MR and CT anatomy and the pathology of skull base focusing on pterygopalatine fossa

EUROPEAN CONGRESS OF RADIOLOGY 201

Quantitative analysis of circulatory function for prostate tumors using reference tissue model in DCE-MRI studies

In dynamic contrast-enhanced MRI (DCE-MRI) studies, a time-concentration curve of injected contrast agent is obtained from dynamically acquired T1-weighted images, and circulatory function around tumors is evaluated quantitatively by compartmental analysis with an arterial input function (AIF). However, it is difficult to obtain AIF individually, and AIF errors deteriorate the reliability of quantitative outcomes. In this study, we developed a quantitative analysis method using reference tissue, and applied it to DCE-MRI of prostate tumors. The reference tissue model, providing the ratio of transfer rate constants between the target and reference regions without AIF, was derived from a conventional one-tissue compartment model. In the DCE-MRI images of patients with prostate tumors, the model parameters in normal parts (transitional zone and peripheral zone) and tumor parts were estimated by the reference tissue model using the gluteus muscle as reference region. The differences between normal and tumor parts were evaluated using paired t-test with 0.05 as significance level, and were compared with those by the conventional method with AIF. The reference tissue model showed higher efflux rate constants in the tumors compared with normal parts, and the ability to discriminate between normal and tumor parts was better than that of the conventional method. The proposed method can provide reliable parameters related to circulatory function by a simple analysis, and it should be useful for the diagnosis of prostate tumors.第44回日本磁気共鳴医学会大

Prognostic Value of ADC: Malignant Astrocytic Tumors after Carbon Ion Radiotherapy

PURPOSE: Carbon ion radiotherapy often induces radiation brain injury in various degrees and differentiation of recurrent tumor from radiation injury on follow-up MR images is problematic. Recently it has been reported that assessment of apparent diffusion coefficients (ADCs) of enhancing regions was useful in differentiation between recurrent glioma and radiation injury. The purpose of this study is to assess the relationship between ADC value and prognosis of patients with malignant astrocytic tumors after carbon ion radiotherapy retrospectively and to evaluate the prognostic value of ADCMETHOD AND MATERIALS: Twenty-five patients who underwent diffusion weighted imaging (DWI) in follow-up MR examination after carbon ion radiotherapy for malignant astrocytic tumors were enrolled in this study. We evaluated the most recent MR examination in our institution. MR imaging was performed using a 1.5T MRI unit with a head coil. DWI in the axial direction was obtained by using a STIR-EPI sequence with b-values of 0 and 1,000 sec/mm2, acquired in three orthogonal directions. Region of interest (ROIs) were drawn manually onto the obtained ADC maps in the region corresponding to the enhancing area on contrast-enhanced T1-weighted images. Statistical analysis was performed with SPSS. Mean ADC values between fatality group and survival group were compared using Mann-Whitney U test.RESULTS: One survival patient in whom local recurrence could not be denied because of short follow-up period was excluded from this study. Fatality group included 16 cases and survival group included eight cases. Fatality group included three patients who died from other cause than recurrence. All surviving patients were followed up for more than 3 years and their intracranial lesions were thought to be brain injury. Mean ADC value of fatality group (1.13+0.15[x10-3mm2/sec]) was significantly smaller than those of survival group (1.50+0.26) (p<0.01) . When we used a cutoff value of 1.3 for suspecting prognosis on mean ADC values (i.e., patient with ADC<1.3 would die from recurrence), positive predictive value was 86.7% and negative predictive value was 88.9%.CONCLUSION: For malignant astrocytic tumors after carbon-ion radiotherapy, cases with intracranial lesions of ADC value smaller than 1.3 are suspected to have poor prognosis.96th Scientific Assembly and Annual Meetin

A clinical study of curative partial breast irradiation for stage I breast cancer using carbon ion radiotherapy

Background and purpose: Our institute initiated carbon ion radiotherapy research for patients with stage I breast cancer in April 2013. The purpose of this article is to evaluate the treatment outcome of cases treated outside clinical trial up to May 2020. Materials and methods: Eligibility criteria of the patients were having untreated stage I breast cancer and being unsuitable for operation for physical or mental reasons. The irradiated volume was defined as the gross tumor including intraductal components. The dose escalation study was initially conducted four times a week for a total of 52.8 Gy [relative biological efficacy (RBE)]. After confirming that adverse effects were within acceptable range, the total dose was increased to 60.0 Gy (RBE). Results: Between April 2013 and November 2015, 14 cases were treated. The median follow up period was 61 months. No adverse toxicities were observed except for grade 1 acute skin reaction in 10 cases. The time required from carbonion radiotherapy to tumor disappearance was 3 months in 1 case, 6 months in 3 cases, 12 months in 4 cases, and 24 months in 5 cases. The third case developed local recurrence 6 months after radiotherapy. Twelve patients with luminal subtype received 5-year endocrine therapy. Thirteen of 14 tumors have been maintaining complete response with excellent cosmetic results. Conclusions: The time from carbon ion radiotherapy to tumor disappearance was longer than expected, but complete tumor disappearance was observed except for one high-grade case. With careful patient selection, carbonion radiotherapy in patients with stage I breast cancer is deemed effective and safe, and further research is recommended

Imaging characteristics of metastatic chordoma.

PURPOSE: Our aim was to describe the incidence and sites of metastatic chordomas and show their characteristic computed tomography (CT) and magnetic resonance (MR) findings.\nMATERIALS AND METHODS: One hundred ninety-eight chordoma patients were registered in the institutional database and were followed up with CT and MR examinations for periods ranging from 1 to 158 months. Clinical features and CT and MR findings of metastatic chordomas were analyzed by two radiologists.\nRESULTS: We counted 86 metastatic sites in 49 of 198 patients. The incidence of metastasis was 24.7 %. Sites of metastases were bone, lung, liver, lymph node, muscle, skin, pleura, cerebellum, cardiac muscle, pericardium, and adrenal gland. Duration from the diagnosis to the first detection of metastasis ranged from 0 to 600 months, with an average of 45.0 months. Osteolytic lesions were most common bone metastases, but osteosclerotic metastasis was also encountered. Metastatic chordoma showed very high intensity on diffusion-weighted (DW) images in 29 of 31 patients.\nCONCLUSION: Metastases of chordoma are not rare and may occur several years after primary lesion presentation. The high intensity of DW images is characteristic and helpful for detecting metastatic chordoma

First experience of carbon-ion radiotherapy for early breast cancer.

Breast cancer is increasingly being detected at earlier stages, and partial breast irradiation for patients with low-risk-group tumor has come to be applied in the US and Europe as an alternative to whole-breast irradiation. Based on those experiences, some institutes have tried using particle beams for partial breast irradiation for postoperative or radical intent for early breast cancer, but technical difficulties have hindered its progress. The National Institute of Radiological Sciences has been preparing for carbon-ion radiotherapy (C-ion RT) with radical intent for stage I breast cancer since 2011, and we carried out the first treatment in April 2013. In this case report, we explain our first experience of C-ion RT as a treatment procedure for breast tumor and present the radiation techniques and preliminary treatment results as a reference for other institutes trying to perform the same kind of treatment