dosage 31 of 0.1 mmol/kg was used to generate all simulation data in this study ( Figure 1A).…”