Masae Torii

UCHL1 provides diagnostic and antimetastatic strategies due to its deubiquitinating effect on HIF-1α

Hypoxia-inducible factor 1 (HIF-1) plays a role in tumour metastases; however, the genes that activate HIF-1 and subsequently promote metastases have yet to be identified. Here we show that Ubiquitin C-terminal hydrolase-L1 (UCHL1) abrogates the von Hippel–Lindau-mediated ubiquitination of HIF-1α, the regulatory subunit of HIF-1, and consequently promotes metastasis. The aberrant overexpression of UCHL1 facilitates distant tumour metastases in a HIF-1-dependent manner in murine models of pulmonary metastasis. Meanwhile, blockade of the UCHL1–HIF-1 axis suppresses the formation of metastatic tumours. The expression levels of UCHL1 correlate with those of HIF-1α and are strongly associated with the poor prognosis of breast and lung cancer patients. These results indicate that UCHL1 promotes metastases as a deubiquitinating enzyme for HIF-1α, which justifies exploiting it as a prognostic marker and therapeutic target of cancers.

Visualization of tumor-related blood vessels in human breast by photoacoustic imaging system with a hemispherical detector array

Noninvasive measurement of the distribution and oxygenation state of hemoglobin (Hb) inside the tissue is strongly required to analyze the tumor-associated vasculatures. We developed a photoacoustic imaging (PAI) system with a hemispherical-shaped detector array (HDA). Here, we show that PAI system with HDA revealed finer vasculature, more detailed blood-vessel branching structures, and more detailed morphological vessel characteristics compared with MRI by the use of breast shape deformation of MRI to PAI and their fused image. Morphologically abnormal peritumoral blood vessel features, including centripetal photoacoustic signals and disruption or narrowing of vessel signals, were observed and intratumoral signals were detected by PAI in breast cancer tissues as a result of the clinical study of 22 malignant cases. Interestingly, it was also possible to analyze anticancer treatment-driven changes in vascular morphological features and function, such as improvement of intratumoral blood perfusion and relevant changes in intravascular hemoglobin saturation of oxygen. This clinical study indicated that PAI appears to be a promising tool for noninvasive analysis of human blood vessels and may contribute to improve cancer diagnosis.

Clinical Report on the First Prototype of a Photoacoustic Tomography System with Dual Illumination for Breast Cancer Imaging.

Photoacoustic tomography is a recently developed imaging modality that can provide high spatial-resolution images of hemoglobin distribution in tissues such as the breast. Because breast cancer is an angiogenesis-dependent type of malignancy, we evaluated the clinical acceptability of breast tissue images produced using our first prototype photoacoustic mammography (PAM) system in patients with known cancer. Post-excisionally, histological sections of the tumors were stained immunohistochemically (IHC) for CD31 (an endothelial marker) and carbonic anhydrase IX (CAIX) (a marker of hypoxia). Whole-slide scanning and image analyses were used to evaluate the tumor microvessel distribution pattern and to calculate the total vascular perimeter (TVP)/area for each lesion. In this clinical study, 42 lesions were primarily scanned using PAM preoperatively, three of which were reported to be benign and were excluded from statistical analysis. Images were produced for 29 out of 39 cancers (visibility rate = 74.4%) at the median depth of 26.5 (3.25–51.2) mm. Age, menopausal status, body mass index, history of neoadjuvant treatment, clinical stage and histological tumor angiogenesis markers did not seem to affect the visibility. The oxygen saturation level in all of the measured lesions was lower than in the subcutaneous counterpart vessels (Wilcoxon test, p value<0.001), as well as in the counterpart contralateral normal breast region of interest (ROI) (Wilcoxon test, p value = 0.001). Although the oxygen saturation level was not statistically significant between CAIX-positive vs. -negative cases, lesional TVP/area showed a positive correlation with the oxygen saturation level only in the group that had received therapy before PAM. In conclusion, the vascular and oxygenation data obtained by PAM have great potential for identifying functional features of breast tumors.

