Automatic passive tracking of an endorectal prostate biopsy device using phase‐only cross‐correlation

Abstract

MR-guided transrectal prostate biopsy is currently a time-consuming procedure because the imaging slice is often manually realigned with the biopsy needle during lesion targeting. In this work a pulse sequence is presented that automatically follows a passive marker attached to a dedicated MR biopsy device holder, thus providing an alternative to existing active tracking methods. In two orthogonal tracking FLASH images of the marker the position of the needle axis is automatically identified using a phase-only cross-correlation (POCC) algorithm. The position information is then used to realign a trueFISP imaging slice in real time. In phantom experiments the sensitivity of this technique to initial misalignments of the marker and to the signal-to-noise ratio was evaluated. In several puncture experiments the precision of the needle placement was analyzed. The POCC algorithm allowed for a precise identification of the marker in the images even under severe initial misalignments of up to 45°. At a frame rate 1 image/s a precision of the needle placement of 1.5 ؎ 1.1 mm could be achieved. Magn Reson Med 59:1043-1050, 2008.

Needle-Guiding Robot for Laser Ablation of Liver Tumors Under MRI Guidance

“…Consequently, a mutual distance between the points larger than 30 mm would result in angular errors smaller than 1 degree. Targeting experiments in the MRI scanner demonstrated errors of 1.5 mm ± 1.1 mm for the localization method [52]. Similar results are expected for this implementation, since it relies on the same formulation, and will be verified experimentally as part of our future work.…”

“…Similarly to [52], the Fourier Filtering Method [53] is employed. However, it is applied here to a volume consisting of adjacent slices instead of individual 2D images.…”

“…As a result, the marker's position can be computed at any instant from a predefined set of slices, without simultaneously updating the sequence parameters on the MRI scanner. Instead, in [52] the position of two slices containing the marker should be constantly updated, which required the use of special imaging sequences. From [53], the relationship between the Fourier transforms M and I of the acquired volume and of a template sphere of known radius is:…”

Design and control of 3-DOF needle positioner for MRI-guided laser ablation of liver tumours

“…Additionally they do not experience heating and are therefore completely safe. Passive markers are typically localised using image processing methods such as template matching (de Oliveira et al, 2008). These methods are applicable in principle to all types of markers and can be used with standard imaging sequences.…”

Interventional MR-imaging for thermal ablation therapy

“…active needles [4]. In contrast, we employ a passive guidance approach [5,6] working with standard MR-compatible needles. Based on the trajectory planned by the user, we automatically align the MRI slices and detect the device directly from continuously acquired MR images based on exploiting signal voids induced by the device [7].…”