Motohiro Sato

Extrapancreatic F-18 FDG accumulation in autoimmune pancreatitis.

We report two cases of autoimmune pancreatitis (AIP) in which fluorine-18 fluorodeoxyglucose (FDG) showed moderate accumulation in the pancreas, as well as in bilateral submandibular glands and in multifocal lymph nodes. FDG positron emission tomography (PET)/computed tomography (CT) is a useful diagnostic tool to assess the extrapancreatic lesions of AIP, which is a recently proposed new clinicopathological entity named immunoglobulin G4 (IgG4)-related systemic disease. Recognition of the FDG-PET/CT findings of IgG4-related sclerosing disease is crucial to avoid unnecessary surgery or other intervention because of similarities to malignant lymphoma or malignant tumor with multiple lymph node metastases.

The functional hepatic volume assessed by99mTc-GSA hepatic scintigraphy

The accuracy of measurement of the functional hepatic volume by single photon emission computed tomography (SPECT) with99mTc-galactosyl serum albumin (99mTc-GSA) was evaluated.99mTc-GSA planar scintigraphic images were obtained dynamically and the hepatic SPECT imaging was then performed in 25 patients with hepatobiliary tumors. The patients were divided into 4 groups with normal hepatic function, and mild, moderate and severe hepatic dysfunction. The functional hepatic volume determined by SPECT was compared with the morphological hepatic volume determined by computed tomography. The ratio of the hepatic volumes obtained by the two methods was calculated. The mean hepatic volume ratio was 96.6 ± 2.3% in the normal hepatic function group and 95.9 ± 2.2% in the mild dysfunction group (n.s.). In both the moderate and severe hepatic dysfunction groups, the hepatic volume ratio was smaller than that in the normal group (87.9 ±5.2%, p < 0.001, and 71.9 ± 7.6%, p < 0.0001, respectively). There was a linear correlation between the hepatic volume ratio and various indices of reserve hepatic function, such as LHL15 (r = 0.83, p < 0.0001), HH15 (r = 0.74, p < 0.0001), and ICG15 (r = 0.75, p < 0.0005). These results indicate that the hepatic volume ratio is proportional to the severity of hepatic dysfunction, and suggest that the functional hepatic volume measured with99mTc-GSA faithfully reflects the functioning hepatocyte mass.99mTc-GSA scintigraphy and hepatic SPECT therefore provide information regarding global and regional reserve hepatic function.

F-18 FDG PET/CT in relapsing polychondritis

We report a case of relapsing polychondritis for which fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) showed increased FDG accumulation in all rib cartilages, as well as in the larynx, trachea, and major bronchi. Contrast-enhanced CT during PET/CT showed smooth tracheal and bronchial wall thickening with calcification and airway narrowing. After steroid therapy, clinical symptoms and laboratory data were improved and cartilaginous FDG accumulation had completely disappeared. FDG PET/CT is considered to be a powerful radiological tool to assess the disease activity of relapsing polychondritis.

Usefulness of FDG-PET/CT in the detection of pancreatic metastases from lung cancer

ObjectiveThe objective of this study was to assess the ability to detect pancreatic metastasis of lung cancer and to clarify the degree of fluorodeoxyglucose (FDG) accumulation and computed tomography (CT) characteristics of pancreatic metastasis from lung cancer.MethodsA total of 573 patients (415 men and 158 women) with lung cancer were retrospectively evaluated. All patients underwent FDG-positron emission tomography (PET)/CT with contrast-enhanced CT for first=stage (313 patients; initial study group) or follow-up study (260 patients; follow-up study group). A lesion was regarded as positive for metastasis on the basis of visual judgment of the degree of increased metabolism by two experienced and independent interpreters, supported by semiquantitative evaluation on the basis of calculation of the maximum standardized uptake value (SUVmax).ResultsAbnormal accumulations in the pancreas were detected in 5 of 313 patients (1.60%) in the initial study group, and 6 of 260 patients (2.31%) in the follow-up study group. Seven of these patients had adenocarcinoma, three had small cell carcinoma, and the rest had large cell endocrine carcinoma. Tumor sizes (longitudinal diameter), measured by CT, of these 11 patients ranged from 6 mm to 52 mm (mean ± SD 8.3 mm ± 11.9 mm), and SUVmax for 1 h ranged from 3.37 to 11.1 (mean ± SD 6.12 ± 2.43). Three of these pancreatic lesions were difficult to determine by routine transaxial images, and detection was obvious only by thin-slice images or multiplanar reconstruction images. Contrast-enhanced CT showed gradual fill-in from the peripheral portion to the center. In addition, 10 of 11 cases did not show main pancreatic duct dilatation even if the tumor size was large.ConclusionsMetastases to the pancreas in lung cancer patients are not so rare and radiologists first have an important role to detect the pancreatic mass and then suggest to metastasis as the likely diagnosis. For this purpose, FDG-PET/CT has an advantage in depicting unsuspected pancreatic metastasis from lung cancer, particularly that which is not detected by CT alone.

