Keiichi Cho

Development of quantitative analysis method for stereotactic brain image : Assessment of reduced accumulation in extent and severity using anatomical segmentation

Through visual assessment by three-dimensional (3D) brain image analysis methods using stereotactic brain coordinates system, such as three-dimensional stereotactic surface projections and statistical parametric mapping, it is difficult to quantitatively assess anatomical information and the range of extent of an abnormal region. In this study, we devised a method to quantitatively assess local abnormal findings by segmenting a brain map according to anatomical structure. Through quantitative local abnormality assessment using this method, we studied the characteristics of distribution of reduced blood flow in cases with dementia of the Alzheimer type (DAT). Using twenty-five cases with DAT (mean age, 68.9 years old), all of whom were diagnosed as probable Alzheimers disease based on NINCDS-ADRDA, we collected I-123 iodoamphetamine SPECT data. A 3D brain map using the 3D-SSP program was compared with the data of 20 cases in the control group, who age-matched the subject cases. To study local abnormalities on the 3D images, we divided the whole brain into 24 segments based on anatomical classification. We assessed the extent of an abnormal region in each segment (rate of the coordinates with a Z-value that exceeds the threshold value, in all coordinates within a segment), and severity (average Z-value of the coordinates with a Z-value that exceeds the threshold value). This method clarified orientation and expansion of reduced accumulation, through classifying stereotactic brain coordinates according to the anatomical structure. This method was considered useful for quantitatively grasping distribution abnormalities in the brain and changes in abnormality distribution.

Three-dimensional display in staging hemodynamic brain ischemia for JET study : Objective evaluation using SEE analysis and 3D-SSP display

The Japanese EC-IC bypass trial (JET study) was established to evaluate the validity of MCA-STA anastomosis in intracranial arterial occlusive disease aiming at stroke prevention. This study must use an objective method to reliably estimate hemodynamic brain ischemia. We devised a method of objectively classifying the severity of hemodynamic ischemia using quantitatively analytical and display software, stereotactic extraction estimation for stereotactic brain coordinates and three-dimensional stereotactic surface projections (3D-SSP). We analyzed data from 16 patients registered in the JET study. Our method offers quantitative information and 3-dimensional displays of the CBF at rest and after Diamox challenge, vascular reserve and the severity of the hemodynamic brain ischemia. We compared the maximal projection counts with ROI data from tomographic images in the anterior commissure-posterior commissure plane. The maximal counts data correlated closely with the ROI data of rest and with Diamox SPECT images (both p < 0.0001). The slopes of the linear regression line were 1.15 and 1.12, respectively. The results of this study indicated that our method could simply and objectively evaluate the severity of impaired brain circulation. This procedure should support the evaluation of hemodynamic ischemia in the JET study although validation is required by several institutions using more study subjects.

Development of respiratory gated myocardial SPECT system

BackgroundThe superposition of the diaphragm and abdominal structures on the inferior wall of the left ventricle has often distorted single photon emission computed tomography (SPECT). We developed a respiratory gated SPECT (RGS) system to diminish artifacts caused by overlap between the inferior wall and upper abdomen and have validated its feasibility for clinical use.Methods and ResultsA 2-detector SPECT system equipped with a respiratory monitor based on impedance plethysmography and an original triggering apparatus was used for RGS in 7 healthy male volunteers. A pulse triggered 100 ms after every expiratory peak was processed in a SPECT system as well as an electrocardiogram (ECG) gating pulse. Inspiratory and expiratory frames were determined using the respiratory curve derived from fluctuation of the gall bladder uptake. Both sets of images were reoriented into short-axis and vertical long-axis slices. For quantification, data were reconstructed into polar plots and count density estimated in 9 myocardial segments. The mean percentage uptake of inferior segments at inspiration was significantly greater than that at expiration (81±8.3 versus 76±7.1; P<.0001). The inferior-lateral activity ratio improved from 0.78 at expiration to 0.81 at inspiration (P<.01). The coefficient of variance for each segment of inspiratory data was significantly smaller than that at expiration, indicating improved homogeneity of tracer distribution. The lowest cutoff threshold of the tomograms to separate the inferior uptake from that of the upper abdomen was significantly lower at inspiration than at expiration, suggesting smaller scatter from abdominal structures on inspiratory images.ConclusionsRGS yielded improved tracer uptake of the inferior wall in healthy male subjects and may be suitable as an alternative method for attenuation and scatter correction. However, further clinical validation is needed.

Simultaneous assessment of Tc-99m-sestamibi and I-123-BMIPP myocardial distribution in patients with myocardial infarction: evaluation of left ventricular function with ECG-gated myocardial SPECT.

