Atsutaka Okizaki

Comparison of myocardial fatty acid metabolism with left ventricular function and perfusion in cardiomyopathies: by 123 I-BMIPP SPECT and 99m Tc-tetrofosmin electrocardiographically gated SPECT

Objective: To investigate myocardial fatty acid metabolism and its relationship with left ventricular (LV) function and perfusion in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).Methods: Thirty-nine patients with cardiomyopathies (58±14 y), comprising 15 DCM and 24 HCM, and 9 age-matched healthy controls were studied with123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and99mTc-tetrofosmin (TF) electrocardiographically gated SPECT. As parameters of myocardial fatty acid metabolism, the heart-to-mediastinum ratio (H/M) and global washout of BMIPP were calculated from early and delayed planar images, while regional BMIPP uptake and washout were calculated from SPECT. In TF study, the H/M (H/M-TF) and LV ejection fraction (LVEF) were calculated as global parameters of perfusion and function, while regional TF uptake and wall thickening index were calculated as regional parameters of perfusion and function using the Quantitative Gated SPECT software. The differences in the parameters and the correlations between the parameters from the 2 studies were investigated by one-way ANOVA and multiple linear regression analysis.Results: BMIPP uptake was decreased (p<0.05), and its washout was increased (p<0.05) in DCM and HCM. In multiple linear regression analysis, global BMIPP parameters showed no significant correlation with LVEF (p>0.05), but showed a significant correlation with H/M-TF (p<0.05) in DCM and HCM. According to the partial correlation coefficient, early H/M was the only significant factor (p<0.05) for predicting H/M-TF in DCM and HCM. Multiple linear regression analysis on regional parameters showed regional BMIPP parameters had no correlation with regional function (p>0.05) but had a significant correlation with regional perfusion (p<0.0001) in DCM. In HCM, regional BMIPP parameters showed significant multiple linear correlations with both regional function (p<0.005) and perfusion (p<0.0001). According to the partial correlation coefficients, delayed regional BMIPP uptake was the most significant factor for predicting regional function in HCM, while early regional BMIPP uptake was the only or the most significant factor for predicting regional perfusion in DCM and HCM, respectively.Conclusion: In DCM, BMIPP uptake and washout could not reflect LV function. In HCM, regional delayed BMIPP uptake might be useful for evaluating regional function. In DCM and HCM, early BMIPP uptake might be largely determined by myocardial perfusion.

A compartment model analysis for investigation of myocardial fatty acid metabolism in patients with hypertrophic cardiomyopathy

ObjectiveThe purpose of this study was to investigate the myocardial fatty acid metabolism in patients with hypertrophic cardiomyopathy (HCM) from dynamic SPECT through a compartment model analysis. MethodsTwenty-four normal controls, seven patients with left ventricular hypertrophy (LVH) due to essential hypertension (eHT), and 30 patients with HCM were studied. 123I-BMIPP and 99mTc-tetrofosmin SPECT were performed. All the myocardium was divided into 13 segments, and a total of 390 segments of HCM were categorized into early, moderately and severely advanced HCM segments, based on these SPECT imaging. By using the myocardial and blood pool time–activity curves, BMIPP pharmacokinetics were analysed through a two-compartment model. We defined k1 and k2 as influx and outflux rate constants between blood and myocardial reversible component, and k3 as the specific uptake rate constant between myocardial reversible and irreversible compartments. ResultsThe averages of k3 in HCM were higher than in normal. In contrast, the averages of k1/k2 in HCM were lower than in normal, and gradually decreased with progression of HCM. There are no significant differences in these indexes between normal controls and patients with LVH due to eHT. Conclusionk3 might be a sensitive predictor for early detection of HCM, and k1/k2 could be a useful index to evaluate its progression. A mathematical compartment model analysis with a BMIPP SPECT study might be useful not only for identification of HCM in very early stage, but also for evaluation of the progression of HCM.

Protein-less into retroperitoneal lymphangioma: Demonstration by lymphoscintigraphy and blood-pool scintigraphy with Tc-99m-human serum albumin

A rats, benign congenital lymphangioma has been reported to ocour frequently in the neck and axilla, but rarely in the retroperitoneal space. We report a case of a retroperitoneal lymphangioma associated with hypoproteinemia caused by protein-loss into the tumor. In this case, lympho-scintigraphy with subcutaneously injected Tc-99m-human serum albumin (HSA) disclosed the communication between the tumor and the lymphatic system, and sequential abdominal scintigraphy with intravenously injected Tc-99m-HSA revealed the protein loss into the tumor. Abdominal scintigraphy with Tc-99m-HSA injected intravenously or subcutaneously is occasionally useful for determining the etiology of hypoproteinemia.

Accumulation of Tc-99m HMDP in extramedullary plasmacytoma of the stomach.

