Biomedical subjects

N Tonami

Publications and source records attributed to N Tonami.

At least 73 records · Page 4Linked to original sources

PubMed1999

201Tl SPET in the differential diagnosis of brain tumours.

The aims of this study were to assess the utility of 201Tl single photon emission tomography (SPET) in the differential diagnosis of brain tumours and to elucidate the relationship between 201Tl tumour uptake and degree of contrast-enhancement on magnetic resonance imaging (MRI). Early (15 min) and delayed (3 h) 201Tl SPET imaging and T1-weighted MRI were performed before and after Gd-DTPA enhancement in 101 (41 malignant and 60 benign) untreated brain tumours. The 201Tl uptake ratio (tumour-to-normal brain count ratio) for both the early and delayed SPET studies and the retention index (the ratio of delayed to early 201Tl uptake) were calculated. Malignant tumours were separated from benign tumours with 87% accuracy based on the assumption that tumours with a 201Tl retention index < 0.7 or no abnormal uptake are benign. Meningiomas and pituitary adenomas were differentiated from other benign tumours by their characteristic pattern on SPET. The degree of contrast-enhancement of the tumour on MRI was concordant with the early 201Tl uptake ratio for most histological types. However, schwannomas and cavernous haemangiomas showed a low 201Tl uptake ratio in spite of a high degree of contrast-enhancement on MRI. In conclusion, 201Tl SPET provides additional information that helps in the differential diagnosis of brain tumours.

Adenoma↗

PubMed1999

[Assessment of ECG-gated myocardial SPECT analysis program with cardiac phantom and clinical data].

PURPOSES: ECG-gated myocardial SPECT program (QGS) is coming into wide use. This program permits measurement of end-diastolic volume (EDV), and end-systolic volume (ESV) and ejection fraction (EF) by automatic detection of myocardial edges. We assessed the reproducibility, accuracy, factors that affect the measurement of these indices using a cardiac phantom and clinical data. METHODS: In the phantom study, we evaluated the effects of ventricular volume, location, absorption, acquisition time, enlarged acquisition and pre-filter on the calculated indices. In the clinical study using 99mTc-MIBI, reproducibility between 2 observers, comparison with left ventriculography and effects of pre-filter were assessed. In clinical cases of 201TI and 123I-BMIPP, left ventricular volume and EF were also analyzed by QGS with various pre-filters. RESULTS: Although the true phantom volumes (y) and calculated volumes (x) showed an excellent linear correlation (y = 0.94x - 13.8, r = 0.999), calculated volumes were significantly under-estimated by 14.5-33.8%. An absorbent material around the phantom caused reduction in calculated volumes by 4.1-9.1%. Duration of acquisition times, 3 to 60 seconds per projection, did not influence the calculation of the parameters. With enlarged data collection, calculated volume (37 ml) was larger than that of normal acquisition (33 ml). When the cut-off frequency of Butterworth filter was changed, these indices of volume and EF were almost stable over 0.41 cycle/cm. There was an excellent correlation in intra-observer measurements for EDV (r = 0.998, p < 0.0001), ESV (r = 0.998, p < 0.0001) and EF (r = 0.995, p < 0.0001). In comparison with left ventriculography, correlation of parameters was good in ESV (r = 0.91, p < 0.0001), EF (r = 0.88, p < 0.0001), but was fair in EDV (r = 0.78, p < 0.0001). The QGS program underestimated EDV, ESV and EF. CONCLUSION: QGS program with gated SPECT is useful to calculate relative volume and EF. However, to calculate absolute values, we should understand the various factors that affect the result of QGS.

Aged↗

PubMed1999

Multiple myeloma evaluated with 201Tl scintigraphy compared with bone scintigraphy.

UNLABELLED: The purpose of this study was to investigate the clinical usefulness of 201Tl chloride scintigraphy in the diagnostic evaluation of 20 patients with multiple myeloma (19/20 patients) or extramedullary plasmacytoma (1/20 patients) in comparison with bone scintigraphy. METHODS: Both 201Tl and bone scintigraphy were performed to obtain planar images on the same instrument. RESULTS: 201Tl scintigraphy showed increased uptake in 15 of 20 patients (75%) and was negative in 5 of 20 patients (25%). In addition, 201Tl scintigraphy of multiple myeloma was more useful in detecting the lesions in 11 of 17 patients and less useful in 6 of 17 patients than bone scintigraphy. CONCLUSION: The combination of 201Tl and bone scintigraphy, compared with bone scintigraphy alone, shows promise in more accurately diagnosing multiple myeloma.

