Language：English   Publisher：Nagoya Journal of Medical Science  

Prostatic urethra identification is crucial in prostate stereotactic body radiotherapy (SBRT) to reduce the risk of urinary toxicity. Although computed tomography (CT) with a catheter is commonly employed, it is invasive, and catheter placement may displace the urethral position, resulting in possible planning inaccuracies. However, magnetic resonance imaging (MRI) can overcome these weaknesses. Accurate urethral identification and minimal daily variation could ensure a highly accurate SBRT. In this study, we investigated the usefulness of a three-dimensional (3D) T2-weighted (T2W) sequence for urethral identification, and the interfractional motion of the prostatic urethra on CT with a catheter and MRI without a catheter for implementing noninvasive SBRT. Thirty-two patients were divided into three groups. The first group underwent MRI without a catheter to evaluate urethral identification by two-dimensional (2D)- and 3D-T2W sequences using mean slice-wise Hausdorff distance (MSHD) and Dice similarity coefficient (DSC) of the contouring by two operators and using visual assessment. The second group provided 3-day MRI data without a catheter using 3D-T2W, and the third provided 3-day CT data with a catheter to evaluate the interfractional motion using MSHD, DSC, and displacement distance (Dd). The MSHD and DSC for the interoperator variability in urethral identification and visual assessment were superior in 3D-T2W than in 2D-T2W. Regarding interfractional motion, the Dd value for prostatic urethra was smaller in MRI than in CT. These findings indicate that the 3D-T2W yielded adequate prostatic urethral identification, and catheter-free MRI resulted in less interfractional motion, suggesting that 3D-T2W MRI without a catheter is a feasible noninvasive approach to performing prostate SBRT.

DOI： 10.18999/nagjms.85.3.504

Web of Science

Scopus

PubMed

Language：English   Publisher：Anticancer Research  

Background/Aim: A porous glass membrane-pumping emulsification device (GMD) enables the formation of a high-percentage water-in-oil emulsion with homogeneous and stable droplets. Although GMD is expected to improve the locoregional therapeutic effects of transarterial chemoembolization (TACE) in hepatocellular carcinoma (HCC), its effectiveness in the management of solitary HCC remains unclear. Patients and Methods: Patients treated for solitary HCCs (<5 cm) were retrospectively reviewed. A total of 46 patients who could not undergo liver resection and were unsuitable for radiofrequency ablation were included in this study. Among these, 22 patients underwent TACE using a GMD (GMD-TACE group) and 24 underwent stereotactic body radiotherapy (SBRT) using a robotic radiosurgery system (SBRT group). Local control rates were compared between the two groups. Results: The median HCC tumour size was 24 mm (range=12-50 mm) and 22 mm (range=8-39 mm) in the GMD-TACE and SBRT groups, respectively; however, the difference between the groups was not significant. Age, liver function test results, or Child-Pugh scores were not significantly different between the two groups. The rate of local control at 6 months after treatment was 100% in both groups. Although the 1-year local control rate was higher in the SBRT group (92.3%) than in the GMD-TACE group (81.8%), there was no significant difference in the log-rank test (p=0.654). No major treatment-related complications occurred in either group during the observation period. Conclusion: TACE with GMD could be considered an effective treatment option for the management of solitary HCC.

DOI： 10.21873/anticanres.15889

Web of Science

Scopus

PubMed

Language：English  

DOI： 10.7759/cureus.27269

Web of Science

PubMed

Language：English   Publisher：Physica Medica  

Purpose: Gold fiducial markers are used to guide liver stereotactic body radiation therapy (SBRT) and are hard to detect by magnetic resonance imaging (MRI). In this study, the parameters of the three-dimensional T1-weighted turbo gradient-echo (3D T1W-GRE) sequence were optimized for gold marker detection without degrading tumor delineation. Methods: Custom-made phantoms mimicking tumor and normal liver parenchyma were prepared and embedded with a gold marker. The 3D T1W-GRE was scanned by varying echo time (TE), bandwidth (BW), flip angle (FA), and base matrix size. The signal-to-noise ratio (SNR), contrast ratio (CR), and relative standard deviation (RSD) of the signal intensity in the area including the gold marker were evaluated, and the parameters were optimized accordingly. The modified 3D T1W-GRE (called HYBRID) was compared with the conventional T1W-GRE- and T2*-sequences in both phantom and clinical studies. In the clinical study of six patients with primary liver tumors, two observers visually assessed marker detection, tumor delineation, and overall image quality on a four-point scale. Results: In the phantom study, HYBRID showed significantly higher SNR and RSD than those of conventional T1W-GRE (P < 0.001). In the clinical study, HYBRID yielded significantly higher scores than conventional T1W-GRE did in terms of marker detection (P < 0.001). The scores of both sequences were not statistically different in terms of tumor delineation and overall image quality (P = 0.56 and P = 0.32). Conclusions: The proposed HYBRID sequence improved gold fiducial marker detection without degrading tumor delineation in MRI for SBRT of primary liver tumor.

DOI： 10.1016/j.ejmp.2022.01.003

Web of Science

Scopus

PubMed

Language：English   Publisher：Nagoya Journal of Medical Science  

We propose two methods to evaluate system-related distortion in magnetic resonance imaging (MRI)in radiation therapy treatment planning (RTP) and demonstrate the importance of three-dimensional (3D)distortion correction (DC) by quantitatively measuring the distortion magnitude. First, a small pin phantomwas scanned at multiple positions using an external laser guide for accurate phantom placement andcombined into one image encompassing a large area. Direct plane images were used for evaluating in-planedistortion and multiplanar reconstruction images for through-plane distortion with no DC, two-dimensional(2D) DC, and 3D DC. Second, a large grid sheet was scanned as the direct plane of the phantom placement.The distortion magnitude was determined by measuring the displacement between the MRI and referencecoordinates. The measured distortions were compared between in and through-plane when applying DCand between the two methods. The small pin phantom method can be used to evaluate a wide range ofdistortions, whereas data from the entire plane can be obtained with a single scan using the grid sheetwithout a laser guide. The mean distortion magnitudes differed between the methods. Furthermore, the 3DDC reduced in and through-plane distortions. In conclusion, the small pin phantom method can be usedto evaluate a wide range of distortions by creating a combined image, whereas the grid sheet methodis simpler, accurate, repeatable, and does not require a special-order phantom or laser guide. As 3D DCreduces both in and through-plane distortions, it can be used to improve RTP quality

DOI： 10.18999/nagjms.84.1.29

Web of Science

Scopus

PubMed

Event date： 2021.10

Language：Japanese  

Venue：熊本   Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.4

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan