Shigeaki Higashiyama

Distinguishing benign from malignant gallbladder wall thickening using FDG-PET.

ObjectiveBecause thickening of the gallbladder wall is observed not only in patients with gallbladder cancer but also in those with benign diseases such as chronic cholecystitis and gallbladder adenomyosis, it is difficult to distinguish between benign and malignant gallbladder wall thickening by conventional techniques of diagnostic imaging such as computed tomography (CT), magnetic resonance imaging (MRI), and abdominal ultrasonography (US). In the present study, we attempted to distinguish between benign and malignant gallbladder wall thickening by means of fluorine- 18-fluorodeoxyglucose (FDG)- Positron emission tomography (PET).MethodsFDG-PET was performed in 12 patients with gallbladder wall thickening detected by CT or US, to determine whether it was benign or malignant. Emission scans were taken, beginning 45 minutes after intravenous administration of FDG, and SUV was calculated as an indicator of glucose metabolism.ResultsOf the 12 patients, 4 showed positive uptake of FDG in the gallbladder wall. Of these 4 patients, 3 had gallbladder cancer. The remaining one, who had chronic cholecystitis, had false-positive findings. The other 8 patients had negative uptake of FDG in the gallbladder wall. Two of these 8 underwent surgical resection, which yielded a diagnosis of chronic cholecystitis. The other 6 patients exhibited no sign of gallbladder malignancy and have been followed without active treatment.ConclusionsFDG-PET appears able to distinguish between benign and malignant gallbladder wall thickening.

The usefulness of18F-FDG PET images obtained 2 hours after intravenous injection in liver tumor

Liver tumors, especially hepatocellular carcinomas (HCCs), often exhibit no contrast with surrounding non-tumorous liver tissue in F-18-fluoro-2-deoxy-2-fluoro-d-glucose (FDG) positron emission tomography (PET) images obtained at the usual interval of one hour after intravenous FDG injection. We evaluated the usefulness of FDG PET studies of liver tumors performed 2 hours after intravenous injection.Methods and Materials: Fifteen pretherapeutic patients with 33 liver tumors were studied, including 11 patients with 18 HCCs, and 4 patients with 15 metastatic liver tumors (METAs) from 3 colorectal carcinomas and 1 esophageal carcinoma. After transmission scans, emission scans were obtained 45–55 minutes and 115–125 minutes after intravenous injection of 185–370 MBq FDG as early images and delayed FDG PET images, respectively. Visual analysis of early and delayed images was performed, and the FDG uptake in the tumor to that in nontumorous liver ratio (T/N ratio), the FDG uptake in tumor to that in soft-tissue ratio (T/S ratio) and the FDG uptake in non-tumorous liver to that in soft-tissue ratio (N/S ratio) were calculated for each image.Results: In visual analysis, visual improvement seen in images was observed in 6 of 18 HCC lesions and all 15 META lesions. In quantitative analysis, the mean T/S ratio and T/N ratio of HCCs in early images were 4.97 and 1.90, respectively, and those in delayed images were 6.24 and 2.20, respectively. The mean T/S ratio and T/N ratio of METAs in early images were 5.97 and 2.21, respectively, and those in delayed images were 6.99 and 3.80, respectively. The T/S ratio of HCCs and T/S ratio and T/N ratio of METAs were significantly higher in delayed images than in early images. The mean N/S ratios of HCC cases were 2.58 in the early images and 2.57 in the delayed images, but the ratio showed no constant tendency in the images. All N/S ratios of META cases were decreased in delayed images, although the significance of the small number of cases.Conclusion: FDG PET studies performed 2 hours after intravenous injection were useful for clear visualization of liver tumors, especially metastatic liver tumors.

