Direct visualization of postoperative aortobronchial fistula on computed tomography.

BACKGROUND: Postoperative aortobronchial fistula (ABF) is a rare complication that can occur in 0.3%-5.0% of patients over an extended period of time after thoracic aortic surgery. Direct visualization of the fistula via imaging is rare. AIM: To investigate the relationship between computed tomography (CT) findings and the clinical signs/symptoms of ABF after thoracic aortic surgery. METHODS: Six patients (mean age 71 years, including 4 men and 2 women) with suspected ABF on CT (air around the graft) at our hospital were included in this retrospective study between January 2004 and September 2022. Chest CT findings included direct confirmation of ABF, peri-graft fluid, ring enhancement, dirty fat sign, atelectasis, pulmonary hemorrhage, and bronchodilation, and the clinical course were retrospectively reviewed. The proportion of each type of CT finding was calculated. RESULTS: ABF detection after surgery was found to have a mean and median of 14 and 13 years, respectively. Initial signs and symptoms were asymptomatic in 4 patients, bloody sputum was found in 1 patient, and fever was present in 1 patient. The complications of ABF included graft infection in 2 patients and graft infection with hemoptysis in 2 patients. Of the 6 patients, 3 survived, 2 died, and 1 was lost to follow-up. The locations of the ABFs were as follows: 1 in the ascending aorta; 1 in the aortic arch; 2 in the aortic arch leading to the descending aorta; and 2 in the descending aorta. ABFs were directly confirmed by CT in 4/6 (67%) patients. Peri-graft dirty fat (4/6, 67%) and peri-graft ring enhancement (3/6, 50%) were associated with graft infection, endoleaks and pseudoaneurysms were associated with hemoptysis (2/6, 33%). CONCLUSION: Asymptomatic ABF after thoracic aortic surgery can be confirmed on chest CT. CT is useful for the diagnosis of ABF and its complications.

Prediction of Early-stage Liver Fibrosis Using FDG-PET/CT.

BACKGROUND/AIM: 18F-fluorodeoxyglucose (FDG) is known to accumulate in the liver. We investigated whether accumulation of FDG was correlated with the degree of liver fibrosis and the grade of necro-inflammatory activity. PATIENTS AND METHODS: This retrospective study included 35 patients who underwent FDG-positron emission tomography (PET)/computed tomography (CT) before liver surgery. On fusion images of CT and PET, by placing regions of interest on the lateral, anterior and posterior segments of the liver and the aorta, the standardized uptake value (SUV) mean, and SUV normalized by lean body mass (SUL) mean of the liver were measured, and the ratio SUVmean liver/SUVmean aorta was calculated. According to the New Inuyama Classification, subjects were classified into three groups based on the grade of liver-fibrosis degree, i.e., F0, F1+F2 and F3+F4, and into three groups based on the grade of necro-inflammatory activity, i.e., A0, A1 and A2. Each of the above parameters was then compared among the groups using a Tukey test. RESULTS: Average SULmean liver values of the F0, F1+F2 and F3+F4 groups were 1.573±0.211, 1.845±0.220 and 1.716±0.119, respectively. The SULmean liver of the F1+F2 group was significantly higher than that of the F0 group (p=0.0296). No significant difference was observed for the other two parameters. None of the parameters exhibited significant difference among the A0, A1, and A2 groups. CONCLUSION: FDG accumulation in the liver may be increased in the early stage of liver fibrosis. SULmean liver could be used to determine the necessity for therapeutic intervention in chronic liver disease.

Radiomics analysis for differentiating of cervical lymphadenopathy between cancer of unknown primary and malignant lymphoma on unenhanced computed tomography.

To investigate the usefulness of texture analysis to discriminate between cervical lymph node (LN) metastasis from cancer of unknown primary (CUP) and cervical LN involvement of malignant lymphoma (ML) on unenhanced computed tomography (CT). Cervical LN metastases in 17 patients with CUP and cervical LN involvement in 17 patients with ML were assessed by 18F-FDG PET/CT. The texture features were obtained in the total cross-sectional area (CSA) of the targeted LN, following the contour of the largest cervical LN on unenhanced CT. Values for the max standardized uptake value (SUVmax) and the mean SUV value (SUVmean), and 34 texture features were compared using a Mann-Whitney U test. The diagnostic accuracy and area under the curve (AUC) of the combination of the texture features were evaluated by support vector machine (SVM) with nested cross-validation. The SUVmax and SUVmean did not differ significantly between cervical LN metastases from CUP and cervical LN involvement from ML. However, significant differences of 9 texture features of the total CSA were observed (p = 0.001 - 0.05). The best AUC value of 0.851 for the texture feature of the total CSA were obtained from the correlation in the gray-level co-occurrence matrix features. SVM had the best AUC and diagnostic accuracy of 0.930 and 84.8%. Radiomics analysis appears to be useful for differentiating cervical LN metastasis from CUP and cervical LN involvement of ML on unenhanced CT.

