Reproducible phantom for quality assurance in abdominal MRI focussing kidney imaging

Abstract

Quality assurance (QA) in magnetic resonance imaging (MRI) requires test objects. ‘Phantoms’ provided by MR manufacturers are homogeneously filled spheres or cylinders, and commercially available products are often too small for abdominal imaging, particularly for enlarged polycystic kidneys. Here we present the design, manufacturing and testing of a dedicated, yet versatile, abdominal MRI phantom, that can be reproduced with relatively low costs. The phantom mimics a human abdomen in size and shape and comprises seven test fluids, representing various tissue types at 3 T. The conductivity and permittivity of the test fluids match the average abdomen and kidney with a relative permittivity (ε) 65 and 72 as well as conductivity 0.6 and 0.7 S/m, respectively. The T1 and T2 relaxation times cover healthy average abdomen and kidney tissue values (T1(abd): 856 ms and T1(kid): 1,106 ms; T2(abd): 52 ms and T2(kid): 67 ms), intermediate (T1: 1,183 ms and 1,271 ms; T2: 128 and 189 ms), and disease values for (polycystic) kidney (T1: 1,428 ms, 1,561 ms and 1763 ms; T2: 319 ms, 424 and 647 ms). T1 and T2 relaxation times were stable over 73 weeks. Our reasonably priced, durable and reproducible abdominal phantom enables single and multi-center QA for future collaborative studies aiming for various challenges around abdominal and, particularly, kidney imaging.

Magnetic resonance elastography resolving all gross anatomical segments of the kidney during controlled hydration

“…Therefore, high-resolution MRE measurements together with high-resolution and contrast-rich anatomical scans were used to segment all gross anatomical segments in the kidneys in three dimensions. Kidney structures were identified based on T 1 contrast, with a well-defined cortico-medullary differentiation ( Wolf et al, 2018 ; Wolf et al, 2022 ). The cortex included the cortical rim and renal columns.…”

Optimization of Fair Arterial Spin Labeling Magnetic Resonance Imaging (ASL-MRI) for Renal Perfusion Quantification in Dogs: Pilot Study

“…The blood sample was scanned with a 2D single-slice inversion recovery turbo spin echo sequence following the literature [ 29 ], TR/TE = 10,000/8.8 ms, Voxel size 0.8 mm × 0.8 mm × 5 mm, we turbo factor 7, bandwidth: 352 Hz/Px, with inversion times 50, 100, 400, 1000, 1600, 1900 ms.…”

Phantoms for Quantitative Body MRI: a review and discussion of the phantom value

“…The first phantom use-case often occurs during the design and validation phase of a new method. While many research phantoms are designed to be replicated by other sites and groups [24], the phantoms used for initial methods development can be home-made or single-use as long as they are sufficiently well-characterized. Although this use-case typically consists of a small user base (e.g., a single research group), the downstream effects of the phantom can be quite influential if the method developed using it makes it to the clinic.…”

“…For body MRI, phantoms have been developed to evaluate specific quantitative MRI techniques, for example, elastography (MRE), chemical shift-encoded proton density fat fraction mapping [13][14][15], quantification of diffusion [16][17][18] and perfusion [19][20][21], susceptibility mapping [5], dynamic imaging [22], and relaxometry [8,23,24]. Given the challenges of body MRI in the presence of physiological motion, many phantoms used by this community simulate motion found within the torso, such as respiratory, cardiac, and blood flow [16,17,23,[25][26][27][28][29][30][31][32].…”