Takayoshi Shinya

Dual-Time-Point F-18 FDG PET/CT for Evaluation of Intrathoracic Lymph Nodes in Patients with Non-Small Cell Lung Cancer

Purpose: The aim of this study was to evaluate the diagnostic capacity of F-18 fluorodeoxyglucose dual-time-point (DTP) positron emission tomography (PET)/computed tomography (CT) for intrathoracic lymph node (LN) metastases in patients with nonsmall cell lung cancer (NSCLC). Materials and Methods: Thirty-four patients had DTP PET/CT, with 60 minutes and 2-hour scans (n = 19, NSCLC; n = 15, benign pulmonary disease). LN diagnoses were confirmed by surgery or clinical follow-up (n = 14, metastatic LNs; n = 45, nonmetastatic LNs; n = 39, inflammatory LNs). Results: The maximum standardized uptake value (SUVmax) in the metastatic group was significantly higher than those in the nonmetastatic and inflammatory groups on both early- and delayed-phase imaging (each P < 0.0001). The retention index (RI) of SUVmax (RI-SUVmax) in the metastatic group was significantly higher than in the nonmetastatic (P = 0.0008) and inflammatory groups (P = 0.0074). No significant difference was found between SUVmax values of the nonmetastatic and inflammatory groups on early- (P = 0.6461) or delayed-phase (P = 0.6913), or between RI-SUVmax values of the nonmetastatic and inflammatory groups (P = 0.5717). For early-phase SUVmax, the cut-off value for highest accuracy with metastatic LNs was 3.61, yielding a sensitivity of 86.67% and a specificity of 88.00%. For delayed-phase SUVmax, the cut-off value was 4.00, yielding a sensitivity of 91.6% and specificity of 92.9%. For RI-SUVmax, the cut-off value was 20.91%, yielding a sensitivity of 73.6% and specificity of 75.9%. Conclusions: DTP PET/CT with a semiquantitative technique may improve diagnostic capacity for nodal staging of NSCLC.

Assessment of mean transit time in the engrafted lung with 133Xe lung ventilation scintigraphy improves diagnosis of bronchiolitis obliterans syndrome in living-donor lobar lung transplant recipients

ObjectiveStaging of bronchiolitis obliterans syndrome (BOS) following lung transplantation is based on declines in forced expiratory volume in 1 s (FEV1). The aim of this study was to evaluate the usefulness of 133Xe ventilation scintigraphy in the early detection of BOS following living-donor lobar lung transplantation (LDLLT), to compare 133Xe washout imaging with computed tomography (CT) findings for early detection of BOS following LDLLT, and to evaluate 133Xe washout imaging by quantitative analyses.MethodsSubjects comprised 30 double-lung recipients and 1 single-lung recipient, who had undergone LDLLT at our institution and survived more than 1 year. Clinically diagnosed BOS developed in six recipients. Declines in graft function were evaluated using a combination of three methods, namely, dynamic spirometry, high-resolution CT (HRCT), and 133Xe ventilation scintigraphy. Findings for all transplanted lungs were compared between CT and 133Xe washout imaging. 133Xe washout imaging was assessed using mean transit time (MTT) of bi-and unilateral lungs. Correlations between MTT of bilateral lungs and FEV1% were evaluated. Differences in MTT between BOS and non-BOS lungs, and between non-BOS and donor lungs were also evaluated on unilateral lungs. Appropriate cut-off values of MTT of unilateral lungs were set for the diagnosis of BOS.ResultsIn all six BOS cases, prolonged-washout images of engrafted lungs revealed early-phase BOS with declines from baseline FEV1, whereas only one BOS case could be detected using early CT findings of BO (bronchodilatation, decrease in number and size of pulmonary vessels, thickening of septal lines, and volume reduction). A significant correlation was identified between MTT and FEV1% (r = −0.346, P < 0.0001). MTT of unilateral lungs was significantly longer in BOS lungs than in non-BOS lungs (P < 0.0001). The cut-off MTT of unilateral lungs for the diagnosis of BOS was set at 64.77 s.ConclusionsOur data show that 133Xe washout imaging offers excellent potential for early detection of BOS compared with early CT findings. Using 133Xe washout imaging and MTT with radioactive tracer offers a noninvasive indication of selective ventilatory function in engrafted lungs following LDLLT. MTT appears useful for identifying BOS following LDLLT and allows quantitative evaluation of graft function in unilateral lungs.

Computed tomography findings of congenital generalized lipodystrophy: multiple nodular fatty liver and diffuse sclerosis of bones

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disease that is also referred to as Berardinelli-Seip syndrome. It is characterized by a lack of adipose tissue throughout the body from birth, muscular hypertrophy, advanced bone age, fatty liver, and insulin resistance. We describe computed tomography (CT) and magnetic resonance findings for a 35-year-old woman with CGL. Multiple nodular, well-defined regions of fatty infiltration of the liver are rare and have never been previously reported in a patient with lipodystrophy. To our knowledge, this is the first report describing CT findings of bone sclerotic changes associated with CGL.

