Rumi Nakashima

18F-fluorodeoxyglucose and 11C-acetate positron emission tomography are useful modalities for diagnosing the histologic type of thymoma

The objective of this study was to clarify the usefulness of positron emission tomography (PET) using18F‐fluorodeoxyglucose (FDG) and carbon 11‐labeled acetate (AC) for predicting the histologic types and tumor invasiveness of thymoma in a multicenter study.

Analysis of various malignant neoplasms detected by FDG-PET cancer screening program: based on a Japanese Nationwide Survey.

ObjectiveThe most distinctive feature of FDG-PET cancer screening program is the ability to find various kinds of malignant neoplasms in a single test. The aim of this survey is to clarify the range and frequency of various malignant neoplasms detected by FDG-PET cancer screening performed in Japan.Methods“FDG-PET cancer screening” was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. This survey was based on a questionnaire regarding FDG-PET cancer screening. We analyzed the situation of 9 less frequently found malignant neoplasms including malignant lymphoma, malignancy of head and neck, esophagus, hepatobiliary and gallbladder, pancreas, kidney, cervical and uterine, ovary, and bladder.ResultsThe detailed information of subjects with the suspected 9 kinds of malignant neoplasms mentioned above in the FDG-PET cancer screening program was studied in a total of 1,219 cases from 212 facilities. A statistical significance between PET/CT and PET was found in relative sensitivity and PPV for renal cell cancer. Malignant lymphoma was frequently of indolent type, suspected head and neck cancers had many false-positive results, and pancreatic cancer detected in this program was often in the advanced stage even in asymptomatic subjects. The recommendation of combined screening modality to PET or PET/CT was as follows: gastric endoscopy for assessing early esophageal cancer; abdominal ultrasound for screening hepatobiliary and gallbladder cancer; pelvic magnetic resonance imaging for assessing gynecological and pelvic cancers; and the CA125 blood test for screening ovarian cancer. Delayed image was helpful depending on the type of suspected malignant neoplasm.ConclusionWe analyzed various types of malignant neoplasms detected by the FDG-PET cancer screening program and presented recommended combination of examinations to cover FDG-PET and PET/CT.

Evaluation of Semiquantitative Assessments of Fluorodeoxyglucose Uptake on Positron Emission Tomography Scans for the Diagnosis of Pulmonary Malignancies 1 to 3 cm in Size

BACKGROUND To determine the optimal method of evaluating fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) for the diagnosis of pulmonary malignancies, the sensitivity and specificity of visual assessment and the several semiquantitative analyses were compared. METHODS Positron emission tomography data were analyzed for 130 pulmonary nodules from 1 to 3 cm in size (101 malignant and 29 benign nodules). The FDG uptake was measured by maximum standard uptake value (SUVmax), the contrast ratio (CR) of the SUV to the cerebellum (CR brain), and the CR of the SUV to the contralateral lung (CR lung). The CR lung was calculated from the SUV of the tumor (T) and that of the contralateral normal lung (N) and then was measured by two formulas, namely, T-N/T+N and T/N. RESULTS The sensitivities of both CR lung T-N/T+N and CR lung T/N were significantly higher than those of visual assessment, SUVmax, and CR brain (p = 0.01 to p < 0.001). No significant difference in sensitivity was observed between the CR lung T-N/T+N and CR lung T/N. Both CR lung T-N/T+N and CR lung T+N successfully imaged well-differentiated lung adenocarcinoma more frequently than the visual assessment, SUVmax, and CR brain (p = 0.002 to p < 0.001), whereas there were no significant differences of sensitivity among those five methods for the diagnosis of other histologic types of pulmonary malignancies. CONCLUSIONS The FDG uptake evaluated by the CR lung is superior to that evaluated using the visual assessment, SUVmax, and CR brain for the diagnosis of pulmonary malignancies, especially for well-differentiated lung adenocarcinoma. The simplified formula of CR lung with T/N can be used in place of that with T-N/T+N.

