MRI robot for prostate focal laser ablation : An ex vivo study in human prostate

Purpose: A novel grid-template-mimicking MR-compatible robot was developed for in-gantry MRI-guided focal laser ablation of prostate cancer. Method: A substantially compact robot was designed and prototyped to meet in-gantry lithotomy ergonomics and allow for accommodation in the perineum. The controller software was reconfigured and integrated with the custom-designed navigation and multi-focal ablation software. Three experiments were conducted: (1) free space accuracy test; (2) phantom study under computed tomography (CT) guidance for image-guided accuracy test and overall workflow; and (3) magnetic resonance imaging (MRI)-guided focal laser ablation of an ex vivo prostate. The free space accuracy study included five targets that were selected across the workspace. The robot was then commanded five times to each target. The phantom study used a gel phantom made with color changing thermos-chromic ink, and four spherical metal fiducials were deployed with the robot. Then, laser ablation was applied, and the phantom was sliced for gross observation. For an MR-guided ex vivo test, a prostate from a donor who died of prostate cancer was obtained and multi-focally ablated using the system within the MRI gantry. The tissue was sliced after ablation for validation. Results: free-space accuracy was 0.38 ± 0.27 mm. The overall system targeting accuracy under CT guidance (including robot, registration, and insertion error) was 2.17 ± 0.47 mm. The planned ablation zone was successfully covered in both acrylamide gel phantom and in human prostate tissue. Conclusions: The new robot can accurately facilitate fiber targeting for MR-guided focal laser ablation of targetable prostate cancer

Increased superoxide production contributes to the impaired angiogenesis of fetal pulmonary arteries with in utero pulmonary hypertension

Persistent pulmonary hypertension of newborn (PPHN) is associated with impaired pulmonary vasodilation at birth. Previous studies demonstrated that a decrease in angiogenesis contributes to this failure of postnatal adaptation. We investigated the hypothesis that oxidative stress from NADPH oxidase (Nox) contributes to impaired angiogenesis in PPHN. PPHN was induced in fetal lambs by ductus arteriosus ligation at 85% of term gestation. Pulmonary artery endothelial cells (PAEC) from fetal lambs with PPHN (HTFL-PAEC) or control lambs (NFL-PAEC) were compared for their angiogenic activities and superoxide production. HTFL-PAEC had decreased tube formation, cell proliferation, scratch recovery, and cell invasion and increased cell apoptosis. Superoxide (O2−) production, measured by dihydroethidium epifluorescence and HPLC, were increased in HTFL-PAEC compared with NFL-PAEC. The mRNA levels for Nox2, Rac1, p47phox, and Nox4, protein levels of p67phox and Rac1, and NADPH oxidase activity were increased in HTFL-PAEC. NADPH oxidase inhibitor, apocynin (Apo), and antioxidant, N-acetyl-cysteine (NAC), improved angiogenic measures in HTFL-PAEC. Apo and NAC also reduced apoptosis in HTFL-PAEC. Our data suggest that PPHN is associated with increased O2− production from NADPH oxidase in PAEC. Increased oxidative stress from NADPH oxidase contributes to the impaired angiogenesis of PAEC in PPHN

Template for MR Visualization and Needle Targeting

© 2018, Biomedical Engineering Society. To improve the targeting accuracy and reduce procedure time in magnetic resonance imaging (MRI)-guided procedures, a 3D-printed flexible template was developed. The template was printed using flexible photopolymer resin FLFLGR02 in Form 2 printer ® (Formlabs, Inc., Somerville, MA). The flexible material gives the template a unique advantage by allowing it to make close contact with human skin and provide accurate insertion with the help of the newly developed OncoNav software. At the back of the template, there is a grid comprised of circular containers filled with contrast agent. At the front of the template, the guide holes between the containers provide space and angular flexibility for needle insertion. MRI scans are initially used to identify tumor position as well as the template location. The OncoNav software then pre-selects a best guide hole for targeting a specific lesion and suggests insertion depth for the physician A phantom study of 13 insertions in a CT scanner was carried out for assessing needle placement accuracy. The mean total distance error between planned and actual insertion is 2.7 mm, the maximum error was 4.78 mm and standard deviation was 1.1 mm. The accuracy of the OncoNav-assisted and template-guided needle targeting is comparable to the robot-assisted procedure. The proposed template is a low-cost, quickly-deployable and disposable medical device. The presented technology will be further evaluated in prostate cancer patients to quantify its accuracy in needle biopsy

