Yasuhiro Fukushima

Background and purpose: Sacral chordoma is a rare and locally aggressive malignant bone tumor. Carbon ion radiotherapy (CIRT) has emerged as a promising therapeutic modality, but tumor size may not decrease immediately after treatment, presenting challenges in evaluating treatment response. We aimed to evaluate tumor response after CIRT in sacral chordoma patients using magnetic resonance imaging (MRI) multi-planar measurements and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) quantitative parameters.Materials and methods: A retrospective analysis was conducted on 35 treatment-naïve sacral chordoma patients who underwent CIRT. Baseline follow-up images for up to 60 months post-CIRT were assessed. Dynamic changes in tumor size were measured on three orthogonal dimensions: long-axis diameter (LAD), short-axis diameter (SAD), and cranio-caudal diameter (CCD). We also evaluated quantitative FDG-PET/CT parameters consisting of maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG).Results: A minor reduction in mean tumor size was first observed at six months post-CIRT (LAD: 1.2%; SAD: 3.1%; CCD: 3.4%). From 12 to 60 months post-CIRT, inter-measurement differences between LAD, SAD, and CCD were statistically significant (p < 0.05), with the largest reduction in SAD (32.7%) and the smallest in LAD (11.0%) at 60 months. In a subgroup of 10 patients, who had FDG-PET/CT, average monthly reduction was greater for metabolism than morphology (SUVmax: 2.0% monthly; LAD: 0.6% monthly).Conclusion: Sacral chordoma after CIRT showed an unequal shrinkage pattern. Among MRI-based plane-specific measurements, SAD demonstrated the greatest reduction. FDG-PET/CT may predict or confirm treatment response before morphological changes become apparent.

Purpose: To assess the institutional variability in ultrafast dynamic contrast-enhanced (UF-DCE) breast MRI using time-resolved angiography with stochastic trajectories (TWIST)-volumetric interpolated breath-hold examination (VIBE) and compressed sensing (CS)-VIBE sequences acquired at 2 different institutions with different patient populations and contrast injection protocols.Methods: UF-DCE MR images of 18 patients from site A acquired using a TWIST-VIBE sequence, and UF-DCE MR images of 18 patients from site B acquired with a CS-VIBE sequence, were retrospectively evaluated and compared. The 2-site patient cohort was matched for patient age, background parenchymal enhancement, malignancy or benignity, and lesion size. Qualitative assessments included noise, blurring, poor fat suppression, aliasing artifact, motion artifact, lesion conspicuity, lesion morphology, time-intensity-curve smoothness, and vessel delineation. For quantitative assessment, the bolus arrival time was evaluated for each lesion, and its diagnostic performance in discriminating between benign and malignant lesions was examined using receiver operating characteristics analysis.Results: Thirteen malignant and five benign lesions were included from each site. Qualitative evaluation revealed that poor fat suppression and aliasing artifacts were visible in images from site A with TWIST-VIBE (P = 0.004 and P < 0.001), whereas motion artifacts were present in images from site B with CS-VIBE (P = 0.04). Lesion morphology assessments (P < 0.001) and vessel delineation (P < 0.001) were superior for images from site B with CS-VIBE. Bolus arrival time was significantly longer with TWIST-VIBE than with CS-VIBE, for both benign and malignant lesions (P < 0.001). The area under the receiver operating characteristics curve was 0.55 for site A and 0.69 for site B (P = 0.39).Conclusion: Both acquisitions allowed evaluation of breast lesions with good lesion conspicuity and time-intensity-curve smoothness, whereas CS-VIBE was superior to TWIST-VIBE for morphological evaluation of breast lesions and depiction of blood vessels in the breast. Injection rate appears to have a significant impact on semi-quantitative parameters derived from UF-DCE MRI.

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Purpose To analyze the appropriateness of primary response for anaphylaxis due to iodinated contrast media (ICM) or gadolinium-based contrast agents (GBCA). Materials and methods This retrospective study included all patients in whom intravenous contrast agents (five types of ICMs and four types of GBCAs) were administered at our hospital between April 2016 and September 2021. For the patients who developed anaphylaxis, we obtained data on the time records of contrast injection, anaphylaxis onset, and intramuscular adrenaline (epinephrine) administration. Results Of the 76,555 ICM and 30,731 GBCA administrations, anaphylaxis occurred in 49 cases (0.05%), and in 48 cases (98.0%) the onset was within 30 min after administration with widely distributed times (median, 7.5 min; interquartile range, 4.5–10.8 min; max, 26 min). Intramuscular adrenaline administration was performed in 43 cases (87.8%), and this was done within five minutes after the onset in 37 cases (75.5%). Only in 24 cases (49.0%), there were time records of both the onset and adrenaline administration (if performed). Conclusion Anaphylaxis occurred within 30 min after contrast injection in the majority of the cases, but times were widely distributed. Only in 75.5% of cases, appropriate primary treatment was performed, and the importance of keeping exact time records in patients’ charts should be re-emphasized.

Aim: To evaluate the effectiveness of radiation protection training among medical students using X-ray equipment. Methods: Medical students attended a training class in diagnostic radiology. This training class began with a lecture on radiation protection, followed by experiments to measure the radiation dose. At the beginning and end of the training class, participants answered five-choice questions regarding the three principles of external radiation protection and the dose reduction rate of the lead apron. We also asked participants to provide free-text answers regarding what they learned from the training class and then conducted a text-mining analysis. Results: In the question regarding the three principles of external radiation protection, only 86% of students correctly answered “time” before the training class, but almost all respondents answered the question correctly after the training class. Before the training class, 81% of the students answered that the shielding rate of the lead apron was 95%, but after the training class, almost all students answered correctly that the shielding rate was 80%. Text-mining showed a co-occurrence network consisting of 10 subgraphs from the frequently occurring words. Conclusion: Having the students conduct measurement experiments on their own was effective for improving their understanding of radiation protection.