Bone Neoplasms↗

PubMed1999

[Internal radiation therapy for malignant neoplasm].

Internal radiation therapy selectively targets beta- or alpha-emitting radionuclides to the area of the tumor tissue, and is therefore capable of treating disease regardless of the location and number of foci. The biological effect of internal radiation therapy is thought to be different from that of conventional external beam radiation. Thyroid cancer: The local recurrence and metastatic lesions from differentiated thyroid cancers can be controlled with 131I administration. Even though the patient does not have macroscopic disease, 131I is also utilized for thyroid remnant ablation in locally advanced cases. Recently, the maximum tolerable dose can be calculated based on the dosimetry of each patient, and safely administered. The therapeutic effect of this method is superior to the fixed dose method. 131I-MIBG: 131I-MIBG is taken up by sympathetic neurons as well as a group of tumors originating in the neural crest, especially phecromocytomas and neuroblastomas. The various symptoms caused by the hypersecretions of hormone-producing tumors can be improved. Pain palliation of bone metastases: Pain palliation using 89Sr is a very promising option in treating patients with painful bone metastases. The pain palliation mechanism of 89Sr is different from other drugs; therefore, complimentary usage is reasonable. The symptomatical improvement can last for several months, thus helping to maintain the quality of life of the patient.

3-Iodobenzylguanidine↗

PubMed1999

[Assessment of regional myocardial function by ECG-gated myocardial SPECT].

PURPOSES: Regional myocardial functional parameters were assessed by ECG-gated myocardial SPECT analysis in normal subjects and ischemic heart diseases. METHODS: Normal subjects (13 male and 10 female) and 51 patients with chronic ischemic heart disease underwent ECG-gated myocardial SPECT. A dose of 740 MBq of 99mTc-MIBI was injected at rest, and gated SPECT was performed 60 min later. Wall motion (WM) and systolic wall thickening (WT), % tracer uptake were evaluated by quantitative gated SPECT program (QGS). Regional parameters were obtained in the 16 segments based on the functional polar map. In the normal group, standard values were evaluated in the lateral, septal, anterior and inferior regions both in male and female subjects. In the ischemic heart disease group, sensitivity and specificity of these parameters were assessed in each segment. To estimate the ability of WM and WT in detecting regional dysfunction, decreased perfusion area, which was defined as < mean - 2SD by the normal profile, was used as a standard. The receiver operating characteristics (ROC) area analysis was also performed. RESULT: In the normal profile, % tracer uptake was decreased in the anterior segments of female group, no significant difference was observed between male and female in WM and WT. WM was decreased in the septum and increased in the lateral segment. WT didn't show any difference regional difference. Sensitivity and specificity of WM were 56%/91% in the anterior, 0%/100% in the septum, 43%/87% in the inferior, 31%/85% in the lateral. WT were 67%/93% in the septum, 67%/79% in the inferior, and 59%/81% in the septum. The area under ROC curve was WM 0.63, WT 0.85 (p < 0.005 between WM and WT) in the septum, in inferior WM 0.77, WT 0.80 (p = 0.57), in anterior WM 0.86, WT 0.87 (p = 0.095), in lateral WM 0.68, WT 0.78 (p = 0.037). CONCLUSION: In normal profile, the % tracer uptake in the anterior wall decreased in females, but WM and WT did not show significant difference in each region affected this influence. The septal WM was decreased in the normal profile and ability to diagnose regional function was also decreased compared with WT. Thus, we can conclude that WT is preferable for detecting septal functional abnormality.

Aged↗

PubMed1999

Preoperative assessment of residual hepatic functional reserve using 99mTc-DTPA-galactosyl-human serum albumin dynamic SPECT.

