Dual-energy CT: minimal essentials for radiologists

Dual-energy CT, the object is scanned at two different energies, makes it possible to identify the characteristics of materials that cannot be evaluated on conventional single-energy CT images. This imaging method can be used to perform material decomposition based on differences in the material-attenuation coefficients at different energies. Dual-energy analyses can be classified as image data-based- and raw data-based analysis. The beam-hardening effect is lower with raw data-based analysis, resulting in more accurate dual-energy analysis. On virtual monochromatic images, the iodine contrast increases as the energy level decreases; this improves visualization of contrast-enhanced lesions. Also, the application of material decomposition, such as iodine- and edema images, increases the detectability of lesions due to diseases encountered in daily clinical practice. In this review, the minimal essentials of dual-energy CT scanning are presented and its usefulness in daily clinical practice is discussed.

MRI findings of epithelial–myoepithelial carcinoma of the parotid gland with radiologic–pathologic correlation

Purpose This study aimed to describe the MRI findings of epithelial-myoepithelial carcinoma (EMC) of the parotid gland. Materials and methods Seven patients (four males and three females) aged 40–86 years (mean age, 64 years) with histologically proven EMC of the parotid gland who underwent surgical resection after preoperative MRI were enrolled. MRI images were retrospectively reviewed and contrasted with pathological findings. Results Five patients (71%) had predominantly solid lesions, and two (29%) had predominantly cystic lesions. All seven lesions had well-demarcated margins and capsules without the invasion of adjacent structures. The capsules were incomplete in five lesions (71%) and complete in two (29%). Four lesions (57%) exhibited a multinodular structure with internal septa. Cystic components were observed in three lesions (43%). On T1-weighted images, the solid components were frequently homogeneous (5/7, 71%), and demonstrated isointensity in five lesions (71%) and hypointensity in two (29%) relative to the spinal cord. On T2-weighted images, the solid components were usually heterogeneous (6/7, 86%), and demonstrated hyperintensity in five lesions (71%) and isointensity in two (29%) relative to the spinal cord. The mean apparent diffusion coefficient value of the solid components was 0.967 × 10−3 mm2/s. Conclusion Parotid gland EMCs usually appeared as predominantly solid lesions with well-demarcated margins and capsules. A multinodular structure with internal septa was characteristics of EMCs.

Usefulness of quantitative 99mTc-pyrophosphate SPECT/CT for predicting the prognosis of patients with wild-type transthyretin cardiac amyloidosis

Purpose Wild-type transthyretin-related amyloidosis cardiomyopathy (ATTRwt-CM) is an increasingly recognized cause of heart failure especially in elderly patients. The purpose of the present study was to determine retrospectively whether the quantitative indices of 99mTc-pyrophosphate (PYP) SPECT/CT help to predict the prognosis of ATTRwt-CM patients when compared with other clinical parameters. Materials and methods Sixty-eight patients with biopsy-proven ATTRwt-CM who underwent PYP SPECT/CT were enrolled. Baseline clinical characteristics, echocardiographic parameters, and qualitative and/or quantitative indices of planar and SPECT/CT imaging in PYP scintigraphy for each patient were included. For quantitative analysis of SPECT/CT, the accumulation ratio of PYP in the septum, posterior, anterior, lateral, and apex walls to the cavity pool was calculated as the septal wall-to-cavity ratio (Se/C), lateral wall-to-cavity ratio (La/C), anterior wall-to-cavity ratio (An/C), inferior wall-to-cavity ratio (In/C), and apical wall-to-cavity ratio (Ap/C), respectively. Endpoints for prognostic accuracy evaluation were cardiac death or hospitalization due to heart failure. Event-free survival rate was evaluated through Cox proportional hazards regression analysis, providing estimated hazard ratios (HRs) with 95% confidence intervals (CIs) and Kaplan–Meier curves. Results High-sensitivity cardiac troponin T (hs-cTnT), La/C, age, interventricular septal thickness in diastole, and E/e′ ratio in the septal wall were significantly associated with event-free survival (P < 0.05). For a multivariable Cox proportional hazards analysis, hs-cTnT (HR 1.153; 95% CI 1.034–1.286; P < 0.01), La/C (HR 2.091; 95% CI 1.012–4.322; P = 0.046), and age (HR 1.116; 95% CI 1.007–1.238; P = 0.037) were significant independent prognostic factors. Conclusion This study indicated that the quantitative indices of PYP SPECT/CT can help to predict the prognosis of ATTRwt-CM patients.

Radiotherapy for HPV-related cancers: prediction of therapeutic effects based on the mechanism of tumor immunity and the application of immunoradiotherapy

Human papillomavirus (HPV)-related cancer is one of the diseases entities for which the applications of radiotherapy have been increasing. Recently, the process of carcinogenesis from HPV infection and the mechanism of tumor immunity that develops during disease progression have been elucidated. In this review, we will describe the mechanism of tumor immunity and how chemoradiotherapy may overcome and improve the efficacy of tumor immunity. We will also discuss the usefulness of proteins involved with tumor immunity as a predictive marker of radiotherapy response, and present an overview of ongoing clinical trials of combinations of immune checkpoint inhibitors and radiotherapy to demonstrate the promising combination therapy that has been currently emerging.

