Kentaro Takanami

Evaluation of the relationship between physiological FDG uptake in the heart and age, blood glucose level, fasting period, and hospitalization

ObjectivePositron emission tomography (PET) with fluorodeoxyglucose (FDG) is widely used for evaluation of cancer and ischemic heart disease. Recently, increased myocardial FDG uptake has been reported to be related to some types of heart disease, such as sarcoidosis. However, the physiological increased FDG uptake in the heart often mimics the abnormal high uptake in these cases. In this study, we investigated the relationships between myocardial uptake and age, blood glucose level, fasting period, and hospitalization status (inpatient vs. outpatient).MethodsA total of 159 non-diabetic patients were enrolled in the present study. Patients were imaged on a PET/CT scanner, and a three-dimensional region of interest (ROI) was drawn on the fused PET/CT image to measure the maximum standardized uptake value (SUVmax) of the whole left ventricle.Results: No significant relationships were observed between myocardial uptake and age or fasting period. Blood glucose level showed a significant relationship (p = 0.025) with myocardial uptake, but the R-square was extremely small (r2 = 0.03). With an SUVmax threshold of 3.0, there was no significant difference between inpatients and outpatients. However, outpatients showed a significantly higher frequency of myocardial uptake over SUVmax of 5.0 (x2 test: p = 0.046).ConclusionIt is difficult to predict the degree of physiological uptake in the heart from data regarding age, fasting period, or blood glucose level. Outpatients tend to show higher myocardial uptake than inpatients, which may make it difficult to detect abnormally increased uptake in the heart. A long fasting period, such as overnight fasting, is an inadequate means to reduce the physiological uptake of FDG in the heart.

Intraductal papillary mucininous neoplasm of the bile ducts: multimodality assessment with pathologic correlation

Mucin-producing intraductal papillary neoplasm (adenocarcinoma/adenoma) in the bile duct is becoming recognized as a specific type of neoplasm. Since, it bears a striking similarity to intraductal papillary mucinous neoplasms of the pancreas with regard to its histopathologic features, the term “intraductal papillary mucinous neoplasms of the bile duct” (IPMN-B) is frequently used, although no definite terminology or definition has been decided by World Health Organization. This neoplasm lacks ovarian-like stroma and communicates with the bile ducts, unlike biliary mucinous cystic neoplasm (MCN). On the other hand, malignant IPMN-B is categorized as an intraductal-growth type of intrahepatic cholangiocarcinoma (ICC). In comparison to other types of ICC, such as the mass-forming type and periductal-infiltrating type that have poor resectability and an unfavorable prognosis, malignant IPMN-B can be resected and demonstrates a more favorable prognosis. Meanwhile, unlike biliary MCN that is usually confined in a closed cyst, IPMN-B can spread along the mucosal surface of the bile ducts, and it should be widely resected. Therefore, multimodality assessment is needed to ensure the correct diagnosis of IPMN-B. We herein review the imaging findings of IPMN-B with pathologic correlation.

Imaging of hypoxic lesions in patients with gliomas by using positron emission tomography with 1-(2-[18F] fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole, a new 18F-labeled 2-nitroimidazole analog

OBJECT Assessment of hypoxic conditions in brain tumors is important for predicting tumor aggressiveness and treatment response. A new hypoxia imaging agent, 1-(2-[(18)F]fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole (FRP-170), with higher image contrast and faster clearance than preexisting hypoxia tracers for PET, was used to visualize hypoxic tissues in 8 patients with glioma. METHODS The FRP-170 was injected and PET imaging was performed 2 hours later in 8 patients, including 3 with glioblastoma multiforme, 2 with oligodendroglioma, and 1 each with diffuse astrocytoma, anaplastic ganglioglioma, and recurrent anaplastic astrocytoma. All 8 patients also underwent MR imaging, and some patients underwent [(11)C]methionine or [(18)F]fluorodeoxyglucose PET, and proton MR spectroscopy for comparison. Tissues obtained at biopsy or radical resection were immunostained with hypoxia-inducible factor-1alpha (HIF-1alpha) antibody for the confirmation of hypoxia, except in the patient with recurrent anaplastic astrocytoma who was treated using Gamma Knife surgery. RESULTS The FRP-170 PET images showed marked uptake with upregulation of HIF-1alpha in the 3 glioblastomas multiforme, and moderate uptake in the recurrent anaplastic astrocytoma and one oligodendroglioma, but no uptake in the other tumors. The FRP-170 PET images showed positive correlation with HIF-1alpha immunoreactivity and some correlation with FDG PET and MR imaging enhancement, but no correlation with [(11)C]methionine PET. Imaging with FRP-170 PET seemed to be more sensitive for detecting hypoxia than identifying the lactate peak on proton MR spectroscopy. CONCLUSIONS Imaging with FRP-170 PET can visualize hypoxic lesions in patients with glioma, as confirmed by histological examination. This new method can assess tumor hypoxia preoperatively and noninvasively.

F-18 FDG PET/CT findings in two patients with hepatic angiomyolipoma with and without intratumoral hemorrhage.

Two female patients aged 62 and 74 years underwent F-18 FDG PET/CT for evaluation of a large hepatic tumor. Subsequently, both patients underwent a partial hepatectomy which histopathologically revealed benign hepatic angiomyolipomas (AMLs). One patient with AML with a massive intratumoral hemorrhage presented with multiple foci demonstrating an increased FDG uptake along the margin of the cold defects that corresponded to low density areas within the tumor on contrast-enhanced CT, whereas the other patient with AML without any hemorrhage presented with a low FDG uptake in the tumor. This report demonstrates that benign hepatic AMLs may demonstrate increased FDG uptake if there is hemorrhage and a related inflammatory response.