UNLABELLED: Preoperative assessment of residual hepatic functional reserve offers important strategic information for hepatic resection. To predict the postoperative residual liver function, we assessed the value of hepatic 99mTc-diethylenetriamine pentaacetic acid-galactosyl-human serum albumin (99mTc-GSA) clearance estimated by dynamic SPECT analysis. METHODS: We investigated 114 consecutive patients with liver disease, including 55 hepatectomy cases. One minute after injection of 185 MBq 99mTc-GSA, 15 serial dynamic SPECT images were obtained every minute. The initial five sets of SPECT images were analyzed by Patlak plot to estimate the sequential initial hepatic 99mTc-GSA clearance (mL/min) as an index of hepatic function. The sum of hepatic 99mTc-GSA clearance of the segments immune from resection was categorized as predicted residual 99mTC-GSA clearance. In the hepatectomy cases, scintigraphy was performed before and 37 +/- 10 d after the operation. RESULTS: Good correlation was observed between the total hepatic 99mTc-GSA clearance and conventional hepatic function tests: plasma retention rate of iodocyanine green (ICG) at 15 min (ICG R15), r = -0.600, P < 0.0001, n = 94; plasma disappearance rate of ICG (K ICG), r = 0.670, P < 0.0001, n = 83; cholinesterase, r = 0.539, P < 0.0001, n = 121; serum albumin, r = 0.421, P = 0.0001, n = 123; and hepaplastin test, r = 0.456, P < 0.0001, n = 120. There was good correlation between the predicted residual 99mTc-GSA clearance and the postoperative total hepatic 99mTc-GSA clearance in patients who underwent segmentectomy or lobectomy (r = 0.84, P < 0.0001, n = 28) and between the pre- and postoperative total hepatic 99mTc-GSA clearance in patients who underwent subsegmentectomy (r = 0.91, P < 0.0001, n = 25). Five patients who had postoperative complications due to hepatic insufficiency (2 patients died of postoperative hepatic failure within 2 mo after operation) showed significantly lower predicted residual 99mTc-GSA clearance compared with the patients without complications (90.3 +/- 37.2 versus 320.9 +/- 158.8 mL/min; P < 0.005). CONCLUSION: The total hepatic 99mTC-GSA clearance reflected hepatic function. In addition, preoperative predicted residual hepatic 99mTc-GSA clearance was a good indicator of postoperative hepatic function and early prognosis. 99mTc-GSA dynamic SPECT is assumed to be a useful method for determining the surgical strategy in patients with hepatic tumor and especially in patients with hepatic dysfunction.

Coloring Agents↗

PubMed1999

Age-related changes in the cerebral distribution of 99mTc-ECD from infancy to adulthood.

UNLABELLED: Although cerebral blood flow in infants differs from that in older individuals, the distribution of 99mTc-ethyl cysteinate dimer (ECD) in infants has not been well studied. This study compared 99mTc-ECD distribution in infants and children with that in young adults. METHODS: 99mTc-ECD SPECT was performed on 37 patients suspected of having epilepsy, ranging in age from 3 mo to 26 y. The patients were divided into two age-matched groups, a drug-free group (n = 19) and a drug-taking group (n = 18), according to their anticonvulsant medication status at the time of examination. 99mTc-ECD (100-740 MBq) was injected interictally, and SPECT data were acquired using a triple-head gamma camera. Mean whole-brain counts were obtained from 10 sequential SPECT images. Regions of interest were set bilaterally on five areas of the cerebral cortex and on the basal ganglia, thalamus and cerebellum. The brain perfusion index (BPI) was obtained as a ratio of the mean counts in each region of interest to the mean whole-brain counts. The relationship between BPI and age in each region in the drug-free and drug-taking groups was analyzed separately and together using linear regression. The relationship between five patient age groups (<1 y, n = 4; 1-4 y, n = 9; 5-9 y, n = 8; 10-15 y, n = 7; >15 y, n = 9) and BPI in each region was also examined using multiple comparison analyses. RESULTS: Significant positive correlations between BPI and age in the frontal cortex and cerebellum were confirmed in the drug-free group. Anticonvulsant drugs did not affect the regression lines of BPI in the frontal cortex and cerebellum. Significant differences in BPI between age groups were seen in the parietal cortex, frontal cortex, occipital cortex, basal ganglia, thalamus and cerebellum in all patients. CONCLUSION: Age-related changes in cerebral 99mTc-ECD distribution were confirmed and found to be unaffected by the administration of anticonvulsant drugs. 99mTc-ECD uptake in children and infants is different from cerebral blood flow glucose metabolism as previously reported, especially in the cerebellum.

