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Shibutani, Takayuki ; Nakajima, Kenichi ; Wakabayashi, Hiroshi ; Mori, Hiroshi ; Matsuo, Shinro ; Yoneyama, Hiroto ; Konishi, Takahiro ; Okuda, Koichi ; Onoguchi, Masahisa ; Kinuya, Seigo ; 澁谷, 孝行 ; 中嶋, 憲一 ; 若林, 大志 ; 松尾, 信郎 ; 米山, 寛人 ; 小野口, 昌久 ; 絹谷, 清剛
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金沢大学医薬保健研究域保健学系<br />ObjectivesThe patient-based diagnosis with an artificial neural network (ANN) has shown potential u
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tility for the detection of coronary artery disease; however, the region-based accuracy of the detected regions has not been fully evaluated. The aim of this study was to demonstrate the accuracy of all detected regions compared with expert interpretation.\nMethodsA total of 109 abnormal regions including 33 regions with stress defects and 76 regions with ischemia were examined, which were derived from 21 patients who underwent myocardial perfusion SPECT within 45 days of coronary angiography. The gray and color scale images, a polar map of stress, rest and difference, and left ventricular function were displayed on the monitor to score the extent and severity of stress defect and ischemia. Two experienced nuclear medicine physicians (Observers A and B) scored the abnormality with a 4-point scale and draw abnormal regions on a polar map. The gold standard was determined by the final judgment of normal or abnormal by the consensus of two other independent expert nuclear cardiologists, and was compared with the stress defect and ischemia derived from ANN.\nResultsThe concordance rate of ANN to the gold standard was higher than that of two observers. Furthermore, the κ coefficient indicated moderate to substantial agreement for stress defect and slight to the fair agreement for ischemia. The area under the curve (AUC) of ANN was the highest for both stress defect and ischemia; in particular, the ANN of ischemia showed significantly higher AUC than Observer A (p = 0.005). The ANN of stress defect showed higher specificity compared with two observers, while the ANN of ischemia showed higher sensitivity. Consequently, the accuracy of ANN showed the highest in this study.\nConclusionThe ANN-based regional diagnosis showed a high concordance rate with the gold standard and comparable or even higher than the interpretation by nuclear medicine physicians.<br />Embargo Period 12 months
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Onoguchi, Masahisa ; Maruno, Hirotaka ; Takayama, Teruhiko ; Murata, Hajime
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Okuda, Koichi ; Nakajima, Kenichi ; Motomura, Nobutoku ; Kubota, Masahiro ; Yamaki, Noriyasu ; Maeda, Hisato ; Matsuo, Shinro ; Kinuya, Seigo
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金沢大学医薬保健研究域<br />Objective: Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) met
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hod can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusion database. Methods: A total of 32 sets of exercise-rest myocardial images with Tc-99 m-sestamibi were acquired in both photopeak (140 keV ± 10%) and scatter (7% of lower side of the photopeak window) energy windows. Myocardial perfusion databases by the SSPAC method and non-AC (NC) were created from 15 female and 17 male subjects with low likelihood of cardiac disease using quantitative perfusion SPECT software. Segmental myocardial counts of a 17-segment model from these databases were compared on the basis of paired t test. Results: AC average myocardial perfusion count was significantly higher than that in NC in the septal and inferior regions (P < 0.02). On the contrary, AC average count was significantly lower in the anterolateral and apical regions (P < 0.01). Coefficient variation of the AC count in the mid, apical and apex regions was lower than that of NC. Conclusions: The SSPAC method can improve average myocardial perfusion uptake in the septal and inferior regions and provide uniform distribution of myocardial perfusion. The SSPAC method could be a practical method of attenuation correction without X-ray CT. © 2009 The Japanese Society of Nuclear Medicine.