Physiological FDG uptake in the palatine tonsils

In clinical F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) studies of the head and neck region, remarkable symmetric tonsillar FDG uptake is sometimes observed. We determined the incidence and degree of tonsillar FDG uptake and investigated the significance of tonsillar FDG uptake. Between June 1998 and August 1998, we obtained informed consent from 17 patients who were scheduled to undergo a FDG-PET study for their own disease (11 men and 6 women; aged 22 to 77 yr) and who did not have head and neck disease to perform FDG-PET scanning of the head and neck region in addition to their target organs. The incidence and degree of tonsillar FDG uptake were determined. Remarkable tonsillar FDG uptake was found in 9 patients. The SUVs of these FDG uptakes ranged from 2.48 to 6.75, with a mean of 4.29±1.20 (SD). Tonsillar FDG uptakes in the remaining 8 patients were not remarkable, and their SUVs ranged from 1.93 to 3.31, with a mean of 2.46±0.45. Head and neck disease does not appear to have been responsible for the increase in tonsillar FDG uptake. Differences among tonsillar FDG uptake in these 17 patients without head and neck disease appear to reflect differences in activity of “physiological” inflammation of the palatine tonsils.

Frontal hypoperfusion in depressed patients with dementia of Alzheimer type demonstrated on 3DSRT.

Aims:  Depressive symptoms are common in patients with dementia of Alzheimer type (DAT) and contribute to clinical morbidity. Previous studies have suggested that hypoperfusion in the prefrontal cortex and anterior cingulate gyrus are involved in the pathophysiology of depression in DAT. Using 3‐D stereotactic region of interest (ROI) template (3DSRT), fully automated ROI analysis software, the purpose of the present study was to investigate the relationship between depressive symptoms and regional cerebral blood flow (rCBF) in DAT.

The relationship between depressive symptoms and prefrontal hypoperfusion demonstrated by eZIS in patients with DAT.

Depressive symptoms are common in Alzheimers disease (AD) and contribute to clinical morbidity. Previous studies have suggested that hypoperfusion in the prefrontal cortex and anterior cingulate gyrus are involved in the pathophysiology of depression. Using the easy Z-score imaging system (eZIS), we investigated the relationship between depressive symptoms and prefrontal hypoperfusion in AD. Tc-99m-ethyl cysteinate dimer (Tc-99m-ECD)-single photon emission tomography (SPECT) and Neuropsychiatric Inventory (NPI) were performed in forty-four patients diagnosed as having Dementia of Alzheimers type (DAT) with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). These patients were divided into the depressive group (D group: n=26) and non-depressive group (ND group: n=18) using NPI depression items. All data from SPECT images were analyzed using eZIS software. Scores in four regions were determined by Z-values; these regions consisted of each side of the prefrontal cortex and anterior cingulate gyrus. The mean scores between the D group and ND group were compared. The mean scores of the left prefrontal cortex in the D group were significantly higher (p<0.0125) than those in the ND group. There were no significant differences in the scores of the right prefrontal cortex and the bilateral anterior cingulate gyrus between these two groups (Mann-Whitney U-test). These findings suggest that hypoperfusion in the left prefrontal area contributes to the expression of depressive symptoms in patients with DAT.

Effectiveness of preoperative PET examination of huge angiosarcoma of the heart.

Abstract: We report a 60-year-old-woman with a huge intracardiac angiosarcoma in whom preoperative F-18 fluorodeoxyglucose (FDG) PET was useful for confirming malignancy of the tumor and determining whether surgery was indicated for it. Her chief complaint was dyspnea. Because she was suspected to have a huge intracardiac tumor on the basis of transthoracic echocardiographic and computed tomography (CT) findings, FDG PET was performed, and the maximum standardized uptake value (SUV) of the tumor was found to be 5.6. Because other tests and SUV level suggested a malignant cardiac tumor, surgical resection of it was attempted. On histopathological examination, the tumor was found to be an angiosarcoma. Our experience with this case indicates that, when dealing with patients suspected to have very large tumors, FDG PET is useful in examination for malignant potential and is indispensable in exploration for distant metastases.

FDG uptake by tongue and muscles of mastication reflecting increased metabolic activity of muscles after chewing gum.

