Biomedical subjects

E Tsukamoto

Publications and source records attributed to E Tsukamoto.

At least 37 records · Page 2Linked to original sources

PubMed2000

A new dynamic myocardial phantom for the assessment of left ventricular function by gated single-photon emission tomography.

Gated myocardial perfusion single-photon emission tomography (SPET) has been used for the measurement of left ventricular (LV) function and validated by means of comparison with other imaging modalities. We have designed a new dynamic myocardial phantom in order to validate the LV function as assessed by the use of gated myocardial perfusion SPET. The phantom consists of two half-ellipsoids (an endocardial surface and an epicardial surface) and a thorax. The myocardial space is filled with a radioactive solution. The endocardial surface moves continuously towards and away from the epicardial surface in the longitudinal axis to vary the LV volume [143 ml at end-diastole (ED), 107 ml at end-systole (ES)] and thickness (apex 8 mm at ED and 26 mm at ES, midplane 8 mm). The mean values of wall motion (WM) for the apical midplane region and the basal midplane region were 5 mm and 2 mm, respectively. Gated myocardial SPET was performed during 8 and 16 intervals. These projection data sets were processed using a Butterworth filter with an order of 5 and a critical frequency of 0.34 cycles/cm. LV function was calculated using the quantitative gated SPET (QGS) algorithm. The LV function values estimated by gated SPET during 16 intervals [22% for ejection fraction (EF), 3.7 mm for WM of the apical midplane, 1.7 mm for WM of the basal midplane] closely resembled actual LV functions [25% for EF, 5 mm for WM of the apical midplane, 2 mm for WM of the basal midplane]. However, the estimated values during 8 intervals were smaller than those during 16 intervals (19% for EF, 3.3 mm for WM of the apical-midplane, 1.1 mm for WM of the basal-midplane). The estimated LV volumes closely correlated with the actual volumes (r=0.99 for 16 intervals, r=0.95 for 8 intervals). Utilizing this phantom, LV function estimated using gated myocardial SPET can be compared with actual values.

Diastole↗

PubMed2000

Comparison between segmental wall motion and wall thickening in patients with coronary artery disease using quantitative gated SPECT software.

This study was performed to evaluate regional wall motion (WM) and wall thickening (WT) using gated myocardial perfusion single photon emission computed tomography (SPECT) and to determine their similarity and disparity in patients with coronary artery disease (CAD). A total of 44 patients underwent 1 day stress/rest (MIBI) gated SPECT. Commercially available quantitative analysis of gated SPECT (QGS) software was used to generate 3D surface display and cine-mode SPECT display. Left ventricle was divided into nine segments to score WM and WT from 0 (no abnormality) to 4 (severe abnormality) by six independent observers. Finally a mean score was calculated for each segment from the scores of six observers. There was fairly good correlation between WM and WT of individual segments (r = 0.62, p < 0.0001). Concordance rate (IWM - WTI < 1) was 85%. A large difference between WM and WT (WM - WT > or = 2) was observed in 15 segments, including 12 segments with greater WM abnormalities and 3 segments with greater WT abnormalities (lateral and inferior walls). Greater WM abnormalities were most commonly observed in anteroseptal segments especially in post coronary artery bypass grafting (CABG) patients. In conclusion, WM and WT showed similarity on QGS studies. However, these two parameters may be determined separately in gated SPECT studies for comprehensive and robust evaluation of the functional status of myocardium. Analyses based on WM assessment alone may lead to erroneous results especially in septal regions.

Aged↗

PubMed2000

Early detection of bone marrow involvement in extramedullary plasmacytoma by whole-body F-18 FDG positron emission tomography.

The utility of positron emission tomography (PET) with the glucose analog 2-deoxy-2-[F-18] fluoro-D-glucose (F-18 FDG) in plasmacytoma has not been well evaluated. The authors report a case of extramedullary plasmacytoma (EMP) in which whole-body F-18 FDG PET was useful in the early detection of bone marrow involvement. A 34-year-old woman had EMP without histologic or radiologic evidence of bone lesions. However, the early phase of bone marrow involvement was considered because of spotty accumulation shown by F-18 FDG PET. A follow-up F-18 FDG PET study after radiotherapy showed intense multifocal accumulation in the bone marrow, which was confirmed on bone marrow aspiration as abnormal proliferation of plasma cells. Whole-body F-18 FDG PET has the potential to detect the early phase of bone marrow involvement in patients with EMP.