Abstract123I-labeled 15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid (BMIPP) is a branched-chain free fatty acid that is used to evaluate various cardiac diseases. The aim of the present study was to investigate the relationship between myocardial perfusion (99mTc-sestamibi) and BMIPP uptake, and to correlate perfusion and metabolic alterations with regional left ventricular dysfunction in patients with myocardial infarction (MI). ECG-gated dual-isotope myocardial SPECT was performed on 130 patients with MI with sestamibi (555 MBq) and BMIPP (148 MBq). The patients were classified into 3 groups according to PTCA therapy and the interval between the onset of infarction and RI injection (OR time). Group A (n-56) included patients whose OR time was less than one month and who had undergone successful PTCA, Group B (n=36) had OR times of less than one month and had conservative medical therapy, and Group C (n=38) had OR times of over one month. The severity scores of the dual-isotope images were calculated from the defect scores in 9 segments. From the ECG-gated SPECT data with sestamibi, the left ventricular ejection fraction (LVEF; %) and regional wall motion were determined automatically using the QGS programTM. LVEF obtained from gated SPECT correlated well with the severity scores for sestamibi and BMIPP (r=−0.68 and −0.76, respectively). The Δ severity scores (BMIPP scores — sestamibi scores) of Group A were significantly higher than those of the other two groups (3.6±3.0 vs. 1.5±1.7 and 1.0±1.4, p<0.001). The rate of dysfunctional segments with normal sestamibi distribution was significantly higher in Group A than in Group C (20.7% vs. 6.7%, p<0.001). ECG-gated dual-isotope SPECT is useful since myocardial perfusion, fatty acid metabolism and left ventricular function can be analyzed during a single examination, so that this procedure has the potential to provide comprehensive information when evaluating patients with ischemic heart disease.

Assessment of myocardial washout of Tc-99m-sestamibi in patients with chronic heart failure: Comparison with normal control

BackgroundIn contrast to201T1C1,99mTc-sestamibi shows very slow myocardial clearance after its initial myocardial uptake. In the present study, myocardial washout of99mTc-sestamibi was calculated in patients with non-ischemic chronic heart failure (CHF) and compared with biventricular parameters obtained from first-pass and ECG-gated myocardial perfusion SPECT data.Methods and ResultsAfter administration of99mTc-sestamibi, 25 patients with CHF and 8 normal controls (NC) were examined by ECG-gated myocardial perfusion SPECT and planar data acquisition in the early and delayed (interval of 3 hours) phase. Left ventricular ejection fraction (LVEF, %), peak filling rate (PFR, sec−1), end-diastolic volume (LVEDV, ml) and end-systolic volume (LVESV, ml) were automatically calculated from the ECG-gated SPECT data. Myocardial washout rates over 3 hours were calculated from the early and delayed planar images. Myocardial washout rates in the CHF group (39.6±5.2%) were significantly higher than those in the NC group (31.2±5.5%, p<0.01). The myocardial washout rates for the 33 subjects showed significant correlations with LVEF (r=−0.61, p<0.001), PFR (r=−0.47, p<0.01), LVEDV (r=0.45, p<0.01) and LVESV (r=48, p<0.01),Conclusion: The myocardial washout rate of99mTc-sestamibi is considered to be a novel marker for the diagnosis of myocardial damage in patients with chronic heart failure.

Comparison of emory and cedars-sinai methods for assessment of left ventricular function from gated myocardial perfusion SPECT in patients with a small heart

To evaluate the effect of left ventricular (LV) size on the calculation of LV function from gated myocardial SPECT with Emory and Cedars-Sinai programs, we performed99mTc-tetrofosmin gated SPECT on 49 patients with ischemic heart disease. End-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) were semi-automatically calculated by each program. All patients underwent left ventriculography (LVG) within 3 months before and after the SPECT study. We grouped the patients into 22 with a calculated ESV obtained from LVG of over 50 ml (group A) and 27 with an ESV value of 50 ml or below (group B). We then compared the ESV values from gated SPECT with those from LVG in each group. In group A, the ESV from both Emory and Cedars-Sinai programs similarly correlated well with those from LVG (r=0.92 and r=0.93, respectively), but in group B, the ESV calculated from the Cedars-Sinai program correlated less with those from LVG (r=0.53) than those from the Emory program did (r=0.70). The calculated LV volumes had more errors in the Cedars-Sinai program than in the Emory program, when a patient had a small heart.