Photoacoustic mammography capable of simultaneously acquiring photoacoustic and ultrasound images

Abstract. We have constructed a prototype photoacoustic mammography system (PAM-02) capable of simultaneously acquiring photoacoustic (PA) and ultrasound (US) images. Each PA, US, and fused PA/US image can be acquired over a wide area of the breast using the scanning module of a US transducer, a PA detector, and optical prisms. The resolution of the PA images exhibits improvement from 2 to 1 mm compared to images acquired using our previous prototype. The maximum scan area of PAM-02 is 90 mm along the horizontal axis and 150 mm along the vertical axis. In a phantom experiment, the available depth was at least 45 mm. A representative example of the application of the PAM-02 prototype in clinical research at Kyoto University is presented and shows S-factor images, which are considered an approximation parameter related to hemoglobin saturation of tumor-related blood vessels. We confirmed the applicability of the system for anatomical and biological research.

Abstract P1-02-01: Evaluation of second-generation photoacoustic mammography in detecting the breast cancer vasculature and hypoxic status; a preliminary study

Background: Functional imaging of tumor vasculature and oxygenation status is essential for monitoring the therapeutic response to the manipulation of abnormal vasculature. Moreover, it could be also applicable for the detection and risk assessment of breast lesion with borderline malignancy since hypoxia and angiogenesis is known to be associated with the malignant potential of precursor lesion of solid tumor. Photoacoustic mammography (PAM) is a novel optical imaging technology that can visualize the hemoglobin distribution and its oxygen saturation (SO2) noninvasively. We have previously reported a promising clinical result of a prototype model of PAM (Canon Inc., Tokyo, Japan) in breast cancer patients. However, the improvement of spatial resolution and the identification of signal origin are still big challenges when considering its application for clinical settings. Materials and methods: We developed the second-generation model of PAM (PAM-02). This instrument has achieved the improved spatial resolution (1.3mm) and enhanced detectability by carrying a high-sensitive detector. Moreover, it is equipped with B-mode ultrasound, which enables us to identify the tumor location in PAM images more precisely. The distribution of hemoglobin within breast tissue carrying solid tumor was evaluated by using PAM-02 under the approval of the ethics committee in Kyoto University Hospital, Japan. Contralateral breast without tumor was also evaluated as a control if possible. Calculated SO2 from photoacoustic (PA) signals were illustrated by using color scale. Results: Seventeen breast lesions from 15 patients were analyzed including 4 ductal carcinoma in situ (DCIS), 12 invasive ductal carcinoma (IDC) and one usual ductal hyperplasia. Tumor locations were successfully identified in 14 out of 17 lesions (82.3%) by B-mode ultrasound imaging. The location of 3 lesions undetectable by B-mode ultrasound imaging could be identified by comparing with corresponding MRI images. B-mode ultrasound imaging made it easy to distinguish intra-tumoral PA signals from peri-tumoral PA signals. Intra-tumoral PA signals were detectable in 68.7% of malignant lesions (11 out of 16 lesions). Peri-tumoral PA signals, which were suggested to be from feeding vessels, were detectable in 81.3% of malignant lesion (13 out of 16 lesions). In the case of benign UDH, PA signals were not detected in either intra- or peri-tumoral region. Intra-tumoral SO2 was estimated to be lower than peri-tumoral SO2 in malignant lesion. While peri-tumoral PA signals were often described as continuous vasculature, intra-tumoral PA signals often showed the spotty patterns. In addition, PA signal density was relatively higher in DCIS compared with IDC. These findings was supposed to reflect the decreased hemoglobin perfusion within solid structure of breast cancer. The minimum detectable lesion was DCIS with a diameter of 8mm. Conclusion: Improved spatial resolution and combination with B-mode ultrasound imaging facilitate the region-specific evaluation of PAM imaging. PAM-02 was supposed to be feasible for evaluating the hypoxic status within small breast tumor and its microenvironment. Citation Format: Masahiro Kawashima, Iku Yamaga, Masae Torii, Mariko Tokiwa, Fakhrejahani Elham, Masako Kataoka, Shotaro Kanao, Masahiro Takada, Yasufumi Asao, Tsuyoshi Shiina, Masakazu Toi. Evaluation of second-generation photoacoustic mammography in detecting the breast cancer vasculature and hypoxic status; a preliminary study [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-02-01.

Analysis of the microvascular morphology and hemodynamics of breast cancer in mice using SPring-8 synchrotron radiation microangiography

Synchrotron-radiation-based microvascular hemodynamic analysis was established in this study. Tumor vasculature analysis using this method showed unique characteristics of tumor blood flow in vivo.