Adult↗

PubMed2000

Improvement in fatty acid utilization in relation to a change in left ventricular hypertrophy in spontaneously hypertensive rats.

Although fatty acid metabolism is reportedly impaired in myocardial hypertrophy, it is unclear whether the antihypertensive drugs are associated with improved fatty acid metabolism. In order to evaluate the effects of antihypertensive drugs on fatty acid metabolism and myocardial perfusion, the simultaneous uptake of iodine-125(125I)-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and thallium-201 (Tl) were measured in 3 groups of rats: (1) spontaneously hypertensive rats (SHR) without treatment (SHR-N), (2) SHR chronically treated with captopril (SHR-C), and (3) SHR chronically treated with hydralazine (SHR-H). Captopril and hydralazine were administered to their respective groups for 3 weeks from 12 weeks of age. The hearts were removed 10 min after simultaneous intravenous injections of BMIPP and Tl and the 125I and 201Tl counts were measured to calculate the uptake ratio. The systolic blood pressure (SBP) in SHR-N was 222+/-10 mm Hg, whereas the SHR-C and SHR-H groups showed significant SBP reduction (156+/-11, and 158+/-10 mm Hg, respectively) (p<0.01 each). The heart/bodyweight ratio was significantly lower in SHR-C (2.48+/-0.09) than in SHR-N (2.74+/-0.11) (p<0.05). However, there was no significant difference in the heart/bodyweight ratio between SHR-N and SHR-H (2.65+/-0.09). The ratio of BMIPP uptake to Tl uptake (BMIPP/Tl) was significantly higher in SHR-C (0.71+/-0.13) than in SHR-N (0.50+/-0.09) (p<0.05). However, BMIPP/Tl in SHR-H (0.53+/-0.09) was similar to that in SHR-N. These results suggest that captopril improves fatty acid metabolism in the hypertrophied ventricle in SHR. The metabolic alterations may improve with left ventricular hypertrophy regression but are not effected by the reduction of blood pressure only.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

[Single-blood-sample method for the determination of glomerular filtration rate using 99mTc-DTPA in Japanese].

The study was aimed to evaluate glomerular filtration rate with 99mTc-DTPA by means of a single-plasma-sample method in Japanese. Three were 50 patients (29 males and 21 females, age range being 25 to 91 years) with diabetes mellitus of various degree of the renal function. 99mTc-DTPA of 300 MBq/2 ml that was prepared in our hospital was injected. Dynamic renal scintigraphy was carried out and 10 blood samples were taken after the injection. Blood clearance (true GFR) of 99mTc-DTPA was determined from plasma concentration which was fitted to the biexponential curve by a non-linear least squares method. Plasma concentration (ml/min/1.73 m2) after 75 min-post injection showed very higher linear regression and linear correlation with true GFR than 0.900. The best linear regression and linear correlation was observed with 180 min-sample (r = 0.989). As general, the following equation was obtained; Y = A + Bln(X), A = 436.1217 - 3.45817t + 0.01205t2 - 0.000015t3, B = -212.601 + 1.42518t - 0.04834t2 + 0.0000062t3, X = plasma concentration at sampling time t (%ID/L/1.73 m2), t = sampling time from 75 to 300 min (r > 0.900). This is the new equation of single-plasma-sample method for the determination of GFR using 99mTc-DTPA for Japanese. The clinical feasibility should be accessed in a field of a nuclear medicine practice.

Adult↗

PubMed2000

The role of fatty acids in cardiac imaging.

Nuclear medicine has progressed in conjunction with the recent growth of molecular medicine. Myocardial energy metabolism has long been investigated in experimental models with the use of Langendorff's method or coronary sinus blood sampling. However, the introduction of a variety of radiopharmaceutical agents has now made possible easy visualization of myocardial energy metabolism in vivo with nuclear medicine techniques.

Animals↗

PubMed1999

Technetium-99m-tetrofosmin imaging of lung cancer: relationship with histopathology.