Usefulness of F-18 FDG PET/CT in the assessment of disseminated Mycobacterium avium complex infection

A patient showing abnormal fluorine-18-fluorodeoxyglucose (FDG) uptake due to disseminated Mycobacterium avium complex (MAC) infection is presented. Increased focal FDG uptake was demonstrated in the cervical and supraclavicular lymph nodes, spleen, and diffuse bone marrow. FDG PET/CT is considered as a useful diagnostic tool to assess the exact extent and activity of disseminated MAC infection. Moreover, it is advantageous over CT and magnetic resonance imaging to assess the treatment response and time course of the disease.

FDG PET/CT findings of thymic carcinoid and bronchial carcinoid in a patient with multiple neuroendocrine neoplasia type1.

Thymic carcinoid is a rare thymic neoplasm and frequently accompanies neuroendocrine neoplasia (MEN) type1. Other carcinoid tumors derived from the foregut, like bronchial, gastric, and duodenal carcinoid are also of high incidence in MEN type1 patients. Recent studies revealed thymic carcinoid as a FDG-avid tumor, and FDG-PET is useful in detecting thymic carcinoid, its metastases, and recurrence. On the other hand, FDG accumulation in bronchial carcinoid is variable. We report a case of thymic carcinoid and bronchial carcinoid in a patient who was diagnosed as having multiple neuroendocrine neoplasia type1 previously. FDG PET/CT showed abnormal accumulation in the thymic atypical carcinoid and its mediastinal lymph node metastases, whereas the FDG did not show uptake in the typical bronchial carcinoid. These findings indicate that FDG PET is useful in detecting thymic carcinoid and its metastases.

High F-18 fluorodeoxyglucose accumulation in solid pseudo-papillary tumors of the pancreas

We report two cases of young women with a solid pseudo-papillary tumor of the pancreas which having cystic and hemorrhagic components with marked calcification on computed tomography and magnetic resonance imaging. F-18 fluorodeoxyglucose positron emission tomography revealed abnormally increased accumulation of F-18 fluorodeoxyglucose in the pancreas tail tumors, especially in the non-calcified solid portion of the tumors. These patients underwent elective resection of the masses and distal pancreatectomy and were diagnosed with solid pseudo-papillary tumors by histopathological analysis. There was no evidence of distant metastasis on follow-up after surgery and they showed no histopathological findings suggesting malignancy. These cases suggest that solid pseudo-papillary tumor may show high uptake of F-18 fluorodeoxyglucose.

F-18 FDG accumulation in mucinous cystic neoplasm of pancreas.

We report a case of mucinous cystic neoplasm which showed FDG accumulation in its cyst wall. MRI revealed that this tumor had repeated intracystic hemorrhage. Inhomogeneous FDG accumulation was found in the cyst wall. The epithelium was focally denuded and ovarian-like stroma with macrophage migration, which phagocytosed red blood cells, and fibrosis were recognized on histopathological examination. These histopathological findings suggested that FDG accumulates not in the monolayer epithelium but in ovarian-like stroma with macrophage migration and fibrosis. Macrophage migration and fibrosis were considered to have contributed to FDG accumulation in this mucinous cystic neoplasm.

Epilepsy accompanied by intracranial arachnoid cysts: studies on volume and regional cerebral blood perfusion using MRI and SPECT

Abstract To evaluate whether arachnoid cysts (ACs) can directly cause epilepsy by cortical compression, we studied the relationships among seizures, the volume of ACs, and regional cerebral blood perfusion around ACs. Subjects were 11 patients (10.5 ± 7.2 years) with primary intracranial ACs. The AC volume was calculated from axial T 1 -weighted magnetic resonance imaging (MRI). N-isopropyl p-iodoamphetamine ( 123 I-IMP) single photon emission computed tomography (SPECT) was used to evaluate cerebral blood perfusion. The lesional side to normal side ratio (L/N ratio) was calculated from rectangular and irregular region of interests (ROIs) in frontal and temporal area around the ACs. The volume of ACs in nonepileptic patients was significantly larger than in epileptic patients. In nonepileptic patients, SPECT demonstrated hyperperfusion around ACs, whereas in epileptic patients it showed hypoperfusion. The L/N ratio of rectangular ROIs in the posterior temporal area and irregular ROIs in the temporal area were significantly lower in epileptic patients than in nonepileptic ones. Our results suggest that epilepsy with ACs is related to the cerebral blood perfusion in the surrounding brain structures rather than to the volume of the ACs. Not only compression but also complicated brain parenchymal lesions may participate in the development of epilepsy.

Tc-99m diethylenetriamine pentaacetic acid (DTPA)-human serum albumin (HSA) radionuclide lymphography for detecting the location of chyluria.

The cause of chyluria cannot be easily detected by CT scan or other imaging methods, except conventional lymphography, but Tc-99m diethylenetriamine pentaacetic acid radionuclide lymphography clearly revealed the location of chyluria in the left renal pelvic area. Radionuclide lymphography is one of the choices in investigating chyluria due to its noninvasive and simple technique.