Vascular branching point counts using photoacoustic imaging in the superficial layer of the breast: A potential biomarker for breast cancer

This study aimed to identify the characteristics of the vascular network in the superficial subcutaneous layer of the breast and to analyze differences between breasts with cancer and contralateral unaffected breasts using vessel branching points (VBPs) detected by three-dimensional photoacoustic imaging with a hemispherical detector array. In 22 patients with unilateral breast cancer, the average VBP counts to a depth of 7 mm below the skin surface were significantly greater in breasts with cancer than in the contralateral unaffected breasts (p < 0.01). The ratio of the VBP count in the breasts with cancer to that in the contralateral breasts was significantly increased in patients with a high histologic grade (p = 0.03), those with estrogen receptor-negative disease (p < 0.01), and those with highly proliferative disease (p < 0.01). These preliminary findings indicate that a higher number of VBPs in the superficial subcutaneous layer of the breast might be a biomarker for primary breast cancer.

Real-time navigation system for sentinel lymph node biopsy in breast cancer patients using projection mapping with indocyanine green fluorescence

BackgroundInability to visualize indocyanine green fluorescence images in the surgical field limits the application of current near-infrared fluorescence imaging (NIR) systems for real-time navigation during sentinel lymph node (SLN) biopsy in breast cancer patients. The aim of this study was to evaluate the usefulness of the Medical Imaging Projection System (MIPS), which uses active projection mapping, for SLN biopsy.MethodsA total of 56 patients (59 procedures) underwent SLN biopsy using the MIPS between March 2016 and November 2017. After SLN biopsy using the MIPS, residual SLNs were removed using a conventional NIR camera and/or radioisotope method. The primary endpoint of this study was identification rate of SLNs using the MIPS.ResultsIn all procedures, at least one SLN was detected by the MIPS, giving an SLN identification rate of 100% [95% confidence interval (CI) 94–100%]. SLN biopsy was successfully performed without operating lights in all procedures. In total, 3 positive SLNs were excised using MIPS, but were not included in the additional SLNs excised by other methods. The median number of SLNs excised using the MIPS was 3 (range 1–7). Of procedures performed after preoperative systemic therapy, the median number of SLNs excised using the MIPS was 3 (range 2–6).ConclusionsThe MIPS is effective in detecting SLNs in patients with breast cancer, providing continuous and accurate projection of fluorescence signals in the surgical field, without need for operating lights, and could be useful in real-time navigation surgery for SLN biopsy.

Abstract P4-01-10: Development of photoacoustic vascular imaging system for breast cancer

Background: Tumor angiogenesis and hypoxia are associated with breast cancer growth and metastasis. Photoacoustic (PA) tomography is an optical imaging technology that visualizes distribution and oxygenation status of hemoglobin with high spatial resolution. Initially we developed a photoacoustic mammography (PAM) having a flat-shaped scanning detector that could detect breast tumors. Nevertheless, the flat-shaped detector array has the drawback of a limited view. Here we developed a novel PAM system with a hemispherical-shaped detector array (HDA), which enables us to identify microvasculatures non-invasively and allow the collection of nearly spatially isotropic three-dimensional reconstructed image of blood vessels. This non-invasive vascular imaging system may be able to characterize tumor angiogenesis and analyze the status of microcirculation. The aim of this study was to analyze the imaging findings of tumor-related vasculature in breast cancer patients. Patients and method: A PAM system with HDA has been generated in a cooperation project between Canon Inc., Japan, and Kyoto University. Twenty-two primary breast cancer patients, including 5 patients with non-invasive cancer and 17 patients with invasive cancer, diagnosed between December 2014 and December 2015 underwent the PAM imaging analysis. We also applied the breast deformation algorithm from the breast shape in a MRI image to that in a PA image in order to create a fusion image of the two modalities for the analysis. Features of peri- and intra-tumoral vasculature, and their oxygenation status were evaluated. The study protocol was approved by the institutional review board at Kyoto University Hospital (UMIN000012251). All patients provided informed consent to participate in this study. Results: The abnormal peri-tumoral vasculature was detected in 86% of all non-invasive and invasive disease cases. In invasive cancer cases, most tumor-related blood vessels were centripetally directed toward the tumor, and 93% of centripetal blood vessels appeared to be disrupted or rapidly narrowed at the tumor boundary. The centripetal blood vessel structure was frequently observed in invasive cancer compared with non-invasive cancer (61% vs 35%). PA images before and after preoperative chemotherapy were obtained in one case, where intra-tumoral blood vessels became finer after chemotherapy, reflecting normalization of intra-tumoral microcirculation induced by chemotherapy. Conclusions: A PAM system with HDA has provided a high-resolution vascular images of primary breast cancers. The morphological differences of peri-tumoral vasculature were observed between invasive disease and non-invasive disease. These results suggest the potential of PA imaging as a non-invasive tool to analyze tumor vasculature of human breast cancers and maybe be helpful for breast cancer diagnosis. (Acknowledgements) This work was partially supported by the Innovative Techno-Hub for Integrated Medical Bio-imaging Project of the Special Coordination Funds for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. Citation Format: Toi M, Asao Y, Takada M, Kataoka M, Endo T, Kawashima M, Yamaga I, Nakayama Y, Tokiwa M, Fakhrejahani E, Torii M, Kawaguchi-Sakita N, Kanao S, Matsumoto Y, Yagi T, Sakurai T, Togashi K, Shiina T. Development of photoacoustic vascular imaging system for breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-01-10.