Tc-99m-tetrofosmin is an agent to delineate cancer. To elucidate the usefulness of Tc-99m-tetrofosmin scintigraphy, we analyzed the relationship between the uptake of Tc-99m-tetrofosmin and histopathology in patients with lung cancer. SPECT studies were conducted twice: 15 minutes (early scan), and 60 minutes (delayed scan), after intravenous injection of 740 MBq Tc-99m-tetrofosmin. We calculated the retention index in order to evaluate the degree of Tc-99m-tetrofosmin retention in the primary tumor. The retention indices were significantly lower in squamous cell carcinoma than those of small cell carcinoma or adenocarcinoma. As the retention indices of Tc-99m-tetrofosmin were different in each histopathology, the index might play a part as a tumor marker of lung cancer.

Adenocarcinoma↗

PubMed1999

Validity of 99mTc-DMSA renal uptake by planar posterior-view method in children.

Renal uptake of 99mTc-DMSA has been quantified by various methods. The aim of this study is to obtain a normal value for 99mTc-DMSA renal uptake calculated by the posterior view method and age variation, and to assess its clinical validity. Scintigrams of 238 children (0-12 years) with 99mTc-DMSA were reviewed. All the children had a clinical history of primary vesicoureteral reflux and/or neurogenic bladder, ureteral or urethral anomalies. Their kidneys were divided into two groups, "normal" and "abnormal" according to their scintigraphic findings and split renal functions. Percent renal uptake per injected dose (% RU) was quantitated from planar images at 2 hours after injection of an age-adjusted dose (26-95 MBq) of 99mTc-DMSA. Calculated total % RU, individual % RU of the right and left kidneys (mean +/- sd) in patients with normal kidneys were 40.7 +/- 5.0%, 20.2 +/- 3.0%, 20.4 +/- 2.7%, respectively. There was no significant correlation between % RU and age (r = 0.231). Longitudinal variation in the % RU in 9 patients ranged from 1.2% to 18%. Our conventional method for quantifyng % RU is simple, practical and feasible in routine clinical practice, especially for children under follow up.

Adolescent↗

PubMed1999

Future aspects of BMIPP.

Iodinated fatty acid compounds have an important role in early detection of myocardial abnormalities and provide insights into pathological states in the heart. Among them, 15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid (BMIPP) has been most widely used providing excellent images of the left ventricular myocardium due to high myocardial uptake and long retention. The previous chapters have focused on the basic characters and clinical applications of this compound. However, the precise mechanisms of myocardial kinetics should be further investigated under various conditions. Most of the studies showed reduced BMIPP uptake relative to perfusion in a variety of myocardial disorders, whereas an increase in BMIPP uptake relative to perfusion is often reported. The potential mechanisms of such conflicting results are discussed, but basic studies should be performed to clarify such results in detail. There are a number of clinical values of this compound. Since alteration of fatty acid is observed in the repetitive ischemia, BMIPP can be used for detecting severe ischemic episodes. The concept of 'ischemic memory' imaging can be applied for patients with unstable or vasospastic angina at rest and for those with acute myocardial infarction with successful revascularization to identify the risk area. The discordant decrease in BMIPP uptake relative to perfusion is often seen in ischemic but viable myocardium, and therefore, the combined imaging of BMIPP and perfusion can be used for assessment of tissue viability. Furthermore, abnormal BMIPP uptake is most often observed in hypertrophic cardiomyopathy, and thus, this compound can be used for an early detection and differential diagnosis of the cardiomyopathy. Although BMIPP imaging seems to be quite promising in many fields, the number of patient data remain limited. In this respect, a multicenter study with a vast majority of patients is warranted to confirm these important values of BMIPP. In addition, this attractive tracer should be available all over the world to confirm its clinical value in the near future.

Cardiomyopathies↗

PubMed1999

Hypofluorescent spots on indocyanine green angiography at the recovery stage in multiple evanescent white dot syndrome.

PURPOSE: To evaluate the fundus lesions in a young woman. METHODS: Visual function, ophthalmoscopy, electrophysiology, fluorescein angiography, and indocyanine green angiography were performed. RESULTS: A 24-year-old woman had decreased visual acuity (0.2), granularity in the macula, and multiple yellow-white patches in the fundus, reduced a wave on electroretinography, hyperfluorescence on fluorescein angiography, and hypofluorescence on indocyanine green angiography in the left eye. When visual acuity improved to 1.0, the white dots disappeared ophthalmoscopically, and fluorescein angiography showed normal findings. Hypofluorescent spots were found, however, on indocyanine green angiography. CONCLUSION: It is possible that signs of multiple evanescent white dot syndrome may remain longer during examination by indocyanine green angiography than by visual function, ophthalmoscopy, or fluorescein angiography.