Glucose metabolic activity of the muscles increases during exercise. The authors report an example of intense F-18 fluorodeoxyglucose (FDG) uptake by the tongue and the muscles of mastication in a patient after 3 hours of chewing sugar-free gum before F-18 FDG administration.

Evaluation of diagnostic abilities of Ga-SPECT for head and neck lesions.

ObjectiveSingle-photon emission computed tomography (SPECT) using gallium (Ga) has been frequently used for diagnosing head and neck tumors in patients. Although the usefulness of Ga-SPECT is well known, the degree of the increase in diagnostic ability with Ga-SPECT for head and neck tumors has not been reported. We compared the ability of the planar images of Ga scintigraphy, SPECT images of Ga scintigraphy, and CT images to diagnose head and neck primary tumors and neck metastases.MethodsThe subjects of this study were 167 patients with malignant head/neck lesions. For Ga scintigraphy, Ga-67-citrate (74 MBq) was injected via a cubital vein. Planar and SPECT images were taken 72 h after the Ga-67-citrate injection. The rate of detection of the primary lesions was compared first between SPECT and planar images then between SPECT and CT images. The rate of detection for each stage of disease according to the TNM classification was also analyzed.ResultsThe rate of detection of primary lesions was 50% with planar imaging and 69% with SPECT. And similarly, regarding the rate of detection of lymph node metastases, there was a significant difference between planar imaging and SPECT. The rate of detection of primary lesions was 70% for both CT and SPECT. At T stage, the rates of detection of primary lesions with each imaging technique were 11% with planar imaging and 39% with SPECT, and 22% with CT for stage T1.ConclusionsThis study revealed the marked superiority of SPECT images over planar images in terms of the ability to detect primary tumors and tumor metastasis to cervical lymph nodes. Furthermore, the primary T1 tumor detection rate of SPECT images was higher than that of CT images. On the basis of these results, the concomitant use of SPECT is highly recommended when Ga scintigraphy is performed to check for malignant head/neck tumors.

A case of cavernous hemangioma in which malignancy was preoperatively excluded by FDG-PET

A contrast-enhanced mass was revealed by computed tomography and magnetic resonance imaging in the left pelvic cavity of a 71-year-old man. Although the mass appeared to be a cavernous hemangioma, malignancy could not be ruled out. Abdominal angiography was performed but failed to rule out malignancy because it revealed vascular dislocation and encasement. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) was then performed, and suggested a benign tumor, with a standardized uptake value (SUV) of 1.7. Following this finding, because the tumor was large and rupture could not be ruled out, we decided to perform surgery. The resected tumor was a benign cavernous hemangioma, consistent with the result obtained by FDG-PET.

Detection of local residual tumor after laryngeal cancer treatment using FDG-PET

Objective: Fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) is sometimes used as a means of follow-up after diagnosis and treatment of cancers of the head and neck region. The present study was undertaken to evaluate the ability of FDG-PET to detect local residual tumor after treatment of laryngeal cancer.Methods: Thirty-six patients with laryngeal cancer underwent FDG-PET before and after initial treatment. Of these patients, 20 received FDG-PET before treatment and 28 received it after treatment. The relationship between standardized uptake values (SUV) and the presence or absence of local residual tumor was investigated by setting the cut-off value of the SUV using the receiver operating characteristics (ROC) curve.Results: When the pre-treatment SUV threshold for laryngeal cancer was set at 7.20, the detection of local residual tumor after treatment using FDG-PET had a sensitivity of 77.78%, specificity of 81.82%, false positive rate of 18.18%, false negative rate of 22.22%, accuracy of 80% and a p value of 0.02. When the post-treatment SUV threshold for the larynx was set at 3.35, the test had a sensitivity of 93.75%, specificity of 91.67%, false positive rate of 8.33%, false negative rate of 6.25%, accuracy of 92.86% and a p value of 0.0001.Conclusions: FDG-PET was found to be useful for determining the presence of local residual tumor after treatment of laryngeal cancer.