Adolescent↗

PubMed1999

Forward cardiac output measurement with first-pass technique using 99mTc-labeled myocardial perfusion imaging agents.

UNLABELLED: The aim of this study was to develop and validate a new first-pass method for the measurement of forward cardiac output (CO) using 99mTc-labeled myocardial perfusion imaging agents. METHODS: In protocol 1, to test the new method for measuring CO, the conventional method and the new method for CO measurement were performed in 1 d in 57 patients (32 men, 25 women; age 68 +/- 11 y). In the conventional method, radionuclide angiography (1 frame/s) with in vivo 99mTc labeling (110 MBq) of red blood cells was performed for 2 min in the left anterior oblique projection. Five minutes later, a 1-min equilibrium image was obtained, and a blood sample was taken for calculation of the distribution volume. To obtain data for the new method, further radionuclide angiography (1 frame/sec) with 99mTc labeling (600-740 MBq) of red blood cells was then performed in the anterior projection. CO was calculated using the following equation: CO = Cmax x V(LV)/integral of f(t)dt, where Cmax is the background-corrected peak count of the whole thorax during angiography, integral of f(t)dt is the area under the gamma variate-fitted left ventricular (LV) time-activity curve after background correction and V(LV) is the LV volume obtained by the area length method applied to the radionuclide angiography and myocardial tomography. In protocol 2, to evaluate the new method, 24 patients (16 men, 8 women; age 71 +/- 9.2 y) underwent radionuclide angiography with 99mTc-tetrofosmin (600-740 MBq), and the measured CO was compared with the CO obtained by the conventional method with 99mTc-labeled red blood cells. RESULTS: In protocol 1, good correlation was observed between the CO by the new method (Y) and the CO by the conventional method (X): Y = 1.0X + 57 mL/min and r = 0.95. There was good agreement between the two methods (mean difference -56 +/- 381 mL/min). Inter- and intraobserver correlation coefficients were 0.96 and 0.98, respectively. In protocol 2, the CO by the new method using 99mTc-tetrofosmin (Y) showed a good correlation with the CO by the conventional method (X): Y = 0.90X + 453 mL/min and r = 0.93. Good agreement between the two methods was observed (mean difference 73 +/- 390 mL/min). Inter- and intraobserver correlation coefficients were 0.95 and 0.98, respectively. CONCLUSION: This new method permits accurate forward CO measurement using the first-pass data with 99mTc-terofosmin, which is applicable to other 99mTc-labeled myocardial perfusion imaging agents.

Aged↗

PubMed1999

[Assessment of regional quantitative analysis by ECG-gated myocardial SPECT after coronary artery bypass surgery].

PURPOSE: ECG-gated myocardial SPECT (G-SPECT) was performed before and after coronary artery bypass surgery (CABG) to investigate how this operation would affect the assessment of regional quantitative analyses. METHODS: Nineteen patients with coronary artery disease underwent G-SPECT before and 1 month after uncomplicated CABG. 99mTc-MIBI 740 MBq was injected at rest, then G-SPECT was performed 60 min later. Regional ejection fraction (rEF), wall motion (WM), systolic wall thickening (WT) and % tracer uptake were evaluated by quantitative gated SPECT program (QGS). Parameters were obtained quantitatively in 16 segments based on the functional bull's eye map. RESULTS: Percent tracer uptake increased in septum from 75 +/- 11% to 78 +/- 11% (p < 0.001), while WT did not change (40 +/- 19% to 41 +/- 20%) after CABG. However, in septum rEF decreased from 17 +/- 13% to 6 +/- 9% (p < 0.001) and WM decreased in septum from 1.6 +/- 1.1 mm to 0.6 +/- 0.9 mm (p < 0.001). CONCLUSION: Significant reduction of rEF and WM despite of no deterioration of WT and % tracer uptake suggested that rEF and WM were affected by pseudoparadoxical asynergy after uncomplicated CABG. For the evaluation of regional function after CABG by G-SPECT, WT might be the preferred parameter.

Aged↗

PubMed1998

Sentinel Lymphadenectomy in Breast Cancer: An Alternative to Routine Axillary Dissection.