Unenhanced CT texture analysis with machine learning for differentiating between nasopharyngeal cancer and nasopharyngeal malignant lymphoma.

Differentiating between nasopharyngeal cancer and nasopharyngeal malignant lymphoma (ML) remains challenging on cross-sectional images. The aim of this study is to investigate the usefulness of texture features on unenhanced CT for differentiating between nasopharyngeal cancer and nasopharyngeal ML. Thirty patients with nasopharyngeal tumors, including 17 nasopharyngeal cancers and 13 nasopharyngeal MLs, were underwent 18F-FDG PET/CT. All nasopharyngeal cancers and 7 of 13 nasopharyngeal MLs were confirmed by endoscopic biopsy. On unenhanced CT, 34 texture features were analyzed following lesion segmentation in the maximum area of the target lesion. The Mann-Whitney U test and areas under the curve (AUCs) were used for analysis and to compare the maximum standardized uptake values (SUV)max, SUVmean, and 34 texture features. A support vector machine (SVM) was constructed to evaluate the diagnostic accuracy and AUCs of combinations of texture features, with 50 repetitions of 5-fold cross-validation. Differences between the SUVmax and SUVmean for nasopharyngeal cancers and nasopharyngeal MLs were not significant. Significant differences of texture features were seen, as follows: 1 histogram feature (p = 0.038), 3 gray-level co-occurrence matrix features (p < 0.05), and 1 neighborhood gray-level different matrix feature (NGLDM) (p = 0.003). Coarseness in NGLDM provided the highest diagnostic accuracy and largest AUC of 76.7% and 0.82, respectively. SVM evaluation of the combined texture features obtained the highest accuracy of 81.3%, with an AUC of 0.80. Combined texture features can provide useful information for discriminating between nasopharyngeal cancer and nasopharyngeal ML on unenhanced CT.

Scintigraphy and computed tomography findings for the diagnosis of bronchiolitis obliterans following peripheral blood stem cell transplantation.

We report a case of bronchiolitis obliterans (BO) associated with allogenic peripheral blood stem cell transplantation for acute leukemia. On inspiratory and expiratory chest computed tomography (CT), characteristic findings for BO, such as air-trapping, mosaic attenuation or bronchial wall thickening were not clearly observed. However, ventilation-perfusion lung scans of the chest demonstrated multiple matched defects, which suggested severe obstructive airway disease. In the diagnosis of BO after stem cell transplantation, lung scans should be recommended when representative findings are not obvious on chest CT.

Clinical significance of thallium-201 SPECT after postoperative radiotherapy in patients with glioblastoma multiforme.

To assess the clinical significance of 201Tl-SPECT after postoperative radiotherapy in patients with glioblastoma multiforme (GM). Eighteen patients with macroscopically residual GM who underwent 201Tl-SPECT just after postoperative radiotherapy were analyzed. Fifteen patients (83%) received radiotherapy with a total dose of 60 Gy in conventional fractionation, and the remaining three patients were treated with 72 Gy with hyperfractionation schedules. Sixteen patients (89%) were treated with chemotherapy that consisted of procarbazine, nimustine (ACNU) and vincristine. Concerning 201Tl-SPECT, we calculated the radioactivity ratio of the tumors to contralateral normal brain (T/N ratio) on early and delayed images after 111 MBq 201Tl chloride injections. The median follow-up of all 18 patients was 14.7 months (range, 2.7-38.0 months). At the time of this analysis, 15 patients (83%) had died, and the 1-year overall survival and the median survival time were 67% and 16.2 months, respectively. Fifteen patients (83%) had disease recurrence, and the 1-year progression-free survival (PFS) rate and the median time to progression in all 18 patients were 29% and 7.6 months, respectively. Patients with a high early T/N ratio had a significantly poorer PFS than those with a low T/N ratio (P = 0.0131). On univariate analysis, early T/N ratio alone had a significant impact on PFS, and on mutivariate analysis, early T/N ratio alone was a significant prognostic factor for PFS. 201Tl-SPECT after postoperative radiotherapy was predictive of PFS in patients with macroscopically residual GM.

CT of internal hernia through a defect of the perirectal fossa.

We report a case of internal hernia due to a peritoneal defect of the perirectal fossa. This condition is extremely rare and has been reported in the literature only once. This is the first independent case report. CT findings as well as the differential diagnosis of the condition are discussed.