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Shikano, Naoto ; Kawai, Keiichi ; Garcia Flores II, Leo ; Nishii, Ryuichi ; Kubota, Nobuo ; Ishikawa, Nobuyoshi ; Kubodera, Akiko
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金沢大学大学院医学系研究科<br />We evaluated the use of radiolabeled 4-iodo-L-meta-tyrosine as an amino acid transport marker. The ph
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armacologic features of this compound, particularly the biodistribution and excretion, were examined by conducting in vivo and in vitro studies using 4-125I-iodo-L-meta-tyrosine (4- 125I-mTyr). Results obtained for L-14C-Tyr and 3- 125I-iodo-α-methyl-L-tyrosine (125I-IMT) were used for comparison. Methods: In vivo biodistribution studies of 4- 125I-mTyr were performed in male ddY mice. Urinary excretion of 4-125I-mTyr and 125I-IMT with administration of probenecid was studied. Local distribution of 4-125I-mTyr and 125I-IMT in kidney was visualized by autoradiography. We performed metabolite analysis of 4-125I-mTyr in mice. For in vitro studies, reabsorption mechanisms of 4-125I-mTyr were compared with those of 125I-IMT and the parent L-14C-Tyr using superconfluent monolayers of the porcine kidney epithelial cell line LLC-PK1 in medium containing inhibitor (L-Tyr, D-Tyr, and 2,4-dinitrophenol), in Na +-free medium, and at 4°C. Results: 4-125I-mTyr demonstrated high accumulation in the pancreas and kidney and comparable brain uptake to that of 125I-IMT. Blood clearance of 4-125I-mTyr was faster than that of 125I-IMT. Three hours after administration, >70% of 4-125I-mTyr was excreted via the urine, whereas <5% was found in the feces. Renal autoradiography revealed moderate accumulation of 4-125I-mTyr and high accumulation of 125I-IMT in the renal cortex. Probenecid further reduced accumulation of 4-125I-mTyr and 125I-IMT in the kidney as well as urinary excretion. At 30 min after tracer injection, intact free 4-125I-mTyr accounted for >98.1% of the total present in kidney and >96.3% in urine. Protein incorporation was not observed. Uptake of 4-125I-mTyr into LLC-PK1 cell monolayers was remarkably reduced by 5 mmol/L L-Tyr (4.6%) and incubation at 4°C (15.6%) but was reduced by 5 mmol/L D-Tyr (50.0%). L-14C-Tyr and 125I-IMT showed similar results; however, uptake of 125I-IMT was enhanced by 0.1 mmol/L 2,4-dinitrophenol (165.1%), an inhibitor of generation of energy-rich phosphates. Conclusion: The artificial amino acid 4-125I-mTyr demonstrated high metabolic stability, rapid blood clearance, rapid urinary excretion, and similar biodistribution to other radioiabeled L-Tyr analogs. 4-125I-mTyr can be a competitive substrate of L-Tyr reabsorption. However, 4-125I-mTyr demonstrates different pharmacologic features than those of 125I-IMT, particularly in renal handling. 4-125I-mTyr may potentially be applied as a new amino acid transport marker.
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Shuke, Noriyuki ; Okizaki, Atsutaka ; Kino, Shuichi ; Sato, Junichi ; Ishikawa, Yukio ; Zhao, Chunlei ; Kinuya, Seigo ; Watanabe, Naoto ; Yokoyama, Kunihiko ; Aburano, Tamio
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金沢大学大学院医学系研究科<br />The objective of this study was to validate a method for estimating regional liver asialoglycoprotein
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(ASGP) receptor amount from single blood samples using static SPECT with 99mTc-diethylenetriaminepentaacetic acid galactosyl human serum albumin (99mTc-GSA). Methods: Based on a 2-compartment nonlinear model, regional ASGP receptor amount could be calculated from total liver ASGP receptor amount (Ro) and regional GSA uptake at a specific time. Because Ro could be estimated from single blood samples using an empiric formula, regional GSA uptake obtained as a SPECT voxel count could be converted to regional ASGP receptor amount by solving a non-linear model equation. To validate this method, data from 62 patients with chronic liver disease underwent dynamic SPECT (30 rotations per 30 min) and simultaneous multiblood sampling and were analyzed by this method. Ro was calculated as the sum of voxel values of parametric receptor images generated from plasma concentration of GSA at 20 min and of static SPECT images generated by merging dynamic SPECT data (12-20 min). Ro was also estimated by fitting time-activity curves (4-30 min) of plasma and whole liver to the nonlinear model using the nonlinear regression method. Ro obtained from the receptor image was compared with that from curve fitting in relation to the results of hepatic function tests (indocyanine green test, hepaplastin test, and branched-chain amino acids/tyrosine plasma concentration ratio) and Child's classification. Results: Ros from the 2 methods showed a significant linear correlation (r2 = 0.938; P < 0.0001; slope = 0.90; y-intercept = 1.5). Both Ros had significant correlations with the results of hepatic function tests (P < 0.001) and differed significantly among the 3 groups of Child's classification (P < 0.0001). Conclusion: The present method could provide a quantitative ASGP receptor image without dynamic data acquisition. This approach could be useful for quantitative evaluation of regional liver function and estimation of residual liver function in hepatectomy.
