Comparison of MRI visualization between linearly placed iron-containing and non-iron-containing fiducial markers for prostate radiotherapy.

OBJECTIVE: Visualizing the gold marker (GM) in CT and MRI is critical, especially for registration in high-precision radiotherapy. GM sizes vary. Large markers are easily visualized in MRI. Small GMs show fewer artefacts in CT but are harder to detect in MRI because the signal is influenced by metal in MRI. Therefore, we compared MRI visualization between linearly placed new iron-containing marker and non-iron containing marker. METHODS: 27 patients underwent CT/MRI fusion-based intensity-modulated radiotherapy. The gold markers were placed by urologists. An iron-containing Gold Anchor™ (GA) marker (diameter, 0.28 mm; length, 10 mm) was placed by using a 22 G needle on one side of the prostate linearly. A non-iron-containing VISICOIL™ (VIS) marker (diameter, 0.35 mm; length, 10 mm) was placed by using a 19 G needle on the opposite side linearly. T2* weighted MRI was mostly performed. Two Radiation Oncologists and one Radiation Technologist evaluated and assigned visual quality scores (GA shape, CT artefacts, MRI signal voids). RESULTS: The mean visualization scores of artefacts were similar between GA and VIS in planning CT. GM visualization in MRI of the prostate was better for GA than for VIS. The visibility of the linear shape of the GA was 3.4-4.1 points when the VIS was 5 points (1 is worst and 5 is best). CONCLUSION: Visualization quality was similar between GA (iron-containing marker) and VIS (non-iron-containing marker) in planning CT, but was better for GA than for VIS in MRI. To achieve high-precision radiotherapy, an iron-containing gold marker was useful for CT and MRI registration. Advances in knowledge: An iron-containing fiducial marker was useful for CT and MRI registration, especially in high-precision radiotherapy, such as stereotactic body radiotherapy and intensity-modulated radiotherapy.

Visibility of an iron-containing fiducial marker in magnetic resonance imaging for high-precision external beam prostate radiotherapy.

INTRODUCTION: Visualization of fiducial gold markers is critical for registration on computed tomography (CT) and magnetic resonance imaging (MRI) for imaging-guided radiotherapy. Although larger markers provide better visualization on MRI, they tend to generate artifacts on CT. MRI is strongly influenced by the presence of metals, such as iron, in the body. Here we compared efficacies of a 0.5% iron-containing gold marker (GM) and a traditional non-iron-containing marker. METHODS: Twenty-seven patients underwent CT/MRI fusion-based intensity-modulated radiotherapy. Markers were placed by urologists under local anesthesia. Gold Anchor (GA; diameter: 0.28 mm; length: 10 mm), an iron-containing marker, was placed on the right side of the prostate using a 22-G needle and VISICOIL (VIS; diameter: 0.35 mm; length: 10 mm), a non-iron-containing marker, was placed on the left side using a 19-G needle. T2*-weighted images MRI sequences were obtained. Two radiation oncologists and a radiation technologist evaluated and assigned scores for visual quality on a five-point scale (1, poor; 5, best visibility). RESULTS: Artifact generation on CT was slightly greater with GA than with VIS. The mean marker visualization scores on MRI of all three observers were significantly superior for GA than for VIS (3.5 vs 3.2, 3.9 vs 3.2, and 4.0 vs 2.9). The actual size of the spherical GA was about 2 mm in diameter, but the signal void on MRI was approximately 5 mm. CONCLUSION: Although both markers were well visualized and can be recommended clinically, the results suggest that GA has some subtle advantages for quantitative visualization that could prove useful in certain situations of stereotactic body radiotherapy and intensity-modulated radiotherapy.

Comparison of MRI sequences in ideal fiducial maker-based radiotherapy for prostate cancer.

AIM: Prostate contouring using CT alone is difficult. To overcome the uncertainty, CT/MRI registration using a fiducial marker is generally performed. However, visualization of the marker itself can be difficult with MRI. This study aimed to determine the optimal MRI pulse sequence for defining the marker as well as the prostate outline among five sequences. MATERIALS AND METHODS: A total of 21 consecutive patients with prostate cancer were enrolled. Two gold fiducial markers were placed before CT/MRI examination. We used the following five sequences: T1-weighted spin-echo (T1WI; TR/TE, 400-650/8 ms); T2-weighted fast spin-echo (T2WI; 4000/80); T2*-2D-weighted gradient echo (T2*2D; 700/18); T2*-3D-weighted gradient echo (T2*3D; TR/TE1/deltaTE, 37/14/7.3); and contrast-enhanced T1-weighted spin-echo (CE-T1WI; 400-650/8). Qualitative image analysis of the sequences was performed by three observers. These observers subjectively scored all images on a scale of 1-3 (1 = unclear, 2 = moderate, 3 = well visualized). A higher score indicated better visualization. RESULTS: T2WI was significantly superior to the other sequences in terms of prostate definition. T2*2D and T2*3D were strongly superior to the other sequences and were significantly superior in terms of fiducial marker definition. CONCLUSIONS: T2*2D and T2*3D are superior to the other sequences for prostate contouring and marker identification. Therefore, we recommend initial T2*3D and T2*2D examinations.