We reviewed the literature concerning sentinel lymphadenectomy in breast cancer and reached the following conclusions: (a) A combination of lymphoscintigraphy and dye-guided and/or gamma probe-guided techniques are superior to either technique alone for identifying the sentinel lymph node. (b) lmmediate and reliable intraoperative information on the sentinel node is vital for the technique's success. However, the reliability of sentinel node diagnosis using frozen sections is questionable, because micrometastatic foci cannot be identified. (c) A reverse transcriptase-polymerase chain reaction(RT-PCR)method is more sensitive than immunohistochemistry for the detection of micrometastasis in the sentinel node. (d) Until there are new tumor markers or new imaging techniques to identify axillary metastasis without operative intervention, sentinel lymphadenectomy is a highly accurate, minimally invasive way to assess disease extent. Before sentinel lymphadenectomy gains general acceptance for patients with primary breast cancer, however, a large clinical trial will be essential to verify the value of this technology.

Journal Article↗

PubMed1998

Asymmetries of benzodiazepine receptor binding potential in the inferior medial temporal lobe and cerebellum detected with 123I-iomazenil SPECT in comparison with 99mTc-HMPAO SPECT in patients with partial epilepsy.

We examined the relation between regional 123I-iomazenil (IMZ) parameters and cerebral blood flow (CBF) to evaluate the difference between the quantitative parameters of IMZ and the CBF in detecting epileptic abnormality. Seventeen patients with unilateral partial epilepsy were subjected to 99mTc-hexamethylpropylene amine oxime (HMPAO) SPECT, and early and delayed IMZ SPECT. Then we quantitatively obtained the blood-to-brain transfer constants (K1) and binding potentials (BP) for nine regions of interest, and the regional CBF was also by using the simple angiographic method. From our data, significant asymmetries of BP in the inferior medial temporal lobe and cerebellum were shown and may be related to a remote effect such as crossed cerebellar diaschisis. In conclusion, the asymmetry of BP with iomazenil SPECT was demonstrated in patients with unilateral epilepsy that was not detectable by HMPAO SPECT.

Adult↗

PubMed1998

99mTc-tetrofosmin uptake in bone metastases from breast cancer.

99mTc-tetrofosmin myocardial imaging was performed in a 62-year-old woman who had undergone standard radical mastectomy for right breast cancer 6 years ago. Although the result was negative for the ischemic heart disease, it showed abnormal accumulation corresponding to the bone metastases in the spine. We believe that 99mTc-tetrofosmin imaging is helpful in detecting bone metastases from breast cancer.

Bone Neoplasms↗

PubMed1998

Value of iodine-123 metaiodobenzylguanidine scintigraphy in patients with vasospastic angina.

To assess the presence and location of presynaptic myocardial sympathetic abnormality in patients with vasospastic angina, iodine-123 labelled metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPET) was performed. Fifty patients suspected of having vasospastic angina pectoris were enrolled in the study. All patients underwent a provocative test with intracoronary ergonovine infusion during coronary angiography, in which 99%-100% obstructive spasm was defined as a positive result. Twenty-five patients were diagnosed as having vasospastic angina based on a positive provocative test. MIBG SPET was performed at 20 min and 3 h after administration of 111 MBq or MIBG. On early images, only 5 of 25 patients with vasospastic angina showed a mild reduction in MIBG uptake, whereas 3-h delayed images demonstrated MIBG abnormality in 20 patients (80%). The location of the MIBG abnormality was completely or partially consistent with the spastic coronary territory in 18 patients. On the other hand, only 4 of 25 patients (16%) with negative provocative test demonstrated reduced MIBG uptake. Accordingly, positive and negative predictive values of MIBG SPET for the provocative test were 83% (20/24) and 81% (21/26) respectively. In conclusion, MIBG scintigraphy with SPET can permit the non-invasive detection and evaluation of suspected vasospastic angina.

3-Iodobenzylguanidine↗

PubMed1998

Superiority of triple-detector single-photon emission tomography over single- and dual-detector systems in the minimization of motion artefacts.

