Geometric accuracy in three‐dimensional coordinates of Leksell stereotactic skull frame with wide‐bore 1.5‐T MRI compared with conventional 1.5‐T MRI

Abstract

The use of 1.5-tesla (T) magnetic resonance (MR) imaging with a wide and simultaneously short bore enhances patient comfort compared with traditional 1.5-T MR imaging and is becoming increasingly available in stereotactic radiosurgery treatment planning. However, the geometric accuracy seems unavoidably worse in wide-bore MR imaging than in conventional MR imaging. We assessed the geometric distortion of the stereotactic image attached on a Leksell skull frame in conventional and wide-bore 1.5-T MR imaging. Two kinds of acrylic phantoms were placed on the skull frame and were scanned using computed tomography (CT) and conventional and wide-bore 1.5-T MR imaging. The three-dimensional coordinates on both MR imaging were compared with those on CT. Deviations of measured coordinates at selected points (x = 50, 100, 150 mm; y = 50, 100, 150 mm) were indicated on different axial planes (z = 50, 75, 100, 125, 150 mm). The differences of coordinates were less than 1.0 mm in the entire treatable area for conventional MR imaging. With the large bore system, the differences of the coordinates were less than 1.0 mm around the center but substantially exceeded 1.0 mm in the peripheral regions. Further study is needed to increase the geometric accuracy of wide-bore MR imaging for stereotactic radiosurgery treatment planning.

Image quality assessments according to the angle of tilt of a flex tilt coil supporting device: An ACR phantom study

“…A few studies showed that magnetic field inhomogeneity and gradient field nonlinearity increase toward the periphery away from the magnet isocenter, thus leading to nonuniform intensity. 9,11,21 As well, differences in the measured values resulting from changes in the angle of tilt coil and phantom positioning may influence the RF…”

Liver acquisition with volume acceleration flex on 70-cm wide-bore and 60-cm conventional-bore 3.0-T MRI

“…However, the SNR of the pancreas on wide-bore 3.0-T MRI was lower than that on conventional-bore 3.0-T MRI for both LAVA-Flex and LAVA. The geometric accuracy is unavoidably worse with wide-bore MRI than with conventional MRI [19]. In particular, achieving high geometric accuracy becomes problematic when imaging a large body area such as the upper and lower abdomen using high-field large-bore MRI systems.…”

“…The new high-field MRI systems with wide bore provide satisfactory patient access and allow performing MR fluoroscopy for biopsy [17,18]. However, geometric accuracy unavoidably decreased in wide-bore MRI compared to that in conventional MRI [19]. In particular, achieving sufficient geometric accuracy is problematic when using high-field wide-bore MRI systems for abdominal MRI, which covers a wide body area (upper and lower abdomen).…”

The posterior cranial fossa: a comparative MRI-based anatomic study of linear dimensions and volumetry in a homogeneous South Indian population

“…MRI images are subject to distortion and loss of accuracy of spatial resolution as the slice thickness reduces, interslice distance reduces or acquisition parameters vary [1,21,32,34]. The volumes calculated on MR images are only an estimation of the true PCFV.…”