Portable perfusion phantom for quantitative DCE‐MRI of the abdomen

Abstract

Purpose To develop a portable perfusion phantom and validate its utility in quantitative dynamic contrast-enhanced magnetic resonance imaging of the abdomen. Methods A portable perfusion phantom yielding a reproducible contrast enhancement curve (CEC) was developed. A phantom package including perfusion and static phantoms were imaged simultaneously with each of three healthy human volunteers in two different 3T MR scanners. Look-up tables correlating reference (known) contrast concentrations with measured ones were created using either the static or perfusion phantom. Contrast maps of image slices showing four organs (liver, spleen, pancreas, and paravertebral muscle) were generated before and after data correction using the look-up tables. The contrast concentrations at 4.5 minutes after dosing in each of the four organs were averaged for each volunteer. The mean contrast concentrations (4 organs x 3 volunteers = 12) were compared for the two scanners, and the intra-class correlation coefficient (ICC) was calculated. Also, the ICC of the mean Ktrans values between the two scanners was calculated before and after data correction. Results The repeatability coefficient of CECs of perfusion phantom was higher than 0.997 in all measurements. The ICC of the tissue contrast concentrations between the two scanners was 0.693 before correction, but increased to 0.974 after correction using the look-up tables (LUTs) of perfusion phantom. However, the ICC was not increased after correction using static phantom (ICC: 0.617). Similarly, the ICC of the Ktrans values was 0.899 before correction, but increased to 0.996 after correction using perfusion phantom LUTs. The ICC of the Ktrans values, however, was not increased when static phantom LUTs were used (ICC: 0.866). Conclusions The perfusion phantom reduced variability in quantifying contrast concentration and Ktrans values of human abdominal tissues across different MR units, but static phantom did not. The perfusion phantom has the potential to facilitate multi-institutional clinical trials employing quantitative DCE-MRI to evaluate various abdominal malignancies.

Quantitative imaging biomarkers alliance (QIBA) recommendations for improved precision of DWI and DCE‐MRI derived biomarkers in multicenter oncology trials

“…Phantom quality control may ensure adequate precision and reproducibility in T 1 measurements, a prerequisite for performing quantitative DCE analysis. It also allows for the measurement of the contrast response of the employed DCE acquisition sequence across a range of T 1 relaxation rates observed in in vivo DCE studies and the stability of that contrast response over time and across system upgrades …”

“…In addition to static T 1 phantoms, some investigators have developed dynamic phantoms for MRI (Kim et al), and computed tomography (CT) (Driscoll et al). The recent perfusion phantom was developed to correct MR scanner‐dependent variations in estimates of the tissue perfusion parameters in the abdomen . The design of Kim et al is shown in Fig.…”

“…b). Kim et al have demonstrated that this phantom significantly reduced the variation in quantifying perfusion parameters of various abdominal tissues across two different 3T scanners . However, the stability of this and other dynamic phantoms will need to be validated in longitudinal multisite trials because such dynamic phantoms are difficult to produce in a manner that provides consistent results across phantoms and time.…”

“…It also allows for the measurement of the contrast response of the employed DCE acquisition sequence across a range of T 1 relaxation rates observed in in vivo DCE studies and the stability of that contrast response over time and across system upgrades. 70,71 DCE acquisition parameters can vary significantly across vendors, scanners, station software packages, and magnetic field strengths. Often, each vendor and platform has preferred acquisition protocols.…”

Translating preclinical MRI methods to clinical oncology

“…With DSC‐MRI, validation efforts have included in vivo comparisons of blood volume and blood flow measures to those derived from positron emission tomography (PET) and single photon emission computed tomography (SPECT), histology, and synthetic patient datasets . Similarly, numerous studies have validated DCE‐MRI methods using physical phantoms, and parameters in different organs using autoradiography, histology, and DCE computed tomography (CT) . There is also an extensive literature validating cerebral perfusion measures from ASL using [ 15 O]‐water PET .…”