FDG PET/CT findings in malignant intraductal papillary mucinous neoplasm of the bile ducts.

Abstract: A 58-year-old man with no significant symptoms was referred to the hospital due to the presence of an intrahepatic cystic tumor and a dilated intrahepatic bile duct. F-18 FDG PET/CT demonstrated intense FDG uptake in the marginal region of the cystic tumor. Subsequently, the patient underwent a right hemihepatectomy with extrahepatic bile duct resection. The histopathology revealed a malignant intraductal papillary mucinous neoplasm of the bile ducts with dysplasia. This report thus documents the FDG PET findings in malignant intraductal papillary mucinous neoplasm of the bile ducts, which showed an intense FDG uptake in the tumor.

Validation of the use of calibration factors between the iodine concentration and the computed tomography number measured outside the objects for estimation of iodine concentration inside the objects: phantom experiment

PurposeThe aim of this study was to validate the use of a calibration factor measured outside the object for estimating the iodine concentration inside the object to improve the accuracy of the quantitative contrastenhanced computed tomography (CT).Materials and methodsSeveral known concentrations (0, 6, 9, and 12 mg I/ml) of iodine contrast material (CM) samples were placed inside and outside cylindrical acrylic phantoms of two sizes and were imaged under various combinations of the tube voltages and currents (kV/mAs–80/200, 100/200, 120/200, 140/200) to obtain K factors. The K factors were compared between the phantoms and among the tube voltages. Each CM concentration was estimated from the CT number using the K factor measured outside the phantom.ResultsThe K factors varied between the phantoms or among the tube voltages (P < 0.05). Although there were statistically significant variations in K factors among the different regions in a phantom, the mean variation coefficient was 3%–4%. The mean error of the estimated concentration was −5.5%.ConclusionThe CM concentration should be accurately estimated at the region within a patient’s body using the K factor measured at the surface of the body regardless of body size and tube voltage.

FDG PET for esophageal cancer complicated by sarcoidosis mimicking mediastinal and hilar lymph node metastases: two case reports.

This report documents 2 cases of esophageal cancer complicated by sarcoidosis mimicking mediastinal lymph node metastases on F-18 fluorodeoxyglucose positron emission tomography (FDG PET) for staging of the cancer. In both cases, FDG PET demonstrated intense uptake in the swollen mediastinal and bilateral hilar lymph nodes. In 1 case, FDG PET showed intense uptake in the primary esophageal cancer. In another case, FDG PET showed no definite intense uptake in the primary esophageal cancer. The histopathology of the resected mediastinal and hilar lymph nodes demonstrated no malignant cells but sarcoid lesions such as noncaseating granuloma. Therefore, sarcoidosis should be considered when FDG PET shows intense FDG uptake in nonregional swollen lymph nodes, although the incidence of esophageal cancer complicated by sarcoidosis is rare.

Q fever with lymphadenopathy on F-18 FDG PET.

A 22-year-old woman with a high fever of unknown origin underwent PET imaging that demonstrated intense uptake in a swollen abdominal lymph node. After treatment with antibiotics consisting of doxycycline and rifampicin, the fever went down and both the size and uptake in the lymph node also decreased. Later, the patient was serologically diagnosed to have acute Q fever. This report indicates that FDG PET/CT may be useful for identifying lymphadenopathy because of Q fever.

Evaluation of radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid scintigraphy

We evaluated radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy. Between May 2010 and April 2011 we performed I-123 BMIPP scintigraphy for patients who had maintained complete response to curative radiotherapy (RT) for esophageal cancer for more than six months. We compared the area of the myocardium in the RT fields with that of reduced I-123 BMIPP uptake using a 15-segment model that is based on axial computed tomography (CT) images. We classified the segments into three categories: segments receiving 40 Gy (Segment 40 Gy), segments receiving 60 Gy (Segment 60 Gy) and segments out of the radiation fields (Segment 0 Gy). A segment with reduced uptake in the RT fields was defined as positive. A total of 510 segments in 34 patients were used for analysis. The median interval from completion of RT to I-123 BMIPP scintigraphy was 22 months (range, 6–103 months). The numbers of Segment 0 Gy, Segment 40 Gy and Segment 60 Gy were 324, 133 and 53, respectively. Reduced uptake was detected in 42.9% (57/133) of Segment 40 Gy, 67.9% (36/53) of Segment 60 Gy and 13.3% (43/324) of Segment 0 Gy. The odds ratios of 40 Gy and 60 Gy compared with regions out of the RT fields were 5.2 (95% confidence interval [CI]: 3.7–7.4) and 15.4 (95% CI: 6.9–34.6), respectively. Reduced myocardial I-123 BMIPP uptake in RT fields, suggesting RT-induced myocardial damage, was frequently observed. I-123 BMIPP myocardial scintigraphy may be useful for identifying RT-induced myocardial damage.

Two cases of 18 F-FDG PET/CT findings in acinar cell carcinoma of the pancreas.

The patients consisted of a 60-year-old woman and a 72-year-old man with no significant symptoms, who were both referred to the hospital due to the presence of large pancreatic tumors. They underwent F-18 FDG PET/CT and subsequently a pancreaticoduodenectomy and acinar cell carcinoma in the pancreas was proven histopathologically. In one case, the tumor consisted of a solid component presenting intense FDG uptake and necrotic tissue. In another case, the tumor consisted of cystic and papillary components presenting with weak FDG uptake. This report thus documents 2 cases of acinar cell carcinoma that showed contrasting histopathologic and F-18 FDG PET/CT findings.