Assessment of esophagogastric junction morphology by dynamic real-time MRI: comparison of imaging features to high-resolution manometry

Purpose To assess the esophagogastric junction (EGJ) on real-time MRI and compare imaging parameters to EGJ morphology on high-resolution manometry (HRM). Methods A total of 105 of 117 eligible patients who underwent real-time MRI and high-resolution manometry for GERD-like symptoms between 2015 and 2018 at a single center were retrospectively evaluated (male n = 57; female n = 48; mean age 52.5 ± 15.4 years). Real-time MRI was performed at a median investigation time of 15 min (1 frame/40 ms). On HRM, EGJ morphology was assessed according to the Chicago classification of esophageal motility disorders. Real-time MRI was performed at 3 T using highly undersampled radial fast low-angle shot acquisitions with NLINV image reconstruction. A 10 mL pineapple juice bolus served as oral contrast agent at supine position. Real-time MRI films of the EGJ were acquired during swallowing events and during Valsalva maneuver. Anatomic and functional MRI parameters were compared to EGJ morphology on HRM. Results On HRM, n = 42 patients presented with EGJ type I (40.0%), n = 33 with EGJ type II (31.4%), and n = 30 with EGJ type III (28.6%). On real-time MRI, hiatal hernia was more common in patients with EGJ type III (66.7%) than in patients with EGJ type I (26.2%) and EGJ type II (30.3%; p < 0.001). Sliding hiatal hernia was more frequent in patients with EGJ type II (33.3%) than in patients with EGJ type III (16.7%) and EGJ type I (7.1%; p = 0.017). The mean esophagus–fundus angle of patients was 85 ± 31° at rest and increased to 101 ± 36° during Valsalva maneuver. Conclusion Real-time MRI is a non-invasive imaging method for assessment of the esophagogastric junction. Real-time MRI can visualize dynamic changes of the EGJ during swallowing events.

High tumor mutational burden predicts worse prognosis for cervical cancer treated with radiotherapy

Purpose Tumor mutational burden (TMB) is a surrogate biomarker of neo-antigens and high TMB status is associated with favorable response to immune-checkpoint inhibitors (ICIs). This study aimed to elucidate the association between TMB and the outcome of definitive radiotherapy in patients with cervical cancer. Materials and methods TMB and treatment outcome were retrospectively analyzed in patients with newly diagnosed cervical cancer treated with definitive radiotherapy available with somatic mutation data of pre-treatment tumors obtained using a commercially available gene panel. Results The study enrolled 98 patients (median follow-up period, 61 months). The median TMB was 9.5 mutations per megabase (range, 3.0–35.5 mutations per megabase). After dichotomization based on this median value, the 5-year overall survival (OS) for TMB-high patients was significantly worse than that of TMB-low patients (61.1% vs. 82.2%). Multivariate analysis identified high TMB status as a significant prognostic factor for worse OS, along with advanced stage, para-aortic lymph node involvement, and absence of concurrent chemotherapy. Conclusion These data indicate that TMB is a potential prognostic factor for worse survival in patients with cervical cancer treated with definitive radiotherapy, thereby providing a rationale for treatment of TMB-high cervical cancers with a combination of ICIs plus radiotherapy. Secondary abstract This retrospective study of 98 patients demonstrates for the first time that tumor mutational burden (TMB) is an independent prognostic factor for worse overall survival of patients treated with definitive radiotherapy, providing a rationale for treatment of TMB-high cervical cancers with a combination of immune-checkpoint inhibitors plus radiotherapy.

Clinical results of image-guided interstitial brachytherapy with or without external beam radiotherapy for postsurgical vaginal recurrence of cervical and endometrial cancers

Purpose This study aimed to evaluate the clinical outcome and efficacy of image-guided interstitial brachytherapy (ISBT) for postsurgical vaginal recurrence of cervical and endometrial cancers. Materials and methods The study included 11 patients who received CT-based image-guided high-dose-rate ISBT with or without external beam radiotherapy (EBRT). Local control, progression-free survival, and treatment-related toxicities were evaluated retrospectively. Results Of the 11 patients, 4 underwent ISBT with EBRT and the other 7 ISBT alone; two of the latter patients received previous pelvic radiotherapy. After a median follow-up of 43.9 months (range 3.9–92.7 months), the 2-year local control rate was 100%. The median equivalent doses in 2 Gy fractions received by at least 90% of the clinical target volume for ISBT with versus without EBRT were 82.2 Gy (range 60.4–84.2 Gy) versus 69.0 Gy (range 50.8–98.2 Gy). The 2-year progression-free survival rates after ISBT with versus without EBRT were 75% versus 80%, and the difference was not significant (p = 0.74). Grade 3 late toxicities occurred in two patients. Conclusion Our radiotherapy strategy using image-guided ISBT, either with or without EBRT, for postsurgical vaginal recurrence showed effective treatment outcomes.