A case of extramedullary plasmacytoma is reported as a rare cause of stomach uptake of bone tracer. A 48-year-old woman, who was thought to have a submucosal tumor of the stomach based on endoscopic findings, underwent bone scintigraphy with Tc-99m HMDP that showed extraosseous uptake in the left upper abdomen. A double-contrast upper gastrointestinal barium examination and abdominal computed tomography revealed a large tumor of the stomach with dense calcifications, which corresponded to the accumulation of Tc-99m HMDP. Biopsy of the tumor removed via endoscopy revealed extramedullary plasmacytoma of the stomach.

Hepatic clearance measured with (99m)Tc-GSA single-photon emission computed tomography to estimate liver fibrosis.

AIM To evaluate the clinical utility of hepatic clearance (HC) measured with technetium-99m-diethylenetriaminepenta-acetic acid-galactosyl human serum albumin ((99m)Tc-GSA) single-photon emission computed tomography (SPECT) to estimate the degree of liver fibrosis. METHODS Seventy-eight consecutive patients who underwent initial hepatectomy due to hepatocellular carcinoma were enrolled in this study. Indocyanine green clearance (ICG R15), quantitative indices estimated by (99m)Tc-GSA [the receptor index (LHL15 and HH15) and HC via SPECT analysis], and conventional liver function tests were performed before hepatectomy. Correlations among the quantitative indices for liver functional reserve, conventional liver function tests, and the degree of liver fibrosis were evaluated. RESULTS The degree of liver fibrosis was correlated with ICG R15, HH15, LHL15, and HC. HC showed the best correlation with conventional liver function tests. According to multivariate analysis, HC and LHL15 were significant independent predictors of severe fibrosis. HC was the most valuable index for predicting severe fibrosis. CONCLUSION HC measured with (99m)Tc-GSA SPECT is a reliable index for assessing liver fibrosis before hepatectomy.

Cerebral control of bladder storage in patients with detrusor overactivity

ObjectiveTo identify the brain areas that control bladder storage by technetium-99m hexamethylpropyleneamine oxime single-photon emission computed tomography (SPECT) with the Neurological Statistical Image Analysis software (NEUROSTAT) in patients with detrusor overactivity (DO). MethodsSPECT scans were performed on 19 patients with DO. Eight patients with normal detrusor function, who had some storage symptoms of the lower urinary tract as the patients with DO, also had a SPECT scan, as controls. All the patients were male and right handed, and were scanned twice under two conditions: resting state and urine withholding state. NEUROSTAT was adopted to analyze the difference in brain--blood perfusion between groups and states. The results were displayed on Z score images at a significance threshold of P value of less than 0.05 with correction for multiple comparisons. ResultsNo region reached the significant threshold in comparison with patients with DO and normal detrusor function in resting state. Significant increases in tracer activity in the right inferior frontal gyrus and the right middle temporal gyrus during urine withholding state as compared with resting state in patients with normal detrusor function were observed. Among the regions, the right inferior frontal gyrus was distinctly prominent at both Z score and the extent. The regions that were significantly activated in patients with normal detrusor function did not reach a significant threshold during urine withholding in patients with DO. ConclusionThe study indicated that the right inferior frontal gyrus and the right middle temporal gyrus, especially the right inferior frontal gyrus, played a role in the cerebral control of bladder storage, inhibiting the contraction of detrusor in urine storage.

Improved accuracy in estimation of left ventricular function parameters from QGS software with Tc-99m tetrofosmin gated-SPECT: a multivariate analysis

The purpose of this study was to verify whether the accuracy of left ventricular parameters related to left ventricular function from gated-SPECT improved or not, using multivariate analysis.Methods: Ninety-six patients with cardiovascular diseases were studied. Gated-SPECT with the QGS software and left ventriculography (LVG) were performed to obtain left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Then, multivariate analyses were performed to determine empirical formulas for predicting these parameters. The calculated values of left ventricular parameters were compared with those obtained directly from the QGS software and LVG.Results: Multivariate analyses were able to improve accuracy in estimation of LVEF, EDV and ESV. Statistically significant improvement was seen in LVEF (from r=0.6965 to r=0.8093, p<0.05). Although not statistically significant, improvements in correlation coefficients were seen in EDV (from r=0.7199 to r=0.7595, p=0.2750) and ESV (from r=0.5694 to r=0.5871, p=0.4281).Conclusion: The empirical equations with multivariate analysis improved the accuracy in estimating LVEF from gated-SPECT with the QGS software.