Three-dimensional registration of myocardial perfusion SPECT and CT coronary angiography

ObjectiveIn this study, we describe a new technique for three-dimensional registration of CT coronary angiography (CTCA) and gated myocardial perfusion SPECT.MethodsTwelve patients with known or suspected CAD who underwent CTCA and gated SPECT were enrolled retrospectively. Coronary arteries and their branches were traced using CTCA data manually and reconstructed in three-dimensions. Gated SPECT data were registered and mapped to a left ventricle binary model extracted from CTCA data using manual, rigid and nonrigid registration methods.ResultsThree-dimensional reconstruction and volume visualization of both modalities were successfully achieved for all patients. All 3 registration methods gave better quality based on visual inspection, and nonrigid registration gave significantly better results than the other registration methods (p < 0.05). The cost function for three-dimensional registration using nonrigid registration (235.3 ± 13.9) was significantly better than those of manual and rigid registration (218.5 ± 15.3 and 223.7 ± 17.0, respectively). Inter-observer reproducibility error was within acceptable limits for all methods, and there were no significant difference among the methods.ConclusionThis technique of image registration may assist the integration of information from gated SPECT and CTCA, and may have clinical application for the diagnosis of ischemic heart disease.

Examination of intra‐gastrointestinal tract signal elimination in MRCP: Combined use of T1‐shortening positive contrast agent and single‐shot fast inversion recovery

To examine the effects of removing the gastrointestinal signal in MR cholangiopancreatography (MRCP), investigations were carried out on the combined use of T1‐shortening intestine‐positive contrast medium, FerriSeltz with ferric ammonium citrate as the main component, and high‐speed imaging using single‐shot fast inversion recovery (SSFIR). The contrast effect was significantly elevated to 10.2 ± 1.6 after administration, compared with 5.9 ± 2.4 before administration (P < 0.001). The enhancement effect was also significantly elevated to 13.2 ± 3.0 after administration, compared with 4.9 ± 3.1 before administration (P < 0.001). These results were obtained because the null point of FerriSeltz aqueous solution (5.97 mmol/L) was in the range of approximately 180 msec. With the present method, adequate suppression of the signal intensity of the digestive tract was obtained relatively easily with MRCP, and the technique was found to be effective. J. Magn. Reson. Imaging 2001;13:738–743.

Rapid data acquisition protocol in ECG-gated myocardial perfusion SPECT with Tc-99m-tetrofosmin

Into 25 patients with heart disorders,99mTc-tetrofosmin 555–740 MBq was injected intravenously at rest. After 40 minutes, ECG-gated myocardial perfusion SPECT was performed with a two detector gamma camera VERTEX (ADAC), setting up two detectors to form a 90-degree angle. Sixteen frames per R-R interval were acquired during a 180° rotation from the RAO 45° to the LPO 45°. A pair of data sets with standard (SDA) and rapid data acquisition (RDA) protocols was collected. In an SDA protocol, SPECT imaging was performed for 50 sec per step in 5° angular steps (total acquisition time; 15 minutes). An RDA protocol was conducted with 12 sec per step, 6° angular steps (acquisition time, 3 minutes). LVEF (%) and LVEDVml quantitated automatically with a QGS program showed excellent correlations between two protocols with correlation coefficients of 0.980 (p < 0.01) and 0.983 (p < 0.01), respectively. Subsequently visual assessment of regional wall motion based on a four-point grading system was carried out with a 3-D cine LV display. High complete agreement was gained with 158 (90.3%) out of total 175 segments, so that assessment of the global and regional LV function with the RDA protocol demonstrated high reliability and feasibility.

Assessment of left ventricular function using solid-state gamma camera equipped with a highly-sensitive collimator

Purpose: The solid-state gamma camera 2020tc ImagerTM (Digirad, CA) is now commercially available and has been clinically applied. The present study evaluates the feasibility of equilibrium radionuclide ventriculography (ERNV) within a 3 min period using this camera equipped with a highly sensitive collimator.Materials and Methods: ERNV was performed from the best septal position (left anterior oblique view) in 20 patients with cardiac disease using a single detector angertype gamma camera equipped with a low-energy, high-resolution collimator. Immediately thereafter, we performed a second ERNV using the solid-state gamma camera equipped with a highly sensitive collimator. Acquisition periods were 10 and 3 min, respectively.Results: Significantly more counts were collected from over the left ventricle with the solid-state gamma camera over 3 min than those with the anger-type gamma camera over 10 min (817.1±387.8 k counts vs. 668.2±327.4 k counts, p<0.01). The left ventricular ejection fraction obtained from ERNV data using the solid-state gamma camera correlated closely with those acquired by the anger-type gamma camera (r=0.94, p<0.0001, SEE=5.93%).Conclusion: The results showed that the solid-state gamma camera could assess left ventricular function with excellent data collection efficiency and high reliability.