Adult↗

PubMed1999

Endoscopic ventriculocystocisternostomy of a quadrigeminal cistern arachnoid cyst. Case report.

The authors present the case of an elderly patient with a quadrigeminal arachnoid cyst who was successfully treated with endoscopic fenestration through the posterior wall of the third ventricle via the anterior horn of the lateral ventricle. This 71-year-old man suffered from progressive gait instability and disorientation. Radiological examination revealed hydrocephalus caused by a quadrigeminal arachnoid cyst. The patient underwent endoscopic fenestration of the quadrigeminal cistern arachnoid cyst and third ventriculostomy via one burr hole placed at the coronal suture. This method is less invasive and is effective for quadrigeminal cistern arachnoid cyst and accompanying hydrocephalus.

Aged↗

PubMed1999

[Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software].

Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r = 0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemic area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function.

Electrocardiography↗

PubMed1999

Relationship among 201T1 uptake, nuclear DNA content and clinical behavior in metastatic thyroid carcinoma.

UNLABELLED: A prospective study of 201TI uptake was performed to compare 201TI uptake with nuclear deoxyribonucleic acid (DNA) content and clinical behavior of tumors in metastatic thyroid carcinoma and to assess the significance of 201TI uptake in evaluating clinical characteristics of thyroid carcinoma. METHODS: Fifty-six patients with metastases of differentiated thyroid carcinoma had 201TI scintigraphy. Grade of 201TI uptake was semiquantitatively assessed according to tumor-to-background ratio on 2-h late scan. Nuclear DNA content was analyzed within 3 wk of 201TI study by flow cytometry using biopsy material and was classified as diploidy or aneuploidy. Patients were followed up to examine incidence of tumor growth and/or anaplastic transformation. RESULTS: DNA content was diploidy in 48 patients and aneuploidy in 8 patients. 201TI uptake in the DNA-aneuploid group (2.61 +/- 0.29) was significantly higher than that in the DNA-diploid group (1.82 +/- 0.35, P < 0.01 for both groups). Tumor growth was observed in all patients with DNA aneuploidy but in only 5 of 48 patients with DNA diploidy (P < 0.01). Anaplastic transformation was observed in 3 patients in the DNA-aneuploid group but in none of the patients in the DNA-diploid group. CONCLUSION: High 201TI uptake indicates greater incidence of abnormal DNA content with aggressive clinical behavior of metastatic tumors. Thus, 201TI scintigraphy may be useful in characterizing metastatic thyroid carcinoma and in identifying those patients with poorer prognoses.

Adenocarcinoma, Follicular↗

PubMed1999

[Synthesis of 18F-FDG with FDG MicroLab system: basic studies for clinical application].

We synthesized 18F-FDG by using an automated synthetic apparatus "FDG MicroLab" (GE Medical Systems) which produces 18F-FDG by a solid phase 18F-fluorination. Its quality and reproducibility were evaluated in order to assess feasibility of the apparatus for routine clinical production of 18F-FDG. For 5 consecutive 18F-FDG synthesis, target irradiation was carried out at 15 microA for 60 min. 18F-FDG was obtained in 50 min after EOB with an end-of-synthesis yield of 9.34 +/- 1.06 GBq. Radiochemical yield and radiochemical purity were 47 +/- 3% (decay corrected) and 98.0 +/- 0.5%, respectively. Other several quality control parameters tested conformed with "Standards of Compounds Labeled with Positron Nuclides" (RADIOISOTOPES, 44, 1995). Thus, the automated synthetic apparatus "FDG MicroLab" has proven to stably produce 18F-FDG with high yield and high purity. The apparatus is feasible for routine clinical production of 18F-FDG.

Chemical Phenomena↗

PubMed1999

[Visualization of normal organs in whole-body FDG-PET imaging].

