Quantification of pulmonary blood flow (PBF): Validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with HO positron emission tomography (PET)

A View on Imaging in Drug Research and Development for Respiratory Diseases

“…MRI perfusion assessments in animals have been accomplished primarily using contrastenhanced techniques comprising the dynamic acquisition of images in combination with the administration of a paramagnetic contrast agent (Neeb et al, 2009). Such an approach has been used to analyze a rabbit model of pulmonary embolism (Keilholz et al, 2009) and a newborn piglet model of pulmonary hypertension (Ryhammer et al, 2007).…”

Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Quantitative Lung Perfusion Imaging Using the Dual-Bolus Approach

“…Selection of a suitable contrast dose is a challenge, as a linear relationship between contrast agent concentration and the signal time course of the parenchyma can be achieved at small doses only. 14,28,29 Previous studies have demonstrated that the use of the dual-bolus technique improves DCE-MRI for lung perfusion measurement by avoidance of signal saturation in the AIF measurements and simultaneous increase in tissue signal. 16,17 More exact perfusion quantification was noted using the dual-bolus approach when compared with single bolus DCE-MRI.…”

Comparison of Models and Contrast Agents for Improved Signal and Signal Linearity in Dynamic Contrast-Enhanced Pulmonary Magnetic Resonance Imaging

“…2" rend="display" xml:id="FD2">$$C_{AIF}false(tfalse)=\sum _{q=0}^{V/V_{\mathit{\text{pre}}}}{S}_{\text{italicrel},\text{italicpre}}false(t+q\tau false);$$ where V is the "bolus" volume, V pre is the "pre-bolus" volume, S rel,pre is the "pre-bolus" signal-time course for the "pre-bolus", and τ is the duration of the "pre-bolus" injection. Therefore the new C AIF is constructed by adding up the "pre-bolus" volume until it matches the volume of the "bolus" injection, while being shifted to achieve the correct kinetics of the "bolus" injection."Non-linear Correction" [10]:Normalized S rel (t) in the AIF from the "bolus" acquisition was corrected to C AIF (t) according to its appropriate calibration curve using the method described by Neeb et al and the signal equation for an SPGR sequence: $$S_{SPGR}false(cfalse)=M_0·\text{exp}false(-TE·R_2^{*}false)·\text{sin}false(\alpha false)·\frac{1-\text{exp}false(-TR·R_{1}false)}{1-\text{cos}false(\alpha false)·\text{exp}false(-TR·R_{1}false)}$$ where signal, S SPGR , is a function of concentration, c; M 0 is the equilibrium longitudinal magnetization; α is the flip angle; and R i (i = 1,2) is the relevant relaxation rate for the CA administered.…”

“…However, it requires two perfusion scans with some intervening delay to allow for sufficient washout of the "pre-bolus" injection. The third method focuses not on the contrast injection protocol itself but instead on a post-processing algorithm to correct for the non-linearity and obtain an accurate AIF signal-time course curve [10]. Despite using a low dose of 0.025 mmol/kg, Neeb et al showed that assuming a linear relationship between signal and CA concentration was not valid for all pulse sequence parameters.…”