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Biomedical subjects

T Iinuma

Publications and source records attributed to T Iinuma.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Measurement of arterial tracer concentrations from cardiac PET images.

OBJECTIVE: Cardiac PET imaging offers the potential capability for the noninvasive measurement of arterial input function. This capability is somewhat limited, however, because of partial volume and spillover effects. The purpose of this study was to validate arterial tracer concentration measurements using PET images by assigning a region of interest (ROI) to the left ventricle, left atrium (LA), and ascending aorta. MATERIALS AND METHODS: We selected [11C]CO and [13N]ammonia as tracers, because the activity of [11C]CO is primarily in the blood pool and that of [13N]ammonia primarily in myocardial tissue. Six [11C]CO and 11 [13N]ammonia PET scans were obtained in 17 subjects. Arterial tracer concentrations determined by PET were compared with those measured by well counting of arterial blood sampling obtained at the midpoint of each image acquisition. RESULTS: Arterial tracer concentrations as determined by LA-PET imaging correlated closely with those measured by blood sampling (r = 0.996, slope = 1.00 for [11C]CO; r = 0.841, slope = 0.974 for [13N]ammonia). Partial volume and spillover effects were minimized by assigning an ROI to the LA. CONCLUSION: Arterial tracer concentrations can be measured noninvasively with cardiac PET.

Adolescent↗
PubMedDate not supplied

Measurements of the effect of dipyridamole on regional myocardial blood flow with positron emission tomography and the first-pass flow model.

We assessed percent changes of regional myocardial blood flow (RMBF) after infusion of dipyridamole (0.56 mg/kg) with dynamic N-13 ammonia PET and the first-pass flow model. Positron emission tomography (PET) was performed at rest and after infusion of dipyridamole in 17 participants [five normal subjects, five patients with hypertrophic cardiomyopathy (HCM), and seven patients with coronary artery disease]. Dipyridamole increased RMBF 126 +/- 69% (mean +/- SD) in normal subjects and 55 +/- 43% in the patients with HCM. In the cases of coronary artery disease, the percent changes of RMBF were +19 +/- 19% in ischemic areas and +76 +/- 23% in nonischemic areas. These results demonstrate that N-13 ammonia dynamic PET study is useful in assessing the percent changes of RMBF induced by dipyridamole infusion.

Adult↗
PubMedDate not supplied

Ultrasonography of small hepatic tumors.

The differential accuracy of ultrasonographic examinations of small hepatic tumours was analyzed by receiver-operating characteristics. Using only one image of a single hepatic tumor under 3 cm in diameter as revealed by real-time scanner, the readers were requested to select one out of five diagnoses (hepatocellular carcinoma, metastatic tumor, cavernous hemangioma, cyst, or miscellaneous) and to choose the credibility from five levels of confidence. The averaged diagnostic accuracy was 68% in hepatocellular carcinoma, 70% in metastatic tumor, and 77% in cavernous hemangioma. Hepatic tumors were classified retrospectively into eight ultrasonographic patterns, based on mutual consent. The mosaic and hypoechoic patterns were relatively characteristic of hepatocellular carcinoma (91% and 92% respectively). Except for these two patterns, ultrasonographic findings in small liver tumors were nonspecific, including frequently reported hyperechoic pattern for cavernous hemangioma.

Carcinoma, Hepatocellular↗