Small bowel neoplasms: enhancement patterns and differentiation using post-contrast multiphasic multidetector CT

PurposeThe purpose of the present study was to analyze the enhancement patterns of small bowel neoplasms on post-contrast multiphasic multidetector CT and to assess the diagnostic capacity for differentiating five tumor types.MethodsWe performed a retrospective study of data on 92 small bowel neoplasms. The neoplasms were categorized into five groups according to pathology findings, not imaging findings (23 adenocarcinomas; 22 lymphomas; 19 metastases; 18 gastrointestinal stromal tumors [GIST]; 10 neuroendocrine tumors [NET]).ResultsGIST and NET demonstrated a hypervascular pattern in the multiphasic dynamic study. Adenocarcinoma and lymphoma showed a delayed enhancement pattern. Metastasis was classified as an intermediate enhancement pattern. The receiver operating characteristic analyses revealed that attenuation thresholds could be set with acceptable accuracies for most of the small bowel neoplasms.ConclusionsMultiphasic dynamic studies may have the potential to improve the diagnostic capacity of multidetector CT for small bowel neoplasms.

Positive gallium-67 and thallium-201 scans in thymic rebound after chemotherapy for lymphoma.

It is a diagnostic problem to distinguish thymic rebound or rebound thymic hyperplasia from thymic malignancy, but it is frequently made more difficult because most patients have had previous malignancies. Recently we evaluated a six-year-old girl with thymic rebound after chemotherapy for lymphoma, by both gallium-67 and thallium-201 scans. On gallium-67 scan, intensive uptake was seen in the anterior mediastinum. CT revealed a triangular-shaped, homogeneous mass in the anterior mediastinum. On early scan of thallium-201 study, slight accumulation was seen in the anterior mediastinum and was enhanced in delayed scans. Considering the clinical state and imaging results, thymic rebound after chemotherapy was the most likely diagnosis, and follow-up observation was done without therapy. During the course, there were no signs of relapse. Some reports have described both positive and negative thallium-201 accumulation in thymic rebound. Although more experience with similar cases is necessary, it is likely that thallium-201 also tends to accumulate in thymic rebound as well as gallium-67.

A rapid caliber change in the inferior vena cava during multiphasic contrast-enhanced computed tomography may signal an acute anaphylactic reaction to nonionic contrast medium

Severe anaphylactic reactions to an intravenous nonionic iodine contrast medium (NICM) are uncommon but can result in permanent morbidity or death if not managed appropriately. An anaphylactic reaction to an NICM typically manifests as clinical symptoms that include an itchy nose, sneezing, and skin redness. To our knowledge, a rapid change in the caliber of the inferior vena cava (IVC) during multiphasic contrast-enhanced computed tomography (CT) has not been reported. Here, we report the computed tomographic findings in three cases of hypovolemic shock caused by an anaphylactic reaction to an NICM. We suspect that a decrease in caliber of the IVC during multiphasic contrast-enhanced CT may be a predictor of an allergic-like reaction to an NICM. Patients in whom physicians and radiographers detect a rapid caliber change in the IVC during multiphasic contrast-enhanced CT should be managed carefully.

Both a visual and a semiquantitative analysis for differentiating benign from malignant chondrogenic bone tumors using Tc-99m (V) DMSA scintigraphy: a prospective study.

OBJECTIVE The aims of this prospective study were to assess the relationship between tumor aggressiveness and Tc-99m (V) dimercaptosuccinic acid (DMSA) uptake in chondrogenic bone tumors and the value of Tc-99m (V) DMSA scintigraphy for differentiating benign from malignant tumors. METHODS Twenty-four patients with chondrogenic tumors (19 benign and five malignant) underwent Tc-99m DMSA (V) scintigraphy. Radiopharmaceutical uptake was classified using a three-point scale to allow a visual-only analysis, and a tumor-to-background contrast (TBC) was computed using regions of interest to provide a semiquantitative analysis. Spearmans correlation coefficient was used to assess the correlation between tumor aggressiveness and TBC. The difference in TBC between benign and malignant tumors was analyzed with the Mann-Whitney U-test. An appropriate cutoff value of TBC was chosen for the diagnosis of malignancy of a tumor using receiver operating characteristic analysis. RESULTS Six benign tumors showed negative uptake (uptake score 0), whereas 13 benign tumors showed positive uptake (n=10 uptake score 1; n=3 uptake score 2). All chondrosarcomas showed positive uptake (n=2 uptake score 1; n=3 uptake score 2). A significant correlation was found between tumor aggressiveness and TBC. A significant difference was seen in TBC between benign and malignant tumors. With the chosen cutoff value of TBC equal to 0.611, the sensitivity was 80.0%, specificity was 78.9%, the positive predictive value was 50.0%, and the negative predictive value was 93.8%. CONCLUSION Tc-99m (V) DMSA scintigraphy may have the potential to improve diagnostic methods for detecting chondrosarcomas using visual and/or semiquantitative analyses.