外山 宏

Background 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is a pivotal tool for diagnosing cardiac sarcoidosis, but its prognostic value during the phase of stable medical and device therapy after initiation of immunosuppressive therapy remains unclear. We aimed to evaluate the prognostic significance of cardiac FDG uptake in patients with cardiac sarcoidosis after treatment initiation. Methods We retrospectively analyzed 79 patients who underwent FDG-PET/CT ≥ 12 months after initiating immunosuppressive therapy (June 2013–October 2023). Patients were categorized into the cardiac accumulation (+) and (-), and Cardiac metabolic activity (CMA) was also quantitatively measured. Major adverse cardiac events—including cardiac death, ventricular arrhythmias, ICD therapy, and heart failure hospitalization—were evaluated. Results Patients in the cardiac accumulation (+) had a higher 2-year incidence of major adverse cardiac events than those in the cardiac accumulation (-), as determined by Kaplan–Meier analysis (log-rank P = 0.030), but FDG uptake was not identified as a predictor in Cox regression analysis. In long-term outcomes, the incidence of cardiac events tended to be higher in the cardiac accumulation (+) group, although this difference did not reach statistical significance (log-rank P = 0.078). Among patients with preserved left ventricular ejection fraction (LVEF ≥50%, independently associated with fewer events), annual cardiac event rates were similarly low regardless of uptake status (1.3% vs. 0.8%; log-rank P = 0.91). In 41 patients who underwent repeat PET imaging, CMA significantly decreased (median 4.83 to 0.82, P = 0.038). Among 23 patients without intensified immunosuppression despite uptake, it resolved spontaneously in 8 patients. Conclusions Follow-up cardiac FDG uptake may be associated with an increased risk of short-term events but has limited value for predicting long-term prognosis. LVEF and the temporal dynamics of FDG uptake should be considered when managing cardiac sarcoidosis.

BACKGROUND: Diffusion-weighted images (DWI) obtained by echo-planar imaging (EPI) are frequently degraded by susceptibility artifacts. It has been suggested that DWI obtained by fast advanced spin-echo (FASE) or reconstructed with deep learning reconstruction (DLR) could be useful for image quality improvements. The purpose of this investigation using in vitro and in vivo studies was to determine the influence of sequence difference and of DLR for DWI on image quality, apparent diffusion coefficient (ADC) evaluation, and differentiation of malignant from benign head and neck tumors. METHODS: For the in vitro study, a DWI phantom was scanned by FASE and EPI sequences and reconstructed with and without DLR. Each ADC within the phantom for each DWI was then assessed and correlated for each measured ADC and standard value by Spearman's rank correlation analysis. For the in vivo study, DWIs obtained by EPI and FASE sequences were also obtained for head and neck tumor patients. Signal-to-noise ratio (SNR) and ADC were then determined based on ROI measurements, while SNR of tumors and ADC were compared between all DWI data sets by means of Tukey's Honest Significant Difference test. RESULTS: For the in vitro study, all correlations between measured ADC and standard reference were significant and excellent (0.92 ≤ ρ ≤ 0.99, p < 0.0001). For the in vivo study, the SNR of FASE with DLR was significantly higher than that of FASE without DLR (p = 0.02), while ADC values for benign and malignant tumors showed significant differences between each sequence with and without DLR (p < 0.05). CONCLUSION: In comparison with EPI sequence, FASE sequence and DLR can improve image quality and distortion of DWIs without significantly influencing ADC measurements or differentiation capability of malignant from benign head and neck tumors.

PURPOSE: The purpose of this study was to determine the utility of compressed sensing (CS) with deep learning reconstruction (DLR) for improving spatial resolution, image quality and focal liver lesion detection on high-resolution contrast-enhanced T1-weighted imaging (HR-CE-T1WI) obtained by CS with DLR as compared with conventional CE-T1WI with parallel imaging (PI). METHODS: Seventy-seven participants with focal liver lesions underwent conventional CE-T1WI with PI and HR-CE-T1WI, surgical resection, transarterial chemoembolization, and radiofrequency ablation, followed by histopathological or >2-year follow-up examinations in our hospital. Signal-to-noise ratios (SNRs) of liver, spleen and kidney were calculated for each patient, after which each SNR was compared by means of paired t-test. To compare focal lesion detection capabilities of the two methods, a 5-point visual scoring system was adopted for a per lesion basis analysis. Jackknife free-response receiver operating characteristic (JAFROC) analysis was then performed, while sensitivity and false positive rates (/data set) for consensus assessment of the two methods were also compared by using McNemar's test or the signed rank test. RESULTS: Each SNR of HR-CE-T1WI was significantly higher than that of conventional CE-T1WI with PI (p < 0.05). Sensitivities for consensus assessment showed that HR-CE-MRI had significantly higher sensitivity than conventional CE-T1WI with PI (p = 0.004). Moreover, there were significantly fewer FP/cases for HR-CE-T1WI than for conventional CE-T1WI with PI (p = 0.04). CONCLUSION: CS with DLR are useful for improving spatial resolution, image quality and focal liver lesion detection capability of Gd-EOB-DTPA enhanced 3D T1WI without any need for longer breath-holding time.