11C-Acetate can be Used in Place of 18F-Fluorodeoxyglucose for Positron Emission Tomography Imaging of Non-small Cell Lung Cancer with Higher Sensitivity for Well-Differentiated Adenocarcinoma

Objectives: Although positron emission tomography (PET) using 18F-fluorodeoxy-glucose (FDG) frequently gives false-negative results for slow-growing tumors, 11C-acetate (AC)-PET has been reported to be able to detect them. To determine the usefulness of AC-PET for imaging non-small cell lung cancers (NSCLCs), the sensitivity and specificity were compared between the AC-PET and FDG-PET with a multicenter study. Materials and Methods: A total of 284 pulmonary lesions (227 NSCLCs and 57 benign lesions) were examined using both AC-PET and FDG-PET before surgery at seven Japanese institutes. The AC- or FDG-uptake in each lesion were quantitatively measured using the contrast ratio of the standard uptake value between the lesions and the contralateral lung. Results: The sensitivity of AC-PET for diagnosing NSCLC was 0.71, which was significantly higher than the value of 0.57 obtained by FDG-PET (p < 0.001). No significant difference in the specificity was seen between AC- and FDG-PET. For the 146 well-differentiated adenocarcinomas, the sensitivity of AC-PET was 0.62, which was significantly higher than the value of 0.37 obtained by FDG-PET (p < 0.001). Of the 51 moderately- or poorly-differentiated adenocarcinomas and 30 nonadenocarcinomas, there was no significant difference of sensitivity between AC- and FDG-PET. Conclusions: AC-PET could be used in place of FDG-PET for imaging NSCLC, with higher sensitivity for well-differentiated adenocarcinoma compared with FDG-PET.

Correlation of Tc-99m GSA hepatic studies with biopsies in patients with chronic active hepatitis.

To determine whether scintigraphic findings of Tc-99m DTPA-galactosyl-HSA (GSA) correspond to histopathologic findings, Tc-99m GSA hepatic scintigraphy and biopsy were compared in 65 patients with chronic active hepatitis. After injecting 185 MBq of Tc-99m GSA, anterior images were obtained at 5 minutes and 15 minutes. Scintigrams were classified into three grades according to the extent of visualization of the cardiac blood pool on 5 minute and 15 minute images. Biopsies were subjectively graded for findings of necrosis and fibrosis. Scintigraphic grades on 5 minute images were correlated with hepatic necrosis and fibrosis and those on 15-minute images with hepatic fibrosis. Scintigraphic abnormalities of Tc-99m GSA correlated well with histopathologic abnormalities, especially with hepatic fibrosis and necrosis in patients with chronic active hepatitis.

Usefulness of Turbo-FLASH dynamic MR imaging of dissecting aneurysms of the thoracic aorta

AbstractPurpose: We attempted to determine whether Turbo-FLASH dynamic magnetic resonance imaging is clinically useful for the diagnosis of dissecting aneurysm of the thoracic aorta by differentiating slow flow from thrombus in the false lumen. Methods: Magnetic resonance imaging (MRI) was performed in ten patients using three different pulse sequences (spin echo, cine and turbo-FLASH dynamic MRI). The three imaging techniques were compared for their ability to demonstrate anatomical and hemodynamic abnormalities by visual assessment. Results: In all patients with thrombus in the false lumen, the thrombus was accurately differentiated from slow flow on contrast enhanced turbo-FLASH dynamic MRI, but only with difficulty on spin echo and cine MRI. Dynamic MRI was also useful for the evaluation of flow dynamics in the false lumen. Conclusion: Turbo-FLASH dynamic MRI is recommended for patients with dissecting aneurysm of the thoracic aorta, not definitely diagnosed by spin echo and cine MRI.

Quantitative renography with the organ volume method and interporative background subtraction technique

When quantification of renal activity is performed by planar imaging, many correction factors must be considered. To obtain quantitative renal images and renogram, we have examined our proposed method by using the organ volume for scatter, attenuation, and background activity, and the interporative background subtraction (IBS) technique in phantom and clinical studies. A renal phantom study was performed by varying the renal depth from 3 to 11 cm and the kidney-to-background activity concentration ratio from 5 to 80. Planar images were properly corrected for scatter, attenuation and background activity by our method and the corrected images were compared with the images obtained by the conventional method for the estimation of true renal activity. Clinical Tc-99m DTPA dynamic data for both a good and a poor renal function were also corrected by our method and volume-corrected renograms were obtained. For the phantom study, depth-independent images were obtained and these images gave a good estimation of the true count rate. In the clinical study, the conventional renogram was especially modified to allow for oversubtraction of background counts in the early phase (0–4 min). In conclusion, our proposed correction method can assess renal function qualitatively and quantitatively in both static and dynamic planar renal imaging.