Tracked Foley catheter for motion compensation during fusion image-guided prostate procedures: a phantom study

© 2020, The Author(s). Background: Uncorrected patient or prostate motion may impair targeting prostate areas during fusion image-guided procedures. We evaluated if a prototype “tracked Foley catheter” (TFC) could maintain fusion image alignment after simulated organ motion. Methods: A pelvic phantom model underwent magnetic resonance imaging (MRI), and the prostate was segmented. The TFC was placed in the phantom. MRI/ultrasound (US) fusion was performed. Four trials were performed varying motion and TFC presence/absence: (1) TFC/no-motion, (2) TFC/motion, (3) no-TFC/no-motion, and (4) no-TFC/motion. To quantify image alignment, screen captures generated Dice similarity coefficient (DSC) and offset distances (ODs) (maximal US-to-MRI distance between edges on fusion images). Three anatomical targets were identified for placement of a needle under fusion guidance. A computed tomography scan was used to measure system error (SE), i.e., the distance from needle tip to intended target. Results: The TFC presence improved MRI/US alignment by DSC 0.88, 0.88, 0.74, and 0.61 in trials 1, 2, 3, and 4, respectively. Both OD (trial 2 versus trial 4, 4.85 ± 1.60 versus 25.29 ± 6.50 mm, p \u3c 0.001) and SE (trial 2 versus trial 4, 6.35 ± 1.31 versus 32.16 ± 6.50 mm, p \u3c 0.005) were significantly lower when the TFC was present after artificial motion, and significantly smaller OD when static (trial 1 versus trial 3, 4.29 ± 1.24 versus 6.42 ± 2.29 mm, p \u3c 0.001). Conclusion: TFC provided better image alignment with or without simulated motion. This may overcome system limitations, allowing for more accurate fusion image alignment during fusion-guided biopsy, ablation, or robotic prostatectomy

Correlation of ultrasound tomography to MRI and pathology for the detection of prostate cancer

© 2019 SPIE. Purpose: This study aims to investigate correlation of speed of sound (SoS) map with T2-weighted (T2w) MRI and pathology in an ex vivo human prostate tissue with cancer, as an early proof of concept towards cost effective augmented ultrasound diagnosis of prostate cancer. Method: A commercial breast full angle ultrasound tomography scanner was used to generate US tomography images. Prostate-specific Echolucent mold was fabricated to allow MRI and UST to be spatially correlated. Similarly, a 3D printed mold was developed to align the histology slices with the UST and MRI. The resulting slices of prostate tissue were H and E stained. A radiologist with 10 years of experience in using multi parametric MRI for prostate cancer diagnosis labeled and contoured the suspicious ROIs in both MRI and UST. For all tissue blocks (N=10 slices with 6 mm thickness), H and E slides were prepared and labeled by an expert pathologist. Results: The radiologist found two slices with prominent cancer in each modality (i.e. MR and UST) in the peripheral zone. These two pairs of slices correlated with each other and with slices #5 and #7 in pathology. The cancer ROIs were found at similar locations in all modalities, although MR and UST underestimated the size of lesions (Sørensen-Dice coefficients, with respect to pathology, for T2w and UST were 0.11 and 0.20 respectively for first ROI, and 0.33 and 0.27 for second ROI). The SoS was 1580.4±17.7 m/s and 1571.4±9.2 m/s for normal and cancer tissues in first ROI, and 1577.7±17.7 m/s and 1574.5±10.1 m/s for second ROI. Conclusions: SoS map can correlate with MRI and pathology findings in prostate cancer. Further ex vivo validation with fresh prostate tissue is warranted