Hidenobu Nakajo

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.

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.

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.

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.

Assessment of contractile response to dobutamine stress by means of ECG-gated myocardial SPECT: Comparison with myocardial perfusion and fatty acid metabolism

The present study assessed left ventricular performance during dobutamine stress measured using gated SPECT, and compared the results to myocardial perfusion and fatty acid metabolism.MethodsThirty-six patients with myocardial infarction given99mTc-sestamibi or99mTc-tetrofosmin were examined by gated SPECT at rest and during dobutamine stress (4-20 µg • kg-1 • min-1). After acquiring data at the highest dose,201T1C1 was injected and dual-isotope SPECT was performed to assess myocardial ischemia. Thirty of 36 patients also underwent myocardial SPECT with123I-BMIPP. Regional wall motion changes during dobutamine infusion were determined from the gated SPECT data and classified as: (1) Improvement, (2) Worsening, (3) No change, and (4) Biphasic response. For myocardial segments of each infarct area, stress201Tl, rest99mTc and123I-BMIPP uptakes were graded on a five-point scoring system of defects from 0 (normal) to 4 (grossly defective).ResultsRest99mTc defect score index (DSI) in No change area was significantly higher than that in Biphasic area. The ΔDSI (stress201T1 – rest99mTc) in Biphasic area was significantly higher than those in Improvement and No change areas. The ΔDSI (BMIPP –99mTc) in Worsening area tended to be higher than that in No Change area.ConclusionsRegional contractile response to dobutamine stress analyzed by gated SPECT showed that the response in-myocardial infarct areas could be classified by rest and stress myocardial perfusion and BMIPP accumulation.

Serial assessment of left ventricular performance at rest and during bicycle exercise by ECG-gated myocardial perfusion SPECT.

The present study evaluates left ventricular performance during exercise by ECG-gated myocardial perfusion SPECT with short-time data collection. Methods: The study population consisted of 10 healthy volunteers (Group N) and 9 patients with ischemic heart disease (Group I). Seven patients in Group I had a history of prior myocardial infarction. Rest ECG-gated SPECT was performed 40 min after an injection of Tc-99m-tetrofosmin (555–740 MBq). After resting data acquisition, Group N underwent up to two 5-min stages of exercise (75 and 125 watts) on a detachable bicycle ergometer. The Group I patients all underwent symptom-limited, maximal testing on the ergometer. ECG-gated SPECT data were acquired from both groups for 3 min at rest and during the last 3 min of each exercise stage. Results: Significant increases occurred in LVEF from rest to peak stress in both groups (from 55.4±5.8 to 66.6±4.1% in group N, p<0.0001; from 49.0±12.8 to 56.7±13.8% in Group I, p<0.001). The LVESV values significantly decreased to peak stress in Group N (from 49.9±13.1 to 37.8±10.0 ml, p<0.0001), whereas LVEDV did not change (from 110.6±18.9 to 112.0±19.0 ml). In contrast, the LVESV values at rest and under peak stress were similar in Group I (from 52.6±23.9 to 51.7±31.4 ml) and LVEDV in Group I at peak exercise tended to increase (from 102.8±36.7 to 111.3±39.0 ml). The changes in LVESV from rest to peak stress were significantly different between Groups N and I (−12.1±6.3 vs.−0.9±11.6 ml, p<0.02). Conclusion: ECG-gated SPECT with short-time data collection can assess left ventricular function during exercise and may offer useful information for evaluating patients with ischemic heart disease.

Regional cerebral blood flow and vascular reserve in neuronal migration disorder assessed by Tc-99m hexamethylpropylene amineoxime SPECT with acetazolamide challenge

A 20-month-old boy had left hemiparesis and mental retardation. Magnetic resonance imaging revealed agyria-pachygyria in the right cerebral hemisphere, but magnetic resonance angiography showed no arterial stenosis or hypoplasia. Resting SPECT showed reduced Tc-99m hexamethylpropylene amineoxime accumulation in the affected cortex compared with the contralateral unaffected cortex, but during acetazolamide administration accumulation in the affected cortex was similar to that in the unaffected cortex. These findings suggest that the vasodilator function of the affected cortex was intact. This supports the contention that the low accumulation of cerebral blood flow tracer in migration disorder does not reflect impaired cerebral blood supply but rather reduced tissue activity.