Estimation with Tc-99m tetrofosmin SPECT of salvaged myocardial mass after emergent reperfusion therapy in acute myocardial infarction

Objectives: The purpose of this study was to validate a new quantitative index of salvaged myocardial mass calculated from Tc-99m tetrofosmin SPECT for evaluating the therapeutic effect of emergent reperfusion therapy in acute myocardial infarction (AMI).Methods: Tc-99m tetrofosmin SPECT was performed before and after emergent percutaneous transluminal coronary angioplasty (PTCA) in eight patients with AMI. In the pre-PTCA study, Tc-99m tetrofosmin was injected before emergent PTCA. Two weeks after the PTCA, post-PTCA study was performed. As a quantitative index of salvaged myocardial mass, salvaged myocardial volume (SMV) was defined as the difference of myocardial functional volume between the SPECT studies before and after the PTCA. To investigate the clinical significance of SMV, SMV was compared with the grade of therapeutic efficacy determined visually from pre- and post-PTCA SPECT images and clinical parameters, namely peak creatine phosphokinase level (pCK) and the time from the onset of the AMI to reperfusion (RPT).Results: SMV showed a significant correlation with the visual grade of therapeutic efficacy (r = 0.737, p < 0.037) and a trend toward significant correlation with pCK (r = -0.622, p < 0.1 ). SMVs in early- and late-reperfusion groups (RPT ≤ 6 hr and RPT > 6 hr) were 30.0 ± 14.0 and -6.2 ± 25.5 ml, showing a greater mean SMV value in the early-reperfusion group ( p < 0.07).Conclusion: SMV could be used as a quantitative index of salvaged myocardial mass for evaluating the therapeutic effect of emergent reperfusion therapy.

Optimization of the uptake method for estimating renal clearance of 99mTc mercaptoacetyltriglycine.

ObjectiveTo improve the estimation of 99mTc mercaptoacetyltriglycine clearance in the renal uptake method by optimizing the conditions of renal depth, background, threshold for renal boundary determination, and time interval for integrating renal counts. MethodsDynamic renal imaging was performed in 232 patients with dual energy window acquisition (main, 140±14 keV; sub, 122.5±3.5 keV). For drawing renal regions of interest (ROIs), cut-off methods with 50% and 70% of the highest renal pixel counts were used. For drawing the backgrounds, circumferential and lateral-inferior quadrant peri-renal ROIs were used. For setting the time interval, periods of 1–2, 1–2.5, 1.5–2.5, 1.5–3 and 2–3 min post-injection were used. For determining renal depth, three methods of a theoretical exponential function using scatter fraction, Tønnesens formula, and linear combination of scatter fraction and Tønnesens formula were used. The scatter fraction was calculated using the counts in renal ROIs in the two energy windows. Using every combination of these conditions, renal uptake was calculated. As a reference, one-sample clearance was calculated from a blood sample taken at 30 min post-injection following Bubecks formula. According to the methods for estimating renal depth, three non-linear regression models were derived to convert renal uptake to clearance. Using one-sample clearance and integrated renal counts as dependent and independent variables, data were fitted to the models to determine the necessary constants. The correlations between the model estimated clearances and one-sample clearance were investigated. ResultsOne-sample clearance ranged from 11 to 404 ml·min−1 per 1.73 m2. More than half of the regression using renal depth determined by the scatter fraction alone failed to converge. Among the successfully converged regressions, all model estimated clearances showed significant correlations (P<0.01) with one-sample clearance. The best correlation was observed in the model using renal depth determined by the combination of scatter fraction and Tønnesens formulas, renal ROIs by 50% cut-off, lateral-inferior background and time interval of 2–3 min (r=0.898, P<0.001). ConclusionThe renal uptake method for estimating the clearance of mercaptoacetyltriglycine can be improved by the processing conditions proposed here.

Correct localization of epileptogenic focus with I-123 iomazenil cerebral benzodiazepine receptor imaging: a case report of temporal lobe epilepsy with discordant ictal cerebral blood flow SPECT

A 26-year-old female with intractable epileptic seizures was studied with 1-123 iomazenil cerebral benzodiazepine receptor, 1-123 IMP inter-ictal and Tc-99m ECD ictal cerebral blood flow SPECT. The ictal cerebral blood flow SPECT indicated the location of the seizures to be in the left temporal lobe, where increased regional cerebral blood flow was noted in marked contrast to the inter-ictal SPECT. Ictal electroencephalograms (EEGs) recorded with scalp and sphenoidal electrodes also suggested the left temporal lobe as the location of the seizures. On 1-123 iomazenil SPECT, however, decreased benzodiazepine receptor density was demonstrated in the right temporal lobe. MRI showed mild atrophy and abnormal signal intensity in the right temporal lobe. Ictal EEGs recorded with intracranial electrodes revealed that abnormal electrical activity of the brain always emerged from the right temporal lobe and then propagated to the contralateral side. Based on the findings of intracranial EEGs, partial resection of the right anterior temporal lobe including hippocampus was performed. After the surgery, no seizure occurred. Pathological examination of the surgical specimens revealed hippocampal sclerosis. This case suggested that cerebral benzodiazepine receptor imaging with 1–123 iomazenil can be helpful for correct localization of epileptogenic foci.