Dual-time-point 18F-FDG PET for the evaluation of gallbladder carcinoma.

UNLABELLED: Conventional imaging techniques such as ultrasonography, CT, and MRI are able to detect gallbladder abnormalities but are not always able to differentiate a malignancy from other disease processes such as cholecystitis. The purpose of the present study was to evaluate the efficacy of dual-time-point (18)F-FDG PET for differentiating malignant from benign gallbladder disease. METHODS: The study evaluated 32 patients who were suspected of having gallbladder tumors. (18)F-FDG PET (whole body) was performed at 62 +/- 8 min (early) after (18)F-FDG injection and was repeated 146 +/- 14 min (delayed) after injection only in the abdominal region. We evaluated the (18)F-FDG uptake both visually and semiquantitatively. Semiquantitative analysis using the standardized uptake value (SUV) was performed for both early and delayed images (SUV(early) and SUV(delayed), respectively). The retention index (RI) was calculated according to the equation (SUV(delayed) - SUV(early)) x 100/SUV(early). The tumor-to-liver ratio was also calculated. RESULTS: The final diagnosis was gallbladder carcinoma in 23 patients and benign disease in 9 patients. For visual analysis of gallbladder carcinoma, delayed (18)F-FDG PET images improved the specificity of diagnosis in 2 patients. When an SUV(early) of 4.5, SUV(delayed) of 2.9, and RI of -8 were chosen as arbitrary cutoffs for differentiating between malignant and benign conditions, sensitivity increased from 82.6% to 95.7% and 100% for delayed imaging and combined early and delayed imaging (i.e., RI), respectively. With the same criteria, specificity decreased from 55.6% to 44.4% for delayed imaging and combined early and delayed imaging, respectively. The specificity of (18)F-FDG PET improved to 80% in the group with a normal level of C-reactive protein (CRP) and decreased to 0% in the group with an elevated CRP level. For gallbladder carcinoma, both SUV and tumor-to-liver ratios derived from delayed images were significantly higher than the ratios derived from early images (P < 0.0001). CONCLUSION: Delayed (18)F-FDG PET is more helpful than early (18)F-FDG PET for evaluating malignant lesions because of increased lesion uptake and increased lesion-to-background contrast. However, the diagnostic performance of (18)F-FDG PET depends on CRP levels.

Comparative evaluation of 18F-FDG PET and 67Ga scintigraphy in patients with sarcoidosis.

UNLABELLED: 67Ga scintigraphy has been used for years in sarcoidosis for diagnosis and the extent of the disease. However, little information is available on the comparison of 18F-FDG PET and 67Ga scintigraphy in the assessment of sarcoidosis. The purpose of this study was to compare the uptake of 18F-FDG and 67Ga in the evaluation of pulmonary and extrapulmonary involvement in patients with sarcoidosis. METHODS: Eighteen patients with sarcoidosis were examined. 18F-FDG PET was performed at 1 h after injection of 185-200 MBq 18F-FDG. 67Ga whole-body planar and thoracic SPECT images were acquired 72 h after injection of 111 MBq 67Ga. We evaluated 18F-FDG and 67Ga uptake visually and semiquantitatively using standardized uptake values (SUVs) and the ratio of lesion to normal lumbar spine (L/N ratio), respectively. The presence of pulmonary and extrapulmonary lesions was evaluated histopathologically or by the radiologic findings. RESULTS: Five patients had only pulmonary lesions, 12 patients had both pulmonary and extrapulmonary lesions, and 1 patient had only an extrapulmonary lesion. Both 67Ga planar and SPECT images detected 17 of 21 (81%) clinically observed pulmonary sites. The mean +/- SD of the L/N ratio was 1.97 +/- 1.09. 67Ga planar images detected 15 of 31 (48%) clinically observed extrapulmonary sites. The mean +/- SD of the L/N ratio was 1.17 +/- 0.33. 18F-FDG PET detected all 21 (100%) clinically observed pulmonary sites. The mean +/- SD of the SUV was 7.40 +/- 2.48. 18F-FDG PET detected 28 of 31 (90%) clinically observed extrapulmonary sites. The mean +/- SD of the SUV was 5.90 +/- 2.75. CONCLUSION: The results of this clinical study suggest that 18F-FDG PET can detect pulmonary lesions to a similar degree as 67Ga scintigraphy. However, 18F-FDG PET appears to be more accurate and contributes to a better evaluation of extrapulmonary involvement in sarcoidosis patients.

CT assessment of pulmonary emphysema using teleradiology.

PURPOSE: The present study assessed the usefulness of CT for diagnosis of pulmonary emphysema (PE) using teleradiology. METHODS: We reviewed 95 cases (56 men and 39 women, ranging in age from 18 to 89 years) who had undergone CT examination between June 2002 and January 2003. CT images were transmitted via ISDN by DICOM to our hospital, and displayed in 4-image and 1-image format for reading on an image viewer. RESULTS: In 72 of the total 95 cases, both 1-image and 4-image displays were normal, and no PE was detected. Of the remaining 23 patients, PE was found in 22 on 4-image display and in all 23 on 1-image display. The same grade and subtype were observed on 4-image and 1-image displays in 19 cases. On the other hand, difference in diagnosis between the two types of display was obtained in four cases, in which mild low attenuation areas (LAAs) such as grade 1 or grade 2 centrilobular emphysema were found on the 1-image display but not seen on the 4-image display. CONCLUSIONS: The diagnosis of PE can be made by CT examination using teleradiology even in cases of mild lesions, when, for example, LAAs were found on the 1-image display but not seen on the other one. Therefore, teleradiology enables rapid diagnosis even in medical institutions where no expert chest radiologist is present.

Ga-67 scintigraphy in patients with breast lymphoma.

PURPOSE: The authors studied the utility of Ga-67 citrate scintigraphy in patients with breast lymphoma. METHODS: Seven patients with histologically proved breast lymphoma were examined. In three patients, both breasts were involved, and all patients had rapidly growing breast masses. Planar and SPECT images were obtained 72 hours after injection of Ga-67. RESULTS: Ga-67 scintigraphy showed intense accumulation in all lymphomas. SPECT images provided better contrast than did planar images. In one of the seven patients, the axilla and mediastinum were also involved. In six of the seven patients, Ga-67 scintigraphy was also performed after treatment and showed the disappearance of Ga-67 accumulation. In one patient with local recurrence and lung involvement, abnormal accumulation was depicted on follow-up Ga-67 scintigraphy. CONCLUSIONS: Ga-67 scintigraphy was helpful to confirm the diagnosis and the systemic extent of lymphoma and to evaluate the therapeutic effect during follow-up in patients with breast lymphoma.