A patient motion-related artefact is one of the most important artefacts in single-photon emission tomography (SPET) imaging. This study evaluated the effect of the number and configuration of SPET detectors on motion artefacts. The following acquisition conditions were simulated based on original 360 degrees projection images: (1) single-detector 180 degrees rotation (S180), (2) a dual-detector rectangular (L-shaped) 180 degrees acquisition (D180L), (3) dual-detector cameras mounted opposite each other with 360 degrees acquisition (D360) and (4) triple-detector 360 degrees acquisition (T360). The motion artefacts were introduced using a syringe and a myocardial phantom. Clinical cases with technetium-99m methoxyisobutylisonitrile and thallium-201 studies were analysed to confirm the validity of this phantom simulation. The effect of continuous alternate rotation acquisition and summing the projections on the reduction of motion artefacts was investigated in each model. The effect of motion depended on the number and the configuration of the SPET detectors. A 1-pixel (6.4 mm) motion in the S180, D180L and D360 models generated only slight artefacts, and a 2-pixel motion led to an apparent decrease in activity or created hot areas in the myocardium. On the other hand, a T360 rotation created few artefacts even with a 2-pixel motion of the last quarter of the projections. Despite the difference in attenuation with 201Tl and 99mTc, similar artefact patterns were observed with both radionuclides in selected patient model studies. Continuous alternate rotation could reduce artefacts caused by less than a 2-pixel motion. In conclusion, calculating the average of the sum of the projections of triple-detector 360 degrees rotations with alternate rotation is the best method to minimize motion artefacts. This "averaging" effect of motion artefacts is a key to this simulation.

Gamma Cameras↗

PubMed1998

Effect of 360 degrees and 180 degrees rotation SPET acquisitions on myocardial polar map: comparison of 201Tl-, 99Tcm- and 123I-labelled radiopharmaceuticals.

Both 360 degrees and 180 degrees rotation acquisition methods have been used in myocardial single photon emission tomography (SPET) studies. We compared both methods using 201Tl, 99Tcm and 123I radiopharmaceuticals with phantoms and clinical models. Myocardial phantom studies with anterior and inferior defects were performed using 201Tl, 99Tcm and 123I. Clinical models of 14 typical situations, including normal subjects, patients with anterior or inferior defects and a high right hemi-diaphragm, were studied. The radiopharmaceuticals were 201Tl, 99Tcm-sestamibi, 123I-BMIPP and 123I-MIBG. Four sets of 180 degrees anterior rotation data with starting angles of (A) posterior, (B) LPO 30 degrees, (C) LPO 60 degrees and (D) left lateral direction were generated and compared with 360 degrees rotation SPET. A polar map display was used for quantification. In phantom studies, the defect contrast on the map was higher in the anterior defect with 180 degrees rotation than with 360 degrees rotation. However, it was decreased in the inferior defect, particularly with 201Tl, because of decreased wall activity around the defect. In the patient model with anterior or inferior defects, the defect contrast was improved with 180 degrees SPET by up to 10%. A slight decrease in the normal region was also noted in the 180 degrees reconstruction. The effect of diffuse liver activity on the inferior region depended on the rotation range. A patient with a high right hemi-diaphragm showed a lower inferior count with 360 degrees SPET. In conclusion, the 360 degrees acquisition was superior to the 180 degrees acquisition in the phantom with defects. Clinically, the quantitative differences in radionuclide types (99Tcm, 123I or 201Tl) were not significant for quantifying a moderate degree (50-60% of peak count) of defect. However, we note quantitative variation depending on the rotation range in the 180 degrees method.

3-Iodobenzylguanidine↗

PubMed1998

Myocardial fatty acid imaging with 123I-labelled 9-methyl-branched pentadecanoic acid (9MPA) using SPET.