Abstract P4-03-03: Detection of the tumor vasculature and the hypoxic status of breast lesions using second-generation photoacoustic mammography: An exploratory study

Background: Tumor angiogenesis and hypoxia are associated with breast cancer growth and metastasis. Photoacoustic mammography (PAM) non-invasively visualizes hemoglobin distribution inside the breast by detecting thermoelastic waves from hemoglobin generated by the irradiation of a near-infrared laser pulse. Oxygen saturation (SO2) can be calculated using photoacoustic (PA) signals obtained by two laser pulses of different wavelengths. We further improved the spatial resolution of PAM by approximately 1 mm and enhanced detectability by using a high-sensitivity detector. This new PAM technique can obtain both PAM images and ultrasonography (US) images simultaneously. The aim of this study was to explore the clinical usefulness of this PAM technique. Patients and methods: Women who had breast lesions were eligible for this study. The participants9 lesions were measured using the new PAM technique before they began treatment. The PAM images were evaluated by 5 physicians. First, the lesions were identified using only the PAM images. Second, we used US or contrast-enhanced magnetic resonance images (CE-MRI) to identify the locations of the lesions. Next, we evaluated the photoacoustic (PA) signals based on their locations. Peri-tumoral PA signals were defined as linear signals that congregated in the peri-tumoral area, boundary PA signals were defined as peri-tumoral signals that were disrupted at the lesion9s boundaries, and intra-tumoral PA signals were defined as any significant PA signals inside the tumor. SO2 was illustrated using a color scale. The study protocol was approved by the institutional review board at Kyoto University Hospital, Japan (UMIN000007464). Results: PAM was performed on 48 breast lesions in 45 patients, including 36 invasive carcinoma lesions, 8 ductal carcinoma in situ (DCIS) lesions, and 4 benign lesions. Evaluations of PA signals according to the locations of the lesion, with confirmation from US or CE-MRI, were successfully performed for 38 lesions. Peri-tumoral PA signals were detected in 33 lesions (87%), disrupted boundary PA signals were detected in 30 lesions (79%), and intra-tumoral PA signals were detected in 25 lesions (66%). The detection rates for peri-tumoral, boundary and intra-tumoral PA signals were 94%, 87%, and 65% for invasive carcinoma, and 60%, 40%, and 80% for DCIS, respectively. Intra-tumoral PA signals tended to be weaker than peri-tumoral PA signals in invasive carcinoma lesions, and they often displayed a spotty rather than a linear shape. Intra-tumoral PA signals were observed to have lower SO2 levels than peri-tumoral PA signals in 95% of invasive carcinoma lesions and in 75% of DCIS lesions. Although peri-tumoral and boundary PA signals were also detected in a 38-mm fibroadenoma, the intra-tumoral PA signals displayed a diffuse pattern. Conclusions: We demonstrated that high spatial resolution and use in combination with US and CE-MRI facilitate the region-specific evaluation of PAM imaging. PAM could become a useful tool for the evaluation of the hypoxic status of tumors by enhancing its sensitivity. Citation Format: Takada M, Kawashima M, Kataoka M, Kanao S, Yamaga I, Torii M, Tokiwa M, Fakhrejahani E, Sakurai T, Asao Y, Haga H, Shiina T, Togashi K, Toi M. Detection of the tumor vasculature and the hypoxic status of breast lesions using second-generation photoacoustic mammography: An exploratory study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-03-03.