Reduction of toxicity in brachytherapy using a new technique

PurposeThe purpose of the study was to elucidate the usefulness of a dose evaluation method for reducing late genitourinary (GU) toxicity in high-dose-rate brachytherapy (HDR-BT) of prostate cancer.Methods and MaterialsGU toxicity was scored in accordance with the Common Terminology Criteria for Adverse Events version 4.0. The prostatic urethra was divided into three segments (base = B, midgland = M, apex = A), which were subclassified into seven subgroups (B, M, A, BM, BA, MA, BMA) using a D_10% color map of the urethra. Significance testing was conducted on urethral D_0.1% and D_10% among the seven subgroups. Grade < 2 GU toxicity was also implemented.ResultsData of 174 patients with localized prostate cancer treated with HDR-BT combined with external beam radiotherapy between November 2011 and July 2014 were analyzed retrospectively. Median age was 74 (53–84) years, and median followup period was 44 (6–69) months. The number of Grade < 2 and Grade ≥ 2 toxicity was significantly different in the M subgroup than in the other subgroups (p < 0.05), suggesting increased radioresistance in the midgland urethra.ConclusionsA high-dose-area evaluation method using a urethral D_10% color map may be helpful in reducing late GU toxicity in HDR-BT for prostate cancer.     

Optimized scan delay for late hepatic arterial or pancreatic parenchymal phase in dynamic contrast-enhanced computed tomography with bolus-tracking method

Objectives:To determine the optimal scan delay corresponding to individual hemodynamic status for pancreatic parenchymal phase in dynamic contrast-enhanced CT of the abdomen.Methods:One hundred and fourteen patients were included in this retrospective study (69 males and 45 females; mean age, 67.9 ± 12.1 years; range, 39–87 years). These patients underwent abdominal dynamic contrast-enhanced CT between November 2019 and May 2020. We calculated and recorded the time from contrast material injection to the bolus-tracking trigger of 100 Hounsfield unit (HU) at the abdominal aorta (s) (Time_TRIG) and scan delay from the bolus-tracking trigger to the initiation of pancreatic parenchymal phase scanning (s) (Time_SD). The scan delay ratio (SDR) was defined by dividing the Time_SD by Time_TRIG. Non-linear regression analysis was conducted to assess the association between CT number of the pancreas and SDR and to reveal the optimal SDR, which was ≥120 HU in pancreatic parenchyma.Results:The non-linear regression analysis showed a significant association between CT number of the pancreas and the SDR (p < 0.001). The mean Time_TRIG and Time_SD were 16.1 s and 16.8 s, respectively. The SDR to peak enhancement of the pancreas (123.5 HU) was 1.00. An SDR between 0.89 and 1.18 shows an appropriate enhancement of the pancreas (≥120 HU).Conclusion:The CT number of the pancreas peaked at an SDR of 1.00, which means Time_SD should be approximately the same as Time_TRIG to obtain appropriate pancreatic parenchymal phase images in dynamic contrast-enhanced CT with bolus-tracking method.Advances in knowledge:The hemodynamic state is different in each patient; therefore, scan delay from the bolus-tracking trigger should also vary based on the time from contrast material injection to the bolus-tracking trigger. This is necessary to obtain appropriate late hepatic arterial or pancreatic parenchymal phase images in dynamic contrast-enhanced CT of the abdomen.     

Well‐differentiated papillary mesothelioma,possibly giving rise to diffuse malignant mesothelioma: A case report

Well‐differentiated papillary mesothelioma (WDPM) is a distinct subtype of mesothelial tumor from diffuse malignant mesothelioma (DMM), with an uncertain malignant potential. The relationship between WDPM and DMM, with regard to the ability of the former to develop into the latter, is also unknown. A 58‐year‐old woman, diagnosed with a rectal carcinoid tumor, underwent removal of the lymph nodes via the abdomen in 2004. A large number of white miliary nodules were identified on the mesentery and peritoneum, which were histologically diagnosed as WDPM. No further therapy was administered, but the patient was followed‐up using imaging methods. Seven years later, an abdominal wall mass was discovered using positron emission tomography‐computed tomography, and a laparotomy biopsy was performed. DMM was diagnosed, because mesothelioma with extended invasion had been histologically identified. Mesothelioma similar to papillary proliferation was present on the outer layer of the peritoneum, and an infiltrating lesion with continuous restiform or solid‐like structures was noted. WDPM was believed to have undergone malignant transformation. Compared to DMM, WDPM has a good prognosis and is considered a benign or borderline neoplasm. Our findings suggest that WDPM does have malignant potential, however, because histological findings indicated a malignant transformation of WDPM to DMM.