Efficacy of butylscopolamine in obtaining clear MR image for intensity-modulated radiotherapy for prostate cancer.

PURPOSE: The use of butylscopolamine in magnetic resonance imaging (MRI) of the prostate is controversial in the context of diagnostic imaging where local invasion and the presence of metastases are evaluated. However, in radiation oncology, MRI is performed as part of the simulation process, and the objectives differ to the diagnostic setting. MRI is primarily used for accurate target delineation; hence, the use of an agent to reduce intestinal peristalsis and increase image quality may be beneficial. The impact of butylscopolamine on MRI for radiation oncology purposes has not previously been described. The aim of this study was to evaluate the efficacy of butylscopolamine in MRI acquired for radiation oncology simulation of the prostate. METHODS AND MATERIALS: In total, 67 patients were enrolled in this study. Thirty-five patients received intramuscular injection of butylscopolamine (group A) and 32 patients did not (group B). Visualization of the prostate outline and detection of fiducial gold markers (GMs) in the prostate were evaluated on MRI. Two blinded radiation oncologists (ROs) and one radiation technologist (RT) scored the image quality of the detection of prostate outline and recognition of GMs in the prostate on a scale of 1-5 (1 = poor; 5 = excellent), and the results were evaluated using Mann-Whitney U test and p < 0.05 was considered as statistically significant. RESULTS: On MRI, group A was statistically superior to group B in terms of fiducial marker detection by two ROs (p < 0.01). However, there was no significant difference in RT scoring. Furthermore, on MRI, group A was statistically superior to group B in terms of the detection of the prostate outline by an RT. CONCLUSIONS: Butylscopolamine is effective with respect to detection of the prostate outline and GM recognition (without endorectal coil). The addition of butylscopolamine is simple and cost efficient. We recommend the use of butylscopolamine routinely to obtain good MR images, particularly in the detection of GMs.

Fiducial marker for prostate radiotherapy: comparison of 0.35- and 0.5-mm-diameter computed tomography and magnetic resonance images.

PURPOSE: When performing intensity-modulated radiotherapy for prostate cancer, a marker is inserted into the prostate to enable the recognition of its position using cone-beam computed tomography (CT). However, it is difficult to recognize the prostatic outline using CT alone. Magnetic resonance imaging (MRI) can depict the prostatic outline better than CT. In treatment plans using CT and MRI registration, various markers are used in institutions; however, the selection of an optimal marker size is difficult. Comparison of a different fiducial marker study was conducted using phantom, but no study in vivo was found. Therefore, we prospectively investigated the effects of different marker diameter sizes using CT and MR images. METHODS: Thirty-one consecutive patients were enrolled in this study. CT and MRI were performed 3 weeks after marker placement. The 0.35-mm-diameter marker was placed on the left side of the prostate, and the 0.5-mm-diameter marker was placed on the right side. The length of each marker was 10 mm. The better MRI image was selected between those obtained using T2*-two-dimensional weighted image (T2*2D) and T2*-three-dimensional weighted image (T2*3D). Two observers evaluated and scored the prostatic outline image quality as well as visualized the prostatic markers using CT and MRI. RESULTS: MRI was significantly superior to CT in depicting the prostatic outline. The CT artifacts were significantly lesser for the 0.35-mm-diameter marker than for the 0.5-mm-diameter marker. The degree of marker recognition using MRI was significantly better with the 0.5-mm-diameter marker. CONCLUSION: The 0.5-mm-diameter fiducial marker had significantly better visualization than the 0.35-mm-diameter marker. While CT artifacts were significantly worse with the 0.5-mm-diameter marker, the artifact level was tolerable for clinical practice. Therefore, we recommend the 0.5-mm-diameter diameter marker in terms of prostatic outline and marker visualization using MRI.

Photodynamic therapy combined with intravitreal bevacizumab and sub-tenon triamcinolone acetonide injections for age-related macular degeneration.

PURPOSE: To report the results of triple therapy with photodynamic therapy (PDT) (PDT combined with intravitreal injection of bevacizumab (IVB) and sub-tenon injection of triamcinolone acetonide (STTA)) for the treatment of age-related macular degeneration (AMD) in Japanese patients. METHODS: This retrospective case series included 38 eyes of 38 patients with exudative AMD treated with PDT combined with IVB (1.25 mg) and STTA (40 mg). Retreatment was performed in the same manner with intervals of at least 3 months. All patients had been treatment naïve, with a follow-up period of 12 months. Best-corrected visual acuity (BCVA), macular retinal thickness (MRT) on optical coherence tomography, and the number of treatments were analyzed. RESULTS: The mean logarithm of the minimum angle of resolution BCVA in patients treated with PDT triple therapy was 0.86 ± 0.55 at baseline and 0.62 ± 0.55 at 12 months (p < 0.001). The mean MRT was 554.0 ± 202.6 µm at baseline and 205.1 ± 78.6 µm at 12 months (p < 0.001). During the 1-year follow-up, the average number of PDT triple therapy (treatments per patient) was 1.1. No complications, for example increase in intraocular pressure, cataract, or endophthalmitis, were observed. CONCLUSIONS: In AMD patients, PDT triple therapy significantly improved visual acuity with a minimum number of treatments and a low risk of complications during the 1-year follow-up.