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Taki, Junichi ; Matsunari, Ichiro
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金沢大学医学部附属病院核医学診療科<br />Introduction: In normal condition, the heart obtains more than two-thirds of its energy from the
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oxidative metabolism of long chain fatty acids, although a wide variety of substrates such as glucose, lactate, ketone bodies and amino acids are also utilised. In ischaemic myocardium, on the other hand, oxidative metabolism of free fatty acid is suppressed and anaerobic glucose metabolism plays a major role in residual oxidative metabolism. Therefore, metabolic imaging can be an important technique for the assessment of various cardiac diseases and conditions. Materials and methods: In SPECT, several iodinated fatty acid traces have been introduced and studied. Of these, 123I-labelled 15-(p-iodophenyl)3-R, S-methylpentadecanoic acid (BMIPP) has been the most commonly used tracer in clinical studies, especially in some of the European countries and Japan. Results and discussion: In this review article, several fatty acid tracers for SPECT are characterised, and the mechanism of uptake and clinical utility of BMIPP are discussed in detail. © 2007 Springer-Verlag.
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Matsuo, Shinro ; Nakajima, Kenichi ; Wakabayashi, Hiroshi ; Akhter, Nasima ; Taki, Junichi ; Okuda, Koichi ; Kinuya, Seigo
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金沢大学附属病院核医学診療科<br />Background: We evaluated the relationship between computed tomography angiography (CTA) and SPECT, a
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nd assessed to determine the clinical usefulness of the fusion image using CTA and myocardial perfusion imaging (MPI). Methods: Forty-one consecutive patients [after coronary artery bypass operation (n = 13) and suspected stenosis (n = 28)] underwent MPI and CTA. SPECT/CTA fused images were generated. Results: In total, 687 segments including bypass graft in 164 coronary arteries were analyzed. Myocardial ischemia on MPI was observed in 11 patients among 28 with CTA abnormalities, one had both ischemia and infarction, and 7 had only infarction. Segment-based analysis showed that ischemia was found in 14 segments (24%) among 59 stenoses on CTA. Forty stenotic segments (69%) were not associated with perfusion abnormality. The rest 5 stenotic segments were considered equivocal (8%). A fusion image made it possible to associate perfusion defects with its corresponding coronary artery in 4 out of 5 equivocal lesions on side-by-side analysis. Patients with incremental diagnostic information on SPECT/CTA fusion (n = 4) had significant smaller coronary diameter than that of not-improved coronary vessels (2.0 ± 0.4 vs. 3.9 ± 0.4 mm, p = 0.001). Conclusion: Cardiac fusion imaging accurately diagnosed functionally relevant coronary stenosis. SPECT/CTA fusion images in coronary artery disease may provide added diagnostic information on functional relevance of coronary artery disease. © 2009 The Japanese Society of Nuclear Medicine.
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Matsuo, Shinro ; Nakajima, Kenichi ; Yamasaki, Yoshimitsu ; Kashiwagi, Atsunori ; Nishimura, Tsunehiko
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金沢大学附属病院核医学診療科<br />Background: This study was designed to determine the clinical risk for hard events after normal sing
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le-photon emission computed tomography (SPECT) and to identify the predictors of increased risk in asymptomatic patients with diabetes mellitus, based on a Japanese Assessment of Cardiac Events and Survival Studies by quantitative gated SPECT (J-ACCESS)-2 study. Methods and Results: A total of 513 consecutive asymptomatic patients who underwent stress 99 mTc-tetrofosmin SPECT in Japan were included in this study. Based on SPECT image and QGS data, 319 had a summed stress score ≤3, a summed difference score <2 and normal cardiac function (end-systolic volume ≤60 ml, males, ≤40 ml, females; left ventricular ejection fraction ≥49%, males, ≥50%, females). Myocardial perfusion was normal in 62% of this study population. During a 3-year follow-up, there were a total of 8 cardiac major events (2.5%): 2 cases of sudden death, 5 of acute coronary syndrome, and 1 of hospitalization because of congestive heart failure. The annual major event rate was 0.8%. Subjects undergoing coronary angiography had significantly more major events than those who did not among normal SPECT subjects (P=0.01). Kaplan-Meier analysis showed that the cardiac major events rate was very low, and subjects with normal SPECT can be considered as low risk among asymptomatic patients with diabetes. Conclusions: An excellent prognosis was associated with a normal SPECT in asymptomatic patients with diabetes, so these patients can be exempted from further invasive procedure.
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