123I-labelled 15-(p-iodophenyl)-9-(R,S)-methylpentadecanoic acid (9MPA) is a modified long-chain fatty acid that shows some beta-oxidation. Some basic aspects of this fatty acid, including myocardial uptake, distribution, clearance and differences from 201Tl myocardial perfusion, have yet to be evaluated. An average of 150 MBq of 123I-9MPA was injected intravenously into 16 patients with coronary artery disease. Planar images were obtained 45, 120 and 240 min post-injection, and single photon emission tomography (SPET) was performed at the initial (5 min), middle (45 min) and late (120 min) phases after injection. Myocardial uptake and clearance were evaluated by planar imaging, and a segmental comparison between 123I-9MPA and reinjection or resting 201Tl was performed on the SPET images. 123I-9MPA showed good uptake between 5 and 60 min, but a severe decrease was seen after 120 min in three (19%) patients. The heart-to-mediastinum ratio was 1.68 +/- 0.19, 1.55 +/- 0.19 and 1.40 +/- 1.40 at 45, 120 and 240 min, respectively. The washout rate after background subtraction was 28% for 45 min to 2 h and 47% for 45 min to 4 h. The segmental comparison (n = 182) between 123I-9MPA and 201Tl showed complete agreement of 72, 75 and 65% at 10, 45 and 120 min, respectively. The grading of the uptake of 123I-9MPA was less than that of 201Tl in 20-30% of the segments indicating myocardial fatty acid metabolic impairment relative to perfusion. The regional clearance from 5 to 120 min in the reduced-count region was lower than that in the normal region (28 +/- 7% vs 36 +/- 8%, P < 0.01). All 123I-9MPA SPET images showed good contrast if the data were acquired within 60 min. Based on the clearance of 123I-9MPA from the myocardium, imaging within 120 min is desirable. A mismatch of fatty acids and perfusion was seen in one-quarter of patients, and differential regional clearance may be clinically significant and should be investigated.

Adult↗

PubMed1998

Rhenium-186-mercaptoacetyltriglycine-labeled monoclonal antibody for radioimmunotherapy: in vitro assessment, in vivo kinetics and dosimetry in tumor-bearing nude mice.

Stability and immunoreactivity of 186Re-labeled monoclonal antibody were examined, and its in vivo kinetics was investigated in tumor-bearing Balb/c nu/nu female mice to assess the feasibility of using it in radioimmunotherapy (RIT). A murine IgG1, A7, against a 45 kD glycoprotein in human colon cancer was radiolabeled with 186Re by using a chelating method with a mercaptoacetyltriglycine (MAG3). 186Re-MAG3 complex was conjugated to A7 after esterification of 186Re-MAG3 with tetrafluorophenol (TFP). The efficiency of 186Re-MAG3-TFP production and the labeling efficiency of A7 were 51-59% and 57-60%, respectively. Immunoreactivity of purified 186Re-MAG3-A7 was 68.2% at infinite antigen excess. In 0.9% NaCl at 4 degrees C, the radioactivity (12.7 MBq/mg, 3.55 MBq/ml) dissociated with time from 186Re-MAG3-A7 as a small molecular weight moiety because of autoradiolysis. The addition of ascorbic acid, 5 mg/ml, as a radioprotectant or storage at -80 degrees C could effectively prevent the radiolysis of 186Re-MAG3-A7 for 7 days. Immunoreactivity of 186Re-MAG3-A7, 6.70 MBq/mg (6.66 MBq/ml), stored in the presence of ascorbic acid was well retained up to 8 days after the preparation. In colon cancer xenografted mice, 31.0% of the injected dose/g of 186Re-MAG3-A7 had accumulated in the tumors at 24 h postinjection. Estimated radiation dose to tumors was 14.9 cGy/37 kBq up to 8 days postinjection which was 12-fold greater than the whole-body radiation dose. These in vivo characteristics were superior to those of A7 labeled with radioiodine, affording greater therapeutic ratios than 131I-A7. Because of the better image quality of 186Re-MAG3-A7 as well as more favorable dosimetry, 186Re-MAG3-A7 would be a better choice for RIT of colon cancer than 131I-A7. These results indicated the feasibility of RIT with 186Re-MAG3-A7, though the prevention of radiolysis of the labeled antibody should be considered.

Animals↗

PubMed1998

177Lu-EDTMP: a potential therapeutic bone agent.

Lutetium-177 (177Lu) has both beta particle emissions for a therapeutic effect and gamma emissions for imaging. This study was undertaken to synthesize and evaluate 177Lu-EDTMP (ethylenediaminetetramethylene phosphonic acid) as a therapeutic radiopharmaceutical for the palliation of pain from bone metastases. Chelation of 177Lu to EDTMP was obtained by heating for 30 min in boiling water at pH 8.8, resulting in a radiochemical yield of over 99%. The compound was stable for 20 days without any appreciable dissociation. Biodistribution studies in normal rats indicated selective bone accumulation, showing faster blood clearance, higher bone uptake and higher bone-to-soft tissue ratios than 99Tcm-MDP. In conclusion, 177Lu-EDTMP has favourable biological and physical characteristics for the palliative treatment of painful bone metastases.

Animals↗