Determination of the venous output function from MR signal phase: Feasibility for quantitative DCE-MRI in human brain

Abstract

For dynamic contrast-enhanced MRI studies in the human brain, it is useful to measure the venous output function (VOF). The purpose of this work was to explore the feasibility of measuring the VOF using the MR signal phase (in absolute units of gadolinium concentration) in the superior sagittal sinus. Phantom experiments were performed to validate the technique for different superior sagittal sinus angles (h 5 0-488 relative to the main magnetic field), different curvatures (straight or radius 5 45 mm), and different spatial resolutions (2.2-5.5 mm, to study partial-volume effects). Additionally, the technique was tested on three patients. The phantom experimental results (echo time 5 5.5 ms, h ≤ 218) agreed with theoretical predictions to within 10%. For the patient studies, the measured VOFs had reasonable amplitude and shape characteristics and the patients' superior sagittal sinus angles (<158) and curvatures (radii ≈ 40 mm) were within the range explored with phantoms. Our results suggest that partial-volume contributions to the VOF will be <5% and that the VOF can be evaluated in vivo to within 10% error. In conclusion, it is highly feasible to use MR signal phase to measure the VOF in the superior sagittal sinus for human dynamic contrast-enhanced MRI. Magn Reson Med 63:772-781,

Diagnostic Accuracy of Dynamic Contrast-Enhanced MR Imaging Using a Phase-Derived Vascular Input Function in the Preoperative Grading of Gliomas

“…8 The authors obtained a median transfer constant for grade IV gliomas of 0.107 minutes Ϫ1 , which is similar to our K trans _SI of 0.15 minutes Ϫ1 . They also found a statistically significant difference between the transfer constants for grade III and IV gliomas but not between grades II and III, which is consistent with our findings.…”

“…8,9,15 For that reason, some authors have proposed performing 2 injections of 0.05 mmol/kg of gadolinium for DCE MR imaging to minimize the error arising from the conversion of signal intensity to gadolinium concentration from magnitude images. 16 While saturation of signal intensity could lead to an underestimation of the contrast agent concentration, the presence of inflow effects could lead to an overestimation.…”

“…This step was performed off-line by using in-house software written in IDL (ITT Visual Information Solutions, Boulder, Colorado) and is described in a previous article. 8 Voxel-by-voxel estimates of V p_ and K trans _ were determined by using a kinetic model analysis from the nordicICE software (Version 2; NordicNeuroLab, Bergen, Norway) as described in the Appendix. Representative parametric maps of V p_ and K trans _ are shown in Fig 1B, -C.…”

“…6,7 Recently, several authors have proposed the use of phase information to derive the VIF. 8,9 It is known that if a vessel is approximately parallel to the magnetic field, changes in gadoliniumbased contrast agent concentration vary linearly with phase changes. 10 Because phase images can be acquired at the same time as magnitude images, no additional imaging is required.…”

Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas

“…7,8 Recently, some au-thors have suggested that measuring changes in the phase of the MR signal rather than its magnitude following gadolinium injection might provide a more accurate VIF because phase change inside the vessel is linearly related to the concentration of contrast agent. [9][10][11][12] While measurement of precontrast tissue T1 is typically included in DCE-MR imaging studies, an additional measurement of tissue T1 postinjection ("bookend" method) might also improve the reproducibility of perfusion values in gliomas. 13,14 To our knowledge, there have been few comparative studies between DCE and DSC imaging in patients with gliomas.…”