It is important to know FDG accumulation in the normal distributions for interpreting whole-body PET imaging for tumor detection. Twenty-eight normal subjects were studied with whole-body PET imaging and were examined the intensity of FDG uptake in major organs and the factors which caused it's variety. Emission images were acquired and images were reconstructed without attenuation correction. The intensity of FDG uptake was classified into 4 grades visually. No accumulation was found in the thyroid, the esophagus and the spleen. The oral cavity, the liver, the stomach, and the colon were visualized in all subjects. The laryngeal muscle, the cervical muscle, and the heart accumulated FDG with various grade from 1 to 4 grades. No association was found between the intensity of uptake in the organs and volunteer's age. The fasting time was shorter in volunteers whose heart showed "high" grade than those showed less accumulation (p < 0.05). Serum concentration of free fatty acid was significantly lower in them, too (p < 0.05). Various FDG uptake was observed in many organs, especially the laryngeal muscle, the cervical muscle, and the heart. In our study, there was no facter which caused FDG uptake in organs except for the fasting time and the value of free fatty acid in the heart. Such analysis of whole-body FDG distributions in the normal subjects is valuable for tumor detection with FDG-PET.

Adult↗

PubMed1998

Use of 123I-BMIPP single-photon emission tomography to estimate areas at risk following successful revascularization in patients with acute myocardial infarction.

Previous studies have indicated that iodine-123 labelled beta-methyliodophenyl pentadecanoic acid (BMIPP), an iodinated fatty acid analogue, can identify persistent alteration of fatty acid metabolism after restoration of blood flow. To assess whether fatty acid imaging can delineate areas at risk following successful revascularization in patients with acute myocardial infarction (AMI), BMIPP findings at 1 week post AMI were compared with perfusion imaging before and after revascularization therapy. Sixty-five patients with AMI underwent technetium-99m tetrofosmin single-photon emission tomography (SPET) before m (TF0) and 1 week (TF1) after successful revascularization therapy. BMIPP SPET was also performed under a fasting state at 1 week (BM1) post AMI. The extent scores were calculated from the defect scores in 20 segments. The BM1 score (7.7 +/- 3.9) was similar to the TF0 score (8.8 +/- 4.2) (r = 0.86, P < 0.0001), but significantly higher than the TF1 score (5.8 +/- 3.9) (P < 0.0001). A significant correlation was observed between the BM1 score and TF0 score (r = 0.86, P < 0.0001). Among a total of 1300 segments, the BM1 score was identical to the TF0 score in 1156 (88.9%). These data indicate that the ability of BMIPP imaging at 1 week post AMI to identify areas at risk is similar to that of tetrofosmin perfusion imaging in the acute phase. This may be due to the impairment of fatty acid uptake and metabolism reflecting prior severe ischaemic insult which persists at least 1 week after recovery of perfusion in the acute phase of AMI.

Acute Disease↗

PubMed1998

Hypoglossal nerve paresis caused by spontaneous dissection of kinked internal carotid artery--case report.

A 54-year-old male presented with pure hypoglossal nerve paresis. Angiography and magnetic resonance (MR) imaging showed the characteristic findings of left internal carotid artery (ICA) dissection. He received aspirin and his symptoms gradually disappeared. Repeat angiography and MR imaging showed that the lesion had completely disappeared. This case supports the hypothesis that hypoglossal nerve paresis is due to nerve stretching and compression by intramural hematoma of the dissected ipsilateral ICA, and severe tortuosity of the ICA may be a related phenomenon.

Aortic Dissection↗

PubMed1998

Accumulation of iodine-131-iodocholesterol in renal cell carcinoma adrenal metastases.

Adrenocortical scintigraphy is a useful technique for differentiating between types of nonhyperfunctioning adrenal masses. Metastatic tumors do not normally accumulate radioiodocholesterol and show discordant uptake on scintigrams. We present two patients who showed accumulation of 131I-6beta-iodomethyl-19-norcholesterol (NP59) in the adrenal metastases from renal cell carcinoma. In one patient with bilateral adrenal metastases, accumulation in the primary tumor as well as adrenal metastases was demonstrated. The adrenal metastases in both patients were resected and were histologically proven to be metastases from clear-cell renal carcinoma. Accumulation of NP59 in metastatic adrenal tumors, although a very rare finding, suggests a pitfall in the differential diagnosis of adrenal cortical tumors.

19-Iodocholesterol↗