Elevated choroidal blood flow velocity during systemic corticosteroid therapy in Vogt-Koyanagi-Harada disease.

PURPOSE: Laser speckle flowgraphy (LSFG) can be used to non-invasively visualize the haemodynamics of choroidal circulation and the vascular pattern. The purpose of this study was to examine the ability of LSFG to quantitatively evaluate blood flow velocity at the macula in patients with Vogt-Koyanagi-Harada (VKH) disease before and after systemic corticosteroid therapy. METHODS: Prednisolone (200 mg/day) was systemically administered in 10 VKH disease patients with serous retinal detachment at the macular area. The drug was gradually tapered to zero over a 6-month period. Laser speckle flowgraphy measurements were taken in the 20 eyes of these patients at their initial visit and at 1, 4 and 12 weeks after the onset of therapy. Square blur rate (SBR), a quantitative index of relative blood flow velocity, was calculated using LSFG. RESULTS: Serous retinal detachment resolved within 4 weeks after treatment and visual acuities improved to > 1.0 in almost all cases. There were significant increases in average SBR at the macula at 4 weeks after treatment compared with at 1 week after treatment, and also at 12 weeks after treatment compared with at 4 weeks after treatment. CONCLUSIONS: These results suggest that systemic corticosteroid therapy improves inflammation-related impairment in choroidal blood flow velocity at the macula. Laser speckle flowgraphy can evaluate the effect of systemic corticosteroid therapy by enabling comparisons between measurements of blood flow velocity, which is considered to reflect inflammation activity in the choroid.

Positive association of pigment epithelium-derived factor with total antioxidant capacity in the vitreous fluid of patients with proliferative diabetic retinopathy.

BACKGROUND: Pigment epithelium-derived factor (PEDF), a glycoprotein with potent neuronal differentiating activity, was recently found to inhibit advanced glycation end product (AGE)-induced retinal hyperpermeability and angiogenesis through its antioxidative properties, suggesting that it may exert beneficial effects on diabetic retinopathy by acting as an endogenous antioxidant. However, the inter-relationship between PEDF and total antioxidant capacity in the eye remains to be elucidated. AIMS: To determine vitreous PEDF and total antioxidant levels in patients with proliferative diabetic retinopathy (PDR), and to investigate the relationship between them. METHODS: Vitreous levels of PEDF and total antioxidant capacity were measured by an ELISA in 39 eyes of 36 patients with diabetes and PDR and in 29 eyes of 29 controls without diabetes. RESULTS: Vitreous levels of total antioxidant capacity were significantly lower in patients with diabetes and PDR than in controls (mean (SD) 0.16 (0.05) vs 0.24 (0.09) mmol/l, respectively, p<0.001). PEDF levels correlated positively with total antioxidant status in the vitreous of patients with PDR (r = 0.37, p<0.05) and in controls (r = 0.41, p<0.05). Further, vitreous levels of PEDF in patients with PDR without vitreous haemorrhage (VH(-)) were significantly (p<0.05) decreased, compared with those in the controls or in patients with PDR with vitreous haemorrhage (VH(+); PDR VH(-), 4.5 (1.1) microg/ml; control, 7.4 (4.1) microg/ml; PDR VH(+) 8.5 (3.6) microg/ml). CONCLUSION: This study demonstrates that PEDF levels are associated with total antioxidant capacity of vitreous fluid in humans, and suggests that PEDF may act as an endogenous antioxidant in the eye and could play a protective role against PDR.

Stem water transport of Lithocarpus edulis, an evergreen oak with radial-porous wood.

The stem water conducting system of an evergreen broad-leaved oak, Lithocarpus edulis (Mak.) Nakai, was investigated. Evergreen broad-leaved oaks (Lithocarpus, Castanopsis, Cyclobalanopsis, Quercus) belonging to the Quercoideae are a major component of Asian monsoon forests, and are characterized by the possession of radial-porous wood. A characteristic of radial-porous wood is the development of aggregate rays between radially oriented files of vessels. We measured the distribution of vessel lumen diameters in a stem cross section and calculated the theoretical water conductivity of the wood. The radial profile of the heat pulse velocity (HPV) was measured for an intact whole tree under field conditions and compared with the theoretical distribution of water conductivity. Soft X-ray photographs of frozen stem sections indicated that most of the vessel lumina were filled with water, including those of vessels more than 20 years old. Even when vessels were relatively wide (lumen diameters > 100 microm), cavitation was negligible. The rate of water uptake from the cut stem base correlated closely with HPV (r = 0.96), and HPV closely reflected the mean volume flow per stem sectional area (SFVS) around the sensor probes. However, the ray tissue sharply inhibited heat transfer, and the positioning of the probes strongly affected the absolute value of HPV. It was also found that HPV more closely reflected the mean sap flow velocity in the vessels than did SFVS.